Apparatus and method for manufacturing compact discs having a non-round outer profile

An apparatus and method for manufacturing compact discs (2) having a non-circular outer profile (8) includes imprinting digital information in an annular region (12) on the under face of a compact disc blank (36) such that an outer limit (14) of the annular region (12) does not extend beyond the innermost reach (16) of the edge of the compact disc (2) in its final shape, forming a first alignment mark (20a, 20b) on the blank (36), applying a label (22) to the upper face of the blank (36), orienting the blank (36) on a manufacturing platform (26) by aligning the first alignment mark (20a, 20b) with respect to an alignment mark (34a, 34b) on the manufacturing platform (26), securing the blank (36) against rotation with respect to the platform (26) and shaping the blank (36) into its final shape by removing portions of the blank with a grinding tool (44) which cooperates with a form (38) to provide the final shape.

BACKGROUND OF THE INVENTION 
The present invention relates to compact discs and related devices, such as 
CD-ROMs, laser discs and cleaning CD's, having a profile other than 
circular. In particular, the invention relates to processes for 
manufacturing this novel type of compact disc. 
Presently, all compact discs have a circular profile shape. It is common 
that a label containing artwork or other visually readable material is 
applied to the upper, non-functional face of the compact disc. Since the 
normal compact disc is round, the label may be applied in any radial 
direction so long as the label is properly centered. 
However, the orientation of a non-round compact disc changes about the 
perimeter of the disc, the label must be applied not only in centered 
fashion, but must also be aligned in the proper radial direction with 
respect to the disc perimeter or profile. It therefore becomes necessary 
to label and manufacture non-round compact discs to insure that the label 
is properly aligned in the desired orientation. 
Is it currently considered to be a requirement that compact discs have a 
circular outer profile, based on the process by which information is read 
on the compact disc by a reading machine, such as a compact disc player. 
The disc rotates about a central axis in a receiving tray of the player 
with respect to a laser-based reading element, and therefore, the 
information on the disc must be arranged in a circular fashion. Since the 
disc must rotate within the player, it is of course most convenient to 
have the disc as a whole shaped with a circular outer profile, with the 
player shaped to receive the circular disc. 
However, it has now been discovered that it is possible to provide a 
compact disc having a non-circular outer profile. FIG. 1 shows a heart 
shaped compact disc in bottom plan view, although any non-circular disc is 
within the scope of the invention. The radius r.sub.1, of such a non-round 
disc 2, measured from the center of the disc (i.e. the center of the 
center hole 10) to the furthest point 6 on the outer profile 8, should be 
sized to fit within the usually round receiving tray of an appropriate CD 
player. In other words, the radius r.sub.1 must be less than or equal to 
the inside diameter of the receiving tray. However, since the non-circular 
compact disc will have the usual center hole 10 found on standard round 
compact discs, these non-circular discs will also properly spin within the 
receiving tray of a CD player. 
While the outer profile of the CD of the invention may be of non-round 
shape, the readable digital information 12 provided on the disc must be 
provided in the usual annular arrangement. However, in order to insure 
that all of the intended information will be readable, the outer limit 14 
of the annularly arranged information region must not extend beyond the 
innermost point 16 of the outer profile 8. 
Compact discs generally possess a so-called stacking ring about the center 
of the disc, which acts as a spacer to prevent damage to the disc surface 
when stacked with other discs. However, the spaces resulting between the 
stacked discs become problematic during a shaping process in which a 
plurality of stacked discs are simultaneously shaped. In particular, dust 
and other debris from the shaping process tends to enter the interstitial 
area between discs and could result in damage to the delicate disc 
surface. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a process 
which insures that the labels applied to the non-round compact discs are 
properly aligned with respect to the outer profile of the disc. 
It is a further object of the invention to provide a process for mass 
producing non-round compact discs in a convenient and cost-efficient 
manner, while protecting the integrity of the information on the disc from 
damage.

DETAILED DESCRIPTION OF THE INVENTION 
A compact disc to be fashioned into a disc having a non-round outer profile 
is first imprinted with laser-readable digital information arranged in an 
annular region on the underface of a blank, which may be round. The 
digital information region should conform to the limitations discussed 
above with respect to the dimensions of the desired outer profile to be 
achieved. 
In a first embodiment of the process, the compact disc having digital 
information thereon will then have applied to its upper face an opaque 
label in the known manner such as by way of a screen printing process. 
FIG. 2 shows a top plan view of the compact disc of FIG. 1, having a label 
22 applied thereto. The label may cover all or part of the upper face, 
leaving open only the center hole. From this view, it can be appreciated 
that it is important that the label be properly aligned with respect to 
the outer profile of the non-round compact disc; such a concern is not 
present for circular discs. 
The compact disc blank may have a transparent annular region 18 immediately 
adjacent to and located outwardly of the center hole 10. The transparent 
annular portion will not contain digital information, as the annular 
digital region 12 will be located outward of the transparent region 18. In 
the drawing shown, the label is optionally applied to cover most of the 
transparent region. Similarly, a transparent region may be present 
elsewhere on the compact disc, such as towards the outer perimeter. 
At least one transparent marking 20a or 20b is formed in the transparent 
region by leaving a portion of that region uncovered by the label. In the 
alternative, a marking can be located in the transparent region 20 by the 
reverse procedure, i.e. by leaving a larger portion of said region 
transparent and then placing a portion of the label or some other form of 
opaque marking within said larger portion to thereby serve as a marking 
element. It will be contemplated that any such arrangement involving the 
location of opaque and/or transparent or translucent markings within the 
transparent region may be used to form a marking element, which marking 
element will be used to properly align the labeled compact disc blank 
during the subsequent process during which the non-round outer profile is 
imparted. 
With respect to FIGS. 3A-3E, a manufacturing platform 26, preferably made 
of a strong material such as metal is provided. A shaft 28, rotationally 
fixed with respect to the platform extends upwardly for fittingly 
receiving one or more labeled compact disc blanks 36 by way of the center 
holes 10 thereof. The platform is provided with an alignment marking 34 
which allows alignment with the marking 20 of the compact disc blank. The 
platform marking 34 may be located or fashioned in any manner which would 
allow for proper aligning of the blanks. For example, the platform marking 
34a may be located such that it can be seen through the corresponding 
transparent marking 20b. Also, the platform marking 34b may be located 
clear of the point to which the blank will extend when placed on the 
platform to allow an alignment based on any corresponding marking on the 
blank. A similar alignment marking, such as a longitudinal line may be 
placed on the shaft to allow alignment with a marking placed along the 
edge of the center hole of the blank. 
A form 38 is provided with an attachment means 40 which corresponds with an 
attachment means 41 on the shaft, to permit the form to be removably fixed 
to the shaft during the shaping process. In the embodiment shown, the 
means 40 is a screw while the means 41 is a conforming screw hole, 
however, it should be clear that these may be reversed, or that any means 
for removably fixing the form 38 to the shaft 28 may be employed. In order 
to be sure that the form is properly aligned with respect to the shaft, 
and hence the platform, an anti-rotation alignment means 32 is provided 
which co-acts with a conforming means 42 on the form 38. In the drawing, 
the means 32 is shown as two pins and the means 42 is shown as two holes 
for conformingly receiving the pins. Again, it should be clear hat any 
known anti-rotation means may be provided, such as single pin having a 
non-circular cross-section and a conforming receiving hole; and that the 
location of the pin and hole may be reversed. 
The form 38, preferably made of a hard material such as metal, will have 
the shape of the intended outer profile of the compact disc, and the form 
should have some degree of thickness in order to support the later force 
of a grinding tool 44 applied thereagainst. 
Once the form 38 is fixed to the shaft 28, and the compact disc blanks 36 
are secured against movement, the shaping step is achieved by removing the 
portion of the blank 36 extending beyond the form 38 by way of a shaping 
tool. The shaping tool may be any suitable device, and is shown as a 
rotating grinding tool 44 which is against the edge of the blank until it 
meets the abutting edge 48 of the form 38, and then follows the form about 
its perimeter until the entire blank has been shaped into the desired 
final compact disc product. It should also be realized that the rotating 
grinding tool may remain stationary while the platform, along with the 
blank and form fixed thereto, is moved about the tool. 
In an alternative embodiment, (see FIG. 4) the steps set forth above are 
followed except that the alignment of the blank with respect to the 
platform is accomplished in a physical, rather than visual, manner. Before 
the compact disc blanks are placed on the platform for shaping, a cut-out 
is made in the blank at a location which does not contain digital 
information. The cut-out may be in the form of a notch 52 in the edge of 
the blank, which then co-acts with a conforming alignment shaft 50 which 
extends perpendicularly from the platform. The cut-out may also be in the 
form of a hole in the blank other than the center hole, which hole then 
fits about the alignment shaft. 
A further embodiment performs (see FIG. 5) the alignment step by way of the 
cut-out notch 52 described above. However, rather than an alignment shaft 
extending from the flat face of the platform, the platform 26 is provided 
with a recess 62 sunken with respect to the face 60 of the platform. The 
recess has the general shape of a round blank to be conformingly received 
therein, while also having an inward protrusion 64. The protrusion will 
fit within the notch 52 in the blank to perform the alignment step. The 
shaping step is then accomplished by way of a properly shaped die which 
stamps out the desired profile. An alternative shaping step may be 
performed, wherein the recess 62 is further fashioned as a, e.g. female 
portion of a mold, corresponding with a male portion of a mold, which 
co-act upon stamping to produce the compact disc of the desired shape. 
In a still further embodiment (see FIG. 6) related to automated production 
of the shaped discs, round blanks are provided with a notch 152, e.g. a 
semi-circular notch, in the edge thereof. This can be achieved by any 
convenient means, such as simultaneous milling of a stack of discs. A 
plurality of notched discs 136 are then stacked onto a spindle 184 by way 
of their center holes. A guide spindle 180, conforming to the shape of the 
notch on each disc, is provided on the stacking platform at a distance 
from and parallel to the center spindle, such that all of the notched 
discs can be aligned together and held in position by the guide spindle. 
The notched discs are then removed one at a time, preferably by suction by 
way of a robot arm 188, and are loaded onto a standard apparatus 186 for 
printing labels on a compact disc. It is important that the robot arm 
consistently place the notched discs onto the printing tray with a 
consistent rotational motion, such as through a set angle, so that the 
notch or other alignment means is always located in the same position with 
respect to the label to be printed on the disc. 
The labeled discs are then taken to the shaping apparatus. Again, the notch 
152 is used to correctly position each labeled disc with respect to the 
particular shape to be imparted to the profile of the disc. Thus, the 
labeled discs may be loaded onto a center shaping spindle 192, and held in 
place by a guide spindle 174 projecting from the shaping platform. The 
shaping procedure is then coordinated with the automatically positioned 
discs to provide a shaped profile to the discs which conforms to the 
label. 
A still further method for insuring the alignment of the label and shaped 
profile of the disc involves providing a sensor-readable mark on the disc 
during the labeling process. In this embodiment, normal round blank discs 
may loaded on the center spindle of the labeling apparatus without regard 
to rotational position. During the printing step, a sensor mark is printed 
on, or otherwise provided on the surface of the disc. The sensor mark may 
be any mark which is machine-readable, such as by virtue of its shape, 
color, wavelength, pattern, composition, or other physical 
characteristics. The mark should be preferably placed on a portion of the 
disc which will be cut away during later shaping; however, this may not be 
of concern if a mark is provided which is not visible under ordinary 
circumstances. 
Once the discs are labeled with the sensor mark, they may be notched as 
above in relation to the mark, either at the mark itself, or at a set 
distance from the mark. The notches may be provided by any convenient 
means, such as by milling a plurality of stacked discs. The notches are 
then used to properly orient the discs during the shaping procedure. 
Alternatively, the notches can be dispensed with altogether in a totally 
sensor driven procedure. In such a case, the discs may be aligned on the 
shaping spindle automatically by way of a sensor in communication with a 
stacking means on the shaping platform. 
As shown in FIG. 7, a preferred shaping procedure involves the use of a 
milling bit 144 on a shaping platform 126. Preferably, a plurality of 
labeled discs 136 are properly aligned on a shaping spindle 190. A guide 
spindle 174 may be present on the platform to perform an initial alignment 
on the shaping spindle 190. Once the discs are secured against rotation by 
other means (see below), the guide spindle may optionally be removable to 
prevent interference with the milling apparatus. Advantageously, the 
spindle 192 may have a round cross-section with a portion cut away 193. A 
shaping form 138 is then placed on top of the stack about the spindle 190. 
In order to insure that the form 138 is properly aligned with the discs 
136, the center hole 194 in the form should conform 195 to the 
cross-section of the spindle in order to have it retained against rotation 
on the spindle. Alternatively (see FIG. 8), for ease of manufacture of the 
form, the form can simply have a circular center hole. When in use, a 
spindle adapter can be secured to a face of the form. While the form could 
also have a notch which is alignable in a guide spindle, this would not be 
preferable as it could interfere with an uninterrupted milling of the 
outer profile. The form is then secured in place by way of a collar 170 
and set screw 172 or the like, or any known means which can apply pressure 
from above, in such a manner as to supply sufficient pressure against the 
stack of discs so as to prevent rotation of the discs during milling. 
A particular problem arises during the simultaneous milling of a stack of 
discs by virtue of a stacking ring 200 (see FIG. 9) provided as a standard 
component of all compact discs. Such stacking ring 200 rises slightly 
above the surface of the disc, to insure separation during stacking with 
other discs during the manufacturing process in order to prevent damage to 
the disc surface from another disc. However, during the milling of a 
plurality of stacked discs, the separation between discs by virtue of the 
stacking rings provides an opportunity for dust and other milling debris 
to enter the area between the discs, and to thereby damage the disc 
surface. 
In order to overcome this problem, the applicant has discovered that by 
providing a specialized form, this can be avoided. In particular, with 
reference to FIG. 10 showing an underside of a form, the shaping form 138 
is designed with a downward projecting lip 139. The lip may follow the 
profile of the form shape, or may simply be of a general ring shape. 
Alternatively, the lip may be provided as a separate ring for placement 
under a form. 
When the form having a lip, or a form having a ring placed thereunder is 
applied with pressure to the stack of discs, the lip or ring acts to bend 
the outer portion of the discs downward, against the disc below, to 
thereby close off entry to the area 201 between the discs, and to prevent 
dust or debris from entering the area. This is seen if FIG. 11. It will 
therefore be appreciated that the lip or ring must be oriented at a 
minimum distance from the outer perimeter of the stacking rings to allow 
for a convenient amount of torque to applied to the stack in order to 
temporarily deform the discs as desired. In addition, the outer perimeter 
of the ring should be chosen with respect to the shape of the particular 
form being used, so as not to interfere with the grinding operation. 
It should be clear that the lip or ring can also be provided against the 
bottom of the stack of discs, either in lieu of an upper location, or in 
addition thereto. Thus, a ring can be located beneath the bottom-most disc 
of a stack, either as a means permanently fixed to the platform, or being 
a separable item. When pressure is applied from above, the bottom ring 
will push upwardly to deform the discs in a similar fashion to that 
described above. By using simultaneous rings in the upper and lower 
portions, the deformation can be increased, and greater number of discs 
can be stacked and processed.