KR19990007253A - Optical reproducing apparatus and optical recording medium - Google Patents

Abstract

The optical reproducing apparatus of the present invention detects the average amplitude values of the short mark and the long mark which are recording marks for controlling reproduction power recorded on the magneto-optical disk by the mark level detection circuit and the long mark level detection circuit respectively. Then, the differential amplifier outputs the result of comparison between the ratio of these two average values and the target value. Thereafter, the reproduction power control circuit controls the reproducing power of the semiconductor laser so that the absolute value of the comparison result becomes small. The average amplitude value of the short mark and the long mark is detected. Therefore, the detection result is very accurate, and the accuracy in controlling the reproduction power can be made very high.

Description

Optical reproducing apparatus and optical recording medium

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reproducing device and an optical memory medium and, more particularly, to an optical reproducing device and an optical recording medium which control an amount of light of a light beam such that the amount of reproduction signals from a recording mark in an optical recording medium is close to a predetermined value An optical reproducing apparatus and an optical recording medium reproduced by the optical reproducing apparatus.

In a magneto-optical disk apparatus of a magnetic ultra high resolution method, a magneto-optical disk having a recording layer and a reproducing layer having in-plane magnetization is used. In such a magneto-optical disk device, a light beam is irradiated to the reproduction layer side of the magneto-optical disk at the time of reproduction. Then, in the reproducing layer, a part of the area irradiated with the light beam is above a predetermined temperature, and the magnetization of this part (detection aperture) shifts from the in-plane magnetization to the perpendicular magnetization to which the magnetization of the corresponding recording layer is transferred . As described above, in this magneto-optical disk device, by reproducing the magnetization of the detection port, a recording mark smaller than the spot diameter of the light beam can be reproduced.

In a magneto-optical disk device employing this magnetic super-resolution method, it is preferable that the power (reproducing power) of the light beam at the time of reproduction is always optimum. However, the optimum value of the regenerating power may fluctuate depending on the change of the environmental temperature during the regeneration. Therefore, there is a case where the reproduction power deviates from the optimum value even if the current (driving current) for driving the configuration for generating the light beam is kept constant.

If the reproduction power is excessively stronger than the optimal value, the detection aperture formed on the magneto-optical disk becomes excessively large. As a result, the output (crosstalk) of the reproduction signal from the track adjacent to the reproduction-related track increases and the ratio of the noise signal included in the reproduced data increases, thereby increasing the probability of occurrence of a reading error.

On the other hand, if the reproduction power is excessively weaker than the optimum value, the detection aperture becomes smaller than the recording mark, and the output of the reproduction signal from the track to be read is also reduced. Therefore, in this case as well, the probability of occurrence of the read error increases.

Thus, in the recording / reproducing apparatus disclosed in Japanese Patent Application Laid-Open No. 8-63817 (US Pat. No. 5,617,400), a long mark and a short mark formed on the magneto-optical disk are reproduced . These long marks and short marks are two types of recording marks for reproduction power control having different mark lengths. In this apparatus, the reproduction power is controlled so that the ratio of the reproduction signal amount from these recording marks is close to a predetermined value. Accordingly, in this apparatus, the reproduction power is always kept at the optimum value, thereby reducing the probability of occurrence of a reading error.

Fig. 30 is an explanatory diagram showing the outline of the configuration of this apparatus. In this apparatus, the light beam emitted from the semiconductor laser 108 is irradiated to the magneto-optical disk 112. [ The reflected light from the reproduction power control mark consisting of a long mark and a single mark is converted into a reproduction signal by the photodiode 113 and input to an A / D (Analog / Digital) converter 115 and a clock generation circuit 114 . The clock generation circuit 114 generates a clock signal synchronized with the reproduction signal input by a PLL (Phase Locked Loop) control method and outputs the clock signal to an A / D (Analog / Digital)

Then, the A / D converter 115 converts the reproduction signal into a digital signal based on the clock signal, and outputs the digital signal to the amplitude ratio detection circuit 116. The amplitude ratio detection circuit 116 extracts only the digital signals corresponding to the upper and lower peak points in the reproduction signal among the digital signals inputted for each clock signal. Then, the amplitude ratio detection circuit 116 obtains the values of the upper and lower peak points based on the extracted digital signal, and obtains amplitude values of the long mark and the short mark. Then, the ratio (amplitude ratio) of these amplitude values is obtained and output to the differential amplifier 110. This amplitude ratio is dependent on the size of the detection aperture in the reproduction layer.

The differential amplifier 110 compares the amplitude ratio with a predetermined target value and outputs the comparison result to the reproduction power control circuit 111. [ Then, the reproduction power control circuit 111 controls the drive current supplied to the semiconductor laser 108 so that the feedback is applied in the direction in which the difference between the amplitude ratio and the target value becomes smaller.

Thus, in this recording / reproducing apparatus, the driving current supplied to the semiconductor laser 108 is controlled such that the optical beam is irradiated to the magneto-optical disk at the optimum reproducing power at all times.

However, in this recording / reproducing apparatus, the amplitude value of the reproduction power control recording mark is obtained from the value of one upper peak point and the value of one lower peak point. Because of this, the amplitude ratio calculated from these amplitude values can not be a sufficiently accurate value, so that the control of reproduction power in this recording / reproducing apparatus includes a large error.

In addition, a PRML (Partial Response Maximum Likelihood) demodulation method has been proposed as a method for reducing the occurrence rate of read errors of data recorded at high density. This PRML demodulation scheme is a demodulation scheme that performs partial response equalization to a reproduction signal and performs optimal decoding (maximum likelihood decoding (ML decoding) by Viterbi decoding.

A reproducing apparatus using this demodulation system is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-243598. In this apparatus, a reproduction signal from an optical disk is equalized to PR (1, 2, 1) characteristics and decoded into data most likely to be obtained by Viterbi decoding. 31 is an explanatory diagram showing a schematic configuration of this apparatus.

In reproduction in this apparatus, the optical head 121 reads data recorded on the optical disk 120 and outputs an analog signal according to the data. Then, an analog / digital (A / D) converter 123 converts the analog signal into a digital signal and outputs it. The digital signal output from the A / D converter 123 is input to the PRML demodulation circuit 126.

The PRML demodulation circuit 126 includes a PR equalizer 124 and a Viterbi decoder 125. [ Then, the input digital signal is equalized to the PR (1, 2, 1) characteristic by the PR equalizer 124, and then is Viterbi-decoded by the Viterbi decoder 125 and output as binary data.

The analog signal output from the optical head 121 is also input to the clock extraction unit 122. [ The clock extracting unit 122 generates a clock signal having a bit period synchronized with the phase of the analog signal, and inputs the clock signal to the A / D converter 123. The A / D converter 123 converts the analog signal into a digital signal in accordance with the timing of the clock signal.

However, this playback apparatus has the following problems. That is, in this reproducing apparatus, a preferable sampling timing for reproduction of data and a reproduction power control record (which is determined by a combination of a modulation scheme of data recorded on the optical disc 120 and a demodulation scheme of the PRML demodulation circuit 126) There is a possibility that the preferable sampling timings do not match in order to accurately detect the reproduction signal amount of the mark.

(1, 7) RLL (Run Length Limited) modulation scheme is adopted as the modulation scheme and the PR (1, 2, 1) ML demodulation scheme is adopted as the demodulation scheme in the PRML demodulation circuit 126 Consider a case where regenerative power control is performed by the configuration.

32 shows A / D conversion (sampling) timing suitable for the PR (1, 2, 1) ML demodulation method of the reproduction signal obtained by reproducing a pattern in which the shortest mark (mark length 2Tc) Fig. As shown in this figure, in the sampling suitable for the PR (1, 2, 1) ML demodulation system, the shoulder portion of the reproduction signal is sampled.

On the other hand, the mark length of the short mark used for regenerative power control is usually 2Tc. It is preferable that the upper and lower peak points of the reproduction signal obtained in this reproduction of the end mark are sampled.

However, as shown in Fig. 32, in the sampling in this configuration, the shoulder portion of the reproduction signal according to the recording mark having the mark length of 2Tc is sampled. Therefore, it is not preferable to use the reproduction signal amount obtained by this sampling for reproduction power control.

As described above, in this configuration, there is a problem that it is difficult to control the reproduction power if A / D conversion is performed at a timing suitable for the PR (1, 2, 1) ML demodulation system.

In this example, the combination of the PR (1, 2, 1) ML demodulation and the (1, 7) RLL modulation scheme is considered, but for example, the PR (1,1) ML demodulation scheme and the Eight to Fourteen Modulation There is a preferable sampling timing according to this combination even in the data reproduced by the combination of modulation schemes.

As described above, in the conventional configuration, when the timing of the optimum sampling for the reproduction of the data determined by the combination of the PRML demodulation system and the modulation system and the timing of the optimum sampling for the control of the reproduction power do not coincide with each other, There was a problem that it was difficult.

SUMMARY OF THE INVENTION A first object of the present invention is to provide an optical reproducing apparatus capable of precisely calculating the amount of a reproduction signal obtained from an optical recording medium and accurately controlling reproduction power based on the amplitude value.

A second object of the present invention is to provide an optical reproducing apparatus capable of controlling reproduction power and reproducing digital data by using an optimum clock signal.

In order to achieve the first object, an optical reproducing apparatus of the present invention is an optical reproducing apparatus for irradiating a light beam onto an optical recording medium and for generating a reproduction signal in accordance with a recording mark recorded on the optical recording medium, A control signal output unit for detecting an average value of a signal amount in a reproduction signal generated by the reproduction signal generating unit and generating a first control signal according to the average value; And a reproduction power control section for controlling the reproduction power of the light beam irradiated by the reproduction signal generation section so that the signal amount in the reproduction signal becomes a predetermined value based on the signal.

The reproduction signal generator in the above-described configuration irradiates the optical recording medium with a light beam and generates a reproduction signal in accordance with the recording mark recorded on the optical recording medium. The amount of the reproduction signal depends on the reproduction power of the light beam irradiated on the optical recording medium.

Then, the control signal output section calculates an average value in the amplitude value of the reproduction signal, and generates a first control signal based on the average value. The first control signal is generated based on the average value of the amplitude values, and therefore, it corresponds to the amount of the reproduction signal from the optical recording medium.

Then, the reproduction power control section controls the reproduction power of the light beam irradiated to the optical recording medium by the reproduction signal generating section based on the first control signal. That is, the reproduction power control section determines the amount of the current reproduction signal from the first control signal. Then, the reproducing signal generator controls the reproduction power of the light beam irradiated to the optical recording medium so that the amount of the reproduction signal becomes a predetermined value.

Thus, in the above-described configuration, it is possible to always maintain the reproduction power capable of generating the reproduction signal of the predetermined signal amount. As a result, read errors such as crosstalk can be reduced and stable reproduction can be performed.

Further, according to the above configuration, the control signal output section detects the average value of the reproduction signal amount and generates the first control signal based on the average value. Therefore, the first control signal reflects the value of the actual reproduction signal amount very accurately. Therefore, the reproducing power control section is able to control the reproducing power of the reproducing signal generating section with high accuracy.

In addition, the predetermined signal amount is, for example, the optimum signal amount for reproduction by the optical reproducing apparatus. The signal amount is, for example, the amplitude value of the reproduction signal.

In order to achieve the second object, an optical reproducing apparatus of the present invention irradiates a light beam onto an optical recording medium and generates a reproduction signal according to a recording mark recorded on the optical recording medium, based on the reflected light of the light beam A reproduction signal generating unit for generating a reproduction signal based on the reproduction signal, a digital signal output unit for outputting a digital signal according to the reproduction signal, a demodulation unit for demodulating the digital signal, Wherein the digital signal output unit includes a clock signal output unit for outputting a clock signal according to a modulation scheme of the recording mark, a demodulation scheme in the demodulation unit, and a control scheme in the reproduction power control unit, A digital signal for sampling a reproduction signal based on the clock signal outputted by the signal output unit and generating a digital signal And a generating unit.

The reproduction signal generator in the above-described configuration irradiates the optical recording medium with a light beam to generate a reproduction signal in accordance with the recording mark recorded on the optical recording medium.

The digital signal output section has a clock signal output section for generating a clock signal based on the reproduction signal. The clock signal is based on the modulation scheme of the recording mark, the demodulation scheme of the demodulation unit, and the control scheme of the reproduction power control unit. Then, based on the clock signal, the digital signal generation unit generates a digital signal corresponding to the reproduction signal.

In general, the sampling timing for generating a digital signal suitable for demodulation by the demodulation unit is determined by the modulation scheme of the recording mark and the demodulation scheme of the demodulation unit. The timing of sampling for generating a digital signal suitable for controlling the reproduction power is determined by the modulation scheme of the recording mark and the control scheme of the reproduction power control section. Further, the timing of the sampling is determined by the clock signal.

Thus, the clock signal output unit is configured to generate a clock signal capable of generating the two digital signals by considering the modulation method, the demodulation method, and the control method. The clock signal may be, for example, two different clock signals or one clock signal capable of generating the two digital signals.

The digital signal generation unit generates a digital signal for outputting to the demodulation unit and a digital signal for outputting to the reproduction power control unit based on the clock signal output from the clock signal output unit and outputs the generated digital signal to the demodulation unit and the reproduction power control unit .

Therefore, even if the timing of sampling for generating a digital signal for demodulation and the timing of sampling for generating an optimum digital signal are different from each other in control of reproduction power, Demodulation can be performed.

Other objects, features and advantages of the present invention will become more apparent from the following description. Further, advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a configuration of a magnetic super-resolution type optical reproducing apparatus according to a first embodiment of the present invention; FIG.

Fig. 2 is an explanatory view showing a configuration of a magneto-optical disc reproduced by the optical reproducing apparatus shown in Fig. 1; Fig.

FIG. 3 is an explanatory view showing a structure of a sector formed on the magneto-optical disk shown in FIG. 2;

FIG. 4 is an explanatory view showing an end mark and a long mark formed on the magneto-optical disk shown in FIG. 2;

5 is an explanatory view showing a configuration of an end mark level detection circuit in the optical reproducing apparatus shown in Fig.

Fig. 6 is an explanatory view showing a structure of a shift register in the short mark level detection circuit shown in Fig. 5; Fig.

7 is an explanatory view showing a configuration of a long mark level detecting circuit in the optical reproducing apparatus shown in Fig.

8 is an explanatory view showing a structure of a shift register in the long mark level detection circuit shown in Fig.

FIG. 9 is an explanatory view showing sampling by an A / D converter of an analog reproduction signal obtained from an end mark recording area in the magneto-optical disk shown in FIG. 2;

FIG. 10 is an explanatory view showing sampling by an A / D converter for an analog reproduction signal obtained from a chapter mark recording area on the magneto-optical disk shown in FIG. 2;

11 is a graph showing the results of measurement of the relationship between the number of averaging bytes of the short mark and long mark in the magneto-optical disk shown in FIG. 4 and the accuracy of the average amplitude ratio detected by the optical reproducing apparatus shown in FIG.

12 is a graph showing the relationship between the reproducing power of the semiconductor laser in the optical reproducing apparatus shown in Fig. 1 and the BER of the binarization data obtained from the data reproducing circuit and the relationship between the average reproducing ratios and the average amplitude ratios calculated by the dividers A graph showing one result.

13 shows the results of measuring the relationship between the number of averaging bytes of the short marks and long marks in the magneto-optical disk in which the modulation method is the NRZI modulation method and the accuracy of the average amplitude ratio detected by the optical reproducing apparatus shown in Fig. 1 graph.

14 is a graph showing the relation between the reproduction power of the semiconductor laser in the case where the optical recording medium of the NRZI modulation scheme is reproduced by the optical reproducing apparatus shown in FIG. 1 and the BER of the binary data obtained from the data reproducing circuit, A graph showing the results of measuring the relationship between the same rewrite power and the average amplitude ratio calculated by the divider.

FIG. 15 is an explanatory view showing sampling marks recorded by the (1, 7) RLL modulation method and analog playback signals according to these recording marks; FIG.

16 is an explanatory view showing sampling of a chapter mark recorded by the (1, 7) RLL modulation method and an analog reproduction signal according to these chapter marks;

17 is an explanatory view showing sampling marks recorded by the NRZI modulation method and analog playback signals according to these recording marks;

18 is an explanatory view showing sampling of a chapter mark recorded by the NRZI modulation method and an analog reproduction signal according to the chapter mark;

19 is an explanatory view showing a configuration of an optical reproducing apparatus according to a second embodiment of the present invention;

Fig. 20 is an explanatory view showing a configuration of a magneto-optical disc reproduced by the optical reproducing apparatus shown in Fig. 19; Fig.

Fig. 21 is an explanatory view showing a structure of a sector formed on the magneto-optical disk shown in Fig. 20; Fig.

Fig. 22 is an explanatory view showing an end mark and a long mark formed on the magneto-optical disk shown in Fig. 20;

23 is an explanatory diagram showing a clock signal generated by the first clock generating circuit and the second clock generating circuit in the optical reproducing apparatus shown in Fig.

24 is an explanatory view showing the relationship between the clock signal and an analog playback signal according to the end mark and the chapter mark on which sampling is performed based on the clock signal.

Fig. 25 is an explanatory view showing the sampling of the analog reproduction signal according to the short mark and the analog reproduction signal according to the long mark by the A / D converter in the optical reproducing apparatus shown in Fig.

26 is an explanatory view showing a configuration of an optical reproducing apparatus according to a third embodiment of the present invention;

FIG. 27 is an explanatory diagram for illustrating a clock signal outputted by a doubled clock generation circuit in the optical reproducing apparatus shown in FIG. 26, in comparison with the clock signal shown in FIG.

28 is an explanatory view showing the generation of a digital reproduction signal by the A / D converter in the optical reproduction apparatus shown in Fig. 26 when an analog reproduction signal according to a recording mark having a mark length of 2Tc is inputted;

FIG. 29 is an explanatory view showing the generation of a digital reproduction signal by the A / D converter in the case of reproducing digital data in which recording marks having various mark lengths are randomly formed; FIG.

30 is an explanatory view schematically showing a configuration of a conventional optical reproducing apparatus;

31 is an explanatory view schematically showing a configuration of another conventional optical reproducing apparatus;

32 is a timing chart showing the timing of sampling suitable for the PR (1, 2, 1) ML demodulation method for the reproduction signal obtained by reproducing the pattern in which the recording mark with the mark length of 2Tc is repeated by the optical reproducing apparatus shown in Fig. Fig.

Fig. 33 is an explanatory view showing a waveform of a reproduction signal according to a recording mark having a mark length of 1Tc; Fig.

34 is an explanatory diagram showing a waveform of a reproduction signal according to a pattern in which recording marks having a mark length of 2Tc are repeated;

DESCRIPTION OF THE REFERENCE NUMERALS

1: magneto-optical disk

2: Optical head

4: clock generation circuit

5: A / D converter

6: Short mark level detection circuit

7: chapter mark level detection circuit

8: Data reproducing circuit

9:

14: Error correction circuit

[First Embodiment]

A first embodiment of the present invention will be described below.

Fig. 1 is an explanatory diagram showing the configuration of a magnetic super-resolution type optical reproducing apparatus (hereinafter referred to as a main reproducing apparatus) according to the present embodiment. As shown in this figure, the present reproducing apparatus includes an optical head 2, a clock generating circuit 4, an A / D converter 5, a mark level detecting circuit 6, a long mark level detecting circuit 7, A data reproducing circuit 8, a divider 9, a differential amplifier 10, a reproducing power control circuit 11 and an error correction circuit 14. [ The magneto-optical disk 1 shown in this drawing is an optical recording medium reproduced by the present reproducing apparatus.

First, the configuration of the magneto-optical disk 1 will be described before describing the configuration of the reproducing apparatus. This magneto-optical disk 1 is a (1, 7) RLL (Run Length Limited) modulation system in which various kinds of information are recorded. 2 is an explanatory view showing a configuration of the magneto-optical disc 1. As shown in this figure, in the magneto-optical disk 1, a recording track 21 is formed concentrically. In the recording track 21, a plurality of sectors 22 are formed continuously.

3 is an explanatory view showing a configuration of this sector 22. As shown in Fig. As shown in this figure, in each sector 22, a mark recording area 23, a long mark recording area 24 and a data recording area 25 are formed.

The mark recording area (reproducing power control area) 23 is an area where a mark is formed, which is a recording mark for reproducing power control. The chapter mark recording area (playback power control area: 24) is an area where the same long mark as the recording mark for reproduction power control is formed. The data recording area 25 is an area where information desired by the user is modulated by the (1, 7) RLL modulation method and recorded as digital data.

4A and 4B are explanatory diagrams showing these end marks and long marks. As shown in this figure, a short mark having a mark length of 2Tc (Tc is a channel bit length) is repeatedly formed in the short mark recording area 23 at an inter-mark distance of 2Tc. Likewise, a chapter mark having a mark length of 8Tc is repeatedly formed in the long mark recording area 24 at an inter-mark distance of 8Tc. In the following description, the numbers of the short marks and the long marks formed in the short mark recording area 23 and the long mark recording area 24 are N and M, respectively (N and M are predetermined natural numbers).

Next, each configuration of the reproducing apparatus shown in Fig. 1 will be described.

The optical head 2 is provided with a semiconductor laser 12 and a photodiode 13. The semiconductor laser (reproduction signal generating section, light beam irradiating section) 12 irradiates the recording track 21 in the magneto-optical disc 1 with a predetermined reproducing power. A photodiode (reproduction signal generating section, light receiving section) 13 receives light reflected from each of the areas 23 to 25 of the sector 22 in the recording track 21 and generates an analog reproduction signal based on the light And outputs it.

In the following description, an analog reproduction signal obtained from the magneto-optical disk 1 is referred to as an analog reproduction signal.

The clock generation circuit (control signal output section) 4 generates a clock signal synchronized with the channel bit frequency of the analog reproduction signal input by the PLL (Phase Locked Loop) and outputs the clock signal to the A / D converter 5.

The A / D converter (control signal output unit, amplitude value detector) 5 receives the analog playback signal and the clock signal, samples the analog playback signal based on the clock signal, and outputs the value of the analog playback signal at each sampling point And outputs the digital signal to the mark level detection circuit 6, the long mark level detection circuit or the data reproduction circuit 8. In the following, a digital signal corresponding to each sampling point is referred to as a digital reproduction signal. Sampling of the analog reproduction signal by the A / D converter 5 will be described later.

The mark level detection circuit (control signal output section, average value generation section, first average value calculation section 6) detects the mark level of the single mark recording area 23 based on the digital reproduction signal input from the A / The average value of all the maximum values of the analog reproduction signal obtained from the entire area and the average value of the same minimum value are calculated. The average amplitude value (mark average amplitude value) of the analog reproduction signal obtained from one end mark recording region 23 is calculated based on the obtained two average values.

5 is an explanatory view showing a configuration of the short mark level detection circuit 6; As shown in this figure, the mark level detection circuit 6 includes a shift register 31, an adder 32 · 33, a divider 34 · 35 and a subtracter 36.

The shift register 31 is a 4N-stage shift register. Fig. 6 is an explanatory diagram showing the configuration of the shift register 31. Fig. As shown in this figure, the shift register 31 has 4N cells composed of cells ds ₀ to ds _{4 (N-1) +3} . Then, the shift register 31 has a clock generation circuit 4 that each clock signal, and outputting an A / D converter 5, a single mark recording area 23 is the value of the digital reproduction signal the cells obtained from ds input from ₀ to ds _{4 (N-1) +3} .

The adder 32 and 33 add the value of the digital reproduction signal stored in the predetermined cell in the shift register 31 and output it. The divider 34 · 35 divides the added value output from the adder 32 · 33 by N and outputs the obtained divided value to the subtracter 36. The subtracter 36 subtracts the division value output from the divider 35 from the division value output from the divider 34 and outputs the result to the divider 9 shown in Fig.

The calculation of the end mark average amplitude value by the end mark level detection circuit 6 will be described later.

The long mark level detection circuit (control signal output section, average value generation section, second average value calculation section) 7 detects the number of the long mark recording areas 24 The average value of all the maximum values of the analog reproduction signal obtained from the entire area and the average value of the same minimum value are calculated. Then, based on the obtained two average values, the average amplitude value (the average value of the long mark average amplitude) of the analog reproduction signal obtained from one long mark recording area 24 is calculated.

7 is an explanatory view showing a configuration of the long mark level detection circuit 7. In FIG. As shown in this figure, the long mark level detecting circuit 7 includes a shift register 41, an adder 42 and 43, a divider 44 · 45 and a subtracter 46.

The shift register 41 is a 16M stage shift register. Fig. 8 is an explanatory view showing a configuration of the shift register 31. Fig. As shown in this figure, the shift register 41 has 16M cells consisting of cells d1 ₀ to d1 _{16 (M-1) +15} . The value of the digital reproduction signal obtained from the chapter mark recording area 24 and input from the A / D converter 5 for each clock signal output from the clock generation circuit 4 is stored in these cells d1 ₀ to d1 _{16 (M- 1) +15} .

The adder 42 and 43 add the value of the digital reproduction signal stored in the predetermined cell in the shift register 41 and output it. The divider 44 占 5 divides the addition value output from the adder 42 占 3 by 4M and outputs the division value to the subtractor 46. [ The subtractor 46 subtracts the divided value output from the divider 45 from the division value output from the divider 44 and outputs the result to the divider 9 shown in Fig.

The calculation of the long mark average amplitude value by the long mark level detection circuit 7 will be described later.

The data reproduction circuit (binarized data generation section) 8 detects the level of a signal obtained from the light reflected from the data recording area 25 in the sector 22 among the digital reproduction signals outputted from the A / D converter 5 . That is, the data reproducing circuit 8 generates binary data in accordance with a signal obtained from the data recording area 25 of the digital reproduction signals outputted from the A / D converter 5. [

The divider (control signal output unit, control signal generating unit) 9 inputs the end mark average amplitude value and the chapter mark average amplitude value output from the short mark level detection circuit 6 and the long mark level detection circuit 7 And calculates and outputs the ratio (average amplitude ratio, first control signal) at these two average amplitude values.

The differential amplifier (regenerative power controller) 10 compares the average amplitude ratio output from the divider 9 with the target value output from the target value generator circuit (not shown) and outputs the comparison result (difference between the average amplitude ratio and the target value, second control signal) . This average amplitude ratio is dependent on the signal amount of the analog reproduction signal, that is, the magnitude of the detection sphere in the reproduction layer of the magneto-optical disk 1. [

The target value is, for example, a value of the average amplitude ratio detected when reproducing is performed with the reproducing power, that is, the optimum reproducing power so that the bit error rate in the reproducing apparatus is minimized. Alternatively, an intermediate value in a range in which the average amplitude ratio is preferable as the target value may be used. In this reproducing apparatus, such a target value is measured in advance and is stored in a storage device (not shown).

The reproducing power control circuit (reproducing power controlling section, reproducing power varying section) 11 supplies a driving current to the semiconductor laser 12 and controls the reproducing power of the semiconductor laser 12 by controlling the driving current value. The reproduction power control circuit 11 receives the comparison result output from the differential amplifier 10 and controls the drive current to be supplied to the semiconductor laser 12 so that the absolute value of the comparison result becomes smaller.

An error correction circuit (error correction unit) 14 is a circuit for correcting an error of the binary data output from the data reproduction circuit 8. The error correction circuit 14 can reliably correct errors in the binarized data when the bit error rate (BER) of the binarized data is 1E-4 (1 x ^10-4 ) or less.

Next, the reproducing operation of the magneto-optical disk 1 in the reproducing apparatus will be described.

Reproduction is started from the mark recording area 23 in the sector 22 at the time of reproduction. That is, the light beam emitted from the semiconductor laser 12 is irradiated to the mark recording region 23 with a predetermined initial reproduction power. The initial regenerated power is as follows. When the feedback signal from the differential amplifier 10 is not input to the reproduction power control circuit 11, the reproduction power control circuit 11 supplies an initial drive current of a predetermined value to the semiconductor laser 12 . That is, the initial reproducing power of the semiconductor laser 12 is the reproducing power obtained according to the initial driving current.

The photodiode 13 receives the reflected light from the mark recording area 23 and generates an analog reproduction signal and outputs it to the clock generation circuit 4 and the A / D converter 5. The clock generation circuit 4 generates a clock signal synchronized with the channel bit frequency of the analog reproduction signal and outputs the clock signal to the A / D converter 5.

The A / D converter 5 generates a digital reproduction signal from the analog reproduction signal based on the timing of the clock signal output from the clock generation circuit 4, and outputs the digital reproduction signal to the mark level detection circuit 6. 9 is an explanatory diagram showing sampling by the A / D converter 5 for the analog reproduction signal obtained from the mark recording area 23; In this figure, the sampling point is indicated by?.

As shown in Fig. 9, the sampling point in the A / D converter 5 has four kinds of dots, ie, an upper peak point and a lower peak point of the analog reproduction signal, and two intermediate points of these peak points. Hereinafter, as shown in the figure, a sampling point s _4i is defined as an upper peak point of the analog reproduction signal, a sampling point s _{4i + 1} is defined as an intermediate point passing from an upper peak point to a lower peak point, s _{4i + 2} and the lower will be the midpoint of passing from the peak point to the upper peak point to a sampling point _{s 4i + 3 (i = 0} , 1, ..., N-1).

The A / D converter 5 converts the values of the analog reproduction signals at these sampling points into digital signals and sequentially outputs them as digital reproduction signals. That is, the digital reproduction signals at the upper peak point, the lower peak point, and the two intermediate points in the analog reproduction signal are output at every four sampling points.

When the digital reproduction signal outputted from the A / D converter 5 is inputted, the shift register 31 in the mark level detection circuit 6 stores these digital reproduction signals as follows. That is, the shift register 31 supplies the digital reproduction signals of the sampling points S ₀ to S _{4 (N-1) +3} to the 4N cells ds ₀ to ds _{4 (N-1) +3 shown} in _FIG. Remember in order. That is, the cells ds _4i · ds _{4i + 1} · ds _{4i + 2} · ds _{4i + 3} {i = 0, 1, ... , (N-1)} of the sampling points s _4i · s _{4i + 1} · s _{4i + 2} · s _{4i + 3} , respectively. The digital reproduction signal stored in each cell is maintained until the reproduction of the short mark recording area 23 is completed.

When the reproduction of the mark recording area 23 ends, the shift register 31 outputs the value of the digital reproduction signal of the sampling point _s4i stored in the cell _ds4i , that is, the value of the upper peak point of the analog reproduction signal, 32. Further, the shift register 31 outputs the value of the digital reproduction signal of the sampling point s _{4i + 2} stored in the cell ds _{4i + 2} , that is, the value of the lower peak point of the analog reproduction signal to the adder 33.

The adder 32 adds all the values of the digital reproduction signal of the input sampling point _s4i and outputs the obtained addition value to the divider 34. [ The adder 33 additionally adds all the values of the digital reproduction signal of the input sampling point s _{4i + 2} and outputs it to the divider 35.

The divider 34 divides the addition value inputted from the adder 32 by N and obtains the average value of the sampling point _{s4i which} is an upper peak point of the analog reproduction signal. In the following, the average value of the sampling points s _4i is Ts _mean . The divider 35 divides the addition value inputted from the adder 33 by N and obtains the average value of the sampling point s _{4i + 2 which} is the lower peak point of the analog reproduction signal. In the following, the average value of the sampling point s _{4i + 2} is Bs _mean . Thereafter, the divider 34 · 35 outputs Ts _mean and Bs _mean to the subtracter 36. The subtractor 36 calculates the average short mark amplitude by subtracting the _mean from Bs Ts _mean value and outputs it to a divider (9). That is, the subtractor 36 obtains the (Ts _mean -Bs _mean), and outputs it to the divider 9, the result value as a short mark amplitude average.

After the reproduction of the mark recording area 23 is completed, the light beam emitted from the semiconductor laser 12 by the predetermined initial reproducing power is irradiated to the long mark recording area 24. [ The analog playback signal is input to the A / D converter 5 in the same manner as the playback of the short-mark recording area 23. [ Then, the A / D converter 5 generates a digital reproduction signal from the analog reproduction signal based on the timing of the clock signal output from the clock generation circuit 4, and outputs it to the long mark level detection circuit 7.

10 is an explanatory view showing sampling by the A / D converter 5 for the analog reproduction signal obtained from the chapter mark recording area 24. In FIG. Also, in this drawing, the sampling points are indicated by o.

As shown in Fig. 10, the sampling point in the A / D converter 5 is a point dividing the analog reproduction signal of one period into 16 parts. Therefore, as shown in the figure, four points of the upper envelope of the analog reproduction signal are sampled at sampling points 1 _16j 1 _{16j + 1} 1 _{16j + 2} 1 _{16j + 3} and four points of the lower envelope The middle four points from the upper envelope to the lower envelope are sampled at a sampling point 1 _{16j + 4} · 1 _{16j + 5} · 1 _{16j + 6} · 1 _{16j + 8} · 1 _{16j + 9} · 1 _{16j + 10} · 1 _{16j +} 1 _{16j + 7} and the intermediate four points from the lower envelope to the upper envelope are designated as sampling points 1 _{16j + 12}占_{16j + 13}占_{16j + 14}占_{16j + 15} (j = 0, 1, ..., ). The A / D converter 5 converts the values of the analog reproduction signals at these sampling points into digital signals and sequentially outputs them as digital reproduction signals.

When the digital reproduction signal outputted from the A / D converter 5 is inputted, the shift register 41 in the long mark level detection circuit 7 stores these digital reproduction signals as follows. That is, the shift register 41 outputs digital reproduction signals of sampling points 1 ₀ to 1 _{16 (M-1) +1} to the 16M cells d1 ₀ to d1 _{16 (M-1)} Remember in order. That is, the cells d1 _16j to d1 _{16j + 15} {j = 0, 1, ... , (M-1)} are _stored in the sampling points _16j to _{16j + 15} , respectively. The digital reproduction signal stored in each cell is maintained until the reproduction of the chapter mark recording area 24 is completed.

When the reproduction of the chapter mark recording area 24 is completed, the shift register 41 reads the value of the digital reproduction signal of the sampling points 1 _16j to 1 _{16j + 3} stored in the cells d1 _16j to d1 _{16j + 3} , And outputs the value of the upper envelope point to the adder 42 as a whole. Further, the shift register 41 sets the value of the digital reproduction signal of the sampling point 1 _{16j + 8} to 1 _{16j + 11} stored in the cells d1 _{16j + 8} to d1 _{16j + 11} , that is, the value of the lower envelope point of the analog reproduction signal And outputs them all to the adder 43.

The adder 42 adds all the values of the digital reproduction signals of the input sampling points 1 _16j to 1 _{16j + 3} and outputs the obtained sum to the divider 44. The adder 43 additionally adds all the values of the digital reproduction signals of the input sampling points 1 _{16j + 8} to 1 _{16j + 11} and outputs them to the divider 45.

The divider 44 divides the added value input from the adder 42 by 4M and obtains an average value of the sampling points 1 _16j to 1 _{16j + 3, which} is the upper envelope point of the analog reproduction signal. Hereinafter, the average value of the sampling points 1 _16j to 1 _{16j + 3} is taken as T1 _mean . The divider 45 divides the addition value input from the adder 43 by 4M and obtains the average value of the sampling points 1 _{16j + 8} to 1 _{16j + 11, which} is the lower envelope point of the analog reproduction signal. Hereinafter, the average value of the sampling points 1 _{16j + 8} to 1 _{16j + 11} is defined as B1 _mean . Thereafter, the divider 44 占 5 outputs T1 _mean and B1 _mean to the subtracter 46. [ After that, the subtracter 46 calculates a device mark average amplitude B1 by subtracting the _mean from the _mean T1 and outputs it to a divider (9). That is, the subtracter 46 obtains (T1 _mean- B1 _mean ) and outputs the result to the divider 9 as a long-mark average amplitude value.

When the short-mark average amplitude value and the long-mark average amplitude value are inputted, the divider 9 calculates the average amplitude ratio, which is the ratio of these average amplitude values, to the differential amplifier 10. That is, the divider 9 calculates (Ts _mean- Bs _mean ) / (T 1 _{mean-B 1 mean} ) and outputs the result to the differential amplifier 10 as an average amplitude ratio.

When the average amplitude ratio is inputted from the divider 9, the differential amplifier 10 compares this value with the target value and outputs the comparison result to the reproduction power control circuit 11. [ Then, the reproduction power control circuit 11 controls the drive current to the semiconductor laser 12 so that the feedback is applied in the direction in which the value of the comparison result is reduced. As a result, the semiconductor laser 12 emits a light beam with optimum reproduction power.

After the reproduction of the long mark recording area 24 is completed, the light beam emitted from the semiconductor laser 12 by the optimum reproducing power is irradiated to the data recording area 25. [ The analog playback signal according to the digital data of the data recording area 25 is input to the A / D converter 5 in the same manner as the playback of the short mark recording area 23 or the long mark recording area 24. [

The A / D converter 5 performs predetermined A / D conversion on the analog reproduction signal, generates a digital reproduction signal, and outputs the digital reproduction signal to the data reproduction circuit 8. [ The data reproduction circuit 8 generates binary data based on the digital reproduction signal and outputs it to the error correction circuit 14. The error correction circuit 14 corrects the error of the binarized data and outputs binarized data to a binarized data processing device (not shown). Thereafter, information based on the digital data is reproduced based on the binarized data.

When the reproduction of the data recording area 25 is completed and the reproduction of one sector 22 is completed, the other sectors 22 formed adjacent to this sector are reproduced in the same manner. The reproduction of the data recording area 25 is performed after the drive current supplied to the semiconductor laser 12 is controlled so that the reproduction power of the semiconductor laser 12 is optimal even in the reproduction of the sector 22. [

As described above, in order to calculate the amplitude values of the short mark and the long mark in the reproducing apparatus, a predetermined number of short mark and analog reproducing signal according to the long mark are sampled and the mark average amplitude value and the long mark average amplitude value are calculated . Then, the ratio between the average value of the end marks and the average value of the average marks is calculated, and the reproduction power is controlled based on the average amplitude ratio.

As a result, the error of the calculated average amplitude ratio value can be made very small, so that the error of the reproduction power control by the reproduction power control circuit 11 can be made very small. Therefore, according to the present reproducing apparatus, it is possible to perform reproduction with the optimum light beam.

In the magneto-optical disk 1, the short mark recording area 23 and the long mark recording area 24 are provided for each sector 22 in a dispersed manner. The drive current supplied to the semiconductor laser 12 is controlled so that the reproduction power of the semiconductor laser 12 is optimized every time each sector 22 is reproduced.

As described above, the reproducing power of the semiconductor laser 12 is controlled in short time intervals in the present reproducing apparatus. Therefore, even if the environment in which the reproducing apparatus is placed changes in a short time and the optimal reproducing power for the semiconductor laser 12 fluctuates within a short time, the reproducing power of the semiconductor laser 12 can be always controlled to an optimum value. That is, in this reproducing apparatus, it is possible to control the reproducing power of the semiconductor laser 12 in accordance with the short-term fluctuation of the optimum reproducing power.

Next, the accuracy of control at the reproducing power of the semiconductor laser 12 in the reproducing apparatus will be described. This accuracy depends on the precision of the comparison result outputted by the differential amplifier 10, and the comparison result also depends on the accuracy of the average amplitude ratio calculated by the divider 9. The accuracy of this average amplitude value (Ts _mean- Bs _mean ) / (T1 _mean- B1 _mean ) depends on the number of averaging bytes of the short mark and the long mark.

As described above, when the bit error rate (BER) of the binary data obtained from the data reproducing circuit 8 is 1E-4 (= 1 x 10 ^-4 ) or less, It is possible to perform a correct correction. That is, the BER of the binary data obtained from the data reproducing circuit 8 preferably falls within this range.

In order to keep the BER of the binarized data within the above-mentioned range, it is preferable that the detection aperture formed on the magneto-optical disk 1 in this reproducing apparatus always has a size within a predetermined range. Further, the size of the detection sphere depends on the magnitude of the regenerated power under a constant environmental temperature. Therefore, under a constant environmental temperature, there is a range of regenerative power that makes it possible to set the size of the detection port within a predetermined range.

Further, the control of the regenerative power by the regenerative power control circuit 11 is performed so that the regenerative power is the optimum value, but as described above, this control is based on the result of the comparison outputted from the differential amplifier 10 will be. Incidentally, this comparison result includes an error of magnitude due to an error included in the average amplitude ratio calculated from the divider 9. Therefore, the control of the reproduction power control circuit 11 includes an error equal to the error of the comparison result in the differential amplifier 10.

Therefore, it is preferable that the error of the comparison result output from the differential amplifier 10 is within a range in which the reproduction power generated by the reproduction power control circuit 11 is not deviated from the above range.

Further, the comparison result in the differential amplifier 10 is generated from the value of the target value and the average amplitude ratio. This target value is a value of the average amplitude ratio detected in advance. Therefore, the error of the comparison result of the differential amplifier 10 is an error of the error of the average amplitude ratio outputted from the divider 9.

Therefore, if the error of the average amplitude ratio output from the divider 9 is within a half of the allowable range of the comparison result in the differential amplifier 10, the BER of the binary data output from the data reproducing circuit 8 is 1E -4 or less. The range of the average amplitude ratio error corresponds to the number of averaged bytes of the short mark and the long mark in the short mark recording area 23 and the long mark recording area 24. Therefore, the range of the error of the average amplitude ratio and the average number K of averaging bytes of the short mark and the long mark will be described below.

11 is a graph showing the result of measuring the relationship between the number K of averaged bytes of the short mark and the long mark in the magneto-optical disk 1 and the accuracy of the average amplitude ratio detected by the present reproducing apparatus.

As described above, the end mark and the long mark in this measurement are recorded according to the (1, 7) RLL modulation method. In this figure, the accuracy of the average amplitude ratio is shown by the standard deviation. This standard deviation is obtained from the distribution of the results of detection of the average amplitude ratio 100 times (the result of reproduction for a total of 100 sectors 22). The magnitude of the standard deviation depends on the magnitude of the fluctuation of the average amplitude ratio, .

12 shows the relationship between the reproduction power of the semiconductor laser 12 and the BER of binary data obtained from the data reproduction circuit 8 and the relationship between the reproduction power and the average amplitude ratio calculated by the divider 9 And the results are shown in FIG. These measurements were made at a certain environmental temperature.

As shown in Fig. 12, the regenerating power that the BER is made to be 1E-4 or less is about 2.10 to 2.68 mW. That is, the preferable range of regenerative power under the environmental temperature is about 2.10 to 2.68 mW. When the reproduction power is in this range, the average amplitude ratio is 0.14 to 0.28. That is, the average amplitude ratio in this case is 0.21 + 0.07, and the target value input to the differential amplifier 10 is 0.21.

Therefore, under this environmental temperature, the regenerative power control circuit 11 controls the regenerative power so that the average amplitude ratio is 0.21. The permissible range of the error in the control by the regenerative power control circuit 11, that is, the permissible range of the error in the comparison result of the differential amplifier 10, can be within 0.07. Therefore, the permissible range of the error of the average amplitude ratio output from the divider 9 can be within +/- 0.035 (+/- 0.07 / 2).

The tolerance range of the error in the comparison result of these differential amplifiers 10 and the tolerance range in the average amplitude ratio of the divider 9 does not substantially change even if the ambient temperature changes. This reason will be described below.

The measurement results shown in Fig. 12 change depending on the environmental temperature. That is, when the ambient temperature is high, the average amplitude ratio to the regenerative power is shifted to the low power side in principle. In this case, the BER for the reproduction power also shifts to the lower power side equally. Therefore, the range of the average amplitude ratio when the BER is in the range of 1E-4 or less does not substantially change with the change of the environmental temperature. In addition, the standard deviation of the average amplitude ratio shown in Fig. 11 and the reproduction power at which the BER is in the above range are negligibly small in accordance with the environmental temperature. This is also true for the measurement with respect to the magneto-optical disk of the NRZI modulation method to be described later.

Therefore, the range of the tolerance in the tolerance of the error in the comparison result of the differential amplifier 10 and the tolerance in the average amplitude ratio of the divider 9 can be regarded as the range not depending on the ambient temperature.

According to the statistic, if the standard deviation of the average amplitude ratio distribution (which can be regarded as almost normal distribution) is σ, if 3σ is 0.035 or less, the error of the average amplitude ratio is considered to be within ± 0.035 with a probability of 99.7% or more . Therefore, in order to make the detection error of the average amplitude ratio within the range of 占 0,035, it can be said that? Is preferably 0.0117 (0.035 / 3) or less. It can be seen from Fig. 11 that the standard deviation is 0.0117 or less when the number of averaged bytes K is 5 or more. Therefore, it can be said that the number K of averaging bytes of the short mark and the long mark is preferably 5 bytes or more.

As shown in Fig. 11, when the number of averaged bytes K becomes 40 bytes or more, the standard deviation hardly changes. Therefore, the number of averaged bytes K is 40 bytes or less.

Next, the detection error of the average amplitude ratio in the magneto-optical disk whose modulation method is the NRZI modulation method will be described. In this magneto-optical disk, an end mark having a mark length of 2Tc is repeatedly recorded at a mark distance of 1Tc in the end mark recording area 23 in the configuration of the magneto-optical disk 1, 24, a long mark having a mark length of 8Tc is repeatedly recorded at an inter-mark distance of 8Tc. Further, the number of averaged bytes between the short mark and the long mark on the magneto-optical disk is denoted by K '.

13 is a graph showing the result of measuring the relationship between the number K of averaged bytes of the short marks and the long marks and the accuracy of the average amplitude ratio detected by the present reproducing apparatus. 11, the accuracy of the average amplitude ratio is shown by the standard deviation. This standard deviation is obtained from the distribution of the results of detecting the average amplitude ratio 100 times. As shown in the figure, the standard deviation hardly changes when the number of averaged bytes K 'is 25 bytes or more.

14 shows the relation between the reproducing power of the semiconductor laser 12 and the BER of the binary data obtained from the data reproducing circuit 8 when the present magneto-optical disk is reproduced by the reproducing apparatus, And the average amplitude ratio calculated in the divider 9 are measured. These measurements were made at any given environmental temperature.

As shown in Fig. 14, the average amplitude ratio is in a range from 0.23 to 0.38 at a reproducing power such that the BER is 1E-4 or less. That is, under this environmental temperature, the average amplitude ratio is 0.305 ± 0.075, and the target value input to the differential amplifier 10 is 0.305. The range of ± 0.075 is a range that does not substantially change according to the environmental temperature as described above.

Therefore, it is preferable that the standard deviation sigma of the average amplitude ratio distribution be equal to or less than 0.0125 (0.075 / 2/3) in the same manner as in the case of the magneto-optical disk 1 in which recording is performed by the (1, 7) RLL modulation method can do. Therefore, it can be said from FIG. 13 that the number of averaged bytes K 'is preferably 5 bytes or more.

To sum up the above results, it is preferable that the number of averaging bytes in the recording mark for reproduction power control is at least 5 bytes or more, and at most 40 bytes is sufficient. That is, it can be said that the recording amounts of the short mark recording area 23 and the long mark recording area 24 are preferably 5 bytes or more and 40 bytes or less, respectively.

Therefore, by recording the recording mark for controlling the reproducing power at 5 bytes or more and 40 bytes or less in the magneto-optical disk 1, it is possible to control the reproducing power at a sufficiently high precision and in a short time without deteriorating the utilization efficiency of the magneto- .

As shown in Fig. 15, in the sampling of the analog reproduction signal according to the mark recorded according to the (1, 7) RLL modulation method, the upper and lower peak points are sampled one by one for every 4 channel bits. Therefore, amplitude values of three samples are obtained for each one byte (12 channel bits). 16, in the sampling of the analog reproduction signal according to the chapter mark recorded similarly by the (1, 7) RLL modulation method, four upper and lower envelope points are sampled for every 16 channel bits. Therefore, amplitude values of three samples can be obtained every one byte.

In addition, as shown in FIG. 17, in the sampling of the analog reproduction signal according to the end marks recorded by the NRZI modulation method, the top and bottom peak points are sampled one by one for every three channel bits. Therefore, amplitude values of about 2.7 (= 8/3) samples are obtained for each 1 byte (8 channel bits). In addition, as shown in Fig. 18, in the sampling of the analog reproduction signal according to the long mark recorded by the NRZI modulation method, 6 upper and lower envelope points are sampled for every 16 channel bits. Therefore, amplitude values of three samples are obtained every one byte.

Therefore, when the recording mark for reproduction power control is recorded by the (1, 7) RLL modulation method, if the number of samples is 15 or more, the detection error of the average amplitude ratio is within 0.035. In addition, it is sufficient that the number of samples is 120 or less.

The number of samples is the number of amplitude values used to obtain the average amplitude value.

Further, in the case where the recording mark for regenerative power control is recorded by the NRZI modulation method, the detection error of the average amplitude ratio can be made within 0.0375 when the number of samples is (40/3) or more, that is, 14 or more. In addition, it is sufficient that the number of samples is 120 or less.

Therefore, even if the modulation method of the magneto-optical disk is the (1, 7) RLL modulation method or the NRZI modulation method, it is preferable that the number of samples is 15 or more and 120 or less.

The error correcting circuit 14 in this reproducing apparatus is capable of performing a correct correction when the BER of the binary data obtained from the data reproducing circuit 8 is 1E-4 or less. However, Is the same as the error correction circuit used in Fig. That is, the BER is preferably 1E-4 or less even in a normal optical reproducing apparatus.

In addition, there is a possibility that the preferable range of the above-described averaged bytes K and K 'and the number of samples of recording marks for regenerative power control are slightly varied depending on the reproduction characteristics of the optical reproducing apparatus. However, it is considered that there is no large variation in the characteristics of the optical reproducing apparatus, such as deviating from these ranges.

Although the reproducing power of the semiconductor laser 12 is controlled in accordance with the driving current in the present embodiment, it actually varies depending on the environmental temperature. However, in this reproducing apparatus, since the reproducing power is controlled so that the average amplitude ratio becomes constant, even if the reproducing power varies according to the environmental temperature, the reproducing power can be set to the optimum value.

Further, a technology called APC (Auto Power Control) may be used in order to compensate for the change in the regenerative power with the change of the environmental temperature. This technique feeds back the difference between the preset regenerating power and the current regenerating power to always maintain the regenerating power at the regenerated regenerating power even if the ambient temperature changes. That is, the reproducing apparatus may be configured to perform APC, and the reproducing power control circuit 11 may control the setting reproducing power.

The present playback apparatus has a configuration in which the short mark level detection circuit 6 and the long mark level detection circuit 7 are provided with a shift register 31 and a shift register 41. [ Then, the calculation of the average value is performed after all the values of the predetermined number of digital reproduction signals are inputted to the shift registers 31 and 41 in the calculation of the short mark average amplitude value and the long mark average amplitude value. However, the configuration of the reproducing apparatus is not limited to this.

That is, the values of the digital reproduction signals of the upper peak point and the lower peak point inputted to the mark level detection circuit 6 are not stored in the shift register but are sequentially added, and after all the values are added, And the average value of the end mark magnitudes may be calculated by taking the difference between the obtained magnitude values.

Likewise, the values of the digital reproduction signals of the upper envelope point and the lower envelope point input to the long mark level detection circuit 7 are not sequentially held in the shift register but are sequentially added, and after all the values are added, The average amplitude value of the long mark may be calculated by performing the division and taking the obtained difference value.

Further, even in the configuration in which only the sampling points of the upper and lower peak points in the analog reproduction signal are sampled from the digital reproduction signal corresponding to the end mark in the short mark level detection circuit 6 and the result is averaged, good. Similarly, the long mark level detecting circuit 7 may extract only the sampling points of the upper and lower envelope points from the digital reproduction signal according to the long mark, perform averaging processing, and output the same as the long mark average amplitude value.

In the present embodiment, a case has been described in which the reproducing apparatus reproduces a magneto-optic disc of a magnetic super resolution type. However, the recording medium which can be reproduced by the reproducing apparatus is not limited to this. The reproducing apparatus can be configured to reproduce a magneto-optical disk, an optical disk, an optical card, an optical tape, etc., instead of a magnetic super-resolution system.

Although the recording track 21 of the magneto-optical disk 1 is formed in a concentric circular form, the recording track of the magneto-optical disk 1 may be formed in a spiral form.

The step mark and the long mark in the magneto-optical disk 1 may not be previously formed in the short mark recording area 23 and the long mark recording area 24. [ The magneto-optical disk 1 may be provided with an area of a predetermined size (for example, 5 bytes or more, and 40 bytes or less) for forming these end marks and long marks. The recording marks for controlling the reproduction power desired by the user may be recorded in these areas 23 and 24 until reproduction is performed.

In this reproducing apparatus, the short mark level detecting circuit 6 and the long mark level detecting circuit 7 perform the reproducing power control using the peak points in the upper and lower sides in the sampling, It does not stop. The mark level detection circuit 6 and the long mark level detection circuit 7 may use any sampling point as long as the mark average amplitude value and the long mark average amplitude value are obtained.

That is, the short mark level detection circuit 6 and the long mark level detection circuit 7 detect the size of the analog reproduction signal in a predetermined phase (for example, analog The size of the shoulder phase in the reproduction signal) may be extracted. The short mark level detection circuit 6 and the long mark level detection circuit 7 may calculate the short mark average amplitude value and the long mark average amplitude value in the analog reproduction signal based on the extracted size.

As described above, the reproducing light quantity control device in the first optical reproducing apparatus of the present invention uses an optical recording medium for reproducing recording information from the recording layer by generating an opening smaller than the light spot diameter of the irradiated light beam in the reproducing layer And a control means for controlling a reproduction power by detecting a reproduction signal from a reproduction power control mark recorded on the optical recording medium, wherein in the reproduction light quantity control device in the optical reproduction apparatus, And the reproduction power is controlled based on the reproduction signal obtained by reproduction in the range of 5 bytes or more and 40 bytes or less.

The reproducing light quantity control device in the second optical reproducing apparatus of the present invention uses an optical recording medium for reproducing recording information from the recording layer by generating an opening in the reproducing layer smaller than the optical spot diameter of the irradiated light beam, In the reproducing light quantity control apparatus in the optical reproducing apparatus having the control means for detecting the reproducing signal from the reproducing power control mark recorded on the optical recording medium and controlling the reproducing power, / 3) samples and not more than 120 samples, and the reproduction power is controlled based on the reproduced signals.

Further, in the structure of the reproduction light quantity control device in the above-described first or second optical reproducing device, the reproduction light quantity control device in the third optical reproducing device of the present invention is a device for obtaining a plurality And an averaging means for averaging the amplitude values of the amplitude values.

If the recording area of the recording mark for reproduction power control is excessively large, the use efficiency of the magneto-optical disk is deteriorated. On the other hand, if the recording area is excessively small, fluctuation in the average amplitude ratio obtained becomes large, and the control error of reproduction power becomes large.

According to the configuration of the reproducing light quantity control device in the first to third optical reproducing apparatuses described above, since the recording area of the reproducing power control mark is an appropriate size, the use efficiency of the optical recording medium can be improved, And the power can be controlled.

Further, in the first optical recording medium of the present invention, in the optical recording medium for reproducing the record information from the recording layer by generating an opening smaller than the optical spot diameter of the irradiated light beam in the reproducing layer, And a control mark is recorded.

Further, in the second optical recording medium of the present invention, in the above-mentioned first optical recording medium, the reproducing power control mark is formed by repeating patterns of mark marks and repeating patterns of mark marks, and each repeating pattern is 5 bytes or more and 40 bytes or less .

Further, in the third optical recording medium of the present invention, in the above-mentioned first optical recording medium, the mark for regenerating power control is provided for each sector.

According to the configurations of the first to third optical recording media, since the data recording area can be enlarged, it is possible to improve both the utilization efficiency of the optical recording medium and the control of the reproduction power with high accuracy. In addition, the reproduction power control can be performed for each sector as the recording areas of the recording marks for reproduction power control are distributed and provided for each sector, so that reproduction power control can be performed at short time intervals. Therefore, it is possible to follow the short-term fluctuation of the optimum regenerative power.

[Second embodiment]

A second embodiment of the present invention will be described below.

19 is an explanatory view showing a configuration of a magnetic super-resolution type optical reproducing apparatus (hereinafter referred to as a main reproducing apparatus) according to the present embodiment. As shown in the figure, the reproducing apparatus includes an optical head 62, an identification information reproducing circuit 64, a first clock generating circuit 65, a second clock generating circuit 66, a clock selecting circuit 67 A PRML demodulation circuit 69, an amplitude ratio detection circuit 70, a differential amplifier 71, and a regenerative power control circuit 72. The A / D converter 68, the PRML demodulation circuit 69, The magneto-optical disk 61 shown in this figure is an optical recording medium of a magnetic super-resolution type reproduced by the present reproducing apparatus.

First, the configuration of the magneto-optical disk 61 will be described. The magneto-optical disk 61 has a reproducing layer and a recording layer, a detection aperture smaller than the optical spot diameter of the irradiated light beam is generated in the reproduction layer, and a magnetic super-resolution Type recording medium.

20 is an explanatory diagram showing the configuration of the magneto-optical disk 61. Fig. As shown in the figure, the recording track 91 is formed concentrically in the magneto-optical disk 61. [ In the recording track 91, a plurality of sectors 92 are formed continuously.

21 is an explanatory diagram showing the configuration of the present sector 92. Fig. As shown in the figure, in each sector 92, a mark recording area 93, a chapter mark recording area 94, a data recording area 95, and an identification information recording area 96 are formed.

The mark recording area (reproduction power control area) 93 is an area where a mark, which is a recording mark for controlling reproduction power, is formed. Also, the chapter mark recording area (reproduction power control area) 94 is an area in which a long mark, which is a recording mark for controlling reproduction power, is formed. The data recording area 95 is an area in which information desired by the user is recorded as digital data. The modulation method of the digital data recorded in the data recording area 95 is not particularly limited. Hereinafter, (1, 7) RLL (Run Length Limited) modulated digital data is recorded in the data recording area 95 do.

Fig. 22 is an explanatory diagram showing these long marks and short marks. As shown in the figure, a chapter mark having a mark length of 8Tc is repeatedly formed in the chapter mark recording area 94 with a mark inter-mark distance of 8Tc (Tc is a channel bit length). In the same way, in the end mark recording area 93, an end mark having a mark length of 2Tc is repeatedly formed at an inter-mark distance of 2Tc. In the following description, the numbers of the short marks and the long marks formed in the short mark recording area 93 and the long mark recording area 94 are N and M, respectively (N and M are predetermined natural numbers).

The identification information recording area (disc information area) 96 includes identification information (hereinafter referred to as modulation method identification information) for identifying the modulation method of the digital data stored in the data recording area 95, (Hereinafter referred to as control recording mark identification information) for identifying the recording state of the recording mark for reproduction power control made up of the long mark and the long mark are recorded in advance. Here, the recording state of the recording mark for reproduction power control means the size of the short mark recording area 93 and the short mark recording area 94, the length and number of marks of the short mark and long mark recorded in these, The frequency and the phase of the optimum clock signal for sampling the analog reproduction signal according to the clock signal.

Next, each configuration of the playback apparatus shown in Fig. 19 will be described.

The optical head (reproduction signal generating section) 62 includes a semiconductor laser 82 and a photodiode 83. The semiconductor laser (reproduction signal generating section) 82 irradiates the recording track 91 on the magneto-optical disk 61 with a light beam a by a predetermined reproducing power. The photodiode (reproduction signal generating section) 83 receives the light reflected by the respective areas 93 to 96 of the sector 92 in the recording track 91 and outputs an analog reproduction signal corresponding to the light And outputs it. In the following description, an analog playback signal obtained from the magneto-optical disk 61 is referred to as an analog playback signal c.

An identification information reproducing circuit (a digital signal output unit, a clock signal selecting unit, and a recording mark determining unit) 64 receives the analog playback signal c generated by the photodiode 83, And obtains the modulation mode identification information and the control recording mark identification information of the magneto-optical disc 61 from the analog reproduction signal c according to the recording area 96. [ The identification information reproducing circuit 64 identifies the type of modulation scheme and the recording state of the recording mark for reproduction power control from these both identification information and delivers them to the clock selection circuit 67. In the following description, the type of the modulation scheme of the magneto-optical disk 61 transmitted by the identification information reproduction circuit 64 and the recording status of the recording mark for reproduction power control will be referred to as disk information.

A first clock generating circuit 65 (a digital signal outputting unit, a clock signal generating unit, and a first clock signal generating circuit) 65 receives an analog reproduction signal c and generates an analog reproduction signal c by a phase locked loop (PLL) And generates and outputs the clock signal CLK 1 of the bit period. Similarly, the second clock generation circuit (digital signal output section, clock signal generation section, second clock signal generation circuit) 66 receives the analog reproduction signal c and generates a bit cycle And outputs the generated clock signal CLK2.

Fig. 23 is an explanatory view showing the clock signal CLK 1 and the clock signal CLK 2. As shown in this figure, these clock signals CLK 1 and CLK 2 are the same in frequency but out of phase with each other. That is, the phase of the clock signal CLK 2 is out of phase with the phase of the clock signal CLK 1 by a half period (180 °).

A clock selection circuit 67 (a digital signal output unit, a clock signal selection unit, and a clock signal selection circuit) 67 receives the clock signal CLK 1 and the clock signal CLK 2 and the magneto-optical disk 61 output from the identification information reproduction circuit 64, The disc information of the disc is input. Then, based on the disc information, one of the two clock signals is selected and output to the A / D converter 68.

The A / D converter 68 (digital signal output section, digital signal generation section) receives the analog playback signal c and the clock signal output from the clock selection circuit 67. Then, based on the timing of the clock signal, the analog playback signal c is converted into a digital signal and output. In the following description, the digital signal output from the A / D converter 68 is referred to as a digital reproduction signal.

A PRML demodulation circuit (demodulation section) 69 receives a digital reproduction signal, demodulates the signal in accordance with a PRML (Partial Response Maximum Likelihood) demodulation method, and generates binary data.

An amplitude ratio detection circuit (reproduction power control section) 70 receives a digital reproduction signal and outputs a digital reproduction signal based on a digital reproduction signal in accordance with the short mark recording area 93 and the long mark recording area 94 in one sector 92 (Detects) the amplitude ratio (referred to as the amount of the reproduction signal, hereinafter referred to as the average amplitude ratio) between the end mark and the long mark according to the method described later and outputs the calculated result.

The differential amplifier (regenerative power control section) 71 compares the average amplitude ratio output from the amplitude ratio detection circuit 70 with the target value output from the target value generation circuit (not shown), and outputs a comparison result (difference between the average amplitude ratio and the target value) .

A regenerative power control circuit (regenerative power control section) 72 supplies a drive current to the semiconductor laser 82 and controls the regenerative power of the semiconductor laser 82 by controlling the drive current value. The reproduction power control circuit 72 receives the comparison result output from the differential amplifier 71 and controls the drive current supplied to the semiconductor laser 82 so that the absolute value of the comparison result becomes smaller.

Here, the selection of the clock signal by the clock selection circuit 67 will be described.

The clock selection circuit 67 selects a clock signal most suitable for sampling the analog reproduction signal c based on the disc information transmitted from the identification information reproduction circuit 64, and outputs the clock signal to the A / D converter 68.

In other words, when the analog reproduction signal c is digital data, the clock selection circuit 67 selects the optimum one for the sampling based on the combination of the digital data modulation method and the PRML demodulation method in the PRML demodulation circuit 69 And selects and outputs a clock signal.

When the analog playback signal c is in accordance with the recording mark for controlling the reproduction power, the clock selection circuit 67 performs sampling on the basis of the recording state of the recording mark such as the mark length of each of the short mark and the long mark, And selects and outputs an optimum clock signal.

24A to 24C are explanatory diagrams showing the relationship between the clock signals CLK 1 and CLK 2 and the analog playback signal c according to the end mark and the chapter mark on which sampling is performed based on these clock signals.

That is, Fig. 24 (a) is an explanatory diagram showing a sampling point when sampling is performed based on the clock signal CLK1 for the analog playback signal c from the end mark. FIG. 24B is an explanatory diagram showing a sampling point in a case where sampling is performed based on the clock signal CLK 2 for the analog playback signal c from the end mark. Fig. 24C is an explanatory diagram showing a sampling point when sampling is performed on the analog playback signal c from the long mark on the basis of the clock signal CLK1.

In these drawings, & cir & indicates a sampling point to be applied to each analog playback signal c determined based on each clock signal.

As shown in FIG. 24A, the clock signal CLK 1 has an optimal phase for demodulation by the PR (1, 2, 1) ML demodulation method.

In addition, as shown in Fig. 22, a recording mark pattern in which a mark having a mark length of 2Tc is repeated is formed in the mark recording area 93. [ In order to control the reproduction power, it is preferable that the upper and lower peak points of the analog reproduction signal c according to these mark marks be sampled.

Therefore, when the clock signal CLK l is used as shown in FIG. 24A, it is difficult to sample the upper and lower peak points of the analog playback signal c.

On the other hand, when the clock signal CLK 2 is used as shown in Fig. 24B, it is easy to sample the upper and lower peak points of the analog playback signal c. Therefore, sampling of the analog playback signal c according to the end mark is preferably performed based on the clock signal CLK 2 rather than based on the clock signal CLK 1.

As shown in Fig. 22, a recording mark pattern is formed in which a long mark having a mark length of 8Tc is repeated in the long mark recording area 94. [ In addition, in order to control the reproduction power, it is preferable that a large amount of sampling is performed so as to be the upper and lower envelope points of the analog reproduction signal c according to these chapter marks. Therefore, it is preferable that sampling of the analog playback signal c according to the long mark is performed based on the clock signal CLK 1 rather than the clock signal CLK 2 as shown in FIG. 24C.

Therefore, the clock selection circuit 67 outputs the clock signal CLK 1 to the A / D converter 68 when the analog reproduction signal c is in accordance with the digital data or according to the long mark. On the other hand, the clock selection circuit 67 outputs the clock signal CLK2 to the A / D converter 68 when the analog reproduction signal c follows the mark.

Next, the reproducing operation of the magneto-optical disk 61 in the reproducing apparatus will be described.

At the time of reproduction, reproduction is started from the identification information recording area 96 in the sector 92. That is, the light beam a emitted from the semiconductor laser 82 is irradiated to the identification information recording area 96 by a predetermined initial reproduction power. This initial regenerative power is as follows. When the feedback signal from the differential amplifier 71 is not input to the reproduction power control circuit 72, the reproduction power control circuit 72 supplies a predetermined initial drive current to the semiconductor laser 82. That is, the initial reproducing power of the semiconductor laser 82 is the reproducing power obtained according to the initial driving current.

When the light beam is irradiated from the semiconductor laser 82 to the identification information recording area 96 in the magneto-optical disk 61, the photodiode 83 receives the reflected light b from the identification information recording area 96, And generates a reproduction signal c. The analog reproduction signal c is output to the identification information reproduction circuit 64, the first clock generation circuit 65, the second clock generation circuit 66, and the A / D converter 68.

When the analog playback signal c is input, the identification information reproducing circuit 64 acquires the modulation mode identification information of the magneto-optical disk 61 and the control recording mark identification information based on this signal. Then, the identification information reproduction circuit 64 identifies the type of modulation scheme and the recording state of the recording mark for reproduction power control from these both identification information, and delivers the identification result to the clock selection circuit 67 as disk information.

That is, the identification information reproducing circuit 64 determines that the modulation method of the digital data in the data recording area 95 of the magneto-optical disk 61 is (1, 7) RLL, And the long mark with the mark length of 8Tc is repeatedly formed at the inter-mark distance 8Tc in the long mark recording area 94, and the clock selection circuit 67 ).

After the reproduction of the identification information recording area 96 is completed, the light beam a emitted from the semiconductor laser 82 at a predetermined initial reproduction power is sequentially recorded in the mark recording area 93 and the chapter mark recording area 94 . Similar to the reproduction of the identification information recording area 96, the analog reproduction signal c is generated in accordance with the mark or the chapter mark recorded in each area, and the identification information reproduction circuit 64, the first clock generation circuit 65, The second clock generation circuit 66, and the A / D converter 68, as shown in FIG.

When the analog reproduction signal c according to the end mark or the long mark is inputted, the first clock generation circuit 65 generates the clock signal CLK 1 synchronized with the bit frequency of this signal and outputs it to the clock selection circuit 67. Similarly, the second clock generation circuit 66 generates a clock signal CLK 2 synchronized with the bit frequency of this signal and outputs it to the clock selection circuit 67. As shown in Fig. 23, the phases of these two clock signals are out of phase with each other.

The clock selection circuit 67 selects either the clock signal CLK 1 or the clock signal CLK 2 on the basis of the disc information transmitted from the identification information reproduction circuit 64 during reproduction of the identification information recording area 96, And outputs it to the converter 68.

The A / D converter 68 samples the analog reproduction signal c based on the clock signal output from the clock selection circuit 67, generates a digital reproduction signal, and outputs it to the PRML demodulation circuit 69 and the amplitude ratio detection circuit 70 Output.

The amplitude ratio detection circuit 70 calculates the average amplitude ratio based on these signals and outputs the calculated average amplitude ratio to the differential amplifier 71 when the digital playback signal corresponding to the short mark and the long mark is input. The sampling of the analog reproduction signal c according to the long mark and the short mark by the A / D converter 68 and the calculation of the average amplitude ratio by the amplitude ratio detection circuit 70 will be described later.

When the average amplitude ratio is inputted from the amplitude ratio detection circuit 70, the differential amplifier 71 compares this value with a target value (an anomaly value in the ratio of the amplitude value) and outputs a comparison result (difference between the average amplitude ratio and the target value) And outputs it to the reproduction power control circuit 72. Then, the reproduction power control circuit 72 controls the drive current supplied to the semiconductor laser 82 so that the feedback is applied in the direction in which the comparison result becomes smaller. Thus, the semiconductor laser 82 emits the light beam a by the optimum reproducing power.

After the reproduction of the short mark recording area 93 and the long mark recording area 94 is completed, the light beam a emitted from the semiconductor laser 82 by the optimum reproducing power is irradiated to the data recording area 95. [ The analog playback signal c according to the digital data is supplied to the first clock generation circuit 65 and the second clock generation circuit 66 as in the case of the playback of the short mark recording area 93 and the long mark recording area 94. [ And the A / D converter 68, and the clock signal CLK 1 and the clock signal CLK 2 are input to the clock selection circuit 67.

The clock selection circuit 67 outputs the clock signal CLK 1 optimal for sampling the analog reproduction signal c according to the digital data to the A / D converter 68 based on the disc information. The A / D converter 68 samples the analog reproduction signal c according to the digital data based on the clock signal CLK 1, generates a digital reproduction signal, and outputs it to the PRML demodulation circuit 69 and the amplitude ratio detection circuit 70.

The PRML demodulation circuit 69 equalizes the digital reproduction signal according to the data recording area 95 with the PR (1, 2, 1) characteristics, and thereafter, And decodes it into data to generate binary data. Then, the PRML demodulation circuit 69 outputs this binarized data to a binarized data processing device (not shown).

When the reproduction of the data recording area 95 is completed and the reproduction of one sector 92 ends, the other sectors 92 formed adjacent to this sector are reproduced in the same manner.

Here, the calculation of the average amplitude ratio by the amplitude ratio detection circuit 70 will be described. 25 (a) is an explanatory diagram showing sampling of the analog playback signal c according to the end marks by the A / D converter 68, and FIG. 25 (b) Fig.

As shown in FIG. 25A, the A / D converter 68 generates an upper peak point (T _Si ), an intermediate point (indicated by X in the figure) of the analog reproduction signal c according to the end mark based on the clock signal CLK2, Point), a lower peak point (B _Si ), and an intermediate point are sampled in this order (i is a natural number). Then, the digital reproduction signals obtained by the sampling are sequentially outputted to the amplitude ratio detection circuit 70.

Then, the amplitude ratio detection circuit 70 obtains the average value T _Smean (average value of the upper peak points) in the value of the digital reproduction signal obtained by sampling a predetermined number of T _Si . That is, the amplitude ratio detection circuit 70 obtains the sum of the values of the digital reproduction signal obtained by sampling a predetermined number of T _Si , and divides the sum by the predetermined number to obtain the average value T _Smean .

Further, the amplitude ratio detection circuit 70 similarly obtains the average value B _Smean (average value of lower peak points) in the value of the digital reproduction signal obtained by sampling a predetermined number of B _Si . The sampling numbers of T _Si and B _Si used in calculating the average values T _Smean and B _Smean are the same. Then, the amplitude detection circuit 70 calculates the difference (T _{Smean- Smean} B) between these T _{Smean Smean} and B, and recognizes the average amplitude value of this value, only the mark.

In addition, as shown in Fig.'S 25 0b, A / D converter 68 a clock signal field on the basis of the CLK 1 4 opening of the upper envelope point of the analog reproduction signal c in accordance with the mark (T1 _{j + 1,} T1 _j (B1 _{j + 1} , B1 _{j + 2} , B1 _{i + 2} , T1 _{j + 3} and T1 _{j + 4} ) of the lower envelope point, ₃ , B1 _{j + 4} ) and _four points of the intermediate point are sampled in this order (j is a multiple of 4). Then, the digital reproduction signals obtained by the sampling are outputted to the amplitude ratio detection circuit 70 in order.

Then, the amplitude ratio detection circuit 70 obtains the average value T1 _mean (average value of upper envelope points) of the values of the digital reproduction signal obtained by sampling a predetermined number of T1 _{j + k} (k = 1 to 4). That is, the amplitude ratio detection circuit 70 obtains the sum of the values of the digital reproduction signal obtained by sampling a predetermined number of T1 _{j + k} , and divides the sum by the predetermined number to obtain the average value T1 _mean .

The amplitude ratio detection circuit 70 similarly obtains the average value B1 _mean (average value of the lower envelope points) of the values of the digital reproduction signal obtained by sampling a predetermined number of B1 _{j + k} (k = 1 to 4). The sampling numbers of T1 _{j + k} and B1 _{j + k} used in calculating the average values T1 _mean and B1 _mean are the same. Then, the amplitude ratio detection circuit 70 calculates the _difference (T1 _mean- B1 _mean ) between the Tl _mean and the B1 _mean , and recognizes this difference as the average amplitude value of the long mark.

Then, the amplitude ratio detection circuit 70 calculates the ratio (T _Smean- B _Smean ) / (T 1 _mean- B _{1 mean} ) of the average amplitude value of the short marks to the average amplitude value of the long marks as an average amplitude ratio.

As described above, the magneto-optical disk 61 reproduced by the reproducing apparatus is provided with the identification information recording area 96 in which the modulation mode identification information and the control recording mark identification information are recorded in advance.

In this reproducing apparatus, the identification information reproducing circuit 64 obtains the modulation mode identification information and the control recording mark identification information, identifies the modulation method of the digital data and the recording status of the recording mark for the reproduction power control, To the clock selection circuit 67 as information. The clock selection circuit 67 is supplied with the clock signal CLK 1 and the clock signal CLK 2 which are two types of clock signals having different phases.

The clock selection circuit 67 outputs either the clock signal CLK 1 or the clock signal CLK 2 to the A / D converter 68 based on the disc information. That is, the clock selection circuit 67 selects an optimum clock signal for performing the A / D conversion on the analog playback signal c according to the type of the analog playback signal c and outputs it to the A / D converter 68.

Therefore, the A / D conversion performed by the A / D converter 68 is performed by the optimum sampling period for the input analog playback signal c. That is, the analog playback signal c according to the recording mark for digital data and playback power control is sampled at an optimal phase as shown in Figs. 24A to 24C.

As a result, the PRML demodulation circuit 69 can perform good PRML demodulation. Therefore, the present reproducing apparatus has a low error rate, and it is possible to reproduce the magneto-optical disk 61 according to the PRML demodulation method.

Similarly, the amplitude ratio detection circuit 70 can accurately detect the peak value or the envelope value of the analog playback signal c in the playback power control recording mark, and obtain the average amplitude ratio (playback signal amount). Therefore, the reproducing apparatus can accurately control the regenerating power of the semiconductor laser 82, that is, the light quantity of the light beam a irradiated by the semiconductor laser 82.

As described above, in this reproducing apparatus, the optimum clock signal for the reproduction of the digital data, which is determined by the combination of the modulation method and the demodulation method of the digital data, and the recording All of the recording marks for digital data and reproduction power control can be reproduced based on the optimum clock signal even if the optimum clock signal for reproducing the mark is not unified.

Also, in this reproducing apparatus, a digital reproduction signal is outputted from the one A / D converter 68 to the amplitude ratio detection circuit 70 and the PRML demodulation circuit 69. That is, a digital reproduction signal is outputted to a circuit that performs two different processes from one A / D converter. Therefore, the present reproducing apparatus can be realized by a simple structure.

Further, in this reproducing apparatus, the reproduction power of the semiconductor laser 82 is controlled every time the reproduction of each sector is started. Therefore, the reproduction power is controlled in a short time interval. Therefore, even if the environment in which the reproducing apparatus is placed changes in a short time and the optimum reproducing power for the semiconductor laser 82 fluctuates in a short time, the reproducing power of the semiconductor laser 82 can always be controlled to an optimum value have. That is, in this reproducing apparatus, it is possible to control the reproducing power of the semiconductor laser 2 in accordance with the short-term variation of the optimum reproducing power.

Here, the reason why the sampling of the end mark by the clock signal CLK 1 shown in FIG. 24A is suitable for demodulation by the PR (1, 2, 1) ML demodulation method will be described below.

In the PR (1, 2, 1) ML demodulation system, the better the error rate is, the closer to the PR (1, 2, 1) characteristics the isolated and reproduced waveform 1Tc is. The characteristics of PR (1, 2, 1) are such that the level ratio for each sampling of the channel lock period is as shown in Fig. , 0, 1, 2, 1, 0, ... . In addition, the reproduction signal according to the pattern in which the recording mark having the mark length of 2Tc is repeated is overlapped with this isolated waveform, and therefore, the waveform is as shown in Fig. Therefore, in sampling for the reproduction signal according to this pattern, as shown in FIG. 24A, the clock signal for sampling the shoulder portion of the reproduction signal becomes optimum.

In this embodiment, the PRML demodulation method in the PRML demodulation circuit 69 is the PR (1, 2, 1) modulation method of the digital data in the magneto- ML demodulation method. However, the modulation scheme of the digital data reproducible by the reproducing apparatus is not limited to the (1, 7) RLL modulation scheme, but may be any modulation scheme. The demodulation scheme in the PRML demodulation circuit 69 is not limited to the PR (1, 2, 1) ML demodulation scheme, but may be any PRML demodulation scheme.

In the present embodiment, the information recorded in the identification information recording area 96 of the magneto-optical disk 61 is composed of two types of modulation scheme identification information and control recording mark identification information, However, The information recorded in the identification information recording area 96 and transmitted to the clock selection circuit 67 may be as follows.

That is, a plurality of types of digital information (including digital data and recording marks for controlling reproduction power) are recorded on the magneto-optical disk 61, and an optimum clock signal for reproducing these digital information is recorded on the type of digital information In other cases, the identification information recording area 96 may be provided with information for specifying a clock signal optimum for reproduction of each digital information, the position of each digital information in the sector, and the like. By using such a magneto-optical disk 61, it is possible for this reproducing apparatus to perform reproduction based on a clock signal optimum for all digital information.

In the present embodiment, the magneto-optical disk 61 is provided with an identification information recording area 96 in which modulation scheme identification information and control recording mark identification information are recorded. Then, the identification information reproducing circuit 64 in the reproducing apparatus obtains the modulation method identification information and the control recording mark identification information, and transfers the disk information to the clock selection circuit 67 based on these information. However, the configuration of the reproducing apparatus and the magneto-optical disk 61 is not limited to this.

That is, the reproducing apparatus may be configured so that the analog playback signal c is input to the clock selection circuit 67, and the clock selection circuit 67 identifies the type of the analog playback signal c by analyzing the analog playback signal c.

In this configuration, the clock selection circuit 67 outputs one of the two clock signals to the A / D converter 68 based on the type of the identified analog reproduction signal c. In this configuration, the magneto-optical disk 61 does not need to be provided with the identification information recording area 96. [

Although the phase of the clock signal CLK 1 and the clock signal CLK 2 is shifted by half a period in this reproducing apparatus, the clock signal inputted to the clock selecting circuit 67 is not limited to this. That is, the clock signal inputted thereto may be any suitable one for reproducing the digital data recorded on the magneto-optical disk 61 or the recording mark for controlling the reproduction power.

In the present embodiment, the magneto-optical disk 61 is recorded with a mark for performing optimum reproduction by the clock signal CLK2 as an end mark, while optimum reproduction is performed by the clock signal CLK (1) as a long mark However, the recording mark for controlling the reproducing power recorded on the magneto-optical disk 61 is not limited to this.

For example, a mark on which optimum reproduction is performed by the clock signal CLK2 may be recorded as a chapter mark. That is, the recording mark for performing the optimum reproduction with the clock signal CLK 2 may be used as the long mark and the short mark for the reproduction power control.

When reproducing the magneto-optical disk 61 having such a configuration, the first clock generation circuit 65 of the present reproduction apparatus is a circuit for generating a clock signal for reproducing digital data, while the second clock The generation circuit 66 is a circuit for generating a clock signal for reproducing the recording mark for regenerative power control.

In such a configuration, even if the first clock generating circuit 65 becomes unable to normally output the clock signal CLK 1 due to, for example, unlocking of the PLL, the amplitude ratio detecting circuit 70, the differential amplifier 71, And reproduction power control by the reproduction power control circuit 72 are not affected. Therefore, even if a problem occurs in the first clock generation circuit 65, control of the reproduction power can be normally continued.

Although the clock signal input to the clock selection circuit 67 is of two types, that is, the clock signal CLK 1 and the clock signal CLK 2, the number of clock signals input to the clock selection circuit 67 is It is not limited.

The clock selection circuit 67 may be supplied with as many clock signals as necessary for optimum reproduction of the recording marks for digital data or reproduction power control.

In the present embodiment, the magneto-optical disk 61 has a configuration in which the identification information recording area 96 is provided as one area independent of each sector 92. However, this identification information recording area 96 may be provided in the end mark recording area 93, the long mark recording area 94, or the data recording area 95 in the magneto-optical disk 61, But may be provided in other areas. The identification information recording area 96 may be provided not for each sector 92 but for each recording track 91 or for each magneto-optical disk 61.

The magneto-optical disk 61 is a conventional magnetic recording medium which has a reproduction layer and a recording layer and generates a detection aperture smaller than the optical spot diameter of the semiconductor laser 82 in the reproduction layer to reproduce the record information in the recording layer. Or a super resolution type optical recording medium.

The PRML demodulation circuit 69 in this reproducing apparatus may have the same configuration as the conventional PRML demodulation circuit 26. [

In this reproducing apparatus, the identification information reproducing circuit 64 reproduces the modulation scheme identification information and the control recording mark identification information recorded in the identification information recording area 96 prior to the reproduction of the recording mark for digital data or reproduction power control, (1, 7) RLL and that the recording mark for reproduction power control is a chapter mark consisting of a repetition pattern of 2Tc and a repetition pattern of 8Tc in advance.

Further, in this reproducing apparatus, the amplitude ratio detecting circuit 70 calculates the average amplitude ratio, but the configuration of the reproducing apparatus is not limited to this. For example, instead of the amplitude ratio detecting circuit 70, the present reproducing apparatus may be provided with an end mark level detecting circuit 6, a long mark level detecting circuit 7 and a divider 9 as shown in Embodiment 1 .

The step mark, the chapter mark and the disc information in the magneto-optical disc 61 are not necessarily recorded in advance in the mark recording area 93, the chapter mark recording area 94 and the identification information recording area 96 . The magneto-optical disk 1 may be provided with an area of a predetermined size for recording these step marks, chapter marks and disc information. Then, until the reproduction is performed, the recording mark and the disk information for the reproduction power control desired by the user may be recorded in these areas 93 · 94 · 96.

[Embodiment 3]

A third embodiment of the present invention will be described. Members having the same functions as those of the second embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

26 is an explanatory view showing a configuration of an optical reproducing apparatus (hereinafter referred to as a main reproducing apparatus) according to the present embodiment. As shown in this figure, the present reproducing apparatus has an identification information reproducing circuit 64, a first clock generating circuit 65, a second clock generating circuit 66 Instead of the clock selection circuit 67, the A / D converter 68 and the amplitude ratio detection circuit 70, the double clock generation circuit 101, the A / D converter 102, the signal separation circuit 103, A mark extracting circuit 104 and an amplitude ratio detecting circuit 105 are provided.

The magneto-optical disk 100 in this drawing is an optical recording medium which is reproduced by the present reproducing apparatus. This magneto-optical disk 100 is provided with the mark recording area 93, the chapter mark recording area 94 and the identification information recording area 96 in the configuration of the magneto-optical disk 61 shown in the second embodiment . That is, in the magneto-optical disk 100, recording marks for controlling reproduction power, which are formed by a long mark and a single mark, are not recorded, and only information desired by the user is recorded as digital data.

The double clock generating circuit (digital signal output unit, clock signal output unit) 101 generates a clock signal having a frequency twice as high as the bit frequency (reproduction bit frequency) based on the analog reproduction signal c input from the photodiode 83, CLK 3 is generated and output.

FIG. 27 is an explanatory diagram for illustrating this clock signal CLK 3 in comparison with the clock signal CLK 1 and the clock signal CLK 2 shown in FIG. As shown in this figure, the clock signal CLK 3 is a clock signal having a frequency twice that of the clock signals CLK 1 and CLK 2. Therefore, the clock signal CLK3 has a phase suitable for PR (1, 2, 1) ML demodulation and detection of the upper and lower envelope points in the long mark shown in Fig. 22, Quot ;, it can be said that it is a clock signal including both of the phases suitable for detecting the upper and lower peak points in the clock signal.

The A / D converter (digital signal output unit, digital signal generation unit) 102 shown in Fig. 26 converts the analog reproduction signal c into a digital signal on the basis of the timing of the clock signal CLK3 . In the following description, a digital signal output from the A / D converter 102 is referred to as a digital reproduction signal.

The signal separation circuit (digital signal output section, digital signal separation section 103) receives the digital reproduction signal and alternately separates the values of the digital reproduction signal based on the timing of the clock signal CLK 3 to output two signals .

The long and short mark extraction circuit (reproduction power control section, timing detection section 104) receives binary data output from the PRML demodulation circuit 69 as input, and outputs a recording mark having a mark length of 2Tc and a recording mark having a mark length of 8Tc Only binary data is extracted.

Next, the reproducing operation of the magneto-optical disk 100 in the reproducing apparatus will be described. The operation up to the generation of the analog reproduction signal c from the magneto-optical disk 100 is the same as that of the optical reproducing apparatus shown in Embodiment 2, and a description thereof will be omitted below.

In this playback apparatus, the analog playback signal c output from the photodiode 83 is input to the double clock generation circuit 101 and the A / D converter 102. [ As described above, since the recording mark for controlling the reproducing power is not recorded in the magneto-optical disk 100, the analog reproducing signal c according to the digital data is always outputted from the photodiode 83. [

The double clock generating circuit 101 generates a clock signal CLK 3 having a frequency twice the bit frequency of this signal based on the input analog playback signal c and outputs the clock signal CLK 3 to the A / D converter 102 and the signal separation circuit 103). The A / D converter 102 samples the analog reproduction signal c based on the clock signal CLK (3), generates a digital reproduction signal, and outputs the digital reproduction signal to the signal separation circuit 103.

28 is an explanatory diagram for explaining the generation of a digital reproduction signal by the A / D converter 102 when an analog reproduction signal c according to a recording mark having a mark length of 2Tc to be. In this figure, circles? And? Are points in which the A / D converter 102 performs sampling on the basis of the clock signal CLK3.

As shown in this figure, in the A / D conversion based on the clock signal CLK 3, a sampling point suitable for the PRML demodulation (and a recording mark with a mark length of 8 Tc) indicated by O and a sampling point suitable for the PRML demodulation The sampling points corresponding to the peak detection in the recording mark having the mark length of 2Tc are alternately sampled.

29 is an explanatory view for explaining generation of a digital reproduction signal by the A / D converter 102 when digital data in which recording marks having various mark lengths are randomly formed is reproduced. Also in this drawing, points where the A / D converter 102 performs sampling are indicated by? And?.

The A / D converter 102 generates a digital reproduction signal by such sampling and outputs it to the signal separation circuit 103.

The signal separation circuit 103 alternately separates the inputted digital reproduction signals. That is, the signal dividing circuit 103 divides the digital reproduction signal (hereinafter referred to as the first digital reproduction signal) obtained from the sampling point indicated by o in Fig. 29 and the digital reproduction signal (the second digital reproduction Signal). The first digital reproduction signal is output to the PRML demodulation circuit 69 while the first digital reproduction signal and the second digital reproduction signal are output to the amplitude ratio detection circuit 105. [

The PRML demodulation circuit 69 equalizes the signal with the PR (1, 2, 1) characteristics and then decodes it into the most reliable data by Viterbi decoding and outputs the binarized data . Then, the PRML demodulation circuit 69 outputs this binarized data to the long-term mark extraction circuit 104 and a binarized data processing device (not shown).

The binary data input to the long and short mark extracting circuit 104 corresponds to a recording mark having any one of seven kinds of mark lengths of 2Tc to 8Tc. The long and short mark extraction circuit 104 extracts data obtained from a recording mark having a mark length of 8Tc from the input binary data. Then, the time at which this data is obtained and the sampling is performed (hereinafter referred to as a first sampling time) is specified. The long / short mark extraction circuit 104 similarly extracts data obtained from the recording mark having the mark length of 2Tc. Then, the time at which this data is obtained and the sampling is performed (hereinafter referred to as a second sampling time) is specified. Then, the long and short mark extraction circuit 104 transfers the first and second sampling times to the amplitude ratio detection circuit 105 by a predetermined number.

The amplitude ratio detection circuit (reproduction power control unit, reproduction power control circuit) 105 calculates the average amplitude of the recording mark having a mark length of 8Tc from the first digital reproduction signal, based on the first sampling time transmitted from the long- That is, the average amplitude value (Tl _mean - Bl _mean ) of the long marks shown in the second embodiment. The amplitude ratio detection circuit 105 detects the average amplitude value of the recording mark having the mark length of 2Tc from the second digital reproduction signal based on the second sampling time transmitted from the long mark mark extraction circuit 104, The mean amplitude value of the mark (TS _mean - BS _mean ) is calculated.

Then, the amplitude ratio detection circuit 105 calculates the ratio of these two average amplitude values, that is, the average amplitude ratio (TS _mean - BS _mean ) / (Tl _mwan - Bl _mean ) shown in Embodiment Mode 2, (71).

The calculation of the average amplitude value and the average amplitude ratio by the amplitude ratio detection circuit 105 is performed in the same manner as the calculation method in the amplitude ratio detection circuit 70 shown in the second embodiment. The control of the reproduction power of the semiconductor laser 82 by the differential amplifier 71 and the reproduction power control circuit 72 is as shown in the second embodiment.

As described above, the present reproducing apparatus generates the clock signal CLK 3 having twice the frequency of the clock signals CLK 1 and CLK 2, and the A / D converter 102 outputs the clock signal CLK 3, To generate a digital reproduction signal.

The signal separation circuit 103 alternately separates the digital reproduction signals and outputs the two digital reproduction signals to the amplitude ratio detection circuit 105 and the PRML demodulation circuit 69. Then, the long / short mark extraction circuit 104 specifies the sampling time of the recording mark corresponding to the short mark and the long mark, and transfers the sampling time to the amplitude ratio detection circuit 105 so that the amplitude ratio detection circuit 105 calculates the average amplitude ratio .

Therefore, the reproducing apparatus is not limited to the magneto-optical disc having the recording area for controlling the reproducing power such as the identification information recording area 96, the short mark recording area 93 and the chapter mark recording area 94 shown in the second embodiment. It is possible to calculate the average amplitude ratio and to control the reproduction power of the semiconductor laser 82 even when the recording medium such as the optical disk 100 is reproduced.

Therefore, by using this reproducing apparatus, it is possible to improve the reproduction efficiency of a magneto-optical disk having a higher utilization efficiency than the magneto-optical disk such as the magneto-optical disk 61 shown in Embodiment 2, Can be performed.

(1, 7) RLL modulation method, and the demodulation method in the PRML demodulation circuit 69 is PR (1, 2, 3) 1) ML demodulation method.

However, the modulation scheme of the digital data reproducible by the reproducing apparatus is not limited to the (1, 7) RLL modulation scheme, but may be any modulation scheme. Further, the demodulation method in the PRML demodulation circuit 69 is not limited to the PR (1, 2, 1) ML but may be any PRML demodulation method.

That is, an optimum clock signal for reproduction of digital data, which is determined by a combination of a modulation method and a demodulation method of a digital data, and an optimum clock signal for reproducing a recording mark for controlling reproduction power, It is only necessary to be able to generate the double clock generator circuit 101 by one clock signal corresponding to the two clock signals of the optimum clock signal.

In the present embodiment, a case has been described in which the reproducing apparatus reproduces a magneto-optic disc of a magnetic super resolution type. However, the recording medium that can be reproduced by the reproducing apparatus is not limited to this. The reproducing apparatus can be configured to reproduce a magneto-optical disk, an optical disk, an optical card, an optical tape, etc., instead of a magnetic super-resolution system.

The long and short mark extraction circuit 104 of the present reproduction apparatus extracts only the recording marks of the mark lengths of 2Tc and 8Tc from the binary data output from the PRML demodulation circuit 69, The sampling point may be notified to the amplitude ratio detection circuit 105. [

Further, since the optimum sampling phase of the reproduction signal of the reproduction power control recording mark differs depending on the combination of the digital data modulation method, the PRML demodulation system, and the type of recording mark for reproduction power control, So that an optimal configuration may be employed.

As described above, the fourth optical reproducing apparatus of the present invention is an optical reproducing apparatus for controlling the light amount of the light beam on the basis of a reproduction signal obtained by irradiating a light beam on an optical recording medium on which recording data and recording marks are recorded, Clock generating means for generating a first sample clock for sampling the reproduction signal and a second sample clock having a phase different from that of the first sample clock, A / D conversion means for A / D converting the reproduction signal, PRML demodulation means for demodulating the recording data subjected to A / D conversion based on the first sample clock, signal amount detection means for detecting a reproduction signal amount from the recording mark subjected to A / D conversion based on the second sample clock, And a light amount control means for controlling the light amount of the light beam based on the reproduction signal amount.

In this fourth optical reproducing apparatus, data reproduction with a low error rate by PRML demodulation is performed by optimally selecting the sampling phase of A / D conversion in the case of performing the PRML demodulation and the detection of the recording mark for reproduction power control At the same time, the peak value of the reproduction signal of the recording mark for reproduction power control can be detected accurately and the reproduction signal amount can be obtained, so that accurate reproduction power control can be realized.

In the fifth optical reproducing apparatus of the present invention, in the configuration of the fourth optical reproducing apparatus, the clock generating means includes first PLL means for generating the first sample clock and second PLL means for generating the second sample clock And a second PLL means are separately provided.

In this fifth optical reproducing apparatus, the PLL for generating the sample clock for PRML demodulation and the PLL for generating the sample clock for detecting the amplitude value of the reproduction mark for reproducing power control are separately provided, Even if the normal clock can not be outputted by the unlocking or the like, the control of the reproducing power can be normally continued since the detection of the recording mark for reproducing power control is not affected.

Further, in the sixth optical reproducing apparatus of the present invention, in the configuration of the above-mentioned fourth optical reproducing apparatus, when the PRML demodulation is performed, the first sample clock is switched to the second sample clock, And outputting it to the A / D conversion means.

In this sixth optical reproducing apparatus, by switching the sampling timings of the A / D conversion by switching the two kinds of clocks having different phases, one A / D converting means is shared for PRML demodulation and detection of recording marks for reproduction power control It is possible to simplify the configuration of the reproducing apparatus.

The seventh optical reproducing apparatus of the present invention further includes identification information reproducing means for reproducing identification information for identifying a clock necessary for PRML demodulation and a clock necessary for controlling the light amount in the configuration of the sixth optical reproducing apparatus described above , And switches the clock selection means based on the identification information.

Further, the fourth optical recording medium of the present invention is an optical recording medium for reproducing recorded information from a recording layer by generating a detection sphere having a reproduction spot and a recording layer smaller than an optical spot diameter in a reproduction layer, And an identification information recording area in which identification information for identifying that the phase of the clock for detecting the amount of reproduction signal for controlling the light amount of the light source and the clock for data reproduction are different from each other is recorded.

In the seventh optical reproducing apparatus and the fourth optical recording medium described above, identification information such as a modulation method and a type of a recording mark for regenerative power control is recorded in the identification information recording area of the magneto-optical disk, And a clock for A / D conversion is selected on the basis of the identification information, whereby a recording mark for reproduction power control, which can be generated in various cases by a combination of the types of recording marks for PRML demodulation, modulation and reproduction power control It is possible to realize accurate reproduction power control by setting the A / D conversion sampling phase to be optimum.

The eighth optical reproducing apparatus of the present invention is an optical reproducing apparatus for controlling the amount of the optical beam based on a reproduction signal obtained by irradiating a light beam on an optical recording medium on which recording data and a recording mark are recorded, A / D converting means for A / D converting the reproduction signal by the sample clock, and A / D converting means for converting the A / D-converted output signal Demultiplexing means for demodulating one of the two separated signals and outputting the demodulated signal to a demodulating means for demodulating the demodulated signal; And a light quantity control means for controlling the light quantity of the light beam based on the reproduction signal quantity.

In this eighth optical reproducing apparatus, the A / D-converted reproduced signals are alternately separated for each sampling clock by using a sampling clock having a frequency twice the reproduction bit frequency, so that the reproduced signals of the record data including various mark lengths It is possible to detect the amplitude value of the mark and the long mark from the recording mark, so that the recording mark for the reproduction power control becomes unnecessary, and the use efficiency of the magneto-optical disk can be improved.

The ninth optical reproducing apparatus of the present invention is a ninth optical reproducing apparatus for irradiating a light beam onto an optical recording medium and for generating a reproducing signal in accordance with a recording mark recorded on the optical recording medium on the basis of the reflected light of the light beam, A control signal output unit for detecting an average value of a signal amount in a reproduction signal generated by the reproduction signal generating unit and generating a first control signal according to the average value, And a reproduction power control section for controlling the reproduction power of the light beam irradiated by the reproduction signal generating section so that the signal amount in the reproduction signal becomes an appropriate value.

The tenth optical reproducing apparatus of the present invention is the tenth optical reproducing apparatus according to the ninth optical reproducing apparatus, wherein the control signal outputting unit outputs the maximum value and the minimum value of the reproduction signal according to the recording mark in the optical recording medium, An average value generation unit for generating an average value in amplitude value of the reproduction signal from a maximum value and a minimum value of the predetermined amount detected by the peak value detection unit; And a control signal generator for generating a control signal.

In the eleventh optical reproducing apparatus of the present invention, in the structure of the tenth optical reproducing apparatus, the peak value detecting unit detects a maximum value and a minimum value of a reproduction signal according to a first recording mark having a predetermined mark length, And the average value generation unit detects the maximum value and the minimum value of the reproduction signal according to the second recording mark whose mark length is different from the maximum value and the minimum value of the reproduction signal according to the first recording mark And a second average value calculating section for calculating an average value in the amplitude value of the reproduction signal from the maximum value and the minimum value of the reproduction signal according to the second recording mark, The generating unit may calculate a ratio of an average value calculated by the first average value calculating unit and an average value calculated by the second average value calculating unit as a first control signal A block which.

In the twelfth optical reproducing apparatus of the present invention, in the configuration of the eleventh optical reproducing apparatus, the first and second average value calculating units calculate the first and second average value calculating units in accordance with the first and second recording marks detected by the peak value detecting unit A first adder for calculating a sum of all the maximum values stored in the shift register and a second adder for calculating a sum of all the smallest values stored in the shift register, A second divider for dividing the sum of the maximum values calculated by the first adder by the predetermined amount to calculate an average value of the maximum values and a second divider for calculating a sum of the minimum values calculated by the second adder, A second divider for calculating an average value of a minimum value by dividing the current value by a predetermined amount and a second divider for calculating an average value of the minimum value by dividing the current value by a predetermined divisor By subtracting the average value of the minimum value is exported configuration having a first subtractor for calculating the average value of the amplitude value of the reproduced signal according to the first or second recording mark.

In the thirteenth optical regenerating apparatus of the present invention, in the configuration of the ninth optical regenerator, the regenerative power controller receives the first control signal and a predetermined target value, and outputs the first control signal and the target value And a reproducing power varying section for controlling the reproducing power so that the value of the second control signal becomes small, and the BER of the reproducing signal generated by the reproducing signal generating section is The second control signal is generated to be equal to or less than 1E-4.

The fifth optical recording medium of the present invention comprises a recording layer for recording information, a recording layer formed on the recording layer and formed with a detection aperture as a predetermined light beam is irradiated, Wherein the recording layer includes a data recording area in which a recording mark for recording normal information is formed and a recording mark for controlling reproduction power for controlling the reproduction power of the light beam is 5 bytes And a reproduction power control area formed by an amount equal to or smaller than 40 bytes.

In the sixth optical recording medium of the present invention, in the structure of the fifth optical recording medium, the reproduction power control area is formed such that a first recording mark having a predetermined mark length is formed by an amount of 5 bytes or more and 40 bytes or less And a second recording mark having a mark length different from that of the first recording mark is formed by an amount of 5 bytes or more and 40 bytes or less.

In the seventh optical recording medium of the present invention, in the configuration of the fifth optical recording medium, the reproduction power control area is provided for each sector formed in the recording layer.

The eighth optical recording medium of the present invention comprises a recording layer for recording information, and a recording layer formed on the recording layer, wherein a detection aperture is formed as a predetermined light beam is irradiated, Wherein the recording layer includes a data recording area in which a recording mark for recording normal information is formed and a recording mark for controlling reproduction power for controlling the reproduction power of the light beam, And a disc information area in which the recording state of the recording mark for the reproduction power control is recorded.

The specific embodiments or examples made in the detailed description of the invention are intended to clarify the technical content of the present invention only. Therefore, the invention should not be construed as being limited to such specific examples but may be modified in various ways within the scope of the following claims.

Claims (24)

In the optical reproducing apparatus, A reproduction signal generating section for applying a light beam to the optical recording medium and generating a reproduction signal in accordance with the recording mark recorded on the optical recording medium based on the reflected light of the light beam, A control signal output unit for detecting an average value of a signal amount in a reproduction signal generated by the reproduction signal generating unit and generating a first control signal according to the average value, And a reproduction power control section for controlling the reproduction power of the light beam irradiated by the reproduction signal generating section so that the signal amount in the reproduction signal becomes a predetermined value based on the first control signal generated by the control signal output section Wherein the optical recording medium is an optical recording medium. The method according to claim 1, The reproduction signal generating unit Irradiating a light beam onto an optical recording medium having a recording layer on which a recording mark is recorded and a reproducing layer on which the recording mark is to be transferred and generating a detection aperture of a size corresponding to the reproducing power of the optical beam on the reproducing layer A light beam irradiating unit, And a light receiving section for generating a reproduction signal in accordance with a recording mark of the recording layer, based on the light reflected from the detection aperture formed in the reproduction layer. 3. The method of claim 2, The control signal output unit An amplitude value detector for detecting an amplitude value of a reproduction signal according to the recording mark in the optical recording medium by a predetermined amount, An average value generation unit that generates an average value in an amplitude value of a predetermined amount detected by the amplitude value detection unit; And a control signal generator for generating a first control signal based on the average value generated by the average value generator. The method of claim 3, Wherein the amplitude value detecting section detects amplitude values of a reproduction signal according to a first recording mark having a predetermined mark length and amplitude values of a reproduction signal according to a second recording mark having a mark length different from the first recording mark, Respectively, Wherein the average value generation unit comprises: a first average value calculation unit for calculating an average value in the amplitude value of the reproduction signal from the amplitude value of the reproduction signal according to the first recording mark; and a second average value calculation unit for calculating, from the amplitude value of the reproduction signal according to the second recording mark, And a second average value calculating unit for calculating an average value in the amplitude value of the reproduction signal, Wherein the control signal generating unit generates the ratio of the average value calculated by the first average value calculating unit and the average value calculated by the second average value calculating unit as the first control signal. 5. The method of claim 4, The reproducing power control section A differential amplifier for receiving the first control signal and a predetermined target value and generating a comparison result of the first control signal and the target value as a second control signal, And a reproducing power varying unit for controlling the reproducing power so that the value of the second control signal becomes smaller. 6. The method of claim 5, A binary data generating section for generating binary data in accordance with the reproduction signal output from the reproduction signal generating section; and an error correcting section for correcting the error of the binary data, Wherein the second control signal is generated so that the BER of the binary data becomes a correctable range within a range of the correction capability of the error correction unit. 5. The method of claim 4, Wherein the predetermined amount is 5 bytes or more. 8. The method of claim 7, Wherein the predetermined amount is 40 bytes or less. 5. The method of claim 4, Wherein the predetermined amount is 14 or more. 10. The method of claim 9, Wherein the predetermined amount is 120 or less. 8. The method of claim 7, The first and second recording marks are recorded on the optical recording medium by the (1, 7) RLL modulation method, Wherein the first recording mark has a mark length and a distance between marks of two channel bits, Wherein the second recording mark has a mark length and a distance between marks of 8 channel bits. 8. The method of claim 7, Wherein the first and second recording marks are recorded on the optical recording medium by an NRZI modulation method, Wherein the first recording mark has a mark length of two channel bits and a distance between marks of one channel bit, Wherein the second recording mark has a mark length and a distance between marks of 8 channel bits. In the optical recording medium, A recording layer for recording information; And a reproducing layer which is laminated on the recording layer and in which a detection aperture is formed by irradiating a predetermined light beam and information recorded in the recording layer is read out from the detection aperture, And a reproduction power control area of 5 bytes or more and 40 bytes or less for recording a recording mark for controlling reproduction power for controlling the reproduction power of the light beam on a track for recording information. media. 14. The method of claim 13, The reproduction power control area includes an area of 5 bytes or more and 40 bytes or less for recording a first recording mark having a predetermined mark length, And an area of 5 bytes or more and 40 bytes or less for recording a second recording mark having a mark length different from that of the first recording mark. 14. The method of claim 13, Wherein the reproducing power control area is provided for each sector formed on the track. In the optical reproducing apparatus, A reproduction signal generator for generating a reproduction signal in accordance with a recording mark recorded on the optical recording medium based on the reflected light of the light beam, A digital signal output unit for outputting a digital signal corresponding to the reproduction signal, A demodulator for demodulating the digital signal, And a reproduction power control unit for controlling reproduction power in the reproduction signal generation unit based on the digital signal, The digital signal output unit A clock signal output unit for outputting a clock signal according to a modulation scheme of the recording mark, a demodulation scheme in the demodulation unit, and a control scheme in the reproduction power control unit, And a digital signal generator for generating the digital signal by sampling the reproduction signal based on the clock signal output by the clock signal output unit. 17. The method of claim 16, The clock signal output unit A clock signal generator for generating a plurality of different clock signals based on the reproduction signal, And a clock signal selection unit for selecting a clock signal according to the modulation scheme, the demodulation scheme, or the control scheme from among the plurality of different clock signals based on the reproduction signal, and outputting the selected clock signal to the digital signal generation unit . 18. The method of claim 17, The clock signal selector A recording mark judging section for judging whether a recording mark related to reproduction is a recording mark for regenerating power control or a recording mark for demodulating based on the reproduction signal, And a clock signal selection circuit for selecting one of the plurality of clock signals output from the clock signal generation unit based on the determination result. 19. The method of claim 18, The clock signal generator A first clock signal generation circuit for generating a first clock signal according to the modulation method and the demodulation method based on the reproduction signal, And a second clock signal generation circuit for generating a second clock signal according to the modulation method and the control method based on the reproduction signal. 20. The method of claim 19, The modulation scheme of the recording mark is (1, 7) RLL modulation scheme, The control method of the reproducing power by the reproducing power control section detects the average value of the amplitude values in the reproducing signal according to the two kinds of recording marks having different mark lengths for controlling the reproducing power recorded on the optical recording medium, Calculating a ratio of the average value of the number of the recording mediums, and controlling the reproducing power so as to bring the ratio close to a preset target value, The demodulation scheme of the demodulation unit is a PR (1, 2, 1) ML demodulation scheme, Wherein the phase of the first clock signal and the phase of the second clock signal are shifted by a half period from each other. 17. The method of claim 16, Wherein the clock signal output unit of the digital signal output unit outputs one clock signal according to the modulation scheme, the demodulation scheme, and the control scheme, The digital signal output unit A first digital signal for demodulating the digital signal generated by the digital signal generating unit and a second digital signal for controlling the reproduction power, and outputting the first digital signal to the demodulator, And a digital signal demultiplexing section for outputting the digital signal to the reproducing power control section. 22. The method of claim 21, The modulation scheme of the recording mark is (1, 7) RLL modulation scheme, The control method of the reproducing power by the reproducing power control section detects the average value of the amplitude values in the reproducing signal according to the two kinds of recording marks having different mark lengths for controlling the reproducing power recorded on the optical recording medium, Calculating a ratio of the average value of the number of the recording mediums, and controlling the reproducing power so as to bring the ratio close to a preset target value, The demodulation scheme of the demodulation unit is a PR (1, 2, 1) ML demodulation scheme, Wherein the clock signal output by the clock signal output unit is a signal having a frequency twice that of the clock signal according to the modulation method and the demodulation method. 22. The method of claim 21, The reproducing power control section A timing detecting section for obtaining, based on the digital signal demodulated by the demodulating section, a timing at which a recording mark suitable for controlling reproduction power is sampled; And a reproduction power control circuit for extracting a digital signal corresponding to the recording mark from among the second digital signals based on the timing detected by the timing detection section and controlling reproduction power based on the digital signal . In the optical recording medium, A recording layer for recording information; A reproducing layer which is laminated on the recording layer and in which a detection aperture is formed by irradiating a predetermined light beam and information recorded in the recording layer is read out from the detection aperture, A reproduction power control area for recording a recording mark for controlling reproduction power for controlling reproduction power of the light beam; Wherein a disc information area is provided for recording the modulation method of the recording mark in the two areas and the recording state of the recording mark for controlling the reproduction power.