JPS6336511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a display device that electrically controls light reflectance and light transmittance.

2. Description of the Related Art Conventionally, liquid crystal display devices have been widely used as so-called passive displays for displaying characters, figures, images, and the like. However, this type of display device has several problems that are essentially difficult to improve, such as a narrow operating temperature range, difficulty in producing a wide screen, and slow response speed.

In view of the above, the present inventors have first proposed a method for applying liquid to a display structure including a porous body made of a film or a plate-like dielectric material having a large number of fine openings exposed on at least one surface. A composite body impregnated with the material is placed on a supporting base material surface such that one surface portion having the opening faces the open space, and a first electrode is provided between the porous body and the supporting base material. is located, and the second electrode is isolated from the first electrode and placed between the porous body and the supporting base material, or on the surface of the porous body on the opposite side to the supporting base material. a display section for controlling external light corresponding to at least one of the first and second electrodes on the main surface side of the porous body facing the open space; The present invention proposes a display device which has means for applying a signal voltage between the porous bodies and which controls external light by controlling the liquid impregnation rate of the display section by moving the liquid material with respect to the porous body in accordance with the signal voltage. did.

This type of display device scatters external light by controlling the liquid impregnation rate on the surface of the porous body by utilizing the electroosmotic phenomenon of the liquid material in the porous body.
Causes diffuse reflection and refraction.

The dielectric material forming the porous body is preferably composed of a translucent dielectric material itself, or a translucent dielectric material colored with a dye, pigment, or the like.
The porous body is preferably made of any material as long as it has pores or gaps that substantially penetrate from one surface to the opposite surface, but in particular, the material has an average pore diameter of 0.1 μm.
A microporous membrane filter made of plastic material such as cellulose ester with a diameter of about 1.0 μm is suitable. The liquid material is preferably translucent, and particularly preferably has a light refractive index approximately equal to that of the translucent dielectric material itself which is the constituent material of the porous body. The second electrode installed on the surface side of the porous body facing the open space is preferably transparent and permeable to liquid, and is coated with a conductive film of, for example, a metal oxide. .

On the surface of the porous body facing the open space, fine depressions in the form of dots, strips, lines, networks, etc., including a plurality of the above-mentioned fine openings, can be provided. In this case, the refraction and scattering rate of external light can be significantly improved. In this configuration, the second electrode made of a transparent and liquid-permeable conductive film can be deposited on the inner surface of the recessed portion, and at the same time, the recessed portion can be selectively coated with opaque ink. Opaque-forming agents such as oil repellents can be applied. In addition, the above-mentioned conductive film is not applied, the above-mentioned recessed portion is left on the surface of the porous body, and the necessary above-mentioned opacity-forming agent is selectively applied, and a second layer made of conductive ink is applied.
electrodes can be coated.

When the porous body is made of a colored dielectric material, it is useful as a reflective display device, and when the porous body is made of a translucent dielectric material, it is useful as a transmissive and reflective display device.

This type of display device has a wide operating temperature range due to the use of a liquid material with a high boiling point, a wide screen can be easily obtained due to the use of porous paper as the display structure, and furthermore, it is possible to control external light. It has many advantages, such as saturation with extremely small liquid movement of about 1 micron due to electroosmosis, and can have an extremely fast response speed compared to display devices such as liquid crystals.

However, since this type of display device includes the movement of liquid material as an essential element, it has been found that the freedom of movement of liquid material due to electroosmosis plays an important role in operating characteristics and display image quality.

Conventionally, porous bodies were placed directly on the supporting base material surface without being fixed, and the gaps between them were used to
The liquid material was given a certain degree of freedom.

However, in particular, a second electrode is provided on the surface of the porous body opposite to the first electrode, and a signal voltage is applied between the two opposing electrodes to electro-osmote the liquid material in the thickness direction of the porous body. When using a liquid material, it is essential that the liquid material directly enters and exits the gap. Therefore, the entire porous body is forced to move up and down, and sometimes the porous body adheres tightly to the support base material, making it difficult for the liquid material to flow in and out of the gap.

This non-uniformity causes non-uniformity in characteristics and image quality. This tendency is particularly noticeable in large-screen display devices.

The present invention has been made against the background of the above-mentioned problems.
The object of the present invention is to provide a display device that improves this problem.

To describe the present invention more specifically, in the display device, dots are provided on at least one of the composite supporting surface of the supporting base material or the porous body surface located on the supporting surface side. shape, linear,
A display characterized in that a plurality of at least one of rectangular and net-shaped recessed gaps are provided to form a substantially uneven gap between the supporting base material and the porous body. It's in the device.

Hereinafter, aspects of the present invention will be described in detail with reference to Examples. Note that, for convenience of explanation, each part is appropriately enlarged and its relative dimensions may not necessarily match the description in the main text.

FIG. 1 is a diagram showing a vertical cross-sectional structure and a power feeding system of an embodiment of a display device according to the present invention. In particular, this example explains the operating principle of the present invention.
A transmissive display device is exemplified as a display format. In the figure, reference numeral 100 denotes a composite body, which is placed on the surface of a supporting base material 200 made of a transparent glass plate on which a first electrode 300 made of a transparent conductive film such as tin oxide is coated. The composite 100 is made of a transparent dielectric material such as cellulose acetate or cellulose nitro, and is made of a porous body 110 having a two-dimensional extent, such as a microporous membrane filter.
A preferably transparent translucent liquid material 400 having a refractive index approximately equal to this (indicated by a dot in the figure)
The surface of the porous body 110 facing the open space 600 is provided with a depression 120 that scatters external light L ₁ , and the opaque ink 150 Furthermore, display electrodes 141 and 142 made of graphite conductive ink and insulated from each other are provided as second electrodes. The electrode 141 is connected to the electrode 300 via the conducting wire 501.
The electrode 142 and the electrode 300 are connected to a DC power supply _VB via a conductive wire 502, and the translucent liquid material 40
0 is electroosmotic in the thickness direction of the porous body 110.

In order to increase the degree of freedom of movement of the liquid material 400 by electroosmosis, as shown in the figure, a large number of depressed gaps 181 are provided on the side of the display electrode 141, or As illustrated in FIG.
The gap 1 between the composite body 100 and the support substrate 200 on which the electrode 300 is attached is formed by providing a large number of depression gaps 182 on the surface of the 00.
80 is substantially provided with unevenness.

For example, the porous body 110 has a refractive index n _d
A microporous membrane filter made of cellulose acetate with a thickness of 1.47 mm, a thickness of 150 microns, an average pore diameter of 0.5 microns forming porosity, and a porosity of about 80% is used. The surface of this porous body 110 is embossed so that the average opening diameter is 15 to 30 microns, the cross section is trapezoidal or triangular, the depth is 10 to 25 microns, and the average diameter of the tip is sharp and sharp within 3 microns. A pattern for displaying, for example, point-like depressions 120 at a density of 100 to 400 per inch, that is, the display electrode 1
41, 142, and then apply opaque ink 150 and conductive ink 141, 142 by offset printing or the like.

The depression gap 181 in the porous body 110 can be formed by an embossing method similar to the method for forming the depression 120. The shape of the depression gap 181 is the same as the depression 120
Similarly, it can be shaped into dots, lines, parallel grids, strips, nets, etc. The depth of the depression gap 181 is made shallow, about 10 to 30 microns, and care is taken so that this processing does not mechanically affect the depression 120. The arrangement interval is selected at a density of about 100 to 400 pieces per inch, as necessary.

The shape of the recessed gap 182 provided on the surface of the support substrate 200 can also be the same as that of 181, but when the support substrate 200 is made of glass or the like, the surface is etched by chemical etching using hydrofluoric acid or the like, sandblasting, or the like. A simple method is to add unevenness to the surface. The necessary electrodes 300 are deposited directly on this uneven surface, as illustrated in the figure. In the case of a transmissive display device, the electrode 300 is transparent as described above, while in the case of a reflective display device, it is coated with a vapor-deposited metal film or the like.

As the transparent liquid material 400, for example, γ-
Methacryloxypropyltrimethoxysilane (n _d
= 1.43) and α-methylnaphthalene (n _d = 1.62)
The refractive index n _d of cellulose acetate is selected to be approximately equal to 1.47, and the refractive index is matched.

In this way, when the porous body 110 is impregnated with the translucent liquid material 400, the composite body 100 becomes transparent. No voltage is applied to the portion corresponding to the display electrode 141 in FIG. Therefore, the liquid impregnation rate of the depressed portion surface 121' is also saturated due to capillarity,
This depression 12 does not cause mismatch of refractive index.
0, a bright transmitted light L _2T is obtained. on the other hand,
The part corresponding to the display electrode 142 has a DC voltage.
V _B is applied. In the material configuration described above, the liquid material 400 electroosmoses toward the negative electrode, so the liquid material 400 electroosmoses toward the electrode 300, which is the negative electrode.

In the conventional configuration, since the porous body 110, which also has a flat surface, is placed on the support substrate 200, which also has a flat surface, there is little flexibility in the destination of the electro-osmotic liquid material 400.
This often caused unstable operation and non-uniform display images. On the other hand, as in this embodiment, since there is a depressed gap 182 and a substantially uneven gap 180 is formed therebetween, the liquid material 400 easily flows into this gap and diffuses. can do.

Due to this movement due to electroosmosis, the depression surface 1
The liquid impregnation rate of 21'' decreases, and air enters the micropores forming the porosity from the open space 600 side.This causes a mismatch in the refractive index, and external light is scattered. The transmitted light L _2B becomes significantly dark. In this state, when V _B is set to zero, the liquid material 400 moves toward the open space 600 due to capillary action, and as shown in the display electrode 141 section, the liquid material 400 moves to the surface of the depressed portion. The liquid impregnation rate is saturated, the refractive index mismatch is removed, and the recess surface 121' returns to a transparent state,
Bright transmitted light L _2T can be obtained. According to the conventional configuration, it is often difficult to supply liquid to the return of the liquid material 400, resulting in non-uniform response time constants, etc. As in this embodiment, the depression gap 18
1,182, an effective liquid reservoir is formed, and the liquid material 400 required for return movement is smoothly supplied from there, so this problem is solved. be done.

According to experiments with the above material configuration, the change in transmitted and projected light by setting V _B to 80 volts and 0 volts, that is, the contrast ratio, was 1:18,
The response time constant j _r for blocking transmitted light to the application of V _B was 17 milliseconds, and the response time constant for returning to the light transmitting state by setting V _B =0 volts was j _d =20 milliseconds.

For reference, in the conventional example in which the depression gaps 181 and 182 are not provided, the contrast ratio is 1:15, and j _r =25.
milliseconds, j _d = 30 milliseconds, and according to the invention the image quality,
Drivability was improved in all aspects, and the uniformity of the displayed image was also good.

In the embodiment shown in FIG. 1, the depression gap was provided on either the porous body side or the support base material side, but it can be provided on both sides, and in this case, the depression gap part can be provided on either the porous body side or the supporting base material side. The degree of freedom of inflow and outflow can be increased.

If the depth of the depressed gap is made extremely deep, a gap may be created in which no liquid material can exist, and if it is too shallow, the degree of freedom will be insufficient. From this point of view as well, the above depth is a recommended value.

FIG. 2 is a longitudinal cross-sectional structural diagram and a power supply system diagram of another embodiment of the display device according to the present invention.

In this embodiment, the electrodes 531 and 532 constituting the first and second electrodes are formed on a supporting base material 5 such as a glass plate.
The porous body 110 is provided with a depression gap 183 as described above on the main surface thereof, and is impregnated with the translucent liquid material 400. A composite body 100 is installed to constitute a transmissive display device. At least a conductive portion of one of these electrodes 531 is configured to be substantially opaque, and a portion of the composite body 100 corresponding to the other transparent electrode 532 forms a display portion.
Now, the electrode 531 is the first electrode, and the electrode 532 is the second electrode.
We will refer to this as the electrode.

In this embodiment, an opaque layer 53 made of black paint such as carbon black is provided on the first electrode 531.
3 is applied thinly to make the area from the conductive part of the electrode 531 to the gap part opaque. Note that when the gap is narrow, the opaque layer 533 in this portion can be removed. Furthermore, if the electrode 531 is formed of an opaque electrode made of a metal such as aluminum or a vapor-deposited film of an opaque substance such as graphite, the opaque layer 531
3 can be removed and this opaque electrode 531 can also be used. The first and second electrodes 531 and 532 are connected to the variable signal power source 700 via conductive wires 571 and 572.
connected to. Similar to FIG. 1, the porous body 110
If the refractive index and the transparent liquid material 400 are selected to have substantially the same refractive index, the composite 100 becomes transparent. Therefore,
When the second electrode 532 is formed of a transparent conductive film such as tin oxide, external light L ₁ is transmitted through this portion of the composite 100, producing transmitted light L ₂ . If the liquid impregnation rate of the surface of this portion on the open space 600 side is controlled, transmitted light control can be performed.

In the configuration of the composite body 100 described above, the transparent liquid material 400 electroosmoses toward the negative electrode. Therefore, the second
As illustrated in the figure, from the variable signal power supply 700, the first electrode 531 is connected with the second electrode 532 as a reference.
A negative voltage pulse V _B with a large amplitude and a positive voltage V _B ' with the same amplitude are applied to. When applying the negative voltage pulse V _B , the second electrode 53 which is the positive electrode
The liquid material 400 electro-osmoses from the second side to the first electrode 531 side, which is the negative electrode, and the liquid impregnation rate of the surface facing the open space of the composite body 100 corresponding to the second electrode 532 decreases, thereby causing light scattering. causes transmitted light
The strength of L ₂ decreases. On the other hand, when a pulse voltage V _B ' of opposite polarity is applied, the liquid material accumulated on the electrode 531 side moves to the electrode 532 side due to surface tension and electroosmosis, and the liquid impregnation rate on the surface of the composite 110 decreases. Since the light increases and a transparent state is formed, transmitted light L ₂ of large intensity is obtained.

In the above operation, due to the presence of the depressed gap portion 183, a substantially uneven gap 180 is formed between the porous body 110 and the support base material 540, which prevents the movement of the liquid material 400 due to electroosmosis. Forms a liquid reservoir. Therefore, since the liquid material 400 flows in and out through the gap 180, the degree of freedom of liquid movement is improved, and uniform and stable operation can be realized with a fast response speed.

In the above examples, a translucent dielectric material was used as the porous body, but the translucent dielectric material was colored by mixing dyes or pigments, and on the other hand, a translucent liquid material was used as the liquid material. By using it, it can also be used as a reflective display device.

As described above, the present invention provides a display device utilizing electroosmosis, in which the surface of the front support base supporting the composite or the surface of the porous body located on the support surface side is provided. A plurality of recessed gap portions are provided on at least one of the surfaces of the porous body, and a substantially uneven gap is formed between the supporting base material and the porous body, and the liquid material is produced by electroosmosis. This device increases the degree of freedom for movement of the display device, improves response speed, contrast ratio, and display image quality, and is extremely useful industrially as a wide-screen display device, unlike liquid crystal display devices.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the display device of the present invention, and FIG. 2 is a sectional view showing another embodiment. 100...Composite, 110...Porous body, 12
0... Depression portion, 200,540... Support base material, 1
41,142,300,531,532...electrode, 180...gap, 181,182,183...
... Depression gap, 400 ... Transparent liquid material, 60
0...Open space, 700...Signal power supply.

Claims (1)

[Claims] 1. A display structure including a porous body made of a membrane or plate-like dielectric material having a large number of fine openings exposed on at least one surface thereof is impregnated with a liquid material, and the display structure is impregnated with a liquid material. A first electrode is placed between the porous body and the supporting substrate, and a second electrode is placed on the supporting substrate surface so that one surface portion facing the open space faces the open space. Located either between the porous body and the support base material or on the surface of the porous body opposite to the support base material, and corresponds to at least one of the first and second electrodes. the porous body has a display section on the surface side facing the open space, and means for applying a signal voltage between the two electrodes; In a display device that controls external light by controlling the liquid impregnation rate of the display section by movement of the liquid material relative to the mass, the composite support surface of the support base material or the porous surface facing the support surface is provided. A display device characterized in that a large number of concavo-convex portions other than display recessed portions are provided on one or both of the body surfaces.