Optical waveguides – Illuminating or display apparatus
Reexamination Certificate
1999-07-01
2004-04-20
Font, Frank G. (Department: 2877)
Optical waveguides
Illuminating or display apparatus
C385S147000, C385S019000, C385S031000
Reexamination Certificate
active
06724973
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a display device which consumes less electric power, and which has large screen brightness. In particular, the present invention relates to improvement in the display device for displaying a picture image corresponding to an image signal on an optical waveguide plate by controlling leakage light at a predetermined position on the optical waveguide plate by controlling the displacement action of an actuator element in a direction to make contact or separation with respect to the optical waveguide plate in accordance with the attribute of the image signal to be inputted. The present invention also relates to a method for producing the display device.
BACKGROUND ART
Those hitherto known as the display device include, for example, cathode ray tubes (CRT) and liquid crystal display devices.
Those known as the cathode ray tube include, for example, ordinary television receivers and monitor units for computers. Although the cathode ray tube has a bright screen, it consumes a large amount of electric power.
Further, the cathode ray tube involves a problem that the depth of the entire display device is large as compared with the size of the screen.
On the other hand, the liquid crystal display device is advantageous in that the entire device can be miniaturized, and the display device consumes a small amount of electric power. However, the liquid crystal display device involves problems that it is inferior in brightness of the screen, and the field angle of the screen is narrow.
In the case of the cathode ray tube and the liquid crystal display device, it is necessary for a color screen to use a number of pixels which is three times a number of pixels used in a black-and-white screen. For this reason, other problems occur in that the device itself is complicated, a great deal of electric power is consumed, and it is inevitable to cause the increase in cost.
In order to solve the problems described above, the present applicant has suggested a novel display device (see, for example, Japanese Laid-Open Patent Publication No. 7-287176). As shown in
FIG. 63
, this display device includes actuator elements
400
arranged for respective pixels. Each of the actuator elements
400
comprises a main actuator element
408
including a piezoelectric/electrostrictive layer
402
and an upper electrode
404
and a lower electrode
406
formed on upper and lower surfaces of the piezoelectric/electrostrictive layer
402
respectively, and an actuator substrate
414
including a vibrating section
410
and a fixed section
412
disposed under the main actuator element
408
. The lower electrode
406
of the main actuator element
408
contacts with the vibrating section
410
. The main actuator element
408
is supported by the vibrating section
410
.
The actuator substrate
414
is composed of ceramics in which the vibrating section
410
and the fixed section
412
are integrated into one unit. A recess
416
is formed in the actuator substrate
414
so that the vibrating section
410
is thin-walled.
A displacement-transmitting section
420
for obtaining a predetermined size of contact area with respect to an optical waveguide plate
418
is connected to the upper electrode
404
of the main actuator element
408
. In the illustrative display device shown in
FIG. 63
, the displacement-transmitting section
420
is arranged such that it is located closely near to the optical waveguide plate
418
in the OFF selection state or the NO selection state in which the actuator element
400
stands still, while it contacts with the optical waveguide plate
418
in the ON selection state at a distance of not more than the wavelength of the light.
The light
422
is introduced, for example, from a lateral end of the optical waveguide plate
418
. In this arrangement, all of the light
422
is totally reflected at the inside of the optical waveguide plate
418
without being transmitted through front and back surfaces thereof by controlling the magnitude of the refractive index of the optical waveguide plate
418
. In this state, a voltage signal corresponding to an attribute of an image signal is selectively applied to the actuator element
400
by the aid of the upper electrode
404
and the lower electrode
406
so that the actuator element
400
is allowed to make a variety of displacement actions in conformity with the ON selection, the OFF selection, and the NO selection. Thus, the displacement-transmitting section
420
is controlled for its contact and separation with respect to the optical waveguide plate
418
. Accordingly, the scattered light (leakage light)
424
is controlled at a predetermined portion of the optical waveguide plate
418
, and a picture image corresponding to the image signal is displayed on the optical waveguide plate
418
.
When a color picture is displayed by using the display device, the following operation is performed. That is, for example, light sources for three primary colors are switched to control the light emission time for three primary colors while synchronizing the contact time between the optical waveguide plate and the displacement-transmitting plate with the period of color development. Alternatively, the contact time between the optical waveguide plate and the displacement-transmitting plate is controlled, while synchronizing the light emission time for three primary colors with the color development period.
Therefore, the illustrative display device suggested by the present applicant is advantageous in that it is unnecessary to increase the number of pixels as compared with the black-and-white screen, even when the display device is applied to the color display system.
An object of the present invention is to provide a display device and a method for producing the same to exhibit the following effects, by improving the arrangement of the illustrative display device suggested by the present applicant.
(1) The clearance (gap) can be easily formed between the optical waveguide plate and the pixel structure, and the gap can be formed uniformly for all of the pixels.
(2) The size of the gap can be easily controlled.
(3) The adhesion of the pixel structure to the optical waveguide plate can be avoided, and it is possible to effectively realize a high response speed.
(4) The contact surface of the pixel structure (contact surface with respect to the optical waveguide plate) can be formed to be smooth so that the light is efficiently introduced into the pixel structure when the predetermined pixel structure makes contact with the optical waveguide plate.
(5) It is possible to ensure the response speed of the pixel.
(6) It is possible to obtain the uniform brightness for all of the pixels.
(7) It is possible to improve the brightness of the pixel.
DISCLOSURE OF THE INVENTION
According to the present invention, there is provided a display device comprising an optical waveguide plate for introducing light thereinto; an actuator substrate provided opposingly to one plate surface of the optical waveguide plate and arranged with actuator elements of a number corresponding to a large number of pixels; a pixel structure formed on each of the actuator elements of the actuator substrate; and a crosspiece formed at a portion other than the pixel structure between the optical waveguide plate and the actuator substrate (invention as defined in claim 1).
According to the present invention, all of the light, which is introduced, for example, from a lateral end of the optical waveguide plate, is totally reflected at the inside of the optical waveguide plate without being transmitted through front and back surfaces thereof by controlling the magnitude of the refractive index of the optical waveguide plate. In this state, when the displacement-transmitting section approaches the optical waveguide plate in accordance with the displacement action of the actuator section, the light, which has been subjected to total reflection, is reflected by the pixel structure, and it behaves as scattered light. A part of the scattered light is reflec
Akao Takayoshi
Nanataki Tsutomu
Shimogawa Natsumi
Takeuchi Yukihisa
Font Frank G.
Mooney Michael P.
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