JP3166846B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk having an information recording section composed of pits and a magneto-optical recording area, and a plurality of types of disks such as a read-only optical disk having a different recording format from the magneto-optical disk. The present invention relates to an optical disk reproducing apparatus capable of reproducing an image.

[0002]

2. Description of the Related Art Currently known optical disks include:
There are three types, such as a reproduction-only type, a write-once type, and a rewritable type.

For example, a CD (compact disc), which is one of the read-only optical discs, has digital audio data recorded on a transparent plastic disc by pit trains made by injection molding or the like, and the recording surface thereof. Is covered with a metal reflection film such as aluminum, and the surface is further covered with a protective film.

[0004] Reproduction data from the optical disk is detected by detecting the intensity of the amount of light reflected from the pit row by utilizing the light diffraction phenomenon.

On the other hand, in the magneto-optical recording area of a rewritable magneto-optical disc, for example, a magneto-optical recording film (perpendicular magnetization film) made of a material such as TbFeCo is formed on a disc made of a transparent plastic, and then formed thereon. Is covered with a protective film. In recording on this magneto-optical disk, a signal is recorded as the direction of magnetization by the magnetic field and the heat of the laser beam. Further, the detection of the reproduction signal is performed by utilizing a phenomenon (Kerr effect) in which, when a magneto-optical disk is irradiated with laser light, the plane of polarization rotates according to the direction of magnetization.

[0006] An information recording section is provided on the inner peripheral side of the magneto-optical recording area of the magneto-optical disk so that recording conditions and the like can be recorded in advance by a pit row formed by injection molding or the like. .

As described above, the recording format differs between the read-only optical disk and the rewritable magneto-optical disk.
The detection format of the reproduction signal is the same as that of irradiating the disk with the laser beam and detecting the reflected light, but there is a difference in the method of detecting the reproduction signal. Further, the light reflectance from the disk is about 1/5 that of the read-only optical disk when that of the read-only optical disk is 1, which is also different. For this reason, conventionally, an optical disk device is separately provided for each type of optical disk.

This relationship is the same between the information recording section composed of the pit row on the inner peripheral side of the magneto-optical disk and the magneto-optical recording area.

[0009]

However, in order to reproduce an optical disk capable of reproducing an optical signal similarly,
If a separate playback device must be used depending on the type of disc, the cost burden on the user increases, and the operation becomes troublesome.

Furthermore, it is very uneconomical to use separate optical heads for the information recording section of the inner pit row of the same magneto-optical disk and the magneto-optical recording area.
This leads to an increase in the size of the device.

In view of the above, the present invention provides a magneto-optical disk which can reproduce a plurality of different types of disks with the same optical disk device and has an information recording section composed of pits and a magneto-optical recording area. An object is to enable reproduction with one optical head.

[0012]

In order to solve the above-mentioned problems, an optical disk reproducing apparatus according to the present invention comprises: an information recording section comprising pits; a magneto-optical disk having a magneto-optical recording area; An optical disc reproducing apparatus for reproducing data from at least two types of optical discs of different types, comprising a light source, an objective lens for converging a light beam emitted from the light source on the optical disc, and entering through the objective lens An optical element for separating the light beam reflected by the optical disk into a plurality of light beams, first, second, third, and fourth light receiving units for receiving the plurality of light beams separated by the optical element; Fifth and sixth light receiving portions arranged to sandwich the first, second, third and fourth light receiving portions, and the first, second, third and third light receiving portions .
The seventh and eighth receivers are arranged with the fourth and fourth light receivers interposed therebetween.
An optical head comprising a light detector and a light portion, and the sum signal of the first output signal from the light receiving portion of said third output signal from the light receiving portion of the output from the second light receiving portion A focus error signal generating means for generating a focus error signal based on a signal obtained by taking a difference between a signal and a sum signal of output signals from the fourth light receiving unit;
Between the output signal of the third light receiving section and the output signal of the eighth light receiving section.
To generate a tracking error signal.
Tracking error signal generation means, identification means for identifying the type of loaded optical disc, and addition processing of the output signal from the fifth light receiving section and the output signal from the sixth light receiving section. A signal processing unit that generates a first signal and performs a subtraction process between an output signal from the fifth light receiving unit and an output signal from the sixth light receiving unit to generate a second signal. When the discriminating means identifies that the magneto-optical disc is loaded, the signal processing means determines whether the information recording section including the pits of the loaded magneto-optical disc is the first type.
Of reads by outputting a signal, the magneto-optical recording area of the loaded magneto-optical disk have rows read by outputting the second signal, the
The discrimination means differs from the magneto-optical disk in recording method.
If the disc is identified as loaded,
The signal processing means outputs the first signal,
It is switched to read, and
The racking error signal generation means is provided by the identification means.
An optical disk having a recording method different from that of the magneto-optical disk
Is loaded, or the magneto-optical
During the reproduction of the information recording section consisting of disk pits,
The polarity differs between when reproducing the magneto-optical recording area of the magnetic disk.
Output a tracking error signal .

In the optical disk apparatus of the first aspect, when the optical disk is loaded in the reproducing apparatus, the type of the loaded disk is identified by the identification means, and the signal processing means is operated by the identification output. And selectively outputs the first signal or the second signal according to the identified type of optical disc. At this time, a focus servo is applied to the optical head based on the error signal from the focus error signal generation means.

When the loaded disk is identified as a magneto-optical disk, the signal processing means performs reading by outputting a first signal for the information recording section composed of pits, and performs magneto-optical recording. Reading is performed for the area by outputting the second signal.

Accordingly, a plurality of different types of disks can be reproduced by the same optical disk device, and a magneto-optical disk having an information recording section composed of pits and a magneto-optical recording area can be reproduced by one optical head. Can be.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk reproducing apparatus according to the present invention will be described below with reference to the drawings.

The embodiment described below is a novel one which can reduce the size of a disk and the size of an optical disk device, and is suitable for a portable type and a vehicle type. .

The following description will be made in the following order. [1] Two types of optical disks [2] Recording / reproducing device [2-1] Recording system of recording / reproducing device [2-2] Reproducing system of recording / reproducing device [3] Modification.

[1] Two Kinds of Optical Disks In this example, a case where a read-only optical disk and a rewritable magneto-optical disk can be reproduced by one optical disk device (optical disk recording and / or reproducing device). To take.

The sizes of the two types of optical disks in this example are the same, and the specifications are as follows.

That is, as shown in FIG.
Has an outer diameter D of 64 mm, a central hole diameter d of 10 mm, and a signal recordable area W indicated by hatching is an area having a diameter of 32 mm or more. The thickness t of the disk 1 is 1.2 mm.

Then, recording tracks are formed on the disk 1 in a spiral shape at a pitch of 1.6 μm. The disk 1 is rotated at a constant linear speed of 1.2 to 1.4 m / s.

In this example, as will be described later, the recording information is compressed and recorded, so that the target information can be recorded and reproduced for 130 Mbytes or more. For example,
In the case of an audio signal, for example, when A / D conversion is performed on a 16-bit digital signal per sample at a sampling frequency of 44.1 kHz, the digital audio data is compressed to, for example, 1/4, thereby obtaining 2 bits.
The audio signals for the channels can be recorded and reproduced for 60 minutes or more.

In the case of this example, the disc 1 is composed of two or more different types of discs, ie, a read-only optical disc and a rewritable optical disc having a magneto-optical recording film and capable of recording, reproducing and erasing. Provide a magnetic disk.

A read-only optical disk has an information signal by a pit train formed by injection molding or the like on a transparent plastic disk. In this case,
A digital audio signal is recorded, a metal reflection film such as aluminum is coated on the surface of the recording surface, and the surface is further covered with a protective film.

On the other hand, in a rewritable magneto-optical disk, a magneto-optical recording film (perpendicular magnetic film) made of a material such as TbFeCo is formed on a disk made of a transparent plastic, and is covered with a protective film. Configuration.

In the case of a magneto-optical disk, as shown by a broken line in FIG. 2, a portion P of 30 to 32 mm on the inner peripheral side of the signal recording area W is formed by injection molding or the like as necessary. The recording conditions and the like can be recorded in advance by the pit train.

Further, a pre-groove for light spot control (for tracking control) is formed on the disk 1 in advance. In particular, in this example, the pre-groove is provided with a wobbling signal for tracking. An absolute time code is recorded in a superimposed manner (Japanese Patent Laid-Open No. 63-8 / 1988)
No. 7682).

In this case, in the pit recording portion P of the magneto-optical disk, the range of this portion P is recorded as the above absolute time, and the signal recording area W by magneto-optical recording and this portion are recorded. P is used for region identification.

The light reflectance of a read-only optical disk and that of the above-mentioned magneto-optical disk is about 0.2 for a magneto-optical disk, assuming that that of a read-only optical disk is one.

In the case of this example, the disk 1 is housed in a disk cartridge to prevent dust and prevent scratching.

FIG. 3 is a front view of a disk cartridge for a read-only optical disk, and FIG. 4 is a rear view thereof. In the figure, 2 indicates the cartridge as a whole,
3 is a shutter plate. In FIG. 4, when the shutter plate 3 moves in the direction indicated by the arrow A, the opening of the cartridge 2 is exposed, and the internal disk 1 is exposed to the outside. However, in the case of this reproduction-only type, FIG.
As shown in FIG.
There is no shutter opening, and the quadrilateral area 4 slightly smaller than the outer shape of the cartridge 2 is lower than its surroundings,
In this area 4, for example, a label or the like including a picture showing the recorded content or an explanation can be attached.

Reference numeral 5 denotes a shutter lock member, and reference numeral 6 denotes a shutter return spring, which is housed in the cartridge 2. When the cartridge 2 is inserted from the cartridge insertion port of the apparatus in the insertion direction shown in FIG. 3 is locked so that the opening of the cartridge 2 is exposed,
Further, it is used to close the shutter plate 3 again when the cartridge 2 is removed from the apparatus.

Reference numeral 7 denotes an opening for inserting a spindle of a disk rotation drive motor of the recording / reproducing apparatus, and 8 and 9 are concave holes into which positioning pins of the recording / reproducing apparatus are inserted when the cartridge 2 is inserted into the apparatus. It is.

FIG. 5 is a front view of a disk cartridge 12 for a rewritable magneto-optical disk, and FIG. 6 is a rear view thereof. In this case, the cartridge 12 has shutter openings on both front and back surfaces. Therefore, when the shutter plate 13 is moved in the direction of the arrow in FIG. 6, the discs 1 stored on both sides are exposed. This cartridge 12
In the case of (1), there is no area 4 to which a label like the cartridge 2 can be attached over almost the entire surface. Otherwise, the cartridge 2 is the same as the cartridge 2, 15 is a shutter lock member, 16 is a shutter return spring, 17 is a spindle insertion opening of a disk rotation drive motor of a recording or reproducing device, and 18 and 19 are positioning pins. It is a concave hole.

In the case of this example, the cartridges 2 and 12 have the same size, and as shown in FIGS. 3 and 5, the horizontal and vertical lengths a and b are a = 72 mm, b
= 68 mm and thickness 5 mm.

As shown in FIGS. 4 and 6, a concave hole (or protrusion) for discriminating whether the stored disk is a read-only type or a rewritable type is formed on the back side of the cartridges 2 and 12. 10a and 10b are provided. Also,
On the back surface of the disk cartridge 12, a hole 10E for preventing erroneous erasure is further provided. It is to be noted that, for the purpose of preventing the erroneous erasure, a type in which an erroneous erasure prevention claw used for a micro floppy disk or the like is slid may be used.

[2] Recording / Reproducing Apparatus Next, a description will be given of a recording / reproducing apparatus in which an embodiment of the optical disk reproducing apparatus according to the present invention is applied to its reproducing system. In this example, an example will be described in which a recording / reproducing apparatus that records, for example, an audio signal as an information signal on the disc 1 described above and reproduces the recorded audio signal.

FIG. 1 shows an embodiment of the recording / reproducing apparatus.
This example is devised so that the configuration can be simplified as much as possible by using an IC.

[2-1] Recording System of Recording / Reproducing Apparatus First, recording on a magneto-optical disk will be described. It should be noted that the system controller 20 is used during recording and during reproduction.
The mode of each circuit unit is switched by the mode switching signal R / P from. A key input operation unit (not shown) is connected to the system controller 20, and an operation mode is designated by an input operation on the key input operation unit. Further, the identification concave holes 10a,
By 10b, whether or not the disk inserted into the apparatus is a magneto-optical disk is identified, and the identification output is supplied to the system controller 20.

For example, an analog audio signal of two channels through the input terminal 21 is sampled by the A / D converter 22 at a sampling frequency of 44.1 kHz, and each sampled value is converted into a 16-bit digital signal. The 16-bit digital signal is supplied to the data compression / decompression processing circuit 23.

The data compression / decompression processing circuit 23 functions as a data compression circuit during recording, and in this case,
The input digital data is compressed to 1/4. Various data compression methods can be used,
For example, an ADPCM (Adaptive Delta) with a quantization number of 4 bits
Pulse Code Modulation) can be used. Further, for example, the input digital data is divided into a plurality of bands so that the higher the band, the wider the band is, and a plurality of samples (the number of samples is better to be the same in each band) for each divided band. It is also possible to use a method in which blocks are formed, orthogonal transform is performed for each block in each band, coefficient data is obtained, and bit allocation is performed for each block based on the coefficient data. In this case, the data compression method takes into account the characteristics of human perception of sound and can perform data compression with high efficiency (see Japanese Patent Application No. 1-278207).

Thus, the digital data DA (FIG. 7A) from the A / D converter 22 is compressed to 1/4 by the data compression processing in the circuit 23, and the data compressed da (FIG. 7B) is track jumped. The data is transferred to the buffer memory 25 controlled by the memory controller 24. In this example, a D-RAM having a capacity of 1 Mbit is used as the buffer memory 25.

The memory controller 24 sequentially reads out the compressed data da from the buffer memory 25 at a transfer speed four times the writing speed, unless a track jump occurs in which the recording position on the disk 1 jumps due to vibration or the like during recording. The read data is transferred to the data encoding / decoding circuit 26 (FIG. 7C).

When it is detected that a track jump has occurred during recording, the data transfer to the circuit 26 is stopped, and the compressed data da from the processing circuit 23 is stored in the buffer memory 25. Then, when the recording position is corrected, control is performed so that data transfer from the buffer memory 25 to the circuit 26 is restarted.

The detection of whether or not a track jump has occurred can be performed, for example, by providing a vibrometer in the apparatus and detecting whether or not the magnitude of the vibration is such that a track jump occurs. Further, as described above, the absolute time code is recorded on the disk 1 of this example so as to be superimposed on the wobbling signal for tracking control when the pregroove is formed. Therefore, it is possible to read the absolute time code from the pre-groove at the time of recording and detect a track jump from the decoded output. Alternatively, a track jump may be detected by ORing the absolute time code with the vibrometer.
When a track jump occurs, the power of the laser beam for magneto-optical recording is reduced or the power is set to zero.

The correction of the recording position when a track jump occurs can be performed using the absolute time code.

As understood from the above, the data capacity of the buffer memory 25 in this case is as follows.
At least, a capacity capable of storing the compressed data da corresponding to the time from the occurrence of the track jump to the time when the recording position is correctly corrected is required. In this example, the capacity of the buffer memory 25 has 1M bits as described above, and this capacity is selected as having a sufficient margin to sufficiently satisfy the above-mentioned conditions.

In this case, the memory controller 24
Performs a memory control so that the data stored in the buffer memory 25 is reduced as much as possible during normal operation during recording. For example, when the data amount of the buffer memory 25 is equal to or more than a predetermined amount, the memory control is performed such that a predetermined amount of data is read from the buffer memory 25 and a write space equal to or larger than the predetermined amount of data is always secured. Do.

The data encoding / decoding circuit 26
At the time of recording, it works as an encoding circuit and the buffer memory 2
5 is encoded into data having a sector structure (about 2 Kbytes) of the CD-ROM.

This data encoding / decoding circuit 26
Is supplied to the recording encoding circuit 27.
The recording encoding circuit 27 performs encoding processing for error detection and correction on data, in this example, CIRC encoding processing, and performs modulation processing suitable for recording, in this example, EF
An M encoding process or the like is performed.

The encoded data from the recording encoding circuit 27 is supplied to a magnetic head 29 via a magnetic head driving circuit 28. The magnetic head drive circuit 28 drives the magnetic head so as to apply a modulation magnetic field according to the recording data to the disk 1 (magneto-optical disk). The recorded data on the disk 1 is as shown in FIG. 7D.

In this case, the magneto-optical disk 1 is housed in the cartridge 12, but when loaded in the apparatus, the shutter plate 15 is opened, and the disk 1 is exposed from the shutter opening. The rotation shaft of the disk drive motor 30M is inserted and connected to the spindle hole 15, and the disk 1 is driven to rotate at a linear speed of 1.2 to 1.4. The disk drive motor 30M is controlled at a constant linear velocity by a servo control circuit 32 described later.

The magnetic head 29 is mounted on the cartridge 12
The disk 1 is exposed from the shutter opening of the disk 1. An optical head 30 is provided at a position facing the surface of the disk 1 opposite to the surface facing the magnetic head. During recording, the optical head 30 irradiates a recording track with laser light having a constant power larger than that during reproduction. This light irradiation and the magnetic head 2
The data is recorded on the disk 1 by the thermomagnetic recording due to the modulation magnetic field 9.

Both the magnetic head 29 and the optical head 30 are configured to be able to move along the radial direction of the disk 1.

At the time of this recording, the optical head 3
The output of 0 is supplied to the absolute time decoding circuit 34 via the RF circuit 31, and the absolute time code from the pregroove of the disk is extracted and decoded. Then, the decoded absolute time information is supplied to the recording encoding circuit 27, inserted into the recording data as the absolute time information, and recorded on the disk. The absolute time information from the absolute time decoding circuit 34 is also supplied to the system controller 20 and used for recognition of the recording position and position control as described above.

[2-2] Reproducing System of Recording / Reproducing Apparatus The apparatus of this example is capable of reproducing two types of discs, a read-only optical disc and a rewritable magneto-optical disc. As described above, the two types of disks can be identified by detecting the identification concave holes 10a and 10b provided in the disk cartridges 2 and 12, respectively. For example, in the disk cartridge 2 for a read-only disk, only the concave hole 10a is formed out of the two concave holes 10a and 10b for identification, and in the disk cartridge 12 for the magneto-optical disk, two Concave holes 10a, 10b
To form both. As a result, the cartridge 2
Or 12 is loaded, the identification recesses 10a,
By detecting the number of 10b, it is possible to identify which cartridge.

Since the light reflectivity of the read-only disc and the rewritable disc is different from 1: 0.2 as described above, it is possible to discriminate the two discs from the output of the optical head 30. it can. In the reproducing system of the example of FIG. 1, as will be described later, a disc identification circuit 40 for discriminating two types of discs from the difference in light reflectance is provided.

The disk loaded in the recording / reproducing apparatus is driven to rotate by a disk drive motor 30M. Then, in the same manner as during recording, this disk drive motor 30
The rotation speed M is controlled by the servo control circuit 32 so that the disk 1 is kept at a constant linear velocity of 1.2 to 1.4 m / s.

At the time of reproduction, the optical head 30 detects a focus error by, for example, an astigmatism method by detecting reflected light of a laser beam applied to a target track, and detects a tracking error by, for example, a push-pull method. At the same time, in the case of a read-only optical disk, a reproduced signal is detected by utilizing the diffraction phenomenon of light in a pit row of a target track, and in the case of a rewritable magneto-optical disk, reflected light from the target track is detected. The reproduction signal is detected by detecting the difference in the polarization angle (Kerr rotation angle).

FIG. 8 shows an embodiment of the structure of the optical head 30. In FIG. 8, a laser beam from a semiconductor laser 301 is converted into a parallel beam by a collimator lens 302 and is divided into three beams by a diffraction grating 303.
The light enters the polarization beam splitter 304. Then, the three laser beams whose optical axis directions have been changed by the polarization beam splitter 304 are
5 and converges on the disk 1.

A part of the laser beam incident on the beam splitter 304 is changed in the optical axis direction and is incident on a photodetector 306. The photodetector 306 responds to the emission power of the semiconductor laser 301. The received light amount is detected. The light reception output of the photodetector 306 is supplied to a power control circuit 311. The power control circuit 311 controls the semiconductor laser 30 based on the amount of received light.
Control is performed so that the light emission power of No. 1 becomes a predetermined value.

The laser beams (three) reflected by the disk 1 enter the polarization beam splitter 304 via the objective lens 305, change the optical axis direction, and enter the Wollaston prism 307. In the Wollaston prism 307, the incident light is separated into orthogonal polarization components, that is, a P-polarization component and an S-polarization component, and the P-polarization component is set to the first beam direction (P) in FIG. The S-polarized component is in the lower second beam direction (S).

The Wollaston prism 307
From above, a composite component of the P-polarized component and the S-polarized component is obtained in the direction intermediate between the first and second beam directions, having the same optical axis direction as the incident reflected laser beam. In this case, in FIG. 8, the Wollaston prism 307
The three laser beams incident on the laser beam are arranged in a direction perpendicular to the plane of the paper, and are separated into a P-polarized component, an S-polarized component, and a composite component thereof as described above, so that a total of nine beams are formed. Will be obtained.

The reflected laser beams in the first beam direction (P) and the second beam direction (S) enter the light detection unit 50 through the condenser lens 308, and
The reflected laser beam in the third beam direction is
08 and through the cylindrical lens 309.

The light detecting unit 50 is composed of a plurality of light detecting elements. In this example, as shown in FIG. 9, the light detecting element 50 includes four light detecting elements 50A, 50B, 50C and 50D at the center. A group 51 is provided, a light detecting element 50E and a light detecting element 50F are provided at left and right positions of the light detecting element group 51, and a light detecting element 50I is provided at a position above and below the light detecting element group 51. And a light detection element 50J.

The three laser beams in the third beam direction among the reflected laser beams incident on the light detection unit 50 are incident on the light detection elements 50E and 50F and the light detection element group 51. The reflected laser beam at the center of the three beams in the first beam direction, that is, the P-polarized component is
The reflected laser beam at the center of the three beams in the second beam direction that is incident on the photodetector 50I, that is, the S-polarized component, is incident on the photodetector 50J. Then, the detection output of each of the light detection elements 50A to 50J, which is the output of the optical head 30, is supplied to the RF circuit 31.

The RF circuit 31 compares the detection output of the P-polarized component by the photodetector 50I with the output of the S-polarized component detected by the photodetector 50J to reflect the reflected light on the perpendicular magnetization film of the magneto-optical disk. The rotation of the polarization plane received by the laser beam is detected, and a read information signal _DRF is formed by the comparison output having a change corresponding to the rotation of the polarization plane. Then, reproduction data is generated from the information signal _DRF .

When reproducing from a read-only optical disk, the reproduction data is generated by using the diffraction phenomenon of the laser beam as the intensity of the light detection amount. In this example,
The read information signal _DRF is formed from the sum of the detection output of the P polarization component by the photodetector 50I and the detection output of the S polarization component by the photodetector 50J.

Therefore, in the RF circuit 31, the signal processing circuit is switched using the discrimination output of the disc, and in the case of a magneto-optical disc, the difference (comparative output) between the P-polarized component and the S-polarized component is obtained, and the read-only type is obtained. when the disc by to obtain the sum of the P and S polarization components, to form a read information signal D _RF from both the optical disk and read-only type disc, the data can be reproduced Become.

The RF circuit 31 also obtains the change in the reflected laser beam from the wobbling track for tracking servo provided on the disk in the light detecting elements 50E and 50F of the light detecting unit 50. And a tracking error signal is formed by using the photodetection output of 50F. Further, the light detection element group 5
The shape of the beam spot on the first light detecting element 50A
By detecting using a detection output of ~ 50D, a focus error signal of the laser beam incident on the disk is formed.

In the RF circuit 31, the RF gain of the read information signal forming circuit system is switched in consideration of the difference in light reflectance between the read-only disk and the magneto-optical disk, and each servo error signal forming circuit is switched. The RF gain of the system is switched.

FIG. 10 shows an embodiment of the circuit configuration of the RF circuit 31.

That is, the light detection outputs LI and LJ of the light detection elements 50I and 50J of the light detection unit 50 are:
The signals are amplified by operational amplifiers 101 and 102, respectively. The output of the sum of the outputs of these operational amplifiers 101 and 102 is obtained from the operational amplifier 103, the output of the sum is supplied to one input terminal P of the switch circuits SW _1. The output of the operational amplifier 101 and the operational amplifier 102
Is input to the differential amplifier 104, and the output of the operational amplifier 101 and the output of the operational amplifier
The output of the difference between the second output is obtained, the output of the difference is supplied to the other input terminal M of the switch circuits SW _1.

The switch circuit SW ₁ responds to a switching signal from the system controller 20 which is formed from an identification output of the disk identification circuit 40, which will be described later, during playback from the read-only disk and playback from the magneto-optical disk. At the time of reproduction from a recording portion by pits from the portion P of the disk 1, the input terminal P is switched to one input terminal P side, and the output of the sum of the photodetection outputs LI and LJ is output signal D.
_RF at the output terminal 105, and when reproducing from the magneto-optical recording area W of the magneto-optical disk, the other input terminal M
Is switched to the side, the output of the difference of the photodetection output LI and LJ is obtained at the output terminal 105 as the output signal D _RF.

Further, the operational amplifier 103 is provided with a switch circuit SG ₁ for switching the gain. When a reproduction-only disc is reproduced, the switch circuit SG ₁ is turned on by a switching signal from the system controller 20 to turn on the gain. Is turned to GA, and during reproduction of the portion P of the magneto-optical disk, this is turned off and the gain is set to about 5GA. Note that the gain of the differential amplifier 104 is about 30 GA.

The light detection outputs LE and LF of the light detection elements 50E and 50F are connected to the operational amplifiers 106 and 1 respectively.
After being amplified by 07, they are supplied to one and the other input terminals of a differential amplifier 108, respectively, from which an output of the difference between the light detection outputs LE and LF is obtained. The output of the differential amplifier 108 are those corresponding to the tracking deviation amount, the output of this difference is supplied to one input terminal I of the switch circuit SW _2, the switch circuit SW ₂ through an inverting amplifier 109 It is supplied to the other input terminal N.

The switch circuit SW ₂ is operated by a switching signal from the system controller 20 at the time of reproduction from the read-only disk and at the time of reproduction from the magneto-optical disk. At the time of reproduction, it is switched to the other input terminal N side, and at the time of reproduction from the magneto-optical recording area W of the magneto-optical disk, it is switched to one input terminal I side.

This switching is performed at the time of reproduction from a read-only disk and at the time of reproduction from a magneto-optical disk. At the time of reproduction from a recorded portion by pits from the portion P, the tracking servo uses the three-spot method. This is because the push-pull method is used at the time of reproduction from the magneto-optical recording area W of the magneto-optical disk, and it is necessary to change the polarity of the tracking error signal by both tracking servo methods.

The output of the switch circuit SW ₂ is amplified by the operational amplifier 110, and the output is output to the output terminal 11.
Obtained as a tracking error signal Te to 1, but the gain is switched by the switch circuit SG _2.
That is, the switching signal from the system controller 20, read-only type when reproducing the disc, the switch circuit SG ₂ is being turned on, the gain is set to the GT, also when the optical disk reproduction, the switching circuit SG ₂ Is turned off, and the gain is set to 5GT.

After the sum of the light detection output LA of the light detection element 50A of the light detection element group 51 of the light detection unit 50 and the light detection output LC of the light detection element 50C is amplified by the operational amplifier 112, the differential amplifier 114, and the sum of the light detection output LB of the light detection element 50B and the light detection output LD of the light detection element 50D is supplied to the operational amplifier 113.
After that, the signal is supplied to the other input terminal of the differential amplifier 114, and the output of the difference between the signals supplied to the two input terminals according to the focus error amount is obtained from the differential amplifier 114.

The output of the differential amplifier 114 corresponds to the focus error amount. The output of the differential amplifier is amplified by the operational amplifier 115, and the output is obtained at the output terminal 116 as the focus error signal Fe.
Its gain is switched by the switch circuit SG _3. That is, the switching signal from the system controller 20, upon reproduction of the read-only type disc, the switch circuit SG ₃ is being turned on, the gain is the GF, also,
When the optical disk reproduction, the switch circuit SG ₃ is turned off, the gain is set to 5 gf.

The tracking error signal Te obtained at the output terminal 111 of the RF circuit 31 and the output terminal 1
The focus error signal Fe obtained at 16 is supplied to the servo control circuit 32.

The servo control circuit 32 controls the focus of the optical system of the optical head 30 so that the focus error signal Fe becomes zero, and controls the optical system of the optical head 30 so that the tracking error signal Te becomes zero. Performs tracking control of the system.

Although not shown, a part of the signal for detecting the tracking error Te of the RF circuit 31 is supplied to the absolute time decoding circuit 34 for extracting the absolute time code from the pre-probe. Then, the absolute time information from the decoding circuit 34 is supplied to the system controller 20 and used for the reproduction position control as needed. The system controller 20 can also use the address information in sector units extracted from the reproduction data to manage the position on the recording track where the optical head 30 is scanning.

The discrimination between the two types of optical discs and the discrimination between the recording area W and the portion P of the magneto-optical disc are performed as follows in this case.

That is, the operational amplifier 10 of the RF circuit 31
The outputs X and Y of 1 and 102 are proportional to the laser beam reflected from the optical disk, and are proportional to the reflectivity of the optical disk. Therefore, the outputs X and Y
Is input to the disc identification circuit 40.

FIG. 11 shows an embodiment of the disc identification circuit 40. The signal of the sum of the output X and the output Y is amplified by the operational amplifier 41, and then the first and second comparison circuits 42 and 45. Then, the first comparison circuit 42 and compared with the first threshold value VT ₁ by the DC power supply 43, also in the second comparison circuit 45, the second threshold value VT by the DC power source 46
Compared to ₂ .

In this case, the light reflectance of the read-only disc is high, and the output of the operational amplifier 41 during the reproduction is large as shown by the solid line 61 in FIG. On the other hand, the light reflectance of the magneto-optical disk is about 1/5 that of the read-only type, and the output of the operational amplifier 41 during the reproduction is small as shown by the solid line 62 in FIG. Therefore, the first and second threshold values VT ₁ and VT _2, in this example, as shown in FIG. 12, are selected to VT ₁ <VT _2.

In this way, if the disc loaded in the apparatus is of a read-only type, the output of the comparison circuit 42 is "1" and the output of the comparison circuit 45 is "0". , The output of the comparison circuit 42 becomes “1”, and the output of the comparison circuit 45 also becomes “1”. The outputs of the comparison circuits 42 and 45 are supplied to the system controller 20 via output terminals 44 and 47, respectively. And
In the system controller 20, when the output signal of the output terminal 44 is "1" and the output signal of the output terminal 47 is "0", the disc loaded in the apparatus is identified as a read-only disc, and When the output signal is "1" and the output signal of the output terminal 47 is "1", the disc loaded in the apparatus is identified as a magneto-optical disc.

Further, based on the decoded output of the data from the portion P of the magneto-optical disk, the system controller 20 detects the absolute time indicating the area of the portion P. Then, the part P and the signal recording area W are identified from the absolute time from the absolute time decoding circuit 34.

Then, the system controller 20 forms the above-mentioned switching signals of the respective switch circuits SW ₁ , SW ₂ , SG _{1 to} SG ₃ based on the two identification outputs.

Next, the read information signal D _RF obtained at the output terminal 105 of the RF circuit 31 is waveform-shaped and binarized, and then supplied to the reproduction encoding circuit 33.

The reproduction decoding circuit 33 receives the binary reproduction signal from the RF circuit 31 and
, Ie, a decoding process for error detection and correction, an EFM decoding process, and the like. The output data of the reproduction decoding circuit 33 is supplied to the data encoding / decoding circuit 26.

This data encoding / decoding circuit 26
Operates as a decoding circuit at the time of reproduction, and decodes data having a sector structure of a CD-ROM into compressed original data.

The data encoding / decoding circuit 26 receives the disc identification data from the system controller 20 and, when reproducing a magneto-optical disc, detects a portion where a track jump has occurred during recording, and detects the jump. The joint processing of the data in the track jump portion is performed as needed. The detection of the track jump position can be performed, for example, by inserting information indicating the fact into the recording data.

This data encoding / decoding circuit 26
Is transferred to a buffer memory 25 controlled by a track jump memory controller 24.
Writing is performed at a predetermined writing speed.

At the time of this reproduction, the memory controller 24 transmits the compressed data from the data encoding / decoding circuit 26 unless a track jump at which the reproduction position jumps due to vibration or the like occurs during the reproduction. A data compression / expansion processing circuit 2 sequentially reads data at a transfer rate of 1/4 times the writing speed and reads the read data.
Transfer to 3.

When it is detected that a track jump has occurred during reproduction, the writing of data from the circuit 26 to the buffer memory 25 is stopped, and only the transfer of data to the data compression / decompression processing circuit 23 is performed. Do. Then, when the reproduction position is corrected, control is performed to restart writing data from the circuit 26 to the buffer memory 25.

The detection of whether or not a track jump has occurred is performed by, for example, a method using a vibrometer and an absolute time code which is recorded on a pregroove of an optical disk by superimposing it on a wobbling signal for tracking control. The method used (that is, the method using the decoded output of the absolute time decoding circuit 34) or the method of detecting the track jump by taking the OR of the vibrometer and the absolute time code can be used. Furthermore, during this playback,
As described above, since the absolute time information and the address information in sector units are extracted from the reproduced data, they can be used.

As described above, the track position control such as the correction of the reproduction position when a track jump occurs can use the address information in addition to the above-described absolute time code.

As will be understood from the above, the data capacity of the buffer memory 25 at the time of this reproduction corresponds to the time from the occurrence of a track jump to the correct correction of the reproduction position. A minimum capacity that can always store data is required. This is because, with such a capacity, data can be continuously transferred from the buffer memory 25 to the data compression / decompression circuit 23 even if a track jump occurs. In this example, 1 Mbit as the capacity of the buffer memory 25 is selected as a sufficient capacity so as to sufficiently satisfy the above condition.

In this case, the memory controller 24
In this reproduction, during normal operation, memory control is performed so that predetermined data equal to or more than the necessary minimum is accumulated in the buffer memory 25 as much as possible. For example, when the amount of data in the buffer memory 25 becomes equal to or less than a predetermined amount, data is written from the circuit 26, and memory control is performed so that a read space equal to or more than the predetermined amount of data is always secured.

The data compression / decompression processing circuit 23 functions as a data decompression circuit during reproduction, and converts ADPCM data into
A reverse conversion process is performed with respect to the data compression process at the time of recording, and the data is expanded four times.

The digital audio data from the data compression / decompression circuit 23 is supplied to a D / A converter 35, returned to a two-channel analog audio signal, and output from an output terminal 36.

In this example, the digital audio data before the D / A conversion can be directly output from the output terminal 37.

The disk of the embodiment described above has a capacity of 80
It is very small with an outer diameter of less than mm, which is very useful for miniaturizing a recording and reproducing apparatus.
Moreover, since the data is compressed and recorded on this small disk, it is possible to record and reproduce, for example, an audio signal for 60 minutes or more, and furthermore, the recording capacity is reduced by downsizing the disk. It does not lower.

Also, in this embodiment, a buffer memory is provided between the data compression means and the recording encoding means in the recording system, and between the reproduction decoding means and the data decompression means in the reproduction system. By setting the capacity to a predetermined value, during recording and reproduction, even if a track jump occurs and the recording position or reproduction position jumps, recording is continuously performed without causing discontinuity of the recording signal on the disc. The reproduction signal can be reproduced without generating unnatural breaks or noise.

As described above, in this embodiment, since the countermeasures against the track jump are taken by the signal processing, it is not necessary to use the anti-vibration structure for the countermeasures against the vibration, and the recording apparatus and the reproducing apparatus can be downsized. Greatly contribute to. Also, by using a vibration isolating structure for vibration countermeasures together, stronger vibration countermeasures can be taken, but even in this case, the vibration isolating structure is relatively simple and small in scale. Since such a device can be used, the recording device and the reproducing device can be downsized.

Therefore, if the recording / reproducing apparatus of this embodiment is applied to a portable or in-vehicle type disc recording and / or reproducing apparatus, the effect is remarkable.

[3] Modifications The present invention is also applicable to a case where the optical disk to which the present invention is applied is not limited to two types of optical disks, but to three or more types of optical disks.

The recording information is not limited to the audio signal alone, but may record a video signal, a character or graphic pattern signal or a code conversion signal, map information, and other various data.

The disc identification means may use an identification mark formed on the disc cartridge. The identification mark is not limited to the recessed hole or the protrusion as shown in the embodiment of the drawing. For example, an identification barcode or the like may be provided at any position of the cartridge or the label attached thereto.

Further, in the above example, the portion to be switched in accordance with the disc identification output is the gain and the signal processing circuit in the RF circuit 31. When it is necessary to switch the signal processing circuit of the subsequent circuit, it is needless to say that that part is also switched according to the disc identification output.

[0115]

As described above, according to the present invention, in an optical disk reproducing apparatus for reproducing a plurality of types of optical disks having different recording systems, the optical disk can be used without using a plurality of optical heads corresponding to the type of the optical disk. Can be reproduced in accordance with the type of the optical disc, and the information recording section composed of the pits of the magneto-optical disk and the magneto-optical recording area can be reproduced by one optical head.

Since the circuit configuration subsequent to the RF circuit can be common to a plurality of types of optical disks, the configuration as an optical disk device is different from that in a case where a plurality of different types of optical disk devices are combined. Also, the configuration can be greatly simplified and the configuration can be made inexpensively.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a recording and reproducing apparatus to which an embodiment of a disk reproducing apparatus according to the present invention is applied.

FIG. 2 is a diagram for explaining an example of an optical disc to be reproduced.

FIG. 3 is a diagram showing an example of a disk cartridge for storing an optical disk to be reproduced.

FIG. 4 is a diagram showing an example of a disk cartridge for storing an optical disk to be reproduced.

FIG. 5 is a diagram showing an example of a disk cartridge for storing an optical disk to be reproduced.

FIG. 6 is a diagram showing an example of a disk cartridge for storing an optical disk to be reproduced.

FIG. 7 is a time chart for explaining a recording system.

FIG. 8 is a configuration diagram of an example of an optical head 30.

FIG. 9 is a diagram showing an example of the light detection unit.

FIG. 10 is a circuit diagram of an example of an RF circuit.

FIG. 11 is a circuit diagram of an example of a disc identification circuit.

FIG. 12 is a diagram showing the output of the optical head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Disk, 2; Read-only optical disk cartridge, 12; Magneto-optical disk cartridge, 10a, 1
0b; concave hole for disc identification, 20; system controller, 23; data compression / decompression processing circuit, 30; optical head, 31; RF circuit, 33; reproduction decoding circuit, 40;
Disc identification circuit, SW ₁ , SW ₂ ; switch circuit for switching signal processing circuit, SG ₁ , SG ₂ , SG ₃ ; switch circuit for switching RF gain

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G11B 11/105 556 G11B 11/105 556C 576 576A 581 581C ) Surveyed field (Int.Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/09-7/095 G11B 11/105

Claims (2)

(57) [Claims] 1. An optical disc reproducing apparatus for reproducing information from at least two types of optical discs having different recording systems, comprising: an information recording section comprising pits; a magneto-optical disc having a magneto-optical recording area; A light source, an objective lens for focusing a light beam emitted from the light source on an optical disk, and an optical element for separating the light beam reflected by the optical disk incident through the objective lens into a plurality of light beams; A first, a second, a third, and a fourth light receiving unit for receiving a plurality of light beams separated by the optical element, and the first, second, third, and fourth light receiving units are disposed therebetween. Fifth and sixth light receiving units, and the first, second, third and fourth light receiving units
An optical head including a light detection unit having seventh and eighth light receiving units disposed in the following manner: a sum signal of an output signal from the first light receiving unit and an output signal from the third light receiving unit; , the second based on a signal taken the difference between the sum signal of the output signal from the output signal and the fourth light receiving portion of the light receiving portion, a focus error signal generating means for generating a focus error signal, the The output signal from the seventh light receiving unit and the output signal from the eighth light receiving unit
Tracking by taking the difference from the output signal
Tracking error signal generating means for generating an error signal
An identification means for identifying the type of the loaded optical disc; and a first signal generated by performing an addition process on an output signal from the fifth light receiving section and an output signal from the sixth light receiving section. And a signal processing unit that generates a second signal by performing a subtraction process between an output signal from the fifth light receiving unit and an output signal from the sixth light receiving unit. When it is determined that the magneto-optical disk has been loaded, the signal processing means performs reading by outputting the first signal with respect to the information recording section composed of pits of the loaded magneto-optical disk, the magneto-optical recording area of the magneto-optical disk that is had rows read by outputting the second signal, and the magneto-optical disc by said identification means
If a disc with a different recording format is identified as loaded
The signal processing means outputs the first signal.
Is switched to read by
In both cases, the tracking error signal generating means includes the identifying means.
Optical data with a different recording method from the magneto-optical disk
Disc is identified as loaded, or
At the time of reproduction of the information recording section consisting of pits on the magnetic disk,
Polarity when reproducing the magneto-optical recording area of the magneto-optical disk
An optical disc reproducing apparatus which outputs different tracking error signals . 2. The tracking error signal generating means,
An output signal from the seventh light receiving unit and an eighth light receiving unit
A subtraction circuit for taking a difference from an output signal from the
And an inverting circuit for inverting the polarity of the output signal from the road.
When reproducing the magneto-optical recording area of the magneto-optical disk,
The output signal from the subtraction circuit is a tracking error signal.
And output by the identification means.
Discriminated that an optical disc with a different recording method has been loaded
Or from the pits of the magneto-optical disk
When the information recording section is reproduced, the output from the inverting circuit section is output.
2. The optical disc reproducing apparatus according to claim 1, wherein the force signal is output as a tracking error signal .