JP2010231000A - Light source integrated type electrophoretic display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source integrated type electrophoretic display device having a structure equipped with a front light obtained, by integrally forming a light source and an electrophoretic display layer to enable a user to view the display contents, even at night or in a dark environment, the structure having the reduced number of constitutional members on the electrophoretic display layer and causing light led from the light source to be emitted uniformly in an outgoing surface for attaining a bright display with high light utilization efficiency. <P>SOLUTION: The light source integrated type electrophoretic display device has the structure including the light source; a first substrate which is a transparent conductive member having an incident surface and an outgoing surface of light from the light source and having a transparent electrode layer on the light-outgoing surface; a second substrate which is a counter substrate disposed on a position opposed to the outgoing surface of the first substrate; and an electrophoretic display layer which includes charged particles and a dispersion medium with the charged particles dispersed therein and is sandwiched between the first substrate and the second substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention comprises an electrophoretic display unit that utilizes the fact that a slurry having microcapsules on a transparent substrate is coated on a substrate of a front light, and that charged particles in the microcapsules move by application of a voltage, and The present invention relates to a light source integrated electronic paper display device having a structure that can be seen in a dark environment.

  In recent years, with the development of information equipment, information display has been made in various forms. As the variable information display, a CRT (cathode ray tube), a liquid crystal display, and the like are mainly used. A light-emitting display such as a liquid crystal display of the type using a CRT or a backlight is not suitable for reading a document or the like because it makes the eyes look tired when used for a long time.

  In addition, since a liquid crystal display is currently thin as a flat panel display device and can be miniaturized, it is widely used in various applications. Are prone to fatigue, and the optical characteristics vary greatly depending on the viewing angle.

  On the other hand, a liquid crystal display of a type that does not use a backlight has a problem that the darkness of the screen due to the use of a polarizing plate appears and the visibility is poor. Furthermore, the images displayed on these displays have no memory property and have the disadvantage that they disappear at the same time as the electrical energy supply is stopped.

  In the replacement of the display of portable information devices such as e-books and portable information terminals, which are expected to become more popular in the future, even when used for a long time, it is less likely to cause eye fatigue, good visibility, and low power consumption. In addition, it is considered necessary to have image memory properties.

  Among them, electronic paper is one of display devices that are particularly attracting attention. This has the advantages of both paper and an electronic display, and has the feature that image information is retained even in a non-powered state and can be rewritten. Because of the reflective display, there is an advantage that the contrast ratio does not change and the viewing angle is wide. For example, an electronic paper electrophoretic display device using microcapsules as in Patent Document 1 has been proposed.

  However, while the conventional electronic paper is reflective, it can be seen by reflecting light from the outside, such as sunlight or fluorescent lamps. However, it can be seen at night or in a dark environment. There was a problem that it was not possible. In addition, since electronic paper is structurally reflective, it is difficult to use a transmissive type backlight like a liquid crystal display device to transmit light from the back side.

  In order to solve the above problem, for example, an electrophoretic display device having a front light composed of a commonly used light source and a light guide plate, such as Patent Document 2, has been proposed. There is a problem that the light utilization efficiency is lowered because several kinds of constituent member layers are transmitted before reaching the migration layer.

JP 2000-221546 A JP 2008-224900 A

  The present invention has been made to solve the above-mentioned problem, and by providing a front light in which a light source and an electrophoretic display layer are integrated, display contents can be visually recognized at night or in a dark environment, Furthermore, the number of components on the electrophoretic display layer is reduced, and the light source integrated type has a structure in which light introduced from the light source is uniformly emitted within the emission surface and bright display with high light utilization efficiency can be performed. An object is to provide an electrophoretic display device.

  In order to achieve the above-described object in the present invention, in claim 1, a transparent light guide member having a light source, an incident surface and an output surface from the light source, and a transparent electrode layer on the light output surface is provided. One substrate, a second substrate on the back substrate at a position facing the emission surface of the first substrate, a charged particle and a dispersion medium for dispersing the charged particles, and the first substrate and the second substrate The present invention provides a light source integrated electrophoretic display device having a structure having an electrophoretic display layer sandwiched therebetween.

  According to a second aspect of the present invention, a light guide and a transparent light guide having a light incident surface from the light source at a side end, a light emitting surface on the lower surface, and a transparent electrode on the light emitting surface. A first substrate of a member, a second substrate disposed opposite to the first substrate and having an electrode at a position facing the emission surface, and sandwiched between the two substrates, the charged particles and the dispersion medium are transferred to the first substrate. 2. The light source integrated electrophoretic display device according to claim 1, further comprising a microcapsule encapsulated by a resin film having a refractive index smaller than that of the substrate.

  Further, in claim 3, the electrophoretic display layer is configured as a microcapsule in which charged particles and a dispersion medium for dispersing charged particles are encapsulated in a resin film. An electrophoretic display device is provided.

  According to the present invention, by providing the front light, the display contents can be visually recognized even in a dark environment, and the substrate on the display surface side is also used as the transparent light guide plate of the front light, thereby reducing the number of components. There is an effect that display with high use efficiency is possible.

It is a schematic diagram which shows an example of the light source integrated electrophoretic display device 1 of the present invention. It is sectional drawing of the light source integrated electrophoretic display device 1 of this invention. It is a mimetic diagram of a microcapsule contained in a microcapsule display layer of a microcapsule type electrophoretic display sheet concerning an embodiment of the present invention. It is a block diagram which shows the system configuration example of the display format which concerns on one Embodiment of this invention.

  The best mode for carrying out the present invention will be specifically described below with reference to the drawings.

One of display devices using electrophoresis is an electrophoretic display device using microcapsules. White and black particles charged positively and negatively are placed in microcapsules filled with a dispersion medium, and an image is formed by pulling up each particle to the display surface by applying an external voltage. Since the size of the microcapsules is as small as several tens of μm to several hundreds of μm, when the microcapsules are dispersed in a transparent binder material, they can be coated like ink.

  An active matrix display can be obtained by coating the ink on a transparent resin film on which a transparent electrode is formed and bonding the ink to a substrate on which an electrode circuit for driving an active matrix represented by a TFT is formed. Usually, a component in which a transparent resin film on which a transparent electrode is formed is coated with electronic ink is called a “front plate”, and a substrate on which an electrode circuit for driving an active matrix is formed is called a “back plate”. In addition to the active matrix, various substrates and films having conductivity can be used for the back plate.

  FIG. 1 is a configuration diagram showing an example of a light source integrated electrophoretic display device 1 of the present invention.

  As shown in FIG. 1, the electrophoretic display device 1 of the present invention includes a front light unit portion 5, a transparent light guide plate 2, a TFT substrate 7, a light guide 3, a light source 6, and a cover 4 as a back plate layer.

  The front light unit 5 includes a light guide 3 provided at the end of the light source 6, a cover 4 that protects the light guide 3 and regulates the direction of light emitted from the light guide 3, and the light guide 3 that emits light from the light source 6. It is comprised from the transparent light-guide plate 2 which guides the light which enters via a display surface. Furthermore, it has a structure having a TFT substrate 7 as a driving substrate.

  FIG. 2 is a cross-sectional view of the light source integrated electrophoretic display device 1 of the present invention.

  As shown in FIG. 2, the front light unit portion 5 of the electrophoretic display device 1 of the present invention includes a transparent light guide plate 2 and a light source 6 as constituent members.

  The light source 6 is provided on the end side of the transparent light guide plate 2, and is configured as a light guide 3 rod-shaped light source.

  An electrophoretic display layer is formed by forming a transparent electrode layer 11 on the light output surface 13 side of the transparent light guide plate 2 and applying electronic ink containing microcapsules 8 and a binder on the transparent electrode layer 11 by screen printing. 10 is formed. Next, the conductive adhesive layer 9 is formed on the microcapsule display layer 10 to obtain the front plate 12.

  The light source integrated electrophoretic display device 1 of the present invention is obtained by bonding a transparent adhesive layer 9 and a TFT substrate (thin film transistor substrate) 7 as a back electrode.

  By the above method, the light source integrated electrophoretic display device 1 of the present invention also uses the display side substrate for holding the electrophoretic layer 10 also as the transparent light guide plate 2 of the front light to form an air layer or a low refractive index layer. It has a replaced structure. As a result, it is possible to reduce the number of constituent members required for the electrophoretic display layer 10 and increase the light utilization efficiency.

  The transparent light guide plate 2 is a flat transparent member having a large refractive index. Further, a side end surface facing the light source 6 at the end of the transparent light guide plate 2 is configured as a light incident surface 14, and an upper surface is a light emitting surface 13 of light propagating through the transparent light guide plate 2.

  The transparent light guide plate 2 has a wedge-shaped cross section in order to guide light incident from the light incident surface 14 from the light source 6 on the side surface of FIG. 2 from the light exit surface 13 side. Yes.

  The transparent light guide plate 2 includes a sheet shape, a film shape, or a plate shape, and in particular, if a sheet shape or a film shape is used, an effect of facilitating thinning and flexibility of the entire apparatus can be expected. The transparent light guide plate 2 can be made of, for example, PMMA (methyl methacrylate resin, acrylic resin), PET (polyethylene terephthalate), PC (polycarbonate), or the like as a transparent resin plate material. Etc.

  The transparent electrode layer 11 on the transparent light guide plate 3 is made of a conductive material having high light transmittance such as indium tin oxide (ITO) or indium zinc oxide (IZO). Moreover, you may use the transparent resin material which has electroconductivity for the transparent electrode layer 11 other than the said metal material. Such a transparent electrode layer 11 can be formed using a sputtering method, a vapor deposition method, or the like.

  The TFT substrate 7 can be formed by a printing method, a sputtering method, or the like.

  In addition to a white LED (Light Emitting Diode), a light emitting element such as an inorganic EL can be used as the light source 6, and the user can adjust the power on / off and the light amount of the light source 6 according to the surrounding environment. It has become a structure.

  FIG. 3 is a schematic view of microcapsules included in the microcapsule display layer of the microcapsule type electrophoretic display sheet according to the embodiment of the present invention.

  As shown in FIG. 5, the microcapsule 8 included in the electrophoretic display layer 10 has a capsule shell 15 made of methacrylic acid resin, urea resin, gum arabic or the like, and white particles 17 made of titanium oxide and carbon black therein. The black particles 18 are encapsulated in a state of being dispersed in a highly viscous dispersion medium 16 such as silicone oil. Titanium oxide, which is white particles 17, has a positive charge, while carbon black, which is black particles 18, has a negative charge.

  The display body using the microcapsule type electrophoresis method of the layer formed as shown in FIG. 2 operates as follows.

  As shown in the cross-sectional view of FIG. 2, the electrophoretic display layer 10 includes a large number of microcapsules 8. By controlling the direction of the electric field of the electrode layer, the particles in the microcapsules 8 are dispersed based on the principle described above. By moving it, it can be displayed as white and black.

  The light source-integrated electrophoretic display device 1 of the present invention having the above-described structure also has high contrast when displaying two colors, in which the white display is close to the white color of paper with high reflectivity in terms of visibility. The viewing angle is extremely large, and it can be used without problems under direct sunlight outdoors.

  Further, even in a dark environment, light is irradiated from the front light, and the irradiated light travels through the transparent light guide plate 2, and thus reaches the entire display surface, thereby enabling visual recognition.

  FIG. 4 is a block diagram showing a system configuration example of a display format according to an embodiment of the present invention.

As shown in FIG. 4, the light source integrated electrophoretic display device 1 of the present invention includes a front light unit 5 and an electrophoretic display layer 10. In addition, power is supplied to the irradiation control device 20 for controlling the light emission of the front light unit 5, the display control device 19 for controlling the display of the light source integrated electrophoretic display device 1, and each device and the light source 6. The power supply unit 21 is provided.

  The light amount of the front light is adjusted by the irradiation control device 20, and the display of the electrophoretic display layer 10 is controlled by the display control device 20.

  For the power supply unit 21, for example, a dry battery or a button battery can be used.

  As described above, white and black can be displayed by applying a voltage from the transparent electrode layer 11 and the TFT substrate 7 side of the transparent light guide plate 2, and by selectively applying a positive or negative voltage to the electrode, it can be selected. It is possible to express black and white colors.

  Since each particle in the microcapsule 8 of the electrophoretic display layer 10 is dispersed in a highly viscous dispersion medium, once the electric field is applied, the position of the particle does not change even when the power is turned off. In this way, since the display image has a memory property that does not disappear, an electric field may be applied only at the time of rewriting.

  When the refractive index of the resin film is smaller than that of the first substrate, a transparent electrode layer having a refractive index smaller than that of the first substrate is interposed between the emission surface of the first substrate and electrophoresis, so that On the other hand, light incident at a shallow angle is totally reflected at the boundary between the exit surface and the transparent electrode layer and propagates inside the light guide plate. In other words, the transparent electrode layer plays the same role as the conventional air layer, and the transparent electrode layer is disposed directly on the electrophoretic display upper layer, thereby reducing the number of constituent members disposed on the electrophoretic display layer. Improvement of light utilization efficiency can be realized.

  Therefore, even in the case of only reflection of external light without using a light source, it is more preferable because a brighter display can be realized than in the past.

  For example, ITO was coated as a transparent electrode layer, and an acrylic resin having a wedge-shaped cross section was used as a transparent light guide plate, and a coating solution was applied onto the ITO coating surface by a predetermined coating method.

  A conductive adhesive layer is provided on the coating sheet. Specific materials for the conductive adhesive layer include silicon rubber, acrylic rubber, butyl rubber, fluorine rubber, ethylene propylene rubber, and the like. The film thickness was about 25 μm, and a front plate was obtained.

  A TFT substrate is attached on the conductive adhesive layer. A light source integrated electrophoretic display device was obtained by connecting to a front light unit composed of a light source and a light guide.

  It was confirmed that a desired image was displayed by selectively applying a voltage to both substrates. In addition, a bright display can be realized even when only the external light is reflected, and the display image can be visually recognized by turning on the light source of the front light even in a dark environment.

DESCRIPTION OF SYMBOLS 1 ... Light source integrated electrophoretic display device 2 ... Transparent light guide plate 3 ... Ride guide 4 ... Cover 5 ... Front light unit part 6 ... Light source 7 ... TFT substrate 8. ··· Microcapsule 9 ··· Conductive adhesive layer 10 ··· Electrophoretic display layer 11 ··· Transparent electrode layer 12 · · · Front plate 13 · · · Light exit surface 14 · · · Light incident surface 15 ··· -Capsule shell 16 ... Dispersion medium 17 ... White particles 18 ... Black particles 19 ... Display control device 20 ... Lighting control device 21 ... Power supply unit

Claims (3)

  A light source, a first substrate of a transparent light guide member having an entrance surface and an exit surface from the light source, and having a transparent electrode layer on the light exit surface, and a back surface at a position facing the exit surface of the first substrate A structure including an electrophoretic display layer sandwiched between the first substrate and the second substrate, including a second substrate of the substrate, a charged particle and a dispersion medium for dispersing the charged particles. A light source integrated electrophoretic display device.   A light source, a first substrate of a transparent light guide member having a light incident surface from the light source at a side end, a light emitting surface on the lower surface, and a transparent electrode on the light emitting surface; A resin that is disposed opposite to the first substrate and has an electrode at a position facing the emission surface, and is sandwiched between the two substrates, and the charged particles and the dispersion medium have a smaller refractive index than the first substrate. 2. The light source integrated electrophoretic display device according to claim 1, further comprising a microcapsule encapsulated by a film.   2. The light source integrated electrophoretic display device according to claim 1, wherein the electrophoretic display layer is configured as a microcapsule in which charged particles and a dispersion medium for dispersing charged particles are encapsulated in a resin film.

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