Method of manufacturing an optical recording/reproducing disc

Dynamic information storage or retrieval – Storage medium structure – Specific disc profile

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

369283, 369286, 427240, G11B 1902, B05D 138

Patent

active

045464642

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION

This invention relates to a method of manufacturing an optical recording/reproducing disc, and more particularly an optical recording/reproducing disc which is difficult to injure, and which is provided at the outer peripheral surface with a disc protecting layer to thereby protect a region for recording/reproducing signals.


BACKGROUND ART

Conventionaly, an optical recording disc has been formed by a round plastic plate having a recording layer capable of optically recording/reproducing and thereafter another plastic plate placed over the recording layer for protecting it. The protective plastic plate for the recording layer, however, has a problem in that the surface of the recording disc, when placed on a flat surface, is injured by contact with dust or foreign objects during manufacture. This has been a problem also with an optical recording/reproducing disc using a laser beam. In other words, a problem has been created in that the flaws on the protective plate will appear as noise during recording and/or reproducing of signals.


SUMMARY OF THE INVENTION

An optical recording/reproducing disc according to the invention comprises a round plastic plast, a recording layer provided on the plastic plate and enabling optical recording and/or reproducing, and a round protective layer of plastic material provided on the recording layer and having at the outer peripheral end a projection higher by 10 to 200.mu. than the inner peripheral surface at the effective recording/reproducing surface, thereby to protect the recording layer, so that when the disc is placed on a flat surface the projection of the protective layer forms a space between the recording layer and the flat surface, thereby preventing flaws from being produced by contact with dust or a foreign object.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view of an embodiment of an optical recording/reproducing disc manufactured according to the method of the invention, and
FIGS. 2, 3 and 4 are partially sectional views of outer peripheral end portions of the embodiment of FIG. 1 and of modified embodiments manufactured according to the method of the invention.


BEST MODE FOR CARRYING OUT THE INVENTION

The optical recording/reproducing disc base member of the invention, as shown in FIG. 1, mainly comprises three layers. Namely, a recording layer 2 necessary for optical recording and/or reproducing is interposed between two plastic plates 1 of acrylic resin each having a center bore and a diameter of 210 mm. In further detail, the recording layer 2 utilizes the principle that irradiation by a laser beam causes a phase transition to change the reflectivity of the layer.
FIGS. 2 and 3 are partially enlarged sectional views of a portion designated by A in FIG. 1, and each shows the disc in FIG. 1 coated with a protective layer 3. The disc in FIG. 2 is chamfered as at 4 at the corners of the outer peripheral end portion of disc, and the disc in FIG. 3 is rounded-chamfered at the same portion. A projection 6 is provided at the outermost periphery of each disc. In FIG. 4, the projection 6 of the protective layer 3 provided at the outermost peripheral end of the disc comprising the plastic plates 1 and recording layer 2 preferably has a height m as large as possible. However, when height m becomes too large, the area of projection 6 and width l thereof are increased, resulting in a poor appearance. Thus, the projection 6 preferably has a height of about 200.mu. or less from the viewpoint of the positional relation with the laser head. However, a height of 10.mu. or less has not been effective in prevention of flaws caused by dust or the like. The embodiment in FIG. 4 is obtained by a coating operation wherein a coating liquid is filled in a dip tank, and the coating material is applied simultaneously to both surfaces of the resin disc by rotating the disc by a rotary shaft, thereby simultaneously forming the protective layer 3 and projection 6.
The coating apparatus and method used for this embodiment prov

REFERENCES:
patent: 2631859 (1953-03-01), Ellsworth
patent: 3430766 (1967-04-01), Gregg
patent: 4038524 (1977-07-01), Puech et al.
patent: 4111698 (1978-09-01), Sato
patent: 4113492 (1978-09-01), Sato et al.
patent: 4175145 (1979-11-01), Fetchet
patent: 4371954 (1983-02-01), Cornet

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Method of manufacturing an optical recording/reproducing disc does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of manufacturing an optical recording/reproducing disc, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing an optical recording/reproducing disc will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2224254

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.