JPH0383265A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE:To shorten the time required for reproducing an optical disk as a whole by generating a reference signal for reproducing reference based on a frequency component of pre-recording information in a signal reproduced by a reproducing means. CONSTITUTION:A spindle motor 3 is controlled by a CAV control circuit 4 to rotate the optical disk 1 at a constant angular velocity (CAV). Reflected light from the optical disk 1 is detected by an optical head 5, so as to reproduce the pre-recording information consisting of a biphase mark modulation wave of an absolute address recorded by a bias between recording information and a guide groove. These reproductive signal and pre-recording information are inputted via a reproductive amplifier 6 to a reproductive signal processing circuit 7, where a reproduced data D is outputted from an output terminal 8 based on a reproducing clock from a reproducing clock generating circuit 11. On the other hand, the regenerative signal and the pre-recording information from the regenerative amplifier 6 are inputted to an extraction circuit 10 to extract the pre-recording information to be inputted to the circuit 11, where the reproducing clock signal as the reference signal in proportion to a bit frequency of the pre-recording information is generated, and is sent to the circuit 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc reproducing device for reproducing information recorded on various types of optical discs, such as read-only type, write-once type, and rewritable type. The present invention relates to an optical disc reproducing apparatus which reproduces an optical disc on which pre-recorded information is formed for the purpose of controlling rotation at a constant linear velocity by controlling the rotation at a constant angular velocity.

[Conventional technology]

Conventionally, so-called compact discs (hereinafter referred to as CDs) on which music information and the like are recorded as digital signals using uneven bits have been widely used. This CD is played back by a playback-only optical disc playback device.

The above-mentioned CD usually has a plurality of pieces of information recorded in succession, and during playback, the absolute address pre-recorded on the disc and the TO
Continuous reproduction, selective reproduction, etc. of desired information is performed by checking the absolute address of the recording start position of each piece of information recorded in the C (Table Of Contents) N area.

On the other hand, when recording music information on rewritable disks such as magneto-optical disks, which have been developed in recent years, or write-once optical disks that can only be recorded once, it is difficult to compare them with conventional CDs. It is desirable to standardize the playback method between the two and provide compatible optical disc recording and playback devices. In that case, when the optical disc rotates during recording or playback, the so-called constant linear velocity (constant linear velocity)
Hereinafter, CL V (Constant Linear
Rotation control (referred to as "velocity") can be adopted. Furthermore, so-called CD-ROM, which is a playback-only CD that records various data other than music information, has conventionally been used.
is provided, but this CD-ROM also includes CL.
V control is adopted.

However, in the CLV control described above, it is necessary to change the rotational speed of the motor according to the radial position of the disk, which complicates the control of the rotation of the motor and moves the optical head in the radial direction of the disk to achieve the desired When accessing the trunk, the rotational speed of the motor must be changed before and after access, which increases the time required for access. Also, for example, when reproducing information recorded on a CD-ROM and transferring it to an external device, CLV$1ll)
In this case, since the time required for reproduction per round of the disc increases toward the outer circumference, there is a problem that the time required to reproduce the entire disc becomes longer.

In order to eliminate the above-mentioned problems, when recording or reproducing information that does not matter even if the time series changes, such as computer data, the rotational speed of the spindle motor should be kept constant regardless of the radial position of the disk. , so-called constant angular velocity (CAV)
rotation control (referred to as ngular velocity) can be employed.

However, in the CAV method, since the frequency of the clock for recording or reproduction is constant regardless of the radial position of the disk, the recording density decreases toward the outer circumference of the disk, resulting in insufficient recording capacity. . Conventionally, in CAV control, by increasing the recording frequency toward the outer periphery of the disk, the recording density is kept almost constant between the inner and outer peripheries of the disk, and the recording capacity is increased. CA
V) method has also been proposed. When recording is performed using this MCAV method, it is necessary to gradually increase the frequency of the reproduction clock toward the outer circumference of the disc during reproduction as well.

[Problems to be Solved by the Invention] By the way, in the conventional MCAV method, several types of frequency generators are provided, one of the frequency generators is selected corresponding to the disc area to be reproduced, and the The signal from the frequency generator is used as a reference signal during reproduction. At that time, the disk is divided into multiple areas corresponding to the several types of frequencies mentioned above, and the recording density is assumed to be approximately constant, but a recording density equivalent to that of the CL and v systems has not been achieved.

Furthermore, on optical disks such as magneto-optical disks that can be freely recorded by the user, pre-recorded information such as absolute addresses is recorded in a non-erasable state, but the format of the pre-recorded information is CLV. Since an optical disc for which rotation control is performed and an optical disc for which rotation control is performed by MCAV are different, it has been impossible to share an optical disc recordable with both CLV and MCAV systems.

[Means to solve the problem]

In order to solve the above-mentioned problems, an optical disc playback device according to the present invention has pre-recorded information periodically formed along a track to control rotation at a constant linear velocity (CLV) over the entire surface. In an optical disc playback device that plays back an optical disc, the optical disc is moved at a constant angular velocity (CA).
(V), a reciprocating means for reproducing the signal on the optical disk, and a reference signal for generating a reference signal for reproduction based on the frequency component of the pre-recorded information (in No. 8) reproduced by the reproducing means. The present invention is characterized by comprising a signal B generating means.

[Function] In the above configuration, the pre-recorded information is formed in accordance with CLV, so when this optical disc is rotated using the CLV method, the frequency components of the pre-recorded information are almost constant regardless of the radial position of the optical disc. However, when rotated by the CAV method as in the above configuration, the frequency component of the pre-recorded information becomes higher toward the outer circumference of the optical disc. Therefore, as described above, if a reference signal such as a reproduction clock is generated based on the frequency component of pre-recorded information, it is possible to accurately generate a reference signal whose frequency increases toward the outer circumference of the optical disc. become able to.

Furthermore, in order to perform rotation control at a constant linear velocity (CLV), an optical disc on which pre-recorded information such as an absolute address is recorded is rotated at a constant angular velocity (CAV) and played using the MCAV method. In the case of a recordable type, one optical disc can be used in both the original CLV system and the MCAV system according to the present invention, and can be reproduced by the optical disc reproducing apparatus according to the present invention in either case.

Also, for example, if a CD-ROM manufactured for the purpose of playback using the CLV method is played back using the MCAV method,
In the MCAV method, since the time required for reproducing the optical disc per revolution is constant regardless of the radial position, it is possible to shorten the time required for reproducing the entire optical disc.

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

FIG. 3 shows the optical disc 1. This optical disc l may be of various types, such as a read-only type, a write-once type, or a rewritable type, and has a TOC (Table O
f Contents) area 1a is provided, and most of the area outside the TOC area 1a is an information recording area 1b. Various types of information are recorded in the information recording area 1b, while additional information regarding each piece of information recorded in the information recording area 1b, such as the recording start and end positions of each piece of information, is recorded in the TOC area 1a. It is something that

As shown in FIG. 4, in the T○C area 1a and the information recording area 1b of the optical disc 1, spiral or concentric guide grooves 2, 2... (shown by hunting for convenience) are predetermined in the radial direction. They are formed at intervals of . The absolute address of each part on the optical disc 1 is
As shown in Publication No. 39632, after the biphase mark is biased, the guide grooves 2, 2, etc. biased inward or outward.

The bi-phase mark modulated absolute addresses mentioned above use pre-recorded information and are recorded at approximately constant intervals along the guide grooves 2 forming the track. Therefore, the frequency with which absolute addresses are recorded within the same angular range increases toward the outer circumference of the disk. In this way, the pre-recorded information is provided on the premise that recording or reproduction will be performed on the optical disc l using the CLV method.

For example, when recording or reproducing various types of data on the optical disc 1, rotation control may be performed using the CAV method, whereas when recording music information, etc., rotation control may be performed using the CLV method. good.

In the following, an optical disc reproducing apparatus that reproduces an optical disc 1 on which various data, etc. are recorded, using the MCAV method will be described.

As shown in FIG. 2, the optical disc reproducing apparatus according to this embodiment includes a spindle motor 3 as a driving means for supporting and rotating the optical disc 1, and a constant angular velocity (CA)
V), that is, the rotational speed of the spindle motor 3 is set so that the optical disk 1 is rotated at a constant rotational speed regardless of the radial position of the optical head 5! The CAM control circuit 4 that controls the IJ and the optical disc 1 are irradiated with laser light, and based on the reflected light from the optical disc 1, recording information such as various data recorded by uneven pits or magneto-optical signals, etc., and the guide groove 2 are recorded. The optical head 5 is provided as a reproducing means for reproducing pre-recorded information consisting of a bi-phase mark modulated wave of an absolute address recorded by biasing. Hereinafter, a signal obtained by reproducing the recorded information will be referred to as a reproduced signal, and a signal obtained by reproducing the pre-recorded information will be referred to as pre-recorded information.

The optical disk reproducing apparatus includes a reproducing amplifier 6 that amplifies the reproducing signal and pre-recorded information sent from the optical head 5. The reproduced signal amplified by the reproduced amplifier 6 is sent to the reproduced signal processing circuit 7, where it is subjected to predetermined processing based on the reproduced clock supplied from the reproduced clock generation circuit 11, which will be described later, and then sent to the output terminal 8. The playback data is output via the .

The reproduction signal and pre-recorded information amplified by the reproduction amplifier 6 are also sent to a pre-recorded information detection circuit 10 consisting of, for example, a bandpass filter, where only the pre-recorded information consisting of the bi-phase mark modulated wave of the absolute address is detected. is now extracted.

The pre-recorded information extracted by the pre-recorded information detection circuit 10 is sent to a reproduced clock generation circuit 11 as a reference signal generation means, and on the other hand, a reproduced signal from the reproduction amplifier 6 is also sent to this reproduced clock generation circuit 11. Then, a reproduced clock as a reference signal proportional to the bit frequency 13 of the bi-phase mark modulated wave of the absolute address, which is pre-recorded information, is generated in the reproduced clock generation circuit ll and sent to the reproduced signal processing circuit 7. It is configured.

Note that since the rotation of the optical disc 1 is controlled by the CAV direction, the bit frequency f of the biphase mark modulated wave of the above-mentioned absolute address becomes higher toward the outer circumference of the optical disc 1 as described above, and therefore, the reproduction clock The frequency f2 also increases toward the outer circumference of the optical disc 1. Thereby, the reproduced signal processing circuit 7 extracts reproduced data at a period corresponding to the radial position of the optical disc l.

Next, a more detailed configuration of the reproduction clonk generation circuit 11 will be explained based on FIG.

The recovered clock generation circuit 11 is configured as a type of phase-locked loop (PLL), and includes a phase comparison circuit 12, a low-pass filter (LPF) 13, an adder 14,
Voltage controlled oscillator (VC○) 15, frequency divider 16, and F/
V (frequency/voltage) converter 17.

A reproduction signal from the reproduction amplifier 6 is input to one input terminal of the phase comparator circuit 12 . The output signal of the phase comparison circuit 12 is input to a low-pass filter 13, and the output voltage 2 of the low-pass filter I3 is input to one input terminal of an adder 14. Further, a bi-phase mark modulated wave of an absolute address, which is pre-recorded information, is inputted to the input terminal of the F/V converter 17 from the pre-recorded information detection circuit 10, and the bit frequency f of this bi-phase mark modulated wave corresponds to the input terminal of the F/V converter 17. is converted into a voltage V, which is inputted to the other input terminal of the adder 14.

The output voltage ■, of the adder 14 is input to the voltage controlled oscillator 15, where the frequency ft corresponding to the above output voltage V is input to the voltage controlled oscillator 15.
Oscillation occurs at The output signal of this voltage controlled oscillator 15 becomes a recovered clock. In addition to being sent to the reproduced signal processing circuit 7, this reproduced clock is inputted to the other input terminal of the phase comparator circuit 12 via a frequency divider 16.

As shown by ■ in FIG. 5, the frequency f of the pre-recorded information becomes higher toward the outer circumference of the optical disc 1, as described above. Further, as shown by ■ in the same figure, the frequency island of the reproduced signal is higher than the frequency r of the pre-recorded information, but the frequency f of this reproduced signal also increases toward the outer circumferential side of the optical disc l.

FIG. 6 shows the transition of the output signals of each part of the reproduced clock generation circuit 11 when accessing from the inner circumference to the outer circumference of the optical disc l. As shown in (a) in the figure, during reproduction of the inner circumferential portion T, as long as the same track or a group of adjacent tracks is being reproduced, the reproduction that is manually input to one input terminal of the phase comparator circuit 12 The frequency f1 of the signal is almost constant, the frequency of the reproduced signal gradually increases at T2 during the access operation, and the frequency f1 of the reproduced signal gradually increases at T2 during the access operation, and when the outer peripheral portion is reproduced after the access is completed
, the frequency f1 of the reproduction signal is substantially constant at a value higher than TI during reproduction of the inner circumferential portion.

Furthermore, as shown in (b) and (C) in the same figure, the frequency f of the pre-recorded information and the output voltage v1 of the F/V converter 17 also show the same tendency as the frequency f of the reproduced signal, and Almost constant at T1 during peripheral playback, T during access operation! gradually increases, and becomes almost constant at T when the outer peripheral portion is reproduced.

In addition, as shown in (d) in the same figure, a low-pass filter 13
Although the output voltage z causes a slight fluctuation in T2 during the access operation, it remains almost constant regardless of the radial position of the optical disk l.

Furthermore, as shown in (e) and (f) in the figure, the adder 1
The output voltage V of 4 and the frequency f2 of the reproduction clock are almost constant at T1 when reproducing the inner circumference, gradually increasing although there is a slight fluctuation at T2 during the access operation, and when T, when reproducing the outer circumference. It remains almost constant. As shown in (e) in the same figure, the output voltage (■) of the adder 14 is mainly caused by the F/V converter 17.
In other words, the frequency f of the pre-recorded information
.

The output voltage v of this adder 14 changes in response to the change in
3 increases toward the outer periphery of the optical disc 1, so as shown in (f) in the figure, the reproduction clock frequency f2
becomes higher toward the outer circumference of the optical disc 1.

As described above, the frequency f2 of the reproduced clock changes mainly in accordance with the frequency f of the pre-recorded information. Therefore,
Even if there is an unrecorded portion of information at the time of access and it is impossible to detect the reproduced signal, it is possible to detect the pre-recorded information, so the reproduction clock can be generated based on the pre-recorded information even during the access period. It will be planned. As a result, the PLL in the reproduction clock generation circuit N11 is locked immediately after the access ends, so that reproduction can be started immediately after the access.

Note that the above access is performed by coarse access in which the optical head 5 is moved near the target track at high speed, and fine access in which the optical head 5 is moved to the target track while reading the absolute address included in pre-recorded information after coarse access. Considering these separately, since it is possible to completely reproduce the pre-recorded information at least during the dense access, the reproduction clocks can be synchronized at least from the time of the dense access.

[Embodiment 2] Next, a second embodiment will be described based on FIGS. 7 to 10.

The second embodiment has the same structure as the first embodiment as a whole, but differs from the first embodiment in the internal structure of the reproduced clock generation circuit 11. Therefore, only the recovered clock generation circuit 11 will be described below.

As shown in FIG.
phase-locked loop (first PLL) 21 and second
A phase-locked loop (second PLL') 22 is provided. The reproduced clock generation circuit 11 generates a reproduced clock based on the reproduced signal (binary signal) from the reproduction amplifier 6 during normal reproduction, and generates the reproduced clock based on pre-recorded information from the pre-recorded information detection circuit 10 during access. The clock is configured to generate a recovered clock.

To explain in detail below, the first PLL 21 includes a first phase comparator circuit 23, a first low-pass filter (first LPF) 24 arranged at the subsequent stage, and a first low-pass filter (first LPF) arranged at the subsequent stage. a voltage controlled oscillator (first VCO) 25 and a first voltage controlled oscillator 25 that divides the reproduced clock, which is an output signal of the first voltage controlled oscillator 25, at a predetermined frequency division ratio and feeds it back to the first phase comparison circuit 23. A frequency divider 26 is provided.

A switch 27 is arranged before the first PLL 21, and the first phase comparator circuit 23 receives a signal generated based on the playback signal from the playback amplifier 6 or pre-recorded information via the switch 27. Any of the signals from the third frequency divider 33 is input. Note that during normal playback, a playback signal with a bit frequency fl is manually input to the first phase comparison circuit 23 based on the switching signal, and a playback clock with a frequency f2 is generated in the first PLL 21 based on this playback signal. Ru.

The second PLL 22 includes a second phase comparator circuit 28 to which a bi-phase mark modulated wave of an absolute address, which is pre-recorded information with a bit frequency f, is input, and a second low-pass filter disposed at the subsequent stage. (Second LPF) 30 and the second (7) disposed at the subsequent stage, the pressure IHIJli8 (
Second (DVCO) 31 (!:, Second voltage controlled oscillator 3
A second frequency divider 32 divides a signal having a frequency f4, which is the output signal of the first phase, by a predetermined frequency division ratio and feeds the divided signal back to the second phase comparator circuit 28.

The signal of frequency f4 from the second voltage controlled oscillator 31 is divided by a predetermined frequency division ratio by the third frequency divider 33 and sent to the switch 27.

The frequency division ratio of the third frequency divider 33 is set so that the frequency of the output signal of the third frequency divider 33 is approximately equal to the bit frequency f1 of the reproduced signal.

In the above-mentioned switch 27, the signal from the third frequency divider 33 is selected at the time of access, and the first PLL 21 generates a reproduced clock based on the pre-recorded information. In addition,
Since the frequency of the signal from the third frequency divider 33 is approximately equal to the bit frequency f1 of the reproduced signal, the frequency will be approximately the same whether the reproduced clock is generated based on the reproduced signal or the pre-recorded information.

In this second embodiment as well, the reproduced clock is generated during access based on the pre-recorded information, so even if it is impossible to detect the reproduced signal during access, the reproduced clock can be generated during access. It is done smoothly. Since the regenerated clock is synchronized even during the access period, the regenerated clock can be quickly synchronized with the regenerated signal after switching the input to the first phase comparison circuit 23 to the regenerated signal after the access ends. This makes it possible to start playback in a short time after access is completed.

Now, as shown in FIG. 8(a), an area N in the information recording area 1b of the optical disc 1, (absolute addresses n1 to n
It is assumed that recorded information such as various data is recorded in the area NZ (range of absolute addresses n, to n4), and area N3 (range of absolute addresses n5 to n+).

In that case, the pre-recorded information is recorded on the entire surface of the optical disc 1 in accordance with CLV, and the rotation is controlled by the CAV method, so the frequency 13 of the pre-recorded information is as shown in (b) in the figure.
The area gradually increases from the inner circumference to the outer circumference of the optical disc 1 as shown in FIG.
The frequency f1 of the reproduced signal gradually increases toward the outer circumference of the optical disc 1.

Here, an area N near the inner circumference is detected by the optical head 5.

Consider a case where an area N3 near the outer periphery is accessed during playback. In that case, as shown in FIG. 9(a), the frequency f1 of the reproduction signal during reproduction of the same track or a group of adjacent tracks is approximately constant at time T when the region N1 is reproduced. Thereafter, when access is started, the frequency f of the reproduced signal changes when passing through area N2 during access period 2.

gradually increases, and when the same track or a group of adjacent tracks is being reproduced at stage T, when reproduction of area N is started after the access is completed, the frequency f of the reproduced signal becomes approximately constant.

In addition, when accessing area N, to area N, the frequency f3 of the pre-recorded information and the frequency r2 of the reproduction clock are different before the access (period T) and during the access (between llI1 and T2).
) and after the access (period Tff), respectively (b
) and (d). Furthermore, the switch 27
The switching signal supplied to the switch changes as shown in (C) in the figure. However, when the switching signal is at High level, the first phase comparison circuit 23 is connected to the third frequency divider 33 based on pre-recorded information.
When the switching signal is at Lo-level, the reproduced signal is input to the first phase comparator circuit 23.

As described above, in this second embodiment, as shown in FIG. 10, signals are reproduced while the optical disc 1 is rotated under CAV control (S 1 ), and access to a predetermined absolute address is commanded. If so, start the access operation.
2) Immediately switch the switch 27 to input the output signal of the third frequency divider 33 to the first phase comparison circuit 23 (S3).

Then, it is determined whether the access has ended or not (S4),
If not completed, repeat this determination. If the access has been completed, the switch 27 is switched so that the reproduction signal from the reproduction amplifier 6 becomes the manual signal of the first phase comparison circuit 23 (S5), and the normal reproduction operation is executed (S6). It is.

In the above embodiment, the switch 27 is switched depending on whether access is in progress or not, but it may also be performed by determining the state of the playback signal, such as by detecting the amplitude of the playback signal or detecting an error state.

Furthermore, in each of the above embodiments, a reproducing apparatus for the optical disc 1 has been described, but if the optical disc 1 is, for example, a magneto-optical disc as a rewritable disc, the optical disc reproducing apparatus shown in FIG. By adding , it is possible to perform recording, reproduction, and erasing on the optical disc 1. In addition, as the optical disc 1, there are 1 types other than the rewritable type.
A write-once type that allows desired recording to be performed only once may be used. In either case, the reproducing system can be configured almost the same as in the above embodiment.

Furthermore, the above-mentioned optical disc reproducing apparatus can also reproduce a CD-ROM, which is a reproduction-only optical disc on which various data are originally recorded so as to be reproduced using the CLV method. In that case, the CD-ROM disc may have information pit strings biased as absolute addresses of pre-recorded information, for example, as shown above, and according to the MCAV system of this embodiment, the disc 1 Since the time required for reproduction per round is constant regardless of the radial position, the time required for reproduction of the entire disc can be shortened.

In addition, although the above embodiment has been described using an example in which pre-recorded information is recorded by biasing the guide groove 2 in accordance with a bi-phase mark modulated wave of an absolute address, the present invention is not limited to this. Other methods with limited frequency bands may also be used. Further, the guide groove 2 may be made to meander instead of being biased.

[Effects of the Invention] As described above, according to the optical disc playback device of the present invention,
In an optical disc playback device for playing back an optical disc in which pre-recorded information for controlling rotation at a constant linear velocity over the entire surface is periodically formed along a track, a driving means for driving the optical disc to rotate at a constant angular velocity. and a reproducing means for reproducing the signal on the optical disk, and a reference signal generating means for generating a reference signal for reproduction based on the frequency component of the pre-recorded information in the signal reproduced by the reproducing means. .

As a result, the pre-recorded information is formed in accordance with CLV, so when this optical disc is rotated using the CLV method, the frequency component of the pre-recorded information will be almost constant regardless of the radial position of the optical disc, but with the above configuration. How <CAV
When the optical disc is rotated in this manner, the frequency components of the prerecorded information become higher toward the outer circumference of the optical disc. Therefore,
As described above, if a reference signal such as a reproduced clock is generated based on the frequency component of pre-recorded information, it becomes possible to accurately generate a reference signal whose frequency increases toward the outer circumference of the optical disc. Therefore, high-speed access can be performed without changing the disk rotation speed during access, and information can be immediately reproduced after access using the above reference signal.

Furthermore, in order to perform rotation control at a constant linear velocity (CLV), an optical disc on which pre-recorded information such as an absolute address is recorded is rotated at a constant angular velocity (CAV) and played using the MCAV method. In the case of a recordable type, one optical disc can be used in both the original CLV system and the MCAV system according to the present invention, and can be reproduced by the optical disc reproducing apparatus according to the present invention in either case.

Also, for example, if a CD-ROM manufactured for the purpose of playback using the CLV method is played back using the MCAV method,
In the MCAV method, the frequency of the reproduced clock increases as it moves toward the outer circumference of the optical disc, so the reproduction and transfer speeds to external equipment can be increased as it moves toward the outer circumference, and as a result, the time required for reproduction and transfer is shortened. You will be able to do this.

Therefore, the characteristics of the CLV method, such as large data capacity and C
It is possible to provide a highly reliable disc playback device that also has high speed, which is a feature of the AV system.

[Brief explanation of drawings]

1 to 6 show one embodiment of the present invention. FIG. 1 is a block diagram showing the internal configuration of the recovered clock generation circuit. FIG. 2 is a block diagram of the optical disc playback device. FIG. 3 is a schematic plan view of the optical disc. FIG. 4 is an enlarged partial view of FIG. FIG. 5 is a graph showing the relationship between the radial position of the optical disc and the frequency of the reproduced signal and pre-recorded information. FIG. 6 is a time chart showing the transition of signals in each part of the reproduced clock generation circuit before and after access. FIGS. 7 to 10 show a second embodiment. FIG. 7 is a block diagram showing the internal configuration of the reproduced clock generation circuit. FIG. 8 is an explanatory diagram showing the recording state of information on the optical disc and changes in the frequency of pre-recorded information and reproduction signals. FIG. 9 is a time chart showing the transition of signals in each part of the reproduced clock generation circuit before and after access. FIG. 10 is a flowchart showing an outline of the control procedure at the time of access. 1 is an optical disk, 3 is a spindle motor (driving means),
5 is an optical head (reproduction means), and 11 is a reproduction clock generation circuit (reference signal generation means).

Claims (1)

[Claims] 1. In an optical disc reproducing apparatus for reproducing an optical disc in which pre-recorded information for controlling rotation at a constant linear velocity over the entire surface is periodically formed along a track, A drive means that rotates at a constant angular velocity, a reproduction means that reproduces a signal on an optical disk, and a reference signal generation means that generates a reference signal for reproduction based on the frequency component of pre-recorded information in the signal reproduced by the reproduction means. An optical disc playback device comprising: