JP4711525B2 - Optical switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical switching device used for optical display, camera diaphragm, strobe light amount adjustment, and the like.
[0002]
[Prior art]
As an apparatus of this type that performs optical switching, an apparatus using an LCD or an apparatus using electrophoresis of particles in a fluid is known. This optical switching device is often used as a display device, and FIG. 4 shows a main part of the display device using the electrophoresis. This figure is a side sectional view of the display section.
[0003]
In FIG. 4, reference numerals 11 and 12 denote two substrates arranged in parallel. A solvent containing a dye is enclosed in the substrates 11 and 12, and white or light colored particles 14 are mixed in the solvent 13. . In addition, transparent planar electrodes 15 and 16 are provided inside the substrates 11 and 12, respectively.
[0004]
When a voltage is applied between the two electrodes 15 and 16, the particles 14 in the solvent 13 move according to the applied voltage. Thereby, the state of the light passing through the two substrates 11 and 12 changes, and a desired display can be performed.
[0005]
[Problems to be solved by the invention]
Incidentally, the optical switching device as described above has a problem that the contrast is low. This is because the black level is not easily obtained due to the absorption of the dye, and the white level is likely to deteriorate due to the coloring of the dye to the particles which are white bodies. Further, in the case where a high refractive material such as ITO is required on the upper side, there is a problem that the black level is deteriorated due to surface reflection of ITO or the like.
[0006]
In addition, the display is memorized (stored) due to the vertical dispersibility of the particles, but it is difficult to stably hold the particles unless the specific gravity of the solvent and the particles is equal, and even if they are aligned, they are stable in the vertical direction. It is extremely difficult to hold the particles, and halftone display is almost impossible.
[0007]
The present invention has been made paying attention to the above-mentioned problems, and an object thereof is to provide an optical switching device which can obtain high contrast, can easily control halftones, and can be easily colored. Yes.
[0008]
[Means for Solving the Problems]
The optical switching device according to the present invention is configured as follows.
[0009]
(1) A transparent fluid is filled in the opposing substrate, particles of a predetermined diameter are mixed in the fluid, a planar electrode is formed inside one substrate, and a corner is formed inside the other substrate. By forming an electrode having a portion and applying an electric field having a DC component between both electrodes , the fluid and particles in the fluid are moved clockwise or counterclockwise around the corner portion. did.
[0010]
(2) In the configuration of (1) above, an object that can pass fluid and cannot pass particles is arranged at a predetermined position.
[0011]
(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 through which particles cannot pass.
[0012]
(4) In the configuration of the above (2) or (3), an object that can pass a fluid but cannot pass a particle is linearly provided below an electrode having a corner.
[0013]
(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]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 is an enlarged top view showing a main part of an optical switching device according to the present invention. Here, an example of an optical display device is shown.
[0016]
In the figure, reference numeral 1 denotes a dielectric transparent fluid (liquid) filled in opposing transparent substrates in a predetermined area. Display particles 2 having a predetermined diameter are mixed and dispersed in this fluid. The two transparent substrates are arranged in parallel to each other, and a planar solid electrode having no corners or edges is formed as the lower electrode 3 on the inner side of one (lower) substrate, and the other (upper). An upper electrode 5 having a corner portion 4 at only one place is formed inside the substrate.
[0017]
Further, an object 6 that can pass the transparent fluid 1 but cannot pass the particles 2 is disposed at a predetermined position (A portion). In this example, the object 6 is linearly provided below the upper electrode 5 having the corner portion 4.
[0018]
FIG. 2 is a top view showing a configuration of a display unit having a plurality of predetermined areas having the above structure, and FIG. 3 is a top view showing details of each area.
[0019]
The area surrounding each transparent fluid is surrounded by a wall member (filter) 7 made of a material through which particles 2 cannot pass. The upper electrode 5 is a translucent electrode, and the lower electrode 3 is formed in a stripe shape.
[0020]
In the display device of the present embodiment, the upper electrode 5 having the 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, the upper electrode A clockwise or counterclockwise force is generated around the edge of the corner portion 4 of 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.
[0021]
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 filter in the part A that allows the fluid 1 to pass therethrough but blocks the particles 2. Thereby, a display device with high contrast and memory property can be realized.
[0022]
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, high contrast display can be obtained with a simple structure without devising the structure of the electrodes and display elements.
[0023]
Next, a description will be given of results obtained when the display device having the above structure is TFT-driven and statically driven.
[0024]
(Example 1: TFT drive)
Hollow particles having an average particle diameter of 10 μmφ are used as the particles 2, nematic liquid crystal ZLI-2231 (made by Merck) is used as the dielectric fluid 1, and RN-722L (made by Nissan Chemical Industries) is used as the alignment film. It was. Further, 10 wt% of particles were added to the liquid crystal, and the rib material used in the PDP, O-LED, LCD, etc. was used for the wall and the A portion separating the display portion.
[0025]
The height of the wall was about 50 μm, and part A was about 5 μm lower than that. As a result, neither the liquid crystal nor the particles can pass through the wall portion, and the liquid crystal can pass through the A portion, and the particles cannot pass therethrough. Actually, such a structure can be realized by reducing the number of photolitho formation times of the rib material by 1-3 times from the wall portion.
[0026]
ITO (solid) was used for the lower electrode 3, and black CF was formed thereon as a light absorption layer. Mo was used for the upper electrode 5.
[0027]
In the above configuration, the lower electrode (common) was grounded, and DC (direct current) was applied to the upper electrode. At that time, each applied voltage was controlled using a TFT (not shown) for the upper electrode.
[0028]
At this time, the rotation direction of the particles (clockwise or counterclockwise) varies depending on the material used, but the rotation speed is substantially 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 correspondingly and the display is switched. However, when a certain time elapses in balance with the voltage holding ratio, the voltage becomes 0 V due to discharge, and the rotation of the particles stops.
[0029]
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 finally applied so that the potential difference between the electrodes becomes 0 V in order to actively stop the rotation of the particles.
[0030]
In addition, a required amount of fluid and particles were dropped onto each display region to superimpose the substrates. The dropping may be performed by a dispenser, but an inkjet method or the like may be used in order to make the dropping amount more accurate. In the examples, the material was dropped using an inkjet method. Furthermore, another particle, for example, a particle having a different color may be inserted for each pixel.
[0031]
As described above, as a result of the display of this example, high contrast was obtained and colorization was easy. Also, control of halftones and the like was easy.
[0032]
(Example 2: Static drive)
Black colored silica particles having a particle diameter of 6 μmφ 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 protrudes from the display portion was used.
[0033]
A portion of the upper electrode 5 and the wall member have slits with holes of about 2 μm (not shown), and the wall height is about 30 μm (cell thickness). At that time, after arranging particles of about 10% of the volume of the display portion in the display portion, the substrates were overlapped, and dielectric fluid Isoper L (manufactured by Exson Chemical) was vacuum-injected in the same manner as the LCD.
[0034]
The upper electrode was grounded, and a rectangular wave voltage (1 KHz) with an offset voltage superimposed on the lower electrode was applied. As a result, the particles could be rotated around the corner portion of the upper electrode as in the above example.
[0035]
As described above, in the optical switching device of the present invention, the movement corresponding to the rotation of the particles in the fluid is stable at a constant speed, the control of the middle is easy, and the particles of different colors are arranged in each block. Therefore, colorization is easy. In this case, the display is extremely bright.
[0036]
In addition, there is no need for an electrode having a special structure, and since no high refractive index material such as ITO is disposed on the upper side of the display unit, external light is not reflected and is incident on the display unit, so that high contrast is obtained. . Since the display unit is surrounded by a wall, it is not affected by the convection of the adjacent display unit. Further, since there is one corner per display portion, all particles can move by receiving one force with respect to the electric field. Furthermore, a polarizing plate is unnecessary, it is bright, it has a display memory property, and it has ultra-low power consumption.
[0037]
In addition, the present invention can be applied not only to the reflection type display device as in the embodiments but also to a camera diaphragm or a strobe light amount adjusting means.
[0038]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain high contrast as an optical device with a simple configuration, to easily control halftones, and to achieve colorization.
[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 showing a configuration of a display unit in an embodiment. FIG. 3 is a top view showing details of each area in the embodiment. 4] Cross-sectional view showing the main part of a display device using electrophoresis [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transparent fluid 2 Particle | grain 3 Lower electrode 4 Corner part 5 Upper electrode 6 Object 7 Wall member

Claims (5)

The opposite 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 corners are formed inside the other substrate. The fluid and the particles in the fluid are moved clockwise or counterclockwise around the corner by applying an electric field having a direct current component between both electrodes. Optical switching device.   2. The optical switching device according to claim 1, wherein an object that allows passage of fluid but not passage of particles is arranged at a predetermined position.   3. The optical switching device according to claim 1, wherein a predetermined area filled with a fluid is surrounded by at least a substance that cannot pass through particles.   4. The optical switching device according to claim 2, wherein an object that allows passage of fluid but not passage of particles is provided linearly below an electrode having a corner.   The optical switching device according to claim 1, wherein the fluid is a dielectric fluid.

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