FIELD OF THE INVENTION
The present invention in general relates to a process for manufacturing optical discs and an apparatus for carrying out the process and in particular, to a novel process for dye dispensing, during manufacturing optical discs.
BACKGROUND OF THE INVENTION
Recordable optical" disc media is coated with an organic dye layer whose transparency is altered either to absorb a laser beam or to allow the beam to pass through to a reflective layer of the optical disc. When the internal energies of the dye molecules reach a particular threshold, the dye layer loses its transparency because of an irreversible chemical reaction. This property is exploited by a high-energy beam to write data by burning pits. A low powered laser reads the data by either passing through the transparent dye layer to the reflective layer or by being absorbed by the nontransparent marks in the dye.
Therefore the dying process is of extremely important in an optical disc manufacturing process. The dye dispensing process starts from the outer periphery of the optical disc and gradually moves towards the internal portion of the disc-that is towards the center of the disc and once again towards the outer portion of the disc.
The dye dispensing cycle time of the process is directly dependent on the distance the dye nozzle has to travel on the disc to dispense the dye on the disc. This process of starting the dye dispensing from the outer periphery of the disc leads to higher cycle time and higher consumption of the dye. This results in higher production cost of the discs.
Hence, there was a long felt need to decipher a process of dye dispensing, during the manufacturing process of an optical disc whereby the dye dispensing cycle time is reduced and consequently, the consumption of dye is brought down to a substantial level, so that, the production cost is reduced.
All through out the present specificaton, the term optical disc is meant to cover similar devices as well, unless specifically mentioned to exclude such similar devices.
Objects of the Invention
It is a principal object of the instant invention to provide an improved process for dye dispensing jn the optical disc manufacturing process.
It is another object of the instant invention to reduce the cycle time in the optical disc manufacturing process.
It is yet another object of the instant invention to optimize the dye dispensing in the optical disc manufacturing process.
It is another object of the instant invention to reduce the dye dispensing volume in the disc manufacturing process.
It is also an object of the instant invention to optimize the cost of production in
the dye dispensing process.
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Summary of the invention
Accordingly, the present invention provides a process for manufacturing optical discs including forming at least a reflective layer on said disc, followed by forming at least a coating of organic dye thereon, wherein the dispensing of dye, to form said coating of organic dye is carried out by inititation of the dye dispensing process from very near the hub of said disc to the middle of the disc, whereby consumption of dye is reduced and optical disc having uniform distribution of dye coating thereon, is obtained thereby improving the quality of the manufactured optical disc.
In accordance with preferred embodiments of the process of the instant invention:
the chuck speed of the apparatus for manufacturing optical discs varies
between 0 to 9999rpm.
-the volume of dye dispensing is reduced.
-the dispensing cycle time is reduced by reducing the distance moved by the
dye dispensing means of the dye dispensing apparatus.
The present invention also provides an apparatus for manufacturing optical
discs, wherein said apparatus includes means adapted to form at least a
reflective layer on said disc, as well as dispensing means, adapted to initiate
dispensing dye for forming at least an organic dye coating on said disc from
very near to hub of said disc to middle of said disc, whereby consumption of
dye is reduced and optical disc having uniform distribution of dye coating
thereon, is obtained thereby improving the quality of the manufactured optical disc.
In accordance with preferred embodiments of the apparatus of the invention: - said dispensing means comprises nozzle(s). The present invention also provides an optical disc manufactured by the process as described hereinbefore.
Brief Description of the Accompanying drawings
The nature and scope of the present invention will be better understood from the following non limiting description, with reference to the accompanying drawings, which are purely by way of illustration and not by way of any sort of limitation. In the accompanying drawings:
Figure 1 shows the movement of the dye dispensing nozzle in the existing process.
Figure 2 shows the movement of the dye dispensing nozzle in the process of the instant invention.
Detailed Description of the Invention.
According to the invention, in the manufacturing of optical discs, we have the changed the profile of dye dispensing profile to reduce the dye dispensing volume and the cycle time. In the inventive process dye dispensing starts from very near to the hub of the disc rather than starting from outside, to the middle of the optical storage disc. The movement of the dispensing nozzle is as shown in the accompanying figure 2. This has immensely improved the consumption of the dye . This is due to the fact that in the inventive process the distance traveled by the dispensing nozzle is less in comparison to the existing process and therefore the cycle time is lesser. This results in more economy in the dye dispensing process. This simple process step is of great importance in economizing the process considering the high volume of productionjnvolved in optical manufacturing process.
The improvement in the process is illustrated in detail in the following comparative examples of the dye dispensing profiles of the existing process vis-a vis the instant inventive process.
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From the above comparison it is clear that by changing the profile of the dye dispensing, significant improvement in the dye dispensing volume can be achieved.
The above dispensing step has also achieved better uniformity in dye dispensing and therefore overall quality of the disc is improved.
The present invention has been described with reference to some preferred embodiments only for the sake of understanding and clarity but the present invention also includes all legitimate variations within the scope of what has been described hereinbefore and claimed in the claims hereinafter.

WE CLAIM
1 .A process for manufacturing optical discs including forming at least a reflective layer on said disc, followed by forming at least a coating of organic dye thereon, wherein the dispensing of dye, to form said coating of organic dye is carried out by inititation of the dye dispensing process from very near the hub of said disc.to the middle of the disc, whereby consumption of dye is reduced and optical disc having uniform distribution of dye coating thereon, is obtained thereby improving the quality of the manufactured optical disc.
2. The process as claimed in claim 1 wherein the chuck speed of the apparatus for manufacturing optical discs varies between 0 to 9999rpm.
3. The process as claimed in any preceding claim wherein the volume of dispensing is reduced.
4. The process as claimed in claims 2 and 3 wherein the dispensing cycle time is reduced by reducing the distance moved by the dye dispensing means of the dye dispensing apparatus.
5. An apparatus for manufacturing optical discs, wherein said apparatus includes means adapted to form at least a reflective layer on said disc as well as dispensing means, adapted to initiate dispensing dye for forming at least an organic dye coating on said disc from very near to hub of said disc to middle of said disc, whereby consumption of dye is reduced and optical disc having uniform distribution of dye coating thereon, is obtained thereby improving the quality of the manufactured optical disc.
6. The apparatus as claimed in claim 5 wherein said dispensing means comprises nozzle(s).
7. An optical disc manufactured by the process as claimed in claims 1 to 4.