Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-02-02
2002-08-27
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C264S001330
Reexamination Certificate
active
06440248
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to information recording media in the form of light-readable discs, and more particularly to such media which are made up of two such discs secured to one another back to back to form a two-sided stack.
Light-readable information recording media in the form of discs are well known as shown, for example, by Kramer U.S. Pat. No. 5,068,846. Commercially available compact discs (“CDs”) and compact disc read-only memories (“CD-ROMs”) are examples of recording media of this general type.
More recently, digital versatile discs (“DVDs”) have emerged wherein light-readable information technology is employed to record movies and other similar real-time audio/visual programming (hereinafter “program information”) on discs. To increase program information storage capacity, DVDs are formed from two discs (similar in appearance to conventional audio CDs) bonded back to back (see, for example, Marquardt U.S. Pat. No. 5,729,533, the entire contents of which are hereby incorporated by reference). Because relatively long audio/visual programs will not fit on one disc of conventional audio CD size, the “backside” disc (i.e., the second disc bonded to the back of the “frontside” or first disc) of a DVD may often contain “spillover” audio/visual program information (i.e., information which would not fit on the frontside of the DVD).
DVDs come in two forms: (1) DVDs wherein frontside program information is read by shining a laser beam on the frontside disc and wherein spillover program information is read by shining a laser beam on the backside disc (i.e., two-side-readable DVDs); and (2) DVDs wherein both frontside program information and spillover program information are read by shining a laser beam on the frontside disc (i.e., single-side-readable DVDs). The placement of graphical image data on and the formation of two-side-readable DVDs are described in previously incorporated Marquardt U.S. Pat. No. 5,729, 533.
A two-side-readable DVD according to the Marquardt patent is shown in
FIG. 1
a
. It comprises first and second discs
120
and
140
bonded to one another back to back to form a stack. Disc
120
typically includes a transparent plastic substrate
122
, the upper surface of which is patterned as shown at
124
to record programming information. The patterned surface
124
is covered with a layer
126
of highly reflective material, such as aluminum. To protect the reflective layer
126
, a resin layer
128
is deposited on the side of layer
126
which faces away from the pattern
124
. Disc
140
is bonded to the exposed surface of layer
128
, for example, by means of a hot melt glue layer
130
.
Modifying a surface of disc
140
to provide visible indicia on that disc is also shown in
FIG. 1
a
. In this embodiment technology similar to that used to record programming on disc
120
is used to provide visible indicia on disc
140
. Thus in this embodiment disc
140
includes a transparent plastic disc
142
with a pattern
144
of surface modifications on one side. Pattern
144
is covered by a layer
146
of highly reflective material such as aluminum. Layer
146
is protected by a layer of lacquer
148
. Pattern
144
includes at least two kinds of regions
144
a and
144
b
. In regions
144
a
pattern
144
includes many small features. In regions
144
b
, however, pattern
144
is smooth over relatively large areas. Light passing into disc
142
is reflected back through the disc visibly very differently depending on whether the reflection is from a region
144
a
or a region
144
b
. Regions
144
a
tend to scatter the light and therefore appear frosted, while regions
144
b
have a more mirror-like appearance. These visibly contrasting regions can be used to provide any desired visible indicia. For example, line work for lettering or to outline graphics can be provided by lines done like regions
144
b
against a background like regions
144
a
. Or lines done like regions
144
a
can be against a background done like regions
144
b
. Figures can be done with large areas like regions
144
a against a background like regions
144
b
. Or a figure can be done with large areas like regions
144
b
against a background like regions
144
a
. Halftone-type shading can be provided by alternating regions like
144
a
and
144
b
. Visible indicia produced in this way are sometimes referred to herein as “pit art” because of the use of “pits” like those in pattern
124
to produce some of the features of the indicia. Constructing two-disc stack
110
c
as shown in FIG.
1
(
a
) has the additional advantage that a portion of pattern
144
can be used to record some generic information that is light-readable for playback in the same way that the programming information can be played back from pattern
124
.
The formation of the single-side-readable DVD is completed by bonding a second, backside program information disc to the first, frontside program information disc. The second disc is similar to the first disc, having third and fourth surfaces opposite one another and having spillover program information recorded on it by means of local changes in the distance of the fourth surface from the third surface. The single-side-readable DVD is formed by bonding the first and second discs back to back so that the fourth surface of the second, backside disc faces the second surface of the first, frontside disc.
Unlike the frontside disc, only a portion of the backside disc contains program information (e.g., only the portion required to record the spillover program information). Furthermore, the fourth surface of the backside disc is coated with a reflective coating (e.g., greater than 70% reflective for a wavelength of approximately 635 to 650 nanometers) rather than a semi-reflective coating. The reflective coating allows the second portion of the light beam (transmitted through the semi-reflective coating of the frontside disc) to reflect toward and re-transmit through the semi-reflective coating and the frontside disc.
Accordingly, to read program information from the second surface of the frontside disc, a laser beam is focused on the second surface and the light reflected therefrom is detected and interpreted. Program information is similarly read from the fourth surface of the backside disc by focusing a laser beam through the frontside disc and on the fourth surface and detecting and interpreting the light reflected therefrom.
Because in a single-side-readable DVD program information stored on the backside disc is read through the frontside disc rather than through the backside disc, the third surface of the backside disc is unused by a DVD player. Graphical information (e.g., textual instructions, artwork, etc.), therefore, may be stored on the third surface of the backside disc without affecting the DVD's playability. Conventionally, graphical information is placed only on the third surface of the backside disc, and as such, graphical information is not viewable from the frontside of the DVD. This ensures that the program information stored on the second surface of the frontside disc and on the fourth surface of the backside disc remains readable.
Nonetheless, it is desirable to have graphical information viewable from the frontside of a single-side-readable DVD so as to provide textual instructions, artwork, and the like. However, such graphical information must not affect the playability of the DVD.
In view of the foregoing, it is an object of this invention to provide methods for transferring or translating graphical information to a single-side-readable DVD so that the graphical information is viewable from the frontside disc of the DVD and so that the playability of the DVD is unaffected.
SUMMARY OF THE INVENTION
These and other objects of the invention are accomplished in accordance with the principles of the invention by providing methods for transferring or translating graphical information to a single-side-readable DVD so that the graphical information is viewable from the frontside disc of the DVD and so that the playabilit
Ball Michael W.
Fish and Neave
Jackson Robert R.
Piazza Glayds
WEA Manufacturing Inc.
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