JPH0452995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical information recording medium, and more particularly to a card-shaped optical information recording medium provided with a track for obtaining a tracking signal and a clock signal.

[Prior art]

2. Description of the Related Art Conventionally, various types of media such as disks, cards, and tapes have been known as media for recording information using light and for reading recorded information.
Among these, card-shaped optical recording media (hereinafter referred to as optical cards) are expected to be in great demand as small, lightweight, easily portable media with a large storage capacity.

By the way, the above-mentioned optical card uses a light beam that is modulated according to recorded information and focused on a minute spot.
By scanning the card, information is recorded as an optically detectable recording bit sequence (information track). At this time, in order to accurately record information without causing problems such as crossing of information tracks, it is necessary to control the irradiation position of the light beam in a direction perpendicular to the scanning direction (auto tracking, hereinafter referred to as AT). It was necessary to do so. Furthermore, in order to correct variations in scanning speed, it was necessary to obtain a clock signal. Therefore, the applicant
Drexler Technology
According to a technical disclosure received from J.D. Corporation, an optical card has been proposed in which a track for obtaining a tracking signal and a clock signal is formed on the card in advance. A first example of such an optical card is shown in FIG.

FIG. 3A is a schematic plan view of the optical card. Here, a clock signal is recorded in advance on the optical card 31, and clock tracks 32 ₁ , 32 ₂ , 32 ₃ , 32 ₄ . . . formed in the form of intermittent broken lines are arranged at equal intervals. . Between the clock tracks are recording areas 34 ₁ and 3 for recording information.
4 ₂ , 34 ₃ ... are provided.

FIG. 3B shows an enlarged view of the recording surface of the optical card 31. When recording information on this optical card, three beams are emitted from the optical head, and each beam is focused into minute spots S ₁ , S ₂ , and S ₃ .
These spots are scanned in the direction of the arrow a by the relative movement of the optical card and the optical head, and information is stored in the recording area ₃₄₁ as in the recording pit 35 by the center spot _S2 . recorded. Further, the reflected light from either spot _S1 or _S3 is guided to a detection means within the optical head, and a tracking signal is detected using a well-known method such as a so-called push-pull method. Based on this tracking _{signal , the} spots
The position of the spot S1 is controlled so that the spot _S1 always accurately traces the clock track ₃₂₁ . Therefore, the recording pits 35 are formed accurately along the clock tracks ₃₂₁ , and it is possible to prevent the information tracks from crossing over. At the same time, a clock signal is reproduced from the reflected light from spot _S1 or _S3 , and is used as a clock for the recording signal.
Information is also reproduced in the same manner.

However, in optical cards, the transfer speed of the card during recording or reproduction is generally slow, so the frequency of fluctuations in the tracking signal due to the discontinuity of the clock track is close to the AT servo band, which has the disadvantage of adversely affecting the AT. It was hot.

Therefore, a second example of an optical card that solves the above drawbacks is proposed in the above-mentioned technical disclosure. This is shown in FIG. FIG. 4A is a schematic plan view, in which the optical card 41 has recording areas _{44 1} , 44 ₂ .
2 ₂ , 42 _{3 .} . . and tracking tracks 43 ₁ , 43 ₂ , 43 _{3 . .} . are formed on the other side, respectively. Here tracking track 43 ₁
... has a continuous linear form.

FIG. 4B shows an enlarged view of the recording surface of the optical card 41. In this optical card as well, three spots are basically scanned in the direction of arrow a, as in the example shown in FIG. 3, and the recording pit 45 is recorded by spot _S2 .
However, in this example, the tracking signal is obtained by tracing the tracking tracks 43 ₁ , 43 ₂ . . . at spot S ₃ . Further, the clock signal is obtained from the spot S ₁ irradiated onto the clock tracks 42 ₁ , 42 ₂ . Therefore, in this example, the tracking signal can be detected completely independently of the clock signal, and accurate AT is possible.

However, the optical card 41 requires a larger area for a tracking track than the example shown in FIG. 3, and the recording capacity per area is inevitably reduced.

[Summary of the invention]

The purpose of the present invention is to solve the drawbacks of the prior art, and to solve the problems of the prior art without reducing the recording capacity per area.
The purpose of the present invention is to provide an optical information recording medium that enables accurate AT.

The above-mentioned object of the present invention is to provide a plurality of tracking tracks, each consisting of a continuous line, which generates a tracking signal, and a plurality of tracking tracks, each consisting of an intermittent broken line, arranged alternately with the tracking tracks and generating a clock signal. a clock track, and a recording area for recording information arranged between each track, and between the two adjacent recording areas, one of the tracking track and the clock track is provided. This is achieved by using a card-shaped optical information recording medium, which is characterized in that only tracks of .

〔Example〕

FIG. 1 shows an embodiment of an optical card according to the present invention, in which A is a schematic plan view of the card and B is an enlarged view of the recording surface of the card. At A, clock signals are recorded in advance on the optical card 1, and clock tracks 2 ₁ , 2 ₂ , 2 ₃ , . . . are formed in the form of intermittent broken lines.
... and tracking tracks 3 ₁ , 3 ₂ ... formed in a continuous linear shape are alternately arranged at equal intervals. Recording areas 4 ₁ , 4 ₂ , 4 ₃ . . . for recording information are provided between each track. That is, the optical card 1 has a recording area in the entire area between the clock track and the tracking track.

When recording information on the optical card 1, first place the spots S ₁ , S ₂ , and S ₃ as shown in B so that S ₁ is above the clock track 2 ₁ and S ₃ is above the tracking track 3 ₁ . irradiate. Spots _S1 to _S3 are scanned in the direction of arrow a by relative movement of the optical head and optical card that form these spots. Here, a clock signal is reproduced from the reflected light from spot _S1 . In addition, the reflected light from the spot _S3 is guided to a detection means in the optical head, and the so-called push-pull method, etc.
Tracking signals are detected using well known methods. Based on this tracking signal, the spot
S ₁ , S ₂ , and S ₃ are moved together in a direction perpendicular to the scanning direction (b direction) to perform AT. By this,
Recording pits 5 are accurately recorded in the recording area ₄₁ along the tracking track ₃₁ by the spot _S2 . Next, when recording information in the recording area ₄₂ , the spots are irradiated as _S1 ', _S2 ', and _S3 ', and the clock signal is reproduced from the clock track ₂₂ by _S3 '. Also, a tracking signal is obtained from tracking track ₃₁ by S1 _' .
While performing AT, information is recorded using S ₂ ′.
By switching operations like this, information can be recorded in all recording areas. Here recording area 4
₁ and ₄₂ may be recorded with different optical heads, or may be recorded with the same optical head.

Reproduction of the information recorded as described above is also performed in the same manner as during recording. On the recording surface of the optical card,
As shown in FIG. 2, information tracks 25 ₁ , 25 ₂ . . . consisting of recording pit rows are formed between clock tracks _{2 1} , 2 _{2 .} . . and tracking tracks 3 ₁ . First, when reading the information on the information track 25 ₁ , three spots S ₁ , S ₂ ,
Information is reproduced by irradiating as shown in S ₃ , reproducing the clock signal from S ₁ , and detecting the reflected light from S ₂ while performing AT using the tracking signal from S ₃ . Next, when reading the information on the information track ₂₅₂ , the spots are irradiated as S ₁ ′, S ₂ ′, and S ₃ ′, and S ₃ ′ is used to reproduce the clock and S ₁ ′ is used for tracking. Playback is performed at ₂ ′. By switching operations like this, information recorded in any area of the optical card can be reproduced.
In this way, the optical head for reading information may be the same as the head used for recording, or a different optical head may be used. Furthermore, when reproducing recorded information, the clock can be extracted from the signal itself recorded on the information track (so-called self-clock), and it is not always necessary to reproduce the clock signal from the clock track. Therefore, various reproduction methods can be considered in addition to the example shown in FIG.

The present invention is not limited to the reflective optical card of the embodiment.
It can also be applied to a transmissive type that records and reproduces information by detecting light transmitted through an optical card. For example, in the case of a reflective type, the tracking track and the clock track are formed in advance in the form of a change in reflectance, absorption spectrum, or a phase change due to unevenness. In the case of a transmission type, changes in transmittance, refractive index, absorption spectrum, unevenness formation, etc. can be similarly utilized. Furthermore, these tracks may have a fine structure such as a diffraction grating inside. Furthermore, the recording pits when recording information may be written on the same principle as tracking tracks or clock tracks on the recording surface by irradiation with spot light, or they may be formed in a form different from these. You may do so.

According to the present invention, no matter where information is recorded in the recording area, the tracking signal can be detected by the tracking track on either side of the recording area. It is possible to perform accurate AT that is not affected by signals. Furthermore, since each track has a recording area, it has a larger recording capacity per unit area than the example shown in FIG.

〔Effect of the invention〕

As explained above, the present invention has an optical card in which tracking tracks and clock tracks are arranged alternately and a recording area is provided between each track, thereby increasing the recording capacity per unit area. This has the effect of improving AT accuracy without reducing it.

[Brief explanation of the drawing]

1A and 1B are diagrams illustrating embodiments of the optical card according to the present invention, and FIG. 2 is an enlarged view of the recording surface of the optical card shown in FIG. 1, illustrating a method for reading information,
FIGS. 3A and 3B and 4A and 4B are diagrams illustrating examples of conventional optical cards, respectively. 1...Optical card, ₂₁ , ₂₂ , ₂₃ ...Clock track, ₃₁ , ₃₂ ...Tracking track,
4 ₁ , 4 ₂ , 4 ₃ ... recording area, S ₁ , S ₂ , S ₃ , S ₁ ',
S ₂ ′, S ₃ ′... Spot.

Claims (1)

[Scope of Claims] 1. A plurality of tracking tracks, each consisting of a continuous line, which generates a tracking signal, and a plurality of tracking tracks, each consisting of intermittent broken lines, which are arranged alternately with the tracking tracks and generate a clock signal. a clock track, and a recording area for recording information arranged between each track, and between the two adjacent recording areas, one of the tracking track and the clock track is provided. A card-shaped optical information recording medium characterized in that only tracks of the following are arranged.