JPH01251085A - Electrophoresis display device - Google Patents

Abstract

PURPOSE:To simplify a control circuit by executing simultaneously write and an erasion by using one piece of high frequency discharger and one set of control electrode. CONSTITUTION:A high frequency power source is used as a mechanism for generating an ion. When a frequency voltage is applied to a discharge electrode 7, both a positive ion and a negative ion are generated in a discharger 5, they are electrified selectively onto a back dielectric substrate 3 by a control electrode 8 and an electrostatic image is obtained. In a part to which an ion whose polarity is the same as that of colored fine particle in an electrophoresis dispersion system 4 has been electrified, the fine particle are migrated to a transparent electrode 2 side, and in a part to which an ion of the opposite polarity has been electrified, the fine particle are migrated to the back dielectric substrate 3 side, therefore, write and an erasion in an electrophoresis display can be realized. In such a way, an inexpensive electrophoresis display device whose constitution is simple can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophoretic display device used as an image display device.

(Prior Art) An electrophoretic display device is a device in which a dispersion system in which colored fine particles are dispersed in a liquid dispersion medium is hermetically filled between two substrates, and an electric field is applied to move the fine particles to obtain a display. Research and development is progressing in various places as a method to obtain high-quality displays at low cost.

(Problem to be Solved by the Invention) A method using ions generated by corona discharge has been proposed as a method of forming an electrostatic image on a rear dielectric substrate (Jikai 62-34187), L Kashi, Corona There is a problem in that ions generated by discharge are unipolar, and one pair of electrodes can only perform writing or erasing. One method to solve this problem is to switch the polarity of the corona discharge, but in this case, the control circuit becomes extremely complex. It is necessary to switch between the positive polarity DC voltage source and the negative polarity DC voltage source of the overlay KV, but it is impossible to switch this using general semiconductor elements, and mechanical switching requires arcing. The problem is that it is extremely dangerous. Another method is to arrange the writing corona discharger and the electrode erasing corona discharger and electrode in parallel, but in this case, the writing start origin position and the erasing start origin position must be precisely aligned. In addition, there was a problem in that the erasing electrode protruded beyond the surface screen during writing, and the writing electrode protruded beyond the surface screen during erasing.

The present invention provides an electrophoretic display device that has a simple configuration and is inexpensive.

(Means for Solving the Problems) The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention, and the feature of the present invention is that a high frequency power source is used as a mechanism for generating ions. When a high frequency voltage is applied to the discharge electrode 7, both positive ions and negative ions are generated within the discharger 5. This is selectively charged onto the back dielectric substrate 3 by the control electrode 8 to obtain an electrostatic image. In the portions of the electrophoretic dispersion system 4 charged with ions of the same polarity as the colored fine particles, the fine particles migrate toward the transparent electrode 2, and in the portions charged with ions of the opposite polarity, the fine particles migrate toward the rear dielectric substrate 3 side. Thereby, writing and erasing in electrophoretic display can be realized.

An example of this is shown in FIG.
0.5 to IMHz% between electrodes 7a and 7c sandwiching b.
A high frequency voltage of about 1 to 10 KV is applied to generate both positive ions and negative ions.

The control electrode 8 is configured such that an upper electrode 8a and a lower electrode 8b are arranged at a predetermined interval, and ions can pass through a through hole provided in the center. When the control power source 12 and the bias power source 13 are applied as shown in FIG. 2(a), the electric field is in the forward direction, allowing positive ions to pass through and blocking negative ions from passing through.

Conversely, when the control power source 12 and bias power source 13 are applied with opposite polarities as shown in FIG. 2(b), positive ions are prevented from passing through, while negative ions are allowed to pass through.

(Effects of the Invention) In the electrophoretic display device of the present invention, writing and erasing can be simultaneously realized by using one high-frequency discharger and one set of control electrodes, so the control circuit is also simplified.
There is no need to switch high-voltage DC voltage sources, and
The electrode portion can be made smaller, and its protrusion outside the display screen is also reduced. In addition, since it is a method that always charges either positive ions or negative ions, a display with high contrast can be obtained.For reasons such as 0 or more, high contrast display devices can be made at low cost, and there is no problem with increasing the size. Therefore, it can also be applied to a large display device the size of a blackboard.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention, and FIGS. 2(a) and 2(b) are circuit diagrams illustrating an embodiment of the control electrode and its operating principle. Explanation of symbols 1. Transparent substrate 2. Transparent electrode 3, dielectric substrate 4. Electrophoretic dispersion system 5, discharge device
6. Spacer 7, discharge electrode 8. Control electrode 9, charged ions 10. Charged negative ions 11, high frequency power supply 12. Control power supply 13, bias power supply Fig. 1 (a) (b) Fig. 2

Claims (1)

[Claims] 1. In an electrophoretic display device in which an electrophoretic dispersion system is hermetically packed between a transparent substrate on which a transparent electrode is formed and a rear dielectric substrate, a flow of both positive and negative ions is generated by one high-frequency discharger. An electrophoretic display device characterized in that it is configured to display and erase an electrostatic image formed on the rear dielectric substrate by a pair of electrodes that control the electrophoretic image.