JPH03187072A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To increase the recording capacity of an optical disk without exerting an adverse effect upon servo characteristics by performing the recording and reproducing of information in a data area based on a signal to be selected out of plural clock signals according to the position of a track concerned. CONSTITUTION:A modulator 17 and a demodulator 18 for modulating and demodulating a data respectively are operated to perform their duties based on a signal selected by a selecting circuit 13 out of plural clock signals to be outputted from clock regenerating circuits 12a-12e. A clock signal in each zone is selected by the circuit 13 based on a command corresponding to a zone under the scanning of an optical head 3 to be outputted by a control circuit 15. Consequently, servo information of an optical disk 1 is obtained over the whole zones at intervals of a given period of time so that the constant servo characteristics can always be obtained. Then, since the optical disk 1 is formed in order to increase the number of data per track in proportion to the track closer located to the outer circumferential side of the disk, the storage capacity is increased as a whole.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention controls the position of an optical head based on servo information arranged at predetermined intervals on the tracks of an information recording medium to increase the recording capacity. The present invention relates to information recording and reproducing devices that increase the number of users.

[Conventional technology]

2. Description of the Related Art Optical disk recording and reproducing devices have been known as information recording and reproducing devices that use optical disks as information recording media. In this case, depending on the recording method, CAV or CL
The V method is often used. In the CAV method, the optical disc is rotated at a constant angular velocity and recording is performed using a constant recording clock. On the other hand, in the CLV method, the optical disk is rotated at a constant linear velocity and recording is performed using a constant recording clock.

When recording using the CAV method, the outer circumferential portion of the optical disc has a lower recording density than the inner circumferential portion, but has the characteristic that a desired track can be accessed at high speed. On the other hand, when recording with the CLV method, recording can be performed at a constant linear recording density over the entire surface of the optical disk, so the recording capacity is large, but on the other hand, the number of rotations of the motor that rotates the optical disk must be changed depending on the radial position of the optical disk. Moreover, the desired track can only be accessed at a low speed.

Therefore, while increasing the recording capacity of optical discs,
In order to access the desired track quickly,
The MCAVCAV method has been developed and put into practical use. M.C.A.V.
The CAV system disk is rotated at a constant angular velocity (same as the conventional CAV system), and the data area on the optical disk is divided into a plurality of zones in the radial direction.
By increasing the frequency of the recording clock in the zone near the outer periphery, a decrease in recording density in the outer periphery is suppressed.

By the way, in an optical disk recording/reproducing device, tracking using a continuous servo method and tracking using a sample servo method are well known and adopted as methods for following a light beam from a light emitting means along a track on an optical disk. ing. The continuous servo method obtains position information (tracking error signal) of a light beam by utilizing diffraction of light in a guide groove formed in advance on an optical disk. In other words, there are cases in which recording is performed on the land between the guide grooves and cases in which it is recorded in the in-loop within the guide groove.Since a tracking error signal is always obtained, control is simple and technically efficient. Established. Furthermore, access of the optical head in the radial direction of the optical disk can also be controlled using signals that traverse the tracks. However, it is necessary to resynchronize each sector.

On the other hand, in the sample servo system, two servo areas are provided within the servo area on the track at predetermined intervals in the track direction at positions equidistant from the center of the track in the radial direction.
The positional information of the light beam is obtained based on the difference in the amount of reflected light from each tracking pit. Note that the servo area has a clock pit in addition to the tracking pit. Other than the above servo area, no guide grooves or marks are preformatted. Furthermore, since the servo area and the data area are spatially separated, there is no interference between the reproduction signals of the two during reproduction. However, there are tracking pits all over the optical disk.
Since the spatial and temporal positions of the clock pit are fixed, high accuracy is required on the time axis.

[Problem to be solved by the invention]

However, when increasing the recording capacity using the MCAVCAV method in an optical recording/reproducing device that employs the conventional sample servo method, the recording/reproducing clock and control clock are generated based on pits formed in advance in the servo area. Therefore, if the recording/reproducing clock for each zone set on the optical disk is changed, the arrangement of the servo areas on the track must be changed.

Changing the arrangement of the servo areas changes the detection cycle of servo information, which has a negative effect on servo characteristics. As a result, the servo characteristics must be switched for each zone provided on the optical disk.

Furthermore, since the positions of corresponding clock pits are different in adjacent zones, there is a problem in that continuous recording and reproducing operations performed across zones are hindered.

[Means to solve the problem]

In order to solve the above problems, an information recording/reproducing apparatus according to the present invention provides information in which the servo area is arranged so that the period of the clock signal generated by the clock information changes depending on the radial position of the track. It uses a recording medium and is characterized by the following circuit configuration for recording and reproducing it.

The present invention includes a clock recovery circuit that generates a plurality of clock signals with different periods from the clock information.

The clock regeneration circuit is composed of, for example, a PLL circuit. Further, the present invention includes a selection circuit that selects one specific clock signal from the plurality of clock signals generated by the clock recovery circuit.

The present invention includes a timing generation circuit that controls the detection timing of servo information based on the output of the clock regeneration circuit or the output of the selection circuit. Note that the timing generation circuit must be configured to include a programmable counter. Further, the present invention includes a control circuit that controls the timing generation circuit and the selection circuit, and outputs a command regarding the clock signal to be selected to the selection circuit in accordance with the position of the track.

The present invention further includes a recording and reproducing circuit that records and reproduces information based on the clock signal selected by the selection circuit. Note that the recording/reproducing circuit includes a modulator,
This is due to the configuration including the demodulator and laser drive circuit.

[For production]

According to the above configuration, the clock reproducing circuit generates a plurality of recording/reproducing clocks having different cycles and a control clock based on clock information obtained by reproducing the servo area of the information recording medium. On the other hand, servo information is detected at a detection timing generated by a timing generation circuit based on a plurality of clock signals from a clock reproduction circuit or one clock signal selected by a selection circuit. Note that the selection of the signal by the selection circuit is performed based on a command from the control circuit regarding the clock signal to be selected depending on the position of the track.

Information is recorded and reproduced in the data area based on the detected clock information. That is, recording and reproducing information in the data area is performed by a recording and reproducing circuit based on a clock signal selected by a selection circuit from among a plurality of clock signals according to the position of the track.

[Example 1] An example of the present invention will be described below based on FIGS. 1 to 6.

FIG. 2 shows an optical disc 1 as an information recording medium according to the present invention. The optical disc 1 has a diameter of
For example, it is 130 mm, and is of a sample servo type in which servo areas (not shown) and data areas (not shown) are arranged alternately on the track. As shown in FIG. 2, the optical disc 1 includes, for example, A and B in order from the inner circumference side.
Five zones: 5C, 5D, and E (for convenience, -
A is divided into
Each zone -D has 4445 tracks, the E zone has 2220 tracks, and the total number of tracks on the optical disc 1 is 20000. The tracks of the optical disc 1 are formatted such that the frequency of the clock for recording and reproducing the servo area and data area and the clock for controlling the zone near the outer circumference is higher (described later).

The arrangement of the servo area and the data area on the track will be explained based on FIG. 3 as follows.

The arrangement of the servo area (SA) and data area (DA) shown in FIGS. 3(a) to (e) is the same as that shown in FIG.
Each corresponds to the H zone. In the A zone, as shown in the figure (a), there is a servo area of 2 bytes long and a
Data areas each having a length of 6 bytes are arranged alternately. The servo area and data area are set as one set (segment),
A total of 1376 sets (segments) are provided on each track belonging to the A zone. Therefore, the number of data per track in the A zone is 22016 bytes.

In the B zone, as shown in FIG. 5B, one segment consists of a 2-byte long servo area and a 20-byte long data area. Each trunk, like the A zone, is limited to a configuration containing 1376 segments. Therefore, the number of data per track in B zone is
It is 27520 bytes. The configuration of each track belonging to the C-E zone is shown in Table 1 below.

As is clear from Table 1, the optical disc 1 is configured such that the number of data (number of bytes) per track increases in the zone closer to the outer circumference. This is done by changing the frequencies of the recording/reproducing clock and control clock for each zone. here,
Regarding the frequencies of the recording/reproducing clocks and control clocks of zones A-H, the optical disc 1 has a frequency of, for example, 1/min.
If it is rotating at a constant angular velocity of 800 revolutions, then A
The frequency of the recording/reproducing clock and control clock in the zone is 11.1456MHz, and in the B zone, the frequency is 11.1456MHz.
3.6224M) tz, 16. in C zone. 0992
MHz, 18.5760 Mllz in D zone,
In the E zone, it is 21,0528 MHz.

Here, the recording/reproducing clock in zone A-E,
The relationship between the frequency of the control clock and the pits in the servo area will be explained based on FIG. 4 as follows.

FIGS. 4(a) to 4(e) are diagrams each schematically explaining the arrangement of the servo areas (SA) in the segments of each zone of A to E. Servo area of each zone of A-E (SA
) includes a pair of tracking pits PA-PB and one clock pit PC. The tracking pits PA and PB are arranged on the track at predetermined intervals in the track direction and at equal distances from the center of the track in the radial direction. On the other hand, the clock pit PC is the tracking pit P on the center of the track.
B is arranged with a predetermined distance therebetween.

As shown in FIGS. 4(a) to 4(e), since the frequencies of the recording/reproducing clock and the control clock are different in each zone A to E, the time intervals between pits are different. However, for the clock cycle in each zone, the distance between the corresponding tracking pits PA-PB and clock pit PC, and the clock pit PC
and the start position of the data area (DA) have an interval corresponding to the same number of clocks. The clock pit PCs are arranged at predetermined angles radially from the center of the optical disc l over all zones A to H.

The configuration of an optical recording and reproducing apparatus as an information recording and reproducing apparatus according to the present invention will be described below based on FIG.

As shown in FIG. 1, the present invention mainly includes an optical disc l, a disc rotation drive motor 2, an optical head 3 as an optical system, a preamplifier 10, and a clock pit detection circuit 11.
, clock regeneration circuit 12, selection circuit 13, timing generation circuit 14, control circuit 15, tracking error generation circuit 16, modulator 17, demodulator 18, laser drive circuit 19,
and a servo circuit 20. The clock regeneration circuit 12 includes five clock regeneration circuits 12a to 1.
It is composed of 2e. In addition, the modulator 17 and the demodulator 1
8 and the laser drive circuit 19 constitute a recording/reproducing circuit.

The optical disc 1 is rotated by a disc rotation drive motor 2 at a constant angular velocity of 1800 revolutions per minute.

Light beam emitted by optical head 3 (not shown)
is configured to scan along a track on the optical disk 1 by tracking control. In the sample servo method, the tracking pit PA in the servo area SA
When the -PB is irradiated with a light beam, a photodetector (not shown) in the optical head 3 outputs a voltage value that changes depending on the amount of light reflected therefrom. The output of the optical head 3 is then sent to a tracking error generation circuit 16. In the tracking error generation circuit 16, the difference between the voltage values corresponding to the tracking pits PA and PB is determined, and then sent as a tracking error signal to the servo circuit 20, which will be described later. The tracking error signal is sampled at regular time intervals each time the optical beam from the optical head 3 scans the tracking pits PA-PB formed in the servo areas SA of zones A-E of the optical disc 1. It has become. This sampling frequency is 41.28k)[z. This can be obtained by considering that, as mentioned above, there are 1376 segments per track over all zones A to E, and that the optical disk I rotates at 1800 revolutions per minute.

The servo circuit 20 is configured to generate a drive signal for controlling the position of the optical head 3 based on the tracking error signal. The servo circuit 20 has a configuration including a filter circuit (not shown) having constant characteristics over all zones A to E, and a driver circuit (not shown).

Recording data sent from an external device is sent to the modulator 17. The modulator 17 modulates the recorded data (
For example, the signal is changed to 4/15 (1) and sent to the laser drive circuit 19. The laser drive circuit 19 controls the amount (power) of the light beam irradiated from the optical head 3 based on the modulated recording data so that recording is performed in a desired part of the data area DA of the optical disc 1. It has become. For example, when a high-power light beam is irradiated onto a desired portion within the data area DA of the optical disc l, the temperature of the portion rises and bits are formed, thereby recording data. on the other hand,
When a desired area is irradiated with a light beam with a weak power that is not sufficient to form bits as in recording, the reflected light from the area is detected by a photodetector (not shown) in the optical head 3. ) detected by The photodetector converts the signal into an electrical signal that changes depending on the recording state of the area irradiated with the light beam, and then sends it to the preamplifier 10. In the preamplifier 10, the electrical signal from the optical head 3 is amplified and sent to the demodulator 18. The demodulator 18 performs demodulation, which is the reverse process of the modulator 17, and then outputs reproduced data corresponding to the recorded data to an external device.

Reflected light from the optical disc 1 during reproduction is sent to a clock bit detection circuit 11 via an optical head 3 and a preamplifier 10. When generating the tracking error signal, tracking bits PA-PB (fourth
A clock signal is required to accurately extract the reproduced signal obtained by reproducing the data (see figure), and this can be obtained from the reproduced signal of the clock pit PC. At this time, the clock bit detection circuit 11 detects the clock pit PC. In other words, the clock bit detection circuit 11
Now, among the input reproduction signal strings, which one is from the clock pit PC?
is identified.

The output of the clock bit detection circuit 11 is sent to the clock recovery circuit 12. The clock reproduction circuit 12 determines the reproduction frequency (the above-mentioned sampling frequency) of the clock pit PC based on the output from the clock bit detection circuit 11.
A clock signal having a frequency that is an integral multiple of is generated in the clock recovery circuits 12a to 12e.

For example, the clock regeneration circuit 12a may be configured to
The clock regeneration circuit 12b generates a 11.1456M7 clock signal corresponding to the zone, the clock regeneration circuit 12b generates a 13.6224MHz clock signal corresponding to the B zone, and the clock regeneration circuit 12c generates a 16.0992MHz clock signal corresponding to the C zone.
Generates a MHz clock signal and uses a clock regeneration circuit 12
d generates a clock signal of 18.5760 MHz corresponding to the D zone, and the clock recovery circuit 12e generates a clock signal of 21.0528 MHz corresponding to the C zone.

The clock recovery circuits 12a to 12e will be explained as follows based on FIG.

As shown in FIG. 5, clock recovery circuits 12a to 12e
is composed of a PLL (Pase Locked Loop) circuit. That is, the relock regeneration circuit 12
A to 12e each consist of a phase comparator 40, a low-pass filter 41, a voltage-controlled oscillator 42, and a frequency divider 43, and the output of the frequency divider 43 and the clock signal input from the outside are reproduced from the PC. The phase with the signal is compared by the phase comparator 40, and the voltage controlled oscillator 42 is controlled so that the phase difference becomes zero. Voltage controlled oscillator 4
The clock signal output from 2 becomes the recording/reproducing clock and control clock for each zone A to E.
The frequency division ratio of the frequency divider 43 is determined by the clock regeneration circuit 12a-12.
270.330.390 and 450.e respectively.
and 510, so that the voltage controlled oscillator 42 generates a clock signal having the predetermined frequency.

Outputs of the clock recovery circuits 12a to 12e are connected to a selection circuit 13 and a timing generation circuit 14, respectively. The extraction timing of the reproduction signal obtained by reproducing the reflected light from the tracking pits PA and PB is controlled by the timing generation circuit 14 based on a plurality of clock signals from the clock reproduction circuits 12a to 12e.

At this time, the timing generation circuit 14 generates the reproduction signal extraction timing for each zone based on the command output from the control circuit 15 according to the zone that the optical head 3 is scanning. There is. The timing generation circuit 14 will be explained below based on FIG.

FIG. 6 shows the configuration of the timing generation circuit 14, and the timing generation circuit 14 mainly includes the counter circuits 30a to 30e1 and the selection circuit 31. When a clock pit PC is detected,
The counter circuits 30a to 30e are connected to the clock regeneration circuit 12.
Start counting the clock signals output from a to L2e and start counting the tracking pits PA-PB of the next segment.
Generate the extraction timing. Then, the selection circuit 31 selects the counter circuit 30 based on the command from the control circuit 15.
One extraction timing is selected from among a plurality of extraction timings outputted from a to 30e. Based on the reproduction of the clock pit PC, the reproduction of the tracking pits PA-PB in the next segment is performed after each zone has counted a different number of clocks for each control clock (see Figures 3 and 4). .

That is, in the A zone, the counter circuit 30a is 24
After counting 6 clocks, the tracking pit PA
is now being played. On the other hand, after the counter circuit 30a counts 251 clocks, the tracking pit PB is reproduced. In the B-E zone, the counter circuits 30b to 30b
After each count 30e counts 306.366.426.486, the tracking pit PA is reproduced. On the other hand, counter circuit 3
0b to 30e are each 311.371.431.49
After each count of 1 is counted, the tracking pit PB is reproduced.

A modulator 17 that modulates and demodulates data, and a demodulator 1
8, the selection circuit 13 selects one of the plurality of clock signals output by the clock regeneration circuits 12a to 12e.
This is carried out based on the clock signal selected by. At this time, the selection circuit 13 outputs the output from the control circuit 15.
The clock signal for each zone is selected based on a command corresponding to the zone that the optical head 3 is scanning.

According to the above configuration, the servo information obtained from the optical disc l is obtained at constant time intervals over all zones, so that constant servo characteristics can always be obtained. In addition, since the clock pit PC is arranged in a straight line from the center of the optical disc 1 toward the outer periphery of the optical disc 1 at a constant angle across all zones, even when the optical disc 3 moves in the radial direction, it always Clock regeneration circuits 12a to 12
e is in a locked state, and the generation of the recording/reproduction clock and the timing generation for obtaining the tracking error signal only need to be controlled by the selection circuit 13 and the selection circuit 31, respectively, and the optical head 3 is immediately moved at the destination. Tracking operations and recording/reproducing operations can be performed. Also, the zone near the outer periphery of the optical disc l is
Since the number of data per track is increased, the overall recording capacity is increased.

(The following is a blank space) [Example 2] The example shown in FIGS. 7 and 8 shows another example of the present invention. For convenience of explanation, members having the same functions as those in the first embodiment described above are given the same reference numerals, and detailed explanation thereof will be omitted.

As shown in FIG. 7, the timing generation circuit 14 selects a clock signal from among a plurality of clock signals having different frequencies outputted from the clock regeneration circuits 12a to 12e by the selection circuit 13 under the command of the control circuit 150. Tracking bits PA-PB
The point of generating the extraction timing of the playback signal from
This is a different feature from the embodiments described above.

The configuration of the timing generation circuit 14 will be explained below based on FIG.

The timing generation circuit 14 has a structure including a programmable counter 30, as shown in FIG. The programmable counter 30 starts counting the number of clock signals from the selection circuit 13 when the clock signal PC is reproduced. That is, in each zone A to E, the programmable counter 30 counts 246.306.366.426.486 clocks, and then reproduces the tracking bit PA in the next segment. On the other hand, the programmable counters 30 each have 251.311
．． After counting the number of clocks of 371.431.491, the tracking bit PB in the next segment is reproduced. These tracking bits PA
- Setting of a predetermined count required for generating the PB extraction timing is programmable by the control circuit 15.

In this embodiment, the circuit configuration of the timing generation circuit 14 can be simplified as described above. However, each time the optical head 3 passes the boundary of the A-H zone, it is necessary to initialize the timing generation described above, and during this period, it is necessary to hold the tracking error signal.

[Embodiment 3] The examples shown in FIGS. 9 to 11 show still another embodiment of the present invention. For convenience of explanation, members having the same functions as those in the first embodiment described above are given the same reference numerals, and detailed explanation thereof will be omitted.

This embodiment differs from the above-described embodiments 1 and 2 in that, as shown in FIG. 9, the clock recovery circuit includes two clock recovery circuits 12a and 12b. The clock regeneration circuits 12a and 12b perform the above-mentioned 11.1456MI (z, 1) under the control of the control circuit 15.
3.6224MHz16, 0992MHz, 18.5
Clock signals having five different frequencies, 760 MHz and 21.0528 MHz, are generated.

That is, one of the clock regeneration circuits 12a and 12b is configured to generate a recording/reproduction clock and a control clock for the zone that the optical head 3 is scanning, and the other is configured to generate a recording/reproduction clock and a control clock for the zone that the optical head 3 is scanning next. It is controlled by a control circuit 15 to generate a recording/reproducing clock and a control clock.

Further, the timing for extracting the reproduction signal from the tracking bits PA-FB is generated by the timing generation circuit 14 based on the clock signal output from the clock reproduction circuits 12a and 12b. At this time, the extraction timing is set by the control circuit 15 according to the zone being scanned by the optical head 3.
This is done based on the directives of

FIG. 10 shows the clock regeneration circuit 12a shown in FIG.
12b is a block diagram showing a PLL circuit forming part 12b.

The clock recovery circuit 12a12b mainly includes a phase comparator 40, a low-pass filter 41, a voltage-controlled oscillator 42,
and a programmable frequency divider 43, whose operation is basically the same as that shown in FIG.

The programmable frequency divider 43 has a frequency division ratio of 270.330.390.45 based on a command from the control circuit 15.
0, and 510. The voltage controlled oscillator 42 has a center frequency of 16.0992 MHz.
It has a pull-in and lock range for the five types of frequencies (11,1456 MHz to 21.0528 MHz).

FIG. 11 shows an example of the configuration of the timing generation circuit 14 shown in FIG. 9. In FIG. The circuit 14 includes programmable counters 30a and 30b and a selection circuit 31. This is basically the same as that shown in FIG.
a is set to a count value corresponding to the zone being scanned by the optical head 3, and generates the extraction timing of the tracking bits PA-PB. The selection circuit 31 is configured to select the extraction timing of the tracking bits PA to PB in accordance with the zone.

On the other hand, the programmable counter 30b is set to a count value corresponding to another zone to be scanned next by the optical head 3, and generates the extraction timing of the tracking bits PA-PB.

In this embodiment, the clock regeneration circuits 12a and 12b
, and programmable counters 30a and 30b are switched and used each time the optical head 3 passes, so the circuit configuration can be simplified.

In addition, the daily operation of the modulator 17 that modulates and demodulates recording data and the demodulator is performed by clock regeneration circuits 12a and 12.
This is performed based on the clock signal selected by the selection circuit 13 from among the clock signals from b.

[Embodiment 4] The example shown in FIG. 12 shows still another embodiment of the present invention. For convenience of explanation, members having the same functions as those in the first embodiment described above are given the same reference numerals, and detailed explanation thereof will be omitted.

In this embodiment, as shown in FIG. 12, the clock regeneration circuit 12 has only one clock regeneration circuit;
It is controlled by a control circuit 15 to generate a recording/reproducing clock and a control clock in the zone that the optical head 3 is scanning. Tracking bit PA
-The timing of extraction from PB is determined by the clock recovery circuit 12.
The timing generation circuit 14 generates the clock signal based on the clock signal output from the timing generation circuit 14. At this time, the extraction timing is generated for each zone based on a command from the control circuit 15 corresponding to the zone that the optical head 3 is scanning. The configuration of the clock regeneration circuit 12 is the same as that shown in the third embodiment described above, and the timing generation circuit 14 is the same as that shown in FIG.

In this embodiment, the circuit configuration can be further simplified compared to Embodiment 3, but the clock regeneration circuit 12 must be synchronized every time the optical head 3 passes through zones A-E. access speed tends to be slow.

Note that the optical disc l described in Examples 1 to 4 above
The numerical values such as the number of zone divisions and the number of segments per track are not limited to these values.

〔Effect of the invention〕

As described above, the information recording and reproducing device according to the present invention includes a clock reproducing circuit that generates a plurality of clock signals with different periods from the clock information, and a control circuit that generates a plurality of clock signals generated by the clock reproducing circuit. a selection circuit that selects one specific clock signal based on a command from the clock signal; a timing generation circuit that controls the detection timing of the servo information based on the output of the clock regeneration circuit or the output of the selection circuit; a control circuit that controls the generation circuit and the selection circuit and outputs to the selection circuit a command regarding a clock signal selected according to the position of the track; and recording of information based on the clock signal selected by the selection circuit; and a recording/reproducing circuit that performs reproduction, and the servo area is arranged so that the period of the clock signal generated by the clock information changes depending on the radial position of the track.

As a result, even if the recording/reproduction clock of each zone set on the information recording medium is changed, the detection cycle of servo information will not change and there will be no effect on the servo characteristics. There is no need to switch the servo characteristics for each zone.

Furthermore, since the positions of the corresponding clock bits are the same in adjacent zones, the continuous recording/reproducing operation that spans between zones can also be easily performed.

[Brief explanation of drawings]

1 to 6 show one embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of an information recording/reproducing apparatus according to the present invention. FIG. 2 is a diagram showing an example of zone division of an information recording medium. FIG. 3 is a diagram showing the arrangement of servo areas and data areas in each zone. FIG. 4 is a diagram showing the relationship between the servo area and data area in each zone and the clock signal. FIG. 5 is a block diagram showing the configuration of the clock recovery circuit. FIG. 6 is a block diagram showing the configuration of the timing generation circuit. 7 and 8 show other embodiments of the invention. FIG. 7 is a block diagram showing the configuration of another information recording/reproducing apparatus according to the present invention. FIG. 8 is a block diagram showing the configuration of the timing generation circuit shown in FIG. 7. 9 to 11 show still other embodiments of the present invention. FIG. 9 is a block diagram showing the configuration of still another information recording/reproducing apparatus according to the present invention. FIG. 10 is a block diagram showing the configuration of the clock recovery circuit shown in FIG. 9. FIG. 11 is a block diagram showing the configuration of the tying generation circuit shown in FIG. 9. FIG. 12 shows still another embodiment of the present invention, and is a block diagram showing its configuration. 1 is an optical disk, 3 is an optical head, 12 is a clock regeneration circuit, 13 is a selection circuit, 14 is a timing generation circuit, 1
5 is a control circuit, and 16 is a tracking error generation circuit. Patent creator Sharp Co., Ltd.

Claims (1)

[Claims] 1. A disk-shaped information recording medium in which servo areas in which pits containing servo information and clock information are formed in advance on tracks and data areas in which information is recorded are provided alternately. In an information recording and reproducing device that records and reproduces information in the data area by rotating the optical system at an angular velocity of a clock regeneration circuit that generates a plurality of clock signals with different periods; a selection circuit that selects one specific clock signal from the plurality of clock signals generated by the clock regeneration circuit based on a command from a control circuit; a timing generation circuit that controls the detection timing of the servo information based on the output of the clock regeneration circuit or the output of the selection circuit; and a timing generation circuit that controls the timing generation circuit and the selection circuit and selects the timing according to the position of the track. a control circuit that outputs a command regarding a clock signal to be selected to a selection circuit, and a recording and reproducing circuit that records and reproduces information based on the clock signal selected by the selection circuit,
An information recording/reproducing apparatus characterized in that the servo areas are arranged so that the period of the clock signal generated by the clock information changes depending on the radial position of the track.