Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-08-31
2002-08-27
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S166000, C349S084000, C349S086000, C349S066000, C345S107000, C359S296000
Reexamination Certificate
active
06441881
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from Japanese Patent Application No. P2000-279478, filed on Sep. 14, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display element utilizing a phenomenon in which particles filled in a cell are moved when a voltage is applied onto the cell.
2. Discussion of the Background
Various types display elements have been studied as display elements for information equipments and other purpose of use. For example, there are display elements using liquid crystals or display elements using electrophoresis.
In a liquid crystal display element, the liquid crystal is filled in a cell. When a voltage is applied onto this cell, the orientation of the liquid crystal molecule is changed, and by this change, the light transmissivity of the whole cell is changed. By the change of the light transmissivity, white and back are expressed, and the information is displayed.
In the condition that the electric field is not applied, for a liquid crystal display apparatus through which the light is normally transmitted, the liquid crystal display changes in such a manner that the light is not transmitted through. Further, in the condition that the electric field is not applied, for a liquid crystal display apparatus through which the light normally is not transmitted when the electric field is applied, the liquid crystal display is changed in such a manner that the light is transmitted through. Further, the intensity of the light can be changed corresponding to the intensity of the electric field.
The liquid crystal display element has the advantage that it is smaller in electric consumption than a cathode ray tube (CRT) display, and a thin type display panel can be realized. Accordingly, the liquid crystal display element has been widely used for a personal computer, word processor, and other information equipments for the office.
However, liquid crystal display elements require fine processing, production is difficult, and the cost is high. Further, because transmitted light is used, a bright display apparatus is hardly produced. Further, because polarized light is used, commonly the easily viewed direction is limited.
On the other hand, a display element operated by electrophoresis has an advantage that, because the light to be observed is a reflected light, it is bright, and an angle of visibility is easily increased.
A display element using the electrophoresis is generally structured in such a manner that the non-conductive liquid, in which the electrophoresis particles are dispersed, is sandwiched by a pair of transparent electrodes. Electrophoresis particles formed of white non-conductive liquid or colored titanium oxide are often used. The electrophoresis particles are charged positively or negatively.
When an electric field is applied onto the liquid layer, the charged electrophoresis particles are moved corresponding to the electric field. When the electrophoresis particles are collected to the transparent electrode on the observer side, the electrophoresis particles cover the transparent electrode on the observer side. Conversely, when the electrophoresis particles are separated from the transparent electrode on the observer side, the non-conductive liquid comes into contact with the transparent electrode. For example, when electrophoresis particles are black, and the non-conductive liquid is white, and when electrophoresis particles cover the transparent electrode on the observer side, the black is displayed. When the electrophoresis particles are separated from the transparent electrode on the observer side, white is displayed.
A conventional electrophoresis display element has, for example, the structure as shown in FIG.
1
.
In the electrophoresis display element, a non-conductive liquid
6
is filled between the substrate
1
and the substrate
2
. These substrate
1
and substrate
2
have respectively an electrode
3
and an electrode
4
. The substrate and electrode which display an image, are transparent, and a non-conductive liquid
6
can be observed from the outside. Further, charged colored particles
7
are dispersed in the non-conductive liquid
6
.
When the voltage is applied between the electrode
3
and the electrode
4
, the charged colored particles
7
dispersed in the non-conductive liquid
6
are moved along the direction of the electric field.
For example, a case where the colored particles
7
are negative charged black particles, and the non-conductive liquid
6
is white, will be considered herein.
When a positive potential is applied onto the electrode
4
, and a negative potential is applied onto the electrode
3
, black particles
7
are moved to substrate
2
by the electrophoresis. At this time, “black” appears on the substrate
2
(as shown in FIG.
1
A). Further, when an inverse potential difference is applied between electrodes, the black particles
7
are moved to substrate
1
. In this case, “white” (i.e., the color of the non-conductive liquid
6
) appears on the substrate
2
(as shown in FIG.
1
B). In this manner, a change of different colors can be displayed on the observed surface.
In such an electrophoresis display element, there are problems, and the electrophoresis display has not yet come into practical use.
For practical use, it is necessary to realize low voltage drive and high speed response.
To realize a low voltage drive, the distance between electrodes can be reduced and the intensity of the electric field can be increased. Further, for a high speed response, the distance between substrates and the movement distance needs to be reduced. That is, for both low voltage drive and high speed response, the distance between substrates needs to be reduced.
However, when the distance between substrates is reduced, there is a problem that the thickness of the non-conductive liquid is reduced, and light penetrates through the non-conductive liquid. Accordingly, when the white display is regarded as important, it is necessary that the degree of turbidity of the white non-conductive liquid is increased. However, when black particles are collected on the display surface side, there is a tendency for the white of the non-conductive liquid to remain on the display surface side, making the display surface gray. That is, when a good white display is conducted, the black display becomes insufficient.
Reversely, when the degree of turbidity of the white liquid is decreased, a good black display can be conducted, but there is a tendency for the white display to become insufficient.
As described above, in the conventional electrophoresis element, the structure appropriate for the low voltage drive and the high speed response can not maintain the display quality. Further, a reduction in the thickness of a display element is difficult in a conventional electrophoresis element.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a noval display which ameliorates the problems of the conventional display.
The above object, and other objects, are achieved accordingly to the present invention by providing a noval reflective display including a transparent first substrate, a transparent first electrode formed on the first substrate, a second substrate located opposite to the first substrate, a second electrode formed on the second substrate, partition walls dividing the display into cells, each cell surrounded by the partition walls, the first substrate, and the second substrate and provided with an electrical bias from the first electrode and the second electrode, the partition walls slanted with respect to the first substrate and the second substrate, and at least one colored particle located in at least one cell and configured to move within the at least one cell such that a side of a part of the partition wall is observed through the first substrate under a first bias condition and the side is obscured by the at lea
Enomoto Shintaro
Nakai Yutaka
Nakao Hideyuki
Yamaguchi Hajime
Litovchenk V.
Parker Kenneth
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