JPH0366062A - Optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable a revolving control at the time of reproducing by changing the revolving control based on the previous recording information when it is detected by a deciding means at the time of reproducing that frequent reproducing errors take place or an optical head comes into a nonrecording part of information so that the revolving control becomes difficult to perform. CONSTITUTION:At the time of performing a constant linear velocity (CLV) control based on a regenerative signal, when frequent reproducing errors take place or the optical head 4 comes into a nonrecording part of information, a synchronizing signal detecting pulse and a synchronizing signal lacking detecting pulse are supplied to a regenerative signal state deciding circuit 21. Then, the number of lacking pulse generating times is counted, and when its value exceeds a reference value, the state is considered that synchronizing abnormality is generated in a signal recorded part or a frame synchronizing signal cannot be detected because the head comes into a nonrecording part, and hence a CLV changeover signal is outputted to a changeover switch 15. By this method, even at the time of reproducing, the change over is made to the CLV control by the previous recording information to prevent a failure in performing the revolving control at the time of reproducing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc recording/reproducing device for recording or reproducing information on a so-called recordable or rewritable optical disc. This relates to constant rotation control of an optical disc.

[Conventional technology]

Conventionally, so-called compact discs (compact discs) on which music information etc. were recorded as digital signals using mechanical pits.
(hereinafter referred to as CD) are 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 T.
Continuous playback, selective playback, etc. of desired information are performed by checking the absolute address of the recording start position of each piece of information recorded in an OC (Table Of Contents) 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 be recorded only 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, as a rotation control method of the optical disc during recording or reproduction, the so-called constant linear velocity control (hereinafter referred to as CLV), which is implemented in CDs, is used.
near Vel.

city control) can be adopted.

By the way, when controlling the rotation of an optical disk using a CLV, for example, the rotation speed of the motor is controlled according to the rotation speed of the motor detected by a rotary encoder or the like and the radial position of the optical head detected by a position detection sensor. However, in that case, detection errors of the rotary encoder and position detection sensor will occur, so sufficiently accurate rotation control cannot be expected.

Therefore, it is conceivable to perform CLV control based on information recorded in advance on the optical disc, such as the above-mentioned absolute address. Conventionally, as an absolute address recording method, after bi-phase mark modulation of the absolute address, the guide groove of the optical disk is shifted radially inward or outward depending on whether each bit is 1" or "0". It has been proposed to change the width of the guide groove (see Japanese Unexamined Patent Publication No. 64-39632).
By making the frequency band of the absolute address and the frequency band of recorded information different, it is possible to reproduce the two separately from each other.

[Problem to be solved by the invention]

However, as mentioned above, even if information is recorded while rotating the optical disc using information such as absolute addresses recorded in advance on the optical disc, the actual CL at the time of recording is
Due to errors in vwi control, information may be recorded in a state slightly deviated from the CLV conditions. In that case,
If the recorded information is music information, subtle variations in performance speed will occur during playback. Therefore, when reproducing information, it is preferable to perform CLV control based on the information to be reproduced.

However, during reproduction, for example, if reproduction errors occur frequently or if the optical head approaches an area where information is not recorded, there is a problem that rotation control based on reproduction information becomes impossible. Furthermore, even if the quality of the reproduced signal is recovered after rotation control based on reproduction information becomes impossible, it takes a considerable amount of time until correct rotation control can be performed.

[Means to solve the problem]

In order to solve the above-mentioned problems, an optical disc recording and reproducing apparatus according to the present invention records or reproduces rotation control information on an optical disc in which rotation control information for performing rotation control at a constant linear velocity over the entire surface is recorded as pre-recorded information. In an optical disc recording/playback device that performs playback, a playback signal state determining means for determining a playback signal state during playback, a rotation control at a constant linear velocity using the pre-recorded information during recording, and a rotation control at a constant linear velocity during playback based on the playback signal. control means for performing rotation control at a constant linear velocity, while switching rotation control during reproduction to rotation control based on the pre-recorded information when the reproduction signal state determination means determines that the reproduction signal state is below a predetermined standard; It is characterized by being provided with.

[For production]

According to the above configuration, during recording, constant linear velocity (CLV) rotation control is performed based on pre-recorded information, and during playback, CLV rotation control is performed based on the playback signal. During playback, suitable rotation control is performed depending on the purpose.

Further, when the reproduction signal state determining means detects that the rotation speed based on the reproduction signal becomes difficult during reproduction due to frequent reproduction errors or the optical head approaching an unrecorded area so that a reproduction signal cannot be obtained. As the next best measure,
Since the rotation control is switched to the rotation control based on the pre-recorded information even during playback, problems such as the inability to perform rotation control during playback do not occur.

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

As shown in FIG. 2, on a magneto-optical disk as a rewritable optical disk, there is a TOC (T
A TOCSR area 1a is provided, and most of the area outside the TOCSR area 1a is an information recording area 1b. In the information recording area 1b, various information such as music programs are recorded, while TOC? Additional information regarding each piece of information recorded in the information recording area 1b, such as the recording start position and recording end position of each piece of information, is recorded in the iI area 1a.

As shown in FIG. 3, the TOC on the magneto-optical disk 1
In the fil area 1a and the information recording area 1b, spiral or concentric guide grooves 2, 2, . . . (shown by hatching for convenience) are formed in advance at predetermined intervals in the disk radial direction. Then, the absolute address of each part on the disk is ``1'' or ``O'' after biphase mark modulation, and the guide grooves 2, 2, etc. are shifted radially inward or outward depending on whether it is ``1'' or ``O''. Note that the above absolute address becomes pre-recorded information as rotation control information.

As shown in FIG. 4, the optical disk recording and reproducing apparatus according to the present embodiment includes a spindle motor 3 that supports and rotates the above-mentioned magneto-optical disk, and a spindle motor 3 that irradiates laser light onto the magneto-optical disk during recording and reproduction. An optical disk recording/reproducing apparatus comprising an optical head 4 and a coil 5 for applying a magnetic field onto a magneto-optical disk during recording is configured to perform recording using a so-called magnetic field modulation method, and is configured to perform recording using a so-called magnetic field modulation method. It is now possible to override, recording new information over the top.

The above-mentioned optical disc recording and reproducing apparatus is equipped with an input terminal 6 for inputting information to be recorded, and the analog information inputted from the input terminal 6 is converted into a digital signal by an A/D (analog/digital) converter 7 and then recorded. In the signal processing circuit 8, E F M (Eight Fourteen
Modulation) The signal is subjected to predetermined processing such as modulation, and then supplied to the coil driver 10.

The coil driver 10 drives the coil 5 based on the supplied signal, and at the same time, a laser beam is irradiated from the optical head 4 onto the magneto-optical disk 1, thereby recording a signal.

Figure 5 shows the signal recording format. This format is conventionally used in CDs, and consists of a 24-byte music information signal and 8-byte parity for error correction for each data field d. , a subcode C indicating the song number and time information of the music information, and a frame synchronization signal S indicating the beginning of the frame are added, and a frame a is continuously recorded. On the other hand, the subcode C in the TOC area 1a includes at least the recording end position of each piece of information, or the length from the recording start position to the recording end position, for information such as the recording start position of each piece of information in the format of a playback-only CD. This new information includes information such as size.

The regeneration system will be described below. In FIG. 4, the signal regenerated by the optical herad 4 is amplified by a reproducing amplifier 11. In FIG. The amplified signal is sent to a prerecorded information detection circuit 12 and a reproduction signal processing circuit 16.

The pre-recorded information detection circuit 12 is composed of, for example, a band-pass filter and a phase-locked loop, and generates a synchronized clock using the phase-locked loop with respect to the pre-recorded information in the reproduced signal extracted by the band-pass filter. It has become. Then, the clock frequency synchronized with the pre-recorded information consisting of the bi-phase mark modulated wave of the absolute address and the first reference frequency supplied from the first oscillator 13 are compared by the first comparator 14, and the difference signal is switched. The water is supplied to the container 15.

In addition, this device is equipped with a pre-recorded information demodulation unit (not shown), and when necessary during access etc., the pre-recorded information demodulation unit demodulates the bi-phase mark and recognizes the value of the absolute address as the pre-recorded information. It is something that will be done.

The reproduced signal processing circuit 16 performs EFM demodulation and other predetermined processing on the magneto-optical signal component in the reproduced signal supplied from the reproduced ambut 1, and the reproduced signal is sent to a D/A (digital/analog) converter 17 and It is designed to be output to the outside via the output terminal 18.

Further, a synchronization signal detection pulse indicating that the frame synchronization signal has been detected in each frame in the reproduction signal is supplied from the reproduction signal processing circuit 16 to the second comparator 20, where the synchronization signal detection pulse is supplied. The period is the second oscillator 19
The difference signal is sent to the switch 15. In addition,
When the reference frequencies of the first oscillator 13 and the second oscillator 19 are the same, the first oscillator 13 and the second oscillator 19 can be used in common. Furthermore, if the first reference frequency of the first oscillator 13 and the second reference frequency of the second oscillator 19 are in an integral multiple relationship, a single oscillator is used and the frequency of this oscillator is divided by a frequency divider. The frequency may be divided appropriately.

The signal processed by the reproduced signal processing circuit 16 is sent to a reproduced signal state determination circuit 21 as a reproduced signal state determination means,
Here, check whether the magneto-optical signal recorded on the magneto-optical disk 1 is being reproduced properly or not, or whether the optical head 4 is currently
A determination is made as to whether or not a recorded area is being reproduced.

This optical disc recording and reproducing apparatus is equipped with a control means consisting of a controller (not shown), and when recording a signal, this control means switches the switch 15 to the first comparator 14 side, as shown in FIG. 1(a). CLv based on pre-recorded information
While performing the I control (Sl), the recording operation is performed (S2
). That is, in this case, the difference signal of the first comparator 14 is sent to the spindle motor 3 via the switch 15, and the clock frequency synchronized with the biphase mark modulated wave of the absolute address as the pre-recorded information is output to the first oscillator. CLV control is performed so that the first reference frequency from No. 13 coincides with the first reference frequency.

Furthermore, as shown in FIG. 1(b), when reproducing the signal,
The reproduced signal state is detected by the reproduced signal state determination circuit 21 (
SL), and the control means determines whether or not the reproduction signal condition is good (S2), and if the recorded area is currently being reproduced and the reproduction signal condition is good. , the CLV control is switched to the reproduction signal side and a reproduction operation is performed (S3). That is, the difference signal from the second comparator 20 is supplied to the spindle motor 3 via the switch 15, and the period of the synchronization signal detection pulse supplied from the reproduction signal processing circuit 16 and the second difference signal from the second oscillator 19 are CLV control is performed so that the frequency matches the reference frequency. Therefore, even if slight variations in linear velocity occur during recording, the amount of signals reproduced per unit time during reproduction remains constant.

Also, if an unrecorded area is reached during playback, or
If it becomes difficult to perform CLV control based on the playback signal due to the deterioration of the playback signal condition due to frequent playback errors, etc., the next best measure is to control the CLV based on the pre-recorded information even during playback. <Since CLV control (S4) is performed, problems such as inability to perform CLV control during playback do not occur.

A more specific configuration of the reproduced signal state determination circuit 21 will be described below. In this embodiment, if an abnormality occurs in the synchronization state and the frame synchronization signal is continuously dropped while performing CLV control based on the reproduced signal, or if the optical head 4 approaches an area where information is not recorded. Detects when the frame synchronization signal is continuously lost, and adjusts the CLV during playback.
Control is switched to control based on pre-recorded information.

That is, as shown in FIG. 6, the reproduced signal state determination circuit 21 includes a counter 22, a comparator 23, and a reference value supply circuit 2.
4, from the reproduction signal processing circuit 16 to the counter 2.
A synchronization signal detection pulse indicating that a frame synchronization signal has been detected at a predetermined timing is supplied to the reset terminal of the counter 22, while a synchronization signal detection pulse indicating that a frame synchronization signal is missing at a predetermined timing is supplied to the clock terminal of the counter 22. A pulse is provided. As a result, the counter 22 counts the number of times a synchronization signal missing pulse is supplied, and the counter 22 is reset when a synchronization signal detection pulse is supplied.

Then, the value of the counter 22 is compared with the reference value supplied from the reference value supply circuit 24 in the comparator 23, and the value of the counter 22 is compared with the reference value supplied from the reference value supply circuit 24.
2 exceeds the reference value from the reference value supply circuit 24, in other words, if the frame synchronization signal is missing for a predetermined number of times or more, It is assumed that a synchronization abnormality has occurred in the recorded part or that the frame synchronization signal is not detected due to the unrecorded part, and the comparator 23 sends C to the switch 15.
The Lv control switching signal is output, and even during reproduction, it is configured to be switched to CLV@@ based on pre-recorded information.

[Example 2] Next, a second embodiment will be explained.

The second embodiment has substantially the same structure as the first embodiment except that the reproduced signal state determination circuit 21 is different from the first embodiment. For simplicity, only the reproduced signal state determination circuit 21 will be described below. In this embodiment, the reproduction signal state determination circuit 21 switches to CLV[@ based on pre-recorded information even during reproduction when reproduction errors occur continuously in the recorded portion of the information recording area 1b. It has become.

That is, as shown in FIG. 7, the reproduced signal state determination circuit 21 includes an inverter 25 and two NAND circuits 26 and 2.
7, a counter 28, a comparator 30, and a reference value supply circuit 31. Both NAs from the reproduction signal processing circuit 16
The above synchronizing signal detection pulse is supplied to one input terminal of the ND circuits 26 and 27. Further, an error flag indicating whether or not a reproduction error has occurred in each frame is input from the reproduction signal processing circuit 16 to the other input terminal of the NAND circuit 26 via the inverter 25.
The error flag is directly input to the other input terminal of 7. Therefore, if a playback error occurs in a certain frame and the error flag becomes the old gh level, N
While the value of the counter 28 is counted up by the signal supplied from the AND circuit 27 to the clock terminal of the counter 28, if no reproduction error occurs in a certain frame and the error flag becomes Low level, the NAND circuit 26
The counter 28 is reset based on a signal supplied to the reset terminal of the counter 28 from the counter 28.

Then, the value of the counter 28 and the reference value from the reference value supply circuit 31 are compared in the comparator 30, and when the value of the counter 28 exceeds the reference value, in other words, the value of the counter 28 is compared with the reference value from the reference value supply circuit 31. When a reproduction error occurs, it is assumed that the reproduction error has occurred frequently and the reproduction signal condition has deteriorated, and the comparator 30 outputs a CLV control switching signal. As a result, <CtV control is performed based on the pre-recorded information even during reproduction.

[Embodiment 3] Next, a third embodiment will be described based on FIGS. 8 to 11.

In this embodiment, it is determined whether or not a phase shift has occurred in the phase locked loop 35 included in the reproduced signal processing circuit 16, and when a phase shift has occurred, the CL2 control is switched.

That is, as shown in FIG. 8, in this example,
The reproduced signal processing circuit 16 includes a phase comparison circuit 32, a low pass filter (LPF) 33, and a voltage dependent oscillator (VCO).
A phase locked loop (PLL) 35 including 34 is provided. On the other hand, the reproduced signal state determination circuit 21 includes an edge detection circuit 36, a delay circuit 37, a D-type flip-flop 38, a frequency determination section 40, and an AND circuit 41.
It is equipped with The edge detection circuit 36 and delay circuit 3
7 and the flip-flop 38 constitute a phase determination section 42.

The edge detection circuit 36 is supplied with the reproduction binary signal ■ from the reproduction signal processing circuit 16, and the edge detection circuit 36
The edge at the inverted position of "1" and "0" in the value signal (2) is detected, and the edge signal (2) falling at the edge position is input to the clock input terminal GK of the flip-flop 38.

Further, the clock ■ outputted from the voltage dependent oscillator 34 is supplied to the delay circuit 37, where 1 of the period of the clock ■
The delayed signal ■ is delayed by /4 and is sent to flip-flop 3.
It is input to the data input terminal 8. Then, the phase determination signal V from the output terminal Q of the flip-flop 38 and the frequency determination signal ■ from the frequency determination section 40 are supplied to the AND circuit 41. Phase judgment signal V and frequency judgment signal■
is High when the phase and frequency are appropriate, respectively.
The CLV control is switched when the signal becomes H level and the cLVIII'4Ta switching signal output from the AND circuit 41 becomes Low level. Note that the frequency determining section 40 is configured to determine whether or not the frequency of the clock (2) is within an appropriate range.

FIG. 9 shows each signal of the above-described reproduction signal state determination circuit 21.
The time chart of ■ is shown. In the figure, (a) shows the transition of the reproduced binary signal l, (b) in the figure shows the transition of the edge signal ■, and (C) shows the transition of the clock ■. in this case,
Phase locked loop 35 is locked and playback 2
The phases of the value signal I and the clock ■ match.

Further, in FIG. 9, (d) shows the transition of the delayed signal (2), and e) shows the transition of the phase determination signal (2).

As is clear from comparing (b) and (d) in the figure, since the delayed signal ■ is always the old gh when the edge signal ■ falls, the phase determination signal V output from the flip-flop 38 is always at the old gh level.

Next, FIG. 10 shows a time chart when the phase of the clock (2) of the phase-locked loop 35 is delayed.

In this case, the clock ■ in (C) in the same figure is the reproduced binary signal I
However, it is delayed by about 215) cycles. Therefore, when the edge signal (2) falls, the delay signal (2) is always at the Low level, and therefore the phase determination signal V is always at the Low-level.

FIG. 11 shows a time chart when the phase of the clock (2) of the phase-locked loop 35 is advanced. In this case, the clock (C) in the figure is ahead of the reproduced binary signal I by about 215) cycles. Therefore, edge signal H
At the time of falling, the delay signal (2) is always at the Lo-level, and therefore the phase determination signal V is always at the Lo-level.

[Embodiment 4] FIG. 12 shows a reproduced signal processing circuit 16 and a reproduced signal state determination circuit 21 in a fourth embodiment.

This embodiment is effective when the reproduction binary signal, such as a so-called DC-free signal, has a signal format in which the energy density of both "'1" and "0" is approximately 50%. It is determined whether the signal state is appropriate or not, and if the reproduced signal state is poor, the control is switched to <CLV control based on pre-recorded information.

The reproduced binary signal from the reproduced signal processing circuit 16 is supplied to one input terminal of a NAND circuit 43, and is also supplied to one input terminal of a NAND circuit 45 via an inverter 44. Further, the pulse from the oscillator 46 is input to the other input terminal of the NAND circuits 43 and 45, and the NAND
The output signal of the AND circuit 43 is input to the addition side input terminal of the up/down (U/P) counter 47, and the output signal of the NAND circuit 45 is input to the subtraction side input terminal of the up/down counter 47. As a result, the oscillator 46
If the reproduced binary signal is "1" when a pulse is input from , the up/down counter 47 counts up, and if the reproduced binary signal is "0", the up/down counter 47 counts down.

Then, the comparator 48 compares the value of the up-down counter 47 with the reference value supplied from the reference value supply circuit 50, and the value of the up-down counter 47 exceeds the reference value, so that the energy density of the reproduced binary signal is When an abnormality occurs, it is assumed that the reproduced signal condition has deteriorated, and the comparator 48 outputs a CLV control switching signal.

[Embodiment 5] Next, based on FIG. 13, a reproduced signal state determination circuit 21 in a fifth embodiment will be described.

This embodiment is configured to switch to <CLV control based on pre-recorded information when the optical head 4 approaches an unrecorded area during reproduction.

That is, the reproduced signal state determination circuit 21 includes an envelope detection circuit 51 and a comparator 52. The reproduced signal state determination circuit 21 also includes a reproduced signal processing circuit 16 shown in FIG.
An analog playback signal before being binarized is supplied from.

Then, the envelope detection circuit 51 performs envelope detection of the analog playback signal, and the detected signal is sent to the comparator 5.
2, when the envelope-detected signal is smaller than the reference voltage Vc, in other words, when the optical head 4 is located in an unrecorded area where no reproduced signal is detected, the CLV control switching signal is activated. It becomes Lo-level and can be switched to CLV control based on pre-recorded information even during playback.

[Embodiment 6] Next, based on FIG. 14, a reproduced signal state determination circuit 21 in a sixth embodiment will be described.

In this embodiment as well, during reproduction, the optical head 4
When the camera is located in an unrecorded area in the area, the control is switched to <CtV control based on the pre-recorded information.

That is, the reproduced signal state determination circuit 21 includes an edge detection circuit 53 and a retriggerable monostable multi-byte break 54, and the reproduced binary signal from the reproduced signal processing circuit 16 is input to the edge detection circuit 53. There is. Retriggerable monostable multivibrator 54
The time constant is, for example, the maximum length of the edge interval of the reproduced binary signal shown in FIG. 9(b) (for example, 11
channel bits).

Therefore, when the optical head 4 is located in the recorded portion of the information recording area 1b of the magneto-optical disk l and the reproduced binary signal is input to the edge detection circuit 53, the retriggerable monostable multivibrator 54 is retriggered at any time, and the CLV control switching signal output from the retriggerable monostable multi-by-break 54 is always at the old gh level, and CLv! 11 control switching is not performed.

On the other hand, when the optical disc 4 is located in the unrecorded area of the information recording area 1b of the magneto-optical disk 1 and the reproduced binary signal is not input to the edge detection circuit 53, edge detection is not performed. Since the retriggerable monostable multivibrator 54 is not triggered, the CLV control switching signal from the retriggerable monostable multivibrator 54 becomes Lo- level, and even during playback, based on the pre-recorded information <CLV! Can be switched to IJ control.

The above embodiment was explained using an example in which the absolute address on the magneto-optical disk 1 was modulated with pi-phase marks.
The present invention is not limited to this, and other modulation methods with limited frequency bands may be used.

Furthermore, in the above embodiments, the magneto-optical disk 1 is used as an example of an optical disk, but the present invention can also be applied to other rewritable optical disks, such as a phase-change optical disk or a write-once optical disk. It is possible.

Further, in the above embodiment, the absolute address was recorded as pre-recorded information by biasing the guide grooves 2, 2, etc., but instead, the guide grooves 2, 2, and so on could be made to meander. good. Furthermore, instead of this, the absolute address may be recorded in advance using uneven pits. In that case, <CLV\VHB may be determined based on the pre-recorded information by comparing the period at which the pits are reproduced with a predetermined reference frequency.

〔Effect of the invention〕

As described above, the optical disc recording and reproducing apparatus according to the present invention is an optical disc recording device that records or reproduces information on an optical disc on which rotation control information for performing rotation control at a constant linear velocity over the entire surface is recorded as pre-recorded information. The playback device includes a playback signal state determining means for determining the state of the playback signal during playback, a means for controlling the rotation at a constant linear velocity using the pre-recorded information during recording, and a means for controlling the rotation at a constant linear velocity based on the playback signal during playback. A control means is provided for controlling the rotation, and switching the rotation control during reproduction to the rotation control based on the pre-recorded information when the reproduction signal condition is determined to be below a predetermined standard by the reproduction signal condition determination means. It is the composition.

As a result, during recording, rotation control is performed at a constant linear velocity based on pre-recorded information, and during playback, rotation control is performed based on the playback signal, so that the rotation is controlled to suit the purpose during recording and playback, respectively. Control comes into play.

In addition, during playback, if the playback signal status determination means detects that the rotation speed based on the playback signal has become difficult due to frequent playback errors or the inability to obtain a playback signal due to reaching an unrecorded area, the following: As a good measure, the rotation control is switched to based on pre-recorded information even during playback, so that problems such as the inability to perform rotation control during playback will no longer occur.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention. FIG. 1(a) is a flowchart showing the CLV control procedure during recording. FIG. 1(b) is a flowchart showing the procedure of CLV control during recording. FIG. 2 is a schematic plan view of a magneto-optical disk. FIG. 3 is an enlarged plan view of a magneto-optical disk. FIG. 4 is a block configuration of an optical disk recording/reproducing device. FIG. 5 is an explanatory diagram showing the signal recording format. FIG. 6 is a block diagram showing the main parts of the optical disc recording and reproducing apparatus. FIG. 7 is an optical disc recording and reproducing apparatus in the second embodiment. FIG. 8 is a block diagram showing the main parts of the optical disk recording/reproducing apparatus. FIGS. 8 to 11 show the third embodiment. FIG. Fig. 11 is a time chart showing the transition of signals around the phase-locked loop. Figs. 12 to 14 are block diagrams showing main parts of the optical disc recording and reproducing apparatus in the fourth to sixth embodiments, respectively. 1 is a magneto-optical disk (optical disk), and 21 is a reproduction signal state determination circuit (reproduction signal state determination means). 11(a) ← Recording operation) FIG. 2 11in(b) (A raw operation) 33

Claims (1)

[Scope of Claims] 1. In an optical disk recording/playback device that records or plays back on an optical disk in which rotation control information for performing rotation control at a constant linear velocity over the entire surface is recorded as pre-recorded information, playback is performed during playback. a reproduced signal state determination means for determining a signal state; during recording, the pre-recorded information is used to perform rotation control at a constant linear velocity; during reproduction, rotation control is performed at a constant linear velocity based on the reproduction signal; An optical disc recording characterized in that it is provided with a control means for switching rotation control during reproduction to rotation control based on the pre-recorded information when the reproduction signal condition is determined to be below a predetermined standard by the reproduction signal condition determination means. playback device.