Optical waveguides – Optical fiber bundle – Fiber bundle plate
Reexamination Certificate
2000-12-27
2004-07-27
Duverne, Jean F. (Department: 2839)
Optical waveguides
Optical fiber bundle
Fiber bundle plate
Reexamination Certificate
active
06768846
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display device and a method for producing the same. In particular, the present invention relates to a display device which involves no fear of any incomplete light off state, and a method for producing the same.
2. Description of the Related Art
FIG. 38
shows an example of a large screen display in which a plurality of display devices are arranged on an optical waveguide plate. The large screen display
100
has, for example, such features that it is of the direct vision type, it is of the thin type, it has a high luminance, and it has a wide angle of visibility. A plurality of display devices
10
as described later on are arranged in the vertical direction and in the lateral direction respectively on a first surface (back surface) of the large optical waveguide plate
102
which is composed of, for example, glass or acrylic to construct the large screen display of the thin type. In addition to the ordinary display having an oblong configuration, it is possible to form screens having a variety of shapes including, for example, those having a rectangular configuration with a longer horizontal length, those having a rectangular configuration with a longer vertical length, and those having a circular configuration, by arbitrarily changing the arrangement of the display devices
10
. It is also possible to form a curved surface display by previously curving the optical waveguide plate.
FIG. 39
shows a schematic cross section of the display device
10
. The display device
10
comprises an actuator substrate
12
, an optical waveguide plate
14
, and a plurality of crosspieces
16
allowed to intervene between the both. The optical waveguide plate
14
and the crosspieces
16
are joined to one another by the aid of an adhesive
17
. The actuator substrate
12
has an actuator element
18
which is displaceable toward the actuator substrate
12
or toward the optical waveguide plate
14
at a position surrounded by the plurality of crosspieces
16
. A unit dot
22
is constructed by the actuator element
18
and a picture element assembly
20
which is provided on the actuator element
18
. As described later on, the display device
10
is provided with a plurality of unit dots
22
.
The unit dot
22
is specifically constructed as follows. That is, a hollow space
24
is formed at the inside of the actuator substrate
12
corresponding to the position at which the actuator element
18
is provided. Therefore, the portion of the actuator substrate
12
, at which the actuator element
18
is provided, has a thin wall thickness as compared with the other portions (the portion will be hereinafter referred to as “thin-walled section”
12
a
).
The actuator element
18
comprises a shape-retaining layer
26
which is composed of a piezoelectric/electrostrictive material or an anti-ferroelectric material, a column electrode
28
which is provided on the lower surface of the shape-retaining layer
26
, and a row electrode
30
which is formed over a range from the side surface to the upper surface of the shape-retaining layer
26
with a through-hole
13
provided through the actuator substrate
12
from the lower surface of the actuator substrate
12
.
The picture element assembly
20
, which is formed on the actuator element
18
, is a laminate comprising a white scattering element layer
32
, a color filter layer
34
, and a transparent layer
36
. As described later on, when the picture element assembly
20
abuts against the optical waveguide plate
14
, the light
38
, which is guided through the inside of the optical waveguide plate
14
, is reflected. In this process, the light
38
is colored to have a color corresponding to a color of the color filter layer
34
, and the light
38
is emitted to the outside of the optical waveguide plate
14
. Accordingly, the unit dot
22
emits light with the color corresponding to the color filter layer
34
.
Therefore, when the color of the color filter layer
34
is varied for each of the unit dots
22
so that the light emission is obtained with the red color for a certain unit dot
22
, the green color for another unit dot
22
, and the blue color for still another unit dot
22
, then the entire display device
10
is provided with the three primary colors of light. Therefore, the display device
10
is capable of emitting all colors. In the following description, a group, in which one or more unit dots
22
for causing red light emission, is referred to as “red dot”, and it is designated by reference numeral
22
R. Similarly, groups, in which one or more unit dots for causing green light emission and blue light emission, are referred to as “green dot” (designated by reference numeral
22
G) and “blue dot” (designated by reference numeral
22
B) respectively.
In general, as shown in
FIG. 40
, the red dot
22
R, the green dot
22
G, and the blue dot
22
B are arranged in an aligned manner. A picture element (pixel)
40
is constructed by them. The display device
10
comprises a plurality of such picture elements
40
, and it displays a variety of colors depending on the light emission states of the red dot
22
R, the green dot
22
G, and the blue dot
22
B. As a result, an image is displayed on the large optical waveguide plate
102
of the large screen display
100
.
In the display device
10
constructed as described above, as shown in
FIG. 39
, when the upper end surface of the picture element assembly
20
(transparent layer
36
) abuts against the optical waveguide plate
14
, then the light
38
, which is guided through the inside of the optical waveguide plate
14
, is transmitted through the transparent layer
36
and the color filter layer
34
, and then it is reflected by the white scattering element layer
32
. The light is emitted as the scattered light
42
to the outside of the optical waveguide plate
14
. As a result, the display device
10
causes light emission with the color corresponding to the color filter layer
34
.
When the voltage is applied between the column electrode
28
and the row electrode
30
, for example, if the column electrode
28
is the positive electrode, then the electric field, which is directed from the column electrode
28
to the row electrode
30
, is generated. As a result, the polarization is induced in the shape-retaining layer
26
, and the strain, which is directed to the column electrode
28
, is generated in the shape-retaining layer
26
. As shown in
FIG. 41
, the strain cause bending deformation of the actuator element
18
. The entire actuator element
18
is displaced downwardly, and the upper end surface of the picture element assembly
20
is separated from the optical waveguide plate
14
. In this situation, the light
38
is not reflected by the picture element assembly
20
, and it is guided through the inside of the optical waveguide plate
14
. Therefore, the light
38
is not emitted to the outside of the optical waveguide plate
14
. That is, in this situation, the display device
10
is in the light off state.
When the applied voltage is changed so that the difference in electric potential between the both electrodes
28
,
30
is decreased, the strain of the shape-retaining layer
26
is removed in accordance with a hysteresis manner. That is, the strain of the shape-retaining layer
26
is scarcely removed at the beginning at which the difference in electric potential between the column electrode
28
and the row electrode
30
is initially decreased. When the difference in electric potential is further decreased, the strain is quickly removed. Finally, the upper end surface of the picture element assembly
20
abuts against the optical waveguide plate
14
again, and thus the display device
10
is in the light emission state (see FIG.
39
).
As clearly understood from the above, the luminance and the light emission color of the display device
10
can be adjusted by adjusting the difference in electric potential between the column electrode
28
and the row electrode
30
. Fu
Akao Takayoshi
Nanataki Tsutomu
Shimogawa Natsumi
Takeuchi Yukihisa
Yamamoto Kazuhiro
Burr & Brown
Duverne Jean F.
NGK Insulators Ltd.
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