JPH02162578A - Optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To promote the utilization efficiency of a recording medium by converting a fundamental clock into a channel clock of a frequency synchronized with an optical disk and corresponding to a recording track of the disk. CONSTITUTION:The fundamental clock of a constant frequency fi synchronized with the disk 10 is generated by a clock regenerating circuit 30 based on a regenerating output of a clock information pit obtained from the recording track in accordance with the rotation of the optical disk 10. The frequency fi is converted by multiplying it by M/N by a frequency converter circuit 50 into the channel clock of the frequency fz. A frequency conversion ratio of the circuit 50 is changed by a system controller 41 in accordance with a recording track number of the disk 10. The channel clock converted in such a way is synchronized with the optical disk, having the frequency corresponding to the track number. Consequently, the recording and reproducing a bit of information in an approximately uniform recording density are performed for each recording track on the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention provides clock information pits arranged radially around the central hole in an annular recording surface extending around the central hole, and a clock information pit between the clock information pits. An optical disk recording and reproducing apparatus that records and reproduces information on and from the recording tracks while rotating an optical disk at a constant angular velocity, the optical disk having a plurality of recording tracks having a data recording area formed in a circular pattern surrounding the central hole. .

B. Summary of the Invention The present invention provides a recording track in which clock sensing pits are arranged radially around the central hole on an annular recording surface portion extending around the central hole, and the space between the clock information pits is a data recording area. In an optical disc recording and reproducing apparatus that records and reproduces information on the recording track while rotating an optical disc formed in a large number of circular patterns surrounding the central hole at a constant angular velocity, clock information of each recording trunk is provided. By frequency converting the basic clock of a predetermined frequency f generated from the playback output of the pit to a channel clock of frequency f2 which is M/N times the frequency corresponding to the recording trunk and performing recording and playback operations, high quality and high efficiency can be achieved. This enables recording and reproducing operations.

C. Prior Art In recent years, disk-shaped recording media such as optical disks and magneto-optical disks that utilize optical or magneto-optical signal recording and reproducing methods have been developed and are being supplied to the market.

These disk-shaped recording media include read-only memories (ROM) such as so-called compact discs (CDs), etc.
mea+ory) type recording media, or 1 on the user side.
So-called write-once type recording media on which data can be written once, and recording media on which data can be rewritten (so-called override), such as magneto-optical disks, are known.

In an optical disk recording and reproducing device that uses an optical disk as a recording medium using an optical or magneto-optical signal recording and reproducing method, a spindle servo rotates the optical disk at a constant angular velocity or a constant linear velocity.
A focus servo or a tracking servo is applied to an optical head that has a built-in laser diode that outputs a laser beam with a length for recording and reproducing information, a photodiode that detects the reflected light of the laser beam from the optical disk, etc., and the recording track of the optical disk is Information is recorded and reproduced by scanning with laser light.

Furthermore, as one of the technologies for realizing a unified recording format for the various optical disks mentioned above, similar to the so-called sector servo in hard disks in the field of magnetic disks, concentric or spiral shaped Servo signals such as clock information pits and tracking information pits are recorded (so-called preformat) on the track at predetermined intervals or at predetermined angles, and these discrete servo signals are sampled and held when the disk is driven to rotate. A so-called sampled servo technique has been proposed in which continuous servo control is performed. As this type of optical disk, for example, an optical disk (10) having a recording formant as shown in FIG. 1O is conventionally known.

In the optical disc (10) shown in FIG. 1O, an annular label portion (12) is arranged around a central hole (11), and an annular recording surface portion (13) that extends around the label portion (12). ) is provided. The recording surface portion (13) has concentric recording tracks (
TK) is provided, and each round of the track, that is, one round track, is divided into a predetermined number m (for example, m=32) of sectors (SC
I), (SC2) to (SC,), and this optical disc ( 10), and is provided with such recording tracks (T).
10) is attached to an optical disc recording/playback device and the arrow (
R) and used for information recording or information reproduction using a light beam.

Each sector (SCI) (S
Each of CZ) to (SC,) is provided with an address information section (AD) on its starting end side, and a predetermined section arranged along the recording track (TK) following this address information section (AD). It is assumed that the number n (for example, n=43) blocks (BLI), (at, z) to (BL,) are included. The above blocks (iI,), (uL
z) to (B1), for example, each sector (SC,)
, (sc,) ~ (SC,) block (BLI
), a plurality of blocks having a corresponding relationship between the respective sectors are arranged in the radial direction of this optical disk (10). Each sector (SCI), (Set) Each of the blocks (BLI), (atz) to (BL,) in ~(SC,) is provided with a servo information area (ARo) on its starting end side, and an information writing area (ARo) following the servo information area (ARo).
is provided to constitute a unit record division. And each of the above blocks (BL, ), (Bt, z)
In the servo information area (ARo) of ~(BL,,), tracking information pits (QA) and (QI) are located shifted outward and inward across the trunk centerline (K,).
and a clock information pit (Qc) located on the truck centerline (Kc).
, ) are formed in advance with predetermined mutual spacing. The above clock information pits (Q,) are shown in FIG. 11 for each recording track (TK, l), (TK, l), (
As shown in the enlarged view of TK.

In an optical disc recording and reproducing apparatus using the optical disc (10) as a recording medium, as shown in FIG. ) reproduction output φ.

A so-called PLL clock recovery operation is performed based on the channel clock φ. and this channel clock φ. is used to record and reproduce information in the information writing area (AR).

D Problems to be Solved by the Invention By the way, in the conventional optical disc recording and reproducing apparatus that records and reproduces information while rotating an optical disc (lO) employing the sampling-for-manro at a constant angular velocity as described above, 10) recording track (T
K) A channel clock φ formed by a clock reproduction operation by a so-called PLL based on a reproduction output φ obtained at each predetermined rotation angle by the clock information pit (Q,) above. Since information is recorded and reproduced in the information writing area (ARo) of each recording track (TK) using The problem was that it was bad.

In view of the above-mentioned conventional problems, the present invention provides clock information pits arranged radially around the central hole in an annular recording surface extending around the central hole. While rotating an optical disk, in which recording tracks serving as data recording areas are formed in a number of circular patterns surrounding the central hole, at a constant angular velocity,
The purpose of this is to improve the utilization efficiency of the recording medium in an optical disc recording/reproducing device that records and reproduces information on the above recording tracks, so that the recording density of information is the same between the inner and outer recording tracks. High quality,
An object of the present invention is to provide an optical disc recording and reproducing device with a novel configuration that enables highly efficient recording and reproducing operations.

E. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method in which clock information pits are arranged radially around the central hole in an annular recording surface extending around the central hole. , while rotating an optical disk at a constant angular velocity, in which a recording track having a data recording area between the clock information pits is formed in a number of circular patterns surrounding the central hole, information is recorded and reproduced on the recording track. In the optical disc recording and reproducing apparatus, the clock reproducing means generates a basic clock having a predetermined frequency r from the reproduced output of the clock information pit, and the clock frequency f of the basic clock.
, and a control means for changing the frequency conversion ratio M/N of the frequency conversion means in accordance with the recording track number of the optical disc. The present invention is characterized in that information is recorded and reproduced on the recording track using the channel clock frequency-converted by the frequency conversion means. Further, in the optical disc recording/reproducing apparatus, the reproduction processing system to which the frequency-converted channel clock obtained by the frequency converting means is supplied is provided with phase control means for the channel clock, and The present invention is characterized in that the phase of the channel clock is controlled so that the level difference between the leading edge portion and the trailing edge portion of the reproduced signal becomes zero. Furthermore, in the optical disc recording and reproducing apparatus, the present invention provides a reproduction processing system including a digital equalizer for reproduction signals reproduced from the recording trunk of the optical disc,
The digital equalizer is characterized in that the digital equalizer is operated using a frequency-converted channel clock obtained by the frequency conversion means.

F Function In the optical disc recording/reproducing apparatus according to the present invention, the clock reproducing means reads the optical disc based on the reproduction output of the clock information pit obtained at each predetermined rotation angle from the recording track of the optical disc which is rotationally driven at a constant angular velocity. A basic clock with a constant frequency f1 synchronized with is generated. Further, the frequency converting means converts the clock frequency of the basic clock "," by M/N times to form a channel clock of frequency f2 of f, -r, .M/N.And,
The control means changes the frequency conversion ratio M/N of the frequency conversion means in accordance with the recording track number of the optical disc. The channel clock frequency-converted by the frequency conversion means is synchronized with the optical disc, and furthermore,
Frequency r2 according to the recording track number of the optical disc
will be changed. By using the channel clock frequency-converted by the frequency converting means, information can be recorded and reproduced at approximately average recording density on each recording track on the optical disk.

Moreover, in the optical disc recording and reproducing apparatus according to the present invention,
The channel clock phase control means provided in the reproduction processing system to which the frequency-converted channel clock 18 is supplied by the frequency conversion means controls the leading and trailing edges of the reproduction signal reproduced from the recording track of the optical disk. The phase of the channel clock is controlled so that the level difference between the sections is t. By providing the phase control means, the reproduction processing system can reliably perform the reproduction operation using the pit clock in the optimum phase state.

Furthermore, in the optical disc recording and reproducing apparatus according to the present invention, the digital equalizer provided in the reproducing processing system operates with the frequency-converted channel clock obtained by the frequency converting means, thereby reproducing data from the recording track of the optical disc. The equalizer characteristics applied to the reproduced signal are automatically changed, and the optimum equalizer processing operation is always performed on the reproduced signal.

G. Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The embodiment shown in the block diagram of FIG. 1 is an example in which the present invention is applied to an optical disc recording and reproducing apparatus that uses a write-once optical disc (10) that adopts the sampling format shown in FIG. 10 as a recording medium. In this optical disc recording and reproducing apparatus, the optical disc (10) is driven to rotate at a constant angular velocity by a spindle motor (20), and the recording track of the optical disc (10) is driven by an optical head (21).
By scanning with a laser beam, digital data is optically recorded and reproduced in a data format that conforms to the CD standard.

In this optical disc recording and reproducing device, the optical head (
21) detects a laser diode which is driven by a laser drive circuit (22) and outputs a laser beam for recording and reproducing information, and the reflected light of the laser beam emitted by the laser diode from the optical disk (10). It has a built-in photodetector, etc., and scans the recording track of the optical disc (10) with a laser beam output from the laser diode, thereby reading information on the recording i/rack (T) of the optical disc (10). It is designed to perform recording and playback.

Then, a detection output obtained by the photodetector is obtained by scanning the recording track (TK) of the optical disk (10) with a reproduced RF signal by the optical head (21), that is, a laser beam output by the laser diode. is the information recording area (ARo) of the recording track (T)
A reproduced RF signal of about ) is subjected to equalizer processing and then reproduced by a decoder (26). It is decoded as U. Also, the servo area (AR) of the recording track (TK) is
The reproduced RF signal from the optical head (21) for s) is supplied from the 20th) 4I positional amplifier (27) to the head servo circuit (28) and the spindle servo circuit (29), and is also supplied to the clock reproduction circuit (30). is supplied to.

The above head servo circuit (2nd day) is connected to the above optical head (21st day).
) controls a two-wheeled actuator (not shown) that drives the objective lens of the optical head (21) to perform tracking servo and focus servo based on the reproduced RF signal supplied from the optical head (21).
a) Tracking errors are detected and tracking servo control is performed based on the playback outputs of (Qm), and there is no pit between the trunking information pit (Q,) and the clock information pit (Q,). Focus servo control by detecting focus errors based on area playback output?
Do step 11.

Further, the spindle servo circuit (29) detects a rotational angular velocity error of the spindle motor (20) based on the reproduced output of the clock information pit (Q,),
By feedback controlling the drive circuit (40) of the spindle motor (20), the spindle motor (20)
Spindle servo control is performed to keep the rotational angular velocity of the optical disc (10) constant.

Furthermore, the clock regeneration circuit (30) performs a so-called PLL based on the reproduction output of the clock information pit (QC) in the reproduction RF signal supplied from the optical head (10).
The above optical disc (10)
A basic clock φ1 of a predetermined frequency f synchronized with the rotation of is generated.

Here, the clock regeneration circuit (30) is, for example, a second
As shown in the block diagram of the figure, the servo area (
A differentiation circuit (3) that differentiates the reproduced RF signal with respect to ARs)
1), a zero-cross detection circuit (32) that performs zero-cross detection on the differentiated output waveform of the differentiator (31);
The detection output from the zero cross detection circuit (32) is AN
Phase comparator (34) fed via D gate (33)
), a voltage-controlled oscillation circuit (36) in which the phase comparison by the phase comparator (34) is supplied as a control voltage via a low-pass filter (35), the voltage-controlled oscillation circuit (
The frequency divider (37) divides the frequency of the oscillation output f by 36) to 1/270.

In this clock regeneration circuit (30), the AND gate (33) operates the clock information pit (Qc
) is extracted and supplied to the phase comparator (34).

Further, the phase comparator (34) compares the phase of the zero-cross detection output of the reproduced output of the clock information pit (Qc) with the phase of the 1/270 frequency-divided output from the frequency divider (37). , detect its phase error. The voltage-controlled oscillation circuit (36) controls the clock information pit (Qc) by controlling the oscillation phase with a control voltage according to the phase error detected by the phase comparator (34). The clock is reproduced by a so-called PLL in which the oscillation phase is fixed to the phase of the zero-cross detection output for the reproduced output, and as shown in FIG. 3, the clock information pit on the recording track (TK) of the optical disc (10) is (Qc) A basic clock φ having a predetermined frequency r, which is divided by 270, is formed.

The basic clock φ1 of the predetermined frequency f1 obtained by the clock regeneration circuit (30) is supplied to the hend servo circuit (2).
It is supplied as an operating clock to the spindle servo circuit (29) and the frequency conversion circuit (50).

The frequency conversion circuit (50) performs a frequency conversion process on the basic clock φ1 obtained by the clock regeneration circuit (30) to convert the clock frequency f1 into a frequency f, .M/N times M/N. The frequency conversion ratio M/N is controlled by the system controller (41) so that it changes according to the track number of the recording track (T) being scanned by the optical head (21).

For example, as shown in FIG. 4, the frequency conversion circuit (50) performs a first frequency division process that divides the clock frequency f1 of the basic clock φ obtained by the clock recovery circuit (30) by 1/N. (51), a phase comparator (52) to which the divided output t, /N from the first frequency divider (51) is supplied, and the phase comparison by the phase comparator (52) is performed by a low-pass filter (53). a voltage-controlled oscillation circuit (54) supplied as a control voltage via the voltage-controlled oscillation circuit (54);
A second frequency divider (3
7) etc. The phase comparator (52) has the phase of the frequency division output f, /N from the first frequency divider (51) and the frequency division output 1t from the second frequency division 2S (55).
/M to detect the phase error. The voltage-controlled oscillation circuit (54) has an oscillation phase controlled by a control voltage according to the phase error detected by the phase comparator (34), so that f, , = f , , At a frequency f2 of M/N, the phase of the divided output T, /N from the first frequency divider (51), that is, the clock regeneration circuit (
The oscillation phase is fixed to the phase of the basic clock φ1 obtained in step 30).

Here, in the frequency conversion circuit (50), the first and second frequency dividers (51) and (55) are constituted by so-called programmable dividers, and control data D is transmitted from the system controller (41). , ,D, the frequency division values 1/N and 1/M of the first and second frequency divisions n (51) and (55) are variably controlled by
The frequency conversion ratio M/N is changed according to the track number of the recording track (TK) being scanned by the optical head (21), and the recording track (TK) being scanned by the optical head (21) is Frequency conversion processing is performed to convert the TK to a higher frequency f toward the outer circumference, and each recording trunk (TK
) is formed with a channel clock φ2 for recording and reproducing information at a substantially constant recording density.

The channel clock φ2 obtained by the frequency conversion circuit (5o) is transmitted to the encoder (42) of the recording processing system.
), and is also supplied to the A/D converter (24) and digital equalizer (25) of the reproduction processing system via the phase control circuit (60).

The encoder (42) converts the recording data DIN into a recording timing pulse synchronized with the channel clock φ2 obtained by the frequency conversion circuit (5o) in the recording mode, and supplies the pulse to the laser drive circuit (22); By pulse-driving the laser diode of the optical head (10) according to the recording data DIN, the recording track (TK) of the optical disc (10) is changed as shown in FIG.
).

By performing a recording operation in the recording processing system using the frequency-converted channel clock φ2 obtained by the frequency conversion circuit (50) in this way, the optical disc (lO) that is rotated at a constant angular velocity is recorded. Information can be additionally recorded at a substantially constant recording density on the inner and outer circumferential sides of the information writing area (ARo) of each recording trunk (TK).

Note that the information writing area (A
When adding information to Ro), a phase pit (Q,) is recorded immediately after each servo area (ARC) for each data block (BLI), (BL2) to (BL,).

In the reproduction processing system for reproducing the information additionally recorded in each recording track (TK) on the optical disc (10) in this way, the channel clock φ2 obtained by the frequency conversion circuit (50) is Phase control circuit (60
) is supplied with a channel clock φ2° for reproduction processing, and at this channel clock φ2° the above A/D
A converter (24) and a digital equalizer (25) are activated.

The phase control circuit (60) phase-shifts the channel clock φ2 obtained by the frequency conversion circuit (50) to form a channel clock φ2'' for reproduction processing, as shown in FIG. 6, for example. A multi-stage buffer amplifier (6t1) connected in series serves as a phase converter.

(612) to (62,) and the buffer amplifier (6L
), (61t) to (62, l), and two latch circuits (62) for launching the reproduced data DP11 from the A/D converter (24).
3) The latch data from (64) is subtracted by the subtractor (65
), and the adjustment logic (67) controls the selection operation of the switch (62) in accordance with the output of the comparator (66) which compares the subtracted output value obtained by the subtracter (65) with a predetermined value. is configured to do so. As shown in FIG. 6, this phase control circuit (60) operates in the servo area (
The above phase pitch (Qr) of the reproduced RF signal from ARs)
The phase correction is performed by focusing on the spread of the reproduced RF signal with respect to the phase pit (QP), and the sampling level Lr of the leading edge portion and the sampling level L of the trailing edge portion of the reproduced RF signal with respect to the phase pit (QP) are determined by each of the latch circuits. (63).

(64) L, the subtracted output value by the subtracter (65), that is, the channel clock φ2' at which the level difference between the sampling levels LF and Ll is zero, is set by the switch (
62), the adjustment logic (67) controls the selection operation of the switch (62).

By performing reproduction processing using the channel clock φ2' obtained through the phase control circuit (60) in this way, the reproduction processing system allows the optical head (21) to record data on the optical disc (10). The playback signal obtained by scanning the track (TK) can always be played back using the optimal phase channel clock φ2', reducing the error rate and providing highly reliable playback processing. You will be able to do this.

In addition, playback data DP from the A/D converter (24)
The digital equalizer (25) to which I+ is supplied applies equalization processing to the reproduced data D□ using the channel clock φ2° as an operation clock, and has a configuration as shown in FIG. 8, for example.

That is, the digital equalizer (25) shown in FIG.
are four latch circuits (71), (72), (7) whose operation clock is the channel clock φ2°.
3) and (74), the reproduced data DP11 is latched by a first latch circuit (71), and the launch output by this first latch circuit (71) is supplied to a second latch circuit (72). is applied to the synthesizer (77) via the coefficient unit (75), and the second latch circuit (
The latch output from the third latch circuit (72) is supplied to the third latch circuit (73) and also to the synthesizer (77), and the latch output from the third latch circuit (73) is fed to the coefficient multiplier (77). The synthesized output from the synthesizer (76) is output as the equalized reproduced data DPI+" via the fourth launch circuit (74). The synthesizer (76) includes each of the coefficient units (75), (76
) The latch outputs from the first and third launch circuits (71) and (73) supplied through the second
Synthesis processing is performed to subtract from the launch output from the latch circuit (72).

The digital equalizer (25) having such a configuration changes the clock period of the channel clock φ2′ to ΔT=
1 / f z, the impulse response hD) h(t)=δ(t)-K(δ(t+ΔT)+δ(t-Δ
T) exhibits 1 characteristic. The above impulse response h(t) is
When converted to frequency characteristic F(h(t)l by Fourier transform, F(h(t)l = h(t)e-""Ldt=
l K (6-JR'Llslf +e*J27ta
Tf)=1-2Kcosl+rΔTf.

Therefore, the digital equalizer (25) exhibits an equalizer characteristic that changes with the clock frequency #lT (ΔT=1/f,) of the channel clock φ2°, as shown in FIG. 9(B), and this equalizer characteristic is applied to the reproduced RF signal from the recording track (TK) of the optical disk (lO) as shown in FIG. 9(B). In addition, the 9th
In the figure, an example of the equalizer characteristic for the reproduced RF signal from the inner recording track (TK) of the optical disc (10) is shown by a solid line, and the equalizer characteristic for the reproduced RF signal from the outer recording trunk (TK) is shown by a solid line. An example of equalizer characteristics is shown by a broken line.

In this way, the digital equalizer (25) is supplied with the reproduced data [)pm from the A/D converter (24).
), the recording track (TK) of the optical disc (10) is
The equalizer characteristics can be automatically changed according to the frequency characteristics of the reproduced RF signal from the RF signal, and optimal equalizer processing can always be performed to perform high-quality reproduction operations.

H Effects of the Invention In the optical disc recording and reproducing apparatus according to the present invention, the clock reproducing circuit operates based on the reproduced output of the clock information focus obtained at each predetermined rotation angle from the recording track of the optical disc that is rotationally driven at a constant angular velocity. A frequency conversion means that generates a basic clock of a constant frequency f synchronized with the optical disk, and whose frequency conversion ratio M/N is variably controlled by a control means according to the recording track number of the optical disk,
The clock frequency f1 of the basic clock is converted by a frequency converting means M/N times to form a channel clock having a frequency f2 such that r2=f, .M/N. The channel clock whose frequency has been converted by the above frequency conversion means is
Since it is synchronized with the optical disc and has a frequency r2 that changes according to the recording track number of the optical disc, by performing recording and playback processing using this channel clock, each recording trunk on the optical disc It is possible to record and reproduce information at a recording density that is approximately average for that of the recording medium, and it is possible to improve the utilization efficiency of the recording medium and perform high-density recording.

Further, in the optical disc recording and reproducing apparatus according to the present invention, the channel clock phase control means provided in the reproduction processing system to which the frequency-converted channel clock obtained by the frequency converting means is supplied controls the recording track of the optical disc. By controlling the phase of the channel clock so that the level difference between the leading edge and trailing edge of the reproduced signal is zero, it is possible to obtain a channel clock in an optimal phase state. By using this, the reproducing operation can be reliably performed in the reproducing processing system.

Furthermore, in the optical disc recording and reproducing apparatus according to the present invention, by operating a digital equalizer provided in the reproducing processing system using the frequency-converted channel clock obtained by the frequency converting means, the optical disc is reproduced from the recording track of the optical disc. By automatically changing the equalizer characteristics given to the reproduced signal, the optimal equalizer processing operation can always be performed on the reproduced signal, and information recorded at high density can be reproduced with high quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of main parts of an optical disc recording and reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing an example of the configuration of a clock reproducing circuit used in the optical disc recording and reproducing apparatus, and FIG. 3 is a block diagram showing the configuration of the clock reproducing circuit used in the optical disc recording and reproducing apparatus. A time chart for explaining the operation of the reproduction circuit, FIG. 4 is a block diagram showing an example of the configuration of the frequency conversion circuit used in the optical disc recording and reproduction apparatus, and FIG. 5 is a time chart for explaining the operation of the frequency conversion circuit. A time chart, FIG. 6 is a block diagram showing an example of the configuration of a phase control circuit used in the optical disc recording/reproducing apparatus, and FIG. 7 is a time chart.
9 is a time chart for explaining the operation of the phase control circuit, FIG. 8 is a block diagram showing an example of the configuration of a digital equalizer used in the optical disc recording and reproducing apparatus, and FIG.
The figure is a characteristic diagram for explaining the operation of the digital equalizer. Figure 10 is a schematic diagram showing the recording formant of a general optical disc that adopts the sampling formant;
The figure is a schematic % formula for explaining the channel clock reproducing operation for the above-mentioned optical disc (30)... Clock reproducing circuit (41)...
...System controller (50) ...
...Frequency conversion circuit (Qc) ... Clock pit

Claims (3)

[Claims] (1) Clock information pits are arranged radially around the central hole on a ring-shaped recording surface extending around the central hole, and a recording track whose data recording area is between the clock information pits surrounds the central hole. In an optical disc recording and reproducing apparatus that records and reproduces information on the recording track while rotating an optical disc formed in a number of circular patterns at a constant angular velocity, a predetermined frequency f_ is determined from the reproduction output of the clock information pits.
1; a frequency conversion means for generating a channel clock having a frequency f_2 obtained by converting the clock frequency f_1 of the basic clock by M/N times; and a frequency conversion ratio M/ of the frequency conversion means. an optical disc recording device comprising a control means for changing N in accordance with a recording track number of the optical disc, and recording and reproducing information on the recording track using a channel clock whose frequency has been converted by the frequency converting means. playback device. (2) The reproduction processing system to which the frequency-converted channel clock obtained by the frequency conversion means is supplied is provided with phase control means for the channel clock, and the leading edge portion of the reproduction signal reproduced from the recording track of the optical disc is 2. The optical disc recording and reproducing apparatus according to claim 1, wherein the phase of the channel clock is controlled so that a level difference at a trailing edge portion becomes zero. (3) A digital equalizer for the reproduction signal reproduced from the recording track of the optical disk is provided in the reproduction processing system, and the digital equalizer is operated by the frequency-converted channel clock obtained by the frequency conversion means. The optical disc recording and reproducing apparatus according to claim (1).