JPH11120567A - Device and method for recording/reproducing information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record/reproduce information in higher density. SOLUTION: Sample-hold circuits 41-1 to 41-4 subject to sample-and-hold a TPP signal at the prescribed timing synchronized with a PLL clock fed back from a frequency divider 46 to output it to a subtraction circuit 42-1 or the subtraction circuit 42-2. The subtraction circuits 42-1, 42-2 outputs an operation result to the subtraction circuit 42-3. The subtraction circuit 42-3 outputs it to a D/A converter 43. The D/A converter 43 converts the operation result to an analog signal to output it to a low-pass filter 44. The low-pass filter 44 removes a high frequency component from a phase error signal to output a low frequency component to a voltage control oscillator 45. The voltage control oscillator 45 oscillates the clock of a frequency according to an inputted control voltage to output it to the frequency divider 46. The frequency divider 46 frequency divides the inputted clock at a prescribed frequency division ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus and method, and more particularly, to recording or reproducing information at a higher density by generating a clock based on tangential push-pull signals of four different timings. The present invention relates to an information recording apparatus and method capable of performing such operations.

[0002]

2. Description of the Related Art On an optical disk such as a magneto-optical disk or a phase change disk, a signal (clock mark) for generating a clock serving as a base for a synchronization signal or the like is formed in advance.

[0003] As shown in FIG. 8 (A), a convex portion or a mirror portion is provided in a groove as a clock mark.
The land is provided with a concave portion or a groove portion. Thus, when the laser spot moves in the tangential direction of the track, the amount of reflected light changes. As shown in FIG. 9, the reflected light of the laser spot is detected by a photodetector divided into four in a track direction and a direction perpendicular to the track direction. Each of the divided areas and the signal of the reflected light detected in each of the areas are defined as E, F, G, or H clockwise from the upper right.

For example, a tangential push-pull signal (hereinafter referred to as a TPP signal) is obtained from a reflected light of a laser spot tracked by a groove as (E + F)-.
When (G + H) is calculated, a waveform shown in FIG. 8B is obtained. That is, when detecting the reflected light of the laser spot at a position X _1, the level of TPP signal is zero. When detecting the reflected light of the laser spot at a position X ₂ of the laser spot moves to the clock marks from the groove subsequently, the reflected light from the groove is weak, the light reflected from the clock mark is strong.
Therefore, the level of the TPP signal becomes maximum. Then when the laser spot from the clock mark to the groove and detecting reflected light from the laser spot position X ₃ to move, the light reflected from the clock mark is strong, weak reflected light from the groove. Accordingly, the level of TPP signal, in the previous position X ₂ and sign is inverted at a minimum. When the at position X ₄ on the next groove has detected the reflected light of the laser spot, the level of TPP signal is zero.

When (E + F)-(G + H) is calculated as a TPP signal from the reflected light of the laser spot tracked on the land, the waveform shown in FIG. 8C is obtained. That is,
When detecting the reflected light of the laser spot at a position X _1, TPP
The signal level is 0. When detecting the reflected light of the laser spot at a position X ₂ of the laser spot moves to the clock marks from the land Subsequently, reflected light from the land is strong, light reflected from the clock mark is weak. Therefore,
The level of the TPP signal is at a minimum. Then when the laser spot from the clock mark to the land and detecting reflected light of the laser spot at a position X ₃ to move, the light reflected from the clock mark is weak, reflected light from the land is strong. Accordingly, the level of TPP signal, in the previous position X ₂ and sign is reversed, the maximum. Then, the position X ₄ on the next land
When the reflected light of the laser spot is detected by the above, the level of the TPP signal becomes 0.

As described above, the zero cross of the TPP signal whose level changes at the timing of the clock mark is detected, and a master clock is generated by the PLL circuit using the zero cross pulse.

[0007]

As described above, when a clock is generated from the zero-crossing phase error of the TPP signal,
As shown in FIG. 10, when the wavelength of the laser beam is shortened and the diameter of the laser spot is reduced for high-density recording / reproduction, the clock mark recorded on the low-density optical disk is used for high-density recording / reproduction. And the zero cross point of the TPP signal waveform becomes flat. As a result, it becomes difficult to accurately detect the zero-cross point, and the jitter increases. That is, a clock having an accurate phase cannot be generated, and there is a problem that it is difficult to accurately record and reproduce information on a low-density optical disk.

The present invention has been made in view of such a situation. By generating a clock from a difference between TPP signals at different timings, the present invention can accurately perform not only on a high-density optical disk but also on a low-density optical disk. The information can be recorded and reproduced.

[0009]

According to a first aspect of the present invention, there is provided an information recording / reproducing apparatus having lands and grooves formed concentrically or spirally, and one of the lands and the groove is used as a data recording track. In an information recording / reproducing apparatus that optically records or reproduces information on a disk on which a clock area having a different light reflectance from another area is periodically formed on a recording track, the recording track is irradiated. Detecting means for detecting reflected light of light, first generating means for generating a tangential push-pull signal from an output of the detecting means, and second generating means for generating a clock from a difference between the tangential push-pull signals at different timings Means.

According to a third aspect of the present invention, there is provided an information recording / reproducing method having lands and grooves formed concentrically or spirally, wherein one of the lands and the groove is used as a data recording track, and the recording track is periodically recorded. In an information recording / reproducing method of optically recording or reproducing information on a disk on which a clock region having a different light reflectance from that of another region is formed, the reflected light of light applied to a recording track is detected. A first step of generating a tangential push-pull signal from the output of the detecting step.
And a second generation step of generating a clock from a difference between tangential push-pull signals at different timings.

In the information recording / reproducing apparatus according to the first aspect, the detecting means detects the reflected light of the light applied to the recording track, and the first generating means detects the reflected light from the output of the detecting means.
A tangential push-pull signal is generated, and the second generating means generates a clock from a difference between the tangential push-pull signals at a timing different from that of the first generating means.

In the information recording / reproducing method according to the third aspect, in the detecting step, reflected light of light applied to the recording track is detected, and in the first generating step, the tangential push-pull is output from the output of the detecting step. A signal is generated, and in a second generation step, a clock is generated from a difference between the tangential push-pull signals at a different timing from the first generation step.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. In order to clarify the correspondence between each means of the invention described in the claims and the following embodiments, each means is described. When the features of the present invention are described by adding the corresponding embodiment (however, an example) in parentheses after the parentheses, the result is as follows.

That is, the information recording / reproducing apparatus according to the first aspect has lands and grooves formed concentrically or spirally, and one of the lands and the groove is used as a data recording track, and the recording track has a periodicity. ,
In an information recording / reproducing apparatus that optically records or reproduces information on a disk on which a clock region having a different light reflectance from that of another region is formed, reflected light of light applied to a recording track is detected. The detecting means (for example, the optical pickup 3 in FIG. 1) and the first generating means (for example, the IV conversion matrix 4 in FIG. 1) for generating a tangential push-pull signal from the output of the detecting means, Second generation means for generating a clock from the difference between the push-pull signals (for example, FIG. 1)
And a PLL circuit 7).

However, of course, this description does not mean that each means is limited to those described.

An example of the configuration of an information recording / reproducing apparatus to which the present invention is applied will be described with reference to FIG. In this example, the spindle motor 2 rotates the disk 1 at a predetermined speed under the control of the servo controller 5. The optical pickup 3 optically reads data recorded on the disk 1 and supplies the data to the IV conversion matrix 4.

Here, a detailed configuration of the optical pickup 3 will be described with reference to FIG. Laser diode 2
1 outputs a laser beam of a predetermined wavelength, and forms an image on a predetermined area of the disk 1 via the collimator lens 22, the beam splitter 23-1, and the objective lens 24.
The laser light reflected by the disk 1 is incident on the beam splitter 23-1 via the objective lens 24 again, and
Part of the polarized light component and all of the s-polarized light component are reflected and incident on the beam splitter 23-2. The beam splitter 23-2 reflects a part of the incident laser light to enter the lens 25, transmits the remaining laser light, and transmits the remaining laser light via the half-wave plate 28.
9 is incident. The laser light emitted from the beam splitter 23-2 and incident on the lens 25 is incident on the photodetector 27-1 via the cylindrical lens 26 that gives astigmatism to the laser light.

The polarization beam splitter 29 polarizes and separates the incident laser light into an s-polarized light component and a p-polarized light component, and makes the laser light enter the lens 32 and the lens 30, respectively. Lens 32
Is emitted to the photodetector 27-3 via the lens 33, and the laser light emitted from the lens 30 is incident to the photodetector 27-2 via the lens 31.

The detailed configuration of the photodetectors 27-1 to 27-3 will be described with reference to FIG. In this example, the vertical direction in the figure is the radial direction (radial direction) of the disk 1, and the horizontal direction is the track direction (tangential direction). As shown in FIG. 3A, the photodetector 27-1 is divided into regions 27A to 27D, each of which receives the laser beam from the lens 26 of FIG. A to D are output to the IV conversion matrix 4 in FIG. As shown in FIG.
2 is divided into regions 27E to 27H. Each region receives the laser beam from the lens 31 in FIG. 2 and outputs it to the IV conversion matrix 4 as signals E to H according to the amount of the laser beam. I do. Further, as shown in FIG. 3C, the photodetector 27-3 is divided into regions 27I to 27L, each of which receives laser light from the lens 33 in FIG. The signals are output to the IV conversion matrix 4 as signals I to L, respectively.

Returning to the description of FIG. IV conversion matrix 4
Converts each current signal from the photodetectors 27-1 to 27-3 of the optical pickup 3 into a voltage signal. Then, the IV conversion matrix 4 includes a photo detector 27-
From the signal from 1, a (A + C)-(B + D), which is a focus error signal using the astigmatism method, is generated, supplied to the servo controller 5, and the signal of the photodetector 27-2 is used. Generates (E + F)-(G + H) which becomes a TPP signal or (E + H)-(F + G) which becomes a radial push-pull signal (RPP signal), and generates a PLL circuit 7 and a TE signal generation circuit, respectively. Supply 10 The TPP signal may be generated as (A + B)-(C + D), and the RPP signal may be generated as (A + D)-(B + C). The IV conversion matrix 4 becomes a reproduction signal by using the signal from the photodetector 27-2 and the signal from the photodetector 27-3 (E + F + G + H)-(I + J + K + L). Is generated and supplied to the A / D converter 8.

The servo controller 5 is mainly configured to control a focus servo, a tracking servo, a thread servo, or a spindle servo, and a focus error signal supplied from the IV conversion matrix 4 and a TE signal generation circuit 10 Focus control or tracking control of the optical pickup 3 is performed based on the supplied tracking error signal, and the sled motor 6 is controlled based on a DC component of the tracking error signal. Further, the servo controller 5 controls the spindle motor 2 according to the clock signal supplied from the PLL circuit 7. Thread motor 6
Moves the optical pickup 3 to a predetermined position in the radial direction of the disk 1 under the control of the servo controller 5. The laser control circuit 12 is controlled by the servo controller 5 and drives the laser diode 21.

The PLL circuit 7 generates a clock signal based on the TPP signal supplied from the IV conversion matrix 4,
Servo controller 5, A / D converter 8, TG (timing generator) circuit 9, and data detection circuit 1
Feed to 1. The A / D converter 8 binarizes the reproduction signal supplied from the IV conversion matrix 4 in synchronization with the clock signal supplied from the PLL circuit 7 and outputs the binary signal to the data detection circuit 11.

Here, the PLL circuit 7 will be described with reference to FIG. The PLL circuit 7 includes sample and hold (S / H) circuits 41-1 to 41-4 and subtraction circuits 42-1 to 42-
3. D / A converter 43, LPF 44, voltage controlled oscillator (VC
O) 45, and a frequency divider 46.

Sample / hold circuits 41-1 to 41
-4 is such that the TPP signal is sampled and held at a predetermined timing in synchronization with the PLL clock fed back from the frequency divider 46, and is output to the subtraction circuit 42-1 or 42-2 as a digital signal. ing.

The subtraction circuit 42-1 converts the output of the sample / hold circuit 41-1 from the output of the sample / hold circuit 41-1.
2 is subtracted, and the operation result is output to the subtraction circuit 42-3. The subtraction circuit 42-2 includes the sample and hold circuit 4
The output of the sample / hold circuit 41-4 is subtracted from the output of 1-3, and the operation result is output to the subtraction circuit 42-3.
The subtraction circuit 42-3 subtracts the output of the subtraction circuit 42-2 from the output of the subtraction circuit 42-1 and outputs the operation result to the D / A converter 43. The D / A converter 43 converts the operation result, which is a digital signal, into an analog signal and outputs the analog signal to a low-pass filter (LPF) 44. Low-pass filter 44
Removes high frequency components from the input phase error signal,
The low frequency component of the phase error signal is output to the voltage controlled oscillator 45 as a control voltage. The voltage controlled oscillator 45 oscillates a clock having a frequency corresponding to the input control voltage and outputs the clock to the frequency divider 46. The frequency divider 46 divides the frequency of the clock output from the voltage controlled oscillator 45 at a predetermined frequency division ratio.

Returning to the description of FIG. The TG circuit 9 extracts a predetermined timing signal from the clock signal supplied from the PLL circuit 7 and supplies the same to the TE signal generation circuit 10. T
The E signal generation circuit generates a tracking error signal using, for example, the radial push-pull signal RPP1 at time T1 and the radial push-pull signal RPP2 at time T2 sampled and held based on the timing signal from the TG circuit 9, The data is supplied to the servo controller 5.

As shown in FIG. 8, grooves and lands are formed alternately in the disk radial direction on the disk 1, and the recording tracks are, for example, grooves (or lands). Clock marks are periodically formed on the recording tracks.

Next, a master clock generation process of the information recording / reproducing apparatus will be described with reference to a flowchart of FIG. This processing is mainly performed in the PLL circuit 7. In step S1, the optical pickup 3
The light reflected from the disk 1 is detected by the photodetector 27-2, and the detected current is output to the IV conversion matrix 4. In step S2, the IV conversion matrix 4
The current signal input from the photodetector 27-2 is converted into a voltage signal, and the TPP signal = (E + F)-(G + H), which is the difference between the tangential reflected light of the disk 1 in the laser spot, is calculated. I do. The IV conversion matrix 4 outputs a TPP signal to the PLL circuit 7.

In step S3, the sample and hold circuits 41-1 to 41-4 of the PLL circuit 7
The TPP signal is sampled and held at a predetermined different timing synchronized with the PLL clock fed back from 6, and is output as a digital signal to the subtraction circuit 42-1 or 42-2. In this case, the sample-and-hold circuit 41 responds to the PLL clock i as shown in FIG.
-1 samples and holds the value PP (i-2) of the TPP signal corresponding to the timing of the clock of i-2, and
Output to The sample and hold circuit 41-2 has an i-1
TPP signal value PP (i-1) corresponding to the clock timing of
Is sampled and held and output to the subtraction circuit 42-1.
The sample and hold circuit 41-3 samples and holds the value PP (i + 1) of the TPP signal corresponding to the timing of the clock of i + 1, and outputs it to the subtraction circuit 42-2. Further, the sample and hold circuit 41-4 samples and holds the value PP (i + 2) of the TPP signal corresponding to the timing of the clock of i + 2, and outputs the value to the subtraction circuit 42-2.

The subtraction circuit 42-1 converts PP (i-2) to PP (i-1).
, And outputs the operation result to the subtraction circuit 42-3. The subtraction circuit 42-2 subtracts PP (i + 2) from PP (i + 1) and outputs the operation result to the subtraction circuit 42-3. Subtraction circuit 42-3
Is PP (i-2) -PP (i-1) input from the subtraction circuit 42-1.
From PP (i + 1) -PP (i +
2) is subtracted, and the calculation result {PP (i-2) -PP (i-1)}-{PP (i +
1) -PP (i + 2)} as a phase error signal.
Output to The D / A converter 43 converts the phase error signal, which is a digital signal, into an analog signal and outputs the analog signal to the low-pass filter 44. The low-pass filter 44 removes a high-frequency component from the input phase error signal and outputs the low-frequency component as a control voltage to the voltage-controlled oscillator 45. The voltage control oscillator 45 oscillates a clock having a frequency corresponding to the input control voltage and outputs the clock to the frequency divider 46. The frequency divider 46 divides the frequency of the clock output from the voltage controlled oscillator 45 and outputs the result to each unit as a clock having a predetermined frequency.

Next, the phase relationship between the TPP signal and the PLL clock will be described. As shown in FIG. 6A, a PLL clock having an accurate frequency and phase is oscillated, and four different timings of TPP signals PP (i-2), PP (i-1), PP (i + 1), and
When the absolute value of the level of PP (i + 2) is equal and the level of the phase error signal is 0, the voltage controlled oscillator 45 oscillates while maintaining this clock. As shown in FIG. 6B, the phase of the clock advances, and the TPP signals P at four different timings
If the absolute values of the levels of P (i-2), PP (i-1), PP (i + 1), and PP (i + 2) are different and the level of the phase error signal is negative,
The voltage controlled oscillator 45 oscillates by delaying the phase of this clock. As shown in FIG. 6C, the phase of the clock is delayed, and the TPP signals PP (i-2) and PP (i-
If the absolute values of the levels 1), PP (i + 1), and PP (i + 2) are different and the level of the phase error signal is positive, the voltage controlled oscillator 45 advances the phase of this clock. Oscillate.
Therefore, after all, the servo of the PLL is operated so that the phase error signal becomes zero.

As shown in FIG. 7, when the clock mark is smaller than that in FIG. 6 (in order to record and reproduce information at high density, the clock As can be seen from the waveform of the TPP signal, the zero-cross point can be specified (the jitter is small), so that a clock can be generated from the two TPP signals. In this case, for PLL clock i, PL
The sample and hold circuit 41-1 of the L circuit 7 samples and holds the value PP (i-1) of the TPP signal corresponding to the clock timing of i-1 and outputs it to the subtraction circuit 42-1. The sample-and-hold circuit 41-3 samples and holds the value PP (i) of the TPP signal corresponding to the timing of the clock of i and outputs it to the subtraction circuit 42-2. The sample and hold circuits 41-2 and 41-4 do not sample and hold the TPP signal and output 0 to the subtraction circuits 42-1 and 42-2, respectively.

The subtraction circuit 42-1 outputs PP (i-1) to the subtraction circuit 42-3. The subtraction circuit 42-2 outputs PP (i) to the subtraction circuit 42-3. The subtraction circuit 42-3 converts the PP (i-1) input from the subtraction circuit 42-1 into a subtraction circuit 4-3.
Subtract the input PP (i) from 2-2, and calculate the result PP (i-1)
-PP (i) is output to the D / A converter 43 as a phase error signal. The processing after the D / A converter 43 is the same as the example shown in FIG.

[0034]

As described above, according to the information recording / reproducing apparatus according to the first aspect and the information recording / reproducing method according to the third aspect, a clock is generated based on TPP signals at different timings. Therefore, information can be recorded and reproduced at a higher density.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an information recording / reproducing apparatus to which the present invention has been applied.

FIG. 2 is a block diagram showing a configuration of an optical pickup 3 of FIG.

FIG. 3 is a diagram illustrating the photodetector 27 of FIG. 2;

FIG. 4 is a block diagram illustrating a configuration of a PLL circuit 7 of FIG. 1;

FIG. 5 is a flowchart illustrating a clock generation process of the information recording / reproducing apparatus of FIG. 1;

FIG. 6 is a diagram illustrating step S3 in FIG. 5;

FIG. 7 is a diagram illustrating step S3 in FIG. 5;

FIG. 8 is a diagram illustrating waveforms of a clock mark and a tangential push-pull signal.

FIG. 9 is a diagram illustrating a photodetector.

FIG. 10 is a diagram comparing the relative sizes of a low density clock mark and a high density clock mark with respect to a laser spot.

[Explanation of symbols]

1 disk, 2 spindle motor, 3 optical pickup, 4 IV conversion matrix, 5 servo controller, 6 thread motor, 7 PLL circuit,
8 A / D converter, 9 TG circuit, 10 TE signal generation circuit, 11 data detection circuit, 12 laser control circuit, 21 laser diode, 22 collimator lens, 23 beam splitter, 24 objective lens, 25 lens, 26 cylindrical lens,
27 Photodetector, 28 Anti-wavelength plate, 29
Polarizing beam splitter, 30 lenses, 31 lenses, 32 lenses, 33 lenses, 41 sample and hold circuit, 42 subtraction circuit, 43 D / A
Converter, 44 low pass filter, 45 voltage controlled oscillator, 46 frequency divider

Claims (3)

[Claims] A land and a groove formed concentrically or spirally, and one of the land and the groove is a recording track of data, and the recording track periodically reflects light from another area. An information recording / reproducing apparatus that optically records or reproduces information on a disk on which a clock region having a different rate is formed; a detecting unit that detects reflected light of light applied to the recording track; Information recording / reproducing comprising: a first generating means for generating a tangential push-pull signal from an output of the means; and a second generating means for generating a clock from a difference between the tangential push-pull signals at different timings. apparatus. 2. The information recording / reproducing apparatus according to claim 1, wherein the second generation means generates a clock based on four different timing tangential push-pull signals. 3. A land and groove formed concentrically or spirally, and one of the land and the groove is used as a data recording track, and the recording track periodically reflects light from another area. An information recording / reproducing method for optically recording / reproducing information on a disc on which a clock region having a different rate is formed, a detecting step of detecting reflected light of light applied to the recording track; An information recording / reproducing method comprising: a first generation step of generating a tangential push-pull signal from an output of a step; and a second generation step of generating a clock from a difference between tangential push-pull signals at different timings. Method.