JPS61178752A - Optical disk - Google Patents

Abstract

PURPOSE:To decrease the distance between a track to be used exclusively for reproduction and a rewritable track to about 1/2 of 1.6mum, i.e., 0.8mum and to make twice higher the recording capacity over the entire part of a disk by disposing both tracks so as to adjoin alternately to each other. CONSTITUTION:The track 1 to be used exclusively for reproduction is the same as the track of the conventional optical disk consisting of pit trains to be used exclusively for reproduction. For example, an amorphous magnetic film 3 consisting of a rare earth metal-transition metal alloy which permits photomagnetic recording is used as the recording medium for the erasable tracks 2. Such optical disk can be manufactured by forming the pits for the part to be used exclusively for reproduction by a press method in the same manner as in the conventional method then depositing the film 3 thereon by a sputtering method, vapor deposition method, etc. The film 3 acts also as a reflection film of the track part to be used exclusively for reproduction.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical disc in which tracks with different recording/reproducing principles are arranged alternately. The present invention relates to an optical disc that combines tracks of an optical disc and tracks of a rewritable optical disc.

[Conventional technology]

Laser discs or compact discs that are read-only or recordable (that is, can be recorded and played back but cannot be erased), or rewritable optical discs (see, for example, Japanese Patent Application No. 57-831138)
Currently, the lowest track pitch is 1.81L. The limit of this size is determined by the spot diameter of the laser beam, and if the track pitch is less than this size, 2,000, crosstalk between adjacent tracks becomes noticeable.

[Problem that the invention seeks to solve]

The present invention utilizes changes in the intensity of reflected light to read information recorded on tracks of read-only disks, and also uses rotation of the polarization plane of light (Kerr rotation) in rewritable magneto-optical disks. Focusing on the fact that it is being used, we arranged playback-only tracks and rewritable tracks alternately adjacent to each other, and set the distance between each track to 1.8.
The purpose of this is to bring the recording capacity close to approximately 172 degrees of Bm, that is, 0.81 Lm, and to double the recording capacity of the entire disc.

In other words, when detecting changes in the intensity of reflected light and reproducing information recorded on a read-only track, even if the laser beam traces an adjacent rewritable track, the information written there, that is, the magnetization The intensity of the reflected light is not affected by the information recorded either up or down, and conversely, when reading out the recorded information by detecting the rotation of the polarization plane of the light from the rewritable track, the difference Using the dynamic detection method, even if a portion of the laser beam hits an adjacent read-only track, the change in the intensity of the light reflected from it is canceled out and does not affect the reading of information from the rewritable track. It is.

Note that, as will be described later, the optical disc according to the present invention has many forms of use.

[Means for solving problems]

As described above, the present invention includes a first track for reading recorded information by detecting changes in reflected light intensity, and a second track for reading information by detecting rotation of the polarization plane of light. Arrange them alternately.

〔Example〕

Examples of the present invention will be described in detail below.

Figure 2 shows how signals are recorded on a conventional read-only optical disc. In this diagram, 4 is a hole called a bit, and the playback laser beam is diffracted by this bit. Read the signal. Also, the tracking servo operates using this bit string. Reference numeral 5 denotes a metal reflective film, which is usually an AfL film deposited by a method such as vapor deposition. Further, 6 is a substrate made of acrylic polycarbonate or the like.

FIG. 1 shows an embodiment of an optical disk to which the present invention is applied. In this figure, l is a read-only track, which is the same as the track included in a conventional read-only optical disk consisting of a bit string. 2 is an erasable track. As a recording medium for this erasable track, for example, an amorphous magnetic film 3 based on a rare earth metal-transition metal alloy capable of magneto-optical recording is used. This optical disc is manufactured by pressing the bits in the read-only section in the same way as the conventional method.
It can be manufactured by depositing the amorphous magnetic film 3 by sputtering, vapor deposition, or the like. This amorphous metal film 3 also functions as a reflective film for the read-only track portion.

Next, let's talk about tracking.

A laser beam is irradiated to both the read-only track l and the erasable track 2, and in order to perform tracking using the read-only track l, the laser beam is separated by a diffraction grating, etc., and the read-only track l and the erasable track are separated. 2
irradiate at the same time. In this way, tracking can be performed using the reproduction-only track 1. In this case, as long as the relative relationship between the light beam on the erasable track z and the light beam on the read-only track l is maintained accurately, tracking can be performed with high precision for the erasable track 2 as well.

Furthermore, instead of separating the light from one laser using a diffraction grating or the like, a light source in which a plurality of semiconductor lasers are arranged at regular intervals can also be used. In this way, when recording the signal on the erasable track 2 while reproducing the signal on the read-only track 1, the recording laser beam can be easily modulated. However, when the rewritable track is composed of a magneto-optical recording medium, it is not necessarily necessary to modulate the recording laser beam when recording onto the erasable track z, and the laser beam is continuously directed onto the magneto-optical recording medium. It is also possible to record on erasable tracks by irradiating the magnetic field and modulating the bias magnetic field used during recording and erasing.

Furthermore, by providing a guide groove on the erasable track 2 as shown in FIG. 3, it is possible to track the laser spot on the erasable track 2 without irradiating the read-only track 1 with laser light. It is.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
The track pitch of an optical disc has been reduced to the conventional 1.81L.
Since the layer can be reduced to about half, 0.8p, the recording capacity of the entire disc can be approximately doubled.

Furthermore, by using the optical disc according to the present invention and a player that can record on and play back the optical disc, it is possible to: ■ At the same time as the karaoke accompaniment played from the playback-only track, the sound of the karaoke singer can be recorded on the adjacent erasable track. It is possible to record and then play back the accompaniment and the song at the same time. And you can delete the song when it's no longer needed.

■Take a picture of Dai singing karaoke with a TV camera, insert it into a part of the screen of a karaoke video for playback, and use the same image taken with the TV camera or the whole image with that image inserted. Images can be recorded along with audio on adjacent erasable tracks.

■When learning English conversation, you can use the recording, playback, and deletion mechanism to practice pronunciation.

Many other uses are possible, greatly expanding the range of uses for optical discs.

In addition, compared to the case where the manufacturer pre-records karaoke accompaniment on every other track on an erasable optical disc with play-only tracks, recording signals caused by incorrect operation or by bringing a strong magnet close to the It has the advantage of being able to prevent erasure.

In addition, in the embodiment shown in FIGS. 1 and 3, 1
Although there is a pair of one read-only track and one erasable track, it is also possible to arrange a plurality of tracks on each track to adapt it to more diverse purposes.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of an optical disc to which the present invention is applied, and FIG. 2 is a diagram showing an example of a conventionally known optical disc. FIG. 3 is a diagram showing another embodiment of the present invention in which a guide groove is provided in the erase track. 1... Read-only track, 2... Erasable track, 3... Amorphous magnetic film, 4... Bit, 5... Aluminum reflective film. 6...Acrylic polycarbonate.

Claims (1)

[Claims] 1) A first track in which recorded information is read out by detecting changes in reflected light intensity, and a second track in which information is read out by detecting rotation of the polarization plane of light. An optical disc characterized by alternate arrangement. 2) The first track is a read-only track consisting of a bit string, and the second track is a rewritable track formed of an amorphous magnetic film based on a rare earth-transition metal alloy. 1st
Optical disc described in section.