JPH0249497B2 - KOGAKUTEKIKIROKUSAISEISOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording/reproducing device, and particularly to a disk rotation start position mark having concentric or almost concentric (spiral) guide tracks and address information for each guide track formed in advance. It is about detection.

With the recent development of highly sensitive optical recording materials, in addition to the playback-only function of conventional video disks, they are now capable of recording and playing back signals on their own in real time. Such optical recording and reproducing devices generally irradiate a disk coated with or vapor-deposited with a photosensitive material with light whose intensity is modulated by a recording signal, and produce changes in unevenness or changes in refractive index, reflectance, etc. on the disk. An apparatus has already been proposed that can record information such as a video signal in real time as a change in optical characteristics, and can reproduce the recorded information by detecting the change in optical characteristics. In such a device, in order to record a group of video signals, etc. on selected tracks on a disk, and to realize playback, tracks for recording are formed in advance on the disk in the form of grooves, for example, as guide tracks, and then the guide tracks are formed on the disk in advance. When forming the disk, address information is formed on each guide track using a serial number from the outer circumference (or inner circumference) to the inner circumference (or outer circumference) of the disk as a phase change of the unevenness.

In a disk with guide tracks, address information is formed on each track in the shape of an arc forming a certain angle with respect to the center of the disk. Now, when recording a TV image on one track of this disk, it is necessary to prevent image information from being recorded in the address information section of this track. To do this, it is necessary to control the rotation of the disk so that the vertical synchronization signal of the TV image signal and the address information part are recorded in substantially the same phase. For this purpose, it has been proposed to separately provide a rotation start position mark on the disk at a position corresponding to the address information.

This rotation start position mark is formed by adhering aluminum foil, vapor depositing a mirror material, or the like. In addition, as a forming method that takes into account the positional accuracy and productivity of this rotation start position mark, it is possible to form a rotation start position mark consisting of a plurality of arc-shaped guide tracks on the inner or outer periphery of the disk at the same time as forming the guide track. Proposed.

The rotation start position mark is used to rotate the disk at a constant rotation speed in synchronization with the external video signal during recording, and to rotate the disk at a constant rotation speed in synchronization with the internal reference oscillator during playback. In addition to being used to detect the rotation of the disk, it is also used to determine the timing when reading address signals, so stably and accurately detecting the rotation start position mark is extremely important for the operation of the disk device.

Detection of the rotation start position mark is generally performed using elements such as a light emitting diode and a phototransistor, without using an optical head using a laser. Therefore, both the sensitivity and frequency characteristics are not good, and it does not follow the surface runout of the disk, so the sensitivity and frequency characteristics are poor.
The DC component varies significantly. Therefore, it is not easy to detect the rotation start position mark while covering the difference in reflectance between disks and without being affected by scratches on the disk. In particular, it has been confirmed that some scratches have a reflectance comparable to that of the rotation start position mark.

FIG. 1 shows an example of a conventional optical disk. An optical disk 1 includes a groove-shaped guide track 2 constituting a track portion, absolute address information portions 3 and 4 of the track formed on the guide track 2, and a rotation start end position mark 5. It consists of The absolute address information sections 3 and 4 are formed so as to form an angle α with respect to the center 0 of the optical disk 1.

FIG. 2 is an enlarged sectional view of a portion of the track, showing a portion of the guide track 2 and the address information section 3 in a line. Address information is
Track address information is formed as uneven pits in the form of modulated signals such as FM modulation or PE modulation.

FIG. 3 is an enlarged cross-sectional view of the rotation start position mark 5, where the rotation start position is cut out and detected as a difference in reflectance using a light emitting diode and a phototransistor.

FIG. 4 shows an example of an optical recording/reproducing apparatus equipped with the above-mentioned rotation start position mark detector. In FIG. 4, as in FIG. 1, reference numeral 1 designates the aforementioned disk, 2 a groove-shaped guide track, and 5 a rotation start position mark. The light driven by the laser drive circuit 6 passes through the aperture optical system 7 and is irradiated onto the disk 2 by the aperture lens 8 to record image information etc. on the grooved guide track 2 or to reproduce pre-recorded signals. do. When reproducing a signal from the disk 1, the reflected light from the disk 1 is used to reproduce the signal using the photodetector 9. 10 is an address processing circuit that reads only address information from the reproduced signal. Reference numeral 11 denotes a control circuit for determining address information and sending out control commands for the apparatus, and is mainly composed of a microcomputer and the like. 12 is a disk motor for rotating the disk 1, and 13 is a drive control circuit for the disk motor 12. Reference numeral 14 denotes a detector composed of a light emitting diode and a phototransistor so as to detect the rotation start position mark 5. 15 is a waveform shaping circuit that processes the signal from the detector 14. The rotation start position mark signal from the waveform shaping circuit 15 is input to the motor drive control circuit 13, and the disc motor 1
This becomes the reference signal for the rotation of step 2.

FIG. 5 shows a configuration example of the detector 14 and waveform shaping circuit 15 of the rotation start position mark 5 shown in FIG. The detector 14 is a light source 1 such as a light emitting diode.
6. It is composed of a light receiver 17 such as a phototransistor, and converts the amount of light reflected from the rotation start position mark 5 on the disk 1 into an electrical signal and outputs the electrical signal. Receiver 17
The output of is an amplifier 18, a bandpass filter 19,
Waveform shaping circuit 15 composed of comparator 20
and is output from terminal B as a rotation start position mark signal.

FIG. 6 shows an example of waveforms at each part in FIG. 5. In FIG. 6, a shows the output waveform of the photoreceiver 17, A shows the DC fluctuation waveform due to warping of the disk, uneven reflectance, etc., and B and B show the waveform of the rotation start position mark signal. FIG. 6b shows the output waveform of the bandpass filter 19 which removes the high frequency components and low frequency components of a, and the dotted line A is the terminal A of the comparator 20.
Indicates the comparison voltage level input to the Figure 6 c
is the output waveform of the comparator 20, which indicates the rotation start position mark signal, and low-low' corresponds to one rotation of the disk.

In this way, since the rotation start position mark signal is detected by detecting the difference in reflected light from the disk 1, if there is a scratch or dust on the track of the rotation start position mark 5, the rotation start position mark signal is detected. It may be mistakenly recognized as position mark 5. An example of a waveform diagram at this time is shown in FIG. Similar to FIG. 6, FIG. 7 shows a waveform diagram of each part of the waveform shaping circuit 15. In FIG. 7A, B and B' indicate rotation start position mark signals, and C indicates noise caused by changes in reflectance due to scratches and dust. b in Fig. 7 shows the output waveform of the band pass filter (19 in Fig. 5), c in Fig. 7 shows the output waveform of the comparator (20 in Fig. 5), b and b' are rotation start position marks, C is noise caused by scratches and dirt.

The present invention provides an optical recording and reproducing apparatus equipped with a detection device that accurately detects a rotation start position mark signal even if scratches, dust, etc. adhere to the track of the rotation start position mark as described above.

The configuration of the present invention will be explained below based on the drawings.
FIG. 8 shows an embodiment of the optical recording/reproducing device of the present invention, and the same parts as in FIG. 4 are given the same numbers.
Detailed explanation will be omitted. FIGS. 9 and 10 show waveform diagrams of each part.

In FIG. 8, the control circuit 11 generates a signal that becomes "H" when the rotation of the disk motor 12 reaches a controlled rotation speed (for example, 1800 rpm) and the address information j can be read, and becomes "L" otherwise. Send i. On the other hand, address information j from the address processing circuit 10 is input to the multivibrator 25. The multivibrator 25 converts the address information j into one continuous pulse k with a time constant slower than the frequency of the address information j, and inputs it to the low-pass filter 26. A low-pass filter 26 removes single pulses that are not continuous, such as dropouts caused by scratches or dust, and inputs the removed pulses to a comparator 27. Comparator 27 connects the comparison voltage input from terminal D and low-pass filter 2.
7 and sends out an inter-number area signal h. FIG. 10 shows a waveform diagram of the above operation. 1st
j in Figure 0 is the output waveform of the address processing circuit 10,
Section d is address information, and section e is dropout. 10 is the output waveform of the multivibrator 25. In FIG. 10 is the output waveform of the low-pass filter 26, and the dotted line D is the output waveform of the comparator 2.
7 shows the comparison voltage input from terminal D of No. 7. 10th
In the figure, h indicates the number interval signal h output from the comparator 27.

In FIG. 8, the drive control circuit 13 is connected to the detector 1.
The rotation of the disk motor 12 is controlled based on the rotation start position mark signal detected by 4. 7th
As shown in the figure, if scratches, dirt, etc. adhere to the track of the rotation start position mark 5 and noise is generated (the waveform diagram is shown in Figure 9a, B and B' are the rotation start position marks). signal, C and C′ are noise)
In this case, the rotation of the disk motor 12 is not controlled. Therefore, the address information cannot be read, and a signal i of "L" is sent from the control circuit 11, and the output f of the NAMD gate 24 to which this signal i is input.
becomes "H", and the NAND gate 28 outputs the rotation start position mark signal (c in FIG. 9) as is, which is the output of the waveform shaping circuit 15, and inputs it to the multivibrator 21. multi vibrator 21
is the time required for one rotation of the disk (for example, 33 m
s) is set to a shorter time constant. The waveform diagram is shown in FIG. 9d. The waveform diagram d in FIG. 9 shows, as an example, the output waveform when the multivibrator 21 is set to a rising waveform of noise C. The multivibrator 22 is set to have a time constant that is longer than the time required for one rotation of the disk when the time constants of the multivibrators 21 and 22 are combined. The waveform diagram at this time is shown in e of FIG. The output e of the multivibrator 22 is
The pulses C and C' that are input to the NAND gate 23 and differ from the actual rotation start position mark signal (b in c in FIG. 9) are extracted once per rotation as shown in g in FIG. , C' are sent to the drive control circuit as motor reference signals. From this point on, the disk motor 12 is rotationally controlled and rotates at a predetermined constant number of rotations. When the disk motor 12 rotates at a predetermined constant rotation speed, the address information is read by the control circuit 11, and the control circuit 11 sends a signal i of "H" to the NAND gate 24.
The NAND gate 24 gates the number interval signal h (h in FIG. 9) and sends the number interval signal (f' in FIG. 9) of the opposite polarity to the NAND gate 28.
The NAND gate 28 gates the rotation start position mark output signal c (c in FIG. 9) of the waveform shaping circuit 15 and outputs only the determined rotation start position mark signal (m in FIG. 9). A rotation start position mark signal (g' in FIG. 9) is transmitted via the multivibrators 21, 22 and the NAND gate 23.
Only the drive control circuit 13 of the disk motor 12
Send to.

In this way, when noise is generated due to scratches or dust on the track of the rotation start position mark 5, when the disk motor 12 is started, the pulse generated by the rotation start position mark signal or noise etc. is rotated one rotation. is detected at a constant cycle, firstly, the rotation of the disk motor 12 is controlled using this signal as a reference signal, and then the motor reaches a constant rotation speed, and then
When the address information is read, the true rotation start position mark signal existing in the section of the address information is detected by the address area interval signal, and the disk motor is controlled to rotate using this rotation start position mark signal as a reference signal. The reference signal for controlling the rotation of the disk motor is switched between when the motor is started and after the rotation speed reaches a constant speed.

As described above, according to the present invention, even if scratches or dirt adhere to the track of the rotation start position mark, the rotation start position mark signal can be detected stably and truly, and the device can operate stably. .

[Brief explanation of drawings]

Fig. 1 is a plan view of the disk, Fig. 2 is an enlarged sectional view of the track portion of Fig. 1, Fig. 3 is an enlarged sectional view of the rotation start position mark of Fig. 1, and Fig. 4 is a conventional optical recording/reproducing method. A block diagram showing an example of the device; FIG. 5 is a configuration diagram of the rotation start position mark detector shown in FIG. 4;
Figures 6 and 7 are waveform diagrams of the detector in Figure 5;
FIG. 8 is a block diagram showing an embodiment of an optical recording/reproducing apparatus equipped with a rotation start position mark detection circuit of the present invention, and FIG. 9 is a waveform of the rotation start position mark detection circuit of FIG. 10 are waveform diagrams of the detection circuit for the inter-number area signal of FIG. 8. 1...Disc, 2...Groove guide track, 5
... Rotation start position mark, 11 ... Control circuit, 1
2...Disc motor, 14...Detector, 21,
22...Multi vibrator, 23, 24, 28
...NAND gate, 25 ... multivibrator, 26 ... low pass filter, 27 ... comparator.

Claims (1)

[Scope of Claims] 1. A disk having concentric or spiral guide tracks, address information corresponding to each guide track, and a disk rotation start position mark, and rotation control means for a disk motor for rotating the disk. a recording/reproducing means for optically recording or reproducing image information or the like on the guide track; a means for reading the rotation start position mark; a means for reading the address information; and a circuit for detecting the section of the address information. means for detecting one pulse per rotation at a constant cycle from the output signal of the means for reading the rotation start position mark before reading the address information, and detecting the rotation start position mark after reading the address information. 1. An optical recording/reproducing apparatus comprising: a switching means for detecting a pulse existing in the section of the address information from an output signal of the means for reading the address information, and using the pulse as a reference signal for the rotation control means. 2. A first multivibrator having a time constant that is shorter than the time required for one rotation of the disk, and a time constant that becomes longer than the time required for one rotation when added to the time constant of the first multivibrator. Claims characterized in that a second multivibrator is provided, and one pulse per one rotation of the disk is detected from the output signal of the means for reading the rotation start position mark by the output of the second multivibrator. 2. The optical recording/reproducing device according to item 1. 3. The optical recording and reproducing apparatus according to claim 1, wherein the circuit means for detecting the section of the address information sends out an output only when the address information is read.