U.S. patent application number 10/147628 was filed with the patent office on 2003-11-20 for composite structure for enhanced flexibility of electro-optic displays.
Invention is credited to Freeman, Gary A..
Application Number | 20030214612 10/147628 |
Document ID | / |
Family ID | 29419058 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030214612 |
Kind Code |
A1 |
Freeman, Gary A. |
November 20, 2003 |
COMPOSITE STRUCTURE FOR ENHANCED FLEXIBILITY OF ELECTRO-OPTIC
DISPLAYS
Abstract
The invention provides a thin, lightweight, durable
electro-optic display assembly that is significantly more flexible
than known plastic electro-optic displays. The enhanced flexibility
of the plastic display assemblies according to the invention is
achieved by employing laminate display structures in which there is
little, if any, bonding between adjacent layers of the laminate
assembly.
Inventors: |
Freeman, Gary A.; (Newton,
MA) |
Correspondence
Address: |
Barbara E. Arndt, Ph.D.
Jones, Day, Reavis & Pogue
North Point
901 Lakeside Avenue
Cleveland
OH
44114
US
|
Family ID: |
29419058 |
Appl. No.: |
10/147628 |
Filed: |
May 17, 2002 |
Current U.S.
Class: |
349/12 |
Current CPC
Class: |
B32B 27/365 20130101;
B32B 27/08 20130101; G02F 1/133322 20210101; B32B 27/36 20130101;
B32B 9/045 20130101; B32B 2307/412 20130101; G02F 2201/465
20130101; G02F 1/133308 20130101; B32B 7/08 20130101; B32B 27/286
20130101; B32B 27/285 20130101; G02F 2201/503 20130101; B32B 17/06
20130101; G02F 1/133342 20210101; B32B 2457/202 20130101; B32B
2457/206 20130101; B32B 9/005 20130101 |
Class at
Publication: |
349/12 |
International
Class: |
G02F 001/1333 |
Claims
I claim:
1. A flexible electro-optic display assembly comprising: an
electro-optic display element that comprises a material having an
optical state that changes as a function of an applied electric or
magnetic field, at least one laminar layer in sliding apposition to
the display element, and optionally one or more additional
slidingly apposed laminar layers, wherein the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly; and a structure element for fastening together
the individual layers of the laminate assembly, wherein the
structure element engages a portion of the laminate assembly so as
to maintain the individual layers of the laminate assembly in the
sliding apposition, wherein upon flexing of the laminate assembly,
the individual layers slide relative to each other.
2. The flexible electro-optic display assembly of claim 1, wherein
the electro-optic display element further comprises at least one
electro-optic flexible substrate for the material having the
optical state, and wherein at least one of the laminar layers is in
sliding apposition to an outer surface of the substrate.
3. The flexible electro-optic display assembly of claim 2, wherein
the flexible substrate comprises a material selected from the group
consisting of plastic, flexible glass, a composite of a polymer and
a ceramic, a composite of a polymer and an inorganic material, and
combinations thereof.
4. The flexible electro-optic display assembly of claim 2, wherein
the material having the optical state is disposed between two
flexible electro-optic substrates bonded together, and wherein at
least one of the laminar layers is in sliding apposition to an
outer surface of one of the substrates.
5. The flexible electro-optic display assembly of claim 4, wherein
the flexible substrates individually comprise a material selected
from the group consisting of plastic, flexible glass, a composite
of a polymer and a ceramic, a composite of a polymer and an
inorganic material, and combinations thereof.
6. The flexible electro-optic display assembly of claim 1, wherein
the material having the optical state is selected from the group
consisting of a liquid crystal, a polymer dispersed liquid crystal,
an electrophoretic microparticle, a rotating bichromal microbead, a
thin film electroluminescent material, an organic light emitting
diode and an electrochomic material.
7. The flexible electro-optic display assembly of claim 1, wherein
each of the laminar layers are independently selected from the
group consisting of a polarizer, an analyzer, a reflector, an
optical compensation element, a touchscreen element, an
anti-scratch layer, a protective barrier layer, and combinations
thereof.
8. The flexible electro-optic display assembly of claim 1, wherein
the structure element for fastening together the individual layers
of the laminate assembly comprises a flexible frame structure
having an inner periphery defining a viewing area for an
electro-optic display, the flexible frame structure engaging
peripheral portions of the laminate assembly.
9. The flexible electro-optic display assembly of claim 8, wherein
the flexible frame structure comprises a rectangular shape having
four sides.
10. The flexible electro-optic display assembly of claim 8, wherein
the flexible frame structure comprises an irregular shape.
11. The flexible electro-optic display assembly of claim 8, wherein
the flexible frame structure comprises an adhesive film.
12. The flexible electro-optic display assembly of claim 8, wherein
the flexible frame structure comprises a molded plastic.
13. The flexible electro-optic display assembly of claim 12,
wherein at least one of the layers of the laminate assembly
comprises a means for facilitating engagement of the peripheral
portions of the laminate assembly by the molded plastic.
14. The flexible electro-optic display assembly of claim 13,
wherein the means for facilitating engagement is a notch or a
depression in a peripheral portion of the laminate assembly.
15. The flexible electro-optic display assembly of claim 1, wherein
the flexible frame structure comprises a watch band or a flexible
plastic card.
16. The flexible electro-optic display assembly of claim 1, wherein
the flexible structure for fastening together the individual layers
of the laminate assembly comprises at least one clip engaging a
peripheral portion of the laminate assembly.
17. The flexible electro-optic display assembly of claim 16,
wherein the peripheral portion of the laminate assembly includes a
side periphery, and the clip engages the side periphery.
18. The flexible electro-optic display assembly of claim 16,
wherein the peripheral portion of the laminate assembly includes
two side peripheries that intersect to form a corner of the
periphery, and the clip engages the corner.
19. The flexible electro-optic display assembly of claim 18,
wherein the corner is a square corner.
20. The flexible electro-optic display assembly of claim 18,
wherein the corner is a curved corner.
21. The flexible electro-optic display assembly of claim 16,
wherein the clip and the peripheral portion of the laminate
assembly include a means for facilitating engagement of the clip to
the peripheral portion.
22. The flexible electro-optic display assembly of claim 21,
wherein the means for facilitating engagement comprises a latching
element extending from the clip for engaging a corresponding
element in the peripheral portion.
23. The flexible electro-optic display assembly of claim 21,
wherein the means for facilitating engagement comprises a
rivet.
24. The flexible electro-optic display assembly of claim 1, wherein
the display assembly comprises an outer periphery for inserting the
assembly into a housing.
25. The flexible electro-optic display assembly of claim 24,
wherein the housing comprises an electronic device.
26. The flexible electro-optic display assembly of claim 24,
wherein the housing comprises a watch band, a telephone, a
calculator, a clock, a personal digital assistant, an integrated
circuit chip card, a pager, a computer, a cellular telephone, a
television set, and combinations thereof.
27. The flexible electro-optic display assembly of claim 24,
wherein the display assembly comprises a mounting means for
mounting the display assembly in a housing.
28. A flexible electro-optic display assembly comprising: an
electro-optic display element that comprises a material having an
optical state that changes as a function of an applied electric or
magnetic field, at least one laminar layer in sliding apposition to
the display element, and optionally one or more additional
slidingly apposed laminar layers, wherein the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly; and a flexible frame structure having a top
portion comprising an area for viewing an electro-optic display,
and a body portion, wherein the top portion and the body portion
comprise a housing for the laminate assembly so as to maintain the
individual layers of the laminate assembly in the sliding
apposition, wherein upon flexing of the housing, the individual
layers of the laminate assembly slide relative to each other.
29. The flexible electro-optic display assembly of claim 28,
wherein the flexible frame structure comprises a flexible plastic
card.
30. A flexible electro-optic display assembly comprising: an
electro-optic display element that comprises a material having an
optical state that changes as a function of an applied electric or
magnetic field, at least one laminar layer in sliding apposition to
the display element, and optionally one or more additional
slidingly apposed laminar layers, wherein the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly having a deflection axis; and a fastener for
fastening together the individual layers of the laminate assembly,
wherein the fastener maintains the individual layers of the
laminate assembly in a first position relative to one another at
the fastener, and wherein upon flexing of the display assembly, the
individual layers slide relative to each other in regions outside
of the fastener.
31. The flexible electro-optic display assembly of claim 30,
wherein the fastener is rigid.
32. The flexible electro-optic display assembly of claim 30,
wherein the fastener is flexible.
33. The flexible electro-optic display assembly of claim 30,
wherein the display assembly has a periphery comprising at least a
first side and a second side that intersect to form a corner area
of the assembly, and the fastener is located in the corner area of
the display assembly.
34. The flexible electro-optic display assembly of claim 30,
wherein the fastener is a rivet.
35. The flexible electro-optic display assembly of claim 33,
wherein the fastener comprises a rivet assembly comprising an
alignment portion that aligns the rivet assembly with the first
side and the second side of the display assembly periphery at the
corner area.
36. A flexible electro-optic display assembly comprising: an
electro-optic display element that comprises a material having an
optical state that changes as a function of an applied electric or
magnetic field, at least one laminar layer in sliding apposition to
the display element, and optionally one or more additional
slidingly apposed laminar layers, wherein the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly having a deflection axis; and at least two
fasteners placed on a fixation axis oriented at a non-zero angle
relative to the deflection axis for fastening together the
individual layers of the laminate assembly on the fixation axis,
wherein the fasteners maintain the individual layers of the
laminate assembly in a first position relative to each other along
the fixation axis, and wherein upon flexing of the display
assembly, the individual layers outside of the fixation axis slide
relative to each other along the deflection axis.
37. The flexible display assembly of claim 36, wherein the fixation
axis is orthogonal to the deflection axis.
38. The flexible display assembly of claim 36, wherein the fastener
is flexible.
39. The flexible display assembly of claim 36, wherein the fastener
is rigid.
40. A flexible electro-optic display assembly comprising: a first
electro-optic display element and a second electro-optic display
element, wherein the first and second electro-optic display
elements independently comprise a material having an optical state
that changes as a function of an applied electric or magnetic
field, at least one laminar layer in sliding apposition to the
first or the second display element, and optionally one or more
additional slidingly apposed laminar layers, wherein the first and
second electro-optic display elements, the at least one laminar
layer and the optional one or more additional laminar layers
comprise individual layers of a laminate assembly; and a structure
element for fastening together the individual layers of the
laminate assembly, wherein the structure element engages a portion
of the laminate assembly so as to maintain the individual layers of
the laminate assembly in the sliding apposition, wherein upon
flexing of the laminate assembly, the individual layers slide
relative to each other.
41. The flexible electro-optic display assembly of claim 40,
wherein the electro-optic display assembly comprises a front
portion and a back portion, and wherein the first and the second
electro-optic display elements are positioned in the laminate
assembly such that the first electro-optic display element provides
an image on the front portion of the electro-optic display assembly
and wherein the second electro-optic display element provides an
image on the back portion of the electro-optic display assembly.
Description
BACKGROUND OF THE INVENTION
[0001] Commercially, it is highly desirable for an electronic
display to be as thin and light as possible while still maintaining
a high degree of ruggedness and imperviousness to forces that are a
consequence of shock and drop. In the area of mobile electronics,
such as cellular telephones, personal digital assistants (PDAs),
and the like, size and weight are critical factors to the
commercial success of a product. However, breakage of the
electro-optic displays within these devices remains the primary
cause of repairs and product returns.
[0002] In general, electro-optic displays contain an electro-optic
material having an optical state that changes as a function of an
applied electric or magnetic field. The electro-optic material can
be contained on a single substrate or can form an electro-optic
layer between two substrates that are bonded together.
Traditionally, electro-optic displays have been manufactured using
glass substrates, making the product heavy, rigid and prone to
breakage. Lighter, thinner displays employing rigid plastic
substrates also require structural support and shock absorption
properties to prevent or reduce breakage. Therefore, attention in
the industry has turned to the need for electro-optic displays that
are thin and lightweight and can also be bent or flexed while
maintaining desirable durability.
[0003] There are many useful applications for such flexible
products. For example, so-called `electronic paper` in which fiber
paper is replaced with a display would be much more compelling as a
product if the electro-optic display could be rolled up or folded
like traditional paper. Wearable electronics, such as pagers,
computers or multifunction watches, and the like, would be more
comfortable to the wearer if the display conformed to the user's
body. Integrated circuit chip cards or smart cards, which have
strict flexure life-test performance standards, would be able to
incorporate flexible electro-optic displays and still conform to
those standards.
[0004] In addition to the electro-optic layer and substrate(s),
electro-optic displays such as liquid crystal displays (LCDs)
require additional layers such as polarizers, analyzers,
reflectors, and the like, to achieve the desired electro-optic
effect. In applications requiring input by a user, an electro-optic
display of any type can also include a touchscreen incorporated
into the overall display assembly. Often, electro-optic display
assemblies can include a protective barrier layer, an anti-scratch
layer, and the like.
[0005] Conventionally, all of the layers of the electro-optic
display assembly are bonded together by optically-clear adhesives,
or other similar means. This results in a laminate having an
increased rigidity, in much the same way that bonding multiple thin
layers of wood together results in a plywood sheet having
significantly enhanced rigidity and strength. Even when the
individual layers of the laminate stack are very thin, the overall
flexibility of the bonded laminate is still significantly less than
the flexibility of a single sheet of plastic having an equivalent
thickness. The relatively inflexible mechanical properties of these
plastic displays are therefore considered detrimental for
performance in applications in which very flexible plastic displays
are desirable.
[0006] There is a need, therefore, for multiple layer flexible
electro-optic displays that have enhanced flexibility.
SUMMARY OF THE INVENTION
[0007] The invention provides a thin, lightweight, durable
electro-optic display assembly that is significantly more flexible
than known plastic electro-optic displays, while eliminating the
need for additional structural support and shock absorption that
glass displays and even rigid plastic displays require. The
enhanced flexibility of the electro-optic display assemblies
according to the invention is achieved by employing laminate
display structures in which there is little, if any, bonding
between adjacent layers of the laminate assembly. If any bonding is
used, it is localized to areas where stress induced by flexing of
the laminate assembly is minimized. As a result, the flexible
electro-optic display assemblies according to the invention retain
all the advantages of known plastic electro-optic displays, while
providing desirably enhanced flexibility.
[0008] In one embodiment, the invention provides a flexible
electro-optic display assembly that comprises an electro-optic
display element that comprises a material having an optical state
that changes as a function of an applied electric or magnetic
field, at least one laminar layer in sliding apposition to the
display element, and optionally one or more additional slidingly
apposed laminar layers, wherein the electro-optic display element,
the at least one laminar layer and the optional one or more
additional laminar layers comprise individual layers of a laminate
assembly; and a structure element for fastening together the
individual layers of the laminate assembly, wherein the structure
element engages a portion of the laminate assembly so as to
maintain the individual layers of the laminate assembly in the
sliding apposition, wherein upon flexing of the laminate assembly,
the individual layers slide relative to each other.
[0009] The structure element can comprise a flexible frame
structure having an inner periphery defining a viewing area for a
liquid crystal display, the flexible frame structure engaging
peripheral portions of the laminate assembly so as to maintain the
individual layers of the laminate assembly in the sliding
apposition, wherein upon flexing of the display assembly, the
individual layers slide relative to each other. The resulting
flexible electro-optic display assembly can be mounted into any
desired device, such as a cellular telephone, computer, watch band,
PDA, pager, clock, integrated circuit chip card, or the like.
Alternatively, the device itself can provide the flexible frame
structure for the laminate assembly, such as by molding a portion
of the device over the laminate assembly.
[0010] In another embodiment, the invention provides a flexible
electro-optic display assembly such as that described in the
embodiment above, wherein the structure element, such as a flexible
frame structure, has a top surface portion comprising an area for
viewing a liquid crystal display, and a body portion, wherein the
top portion and the body portion comprise a housing for the
laminate assembly so as to maintain the individual layers of the
laminate assembly in the sliding apposition, wherein upon flexing
of the housing, the individual layers of the laminate assembly
slide relative to each other. An exemplary use for this embodiment
is an integrated circuit chip card.
[0011] In yet another embodiment of the flexible electro-optic
display assembly of the invention, the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly having a deflection axis. A fastener is provided
for fastening together the individual layers of the laminate
assembly. The fastener maintains the individual layers of the
laminate assembly in a first position relative to one another at
the fastener, and wherein upon flexing of the display assembly, the
individual layers slide relative to each other in regions outside
the fastener.
[0012] The flexible plastic electro-optic display assemblies
according to embodiments of the invention are especially suitable
for, but not limited to, applications such as "electronic paper"
and the like, wearable electronics, such as computers,
multifunction watches, and the like, and other electronic and/or
mobile communication device applications, such as cellular
telephones, PDAs, pagers, calculators, clocks, integrated circuit
chip cards, computers, television sets, combinations of the
foregoing, and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A is a cross-sectional view of a flexible
electro-optic display assembly according to the invention,
comprising a liquid crystal display element and laminar layers in
sliding apposition, held together by a structure element such as a
flexible frame structure.
[0014] FIG. 1B is a view similar to FIG. 1A, illustrating spacing
elements that can be used to prevent optical interference patterns
resulting when the inner surfaces come in contact.
[0015] FIG. 1C is a view similar to FIG. 1A, illustrating two
electro-optic display elements in a single electro-optic display
assembly.
[0016] FIG. 2 is a plane view of an embodiment of the flexible
electro-optic display assembly, such as that illustrated in FIGS.
1A, 1B and 1C.
[0017] FIG. 3 is a plane view of an embodiment of the flexible
electro-optic display assembly wherein the structure element
contains means for mounting the display assembly into a device or
housing.
[0018] FIG. 4 is a plane view of an embodiment of the flexible
electro-optic display assembly in which the structure element
comprises a watch band.
[0019] FIG. 5 is a cross-sectional view of the display assembly
illustrated in FIG. 4.
[0020] FIGS. 6A and 6B are cross-sectional views of embodiments of
a laminate assembly housed in a flexible plastic card which
comprises a structure element for holding together the layers of
the laminate assembly in sliding apposition.
[0021] FIGS. 7A and 7B are embodiments of the inside of the top
cover of a flexible plastic card showing circuitry and battery
connections.
[0022] FIG. 8 illustrates an embodiment of the flexible
electro-optic display assembly wherein the layers of the laminate
assembly are held together by one or more fasteners placed on a
fixation axis orthogonal to a deflection axis.
[0023] FIG. 9 illustrates an alternate placement of fasteners on a
fixation axis orthogonal to a deflection axis.
[0024] FIG. 10 illustrates a flexing of an embodiment according to
FIG. 9.
[0025] FIG. 11 illustrates an embodiment of the flexible
electro-optic display assembly where the layers of the laminate
assembly are held together by a single fastener in conjunction with
a collar positioned along a second orthogonal axis.
[0026] FIG. 12 illustrates a detail view of the collar of FIG.
11.
[0027] FIGS. 13A, B and C illustrate an alternative embodiment of
FIGS. 8 and 9, wherein the fasteners take the form of clips.
[0028] FIGS. 14A and B illustrate details of the clips used in FIG.
13.
[0029] FIG. 15 illustrates an embodiment in which a single rivet
assembly is employed to hold together the layers of the laminate
assembly.
[0030] FIGS. 16A, B and C illustrate detail views of the rivet
assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The enhanced flexibility of the electro-optic display
assemblies according to the invention is achieved by employing
laminate display structures in which there is little, if any,
bonding between adjacent layers of the laminate assembly. If any
bonding is used, it is localized to areas where stress induced by
flexing of the laminate assembly is minimized. Therefore, the
invention provides an electro-optic display assembly having
laminate layers with enhanced flexibility over known display
assemblies. The invention can be applied to any electro-optic
display having two or more layers including, but not limited to,
displays employing electro-optic materials such as liquid crystals,
polymer dispersed liquid crystals, electrophoretic microparticles,
rotating bichromal microbeads, thin film electroluminescent
material, thin film photoluminescent material, organic light
emitting diodes and other electrochomic materials, and the
like.
[0032] An electro-optic display element can be defined as an
element that comprises a material having an optical state that
changes as a function of an applied electric or magnetic field,
including photoelectric-induced luminescence. That is, the material
is "switchable" from one optical state to another. Generally, the
switchable material is associated with one or more substrates on
which electrodes may be located to change the optical state of the
material in accordance with a desired pattern.
[0033] There are a variety of different types of electro-optic
displays employing the switchable electro-optic material disposed
between two substrates that are bonded together to form a so-called
microencapsulated display. For example, electrophoretic displays
achieve images by electrophoresis, the rapid migration of
microparticles in colloidal suspensions. In this type of display,
light scattering particles are moved within a dyed colloidal
suspension by electrostatic forces. The particles either move
toward the viewer, in which case the typically white particles are
observed, or to the surface away from the viewer, in which case the
white particles are hidden by the dark dye.
[0034] Cholesteric displays employ a cholesteric liquid crystal
material that, when sandwiched between conducting electrodes, can
be switched between two stable states--the so-called focal conic
and planar states--in which the helical structures of the liquid
crystal have different orientations. In the focal conic state, the
helical structures are unaligned and the liquid crystal is
transparent. In the planar state, the axes of the helical
structures are all perpendicular to the display's surface resulting
in essentially monochromatic transmission by the display.
[0035] Another type of microencapsulated display employs
microscopic beads, randomly dispersed and held in place between two
plastic substrates by a flexible elastomeric matrix of oil-filled
cavities. The balls have strongly contrasting hemispheres, black on
one side and white on the other. The white side is highly
reflective, while the black side absorbs light. Each hemisphere has
a unique intrinsic charge, resulting in a force on the ball when an
electric field is applied and the axis of the ball is not aligned
with the field. The side of the ball presented for display depends
on the polarity of the voltage applied to the electrode.
[0036] Liquid crystal displays (LCDs) are attractive because of the
low drive voltages required to switch them, their relatively fast
response times, the wide availability of drive electronics, and the
significant intellectual and manufacturing investment in the
technology. Attempts have been made to develop LCDs that intermix
the liquid crystal within a polymer matrix in order to make them
compatible with plastic substrates, one example being polymer
dispersed displays (PDLCDs). PDLCDs are fabricated by intermixing
the liquid crystal and a pre-polymer into a solution prior to
assembling the display. After assembling the display, the polymer
is cured, typically by ultraviolet light. During the polymerization
the LC separates out from the polymer into microscopic droplets.
Since the droplets of LC are not in contact with any alignment
layer, the orientation of the molecules is random and light is
scattered by the droplets. Applying a voltage to the electrodes of
the PDLCD causes the LC molecules to become aligned, resulting in
the display becoming transparent.
[0037] All of the foregoing electro-optic displays can employ
layers on an outer surface of one or more of the substrates such
as, but not limited to, polarizers, analyzers, reflectors, or other
optical compensation elements, anti-scratch layers and other
protective barrier layers, and the like, and combinations of any of
the foregoing.
[0038] There are also a variety of electro-optic displays employing
an electro-optic (or photo-optic) material disposed on one
substrate. For example, thin film electroluminescent (TFEL)
displays employ a glass sheet as a substrate that is coated with an
electrode (e.g., indium tin oxide) and a light-emitting phosphor
film (e.g., ZnS:Mn). A thin film black layer is then deposited to
provide optical contrast, followed by application of a rear
electrode (e.g., aluminum). The display is then "encapsulated" with
a solid gel and a glass cover plate to keep out moisture. These
displays also can employ additional layers on an outer surface of
the electro-optic layer and/or the substrate layer, such as but not
limited to, absorption and interference filters, reflective layers,
protective layers, and the like.
[0039] Organic light emitting diodes (OLEDs) form another type of
electro-optic display based on light emission by phosphorescent
phosphors upon electrical stimulation. The OLED can employ a glass
substrate as a substrate that is coated with an electrode and a
light-emitting small molecule based on, e.g., aluminum quinolate
(Alq3). These displays also can employ additional layers on an
outer surface of the electro-optic layer and/or the substrate
layer, such as but not limited to, polarizer layers, reflective
layers, protective layers, and the like.
[0040] Each of the foregoing embodiments of electro-optic displays
can additionally include a touchscreen element incorporated into
the overall display assembly, for applications requiring input by a
user.
[0041] In one embodiment, the invention provides a flexible
electro-optic display assembly comprising an electro-optic display
element that comprises a material having an optical state that
changes as a function of an applied electric or magnetic field, at
least one laminar layer in sliding apposition to the display
element, and optionally one or more additional slidingly apposed
laminar layers, wherein the electro-optic display element, the at
least one laminar layer and the optional one or more additional
laminar layers comprise individual layers of a laminate assembly;
and a structure element for fastening together the individual
layers of the laminate assembly, wherein the structure element
engages a portion of the laminate assembly so as to maintain the
individual layers of the laminate assembly in the sliding
apposition, wherein upon flexing of the laminate assembly, the
individual layers slide relative to each other.
[0042] In embodiments illustrated in FIGS. 1A and 1B, a flexible
electro-optic display assembly 1 according to the invention
includes an electro-optic display element that contains an
electro-optic material 2, disposed between two substrates 3 that
are bonded together, such as by a gasket 4. Bonding between two or
more substrates can be achieved by an adhesive, by ultrasonic
welding, by laser cutting, or the like. The adhesive can be an
ultraviolet cured adhesive, if desired. The type of bonding of the
substrates is not critical to the invention. Although two
substrates are illustrated, an electro-optic display element having
one substrate is not excluded. Further, the display element is not
limited to any one type of element design. The type of
electro-optic material employed and the configuration of the
material with or without other compounds or electrode materials
within the element are not critical to the invention. In the
embodiment illustrated in FIG. 1, spacers 5 are shown as an example
of other non-limited materials that can be included in the
electro-optic display element.
[0043] The substrate(s) 3 can be made of commonly used optically
clear materials such as, but not limited to, cast allyl-diglycol
carbonate, or the like, which is a relatively rigid material.
Flexible clear plastic materials including, but not limited to,
polycarbonate, polyethersulfone, polyethylene naphthalate, and the
like, that are well known to those skilled in the art, can also be
employed as the substrate(s). Alternatively, the substrate(s) may
be made of clear glass, preferably a very thin flexible glass. For
example, a suitable flexible glass substrate is about 0.030 mm
thick and available from Schott Glass Technologies, Inc., Duryea,
Pa. If desired, the substrate can comprise a composite of a polymer
and a ceramic or a composite of a polymer and an inorganic
material, which are well known materials. Moreover, if two or more
substrates are employed, they can be individually made from
different materials. An advantage of the display assembly according
to the invention is that commonly obtained plastic, glass or
composite substrate materials can be employed that are optimized
for such desirable features as hardness, scratch-resistance,
puncture resistance, and the like, but can have very little
elasticity or be very flexible.
[0044] The display assembly 1 also includes one or more layers
adjacent to an outer surface of the electro-optic material and/or
to at least one of the substrates 3, to achieve the desired
electro-optic effect. These layers can include, but are not limited
to, polarizers 6, a reflector 7, and the like, but can include
other or alternative desirable layers, such as an analyzer, an
optical compensation element, or other layers known to those of
ordinary skill in the art of electro-optic displays. Commonly used
polarizers, analyzers and reflectors can be employed without
limitation. In addition to enhancing the electro-optic effect,
these layers can add desired features, such as hardness and scratch
resistance or anti-reflection layers to the display assembly. Other
layers can include an anti-scratch layer or any type of protective
barrier layer. Additionally, the layers may include a flexible
touchscreen input subassembly, currently manufactured and
incorporated into rigid products such as Palm Pilots or other PDAs.
The layers, together with the electro-optic display element are all
slidingly apposed and comprise individual layers of a laminate
assembly 8.
[0045] In the embodiment shown in FIGS. 1A and 1B, the individual
layers of the laminate assembly are held together in sliding
apposition by a structure element, such as a flexible frame
structure 9 having an inner periphery 10 defining a viewing area 11
which is better seen in FIG. 2. The flexible frame structure
engages peripheral portions of the laminate assembly so as to
maintain the layers of the laminate assembly 8 in the sliding
apposition until flexing of the display assembly allows the
individual layers to slide relative to each other. The materials
used for the flexible frame structure are preferably softer and
more elastic than those used for the substrates, and have no
requirement to be optically clear. For example, the flexible frame
can be made from vinyl, urethane, polyethylenes, polyvinyl
chloride, cellulose derivatives, vinyl resins, polystyrenes,
polyamides, polyimides, polycarbonates, paper, rubber; mica tape,
plate or sheet, glass cloth, and the like. The flexible frame can
be made from a polymer film, preferably an adhesive-back film.
Exemplary films can include, but are not limited to, Kapton.RTM.,
Nomex.RTM. and Mylar.RTM. (E. I. duPont de Nemours Co.). For
example, an adhesive-based film can be folded over the laminate
stack. An optically clear film can cover all or part of the viewing
area for the electro-optic display, if desired.
[0046] In any of the embodiments according to the invention,
spacing elements 12 that prevent direct contact between the inner
surfaces of the laminate layers may be incorporated, as illustrated
in FIG. 1B. The spacing elements are used to prevent optical
interference patterns resulting when the inner surfaces come in
contact. Such patterns are commonly called Newton rings or fringes.
Spacing between layers is usually maintained at less than 10 mils,
though the exact gap is not critical other than that the gap must
be greater than 1/2 the longest wavelength of light of interest.
Methods commonly used by those skilled in the art include printing
the spacer elements onto at least one of the surfaces. Other
methods may involve use of adhesive-coated microspheres such as
those used to maintain the cell gap in a liquid crystal cell.
[0047] FIG. 1C illustrates an embodiment of the electro-optic
display assembly that includes a second electro-optic display
element 13, including its attendant layers that are similar to
those of the display element 12 and are designated with an "A" in
addition to the numerical identification. That is, a flexible
electro-optic display assembly is provided that comprises a first
electro-optic display element and a second electro-optic display
element, wherein the first and second electro-optic display
elements independently comprise a material having an optical state
that changes as a function of an applied electric or magnetic
field, at least one laminar layer in sliding apposition to the
first or the second display element, and optionally one or more
additional slidingly apposed laminar layers, wherein the first and
second electro-optic display elements, the at least one laminar
layer and the optional one or more additional laminar layers
comprise individual layers of a laminate assembly; and a structure
element 9 for fastening together the individual layers of the
laminate assembly, wherein the structure element engages a portion
of the laminate assembly so as to maintain the individual layers of
the laminate assembly in the sliding apposition, wherein upon
flexing of the laminate assembly, the individual layers slide
relative to each other. The first and second display elements may
be the same or may be different from each other. An advantage of
this embodiment is that the electro-optic display assembly can
comprise a front portion 11 and a back portion 11A, and the first
and the second electro-optic display elements are positioned in the
laminate assembly such that the first electro-optic display element
provides an image on the front portion of the electro-optic display
assembly and the second electro-optic display element provides an
image on the back portion of the electro-optic display
assembly.
[0048] FIG. 2 illustrates one embodiment of a structure element
such as the flexible frame in which the shape of the frame is
generally a rectangle having four sides 12. However, a flexible
frame can have a variety of different shapes, such as oval or
irregular shapes, and the like, without limitation. A flexible tail
13 for connecting the liquid display element to conventional
display driver electronics is also illustrated. The flexible frame
can have an outer periphery 14 for inserting the flexible display
assembly into a housing (not shown) such as a mobile communications
device, a watch, a PDA, or the like, or other electronic device,
such as a cellular telephone, a calculator, a clock, an integrated
circuit chip card, a pager, a computer, a television set, or the
like. Mechanical features can be added to the frame to aid with
mounting of the flexible electro-optic display assembly into the
device into which it is to be integrated. For example, as
illustrated in FIG. 3, mounting holes 15 can be placed between the
outer and inner peripheries of the flexible frame structure.
Alternatively, exemplary mounting means can be, but are not limited
to, pegs, rivets, velcro, or the like, or combinations of these.
The mounting means can be flexible or rigid. The mounting means can
employ adhesives for mounting the display assembly into the
device.
[0049] In another embodiment of the invention, the structure
element can engage the peripheral portions of the laminate assembly
by overmolding, such as with a urethane or other thermoplastic
polymer. In one such embodiment, the device in which the laminate
assembly is to be employed can itself serve as the structure
element. A non-limiting example of such a device is illustrated in
FIGS. 4 and 5, which illustrate a watch band 20 that is a structure
element for maintaining the individual layers of the laminate
assembly of the electro-optic display 21 in the sliding apposition.
The device, such as the watch band can further comprise
conventional electronics, battery and controls 22, as known to
those skilled in the art of electro-optic displays. As shown more
clearly in FIG. 5, the flexible electro-optic display assembly
includes the electro-optic display element 23 comprising the
electro-optic material dispersed between substrates 24 and 25 and a
reflector layer 26 slidingly apposed to an outer surface of one of
the substrates 24. A clear protective top layer 27 can optionally
be added to protect the display assembly from damage.
[0050] It may be desirable to provide a means for more firmly
integrating the molding with the flexible laminate assembly. For
example, small holes or notches 28 can be introduced in the
peripheral areas of the laminate stack that can become filled with
the polymer during the molding process. Such notches or holes can
be produced, for example, by die cutting or by laser, such as a
carbon dioxide laser, by known methods.
[0051] In another embodiment, the flexible electro-optic display
assembly comprises a flexible frame structure having a top portion
comprising an area for viewing the electro-optic display, and a
body portion, wherein the top portion and the body portion comprise
a housing for the laminate assembly so as to maintain the
individual layers of the laminate assembly in the sliding
apposition, wherein upon flexing of the housing, the individual
layers of the laminate assembly slide relative to each other.
[0052] An illustrative example of this embodiment is shown in FIGS.
6A and 6B, in which the laminate assembly 30 is incorporated into a
laminated flexible plastic card 31, such as an integrated circuit
chip card. In the embodiment shown in FIG. 6A, the card comprises a
top cover 32 for viewing the electro-optic display 33 and a body
portion 34 that is preferably opaque. The laminate assembly 30 is
layered and fitted into an appropriately sized opening 35 in the
body portion 34 and the top cover 32 is laminated to the body
portion 34, thus forming a housing that encloses and holds together
the layers of the laminate assembly in sliding apposition. In an
alternative embodiment shown in FIG. 6B, the body portion 34
comprises an inner body 36 and a bottom cover 37. The top cover 32,
the inner body 36 and the bottom cover 37 are configured to provide
an appropriately sized opening 38 for the laminate assembly 30 to
hold together the layers of the laminate assembly in sliding
apposition and to contain the assembly within the housing. Upon
flexing of the plastic card, the individual layers of the laminate
assembly slide relative to each other. An advantage of providing a
laminate assembly having slidably apposed layers into a flexible
plastic card is that the card can flex sufficiently to meet strict
flexure life-test performance standards without delamination of the
electro-optic display.
[0053] The integrated circuit chip card can further comprise
electronic connections to the laminate assembly, integrated
circuits, battery and controls 39, including micromodular
electronic systems and the like, as known to those skilled in the
art of electronic displays in integrated circuit chip cards, such
as the chip card disclosed in U.S. Pat. No. 6,019,284, the
disclosure of which is hereby incorporated by reference.
[0054] FIGS. 7A and 7B illustrate more detailed views of
embodiments of the inside of the top cover of a smart card 131 and
the non-viewing area surface of the laminate assembly. As shown in
FIG. 7A, the electro-optic display assembly 130 is connected to a
micromodule (a printed circuit board) 132 having an integrated
circuit 133 for smart card functions. Also illustrated are
additional integrated circuits and passive components 134 located
on the display assembly 130. A battery 135 is connected to the
display assembly by a contact ledge 136. The display assembly is
connected to the micromodule by a contact ledge 137. FIG. 7B
illustrates another embodiment of the inside of the top cover that
does not include a separate micromodule. That is, the display
assembly 130 comprises a micromodule area 138 containing integrated
circuit 133 for smart card functions. The battery 135 is connected
to the micromodule area 138 of the display assembly 130 by the
contact ledge 136.
[0055] In some embodiments of the structure element such as the
flexible frame structure and/or fasteners described herein, when
the display is not in flexed configuration, the structure element
holds the layers of the laminate assembly in the correct alignment
to allow the display to function correctly. When the display is
flexed into a curved shape, the performance of the display may be
degraded. For those embodiments which have degraded performance
during flexure, once the display is allowed to resume its original
shape the display will regain its original performance
characteristics. In other embodiments, the laminate assembly and
structure element are manufactured in a pre-flexed configuration
and the structure element holds the layers of the flexed laminate
assembly in the correct alignment to allow the display to function
correctly.
[0056] In yet another embodiment of the flexible electro-optic
display assembly of the invention, the electro-optic display
element, the at least one laminar layer and the optional one or
more additional laminar layers comprise individual layers of a
laminate assembly having a deflection axis. A fastener is provided
for fastening together the individual layers of the laminate
assembly. The fastener maintains the individual layers of the
laminate assembly in a first position relative to one another at
the fastener, and wherein upon flexing of the display assembly, the
individual layers slide relative to each other in regions outside
of the fastener.
[0057] For example, FIGS. 8 and 9 illustrate a laminate assembly 40
that is held together by two or more rigid or flexible fasteners
such as, but not limited to, two or more rivets 41 placed on a
so-called fixation axis 43 that is at a non-zero angle to a
deflection axis 42. That is, the layers of the laminate assembly 40
cannot slide relative to each other on the fixation axis. However,
the layers can slide relative to each other outside of the fixation
axis. The deflection axis 42 is determined by the axis at which the
assembly is bent; that is, it is non-specific to a particular
display and will change depending on the direction in which the
display is bent. As a non-limiting example, the fixation axis 43
along which the rivets 41 are placed can be at a side 44 of the
laminate assembly or can be centrally located, as illustrated in
FIGS. 8 and 9, respectively. However, the fixation axis can be
located anywhere on the laminate assembly depending on the
configuration and location of the deflection axis. In a similar
embodiment illustrated in FIG. 10, two or more fasteners 50 can
hold together the layers of the laminate assembly 51 and are placed
on an axis 52 orthogonal to a deflection axis 53. In this
embodiment, the orthogonal axis is a fixation axis. The layers can
slide relative to each other outside of the fixation axis during
flexing of the laminate assembly.
[0058] In the embodiment illustrated in FIGS. 11 and 12, a single
fastener, such as a rivet 61 is used in conjunction with a collar
62 positioned along a fixation axis 63. In this embodiment, the
collar positioned along the fixation axis maintains rotational
alignment between the layers of the laminate assembly 60 about the
axis 64 of the fastener 61, but still allows for flexure along the
displacement axis 65. The collar 62 may be a rigid, semi-flexible,
or flexible element that may be either fully circumferential around
the laminate assembly 60 or only semi-circumferential. A
semi-circumferential collar comprises an elongated portion 66
having opposite ends 67 and 68. A fully circumferential collar
comprises an additional elongated portion 69 connecting the ends 67
and 68. The collar may also contain features which constrain the
motion of one or more layers relative to each other along the
displacement axis. For example, as illustrated in FIG. 12, molded
protrusions 70 on an inner wall 71 of the collar keep the collar
from sliding off the laminate assembly.
[0059] In an alternative embodiment illustrated in FIGS. 13 and 14,
one or more clips 81 can be employed as fasteners to hold together
the laminate stack forming the display 80. The clips can be located
on the sides of the display. However, as illustrated in FIG. 13A,
the clips 81 can be located in the corners of the display if the
display is rectangular in shape. That is, the display assembly has
a periphery comprising at least a first side 82 and a second side
83 that intersect to form a corner area 88 of the assembly, and the
fastener is located in the corner area of the display assembly. If
the display has curved outer edges, the clips can be formed so as
to closely conform to the perimeter of the display edge with which
it comes into contact. Possible configurations of a clip 90
conforming to a side of the display and a clip 91 conforming to a
corner of the display are illustrated in FIGS. 14A and 14B
respectively. It is also preferable that the upper 93 or lower 94
inner surfaces, respectively, of the clips which come into contact
with the laminate stack have protrusions 92 that extend into holes
or depressions in the outer layers of the laminate stack so as to
retain the clips in the desired position relative to the laminate
stack. For example, FIG. 13B illustrates a hole or depression
pattern 84 in a top sheet 85 of the laminate stack. FIG. 13C
illustrates a hole or depression pattern 86 in a bottom sheet 87 of
the laminate stack. The protrusions may be on both the upper and
lower inner surfaces of the clips, but it is preferable that the
protrusions only be on one of the inner surfaces. The latching
mechanism provided by the protrusion/hole combination may be
augmented with a heat or ultraviolet light activated adhesive on
the inner surface with the protrusion. This single-sided latching
mechanism allows for all laminate layers to slide apposing with
each other. Additionally, the side of the display on which the
single-sided latch is located can be alternated so that each outer
laminate layer can have at least one clip latched to it.
[0060] In another embodiment, a single rivet assembly 96 may be
used as shown in FIG. 15 and in more detail in FIG. 16 wherein the
rivet is located in a corner of the display 95. Features are
incorporated in the rivet assembly 96 that, when riveted to the
laminate stack, align with edges of the stack that intersect at the
corner at which the rivet is located. FIGS. 16A, 16B and 16C
illustrates an outer oblique view of the top half of the rivet
assembly 96, a rear view of the top of the rivet assembly, and a
view of the bottom half of the rivet assembly, respectively,
showing corner alignment rails 97 and insertion hole 98 for a rivet
99. In this way, a single rivet with corner alignment features can
be used to hold together the laminate stack, both rotationally and
laterally, while still allowing for the individual layers to slide
against each at all points other than at the rivet.
[0061] In any of these embodiments incorporating one or more
fasteners, preferably optically clear fasteners may be used in the
area for viewing the electro-optic display, if desired. Means for
fastening the layers together can also include other conventional
fasteners, such as pins, bolts, screws, clamp pairs, and the like,
known to those skilled in the art. The fasteners may be rigid or
flexible.
[0062] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to make and use the invention. The patentable
scope of the invention is defined by the claims, and can include
other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they
have elements that do not differ from the literal language of the
claims, or if they include equivalent elements with insubstantial
differences from the literal language of the claims.
* * * * *