JP2501690Y2 - Transmissive electrophoretic display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a transmissive electrophoretic display device used as a display device for industrial machines such as home appliances, computers and automobiles, or as a window blind of automobiles and houses. Regarding

[Prior Art] An electrophoretic display element has a dispersion liquid layer in which particles are dispersed in an insulating liquid enclosed between a pair of glass substrates having transparent electrodes. By utilizing the fact that the particles have a surface charge, the particles are moved by electrophoresis to visualize the signal.

As a conventional electrophoretic display, for example, one shown in FIG. 5 is known (Japanese Patent Laid-Open No. 62-299824). In FIG. 5, a pair of substrates 1a and 1b are arranged so as to face each other, at least the display-side substrate 1a is transparent, and transparent electrode layers 3a are provided on the opposite faces of the respective substrates 1a and 1b. 3b and 3c are provided. Board 1a
A spacer 6 is fixed to the inner surface of the peripheral portion of the substrate 1 so as to form a cell between 1 and 1b. The dispersion layer is formed by dispersing the dispersion particles 4 in a dispersion medium 5 made of an insulating liquid.
It is formed by being injected into the cell formed between 1a and 1b.

When no voltage is applied to the electrodes, the dispersed particles 4 are dispersed in the dispersion medium 5, and the substrate on the display side displays the color of the dispersion medium 5. However, when a voltage is applied to the electrodes, the dispersed particles 4 change the applied voltage. The display side substrate displays the color of the dispersed particles 4 because it migrates and adheres to one of the electrodes depending on the polarity.

[Problems to be Solved by the Invention] As described above, in the conventional electrophoretic display device, when no voltage is applied to the electrode layer, the dispersed particles are dispersed in the dispersion medium, and the display-side substrate is a dye of the dispersion medium. When a voltage is applied to the electrode layer to display the color of the dispersed layer, the dispersed particle adheres to the display portion where the electrode layer is formed and the color of the dispersed particle is displayed. However, it could not be used as a transmissive display element as it was.

Therefore, if transmissive display is possible in the conventional electrophoretic display element, the range of color tones that can be displayed as the display element is expanded, and the range of application as window blinds of automobiles and houses is expanded.

The present invention has been made in view of the problem that the conventional electrophoretic display element cannot perform transmissive display as it is. By enabling transmissive display of the electrophoretic display element, a display range as a display element can be obtained. It is an object of the present invention to provide a transmissive electrophoretic display device which can be used as a blind, etc.

[Means for Solving the Problems] The transmissive electrophoretic display device of the present invention comprises two transparent substrates arranged to face each other, and a peripheral edge of the transparent substrate for forming a cell between the transparent substrates. A spacer fixed to the portion, a large number of horizontal partition walls that vertically divide the cell into a large number of minute portions, an electrode layer formed on the upper and lower surfaces of the horizontal partition wall, and enclosed in each minute portion of the cell. The gist of the invention is that it comprises a dispersion medium having a high insulating property and dispersed particles dispersed in each dispersion medium.

The transparent substrate used in the electrophoretic display device of the present invention is
It may be a glass substrate or a resin substrate. Also,
The transparent substrate may be slightly colored as long as it has translucency.

The spacer is interposed in the peripheral portion of the transparent substrate to form a cell by keeping the transparent substrate at a predetermined distance, and the dispersion medium and the dispersed particles are enclosed in the cell.

The horizontal partition wall horizontally divides the cells formed by the transparent substrate and the spacers and distributes them into a minute portion, and it is preferable to use a transparent partition wall in order to improve light transmission.
The horizontal partition and the transparent substrate may be attached to the transparent substrate at right angles as shown in FIG. 3, or when the transparent substrate is oblique as shown in FIG. The horizontal partition may be obliquely attached to the transparent substrate.

The electrode layers formed on the upper surface and the lower surface of the horizontal partition are those in which the vertically opposed electrode layers have mutually different polarities, and may be formed using a transparent conductive material.
It may be formed of a metal thin film such as l or Cr. As the material of the transparent electrode, various transparent conductive materials can be used, but ITO (indium-tin-oxide), tin dioxide or the like is usually used. The method of forming the electrode layer is
Various vapor deposition methods or sputtering and spray-firing methods can be used.

A conventional dispersion medium can be used for the dispersion liquid layer. The dispersion medium is a non-conductive insulating type, and usually a halogen type solvent such as bromine having a relatively large specific gravity is used. The dispersion medium may be an uncolored transparent one or a colorant-containing one.

Further, the dispersion particles are those which are positively or negatively charged in the dispersion medium, and those having substantially the same specific gravity as the dispersion medium or having different specific gravity from the dispersion medium are used depending on the purpose. When used as a display element, one having a desired color is used, and when used as a blind, one having an appropriate color is used so as to block light.

[Operation] First, a case where the specific gravity of the dispersion medium and the dispersion particles enclosed in each minute portion of the cell is different will be described.

When no specific voltage is applied to the electrode layer and the specific gravity of the dispersed particles is light, the dispersed particles float from the dispersion medium and adhere to the electrode layer on the lower surface of the horizontal partition. On the other hand, if the specific gravity of the dispersed particles is heavy,
The dispersed particles settle on the bottom of the dispersion medium and adhere to the electrode layer on the upper surface of the horizontal partition. Therefore, in either case, the light is transmitted.

Next, when an AC voltage is applied between the electrode layers of each minute portion facing each other, the dispersed particles of each minute portion move into the dispersion medium by the action of the electric field, and the dispersed particles are dispersed in the dispersion medium. Then, the electrophoretic display element is colored by the dispersed particles or is in a light-shielding state by the dispersed particles.

Next, the case where the specific gravity of the dispersion medium and the specific gravity of the dispersed particles are almost equal will be described.

When no voltage is applied to the electrode layer, since the dispersed particles are dispersed in the dispersion medium, the electrophoretic display element is colored by the dispersed particles or is in a light shielding state by the dispersed particles.

Next, when a DC voltage is applied between the electrodes facing each other in each minute portion, since the dispersed particles are positively or negatively charged, they are attracted to the positive or negative electrode layer and migrate in the dispersion medium. , Attached to either the upper or lower electrode layer of the horizontal partition. Therefore, the display element is in a light transmitting state.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention should not be construed as being limited to what is described in the examples below.

FIG. 1 is a sectional view of an embodiment of the present invention. The two transparent substrates 1a and 1b are soda-lime glass (made by Asahi Glass) having a thickness of 1.8 mm, and the two transparent substrates 1a and 1b are arranged so as to face each other with a desired gap therebetween. A spacer 6 made of a polyester film (manufactured by Toray) having a thickness of 100 μm is fixed to the inner surface of the part to form cells between the substrates.

The horizontal partition walls 2 ... are plate materials made of Asahi Kasei's photosensitive resin APR, which horizontally traverses the cells formed by the transparent substrates 1a and 1b spacers 6 and divides the cells into a plurality of upper and lower parts to form minute portions. Thus, it is attached to the transparent substrates 1a and 1b. Electrode layers 3a ... And 3b ... made of ITO are formed with a thickness of 1500Å on the upper surface and the lower surface of each horizontal partition wall 2 which face each other. Although not shown, the electrode layers 3a ... And the electrode layers 3b ... Are collectively connected to a conductive wire and connected to an AC power source.

Dispersed particles 4 and dispersion medium 5 are enclosed in each minute portion of the cell. As the dispersion particles 4, a pigment Labcorol manufactured by Dainichiseika Co., Ltd. having a higher specific gravity than the dispersion medium 5 was used, and as the dispersion medium 5, transparent kerosene (manufactured by Nacalai Tesque) was used.

Next, the operation of the apparatus of this embodiment will be described with reference to FIGS. 1 and 2.

When no voltage is applied between the electrode layers 3a-3b, the dispersed particles 4
Since the specific gravity of is larger than that of the dispersion medium 5, the dispersed particles 4 are deposited on the bottom of the dispersion medium and adhere to the electrode layer 3b on the upper surface of the horizontal partition wall 2 as shown in FIG. Therefore, since incident light is transmitted through the cell, the electrophoretic display element is in a transmissive state.

Next, between the electrode layers 3a-3b facing each other in each minute portion,
When an alternating voltage with a frequency of 50 Hz and a voltage of 100 V is applied, as shown in FIG. 2, the dispersed particles 4 in each minute portion move into the dispersion medium 5 due to the action of the electric field. And the electrophoretic display element is colored by the dispersed particles 4 or is in a light shielding state by the dispersed particles 4.

When this AC voltage is turned off, the dispersed particles 4 immediately settle in the dispersion medium 5, so that the electrophoretic display element is again in a light transmitting state.

In this example, the case where the specific gravity of the dispersed particles is larger than that of the dispersion medium 5 is shown. On the contrary, when the specific gravity of the dispersed particles 4 is smaller than that of the dispersion medium 5, the particles are dispersed in a voltage cutoff state. The operation is the same as that of the present embodiment except that the particles 4 float from the dispersion medium 5 and adhere to the electrode layer 3a on the lower surface of the horizontal partition 2.

When the specific gravity of the dispersed particles 4 is the same as that of the dispersion medium 5,
Although the dispersed particles 4 are dispersed in the dispersion medium 5 in the voltage cut-off state to be in a colored state or a light cut-off state, when a DC voltage is applied between 3a and 3b, the charged dispersed particles 4 are dispersed in the dispersion medium 5. The electrophoretic display element is electrophoresed, and the dispersed particles 4 are attached to one of the electrode layers, so that the electrophoretic display element is in a light transmitting state.

[Advantages of the Invention] As described above, the transmissive electrophoretic display device of the present invention divides a cell formed by a transparent substrate and a spacer into minute parts by horizontal partition walls, and forms electrode layers on the upper and lower surfaces of the horizontal partition walls. Provided, the dispersion medium and the dispersion particles are enclosed in each minute part, and when the specific gravity of the dispersion particles and the dispersion medium are different, the floating state or the sedimentation of the dispersion particles gives a light transmission state to the electrode layer. By applying an AC voltage, the dispersed particles are dispersed in the dispersion medium, and the colored state of the dispersed particles or the light blocking state can be obtained. Also,
When the specific gravity of the dispersed particles is equal to that of the dispersion medium, when no voltage is applied, the dispersed particles are dispersed in the dispersion medium and a colored state or a blocked state is obtained. A transparent state is obtained. Thus, the electrophoretic display device of the present invention enables transmissive display, and is extremely useful as a display device or as a window blind of an automobile or a house.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view for explaining the operation of the embodiment of FIG. 1, FIG. 3 and FIG. 5 is a sectional view of a conventional electrophoretic display element. 1a and 1b ... Transparent substrate, 2 ... Horizontal partition, 3a and 3b
...... Electrode layer, 4 ... Dispersion particles, 5 ... Dispersion medium, 6 ... Spacer

Claims (1)

(57) [Scope of utility model registration request] 1. Two transparent substrates arranged to face each other,
Spacers fixed to the peripheral edge of the transparent substrate to form cells between the transparent substrates, a large number of horizontal partition walls that vertically divide the cells into a number of minute portions, and upper and lower surfaces of the horizontal partition walls. Transmissive electrophoretic display device characterized by comprising: a formed electrode layer, a highly insulating dispersion medium enclosed in each minute portion of the cell, and dispersed particles dispersed in each dispersion medium. .