JPH0641222Y2 - Electrophoretic display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electrophoretic display device.

[Prior Art] Japanese Patent Publication No. 52-28556 discloses that in an electrophoretic display device, an asymmetric AC voltage of 20 HZ or more is applied between a pair of electrodes, and the asymmetry of the applied AC voltage is changed to change the dispersion system. A method is disclosed in which electrophoretic particles are vibrated between the electrodes to form a mixed color in a cycle corresponding to the frequency of the applied asymmetrical alternating voltage, and a method of displaying an intermediate color using a so-called afterimage phenomenon is disclosed.

[Problems to be Solved by the Invention] However, in the case of the intermediate color display method of the electrophoretic display device disclosed in the above Japanese Patent Publication No. 52-28556, it is intended to change the coloring of the dispersion system and to obtain the light transmittance. Could not be displayed in gradation by switching.

Further, in the transmissive electrophoretic display element, when the voltage is controlled as a means for displaying gradation, a low voltage is applied to have a low transmittance and a high voltage is applied to have a high transmittance. Problems such as poor responsiveness due to low voltage, loss of light transmittance difference between low voltage application and high voltage application due to vibration when using this device in a vehicle, etc. Can not withstand use.

An object of the present invention is to provide an electrophoretic display device that solves the above problems.

[Means for Solving the Problems] An electrophoretic display device according to the present invention is a transparent first substrate and a transparent substrate that is disposed at a predetermined distance from the first substrate to form a cell space. A second substrate, and a mesh-shaped or stripe-shaped transparent first linear electrode formed on the surface of the first substrate facing the second substrate,
A mesh-shaped or stripe-shaped transparent second linear electrode formed on a surface of the second substrate facing the first substrate;
A dispersion medium enclosed in the cell space and electrophoretic particles dispersed in the dispersion medium, wherein the first linear electrode and the second linear electrode are surfaces of the first substrate and the second substrate. It is characterized in that the occupied areas occupied by each are different from each other.

The feature of the present invention resides in the first linear electrode and the second linear electrode.

The first linear electrode is formed in a mesh shape or a stripe shape on the surface of the first substrate facing the second substrate. The second linear electrode is on the surface of the second substrate facing the first substrate,
It is formed in a mesh shape or a stripe shape.

The first linear electrode and the second linear electrode face each other, and are configured so that the occupied areas on the surfaces of the first substrate and the second substrate are different from each other. This has an important meaning in the transmissive electrophoretic display device.

That is, the difference in the occupied area is the area of the non-arrangement part of the first linear electrode of the first substrate and the area of the non-arrangement part of the second linear electrode of the second substrate. Will be different. When the transmissive electrophoretic display device is driven, the first
Optical paths formed between the first linear electrodes and between the second linear electrodes when the electrophoretic particles are attached to the linear electrodes and when the electrophoretic particles are attached to the second linear electrodes. This is because the area sizes of the two are different, which causes a difference in the light transmittance, and the light transmittance can be switched between two levels.

The transmittance of the light transmitted between the first linear electrodes and between the second linear electrodes can be variously changed by setting the occupied area in advance according to the purpose. For example, the occupying area of the first linear electrode and the second linear electrode is variously set so that the line width values of the mesh-shaped or stripe-shaped linear portions forming both linear electrodes are different from each other. . By setting various line width ratio values according to the purpose,
It is possible to set various ratios of light transmittance that are switched to two levels.

Further, even if the first linear electrode and the second linear electrode have the same line widths of the linear portions, by making the numbers different from each other, the occupied area of both the linear electrodes can be reduced. Can be different from each other. Also in this case, by changing the ratio of the number of linear portions of both linear electrodes, similarly to the case of changing the ratio of the line widths, various ratios of the light transmittance for switching to two stages are set. be able to. The first linear electrode and the second linear electrode can be formed by using various transparent conductive materials such as ITO (indium-tin-oxide) and tin dioxide as the conductive material.

The first linear electrode and the second linear electrode are formed by alternately forming a linear portion provided as a transparent electrode on the inner surface side of the transparent substrate and a non-provided portion. The terminals are connected to each other, and a voltage can be applied by a common lead wire. The first linear electrode and the second linear electrode have a cross-sectional shape formed directly on the inner surface of the transparent substrate without processing the inner surface of the transparent substrate, such as rectangular, triangular, semicircular, and other various shapes. It is possible to use a material having a sawtooth shape or an uneven shape obtained by processing the inner surface of the substrate and having a surface substantially parallel to the transmitted light.

Further, these electrodes can be formed by using various conventionally known vacuum deposition methods, high frequency sputtering methods, spray methods, photoetching methods, and the like.

The first substrate and the second substrate are formed of a transparent glass plate or a transparent resin plate. Further, as the transparent substrate, any one can be used as long as it is translucent even if it is slightly colored.

The shapes of the first and second substrates forming the cell portion may be rectangular, circular, or various other shapes.

The dispersion medium and the electrophoretic particles can be the same as the conventional ones. The dispersion medium is a non-conductive insulating type, and normally a halogen type solvent having a relatively large specific gravity is used. As the dispersion medium, a colored one containing a soluble colorant or a colorless one containing no colorant can be used. It is preferable that the electrophoretic particles have the same density as that of the dispersion medium. As the electrophoretic particles, positively charged particles or negatively charged particles can be selectively used according to the purpose. Further, both of these particles can be used by dispersing them in a dispersion medium.

[Operation and Effect] The first linear electrode and the second electrode of the electrophoretic display device of the present invention.
The linear electrodes are formed such that the occupied areas of the surfaces of the first substrate and the second substrate are different from each other.

Therefore, the first substrate and the second substrate are different in the area of the non-arranged portion of the first linear electrode and the second linear electrode,
When the electrophoretic particles dispersed in the dispersion medium are attached to the first linear electrode and when the electrophoretic particles are attached to the second linear electrode, the amount of light passing through the two non-arranged portions having different areas is different. It will be different.

Therefore, according to the electrophoretic display device of the present invention, when the electrophoretic display device is driven to transmit light, the electrophoretic particles dispersed in the dispersion medium are attached to the first linear electrode to transmit the light and the second linear electrode. With the transmission state of the light attached to the electrode, it is possible to switch to different light transmission areas,
In the same element, the light transmittances are different when the two light are in the transmissive state.

For this reason, in the transmissive electrophoretic display element, it is possible to reliably switch the light transmittance between two levels, and the application is wide. It can also be used, for example, as a sunroof, a sun visor, a headlamp cover, etc. of a vehicle, and in these cases, it is excellent in terms of function and design.

Example FIG. 1 is a cross-sectional view showing the electrophoretic display device of this example.
This will be described with reference to FIGS. 2 and 3.

The electrophoretic display device 1 includes a first substrate 10 and a second substrate.
20, spacer 30, seal member 40, and first linear electrode
50 and the second linear electrode 60, the dispersion medium 70 and the electrophoretic particles 80.

Both the first substrate 10 and the second substrate 20 have a thickness (1.1 mm
It consists of a transparent soda-lime glass plate (made by Asahi Glass). Further, as shown in FIG. 1, transparent first linear electrodes 50 and second linear electrodes 60 are formed on the inner surfaces 100 and 200 of the two substrates 10 and 20 facing each other.

The first linear electrode 50 is composed of a plurality of stripe-shaped electrode portions 500 arranged and formed on the inner surface 100 of the first substrate 10. And the line width L1 of each striped electrode portion 500
Is set to 600 μm, and the line interval L10 is set to 400 μm. The first linear electrode 50 having such a shape is formed on the first substrate.
It is made by uniformly vapor-depositing ITO on the surface 100 of 10 to a thickness of about 500 Å by ion plating, and then patterning by photolithography. The second linear electrode 60 is composed of a plurality of stripe-shaped electrode portions 600 arranged and formed on the inner surface 200 of the second substrate 20. The line width L2 of each striped electrode part 600 is 200μ.
m, L20 between lines is set to 800 μm. The second linear electrode 60 having such a shape is transparent like the first linear electrode 50.
It is formed with ITO to a thickness of approximately 500Å.

Further, lead wires (not shown) are bonded and connected to the respective peripheral portions of the first linear electrode 50 and the second linear electrode 60 with a conductive adhesive in order to transmit the applied voltage.

The spacers 30 are arranged in a sandwich shape on the peripheral portions of the inner surfaces 100 and 200 of the first substrate 10 and the second substrate 20, which face each other, except for a portion serving as an injection port (not shown) for the dispersion medium 70, A gap in which the dispersion medium 70 can be enclosed is formed in the first and second substrates 10 and 20. This spacer 30 has a thickness of 100
A μm polyester film (manufactured by Toray Industries Inc.) is cut to have a frame shape that is surrounded by the first substrate 10 and the second substrate 20 and has a width of about 5 mm and is partially surrounded by a strip as an injection port. . An epoxy adhesive is applied to the outer peripheral portion of the spacer 30 excluding the injection port portion to form the seal member 40. In this way, the cell part is manufactured.

As the dispersion medium 70, xylene / tetrachloroethylene (manufactured by Nacalai Tesque, Inc.) was used. In this dispersion medium 70,
The background color dye is not included.

The electrophoretic particles 80 are red pigments (Re-made by Nippon Ciba Geigy).
d BRN) was used. This is a particle whose surface is positively charged.

A dispersion liquid was prepared in which the concentration of the electrophoretic particles 80 was adjusted to 1% by weight and a slight amount of a dispersion stabilizing surfactant was added. Then, after the dispersion liquid is injected into the cell part 1 from the injection port to fill the inner space of the cell part 1, the injection port part is filled and sealed with a seal member (not shown) made of the same material as the seal member 40. .

The electrophoretic display device 1 of the example having the above-described configuration is
When no voltage is applied to the first linear electrode 50 and the second linear electrode 60, the electrophoretic particles 80 are substantially uniformly dispersed in the dispersion medium 70 as shown in FIG. There is. For this reason, the red color of the electrophoretic particles 80 can be visually recognized from the viewing side, and the light transmittance in this case is extremely small at about 0.5%.

Here, when a voltage of DC200V is applied with the first linear electrode 50 as the cathode and the second linear electrode 60 as the anode, the electrophoretic particles 80 positively charged in the dispersion medium 70 are as shown in FIG. It adheres along each striped electrode part 500. As a result, a light transmission path L11 is formed between the stripe-shaped electrode portions 500, and the incident light R from the second substrate 20 side is the light transmission path L11.
Through. In this case, the light transmittance is 36%. Therefore, the electrophoretic display element 1 is in a transmissive state of a gradation with a small amount of light even when the light is in a transmissive state.

When a voltage of DC200V is applied with the first linear electrode 50 as the anode and the second linear electrode 60 as the cathode, the electrophoretic particles 80 positively charged in the dispersion medium 70 are shown in FIG. Adhere along the striped electrode portion 600. As a result, the light transmission path L21 is formed between the striped electrode portions 600, and the second
Incident light R from the substrate 20 side passes through the light transmission path L21.
In this case, the light transmittance is 72%. This transmittance is 72%
Is twice as high as the transmittance of 36% when the electrophoretic particles 80 are adhered to each stripe-shaped electrode portion 500 of the first linear electrode 50, and a transmission state with increased clarity is obtained by this amount. To be

(Modification) Next, a modification of the present embodiment will be described with reference to FIGS. In this modified example, in the figure, the same parts as those in the above-described embodiment are designated by the same reference numerals, and different parts are designated by the reference numerals in parentheses.

In this modification, kerosene / propylene bromide (manufactured by Nacalai Tesque) is used as the dispersion medium 70a, and electrophoretic particles are used.
Instead of the red pigment of the above embodiment, a black pigment having a negatively charged surface (Love Call Black manufactured by Dainippon Seika) is used as 80a, and each striped electrode portion 5 of the first linear electrode 50a is used.
The line width L1a of 00a is set to 800 μm, the line interval L10a is set to 200 μm, and each stripe-shaped electrode portion 600 of the second linear electrode 60a is set.
The configuration is the same as that of the above embodiment except that the line width L2a of a is set to 400 μm and the line spacing L20a is set to 600 μm.

Here, the first linear electrode 50a is an anode and the second linear electrode 60a is
When a voltage of DC200V is applied as a cathode, the electrophoretic particles 80a that are negatively charged in the dispersion medium 70a are attached along the striped electrode portions 500a as shown in FIG. As a result, the light transmission path L11a is provided between the striped electrode portions 500a.
Is formed, and the incident light R from the second substrate 20a side is transmitted through the light transmission path L11a. In this case, the light transmittance is 18%. Therefore, the electrophoretic display element 1 is in a transmissive state of a gradation with a small amount of light even when the light is in a transmissive state.

Further, when a voltage of DC200V is applied with the first linear electrode 50a as a cathode and the second linear electrode 60a as an anode, electrophoretic particles 80a that are positively charged in the dispersion medium 70a are respectively charged as shown in FIG. It adheres along the striped electrode portion 600a. As a result, the light transmission passage L21a is formed on the side of each striped electrode portion 600a, and the incident light R from the second substrate 20a side is transmitted through the light transmission passage L21a. In this case, the light transmittance is 54%. The transmittance of 54% is 1 when the electromigration particles 80a are attached to the respective striped electrode portions 500a of the first linear electrode 50a.
It is three times as much as 8%, and a transparent state with increased brightness can be obtained.

As described above, in the electrophoretic display elements of the above-mentioned embodiment and modification,
It is possible to switch and change the light transmittance when transmitting light, and the gradation of the brightness can be displayed in two steps, and the case where red display and black display are displayed when the light is blocked is shown. The present invention is not limited to this, and it is possible to select the two-stage transmittance ratio and the type of color of the electrophoretic particles according to the purpose of use.

[Brief description of drawings]

FIG. 1 shows an electrophoretic display device according to an embodiment of the present invention,
And it is sectional drawing which shows the state which does not apply a voltage to a 1st linear electrode and a 2nd linear electrode. FIG. 2 is a sectional view showing a state in which a voltage is applied so that the electrophoretic particles adhere to the first linear electrode side in FIG. FIG. 3 is a sectional view showing a state in which a voltage is applied so that the electrophoretic particles adhere to the second linear electrode side as well. 10 ... Transparent first substrate 20 ... Transparent second substrate 30 ... Spacer, 40 ... Sealing member 50 ... First linear electrode 500 ... Striped electrode portion 60 ... Second linear electrode 600 ... Striped electrode portion 70 ... Dispersion medium, 80 ... Electrophoretic particles L1 ... Line width, L10 ... Line spacing L11 ... Light transmission passage, L21 ... Light transmission passage L2 ... Line width, L20 ... Line spacing

Claims (1)

[Scope of utility model registration request] 1. A transparent first substrate, a transparent second substrate disposed at a predetermined distance from the first substrate to form a cell space, and the first substrate of the first substrate. Two transparent mesh-shaped or striped linear electrodes formed on the surface facing the two substrates, and a mesh-shaped or striped transparent first linear electrode formed on the surface of the second substrate facing the first substrate. A second linear electrode, a dispersion medium enclosed in the cell space, and electrophoretic particles dispersed in the dispersion medium, wherein the first linear electrode and the second linear electrode are the first substrate. And an electrophoretic display device, wherein the occupied areas of the surface of the second substrate are different from each other.