JP4706176B2 - Microcapsule type electrophoretic display device and manufacturing method thereof - Google Patents

Description

The present invention relates to a microcapsule type electrophoretic display device suitable for large screen display and a method for manufacturing the same .

  Various flat panel display devices such as a liquid crystal display device, an EL display device, a microcapsule type electrophoretic display device and the like are known, and since these display devices are thin and lightweight, there are various types of display devices. Practical use is being promoted in a wide range of applications.

  For example, these flat panel display devices are being considered for use as large-screen display displays for transmitting information in waiting rooms of facilities such as hospitals and stations, and for advertising on the streets.

  However, these flat panel display devices are thin and lightweight, but are difficult to increase in size. Therefore, in order to display a large area, a plurality of display devices must be arranged and connected to a screen.

  Generally, in a flat panel display device in which a display medium is sandwiched between two electrode substrates represented by a liquid crystal display device, it is necessary to connect an electrode on the observation surface side to a drive circuit. Usually, a portion for making this electrical connection is provided at the peripheral portion outside the display area, but since the panel is fitted in a frame, this peripheral portion is not visible to the eye as long as it is used as a single display device. Since it does not stick, there is no particular problem.

  But as mentioned above. When a plurality of display devices are arranged in order to display a large area and the screens are connected, the large screen is divided by an electrical connection portion where the screens are not displayed, resulting in a problem that the screen is difficult to view. The electrical connection cannot be eliminated, and it is difficult to reduce the width.

The present invention is made under the circumstances described above, and is suitable for large screen display that enables easy-to-view image display when a plurality of display devices are arranged in parallel to connect a plurality of screens to form a large screen. Another object is to provide a microcapsule type electrophoretic display device .
Another object of the present invention is to provide a method of manufacturing such a microcapsule type electrophoretic display device .

  Another object of the present invention is to provide a display device having such a front plate.

In order to solve the above problems, one embodiment of the present invention is arranged to face the front plate so that a front plate having a transparent electrode layer on a film-like substrate and a microcapsule type electrophoretic display medium are interposed therebetween. A wiring board having an electrode layer on the display medium side and an electrical connection part on the opposite side of the display medium side, and the laminate of the film-like substrate and the transparent electrode layer of the front plate is An electrical connection between the transparent electrode layer in the non-display area of the laminate and the wiring board; and a display area in which the display medium is formed and a non-display area adjacent to the display area in which the display medium is not formed A microcapsule type electrophoretic display device is provided in which the unit is electrically connected to each other by an inter-substrate conductive film that covers an end face of the wiring board.

  Also, since the transparent electrode layer is usually not flexible, the transparent electrode layer may be damaged when the non-display area is bent. In addition, it is desirable to coat the conductive compensation layer. Since the non-display area does not necessarily need to be transparent, a flexible conductive layer may be coated on the film-like substrate in the non-display area instead of the transparent electrode.

Another aspect of the present invention, the ink comprising a microcapsule-type electrophoretic display medium in the display region forming region of the transparent electrode layer formed on one surface of the film-shaped substrate is coated, the in the transparent electrode layer A step of forming a display area in which a display medium is formed, a non-display area in which the display medium is not formed adjacent to the display area, and an electrode layer on one surface and an electrical connection portion on the other surface A step of bonding the electrode layer of the wiring board and the display medium layer of the film-like substrate, a transparent electrode layer in a non-display area at an end of the film-like substrate, and an electrical connection portion of the wiring substrate to the substrate And a step of electrically connecting the wiring substrate so as to cover an end portion of the wiring substrate with an inter- connection conductive film. A method of manufacturing a microcapsule type electrophoretic display device is provided.

  A metal paste such as a silver paste or a metal foil can be used as the conductive film for inter-substrate connection covering the end face of the wiring board.

According to the present invention, when performing display of a large screen by juxtaposed a plurality of display devices, inconspicuous or no seams between adjacent display screen makes it possible to perform excellent image display, microcapsules An electrophoretic display device and a manufacturing method thereof are provided.

Embodiments of the present invention will be specifically described below with reference to the drawings.
As shown in FIG. 1, a front plate of a display device according to an embodiment of the present invention includes a transparent electrode layer 2 and a display medium 3 on a film substrate 1.

  Since the film-like substrate 1 is a substrate on the observation side, it must be transparent, and since it is bent in the manufacturing process of the display device, it should be flexible enough to withstand bending. I must. Specific materials for the film-like substrate 1 satisfying such requirements include polyethylene terephthalate (PET), polyethylene (PE), polycarbonate (PC), polyethersulfone (PES), PEN, triacetyl cellulose (TAC) and the like. However, the present invention is not limited to these.

  Specific examples of the material for the transparent electrode layer 2 include, but are not limited to, indium oxide / soot (ITO) and indium oxide / zinc (IZO).

  The display medium 3 may be any display medium as long as it can display an image by applying a voltage and can be formed by electrolytic deposition. Examples of such a display medium include liquid crystal, organic EL, inorganic EL, electrophoretic display layer, dichroic toner, and electrochromic material. In FIG. 1A, a microcapsule display layer that is an electrophoretic display layer is shown as an example of the display medium 3.

  As shown in FIG. 1B, the planar shape of the front plate configured as described above is adjacent to the display area A where the display medium 3 is formed, and is not displayed. Since the non-display area B is bent at the time of manufacturing the display device and is electrically connected to a printed back plate described later, the area B has a sufficient width for such bending and electrical connection. It is what has.

  The planar shape of the front plate is not limited to the shape in which the non-display area B is provided as an extension of the entire side of the rectangular display area A as shown in FIG. But you can. That is, as shown in FIG. 2A, the non-display area B may be provided as an extension of only the central part of one side of the rectangular display area A, and may have a planar shape. As shown in FIG. 4, a planar shape in which the non-display area B is provided as an extension of the upper part and the lower part of one side of the rectangular display area A may be used.

  The non-display area B of the front plate is a laminate of the film-like substrate 1 and the transparent electrode layer 2, of which the film-like substrate 1 has flexibility, but the transparent electrode layer 2 often has no flexibility. . For this reason, if the non-display area B is bent in the manufacturing process of the display device, there is a possibility that cracks may occur in the transparent electrode layer 2 in that portion. As described above, when the transparent electrode layer 2 is cracked, electrical connection with the pad electrode on the printed back plate is hindered, and it becomes difficult to display the image by driving the display medium 3.

  In order to solve such a problem, as shown in FIG. 3A, a conductive compensation layer 4 made of carbon paste, silver paste, metal foil or the like is provided on the transparent electrode layer 2 in the non-display area B in advance. I can do it. The conductive compensation layer 4 may be provided on the entire surface of the transparent electrode layer 2 in the non-display region B, but may be selectively provided only in a portion where a crack is likely to occur due to bending. Alternatively, as shown in FIG. 3B, the non-display area B is provided with a flexible conductive compensation layer 5 made of carbon paste, silver paste, metal foil or the like instead of the transparent electrode layer 2. May be. Since these conductive compensation layers 4 and 5 are formed in the non-display region B, they do not need to be transparent, and may have flexibility and conductivity, so that the degree of freedom of material selection is great. .

  Next, a display device configured using the front plate described above will be described.

  FIG. 4 is a cross-sectional view illustrating a microcapsule electrophoretic display panel as an example of a display device including a front plate according to an embodiment of the present invention. The microcapsule-type electrophoretic display panel is thin, has a low manufacturing cost, and has low power consumption. Therefore, the microcapsule type electrophoretic display panel can be particularly suitably used for a large screen display in which a plurality of display panels are arranged in a plane. .

  As shown in FIG. 4, a microcapsule type electrophoretic display panel includes a printed back plate 11 having an electrode layer 12 formed on the surface, a transparent electrode layer 2 and a display medium on a film-like substrate 1 shown in FIG. 3 is bonded to a front plate. The non-display area of the film-like substrate 1 having the transparent electrode layer 2 formed on the inner surface is bent, and the transparent electrode layer 2 on the inner surface of the tip is electrically connected to the electrode 13 provided on the back surface of the printed back plate 11. Has been. The electrode on the back surface of the printed back plate 1 is connected to the driver IC 14.

  The microcapsule type electrophoretic display panel shown in FIG. 4 is manufactured as follows. That is, first, as shown in FIG. 1, electronic ink is printed as the display medium 3 on the display area A of the transparent electrode layer 2 formed on the film substrate 1 by screen printing or the like to form a front plate. . Next, the front plate is attached to the wiring substrate 11 having the electrode layer 12 on the surface via an adhesive layer (not shown).

  Next, the non-display area B of the front plate is bent along the end surface of the wiring substrate 11 so that the end portion reaches the back surface of the wiring substrate 11. The portion of the transparent electrode layer 2 at the end is electrically connected to the pad electrode 13 provided on the back surface of the wiring board 11.

  Thereafter, a driver IC 14 is connected to the back surface of the wiring substrate 11 to obtain a microcapsule type electrophoretic display panel as shown in FIG.

  As described above, in the microcapsule type electrophoretic display panel having the configuration shown in FIG. 4, the front plate is directly connected to the wiring substrate 11 through the non-display area. When displaying a large screen in parallel, the joint between adjacent display screens is not visible or noticeable.

  In the structure shown in FIG. 4, the non-display area B of the front plate is bent until the end portion reaches the back surface of the wiring substrate 11, and the transparent electrode layer 2 at the end portion is bent on the back surface of the wiring substrate 11. In the present invention, the present invention is not limited to such a structure, and as shown in FIG. 5, the non-display area B of the front plate has an end portion on the wiring board 11. The transparent electrode layer 2 at the end may be bent so as to reach the end surface of the wiring board 11 and electrically connected to the pad electrode 13 provided on the end surface of the wiring board 11.

  However, in this case, the width of the non-display portion at the end of the display device is widened, and when a plurality of display devices are arranged in a planar shape, there is a possibility that the joint between adjacent display devices may be noticeable, thus preventing this. For this purpose, as shown in FIG. 6, it is desirable to form a recess 15 in the end surface of the wiring substrate 11, provide a pad electrode 13 in the recess, and connect the end portion of the transparent electrode layer 2 to this. .

  The example in which the non-display area B of the front plate is bent and electrically connected to the wiring board 11 has been described above, but the present invention is not limited to this, and the non-display area B is bent as shown in FIG. Instead, the portion of the transparent electrode layer 2 at the end of the non-display area B and the wiring board are connected by the inter-substrate conductive film 16 made of metal paste such as silver paste or metal foil. Good. In this case, the non-display area of the front plate may be a narrow area because the connection to the inter-substrate conductive film 16 may be performed instead of the connection with the wiring board itself. As shown in FIG. 11, the inter-substrate conductive film 16 connected to the transparent electrode in the non-display area of the front plate covers the end surface of the wiring substrate 11 and is connected to the pad electrode 13 on the back surface of the wiring substrate 11. The

  In the configuration shown in FIG. 11 as well, as in the configuration shown in FIG. 5, the wiring substrate 11 and the inter-substrate connection conductive film 16 may be connected at the end face of the wiring substrate 11. As shown in FIG. 6, it is possible to provide a recess on the end face of the wiring board 11 to connect the wiring board 11 and the inter-substrate connecting conductive film 16. Furthermore, it is also possible to form a through hole in the end face of the wiring substrate 11 instead of the recess, and to connect the substrates by pouring a metal paste such as a silver paste into the through hole.

  As described above, even in the configuration shown in FIG. 11, the non-display area of the front plate is a very narrow area. Therefore, when a large screen is displayed by arranging a plurality of display devices, the adjacent display screens The joint between them is not noticeable.

  In the microcapsule-type electrophoretic display panel described above, the microcapsules included in the microcapsule display layer 3 include, for example, a methacrylic acid resin, urea resin, gum arabic or the like as a capsule shell 111 as shown in FIG. Inside, white particles 113 made of titanium oxide and black particles 114 made of carbon black are enclosed in a state of being dispersed in a highly viscous dispersion medium 112 such as silicone oil. Titanium oxide, which is a white particle 113, has a positive charge, while carbon black, which is a black particle 114, has a negative charge.

  A display body using such a microcapsule type electrophoresis system including the microcapsules 110 operates as follows.

  That is, as shown in the schematic diagram of FIG. 8, an electric field is applied to the transparent electrode layer 2 formed on the film substrate 1 and the electrode layer 12 on the printed board 11 side, the transparent electrode layer 2 being a negative electrode, and the electrode layer 12 being a positive electrode. In this case, positively charged white particles 113 are attracted to the transparent electrode layer 2 side, and negatively charged black particles 114 are attracted to the electrode layer 12 side. Therefore, when observed from above the transparent electrode layer 2 side, That part looks white.

  Conversely, when the transparent electrode layer 2 is the positive electrode and the electrode layer 12 is the negative electrode, the positively charged white particles 113 are drawn to the electrode layer 12 side, and the black particles 114 are the transparent electrode layer 2 side. Therefore, when observed from above the transparent electrode layer 2 side, the portion looks black.

  The microcapsule display layer 3 includes a large number of microcapsules 110. The transparent electrode layer 2 is used as a common electrode having the same potential, and the electric field of each address electrode of the electrode layer 12 is controlled. By moving the particles inside, desired characters and figures can be displayed as white and black pixels.

  Similarly, by using the electrode layer 12 as a common electrode (the potential is set to zero) and controlling the electric field of each address electrode on the transparent electrode layer 2 side (giving a positive or negative potential), the inside of the microcapsule at the electrode position The desired particles may be displayed by moving the particles.

  A plurality of display panels described above can be arranged to form a large screen display. FIG. 9 shows an example in which a large screen is configured by arranging a large number of rectangular display panels 20 in a planar shape vertically and horizontally. In the display device according to the present invention, there is no electrical connection portion as a non-display area for connecting the transparent electrode formed on the film-like substrate to the pad electrode of the printed circuit board at the periphery of the display surface. When a plurality of images are arranged and an image is displayed on a large screen, the seams between the display panels are hardly visible or are not noticeable even if they exist. Therefore, the display on the large screen can be seen without a sense of incongruity.

  As described above, the shape of the display panel is not limited to a rectangle, and various shapes such as a triangle, a pentagon, and a hexagon are possible, and these shapes are combined on a mosaic to constitute a large screen. I can do it. In this way, a three-dimensional curved display screen can be configured by using a polygonal shape other than a rectangle.

Next, a display device according to a specific embodiment of the present invention will be described.
FIG. 10 is a block diagram showing a display device according to a specific embodiment of the present invention. In FIG. 10, an image signal is sent from the host 30 to the display controller 40, and an image is displayed on the display panel 60 by the driver 50.

  The host 30 is a transmission side of an image signal to be displayed on the display panel 60. Usually, the image signal flows in only one direction from the host 30 to the display panel 60, and only the image is displayed. However, in some cases, the host 30 has a function of referring to the image displayed on the display panel 60. It is also possible to exchange signals in both directions.

  The display controller 40 includes a microprocessor unit (MPU), a power supply unit, a program memory storing firmware, a clock, an interface circuit, a connector, and the like. It may be equipped with a ROM for storing image and font data.

  The driver 50 includes a driver IC that outputs a voltage / current for driving the display medium of the display panel 50, capacitors that correct the operation of the circuit, communication chips, connectors, and the like.

  The display panel 60 has a structure in which a display medium is sandwiched between a front plate and a wiring board, and the details of the structure are as described above.

  As described above, the case where the microcapsule display layer which is an electrophoretic display layer is mainly used as the display medium has been described. However, the present invention is not limited to this, and the liquid crystal, organic EL, inorganic EL, dichroic toner, electrochromic The present invention can be applied to a display device using various display media such as materials.

  Since the front plate for a display device and the display device according to the present invention can perform excellent image display without any joint between adjacent display screens, information in a waiting room of a facility such as a hospital or a station is provided. It can be widely used as a display for various purposes such as transmission of information and advertisement on the street.

The front plate of the display apparatus which concerns on one Embodiment of this invention. The figure which shows the planar shape of the front plate of the display apparatus which concerns on one Embodiment of this invention. Sectional drawing which shows the front plate of the display apparatus which concerns on other embodiment of this invention. 1 is a cross-sectional view illustrating a microcapsule type electrophoretic display panel according to one embodiment of the present invention. Sectional drawing which shows the microcapsule type | mold electrophoretic display panel which concerns on the other form of this invention. Sectional drawing which shows the microcapsule type | mold electrophoretic display panel which concerns on the other form of this invention. The figure which shows typically the microcapsule contained in the microcapsule display layer of the microcapsule type | mold electrophoretic display panel shown in FIG. The perspective view which represents typically an example of the display form of the microcapsule display layer of the microcapsule type | mold electrophoretic display panel shown in FIG. The figure which shows the large screen which arranged many rectangular display panels in planar shape. The block diagram which shows the display apparatus which concerns on the specific form of this invention. Sectional drawing which shows the microcapsule type | mold electrophoretic display panel which concerns on the other form of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Film-like board | substrate, 2 ... Transparent electrode layer, 3 ... Display medium, 4, 5 ... Conductivity compensation layer, 11 ... Wiring board, 12 ... Electrode layer, 13. ..Pad electrode, 14 ... Driver IC, 15 ... Recess, 16 ... Electroconductive film for inter-substrate connection, 20, 60 ... Display panel, 30 ... Host, 40 ... Display controller , 50 ... driver, 110 ... microcapsule, 111 ... capsule shell, 112 ... dispersion medium, 113 ... white particles, 114 ... black particles.

Claims (4)

The display medium having a transparent electrode layer on a film-like substrate and a microcapsule-type electrophoretic display medium interposed between the front plate and the electrode plate on the display medium side. A wiring board having an electrical connection part on the opposite side, and the laminate of the film-like substrate and the transparent electrode layer of the front plate is adjacent to the display area in which the display medium is formed and the display area A non-display area in which the display medium is not formed, and connecting the transparent electrode layer in the non-display area of the laminate and the electrical connection portion of the wiring board to each other to cover the end face of the wiring board A microcapsule type electrophoretic display device characterized in that it is electrically connected by a conductive film.   The display device according to claim 1, wherein the inter-substrate conductive film is made of a metal paste or a metal foil. The ink comprising a film-like substrate of the microcapsule type electrophoretic display medium in the display region forming area of one surface which is formed on the transparent electrode layer is applied, the display area where the display medium to the transparent electrode layer is formed And forming a non-display area in which the display medium adjacent to the display area is not formed,
Bonding the electrode layer of the wiring board provided with an electrode layer on one surface and an electrical connection part on the other surface and the display medium layer of the film-like substrate;
The transparent electrode layer in the non-display area at the end of the film-like substrate and the electrical connection portion of the wiring substrate are provided so as to cover the end of the wiring substrate with an inter-substrate connection conductive film, and are electrically connected. And a process for producing a microcapsule type electrophoretic display device.   The method for manufacturing a display device according to claim 3, wherein the inter-substrate conductive film is made of a metal paste or a metal foil.

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