A MULTI-LAYERED OPTICAL DISC HAVING IMPROVED MARKING AND
IDENTIDICATION FACILITY OF INDIVIDUAL LAYERS AND A METHOD OF
MARKING AND IDENTIFYING EACH LAYER OF A MULTI-LAYERED OPTICAL
DISC.
FIELD OF THE INVENTION
The present invention in general, relates to a multi-layered optical
disc having improved identification and marking facility of individual
layers and in particular, to an improved method of marking and identifying each
layer of a multi-layered optical disc to avoid obscurity in readability and
identification of individual layers.
BACKGROUND OF THE INVENTION
It is knov\/n in the art that an optical disc may have several information layers,
varying between one to many. There is no restriction for maximum number of
layers. It is common knowledge that information layer(s) is (are) the layer(s)
where data is stored.
In order to track the history of an individual optical disc, usually a unique
reference number is assigned and printed on each individual disc. To be precise,
traditionally, the unique reference number of each individual disc is identical to a
combination of 'unique reference numbers of all the layers' of that particular disc
To be precise, if an optical disc has n number of layers and the layers are
marked as X1 ,X2,X3 Xn then the unique reference number of the optical
disc will be X1X2X3 Xn. However, it has been observed that the reference
numbers of any two consecutive layers often overlap each other due to the limited marking space , hence readability and consequently identification of individual layers of the disc becomes difficult, if not impossible. In other words, due to limited marking space and the traditional technique as stated before, it was very difficult to mark and identify the identity of each layer in a multi-layered disc and often , if not always, this resulted in overlapping of marked or engraved information of each layer.
1A

Hence, there was a long felt need to develop optical discs with improved identifying and marking facility of individual layers, whereby reference numbers of any two consecutive layers do not overlap each other thereby, removing the obscurity in readability of reference numbers of different layers and consequently, identification of different layers of optical discs.
So, in order to improve readability of reference numbers of different layers of
optical discs, the reference number of any of the layers should not coincide with
another layer in any particular location of the optical disc. To facilitate this the
reference numbers of all the layers, should be at different locations of the optical
disc, thereby improving the readability of reference numbers of the different
layers and consequently, identification of the different layers of the optical
discs.
The present invention achieves the long felt need and desired objective as
stated aforesaid.
It is clarified that all throughout the specification including the claims , the term
multi- layered optical disc as used , also includes similar multi-layered
assemblies, unless specifically particularized to that effect and multi-layered
discs have been referred to and described purely for the sake of understanding
and clarity and not by way of any limitation.
OBJECTS OF THE INVENTION
It is a prime object of the present invention to provide multi-layered discs having
improved identification and marking facility of individual layers.
It is another object of the present invention, to provide an improved method of
marking and identifying each layer of multi-layered optical disc.
It is another object of the present invention to provide multi-layered optical discs
with improved readability of reference numbers of the different layers of the
multi-layered optical discs ,avoiding obscurity in readability and identification of
the different layers.

It is a further object of the present invention to improve readability of reference numbers of different layers of optical discs, by ensuring that the reference number of any of the layers does not coincide with another layer in any particular location of the disc.
It is yet a further object of the present invention to ensure that the reference numbers identifying the different layers of a multi-layered optical disc , be at different locations, thereby improving the readability of the reference numbers identifying the different layers of the disc.
It is a further object of the present invention to solve the problem of 'space availability for printing reference number' over different locations at different layers of an optical disc, by printing same reference number, on different layers of the disc at the same location, but using different fonts or otherwise for different layers, thereby ensuring readability of the reference numbers and simultaneously ensuring identification of the different layers of a multi-layered optical disc.
How the foregoing objects are achieved and the other aspects of the pesent invention will be clear from the following description, which is purely by way of illustration and not by way of any sort of limitation. SUMMARY OF THE INVENTION
Accordingly, the present invention provides a multi-layered optical disc having improved identification and marking facility of individual layers, wherein said disc is adapted such that the different layers of said disc are capable of being marked by different reference numbers spread over different locations of the disc, whereby it is ensured that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.
In accordance with preferred embodiments of the multi-layered optical disc of the present invention: -number of layers vary between one and twelve.

-said different reference numbers include identical numbers, printed on different layers of the disc at same location of the disc, by applying different font for different layers, at said same location.
-said font comprises all the meanings of fashion , size, colour, language, pattern and so on.
The present invention also provides a multi-layered disc having improved identification and marking facility of individual layers, said disc being adapted such that the different layers of said disc are capable of being marked by different reference numbers spread over different locations of the disc, wherein said different layers of said disc are capable of being marked by printing the same number on different layers of the disc at same location,, applying different printing font for identifying different layers, whereby it is ensured that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc. The present invention also provides a method of marking and identifying each layer of a multi-layered optical disc including marking the different layers of said disc, by different reference numbers spread over different locations of the disc, thereby ensuring that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.
The present invention also provides a method of marking and identifying each layer of a multi-layered optical disc including marking the different layers of said disc, by different reference numbers spread over different locations of the disc, wherein said different layers of said disc are marked by printing the same number on different layers of the disc at the same location , applying different printing font for identifying different layers, thereby ensuring that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different

layers and consequently, identification of different layers of said disc. The present invention also provides a method of solving the problem of 'space availability for printing reference number' over different locations at different layers of an optical disc, comprising applying the method as described in the preceding paragraph.
The present invention also provides a method of improving readability of reference numbers of different layers and consequently identification of different layers of an optical disc comprising applying the method as described herein before..
Hence, the objects of the present invention are achieved. BRIEF DESCRIPTION OF THE DRAWINGS ACCOMPANYING THE PROVISIONAL SPECIFICATION
The nature and scope of the present invention will be better understood from the following description of the drawings, accompanying the provisional specification , which are by way of illustration and understanding and not by way of any sort of limitation. In the drawings accompanying the provisional specification:
FIG1 illustrates a multi-layered optical disc having existing identification and marking pattern.
FIG 2 illustrates a multi-layered optical disc with improved identification and marking pattern in accordance with the invention, where reference numbers of all the layers are at different locations.
FIG 3 illustrates a multi-layered(only two layers visible) optical disc in accordance with the invention where different fonts for different layers for printing, are utilized.
FIG 4 illustrates a multi-layered optical disc as in FIGS, above where six layers are shown for the purpose of illustration.
FIG 5 illustrates possible marking locations in an optical disc in accordance with the invention .

FIGS 6 to FIG 7 illustrate the existing pattern of the dual substrates of a dual
layer disc before bonding and before ID printing.
FIGS 8 to FIG 9 illustrate the existing pattern of the dual substrates of a dual
layer disc before bonding and after ID printing.
FIGS 10 to FIG11 illustrate the existing pattern of the dual substrates of a
finished dual layer disc after bonding and after ID printing.
FIGS 12 to FIG13 illustrate the proposed pattern of the dual substrates of a dual
layer disc, before bonding and after ID printing.
FIGS 14 to FIG 17 illustrate the proposed pattern of the dual substrates of a dual
layer disc in its finished state, after bonding and after ID printing.
BRIEF DESCRIPTION OF THE INVENTION
The nature and scope of the present invention will be better understood from the
following non-limiting description of some preferred embodiments, with reference
to the drawings, as detailed aforesaid.
As known in the art, an optical disc may have several information layers, varying
between one to many, for example, up to 12. As explained before, there is no
restriction for maximum number of layers. It is common knowledge that
information layer(s) is (are) the layer(s) where data is stored.
Presently, in order to track the history of an individual optical disc, a unique
reference number is assigned and printed on each individual disc.
The unique reference number of each individual disc is a combination of 'unique
reference numbers of all the layers' of that particular disc .For example:
> If number of information layers in a disc = 1, then, reference number for disc will be identical to that for layer.
> If number of information layers in a disc = 2, then, reference number for disc will be combination of reference number of two layers.
> If number of information layers in a disc = 3, then, reference number for disc will be combination of reference number of all three layers.

The reference number of each individual layer is always printed on it's own
surface only, due to manufacturing process requirement.
However, as per disc design, the space available for printing this reference
number on all the layers of disc is limited i.e. from disc radius =7.5mm to 17.5mm
only, irrespective of number of layers. Furthermore, the physical dimension of all
the layers is identical.
Consequently, if the reference numbers of any two consecutive layers come over
each other, then, readability becomes obscure as can be seen from FIG1, and
so the identification of the layers become difficult, if not impossible.
In order to improve readability of the reference numbers identifying the different
layers of an optical disc, the reference number of any of the layer should not
coincide with another layer in any particular location. This is the prime objective
of the present invention. From Fig 2 it is very clear that reference number of all
the layers are at different locations.thereby improving the readability of reference
numbers of the disc and consequently facilitating perfect identification of the
different layers.
From FIG 2 it should be also very clear that the printing of reference numbers is
very easy up to layer 03, but after layer 03, adequate space is not available for
printing reference number for layer 04 onwards. This is particularly due to the fact
that reference number of each individual layer is always printed on its own
surface only, due to manufacturing process requirement. Furthermore, due to
disc design , the space available for printing this reference number on all the
layers of disc is limited i.e. from disc radius =7.5mm to 17.5mm only, irrespective
of number of layers. Furthermore, the physical dimension of all the layers is
identical.
To overcome this problem of 'space availability for printing reference number'
over different locations at different layers of disc, the present invention also
provides a method comprising printing the same number on different layers at
the same location , using different font for different layers, thereby improving
readability, wherein said font includes all the meanings of fashion , size, color.

language, pattern and so on.
These aspects have been very clearly illustrated in FIGS, FIG4 and Fig 5.
FIG 5 shows the possible marking locations of different Layers.
As it will be clear from Fig 5, the different layers at the same location will be
marked by identical numbers, however, different font will be used to identify
each layer and as explained before, font includes, all the meanings of fashion ,
size, color, language, pattern and so on. So, for a particular location, if the
reference number used for marking layer 01 is X3 than all other layers will also
be marked as X3 only for that particular location, but different font will be used
while printing this number on the different layers.
As it is known in the art a dual Layer disc contains two layers,i.e.. LO & LI.
FIG.06 & 07 show the LO & LI substrates before bonding & before ID printing
respectively. These two substrates are then printed separately by some printer,
for Disc ID identification purpose.
FIG. 08 & 09 show the LO & LI substrates before bonding & after ID printing respectively. FIG. 08 & 09 show the existing pattern.
After this individual printing of LO & LI, these substrates are then bonded by
some bonder to get the finished disc.
FIG. 10 & 11 show the finished disc after bonding & after ID printing respectively.
Fig. 10 & 11 show the existing pattern.
Print area means, the area where the company or product advertisement
information is printed, or sticker containing the company or product
advertisement information is pasted.
Data area means the area where actually data is stored.
Fig. 12 & 13 show the LO & LI substrates before bonding & after ID printing
respectively. Fig. 12 & 13 show the proposed pattern.

Fig. 14, 15, 16 & 17 show the finished disc after bonding & after ID printing respectively. Fig. 14, 15, 16 & 17 show the proposed pattern. The present invention has been described with reference to some preferred embodiments and drawings, purely for the sake of understanding and it is not limited to such embodiments and drawings. Hence the present invention includes all legitimate developments within the scope of the foregoing description and the appended claims.

WE CLAIM
1 .A multi-layered optical disc having improved identification and marking facility of individual layers, wherein said disc is adapted such that the different layers of said disc are capable of being marked by different reference numbers spread over different locations of the disc, whereby it is ensured that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.
2. The multi-layered optical disc as claimed in claim 1 wherein numbers of layers vary between one and twelve.
3. The multi-layered optical disc as claimed in any of claim 1 or 2 wherein said different reference numbers include identical numbers, printed on different layers of the disc at same location of the disc, by applying different font for different layers, at said same location.
4. The multi-layered optical disc as claimed in claim 3 wherein said font comprises all the meanings of fashion , size, colour, language, pattern and so on.
5.A multi-layered disc having improved identification and marking facility of individual layers, said disc being adapted such that the different layers of said disc are capable of being marked by different reference numbers spread over different locations of the disc, wherein said different layers of said disc are capable of being marked by printing the same number on different layers of the disc at the same location , applying different printing font for identifying different layers, whereby it is ensured that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.

6. The multi-layered disc as claimed in claim 5 wherein said font comprises all the meanings of fashion , size, colour, language, pattern and so on .
7. A method of marking and identifying each layer of a multi-layered optical disc including marking the different layers of said disc, by different reference numbers spread over different locations of the disc, thereby ensuring that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.
8. A method of marking and identifying each layer of a multi-layered optical disc including marking the different layers of said disc, by different reference numbers spread over different locations of the disc, wherein said different layers of said disc are marked by printing the same number on different layers of the disc at same location, applying different printing font for identifying different layers, thereby ensuring that the reference number of any of the layers does not coincide with another layer in any particular location of the disc, thus facilitating readability of reference numbers of different layers and consequently, identification of different layers of said disc.
9. A method of improving readability of reference numbers of different layers and consequently identification of different layers of an optical disc comprising applying the method as claimed in any of claims 7 or 8.

10. A method of solving the problem of 'space availability for printing reference number' over different locations at different layers of an optical disc, comprising applying the method as claimed in claim 8.