JPH1097765A - Recording medium, its reproducing apparatus, data reproducing apparatus and data reproducing method - Google Patents

Abstract

(57) Abstract: The present invention provides a recording medium, a reproducing apparatus, a data reproducing apparatus, and a data reproducing method for automatically setting optimum characteristics according to the type of the recording medium. It is intended to be. A pickup for reading data recorded in a data recording area, a waveform equalizer for performing a waveform equalization process on a high-frequency modulation signal output from the pickup, and a demodulation process on an output signal of the waveform equalizer. A recording device for reproducing data recorded in a data recording area by a reproducing device having a demodulating means for performing the following. The data recording area indicates a recording form of the data recorded in the data recording area. The parameters are recorded, and the waveform equalizer can switch the waveform equalization characteristics based on the contents of the parameters demodulated by the demodulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium on which digital data such as compressed moving picture video data, sub-picture data and audio data are recorded, a reproducing apparatus for reproducing the recording medium, and reproducing the data. The present invention relates to a data reproducing apparatus and a data reproducing method, and more particularly to a data reproducing apparatus and a data reproducing method capable of automatically controlling a reproducing condition to an optimal state.

[0002]

2. Description of the Related Art As is well known, conventionally, as an optical disk, for example, a compact disk (CD) dedicated to music is used.
In addition, laser disks (LD) and the like that also support moving image images have become widespread.

On the other hand, recently, moving picture video data, audio data, sub-picture data (for example, subtitle data) and the like are compressed and recorded on an optical disc having the same radius as that of the above-mentioned CD at a high density. A system has been developed in which a plurality of different languages and subtitles are recorded, and at the time of reproduction, audio and subtitles in a desired language can be freely selected and reproduced. An optical disk corresponding to this type of system is generally called a DVD.

[0004] As described above, various types of optical disks are available as optical optical disks. A reproducing apparatus that reproduces such an optical disk includes a rotary servo unit that controls the rotation of the optical disk, and a modulation signal recorded on the optical disk by irradiating a laser beam onto a signal recording surface of the optical disk and detecting reflected light thereof. It has an optical pickup for reading the data.

[0005] The modulated signal read by the optical pickup is first input to a waveform equalization circuit and subjected to a waveform equalization process. Then, the signal subjected to the waveform equalization processing is supplied to an error correction circuit, subjected to error correction processing, and then guided to a demodulation circuit to be demodulated.

[0006]

In the conventional optical disk reproducing apparatus, the waveform equalizing circuit has a fixed characteristic. The reason for this is that it is premised that the optical disc and the reproducing apparatus for reproducing the optical disc are in one-to-one correspondence.

However, there are actually different types of optical disks as described above. Therefore, when an optical disc of a type different from the original corresponding optical disc is mounted on the optical disc reproducing apparatus and the optical disc is reproduced, the characteristic of the modulation signal obtained from the optical pickup is
In some cases, the characteristics may be completely different from those intended by the playback device. In such a case, the user may mistake the optical disk reproducing device for a failure or an optical disk defect.

Further, even if the optical discs have the same standard,
Various parameters do not always satisfy the standard ideally due to differences in optical disk manufacturers, changes in characteristics of the optical disk reproducing device, and the like. As a result, the optical disc reproducing apparatus may not be able to obtain an ideal modulated signal. In such a case, the probability of a data error increases, and a good reproduction signal cannot be obtained.

Therefore, the present invention has been made in view of the above circumstances, and has a recording medium capable of automatically setting an optimum characteristic according to the type of the recording medium, a reproducing apparatus thereof, and a data reproducing apparatus. And a data reproducing method.

[0010]

According to the present invention, a part of the recording data includes a parameter for obtaining at least a waveform equalization characteristic which is a standard for reading the recording data.

A recording medium according to the present invention includes a pickup for reading data recorded in a data recording area, a waveform equalizing means for performing a waveform equalization process on a high-frequency modulation signal output from the pickup, It is intended for a device in which data recorded in a data recording area is reproduced by a reproducing device having a demodulating means for demodulating an output signal of the equalizing means. In the data recording area, parameters indicating the recording format of the data recorded in the data recording area are recorded, and based on the contents of the parameters demodulated by the demodulating means, the waveform equalizing means In this case, the equalization characteristics can be switched.

Further, the reproducing apparatus according to the present invention reproduces a recording medium in which a part of the recorded data includes a parameter capable of obtaining at least a waveform equalization characteristic which is a standard for reading the recorded data. It is intended for those who do. A pickup for reading recording data from the recording medium, a waveform equalizing means for performing waveform equalization processing on the high-frequency modulation signal output from the pickup, and a demodulation means for performing demodulation processing on the output signal of the waveform equalization means. ,
Switching means for switching the waveform equalization characteristics of the waveform equalization means based on the contents of the parameters demodulated by the demodulation means is provided.

[0013] A reproducing apparatus according to the present invention is intended for reproducing a recording medium in which a part of recording data includes a parameter indicating a recording mode of the recording data. A pickup for reading recording data from the recording medium, a waveform equalizing means for performing waveform equalization processing on the high-frequency modulation signal output from the pickup, and a demodulation means for performing demodulation processing on the output signal of the waveform equalization means. And a determining means for determining the type of the recording medium based on the contents of the parameters demodulated by the demodulating means.

According to the above configuration, when the recording medium is reproduced, the control direction of the reproduction characteristic, the selection of the reproduction characteristic, or the type and the recording characteristic of the recording medium can be determined based on the contents of the parameters. Thus, the optimum signal reproduction characteristics can be constructed at an early stage.

Further, a data reproducing apparatus according to the present invention performs a waveform equalization process on an input high-frequency modulated signal, and comprises a waveform equalization means capable of selectively switching a plurality of waveform equalization characteristics. 2 for binarizing the output signal of the waveform equalizing means
Value conversion means, error correction means for detecting an error in the output signal of the binarization means and performing error correction processing, and error occurrence rate detection means for obtaining information on the occurrence rate of the error detected by the error correction means. Switching means for switching the waveform equalization characteristics of the waveform equalization means based on the error occurrence rate information obtained by the error occurrence rate detection means.

Further, a data reproducing method according to the present invention comprises:
A waveform equalization process is performed on an input high-frequency modulation signal. A waveform equalization process in which a plurality of waveform equalization characteristics can be selectively switched, and a signal subjected to the waveform equalization process in the waveform equalization process are performed. A binarization step for binarizing, an error occurrence rate detection step of detecting an error of the signal binarized in the binarization step and obtaining error occurrence rate information, and an error occurrence rate detection step And a switching step of switching the waveform equalization characteristics of the waveform equalization step based on the error occurrence rate information obtained in step (a).

According to the above configuration and method, it is possible to obtain an optimum waveform equalization characteristic according to the error occurrence rate of the input data, and to improve the data reproduction capability.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the overall configuration of the optical disk reproducing apparatus described in the first embodiment. That is, in FIG. 1, reference numeral 11 denotes an optical disk, which is rotationally driven by a disk motor 12. On the signal recording surface side of the optical disc 11,
An optical pickup 21 is provided. The optical pickup 21 is controlled to move in the radial direction of the optical disk 11 by a pickup feed motor (not shown).

The high-frequency modulated signal output from the optical pickup 21 is input to a waveform equalizer 23 via a preamplifier 22 and subjected to waveform equalization. The waveform-equalized modulated signal is input to the data slicer 24 and binarized. The binarized signal is supplied to the data extraction unit 25. The data extracting unit 25 includes a data synchronous clock generator using a phase locked loop (PLL) circuit (not shown).

Therefore, in the data extracting section 25, a data clock is generated, and a modulation signal is sampled using the data clock. As a result, the data extraction unit 25 extracts digital data recorded on the optical disk 11. The extracted digital data is supplied to an error correction circuit (ECC) 26 and a sync separator 27 that separates a synchronization signal.

The data clock reproduced by the data extraction unit 25 and the synchronization signal obtained by the sync separator 27 are input to a spindle servo circuit 28. The spindle servo circuit 28 fetches a synchronization signal synchronized with the data clock, and controls the rotation speed of the disk motor 12 based on the frequency and phase of the synchronization signal. In this case, the spindle servo circuit 28 controls the disk motor 12 so that a sync signal of a predetermined frequency can be obtained from the sync separator 27 while normal reproduction is being performed.
Is controlled.

In FIG. 1, reference numeral 29 denotes a data processor, which controls the slice level of the data slicer 24, switches and controls the characteristics of the PLL circuit in the data extraction unit 25, and the operation timing of the spindle servo circuit 28 and the sync separator 27. And the output control of the error correction circuit 26. In particular, the data processor 29 controls the characteristics of the waveform equalizer 23 as described later.

Further, the optical disk reproducing apparatus is provided with a pickup servo means for the optical pickup 21. The pickup servo means includes a focus error detector 31, a three-beam tracking error detector 32, and a phase difference tracking error detector 33.
And a servo signal processing unit 34 for processing each error signal generated from the detection units 31, 32, 33 to obtain control signals for error correction.
The control signal obtained from the servo signal processing unit 34 is supplied to the optical pickup 21 via the amplifier 34a.

FIG. 2 shows the configuration of the focus error detector 31, the three-beam tracking error detector 32, and the phase difference tracking error detector 33 which constitute the pickup servo means. That is, FIG.
2 shows the arrangement of the photodetectors A to F constituting the light detection unit of the optical pickup 21, the inside of the preamplifier 22, and the error detection units 31, 32, and 33.

In this example, the photodetector comprises four photodetectors A, B, C, and D, and two photodetectors E and F disposed before and after the photodetectors. Ideally, the central reflected beam is received at a uniform ratio (area) on each light receiving surface of the four-divided photodetectors A, B, C, and D. In a good tracking state, the front and rear photo detectors E and F also receive the corresponding reflected beams uniformly.

The outputs of the photodetectors A to F are introduced into buffer amplifiers 22a to 22f, respectively.
Of these outputs A and C of the buffer amplifiers 22a and 22c,
Are added by the adder 35 and output as an (A + C) signal. The outputs B and D of the buffer amplifiers 22b and 22d are added by the adder 36 and output as a (B + D) signal.

The outputs of the adders 35 and 36 are input to the subtracter 37, respectively, where (A + C)-(B + D)
By performing the following arithmetic processing, it is extracted as a focus error signal. The focus error signal is input to an S-shaped level detection circuit (not shown) provided in the focus error detection unit 31 to be used for detecting a focus state. The detection operation will be described later.

The outputs of the adders 35 and 36 are:
It is input to the phase difference detector 38. This phase difference detector 38
Detects the phase difference between the (A + C) signal and the (B + D) signal. This detection signal is used as a phase difference tracking error signal. This phase difference tracking error signal is used as an effective signal when a DVD is reproduced.

Further, the buffer amplifiers 22e, 22e
Each output of f is subjected to a subtraction process by the subtractor 39 to generate an (EF) signal. This (EF) signal is used as a three-beam tracking error signal. This three-beam tracking error signal is used as an effective signal when a CD is reproduced.

The buffer amplifiers 22a, 22a
The outputs of b, 22c, and 22d are added by an adder 41 to generate an (A + B + C + D) signal. This (A + B + C + D) signal is an RF (Radio Freq) signal.
uency) signal is supplied to the waveform equalizer 23.

FIG. 3 shows one of the features of the present invention. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. That is, the outputs of the four-division photodetectors A, B, C, and D of the optical pickup 21 are added by the adder 41 and input to the waveform equalizer 23. Here, the waveform equalizer 23 can switch to at least two waveform equalization characteristics. The switching of the waveform equalization characteristic is realized by switching one or both of the delay characteristic and the amplitude characteristic. In FIG. 3, characteristics 1, characteristic 2, characteristics 3,... After switching are shown.

The switching of the waveform equalization characteristics is achieved by the data processor 29 judging the data from the data slicer 24 or the reproduced data after error correction has been performed, so that the optimum characteristics are selected. I have.

As means for selecting the optimum characteristic, there are various embodiments as follows. FIG. 4A shows the operation progress when the optimum characteristic is selected. First, when the optical disk reproducing apparatus starts reproducing the optical disk 11, the optical pickup 21 is moved to a predetermined position,
The rotation speed of the disk motor 12 is automatically set to a predetermined speed.

The waveform equalization characteristics of the waveform equalizer 23 are set to predetermined characteristics. Further, the optical system of the optical pickup 21 and the predetermined beam characteristics are set to predetermined characteristics. Also, the data sampling clock in the data processor 29 is set to a predetermined frequency.

Here, there is an agreement between the optical disk 11 and the optical disk reproducing apparatus. That is, as long as the optical disk 11 is rotated at a predetermined speed and set to a predetermined waveform equalization characteristic and a predetermined beam characteristic, any type (for example, a DVD 1 having a single-layer structure or a double-layer structure) DVD 2) Optical disk 1
Even if it is 1, a recording area (for example, a lead-in area) where a signal can be read is provided, and a parameter indicating the type of the optical disc 11 is recorded in this area [see FIG. 4B]. .

The data processor 29 determines that the parameter read from the area is, for example, "1000".
Is repeated, it is determined that the loaded optical disk 11 is a DVD1 having a single-layer structure, and if "1100" is repeated, it is determined to be a DVD2 having a two-layer structure. When the parameter is "11
If "00" is repeated, it may be determined that it is DVD2, otherwise, it may be determined that it is DVD1.

As described above, the data processor 29 can determine whether the optical disk 11 being reproduced is the DVD1 or the DVD2. Therefore, the data processor 29 can set the rotation speed of the disk motor 12 to a speed suitable for the loaded optical disk 11. Further, the data processor 29 can switch the internal characteristic of the waveform equalizer 23 to the characteristic for DVD1 or the characteristic for DVD2.

Further, the above-mentioned parameter may be a specific parameter representing a relationship between a recording bit clock frequency of recording data and a spatial frequency when the optical pickup 21 reads the recording data, for example, a ratio. In this case, the data processor 29 is programmed to automatically set the characteristics of each unit such as the optical system and the signal processing system according to the contents of the parameters.

For example, for a DVD-ROM or DVD-R,
Regarding the data recording density, the linear density was 0.267 μm /
Bit and 0.293 μm / bit
There are types. Then, “0000” is recorded as a parameter on a DVD with a linear density of 0.267 μm / bit, and “0001” is recorded on a DVD with a linear density of 0.293 μm / bit.

Therefore, the data processor 29 determines that the DVD has a linear density of 0.267 μm / bit when the read parameter is “0000”, and determines that the read parameter is “0001” when the read parameter is “0001”. It is determined that the DVD has a density of 0.293 μm / bit, and the characteristics of each unit such as an optical system and a signal processing system are automatically switched.

Further, the DVD-RAM has a data recording density of a linear density of 0.409 to 0.435 μm.
/ Bit, and its parameter is “001”.
"0" is recorded. Thus, a linear density of 0.40
The reason that the width of 9 to 0.435 μm / bit is
-RAM is ZCLV (Zone Constant Linear Velocity)
) Method is adopted.

FIGS. 5A and 5B show an example in which the first embodiment is developed. That is, when the type of the optical disk 11 is determined, the data processor 29
Can set the rotation speed of the disk motor 12 to a speed suitable for the loaded optical disk 11, as in the previous example. The data processor 29 also determines the internal characteristics of the waveform equalizer 23 for DVD1 or DVD.
It is possible to switch and set the characteristics for two.

In this example, the characteristics of each portion are set to the characteristics corresponding to the optical disk 11 being reproduced, and then the characteristics of the waveform equalizer 23 are particularly finely adjusted. First, in the first example, the characteristics of the waveform equalizer 23 are represented by a1,
By slightly switching to a2, a3,..., for example, a characteristic for obtaining the highest reproduction level is searched. Then, for example, if the highest reproduction level is obtained at the time of the characteristic a2, the characteristic a2 is adopted as the characteristic of the waveform equalizer 23. Although the switching of the characteristics is described only in the column of the DVD1 in FIG. 5A, the switching of the characteristics can be similarly applied to the case where the DVD2 is reproduced.

In the second example, for example, a plurality of parameters for obtaining finer waveform equalization characteristics are recorded in a part of the recording data of DVD2. Then, the content of the parameter which can be read best among the plurality of parameters is determined, and the waveform equalization characteristic according to the content is set.

For example, three parameters X1, X2, X3 having slightly different bit clock frequencies are recorded on a disk. The parameters read in the best condition with little noise due to the once set waveform equalization characteristics indicate the instruction for setting the normal waveform equalization characteristics.

That is, when the parameter X2 is read normally, it is assumed that the currently set waveform equalization characteristic is the best. When the parameter X1 is read normally, it is assumed that the currently set waveform equalization characteristic is shifted from the normal waveform equalization characteristic to a higher side (upper side) on the frequency axis. Similarly, the parameter X3
Is normally read, it is assumed that the currently set waveform equalization characteristic is shifted to a lower side (lower side) on the frequency axis from the normal waveform equalization characteristic.

Therefore, a command for adjusting the current waveform equalization characteristic to a lower side is described as the parameter X1, and a command for adjusting the current waveform equalization characteristic to a higher side is described as the parameter X3. Is described.

In the above description, after the type of the optical disk 11 is determined, the fine waveform equalization characteristics are determined.
The adjustment of the characteristics is to be performed. However, for example, in the case of an optical disc reproducing apparatus in which it is determined that the DVD 2 is to be mounted from the beginning, the processing of the second example can be executed immediately.

That is, for example, a plurality of parameters for obtaining a finer waveform equalization characteristic are recorded in a part of the recording data of the DVD 2. Then, the content of the parameter which can be read best among the plurality of parameters is determined, and the waveform equalization characteristic according to the content is set.

In the system including the optical disk 11 and the reproducing apparatus, not only the parameters for setting the waveform equalization characteristics but also the parameters for switching the characteristics of each unit are recorded on the optical disk 11. The respective units can be switched on the playback device side using this parameter. Switching targets in this case include, for example, a compensation amplifier and a signal processing mode.

In the first embodiment described above, parameters are recorded on the optical disk 11 itself, and when the parameters are read and decoded, setting data for setting optimum reproduction characteristics to the optical disk 11 can be obtained. I can do it.

Next, the structure of the currently mixed optical disk 11 will be described. 6A to 6C show the cross sections of various optical disks 11 in principle. First,
FIG. 6A shows a conventional music CD, the thickness of which is defined as 1.2 mm.

FIGS. 6 (b) and 6 (c) show DVDs that achieve high-density recording and record data-compressed video and audio codes. A density optical disk is also included. That is, this DVD includes a so-called read-only DVD-ROM (Read Only Memory).
mory) and recordable DVD-RAM (Read After Mem)
ory).

FIG. 6B shows a DVD having a one-layer structure composed of one substrate on which a signal recording surface is formed. FIG. 6C shows a two-layer D-type substrate obtained by bonding two substrates each having a signal recording surface formed thereon.
2 shows a VD-ROM. In any case, the thickness of the entire optical disk 11 is 1.2 mm, and the thickness of the substrate is defined as 0.6 mm. In addition, both the CD and the DVD are equally defined as having a diameter of 12 cm / 8 cm.

FIGS. 7 (a) to 7 (c) show the signal recording surface of the optical disk 11 from above in an enlarged manner.
FIG. 7A shows the structure of a signal recording surface of a CD.
7B shows the structure of the signal recording surface of the DVD-ROM, and FIG. 7C shows the structure of the signal recording surface of the DVD-RAM.

FIGS. 7A to 7C also show dimensions such as the thickness, pit width, and track width of the disk substrate. As described above, some optical disks 11 have different track pitches, and some have different recording formats.

Next, the focus servo will be described. That is, the above-described focus error signal is supplied to the S-shaped level detection circuit of the focus error detection unit 31. This S-shaped level detection circuit detects that the level of the focus error signal changes as shown in FIG. 8 according to the focus state.

The level information detected by the S-shaped level detection circuit is input to the servo signal processing section 34. Then, the servo signal processing section 34 causes the optical system of the optical pickup 21 to perform focus servo based on the input level information.

The S-character detection level information can also be used as a material for determining the type of the optical disk 11. In this case, after the type of the optical disc 11 is determined based on the S-curve detection level information, a final confirmation can be obtained based on the above parameters.

That is, in order to determine the type of the optical disk 11 based on the S-character detection level information, the above-described 1
An optical disc 11 such as a CD or DVD having a layered structure and an optical disc 11 such as a DVD-ROM or DVD-RAM having a two-layered structure make use of the fact that the reflectivity upon irradiation with a light beam is different.

That is, in the optical disk 11 such as a CD or DVD having a one-layer structure, the light beam has a reflectance of 60 to 70%.
On the other hand, it is 25 to 30% for the optical disk 11 such as a DVD-ROM having a two-layer structure, and 20% or less for the optical disk 11 such as a DVD-RAM having a two-layer structure.

For this reason, for example, when the focus error signal is at a high level, it can be determined that the optical disk 11 such as a CD or DVD having a one-layer structure is mounted, and when the focus error signal is at a low level, DVD-ROM or DVD-RAM with two-layer structure
It can be determined that the optical disk 11 is mounted.

In order to determine whether the optical disk 11 has a one-layer structure or an optical disk 11 having a two-layer structure, an objective lens (not shown) built in the optical pickup 21 is gradually approached to the optical disk 11 and a focus error signal is generated. It is also possible to use the number of times of reaching the focal point determined from the above.

When the determination is made by this means, the optical disk 11 is stopped without rotating without using the rotation servo system of the optical disk 11 via the spindle servo circuit 28, or forcedly and slowly. It is desirable that the rotation be less than half a rotation or constant rotation. The reason is,
This is because use of a rotary servo system may cause a runaway.

The rotation speed at which the optical disk 11 is slowly rotated at a constant speed is the minimum rotation speed at which the rotation speed of the optical disk 11 is controlled by CLV (Constant Linear Velocity), or the assumed minimum rotation speed of the optical disk 11. A number is desired. Such a control method of the rotation speed is similarly performed when a tracking error signal described later is used for discriminating the optical disk 11.

FIG. 9 shows a recording data structure of an optical disk 11 as an example of a recording medium to which the present invention is applied. The optical disk 11 is a double-sided bonded disk having a storage capacity of about 5 Gbytes on one side, for example, and has a number of recording tracks arranged between a lead-in area on the inner peripheral side and a lead-out area on the outer peripheral side. ing. Each track is composed of a large number of logical sectors, and various information (digital data appropriately compressed) is stored in each sector.

FIG. 10 shows the data structure of a video file recorded on the optical disk 11 shown in FIG. As shown in FIG. 10, the video file includes file management information 1 and video data 2. The video data 2 includes a video data unit (block), an audio data unit (block), a sub-picture data unit (block), and information NAV (DSI; Data S) required to control the reproduction of these data.
earch Information and PCI; Picture ControlInforma
and an NAV unit (block) recording the NAV unit (including an option).

Each unit is divided into packets of a fixed data size for each data type, for example. The video data unit, audio data unit and sub-picture data unit are reproduced in synchronization with each other based on the NAV arranged immediately before these unit groups.

That is, in the aggregate of a plurality of logical sectors shown in FIG. 9, a system area for storing system data used for reproducing the optical disk 11, a volume management information area, and a plurality of file areas Are formed.

As shown in FIG. 10, of the plurality of file areas, for example, as shown in FIG. 10, main image information (video data in the figure) and sub-image information ( (Sub-picture data in the figure), audio information (audio data in the figure), reproduction information, and the like.

Here, since the NAV unit has a data recording margin (reserved portion), a new parameter can be described in the reserved portion. As described above, since the NAV unit is described at a plurality of locations (the outer circumference side and the inner circumference side) of the optical disc 11, several check points are provided, and various parameters for system inspection are provided in the NAV unit at this position. Can be described.

The parameter may be information for controlling the rotation speed of the disk motor 12, as well as for specifying the waveform equalization characteristic. In this way, the reproduction condition of the optical disk reproducing device can always be set to the optimum condition according to the optical disk 11.

According to the first embodiment, since at least the reproduction output state of the modulation signal recorded on the optical disk 11 can be identified, the type of the optical disk 11 can be determined. Further, when a modulated signal recorded on the optical disk 11 is read, it is possible to obtain at least a reproduction characteristic of the modulated signal closer to an ideal characteristic. Further, it is possible to maintain the reproduction condition of the optical disk reproducing device in the best condition by utilizing the parameters of the optical disk 11.

Next, a second embodiment of the present invention will be described. That is, in FIG. 11, reference numeral 51 denotes an optical disk, which is rotationally driven by a disk motor 52. An optical pickup 53 is arranged on the signal recording side of the optical disk 51. This optical pickup 53
Is controlled in the radial direction of the optical disk 51 by a pickup feed motor (not shown).

The high-frequency modulated signal output from the optical pickup 53 is input to a waveform equalizer 55 via a preamplifier 54 and subjected to waveform equalization. The modulated signal whose waveform has been equalized is input to the data slicer 56 and binarized. The binarized signal is supplied to the data extraction unit 57. The data extracting section 57 includes a data synchronous clock generator using a phase locked loop (PLL) circuit (not shown).

For this reason, the data extraction unit 57 generates a data clock and samples a modulation signal using the data clock. As a result, the data extraction unit 57 extracts digital data recorded on the optical disk 51. The extracted digital data is supplied to a synchronization detection / demodulation unit 58 including an error correction circuit (ECC), a sync separator for separating a synchronization signal, a demodulator for converting a modulation signal into an original bit string, and the like.

The output of the synchronization detection / demodulation unit 58 is input to an error correction unit 59, where error correction is performed by a predetermined method. The serial data that has been subjected to the error correction processing is input to the data processing unit 60, and is subjected to data separation processing, decoding processing, and the like.

The data clock in the data processing unit 60 and the synchronization signal in the synchronization detection / demodulation unit 58 are input to the disk servo circuit 61. The disk servo circuit 61 takes in a synchronization signal synchronized with the data clock, and controls the rotation speed of the disk motor 52 based on the frequency and phase of the synchronization signal. The disk servo circuit 61 controls the rotation speed of the disk motor 52 so as to obtain a synchronization signal of a predetermined frequency and phase during normal reproduction.

The output of the preamplifier 54 is input to an error signal generator 62. The error signal generator 62 is adapted to each servo system such as a focus servo, a phase difference tracking servo, and a three-beam tracking servo using an output signal from a photoelectric conversion element built in the optical pickup 53, as described later. Then, a focus error signal, a phase difference tracking error signal, and a three-beam tracking error signal are generated.

The focus error signal is supplied to the focus servo circuit 63, and the phase difference tracking error signal and the three-beam tracking error signal are input to the tracking servo circuit 64. The output of the focus servo circuit 63 is supplied to a focus drive unit of the optical pickup 52. The output of the tracking servo circuit 64 is supplied to a tracking drive unit of the optical pickup 53 and also to a pickup feed motor drive unit 65.

The pickup feed motor controls the movement of the optical pickup 53 in the radial direction of the optical disk 51, and is driven when supplementing the tracking control or during a jump operation. The optical pickup 53 is supplied with an NA switching signal for switching the numerical aperture (NA) from a disc type discriminating circuit (not shown).

When the optical pickup 53 uses the two-lens switching method (two optical lens systems are prepared), the switching of the lens is performed by the NA switching signal.
In the case of the aperture switching method, the aperture of the aperture is switched. In the case where the optical pickup 53 is a bifocal lens system (two focal points exist in the optical axis direction), switching is not particularly required.

FIG. 12 shows a configuration of the photoelectric conversion element in the optical pickup 53 and an error signal generator 62 for obtaining a focus error signal, a phase difference tracking error signal, and a three-beam tracking error signal. That is, FIG. 12 shows the arrangement of the photodetectors A to F, which are the photoelectric conversion elements of the optical pickup 53, the inside of the preamplifier 54, and the inside of the error signal generator 62.

In this example, the photoelectric conversion element comprises four-divided photodetectors A, B, C, and D, and two photodetectors E and F arranged before and after it.
Ideally, the central reflected beam is received at a uniform ratio (area) on each of the light receiving surfaces of the four-divided photodetectors A, B, C, and D. In a good tracking state, the front and rear photo detectors E and F also receive the corresponding reflected beams uniformly.

The outputs of the photodetectors A to F are introduced into buffer amplifiers 54a to 54f, respectively.
Among them, the outputs A and C of the buffer amplifiers 54a and 54c
Are added by an adder 66 and output as an (A + C) signal. The outputs B of the buffer amplifiers 54b and 54d,
D is added by the adder 67 and output as a (B + D) signal.

Then, the outputs of the adders 66 and 67 are input to the subtracter 68, respectively, where (A + C)-(B + D)
By performing the arithmetic processing of (1), it is extracted as a focus error signal. This focus error signal is
S (not shown) provided in the focus servo circuit 63
It is input to a character level detection circuit and is used for detecting a focus state.

The outputs of the adders 66 and 67 are
The signal is input to the phase difference detector 69. This phase difference detector 69
Detects the phase difference between the (A + C) signal and the (B + D) signal. This detection signal is used as a phase difference tracking error signal. This phase difference tracking error signal is used as an effective signal when a DVD is reproduced.

Further, the buffer amplifiers 54e, 54
Each output of f is subjected to a subtraction process in the subtractor 70 to generate an (EF) signal. This (EF) signal is used as a three-beam tracking error signal. This three-beam tracking error signal is used as an effective signal when a CD is reproduced.

The buffer amplifiers 54a, 54a
The outputs of b, 54c, and 54d are subjected to an addition process in an adder 71, thereby generating an (A + B + C + D) signal. This (A + B + C + D) signal is supplied to the waveform equalizer 55 as an RF signal.

Here, returning to FIG. 11, the error occurrence situation in the error correction section 59 is as follows.
The error rate is monitored by the error rate detector 72. The error rate detection unit 72 switches the waveform equalization characteristics of the waveform equalizer 55 according to the detected error rate. The error rate detected by the error rate detection unit 72 is also used for switching characteristics of other parts.

FIG. 13 shows the processing of the error correction section 59. First, the error correction unit 59 outputs the demodulated signal 1
The data of the frame (for one block) is fetched based on the synchronization signal (step A1), and the error checking process is performed line by line using the error checking word. (Step A2). Thereby, the error correction unit 59
Can obtain information on the number of errors and error locations.

If the error can be corrected, the error correction section 59 performs an error correction process (steps A3 and A3).
4), for one block of data serving as a correction unit,
It is determined whether or not all error correction processing has been completed (step A5). Then, if all error correction processes have not been completed for one block, the error correction unit 59 performs error detection and correction for the next row or column. When all the error inspections and corrections for one block have been completed, the data of the next block is fetched.

If the error cannot be corrected in step A3, the error correcting section 59 describes a flag in association with the row or column determined to be impossible (step A6). This flag is stored in a memory for management. Then, it is determined whether the inspection for one block has been completed (step A7). If the inspection has been completed, the error correction unit 59 takes in the data of the next block. The processing shifts to the row or column inspection processing.

As described above, the error check and correction processing is performed for each block. The number of flags and the information on the error position (the number of errors) are monitored by the error rate detection unit 72. The error rate detected by the error rate detection unit 72 is used to control switching of characteristics of each unit of the optical disk reproducing device.

FIG. 14 shows the procedure of the control operation of the error rate detecting section 72. That is, when the optical disk reproducing apparatus starts, the error rate detecting section 72 determines whether or not the elapsed reproduction time TN has passed the predetermined time T1 (step B1). This is because the data error rate is high when the optical disk reproducing apparatus starts.

Thereafter, the error rate detection section 72 determines whether or not the number of flags FN for a plurality of blocks for which error correction is performed is equal to or more than a predetermined number F1 (step B2), and shifts to the processing of step B1.

If the reproduction elapsed time TN has passed the predetermined time T1, the error rate detecting section 72 proceeds to step B3, and again determines whether or not the flag number FN for a plurality of blocks is equal to or larger than the predetermined number F1. . If the number of flags FN is equal to or more than the predetermined number F1 during normal reproduction after the lapse of the predetermined time T1, for example, there is a scratch on the optical disc 51,
Since an abnormality often occurs, the error rate detection unit 72
Executes the warning on / off (steps B4 and B
5).

When the number of flags FN is equal to or less than the predetermined number F1,
In step B6, the error rate detection unit 72 determines whether the number of errors EN for a plurality of blocks is equal to or less than a predetermined number E1. If the number of errors EN is equal to or less than the predetermined number E1, the error rate detection unit 72 determines that the current reproduction characteristic matches the optical disc 51 being reproduced, and maintains the current characteristic (step B8).

If the number of errors EN is equal to or greater than the predetermined number E1, the error rate detecting section 72 determines that the waveform equalization characteristics of the waveform equalizer 55 do not match, and firstly sets the waveform equalization characteristics to the first. (Step B8). And
After waiting for a signal processing period for a plurality of blocks (step B9), the error rate detection unit 72 returns to step B3 and determines again whether the error number EN has increased or decreased.

At the second time, if the number of errors EN is reduced, the error rate detecting section 72 determines that the control direction is correct, and further moves the waveform equalizer 55 toward the control direction.
The switching control of the waveform equalization characteristics is performed. Conversely, the error number E
If N has increased, the error rate detection unit 72 determines that the control direction is wrong, and switches and controls the waveform equalization characteristic of the waveform equalizer 55 in the direction opposite to the previous direction, and again executes step B3. Return to the processing of.

By controlling the waveform equalization characteristics of the waveform equalizer 55, data is reproduced in the best condition. The characteristic control at this time can be realized by controlling the amplitude characteristic of the waveform equalizer 55, controlling the delay characteristic, or controlling both of them.

FIG. 15 shows various examples of objects to be controlled when controlling the waveform equalization characteristics of the waveform equalizer 55. This waveform equalizer 55 can vary its delay characteristics and amplitude characteristics, respectively. The variable control of these characteristics is realized by generating a delay characteristic control signal and an amplitude characteristic control signal from the error rate detection unit 72 described above. The error rate detection unit 72 is specifically a microprocessor MPU.

In the waveform equalizer 55,
The characteristic can be switched by changing the delay amount of the delay element D therein, or the characteristic can be switched by changing the value of a coefficient k in a multiplier that multiplies the output of each delay element D by a coefficient. .

FIG. 16 shows an operation example for controlling the switching of the characteristics of the waveform equalizer 55. In this operation example, the waveform equalization characteristic is set such that the minimum number of errors is realized. Is slightly different.

First, the error rate detecting section 72 sets the delay characteristic of the waveform equalizer 55 to an intermediate characteristic in the variable range (step C1). Next, the error rate detection unit 72 switches the amplitude characteristics of the waveform equalizer 55 in a plurality of stages, and sets the number of errors EN1, EN2,.
EN (n) is stored. Then, the error rate detecting section 72 selects the smallest one of the numbers of errors EN (mi
n) is detected, and the amplitude characteristic corresponding to the minimum error number EN (min) is set again in the waveform equalizer 55 (steps C2 and C3).

Next, the error rate detection section 72 switches the delay characteristics of the waveform equalizer 55 to a plurality of stages, and sets the number of errors EN (n + 1) and EN (n +
2),..., EN (m) are stored. Then, the error rate detection unit 72 detects the minimum error EN (min) from the stored number of errors, and detects the minimum error EN (m).
The delay characteristic corresponding to (in) is set in the waveform equalizer 55 again (steps C4 and C5).

By performing the above-described processing, it is possible to acquire the recording data of the optical disk 51 in the best condition. This control process may be performed periodically at regular time intervals or may be performed within the first predetermined period. After that, the control process may be performed in a fixed characteristic state or performed according to the reproduction position of the optical disk 51. Good thing.

According to the second embodiment, the modulation signal recorded on the optical disk 51 is read out, and the binarized output of the modulation signal or the error occurrence rate when the demodulated signal is subjected to error correction is determined. It is possible to monitor and set an optimum waveform equalization characteristic according to the content of the error occurrence rate information.

Next, another example for switching and controlling the characteristics of the waveform equalizer 55 will be described. That is,
FIG. 17 shows a change in the error rate with respect to a change in the amplitude characteristic of the waveform equalizer 55. Assuming that the variable range of the amplitude characteristic of the waveform equalizer 55 is from A to B, first, an intermediate amplitude characteristic C is set, and the amplitude at which the error rate is minimized is set based on the error rate at that time. The characteristic D is obtained.

Thereafter, the amplitude characteristics are sequentially changed at regular intervals from D to A, and an amplitude characteristic E at which the error rate becomes three times the minimum error rate is obtained. Also, the amplitude characteristic is changed from D to B
, The amplitude characteristic F at which the error rate becomes three times the minimum error rate is obtained. Then, an intermediate amplitude characteristic between E and F is set as an optimum amplitude characteristic.

FIGS. 18 to 21 show flowcharts for realizing the switching control of the waveform equalization characteristics as described above. First, the error rate detector 72 sets the amplitude characteristic of the waveform equalizer 55 to a characteristic C in the middle of the variable range (step D1), and reads the error rate at that time (step D2). After that, the error rate detection unit 72 sequentially changes the amplitude characteristic of the waveform equalizer 55 from C to A side at regular intervals, thereby obtaining the amplitude characteristic D that minimizes the error rate (step D3). ~ D9).

Next, the error rate detecting section 72 sequentially changes the amplitude characteristic of the waveform equalizer 55 from C to the B side at regular intervals to obtain the error rate in the amplitude characteristic D obtained earlier. Also, by searching for the amplitude characteristic D in which the error rate becomes small (steps D10 to D17), the amplitude characteristic D in which the error rate becomes minimum within the range from A to B is obtained.

Thereafter, the error rate detector 72 sequentially changes the amplitude characteristic of the waveform equalizer 55 from D to A side at regular intervals, so that the error rate becomes three times the minimum error rate. Find the amplitude characteristic E (steps D18 to D2)
3). Next, the error rate detection unit 72 sequentially changes the amplitude characteristic of the waveform equalizer 55 from D to B side at regular intervals, so that the error rate becomes three times the minimum error rate. F is obtained (steps D24 to D29).

The error rate detecting section 72 sets the intermediate amplitude characteristic between the amplitude characteristics E and F obtained as described above as the optimum amplitude characteristic (step D30).

In the above description, the control of the amplitude characteristic for switching the waveform equalization characteristic of the waveform equalization circuit 55 has been described. However, the present invention is not limited to this, and the waveform equalization characteristic controls the delay characteristic. Alternatively, both the amplitude and the delay may be controlled. It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the scope of the present invention.

[0116]

As described in detail above, according to the present invention,
It is possible to provide a recording medium, a reproducing apparatus, a data reproducing apparatus, and a data reproducing method for automatically setting optimum characteristics according to the type of the recording medium.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and is a block diagram showing the entirety of an optical disk reproducing apparatus.

FIG. 2 is a block diagram showing a pickup servo means according to the first embodiment;

FIG. 3 is a block diagram showing details of a main part of the first embodiment.

FIG. 4 is an exemplary view for explaining an example of the operation of the first embodiment.

FIG. 5 is a view for explaining another example of the operation of the first embodiment.

FIG. 6 is a side view showing the structure of various optical disks.

FIG. 7 is an enlarged perspective view showing signal recording surfaces of various optical disks.

FIG. 8 is a characteristic diagram showing a level change of a focus error signal.

FIG. 9 is a diagram showing a recording data structure of an optical disc as an example of a recording medium to which the present invention is applied.

FIG. 10 is a view showing a logical structure of data recorded on the optical disc.

FIG. 11 shows a second embodiment of the present invention.
FIG. 1 is a block diagram showing the entirety of an optical disk reproducing device.

FIG. 12 is a block diagram showing details of an optical pickup, a preamplifier, and an error signal generator according to the second embodiment;

FIG. 13 is a flowchart showing the operation of the error correction unit according to the second embodiment.

FIG. 14 is a flowchart showing the operation of the second embodiment.

FIG. 15 is a block diagram showing details of a main part of the second embodiment.

FIG. 16 is a flowchart showing the operation of a modification of the second embodiment.

FIG. 17 is a characteristic diagram shown to explain another modification of the second embodiment;

FIG. 18 is a flowchart showing the operation of another modification.

FIG. 19 is a flowchart showing the operation of another modified example.

FIG. 20 is a flowchart showing the operation of another modification.

FIG. 21 is a flowchart showing the operation of another modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Optical disk, 12 ... Disk motor, 21 ... Optical pickup, 22 ... Preamplifier, 23 ... Waveform equalizer, 24 ... Data slicer, 25 ... Data extraction part, 26 ... Error correction circuit, 27 ... Sync separator, 28 ... Spindle servo circuit, 29 ... Data processor, 31 ... Focus error detecting section, 32 ... 3 beam tracking error detecting section, 33 ... Phase difference tracking error detecting section, 34 ... Servo signal processing section, 35, 36 ... Adder, 37 ... Subtractor, 38 ... Phase difference detector, 39 ... Subtractor, 41 ... Adder, 51 ... Optical disk, 52 ... Disk motor, 53 ... Optical pickup, 54 ... Preamplifier, 55 ... Waveform equalizer, 56 ... Data slicer, 57: data extraction unit, 58: synchronization detection / demodulation unit, 59: error correction unit, 60: data Processing unit, 61: disk servo circuit, 62: error signal generation unit, 63: focus servo circuit, 64: tracking servo circuit, 65: pickup feed motor drive unit, 66, 67: adder, 68: subtractor, 69 ... Phase difference detector, 70: subtractor, 71: adder, 72: error rate detector.

Claims (41)

[Claims] 1. A recording medium characterized in that a part of the recording data includes a parameter capable of obtaining at least a waveform equalization characteristic which is a standard for reading the recording data. 2. The apparatus according to claim 1, wherein the recording data is read by an optical pickup, and the parameter represents a length per unit bit of the recording data on the recording medium. The recording medium according to the above. 3. The parameter is set such that a linear density of the recording data on the recording medium is 0.267 μm / bit, 0.293 μm / bit, or 0.409 to 0.435 μm / bit. 2. The recording medium according to claim 1, wherein at least one of the bits is represented. 4. The recording medium according to claim 1, wherein the parameter is recorded in a lead-in area of the recording medium. 5. The recording medium according to claim 1, wherein a plurality of types of parameters are recorded for designating characteristics of each section of the playback apparatus. 6. The recording medium according to claim 1, wherein the parameters are recorded at a plurality of locations on the recording medium. 7. The recording medium according to claim 1, wherein the parameter is identification data for identifying a type of the recording medium. 8. The recording data is read by an optical pickup, and the parameter controls a frequency-to-amplitude characteristic of a high-frequency modulation signal output from the optical pickup to change a waveform equalization characteristic. 2. The recording medium according to claim 1, wherein the recording medium is data. 9. The recording data is read by an optical pickup, and the parameter controls a frequency-to-delay characteristic of a high-frequency modulation signal output from the optical pickup to change a waveform equalization characteristic. 2. The recording medium according to claim 1, wherein the recording medium is data. 10. The recording data is read by an optical pickup, and the parameter controls both frequency-to-amplitude characteristics and frequency-to-delay characteristics for a high-frequency modulation signal output from the optical pickup,
2. The recording medium according to claim 1, wherein the data is data for changing a waveform equalization characteristic. 11. A pickup for reading data recorded in a data recording area, a waveform equalizer for performing a waveform equalization process on a high-frequency modulation signal output from the pickup, and a demodulation of an output signal of the waveform equalizer. By a reproducing device having a demodulating means for performing processing, a recording medium on which data recorded in the data recording area is reproduced,
In the data recording area, a parameter indicating a recording format of data recorded in the data recording area is recorded, and based on the content of the parameter demodulated by the demodulating means, the waveform equalizing means A recording medium characterized in that its waveform equalization characteristics can be switched. 12. The recording medium according to claim 11, wherein the parameter represents a length per unit bit of data recorded in the data recording area. 13. The parameter, wherein a linear density of data recorded in the data recording area is 0.267 μm /
12. The recording medium according to claim 11, wherein at least one of a bit, a bit of 0.293 μm / bit, and a bit of 0.409 to 0.435 μm / bit is represented. . 14. The parameter is data for changing a waveform equalization characteristic by controlling a frequency-to-amplitude characteristic of the waveform equalization means with respect to a high-frequency modulation signal output from the pickup. The recording medium according to claim 11, wherein 15. The method according to claim 15, wherein the parameter is data for changing a waveform equalization characteristic by controlling a frequency versus delay characteristic of the waveform equalization means with respect to a high-frequency modulation signal output from the pickup. The recording medium according to claim 11, wherein 16. The parameter changes a waveform equalization characteristic by controlling both a frequency-to-amplitude characteristic and a frequency-to-delay characteristic of the waveform equalization means for a high-frequency modulation signal output from the pickup. The recording medium according to claim 11, which is data. 17. A reproducing apparatus for reproducing a recording medium on which a part of the recording data includes a parameter capable of obtaining at least a waveform equalization characteristic which is a standard for reading the recording data, the recording medium being reproduced. A pickup for reading the recording data from the pickup, a waveform equalizer for performing a waveform equalization process on the high-frequency modulated signal output from the pickup, a demodulator for performing a demodulation process on an output signal of the waveform equalizer, And a switching unit for switching a waveform equalization characteristic of the waveform equalization unit based on the contents of the parameter demodulated by the unit. 18. The reproducing apparatus according to claim 17, wherein said demodulating means includes a binarizing means for binarizing an output signal of said waveform equalizing means. 19. The switching means controls a frequency-to-amplitude characteristic of the waveform equalization means with respect to a high-frequency modulation signal output from the pickup to change the waveform equalization characteristic. The playback device according to claim 17. 20. The switching device according to claim 13, wherein the switching unit controls a frequency-to-delay characteristic of the waveform equalizing unit with respect to a high-frequency modulation signal output from the pickup to change the waveform equalizing characteristic. The playback device according to claim 17. 21. The switching means controls both a frequency-to-amplitude characteristic and a frequency-to-delay characteristic of the waveform equalizing means for a high-frequency modulated signal output from the pickup, and changes the waveform equalizing characteristic. 18. The playback device according to claim 17, wherein: 22. The reproducing apparatus according to claim 17, wherein the parameter represents a length per unit bit of the recording data on the recording medium. 23. The parameter is set such that a linear density of the recording data on the recording medium is 0.267 μm / bit, 0.293 μm / bit, or 0.409 to 0.435 μm / bit. 18. The reproducing apparatus according to claim 17, wherein at least one of the bits represents a bit. 24. The playback device according to claim 17, wherein the parameter is a command for controlling characteristics of each unit of the playback device. 25. A reproducing apparatus for reproducing a recording medium on which a part of the recording data includes a parameter indicating a recording form of the recording data, a pickup for reading the recording data from the recording medium; A waveform equalizing unit that performs a waveform equalization process on the output high-frequency modulated signal; a demodulation unit that performs a demodulation process on the output signal of the waveform equalization unit; A discriminating means for discriminating the type of the recording medium. 26. A waveform equalizer for performing a waveform equalization process on an input high-frequency modulation signal, wherein a waveform equalizer capable of selectively switching a plurality of waveform equalization characteristics and an output signal of the waveform equalizer are used as two signals. Binarizing means for converting the value, an error correcting means for detecting an error of an output signal of the binarizing means and performing an error correcting process, and an error occurrence for obtaining information on an occurrence rate of the error detected by the error correcting means Data comprising: a rate detection unit; and a switching unit that switches a waveform equalization characteristic of the waveform equalization unit based on error occurrence rate information obtained by the error occurrence rate detection unit. Playback device. 27. The apparatus according to claim 26, wherein the switching means controls a frequency-to-amplitude characteristic of the waveform equalizing means for the high-frequency modulated signal to change the waveform equalizing characteristic. Data playback device. 28. The apparatus according to claim 26, wherein the switching means controls a frequency-to-delay characteristic of the waveform equalization means for the high-frequency modulation signal to change the waveform equalization characteristic. Data playback device. 29. The switching means controls both a frequency-to-amplitude characteristic and a frequency-to-delay characteristic of the waveform equalizing means for the high-frequency modulated signal to change the waveform equalizing characteristic. The data reproducing apparatus according to claim 26, wherein 30. The switching means, comprising: first means for setting a frequency-to-delay characteristic of the waveform equalization means to an intermediate characteristic in a variable range; In a state where the delay characteristic is set to an intermediate characteristic in the variable range, the frequency-amplitude characteristic of the waveform equalizing means is changed to search for an amplitude characteristic that minimizes the error rate, and A second means for setting in the equalizing means, and the second means changing the frequency versus delay characteristics of the waveform equalizing means in a state where the frequency versus amplitude characteristics of the waveform equalizing means are set. 30. The data reproducing apparatus according to claim 29, further comprising: third means for searching for a delay characteristic that minimizes an error occurrence rate and setting the same in the waveform equalizing means. 31. The switching means sets the frequency-to-amplitude characteristic of the waveform equalization means so that the error occurrence rate falls within a range between a minimum value and a value higher than the minimum value by a predetermined amount. 30. The data reproducing apparatus according to claim 29, wherein the setting is set to: 32. The switching unit sets the frequency-to-delay characteristic of the waveform equalization unit so that the error occurrence rate falls within a range between a minimum value and a value higher than the minimum value by a predetermined amount. 30. The data reproducing apparatus according to claim 29, wherein the setting is set to: 33. The switching means, wherein the frequency-amplitude characteristic and the frequency-delay characteristic of the waveform equalizing means are set between a minimum value of the error occurrence rate and a value higher by a predetermined amount than the minimum value. 30. The data reproducing apparatus according to claim 29, wherein the setting is made so as to fall within the range of. 34. A waveform equalization process for performing a waveform equalization process on an input high-frequency modulation signal, wherein a plurality of waveform equalization characteristics can be selectively switched, and a waveform equalization process in the waveform equalization process. A binarization step of binarizing the processed signal; an error occurrence rate detection step of detecting an error of the signal binarized in the binarization step and obtaining occurrence rate information of the error; A switching step of switching a waveform equalization characteristic of the waveform equalization step based on error occurrence rate information obtained in the error occurrence rate detection step. 35. The switching method according to claim 34, wherein the switching step controls a frequency-to-amplitude characteristic of the waveform equalization step with respect to the high-frequency modulation signal to change the waveform equalization characteristic. Data playback method. 36. The switching method according to claim 34, wherein the switching step controls a frequency-to-delay characteristic of the waveform equalization step with respect to the high-frequency modulation signal to change the waveform equalization characteristic. Data playback method. 37. The switching step controls both a frequency-to-amplitude characteristic and a frequency-to-delay characteristic of the waveform equalization step with respect to the high-frequency modulation signal to change the waveform equalization characteristic. 35. The data reproducing method according to claim 34, wherein: 38. The switching step, comprising: a first step of setting a frequency versus delay characteristic of the waveform equalization step to an intermediate characteristic in a variable range; and the first step comprises: With the delay characteristic set to the middle characteristic of the variable range, the frequency-amplitude characteristic in the waveform equalization step is changed to search for an amplitude characteristic that minimizes the error rate, and A second step of setting the frequency equalization step, and in the state where the frequency-to-amplitude characteristic of the waveform equalization step is set by the second step, the frequency-to-delay characteristic of the waveform equalization step is changed. 35. The data reproducing method according to claim 34, further comprising: a third step of retrieving a delay characteristic that minimizes an error occurrence rate and setting the same in the waveform equalizing step. 39. The switching step, wherein the frequency-to-amplitude characteristic in the waveform equalization step is adjusted so that the error occurrence rate falls within a range between a minimum value and a value higher than the minimum value by a predetermined amount. 35. The data reproducing method according to claim 34, wherein the setting is made as follows. 40. The switching step, wherein the frequency-to-delay characteristic in the waveform equalizing step is adjusted so that the error occurrence rate falls within a range between a minimum value and a value higher than the minimum value by a predetermined amount. 35. The data reproducing method according to claim 34, wherein the setting is made as follows. 41. The switching step, wherein the frequency-to-amplitude characteristic and the frequency-to-delay characteristic of the waveform equalizing step are set so that the error occurrence rate is between a minimum value and a value higher than the minimum value by a predetermined amount. 35. The data reproducing method according to claim 34, wherein the setting is made so as to fall within the range of.