JP2002244164A - Optical switching device - Google Patents

Abstract

(57) Abstract: An optical switching device that performs optical display by moving particles in a fluid so as to obtain high display contrast with a simple configuration. SOLUTION: A transparent fluid 1 is filled in two opposing substrates in a predetermined area, and particles 2 are mixed therein. A planar lower electrode (solid electrode) 3 is provided inside the lower substrate.
Is formed, and an upper electrode 5 having one corner portion 4 is formed inside the upper substrate. Further, an object 6 that allows the passage of the fluid 1 but does not allow the passage of the particles 2 is disposed below the upper electrode 5 and is surrounded by a substance that cannot pass the particles 2 for each predetermined area. Then, a voltage is applied between the upper electrode 5 and the lower electrode 3 to move the particles 2 in the fluid 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical display,
The present invention relates to an optical switching device used for adjusting the aperture of a camera, adjusting the amount of light of a strobe, and the like.

[0002]

2. Description of the Related Art As this type of device for performing optical switching, a device using an LCD and a device using electrophoresis of particles in a fluid are known. This optical switching device is often used as a display device,
FIG. 4 shows a main part of a display device using the above-mentioned electrophoresis.
FIG. 2 is a side sectional view of the display unit.

In FIG. 4, reference numerals 11 and 12 denote two substrates arranged in parallel. A solvent containing a dye is sealed in the substrates 11 and 12, and white or light-colored particles 14 are mixed in the solvent 13. Have been. Transparent flat electrodes 15 and 16 are provided inside the substrates 11 and 12, respectively.

When a voltage is applied between the two electrodes 15 and 16, the particles 14 in the solvent 13 are changed according to the applied voltage.
Moves. Accordingly, the state of light passing through the two substrates 11 and 12 changes, and a desired display can be performed.

[0005]

However, the above optical switching device has a problem that the contrast is low. This is because it is not possible to obtain sufficient black to produce a black portion by the absorption of the dye, and the white level is liable to be deteriorated due to coloring of the white particles with the dye. In the case where a high refraction material such as ITO is required on the upper side, there is also a problem that the black level is deteriorated by surface reflection of ITO or the like.

[0006] In addition, the display is memorized (stored) due to the vertical dispersibility of the particles. However, it is difficult to stably hold the particles unless the specific gravity of the solvent and the particles is adjusted. It is extremely difficult to stably retain the particles, and halftone display is almost impossible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an optical switching device which can provide high contrast, can easily control halftones and the like, and can be easily colored. It is an object.

[0008]

The optical switching device according to the present invention is configured as follows.

(1) An opposing substrate is filled with a transparent fluid, particles of a predetermined diameter are mixed in the fluid, a planar electrode is formed inside one substrate, and a transparent electrode is formed inside the other substrate. Was formed with an electrode having a corner, and the particles in the fluid were moved by the voltage applied to both electrodes.

(2) In the configuration of the above (1), an object which can pass a fluid but cannot pass a particle is arranged at a predetermined position.

(3) In the configuration of the above (1) or (2), the periphery of the predetermined area filled with the fluid is surrounded by at least a substance that cannot pass particles.

(4) In the above configuration (2) or (3), an object that allows passage of a fluid but does not allow passage of particles is linearly provided below the electrode having a corner portion.

(5) In any one of the constitutions (1) to (4), the fluid is a dielectric fluid (a material having a resistance close to that of an insulator).

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged top view showing an essential part of an optical switching device according to the present invention, and here shows an example in which the optical switching device is configured as an optical display device.

In FIG. 1, reference numeral 1 denotes a dielectric transparent fluid (liquid) filled in a predetermined area of an opposing transparent substrate, into which particles 2 for display having a predetermined diameter are mixed and dispersed. I have. The two transparent substrates are arranged in parallel with each other, and a flat solid electrode having no corners or edges is formed as a lower electrode 3 inside one (lower) substrate, and the other (upper). Only one corner 4 inside the substrate
Is formed.

An object 6 that can pass through the transparent fluid 1 but cannot pass through the particles 2 is disposed at a predetermined position (part A). The object 6 is linearly provided below the upper electrode 5 having the corner portion 4 in this example.

FIG. 2 is a top view showing the structure of a display section having a plurality of predetermined areas of the above structure, and FIG. 3 is a top view showing details of each area.

A wall member (filter) made of a material through which the particles 2 cannot pass is provided around each area in which the transparent fluid is sealed.
Surrounded by 7. The upper electrode 5 is a translucent electrode, and the lower electrode 3 is formed in a stripe shape.

In the display device of this embodiment, the upper electrode 5 having one corner portion 4 is disposed on the solid lower electrode 3, and when an electric field having a DC component is applied between the upper and lower electrodes. A clockwise or counterclockwise force is generated around the edge of the corner portion 4 of the upper electrode 5. When the dielectric fluid 1 and the particles 2 dispersed therein are filled between the upper and lower electrodes, the particles 2 can be moved clockwise or counterclockwise according to the polarity of the applied electric field.

At this time, the particles 2 can be collected on the display unit or below the upper electrode 5 by providing an object 6 as a wall or a filter in the portion A, through which the above-mentioned fluid 1 passes but particles 2 are damped. . Thus, a display device with high contrast and memory properties can be realized.

Here, the moving speed of the particles 2 tends to be faster when moving outside the upper electrode 5 than when moving below the upper electrode 5 (about three times). For this reason, a high contrast display can be obtained with a simple structure without devising the structures of the electrodes and the display element.

Next, a description will be given of the results obtained when the display device having the above configuration is driven by TFT and static driving.

(Example 1: TFT driving) As the particles 2, hollow particles having an average particle diameter of 10 μmφ were used, and a dielectric fluid 1 was used.
Nematic liquid crystal ZLI-2231 (Mer
RN-722L (manufactured by Nissan Chemical Industries, Ltd.). In addition, 10 wt.
%, PDP, OL on the wall separating the display and on the part A
The rib material used in ED, LCD, etc. was used.

The height of the wall is about 50 μm.
The part was about 5 μm lower than that. As a result, the wall cannot pass through both the liquid crystal and the particles, and the portion A can pass through the liquid crystal but cannot pass through the particles. Actually, such a structure can be realized by reducing the number of photolithographic formations of the rib material in the portion A one to three times from the wall portion.

The lower electrode 3 was made of ITO (solid), and black CF was formed thereon as a light absorbing layer. Upper electrode 5
Mo was used.

In the above configuration, the lower electrode (common) was grounded, and DC (direct current) was applied to the upper electrode. At this time, each applied voltage was controlled using a TFT (not shown) for the upper electrode.

At this time, the rotation direction (clockwise or counterclockwise) of the particles differs depending on the material used, but the rotation speed is almost proportional to the absolute value of the applied voltage. Since a TFT is used in this embodiment, an arbitrary voltage can be applied. For example, when a certain voltage is applied once, the particles rotate accordingly to switch the display. However, in a balance with the voltage holding ratio, after a certain period of time, the voltage becomes 0 V due to discharge, and the rotation of the particles stops.

Therefore, the state of the particles can be controlled by the voltage value applied once. Of course, the voltage may be applied a plurality of times, and the voltage may be applied so that the potential difference between the electrodes becomes 0 V at the end in order to positively stop the rotation of the particles.

Further, a required amount of fluid and particles were dropped on each display area, and the substrates were overlapped. Although the dispensing may be performed by a dispenser, an ink jet method or the like may be used in order to make the dispensing amount more accurate. In the example, the material was dropped using an inkjet method. Furthermore, another particle for each pixel,
For example, particles of different colors may be inserted.

As described above, as a result of the display of this embodiment, a high contrast was obtained, and colorization was easy. In addition, control of halftone and the like was easy.

(Example 2: Static Driving) Black colored silica particles having a uniform particle diameter of 6 μm were used as the particles 2, and a patterned Al electrode was used as the lower electrode 3. The lower surface of the Al electrode has irregularities and functions as a scattering reflector. For the upper electrode 5, Cr having a pattern in which only one corner protruded from the display portion was used.

The portion A and the wall member of the upper electrode 5 have slit-shaped holes of about 2 μm (not shown), and the height of the wall is about 30 μm (cell thickness). At this time, after arranging particles of about 10% of the volume of the display portion in the display portion, the substrates are overlapped, and a dielectric fluid Isoper L (Ex
son Chemical Co., Ltd.) by vacuum injection in the same manner as the LCD.

Then, the upper electrode was grounded, and a rectangular wave voltage (1 KHz) in which an offset voltage was superimposed was applied to the lower electrode. As a result, similarly to the above-described embodiment, the particles could be rotationally moved around the corner of the upper electrode.

As described above, in the optical switching device of the present invention, the movement of the particles in the fluid corresponding to the rotation is stable at a constant speed, the control of the middle and the like is easy, and the particles of different colors are included in each block. By arranging, colorization is easy. In this case, an extremely bright display is obtained.

In addition, no electrode having a special structure is required, and a high-refractive index material such as ITO is not disposed on the upper side of the display unit. Is obtained. Since the display is surrounded by the wall, it is not affected by convection of the adjacent display. Also one
Since there is one corner per display unit, all particles can move by receiving one force against the electric field. Furthermore,
It does not require a polarizing plate, is bright, has display memory properties, and has very low power consumption.

Further, the present invention can be applied not only to the entire reflection type display device as in the embodiment but also to a means for adjusting the aperture of a camera or a strobe light.

[0038]

As described above, according to the present invention,
High contrast can be obtained as an optical device with a simple configuration, control of halftone and the like is easy, and colorization is easy.

[Brief description of the drawings]

FIG. 1 is a top view showing a main part of an optical switching device according to the present invention.

FIG. 2 is a top view illustrating a configuration of a display unit according to the embodiment.

FIG. 3 is a top view showing details of each area of the embodiment.

FIG. 4 is a cross-sectional view showing a main part of a display device using electrophoresis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent fluid 2 Particle 3 Lower electrode 4 Corner part 5 Upper electrode 6 Object 7 Wall member

Claims (5)

[Claims] A transparent fluid is filled in an opposing substrate,
While mixing particles of a predetermined diameter into the fluid, a planar electrode is formed inside one substrate, and an electrode having a corner is formed inside the other substrate, and application to both electrodes is performed. An optical switching device, wherein particles in the fluid are moved by a voltage. 2. An object which is capable of passing a fluid but not a particle is disposed at a predetermined position.
An optical switching device according to any of the preceding claims. 3. The optical switching device according to claim 1, wherein the periphery of the predetermined area filled with the fluid is surrounded by at least a substance through which particles cannot pass. 4. The optical switching device according to claim 2, wherein an object through which fluid can pass but particles cannot pass is provided in a line below the electrode having a corner. 5. The optical switching device according to claim 1, wherein the fluid is a dielectric fluid.