JPH0427613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc-shaped record carrier (hereinafter referred to as a disk) and a recording/reproducing device for recording or reading information on the record carrier.

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. 2. Description of the Related Art Apparatuses have already been proposed that can record video signals and the like in real time as changes in optical characteristics, and can reproduce recorded information by detecting changes in optical characteristics. In such a device, in order to record and reproduce a video signal or the like on a selected track on a disk, for example, the track to be recorded is formed in advance as a guide track in the shape of a groove on the disk, and then the guide track is During formation, address information is formed on each guide track using a serial number from the outer periphery (or inner periphery) to the inner periphery (or outer periphery) of the disk as a phase change of the unevenness.

This address information is formed in the shape of an arc forming a certain angle with respect to the center of the disk. Now, when recording a television signal on one track of this disk, it is necessary to prevent image information from being recorded in the address information section of this track. 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. or,
As a method of forming this rotation start position mark in consideration of positional accuracy and productivity, it is proposed to form a rotation start position mark consisting of a plurality of arc-shaped guide tracks on the inner or outer circumference of the disk at the same time as forming the guide track. has been done.

The rotation start position mark is used to detect the rotational position of the disk in order to rotate the disk in synchronization with an external video signal during recording, and to rotate the disk in synchronization with an internal reference oscillator during playback. Since it is also used to determine the timing when reading the address signal, stable and accurate detection of the rotation start position mark is extremely important for the operation of the disk device.

Detection of the rotation start position mark generally does not use an optical head using a laser, but instead uses elements such as a light emitting diode and a phototransistor, which has poor sensitivity and frequency characteristics, and does not follow disk surface runout. Therefore, the sensitivity and DC component vary significantly, so it is not easy to detect the rotation start position mark while covering the difference in reflectance between disks and being unaffected by scratches on the disk. In particular, it has been confirmed that some flaws have a reflectance comparable to that of the rotation start position mark.

FIG. 1 shows an example of a conventional optical disk.

The optical disk 1 is composed of a track portion 2 consisting of a groove-shaped guide track, absolute track address information portions 3 and 4 formed on the guide track, and a rotation start end position mark 5. Absolute address information section 3,
4 is formed to form an angle α with respect to the center 6 of the optical disk 1.

FIG. 2 is an enlarged sectional view of a part of the track along the guide track, in which part of the guide track 2 and the absolute address information section 3 are shown in a line. . The absolute address information section 3 is formed as uneven pits in the form of a modulated signal such as FM modulation or PE modulation.

FIG. 3 is an enlarged cross-sectional view of the rotation start position mark 5. The rotation start position mark 5 is cut out and detected as a difference in reflectance by an emission diode and a phototransistor.

FIG. 4 shows an example of the configuration of a rotation start position mark reading device. 1 is the aforementioned disk, and 6 is a motor for rotating the disk 1. The light beam emitted from the light source 7 is reflected by the aforementioned rotation start position mark 5, enters the light receiver 8, is converted into an electric signal, is amplified by the amplifier 9, and reaches the output terminal 10.

FIG. 5 shows an example of the waveform of the output terminal 10 of the conventional configuration shown in FIG. 4 for one rotation of the disk.

Reference numeral 20 indicates a DC component fluctuation waveform due to warping of the disk, uneven reflectance, etc., reference numeral 21 indicates a portion of the rotation start position mark, and 22 and 23 indicate waveform examples of portions of flaws on the disk. When flaws 22 and 23 of the same level appear in the same direction as the output 21 corresponding to the rotation start position mark 5 as in this waveform example, it is difficult to detect them separately. Further, the width of the flaw waveform may be comparable to the width of the rotation start position mark.

The present invention uses the configuration of the conventional detection device described above to read the correct rotation start position from a detection signal that has a fluctuation in the DC component as shown in FIG. This paper proposes a structure for a rotational position mark.

An embodiment of the disk of the present invention is shown in FIGS. 6 and 7. In the figure, the groove-like track 2 and the absolute address information sections 3 and 4 of the track formed on the guide track are the same as those in FIG.

The rotation start end position mark group 5' is formed by forming two or more consecutive unit marks with a width that can be detected independently at one place on the disk, and when forming the guide track of the disk, the beginning is placed in the address information section. is formed to match the beginning of.

FIG. 8 is a block diagram showing the signal processing rotation of the recording/reproducing apparatus in one embodiment of the present invention. Fourth
After detecting the rotation start position mark group with the detection device configured as shown in the figure and converting it into an electrical signal,
0 to the high-pass filter 31, remove DC component undulations caused by disc warpage and uneven reflectance, convert it to logic level in the waveform shaping circuit 3, and then output the rotation start position mark group using the one-shot multi 33. into one continuous pulse. Then, a low-pass filter 34 and a Schmitt trigger 35 remove discontinuous single pulses due to noise caused by scratches, etc., and shape the waveform.

FIG. 9 is a waveform diagram of the above operation. a is the signal waveform of the input terminal 30 in FIG. 8, and 37 is the signal waveform of the input terminal 30 in FIG.
The rotation start position mark 38, which is composed of a plurality of unit marks, is an example of the noise waveform. b is a waveform obtained by removing low-frequency components from signal a by a high-pass filter 31, and is shaped by a waveform shaping circuit 32 to become signal c. d is a waveform obtained by converting the signal c into one continuous pulse for a group of rotation start position marks using a one-shot multi 33 having a time constant equal to or longer than one period of one rotation start position mark. e is the signal d passed through the low-pass filter 34, f
The signal e is shaped by the Schmitt trigger 35 to remove single pulses due to noise, and this becomes the final rotation start position mark.

As described above, since the rotation start position mark of the present invention is composed of a plurality of unit marks, it is caused by a flaw with the same width and the same amplitude or more as the rotation start position mark, which could not be distinguished from the conventional rotation start position mark. Noise can be separated.

Therefore, only the rotation start position can be detected from the photoreceiver output accompanied by noise due to scratches or the like.

[Brief explanation of drawings]

FIG. 1 is a plan view of a conventional disk, FIG. 2 is a partially enlarged sectional view of the track in FIG. 1, FIG. 3 is an enlarged sectional view of the rotation start position mark in FIG. 1, and FIG. Configuration diagram of rotation start position mark detection device,
FIG. 5 is an operational waveform diagram of the detection device, FIG. 6 is a plan view of a disk according to an embodiment of the present invention, and FIG. 7 is a partially enlarged sectional view of a rotation start position mark of the present invention.
FIG. 8 is a block diagram showing a signal processing circuit of a recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 9 is an operation waveform diagram of each part of the circuit configuration of FIG. 8. 1... Disc, 2... Guide track, 3, 4
... Address information, 5, 5' ... Rotation start position mark (rotation position detection mark).

Claims (1)

[Scope of Claims] 1. A disc-shaped record carrier having a position detection mark consisting of a plurality of unit marks continuous in the circumferential direction at one location on the outer periphery or the inner periphery of the disc other than the information recording area. 2 Consisting of continuous pulses by reading a position detection mark consisting of a plurality of unit marks continuous in the circumferential direction provided at one location on the outer periphery or inner periphery of the disc-shaped record carrier other than the information recording area a converting means for converting into an electrical signal, a high-pass filter for removing low-frequency components of the electrical signal, a waveform shaping means for shaping a waveform, and a pulse for converting into one pulse corresponding to a period of the continuous pulse. A recording/reproducing device comprising a converting means.