U.S. patent application number 13/334179 was filed with the patent office on 2013-06-27 for optical media having transparent back side coating.
This patent application is currently assigned to ORACLE INTERNATIONAL CORPORATION. The applicant listed for this patent is Eui Kyoon Kim. Invention is credited to Eui Kyoon Kim.
Application Number | 20130167166 13/334179 |
Document ID | / |
Family ID | 47520292 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130167166 |
Kind Code |
A1 |
Kim; Eui Kyoon |
June 27, 2013 |
Optical Media Having Transparent Back Side Coating
Abstract
An optical media such as an optical tape includes a substrate, a
pre-format layer on one side of the substrate, and a back side
coating. The back side coating is optically transparent and is
electrically conductive. One of the substrate and the pre-format
layer is between the back side coating and the other one of the
substrate and the pre-format layer.
Inventors: |
Kim; Eui Kyoon; (Woburn,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kim; Eui Kyoon |
Woburn |
MA |
US |
|
|
Assignee: |
ORACLE INTERNATIONAL
CORPORATION
Redwood City
CA
|
Family ID: |
47520292 |
Appl. No.: |
13/334179 |
Filed: |
December 22, 2011 |
Current U.S.
Class: |
720/746 ;
118/642; 427/558; 427/58 |
Current CPC
Class: |
Y10T 428/21 20150115;
G11B 7/252 20130101 |
Class at
Publication: |
720/746 ; 427/58;
427/558; 118/642 |
International
Class: |
G11B 7/003 20060101
G11B007/003; B05C 11/00 20060101 B05C011/00; B05D 5/06 20060101
B05D005/06; B05D 5/12 20060101 B05D005/12; B05D 3/06 20060101
B05D003/06 |
Claims
1. An optical media comprising: a substrate; a pre-format layer on
the substrate on one side of the substrate; and a back side
coating, wherein the back side coating is optically transparent at
least in the ultraviolet range and is electrically conductive;
wherein the pre-format layer is between the back side coating and
the substrate with the back side coating being positioned apart
from the pre-format layer on the same side of the substrate.
2. (canceled)
3. The optical media of claim 1 wherein: the back side coating
includes an optically transparent and electrically conductive
oxide.
4. The optical media of claim 3 wherein: the oxide includes at
least one of indium tin oxide (ITO), fluoride doped tin oxide
(FTO), and doped zinc oxide.
5. The optical media of claim 1 wherein: the back side coating
includes a metalized film.
6-8. (canceled)
9. The optical media of claim 1 further comprising: a recording
layer, wherein the recording layer is on the back side coating and
is between the back side coating and the pre-format layer.
10. The optical media of claim 1 wherein: the optical media is an
optical tape.
11-20. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to back side coatings for
optical tape and to a method and system for producing optical tape
having a back side coating.
BACKGROUND
[0002] Optical tape is a media for data storage. Optical tape may
include a thin back side coating to improve winding properties and
to prevent static charge. Typical back side coatings are formed
from materials that are (i) electrically conductive and (ii)
strongly ultraviolet (UV) radiation absorbing or reflective.
[0003] Roll-to-roll nano-imprint lithography systems are used for
patterning or pre-formatting optical tape with the imprint of
nano-structure features such as land and groove and wobble
patterns. The pre-formatting operation includes curing
photo-polymerizable materials of the optical tape with UV
radiation. As a result, back side coatings that are either UV
radiation absorbing or reflective may induce relatively large
decrease in the roll-to-roll process throughput.
SUMMARY
[0004] Embodiments of the present invention are directed to an
optical media such as an optical tape having a back side coating
that is optically transparent and electrically conductive. Back
side coatings in accordance with embodiments of the present
invention are optically transparent at least in the ultraviolet
(UV) radiation range and therefore differ from typical back side
coatings that are UV radiation absorbing or reflective. As back
side coatings in accordance with embodiments of the present
invention are UV transparent and electrically conductive, the
desired winding properties and static charge removal
characteristics can be achieved without sacrificing roll-to-roll
imprint process throughput.
[0005] A back side coating for an optical media such as an optical
tape in accordance with embodiments of the present invention may be
formed from optically transparent and electrically conductive
oxides including indium tin oxide (ITO), fluoride doped tin oxide
(FTO), and doped zinc oxide. Alternatively or additionally, a back
side coating for an optical media such as an optical tape in
accordance with embodiments of the present invention may be formed
from optically transparent and electrically conductive materials
including conductive polymers, films with carbon nanotubes,
graphene, and metal grid structures, and other organic films and
other metal grid films. Such oxides and materials may be used for a
back side coating of an optical tape in accordance with embodiments
of the present invention in order for the back side coating to
obtain the properties of being UV transparent and electrically
conductive.
[0006] An object of the present invention includes an optical media
such as an optical tape having a back side coating that is
transparent at least in the UV radiation range and is electrically
conductive.
[0007] Another object of the present invention includes a method
and a system for producing an optical media such as an optical tape
having a back side coating that is transparent at least in the UV
radiation range and is electrically conductive.
[0008] In carrying out one or more of the above objects and other
objects, an embodiment of the present invention provides an optical
media having a substrate, a pre-format layer on one side of the
substrate, and a back side coating. The back side coating is
optically transparent and is electrically conductive. One of the
substrate and the pre-format layer is between the back side coating
and the other one of the substrate and the pre-format layer.
[0009] In an embodiment, the back coat coating is optically
transparent at least in the ultraviolet range. The back coat
coating may include an optically transparent and electrically
conductive oxide such as indium tin oxide (ITO), fluoride doped tin
oxide (FTO), and doped zinc oxide. The back side coating may
include at least one of electrically conductive polymers, films
with carbon nanotubes, graphene, and metal grid structures. In an
embodiment, the back side coating is on an opposite side of the
substrate and a recording layer may be on the pre-format layer. In
another embodiment, the back side coating is positioned apart from
the pre-format layer on the same side of the substrate. In this
embodiment, a recording layer may be on the back side coating and
between the back side coating and the pre-format layer.
[0010] Further, in carrying out one or more of the above objects
and other objects, an embodiment of the present invention provides
a method for generating an optical media such as an optical tape.
The method includes depositing a back side coating that is
optically transparent and electrically conductive on one side of a
substrate. The method further includes depositing a polymer layer
on an opposite side of the substrate. The method further includes
embossing the polymer layer with embossments using a drum having
protrusions and hardening the embossed surface of the polymer layer
prior to removing the polymer layer from the drum.
[0011] Also, in carrying out one or more of the above objects and
other objects, the present invention provides a system for
generating an optical media such as an optical tape. The system
includes a back side coating stage, an embossing monomer coating
stage, an embossing assembly, and a curing assembly. The back side
coating stage is configured to deposit a back side coating that is
optically transparent and electrically conductive on one side of a
substrate. The embossing monomer coating stage is configured to
deposit a polymer layer on an opposite side of the substrate. The
embossing assembly has a drum with protrusions configured to emboss
the polymer layer with embossments. The curing assembly has an
illumination source configured to illuminate the embossed surface
of the polymer layer with ultraviolet radiation prior to removal of
the polymer layer from the drum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 illustrates a sectional view of an optical tape in
accordance with an embodiment of the present invention;
[0013] FIG. 2 illustrates a block diagram of an optical tape
generation system for producing the optical tape;
[0014] FIG. 3A illustrates a side elevation view of the
embossing/curing stage of the roll-to-roll system in which the
embossing/curing stage embosses or pre-formats information-bearing
structures in the optical tape;
[0015] FIG. 3B illustrates a cross-sectional view of the optical
tape just prior to entering the embossing/curing stage of the
roll-to-roll system;
[0016] FIG. 3C illustrates a cross-sectional view of the optical
tape just after exiting from the embossing/curing stage of the
roll-to-roll system;
[0017] FIG. 4A illustrates a sectional block diagram view of an
optical tape having a first surface incident (air-incident) WORM
media layer composition in accordance with an embodiment of the
present invention;
[0018] FIG. 4B illustrates a sectional block diagram of an optical
tape having a first surface incident (air-incident) rewritable
media layer composition in accordance with an embodiment of the
present invention;
[0019] FIG. 4C illustrates a sectional block diagram of an optical
tape having a second incident (substrate-incident) WORM media layer
composition in accordance with an embodiment of the present
invention; and
[0020] FIG. 4D illustrates a sectional block diagram of an optical
tape having a second incident (substrate-incident) rewritable media
layer composition in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION
[0021] Detailed embodiments of the present invention are disclosed
herein; however, it is to be understood that the disclosed
embodiments are merely exemplary of the invention that may be
embodied in various and alternative forms. The figures are not
necessarily to scale; some features may be exaggerated or minimized
to show details of particular components. Therefore, specific
structural and functional details disclosed herein are not to be
interpreted as limiting, but merely as a representative basis for
teaching one skilled in the art to variously employ the present
invention.
[0022] Referring now to FIG. 1, a sectional view of an optical tape
10 in accordance with an embodiment of the present invention is
shown. Optical tape 10 includes a plurality of layers or films
stacked on top of one another. The layers include an overcoat 12, a
recording layer 14, a polymer layer 16, a substrate (i.e., carrier
layer or base film) 18, and a back side coating 20.
[0023] Overcoat 12 protects the remaining lower layers of optical
tape 10 from physical damage. Overcoat 12 may include
anti-reflective properties (e.g., low index of refraction) to
prevent unwanted reflections of laser light from an optical head
from the layers within optical tape 10 and to allow the laser light
to penetrate through overcoat 12 more efficiently. Overcoat 12 may
be applied by sputtering.
[0024] Recording layer 14 enables reading or writing of user data
from or to optical tape 10. Recording layer 14 belongs to a class
of materials that change one or more physical properties in
response to exposure to laser or other radiation emitted from an
optical head. The materials include phase change and dye-polymer
media. For instance, recording layer 14 includes a plurality of
layers or films including a dielectric layer followed by a phase
change layer followed by another dielectric layer followed by a
reflective layer. The phase change layer is sensitive to laser
light radiation whereby the phase change layer changes from an
amorphous to a crystalline phase when subjected to sufficient heat
of the laser light. Once changed, the composition of the material
prevents it from changing back to the amorphous state. The
reflective layer is made of a metal material such as silver,
aluminum, or antimony and reflects laser light that passes through
the phase change layer. The reflective layer further attenuates
light from above, and reflects light from below, thus attenuating
and blocking light from above and below from passing through and
mixing with laser light, which may introduce noise in the nominal
reflected laser light.
[0025] Polymer layer 16 is to be embossed or pre-formatted with
information bearing-structures such as pit, land, groove, wobble
patterns, or the like. Such structures are physical features that
are incorporated into the surface of polymer layer 16. Position and
tracking, error correction, focusing, and other information can be
provided or enhanced by the surface features as these features are
readable by an optical head. The surface features are incorporated
into optical tape 10 at the time of manufacture and this process is
generally referred to as physical pre-formatting. As described in
greater detail below, polymer layer 16 may be formed from a monomer
fluid by a drum embossing and ultraviolet (UV) curing apparatus
where polymer layer 16 is embossed with the information
bearing-structures (for example, land and groove features) and
cured at the same time. While curing, polymer layer 16 converts
from a liquid monomer to a solid polymer and may be permanently
attached to substrate 18. Polymer layer 16 is attached to substrate
18 by a tie coat/adhesion promoter 17.
[0026] Substrate 18 is positioned underneath polymer layer 16 and
provides mechanical support. Substrate 18 may be created from a
high-performance thermoplastic polyester film such as polyethylene
naphthalate (PEN), polyethylene terephthalate (PET), or similar
material having appropriate mechanical, thermal, and hydroscopic
properties for a data storage optical media product.
[0027] Back side coating 20 is attached to the back side of
substrate 18 opposite polymer layer 16. Back side coating 20 is
attached to substrate 18 by a second tie coat/adhesion promoter 19.
Back side coating 20 is electrically conductive and thereby
minimizes the buildup of static charge. Back side coating 20 may
have a textured surface acting as a conduit to release any
entrapped air generated during tape subsystem operation. Back side
coating 20 may include single or multiple layers for providing
friction and/or surface control, thermal conductivity, and
dissipation of static electricity.
[0028] In addition, as indicated above, back side coating 20 is
optically transparent at least in the ultraviolet (UV) radiation
range. Back side coating 20 is formed from optically transparent
and electrically conductive materials such as, for instance, indium
tin oxide (ITO), fluoride doped tin oxide (FTO), and doped zinc
oxide, conductive polymers, organic films with carbon nanotubes,
graphene, and metal grid structures. In sum, back side coating 20
is UV transparent and electrically conductive.
[0029] Referring now to FIG. 2, a block diagram of an optical tape
generation system 30 for producing optical tape 10 in accordance
with an embodiment of the present invention is shown. System 30
includes a roll-to-roll nano-imprint lithography process (stages 40
and 42 in FIG. 2) for generating pre-formatted optical tape such as
optical tape 10. System 30 includes a plurality of stages and a
tape transport mechanism 32 for moving optical tape 10 through the
different stages. Tape transport mechanism 32 includes a supply
reel 34 and a take-up reel 36. The stages of system 30 are between
reels 34 and 36. Supply reel 34 unwinds and dispenses optical tape
10 in its initial form. In the initial form, optical tape 10 just
includes substrate 18. Take-up reel 36 winds and wraps optical tape
10 in its final form after optical tape 10 has been processed by
the stages of system 30. In its final form, optical tape 10
includes overcoat 12, recording layer 14, polymer layer 16,
substrate 18, and back side coating 20.
[0030] The stages of system 30 beginning in order from supply reel
34 to take-up reel 36 include a back side coating stage 38, an
embossing monomer coating stage 40, an embossing/curing stage 42
having an embossing assembly 44 and a curing assembly 46, another
chemical coating/sputtering stage 48, a tension sensor stage 50,
and a tape splitter stage 52. Back side coating stage 38 coats back
side coating 20 onto the back side of substrate 18 of optical tape
10 as dispensed from supply reel 34 in its initial form. Embossing
monomer coating stage 40 coats polymer layer 16 onto the other side
of substrate 18 opposite back side coating 20. More particularly,
embossing monomer coating stage 40 dispenses a monomer onto the
other side of substrate 18 opposite back side coating 20 and this
monomer becomes polymer layer 16. At this point, optical tape 10
includes polymer layer 16 in its non-processed form (i.e., the
monomer), substrate 18, and back side coating 20 (see FIG. 3B).
Optical tape 10 is then introduced into embossing/curing stage 42.
Embossing/curing stage 42 imprints (i.e., embosses) polymer layer
16 with the information-bearing structures and cures the embossed
polymer layer 16. At this point, optical tape 10 includes polymer
layer 16 in its embossed or pre-format form, substrate 18, and back
side coating 20 (see FIG. 3C). Next, other coating/sputtering stage
48 coats recording layer 14 onto pre-format polymer layer 16 and
then coats overcoat 12 onto recording layer 14. As such, at this
point, optical tape 10 includes overcoat 12, recording layer 14,
pre-format polymer layer 16, substrate 18, and back side coating 20
(see FIG. 1). Tension sensor stage 50 senses the tension of optical
tape 10. Tension sensor stage 50 is in communication with tape
transport system 32 to provide information regarding the tension of
optical tape 10. Tape slitter stage 52 cuts optical tape 10.
[0031] Referring now to FIG. 3A, with continual reference to FIG.
2, a side elevation view of embossing/curing stage 42 of
roll-to-roll system 30 is shown. As indicated above,
embossing/curing stage 42 embosses or pre-formats
information-bearing structures in polymer layer 16 of optical tape
10. Optical tape 10 is introduced to embossing/curing stage 42 from
embossing monomer coating stage 40 of roll-to-roll system 30.
Optical tape 10 as introduced to embossing/curing stage 42 includes
polymer layer 16 in its pure non-embossed form (i.e., as a
monomer), substrate 18, and back side coating 20. FIG. 3B
illustrates a cross-sectional view of optical tape 10 just prior to
entering embossing/curing stage 42.
[0032] Embossing assembly 44 includes a drum 54. Drum 54 is mounted
for rotation about a rotational axis 56. Drum 54 has an outer
circumferential surface 58 having a predetermined pattern of
protrusions for embossing pre-formatted pattern of optically
readable embossments in the surface of polymer layer 16 as optical
tape 10 is rolled over drum 54. Optical tape 10 enters
embossing/curing stage 42 such that polymer layer 16 faces drum 54.
As optical tape 10 enters embossing/curing stage 42, a backing roll
presses optical tape 10 onto drum 54 with polymer layer 16 being in
direct pressured engagement with outer surface 58 of drum 54.
Optical tape 10 rotates with drum 54 as drum 54 rotates and the
protrusions of outer drum surface 58 create the information-bearing
structures in polymer layer 16.
[0033] While polymer layer 16 is in engaged with outer drum surface
58, curing assembly 46 applies UV radiation or illumination to
optical tape 10. Curing assembly 46 is outside of drum 54. As such,
the UV radiation is directed towards backside coating 20, substrate
18, and polymer layer 16 in that order and then towards drum 54.
The UV radiation is applied to solidify (i.e., cure) polymer layer
16 with the embossments therein prior to removal of optical tape 10
from drum 54. Separation of optical tape 10, with the now-patterned
polymer layer 16, from outer drum surface 58 is facilitated by an
up-stream backing roll. Optical tape 10 then exits from
embossing/curing stage 42 and proceeds to coating/sputtering stage
48 to receive recording layer 14 and overcoat 12. Optical tape 10
as exited from embossing/curing stage 42 includes pre-format
polymer layer 16, substrate 18, and back side coating 20. FIG. 3C
illustrates a cross-sectional view of optical tape 10 just after
exiting from embossing/curing stage 42.
[0034] As described, back side coating 20 is optically transparent
at least in the UV radiation range. As such, the base film-stack of
optical tape 10 (polymer layer 16, substrate 18, and back side
coating 20) within embossing/curing stage 42 is transparent in the
UV curing wavelength. Accordingly, curing assembly 46 can be
positioned outside of drum 54 to direct UV radiation towards
optical tape 10 pressed against drum 54 with polymer layer 16 in
direct engagement with outer drum surface 58. As UV radiation is
directed from curing assembly 46 towards drum 54, drum 54 is
preferably made of a metal such as nickel (Ni).
[0035] As described, an optical media in accordance with
embodiments of the present invention such as optical tape 10
includes a plurality of layers including back side coating 20 that
is optically transparent in at least the UV range and is
electrically conductive. Optical tape 10 is read from the "first
surface" (laser light radiation incident on the feature-containing
surface of the tape). However, optical tape 10 is just one example
of pre-formatted optical tape having back side coating 20. The
other layers of pre-formatted optical tape in accordance with
embodiments of the present invention can be varied in number,
composition, thickness, etc., to operate in a write once mode
(i.e., cannot be altered after user data is written) or an erasable
mode (i.e., a user can erase and re-use the tape). In the case of
"second surface" recording (i.e., reading/writing through the
substrate before encountering the recording layer), the composition
of the layers are adjusted accordingly.
[0036] Referring now to FIGS. 4A, 4B, 4C, and 4D, with continual
reference to FIG. 1, sectional block diagrams of different optical
tapes in accordance with other embodiments are shown. In
particular, FIG. 4A illustrates a sectional block diagram view of
an optical tape 60 having a first surface incident (air-incident)
WORM media layer composition. FIG. 4B illustrates a sectional block
diagram of an optical tape 62 having a first surface incident
(air-incident) rewritable media layer composition. FIG. 4C
illustrates a sectional block diagram of an optical tape 64 having
a second incident (substrate-incident) WORM media layer
composition. FIG. 4D illustrates a sectional block diagram of an
optical tape 66 having a second incident (substrate-incident)
rewritable media layer composition.
[0037] Each optical tape 60, 62, 64, and 66 includes back side
coating 20. Further, each optical tape 60, 62, 64, and 66 generally
includes the same layers as optical tape 10. For instance, each
optical tape 60, 62, 64, and 66 includes overcoat 12, pre-format or
embossed polymer layer 16, and substrate 18. Each optical tape 60,
62, 64, and 66 further respectively includes a recording layer 14a,
14b, 14c, and 14d.
[0038] Each optical tape 60, 62, 64, and 66 also includes a topcoat
68. Topcoat 68 is an inorganic or organic, scratch-resistant film
applied by a sputter process and provides a protective layer for
the other layers of the optical tape. Topcoat 68 may include
anti-reflective properties (e.g., low index of refraction) to
prevent unwanted reflections of laser light from wires within the
optical tape.
[0039] As shown in FIGS. 4A, 4B, 4C, and 4D, the arrangement of the
optical tape layers differs between optical tapes 60, 62, 64, and
66. Further, each optical tape 60, 62, 64, and 66 has a respective
recording layer 14a, 14b, 14c, and 14d having a composition and
arrangement of layers different from recording layer 14 of optical
tape 10 and generally different from one another. A constant is
that each optical tape 60, 62, 64, and 66 has back side coating 20
as described above.
[0040] While exemplary embodiments are described above, it is not
intended that these embodiments describe all possible forms of the
present invention. Rather, the words used in the specification are
words of description rather than limitation, and it is understood
that various changes may be made without departing from the spirit
and scope of the present invention. Additionally, the features of
various implementing embodiments may be combined to form further
embodiments of the present invention.
* * * * *