JP2008020828A - Large-sized display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large-sized display device, wherein a large number of persons people can simultaneously watch it on a building wall or at a sports facility, enormous electric power will not be consumed for displaying at high luminance in a bright situation, and a reflection type and a light emission type are switchable. <P>SOLUTION: The thin large-sized display device can be used under all kinds of environment, functioning as a reflection type under a bright environment and as a transmission type by the use of backlight under a dark environment, by a new cell configuration and a drive mode to make the optical transmission properties change by moving fine particles, by a lateral electric field in a direction perpendicular to the optical axis so as to quantitatively change the dispersion state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention can be used as a reflective type or a transmissive type by arranging a number of elements that modulate light transmission by movement of fine particles dispersed in a liquid or gas body by a lateral electric field and providing a light source behind a white diffusion plate. The present invention relates to a large display device characterized in that it can be used.

Large display devices are active indoors and outdoors, such as advertisements on wall surfaces of buildings, messages at sports facilities, scores, and competition conditions. However, these are either a light emitting type or a reflective type, and a large-sized display device for day and night that can be used as a reflective type when it is bright in the daytime and used as a light emitting type when it is dark at night has not been developed. Conventional large outdoor display devices use high-brightness LEDs, discharge tubes, incandescent bulbs, etc. exceeding 5000 cd / m 2 so that the display can be seen even in the daytime under strong sunlight. Electric power was required, and the thickness and weight of the display device increased, resulting in an increase in system price. On the other hand, the reflection type mainly uses magnetic reversal display, but there are limitations such as that it is impossible to display moving images, high-definition display is difficult, and that front lighting is necessary at night. A large-sized display device that can be used both day and night has a significant advantage in that it is brighter and easier to see and can save electric power when it is used in a reflective type during the day when the weather is nice. There is a merit that it can be used in a light emitting type when it is dark and the use efficiency of the display device is improved. Therefore, a large-sized display device that can be switched between a light emitting type and a reflective type is desired.

There has been proposed a lateral electric field type particle movement display method in which light transmittance is changed by moving and accumulating fine particles dispersed in a transparent liquid in a horizontal direction with respect to a display surface (Patent Documents 1 to 8). As shown in FIG. 1, a fine particle dispersion system is sandwiched between the transparent substrate 1 provided with the transparent counter electrode 30 and the transparent substrate 2 provided with the collect electrode 31. It is characterized in that the light transmittance transmitted through the cell is changed depending on whether a voltage is applied to be deposited on the counter electrode 30 or accumulated on the collect electrode 31 having a small area. That is, when the fine particles are black light-absorbing, the dark state is obtained in (A) and the bright state is obtained in (B).

Another configuration is shown in FIG. Here, the pair of electrodes are on the same substrate, and in the same way as in FIG. 1, a bright state is obtained when particles are deposited on a transparent counter electrode having a large area and a dark state is obtained when particles are deposited on a collect electrode.

Both FIG. 1 and FIG. 2 are provided with electrodes having small and large areas in a pixel, shielding light when depositing fine particles on a large area electrode, and transmitting light when deposited on a small area electrode. It is. It is assumed that it is mainly used for reflection, and the panel configuration has a display electrode surface parallel to the display surface, and since an electrode is provided in the pixel, a decrease in aperture ratio (light loss) is avoided. I couldn't. In addition, since there are large and small electrodes in the display area, it is difficult to achieve sufficient contrast, and since a transparent electrode with a large area is required, when the display layer is laminated and colored, the transparent electrode There was a difficulty in reducing the transmittance due to the inevitable loss of light. These proposed display devices are assumed to be reflective display devices such as electronic paper, and their application to a large-sized display device having a much larger pixel size and day / night use has not been considered at all.

On the other hand, in the conventional cell configuration, if particles of the same type with different polarity are mixed, the particles are attached to both large and small electrodes, and the dispersion system used is a dispersion system with only a single polarity to reduce the contrast. It required strict coordination and management to become.

JP 49-24695 A USP 5,745,094 JP 9-2111499 A JP2001-201770 JP2004-20818 Special Table 2005-500572 JP-A-2002-333643 JP2003-248244

Advertising display on building walls, messages / scores / competition status / close-up display at indoor / outdoor sports facilities, messages / advertising display at terminals, event venues and buses, advertising vehicle wall displays, hotels, department stores, public halls Applications of large display devices used indoors and outdoors, such as large advertisements / TV displays, etc., are widespread. Also, the size is actually in operation from several meters square to several tens of meters square, and if the facility cost and power are reasonable, a larger display is required. In addition, there is nothing that can be shared between the light emitting type and the reflective type so far, and it is exactly what the market is waiting for, and its utility value is very high.
The present invention is a review of the previously proposed transverse electric field type particle movement display method, and realizes monochrome, multi-color, and full-color display with little optical loss based on a new electrode configuration and display mode. It can be applied to a large display device.

    In order to solve the above problems, the present invention uses a transverse electric field as in the prior art, but the amount of particles dispersed in the cell is not forcibly deposited on one of the two electrodes. We propose a new display mode based on the idea of modulating the transmittance and controlling the transparency, eliminating the need for a transparent planar electrode that occupies most of the cell. The bright state is achieved by making the dispersed state of the particles the maximum opaque state and collecting the particles locally to reduce the amount of dispersion. The electrode shape can be reflected only by using a pair of linear electrodes. In particular, a particularly important aperture ratio has been remarkably improved, and this has enabled a display device for both reflection and transmission.

In the basic cell of the present invention, as shown in FIG. 3A, a cell 4 is constituted by a partition wall 3 provided between two transparent substrates 1 and 2 such as glass and plastic, and fine particles 5 are dispersed in the cell. The dispersion system 7 is filled, and a voltage can be applied between the electrodes 6-1 and 6-2 provided at the lower part of the partition wall 3. As shown in FIG. 3A, in the state where the black light absorbing fine particles 5 such as carbon black are dispersed in the cell 4, the light incident from the substrate 2 is black if the concealing force of the fine particles 5 is sufficient. Become.

When a DC voltage is applied between the electrodes 6-1 and 6-2 as shown in FIG. 3B, when the fine particles 5 are positively charged, they are accumulated on the negative electrode 6-1 by Coulomb force. In this case, except for the particle accumulation part in the cell 4, there is nothing to block light and it is transparent. Here, if a DC voltage pulse or AC voltage of opposite polarity is applied between 6-1 and 6-2, the fine particles on 6-1 will diffuse and distribute in the cell 4 leaving the electrode, and the cell 4 will become opaque again. . Thus, the transmittance of the cell can be changed by changing the amount of dispersed particles in the cell 4 (and hence the amount of particles accumulated on the 6-1 to 6-2 electrodes), and the accumulated particles are also dispersed particles. In addition, the display has a memory property in order to maintain the state after the voltage is turned off. The dispersion system 7 consists of a gas or a transparent liquid in which fine particles are dispersed. In the case of a liquid, the movement of the particles is called electrophoresis. Of course, one or both of the linear electrodes 6-1 and 6-2 may be provided on the upper part of the partition wall. The electrode can be composed of a thin film obtained by depositing a metal such as aluminum, chromium, or gold by vapor deposition or sputtering and patterned by photolithography, or a conductive thick film provided by printing a conductive paint or ink jet drawing.

When the fine particles are accumulated on the electrode, it is not preferable that the fine particles remain fixed on the substrate surface because the light transmittance in the bright state of the cell is inhibited. Accordingly, it is desirable that the inner surface of the substrate of the cell portion is coated with a fluorine compound or the like so as to prevent the fine particles from sticking. When the dispersion medium is a liquid, the specific gravity of the fine particles and the liquid is preferably as close as possible.

In the present invention, the dispersed state is not only a colloidal state in which fine particles are stably and uniformly dispersed in the liquid regardless of the specific gravity due to Brownian motion, but also some or most of the particles are loosely attached to either the inner surface of the substrate 1 or 2. It includes the state that has been. Further, the fine particles do not need to be one kind, and various kinds of fine particles may be mixed in order to optimize the optical characteristics, and the charging polarities need not be the same. The fine particles 5 are usually light-absorbing, but it is also possible to use a white-reflective material such as titanium dioxide. In this case, the incident light is scattered and reflected by the fine particles when the fine particles are dispersed in the cell 4. The transmitted light attenuates depending on the degree.

The moving speed of the fine particles determines the response speed of the display, but the moving speed of the particles depends on the viscosity of the dispersion medium, the charge amount of the particles, the electric field strength, etc., and when the viscosity is low and the charge amount and the electric field strength are large, the fast response is It becomes possible. In a large display, the pixel size naturally increases, and when a pixel is enlarged with an electrode configuration as shown in FIG. 3A, it is necessary to apply a high voltage, which increases the burden on the driver circuit. In order to secure a sufficient electric field strength even at a low voltage, it is desirable to use a comb electrode as shown in FIG. 4A or a vortex electrode as shown in FIG. In this case, in the bright state of the cell, that is, in the state of particle accumulation on the electrode, a linear opaque portion is generated. However, if the width of the particle accumulation portion is sufficiently narrow compared with the width between the electrodes, the light transmittance of the cell is not significantly reduced. Sufficient brightness and contrast can be obtained.
In the case of a comb-type or vortex-type electrode cell, a monopolar particle system should be used for the dispersion system. In the present invention, for convenience, an electrode for collecting particles is called a drive electrode, and the other electrode is called a common electrode. In FIGS. 4A and 4B, reference numeral 6-1 denotes a drive electrode that accumulates particles, and 6-2 denotes a common electrode that does not accumulate particles. The drive electrode may be either transparent or opaque, but the common electrode is more preferably a transparent electrode such as ITO (indium tin oxide) because the transmittance in the bright state can be improved. An electric field strength of about 0.2 to 2 V / μ is usually suitable for particle movement. When the distance between the drive electrode and the common electrode is 50 μm, it corresponds to a voltage of 10 to 100V. If the distance between the electrodes is reduced, the driving voltage is lowered, but it is disadvantageous in terms of display brightness and contrast. Although it depends on the application, it is appropriate that the distance between the electrodes is about 20 to 100 μm. If the drive electrode is opaque, the electrode width should be less than the width of the integrated particle layer. About 2 to 10 μm is desirable in terms of ease of manufacture and mechanical strength. The transparent common electrode may be somewhat wide. Although not shown in FIG. 4, the insulating partition 4 is provided on the outer periphery of the comb or vortex electrode so as not to deteriorate the aperture ratio, and corresponds to a comb or vortex in order to prevent an increase in drive voltage. It is necessary not to cover the electrode part inside the cell.

FIG. 5 shows a basic cell for color in which three cells as shown in FIG. 3 are stacked in order to enable full color display. However, the three layers of fine particles 5 are C (cyan), M (magenta), and Y (yellow). If Y and M particles are in a moderately dispersed state and C particles are in an electrode-integrated state, that portion is R (red), and if C and M particles are in a moderately dispersed state and Y particles are in an electrode-integrated state, the same subtractive color mixture To B (blue). In addition to the C, M, and Y panels, a fourth cell that can be modulated into white-black in order to block light more completely may be added to form a four-layer configuration. Further, the cell stacking order can be arbitrarily selected.

In a display device in which a large number of cells are stacked, attention should be paid to interface reflection. Interface reflection always occurs at interfaces having different refractive indexes. In the three-layer stacked display cell of FIG. 5, each layer is composed of many layers (two substrates, a dispersion medium, and an adhesive layer), so that each layer is as transparent as possible, and the refractive index is as high as possible. It is important to construct with equal materials to reduce unwanted interface reflections.

Further, in the three-layer stacked display device of FIG. 5, when the thickness of the intervening substrate is thicker than the pixel size, the viewing angle is limited when viewed by reflection. In FIG. 5, when viewed from the direction beyond the angle θ from the substrate normal, the reflected light does not pass through all three layers, so that the correct color cannot be seen. If the pixel size is W, the cell thickness h for one color (the total of the upper substrate, the dispersion system, the lower substrate, and the adhesive layer) is h = W / (3 × tan θ). At θ = 60 degrees (tan (θ) = 1.73), h = W / 5.19, and when the pixel size is 1 mm, h≈0.19 mm, θ = 80 degrees (tan (θ) = 5.65) In this case, h≈0.059 mm. That is, in the three-layer type reflective display device, it is difficult to realize a reflective display with an excellent viewing angle unless the intervening substrate is made as thin as possible. This point transparent substrate is advantageous in view angle characteristics because of its thinness.

FIG. 6 shows an electrode extraction configuration of the cell of FIG. 5, which has three drive electrode terminals for C, M, and Y and corresponding common electrodes, a light source lighting electrode such as an LED, and a common electrode, When the common electrodes are combined into one, there are a total of five terminals. In the example of FIG. 6, the electrodes of the C, M, and Y cells are provided on the inner surface of each upper substrate, and the electrode takeout portion slightly protrudes from the seal. The electrode substrate 15 provided with wiring is hollowed out at the protruding portion, and is electrically connected to the corresponding electrode substrate terminal using a conductive resin 16 or the like. If a film having a thickness of about 20 to 100 μm is used for the substrate, it is easy to form a thickness of several mm even if the backlight unit is included.

FIG. 7 shows a full-color element with pins in which pins are provided at five terminals of the cell of FIG.
By arranging a large number of such cells in an XY matrix, it is possible to construct a full-color super-large display system for both reflection and light emission that is reflective when the light source is not lit and light-emitting when illuminated.
Although FIG. 5 shows one pixel cell, it is needless to say that a panel with multi-element pins using a multi-pixel panel is possible.

A large display device has a screen size of about 100 inches and is not particularly limited, but is assumed to be 1000 inches and a display capacity of about VGA (640 × 480 pixels) to full HD (1920 × 1440 pixels). The pitch is about 3 mm to 32 mm for VGA and about 1 mm to 11 mm for full HD.

FIG. 8 shows an example in which a large display device is configured by arranging a large number of basic panels 26 having a large number of pixels vertically and horizontally. In the present invention, the vertical direction is called a column and the horizontal direction is called a row. Therefore, in this example, a case where a plurality of panels each having 5 columns and 10 pixels are arranged vertically and horizontally is shown, and the electrode configuration is shown by 3 columns and 2 rows in FIG. 9A. 9B to 9D are front views of the electrode substrate 15 used in this panel. Although the common electrode is common in the row direction, the drive electrode is extended to the left end, for example, by a thin line for each pixel. Accordingly, 10 drive electrodes 10 × 5 = 50 and 5 common electrodes are arranged at the left end from one panel of FIG. There are the following four methods for driving each panel composed of these 50 pixels. In the case of (1) simple matrix, (2) static (3) two-terminal active matrix, (4) three-terminal active matrix, and (1) simple matrix, a threshold value characteristic is required for the distributed system, and the drive electrode of each column Ci is connected inside or outside the panel and driven as a matrix of 10 columns × 5 rows (not shown). The electrode terminal at the panel end and the corresponding terminal on the electrode substrate 15 provided perpendicular thereto are connected by a wire bond, an anisotropic conductive film, a conductive resin or the like. FIG. 9B shows an example in which static driving is performed. The driving electrodes of all the pixels are connected to the output of the LSI driver 20, and the five common electrodes are connected to the common terminal of the LSI 20. FIGS. 9C and 9D show examples in which an active matrix is formed on the side electrode substrate 15 with 2-terminal non-linear elements or 3-terminal TFT elements, respectively. Although the example in which the panel drive circuit is configured on the side electrode substrate 15 has been described above, the electrode substrate 15 is simply used as an electrode extension of the panel and connected to the drive circuit provided on the back side of the panel or the backlight. It is also possible to drive. Connection of power and signals between the panels is made by a connector (not shown) provided on the drive circuit board 27 on the back of the panel.
In a full-color panel, the number of drive electrodes increases three times, so that electrode processing becomes complicated, but basically the same configuration as described in FIG. 9 can be applied.

In both monochrome display and color display, it is necessary to devise in order to increase the whiteness as much as possible particularly in the case of using the reflection type. FIG. 10 shows a part of a large display device. When the gap between pixels is s and the pixel pitch is W, it is desirable that s is the same from the viewpoint of display uniformity, and (W−s) The aperture ratio indicated by / W is desired to be as high as possible (≧ 0.8) in order to obtain excellent brightness and contrast. When the pixel pitch is 3 mm, it corresponds to s ≦ 0.6 mm, so it is necessary to process the four sides of each panel with s / 2 ≦ 0.3 mm. In the case of the panel of FIG. 8, it is necessary to form 10 drive electrodes and 1 common electrode of pixels in one row within the width s. However, when the pixels have a pitch of 3 mm, the line and space is made less than 30 μm. it can. In the case of a single pixel element as shown in FIG. 7 where W = 10 mm, it is easy to configure it to 0.5 mm or less including the seal and the electrode substrate, so that the aperture ratio ≧ 90% is easy. The optical characteristics of the s portion between pixels are important. When used in the light emitting type, black opaque is desirable, but when used in reflection, the whiteness is reduced. On the other hand, if white opaque is used, in the case of reflective display, the black portion is deteriorated and the color purity is lowered, but the whiteness is excellent in the white display region. It should be determined according to the aperture ratio, display contents, and the frequency used for reflection and transmission.

In the panel as shown in FIG. 8, each pixel is surrounded by a partition wall to constitute a cell. The reason why the particles are confined in the cell is to prevent the fine particles from moving to the adjacent cell and maintain the particle concentration uniformity in the display panel surface. Instead of confining the fine particles with the partition walls, the fine particles may be confined in the capsule. An advantage of confining the fine particles in the capsule is that the fine particle dispersion system as a liquid or fluid powder can be solidified and easy to handle in application to the display element surface, bonding of the upper and lower substrates, and the like.

FIG. 11A shows an example in which one pixel is composed of 3 × 3 capsule particles, and FIG. 11B shows an example in which capsule particles are arranged in accordance with the pitch of the comb-shaped electrodes in FIG. 4A, for example. Show.

FIG. 12 shows a cross-sectional view of a color panel in which C, M, and Y capsule particles are laminated. In the case of forming a stacked cell or panel, it is sufficient to sequentially stack each color of a substrate provided with electrodes on which a capsule is laid, so that the number of substrates can be easily reduced, and a cell advantageous in view angle characteristics can be configured.

The walls of the capsule particles 10 are made of a transparent inorganic or organic thin film, and the dispersion system in the capsule particles is obtained by dispersing light absorbing or reflecting fine particles in a gas body or a transparent liquid. The gap between the capsule particles and the so-called substrate is filled with a transparent binder resin, adhesive, gel or the like. The capsule particle shape is not limited to a sphere. Further, even if spherical capsule particles are used, the light modulation effect can be increased by using them while being sandwiched between substrates as shown in FIG. 11B.
In the present invention, the cell refers to a region surrounded by partition walls or one capsule particle. A pixel may consist of one cell or a number of cells.

As is clear from the above description, in the light modulation element of the present invention, the light transmittance does not change in the gaps between the partition walls or the capsule particles, so it is desirable that the width of this part in the light transmission direction is as narrow as possible. On the contrary, if this part is transparent, light is lost and the light blocking power of the light modulation element is reduced, so that pure black cannot be obtained. Therefore, it is desirable to make this part black light absorbing or light reflecting. A black matrix or a light reflecting film may be provided so as to cover the regions of the substrates 1 and 2 where light leakage occurs and, if necessary, the particle accumulation portion.

FIG. 13 shows an example of the manufacturing process of the active matrix basic panel array.
A metal film such as aluminum or tantalum is formed on the transparent substrate by vapor deposition or sputtering, and column electrodes are formed by photoetching or the like as shown in FIG. Next, this column electrode is anodized to form an oxide film on the surface. Next, a metal film made of aluminum, tantalum, chromium, gold, or the like is formed, and a comb-shaped drive electrode 6-1 is formed by photolithography as shown in FIG. 13B. In this way, the MIM 2 terminal non-linear element is formed at the intersection of the drive electrode and the column electrode. Next, a transparent insulating film is formed, and at least the comb-shaped electrode portion is removed to avoid an increase in driving voltage. Next, an active matrix array substrate can be configured by forming the row electrode line R with the same material as the drive electrode and then forming the comb-shaped common electrode 6-2 with a transparent electrode such as ITO. If the tip of the comb-shaped common electrode is overlapped with the horizontal bar of the drive electrode via an insulating layer, it functions as a pixel parallel capacitor. Next, another substrate on which the capsule particles are spread almost uniformly over the substrate size is overlaid on the array, and the capsule particle layer is transferred to the array substrate. Of course, the capsule particles may be spread directly on the array substrate. Thereafter, for example, bumps are formed on the row and column electrodes at the substrate edge, a sealing resin and a spacer are provided so as not to cover the bumps, and an array substrate in which capsule particles are provided on the lower substrate 2 having the same size as the transparent substrate 1 is adhesive. The first color panel is completed. Similarly, a laminated panel 24 as shown in FIG. 12 is formed by superimposing substrates of the second and third colors. The arrangement positions of the capsule particles are aligned so as to enter between the combs of the comb-shaped electrode as shown in FIG. In addition, it is desirable that the electrode terminal positions of the second layer and the third layer are slightly shifted from the first layer so that the positions do not overlap with each other when wire bonding is performed later.
For example, the laminated panel is attached to a backlight unit 17 provided with a light source 13 such as an LED, and connected to corresponding terminals of the electrode substrate 15 provided on the row and column terminal surfaces in advance by wire bonding or the like. The column terminals are collected on the back surface of the backlight unit, and are connected to the drive circuit board 27 by anisotropic conductive resin or the like. The electrode substrate 15 is, for example, a thin and flexible film provided with a copper foil, and is firmly attached to the side surfaces of the lower substrate 2 and the backlight unit 17 in the vertical direction from the panel. Finally, it is desirable that the wire bond part is pasted with a protective film or molded with resin. The row and column electrodes may be connected to the electrode substrate with a conductive resin or the like instead of the wire bond. In addition to the anodic oxide film, the two-terminal element may be provided with, for example, a paste in which zinc oxide or the like is dispersed in a resin.

FIG. 14 shows one pixel portion of an active matrix panel in which a TFT is introduced into each pixel. The TFT may be configured below the row electrode (gate electrode) Ri, the source electrode may be connected to the column electrode Ci, and the drive electrode 6-1 may be connected to the drain electrode. For example, the common electrode 6-2 is configured to extend under the drain electrode line and Ci through an insulating film, and may be taken out as one terminal from the peripheral portion.

FIG. 15A shows a side view of the completed basic panel, and FIG. 15B shows a perspective view. If the pixel pitch is 3 mm, and each row and column is 100 pixels, the basic panel size is about 30 cm square, the number of column (drive) electrodes is 300, and the number of row (common) electrodes can be shared by 100 colors. A connector 28 is provided on the circuit board 27 so that it can be electrically connected to the peripheral panel. As shown in Fig. 8, if 12 such horizontal panels are stacked and 9 vertical panels are stacked, the reflective and transmissive shared size is suitable for use in public facilities of 3.6m x 2.7m (diagonal approximately 177 inches). It becomes a full color display system.

As a backlight of a large panel as shown in FIG. 8, a fluorescent tube or an EL surface light source can be used in addition to an LED of a direct type or an edge light configuration.
If the basic panel as shown in FIG. 8 is manufactured with a film, even a three-layer stacked color display can be configured with 1 mm or less. The drive circuit is made of FPC made of polyimide, copper foil, etc., and it is not impossible to construct a color panel with a built-in backlight as well as a reflective monochrome or color panel with a built-in backlight. It is easy and can be applied in various ways to a concave advertisement display installed in a train, a curved display panel along the outer surface of a car, and the like.

If the seal width around the panel and the spacer width in the panel are made 0.2 mm or less, the aperture ratio: (W−s) / W≈87% and 80% at 0.3 mm can be achieved. Although the dispersion system has been described as a microcapsule, it can of course be a partition type. If microcapsule particles having a diameter of about 50 μm are used, the comb-shaped drive electrode pitch P shown in FIG. 13B is about 100 μm, and the capsule particle ends are the drive electrodes and common electrodes as shown in FIG. It is desirable to be placed on top. The substrate 1 and the substrate 2 may be either glass or plastic. The lower substrate 2 may be replaced by the backlight unit 17 itself made up of a white diffuser, white LED, reflector or the like. When constructing a large panel by integrating the basic panels, the dimensional accuracy of the basic panels is critical. Therefore, it is necessary to strictly manage the dimensions such as the substrate size used for the panel, the bonding accuracy, and the seal width. Slight protrusions on the four sides are also undesirable. Therefore, after installing the backlight unit to the specified dimensions, the four sides are polished if necessary, and instead of using the side electrode plate, a thin and highly accurate electrode film is printed on the side of the backlight unit in advance by printing, vapor deposition, sputtering, etc. It is also a method of improving the accuracy to form (in some cases, a dent corresponding to the electrode film thickness is provided in advance).
FIG. 16 shows a simple model in which the effect of reducing the transmittance of the particle accumulation portion is estimated using a panel using comb-shaped electrodes as an example. Assuming that all the dispersed particles dispersed at a concentration at which sufficient contrast can be obtained are accumulated on the upper substrate, the thickness of the particle layer is d and the width of the pixel is W. Assuming that all the dispersed particles are accumulated on the drive electrode and the particles are accumulated in a semicircular shape on one comb-shaped drive electrode, the width is x. FIG. 16 (C) shows the result obtained by the simple formula shown in FIG. 16 (B) for the panel as described in FIG. Here, the aperture ratio ignores the influence of the seal portion. As expected, the larger the electrode pitch p, the smaller the decrease in transmittance. In any case, it is advantageous to use particles with strong coloring power (d is small), and x is small for particles with high hiding power. It can be seen that if an opaque drive electrode is used, it is desirable to make the width as narrow as possible so that it is not limited by the electrode width.

Glass or plastic film can be used as the transparent substrate of the light modulation element used in the present invention. Particularly, since the film is thin, it is advantageous in that the viewing angle can be widened in a laminated panel used in a reflection type, and it can be continuously mass-produced by roll-to-roll It has characteristics.
FIG. 17 shows an example of producing a film cell or panel by roll-to-roll. A roll film in which an electrode pattern has been formed in advance is supplied from the upper roll, and the dispersion system is applied in the form of capsule particles. On the other hand, the two substrates are aligned and bonded so that no air bubbles remain between the lower film substrate provided with a sealing agent such as UV seal resin for punching holes for electrode extraction and printing or inkjet drawing. It is fixed. It is possible to produce a plurality of individual cells or panels for one color by cutting them by punching or the like.

Film materials include vinyl polyethylene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polystyrene, fluororesin, polyamide polycarbonate, polyethylene terephthalate, polyamide nylon, heat-resistant engineering plastic, polyimide, poly Various materials such as sulfone, polyether sulfone, polyphenylene sulfide, polyether ketone, and polyetherimide can be used.

In order to achieve a transmittance modulation of 1000: 1 or more with the light modulation element of the present invention, it is necessary to suppress the light transmittance of the cell in a fine particle dispersed state including the partition wall to less than 0.1%. This can be easily achieved by selecting the concentration of fine particles contained in the cells or capsules while preventing light from passing through the gaps in the capsules. In the reflection type exclusive panel, light passes through the cell twice, so the particle concentration may be ½.

The material used for this invention is described.
As described above, it is desirable that the fine particles have as high a hiding power as possible. For black and white, carbon black, pigment black, graphite or the like, or a so-called toner in which these are embedded in a resin can be used. C, M, Y fine particles include various organic pigments such as azo, phthalocyanine, nitro, nitroso, etc. used in printing ink, color copier toner, ink jet ink, iron oxide, cadmium yellow, and cadmium red. Various things such as inorganic pigments can be used. Y color fine particles such as Hansa Yellow, Benzidine Yellow, and Quinoline Yellow, M Color Fine Particles such as Pigment Red, Rhodamine B, Rose Bengal, and Dimethylquinacridone, and C Color Fine Particles such as aniline blue, phthalocyanine blue, and Pigment Blue K are black. As the fine particles, C, M, and Y fine particles may be mixed and used. The fine particles are not limited to simple substances but may be capsule fine particles containing dyes, pigments and some color materials together with resins and liquids in order to optimize chargeability and color tone. Particles having an anisotropic shape such as a spherical shape, a needle shape, a rod shape, and a scale shape can be said to be suitable when a linear electrode is used as in the present application. This is because particles are oriented in all directions in a dispersed state, and have a high light absorption ability and light scattering ability. Needle-like and rod-like particles are likely to be arranged in parallel to the electrode when they are accumulated on the electrode, and easily overlap each other in the shape of a scale. This is because both the absorption or scattering cross section is reduced and the contrast is easily increased. The size of the fine particles is desirably about 5 nm to 5 μm. Fine particles can be surface-modified by surface coating at the atomic or molecular level, or can be charged and have good dispersibility using a dispersant, surfactant, etc. Must be adjusted to be redistributed. It is important to improve the chargeability of the particles and to ensure the stability of the charged state even under strong light irradiation.

Various known methods can be applied to the method for producing the microcapsules used in the present invention. That is,
(1) Typical interfacial polymerization methods and in-site polymerization methods (interface reaction methods) as chemical methods
(2) Typical submerged drying method, coacervation method, melt dispersion cooling method as physicochemical methods (3) Typical spray drying method, dry mixing, orifice method, etc. as mechanical methods. Microcapsule film materials include gelatin, gum arabic, melamine resin, urea resin, formalin resin,
Various polymer materials such as urethane resin, polyurea resin, amino acid resin, and melamine formaldehyde resin can be used. A microcapsule having a gas body is generally referred to as a microballoon.

Microballoons with built-in microparticles can be manufactured by: (1) introducing a diazo component that generates nitrogen gas or the like into the microparticles by irradiation with ultraviolet light or adsorbing the microparticles on the surface, and then covering the microparticles with a polymer resin. , Irradiate ultraviolet light to generate gas inside to form microcapsules with built-in microparticles (2) Encapsulate particles together with bubbles (3) Liquefaction of dry substances such as dry ice at low temperatures Alternatively, a method of solidifying fine powder and encapsulating with fine particles at low temperature can be used. When the dispersion system 7 is a gas body, since there is little resistance to the movement of fine particles, a display panel with high-speed response becomes possible.
Since it will be exposed to strong light for outdoor use, the materials used (transparent substrates, adhesives, fine particles, dispersion media, capsule materials, binder resins, partition materials, electrodes, etc.) are particularly light and resistant. It is necessary to use one that has excellent high temperature properties. The panel surface should be reinforced with an acrylic plate or with a built-in UV absorber or coated on the surface. An antireflection film is also useful for improving visibility.

When the medium is liquid, various types of highly insulating solvents such as silicon-based, petroleum-based and halogenated hydrocarbons can be used.

As the non-linear element material, a semiconductor such as MIM, a chalcogenite compound, zinc oxide, etc., in which a thin film such as Ta or Al is anodized and sandwiched between the other metals can be used, and as a TFT material, a-Si, a-InGaZnO Inorganic semiconductors such as polysilicon and low molecular and high molecular organic semiconductors such as pentacene, polyfluorene, and polyhexylthiophene are used.

The present invention has the following effects.
In the first aspect of the invention, a cell is formed by sandwiching a dispersion system in which fine particles are dispersed between two transparent substrates, and the fine particles are moved by a lateral electric field parallel to the substrate surface. In the display device in which the light transmittance in the direction perpendicular to the substrate of the cell is changed, the lateral electric field is formed by a pair of linear electrodes provided in the cell, and light is changed by changing the dispersion amount of the fine particles in the cell. This is a large display device that features a large number of two-dimensionally assembled cells configured to change the transparency and is provided with a backlight on the back. It can be used for both reflection and transmission in a thin configuration with full color display. In addition to having unprecedented features, it can be used for reflection in the daytime, so it can demonstrate the advantage of significantly reducing power consumption.

FIG. 2 is a transverse sectional view showing the principle of a conventional horizontal electric field particle movement type display device. FIG. 8 is another cross-sectional view showing the principle of a conventional horizontal electric field particle movement type display device. These are the cross-sectional views which show the principle of the horizontal electric field particle | grain movement type display apparatus of this invention. (A) is a principle explanatory view of the display device of the present invention. (B), (C) is a front view of an electrode configuration. These are the cross-sectional views of the color display element of this invention. Shows the electrode extraction configuration of the color element of FIG. 5, (A) is a cross-sectional view, (B) is a front view. 1 shows a pinned color element of the present invention. A diagram of large panels assembled from basic panels vertically and horizontally The electrode configuration (A) of the basic panel in FIG. 8 and the electrode substrate configuration diagram ((B) to (D)) Diagram showing aperture ratio Sectional view of a cell using capsule particles of the present invention Sectional view of a color panel in which C, M, Y capsule particles of the present invention are laminated Array manufacturing process diagram when the unit panel of FIG. 8 is configured with a two-terminal active matrix. Front view of one pixel unit when the unit panel of FIG. Sectional view (A) and perspective view (B) of the basic panel of FIG. Is an estimate of the effect of reduced permeability of accumulated particles Process drawing for producing cell or panel of the present invention by roll-to-roll

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent upper substrate 2 Transparent lower substrate 3 Partition 4 Cell 5 Fine particle 6-1 Drive electrode 6-2 Common electrode 7 Dispersion system 8 Binder 9 Spacer
10 Capsule Particle 11 Adhesive 12 White Diffuser 13 Light Source 14 Reflector 15 Electrode Substrate 16 Conductive Resin 17 Backlight Unit 18 C1, C2, C3,... Column Electrode Terminal 19 R1, R2, R3,. Terminal 20 LSI driver 21 Two-terminal element 22 TFT element 23 Interlayer insulating film 24 Multilayer cell 25 Electrode pin 26 Panel 27 Circuit board 28 Connector 29 Wire 30 Counter electrode 31 Collect electrode

Claims (12)

A cell is formed by sandwiching a dispersion system in which fine particles are dispersed in a transparent medium between two transparent substrates, and the fine particles are moved by a lateral electric field parallel to the substrate surface, so that the substrate of the cell In the display device that changes the light transmittance in the vertical direction, the lateral electric field is formed by a pair of linear electrodes provided in the cell, and the light transmittance is changed by changing the dispersion amount of the fine particles in the cell. Large-sized display device characterized in that a large screen is formed by assembling a large number of two-dimensional basic cells composed of one pixel or multi-pixel basic panels. 2. The display device according to claim 1, wherein a light source is provided on a back surface of the basic cell or the basic panel. 3. The display device according to claim 1, wherein the pair of linear electrodes has a comb shape or a spiral shape. In Claims 1 to 3, the fine particles are cyan, magenta, and yellow, respectively, and at least three layers are laminated to form a cell, and the transparency of each color is independently set. A full-color display device characterized by being configured to be controllable. 5. A large display device according to claim 1, wherein each pixel of the basic cell or the basic panel is configured to be driven statically or active matrix. 6. A basic panel having m pixels in the column direction and n pixels in the row direction is arranged in M columns and N rows in the row direction, and the total number of pixels is m * M * n * N. The display device is configured so that the electrode of each panel extends outside the panel in a direction perpendicular to the panel and is driven by a circuit board provided behind the panel or provided in a direction perpendicular to the panel A large display device characterized by being configured to be driven by an electrode substrate. 7. The light source according to claim 2, wherein when the outside of the display device is bright, the light source is turned off to display a reflection type, and when the amount of external light incident on the display device becomes smaller than a specified value, the light source is turned on to emit light. Large-sized display device for both reflection and transmission, characterized in that it is configured to function as a type display device. 8. A display device according to claim 1, wherein the dispersion medium in which the fine particles are dispersed is a liquid or a gas body. 9. A display device according to claim 1, wherein the cell is formed by a partition wall provided between the substrates, or is formed by capsule particles containing a dispersion system. 10. A display device according to claim 1, wherein the fine particles have a needle-like, rod-like or scale-like anisotropic shape. 11. The display device according to claim 4, wherein when the angle from the substrate perpendicular is θ and the pixel size is W, the thickness h of the display device per color is h in order to obtain a required viewing angle θ. A full-color display device configured to satisfy ≦ W / tan (θ) / 3. 12. The display device according to claim 1, wherein the display device is configured to have a curved surface shape.