JPH0621108Y2 - Optical disc and reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an optical disc capable of reading information such as a recording signal format, and a reading device thereof.

(Prior Art) Conventionally, the standard of the optical video disc is defined in the Japan Electronic Machinery Manufacturers Association Standard CP-550 "Optical Video Disc System". The outline is as follows. The track pitch is about 1.6 μm, and the recorded signal in the video is based on the NTSC system, and the frequency displacement width is 1.
7MHz (7.6 to 9.3MHz FM signal, voice is 2.3MHz and 2.8MHz 2-channel FM signal and EF
It is an M signal (CD-like signal). There are 12-inch discs (300 mm diameter) and 8-inch discs (200 mm diameter).

On the other hand, in the method of digitally recording both image and sound, and in the case of high-definition, the MUSE signal is 12.5-1.
Various methods are conceivable, such as recording as an FM signal with a frequency displacement width of 5.5 MHz and narrowing the track pitch.
Being experimented. In addition, due to the demand for higher density of recorded information, various proposals have been made regarding the recording signal and format of a disc.

From these requirements, the standard of optical video discs may be changed or diversified, but it is not easy to change the disc size from the viewpoint of manufacturing efficiency. When discs with different standards are available on the market, even if a dedicated player is used for the time being, the disc rotation mechanism, pickup for signal detection and its drive mechanism, common circuit parts, etc. are the same after that. Using the
It is obvious that a general-purpose player capable of reproducing discs having different recording signals and formats is required.

When a general-purpose player is used, a recording signal and a discriminating signal regarding the format are recorded on the disc, and the discriminating information is read prior to the reproduction to control the player. The disc can be automatically adjusted to the recording signal and the format of the disc, the operation becomes easy, and the mistaken selection can be avoided. As described above, in order to record the discrimination signal on the disc and read it out before the reproduction, the disc must first be rotated to detect the discrimination signal. Then, in the above-mentioned conventional standardized optical video disc, in order to read the discrimination signal at the lead-in stage, a discrimination signal different from the current standard has to be put in the track of the inner peripheral portion. Is required, and a conventional player that does not presume to decode the discrimination signal cannot reproduce the disc containing the discrimination signal, which is a limitation. In order to remove this restriction, it is conceivable to manually instruct the disc type at the time of use, but this is not only complicated, but if the user forgets to instruct, the reproduction will be hindered.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-described circumstances, and a recording signal and discriminating information regarding a format are recorded in an area other than a signal recording area of an optical disc for reproduction. It is an object of the present invention to set a disk in a reproducing device in advance and to discriminate a recording signal, a format and the like in a state where the disc is not rotated so as to improve compatibility of an optical disc and a reproducing device.

(Means for Solving the Problems) In the invention according to claim 1, the present invention provides, in an optical disc, predetermined equal intervals in a signal non-recording area corresponding to discriminating information regarding a recording signal and a format of the optical disc. The invention is characterized in that a pattern serving as a diffraction grating is provided on the circumference at a pitch of 1. In the invention according to claim 2, in the optical disk reader, an optical disk is provided in the signal non-recording area of the optical disk. Means for irradiating a light beam to a pattern serving as a diffraction grating formed on the circumference at a pitch of a predetermined equal interval corresponding to the discriminant information regarding the recording signal and format, and the diffraction angle of the diffracted light from the pattern. It is characterized in that a detection means for detecting is provided.

As the signal non-recording area of the optical video disc, it is possible to select a position range of 1 mm inside and 2 mm inside of the outer circumference.

(Operation) When light of wavelength λ is incident on the diffraction grating having the pitch of p, the diffraction angle θm of the m-th order diffracted light is given by θm = sin ⁻¹ (mλ / p). Therefore, since the diffraction angle changes when the pitch p of the diffraction grating is changed, it is possible to identify the diffraction grating by forming diffraction gratings of different pitches and irradiating this with laser light to detect the diffraction angle.

Based on this, the signal non-recording area of the optical disk is provided with a pattern that becomes a diffraction grating with a pitch corresponding to the optical disk standard, so that the signal area is not affected and the disk is rotated during reading. It is possible to read without discriminating and discriminate the optical disc.

(Example) An example will be described using an optical video disc as an example.

In the current disc, the maximum radius of the program track is 145 mm for a 12-inch disc and 96 mm for an 8-inch disc. The lead-out track is 2 from the end of the program track.
It has a width of up to mm. There is no recording area from the end position of the lead-out track to the outer circumference, and the minimum value is 3 mm for the 12-inch disk and 2 mm for the 8-inch disk from the outer edge. FIG. 1 shows the case where a pattern to be a diffraction grating is recorded in this non-recorded area.

In FIG. 1, (A) is a plan view of the disk,
(B) is a partial cross-sectional view, where 1 is the outer circumference of the disc,
Reference numeral 2 is a central hole, 3 is a program recording area, 4 is a diffraction grating pattern, 5 is the back surface of the substrate, 6 is a reflective film, and 7 is a protective film. The diffraction grating pattern 4 is provided on the outer peripheral portion, which is a non-recording area, by the same method as the read-out signal in the program recording area. As the pitch of the pattern, a predetermined value is used for the recording signal and the format. For example, in order to distinguish three types, 2 μm and 3 μ are used.
m, 4 μm, and the pitches at equal intervals are determined in advance from the above according to the difference in recording signal, format, etc. Since the reflection film 6 is for forming the reflection diffraction grating by reflecting the laser light applied to the diffraction grating pattern 4 to the sensor side as described later, when forming the transmission diffraction grating, the reflection film 6 is used. Is not provided.

FIG. 2 is a schematic configuration diagram for explaining one embodiment of the reading device. In the figure, 21 is an optical disk, 22 is a diffraction grating pattern formed at equal pitches, 23 is a semiconductor laser, 24 is a power supply, 25 is a position sensor, and 26 is an arithmetic circuit. The semiconductor laser 23 and the position sensor 25 are
In the case of a player capable of playing a 12-inch disc and an 8-inch disc, it is provided at two locations corresponding to the respective outer circumferences.

The disk is set, and laser light from the semiconductor laser 23 is directed toward the diffraction grating pattern 22. In this example, the diffraction grating pattern 22 was irradiated with laser light from a direction substantially at a right angle. The position sensor 25 receives the diffracted light from the reflection diffraction grating. Pattern pitch is 2μm, 3
In the case of μm and 4 μm, assuming that the wavelength of the semiconductor laser is 780 mm, the diffraction angles are about 23 °, about 15 °, and about 11 °, respectively, and three types of discs can be discriminated. Since the first-order diffracted light is used in this embodiment, the description of the other high-order diffracted lights is omitted. Also,
The irradiation angle of the laser light with respect to the diffracted light pattern may be obliquely downward in the tangential direction. Also, not limited to the reflection diffraction grating,
A transmission diffraction grating can also be used. Since the position sensor has a predetermined diffraction angle, a photoelectric converter may be provided at each reflection position, or an optical sensor array or the like may be used. The output from the position sensor is discriminated by the arithmetic circuit, and the decoding means is selected and the read head drive mechanism is controlled.

FIG. 3 is a view for explaining another embodiment of the optical disc according to the present invention, and FIG. 3A is a plan view of the entire disc,
Part (B) of FIG. 1 is an enlarged view, and the same parts as those of FIG. In this embodiment, the diffraction grating pattern is recorded at the same track pitch as the disc. The irradiation laser light generates not only the diffracted light by the diffracted light pattern formed at equal pitches but also the diffracted light by the track pitch. The diffracted light by the track pitch is orthogonal to the diffracted light by the diffracted light pattern. As it occurs, it does not affect the detection mechanism.

The diffracted light pattern is not limited to being provided outside the recording area of the disc, but may be provided on the outside surface of the disc.

(Effects of the Invention) As is clear from the above description, according to the present invention, a newly developed disc can be reproduced by a multi-functional player regardless of the current (NTSC) standard of the optical video disc. In this case, it is possible to automatically discriminate the disc based on the recording signal and the format difference.
It is good for users.

[Brief description of drawings]

FIG. 1 is for explaining one embodiment of the optical disc of the present invention. FIG. 1A is a plan view of the entire disc, and FIG.
FIG. 2 is a partial sectional view, FIG. 2 is a schematic configuration view for explaining an embodiment of a reading device, and FIG. 3 is a view for explaining another embodiment of an optical disk according to the present invention. (A) is a plan view of the entire disc, and (B) is a partially enlarged view. 1 ... Disk outer circumference, 2 ... Center hole, 3 ... Program recording area, 4 ... Diffraction grating pattern, 5 ... Substrate back surface,
6 ... Reflective film, 7 ... Protective film, 21 ... Optical disc, 2
2 ... Diffracted light pattern, 23 ... Semiconductor laser, 25 ...
... Position sensor, 26 ... Arithmetic circuit.

Claims (2)

[Scope of utility model registration request] 1. A light which is characterized in that a pattern serving as a diffraction grating is formed on a circumference of a signal non-recording area at a pitch of a predetermined equal interval corresponding to discriminating information on a recording signal and a format of the optical disk. Disk. 2. A light beam with respect to a pattern serving as a diffraction grating formed on a circumference of the optical disk at a predetermined equal pitch corresponding to a recording signal of the optical disk and discriminating information about a format in a signal non-recording area of the optical disk. An optical disk reading apparatus comprising: a means for irradiating a laser beam and a detection means for detecting a diffraction angle of diffracted light from the pattern.