JPH0935401A - Optical disc drive and method for discriminating optical disc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disc drive in which a data can be read out from various an optical discs by detecting a returning light through a translucent disc board and discriminating the difference in the thickness of the boards. SOLUTION: The data recording faces 122, 133, 222 of optical discs D1, D2, D3 being turned through a drive section are irradiated with a light emitted from a light emitting section 32 through translucent disc boards. Returning lights L2 are then detected at light receiving sections 33, 34 and the difference in the thickness of translucent disc boards is determined. Based on the output signals SR2, SR1 from a photodetector 30, the type of optical disc D1, D2, D3 is determined at a discriminating section 20 and then the position of optical pickup is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reads a signal on a data recording surface by irradiating light on an optical disc on which not only audio information but also video information is digitally compressed and recorded, and detecting the returning light. And an optical disc discriminating method for discriminating the disc type.

[0002]

2. Description of the Related Art Recently, an optical disc having a diameter of 12 cm has been developed in which not only audio information but also video information is digitized and data is compressed. This optical disc is the same size as a conventional compact disc (CD).
Such an optical disc is particularly called a digital video disc (hereinafter referred to as DVD). In an optical disk reproducing apparatus for reproducing a DVD of this type, a rotating DVD is irradiated with light from an optical pickup. This light is applied to the data recording surface of the DVD,
The returned light is detected by the light receiving section of the optical pickup.
The light receiving unit reads the signal on the data recording surface recorded on the DVD to generate a signal of audio information or video information.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
D is a mixture of two or more standards. For example, one type of DVD has only one side as a data recording side, and another type of DVD has both sides as a data recording side. Such different types of DVDs have different disc thicknesses, and each data recording surface is protected by a transparent disc substrate. However, the substrate thickness of the translucent disc of one type of DVD is different from the substrate thickness of the translucent disc of another type of DVD. Therefore, DVD
If the type is different, from the objective lens of the optical pickup to D
Since the distance to the data recording surface of the VD changes, it is necessary to correct the distance between the objective lens and the data recording surface.

In an apparatus for reproducing many kinds of optical disks that are usually used, the thickness of the optical disk has not changed significantly. Therefore, the correction of the distance between the objective lens and the data recording surface is simply performed by the objective of the optical pickup. This was done by operating a biaxial actuator that drives the lens. But,
Different types of DVDs have different disc thicknesses, that is, substrate thicknesses of translucent discs. Therefore, simply operating the biaxial actuator of the optical pickup makes the objective lens and the data recording surface of the DVD. It is difficult to correct the difference in the distance to. In addition, since the thickness of the transparent substrate of an optical disc such as a compact disc which is usually used may be greatly different from the thickness of the transparent substrate of a DVD of a certain type, the thickness of this ordinary substrate is also large. Compact disc and some kind of DVD
In order to reproduce, it is necessary to largely correct the distance between the objective lens and the data recording surface. Therefore, the present invention has been made to solve the above problems, and reproduces data of various optical discs by detecting the difference in thickness between different types of optical discs and the substrate thickness of translucent discs. It is an object of the present invention to provide an optical disc reproducing apparatus and an optical disc discriminating method capable of performing the above.

[0005]

According to the present invention, the above object is to provide a drive unit for rotating an optical disc on which data is compressed and recorded and a data recording surface of the optical disc rotated by the drive unit. By irradiating light through the substrate of the optical disc and detecting return light through the substrate of the transparent disc, the optical pickup for reading the signal of the data recording surface and the data recording surface of the optical disc are detected. , A light detection unit for detecting a difference in thickness of the substrate of the transparent disc by irradiating light through the substrate of the transparent disc and detecting return light through the substrate of the transparent disc. And a discriminating unit for discriminating the type of the optical disc on the basis of the signal from the light detecting unit. Further, according to the present invention, according to the present invention, the light emitting unit of the light detecting unit irradiates light onto the data recording surface of the optical disc on which data is compressed and recorded, through the substrate of the translucent disc. The light receiving unit of the light detecting unit detects the return light that has passed through the substrate of the light transmitting disc, thereby detecting the difference in the thickness of the substrate of the light transmitting disc, and based on the signal of the light detecting unit. This is achieved by the discriminating method of the optical disc.

According to the above structure, the photodetector detects the thickness of the base branch of the translucent disc, and the discriminating unit discriminates the type of the optical disc based on the signal from the photodetector.

[0007]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limitations are given, the scope of the present invention is not limited to these modes unless otherwise specified to limit the present invention. FIG. 1 shows a preferred embodiment of the optical disk reproducing apparatus of the present invention. In FIG. 1, the optical disk reproducing apparatus is, for example, a DVD (digital video disk).
An optical disc called "ordinary compact disc (CD)" or the like is discriminated and reproduced. The optical disk reproducing device includes a chuck unit 10, a spindle motor 12, an optical pickup 13, and a signal processing circuit 1.
4, a system controller 16, a driver 17, a photodetector 30 and the like. The chuck portion 10 is a portion for removably chucking the optical disc D to the turntable 11 attached to the output shaft of the spindle motor 12. The spindle motor 12 rotates the optical disc D detachably mounted on the turntable 11 at a predetermined speed. The spindle motor 12 operates the driver 17 based on the control signal SS from the system controller 16, and is driven by the drive signal DS of the driver 17.

The optical pickup 13 has a light source 13a, a biaxial actuator 13c, a photodetector 13b and a slide base 13d. The light source 13a is, for example, a laser light source. The light beam of the light source 13a is focused on the data recording surface of the optical disk D via the objective lens 21 of the biaxial actuator 13c. Return light from the data recording surface of the optical disc D is received by the photodetector 13b via the objective lens 21. The slide base 13d holds the light source 13a and the photodetector 13b, and also holds the fixed portion (not shown) of the biaxial actuator 13c. The movable portion 13e of the biaxial actuator 13c includes the objective lens 21 and the electromagnetic drive portion 2 described above.
Holds 2. The electromagnetic drive unit 22 can move the objective lens 21 in the focus direction Fcs and the tracking direction Trk by applying a drive current from the outside, and thereby the light L that has passed through the objective lens 21 can be transmitted. It is possible to irradiate the correct position on the data recording surface.

A photodetector 30 is arranged on the slide base 13d. That is, the photodetector 30 is provided integrally with the slide base 13d. As shown in FIG. 2, the photodetector 30 includes a base 31, a light emitting portion 32 and light receiving portions 33, 34 provided on the base 31,
It also has a parallel light generation lens 35. Light emitting unit 3
2, a light emitting diode (LED) is used, for example, and the forward light L1 of the light emitting unit 32 irradiates the data recording surface DR of the optical disc D. The data recording surface DR is a disc reflecting surface. The return light L2 reflected by the data recording surface DR is collimated light generation lens 3
The light is incident on the light-receiving portion 33 or the light-receiving portion 34 via 5 depending on the thickness of the substrate of the transparent disc. In the example of FIG. 2, the forward light L1 and the return light L for two types of optical discs are used.
The two optical paths are shown.

The light emitting unit 32 is the system controller 16
Light is emitted based on the drive signal S1 from the. Light receiving portion 33,
Upon receiving the return light L, the system controller 1
The light receiving signal SR1 or SR2 is sent to the discriminator 20 of FIG. The discriminator 20 determines the received light signal S
By comparing the sizes of R1 and SR2, it is possible to detect the difference in the thickness of the transparent disc substrate of the optical disc. The signal processing circuit 14 of FIG. 1 generates audio data and / or video data recorded on the data recording surface of the optical disc D by being digitized and data-compressed based on the light detection signal SD of the optical pickup 13. Output to an external device such as a display (not shown). The signal processing circuit 14 is based on a control signal from the system controller 16 and uses a method according to the type of the optical disc D to be reproduced.
The audio data and / or video data of the optical disc D is reproduced.

Next, with reference to FIGS. 3 to 5, examples of different types of optical disks to be reproduced by the optical disk reproducing apparatus of FIG. 1 will be described. 3 and 4 show two types of digital video disc (DVD) systems. FIG. 3 shows a so-called single-sided recording type DVD.
Is a double-sided recording type DVD.

In FIG. 3, a single-sided recording type DVDD1
Is, for example, on one surface of the substrate 121 of the transparent disc made of polycarbonate (PC) by a stamper,
A pit representing data to be recorded is formed, and a first semi-transmissive reflective film 122 made of a semi-transparent dielectric film is formed on the pit by sputtering. And the first
The ultraviolet curable resin 123 is poured onto the reflective film 122 of 1. and the ultraviolet rays are irradiated while pressing the stamper against the surface of the ultraviolet curable resin 123. As a result, the ultraviolet curable resin 123 is cured, and the second reflective film 124 of aluminum or the like is formed on the ultraviolet curable resin 123 by sputtering. By forming a protective film 125 made of an ultraviolet curable resin on the second reflective film 124, the DVDD shown in FIG.
1 is made. A label 126 indicating the recorded content is printed on the surface of the protective film 125. The first reflection film 122 and the second reflection film 124 are formed on the data recording surface D.
It is equivalent to F1.

Next, the double-sided recording type DVDD2 shown in FIG.
A pit representing data to be recorded is formed by a stamper on each surface of the substrates 131 and 132 of one translucent disk. Then, a reflective film 1 made of aluminum or the like is sputtered from above each pit.
33 and 134 are formed. Protective films 135 and 136 made of an ultraviolet curable resin are formed on the reflective films 133 and 134, respectively, and are used as the translucent disk substrate 13.
1, 132 are bonded by an adhesive layer 137 so that the protective films 135, 136 face each other. The reflection films 133 and 134 are the data recording surface DF2.

FIG. 5 shows an example of an ordinary compact disc (CD) as another type of optical disc. The compact disc D3 of FIG. 5 has, for example, a pit representing data to be recorded by a stamper on one surface of a substrate 221 of a translucent disc made of polycarbonate (PC), and a reflective film is formed thereon by sputtering. Two
22 is formed. A protective film 225 is formed on the reflective film 222. The reflective film 222 is the data recording surface DF3. The thickness R1 of the transparent disc substrate 121 of the optical disc D1 of FIG. 3 and the thickness R1 of the transparent disc substrate 221 of the compact disc D3 of FIG.
Is set to, for example, 1.2 mm. On the other hand, the transparent disc substrate 1 of the optical disc D2 of FIG.
The thickness R2 of 31, 132 is set to, for example, 0.6 mm.

When one of the different optical disks D1 to D3 as shown in FIGS. 3 to 5 is reproduced by the optical disk reproducing apparatus of FIG. 1, a translucent disk substrate 121,
By determining the thickness R1 of 221 and the thickness R2 of the substrates 131 and 132 of the translucent disc of FIG. 4 different from this thickness R1, the distance between the objective lens 21 of FIG. 1 and the data recording surface of the optical disc is determined. It needs to be corrected.

Therefore, the system controller 16 of FIG.
Is connected to the drive current supply unit 60. The drive current supply unit 60 can correct the position of the objective lens 21 by moving the position of the objective lens 21 along the focus direction Fcs by supplying a predetermined current to the electromagnetic drive unit 22, for example. As a result, the objective lens 21 is used as the substrate 1 of the transparent disc of FIG. 3 corresponding to the data recording surface of the DVDD 1.
21 thickness R1 or the compact disc D of FIG.
Positioning is performed corresponding to the thickness R1 of the substrate 221 of the translucent disk of No. 3, and the objective lens 21 is the DVDD2 of FIG.
It is possible to perform positioning in accordance with the thickness R2 of the substrate 131 of the translucent disk.

Next, with reference to FIGS. 1 to 5, a method of determining the type of the optical disc and a method of setting the distance between the objective lens and the data recording surface of the optical disc based on the determination will be described. The optical disc D of FIG. 1 is attached to the turntable 11. It is assumed that this optical disc D is, for example, a DVD D1 of a kind shown in FIG. The system controller 16 sends a drive signal S1 to the light emitting section 32 of the photodetector 30 shown in FIG. The light emitting unit 32 is the forward light L1.
Through the parallel light generating lens 35
The reflective surface 122 is irradiated. And the first reflecting surface 122
The return light L2 from is incident on the light receiving unit 34 via the parallel light generating lens 35 as shown by the broken line in FIG. As a result, the light receiving unit 34 sends the light receiving signal SR2 to the determination unit 20.

However, the other light receiving section 33 does not send the light receiving signal S1. Thus, the determination unit 20 determines that the DVDD1 of FIG. 3 is chucked by the turntable 11 of FIG. 1 based on the light reception signal S2. When the determination unit 20 makes such determination, the system controller 16 gives a drive signal to the drive current supply unit 60 of FIG. 1, and the drive current supply unit 60 gives a current to the electromagnetic drive unit 22. As a result, the objective lens 21 and the first reflection film 1 of FIG. 3 correspond to the thickness R1 of the substrate 121 of the transparent disc of FIG.
The distance from 22 can be set.

When the DVDD1 of FIG. 3 is not set to the turntable 11 of FIG. 1 but another type of DVDD2 of FIG. 4 is set, the outgoing light L1 of the light emitting unit 32 of FIG. 2 is set. Passes through the collimating light generation lens 35 and the DVDD
It is reflected by the second reflection film 133. Then, the return light L2 passes through the parallel light generation lens 35 as shown by the solid line and is received by the light receiving unit 33 side. The light receiving unit 33 receives the light receiving signal SR1.
Is sent to the discrimination unit 20. As a result, the determination unit 20 determines that the DVDD 2 of the format shown in FIG. 4 is attached to the turntable 11 shown in FIG. System controller 16
Is based on the determination made by the determination unit 20.
Drive signal to. The drive current supply unit 60 supplies a current to the electromagnetic drive unit 22, and the objective lens 21 moves to the position shown in FIG.
The transparent disc is positioned at a position corresponding to the thickness R2 of the substrate 131. As a result, the distance between the objective lens 21 and the reflection film 133 in FIG. 4 is set accurately.

Further, a compact disc D of the type shown in FIG.
When 3 is chucked to the turntable 11, as shown in FIG. 2, the optical paths of the forward light L1 and the return light L2 indicated by the broken line similar to those of the DVDD1 of the format of FIG. 3 are formed. That is, the return light L2 is received by the light receiving unit 34 side via the parallel light generation lens 35. Therefore, the light receiving unit 34 receives the light receiving signal S
R2 is sent to the determination unit 20. System controller 16
Sends a drive signal to the drive current supply unit 60 based on the determination result of the determination unit 20. The drive current supply unit 60 sends a current to the electromagnetic drive unit 22 so that the objective lens 21 and the reflection film 222 of FIG. 5 correspond to the thickness R1 of the substrate 221 of the transparent disc of FIG. Set the distance between.

In this way, the optical discs of different types and formats as shown in FIGS. 3 to 5 are turned table 1 of FIG.
Even when set to 1, the distance between the objective lens 21 and the reflection film of the optical disc, that is, the data of the objective lens 21 and the optical disc, is corresponding to the thickness R1 or R2 of the substrate of the transparent disc of the optical disc. The distance on the recording surface can be corrected and set accurately.

Next, FIG. 6 shows another embodiment of the optical disk reproducing apparatus of the present invention. The embodiment of FIG. 6 is
The photodetector 30 is set on the fixed base 312. That is, the photodetector 30 is not set on the slide base 13d of the optical pickup 13, but is a separate body. This photodetector 30 has the same structure as the photodetector 30 of FIG. Other elements of the embodiment of FIG.
Since each element is the same as that of the embodiment shown in FIG. 1, its explanation is omitted. As described above, the optical disc reproducing apparatus of the present invention has various types of discs. When one of the various discs is set for the turntable, the type of the chucked disc. To determine.
Then, based on the determined information, the distance between the objective lens of the optical pickup and the data recording surface of the disc can be corrected.

[0023]

As described above, data on various optical disks can be reproduced by detecting the difference between the thicknesses of different types of optical disks and the thickness of the substrate of translucent disks.

[Brief description of drawings]

FIG. 1 is a diagram showing a preferred embodiment of an optical disc reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a photodetector of the optical disc reproducing apparatus of FIG.

FIG. 3 is a sectional view showing a part of a single-sided recording type digital video disc.

FIG. 4 is a sectional view showing a part of a double-sided recording type digital video disc.

FIG. 5 is a cross-sectional view showing a part of an ordinary compact disc.

FIG. 6 is a diagram showing another embodiment of the optical disc reproducing apparatus of the present invention.

[Explanation of symbols]

12 Spindle Motor (Drive Unit for Rotating Optical Disc) 13 Optical Pickup 20 Discrimination Unit 30 Photodetector (Photodetection Unit) 121, 131, 132, 221 Translucent Disc Substrate D1, D2 Optical Disc (Digital Video Disc) D3 Optical disc (compact disc) DF1, DF2, DF3 Data recording surface L1 Forward light for irradiation L2 Return light R1, R2 Substrate thickness of transparent disc

Claims (5)

[Claims] 1. A drive unit that rotates an optical disc on which data is compressed and recorded, and a data recording surface of the optical disc that is rotated by the drive unit is irradiated with light through a substrate of a translucent disc to transmit the light. By detecting the return light through the substrate of the optical disc, the optical pickup for reading the signal of the data recording surface and the data recording surface of the optical disc are irradiated with the light through the substrate of the transparent disc. , Optical detection unit for detecting the difference in thickness of the substrate of the transparent disc by detecting the return light through the substrate of the transparent disc, and the type of optical disc based on the signal of the optical detection unit. And a discriminating unit for discriminating the optical disc reproducing apparatus. 2. The light detecting section detects a return light through a light emitting section for irradiating the data recording surface of the optical disc with light through a substrate of the transparent disc and a substrate of the transparent disc. The optical disc reproducing apparatus according to claim 1, further comprising a light receiving unit for. 3. The optical disc reproducing apparatus according to claim 1, wherein the photodetection unit is arranged integrally with the optical pickup. 4. The optical disc reproducing apparatus according to claim 1, wherein the photodetector is arranged separately from the optical pickup. 5. The light receiving section of the light detecting section, wherein the light emitting section of the light detecting section irradiates the data recording surface of the optical disk on which data is compressed and recorded with light through the substrate of the light transmitting disk. Detects the return light that has passed through the substrate of the translucent disc to detect the difference in the thickness of the substrate of the translucent disc and determine the type of optical disc based on the signal from the photodetector. An optical disk reproducing method characterized by the above.