Process and device for coating disc-shaped data storage media

Details Process and device for coating disc-shaped data storage media Process and device for coating disc-shaped data storage media

1998-11-13

2001-03-20

Beck, Shrive (Department: 1762)

Coating processes

Centrifugal force utilized

C427S162000, C427S425000, C118S052000, C118S320000

Reexamination Certificate

active

06203849

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a method for coating data storage media with a coating medium that is applied by at least one coating nozzle in the inner area of the storage medium and is distributed thereon by rotation of the storage medium due to the resulting centrifugal force. The invention relates furthermore to a device for performing the aforementioned method.
Disc-shaped data storage media are, for example, compact discs (CDs), mini discs, magneto-optical discs, CD-ROMs, CD-Rs, photo and/or video discs. In the following, such discs are referred to as disc-shaped data storage media or, for short, storage media.
Devices of the aforementioned kind are produced and distributed by the assignee of this patent.
FIG. 5
shows a schematic representation of the device, respectively, of the sequence of the coating and drying process at the respective stations of this device.
At a supply station
1
the disc-shaped data storage media
2
are received by a manipulation device
3
, in the shown case a so-called process cup gripper, comprising gripper arms
4
,
5
facing the supply station
1
which grip the storage media
2
supplied by the supply station
1
and transport them to the coating stations
6
,
7
of a processing unit
8
. After coating of the storage media
2
with a coating medium, for example, a coating lacquer, the storage media
2
are transported by the gripper arms
10
,
11
facing the drying station
9
to a receiving position
12
from where they are transported into a drying chamber
13
. After the drying process, the storage medium
2
is transported from the drying chamber
13
into a position
14
within the drying station in which a further gripper
15
grips it and transports it into the receiving station
16
.
The afore disclosed coating devices for disc-shaped data storage media have been used successfully in the production of such storage media.
It is an object of the invention to improve coating processes and devices for disc-shaped information storage media and to provide devices which, per time unit, allow more coating steps, which are more reliable and need less downtime, and which provide for a reduced manufacturing and service expenditure, especially for the coating stations.
SUMMARY OF THE INVENTION
Based on the aforementioned method this object is inventively solved in that at least one coating nozzle in a first movement step is moved fast into the vicinity of the coating medium application location and in a second movement is slowly positioned at the application location. With the first fast movement the coating nozzle is moved in a short period of time into the vicinity of the coating medium application location in order to keep the application process as short as possible and to increase the productivity of the method. With a fast movement, however, at least in context with hydraulic drive devices, it is not possible or possible only with great expenditure to position the coating nozzle exactly at the location at which the coating medium is to be applied within the inner area of the storage medium. When the coating nozzle, on the one hand, is not brought far enough into the inner area toward the selected optimal application location, an undesirable area of the storage medium remains uncoated. When the coating nozzle is moved past the optimal location of application radially inwardly, an undesirable coating of the inner edge of the cutout portion of the storage medium within the inner area or of an inner annular portion of the storage medium which is used for manipulating the storage medium occurs. This holds especially true for modern, state-of-the -art CDs which, in contrast to the conventional CDs, have a cutout of only 15 mm diameter instead of an inner cutout of 35 mm. Furthermore, CDs have an annular groove in the inner area which forms at the opposite side of the storage medium an annular projection. When the coating nozzle is moved by the first fast movement to this annular groove or to the annular projection, the coating medium is applied to the groove or projection which is not desirable. During the subsequent spinning process, this results in a non-uniform distribution on the surface of the storage medium and results in strips and non-uniform thickness of the coating across the surface of the storage medium. These disadvantages are avoided with the inventive feature of the present invention in that a second movement is provided which moves the coating nozzle, after the first fast movement, slowly to the location of application.
Preferably, the velocity with which the coating nozzle is moved during the first and/or second movement can be adjusted according to the respective specifications. Thus, it is possible to individually adjust the movement velocities of the first and second movements to the respective process steps, different storage media and/or coating media.
According to a further very advantageous embodiment, the first fast movement is carried out with the storage medium being stationary, while during the second slow movement the storage medium is moved so that, when the coating nozzle is positioned at the selected location of application, the coating medium can be applied immediately and spun across the storage medium. In this manner it is possible to further shorten the coating process.
Based on a device for coating of disc-shaped data storage media with a coating medium, comprising of rotatable support for the storage medium and at least one coating nozzle, which comprises a drive unit for moving the coating nozzle across the storage medium to the location of application of the coating medium, the aforementioned object is solved in that the drive unit is a hydraulic arrangement with a first hydraulic cylinder for a first fast movement and a second hydraulic cylinder for a second slow movement of the coating nozzle. The aforementioned advantages mentioned in context with the inventive method also apply to the inventive device.
In general, it is possible to use as the drive unit for moving the coating nozzle a step motor that is controllable with respect to the drive velocity. Step motors for this purpose, however, are more complicated and expensive than hydraulic arrangements so that the latter provide a substantial advantage with respect to economic considerations.
According to an advantageous embodiment of the invention, the second hydraulic cylinder takes over the drive of the coating nozzle after completion of the driving action by the first hydraulic cylinder. Especially advantageous is an embodiment according to which the second hydraulic cylinder acts counter to the first hydraulic cylinder during the second slower movement. The first hydraulic cylinder thus realizes the movement of the coating nozzle up to the application location or to a point shortly before, and the movement is then slowed by the second hydraulic cylinder. The second hydraulic cylinder serves in this embodiment as a braking cylinder for the first hydraulic cylinder.
It is advantageous when the cylinder velocity of the first and/or second hydraulic cylinder is selectable, adjustable, controllable and/or governable. The first and/or second hydraulic cylinder comprises thus advantageously a respectively adjustable fluid throttle.


REFERENCES:
patent: 4267212 (1981-05-01), Sakawaki
patent: 4353937 (1982-10-01), Chiba et al.
patent: 4451507 (1984-05-01), Beltz et al.
patent: 4807356 (1989-02-01), Maruyama et al.
patent: 4837757 (1989-06-01), Okada et al.
patent: 5989632 (1999-11-01), Sanada et al.
patent: 3626029 (1987-02-01), None
patent: 0489328 (1992-06-01), None
patent: 0618504 (1994-10-01), None
patent: 0677334 (1995-10-01), None

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