JPH087529Y2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an optical disk device capable of detecting a track pitch of a recording signal recorded on an optical disk and switching to an appropriate recording signal format. Is.

[Prior Art] Conventionally, the chemical-type video disk is based on the Japan Electronic Machinery Manufacturers Association standard CP-550 "optical video disk system"
The standard is defined. The outline is as follows. The track pitch is about 1.6 μm, and the recorded signal is based on the NTSC system, and the frequency displacement width is 1.7 MHz (7.6
~ 9.3MHz) FM signal, 2.3MHz and 2.8MHz audio 2
Channel FM signal and EFM signal (CD-like signal). Disk size is 12 inch disk (diameter 300mm)
There is an 8-inch disc (200 mm diameter).

On the other hand, the method of digitally recording both image and sound, and in HDTV, the MUSE signal is recorded as an FM signal with a frequency displacement width of 12.5 to 15.5 MHz, and the track pitch is narrowed to about 1.4 μm. Various methods are being considered and are being tested.

As described above, the standard of the optical video disc may be changed or diversified, but it is not easy to change the dissize in terms of manufacturing efficiency. When a disc with a different standard is on the market, even if a dedicated player is used for the time being, after that, a disc rotation mechanism, a pickup for signal detection and its drive mechanism,
It is obvious that a general-purpose reproducing device capable of reproducing discs having different recording signals and different formats is required by using the same circuit parts in common.

When using a general-purpose player, the recording signal and the discriminating signal regarding the format are recorded on the disc,
If the discriminating information is read and the player is controlled prior to playback, many types of discs can be automatically adjusted to the recording signals and formats of the discs, and the operation becomes easy. It is possible to avoid making a wrong choice. 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. The step of decrypting the discriminant signal is required, and a conventional player which does not presume to decrypt the discriminant signal cannot reproduce the disc containing the discriminant signal, which is a limitation. To remove this restriction, it is possible to manually specify the type of disk at the time of use,
Not only is it complicated, but if you forget to give instructions, playback will be hindered.

[Problems to be solved by the device]

The present invention has been made in view of the above-described circumstances, and is to detect the track pitch of a recording signal recorded on an optical disk and determine the format of the recording signal from the detected track pitch. Therefore, the optical disc device is set to the optical disc device, the track pitch of the optical disc is determined until the optical disc is rotated, and the optical disc device is switched to the recording signal format of the set optical disc to improve the compatibility of the optical disc device with the optical disc device. This is the purpose.

[Means for solving the problem]

The present invention is, in an optical disk device, an irradiation unit that irradiates a signal recording area of the optical disk with a light beam, and a reflected diffraction light of a first or higher order among the reflected return light of the light beam irradiated by the irradiation unit from the optical disk. The present invention is characterized in that a detection means for detecting a bending angle and a switching means for switching the recording signal format by the output of the detection means are provided.

[Operation] When light of wavelength λ is incident on the diffraction grating having a pitch of p, the diffraction angle θm of the diffracted light of the m-th order is given by θm = sin ⁻¹ (mλ / p). Therefore, when the pitch p of the diffraction grating is changed, the diffraction angle of the first or higher order changes. Therefore, the pitch p of the diffraction grating can be known by irradiating the light of wavelength λ and detecting the diffraction angle of the first or higher order. .

Based on this, the track pitch of the signal recording area of the optical disc is regarded as a diffraction grating, a light beam is irradiated, and the optical angle is detected by detecting the diffraction angle of the reflected and diffracted light of the first or higher order among the reflected return light. It is possible to determine the type of the optical disc without the need to do so.

〔Example〕

One embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG.

In the figure, the output of the semiconductor laser 1 having a wavelength of 780 nm is applied to the optical disc 2 as a light beam. The 0th-order light of the reflected return light is used to extract the information signal of the optical disk, and the 1st-order reflected diffracted light changes the diffraction angle θm depending on the track pitch of the track 3 of the optical disk 2. It is used as a detection signal.

For example, in the case of a video disc created according to the Japan Electronic Machinery Manufacturers Association Standard CP-550, the track pitch is about 1.6.
μm, video signal is NTSC FM signal, audio signal is FM
Signal and EFM signal are recorded. In this video disc, when irradiated with the light beam of the above wavelength of 780 nm, 1
The diffraction angle θm ₁ of the next reflected diffracted light is about 29.2 °. Also,
In a high-definition disc recording a MUSE signal, the track pitch is about 1.4 μm, so the diffraction angle θm ₂ of the first-order reflected diffracted light is about 33.9 °.

Therefore, the irradiation position of the above-mentioned light beam is set in advance, and the position detecting light receiving element 4 is installed at the irradiation position of the first-order reflected diffracted light so that the position of the element having the largest output among the position detecting light receiving elements 4 It is possible to discriminate the diffraction angle, discriminate the type of the optical disc, and switch to an appropriate recording signal format. If the irradiation position of the light beam is set on the inner peripheral portion of the signal recording surface, the problem due to the size of the optical disk does not occur.

[Effect of device]

By using the present invention, the difference in track pitch on the signal recording surface of the optical disc can be discriminated by a simple detection mechanism and circuit configuration, and the recording signal format can be switched to an appropriate one.

[Brief description of drawings]

 FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. 1 ... Semiconductor laser, 2 ... Optical disk 3 ... Track, 4 ... Light receiving element

Claims (1)

[Scope of utility model registration request] 1. In an optical disk device, an irradiating means for irradiating a signal recording area of the optical disk with a light beam, and a reflected diffracted light of a first or higher order of the reflected return light of the light beam irradiated by the irradiating means from the optical disk. 2. An optical disk device comprising: a detection means for detecting the diffraction angle of 1. and a switching means for switching the recording signal format according to the output of the detection means.