JP2537552B2 - Optical disc player - Google Patents

Description

The present invention relates to an optical disc reproducing apparatus for reproducing information recorded on various types of optical discs such as a read-only type, a write-once type, and a rewritable type, and more particularly, 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 performing a rotation control with a constant linear velocity by a rotation control with a constant angular velocity.

[Conventional technology]

Conventionally, so-called compact discs (hereinafter referred to as CDs) in which music information and the like are recorded as digital signals by concave and convex pits are widely used. This CD is reproduced by a reproduction-only optical disk reproducing device.

A plurality of pieces of information are usually recorded continuously on the above-mentioned CD, and at the time of reproduction, an absolute address pre-recorded on the disc and a TOC (T
By collating each information recorded in the able of contents area with the absolute address of the recording start position, continuous reproduction of desired information, selective reproduction, etc. are performed.

On the other hand, when recording and using music information or the like on a rewritable disc such as a magneto-optical disc, which is under development in recent years, or a write-once optical disc that can be recorded only once,
It is desirable to provide a compatible optical disk recording / reproducing apparatus by making the reproducing method common with that of the conventional CD. In that case, when the optical disc is rotated during recording or reproduction, so-called constant linear velocity (hereinafter, referred to as CLV) rotation control, which is carried out by a CD, can be adopted. Furthermore, conventionally, only for playback
There is provided a so-called CD-ROM in which various data other than music information is recorded on a CD, and the CLV control is also adopted in this CD-ROM.

However, in the above CLV control, since it is necessary to change the data rotation speed according to the radial position of the disk, the rotation control of the motor becomes complicated, and the optical head is moved in the radial direction of the disk to obtain the desired value. When the truck is accessed, the rotation speed of the motor has to be changed before and after the access, which increases the time required for the access. Also, for example, when reproducing the information recorded on the CD-ROM and transferring it to the outside, in the CLV control, the time required for reproduction per one revolution of the disc increases as it goes to the outer peripheral side, so that it is necessary to reproduce the entire disc. There is a problem that the time becomes long.

In order to solve the above problems, when recording or reproducing information such as computer data that can be changed in time series, the rotation speed of the spindle motor is kept constant regardless of the disk radial position. , So-called constant angular velocity (hereinafter, CAV (Constant Angular Veloci
ty))) rotation control can be adopted.

However, in the CAV system, since the frequency of the clock for recording or reproduction is constant regardless of the radial position of the disc, there is a problem that the recording density decreases toward the outer peripheral side of the disc and the recording capacity becomes insufficient. Therefore, in the conventional CAV control, by increasing the recording frequency toward the outer peripheral side of the disc, the recording density is made substantially constant between the inner peripheral portion and the outer peripheral portion of the disc, and the recording capacity is increased. A method has also been proposed. When recording is performed by this MCAV method, it is necessary to gradually increase the frequency of the reproduction clock as it goes to the outer peripheral side of the disc even during reproduction.

[Problems to be Solved by the Invention]

By the way, in the conventional reproduction by the MCAV system, there are provided several kinds of frequency generators, one of the above frequency generators is selected corresponding to the disk area to be reproduced, and the signal of the frequency generator is reproduced. It is used as a reference signal.
At that time, the disk was divided into a plurality of areas corresponding to the above-mentioned several kinds of frequencies and the recording density was made almost constant, but the same recording density was not obtained as compared with the CLV system.

Further, on an optical disc such as a magneto-optical disc that can be arbitrarily recorded by a user, prerecorded information such as an absolute address is recorded in an unerasable state in advance. The format of the prerecorded information is CLV. Since an optical disk for controlling rotation and an optical disk for controlling rotation by MCAV are different, it is impossible to share a recordable optical disk with both CLV and MCAV.

[Means for solving the problem]

An optical disk reproducing apparatus according to the present invention is an optical disk reproducing apparatus for reproducing an optical disk in which prerecorded information for performing at least rotation control such that a linear velocity is constant is periodically formed along a track. Driving means for rotating the optical disc at a constant angular velocity, reproducing means for generating a signal on the optical disc, and a signal in the reproducing means based on a frequency component of prerecorded information in the signal reproduced by the reproducing means. And a reference signal generating means for generating a reference signal for reproduction.

[Work]

In the above configuration, since the pre-recorded information is formed in correspondence with CLV, when this optical disc is rotated by the CLV method, the frequency component of the pre-recorded information is almost constant regardless of the radial position of the optical disc, As in the above configuration
When rotated by the CAV method, the frequency component of the pre-recorded information becomes higher toward the outer peripheral side of the optical disc. Therefore, as described above, if the reference signal such as the reproduction clock is generated based on the frequency component of the pre-recorded information,
It becomes possible to accurately generate the reference signal whose frequency increases toward the outer peripheral side of the optical disc.

Also, for the purpose of controlling rotation at constant linear velocity (CLV), the optical disc on which pre-recorded information such as absolute address is recorded is played at MCAV while rotating at constant angular velocity (CAV). 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 in any case, it can be reproduced by the optical disc reproducing device of the present invention.

Also, for example, C manufactured for the purpose of reproducing by CLV method.
If the D-ROM is played back in the MCAV system, the playback time required for one rotation of the optical disc is constant regardless of the radial position in the MCAV system, so that the playback time required for the entire optical disc can be shortened. become.

[Embodiment 1] The following will describe one embodiment of the present invention with reference to FIGS. 1 to 6.

FIG. 3 shows the optical disc 1. This optical disc 1
Each type may be a read-only type, a write-once type, a rewritable type, etc., and the TOC (Table Of Contents
The ts) area 1a is provided, and most of the area outside the TOC area 1a is the information recording area 1b. While various information is recorded in the information recording area 1b, additional information relating to each information recorded in the information recording area 1b, for example, recording start and end positions of each information is recorded in the TOC area 1a. It is a thing.

As shown in FIG. 4, the TOC area 1 on the optical disc 1
.. (indicated by hatching for convenience) having spiral concentric circles are previously formed in the a and the information recording area 1b at predetermined intervals in the radial direction. The absolute address of each part on the optical disk 1 is biphase-mark-modulated as shown in Japanese Patent Laid-Open No. 64-39632,
The guide grooves 2, 2, ... Are biased inward or outward in the radial direction of the magneto-optical disk 1 depending on whether it is “1” or “0”.

The above-mentioned bi-phase mark modulated absolute address constitutes pre-recorded information and is recorded at a substantially constant period along the guide groove 2 forming a track. Therefore, the frequency of recording the absolute address within the same angle range becomes higher toward the outer peripheral side of the disc. As described above, the prerecorded information is provided on the premise that the optical disc 1 is recorded or reproduced by the CLV method.

For example, when recording or reproducing various data or the like on the optical disc 1, rotation control may be performed by the CAV method, while when recording music information or the like, rotation control may be performed by the CLV method. good. In the following, an optical disc reproducing apparatus for reproducing the optical disc 1 on which various data and the like are recorded by the MCAV system will be described.

As shown in FIG. 2, the optical disk reproducing apparatus according to the present embodiment includes a spindle motor 3 as a driving means for supporting and rotating the optical disk 1 and a constant angular velocity (CA).
V), that is, the CAV control circuit 4 that controls the rotation speed of the spindle motor 3 so that the optical disk 1 is rotated at a constant rotation speed regardless of the radial position of the optical head 5.
And irradiating the optical disc 1 with laser light, and based on the reflected light from the optical disc 1, recorded information such as various data recorded by concave and convex pits or magneto-optical signals and the absolute address recorded by the deviation of the guide groove 2. And an optical head 5 as a reproducing means for reproducing the prerecorded information composed of the bi-phase mark modulated wave. Hereinafter, the signal obtained by reproducing the above-mentioned recorded information will be referred to as a reproduction signal, and the signal obtained by reproducing the pre-recorded information will be referred to as the pre-recorded information as it is.

The optical disk reproducing device includes a reproducing amplifier 6 for amplifying the reproducing signal and the prerecorded information sent from the optical head 5.
It has. The reproduction signal amplified by the reproduction amplifier 6 is sent to the reproduction signal processing circuit 7, where predetermined processing is performed based on a reproduction clock supplied from a reproduction clock generation circuit 11 described later, and then the output terminal 8 Playback data is output via the.

The reproduction signal and the pre-recorded information amplified by the reproduction amplifier 6 are also sent to the pre-recorded information detection circuit 10 including, for example, a band pass filter, and here, only the pre-recorded information including the bi-phase mark modulated wave of the absolute address is included. Are to be extracted.

The pre-recorded information extracted by the pre-recorded information detection circuit 10 is sent to the reproduction clock generation circuit 11 as a reference signal generation means, while the reproduction signal is also sent from the reproduction amplifier 6 to the reproduction clock generation circuit 11. Then, in the reproduction clock generation circuit 11, a reproduction clock as a reference signal proportional to the bit frequency f ₃ of the bi-phase mark modulated wave of the absolute address which is the pre-recorded information is generated and sent to the reproduction signal processing circuit 7. Is configured. Since the optical disc 1 is rotationally controlled by the CAV method, the bit frequency f ₃ of the bi-phase mark modulated wave of the absolute address becomes higher toward the outer peripheral side of the optical disc 1 as described above, and therefore the reproduction clock Frequency f _{2 is} also optical disc 1
Becomes higher toward the outer peripheral side. As a result, the reproduction signal processing circuit 7 extracts reproduction data at a cycle corresponding to the radial position of the optical disc 1.

Next, a more detailed configuration of the recovered clock generation circuit 11 will be described with reference to FIG.

The regenerated clock generation circuit 11 is configured as a kind of phase locked loop (PLL), and includes a phase comparison circuit 12, a low pass filter (LPF) 13, an adder 14, a voltage controlled oscillator (VCO) 15, and a divider. A frequency divider 16 and an F / V (frequency / voltage) converter 17 are provided.

The reproduction signal from the reproduction amplifier 6 is input to one input terminal of the phase comparison circuit 12. The output signal of the phase comparison circuit 12 is input to the low pass filter 13, and the low pass filter 13
The output voltage V _{2 of the above} is input to one input terminal of the adder 14. Further, the bi-phase mark modulated wave of the absolute address, which is the pre-recorded information, is input from the pre-recorded information detection circuit 10 to the input terminal of the F / V converter 17, and the bit frequency f _{3 of} this bi-phase mark modulated wave corresponds. Voltage
It is converted to V ₁ and input to the other input terminal of the adder 14.

The output voltage V ₃ of the adder 14 is input to the voltage controlled oscillator 15, where oscillation is performed at the frequency f ₂ according to the output voltage V ₃ . Then, the output signal of the voltage controlled oscillator 15 becomes the reproduction clock. This reproduction clock is input to the other input terminal of the phase comparison circuit 12 via the frequency divider 16 in addition to being sent to the reproduction signal processing circuit 7.

As indicated by I in FIG. 5, the frequency f of the prerecorded information is
As described above, ₃ becomes higher toward the outer peripheral side of the optical disc 1. Further, as indicated by II in the figure, the frequency f ₁ of the reproduction signal is higher than the frequency f ₃ of the pre-recorded information, but the frequency f _{1 of the} reproduction signal also becomes higher toward the outer peripheral side of the optical disc.

FIG. 6 shows the transition of the output signal of each part of the reproduction clock generation circuit 11 when the inner peripheral part of the optical disc 1 is accessed to the outer peripheral part. As shown in (a) of the figure, at the time of reproduction of the inner peripheral portion T ₁ , the reproduction input to one input terminal of the phase comparison circuit 12 as long as reproduction of the same track or a group of adjacent tracks is performed. The frequency f ₁ of the signal is almost constant,
Gradually increasing the frequency f ₁ of the reproduced signal during the access operation T _2, the playback T ₃ of the outer peripheral portion after the access end is higher than the playback T ₁ of the inner peripheral portion frequency f ₁ of the reproduced signal value Is almost constant at.

Further, as shown in (b) and (c) of the figure, the frequency f ₃ of the prerecorded information and the output voltage V _{1 of the} F / V converter 17 also show the same tendency as the frequency f _{1 of the} reproduction signal, During reproduction of the inner peripheral portion, T ₁ is almost constant, during access operation, T ₂ gradually increases, and during reproduction of the outer peripheral portion, T ₃ is almost constant.

In addition, as shown in FIG.
The output voltage V ₂ of T 1 causes a slight change in T ₂ during the access operation, but is almost constant regardless of the radial position of the optical disc 1.

Further, as shown in (e) and (f) of FIG.
The output voltage V _{3 of} 14 and the frequency f _{2 of the} reproduction clock are almost constant during reproduction in the inner peripheral portion T _{1 and} gradually increase although a slight variation occurs in T ₂ during the access operation. It becomes almost constant in ₃ . As shown in (e) in the figure, the output voltage V ₃ of the adder 14 mainly corresponds to the output voltage V _{1 of the} F / V converter 17, in other words, the change in the frequency f ₃ of the prerecorded information. Since the output voltage V ₃ of this adder 14 changes toward the outer circumference of the optical disc 1, the frequency f _{2 of the} reproduction clock moves toward the outer circumference of the optical disc 1 as shown in (f) of FIG. Becomes higher with.

As described above, the frequency f ₂ of the reproduction clock changes mainly corresponding to the frequency f ₃ of the prerecorded information. Therefore, even if there is an unrecorded portion of information at the time of access and the reproduction signal cannot be detected, the pre-recorded information can be detected. Generation is planned. As a result, the PLL in the reproduction clock generation circuit 11 is locked immediately after the access is completed, so that the reproduction can be started immediately after the access.

The above-mentioned access is divided into coarse access for moving the optical head 5 near the target track at high speed and fine access for moving the optical head 5 to the target track while reading the absolute address included in the pre-recorded information after the rough access. Considering this, the pre-recorded information can be completely reproduced at least during the fine access, so that the reproduction clock can be synchronized at least during the fine access.

[Second Embodiment] Next, a second embodiment will be described with reference to FIGS. 7 to 10.

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

As shown in FIG. 7, the recovered clock generation circuit 11 has a first
The phase locked loop (first PLL) 21 and the second phase locked loop (second PLL) 22 are provided. The reproduction clock generation circuit 11 generates a reproduction clock based on the reproduction signal (binary signal) from the reproduction amplifier 6 during normal reproduction, while based on the pre-recorded information from the pre-recorded information detection circuit 10 during access. It is configured to generate a recovered clock.

More specifically, the first PLL 21 includes a first phase comparison circuit 23, a first low-pass filter (first LPF) 24 arranged in a subsequent stage, and a first low-pass filter (first LPF) 24 arranged in a subsequent stage. Voltage controlled oscillator (first VCO) 25 and first voltage controlled oscillator 2
The first frequency divider 26 for dividing the reproduced clock, which is the output signal of 5, by the predetermined frequency division ratio and feeding it back to the first phase comparison circuit 23.
It has and.

A switching device 27 is arranged in the front stage of the first PLL 21, and the first phase comparison circuit 23 is described below and is generated based on the reproduction signal from the reproduction amplifier 6 or the pre-recorded information via the switching device 27. Any of the signals from the third frequency divider 33 is input. During normal reproduction, the reproduction signal of the bit frequency f ₁ is input to the first phase comparison circuit 23 based on the switching signal, and the first PL based on this reproduction signal.
A recovered clock of frequency f ₂ is generated at L21.

The second PLL 22 is provided with a second phase comparison circuit 28 to which a bi-phase mark modulated wave of an absolute address, which is prerecorded information of a bit frequency f ₃ , is input, and a second phase comparison circuit 28 arranged at the subsequent stage.
Low pass filter (second LPF) 30, a second voltage controlled oscillator (second VCO) 31 arranged at the subsequent stage, and a frequency f ₄ which is an output signal of the second voltage controlled oscillator 31. And a second frequency divider 32 which divides the signal at a predetermined frequency division ratio and feeds it back to the second phase comparison circuit 28.

The signal of the frequency f ₄ from the second voltage controlled oscillator 31 is frequency-divided by the third frequency divider 33 at a predetermined frequency division ratio 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 becomes substantially equal to the bit frequency f _{1 of the} reproduction signal.

In the switch 27, the signal from the third frequency divider 33 is selected at the time of access, and the first PLL 21 generates the reproduction clock based on the prerecorded information. The frequency of the signal from the third frequency divider 33 is the bit frequency of the reproduced signal.
Since it is almost equal to f ₁ , the frequency is almost equal regardless of whether the reproduction clock is generated based on the reproduction signal or the prerecorded information.

Also in this second embodiment, since the reproduction clock is generated based on the pre-recorded information during access,
Even if it is impossible to detect the playback signal during access,
The reproduction clock during access is smoothly generated. Since the reproduction clock is synchronized during the access period, the reproduction clock can be quickly synchronized with the reproduction signal after the input to the first phase comparison circuit 23 is switched to the reproduction signal after the access is completed. This is realized, and the reproduction operation can be started in a short time after the end of access.

Now, as shown in FIG. 8A, the area N ₁ (the range of absolute addresses n _{1 to} n ₂ ) and the area N ₂ (the range of absolute addresses n _{3 to} n ₄ ) in the information recording area 1b of the optical disc 1 ) And area N ₃
Record information of various data or the like (the absolute address range n ₅ ~n ₆₎ is assumed to be recorded. In that case, since the pre-recorded information is recorded on the entire surface of the optical disc 1 in correspondence with CLV and the rotation is controlled by the CAV method, the frequency f ₃ of the pre-recorded information is as shown in (b) in the figure. 1 gradually increases from the inner circumference to the outer circumference, and in the figure (c)
, The frequency f ₁ of the reproduced signal in each region N _{1 to} N ₃
Becomes gradually higher toward the outer peripheral side of the optical disc 1.

Here, consider a case where the optical head 5 accesses the area N ₃ near the outer circumference while the area N ₁ near the inner circumference is being reproduced. In that case, as shown in FIG. 9A, the area N ₁
At the time of reproduction T ₁ , the frequency f ₁ of the reproduction signal when reproducing the same track or a group of adjacent tracks is substantially constant. After that, when the access is started, the access period T ₂
The frequency f _{1 of the} reproduction signal gradually increases when passing through the region N ₂ inside, and the stage where the reproduction of the region N ₃ is started after the end of access
When reproducing the same track or a group of adjacent tracks at T ₃ , the frequency f _{1 of the} reproduced signal becomes almost constant.

Further, when accessing the areas N ₁ to N ₃ , the frequency f ₃ of the prerecorded information and the frequency f _{2 of the} reproduction clock are the same as before access (period T ₁ ), during access (period T ₂ ), and after access (period T ₂ ). ₃ ) changes as shown in Fig. ₃ (b) and (d). Further, the switching signal supplied to the switching device 27 changes as shown in FIG. However, when the switching signal is at the high level, the signal from the third frequency divider 33 based on the prerecorded information is input to the first phase comparison circuit 23, and the switching signal is
When it is at the low level, the reproduction signal is input to the first phase comparison circuit 23.

As described above, in the second embodiment, as shown in FIG. 10, the signal is reproduced while rotating the optical disc 1 under the CAV control (S1), and the access to the predetermined absolute address is instructed. For example, the access operation is started (S2), and the switch 27 is switched so that the output signal of the second frequency divider 33 is immediately input to the first phase comparison circuit 23 (S3).

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

In the above-described embodiment, the switching of the switch 27 is performed depending on whether or not the access is being performed, but it is also possible to determine the reproduced signal state such as detecting the amplitude of the reproduced signal or detecting the error state.

Also, in each of the above embodiments, the reproducing apparatus for the optical disc 1 is described. However, when the optical disc 1 is, for example, a magneto-optical disc as a rewritable disc, the optical disc reproducing device shown in FIG. By adding
The optical disc 1 can be recorded, reproduced and erased. Further, as the optical disk 1, besides the rewritable type, a write-once type capable of performing desired recording only once may be used. In either case, the regeneration system can be constructed in the same manner as in the above embodiment.

Further, the above-mentioned optical disk reproducing apparatus can also reproduce a CD-ROM, which is a reproduction-only type optical disk in which various data are originally recorded so as to reproduce by the CLV system. In that case, the CD-ROM disc may be one in which the information pit string is biased as the absolute address of the prerecorded information, for example, as shown above.
According to the method, since the required playback time per disc rotation is constant regardless of the radial position, the required playback time of the entire disc can be shortened.

It should be noted that the above embodiment has been described by using the example in which the prerecorded information is recorded by displacing the guide groove 2 in correspondence with the bi-phase mark modulated wave of the absolute address.
However, the present invention is not limited to this, and another method in which the frequency band is limited may be used. Further, the guide groove 2 may be meandered instead of being biased.

〔The invention's effect〕

The optical disc reproducing apparatus according to the present invention, as described above,
A reference signal for signal reproduction by the reproduction means is generated using the pre-recorded information recorded for controlling the rotation by the CLV method.

As a result, since the pre-recorded information is formed so as to correspond to CLV, the frequency component of the pre-recorded information becomes almost constant regardless of the radial position of the optical disc when this optical disc is rotated by the CLV method. When rotated by the CAV method as described above, the frequency component of the prerecorded information becomes higher toward the outer peripheral side of the optical disc. Therefore, as described above, if the reference signal such as the reproduction clock is generated based on the frequency component of the pre-recorded information, the reference signal whose frequency increases toward the outer peripheral side of the optical disc can be accurately generated. As a result, high-speed access can be performed without changing the disk rotation speed at the time of access, and information can be immediately reproduced after access by the above reference signal.

Also, for the purpose of controlling rotation at constant linear velocity (CLV), the optical disc on which pre-recorded information such as absolute address is recorded is played at MCAV while rotating at constant angular velocity (CAV). 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 in any case, it can be reproduced by the optical disc reproducing device of the present invention.

Also, for example, C manufactured for the purpose of reproducing by CLV method.
If the D-ROM is played back in the MCAV system, the frequency of the playback clock increases in the MCAV system as it moves toward the outer circumference of the optical disc, so the playback speed and the transfer speed to external devices can be increased in the outer circumference. As a result, the time required for reproduction and transfer can be shortened.

Therefore, the large capacity of data and CAV
It is possible to provide a highly reliable disc reproducing apparatus which has the high speed characteristic of the system.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention. FIG. 1 is a block diagram showing the internal structure of the recovered clock generation circuit. FIG. 2 is a block diagram of the optical disk reproducing apparatus. 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 disk and the frequency of the reproduction signal and the prerecorded information. FIG. 6 is a time chart showing transitions of signals of respective parts in the recovered clock generation circuit before and after access. 7 to 10 show the second embodiment. FIG. 7 is a block diagram showing the internal structure of the recovered clock generation circuit. FIG. 8 is an explanatory diagram showing a recorded state of information on the optical disc and changes in frequencies of prerecorded information and a reproduction signal. FIG. 9 is a time chart showing transitions of signals of respective parts in the recovered clock generation circuit before and after access. FIG. 10 is a flowchart showing the outline of the control procedure at the time of access. 1 is an optical disk, 3 is a spindle motor (driving means),
Reference numeral 5 is an optical head (reproducing means), and 11 is a reproduction clock generating circuit (reference signal generating means).

Continuation of front page (56) Reference JP-A-60-177404 (JP, A) JP-A-64-39632 (JP, A) JP-A-59-213003 (JP, A) JP-A-55-146624 (JP , A) JP 57-210481 (JP, A) JP 59-144289 (JP, A) JP 64-39632 (JP, A) JP 1-251371 (JP, A) JP 63-220476 (JP, A) JP 62-38022 (JP, A) JP 59-186138 (JP, A) Actually developed 55-36498 (JP, U)

Claims (1)

(57) [Claims] 1. An optical disk reproducing apparatus for reproducing an optical disk in which pre-recorded information for performing at least rotation control such that a linear velocity is constant is periodically formed along a track. Drive means for rotationally driving at a constant angular velocity, reproducing means for reproducing a signal on an optical disk, and reference for signal reproduction by the reproducing means based on the frequency component of prerecorded information in the signal reproduced by the reproducing means. An optical disk reproducing apparatus, comprising: a reference signal generating means for generating a signal.