JPH0352147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical disc for optically recording and/or reproducing information on a disc-shaped information carrier (optical disk) capable of optically recording and/or reproducing information. This system is designed to detect whether the surface of the disk that is irradiated with a minute spot light from a laser is the front or the back, especially when an optical disk is mounted on the optical recording and reproducing device. .

Conventional structure and its problems As an optical information recording/reproducing device, for example, an optical disk coated with or vapor-deposited with a photosensitive material is rotated, and a beam from a laser light source is focused onto the optical disk to a diameter of 1 μm or less. By irradiating a small spot of light and modulating its optical output intensity with a recording signal, optical changes such as phase changes, refractive index changes, reflectance, and transmittance changes due to unevenness are displayed on the optical disk in real time. There is a device that can record information such as a video signal or digital signal using an optical device, and can reproduce the recorded information by detecting a change in the optical characteristics.

In such devices, optically detectable guide tracks are provided in advance in a concentric or spiral shape on the track to be recorded in order to increase the density of the recording track, discrete partial writing, erasing, etc. An optical information recording and reproducing apparatus can be considered in which conventionally known tracking control is applied so that a minute spot light according to the invention follows the guide track, information is recorded on a predetermined track, and information is reproduced from the track.

The guide track formed on the optical disk is suitably, for example, a groove-like structure with uneven surfaces, and information is recorded on a recording medium deposited in the groove of the guide track.

The device records information by rotating the disk in a fixed direction and recording information along the guide track, so the arrangement of information on the disk is fixed either clockwise or counterclockwise. There is.

On the other hand, there are two types of optical discs: single-sided discs that record information on only one side, and double-sided discs that record information on both sides.

If information is recorded on a track from the back side of a single-sided disc that is structured so that it can be recorded from the side opposite to the normal recording side, when that track is played back from the front side, the arrangement of the information will be reversed from the normal arrangement.
It becomes impossible to read the written information.

Also, to the tracks already recorded on the front side,
If you record from the back side, the legitimate recorded information on the front side will be destroyed. Therefore, when a single-sided disk is installed in the device, it is necessary to determine which side is the recording side, and if the side irradiated by the laser is a non-recording side, it is necessary to not irradiate the laser to prevent erroneous recording. be.

In addition, with a double-sided disc, both the front and back sides have information recording areas, but if the disc is installed upside down when trying to record on the front side and the back side is recorded by mistake, there will be confusion in the allocation of the information to be written. happen. Moreover, if information is recorded incorrectly when information has already been recorded, the previously recorded information will be destroyed. Therefore, even when a double-sided disk is attached to the device, the user must determine whether the laser will irradiate the desired surface, and if the disk is attached in the opposite direction, the laser will be irradiated to prevent erroneous recording. It is necessary to prevent this from happening.

Purpose of the Invention In order to solve the above-mentioned problems, the present invention distinguishes between the front and back sides of a disc, and after confirming that the surface to be irradiated with a laser for recording and reproducing information is the surface desired by the user. It is configured to emit laser light and perform focus and tracking control.

Structure of the Invention The present invention provides a means for detecting a front/reverse discrimination mark provided in a front/reverse discrimination track area of an optical disk using a second light source different from a first light source for recording and reproducing information. This is an optical recording/reproducing device equipped with a means for discriminating the front and back sides of an optical disc based on a front/back discrimination mark signal. By confirming that they are the same, and then emitting light from the first light source, erroneous recording on the disk is prevented.

Description of examples The drawings accordingly illustrate embodiments of the invention.

FIG. 1 is a plan view showing the structure of an optical disk having front and back discrimination marks detectable from both sides, used in an optical recording/reproducing apparatus according to a first embodiment of the present invention.

The optical disc 1 is composed of an information recording area 2 consisting of a groove-shaped guide track and a front/back discrimination track area 3 for distinguishing between the front and back sides of the disc. On the front/reverse discrimination track, there is a reference mark 4 that can be detected from both sides. A comparison mark 5 is formed to compare the position with the reference mark 4. The reference mark 4 and comparison mark 5 are arranged at positions that are not symmetrical with respect to the center of the disk.

FIG. 2 is a perspective view of the basic structure of these two marks. Both marks are constituted by a group of guide track pieces 7 in which guide track pieces 6, each of which has the same groove as the guide track in the information recording area and an arc angle α of the optical disk, are aligned for a plurality of tracks.

FIG. 3 shows an example of the configuration of both marks. The two marks are distinguished by different numbers of guide track pieces arranged. FIG. 3a shows the structure of the reference mark 4, in which a group of guide track pieces 7 whose length in the circumferential direction corresponds to the arc angle α of the disc and whose length in the radial direction corresponds to the arc angle α shown in FIG. Three pieces are arranged with an interval of α. FIG. 3b shows the structure of the comparison mark 5, which is composed of one group of the guide track pieces. At this time, all parts of the front/back discrimination track other than both marks are flat.

FIG. 4 shows an example of a mark detection device for detecting both of the above marks.

In FIG. 4, the optical disk 1 is being rotated by a motor 8 at a constant rotation speed. The mark detector 9 is an optical reflective sensor, and is composed of a light receiving element that focuses a light beam emitted from a light emitting element onto a front/back discrimination track 3 on the optical disk 1 and photoelectrically converts the reflected light. Since both marks have a phase groove structure, light is scattered in the groove, and the amount of reflected light incident on the light receiving element of the mark detector 9 is reduced, thereby being detected. The output of the mark detector 9 is amplified by an amplifier 10, passed through a bandpass filter 11, and then pulse-shaped by a comparator.

FIG. 5 shows the signals of each part in FIG. 4. amplifier 1
Since the output signal 13 of 0 causes an amplitude change as shown in FIG. . The output 14 of the bandpass filter 11 has the above fluctuation component removed as shown in _FIG . The output 15 of this comparator 12 is shown in FIG.

FIG. 6a shows the comparator output signals 15 of the reference mark and comparison mark that can be detected from both sides when the disk is placed face up. b is the same signal 19 when it is installed face down. As is clear from the figure, if the reference mark and comparison mark are placed in positions that are not symmetrical with respect to the center of the disk, when the disk is installed face up and when it is installed face down, The time from the reference mark signal 16 to the comparison mark signal 17 changes from T ₂ to T ₃ within a period T ₁ during which the disk rotates once.
Therefore, by checking whether or not the comparison mark signal 17 is detected within a certain period of time after the reference mark signal 16 is detected, it is possible to detect which direction the disk is mounted.

FIG. 7 shows an embodiment of the disk front/back discrimination circuit shown in the first embodiment. FIG. 8 shows signal waveforms at various parts in FIG. 7.

Now, the laser for recording and reproducing information is not emitted, only the disk motor is rotated, and a front/back discrimination mark signal 15 as shown in FIG. 8 is inputted to the input terminal 18 of this front/back discrimination circuit. This signal 15 is a signal that detects the comparison mark signal 17 within half a rotation after the reference mark signal 16 is detected. The time constant of the retrigger type monomulti 20 is set larger than the pulse period width T ₄ of the reference mark. The output 22 of the monomulti 20 is “L” for the counter 21.
When , do not count, clock 2 is in "H" state.
Start counting 3. Digital comparator 2
The setting value 4 is set to a value such that the pulse that is output when a match occurs is not output in the case of a comparison mark, and is output after the last pulse of the reference mark has finished outputting. That is, the comparator 24 is set so that the output 25 of the comparator 24 is not output when only one pulse is input, as in the case of a comparison mark, but is output only when two or more pulses are input, as in the case of a reference mark.

After a matching pulse appears at comparator output 25,
NAND the output 27 of the monomulti 26, the front and back discrimination mark signal 15, and the motor rotation synchronization signal 28, and set the time constant of the monomulti 25 so that the comparison mark of the front and back discrimination mark signal 15 is detected. . When the NAND output 29 is output, the Q output 32 of the flip-flop 31, which is reset to "L" by the rise of the output DMON 30 when the motor is turned on, becomes "H".

In other words, if the circuit is set so that if a comparison mark is detected within half a rotation after the reference mark is detected, the Q output 32 of the flip-flop 31 becomes "H". In the front/back discrimination mark signal b17 at the time, the Q output of the flip-flop remains at "L", and the front/back of the disk can be determined by the Q output of the flip-flop.

After determining the front and back sides, it is checked by the control of the CPU whether the laser for recording and reproducing information is irradiated on the side desired by the user, and if it is normal, the laser is emitted after checking, Apply focus tracking control.

As described above, according to the first embodiment, in a disk having a front and back discrimination mark that can be detected from both sides as shown in FIG. By emitting a laser for recording and reproducing information after confirming the mounting direction of the disc, it is possible to prevent erroneous recording on the opposite surface from the desired surface.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 9 shows the structure of an optical disk in which there are independent front/reverse discrimination track areas on the front and back sides, and the front/reverse discrimination mark on each track cannot be detected from the opposite side. The front/reverse discrimination track 3 of the optical disk 1 is located on the same circumference on the front and back sides, and only a reference mark 34 is formed at an arbitrary position on the front/reverse discrimination track on the front side, and on the front/reverse discrimination track on the back side. Only the comparison mark 35 is formed at an arbitrary position. The reference mark and comparison mark have the same phase groove structure as shown in the first embodiment, the reference mark is composed of a group of three guide track pieces shown in FIG. It consists of one group of guide track pieces shown in .

FIG. 10 shows output signals of both marks detected by the detection device shown in FIG. 3.

Figure 10a shows the signal 37 detected from the front/back discrimination track on the front side, in which only the reference mark signal 16 is detected, and Figure 8b shows the signal 49 detected from the front/reverse discrimination track on the back side, with only the comparison mark signal 17 detected. has been detected.

FIG. 11 shows one block of the front/back discriminating circuit in the second embodiment of the present invention, and FIG. 12 shows detection signals of each part.

As in the first embodiment, the laser for recording and reproducing information does not emit light and only rotates the disk motor.
The front/back discrimination circuit input terminal 36 in FIG.
A front/back discrimination mark signal 37 shown in the figure is input. This signal is a signal in which only the reference mark is detected.
The counter 38 is a re-trigger type monomulti 39
When the output of the clock 41 is "L", it does not count, but when the output is "H", the clock 41 starts counting. The set value of the digital comparator 42 is such that when a match occurs, the pulse that is output is not just one pulse like the comparison mark signal, but is output only when two or more pulses are input like the reference mark signal. Set it as follows. After the coincidence detection pulse is output from the comparator output 43, the motor rotation synchronization signal 44 and
If you take NAND and get this NAND output 45,
The Q output 48 of the flip-flop 47, which is reset to "L" by the rise of the output DMON 46 when the motor is turned on, is set to "H".

That is, if the circuit is set so that the Q output 48 of the flip-flop becomes "H" when a reference mark is detected, the reference mark signal can be detected using only the comparison mark signal, such as the front/back discrimination mark signal 49 in FIG. If there is no signal or if there is no signal, the Q output 48 of the flip-flop remains at "L", and the front and back sides of the disk can be determined from this Q output.

After determining the front and back sides, the CPU controls to check whether the laser for information recording and playback is irradiated to the desired side of the user. If it is normal, after checking, the laser is emitted and focused.・Apply tracking control.

As described above, according to the second embodiment, two
Even for discs that have independent front/reverse discrimination tracks, and as shown in Figure 10, one side of the front/reverse discrimination track has a reference mark and the other side has no front/reverse discrimination mark, the disk motor cannot be operated. It is possible to distinguish between the front and back sides simply by rotating the disc, and by emitting a laser for recording and reproducing information after confirming the mounting direction of the disc, it is possible to prevent erroneous recording on the side opposite to the desired side.

In both the first and second embodiments, the front/back discrimination track area is located inside the information recording area, but it goes without saying that it may be located outside.

Effects of the Invention The optical recording/reproducing device of the present invention is an optical disk having a front/reverse discrimination track with a front/reverse discrimination mark formed inside or outside an information recording area, and uses a light source different from the light source for recording/reproducing information. By this, it is possible to distinguish between the front and back sides of the disc, and after confirming that the disc is oriented in the direction desired by the user, the light source for recording and reproducing information is emitted, allowing normal reading of information on the desired side. It enables writing and prevents erroneous recording on the disk, which has great practical effects.

[Brief explanation of drawings]

Fig. 1 is a plan view of the first embodiment of the optical disk used in the present invention, Fig. 2 is an enlarged perspective view of the front/back discrimination mark of the same optical disk, and Fig. 3 is a comparison with the reference mark of the same optical disk. FIG. 4 is a main part block diagram showing one embodiment of the detection device for the front/back discrimination mark of the present invention, FIG. 5 is a waveform diagram of detection signals of each part in FIG. 4, and FIG. 6 is a plan view showing the structure of the mark. 7 is a block diagram of the front and back discrimination circuit in the first embodiment of the present invention, and FIG. Figure 9 is a plan view of the second embodiment of the optical disk used in the present invention;
FIG. 10 is a waveform diagram of a detection signal for detecting a front/reverse discrimination mark on an optical disk according to the second embodiment, FIG. 11 is a block diagram showing a front/reverse discrimination circuit in the second embodiment of the present invention, and FIG. FIG. 3 is a signal waveform diagram of each part of the circuit shown in the figure. 1... Optical disk, 2... Information recording area, 3
...Front/backside discrimination track area, 4...Reference mark,
5...Comparison mark, 9...Photodetector, 16...Reference mark signal, 17...Comparison mark signal.

Claims (1)

[Scope of Claims] 1. In the information recording area of an optical disk, the information recording area has a front and back semi-separated track area on the inside or outside of the information recording area, and a front and back discrimination mark having a phase groove structure is formed on the front and back discrimination track area. a first light source for recording and reproducing information; a second light source for illuminating the front/back discrimination track; a photodetector for receiving reflected light from the front/back discrimination track; and an output of the photodetector. What is claimed is: 1. An optical recording/reproducing apparatus comprising: a detecting means for detecting a front/back discrimination mark signal; and a discriminating means for discriminating between the front and back of an optical disk based on the front/reverse discriminating mark signal detected by the detecting means. 2. In the front and back discrimination track area, two front and back discrimination marks, a reference mark and a comparison mark, are formed at positions that are not symmetrical with respect to the center of the disk, and the discrimination means uses the detection time difference between the reference mark and the comparison mark. 2. The optical recording/reproducing apparatus according to claim 1, wherein the optical recording/reproducing apparatus distinguishes between front and back sides. 3. A patent characterized in that the front and back sides have independent front/back discrimination track areas, a reference mark is formed only in one of the front/back discrimination track areas, and the discrimination means discriminates between the front and back depending on whether or not the reference mark is detected. An optical recording/reproducing device according to claim 1.