Coating processes – Coating by vapor – gas – or smoke – Organic coating applied by vapor – gas – or smoke
Reexamination Certificate
2000-04-05
2002-01-22
Beck, Shrive P. (Department: 2709)
Coating processes
Coating by vapor, gas, or smoke
Organic coating applied by vapor, gas, or smoke
C427S255700, C427S250000, C427S251000, C427S248100, C118S715000, C118S7230VE, C118S726000, C118S727000, C118S728000, C118S729000
Reexamination Certificate
active
06340501
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a manufacturing method and a manufacturing device for an optical recording medium having a high density, onto and from which information can be recorded and reproduced by using a laser beam, and more particularly concerns a manufacturing method and a manufacturing device for an optical recording medium capable of recording only once; that is, a so-called write-once type optical recording medium or an optical recording medium, such as CD-Rs and DVD-Rs.
BACKGROUND ART
In recent years, optical recording media have been widely used because of their high information density and ease in retrieving data. In particular, CD-Rs, which have a large capacity (650 MB) and are of comparatively low cost, have recently been extensively used. An explanation will be given of manufacturing methods and products of the optical recording media.
FIG. 1
is a schematic cross-sectional view, taken perpendicularly to the round face of a disk, of a conventional manufacturing device for forming a recording layer of a write-once type optical recording medium. This device is referred to as a spin coater.
In this Figure, reference numeral
10
is a spin coater main body,
12
is a substrate for the optical recording medium,
14
is a spindle shaft,
16
is a spindle table,
18
is an application nozzle for a recording layer solution,
20
is an organic pigment solution of a recording layer material, and
22
is a spindle motor. The organic pigment solution of the recording layer material
20
is supplied onto the optical recording medium substrate
12
through the nozzle
18
. Thereafter, when the spindle motor
22
rotates in the direction of the arrow
24
, the optical recording medium substrate
12
on the spindle table
16
is allowed to rotate at the same time, and the solution of the recording layer material
20
expands in the direction of the arrow
26
so that the solution of the recording layer material
20
is applied onto the optical recording medium substrate
12
with a uniform thickness. The organic pigment contained in the solution of the recording layer material
20
is made of a material such as a phthalocyanine pigment and a cyanine pigment.
FIG. 2
schematically shows a cross-sectional structure, taken perpendicularly to the round face of the disk, of one portion of an optical recording medium manufactured by the above-mentioned manufacturing method. In this Figure, reference numeral
28
is a minute groove provided on the surface of the optical recording medium substrate
12
,
30
is a recording layer,
32
is a reflective layer, and
34
is a protective layer. When the solution of the recording layer material is applied as described above, the solution of the recording layer material fills the minute groove
28
of the optical recording medium substrate made of polycarbonate. The solution that has been applied is dried; and thus, the recording layer is formed. The minute groove
28
is of a spiral form extending from the inner circumference of the optical recording medium substrate
12
to the outer circumference thereof.
When information is recorded on such an optical recording medium as described above, a laser beam spot
36
is irradiated onto the groove
28
from a recording device so that the pigment material of the recording layer is decomposed and/or modified, or in some cases, the substrate
12
is deformed by heat generated at this time, with the result that a pit
38
is formed.
Upon irradiation of a reproducing laser beam with an output power lower than that of the recording laser beam, the reproducing laser beam is allowed to be reflected by the reflective layer
32
formed by sputtering gold or silver. However, compared with portions that have not been subjected to the laser beam at the time of recording, the light reflection coefficient of the pit
38
is lower so that this contrast due to the difference between the reflection coefficients indicates the presence of a signal. With this mechanism, the same signal output as that of the CD disk standardized by the Red book is obtained, so that the signal is identified as a CD one. The contents explained here are the same as those standardized for the write-once optical recording medium of the CD-R in the Orange book.
DISCLOSURE OF THE INVENTION
Although the manufacture of the optical recording medium by the use of the above-mentioned spin coater is comparatively simple, this method has various problems.
First, the characteristics of the organic pigment solution of the recording layer material
20
(for example, viscosity, etc.) are highly susceptible to external factors (for example, temperature, moisture, etc.), and the applied states of the solution are not the same between the inner circumference and the outer circumference of the optical recording medium depending on the number of revolutions of the spin coater and the controlled states of the number of revolutions. This results in the film thickness of the applied solution tending to have a difference between the inner circumference and the outer circumference of the optical recording medium; and therefore, it is not easy to form a recording layer having a uniform film thickness over the substrate.
Moreover, the organic pigment solution of the recording layer material
20
is applied by using various solvents, and in general, it is necessary to sufficiently dry the solution after having been coated. Since this drying process takes a long time, it is difficult to form the recording layer in a short time with high yield, which has been a problem in reducing the production costs of the optical recording medium.
In addition, as demands for high density of the optical recording media have increased, applicability to a short wavelength laser beam (for example, 650 nm) has been demanded, and various demands, such as, for example, capability of reproducing information by a DVD player (that is, compatibility with DVD players), which information has been recorded by using a long wavelength (780 nm in the case of CDs), and improvements of the organic pigment suitable for shortened wavelengths of the laser beam, are presented. Thus, methods such as the use of laminated organic pigment layers have been proposed.
However, the above-mentioned spin coat method has a problem in which a layer that has been first applied tends to be damaged by a solution of a recording layer material that is applied later at the time of rotation at high speeds. Moreover, size reduction of the pitch between grooves has been proposed in order to achieve the high density.
The above-mentioned conventional method has a limitation in its capability for solving these problems.
The present invention provides a manufacturing device of an optical recording medium for solving the above-mentioned problems. Specifically, the present invention provides a device for manufacturing an optical recording medium comprising a plurality of recording layers on a substrate, which device comprises a vacuum pre-treatment chamber, a plurality (at least two) of recording layer forming a chambers each for forming a recording layer by vapor deposition, a reflective layer forming chamber and a vacuum post-treatment chamber. Each recording layer forming chamber is provided with at least one recording layer forming unit, and the reflective layer forming chamber is provided with at least one reflective layer forming unit.
The optical recording medium manufacturing device of the present invention further comprises a substrate transporting mechanism, and this mechanism transports the substrate between chambers in the device. Therefore, by the substrate transporting mechanism, the substrate for the optical recording medium, which has been carried into the vacuum pre-treatment chamber inside the device, is transported from the vacuum pre-treatment chamber, through the recording layer forming chambers and the reflective layer forming chamber, to the vacuum post-treatment chamber, and discharged from the vacuum post-treatment chamber.
As will be described later, for example, in an embodim
Kamiyama Toshifumi
Kunieda Toshiaki
Okazaki Sadayuki
Beck Shrive P.
Markham Wesley
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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