U.S. patent application number 10/119138 was filed with the patent office on 2002-08-29 for seamless tiled active matrix liquid crystal display.
Invention is credited to Ge, Shichao.
Application Number | 20020118321 10/119138 |
Document ID | / |
Family ID | 27373141 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020118321 |
Kind Code |
A1 |
Ge, Shichao |
August 29, 2002 |
Seamless tiled active matrix liquid crystal display
Abstract
A seamless tiled display employs active liquid crystal display
(LCD) and backlight. The active matrix elements of active LCD are
mounted on the inside or outside of the front plate or back plate
of LCD. A thin front plate and a thin sealing wall are used to
reduce the seam width of the tiled LCD. A laser cutting is used for
a thin LCD sealing. A spacer added adhesive array is deposited
between pixels and between front plate and back plate to guarantee
the uniformity of LC cells thickness. A laser riveting is still
used for making a robust plastic LCD. A reflective layer is
deposited on the side wall of back plate to reflect the light
emitted from the backlight and to reduce the apparent seam width.
In the backlight, there can be at least one set of red, green and
blue light source operated at color sequential mode to display a
color image without the use of color filters.
Inventors: |
Ge, Shichao; (San Jose,
CA) |
Correspondence
Address: |
James S. Hsue
Skjerven Morrill MacPherson LLP
Suite 2800
3 Embarcadero Center
San Francisco
CA
94111
US
|
Family ID: |
27373141 |
Appl. No.: |
10/119138 |
Filed: |
April 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10119138 |
Apr 8, 2002 |
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09266448 |
Mar 11, 1999 |
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6369867 |
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60077675 |
Mar 12, 1998 |
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60081085 |
Apr 8, 1998 |
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Current U.S.
Class: |
349/73 |
Current CPC
Class: |
G02F 1/133305 20130101;
G02F 1/13336 20130101 |
Class at
Publication: |
349/73 |
International
Class: |
G02F 001/133 |
Claims
What is claimed is:
1. A tiled active liquid crystal display device, comprising a
plurality of LCD tiles, each tile comprising: an active matrix
liquid crystal display, said display having a thin front plate and
liquid crystal (LC) cells; a backlight with a light source; means
for applying the signals to said display to modulate transmittance
of the liquid crystal (LC) cells, and of light from the backlight
transmitted by said LC cells to display an image; said device
further comprising means assembling said LCD tiles to form a
super-large-screen display.
2. The device of claim 1, wherein thickness of said thin front
plate is in the range of about 0.02 to 0.7 mm.
3. The device of claim 1, wherein each of at least some of said LCD
tiles has an outside active matrix control device mounted on an
outside surface of such LCD tile.
4. The device of claim 3, wherein said outside active matrix
control device is a field effect transistor, bipolar transistor,
diode or varistor.
5. The device of claim 3, wherein said outside active matrix
control device controls one LC cell or one group of LC cells.
6. The device of claim 1, wherein said light source is a cold
cathode fluorescent lamp (CCF), hot cathode fluorescent lamp (HCFL)
or light emitting diode (LED).
7. The device of claim 1, wherein said light source includes a
white light source, and a color filter array on surfaces of said
LCD tiles to display a multi-color or full-color image or
characters etc.
8. The device of claim 1, wherein said light source comprises at
least one set of red, green, blue (R, G, B) CCFLs or LEDs, and
wherein said applying means causes said tiled LCD to be operated at
a color sequential mode to display a full-color image or
characters.
9. The device of claim 1, wherein said light source includes a
driver for controlling light intensity, said driver including a
brightness adjustment circuit for adjusting the brightness of said
light source manually or automatically, to adjust brightness in
order to enhance brightness uniformity across the LCD tiles.
10. A seamless active tiled LCD device, comprising: a LCD with a
thin front plate, a sealing side wall and a back plate, said LCD
having a LC layer and pixels; a thin sealing cover over the thin
sealing wall of the LCD; and an adhesive array having at least one
spacer between the pixels and between the front and back plates to
enhance thickness uniformity of the LC layer in the LCD.
11. The device of claim 10, wherein said front plate and back plate
comprises a transparent substrate, said substrate including glass
or plastic.
12. The device of claim 10, wherein said front plate and sealing
wall form an integral piece or are two separate pieces.
13. The device of claim 10, wherein said outside sealing cover,
which is an anti-reflective plate, a transparent or diffusing
plate, or having the optical function to change the light
direction, i.e. to change the viewing angle, e.g., micro-lens plate
or holographic plate and the like.
14. The device of claim 10, wherein said LCD is an active LCD, the
active matrix devices are mounted on the interior surface of the
substrate of LCD or mounted on the outside of the substrate of
LCD.
15. The device of claim 10, wherein a series of conductive pins
hidden in the plate to connect the electrodes of LC cells and
outside circuits to guarantee the reliability of the electric
connection.
16. A tiled,.transparent LCD, comprising: a transmissive LCD having
a back plate with a side wall, and a reflective layer on the side
wall of the back plate; and a backlight; said reflective layer
reflecting light emitted from the backlight to reduce the apparent
seam width of the LCD.
17. A tiled reflective LCD, comprising: a transmissive LCD having a
back plate with a side wall, and a reflective layer on the side
wall of the back plate; and a reflector located near the back plate
of the LCD; said reflective layer reflecting light reflected by the
back reflector to reduce the apparent seam width of the tiled
display.
18. A tiled active LCD display system comprising: a display screen
having N by M thin seamless active LCD tiles; each tile having at
least one backlight with a light source and driver and at least one
connector; a driving and control circuit; wherein all tiles are
connected to said circuit through said connector; means for
applying voltage and signals to the driving and control circuit and
tiles to display information and images according to the
signals.
19. A seamless tiled LCD, comprising: a good mechanical strength
backlight, which serves as a base plate of a display screen, said
backlight comprising: (a) at least one light source; (b) a
reflective chamber having a first and a second opposing surface and
housing said light source, said first surface being flat; (c) a
good mechanical strength frame holding said chamber and said
diffusing front plate; at least one transparent spacer located
between the opposing surfaces of said reflective chamber to
maintain the flat shape of said first surface; at least two thin
LCD tiles, said tiles connected to the first surface so that they
are supported by the first surface, said tiles having electrodes;
and at least one set of connectors located between said tiles to
connect the electrodes of adjacent tiles.
20. The device of claim 19, further comprising a diffusing front
plate, the first surface of said chamber being a surface of the
diffusing front plate; and means connecting said diff-using plate
to the thin LCD tiles and to said backlight so that such plate is
between the tiles and the backlight.
21. The device of claim 20, wherein said diffusing front plate
includes a brightness enhancement film.
22. The device of claim 20, wherein said spacer is mounted on said
diffusing front plate with transparent adhesive to obtain a
shadowless backlight.
23. The device of claim 19, further comprising one or more optical
plates adjacent to the tiles, said optical plate having the
function of anti-reflection, diffusing, contrast enhancement or/and
viewing angle changing.
24. The device of claim 23, wherein said front optical plate can be
one piece for one screen or one piece for one tile.
25. The device of claim 19, wherein said at least one light source
comprises at least one hot cathode fluorescent lamp, cold cathode
fluorescent lamp or light emitting diode.
26. The device of claim 19, wherein each of at least some of said
LCD tiles comprises a thin front plate and a thin back plate,
wherein the thicknesses of these plates are in the range of about
0.02 to 5 mm.
27. The device of claim 19, wherein each of said LCD tiles is a
transmissive LCD, reflective LCD or scattering LCD.
28. The device of claim 19, wherein each of at least some of said
LCD tiles has LC cells a spacer mixed adhesive array located
between said the front plate and back plate to keep the LC cells
uniform in the whole tile.
29. The device of claim 19, wherein said LCD tile is an
outside-active-matrix (OAM) LCD, including an active control device
that includes a field effect transistor, bipolar transistor, diode,
or varistor.
30. The device of claim 29, wherein said OAM device is at least one
chip, one chip has at least one active device to control the
related LC cell.
31. The device of claim 19, wherein said seamless tiled LCD is a
color LCD, and a color filter array and a black matrix are
deposited on the inside surface or outside of said thin front plate
or back plate of said LCD tiles.
32. The device of claim 27, wherein said spacer mixed adhesive is
still deposited at OAM mounted area between said thin front plate
and thin back plate to increase the mechanical strength.
33. The device of claim 19, wherein said connector is made of a
transparent substrate and at least one conductive means is
deposited, and used for connecting the electrodes of the tiles
between the adjacent tiles.
34. The device of claim 19, wherein said connectors have auxiliary
electrical connectors, which are connected in parallel with the
related column electrodes, row electrodes and the common electrodes
to reduce the resistance of the electrodes and to increase the
reliability of the connections.
35. A light utilization improved structure comprises: a reflective
'matrix is deposited on the outside surface of the front plate of
the backlight or on the outside surface of said thin back plate,
said reflective matrix can reflect the light, which emitting to
black matrix and could being absorbed by black matrix, to the
backlight reflector to increase the light utilization factor of the
backlight.
36. A seamless tiled LCD, comprising: a good mechanical strength
reflector, which is as a base plate of the display screen, and
comprises of diffusing reflective plate or a mirror and a good
mechanical strength frame. at least two thin LCD tiles, said LCD
tiles are mounted on the outside surface of said diffusing front
plate; at least one set of connector located between said tiles to
connect the electrodes of the adjacent tiles; and means mounting
said thin LCD tiles on a good mechanical strength reflector, to
form a thin profile, light weight and very strong large screen
display.
37. The LCD of claim 36, further comprising a front optical plate,
which has the function of anti-reflection, diffusing, contrast
enhancement or/and viewing angle changing;
38. A sealing method for thin sealing wall LCD sealing, which
comprises a spacer mixed adhesive is deposited at the sealing area,
e.g. by printing, between said thin front plate and thin back
plate, then cured; cutting by laser along the sealing wall; means
using laser cutting to form a very thin sealing wall, because the
thin front plate and thin back plate will be melted during laser
cutting. At the same time, at said cutting area still has sealing
adhesive, different sealing wall can be obtained depending on
sealing adhesive pattern design; the width of sealing wall van be
range of 0.01 to 10 mm.
39. A large screen spacer-shadowless backlight, comprising: at
least one light source; one front diff-using plate and one
transparent back plate; at least one transparent spacer located
between said front diffusing plate and transparent back plate; a
side wall located at the four sides of the front diffusing plate
and the transparent back plate and between said plates; a
reflective layer located at the outside of the back plate and the
side wall to form a reflective chamber; a good mechanical strength
frame; means the front diffusing plate, the transparent back plate,
spacer, side wall, reflective layer and mechanical frame forming a
large screen spacer-shadowless good mechanical strength
backlight.
40. The device of claim 39, wherein said light source is HCFL, CCFL
or LED.
41. The device of claim 39, wherein said front diffusing plate and
transparent back plate have the same or similar coefficient of
thermal expansion.
42. The device of claim 39, wherein said front diffusing plate and
transparent back plate can be one piece plate or combined of two or
more pieces plates.
43. The device of claim 39, wherein said spacer is a cone shape
spacer or other shape spacer, and fixed on the inside surface of
the front diffusing plate by transparent adhesive.
44. The device of claim 39, wherein a diagonal dimension of the
backlight is not less than 20 inches.
45. A tiled LCD, comprising: a large screen spacer-shadowless
backlight; at least two thin LCD tiles; means mounting the tiles on
the outside surface of the front diffusing plate of said backlight
to form a tiled LCD.
46. The device of claim 45, wherein a diagonal dimension of the
backlight is not less than 20 inches.
47. The device of claim 45, wherein a series of conductors are
deposited on the outside of the front diffusing plate of said
backlight, used for connecting tiles and connecting tiles to the
driving electronics of the display system.
48. A sealing method for plastic LCD sealing, which comprises a
front plastic plate and a back plastic plate, which with electrodes
and other LCD parts, and aligned each other and fixed; cutting by
laser along the sealing area; means using laser cutting to form a
thin sealing wall at sealing area, because the front plate and back
plate will be melted during laser cutting at sealing area, and a
thin sealing wall will be formed. The width of the sealing wall can
be range of 0.01 to 10 mm.
49. A riveted plastic LCD, which comprises a front plastic plate
and a back plastic plate, which with electrodes and other LCD
parts, and aligned each other and fixed; at least one rivet made by
laser beam to melt said front plate and said back plate to form the
rivet; means making at least one rivet, riveting said front plate
and said back plate to form a robust plastic LCD.
50. The device of claim 49, wherein said LCD can be a transmissive
LCD, reflective LCD or scattering LCD.
51. The device of claim 49, wherein said rivet is a through hole
drilling by laser beam, and along the hole has a thin sealing wall
formed by the melted plastic, and formed the rivet.
52. The device of claim 49, wherein said back plastic plate is
thinner than said front plastic plate. The laser drilling is
started from the back plate using a small diameter laser beam. The
laser beam do not make a through hole, the drilling is stopped at
both of front plate and back plate are melted and attached
together, and to form the rivet. This structure and process can be
used for making the high resolution plastic LCD, and can be used
for making mosaic LCD and single piece LCD.
53. The device of claim 49, wherein said back plastic plate and
said back plate are a plastic film, e.g. polyester, polycarbinate
or other plastic film.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
Provisional Application Ser. No. 60/077,675 filed on Mar. 12, 1998
and U.S. Provisional Application Ser. No. 60/081,085, filed on Apr.
8, 1998.
BACKGROUND OF THE INVENTION
[0002] This invention relates in general to a seamless tiled
display and, in particular, to seamless tiled active liquid crystal
display (LCD).
[0003] Tiled displays have been used frequently in
super-large-screen displays for indoor and outdoor applications to
display character and full-color image, such as sports stadiums,
exhibition halls etc. Several types of tiled full color
super-large-screen displays have been used or proposed. One type
known as tiled flat CRT, such as Jumbotron, is a kind of flat
matrix CRT which has a hot filament cathode, mesh grid and anode.
The anode voltage is about 8 kv, and one display tile includes
about 20 color pixels. This kind of display has a good color
quality image, but a short lifetime and a high anode voltage.
[0004] Another conventional tiled display system currently used is
known as a light emitting diode (LED) tiled display. One pixel
includes several red, green and blue (R, G, B) LED lamps or chips.
It can display a good quality fill color image and high brightness,
and can be used in both indoor or outdoor applications. But this
kind of tiled display is very expensive especially for a
super-large-screen display, because it must employ a large number
of small individual LEDs that have diameters of about 5 mm.
[0005] Another conventional tiled display system is a tiled liquid
crystal display (LCD) as described in U.S. Pat. No. 5,557,436. In
this kind of display, a passive LCD and a hot cathode fluorescent
lamp (HCFL) back-light are used. The color quality, contrast and
brightness are not quite satisfactory. Therefore, at present, this
kind of display is only used for displaying characters. On the
other hand, the seam width of this tiled display is normally quite
large. This is caused by the use of a wide sealing wall, a thick
front plate and thick back plate. This kind of display cannot be
used for a high resolution tiled display.
SUMMARY OF THE INVENTION
[0006] This invention is based on active LCD and backlight to make
a seamless tiled display. The problems described above with
conventional tiled displays are alleviated or avoided
altogether.
[0007] This invention reduces the visually apparent seam width of
the tiled display. For this purpose, a thin glass or plastic front
plate of LCD is used. The thickness of the front plate is
preferably in the range of about 0.02 to 0.7 mm.
[0008] To reduce the visually apparent seam width of the tiled
display, a reflective layer is employed on the side wall of the
back plate to reflect the light emitted from the backlight.
Therefore, the apparent seam width can be reduced.
[0009] As explained above, conventional LCD devices employ thick
front and back plates because of the requirement that the device be
mechanically sturdy. By using a back light or reflector with
adequate mechanical strength and connecting LCD tiles to the back
light or reflector to lend mechanical strength to the tiles, it is
possible to use thin front and back plates in the LCD tiles,
thereby reducing or eliminating apparent seam widths and so that
the tiled display appears to be seamless.
[0010] A plastic LCD device may be conveniently made by aligning LC
cells between two sheets of plastic and using a laser to cut the
two sheets into smaller pieces by melting the plastic in the two
sheets along the lines that are cut. The melting of the plastic at
the edges of the smaller pieces causes the front and back portions
of the pieces to bond and form a sealing wall. Where a sturdier
sealing wall is desired, an adhesive material may be applied
between the two sheets along the lines of cutting by the laser to
bond the two sheets prior to the cutting process. Therefore, the
heat of the laser will melt the plastic material of the two sheets
as well as the adhesive material to form a sturdy sealing wall for
the LCD devices formed.
[0011] To further enhance the mechanical strength of the plastic
LCD's, rivets may be formed connecting the front and back plastic
plates by applying a drilling laser to the device. The laser may be
applied to form one or more holes in the device by melting the
front and back sheets at selected spots and the melted plastic of
the two sheets are bonded together to form a rivet. Alternatively,
for high resolution displays, the rivets are formed without forming
visible holes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1a shows a side cross-sectional view of a conventional
display with the apparent tiled seam width K of two adjacent tiled
displays.
[0013] FIG. 1b shows a top view of FIG. 1a.
[0014] FIG. 2 shows a prior art thin seam tiled display.
[0015] FIG. 3a shows a top view of an embodiment of the seamless
tiled display of the present invention.
[0016] FIG. 3b shows a side cross-sectional view of the display of
FIG. 3a along line 3b-3b in FIG. 3a.
[0017] FIG. 4 shows the effect of the back plate thickness to the
seam width of the tiled display.
[0018] FIG. 5 shows a side cross-sectional view of a seamless tiled
display of the present invention employing a reflective layer on
the side wall to illustrate another embodiment of the present
invention.
[0019] FIG. 6a shows a top view of a seamless tiled display of the
present invention employing a reflective layer on the side wall to
illustrate yet another embodiment of the present invention.
[0020] FIG. 6b shows a side cross-sectional view of the display of
FIG. 6a along line 6b-6b in FIG. 6a.
[0021] FIG. 7 shows a tiled active LCD display system, which has
N.times.M tiles.
[0022] FIG. 8a shows the cross-sectional view of the portion of one
more embodiment of seamless tiled LCD display of the invention.
[0023] FIG. 8b is the front view of the portion of FIG. 8a. FIG. 8a
shows the cross-sectional view of the portion of FIG. 8b along the
line 8a-8a in FIG. 8b.
[0024] FIG. 9 shows the cross-section view of the portion of
another embodiment of seamless tiled LCD of the invention where
multiple tiles share a backlight.
[0025] FIG. 10 shows a side cross-sectional view of an another
embodiment of the seamless tiled display of the present
invention.
[0026] FIG. 11a shows atop view of an embodiment of the laser
sealed and riveted plastic LCD of the present invention.
[0027] FIG. 11b shows a cross-sectional view of the display of FIG.
11a along the line 11b-11b in FIG. 11a.
[0028] FIG. 12 shows the cross-sectional view of the portion of
another embodiment of laser sealed and riveted plastic LCD of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] Each tile in a tiled display contains a number of pixels,
where the adjacent pixels are separated by an inter-pixel spacing.
In order to obtain a seamless tiled display, the actual apparent
inter-pixel spacing between two adjacent tiles is preferably the
same as the inter-pixel spacing within the display tile. That is
the apparent seam width between two adjacent tiles is substantially
the same as the inter-pixel spacing within the display tile so that
a seamless image can be obtained.
[0030] The seam width may be reduced by using a thin front plate.
By using a thin front plate, the apparent seam width is reduced. An
active matrix LCD may also be used. The active matrix elements of
active LCD may be mounted on the interior surface of the substrate
of LCD, or more preferably mounted on the outside of the substrate
as described in U.S. Pat. No. 5,510,915 named outside-active matrix
LCD (OAM-LCD). The active matrix element acts as a switch to
control the electrical signal applied to a given LC cell and to
eliminate the cross-talk between the LC cells, so that good quality
and good contrast images can be obtained.
[0031] In order to improve the uniformity of the LC cells
thickness, it is preferable to employ an adhesive array has one or
more spacers deposited among pixels and between front plate and
back plate of the LCD. The sealing wall and the front plate can be
one piece or separated. The former can be made of plastic and
latter can be made of the same material or different materials; for
example, the front plate is made of glass or plastic, and the
sealing wall is made of plastic.
[0032] The active matrix elements of an active LCD may be mounted
on the interior surface of the substrate of LCD, or more preferably
mounted on the outside of the substrate as described in U.S. Pat.
No. 5,510,915 named outside-active matrix LCD (OAM-LCD). The active
matrix element acts as a switch to control the electrical signal
applied to a given LC cell and to eliminate the cross-talk between
the LC cells, so that good quality and good contrast images can be
obtained.
[0033] In the case of OAM-LCD tiled display, the active matrix
elements are mounted on the outside of the front plate or back
plate. The electrodes of the active elements are connected to the
electrodes of the LC cell through the conductive pin hidden in the
front plate or the back plate. On the other hand, the electrodes of
the active elements are connected to the display system electronics
through the conductive connectors. These connectors are deposited
on the sealing wall, the outside surface of the front plate or the
back plate. Therefore, the LCD can modulate the light emitted from
the backlight and to display a image.
[0034] Due to reduced front plate thickness, sealing wall thickness
and depositing a reflective layer on the side wall of the back
plate, a seamless tiled display can be made having high
resolution.
[0035] The invention teaches a full-color tiled display using at
least a set of red, green and blue (R, G, B) cold cathode
fluorescent lamp (CCF) or light emitting diode (LED) backlight. The
R, G, B CCF or LED can be operated in a color sequential mode
according to the display signal from the display system
electronics. The LCD is also operated according to display signal.
The image signal is divided into three sub-field, R, G, B
sub-field, when LCD displays red image, the red CCF or LED is
lighted, then LCD displays green image, the green CCF or LED is
lighted, then blue. Therefore a full-color image can be displayed.
In this case, the filter is needless and the brightness of the
image will be higher.
[0036] To increase the resolution of the tiled display and to get a
kind of high resolution tiled LCD, the high resolution tiled LCD
comprises of a large screen spacer-shadowless backlight and some
tiles. The tiles are mounted on the front diffusing plate of the
backlight to form a high resolution tiled LCD.
[0037] A laser sealing method may be used for making a plastic LCD.
Using the laser to cut the plastic LCD along the sealing area,
because the front and back plates of the plastic LCD will be melted
during laser cutting, a thin sealing wall will be formed. The laser
sealing method can be used for LCD tile and single piece LCD
sealing. A good robustness riveted plastic LCD comprises a thin
front plastic plate and a thin back plate. In the LCD, there are
some rivets riveting said two plates by laser beam. The riveting
method can be used for plastic LCD tile and single piece plastic
LCD, to get a very robust LCD and large screen plastic LCD.
[0038] FIG. 1a shows a side cross-sectional view of a prior art LCD
display illustrating the concept of the apparent seam width K of
two adjacent tiled displays.
[0039] FIG. 1b shows a top view of the display in FIG. 1a.
[0040] Adjacent LCD display tiles 101 and 102 are shown in FIGS.
1a, 1b, with gap 103 between the two adjacent display tiles. Each
tile has a front plate 104, back plate 105, column electrode 106,
row electrode 107 and sealing wall 108. 109 is a side circuit
plate, which has conductive connector 110. The connector 110
connects the electrodes 106 and 107 to the driving circuit of the
display system. 111 is a LC layer. 112 is a black matrix. The width
M of the black matrix is the inter-pixel spacing within the display
tile.
[0041] The apparent seam width K between two adjacent display tiles
depends on the following factors:
[0042] the gap width H between two display tiles;
[0043] the sealing wall width W of the display tile;
[0044] the thickness C of the side circuit plate of the display
tile;
[0045] the thickness T.sub.F of the front plate of the display
tile, because the light ray 113 from the pixel 114 proceeding to
the side wall 109 will be obstructed by the side wall;
[0046] the thickness TB of the back plate of the display tile,
because the light ray 116 from a backlight or a back reflector
proceeding towards the side wall 109 will be obstructed by the side
wall;
[0047] the non-uniformity of the luminance and the color near the
tiled seam area. If the luminance or color is non-uniform near the
tiled seam, e.g., the luminance of the area 115 is lower than the
area 114 or the color is different, the apparent seam width K will
be larger.
[0048] The actual apparent tiled seam width K is the sum of factors
mentioned above.
[0049] For a seamless tiled display, the luminance and the color
should be uniform in the whole active display area, and the
apparent tiled seam width K should be the same as the inter-pixel
spacing M within the display tile.
[0050] FIG. 2 shows a prior art thin seam passive tiled LCD (e.g.,
U.S. Pat. No. 5,557,436), which has a thin sealing wall 208 and
thin side tape 209. 204 and 205 are the front plate and back plate.
206 and 207 are row and column electrodes of the display. 210 is
the conductive connector located on the side tape 209. The
conductive connector 210 connects the electrodes 206 and 207 to the
driving circuit (not shown) of the display system. 211 is a LC
layer operated at passive mode. 217 are polarizers.
[0051] In the conventional tiled LCD, thick front and back plates
are used to assure that the LC layer 211 has uniform thickness, so
that the LCD displays a uniform image. The thick front and back
plates make the apparent tiled seam width K larger.
[0052] On the other hand, in the conventional tiled LCD, the row
and the column electrodes of the display are extended from the
front and back plate interior surfaces to the side surfaces of the
plates through the rectangle edges 216 of the plates. In this case,
the electric connection can easily become broken at or near the
edges, resulting in an open circuit, which means the reliability of
this structure is usually rather poor.
[0053] In the conventional tiled LCD, a passive LCD is used. In
this case, the contrast and image quality are usually less than
satisfactory, because of the cross-talk between LC cells. In
addition, in the conventional tiled LCD, a hot cathode fluorescent
lamp back-light (HCFL-BL) is used for tiled LCD. Hence the
brightness of the display may be inadequate for some applications
and the life-time of the display is short.
[0054] FIG. 3a shows a top view of a portion of an embodiment of a
seamless tiled outside-active-matrix LCD (OAM-LCD) of the
invention, and FIG. 3b is a cross-sectional view of the LCD of FIG.
3a along the line 3b-3b in FIG. 3a. In FIG. 3a and FIG. 3b, 304 is
a thin front plate, and 305 is the back plate. 304 and 305 are
transparent substrate, e.g., glass or plastic. 308 is a thin
sealing wall, which can be one integral piece with the front plate
304 or a separate piece. 306 is a separated electrode array of LCD,
and 307 is a common electrode of LCD. Electrodes 306 and 307 define
a matrix LCD. 311 is a LC layer. 318 is an adhesive array having at
least one spacer but preferably a plurality of spacers 319
deposited among pixels and between front plate 304 and back plate
305. This adhesive array can guarantee the uniformity of the LC
cell's thickness to get a uniform display image.
[0055] 320 is a series of conductive pins hidden in the front plate
304. One terminal of the pin 320 is connected to the separated
electrode 306, the other terminal of the pin 320 is connected to
the source electrode (S) of the outside active matrix device 321,
which may for example be a field effect transistor (FET), and which
is preferably mounted on the outside surface of the front plate
304. Instead of a FET, the outside active matrix control device 321
may also be a diode, bipolar transistor, switch, or varistor etc.
As shown in FIG. 3a, one outside active device 321 controls one LC
cell, i.e. one color dot. But these active devices can also be
integrated into an integrated circuit chip, i.e. one chip controls
one group of LC cells. 322 is another conductive pin hidden in the
front plate 304, one terminal of the pin being connected to the
common electrode 307 through a conductive means 323, i.e., silver
(Ag) paste, and the other terminal of the pin 322 being connected
to the conductive connector 324 and then connected to the system
driving circuit (not shown) through the printed circuit board (PCB)
329. 325 is a series of another conductive pin hidden in the front
plate 304, one terminal of the pin 325 is connected to the row
scanning electrode 326, and the other terminal of the pin 325 is
connected to the gate electrode (G) of the outside active matrix
device 321. The, row scanning electrode 326 is connected to the PCB
329 through conductive connector 339, then connected to the system
driving circuit (not shown) through the connector 330'. 327 is a
column signal electrode, one terminal of the electrode 327 being
connected to the drain electrode (D) of the outside active matrix
device 321, and the other terminal to the PCB 329 through connector
328, then to the system driving circuit (not shown).
[0056] 317 are two polarizers, one is located at the outside
surface of the front plate 304, and other one is located at the
outside surface of the back plate 305. 330 are color filters,
deposited on the outside surface of the front polarizer 317. For a
monochrome or black/white display, this filter may be omitted. 331
is a black matrix.
[0057] 332 is an outside sealing cover, which is an anti-reflective
plate, a transparent or diffusing plate, or having the optical
function to change the light direction to alter the viewing angle,
e.g., micro-lens plate or holographic plate and the like. This
cover may cover only one tile, or two or more tiles up to the
entire screen of the display. If this cover does not cover the
entire screen, more than one cover may be employed to cover all the
tiles of the screen.
[0058] 333 is a reflective layer deposited on the side wall of the
back plate 305, the operating principle of which is illustrated
below in reference to FIG. 5.
[0059] 334 is a back-light, which has at least one CCF, HCFL or LED
335 as its light source. 336 is a driver for CCF, HCFL or LED 335.
The driver 336 has a brightness adjustment circuit to adjust the
brightness of the backlight by manual or a sensor to automatically
adjust the brightness in order to guarantee the brightness
uniformity in the whole tiled screen. To adjust the brightness
manually, one may adjust a potentiometer in the circuit, for
example. To adjust the brightness automatically, a photodiode in
the circuit may be used to provide feedback signal so as to adjust
the brightness, for example. 337 is a reflective chamber of the
backlight 334. 338 is a diff-user and a brightness enhancement film
(BEF) of the backlight 334.
[0060] In this embodiment, thin front plate, thin sealing wall and
back plate side wall reflector are used, so the apparent seam width
can be very small, therefore, the high resolution seamless tiled
display can be made. For example, the thickness of front plate 304,
T.sub.F, may be in a range of about 0.02 to 0.7 mm, and the
thickness of back plate 305, T.sub.B, may be in a range of about
0.02 to 4 mm. With the front and back plates of such thicknesses,
the apparent seam width is much reduced compared to the
conventional displays.
[0061] FIG. 4 shows a cross-sectional view of a tiled display,
which shows the effect of a thick back plate on the apparent seam
width of the tiled display. 401 and 402 are two adjacent tiled
LCDs. 404 and 405 are the front plate and back plate. 406 is the
separated electrode (similar to 306 in FIG. 3) and 407 is the
common electrode. 411 is a LC layer, and 417 are the polarizers.
434 is a backlight.
[0062] In FIG. 4, "A" shows a location which is far from the
sealing wall 408. In this area, the light rays in all directions,
440, 441 and 442, can go through the display, however, at or near
the sealing wall area B, the light beams in the directions 443 and
444 can go through the display, but the light beam 445 will be
obstructed by the sealing wall 408. 434 may be a backlight in a
transmissive LCD or a light reflector in a reflective LCD. The
light beam 446 emitted from backlight 434 (for transmissive LCD) or
reflected by reflector 434 (for reflective LCD), (equivalent to
beam 445 from the area B), will be also obstructed by the sealing
wall 408. Therefore, the apparent seam width will be wider. The
thicker the back plate T.sub.B, the bigger the apparent seam
width.
[0063] In order to eliminate or reduce the effect of the thick back
plate on the apparent seam width, a reflective layer can be
deposited on the side wall of the back plate. FIG. 5 shows the
reflective layer 533, which is deposited on the side wall of the
back plate 505;,which can reflect the light beams 545 and 546 to
illuminate the LC cell. The light beams 545 and 546 are similar to
547 and 548, which are emitted from backlight 534 for a
transmissive LCD or reflector 534 for a reflective LCD. In other
words, where 534 is a backlight, device 500 is a transmissive LCD;
where 534 is a reflector, device 500 is a reflective LCD.
Therefore, the effect of the back plate thickness on the seam width
can be eliminated or reduced, and a high resolution seamless tiled
display can be obtained.
[0064] FIG. 6a shows a top view of the portion of another
embodiment of a seamless tiled OAM-LCD of the invention, and FIG.
6b is the cross-section view of the LCD of FIG. 6a along line 6b-6b
in FIG. 6a. In this embodiment, a thin front plate and the R, G, B
CCF or LED backlight are used. This display can be operated at
color sequential mode to get the full-color image without using
color filters. In FIG. 6a and FIG. 6b, 604 is a thin front plate,
and 605 is a back plate. The plates 604 and 605 are transparent
substrate, e.g., glass or plastic. 608 is a thin sealing cover, and
made of plastic. 606 is a separated electrode array of LCD, and 607
is the common electrode of LCD. Electrodes 606 and 607 define a
matrix LCD. 675 is a LC layer. 618 is an adhesive array which has
spacer 619 deposited between pixels and between front plate 604 and
back plate 605. This adhesive array can guarantee the uniformity of
the LC cells thickness to get a uniform display image.
[0065] 620 is a series of conductive pins hidden in the front plate
604, one terminal of the pin 620 is connected to the separated
electrode 606, the other terminal of the pin 620 is connected to
the source electrode (S) of the outside active matrix device 621,
e.g. FET, which is mounted on the outside surface of the front
plate 604. As the outside active matrix device, diode, switch,
varistor etc. can also be used. As shown in FIG. 6, one outside
active device control one LC cell, i.e. one color dot. But these
active devices can also be integrated into the chip, i.e. one chip
controls one group of LC cells. 622 is another conductive pin
hidden in the front plate 604, one terminal of the pin 622 is
connected to the common electrode 607 through a conductive means
623, i.e., Ag paste, and the other terminal of the pin 622 is
connected to the conductive connector 624 (which bends down at
sealing wall 608 to reach PCB 629) and then connected to the system
driving circuit through the PCB 629. 625 is a series of another
conductive pin hidden in the front plate 604, one terminal of the
pin 625 is connected to the row scanning electrode 626, and the
other terminal of the pin 625 is connected to the gate electrode
(G) of the outside active matrix device 621. The row scanning
electrode 626 is connected to the PCB 629 through conductive
connector 639, then connected to the system driving circuit through
the connector 630. 627 is a column signal electrode, one terminal
of the electrode 627 is connected to the drain electrode (D) of the
outside active matrix device 621, and the other terminal is
connected to the PCB 629 through connector 628, then to the system
driving circuit (not shown) through connector 630.
[0066] 617 are two polarizers, one is located at the outside
surface of the sealing cover 608, and an other is located at the
outside surface of the back plate 605. 631 is a black matrix.
[0067] 632 is an outside sealing cover, which is an anti-reflective
plate, a transparent or diffusing plate, or having the optical
function to change the light direction to change the viewing angle,
e.g., micro-lens plate or holographic plate and the like. 633 is a
reflective layer deposited on the side wall of the back plate
605.
[0068] 634 is a backlight, which has at least one set of R, G, B
light sources, such as HCFLs, CCFLs or LEDs 635. 636 is a driver
for HCFLs, CCFLs or LEDs 635. 637 is a reflective chamber of the
backlight 634. 638 is a diffuser and a brightness enhancement film
(BEF) of the backlight 634.
[0069] The R, G, B HCFLs, CCFLs or LEDs 635 can be operated in a
color sequential mode according to the display signal from the
display system electronics. At the same time, the LCD is also
operated according to display signals. The image signal is divided
into three sub-field, i.e. R, G, B sub-field. When LCD displays red
image, the red CCF or LED is lighted; then LCD displays green
image, the green CCF or LED is lighted; and then blue. Therefore a
full-color image can be displayed. In this case, color filter need
not be used so that the brightness of the image will not be reduced
by the filters and will be higher than otherwise.
[0070] FIG. 7 shows a tiled active LCD display system, which has N
by M tiles 701, where N, M are positive integers, Each tile has a
backlight with HCFLs, CCFLs or LEDs (not shown) and a driver 736
(performing the same function as driver 636 of FIG. 6) for driving
the backlight, and a connector 730 similar to connectors 330, 630
of FIGS. 3b and 6b. 750 is a control and driving circuit of the
system. 749 is a cable connecting each tile to circuit 750 through
connectors 730. Thus, the system driver circuit 750 controls the
driver circuits 736 which in turn drives the backlight of the tiles
701. Circuit 750 also controls the voltages applied to the common
electrode (not shown in FIG. 7) which are similar to the common
electrodes 307 and 607 in FIGS. 3a, 3b, 6a, 6b, and the separated
electrode array (not shown in FIG. 7) similar to arrays 306 and 606
in FIGS. 3a, 3b, 6a, 6b. Circuit 750 is connected to the common
electrode and separated electrode array through connector 730 of
each tile, where connector 730 serves the same function as
connectors 330, 630 of FIGS. 3a, 3b, 6a, 6b. In this manner,
circuit 750 controls the sequential addressing of the entire
display comprising N.times.M tiles. As shown in FIG. 7, the
connector 730 of each tile are connected to circuit 750 by means of
cable 749. The drivers 736 of all the tiles are connected to the
circuit 750. In the particular design illustrated in FIG. 7, each
tile has its own backlight and backlight and backlight driver,
which is controlled by circuit 750 so that the N.times.M tiles act
as one display.
[0071] FIG. 8a shows the cross-sectional view of a portion of
another embodiment of seamless tiled LCD of the invention; and FIG.
8b is the front view of FIG. 8a. In this embodiment, the LCD tiles
have thin front plate 804 and thin back plate 805, and are mounted
on a backlight or reflector 834 with good mechanical strength so
that the LCD in the tiles will have uniform thickness. The
backlight or reflector 834 is used as a base plate of the display
screen, and can be made a very light weight, thin profile, very
strong large screen and super-large screen display. The tiled
display is like a single piece display. In other'words, by relying
on the backlight for strength to maintain the LCD at a uniform
thickness, it is possible to reduce the thicknesses of both the
front and back plates to reduce apparent seam width.
[0072] In FIGS. 8a and 8b, 801a, 801b, 801c and 801d are the
portions of four adjacent LCD tiles. The LCD tile can be a
transmissive LCD, reflective LCD, scattering LCD or
outside-active-matrix LCD (OAM-LCD).
[0073] In FIGS. 8a, 834 is a backlight or reflector device with
good mechanical strength. For a transmissive tiled LCD, 1034 is a
backlight, which has at least one light source 835, e.g. hot
cathode fluorescent lamp (HCFL), cold cathode fluorescent lamp
(CCF) or LED. 852 is a good mechanical strength frame, which is
made of metal or plastic, e.g. aluminum alloy and steel. 853 is a
reflective chamber, which has high reflective walls 854, and the
front face of the reflective chamber 853 is a diffusing plate 838
to make the brightness of the backlight very uniform. In order to
increase the brightness of the backlight, the diffusing plate 838
can also have a brightness enhancement function, e.g. with a
brightness enhancement film. 855 is a spacer of the backlight,
which is located between the front diffusing plate 838 and the
bottom surface of the reflective chamber 853, so that the good
mechanical strength of the frame 852 lends support also to the
diffusing plate 838 through the spacer 855, thereby enabling the
diffusing plate to have a very flat surface.
[0074] The spacers 855 can be a transparent round pole, cone shape
or other shape, which is made of a transparent material, e.g.
plastic or glass. The top of the spacers 855 are polished, mounted
and attached on the diff-using plate 838 by transparent adhesive
856. The other end of the spacers 855 are fixed on the frame 852 by
screw(s) 857. The frame 852, reflective chamber 853, front
diffusing plate 838 and spacer 855 formed a very bright backlight
with good mechanical strength.
[0075] FIGS. 8a and 8b show an embodiment of a seamless tiled
OAM-LCD of the invention. 801a, 801b, 801c and 801d are the
portions of four adjacent OAM-LCD tiles. The tiles are mounted on
the diffusing plate 838 by adhesive 858. 803 are gaps between the
adjacent LCD tiles. Gaps 803 between tiles may be filled by
adhesive 858. The thin front plate 804 and thin back plate 805 are
made of glass or plastic, and their thicknesses range from 0.01 to
4 mm, to reduce obstruction of light from the backlight and the
apparent seam width. 830 and 812 are respectively the filter and
the black matrix, which can be deposited on the inside surface or
outside of the thin front plate 804 or back plate 805. 811 is a LC
layer, including transmissive LC, e.g. TN, STN, and scattering LC,
e.g. polymer dispersed LC (PD-LC). 817a and 817b are two
polarizers, one of which is located at the outside of the thin
front plate 804, and the other is located at the front surface of
the diffusing plate 838, or at the outside of the back plate 805 of
the LCD tile. The polarizers can be one sheet per display screen or
one sheet per tile. In the case of scattering LC, the polarizers
may be omitted. 808 is a sealing wall, which has spacer 819. 806 is
a separated electrode array of LCD, and 807 is a common electrode
of LCD. One separated electrode and the common electrode defined
one LC cell. Each separated electrode 806 has one corresponding
color filter 830 for color display.
[0076] In order to increase the viewing angle and contrast of the
display image, an optical front plate 859 is located at the front
of the tiled screen. The optical front plate has some optical
function, e.g. diffusing, anti-reflection, viewing angle changing
etc. to increase viewing angle, contrast, and brightness.
[0077] The black matrices 812 may absorb a significant portion of
the light originating from the backlight. In order to increase the
light utilization of the backlight despite the black matrices,
reflective matrices 860 are deposited at the outside surface of the
back polarizer 817a or the outside of the front diffusing plate
838. Each of the reflective matrices is aligned with a
corresponding black matrix 812, and reflects back towards the
chamber 853 the light which is emitted by the backlight and which
otherwise would be directed towards and be absorbed by the
corresponding black matrix. This increases the light utilization of
the backlight.
[0078] Each LCD tile has at least one row electrode 826, which is
deposited on the inside surface of the front plate 804, and at
least one column signal electrode 827, which is deposited on the
outside surface of the front plate 804. 861 is an
out-side-active-matrix (OAM) chip, which has at least one active
device of OAM-LCD and is mounted on the outside surface of the
front plate 804. In the case of FIG. 8a, the chip 861 has 12 active
devices (e.g. FETs) to control four pixel (each pixel having 3 LC
cells for red, green and blue light for a total of 12 LC cells).
For example, one chip 861 has 12 FETs, and each set of 6 FETs have
one common gate electrode. Two row electrodes 826 for row m and row
(m+1), m ranging from 0 to 511, for example, are connected through
pins (not shown) to two gate electrodes of FETs respectively; and 6
column signal electrodes 827 are connected to the D (drain)
electrodes of FETs respectively. Twelve S electrodes of FETs are
connected to twelve separated electrodes 806 through the conductive
pins 820, which are hidden in the front plate 804. When one row,
e.g. row m, is applied a row scanning voltage, all the FETs
connected with this row are turned on. The video display signal
will be applied to the related D electrodes of FETs through related
column electrodes 827 and related FETs, and apply to the related LC
cells 811 to change the transmittance of the LC cells, and to
display the image. Once an LC cell is turned on, its transmittance
remains unchanged until it is again addressed, so that a full color
display results from the sequential addressing.
[0079] Between the LCD tiles, the column electrodes 827 are
connected by a connector 862, made of a transparent means, e.g.
transparent film, with some electrically conductive leads 863
deposited, which connect the related column electrodes between the
adjacent LCD tiles through the electrically conductive connection
pads 864. Between the LCD tiles, the row electrodes 826 are
connected by a connector 865, which is made of a transparent means,
e.g. transparent film with some electrically conductive leads 866
deposited. The connector connects the related row electrodes
between the adjacent LCD tiles through the electrically conductive
pins 825, which are hidden in the front plate 804. One LCD tile has
one common electrode 807. The connector 867 is made of a
transparent means, e.g. transparent film, and the conductive lead
868 is deposited, which is used for connecting the common
electrodes 807 of the adjacent LCD tiles through conductive pins
869 and conductive material 870, e.g. silver paste.
[0080] In other words, each OAM chip includes 12 FETs, one for
controlling each of 12 LC cells. In reference to FIG. 8b, for
example, chip 861 would control the three LC cells in each of the
four pixels immediately adjacent to the chip. Chip 861 would
receive addressing signals from an outside controller (not shown)
through two row electrodes 826: rows m and m+1. The addressing
signal in row m would control the addressing of the pixels
immediately above it and the addressing signals in row m+1 would
control the addressing of the pixels immediately below the row as
shown in FIG. 8b. When the addressing signal to row m is asserted,
this causes the six FETs addressing the two pixels immediately
above row m and adjacent to chip 861 to be turned on. Each of the
six LC cells in the two pixels immediately above row m is
controlled by a corresponding column signal electrode 827.
Therefore, the brightness of the display in each pixel is
controlled by three corresponding column signal electrodes 827. The
video signals on the, corresponding column signal electrode 827
would then be applied to the drain electrode of the FET
corresponding to each of the six LC cells to control the brightness
of the image displayed by such cell. As shown in FIG. 8b, two
column electrodes 827 is shown to overlap the connector 862 on the
left portion of the figure and are connected to the chip 861
through lines 827' and four column signal electrodes are shown to
overlap the connector 862 on the right-hand portion of the figure.
Of such six column signal electrodes, three are used for
controlling the brightness of the pixel in between the two adjacent
connectors 862. Row electrodes 826 and column electrodes 827 are
then connected to the system driver-circuit (not shown) for
controlling the addressing of the LC cells.
[0081] In order to reduce the resistance of the row electrodes,
column electrodes and the common electrodes, and also to increase
the connector reliability, the auxiliary electrodes 871 can be
used, which can be deposited on the outside of the front plate 804
or on the connectors 862, 865 and 868. If the auxiliary electrodes
871 are located on the connectors 862, 865 and 868, said connectors
should be the prolong tapes, e.g. shown as 868, and the auxiliary
electrodes are in parallel with the related electrodes.
[0082] FIG. 9 shows the cross-section view of the portion of anther
embodiment of a high resolution seamless tiled LCD of the
invention. In this embodiment, the LCD comprises of thin LCD tiles
901 and backlight 934. 901a and 901b are the adjacent LCD tiles.
The LCD tile can be a transmissive LCD, scattering LCD or
OAM-LCD.
[0083] In FIG. 9, 934 is a backlight which with good mechanical
strength. In the backlight 934, there are at least one light source
935, e.g., HCFL, CCF or LED. 952 is a good mechanical strength
frame, which is made of metal or plastic, e.g., alloy and steel.
953 is a reflective chamber, which has high reflective walls 945.
The front face of the reflective chamber 953 is a diffusing plate
938, which makes the brightness of the backlight very uniform. 972
is a transparent back plate of the backlight 934, which is used for
eliminating the spacer shadow and to improve the brightness
uniformity of the backlight. The coefficient of thermal expansion
of the transparent back plate 972 is matched with (that is,
substantially the same as) front diffusing plate 938 to assure that
the backlight does not bend at different operating temperatures and
its mechanical strength is maintained over a wide range of
operating temperatures. 955 is the transparent spacer of the
backlight, which is located between the front diffusing plate 938
and the transparent back plate 972. 973 is the side wall of the
backlight 934. The fame 952, front diffusing plate 938, transparent
back plate 972, spacers 955 and side wall 972 forms a backlight
with good mechanical strength.
[0084] The diffusing plate 938 can be a thick diffusing plate or
comprises of a transparent plate 938a and one side or both sides
diffusing layers 938b. In order to increase the brightness of the
backlight, the diffusing plate 938 can also have a brightness
enhancement function, e.g. with a brightness enhancement film.
[0085] The spacer 955 can be a transparent cone spacer or other
shape spacer, which is made of a transparent material, e.g. plastic
or glass. The top of the spacers 955 are polished, mounted and
attached on the diffusing plate 938 by adhesive 956.
[0086] FIG. 9 shows an embodiment of a seamless OAM-LCD tiled LCD.
901a and 901b are two adjacent OAM-LCD tiles, which have thin front
plate 904 and thin back plate 905, and are mounted on the diffusing
plate 938 of the backlight 934 by adhesive, e.g. anisotropic
adhesive. The thin front plate 904 and thin back plate 905 are made
of glass or plastic, and their thicknesses range from 0.01 to 8 mm,
to reduce obstruction of light from the backlight and the apparent
seam width. The front and back plates can be very thin since they
rely on the backlight for support so that they remain flat and
uniform. 911 is LC cell, which with electrodes, filter, black
matrix, alignment layer and LC layer. 908 is the sealing wall of
LCD. 917 are the polarizers. 903 are the gaps between the adjacent
LCD tiles. Adhesive 958 may fill gaps 903. The details of the gap
and the LCD tile structure are shown in FIG. 10 which is an
exploded view of a portion of the device in FIG. 9. The backlight
can be made in any dimensions. A large backlight of the
construction described herein can have a diagonal dimension of not
less than 20 inches.
[0087] In FIG. 9, 961 are the OAM chips, which are mounted on the
tile 901 by adhesive 956, e.g. anisotropic adhesive or wire bonding
and adhesive. The chips 961 are connected to the row and column
electrode driving electronics 974 through the hidden conductors 920
and conductors 975, which are deposited on the surface of the
diffusing plate 938 of the backlight 934. 975 is preferably located
underneath the black matric layer so that it does not block light
from the back light towards the pixels. 936 is the display system
driving circuit, for driving the common and addressing electrodes
(not shown) and the light source 935.
[0088] FIG. 10 shows an enlarged cross-sectional view of the
adjoining portions of two adjacent LCD tiles in the seamless tiled
structure of FIG. 9. 1001a and 1001b are the adjacent tiles. 1004
and 1005 are the front plate and the back plate. 1008 is the
sealing wall. 1006 and 1007 are the electrodes of LCD cell. 1011 is
a LC layer, including transmissive LC, e.g. TN, STN and scattering
LC, e.g. PD-LC. 1012 is the black matrix. 1030 is the color filter.
The black matrix 1012 and the color filter 1030 can be located at
the inside surface or outside surface of the front plate 1004 or
the back plate 1005.
[0089] In FIG. 10, 1003 is the gap between two adjacent LCD tiles.
1076 is the polished side walls of the back plates 1005 of the two
adjacent tiles. Between the side walls 1076, a transparent adhesive
1058, is filled. The refractive index of the adhesive 1058 is
similar to the refractive index of the back plate 1005. 1077 is a
soft black side wall of the LCD tile. The side wall 1077 is located
at the top of the gap 1003 between the adjacent tiles. It can
eliminate the leaking light from the backlight 1034 through the
gap, and protect the LCD tiles from cracking, especially where the
front plates 1004 are made of glass.
[0090] As shown in FIG. 10, the maximum angle .theta. is the
critical angle of the material of the back plate 1005. 1040 is the
light from the backlight with the maximum incident angle. In order
to get a seamless tiled display, the following conditions should be
satisfied:
[0091] T.sub.F.ltoreq.(M-H)/(2 tan.theta.), where T.sub.F is the
thickness of the front plate 1004, M is the width of the black
matrix 1012, H is the width of the gap 1003;
[0092] W.ltoreq.(M-H)/2, where W is the width of the sealing wall
1008;
[0093] P.ltoreq.(M-H)/tan.theta., where P is the height of the soft
side wall 1077.
[0094] From FIG. 10 we can see, if the thickness T.sub.B of the
back plate 1005 is equal or less than (M-H)/(2 tan.theta.), the
transparent adhesive 1058 may be omitted in the gap 1003.
[0095] FIG. 11a shows a top view of the portion of another
embodiment of a thin plastic LCD 1101, where the portion contains
four pixels. FIG. 11b shows the cross-sectional view of the LCD.
1178 is one of the four pixels of the LCD, which can be a
monochrome LCD or a color LCD which with R, G, B color filter. The
thin front plate 1104 and the thin back plate 1105 of the LCD 1101
are plastic plates, e.g. polyester or polycarbinate film. 1111 is
the LC cell, including electrodes, alignment layer, black matrix,
and color filter, where these components are not separately shown.
The LCD 1101 can be a transmissive LCD, reflective LCD or
scattering LCD. 1117 are the polarizers. 1118 is the spacer of
LCD.
[0096] The plastic LCD 1101 is sealed by laser beam during LCD
device laser cutting. Because the thin front plate 1104 and thin
back plate 1105 will be melted during laser cutting, a thin sealing
wall 1108 will be formed along the cutting edge. The width of the
sealing wall 1108 can be range of 0.01 to 10 mm. In other words,
the LCD 1101 may be made by first aligning the LC cells 1111
between two large thin sheets of plastic materials. A laser beam
may be directed towards the sheets to cut them into smaller pieces
such as the LCD 1101, where by cutting along lines that form the
edges of the smaller piece 1101, also seals the front and back
sheets together to form the side sealing walls 1108 of the LCD
1101.
[0097] The plastic LCD 1101 also can be riveted by laser beam to
increase the strength of the plastic LCD. 1179 are rivets formed by
laser beam. By directing a laser beam towards the LCD 1101 at
selected locations to drill holes at, for example 1180, the plastic
material around the hole will melt to form one of the rivets 1179
bonding the front and back plates together. 1181 is the wall of the
hole 1180 formed during hole laser drilling. Thus, the embodiment
of FIGS. 11a, 11b is particularly easier to make.
[0098] FIG. 12 shows an another embodiment of a riveted plastic LCD
1201 that is substantially the same as the embodiment of FIGS. 11a,
11b, except that, instead of through holes in the LCD, the drilling
laser does not drill all the way through, so that the area occupied
by the rivet subsequently formed can be made smaller. Furthermore,
the rivets will not be visible by the viewer even at fine
resolution. In this embodiment, the back plate 1205 is thinner than
the front plate 1204. The front plate and the back plate can be
plastic films, e.g. polyester or polycarbinate film. 1211 is the LC
cell, including electrodes, alignment layer, black matrix, color
filter and LC layer. The LCD 1201 can be a transmissive LCD,
reflective LCD or scattering LCD. 1217 are the polarizers. 1218 is
the spacer of LCD. 1208 is the sealing wall formed by laser
cutting. The laser drilling is started from the back plate using a
small diameter laser beam. The laser beam do not make a through
hole, and the drilling is stopped when both the front and back
plates 1204, 1205 are melted and attached together at a point to
form a rivet 1279 as shown in FIG. 12 without puncturing the front
plate. A transparent adhesive 1256 can be filled in the pit 1282
drilled and left by laser beam to improve the brightness uniformity
of the image. This structure and process can be used for making the
high resolution plastic LCD and large screen plastic LCD, including
transmissive LCD and reflective LCD, and can be used for making
mosaic LCD and single piece LCD.
[0099] To make an even sturdier sealing wall between the front and
back plate of the LCD, after the LC cells have been placed are
aligned onto one large thin sheet of plastic material, an adhesive
material may be applied along lines marking the boundaries of the
smaller pieces into which the sheet is to be cut and another large
sheet of plastic material is placed on top so that the adhesive
material will bond the two sheets with the LC cells aligned between
the two sheets. A laser beam may then be directed towards the
locations along the two large sheets that are bonded by the plastic
material, so as to melt the adhesive material together with the
plastic material of the two thin sheets, thereby cutting the two
large sheets along the lines of the adhesive material into smaller
pieces and thereby securely bonding the smaller pieces together at
the edges by bonding the adhesive material together with portions
of the two thin sheets so that they form one integral piece at the
edges of the smaller pieces.
[0100] Although the invention has been described in detail in the
foregoing for purpose of illustration, it is to be understood that
such details are solely for the purpose and that variations that
may be made therein by those skilled in the art with out departing
from the spirit and scope of the invention are described in the
following claims.
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