Dynamic information storage or retrieval – Storage medium structure – Optical track structure
Reexamination Certificate
2001-08-24
2003-07-01
Dinh, Tan (Department: 2653)
Dynamic information storage or retrieval
Storage medium structure
Optical track structure
C369S275300
Reexamination Certificate
active
06587424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid disc of a dye membrane recording type having a read-only area and a recordable area.
2. Description of the Related Art
A read-only optical disc, such as a CD (Compact Disc) of a read only type has become widespread. Such a read-only optical disc has phase pits to record information. Each phase pit is formed such that its depth is equal to one-four wavelength &lgr; of a light beam used for reproduction, i.e., &lgr;/
4
.
On the other hand, a recordable optical disc is developed. Especially, as one type of the recordable optical disc, a write once type optical disc, such as a CD-R (CD-Recordable) and the like is frequently developed. Such a write once type optical disc has a recording layer composed of a dye membrane. When information is recorded on the write once type optical disc, a light beam modulated such that its intensity is changed depending on the information is emitted onto the recording layer. Thereby, reflectance of the dye membrane at the irradiated part is changed. Thus, the information is recorded on the disc. When reproducing, the recorded information is reproduced on the basis of a change of reflectance.
Here, in the above mentioned write once type optical disc, the intensity of the light beam used for recording is alternatively changed between a first intensity and a second intensity. Namely, when the information to be recorded onto the disc is a high level, the intensity of the light beam is the first intensity. When the information is a low level, the intensity of the light beam is the second intensity. The second intensity is weaker than the first intensity, and the second intensity is roughly or accurately equal to the intensity of a light beam used for reproduction. When the information is recorded on the disc, reflectance of the dye membrane is changed by switching over the intensity of the light beam between the first intensity and the second intensity. In order to increase the intensity of the light beam, it is preferable that the light beam is efficiently used.
Furthermore, when the information is recorded on the write one type optical disc, it is necessary that the light beam is accurately emitted on the target track in order to record the information on it accurately. Therefore, a tracking control is performed. Various kinds of methods to perform the tracking control have been developed. In view of the efficiency of the light beam, a push-pull method is preferably used as the tracking control for recording information on the write once type optical disc. In the push-pull method, a single light beam is used for both recording and the tracking control. In case that the tracking control is performed by using the push-pull method, in order to increase a level of a tracking error signal to the maximum, it is necessary that height (depth) of the information track of the write once type optical disc is one-eight waveform &lgr; of the light beam, i.e., &lgr;/
8
.
Therefore, in the write once type optical disc, in view of both recording and reproduction, a predetermined value between &lgr;/
8
to &lgr;/
4
is set as the depth of the information track.
Here, in view of the recent development of multimedia, an optical disc having the function of the read-only optical disc and the function of the write once type optical disc is desired.
However, it is difficult to realize such an optical disc (Hereinafter, it is referred to as a “hybrid disc”.). The reason is that the depth of the phase pit of the read-only optical disc is different from that of the information track of the write once type optical disc. Namely, the depth of the phase pit of the read-only optical disc is &lgr;/
4
, but the depth of the information track of the write once type optical disc is the predetermined value between &lgr;/
8
to &lgr;/
4
(not &lgr;/
4
). It is very difficult in view of a yield to form the phase pit and the information track each having different depth on a single disc.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide a hybrid type dye record medium which can be easily produced.
Furthermore, it is a second object of the present invention to provide a record disc producing apparatus which can easily produce a record disc, such as a hybrid type dye record medium.
Moreover, it is a third object of the present invention to provide an information reproducing apparatus which can surely reproduce information recorded on a hybrid type dye record medium.
According to the present invention, the above mentioned first object can be achieved by a dye record medium provide with: a substrate having a track-forming-surface divided into a read-only area and a recordable area; a reproducing track formed on the track-forming-surface in the read-only area, and constructed by an arrangement of a plurality of pits, each of the pits comprising a dye material, having a shape corresponding to reproducing information, and having a constant predetermined height; and a recording/reproducing track formed on the track-forming-surface in the recordable area, and extending continuously, the recording/reproducing track comprising the same dye material as each of the pits, and having the same predetermined height as each of the pits.
Namely, the dye record medium has a two areas, i.e., the read-only area and the recordable area. In the read-only area, reproduction information is recorded on the track-forming-surface in advance as the reproducing track constructed by the arrangement of the plurality of pits. In the read-only area, reproducing the reproducing information is possible, but recording a new information is impossible. On the other hand, in the recordable area, both recording new information and reproducing the recorded information are possible.
In the read-only area, the reproducing track is formed. The reproducing track is constructed by the arrangement of the plurality of the pits. Each pit has a shape corresponding to the reproducing information. Namely, the shape of each pit is changed depending on conditions of the reproducing information. Thereby, when the reproducing track is irradiated with the light beam, reflectance of the light beam is changed on the basis of the shape of each pit. Furthermore, each pit is composed of at least dye material. Moreover, each pit having a constant predetermined height. The height means a length between the track-forming-surface and the top of the pit.
In the recordable area, the recording/reproducing track is formed. Unlike the reproducing track, the recording/reproducing track continuously extends. Namely, as the recording/reproducing track does not have pits, there is no break or gap in the recording/reproducing track.
Furthermore, the recording/reproducing track is compose of at least the same dye material as each of the pits of the reproducing track. Moreover, the recording/reproducing track has the same predetermined height as each of the pits of the reproducing track.
Accordingly, when the dye record medium is produced, the reproducing track and the recording/reproducing track can be simultaneously produced in the same process. As a result, it is possible to simplify the production process of the dye record medium and to produce the dye record medium easy.
Moreover, since the reproducing track is constructed by the arrangement of the plurality of pits each having the shape corresponding to the reproducing information, it is possible to reproduce the reproducing information surely.
Furthermore, the top surface of each of the pits and the top surface of the recording/reproducing track may be in the same plane. Accordingly, when the dye record medium is produced, the reproducing track and the recording/reproducing track can be simultaneously produced in the same process. As a result, it is possible to produce the hybrid type dye record medium easy.
Moreover, the substrate of the dye record medium has: a base; a reflective layer formed on the base, for reflecting the light beam; and a dye membrane formed on the reflec
Inoue Akiyoshi
Kuroda Kazuo
Taniguchi Shoji
Dinh Tan
Pioneer Electronic Corporation
Young & Thompson
LandOfFree
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