JPH01248354A - Device for discriminating surface and back of optical recording carrier - Google Patents

Abstract

PURPOSE:To perform the discrimination of the surface and the back plane of an optical disk without reading a signal such as an address signal, etc., by detecting a reflected light beam from the optical disk by a light beam detector. CONSTITUTION:The title device is equipped with a means 4 which projects the light beam A on the optical disk 1 and monitors a reflected beam from the optical disk including reflection B1 from the surface of a recording carrier 1, reflection B2 from a recording plane, and reflection from a sticking plane, and the discrimination of the surface and the back plane of the optical disk is performed by a means 6 which discriminates the number of reflected beams, etc. In such a way, it is not required to use a regenerating address signal from the optical disk 1, and it is possible to perform the discrimination of the surface and the back plane of the optical disk 1 having a various kinds of formats easily and accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a disc-shaped optical record carrier (hereinafter referred to as an optical disk) whose recording surface side/protective surface side (hereinafter, the recording surface side is referred to as the front side and the protective surface side is referred to as the back side). This device is used to unify the front and back sides of optical discs housed in a cartridge case during the optical disc manufacturing process.

BACKGROUND OF THE INVENTION An example of a conventional device for determining whether an optical disc is front or back will be described with reference to FIG. The optical disc 1 has a structure as shown in FIG. 2, and includes a preformatted substrate, a protective substrate 1B, a recording film 1C, and a bonding portion 1D. The turntable motor 8 rotates the optical disc 1 at a constant rotation speed (for example, 90 rpm), and the optical pickup 13 focuses and irradiates a light beam onto the recording film within the optical disc, and positions the light beam in the guide groove of the optical disc. control. It also receives reflected light from the optical disk, converts it into an electrical signal F, and outputs it.

This electrical signal F is applied to the address read circuit 14 to detect the address signal contained in the electrical signal F and perform demodulation. In this address read circuit 14, using an error detection code (for example, a CRC code) in the address signal,
The front and back sides of the optical disc are determined by determining whether the address signals are read correctly in chronological order.

This is a problem to be solved by the present invention, but in such a conventional front/back discrimination device, the optical pick amplifier reads the at least one space information on the recording film of the optical disc, and then determines whether it is correct in chronological order. Since the front and back sides of the optical disc can be determined by this method, it is not possible to respond flexibly to changes in the format of the address signal of the optical disc, and it is not possible to distinguish between the front and back sides of an optical disc that does not have an address signal. In order to read the optical disc, the optical disc must be rotated accurately, the optical pickup must be controlled, and the address signal must be demodulated, making the device itself complicated.

Means for Solving the Problems In the present invention, an optical disc is irradiated with a light beam, and light beams from the optical disc including reflection from the surface of the record carrier, reflection from the recording surface, and reflection from the bonding surface are emitted. It has means for monitoring reflected beams, and the means for determining the number of reflected beams is used to determine whether the optical disc is front or back.

Effect of the Invention With the above-described configuration, the present invention eliminates the need to use a reproduction address signal from an optical disc, and makes it possible to easily and accurately determine the front and back sides of optical discs having various formats.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 shows a first embodiment of the optical disc front/back discriminating device, and shows a case where the recording surface side (front side) of the optical disc is facing up.

The optical disc 1 is placed on a table 2 with the front side facing up, and the position of the laser device 3 is adjusted so that the light beam is incident on the optical disc 1 at a constant angle. As shown in FIG. 2, the optical disc is composed of two plastic molded substrates 1A and 1B, a recording film 1C formed on the substrates 1B, and a bonding resin 1D for bonding these together. This 6...

The recording film hardly transmits the light beam, so the reflected light beam from the optical disc 1 consists of the reflected light beam B1 from the surface of the substrate 1 and the reflected light B2 from the optical disc recording film 1C.
There are two types.

The reflected light beams B1 and B2 enter the light beam detection device 4. The light beam detection device 4 includes, for example, a one-dimensional image sensor. The output signal C1 of this detection device 4 is applied to a discrimination circuit 5.

Contrary to the above, FIG. 3 shows a case in which the protective surface side (back side) of the optical disc is facing upward in the optical disc front/back discriminating device. In this case, the reflected light beam from the optical disk is
There are three types of light beams: a reflected light beam B1 from the substrate surface, a reflected light beam B2 from the optical disk recording film, and a reflected light beam B3 from the bonding surface of the molded substrate and the bonded resin. The reflected light beams B1, B2 and B3 enter the light beam detection device 4. The output signal C2 of this detection device 4 is applied to a discrimination circuit 5.

The discrimination circuit 5 is composed of a comparator 6 which converts the output signal of the detection device 4 into a pulse, and a counter 7 which discriminates the comparator output D1 or 77, -7° or D2 by counting the output signal of the comparator 6. Distinguish between the front and back sides of an optical disc based on the difference in the number of pulses. FIG. 4 shows the signal waveform of the light beam detection device 4 during the sweep time at this time.

FIG. 5 shows a device for determining the front and back sides of an optical disc in a second embodiment.

In particular, if the optical disc 1 is a pref A-mat disc on which address information has already been recorded radially as shown in FIG. , the amount of light reflected from the optical disc 1 changes. Also, due to fluctuations in the local reflectance of the recording film of the optical disc 1, the light beam detection device 4
There may be cases where the output signal level V from the output signal V varies and is not pulsed correctly by the comparator 6. In this second embodiment, in order to avoid the above-mentioned problems, the optical disc 1 is rotated at a constant rotation speed by the turntable motor 8, so that an abnormality does not occur in determining whether the optical disc is front or rear due to a local problem with the optical disc. There is.

FIG. 7 shows an optical disc front/back discrimination device according to a third embodiment of the present invention.

In the optical disc shown in Figure 2, the thickness of the molded substrate is approximately 1 mm.
On the other hand, the thickness of the bonding layer is as thin as about 100 μm, and therefore, when the back side of the optical disc is facing up, the reflected beam B2. Separation of B3 becomes difficult. In the third embodiment, a lens system composed of convex lenses 9A and 9B is inserted into the optical path of the reflected beam incident on the detection device 4 to improve the degree of separation of the reflected beams B2 and B3 in the detection device 4. At this time, in the third embodiment, the light beam B
1 is blocked by slit 1Q before entering the lens system, but slit 1 is blocked by slit 1Q inside the lens system or after exiting from the lens system.
0 so that the light beam does not enter the light beam detection device 4.

FIG. 8 shows an optical disc front/back discrimination device according to a fourth embodiment of the present invention.

In the first embodiment, the optical disc 1 includes an optical beam 9A-7.
Irradiation with .mu.A causes deterioration of the recording film, which becomes a problem especially when the optical disc 1 is a write-once optical disc (W10 disc).

Therefore, a printer 11 is inserted into the optical path of the light beam that enters the optical disc 1 to limit the time during which the light beam enters the optical disc 1. The shutter control circuit 12 controls and drives the shutter 11, and supplies a shutter open/close signal to a counter in the discrimination circuit 5 to determine whether the optical disc is front or back in conjunction with the opening/closing of the shutter.

Effects of the Invention As described above, according to the present invention, it is possible to distinguish between the front and back sides of an optical disk in which two substrates are bonded together and have a recording film on one side without reading signals such as address signals on the optical disk. This makes it possible to easily and accurately determine the front and back sides of various optical discs with different formats.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical disk front/reverse discriminating device according to a first embodiment of the present invention, and FIG. 2 is an optical disk 10 layer thereof. FIG. 3 is a block diagram of the first embodiment when the back side of the optical disc is facing up, and FIG. 4 is a cross-sectional view showing the structure of the first embodiment.
FIG. 5 is a block diagram of the optical disc front/back discriminating device according to the second embodiment of the present invention, and FIG. FIG. 7 is a block diagram of an optical disc front/back discriminating device according to a third embodiment of the present invention, and FIG.
Block diagram of the optical disc front/back discrimination device according to the embodiment, No. 9
The figure is a block diagram of a conventional optical disc front/back discrimination device. 1...Optical disc, 2...Table, 3...
・Laser device, 4...Light beam detection device, 5...
...Discrimination circuit, 6..Comparator, 7. River...
Counter, 8... Turntable motor, 9.
River/Convex lens, 10...Slit, 11...
・Shutter, 12... Shutter control circuit, 13
...Optical pickup, 14 ...Address read circuit. Name of agent: Patent attorney Toshi Nakao, 1 person +:
r ρ QJ Zhanku ri δ Q 2) 工 3-1C) は Ｇａｎｄ 訳〕 U) ツL 0ト

Claims (3)

[Claims] (1) A disc-shaped information recording carrier having a recording/reproducing film for optically recording and reproducing information, and a disc-shaped information recording carrier bonded to face the information recording surface of the disc-shaped information recording carrier so as to protect the recording/reproducing film. a radiation source for irradiating a disc-shaped optical record carrier with radiation having an optical carrier; a table for holding the disc-shaped optical record carrier; and a means for detecting reflected radiation from the disc-shaped optical record carrier, the reflected radiation being reflected from the surface of the disc-shaped optical record carrier and the information recording surface. and at least one of the reflections from the bonded surface of the disc-shaped optical carrier, and the front and back sides are determined by monitoring the reflected radiation. Carrier front/back discrimination device. (2) During the incident optical path in which the reflected radiation from the disc-shaped optical record carrier enters the means for detecting the reflected radiation, the reflected radiation from the bonded surface of the information recording surface and the disc-shaped optical carrier is detected. 2. The device for discriminating front and back sides of a disc-shaped optical record carrier according to claim 1, further comprising an optical system for separating the disc-shaped optical record carrier from the source. (3) having a shutter in the incident optical path in which the radiation from the radiation source is incident on the disc-shaped optical record carrier reflected radiation;
comprising a shutter control circuit that controls the shutter;
2. The apparatus for determining front and back sides of a disc-shaped optical record carrier according to claim 1, wherein reflected radiation is monitored when radiation is incident on the disc-shaped optical record carrier through the shutter.