JPH0518738Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device that realizes a simple display using the principle of electrophoresis.

(Prior art) Technologies in this field include, for example, "Japanese Chemistry and Technology '84/published by Display Chemical Technology Museum,"
There were items listed on pages 86 to 95.

Until now, there have been few examples of devices using the principle of electrophoresis being put into practical use, but as described in the above literature, fine particles (about 0.2 μm in diameter) such as pigment TiO ₂ are mixed into a liquid dispersion medium. An electric double layer is formed, and a voltage is applied to this dispersion medium (thickness 10-20-50 μm).
When 1v/1μm is applied, charged particles migrate through the liquid due to Crohn's force, and the color of the surface of the liquid panel changes depending on the particles. When the voltage is removed, the particles maintain their position, so the display is retained. When erasing the displayed image, a reverse voltage is applied to cause the particles to migrate in the opposite direction, removing the color from the surface of the liquid panel.

(Problem to be solved by the invention) In order to display an arbitrary image in a matrix using the above principle, minute cells are arranged in a matrix, all cells are filled with a dispersion medium, and all It is necessary to control the display/hide of cells individually. For this reason, for example, it is necessary to provide a thin film diode or a thin film transistor corresponding to each matrix, thereby controlling each matrix individually. Therefore, it has been difficult to put medium-sized or large-sized display devices into practical use.

The present invention was made to solve these problems, and it is an electrophoretic display that simplifies the structure of the electrophoretic board and can form a display device without individually controlling each cell of the matrix. The purpose is to provide equipment.

(Means for solving the problem) In order to achieve this purpose, the present invention provides an electrophoretic display device in which one surface is made uniformly a ground surface, and the other surface is made into a three-layer structure, so that each pixel is divided into three layers. It is characterized by providing an information storage capacitor and displaying by applying a voltage to each capacitor.

(Function) According to the above-mentioned means, it is no longer necessary to configure a plurality of cells for displaying an image and to control each cell individually by providing a thin film diode or the like in each cell, which greatly simplifies the structure of the display panel. can be realized. Therefore, both large and medium-sized display devices can be constructed at low cost, and no holding power is required during display.

(Example) Examples will be described below with reference to the drawings.

Figure 1a is a sectional view of an electrophoresis board for explaining an embodiment of the present invention, Figure 1b is a plan view of the electrophoresis board seen from the back, and Figure 2 is a back board 1.
FIG. 3 is an enlarged cross-sectional view of No. 3. In the figure, reference numeral 11 denotes a surface board, which is constructed by coating or pasting a transparent electrode on the inside of a transparent resin (approximately 100 μm thick). With this transparent electrode, the surface board 11
has a uniform potential.

On the back side of the surface board 11, there is an electrophoretic medium 12
is enclosed between it and the back board 13. For example, a spacer such as a glass ball may be interposed between the front board 11 and the back board 13, and an electrophoretic medium may be enclosed in the space formed thereby.

The back board 13 is further divided into three layers.
That is, the backmost layer 14 is the surface opposite to the front board 11, the pixel layer 15 is in contact with the electrophoretic medium 12, and the inner layer 16 is sandwiched between the backmost layer 14 and the pixel layer 15.

The backmost layer 14 is a layer that appears outside as the surface opposite to the front board 11. A plurality of contact electrodes 17 are formed on this bottom layer 14 . The contact electrodes 17 are arranged in a matrix to correspond to the display pixels of the display.

The pixel layer 15 is a layer that is in direct contact with the electrophoretic medium 12 enclosed between the front board 11 and the back board 13. In this pixel layer 14,
Display pixels 18, which are metal films, are arranged in a matrix.

The inner layer 16 is a surface sandwiched between the backmost layer 14 and the pixel layer 15, and the contact electrode 17 formed on the backmost layer 14 and the display pixel 18 formed on the pixel layer 15 are connected to the inner layer 16. It is electrically connected by a penetration part 19 penetrating through 16. For this reason, it is preferable to form, for example, a through hole in the penetrating portion 19 to connect the two.

A ground air shield surface 20 is formed between the inner layer 16 and the pixel layer 15 except for the penetrating portion of the penetrating portion 19 . In reality, it is necessary to provide a small space around the penetrating portion of the penetrating portion 19 to prevent conduction between the penetrating portion 19 and the ground air shield surface 20. The inner layer 16 is formed by applying a dielectric with a thickness of about 1 μm.

With such a structure, when a voltage is applied to the contact electrode 17 of the bottom layer 14, a capacitor realized by the display pixel 18 and the earth shield surface 20 is charged. This potential causes the electrophoretic medium 12
electrophoretic particles are driven. That is, it is attracted or repelled by the display pixel 18 depending on the voltage. At this time, the portion where the electrophoretic particles are attracted to the display pixels 18 is captured as an image when viewed from the front board 11 side.

For display purposes, a line head 30, shown in FIG. 1b, is used. The line head 30 is constructed by arranging in a line the same number of electrodes as the contact electrodes 17 formed horizontally on the bottom layer 14. The number is determined by the size of the display, the fineness of the display matrix, etc.
It consists of 1000 to 2000 electrodes.

This line head 30 can move up and down while contacting the surface of the backmost layer 14 of the display. As a result, a voltage is applied to one horizontal line of contact electrodes arranged in a matrix,
Displays one line. Next, the line head 30 moves downward by one line of the contact electrode, applies a voltage to this one line, and displays this line.
By moving the line head 30 in this manner, a voltage is applied to each line of the contact electrodes arranged in a matrix to perform display.

Since the line head 30 moves while contacting the contact electrode 17, a sufficient voltage can be applied to the contact electrode.

(Effects of the invention) As explained in detail above, according to the invention, each pixel is charged at high speed, and the writing voltage is directly applied to the electrophoresis panel by the line head, so the writing voltage is about 20 to 30V. Can be driven with low voltage. This device can display a large display with a wide viewing angle and high contrast at high speed, so it is clearer than OHP and can be used for a wide range of applications, such as various information displays for a large number of people and remote electronic conferences. Furthermore, if the electrophoretic medium is dyed with a dye and the pixels are separated and sealed in each cell with a separator, color display becomes possible.

[Brief explanation of the drawing]

FIG. 1a is a sectional view of an electrophoresis board for explaining an embodiment of the present invention, FIG. 1b is a plan view of the electrophoresis board as seen from the back side, and FIG. 2 is an enlarged sectional view of the back board 13. 11... surface board, 12... electrophoretic medium,
13...Back board, 14...Backmost layer of back board, 15...Pixel layer, 16...Inner layer, 17...
... Contact electrode, 18 ... Display pixel, 19 ... Penetration part, 20 ... Earth shield surface.

Claims (1)

[Claims for Utility Model Registration] Consisting of a transparent front board, a back board, and an electrophoretic medium sealed between the front board and the back board, a voltage is applied to the electrophoretic medium. In an electrophoretic display device that performs display, the back board is in contact with the electrophoretic medium,
and has a plurality of display pixels arranged in a matrix that can accumulate electric charge, and is movable in the vertical direction on the back side of the back board, and one of the plurality of display pixels in the horizontal direction
An electrophoretic display device characterized by having a line head that applies a voltage to each line.