Stock material or miscellaneous articles – Circular sheet or circular blank
Reexamination Certificate
1999-06-02
2001-04-10
Evans, Elizabeth (Department: 1774)
Stock material or miscellaneous articles
Circular sheet or circular blank
C428S064200, C428S064400, C428S065200, C428S913000, C430S270110, C430S495100, C430S945000, C369S283000, C156S295000
Reexamination Certificate
active
06214432
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of optical disc manufacturing, and more particularly, relates to a method for controlling the bonding layer thickness between two optical discs forming an optical storage apparatus and the optical storage apparatus resulting therefrom. The present invention is further directed to a method of controlling the bonding layer thickness of a DVD-9 optical disc.
BACKGROUND OF THE INVENTION
In order to control the bonding layer thickness between flat panel displays, such as LCD's, microspheres have been used to set the distance between two substrates. This is important for achieving the electrical requirements of flat panels, such as contrast, speed of display, etc. Optical disc manufacturing requires similar control of bonding layer thickness, although for different reasons. The method of using microspheres has been modified as set forth herein and advantageously utilized in the manufacturing of optical discs, in order to improve the bonding layer uniformity.
Some prior solutions have used the center hole burr from the punch and die process in the optical disc manufacturing process as being about the correct thickness and have relied on this thickness. In another previous attempted solutions, a calculated mass has been used to apply pressure to the two discs as they are being bonded to obtain the correct thickness. However, these prior solutions to control the bonding layer thickness between optical discs have been found to be disadvantageous in that (1) the thickness of the bonding layer is dependent upon other processes, (2) the thickness of the bonding layer does not tend to remain consistent across the entire disc, and (3) the thickness of the bonding layer may vary across the disc with respect to the pressure applied thereto.
Moreover, in manufacturing DVD-9 optical discs, any method to control the bonding adhesive thickness must meet its lateral and parallelism requirements. A schematic representation of the lateral requirements of a DVD-9 optical disc is shown in FIG.
1
. This specification for overall bonding layer thickness is set at 55±15 &mgr;m and is required because the player must be able to focus on both the top and bottom discs. In addition, the focus servo has to have the ability to move within this specification. It has been found that a thickness greater than this specification can cause errors in reading information on the disc.
The parallelism requirements of a DVD-9 disc are schematically illustrated in FIG.
2
. In a DVD-9 disc, the specification for variation of the thickness of any one disc is ±10 &mgr;m. In addition, the specification for thickness differences within one revolution is ±4 &mgr;m. These specifications are required because the focus servo will not be able to respond quickly enough to compensate for greater changes. If the focus servo is not so able to respond, errors in reading information on the disc result. Furthermore, if the disc is not parallel, it will be unbalanced. As technology calls for faster players, such as 24x or 32x, this unbalance will cause the disc to wobble thereby contributing to even lower performance.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide a method for controlling the bonding layer thickness in an optical storage apparatus which avoids the aforementioned deficiencies of the prior art.
It is also an object of the present invention to provide a method for controlling the bonding layer thickness of a DVD disc, and more particularly, a DVD-9 disc.
It is a further object of the present invention to provide a method for controlling the bonding layer thickness in an optical storage apparatus which provides for a uniform bonding layer thickness and is relatively easy to control.
It is another object of the present invention to provide a method for controlling the bonding layer thickness of an optical storage apparatus wherein the thickness attained is not dependent on other processes.
It is yet a further object of this invention to provide a method for controlling the bonding layer thickness of an optical storage apparatus wherein the bonding thickness tends to remain consistent across the entire disc.
It is yet another object of this invention to provide a method for controlling the bonding layer thickness of an optical storage apparatus wherein the bonding layer thickness does not vary across the disc with respect to the pressure applied thereto.
It is yet still a further object of the present invention to provide a method for controlling the bonding layer thickness of an optical storage apparatus which meets the lateral and parallelism requirements of a DVD-9 bonding layer.
It is yet still another object of the present invention to provide a method for controlling the bonding layer thickness of an optical storage apparatus which retains the aesthetic qualities of the disc.
It is yet still another object of the present invention to provide an optical storage apparatus which has a uniform bonding layer thickness.
It is yet still a further object of the present invention to provide a DVD-9 disc which has a uniform bonding layer thickness.
Various other objects, advantages and features of the present invention will become readily apparent from the ensuing detailed description and the novel features will be particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, a method for controlling the bonding layer thickness between facing surfaces of two optical discs during manufacture of an optical storage apparatus is provided wherein a plurality of microspheres of a predetermined diameter are selectively placed on a facing surface of one of the two optical discs. A bonding material is placed on the facing surface of the other of the optical discs. Pressure is then applied to the two optical discs to form a substantially uniform thickness of the resulting optical storage apparatus upon curing of the bonding material.
In another aspect of the present invention, an optical storage apparatus is provided which includes two optical discs having a plurality of microspheres of uniform diameter selectively placed in a bonding layer therebetween to thereby provide a uniform thickness of the bonding layer.
The above, and other objects, features and advantages of the present invention will become apparent in the following detailed description of certain preferred embodiments which are to be read in conjunction with the accompanying drawings, and in which like reference numerals are used to identified the same or similar parts in the several views.
REFERENCES:
patent: 4740947 (1988-04-01), Ohta
Chullino, Jr. David Jeffrey
Russell Robert Lowell
Evans Elizabeth
Frommer William S.
Frommer Lawrence & Haug LLP.
Ryan Matthew K.
Sony Corporation
LandOfFree
Method for controlling the bonding layer thickness in an... 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 for controlling the bonding layer thickness in an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling the bonding layer thickness in an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2523060