JP2013195806A - Reflection type display device - Google Patents

Abstract

When a reflective display device performs multicolor display, there is a problem in that the display color is mixed due to a decrease in display brightness or the angle of incident light, and the quality of the display color is impaired.
A reflective substrate having a transparent substrate on the viewer side on which a transparent electrode layer is formed, a rear substrate on which a pixel electrode for driving the reflective display material is disposed, and a reflective display material sandwiched between the substrates. In a display device, by forming a planarizing layer made of a transparent resin covering a microlens disposed in a colored pixel region and a non-colored pixel region on a viewer-side transparent substrate and a microlens having a refractive index different from that of the microlens. The present invention provides a reflective display device that collects incident light on the viewer side, prevents color mixing due to reflected light being emitted from adjacent colored pixels, and enables bright multicolor display.
[Selection] Figure 1

Description

  The present invention relates to a reflective display device that can display a multicolor image.

About.

  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 using a CRT or a backlight is tired to the eyes of the viewer when used for a long time and is not suitable for reading a document or the like.

  In addition, liquid crystal displays used as flat panel display devices are thin and can be miniaturized, so they are used in a wide range of applications. There is a problem that the optical characteristics vary greatly depending on the angle. In addition, the power consumption of the light source is large, and the light source is consumed over time. When the light source is consumed, the display quality is significantly impaired.

  In addition, the display image of these displays has no memory property and has a drawback that it disappears at the same time as the electrical energy supply is stopped.

  In the replacement of display of portable information devices such as e-books and portable information terminals, which are expected to become more popular in the future, eyes will not get tired even when used for a long time, visibility is good, power consumption is low, In addition, it is considered necessary to have image memory properties.

  Among them, an electronic paper display is one of the display devices that are particularly attracting attention. This combines the advantages of paper and an electronic display. External light or room light is incident from a substrate from the observer side, and an image is displayed with reflected light through a reflective display material in the display device. Is. The image information is retained even in a non-powered state and can be rewritten. Moreover, it can be reduced in weight and can be said to be convenient as a portable terminal. 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 electrophoretic display device using microcapsules as in Patent Document 1 has been proposed.

  In recent years, there has been a demand for a multicolor display, and development is actively underway. Announcing a method for multicolor display by attaching a color filter to an electrophoretic display device for monochrome display of two colors. Has been. For example, an electrophoretic display layer, a transparent electrode layer, and a transparent substrate are laminated on a pixel electrode substrate through an adhesive layer, and another transparent substrate on which a color filter layer is formed is bonded through the adhesive layer. Furthermore, it takes the structure which bonded the protective film on the transparent substrate on the opposite side to the color filter layer via the adhesive layer.

  However, in the above method, it is necessary to provide a new adhesive layer between the color filter layer and the electrophoretic display layer, and the distance becomes large between the color filter layer and the electrophoretic display layer. There is a problem that the advantage of the electronic paper that the viewing angle is wide is lost.

In addition, when the light incident from the substrate on the viewer side passes through the colored pixels of the color filter layer and exits through the reflective display material layer, the reflected light is emitted from the adjacent pixels, so that the display color is mixed. However, there is a problem that the quality of the display color is impaired. Furthermore, since the reflective display device uses external light incident on the device as display light, the light utilization efficiency decreases and the display brightness is reduced when the external light passes through components such as a transparent substrate and a color filter layer. There was a problem that decreased.

Japanese Patent No. 3837948

  The present invention has been made to solve the above problems, and in a reflective display device capable of multicolor display, the viewing angle generated by overlapping a color filter on the reflective display material layer is reduced. Provided is a reflective display device that can be avoided and prevents a color mixture and a decrease in color purity that occur when reflected light is emitted from adjacent colored pixels, and enables clear multicolor display with high visibility. Objective.

  The present invention has been made to achieve the above object, and the invention according to claim 1 is directed to a first substrate comprising a transparent substrate on which a transparent electrode is formed, and an electrode facing the transparent electrode of the first substrate. A reflective display device having a reflective display material sandwiched between the two substrates, a color filter layer laminated on the first substrate via an undercoat layer, and the color filter A microlens layer laminated on the layer, and a planarizing layer in which the microlens of the microlens layer is covered with a transparent resin having a refractive index different from that of the microlens, and the planarizing layer is laminated via an adhesive layer And a protective film layer for forming a display surface.

  According to a second aspect of the present invention, in the reflective display device according to the first aspect, the microlens of the microlens layer is disposed in the colored pixel region and the non-colored pixel region of the color filter layer, The refractive index of the resin material constituting the lens is larger than the refractive index of the transparent resin of the flattening layer covering the microlens.

  According to a third aspect of the present invention, in the reflective display device according to the first aspect, the first substrate has a thickness of 5 μm to 100 μm.

  According to a fourth aspect of the present invention, in the reflective display device according to the first or second aspect, at least one microlens of the microlens layer is formed on one colored pixel portion of the color filter layer. The thickness of each lens is 20 μm or less.

  The invention according to claim 5 is the reflective display device according to claim 1, wherein a transparent resin layer is interposed between the planarizing layer and the microlens layer.

  According to the present invention, in order to solve the above problem, by directly forming the reflective display material layer on the transparent substrate provided with the transparent electrode layer, the reflective display material layer and the color filter layer have a close structure, Compared to a display device formed by attaching a color filter, it is possible to prevent the narrowing of the viewing angle.

  In addition, by forming a layer composed of a microlens and a flattening layer that covers the microlens, and having a structure in which a color filter layer and a reflective display material layer are integrated, color mixing for multicolor display and The display color quality is prevented from being lowered, the light collection effect is further improved, and bright display can be achieved efficiently.

It is sectional drawing of the reflection type display apparatus 1 of this invention. It is a schematic diagram of the microcapsule of the display material of the reflective display layer in connection with the embodiment of the present invention.

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

  One of the reflective display devices is an electrophoretic display device using microcapsules. In a microcapsule filled with a dispersion medium, white particles and colored particles that are positively and negatively charged are placed, 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 above-mentioned ink on a transparent resin film on which a transparent electrode is formed and bonding the resultant 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 schematic view showing a configuration example of a reflective display device 1 according to an embodiment of the present invention. In this embodiment, a configuration using microcapsules as a reflective display material is shown as an example. In FIG. 1, an arbitrary viewpoint on the viewer's viewing (viewing) side with respect to the reflective display device 1 is indicated by a symbol p, and a display surface for the observer is indicated by a symbol s.

  As shown in FIG. 1, a reflective display device 1 according to an embodiment of the present invention includes a first substrate 10 including a transparent substrate 8 on the viewer side on which a transparent electrode layer 9 is formed, and an example of a reflective display material. An electrophoretic display type, a reflective display layer 13 composed of a microcapsule 11 enclosing white particles and colored particles (see reference numerals 18 and 19 in FIG. 2) and a binder resin layer 12, and a conductive adhesive layer 14. A pixel electrode 15 and a second substrate 17 including a back substrate 16 are sequentially stacked.

  Further, the undercoat layer 7 for fixing the color ink of the color filter layer 6 on the surface of the first substrate 10 where the reflective display layer 13 is not formed, the colored pixels of the color filter layer 6, and the micro on the color filter layer 6. A lens layer 5, a planarizing layer 4 made of a transparent resin that covers the microlens layer 5, an adhesive layer 3, and a protective film layer 2 are sequentially laminated.

  First, a coating liquid in which microcapsules 11 and a binder resin 12 are dispersed is applied on the transparent electrode layer 9 formed on the first substrate 10 by a predetermined coating method to form a reflective display layer 13. The conductive adhesive layer 14 is bonded to the reflective display layer 13, and then the pixel electrode (15) of the second substrate (17) composed of the surface of the conductive adhesive layer 14, the pixel electrode 15, and the back electrode 16. Paste.

  Next, the undercoat layer 7 is formed on the surface of the first substrate 10 on which the reflective display layer 13 is not formed by a coating method such as die coating, bar coating, spin coating, screen printing, or offset printing. As an example of the undercoat layer 7, a resin such as a urethane resin, an acrylic resin, a polyester resin, or a vinyl chloride resin can be used.

  Further, colored pixels are formed in the pixel region of the color filter layer 6 on the undercoat layer 7 using the color ink, and then the microlens layer 5 is formed using a lens material.

  The color filter layer 6 and the microlens layer 5 are formed by a predetermined method such as ink jet printing, screen printing, or offset printing. When the microlens material is a UV light curable resin, it is formed by curing with UV light.

  Next, the planarizing layer 4 is formed on the microlens layer 5 by a coating method such as die coating, bar coating, or spin coating, and then an adhesive such as urethane resin or acrylic resin is used to protect the display device surface. The reflective display device 1 according to the embodiment of the present invention is obtained by forming the protective film layer 2 through the adhesive layer 3 having the above.

  By providing the microlens layer 5 and the flattening layer 4 and using a material having a refractive index larger than that of the material of the flattening layer 5 as the lens material of the microlens layer 5, light incident from the first substrate 10 side is After being uniformly scattered by the microlens layer 5, it is emitted from the first substrate 10 side through the reflective display layer 13. As a result, regardless of the angle of light incident on the reflective display device 1, light incident from an oblique direction can be condensed on the pixel area, and a bright display can be observed on the viewer side. Furthermore, since it is possible to suppress display color mixing that occurs when incident light is emitted from adjacent pixels through reflected light emitted from the reflective display material, a display image with high display brightness and high quality is obtained. be able to.

  By using a material in which the refractive index of the lens material of the microlens layer 5 is higher than the refractive index of the resin material of the planarizing layer 4, the microlens layer 5 allows the lens to be used regardless of the angle of light incident from the first substrate 10 side. It is uniformly scattered and can be focused on the pixel area.

  The lens material of the microlens layer 5 is preferably one that has high light transmittance and refractive index and can be cured as a lens shape after formation, and is preferably a photo-curing resin or a thermosetting resin. For example, polycarbonate resin, acrylic resin, silicon resin, epoxy resin, polyimide resin, melamine resin, methacrylate resin, or the like can be used. The viscosity of these resin materials can be adjusted using a solvent or the like as needed.

  In the formation method of the color filter layer 6 and the microlens layer 5, the inkjet printing method, which is one of the droplet discharge methods, is preferable because a necessary lens can be formed at an arbitrary position and at an arbitrary discharge amount. You can say that. Compared with a method using a conventional photolithography method, the process can be simplified, and further, there are many advantages such as high material efficiency and easy area enlargement of the substrate.

  The planarizing layer 4 formed on the upper layer of the microlens layer 5 preferably has a higher light transmittance and a lower refractive index. For example, a fluorine resin having a refractive index of 1.34 to 1.45 or a refractive index of 1.46. An organic silicate of ˜1.48 can be used. Further, the resin of the planarizing layer 4 may contain a low refractive index substance, and a fluorine-based surfactant or the like can be used as such a low refractive index substance.

  The liquid substance, which is the lens material of the microlens layer 5 formed by the above method, may spread out in accordance with the contact angle with the colored pixels of the color filter layer 6 and the undercoat layer 7 after formation. Therefore, in order to prevent the liquid material of the material from spreading out and form a desired shape, it may be desirable to perform a liquid repellent treatment on the surface of the color ink forming the color filter layer 6. Examples include pixel formation using a color ink containing a liquid repellent, surface fluorine plasma treatment, and the like.

  The material of the liquid repellent is not particularly limited, and examples thereof include silicon resin, fluororesin, and wax. The liquid repellent is preferably 0.1 to 5% by weight with respect to the color ink composition. .

  The lens shape of the microlens layer 5 is preferably a shape whose surface forms part of a spherical surface. The microlens layer 5 has the function of a spherical lens, and after the incident light incident on each pixel is refracted to the pixel portion region, it can be reflected by the reflective display material layer 13. Further, the surface shape is not limited to a spherical surface, but may be an aspherical surface.

  One or more microlenses 5 are preferably formed on one colored pixel portion of the color filter layer 6, and each thickness is preferably 20 μm or less. This is because if it exceeds 20 μm, it becomes difficult to flatten by the flattening layer 4 formed on the microlens 5. Moreover, the microlens 5 can be arrange | positioned according to the structure of the color filter layer 6 each arrange | positioned uniquely.

  Further, the flattening layer 4 can prevent display unevenness by forming a flat layer by filling the irregularities and gaps on the surface of the microlens layer 5. In addition, when sufficient planarity cannot be obtained simply by forming the planarizing layer 4 on the microlens layer 5, a transparent resin layer is provided between the planarizing layer 4 and the microlens layer 5 and then the planarizing layer is formed. By forming, it is possible to improve flatness.

  Further, when the planarizing layer 4 has sufficient tackiness, the protective film 2 may be bonded without providing the adhesive layer 3.

  Examples of the substrate of the transparent substrate 8 include various transparent substrates such as polycarbonate resin, acrylic resin, polyethylene terephthalate resin, and glass as a supporting base material that holds the color filter layer 6 and the reflective display layer 13.

  When the thickness of the transparent substrate 8 is 5 μm or less, when forming the undercoat layer 7 or the like on the transparent substrate 8, the workability such as large deformation of the base material due to expansion and contraction is low, and the display by deformation This is because unevenness of the image is likely to occur. When the thickness is 100 μm or more, the distance between the color filter layer and the display material layer is widened, so that parallax occurs depending on the viewing angle, and the color unevenness becomes remarkable.

  The transparent electrode layer 9 on the transparent substrate 8 is made of a conductive material having high light transmittance such as indium tin oxide (ITO) or indium zinc oxide (IZO). The transparent electrode layer 9 may be made of a conductive material in addition to the metal material.

  FIG. 2 is a schematic view of a microcapsule as an example of a material included in the reflective display layer of the reflective display device according to the embodiment of the invention.

  As shown in FIG. 2, the microcapsule 11 included in the reflective display layer 13 includes a microcapsule shell 21 made of methacrylic acid resin, urea resin, gum arabic, or the like, and white particles 18 made of titanium oxide and carbon black therein. The colored particles 19 are encapsulated in a dispersed state in a highly viscous dispersion medium 20 such as silicone oil.

  The display body of the reflective display device 1 having a layer formed as shown in FIG. 1 displays information such as characters on the display surface s by applying voltage from the transparent electrode 9 on the transparent substrate 8 and the pixel electrode substrate side. The color can be expressed by selectively applying a positive or negative voltage to the electrodes.

  As shown in the cross-sectional view of FIG. 1, the reflective display layer 13 includes a large number of microcapsules 11. By controlling the direction of the electric field of the electrode layer, the particles in the microcapsules 11 are dispersed based on the principle described above. By moving it, it can be displayed as white and black.

  The reflective display device 1 according to the embodiment of the present invention having the above-described structure is easy to see and close to the white color of paper, has a very large viewing angle, and can be used without problems under direct sunlight outdoors. is there.

  Since each particle in the microcapsule 11 of the reflective display layer 13 is dispersed in a highly viscous dispersion medium, the position of the particle does not change even when the power is turned off once the electric field is applied. 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.

Examples of the present invention will be described below.

  A coating liquid in which microcapsules having a solid content of 40% by weight and a urethane binder resin are dispersed as a reflective display material on a 50 μm-thick PET base ITO film having an ITO film formed as a transparent electrode layer is die-coated. Was applied to obtain a front plate with microcapsules. Next, on the surface of the PET base material on which the microcapsules were not formed, an ink jet receiving layer solution was formed by bar coating to a thickness of 10 μm.

  1.2% by weight of a fluorine-based liquid repellent is added to the color inks R, G, and B with respect to the color ink composition, and a colored pixel is formed in accordance with each pixel by using an inkjet device for the image receiving layer. And dried at 90 ° C. for 3 minutes. Furthermore, inkjet printing was similarly performed on the colored pixels and the non-colored pixels using an acrylic resin as a lens material to form microlenses.

  Next, the planarizing layer was formed using a fluorine-based resin having a refractive index of 1.35 so as to have a thickness of 10 μm. Furthermore, a PET protective film having a thickness of 10 μm and a thickness of 100 μm was bonded using a urethane resin to obtain a reflective device capable of multicolor display.

Comparative Example 1

  Reflective type capable of multicolor display by attaching a color filter made of 0.7 mm substrate on which color inks R, G, and B are formed to the front plate with microcapsules in Example 1 to a PET substrate on the display surface side. A display device was obtained.

  When the reflective apparatus of Example 1 was driven, a desired operation could be obtained without any problem. As a result of providing the color filter layer directly on the substrate on the viewer side, narrowing of the viewing angle could be prevented. Further, since the microlens layer and the flattening layer are formed, light incident from an oblique direction can be condensed on the pixel region, display brightness is higher than that of Comparative Example 1, and reflected light is emitted from the adjacent pixels. By doing so, it was possible to prevent display colors from being mixed and to obtain a high-quality display image.

  DESCRIPTION OF SYMBOLS 1 ... Reflective type display apparatus, 2 ... Protective film layer, 3 ... Adhesive layer, 4 ... Planarization layer, 5 ... Micro lens layer, 6 ... Color filter layer, 7 ... Undercoat layer, 8 ... Transparent substrate, 9 ... Transparent electrode layer, 10 ... first substrate, 11 ... microcapsule layer (reflection display medium), 12 ... binder resin layer, 13 ... reflection display layer, 14 ... conductive adhesive layer, 15 ... pixel electrode, 16 ... Back substrate, 17 ... second substrate, 18 ... white particles, 19 ... colored particles, 20 ... dispersion medium, 21 ... microcapsule shell.

Claims (5)

A reflective display having a first substrate comprising a transparent substrate on which a transparent electrode is formed, a second substrate having an electrode disposed opposite the transparent electrode of the first substrate, and a reflective display material sandwiched between the two substrates In the device
A color filter layer laminated on the first substrate via an undercoat layer;
A planarizing layer in which a microlens layer laminated on the color filter layer and a microlens of the microlens layer are covered with a transparent resin having a refractive index different from that of the microlens;
A protective film layer forming a display surface laminated on the planarizing layer via an adhesive layer;
A reflective display device comprising:   The microlens of the microlens layer is disposed in the colored pixel region and the non-colored pixel region of the color filter layer, and the refractive index of the resin material constituting the microlens is a transparent resin of a planarizing layer that covers the microlens The reflective display device according to claim 1, wherein the reflective display device has a refractive index larger than that of the reflective display device.   The reflective display device according to claim 1, wherein the first substrate has a thickness of 5 μm to 100 μm.   3. The reflection according to claim 1, wherein at least one microlens of the microlens layer is formed on one colored pixel portion of the color filter layer, and each lens has a thickness of 20 μm or less. Type display device.   The reflective display device according to claim 1, wherein a transparent resin layer is interposed between the planarizing layer and the microlens layer.

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