JP3163047B2 - Disk identification 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 disc discriminating apparatus used for a recording or reproducing apparatus for recording information on a recording medium or reproducing information from the recording medium.

[0002]

2. Description of the Related Art Conventionally, CD-ROM (Compac)
t Disk as Read-Only Memory
y), MO (Magneto-Optical dis)
A device for reproducing information from an optical disk having a large storage capacity such as k) or recording information on the optical disk is used as an external storage device of a computer.

In these optical disks, data is recorded by a change in shape or a change in magnetism on the recording surface of the optical disk, and the recording is performed by irradiating a laser beam on the recording surface of the optical disk and detecting reflected light thereof. The data is played. In recent years, with the demand for higher density information on optical discs or recording and reproduction of information including video and audio, DVD (Digital Vid)
eo Disk), etc., and AS-MO
(Advanced Storage-Magneto
The standardization of a new magneto-optical disk called an optical disk is in progress.

In the AS-MO, data is recorded on a magnetic optical disk by using heat of a laser beam and an external magnetic field, and data is recorded on the optical disk by a magneto-optical effect, like other MOs of the conventional ISO standard. The data is reproduced by detecting the magnetism recorded according to the above using a laser beam. In order to indicate the location (address) on the recording surface of the optical disk where the data is stored,
In other MOs other than the AS-MO, the shape and arrangement of the holes formed on the recording surface of the optical disk are changed.
In AS-MO, the shape of the groove formed on the recording surface of the optical disk is changed. That is, in other MOs, a pit row indicating address information is formed, and in the AS-MO, wobbles indicating address information are formed on a wall formed by lands and grooves.

When recording data on an optical disk or reproducing data from the optical disk, a synchronization signal is generated from the optical disk to measure the timing of recording or reproducing the data. This synchronization signal is generated by detecting a change in magnetism recorded on the recording surface of the optical disk in advance in an MD (Mini Disk), which is a kind of MO (internal synchronization method), whereas the AS-M
In O, a change in shape formed on the recording surface of the optical disk, that is, a discontinuous area of land or groove formed at equal intervals in the track direction (to be described later with reference to FIG. 5)
(External synchronization method).

[0006]

However, although optical discs are diversified in accordance with demands for higher density of information or recording and reproduction of information including video and audio, the structure of each optical disc is described. Since the recording methods are different, for example, AS-MO, M
Information cannot be reproduced from all of the optical disks D, CD, CD-ROM, and DVD. Users can use AS-MO, MD, C
It is very inconvenient to own devices for reproducing D, CD-ROM, DVD, etc., and to select these devices according to each optical disk each time information is reproduced.

The present invention has been made in view of the above problems, and has as its object the purpose of AS-MO and AS-M.
An object of the present invention is to provide a disc discriminating device capable of discriminating an optical disc other than O.

[0008]

In order to solve the above-mentioned problems, a disk discriminating apparatus according to the present invention comprises a laser beam irradiating means for irradiating an optical disk with a laser beam, and a laser beam emitted from the laser beam irradiating means and reflected from the optical disk. Light detecting means for detecting reflected light, signal level determining means for determining a signal level of reflected light from the disk detected by the light detecting means, and detecting a discontinuous synchronization pattern formed in a groove or land of the optical disk To do
A synchronization signal detecting means including a filter for separating high-frequency components and a comparator for binarizing the separated high-frequency components is provided.

Further, in the disc discriminating apparatus of the present invention, the disc type is discriminated based on the signal level of the reflected light by the signal level discriminating means, and the disc type is discriminated by the synchronizing signal detecting means based on the presence or absence of a synchronizing signal. Is determined. Further, the disc discriminating device of the present invention, after performing discrimination of the disc type based on the signal level of the reflected light by the signal level discriminating means, further discriminating the disc type based on the presence or absence of a synchronization signal by the synchronization signal detecting means Is determined.

Further, in the disk discriminating apparatus according to the present invention, after the signal level discriminating means discriminates the magneto-optical disc from other discs based on the signal level of the reflected light, the synchronizing signal detecting means further comprises: A magneto-optical disk having a discontinuous synchronization pattern is distinguished from other magneto-optical disks based on the presence or absence of a synchronization signal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an information recording / reproducing apparatus provided with the disc discriminating apparatus of the present invention. The information recording / reproducing apparatus includes a semiconductor laser for driving semiconductor lasers 291 and 292 (see FIG. 2) for generating a laser beam irradiated on the optical disc 1 rotated by the motor 13 as a part related to the discrimination of the optical disc 1. A drive circuit 6, a reproduction signal amplification circuit 5 for amplifying a signal reproduced from the optical disc 1 into a signal suitable for processing, and a servo mechanism for moving the pickup 2 in the radial direction of the optical disc 1 and tracking the optical disc 1 3, a servo circuit 4 for controlling the servo mechanism 3 based on a signal from the reproduction signal amplification circuit 5, and a TN type liquid crystal for selectively rotating the polarization plane of the laser beam according to the type of the optical disc 1. 262 (see FIG. 2).

Further, the information recording / reproducing apparatus includes a sum signal level discriminating circuit 8 and an external synchronizing signal detecting circuit 9 as parts particularly related to discrimination of the optical disk 1. Each of these control units is constituted by a system controller. Controlled by 10. The sum signal level discriminating circuit 8 discriminates the sum signal detected from the optical disc 1, and the external synchronizing signal detecting circuit 9 detects the external synchronizing signal from the optical disc 1, and these circuits discriminate the type of the optical disc 1. In FIG. 1, the terminals a and b are connected, and the reproduced signal from the reproduced signal amplifier circuit 5 is input to the sum signal level discriminating circuit 8, but the terminals a and b are controlled based on the control by the system controller 10. The terminal c can be connected to input the reproduction signal from the reproduction signal amplification circuit 5 to the external synchronization signal detection circuit 9.

Next, an outline of the structure and operation of the pickup 2 will be described with reference to FIG. 2, and after these descriptions, FIG.
-AS-MO in the external synchronization signal detection circuit 9 using FIG.
The discrimination between MD and MD will be described. FIG. 2 is a diagram showing a schematic configuration of the pickup 2 shown in FIG. The pickup 2 has a wavelength of 780 nm for irradiating the optical disc 1.
Laser 291 that generates a laser beam of wavelength 6 and wavelength 6
Semiconductor laser 292 for generating 35 nm laser beam
And a diffraction grating for diffracting one laser beam generated by the laser beam generation unit 29 into three laser beams each including one main beam and two sub beams. 28, a collimator lens 27 for emitting the incident laser beam as parallel light, and a polarizing film 21 after transmitting the laser beam from the polarization plane rotating unit 26 and reflecting on the signal recording surface 11
And a half mirror 22 for reflecting a laser beam incident through the transparent substrate 12 at right angles to the optical disk 1 via the transparent substrate 12.
An objective lens 20 for converging a laser beam on the signal recording surface 11 of the laser beam, a laser beam polarized in a predetermined direction, a laser beam having only a P-polarized component, a laser beam having only an S-polarized component, and a P-polarized component. It includes a Wollaston prism 23 for separating a laser beam into which an S-polarized component is mixed, and a condenser lens 24 for condensing the laser beam on a photodetector 25. The objective lens 20 is
It is designed for a DVD with a substrate thickness of 0.6 mm, and its numerical aperture is 0.6 (allowable error ± 0.05).

The pickup 2 is composed of glass plates 261 and 263 with transparent electrodes and a TN type liquid crystal 262 for reducing aberration of a laser beam with respect to the transparent substrate 12 having different thicknesses. It includes a polarization plane rotation unit 26 for rotating the polarization plane of the beam, and a polarization film 21 for selectively shielding the outer peripheral portion of the laser beam having a circular cross section according to the polarization plane.

In an information recording / reproducing apparatus using the pickup 2, the sum signal level discriminating circuit 8 and the external synchronizing signal detecting circuit 9 shown in FIG. 1 are used to discriminate the optical disc 1 as described later. , AS-M as follows
Information is reproduced (or recorded) from an optical disc 1 such as O, MD, CD (CD-ROM), CD-R, and DVD.

First, AS-MO, D at the pickup 2
The reproduction of VD will be described. AS-MO with Pickup 2,
When a DVD is reproduced, a semiconductor laser 292 that generates a laser beam with a wavelength of 635 nm is selectively driven,
A voltage is applied to the TN liquid crystal 262 of the polarization plane rotation unit 26. As a result, a laser beam having a wavelength of 635 nm, which is generated by the semiconductor laser 292 and is polarized in a direction perpendicular to the paper surface, is changed into three beams by the diffraction grating 28, is converted into parallel light by the collimator lens 27, and is converted by the polarization plane rotation unit 26. The light passes through the polarization plane as it is without being rotated, and enters the polarization film 21 via the half mirror 22.

The polarizing film 21 is formed only on the outer peripheral portion of the laser beam and has a characteristic of transmitting only a laser beam polarized in a direction perpendicular to the plane of the drawing. Is focused by the objective lens 20 without being shielded by the polarizing film 21, focused on the signal recording surface 11 via the transparent substrate 12, and irradiated.

The laser beam reflected from the signal recording surface 11 returns to the half mirror 22 via the objective lens 20 and the polarizing film 21, is half-reflected by the half mirror 22, and is reflected by the Wollaston prism 23 on the P-polarized component only. , And a laser beam containing only the S-polarized component and a laser beam containing both the P-polarized component and the S-polarized component. The laser beam is condensed by the condenser lens 24 and irradiated on the photodetector 25.

Next, reproduction of an MD by the pickup 2 will be described. When the MD is played on the pickup 2,
The semiconductor laser 291 that generates a laser beam having a wavelength of 780 nm is selectively driven, and no voltage is applied to the TN type liquid crystal 262 of the polarization plane rotation unit 26. As a result, the laser beam having a wavelength of 780 nm, which is generated by the semiconductor laser 291 and is polarized in a direction
The light is converted into a beam, is converted into parallel light by a collimator lens 27, is rotated by 90 degrees in a polarization plane by a polarization plane rotation unit 26, is polarized in a direction perpendicular to the paper surface, and is incident on the polarization film 21 via the half mirror 22.

The polarizing film 21 is formed only on the outer peripheral portion of the laser beam, transmits only the laser beam polarized in the direction perpendicular to the plane of the drawing, and transmits the 780 nm laser beam incident on the polarizing film 21 to the polarizing film. 2
The light is condensed by the objective lens 20 without being shielded by the light 1, is focused on the signal recording surface 11 via the transparent substrate 12, and is irradiated.

The laser beam reflected from the signal recording surface 11 returns to the half mirror 22 via the objective lens 20 and the polarizing film 21, is half-reflected by the half mirror 22, and is reflected only by the Wollaston prism 23 on the P-polarized component. , And a laser beam containing only the S-polarized component and a laser beam containing both the P-polarized component and the S-polarized component. The laser beam is condensed by the condenser lens 24 and irradiated on the photodetector 25.

Next, reproduction of a CD by the pickup 2 will be described. When a CD is reproduced by the pickup 2, the semiconductor laser 292 that generates a laser beam with a wavelength of 635 nm is selectively driven, and no voltage is applied to the TN liquid crystal 262 of the polarization plane rotation unit 26. As a result, a laser beam having a wavelength of 635 nm, which is generated by the semiconductor laser 292 and is polarized in a direction perpendicular to the plane of the drawing, is output from the diffraction grating 28.
Is converted into three beams by a collimator lens 27, is converted into parallel light by a collimator lens 27, is rotated by 90 degrees in a polarization plane by a polarization plane rotation unit 26, is polarized in a direction parallel to the paper surface, and is incident on the polarization film 21 via the half mirror 22. .

The polarizing film 21 is formed only on the outer peripheral portion of the laser beam. The outer peripheral portion of the laser beam polarized in a direction parallel to the paper surface is shielded, only the inner peripheral portion transmits through the polarizing film 21, and The light is condensed by the lens 20, focused on the signal recording surface 11 via the transparent substrate 12, and irradiated. The laser beam reflected from the signal recording surface 11 returns to the half mirror 22 via the objective lens 20 and the polarizing film 21, is half-reflected by the half mirror 22, and is reflected by the Wollaston prism 23 as a laser beam having only a P-polarized component, an S-polarized beam. The laser beam is divided into a laser beam having only the component and a laser beam having a mixture of the P-polarized component and the S-polarized component.

Further, reproduction of a CD-R by the pickup 2 will be described. When a CD-R is reproduced by the pickup 2, the semiconductor laser 291 that generates a laser beam having a wavelength of 780 nm is selectively driven, and a voltage is applied to the TN liquid crystal 262 of the polarization plane rotation unit 26. As a result, the laser beam having a wavelength of 780 nm, which is generated by the semiconductor laser 291 and is polarized in a direction parallel to the plane of the drawing, is output from the diffraction grating 2.
The light is converted into three beams by 8, converted into parallel light by a collimator lens 27, transmitted through the polarization plane rotating unit 26 without rotating the polarization plane, and enters the polarization film 21 via the half mirror 22.

The polarizing film 21 is formed only on the outer peripheral portion of the laser beam. The outer peripheral portion of the laser beam polarized in a direction parallel to the plane of the drawing is shielded, and only the inner peripheral portion transmits through the polarizing film 21 and the objective film is not polarized. The light is condensed by the lens 20, focused on the signal recording surface 11 via the transparent substrate 12, and irradiated. The laser beam reflected from the signal recording surface 11 returns to the half mirror 22 via the objective lens 20 and the polarizing film 21, is half-reflected by the half mirror 22, and is reflected by the Wollaston prism 23 as a laser beam having only a P-polarized component, an S-polarized beam. The laser beam is divided into a laser beam having only the component and a laser beam having a mixture of the P-polarized component and the S-polarized component.

Next, the external synchronization signal detecting circuit 9 shown in FIG.
Will be described. FIG. 3 is a diagram showing a configuration of the external synchronization signal detection circuit 9 shown in FIG. 1, and FIG. 4 is a diagram for explaining a push-pull signal and a sum signal used for discriminating an optical disk. As shown in FIG. 3, the external synchronization signal detection circuit 9 includes a high-pass filter 91 and a comparator 92. The high-pass filter 91 passes only a high-frequency component of a predetermined frequency or higher of the push-pull signal based on the reflected light of the optical disk 1 to the lower comparator 92, and the comparator 92 converts the high-frequency component of the push-pull signal passing through the high-pass filter 91 into a binary signal. Become

A light detecting unit provided in the light detector 25 (see FIG. 2) for detecting a laser beam includes:
As shown in FIG. 4, it is divided into four as A to D.
In each of the four divided portions of the light detection unit, the intensity of light corresponding to the position of the laser beam having a circular cross section is detected, and a change in the shape of the signal recording surface 11 such as pits and wobbles is detected. Here, the intensities of the laser beams detected by the respective parts A to D of the light detection unit are sequentially set to A, B, C, and D in a clockwise direction, a signal generated based on A + B + C + D is set as a sum signal, and (A + C) − A signal generated based on (B + D) is a push-pull signal.

The reflectivity of the laser beam from the optical disk is determined by the AS-M
About 25% for O and MD, 60 for CD and DVD
% To 70% or more, and 10% or less for CD-R. The sum signal is directly affected by the reflectivity of the laser beam from the optical disc, and the difference in the reflectivity is used for CD and DV.
D and AS-MO, and MD and CD-R can be determined. The AS-MO has a discontinuous region where a land and a groove are interrupted to generate a synchronization signal, whereas the MD does not have these discontinuous regions. By detecting an external synchronization signal based on the presence or absence of these discontinuous regions as a push-pull signal, AS-MO and MD can be determined.

The discrimination between the AS-MO and the MD is performed as follows using the external synchronizing signal detecting circuit 9 shown in FIG. First, the AS-MO in the external synchronization signal detection circuit 9
The detection of the external synchronization signal from the push-pull signal based on the reflected light from the device will be described. FIG. 5 is a diagram showing the signal recording surface 11 (see FIG. 2) of the AS-MO irradiated with the laser beam.

In the AS-MO, a land (convex portion) 111 and a groove (concave portion) 1 are formed on a signal recording surface 11 of the optical disc 1.
12 are formed in a spiral shape, discontinuous regions 113, which are rectangular grooves, are periodically formed in the lands, and grooves are not formed in the regions corresponding to the discontinuous regions 113. A continuous region 114 is formed. As shown in FIG. 5, the width of each of the land and the groove is 0.6 μm, and the discontinuous region 113 is formed with respect to a land (groove) having a continuous width of about 118 μm.
The length of the (discontinuous area 114) in the track direction is 0.8 to
0.9 μm.

As described above, the discontinuous area 113 formed on the land (the same applies to the discontinuous area 114 formed on the groove) is obtained by the high-pass filter 91 and the comparator 92 of the external synchronization signal detecting circuit 9 as follows. Is detected. FIG. 6 is a diagram for explaining detection of the external synchronization signal from the push-pull signal based on the AS-MO reflected light in the external synchronization signal detection circuit 9.

The push-pull signal 101 based on the intensity of the reflected light from the signal recording surface 11 of the AS-MO due to the discontinuous region 113 contains a high frequency component. The high-frequency component of the push-pull signal 101 passes through the high-pass filter 91, and the signal 102 output from the high-pass filter 91 and input to the comparator 92 contains a high-frequency component. The signal 102 is input to the comparator 92, and H and L are output corresponding to a voltage higher than a predetermined voltage and a voltage lower than the predetermined voltage in the signal 102, and a binarized signal 103 is generated. An external synchronization signal is generated in response to the rise of the binary signal 103.

Next, generation of a signal in the external synchronization signal detection circuit 9 from a push-pull signal based on the reflected light from the MD will be described. FIG. 7 is a diagram showing the signal recording surface 11 (see FIG. 2) of the MD irradiated with the laser beam. In MD,
Land (groove) on signal recording surface 11 of optical disk 1
A wobble (meandering) 116 is formed on the wall surface of the land 115. As shown in FIG. 7, the length of the wobble in one cycle is 54.4 to 63.5 μm.

The wobble 116 formed as described above
Is not detected by the external synchronization signal detection circuit 9. FIG.
FIG. 3 is a diagram for explaining generation of a signal from a push-pull signal based on reflected light of an MD in an external synchronization signal detection circuit 9. The push-pull signal 104 based on the intensity of the reflected light from the signal recording surface 11 of the MD has no high-frequency component.
From the push-pull signal 104, the high-pass filter 9
1, the signal 105 having no voltage value, and the signal 105
From the signal 10 having no voltage value even in the comparator 92.
6 is generated.

As described above, the signal recording surface 1 of the AS-MO
The binarized signal 103 (see FIG. 6) is generated only by the discontinuous areas 113 and 114 (see FIG. 5) formed on the optical disc 1, and the optical disc 1 is output by the external synchronization signal detection circuit 9 (see FIGS. 1 and 3). Is determined to be AS-MO or MD. In the present information recording / reproducing apparatus, such determination is controlled as described below, whereby the AS-MO, MD, CD (CD-ROM),
AS-MO can be determined from the optical disc 1 such as -R or DVD.

FIG. 9 is a flowchart for explaining the procedure of the processing for discriminating the optical disk performed by the system controller 10 shown in FIG. In the disc discriminating process, first, in S1, a laser beam is focused on a signal recording surface on an optical disc having a transparent substrate having a different thickness as described above. In S2, the sum signal level determination circuit 8 (FIG. 1)
) To determine whether the level of the sum signal detected from the optical disk is high, low, or intermediate. If the sum signal level is high or low (at S2, H
In S3, the optical disk is CD (sum signal level is High), DVD (sum signal level is High) in S3.
h), the disc is determined to be a ROM disc such as a CD-R (sum signal level is Low), and the servo system, signal processing system, ROM circuit, and the like are controlled according to the type of each optical disc.
ROM disk such as D, DVD, CD-R etc.
Information is reproduced (or recorded) as described using
Is done.

If the sum signal level is intermediate between these (Med at S2), the optical disk is determined to be MO at S4, the tracking servo is turned on at S5, and tracking is started. Subsequently, in S6, it is determined whether the optical disk has the external synchronization signal or the internal synchronization signal based on the push-pull signal detected from the optical disk by the external synchronization signal detection circuit 9 (see FIGS. 1 and 3). If the optical disc does not have an external synchronization signal (NO in S6), it is determined that the optical disc has an internal synchronization signal, and in S7, the optical disc is an MO other than AS-MO (including MD).
Is determined. If the optical disk has an external synchronization signal (YES in S6), the optical disk is set to A in S8.
It is determined as S-MO. AS-M determined in this way
O, information is reproduced (or recorded) from other MOs as described above with reference to FIG. After these processes, this routine ends.

As described above, AS-MO, MD, C
AS-MO is determined from an optical disc such as D (CD-ROM), CD-R, or DVD, and information is reproduced (or recorded).

[0039]

As described above, according to the present invention, AS-
An MO and an optical disk other than the AS-MO can be distinguished.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a configuration of a device of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a pickup 2 shown in FIG.

FIG. 3 is a diagram showing a configuration of an external synchronization signal detection circuit 9 shown in FIG.

FIG. 4 is a diagram for explaining a push-pull signal and a sum signal used for discriminating an optical disc.

FIG. 5 is a diagram showing a signal recording surface 11 (see FIG. 2) of an AS-MO irradiated with a laser beam.

FIG. 6 is a diagram for explaining detection of an external synchronization signal from a push-pull signal based on reflected light of an AS-MO in the external synchronization signal detection circuit 9;

FIG. 7 is a signal recording surface 1 of an MD irradiated with a laser beam.
1 (see FIG. 2).

8 is a diagram for explaining generation of a signal from a push-pull signal based on reflected light of an MD in an external synchronization signal detection circuit 9. FIG.

FIG. 9 is a flowchart illustrating a procedure of a process of determining an optical disc performed by the system controller shown in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Pickup 3 Servo mechanism 4 Servo circuit 5 Reproduction signal amplification circuit 6 Semiconductor laser drive circuit 7 Liquid crystal drive circuit 8 Sum signal level discrimination circuit 9 External synchronization signal detection circuit 10 System controller 11 Signal recording surface 12 Transparent substrate 20 Objective lens 21 Polarizing film 22 Half mirror 23 Wollaston prism 24 Condensing lens 25 Photodetector 26 Polarization plane rotating unit 27 Collimator lens 28 Diffraction grating 29 Laser beam generating unit 91 High-pass filter 92 Comparator 111 Land formed on AS-MO 112 AS- Groove formed in MO 113 Discontinuous region formed in land 114 Discontinuous region formed in groove 115 Land (groove) formed in MD 116 Wobble 291 formed in MD wavelength 780 laser generating a laser beam with a wavelength of 292 nm 292 A semiconductor laser generating a laser beam with a wavelength of 635 nm

Claims (4)

(57) [Claims] 1. An optical disk is irradiated with a laser beam.
A laser beam irradiating means, and an optical disk emitted from the laser beam irradiating means
Light detecting means for detecting the reflected light reflected from the optical disc, and a signal level of the reflected light from the disk detected by the light detecting means.
A signal level discriminating means for discriminating the bell, which is formed on the groove or land of the optical disc
Separates high frequency components to detect discontinuous sync patterns
Filter and binarize the separated high-frequency components
And a synchronizing signal detecting means including a comparator.
And a disk discriminating device. 2. The light reflected by said signal level discriminating means.
Disc type discrimination based on the signal level of
The synchronization signal detecting means determines whether the synchronization signal exists or not.
Determining the type of disc to be used
Item 10. The disk discriminating apparatus according to Item 1. 3. The light reflected by said signal level discriminating means.
Disc type based on the signal level of the disc
Thereafter, the synchronization signal detecting means further detects the synchronization signal.
Discriminating the type of disc based on the presence or absence
3. The disc discriminating apparatus according to claim 1, wherein 4. The apparatus according to claim 1, wherein said signal level discriminating means detects reflected light.
Magneto-optical and other disks based on signal level
After the discrimination of the synchronization signal,
Has a discontinuous synchronization pattern based on the presence or absence of a synchronization signal
Discriminating magneto-optical disks from other magneto-optical disks
4. The disk according to claim 1, wherein
Identifier.