JPH09153252A - Identifying device for optical recording medium or method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify an optical disk simply and with a high reliability by providing a light shielding plate in a light path of a reflection beam of an optical disk. SOLUTION: When a 0.6mm thick optical disk is mounted, a recording surface 5 positioned at a distance of approximately 0.6mm from a base surface is irradiated with a light beam emitted from a LED 1 through a condensing lens 2 with an incident angle θ1, and the recording surface 5 reflects the light with a same angle as the incident angle θ1, and is detected by a photodetector 3. On the other hand, when a 1.2mm thick base plate is mounted, a light beam emitted from the LED 1 passes through a lens 2 and emitted onto a recording surface 6 positioned at a distance of 1.2mm from the base surface with an incident angle θ2 and is reflected by a recording surface 6 with the same an angle as the incident angle θ2. This reflected light beam is partly shielded by a shielding plate 4 and the remainder of the beam is detected by the photodetector 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of discriminating a plurality of types of optical discs having different substrate thickness and reflectance.

[0002]

2. Description of the Related Art An optical disk having a thickness of about 1.2 mm, such as a CD-ROM, from which information is read using a semiconductor laser is provided. In this type of optical disk, focus servo and tracking servo are performed on a pickup objective lens to irradiate a pit row on a signal recording surface with a laser beam to reproduce a signal. In addition, recently, high density recording for recording a moving image for a long time is progressing.

[0003] For example, the same 12 cm diameter as a CD-ROM
An SD standard for recording about 5 Gbytes of information on one side of an optical disc has been proposed. The SD disc has a thickness of about 0.6 mm, and by laminating the discs, information of about 10 Gbytes can be recorded by one disc. In addition, if about 10 Gbyte is not needed for one sheet, only one substrate with a thickness of 0.6 mm is used for recording, and the other 0.6 mm thickness is used as a reinforcement without recording. A combined type of optical disc is also conceivable. Therefore, in terms of reproducing an optical disk, an optical pickup capable of compatible reproduction of optical disks having different substrate thicknesses is required.

Japanese Patent Laid-Open Publication No. Hei 5-303766 discloses a high-density optical disk having a thin substrate having a thickness of 0.6 mm and a standard-density optical disk having a standard substrate having a thickness of 1.2 mm. An apparatus has been proposed that enables reproduction by one optical pickup. This technique uses an objective lens with a numerical aperture of 0.6 designed to reproduce a high-density disc with a short-wavelength laser beam, and when reproducing an optical disc of standard thickness and standard density, laser is used as an aberration correction means. This is a device in which an outer peripheral side of the beam is shielded and an aperture for reducing the effective numerical aperture is added to the light source side of the objective lens.

In order to reproduce SD and CD with a single pickup, it is important to first identify the type of optical disk set in the reproducing device. As a technique of this kind, there is a method disclosed in JP-A-6-259804. That is, this method is a method in which the optical disc is irradiated with light using an optical pickup and the optical disc is identified by detecting the difference in the detection position of the reflected light from the optical disc.

[0006]

Problems to be Solved by the Invention JP-A-6-25980
In the technique disclosed in Japanese Patent Publication No. 4, the optical pickup must be started up and the optical disc must be reproduced once, so that the optical disc cannot be easily identified. In addition, since the optical disc cannot be identified until the optical disc is reproduced once and the focus servo is performed, and if the optical disc substrate is warped, the focus servo requires time. It takes time.

The present invention solves the above problems and is simple,
It is intended to provide a highly reliable optical disc identification method.

[0008]

According to the present invention, there is provided a light emitting source for obliquely irradiating a beam on a recording surface of an optical recording medium having a standard or thin substrate, and a collector for converging a beam emitted from the light source. An optical lens and a photodetector for detecting a reflected beam reflected by an optical recording medium having a different substrate thickness;
An optical intensity reducing means for reducing the intensity of the reflected beam from the optical recording medium having one substrate thickness is provided in the optical path of the reflected beam.

Further, according to the present invention, a light emitting source for obliquely irradiating a recording surface of an optical recording medium having a standard or thin substrate with a beam in two directions and a beam emitted from the light source in two directions are condensed. Detecting the two reflected beams reflected by the condensing lens and the optical recording medium having different substrate thicknesses 2
One photodetector and an optical intensity reducing means for reducing the intensities of the two reflected beams are provided in the optical path of the reflected beams from the optical recording medium having one substrate thickness.

Further, the present invention is characterized in that the light emitting source is an LED. Further, the invention is characterized in that the light emitting source is an LED or a semiconductor laser. Further, the present invention is characterized in that the optical intensity reducing means is installed in the photodetector. Further, the invention is characterized in that the optical intensity reducing means is a light shielding plate which shields a part of the reflected beam.

In the present invention, the optical intensity reducing means is N
It is a D filter. Also, the present invention
It is characterized in that it is possible to identify optical recording media having different reflectances. In addition, the present invention is 0.55-0.6.
An optical recording medium having a substrate thickness of 5 mm and 1.1 to 1.
It is characterized by being able to distinguish from an optical recording medium having a substrate thickness of 3 mm.

In the present invention, the substrate thickness is 1.1 to 1.3 m.
m, an optical recording medium having a reflectance of 70% or more, and a substrate thickness of 0.55 to 0.65 mm, and 20 to 20.
It is characterized in that it can distinguish from an optical recording medium having a reflectance of 40% or 70% or more. The present invention also provides an optical recording medium having a substrate thickness of 1.1 to 1.3 mm and a reflectance of 70% or more, and a substrate thickness of 0.55 to 0.55.
The optical recording medium is 0.65 mm, and can be distinguished from an optical recording medium having a reflectance of 20 to 40%.

Further, according to the present invention, the substrate has a thickness of 0.55 to 0.6.
It is characterized by being able to distinguish between two optical recording media having a reflectance of 70% or more, which is 5 mm or 1.1 to 1.3 mm. Further, the present invention is characterized in that the optical intensity reducing means is provided in the optical path of the reflected beam from the optical recording medium having the thin substrate.

Further, the present invention is characterized in that an optical recording medium identification device and a compatible pickup capable of reproducing optical recording media having different substrate thicknesses are arranged. Further, the present invention is characterized by including an optical recording medium identification device and two pickups capable of reproducing optical recording media having different substrate thicknesses according to the substrate thickness.

The present invention is also characterized in that the photodetector detects different reflected beam intensities.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to identification of a plurality of optical discs having different substrate thicknesses and reflectances from recording surfaces. FIG. 1 shows the substrate thickness and reflectance for a CD, SD for single-sided recording, and SD for double-sided recording / single-sided reading. There are three types of target optical discs depending on the difference in substrate thickness and reflectance. First Embodiment Therefore, discrimination between a CD and a single-sided recording SD will be described with reference to the drawings. In this case, the reflectance from the recording surface is 70% or more for both discs, and the substrate thickness is 0.6.
mm and 1.2 mm. FIG. 2 shows C in the present invention.
It is a schematic diagram which shows the principle of discrimination of D and SD of single-sided recording.

First, 0.6 (tolerance: ± 0.05) mm
The operation when a thick optical disc is loaded will be described. The beam emitted from the LED 1, which is a light emitting source, passes through the condenser lens 2 and is applied to the recording surface 5 located at a position of about 0.6 mm from the substrate surface at an incident angle θ1. It is reflected at the same angle. The beam reflected by the recording surface 5 is detected by the photodetector 3. in this case,
The condenser lens 2 is designed so that the beam reflected by the recording surface 5 is focused on the photodetector 3.

On the other hand, the substrate thickness is 1.2 (permissible error: ± 0.
1) When an optical disc of mm is mounted, the substrate thickness is 0.1.
As with a 6mm thick optical disc, LE
The beam emitted from D1 passes through the condenser lens 2 and is incident on the recording surface 6 at a position of about 1.2 mm from the substrate surface with an incident angle θ.
2 and is reflected by the recording surface 6 at the same angle as the incident angle θ2. The beam reflected by the recording surface 6 is detected by the photodetector 3, and a part of the reflected beam is detected by the light shielding plate 4 provided between the recording surface 6 and the photodetector 3. Is shielded, and the remaining beam is detected by the photodetector 3. Therefore, the substrate thickness is about 1.2 mm
In the case of the optical disc of No. 3, the intensity of the reflected beam detected is weaker than that of the optical disc having the substrate thickness of about 0.6 mm, and therefore the optical disc mounted can be identified by the detected beam intensity. In the case of an optical disc having a substrate thickness of about 1.2 mm, a part of the beam reflected by the recording surface 6 is shielded because if all the light is shielded, it is not mounted on the optical disc. This makes it impossible to identify

The light-shielding plate 4 need only be located between the recording surface 5 or the recording surface 6 and the photodetector 3, and is not limited to the position shown in FIG. That is, as shown in FIG. 3, the photodetector 3 may be installed so as to block only a part of the beam reflected by the recording surface 6. Further, although the light shielding plate 4 is installed in the optical path of the reflected beam from the optical disc having the substrate thickness of 1.2 mm, the present invention is not limited to this, and the reflected beam from the optical disc having the substrate thickness of 0.6 mm is not limited to this. It may be installed in the optical path.

2 and 3, the substrate thickness is 1.2 m.
The reflected beam intensity was changed by blocking a part of the reflected beam from the recording surface 6 of the m optical disc. However, the present invention is not limited to this, and a filter having a certain transmittance for the entire reflected beam may be used. The intensity of the reflected beam can also be changed by passing it. That is, as shown in FIG. 4, by installing an ND filter in the optical path of the reflected beam from the recording surface 6 of the optical disc having a substrate thickness of 1.2 mm, the intensity of the reflected beam from the optical disc having a substrate thickness of 1.2 mm can be increased. The recording surface 5 of the optical disk having a thickness of 0.6 mm
Can be lower than the reflected beam intensity from the optical disc, and as a result, both optical disks can be distinguished. Second Embodiment Next, discrimination between a CD and an SD for double-sided recording / single-sided reading will be described. In this case, the substrate thickness and reflectance are different,
SD reflectance of double-sided recording / single-sided reading is 20 to 30% and C
Lower than D. Therefore, the configuration shown in FIG. 5 is used in order to identify both optical discs more accurately. That is, in FIG. 5, the light shielding plate 4 is installed in the optical path of the reflected beam from the recording surface 5 of the optical disc having a substrate thickness of 0.6 mm.
By adopting this configuration, the difference in the intensities of the reflected beams from both optical disks becomes large, and it becomes possible to surely identify. The light shield plate may be provided between the recording surface 5 and the photodetector 3, and may be installed on the surface of the photodetector.

Also in this embodiment, the method of blocking a part of the reflected beam from the recording surface 5 is not limited, and the ND is included in the optical path of the reflected beam from the recording surface 5 as shown in FIG. A configuration provided with a filter may be adopted.
Also in this embodiment, the same configuration as that of FIGS. 2, 3 and 4 is used, in which the light shielding plate or the ND filter is installed in the optical path of the reflected beam from the optical disk having the substrate thickness of 1.2 mm. Can also identify both optical disks. In this case, the light shielding plate or the ND filter is designed so that the reflected beam intensity after being shielded or reduced by the light shielding plate or the ND filter is 50 to 60%. Third Embodiment A discriminating method in the case of targeting three types of optical discs of CD, double-sided recording / single-sided reading SD, and single-sided recording SD will be described. In this case, the reflectance from the recording surface 5 of the optical disc having a substrate thickness of 0.6 mm is 20 to 40% and 70%.
Since the above cases are considered, by adopting the configuration in which the light shielding plate or the ND filter 4 is installed in the optical path of the reflected beam from the optical disc having the substrate thickness of 0.6 mm, that is, the configuration of FIG. 5 or 6 is adopted. Three types of optical disks can be identified.

Also in this embodiment, the installation of the light shielding plate or the ND filter is not limited to the optical path of the reflected beam from the optical disk having the substrate thickness of 1.2 mm, and the substrate thickness of 0.6 mm is used. You may install in the optical path from an optical disk. Also in this case, as in the second embodiment,
The light shielding plate or the ND filter is designed such that the reflected beam intensity after being shielded or reduced by the light shielding plate or the ND filter is 50 to 60%.

In the first, second and third embodiments described above, the light emitting source 1 is not limited to the LED and may be a semiconductor laser. Fourth Embodiment In the above first to fourth embodiments, the beam intensity from the optical disk is detected by one photodetector. But,
Since an actual optical disc may be warped when the substrate is molded, in this case, the optical disc may not be accurately identified by the above method. Therefore, FIG. 8 shows a method of accurately identifying an optical disk even when warpage occurs. According to the identification principle shown in FIG. 8, the beam emitted from the light emitting source 1 is irradiated onto the optical disc from two directions via a condenser lens 22 in which two objective lenses are connected,
It is reflected by the recording surface 5 of the optical disc having a substrate thickness of 0.6 mm,
It is detected by the photodetectors 3 and 33, respectively. In this case, when the substrate is warped, the beam intensities detected by the photodetector 3 and the photodetector 33 are different, so the optical disc is identified when the beam intensities detected by the two photodetectors are the same. To do so. Further, when the substrate thickness is 1.2 mm, the beam is reflected by the recording surface 6, so that the same light-shielding plate or ND as shown in the first to third embodiments is provided in the optical path of the reflected beam. Filters 4 and 44 are provided.
As a result, since the beam intensities detected by the photodetectors 3 and 33 are different between the optical discs having the substrate thicknesses of about 0.6 mm and about 1.2 mm, both optical discs can be identified. In this embodiment, the light emitting source 1 has to emit light in two directions and is therefore limited to an LED.

Further, the light shielding plate or the ND filter 4
The numbers 44 and 44 are not limited to being provided between the optical disc and the photodetectors 3 and 33, and may be installed in the photodetectors 3 and 33. Further, also in this embodiment, the installation of the light shielding plate or the ND filter has a substrate thickness of 1.2.
It is not limited to the optical path of the reflected beam from the optical disc of mm, and may be installed in the optical path of the optical disc having the substrate thickness of 0.6 mm. Also in this case, as in the second and third embodiments, the reflected beam intensity after being shielded or reduced by the light shielding plate or the ND filter is 50 to 6
The light shielding plate or the ND filter is designed to be 0%. Fifth Embodiment After discriminating optical discs having different substrate thicknesses and reflectances by the method described in the first, second, third and fourth embodiments, it is necessary to perform reproduction according to each optical disc.

FIG. 7 shows a block diagram of a reproducing apparatus for identifying an optical disk and reproducing according to the identified optical disk. The operation from identification to reproduction will be described below. When the optical disc 10 is loaded, the photodetector 3 detects the reflectance according to the loaded optical disc by the method described in the above embodiment. The reflectance detected by the photodetector 3 is sent to the signal converter 17 and converted into a voltage value. Then, the converted voltage value is sent to the comparator 16 and compared with a predetermined set value. The result of the comparison is sent to the controller 15, and the controller 15 uses the comparison result to pick up the drive circuit 14 and the motor drive circuit 13.
Is controlled to rotate the motor 11 at a predetermined number of rotations, the optical pickup 12 is activated so that the mounted optical disk can be reproduced, and reproduction is performed according to the identified optical disk. Here, the optical pickup 12 has a substrate thickness of about 0.1.
It is a compatible pickup that can reproduce 6mm and 1.2mm optical discs, and its mechanism is to switch the objective lens with different thickness according to the substrate thickness or to switch the effective numerical aperture (NA) according to the substrate thickness. The method is adopted.

In the fifth embodiment, the reproducing apparatus using one pickup is shown, but the present invention is not limited to this, and the reproducing is performed using the optical pickup corresponding to the optical disc of each substrate thickness. It may be a playback device.

[0027]

According to the present invention, the optical disc can be easily identified without starting the optical pickup and reproducing the optical disc. Further, according to the present invention, it is possible to identify optical disks having different substrate thicknesses and reflectances. Also, according to the present invention,
It is possible to identify a plurality of optical discs and perform reproduction with one optical pickup according to the identified optical discs.

Further, according to the present invention, the optical disc can be accurately identified even if the substrate has a warp.

[Brief description of the drawings]

FIG. 1 shows physical constants of various optical disks.

FIG. 2 is a schematic diagram showing the principle of optical disc identification in the first embodiment.

FIG. 3 is a schematic diagram showing the principle of optical disc identification in the first embodiment.

FIG. 4 is a schematic diagram showing the principle of optical disc identification in the first embodiment.

FIG. 5 is a schematic diagram showing the principle of optical disc identification in the second and third embodiments.

FIG. 6 is a schematic diagram showing the principle of optical disc identification in the second and third embodiments.

FIG. 7 is a block diagram of a reproducing apparatus capable of compatible reproduction of a plurality of optical disks according to the present invention.

FIG. 8 is a schematic diagram showing the principle of optical disc identification in the fourth embodiment.

[Explanation of symbols]

 1 ... LED 2 ... Condensing lens 3 ... Photodetector 4 ... Light-shielding plate or ND filter 5, 6 ... Recording surface 10 ... Optical disk 11 ... Motor 12 ... Optical pickup 13 ... Motor drive circuit 14 ... Pickup drive circuit 15 ... Controller 16 ... Comparator 17 ... Signal converter

Claims (16)

[Claims] 1. A light emitting source for obliquely irradiating a beam onto a recording surface of an optical recording medium having a standard or thin substrate, a condenser lens for condensing a beam emitted from the light source, and the substrate thickness. , A photodetector for detecting a reflected beam reflected by different optical recording media, and an optical intensity reducing means for reducing the intensity of the reflected beam in the optical path of the reflected beam from the optical recording medium having one substrate thickness An apparatus for identifying an optical recording medium, comprising: 2. A light emitting source for obliquely irradiating a recording surface of an optical recording medium having a standard or thin substrate with a beam in two directions, and a light condensing light for converging a beam emitted from the light source in two directions. Reflected by a lens and an optical recording medium having a different substrate thickness 2
Providing two photodetectors for detecting one reflected beam and optical intensity reducing means for reducing the intensity of the two reflected beams in the optical path of the reflected beams from the optical recording medium having one substrate thickness. A characteristic optical recording medium identification device. 3. The optical recording medium identification device according to claim 2, wherein the light emitting source is an LED. 4. The apparatus for identifying an optical recording medium according to claim 1, wherein the light emitting source is an LED or a semiconductor laser. 5. The apparatus for identifying an optical recording medium according to claim 1, wherein the optical intensity reducing means is installed in the photodetector. 6. The optical recording medium identification device according to claim 1, wherein the optical intensity reducing unit is a light blocking plate that blocks a part of the reflected beam. 7. The optical recording medium identification device according to claim 1, wherein the optical intensity reducing means is an ND filter. 8. The optical recording medium identification device according to claim 1, wherein the optical recording mediums having different reflectances can be identified. 9. The optical recording medium according to claim 1, wherein the optical recording medium having a substrate thickness of 0.55 to 0.65 mm and the optical recording medium having a substrate thickness of 1.1 to 1.3 mm are identified. An apparatus for identifying an optical recording medium, which is characterized by being capable of. 10. The optical recording medium according to claim 8, wherein the substrate thickness is 1.1 to 1.3 mm and has a reflectance of 70% or more, and the substrate thickness is 0.55 to 0.65 mm. And 20-40%
Alternatively, an optical recording medium identification device characterized by being able to identify an optical recording medium having a reflectance of 70% or more. 11. The optical recording medium according to claim 8, wherein the substrate thickness is 1.1 to 1.3 mm and has a reflectance of 70% or more, and the substrate thickness is 0.55 to 0.65 mm. And 20-40%
An optical recording medium discriminating apparatus, which is capable of discriminating between an optical recording medium having a reflectance of 1. 12. The substrate thickness according to claim 8 or 9, wherein the substrate thickness is 0.55 to 0.65 mm or 1.1 to 1.3 m.
An optical recording medium identification device, characterized in that it can identify two optical recording media having a reflectance of 70% or more. 13. The optical recording medium according to claim 11 or 12, wherein the optical intensity reducing means is provided in an optical path of a reflected beam from the optical recording medium having the thin substrate. Identification device. 14. The method of claim 1, 2, 3, 4, 5, 6, 7,
An optical recording device comprising: an optical recording medium identification device described in 8, 9, 10, 11, 12 or 13 and a compatible pickup capable of reproducing optical recording media having different substrate thicknesses. Media playback device. 15. The method of claim 1, 2, 3, 4, 5, 6, 7,
An optical recording medium identification device according to 8, 9, 10, 11, 12 or 13 and two pickups capable of reproducing optical recording media having different substrate thicknesses according to the substrate thickness. A reproducing apparatus for a characteristic optical recording medium. 16. The method for identifying an optical recording medium according to claim 1, wherein the photodetector detects different reflected beam intensities.