JPH09293321A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the kinds of a plurality of kinds of disks having surface vibrating components accurately, simply and quickly. SOLUTION: Driving signal levels transmitted to object lenses 20 at the time of focussing operation to the recording surfaces 1a of disks 1 are detected, and the height of the recording surfaces 1a of the disks 1 are detected by sensing the focussing places of the object lenses 20 from the driving signal levels and the kinds of the disks 1 are discriminated. The disks 1 are brought to a rotary state in the vicinity of the innermost circumferences of the disks 1 for minimizing the effects of the surface vibrations of the disks 1 at that time, and the kind of the disk is discriminated by using a mean level over for one revolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for optically reproducing or recording / reproducing a signal from a disk, and more particularly to reproducing or recording / reproducing two or more kinds of disks having different disk formats and signal recording formats. The present invention relates to an optical disk device that can be used.

[0002]

2. Description of the Related Art At present, compact disk (hereinafter, referred to as CD) players and laser disk (hereinafter, referred to as LD) players, which are widely used for music reproduction, are used as optical disk devices. Although these devices differ in the outer diameter size and thickness of the disc and the recording signal format, the height of the recording surface is 1.2 mm from the disc surface.
The same applies to both, and since the optical system can be used in common, a device that can reproduce a CD and an LD with one device has been commercialized.

[0003]

However, recently, a digital video disc (hereinafter referred to as DV) capable of recording not only audio but also video information by increasing the recording density of the disc has been recently used.
The basic standard for high-density recording disks such as D) has been decided. This DVD has the same outer size as the CD but has a track pitch of 1.6 μm to 0.74 μm.
The laser wavelength becomes 780 nm to 650 nm.
nm or 635 nm, and the numerical aperture (NA) of the lens increases from 0.45 to 0.60. In order to alleviate the adverse effect that the permissible value of the angle (tilt angle) at which the disc surface deviates from the vertical with respect to the optical axis of the optical pickup due to the increase in the density and the increase in the numerical aperture (NA) becomes smaller, Although the outer size is the same as the DVD, the height of the recording surface is 1.2mm (single plate) of CD
Is 0.6 mm (thickness of 1.2 mm when two pieces are stuck together). Therefore, although DVDs and CDs are discs of seemingly the same size, discs of different standards exist. Naturally, in a DVD compatible optical disc device to be commercialized later, not only DVDs but also CDs It is also required that the playback operation can be performed correspondingly.

However, since the standard is different between CD and DVD, in order to reproduce each disc, it is necessary to switch to the signal reading and signal processing means suitable for each disc, and which disc is mounted when the disc is mounted. It became necessary to determine what. And C
There has been a demand for an optical disk device that can quickly discriminate between D and DVD disks and switch to signal reading and signal processing means according to the mounted disks.

On the other hand, by the same application as the invention of the present application, Japanese Patent Application No. 08-002446 proposes a disk discriminating technique which realizes the above-mentioned requirements. With this technology, the distance from the disk surface to the signal recording surface (light reflecting surface) is 0.6 mm for DVD while 1.2 mm for CD.
By paying attention to the fact that the distance is m, and directly or indirectly detecting this distance, the discrimination between the CD disk and the DVD disk is realized. However, the existing proposal did not mention the influence of surface wobbling of the disc.

[0006] The present invention has been made in view of the above points,
The purpose is to discriminate between a new high-density disc such as a DVD and a conventional CD disc, which disc is mounted at the time of disc mounting with higher reliability as compared with the proposed discrimination technology, It is to realize a convenient optical disc device that can perform signal reading or signal processing corresponding to the determination result or switching to signal processing means to perform reproduction or recording / reproduction.

[0007]

To achieve the above object, the present invention is constituted by the following means.

In an optical disk device for optically reproducing or recording / reproducing a disk, an objective lens for focusing a laser beam on a recording surface of the disk and an objective lens by moving the objective lens in a direction substantially perpendicular to the disk surface. First moving means for adjusting the focus of the lens to the recording surface of the disc, second moving means for moving the focus of the objective lens in the radial direction of the disc, and the objective lens moved by the first moving means. A moving amount detecting means for detecting the moving amount of the recording surface, and the height of the recording surface from the disc surface is different.
For discs of more than one type, when the disc is mounted, the objective lens is moved to the vicinity of the innermost circumference of the disc by the second moving means, and the objective lens is moved to the first objective lens by the first moving means at the time of focusing operation. The position of the recording surface of the disc is detected by detecting the amount of movement in the direction 1 by the moving amount detecting means, and two or more types of discs having different recording surface heights are discriminated.

With this configuration, the position of the recording surface of the disk is correctly detected even for a disk whose disk surface is not uniform in the radial direction, and two or more kinds of disks having different recording surface heights are discriminated. It improves the reliability of.

In an optical disk device for optically reproducing or recording / reproducing a disk, an objective lens for focusing a laser beam on the recording surface of the disk and the objective lens are moved in a direction substantially perpendicular to the disk surface. Moving means, rotating means for rotating the disk, focus control means for adjusting the focus of the objective lens to the recording surface of the disk by controlling the moving amount of the moving means, and movement of the objective lens moved by the moving means. A disc is provided for two or more types of discs having different heights from the disc surface to the recording surface, the disc having a movement amount detection means for detecting the amount and a correction means for correcting the movement amount detected by the movement amount detection means. When mounted, the disc is rotated by the rotating means and the focus of the objective lens is changed by the focus control means. Along with the match on the recording surface of the click,
The amount of movement of the objective lens by the moving means during the focusing operation is detected by the moving amount detecting means, and the change amount due to the rotation of the disk is corrected by the correcting means from the detected moving amount, and the corrected objective is corrected. The height of the recording surface is different by detecting the position of the recording surface of the disc from the amount of movement of the lens.
The configuration is such that the disc types of more than one type are discriminated.

With this configuration, the position of the recording surface of the disk can be accurately detected even for a disk whose surface is not uniform in the circumferential direction, and two or more kinds of disks having different recording surface heights can be detected. This improves the reliability of discrimination.

The moving means is an electric moving means, and the moving amount detecting means detects a driving voltage or a driving current applied to the moving means of the objective lens. The disc is discriminated by detecting the difference in the height of the recording surface of the disc using the relationship with the movement amount.

This is a signal generated by the focus control system, which is indispensable for the optical disk device, since it is not necessary to newly provide a sensor or the like for detecting the amount of movement of the objective lens, so that the amount of movement can be easily detected. Not only can the cost of the device be reduced.

The relationship between the drive voltage or drive current and the amount of movement of the objective lens is variable according to the correction information stored in the storage means.

This is because the relationship between the drive voltage or drive current and the amount of movement of the objective lens varies even when there are variations in the precision of the mechanical attachment of the objective lens or the electrical offset of the drive voltage or drive current. By discriminating the type of the disk with high reliability, the total correction information is collectively stored in the storage means and corrected without individually optimizing and adjusting them.

Further, focus detection means for detecting that the focus of the objective lens matches the recording surface from the signal read from the recording surface of the disk is provided, and the focus of the objective lens is read in order to read the contents of the disk when the disk is mounted. When performing the matching operation by the first moving means, the movement amount of the objective lens is detected by the movement amount detecting means, and the focus detecting means detects that the objective lens is in focus, thereby discriminating the kind of the disc. It is configured to perform.

This is because a signal generated by a focus control system, which is indispensable for an optical disk device, is used to detect whether or not the focus of the objective lens is aligned with the recording surface of the disk. Cost reduction can be achieved.

Further, in an optical disc device which optically reproduces or records and reproduces digital information corresponding to plural kinds of discs, plural kinds of signal detecting means for optically detecting signals from the disc and the signal detecting means Control means for performing focus control and tracking control at the time of signal detection, signal conversion means for converting the signal detected by the signal detection means into a digital signal, and a plurality of digital signal forms of the converted digital signal A plurality of decoding means for performing a decoding process having at least an error detection function, and a selection means for selecting one from the plurality of signal detection means and the plurality of decoding means according to a mode control signal, and the selected decoding Mode of the mode control signal generating means using the error detection information of the means It was configured to switch the control signal.

With this configuration, the discriminating means uses whether or not the reproduced signal can be actually read, with respect to the physical discriminating object such as the recording surface position (height) of the disc, which is more reliable in discriminating. Is to improve.

Further, a physical discriminating means using a physical discriminating criterion such as the recording surface position (height) of the disc, and a signal for discriminating whether the discriminated result is correct or not depending on whether or not the reproduced signal can be actually read. In combination with the use determining means, the physical determining means is used first, and then the signal use determining means is used.

With this configuration, the disc type can be completely discriminated.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to a plurality of embodiments of the present invention shown in FIGS. FIG. 1 is a block diagram of an optical disk device according to an embodiment of the present invention. 2 to 6 are explanatory views for explaining the principle of discriminating a plurality of types of discs according to the embodiment of the present invention. 7 and 9 are explanatory diagrams for clarifying the factors that make it difficult to discriminate between a plurality of types of discs. FIG. 10 is a block diagram showing a specific configuration of the pickup. FIG. 11 is a diagram showing a specific configuration example of a preamplifier circuit for a reproduced signal detected from a disc. FIG. 12 is a waveform diagram showing a reproduction signal waveform example when the objective lens is focused on the recording surface of the disc.

First, FIG. 2 to FIG. 6 and FIG. 7 to FIG.
Using multiple (here, CD and DVD).
We will clarify the principle of disc discrimination and clear issues.

In FIGS. 2 and 3, reference numeral 1 denotes a disk, 1a
Is a recording surface, 2a is a clamper, and 2b is a turntable. The disk is fixed by these 2a and 2b, and is rotated by a spindle motor not shown in this figure. 20a is a CD with a numerical aperture (NA) for CD of 0.45
Objective lens, 20b a DVD objective lens with a numerical aperture (NA) for DVD of 0.6, 21 a lens holder, 22
Is a yoke of the actuator, 23 is a shaft for rotating and sliding the lens holder 21, and 24 is a hole for a laser beam.

A shaft 23 is implanted in the yoke 22, and a focus coil (not shown) and a tracking and lens switching coil (not shown) are attached to the yoke 22. Magnets (not shown) attached to the lens holder 21 are attached at positions opposed to the respective coils. And the current flows through each coil, the lens reference position (initial position)
Therefore, the focusing and tracking of the objective lens and the lens switching operation are performed. The lens holder 21 is rotatably and slidably held by a shaft 23, and a CD
When the objective lens 20a for DVD and the objective lens 20b for DVD are attached and the lens holder 21 is rotated 180 °, the CD
The positions of the objective lens 20a for DVD and the objective lens 20b for DVD are interchanged so that the objective lenses can be switched. Note that h represents the distance from the reference position of the objective lens to the surface of the disc, and when the CD objective lens 20a detects a CD (corresponding to FIG. 2) and when the DVD objective lens 20b detects a DVD (FIG. 3) and values of h are set to be similar.

FIG. 4 is a view of the relationship between the pickup shown in FIGS. 2 and 3 and the mounted disc as seen from the top (or bottom) of the disc. 4, constituent elements given the same reference numerals as those in FIGS. 2 and 3 are the same constituent elements as those in FIGS. 2 and 3. Reference numeral 4 denotes a lead screw, which moves the pickup 25 in the radial direction of the disc by being rotated by a thread motor (not shown).

FIG. 5 illustrates the principle of disc discrimination when the distance from the disc surface to the recording surface is different as in the case of CD and DVD. In FIG. 5, (1) is DV
The case where D is mounted is shown, and (2) shows the case where CD is mounted. The reference numeral of the objective lens is 20, but this is the objective lens 20a for CD and the DVD.
This means that any of the objective lenses 20b for use may be used. As can be seen from the figure, the distance between the objective lens 20 and the disk surface is 0.6 mm shorter in the case of a DVD when considering the CD as a reference, and 0.6 mm longer in the case of the CD when considering the DVD as a reference. . The distance from the disk surface to the objective lens 20 can be detected by detecting the voltage level or the current level of the drive signal of the objective lens when performing focus control.

FIG. 6 shows the relationship between the position of the objective lens 20 in the direction perpendicular to the disk surface and the drive signal level of the objective lens. The horizontal axis is the lens drive voltage (current) and the vertical axis is the objective. The position of the lens. In FIG.
(1) shows the case of driving and detecting with the objective lens for CD, and (2) shows the case of driving and detecting with the objective lens for DVD. When the objective lens for CD of (1) is used, the origin of the lens position is mechanically set to a position which becomes a focal point when reproducing a CD. In this case, the CD
If is attached, the drive voltage (current) becomes “0” and DV
If D is attached, the objective lens is 0.
Since it is necessary to approach the disk surface by 6 mm, the driving voltage (current) becomes V (A) dvd on the + side. Therefore, the drive voltage (current) is 0.3 when discriminating the mounted disc.
If it is larger than V (A) th corresponding to mm, it can be discriminated as a DVD, and if it is smaller, it can be discriminated as a CD. on the other hand,
In the case of using the objective lens for DVD of (2), the origin of the lens position is mechanically set at a position which becomes a focal point when the DVD is reproduced. In this case, the drive voltage (current) becomes “0” when the DVD is mounted, and the objective lens needs to be separated from the disc surface by −0.6 mm in order to focus when the CD is mounted. Drive voltage
(Current) becomes V (A) cd on the minus side. Therefore, the drive voltage (current) is -0.3 mm when discriminating the mounted disc.
If it is larger than V (A) th corresponding to
If it is small, it can be discriminated as a CD.

The above is the principle of disc discrimination when the distance from the disc surface to the recording surface is different as in the case of CD and DVD. However, in reality, due to various unfavorable factors, erroneous discrimination may occur even if the above discrimination principle is directly applied.

The first factor is a phenomenon called surface wobbling of the disk. This is when the disc is not perfectly flat but has warp and curvature, or when the disc surface of the mounted disc is not perpendicular to the rotation axis of the spindle motor due to the influence of mechanical accuracy of the turntable. Occurs in. FIG. 7 shows a specific state of the above-mentioned surface wobbling. In FIG. 7, (1) is an ideal disc state,
(2) is a state where the disk surface is rotating in a state where the disk surface is not perpendicular to the rotation axis of the spindle motor, (3)
And (4) shows a stationary state in the case of (2), and (5) and (6) show a state where the disk is deformed into a bowl shape. In addition to this, there is also a kamaboko type deformation and the like. For these surface runouts, the permissible values are set for CDs and DVDs as a disc.
0.5 mm and DVD are regulated to ± 0.3 mm.

FIG. 8 shows the relationship between FIG. 6 and the relationship between the position of the objective lens used for disc discrimination in the direction perpendicular to the disc surface and the drive signal level of the objective lens in consideration of these allowable surface shake amounts. Show. FIG. 8 shows a case of driving and detecting with a DVD objective lens. In FIG. 8, when a DVD is mounted, there may be a deviation of ± 0.3 mm, so there may be a case of focusing at a position of −0.3 mm. On the other hand, when a CD is mounted, there may be a deviation of ± 0.5 mm, so it is + for a position of -0.6 mm.
If there is a surface runout of 0.5 mm, it may focus at a position of -0.1 mm. Therefore, the shaded portion (-0.1 to -0.3 mm) in FIG. 8 is a range that can occur regardless of whether the mounted disc is a CD or a DVD, and erroneous disc determination occurs.

The second erroneous determination factor is a mechanical relative error between the mounting position of the disc and the reference mounting position of the objective lens, and variations in actuator sensitivity (moving distance of the objective lens with respect to the drive signal level of the objective lens). Can be given. FIG. 9 shows the relationship in FIG. 6 with respect to these factors, that is, the relationship between the position of the objective lens used for disc discrimination in the direction perpendicular to the disc surface and the drive signal level of the objective lens. In FIG. 9, (1) is the previous FIG.
(1) shows the ideal characteristics, and (2) shows the case where the characteristics deviate due to the above factors. First, the fact that the intersection with the vertical axis is on the negative side is due to a mechanical error between the mounting position of the disk and the reference mounting position of the objective lens, and the small inclination means that the actuator sensitivity is small. It shows the case. In the case of the characteristic (2), the drive voltage (current) focused at the time of mounting the DVD is V (A), which is larger than V (A) th, and is therefore discriminated as a CD. .

An example of an embodiment for solving the above disc erroneous determination factors will be described below. First, a first embodiment example for solving the first erroneous discrimination factor will be described with reference to FIG.

FIG. 1 is a block diagram of an optical disk device according to an embodiment of the present invention. In FIG. 1, 1
Is a disk, 2a is a clamper, 2b is a turntable,
3 is a pickup, 4 is a lead screw, 5 is a thread motor, 6 is a spindle motor, 7 is a position sensor, 8
Is a spindle control circuit, 9 is a thread control circuit, 10 is a sensor amplifier, 11 is a tracking control circuit, 12 is a focus control circuit, 13 is a data strobe circuit, 1
Reference numeral 4 is a CD decoder, 15 is a DVD decoder, 16 is a microcomputer (hereinafter referred to as a microcomputer), 1
7 is an output terminal.

In FIG. 1, first, when the disc 1 is loaded, the microcomputer 16 sets the pickup 3 to the disc 1
A control signal is supplied to the sled control circuit 9 so as to move to the vicinity of the innermost circumference. The sled control circuit 9 receives this control signal and supplies a rotation drive signal to the sled motor 5 to rotate the sled motor 5. The rotation of the sled motor 5 is
The pickup 3 is transmitted to the lead screw 4 and moves the pickup 3 in the inner circumferential direction of the disc. At this time, the position sensor 7 for detecting the position of the pickup 3 detects that the pickup 3 has come near the innermost circumference of the disc, and supplies the detection signal to the microcomputer 16. Therefore, the microcomputer 16
Uses the detection signal of the position sensor 7 to move the pickup 3 to the vicinity of the innermost circumference of the disc. If the pickup 3 is already in the vicinity of the innermost circumference of the disk when the disk 1 is mounted, immediately after the mounting of the disk 1, the position sensor 7 outputs a detection signal indicating that the pickup 3 is in the vicinity of the innermost circumference of the disk. Since it is supplied to 16, the moving operation of the pickup 3 is omitted.

Upon completion of the movement of the pickup 3 to the innermost circumference, the microcomputer 16 supplies a light emission control signal to the semiconductor laser in the pickup 3. Pickup 3
FIG. 11 shows a configuration example of the semiconductor laser and the optical system of FIG. In FIG. 10, 20a and 20b are objective lenses, and 2
5 is a semiconductor laser, 26 is a reflecting prism, 27 is a half mirror, and 28 is a photodetector. In FIG. 10, the light flux emitted by the semiconductor laser 25 is the half mirror 2.
The light is reflected by the surface 7 and reflected by the surface of the reflection prism 26, enters the objective lens 20, and is condensed on the disk 1 of FIG. The laser reflected light from the disk 1 passes through the objective lens 20, is reflected by the reflection prism 26, passes through the half mirror 27, and is incident on the photodetector 28. The detection signal from the photodetector 28 enters the sensor amplifier 10,
Amplified and processed, and output as a pit detection signal, a focus error signal, and a tracking error signal. FIG. 11 shows a specific configuration example of the sensor amplifier 10.

In FIG. 11, 28 is four areas A,
Photodetectors B, C and D, 31a to 31d are preamplifiers for the four photodetection areas, 32 to 36 are addition circuits, 37 and 38 are subtraction circuits, and 39 to 41 are output terminals. Reference numeral 29 is a pit on the disk, and 30 is a simulated beam spot of the reflected laser beam on the photodetector 28. The sensor amplifier 10 outputs the detection signals from the four areas of the photodetector 28 to 31a to 31d.
Of the preamplifier, and the adder circuits 32 to 35 add the two signals shown in the figure. The added detection signal is further calculated by the addition circuit 36 and the subtraction circuits 37 and 38, and the pit detection signal (A + B + C + D), the focus error signal (A + C−B−D), and the tracking error signal (A + D−B−C). ) Is output via the output terminals 39 to 41.

Of the above three signals, the pit detection signal (A +
B + C + D) and focus error signal (A + C-B-D)
FIG. 12 shows the signal waveform of. In FIG. 12, the horizontal axis represents the distance between the objective lens and the disc, and the vertical axis represents the signal level. And (1) is the pit detection signal (A + B + C + D)
The waveform is (2) and the focus error signal (A + C-B)
-D) Waveform. As can be seen from the figure, the pit detection signal (A + B + C + D) has a maximum value and the S-curve of the focus error signal (A + C−B−D) has a zero crossing feature at the point where the objective lens is focused on the disc recording surface. Have.

The above three detection signals amplified and processed by the sensor amplifier 10 as described above are supplied to the tracking control circuit 11, focus control circuit 12 and data strobe circuit 13 shown in FIG.

Here, the type of the mounted disc 1 is discriminated by the focus control circuit 12 and the microcomputer 16 in the focus control process. First, microcomputer 1
Reference numeral 6 instructs the focus control circuit 12 to generate a focus scan signal. This focus scan signal is
It is a drive signal for gently moving the objective lens 20 in a direction approaching the disc 1 from the lowest movable point, and is generated by the focus control circuit 12. Focus control circuit 12
The focus scan signal generated by the objective lens 20 is supplied to the focus coil of the pickup 3.
In the focus direction (perpendicular to the disc surface). When the objective lens 20 approaches the in-focus point, the level of the pit detection signal (1) shown in FIG. 12 increases and the focus error signal (2) has an S-shaped curve characteristic. The focus control of the objective lens 20 is realized by switching from the focus scan signal to the drive signal for feedback control using the focus error signal near the zero cross point in the S curve. The drive signal level of the objective lens 20 at the time of switching from the focus scan to the feedback control in the focus control circuit 12 is supplied to the microcomputer 16. Therefore, the microcomputer 16
Will obtain drive signal level information at the point where the objective lens 20 is in focus. The microcomputer 16 uses the focus control circuit 12 as a process for detecting the amount of movement of the objective lens 20.
The supplied focus coil drive signal level is compared with the preset determination reference (threshold) level shown in FIG. 6 to determine the type of disc having a different recording surface height.

Of course, the objective lens 2 at this point
It is necessary for the microcomputer 16 to recognize whether 0 is for a CD or a DVD, but this may be fixed to a CD or a DVD when the disc is mounted, or the latest setting. That is, an objective lens suitable for the previous disk may be used, but in any case, the microcomputer 16 can recognize the type of objective lens. The microcomputer 16 which has discriminated the type of the disk sends the mode control signal to the data strobe circuit 13, the CD decoder 14, the D
The objective lens 20 is supplied while being supplied to the VD decoder 15.
In the case of different types, the objective lens 20 is switched via the tracking control circuit 11. In this example, since the movement of the objective lens 20 in the tracking direction and the movement direction of the lens switching are the same in switching the objective lens 20, the tracking direction drive signal to the objective lens 20 is kept at a predetermined level or higher for a predetermined time or longer. By applying it, the objective lens can be switched.

What is important in the above description is that first, when disc type is determined when the disc is mounted, the pickup 3 is moved to the innermost circumference of the disc, and the recording surface position of the disc near the innermost circumference. Is to detect. This is because when the mounted disc has a surface runout as shown in FIG. 7, that is, when the disc is not completely flat and has a warp and a curve, or the mounted disc surface is affected by the mechanical accuracy of the turntable. Even if the disk is not perpendicular to the rotation axis of the spindle motor, the fact that the surface runout is less affected near the innermost circumference of the disk is used.

When the discrimination of the type of the mounted disk is completed by the above operation, the microcomputer 16 commands each block to perform a normal reproducing operation. First, the microcomputer 16 commands the spindle motor control circuit 8 to generate a drive signal for starting the spindle motor, which causes the spindle motor 6 having the disk 1 to rotate. The pit detection signal supplied from the sensor amplifier 10 is the data strobe circuit 1
3 and the tracking error signal is supplied to the tracking control circuit 11. Tracking control circuit 11
Supplies a drive signal to a tracking coil (not shown) in the pickup 3 to move the objective lens 20 in the tracking direction (radial direction of the disk) based on the tracking error signal, and performs feedback tracking control.

The tracking drive signal is supplied to the sled control circuit 9 so as not to exceed the movable range of the objective lens 20 when the position of the target track moves as the disc rotates. This is because the sled control circuit 9 detects the tracking drive signal level, and if the level exceeds a predetermined range, it is determined that the movable range of the objective lens 20 is small, and the sled motor 5 is rotated. By moving the pickup 3 itself in the desired disc radial direction, tracking control by the objective lens 20 can always be performed within the movable range.

On the other hand, in the data strobe circuit 9 to which the pit detection signal is supplied, after the waveform of the pit detection signal is equalized, it is converted into a logic signal level so as to enable digital signal processing and is synchronized with the detection signal. The reproduced clock signal is reproduced, "0" and "1" of the data are discriminated using this clock signal, and reproduced data is supplied to the next-stage CD decoder 14 and DVD decoder 15. A PLL (Phase Locked Loop) is usually used for the clock reproduction, and the characteristics of the PLL (center frequency and pull-in / hold range) and the waveform equalization characteristics are determined by a microcomputer according to the disc type discrimination result. It is optimally switched by a mode control signal supplied from 16.

The CD decoder 14 or the DVD decoder 15 subjects the reproduction data supplied from the data strobe circuit 13 to processing such as synchronization signal detection, serial / parallel conversion, and demodulation, and a code error generated in the reproduction process. Is detected and corrected, and a reproduction signal is output via the output terminal 17. When the mounted disk is a CD, the CD decoder 14 and the DVD decoder 15 are set to the operating state and the DVD decoder 15 to the stopped state by a mode control signal supplied from the microcomputer 16. If a DVD disc is loaded, the CD
The decoder 14 for DVD is set to the stopped state and the decoder 15 for DVD is set to the operating state.

Further, in the present optical disk device, since the rotation control of the disk is premised on the CLV control (constant linear velocity control), apart from the start control of the disk rotation, in the steady rotation control, the synchronization signal cycle included in the reproduction signal is set. The rotation control of the disk is performed so that is constant. This is a CD
The synchronizing signal detected by the decoder 14 for DVD or the decoder 15 for DVD is supplied to the spindle control circuit 8, and the spindle control circuit 8 generates a disc rotation speed error signal and feeds it back to the spindle motor 6. .

In this example, the tracking control circuit 1
1 is supplied with a pit detection signal, which is a signal used to count the number of jumps of a track when a track is greatly jumped when seeking,
It is usually called a mirror signal. The mirror signal and the tracking error signal become a signal having a phase difference of about 90 °, and the polarities of the phase difference are opposite when the track jump is directed in the inner peripheral direction and when the track jump is directed in the outer peripheral direction. The actual track jump direction can be identified. Information on the track jump direction and the number of track jumps is supplied to the microcomputer 16 and used for seek control.

As described above, by using this embodiment, even for a disk whose disk surface which is the first factor is not uniform in the radial direction, that is, a disk which causes surface wobbling. , The position of the recording surface of the disk is detected near the innermost circumference of the disk with the least amount of surface wobbling, and it is possible to reliably discriminate between two or more types of disks with different recording surface heights. Becomes

Next, with respect to the first embodiment described above,
A second embodiment for further improving the disc identification reliability will be described with reference to FIG.

FIG. 13 is a block diagram of an optical disk device according to an embodiment of the present invention. The blocks denoted by the same reference numerals as those in FIG. 1 have the same configuration and operation as those of the blocks described in the first embodiment.
13 differs from FIG. 1 in that an amplifier 18 is provided and rotation information of the spindle motor 6 is supplied to the microcomputer 16. In FIG. 13, a signal having a frequency proportional to the rotation of the spindle motor 6 is generated by the spindle motor 6 and supplied to the amplifier 18. Although not shown, this frequency signal is a Hall element or MR in which the magnetic flux of a magnet magnetized in the rotor part of the motor is installed on the stator side.
It is detected by an element or a coil, etc.
A plurality of cycles are generated for rotation. this is,
It may be a signal such as a rotation phase detection signal of a motor used for phase switching of a drive signal used in an ordinary three-phase brushless DC motor or the like, or may be newly generated by setting a rotary encoder or the like. The frequency signal supplied from the spindle motor 6 is limit-amplified by the amplifier 18 to a level detectable by the microcomputer 16 and supplied to the microcomputer 16.

In the embodiment shown in FIG. 13, the type of the mounted disc is determined while the disc is rotating. In FIG. 13, when the disc 1 is mounted, the microcomputer 16 supplies a control signal to the sled control circuit 9 to move the pickup 3 to the vicinity of the innermost circumference of the disc 1 as in the case of FIG. Then, upon completion of the movement of the pickup 3 to the innermost circumference, the microcomputer 16
Supplies an emission control signal to the semiconductor laser in the pickup 3 to make the semiconductor laser emit light. After that, the microcomputer 16 commands the spindle control circuit 8 to rotate the spindle motor 6 to rotate the spindle motor. The frequency signal is also supplied to the spindle motor control circuit 8, and the spindle motor control circuit 8
Until the sync signal information of the reproduction signal is supplied from the D or DVD decoders 14 and 15, feedback control is performed so that the cycle of the frequency signal becomes a predetermined cycle, and the determination of the mounted disk is completed. The disk is previously controlled to rotate at a predetermined rotation speed.
In this state, the microcomputer 16 commands the generation of the focus scan signal as in the case of FIG. 1, whereby the focus control circuit 12 moves the objective lens 20 gently in the direction approaching the disc 1 from the lowermost movable point. At the same time, when the objective lens 20 approaches the in-focus point, the pit detection signal and the focus error signal having the waveforms shown in FIG. 12 shift to focus control pull-in and steady control.
The drive signal level of the feedback control using the focus error signal in the vicinity of the zero cross point in the S curve of the focus error signal in the focus control state is supplied to the microcomputer 16. The focus drive signal level supplied to the microcomputer 16 is detected by the microcomputer 16 at the frequency signal cycle of the spindle motor 6 supplied from the amplifier 18, and is averaged over one rotation period of the disk. Then, the microcomputer 16 uses the averaged focus drive signal level and compares it with the preset reference (threshold) level for discrimination shown in FIG. Determine the type.

The averaging process of the focus drive signal level in the microcomputer 16 over one rotation period of the disk is performed as shown in FIG. In FIG. 14, the horizontal axis represents time and the vertical axis represents the lens drive signal level in the focus direction. A plurality of dotted lines parallel to the vertical axis indicate the focus drive signal level detection timing in the microcomputer 16. In the case of this example shown in FIG. 14, the frequency signal is 12 cycles for one rotation of the disk. The focus drive signal waveform on the lower side of FIG. 14 has a substantially sinusoidal shape in the case of uniform surface wobbling, and the averaging in this case is the average value by integration over one rotation cycle and the maximum value. The average value of the minimum values is the same value (1). On the other hand, the focus drive signal waveform on the upper side of FIG. 14 has a distorted waveform in the case of non-uniform surface wobbling, and the averaging in this case is the average value (3) by integration over one rotation cycle, The maximum value and the average value of the minimum value are the same value (2), which is different. However, since there is no actual disc that has an extremely distorted waveform due to nonuniformity, any of the above methods may be used for the averaging process.

In FIG. 14, except for the disc type discriminating operation in the disc rotating state described above, the operation is the same as that of the first embodiment described with reference to FIG. 1, and therefore the explanation is omitted here.

As described above, by using this embodiment, even for a disk whose disk surface which is the first factor is not uniform in the radial direction, that is, a disk which causes surface wobbling. Detecting the position of the recording surface of the disk that is averaged over one rotation of the disk in the vicinity of the innermost circumference of the disk with the least amount of surface wobbling, and there are two or more types with different recording surface heights. Since the disc type is discriminated, it is possible to discriminate the disc with higher reliability.

Next, a third embodiment for solving the above-mentioned second erroneous discrimination factor, that is, the mechanical relative error between the mounting position of the disk and the reference mounting position of the objective lens and the dispersion of the actuator sensitivity will be described. Will be described with reference to FIG.

FIG. 15 is a block diagram of an optical disk device according to an embodiment of the present invention. 1 and FIG.
The blocks denoted by the same reference numerals as 3 have the same configurations and operations as the blocks described in the first or second embodiment. 15 is different from FIG. 14 in that a memory 19 connected to the microcomputer 16 is provided. Information for correcting the mechanical relative error between the mounting position of the disc and the reference mounting position of the objective lens and the variation of the actuator sensitivity is written in the memory 19, and when the disc type is determined, the correction is performed. It uses information.

In the present embodiment, a standard CD is used on the manufacturing line or inspection line of the present disk device.
And the DVD is used for adjustment. The standard product mentioned here is a disc specially made for testing or adjustment, and means a disc in which the amount of surface runout and the distance from the disc surface to the recording surface are highly controlled. First, in FIG. 15, the microcomputer 16 supplies the tracking control circuit 11 with a command to switch the pickup 3 to the CD objective lens when the standard CD is mounted. And pickup 3
Is moved to near the innermost circumference of the disc and the disc is rotated. In this state, the focus scan operation and the focus control operation are performed, and the average focus drive signal for one rotation of the disk in the focused state is detected. In this case, if the mechanical relative error between the mounting position of the disc and the reference mounting position of the objective lens or the offset in the electric circuit of the focus control system is zero, the focus drive is performed as shown in (1) of FIG. Although the signal level becomes zero, it does not become zero as shown in (2) of FIG. 9 when there is a mechanical relative error or an offset in an electric circuit. The focus drive signal level at this time is temporarily stored in the microcomputer 16. Next, the mounted disc is transferred from the standard CD to the standard DVD, and the focus control operation similar to that of the standard CD is performed. In this case, since the position of the disc recording surface is closer to 0.6 mm than the standard CD, the objective lens 20 is closer to the disc by 0.6 mm, and the focus drive signal level naturally becomes higher by 0.6 mm. (However, this is the case where the relationship between the position of the objective lens and the polarity of the drive signal level is that shown in FIG. 6 above.) When the standard DVD is mounted, the focus drive signal level at the focused point is set by the microcomputer 16 By detecting with
The relationship between the position of the objective lens 20 (the position in the direction perpendicular to the disk surface) and the focus drive signal level and the relationship between the drive signal level of the objective lens, which are peculiar to the individual optical disk device, are shown in FIG. Will be clear. That is,
Regarding the actual characteristic shown in (2) of FIG. 9, the intersection with the horizontal axis that has already been temporarily stored and the other one point can be determined, so that the characteristic can be specified, and the target shown in (1) of FIG. It becomes possible to calculate the correction information to be the standard characteristic.
The calculation of the correction information is performed by the microcomputer 16 and stored in the memory 19.

Next, similar correction information is calculated and stored for the DVD objective lens. This is the above C
After the calculation and storage of the correction information for the D objective lens is completed, the microcomputer 16 supplies the tracking control circuit 11 with a command for the pickup 3 to switch to the DVD objective lens.
Then, the average focus drive signal for one rotation of the disc in the focused state is detected. Then, the mounted disc is transferred from the standard DVD to the standard CD, and the focus control operation similar to that of the standard DVD is performed. In this case, the position of the disc recording surface is 0.6 with respect to the standard DVD.
The objective lens 20 is 0.6 m away
As a result, the focus drive signal level is lowered by 0.6 mm. (However, this is the case where the relationship between the position of the objective lens and the polarity of the drive signal level is that shown in FIG. 6 above.) When the standard CD is mounted, the focus drive signal level at the focused point is set by the microcomputer 16 The detection information can be used to calculate the correction information for the target standard characteristic, and the microcomputer 16 calculates the correction information when the objective lens for DVD is used and stores it in the memory 19.

The order of the above processing is not limited to the above, and for example, focus drive signal level information using the CD objective lens and focus drive signal level information using the DVD objective lens when the standard CD is mounted. Is detected and stored temporarily, and then the mounted disc is standard DV
By replacing the information with D, the focus drive signal level information using the CD objective lens and the focus drive signal level information using the DVD objective lens are detected, and finally the correction information stored in the memory 19 is calculated. good.

At the time of reproduction, focus control is performed on the mounted disc as in the second embodiment shown in FIG. In the microcomputer 16 to which the focus drive signal level at the focused point is supplied from the focus control circuit, for example, when the CD objective lens is selected, the objective lens position and the focus drive signal shown in FIG. Using the correction information stored in the memory 19, the level relationship characteristic (1) characteristic is equivalently shown in FIG.
The focus drive signal level is converted to CD
And V (A) which is the threshold level for discriminating DVD
The disc to be mounted is discriminated by determining whether it is larger or smaller than th. Even when the DVD objective lens 20b is selected, the relationship information between the objective lens position and the focus drive signal level is shown in (2) of FIG. 6 using the correction information stored in the memory 19 as in the above. It is converted to ideal characteristics and the type of mounted disc is determined.

As described above, when the present embodiment is used, the mechanical relative error between the mounting position of the disk and the reference mounting position of the objective lens, which is the second factor, and the dispersion of the actuator sensitivity are caused. Even if the relationship characteristic between the focus drive signal level and the position or movement amount of the objective lens deviates from the original design center, the characteristic can be corrected and the disc can be correctly discriminated. It is possible to discriminate a high disc type.

The memory 19 is rewritable, and is stored in a flash memory or an EE so that the stored contents are not erased even when the power of the apparatus is turned off.
A P-ROM (electrically rewritable ROM) is used.

The above-mentioned discs to be mounted are basically discriminated by detecting the difference in the distance from the disc surface to the recording surface.

Next, a fourth embodiment will be described in which the mounted disc is discriminated using the reproduction signal detected from the disc. According to the disc discrimination principle in the fourth embodiment, the mounted disc is reproduced in the set mode (CD mode or DVD mode), and if correct data is reproduced within a predetermined time, the setting mode is correct. If the correct data is not reproduced even after the predetermined time elapses, it is judged that the setting mode is wrong, and the setting mode is switched to another possible setting mode to try the reproduction. The correct data here means whether or not the data format of the sync signal pattern or its block configuration, error detection / correction code configuration, etc. matches a predetermined data format of, for example, a CD or a DVD. It does not mean the correctness of the information provided. Hereinafter, the fourth embodiment using the above disc discrimination principle will be described with reference to FIG.

FIG. 16 is a block diagram of an optical disk device according to an embodiment of the present invention. The blocks denoted by the same reference numerals as those in FIGS. 1, 13 and 15 have the same configurations and operations as the blocks described in the first, second or third embodiment. The difference between FIG. 16 and FIG. 15 is that detection information of correct data of reproduction data detected by the CD decoder 14 and the DVD decoder 15 is supplied to the microcomputer 16.

In FIG. 16, the microcomputer 16 determines the mode, that is, the CD reproduction mode or the DVD reproduction mode, according to the disc discrimination result shown in the above three embodiments after the disc is mounted and the mode setting is performed. Generate a signal. According to the mode setting signal, the CD decoder 14 or the DVD decoder 15 starts the decoding process of the reproduction data. Then, the CD decoder 14 and the DVD decoder 15 perform processing such as synchronization signal detection, serial / parallel conversion, and demodulation on the reproduction data supplied from the data strobe circuit 13 as described above with reference to FIG. The code error generated in the process is detected and corrected, and the reproduced signal is output through the output terminal 17. At this time, in the configuration of FIG. 16, when the error detection of the reproduction data using the error detection / correction code is performed and the correct data is detected, the detection signal of the correct data is supplied to the microcomputer 16.

When the Reed-Solomon code or the like is used as the error effect / correction code used in, for example, a CD or a DVD, the correct data is detected by calculating the syndrome in units of the error detection / correction code block. If the block of which the syndrome is "0" is detected, one pulse is supplied to the microcomputer 16. Therefore, when correct error detection / correction code blocks are reproduced in succession, the same number of correct data detection pulses are output.

The microcomputer 16 returns to the CD decoder 14 or DV within a predetermined time after the mode control signal is generated.
The number of correct data detection pulses supplied from the D decoder 15 is measured. If the measured number is equal to or more than a predetermined value, it is determined that the currently set mode is correct, reproduction is continued, and within a predetermined time. If the coefficient value of 1 does not reach the predetermined value, it is determined that the current setting mode is incorrect, and the setting mode is switched. In this example, the modes are the CD reproduction mode and the DVD reproduction mode, and therefore the switching may be performed exclusively. However, the present invention does not limit the number of reproduction modes. If there are three or more setting modes, if it is determined that the setting modes are incorrect, the settable modes are sequentially set again. It is something to go.

Since the CD and DVD have different data transfer rates, sync signal patterns, error detection / correction code block configurations, etc., the DVD decoder 15 processes the data reproduced with the CD mounted. In some cases, the data that will be played back when the DVD is installed on the CD
In the case of processing by the decoder 14, that is, in the case where the setting mode and the mounted disc are different from each other, it is extremely rare that a correct data detection pulse is generated. One to several pulses are sufficient as the predetermined value of the number.

In the discrimination of the mounted disc using the above reproduction data, when the setting mode and the actual mounted disc match, the time required for the discrimination is practically "0",
When the setting mode and the actual mounted disk are different, it is determined that the setting mode is incorrect after measuring the detection signal of correct data for a predetermined time, and in this case, the time required for the determination becomes long. Therefore, in this embodiment,
As described at the beginning, when the disc is mounted, the microcomputer 16 first sets the mode according to the disc discrimination result of any one of the three embodiments described above.

As described above, according to the present embodiment, whether or not the reproduced signal can be actually read is used for the physical discrimination target such as the recording surface position (height) of the disk. It is a discriminating means and can ensure the reliability of discrimination.

Further, a physical discriminating means using a physical discriminating criterion such as the recording surface position (height) of the disc, and a signal for discriminating whether the discriminated result is correct or not depending on whether or not the reproduced signal can be actually read. By combining with the use determination means, the time required for the determination can be shortened and the usability can be improved.

In the above description, CD and DVD
It has been explained that the difference in the distance from the disc surface to the recording surface directly becomes the difference in the distance from the objective lens and the disc surface at the time of focusing, but strictly speaking, the distance from the disc surface to the recording surface is Due to the difference, a slight deviation occurs in the difference between the two distances due to an optical factor. However,
The effect of this difference is at a level that can be sufficiently dealt with by the effect of the present invention.

Further, the above-mentioned sensor amplifier configuration uses the astigmatism method as the focus error detection method, and it is assumed that the push-pull method is used as the tracking error detection method. Obviously, the method is not limited to these methods.

In the present embodiment, the objective lens for CD and the objective lens for DVD are provided separately, but one objective lens having a variable numerical aperture (NA) may be used.

[0077]

As described above, according to the present invention, even a disk whose disk surface is not uniform in the radial direction, that is, a disk which causes surface wobbling, has the smallest amount of surface wobbling. Near the innermost circumference of the disc, the disc is rotated, and the position of the recording surface of the disc averaged over one revolution of the disc is detected.
There is a mechanical relative error between the mounting position of the disc and the reference mounting position of the objective lens, and there is variation in the sensitivity of the actuator, and the relationship characteristic between the focus drive signal level and the position or movement amount of the objective lens is from the initial design center. Even if there is a deviation, the characteristic can be corrected and the position of the recording surface of the disc can be correctly detected, so that the disc to be mounted can be discriminated with high reliability.

Furthermore, not only the physical discrimination target of the recording surface position (height) of the disc but also whether or not the reproduced signal can be actually read is used to determine the final disc discrimination with respect to the physical discrimination result. By performing the above, it is possible to completely eliminate erroneous discrimination and ensure the reliability of discrimination.

By combining the above-mentioned physical discriminating means and discriminating means using reproduced data, the time required for the discrimination in most cases can be shortened and the usability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an objective lens mechanism according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an objective lens mechanism according to an embodiment of the present invention.

FIG. 4 is a top view showing the relationship between the pickup and the disc according to the embodiment of the present invention.

FIG. 5 is a principle diagram showing a principle of means for physically discriminating a type of a disc according to an embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between an objective lens position and a drive signal level of the objective lens according to the embodiment of the present invention.

FIG. 7 is a copy diagram of a disk for explaining surface wobbling of the disk.

FIG. 8 is a characteristic diagram showing a disc determination range at a drive signal level when a DVD objective lens according to an embodiment of the present invention is used.

FIG. 9 is a diagram of an actual characteristic example showing the relationship between the objective lens position and the drive signal level of the objective lens according to the embodiment of the present invention.

FIG. 10 is a block diagram showing a specific configuration example of the pickup 3 according to the embodiment of the present invention.

FIG. 11 is a block diagram showing a specific configuration example of a preamplifier circuit for a reproduction signal detected from the disc according to the embodiment of the present invention.

FIG. 12 is a signal waveform diagram of a pit detection signal and a focus error signal according to the embodiment of the present invention.

FIG. 13 is a block diagram of an optical disc device according to an embodiment of the present invention.

FIG. 14 is a waveform diagram of a focus drive signal during disk rotation according to the embodiment of the present invention.

FIG. 15 is a block diagram of an optical disc device according to an embodiment of the present invention.

FIG. 16 is a block diagram of an optical disc device according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Disc, 1a ... Disc recording surface, 3 ... Pickup, 4 ... Lead screw, 5 ... Thread motor, 6
... Spindle motor, 7 ... Position sensor, 8 ... Spindle control circuit, 9 ... Thread control circuit, 10 ... Sensor amplifier, 11 ... Tracking control circuit, 12 ... Focus control circuit, 13 ... Data strobe circuit, 14 ... CD
Decoder, 15 ... DVD decoder, 16 ... Microcomputer, 17, 39-41 ... Output terminal, 18 ... Amplifier, 19 ... Memory, 20a ... CD objective lens, 20
b ... Objective lens for DVD, 21 ... Lens holder, 22
... Yoke, 23 ... Axis, 24 ... Hole, 25 ... Semiconductor laser, 26 ... Reflecting prism, 27 ... Half mirror, 28 ...
Photodetectors, 31a to 31d ... Preamplifiers, 32 to 36 ...
Adders, 37, 38 ... Subtractors.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukinobu Tada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Multimedia System Development Headquarters (72) Inventor Ikuo Nishida Yoshida, Totsuka-ku, Yokohama-shi, Kanagawa 292, Machi Stock Company Hitachi, Ltd. Visual Information Media Division

Claims (10)

[Claims] 1. In an optical disk device for optically reproducing or recording / reproducing a disk, an objective lens for focusing a laser beam on a recording surface of the disk and an objective lens for moving the objective lens in a first direction. First to focus on the recording surface of the disc
For moving the objective lens in the second direction to move the focal point of the objective lens in the radial direction of the disk, and the moving amount of the objective lens moved by the first moving means. At least a moving amount detecting means for detecting is provided, and when two or more kinds of discs having different heights from the surface of the disc to the recording surface are loaded, the second moving means moves the objective lens to the maximum position of the disc. The position of the recording surface of the disk is detected by moving to the vicinity of the inner circumference and detecting the amount of movement of the objective lens in the first direction by the first moving unit during the focusing operation by the moving amount detecting unit, An optical disk device characterized by discriminating between two or more kinds of disks having different recording surface heights. 2. In an optical disk device for optically reproducing or recording / reproducing a disk, an objective lens for focusing a laser beam on a recording surface of the disk and an objective lens for moving the objective lens in a first direction. First to focus on the recording surface of the disc
The moving means, the second moving means for moving the objective lens in the second direction to move the focus of the objective lens in the radial direction of the disk, and the moving amount of the objective lens moved by the first moving means. A disc is mounted on at least two types of discs having different heights from the disc surface to the recording surface, which are provided with at least a movement amount detecting unit for detecting and a position detecting unit for detecting the position of the objective lens in the second direction. At this time, the position detecting means detects the position of the objective lens in the second direction, and if the objective lens is not near the innermost circumference of the disc,
The objective lens is moved to the vicinity of the innermost circumference of the disc by the second moving means, and the moving amount detecting means detects the moving amount of the objective lens in the first direction by the first moving means during the focusing operation. Thus, the optical disc device is characterized in that the position of the recording surface of the disc is detected and the type of two or more discs having different recording surface heights is discriminated. 3. An optical disk device for optically reproducing or recording / reproducing a disk, wherein an objective lens for focusing a laser beam on a recording surface of the disk and the objective lens are moved in a direction substantially perpendicular to the disk surface. Moving means, rotating means for rotating the disk, focus control means for adjusting the focus of the objective lens to the recording surface of the disk by controlling the moving amount of the moving means, and movement of the objective lens moved by the moving means. A disc for two or more types of discs having different heights from the disc surface to the recording surface, which is provided with at least a movement amount detection unit for detecting the amount and a correction unit for correcting the movement amount detected by the movement amount detection unit. When the disc is mounted, the disc is rotated by the rotating means, and the focus of the objective lens is adjusted by the focus control means. While adjusting to the recording surface of the disc, the movement amount detecting means detects the amount of movement of the objective lens by the moving means at the time of focusing operation, and the correcting means detects the variation caused by the rotation of the disc from the detected movement amount. The optical disc device is characterized in that the position of the recording surface of the disc is detected from the corrected movement amount of the objective lens, and the type of two or more discs having different recording surface heights is discriminated. 4. The disc type according to claim 1, 2 or 3, comprising two or more objective lenses suitable for two or more types of discs having different recording surface heights, and disc type discriminating results. An optical disk device characterized in that reproduction or recording / reproduction is performed by switching to an objective lens conforming to. 5. The moving means according to claim 1, 2, 3 or 4, wherein the moving means is an electric moving means, and the moving amount detecting means detects a drive voltage or drive applied to the moving means of the objective lens. An optical disk device, which is a current, and discriminates a disk by detecting a difference in the height of the recording surface of the disk by using the relationship between the drive voltage or the drive current and the movement amount. 6. The optical disk device according to claim 5, wherein the relationship between the drive voltage or drive current and the amount of movement of the objective lens is variable according to the correction information stored in the storage means. 7. The focus detection means for detecting that the objective lens is in focus from the signal read from the recording surface of the disc according to claim 1 or 2, wherein the disc is mounted to read the contents of the disc. When the focusing operation of the objective lens is performed by the first moving means, the moving amount of the objective lens is detected by the moving amount detecting means, and the focus detecting means detects that the objective lens is in focus, An optical disk device characterized by determining the type. 8. An optical disk device for optically reproducing or recording / reproducing digital information corresponding to a plurality of kinds of disks, and a plurality of kinds of signal detecting means for optically detecting a signal from the disk, and the signal detecting means. Control means for performing focus control and tracking control at the time of signal detection, signal conversion means for converting the signal detected by the signal detection means into a digital signal, and a plurality of digital signal forms of the converted digital signal A plurality of decoding means for performing a decoding process having at least an error detection function, and a selecting means for selecting one from the plurality of signal detecting means and the plurality of decoding means according to a mode control signal, the selected decoding Mode control of the mode control signal generating means using error detection information of the means Optical disc apparatus being characterized in that so as to switch the issue. 9. The error detecting means according to claim 8 is configured to detect whether or not a correct digital signal is detected corresponding to an error detecting code format of the selected decoding means within a predetermined time. An optical disk device characterized by the above. 10. The optical disc apparatus according to claim 8 or 9, wherein the first mode of the mode control signal generated from the mode control signal generating means when the disc is inserted is defined in claim 1, 2 or 3. An optical disk device characterized in that the setting is made according to the result of disc type discrimination.