JP2015011327A - Reflective display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective display device capable of suppressing development of a moire phenomenon without requiring precise alignment of a partition wall pattern and a pixel electrode pattern.SOLUTION: The reflective display device includes a display medium sealed between opposing two substrates and performs desired display by the display medium when a predetermined electric field is applied between the two substrates. In the device, one substrate has light-transmitting property; and a partition wall segmenting a plurality of cells, a plurality of pixel electrodes arranged in a periodical pattern, and a plurality of electrode structures corresponding to the plurality of pixel electrodes are disposed between the one substrate and the other substrate, in the above order along a direction from the one substrate side to the other substrate side. In a view in a direction from the one substrate side to the other substrate side, light reflection characteristics of a region where the pixel electrode is disposed, and light reflection characteristics of a region between the pixel electrodes are approximately the same.

Description

  The present invention relates to a reflective display device applied to electronic paper and the like.

  Recently, as a reflective display device, an electrophoretic display device using an electrophoretic material as an electroresponsive material contained in a display medium has been widely used. An electrophoretic display device is a device that displays information by using electrophoretic migration, that is, particle movement, of an electrophoretic body (usually electrophoretic particles) in air or in a solvent. In general, an electrophoretic state is controlled by applying an electric field between two substrates, thereby realizing a desired display. As the electrophoretic body, charged powder as well as charged particles can be used. In that case, the charged powder electrophoreses in the gas.

  In recent years, the electrophoretic display device has attracted attention especially as an electronic paper. When applied as an electronic paper, it is possible to enjoy advantages such as visibility at the printed matter level (easy for eyes), ease of information rewriting, low power consumption, and light weight.

  However, in an electrophoretic display device, display defects, particularly a decrease in contrast, may occur due to sedimentation or uneven distribution of particles or powder. In order to prevent this phenomenon, it is used to form partition walls between the upper and lower electrode substrates and divide the migration space of the particles and powder to be electrophoresed, that is, the movement space into minute spaces. This minute space is called a cell. In each cell, ink or gas (display medium) containing an electrophoretic body is enclosed. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2005-24868) and Patent Document 2 (Japanese Patent Publication No. 2011-524548) disclose conventional examples of such an electrophoretic display device.

Japanese Patent Laid-Open No. 2005-24868 Special table 2011-524548 gazette

  The present inventor has obtained the following knowledge while earnestly researching the reflective display device that observes the other substrate through the partition wall from the one substrate side.

  In the reflective display device as described above, a common translucent electrode that covers at least the display region, a partition wall that partitions a plurality of cells, and a periodic pattern are arranged between one substrate and the other substrate. The plurality of pixel electrodes formed are provided in this order when viewed from the one substrate side toward the other substrate side. And the desired display is implement | achieved by controlling the electrophoretic state of the electroresponsive material contained in a display medium for every cell. The pattern of the pixel electrode is a matrix-like periodic alignment pattern that generally forms a rectangle as a whole. In general, the partition walls are also formed in a pattern having periodicity.

  For this reason, in a reflective display device in which the partition pattern and the pixel electrode pattern are not precisely aligned, a moire phenomenon appears and display unevenness occurs. In particular, when manufacturing a high-definition and large-screen reflective display device, it is necessary to perform alignment with higher accuracy.

  The present invention has been made based on such circumstances, and an object of the present invention is to suppress the occurrence of the moire phenomenon without requiring precise alignment between the partition pattern and the pixel electrode pattern. The object is to provide a reflective display device.

  In the present invention, a display medium containing at least one kind of electrically responsive material is sealed between two opposing substrates each having an electrode formed thereon, and a predetermined electric field is applied between the two substrates. A reflective display device that displays a desired display when the one substrate has a light-transmitting property, and a common area that covers at least a display region between the one substrate and the other substrate. A translucent electrode, a partition partitioning a plurality of cells, a plurality of pixel electrodes arranged in a periodic pattern, and a plurality of electrode structures corresponding to the plurality of pixel electrodes are arranged on the one substrate side. Are provided in this order as viewed from the other substrate side toward the other substrate side, and each of the pixel electrodes has a via hole for electrically connecting the corresponding pixel electrode and the electrode structure to each other. Formed from the one substrate side. The reflection type characterized in that the light reflection characteristic of the region excluding the via hole in the pixel electrode and the light reflection characteristic of the region between the pixel electrodes are substantially the same when viewed in the direction toward the other substrate. It is a display device.

  According to the present invention, the light reflection characteristic of the region excluding the via hole in the pixel electrode and the light reflection characteristic of the region between the pixel electrodes are substantially the same, and therefore the period of the pattern of the pixel electrode from one substrate side Visibility is reduced. Thereby, the expression of the moire phenomenon is suppressed.

  Alternatively, in the present invention, a display medium containing at least one kind of electrically responsive material is sealed between two opposing substrates each having an electrode formed thereon, and a predetermined electric field is interposed between the two substrates. Is a reflective display device that displays a desired display when given, and one substrate has translucency, and covers at least a display region between the one substrate and the other substrate. The one substrate includes a common translucent electrode, partitions partitioning a plurality of cells, a plurality of pixel electrodes arranged in a periodic pattern, and a plurality of electrode structures corresponding to the plurality of pixel electrodes. Are provided in this order when viewed from the side toward the side of the other substrate, and each of the pixel electrodes is electrically connected to the corresponding pixel electrode and the electrode structure. A via hole is formed and said one base In the reflection type display device, the light reflection characteristic of the pixel electrode and the light reflection characteristic of the region between the pixel electrodes are substantially the same when viewed from the side toward the other substrate side. is there.

  According to the present invention, since the light reflection characteristics of the pixel electrodes and the light reflection characteristics of the region between the pixel electrodes are substantially the same, the visibility of the period of the pixel electrode pattern from one substrate side is reduced. . Thereby, the expression of the moire phenomenon is suppressed.

  For example, the light reflection characteristic is a color tone. In this case, if the color tone is set to the same color tone as that to be emphasized when desired display is performed on the reflective display device, the desired color tone can be displayed more clearly.

  Preferably, an insulating film is provided in a region between the pixel electrodes and a region on the other substrate side of each pixel electrode, and the insulating film includes a low-transmittance layer having a light transmittance of 10% or less. In addition, the pixel electrode is formed of a material having a high light transmittance of 80% or more. In this case, since the pixel electrode sufficiently transmits the light reflected by the insulating film, it is easy to make the light reflection characteristic of the region where the pixel electrode is disposed substantially the same as the light reflection characteristic of the insulating film. . As a result, it is easy to make the light reflection characteristics of the area where the pixel electrodes are formed substantially the same as the light reflection characteristics of the area between the pixel electrodes. In this case, for example, the pixel electrode is formed of indium oxide IXO (X = Sn, Zn, Ga, etc.), silver nanowire, PEDOT, and zinc oxide.

  Preferably, an insulating film is provided in a region between the pixel electrodes, and the insulating film includes a low-transmittance layer having a light transmittance of 10% or less. It is formed of a material having a low transmittance of 10% or less. In this case, since the pixel electrode sufficiently blocks light reflected by the insulating film, the light reflection characteristics of the region where the pixel electrode is disposed are suppressed from being affected by the light reflection characteristics of the insulating film. Therefore, it is easy to make the light reflection characteristic of the pixel electrode and the light reflection characteristic of the insulating film substantially the same by appropriately selecting materials for the insulating film and the pixel electrode. As a result, it is easy to make the light reflection characteristics of the pixel electrodes substantially the same as the light reflection characteristics of the region between the pixel electrodes. In this case, for example, the low transmittance layer is formed of a titanium oxide black matrix or a carbon black matrix, and the pixel electrode is formed of carbon.

  For example, the electrode structure is a TFT electrode structure.

  Preferably, the partition is formed in a pattern that does not generate moire fringes with respect to the periodic pattern of the pixel electrodes. In this case, the occurrence of the moire phenomenon is remarkably suppressed. For example, the partition is formed in an aperiodic pattern.

  ADVANTAGE OF THE INVENTION According to this invention, the reflection type display apparatus which can suppress the expression of a moire phenomenon without requiring precise alignment with the pattern of a partition and the pattern of a pixel electrode can be provided.

FIG. 1 is a cross-sectional view schematically showing a configuration of a reflective display device according to an embodiment of the present invention. FIG. 2 is a flowchart schematically showing a manufacturing method of the reflective display device according to the embodiment of the present invention. FIG. 3 is a diagram schematically showing an example of the partition wall forming step. FIG. 4 is a diagram illustrating an example of a partition pattern. Specifically, FIG. 4A is a diagram showing a honeycomb-shaped periodic pattern in which hexagonal unit patterns are regularly arranged, and FIG. 4B is a diagram showing regular rectangular unit patterns. FIG. 4C illustrates a non-periodic pattern in which moire fringes are not generated with respect to the matrix-shaped periodic pattern of pixel electrodes. It is a figure which shows a pattern. FIG. 5 is a diagram for explaining the definition of the width of the top surface of the partition wall. FIG. 6 is a diagram schematically showing an example of the adhesive layer forming step. FIG. 7 is a diagram schematically showing an example of the display medium arranging step. FIG. 8 is a schematic view for explaining the function of the conductive paste. FIG. 9 is a plan view showing pixel electrodes arranged in a matrix-like periodic pattern on the other substrate. FIG. 10 is a diagram schematically showing a pixel electrode, a TFT electrode structure corresponding to the pixel electrode, and an insulating film disposed between the TFT electrode structure and the pixel electrode. Specifically, FIG. 10A is a plan view showing the pixel electrode disposed on the TFT electrode structure, and FIG. 10B is a cross-sectional view taken along the line 10b-10b in FIG. FIG. 3 is a diagram showing a state in which a pixel electrode disposed on a TFT electrode structure via an insulating film is electrically connected to a corresponding TFT electrode structure by a via hole formed in the pixel electrode. FIG. 11 is a diagram for explaining the mechanism of the occurrence of the moire phenomenon. FIG. 12 is a diagram for explaining a mechanism for suppressing the occurrence of the moire phenomenon according to the present invention. FIG. 13 is a cross-sectional view showing a state where the other substrate is bonded to the partition wall top surface of one substrate in the counter substrate arranging step.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a reflective display device according to an embodiment of the present invention. In the reflective display device according to the present embodiment, a display medium 13 containing at least one kind of electrically responsive material is sealed between two opposing substrates 11 and 16 each having an electrode formed thereon. When a predetermined electric field is applied between the substrates 11 and 16, the display medium 13 performs a desired display. Here, in the specification and claims of the present application, “translucent” means a property of transmitting light. In this embodiment mode, the substrate disposed on the viewing side has a light-transmitting property such that the total light transmittance is 50% or more, preferably 80% or more, and more preferably 90% or more.

  In FIG. 1 to FIG. 13, electrodes are provided on the surface of one substrate 11, but the illustration of these electrodes is omitted. In the present embodiment, one substrate 11 has translucency and is disposed on the viewing side, and the other substrate 16 is disposed on the non-viewing side.

  One substrate 11 includes a light-transmitting film such as polyethylene (PE), polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), or light-transmitting glass, and indium tin oxide (ITO). ), Zinc oxide (ZnO), tin oxide (SnO), or the like having a translucent electrode (translucent electrode) so as to cover at least the display region of one substrate 11 is typically used. obtain. Here, the “display area” refers to an area used for desired display in the reflective display device.

  The translucent electrode can be formed by a coating method, sputtering, a vacuum deposition method, a CVD method, or the like. In this embodiment, the translucent electrode is formed as a common electrode for active matrix driving.

  The thickness of one substrate 11 is preferably 10 μm to 1 mm. If it is thinner than 10 μm, the strength as a panel cannot be obtained and the risk of breakage increases. On the other hand, if it is thicker than 1 mm, the panel weight becomes too heavy and the handling becomes inconvenient and the cost also increases. Because. A suitable thickness range that is difficult to break and easy to handle is about 50 μm to 300 μm.

  One substrate 11 can be applied in either a roll shape or a sheet shape.

  As the other substrate 16, a substrate such as a resin film, a resin plate, glass, epoxy glass (glass epoxy) or the like can be used. The other substrate 16 may be a translucent base material. Furthermore, it may be an opaque base material that is translucent, but an opaque glass base material, resin film, resin plate, glass, epoxy glass with the other surface different from the electrode surface roughened. (Garaepo) or the like can be used. In the present embodiment, since the other substrate 16 is disposed at a position opposite to the viewing side, there is no necessity of having translucency. However, when the same physical properties as the one substrate 11 such as thermal expansion characteristics are required, a light-transmitting member similar to the one substrate 11 can be used.

  In a later step, a plurality of pixel electrodes 161 and an electrode structure 163 corresponding to the plurality of pixel electrodes are provided on the surface of the other substrate 16 on the display medium side. In the present embodiment, the electrode structure 163 is an electrode structure corresponding to a TFT (Thin Film Transistor) layer for active matrix driving.

  The thickness of the other substrate 16 is preferably 10 μm to 1 mm, similarly to the thickness of the one substrate 11. If it is thinner than 10 μm, the strength as a panel cannot be obtained and the risk of breakage increases. On the other hand, if it is thicker than 1 mm, the panel weight becomes too heavy and the handling becomes inconvenient and the cost also increases. Because. A suitable thickness range that is difficult to break and easy to handle is about 50 μm to 300 μm.

  The other substrate 16 can be applied in either a roll shape or a sheet shape.

<Method for manufacturing reflective display device>
FIG. 2 is a flowchart schematically showing a manufacturing method of the reflective display device according to the embodiment of the present invention.

  FIG. 3 is a diagram schematically showing an example of the partition wall forming step. As shown in FIG. 3, first, a partition wall 12 is formed on the upper surface of one substrate 11 generally placed in a horizontal direction by, for example, photolithography (exposure by ultraviolet (UV) irradiation → development → firing). The The partition wall 12 is a member that defines a plurality of cells to be described later.

  The partition wall 12 can be composed of an ultraviolet curable resin, a thermosetting resin, a room temperature curable resin, or the like. As a method for forming the partition wall 12, a mold transfer method such as embossing can be adopted in addition to the photolithography method. Further, a method of manufacturing a structure having a desired pattern as a partition and sticking the structure to one substrate 11 may be employed. The partition wall 12 may be formed on the pixel electrode 161 formed on the other substrate 16 in a pixel electrode formation step described later.

  In the present embodiment, the partition walls 12 are formed in a honeycomb-like periodic pattern in which hexagonal unit patterns as shown in FIG. 4A are regularly arranged. Of course, other shapes can be adopted as the pattern of the partition wall 12, for example, a square lattice periodic pattern in which rectangular unit patterns as shown in FIG. 4B are regularly arranged. Also good. Further, the pattern of the partition wall 12 may be a non-periodic pattern as shown in FIG. 4C, that is, a pattern that does not cause a moiré phenomenon with respect to a periodic pattern of a pixel electrode 161 described later. . Here, as a specific example of the non-periodic pattern of the partition wall 12, for example, a pattern of the partition wall 12 in which the plurality of cells partitioned by the partition wall 12 have different shapes. In this case, the shape may be different for all the cells, or the shape may be different for only some of the cells. In addition, the method of changing the cell shape may or may not have periodicity.

  The width of the top surface of the partition wall 12 is 9 μm to 50 μm, preferably 9 μm to 20 μm. 9 μm is the lower limit of the line width at which the partition wall 12 can be patterned without falling down. When the width of the top surface of the partition wall 12 is less than 9 μm, in a pattern in which the length of the partition wall 12 is 60 μm or more, at least a part of the partition wall 12 falls, peels off, or the separated partition wall 12 moves over the substrate. Or move. In that case, the function of preventing the movement of particles by the partition wall 12 is lost, and the display quality is deteriorated. On the other hand, the upper limit of 50 μm, which is the upper limit of the preferred range, is an upper limit at which the partition wall 12 is not too conspicuous when visually observed.

  Here, the definition of the width of the top surface of the partition wall 12 is shown in FIG. If the corners of the top surface are not rounded, the width of the top surface is defined as it is, as shown in FIGS. 5 (a) and 5 (b). On the other hand, when the corner of the top surface is rounded, it is understood as the width between the intersection lines of the extended surface of the top surface and the extended surface of the wall surface, as shown in FIG. 5 (c) and FIG. 5 (d). The As a measuring method for evaluation, one substrate 11 on which the partition wall 12 was formed was embedded in a curable resin, and a cross section of the partition wall 12 was cut out by a microtome (Daiwa Kogyo Kogyo Co., Ltd .: FX-801). Each width can be measured based on an image taken by a scanning electron microscope (SEM).

  The thickness of the partition wall 12 is 5 to 50 μm, preferably 10 to 50 μm. If the thickness is 5 μm or less, the amount of ink to be filled is small and sufficient display characteristics, particularly contrast, cannot be obtained. From the viewpoint that good display characteristics can be obtained at a low driving voltage, a thickness in the range of 10 to 50 μm is preferable.

  The cell aperture ratio is preferably 70% or more, and particularly preferably 90% or more. The higher the aperture ratio, the wider the displayable area, so that high contrast can be obtained.

  Next, the adhesive layer 22 is formed on the partition wall 12 (adhesive layer forming step: step (2) in FIG. 2). In this adhesive layer forming step, a thermoplastic resin such as a polyester-based thermoplastic adhesive is formed with a thickness of 1 μm to 100 μm by, for example, a transfer method or a printing method. Preferably, it is formed with a thickness of 1 μm to 50 μm, particularly preferably with a thickness of 1 μm to 20 μm.

  Supplementing a specific description of an example of a typical thermal transfer method as a transfer method, as shown in FIG. 6, for example, a polyester-based thermoplastic adhesive having a thickness of 20 μm on a PET film as a substrate 21. A transfer sheet 20 on which an adhesive 221 is formed is prepared. Next, the transfer sheet 20 is arranged to face the one substrate 11 so that the surface of the adhesive 221 is arranged on the top surface of the partition wall 12 of the one substrate 11. In this state, one substrate 11 and the transfer sheet 20 are laminated at a normal temperature and a pressure of 1 kPa. After laminating, one substrate 11 was oriented such that the end of the partition wall 12 on the one substrate 11 side was positioned higher than the top surface of the partition wall 12 on the side opposite to the one substrate 11. In this state, the one substrate 11 and the transfer sheet 20 are heated for one minute at a temperature higher than the softening point or melting point of the adhesive 221. Thereby, the adhesive layer 22 is formed on the partition wall 12.

  As the adhesive 221 for forming the adhesive layer 22, an adhesive using a thermoplastic material is preferable. It has a property of softening by heating and solidifying when cooled, and is plastic when repeated cooling and heating. Is a material that is reversibly maintained.

  When an adhesive made of a thermoplastic material is used as an adhesive layer, the adhesive 221 solidified on the transfer sheet substrate 21 is softened by heating to a temperature exceeding its softening point or melting point, The adhesive 221 can be reliably thermally transferred only to the top surface of the partition wall. Further, since the adhesive 221 after thermal transfer is cooled to room temperature and solidified again, tackiness, i.e., stickiness, is eliminated. Further, since there is no tack, that is, stickiness, the display medium 13 filled in the cell does not adhere to the adhesive 221. The adhesive 21 on the top surface of the partition wall is again heated to a temperature exceeding its softening point or melting point to be softened, so that it has tackiness, that is, stickiness, so that it is securely bonded to the other substrate 16. The Since the adhesive 221 after being bonded to the other substrate 16 is not tacked again at room temperature, that is, has no stickiness, the display medium 13 is not bonded to the adhesive 221 again, and the display quality may be deteriorated. Nor.

  Specifically, thermoplastic base polymers such as ethylene-vinyl acetate copolymer, polyester, polyamide, polyolefin, polyurethane, natural rubber, styrene-butadiene block copolymer, styrene-isoprene block copolymer, styrene-ethylene. A resin mainly composed of a thermoplastic elastomer such as a butylene-styrene block copolymer or a styrene-ethylene-propylene-styrene copolymer, and a tackifier resin or a plasticizer is mainly used.

  In order to improve the adhesion between the partition wall 12 and the adhesive 221, the partition wall 12 may be subjected to a surface treatment by ultraviolet irradiation, plasma treatment, or the like, or a primer may be formed. Alternatively, a silane coupling agent may be added to the adhesive 221.

  Next, the ink 13 as a display medium is placed on one substrate 11 (display medium placement step: step (3) in FIG. 2). FIG. 7 is a diagram schematically showing an example of the display medium arranging step. Here, (1) the ink 13 is dropped from the dispenser 31 or inkjet or die coat (ink dropping step), and (2) the ink 13 is made uniform in the surface by the applicator 32 or doctor blade, doctor knife, and central squeegee. It is applied (ink application process). The ink 13 may be disposed on one substrate 16.

  As the display medium 13, a display medium containing at least one or more kinds of electrically responsive materials can be used. Examples of the electroresponsive material include a charged particle material and a liquid crystal material, and the charged particle material includes a so-called electrophoretic material in which colored particles such as white, black, and color move in response to an electric field, or two particles. There are materials typified by twist balls that are color-coded and rotated by an electric field, or nanoparticle materials that move by an electric field. On the other hand, the liquid crystal material includes a material for electrically controlling transmission and scattering known as PDLC (Polymer Dispersed Liquid Crystal), a material in which a liquid crystal is mixed with a dye, a cholesteric liquid crystal material, and the like. These materials that have electrical responsiveness and change optical characteristics need to be isolated into cells regardless of the type, and are subject to application of the present invention.

  Returning to FIG. 2, after the display medium placement step, a conductive paste application step is performed (conductive paste application step: step (4) in FIG. 2). FIG. 8 is a schematic view for explaining the function of the conductive paste. The conductive paste 14 is a metal paste such as a silver paste, and is applied to a predetermined position by, for example, a dispenser 41 or ink jet, tampo printing, pad printing, or stacking printing. As shown in FIG. 8, the conductive paste 14 functions as a wiring for applying a voltage to the other substrate 16. When a predetermined electric field (voltage) is applied between the translucent electrode of one substrate 11 and the pixel electrode 161 of the other substrate 16, the electrically responsive material in the ink 13 which is a display medium is driven, and the characters Desired information such as a pattern is displayed. Thereafter, even if the electric field is no longer applied, the information display state is maintained until a new electric field is applied between the two substrates.

  Next, the TFT electrode structure 163 and the pixel electrode 161 are formed in a periodic pattern on the other substrate 16 (pixel electrode forming step: step (5) in FIG. 2). In the present embodiment, the pixel electrodes 161 are formed in a matrix-like periodic pattern as shown in FIG.

  Here, the configuration of the pixel electrode 161 and the TFT electrode structure 163 of this embodiment will be described in more detail with reference to FIGS.

  FIG. 10 is a diagram schematically showing the pixel electrode 161, the TFT electrode structure 163 corresponding to the pixel electrode 161, and the insulating film 164 disposed between the TFT electrode structure 163 and the pixel electrode 161. . Specifically, FIG. 10A is a plan view showing the pixel electrode 161 disposed on the TFT electrode structure 163, and FIG. 10B is a cross-sectional view taken along the line 10b-10b in FIG. In this state, the pixel electrode 161 disposed on the TFT electrode structure 163 via the insulating film 164 is electrically connected to the corresponding TFT electrode structure 163 by the via hole 162 formed in the pixel electrode 161. FIG.

  First, a plurality of TFT electrode structures 163 are arranged on the other substrate 16 so as to correspond to the matrix pattern of the pixel electrodes 161 shown in FIG. 9, and the plurality of TFT electrode structures 163 are arranged on the plurality of TFT electrode structures 163. An insulating film 164 is formed so as to cover the TFT electrode structure 163. In the present embodiment, the insulating film 164 includes a passivation (PV) layer 164pv formed of a resin having a high light transmittance and a black matrix (BM) layer 164bm formed of a resin having a low light transmittance. Yes.

  Here, the “light transmittance” refers to an average value of the rate at which light passes through the object from one side of the object toward the other side. The light transmittance can be measured, for example, using a near-infrared microspectrophotometer (Olympus: USPM-RU-W). In the present embodiment, with respect to light having a wavelength in the range of 400 nm to 800 nm, the ratio of light having various wavelengths that are different by 10 nm each passing through the object from one side to the other is determined for each wavelength light. The average value of the measured values obtained by measurement is defined as the light transmittance of the object.

  Below, the light transmittance of each material is the direction from the side where one substrate 11 of the material is arranged toward the other substrate 16 or the side where one substrate 11 is arranged from the other substrate 16 side. It is described as the light transmittance in the direction toward.

  The BM layer 164bm is formed so as to cover a plurality of TFT electrode structures 163 except for a portion where the TFT electrode structure 163 and the pixel electrode 161 corresponding to the TFT electrode structure 163 are electrically connected. The BM layer 164bm may be formed so as to cover the entire surface of the other substrate 16 between the other substrate 16 and the TFT electrode structure 163. In this case, the BM layer 164bm may be further formed between the TFT electrode structure 163 and the pixel electrode 161 so as to cover at least the TFT.

  Then, the pixel electrode 161 is formed on the insulating film 164 so as to correspond to each TFT electrode structure 163. As shown in FIG. 10, each pixel electrode 161 is formed with a via hole 162 for electrically connecting the pixel electrode 161 and the TFT electrode structure 163 corresponding to the pixel electrode 161.

  The material of the pixel electrode 161 or the material of the pixel electrode 161 and the insulating film 164 is selected so as to suppress the occurrence of the moire phenomenon. Here, with reference to FIGS. 11 and 12, the material of the pixel electrode 161 or the combination of the material of the pixel electrode 161 and the material of the insulating film 164 for effectively suppressing the occurrence of the moire phenomenon will be described. To do.

  FIG. 11 is a diagram for explaining the mechanism of the occurrence of the moire phenomenon. According to the knowledge obtained by the present inventor, the moire phenomenon is caused by the following two periodic patterns when viewed from the one substrate 11 side toward the other substrate 16 side, as shown in FIG. This is caused by being visually recognized. The first pattern is visually recognized corresponding to the periodic pattern of the partition walls 12 or, when the partition walls 12 are formed of a material having a high light transmittance, corresponding to the partition walls 12 formed of the periodic pattern. It is the periodic pattern of the high transmittance part with high light transmittance. In the second pattern, the light reflection characteristics of the pixel electrodes 161 periodically arranged on the insulating film 164 of the other substrate 16 are significantly different from the light reflection characteristics of the region 166 between the pixel electrodes 161. It is a pattern of the periodic change of the light reflection characteristics that is visually recognized. That is, when the first pattern and the second pattern overlap with each other with different periods and rotational deviations, periodic shading occurs when viewed from the one substrate 11 side, which is the cause of the occurrence of the moire phenomenon. It is thought that.

  Accordingly, as shown in FIG. 12, the difference in light reflection characteristics between the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161 is reduced, and periodic light is generated on the other substrate 16. It is considered that the occurrence of the moire phenomenon is suppressed if the formation of the reflection characteristic change pattern is suppressed.

  Therefore, in order to suppress the occurrence of the moire phenomenon, the material of the pixel electrode 161 or the pixel electrode is set so that the light reflection characteristic of the pixel electrode 161 and the light reflection characteristic of the region 166 between the pixel electrodes 161 are substantially the same. 161 and the material of the insulating film 164 are selected.

  Here, in the present embodiment, the light reflection characteristic is a color tone. The difference in color tone can be measured using, for example, a near-infrared microspectrophotometer (Olympus: USPM-RU-W). In the present embodiment, with respect to light within a wavelength range of 400 nm to 800 nm, the reflectance of each wavelength of light having different wavelengths by 10 nm is measured for each wavelength of light, and the obtained measurement values are obtained. The average value is defined as the average reflectance of the object. Similarly, with respect to two objects, the reflectance of each object of various wavelengths of light having a wavelength range of 400 nm to 800 nm and different wavelengths by 10 nm is measured for each wavelength of light, and the same wavelength. The absolute value of the difference in reflectance between the two objects is obtained for each light, and the average value of the obtained absolute values is defined as the difference in average reflectance between the two objects. Since the difference in the average reflectance is smaller as the difference in color tone between the two objects is smaller, it can be used as a value representing the difference in color tone between the two objects. In the present embodiment, when the difference in average reflectance, which is a value representing the difference in color tone, is within 30%, the color tone of the two objects is evaluated to be substantially the same.

  In the present embodiment, the BM layer 164bm of the insulating film 164 is formed of a material having a low transmittance of 10% or less, preferably 5% or less, and thus the other substrate than the BM layer 164bm. The element arranged on the side of 16 and the light reflected by the other substrate 16 are sufficiently blocked. Therefore, the color tone of the other substrate 16 on which the insulating film 164 is formed is a portion where the via hole 162 is electrically connected when viewed from the side on which the insulating film 164 is formed toward the other substrate 16 side. Is substantially the same as the color tone of the BM layer 164bm. If a material having a high light transmittance of 80% or more is selected as the material of the pixel electrode 161 disposed on the insulating film 164 including such a BM layer 164bm, the pixel electrode 161 becomes an insulating film. Since the light reflected by 164 is sufficiently transmitted, the color tone of the region excluding the via hole 162 in the pixel electrode 161 and the color tone of the region 166 between the pixel electrodes 161 are substantially the same. Here, as a material for forming the pixel electrode 161 having high transmittance, for example, a transparent conductive polymer such as an indium oxide, a zinc oxide, or PEDOT, and a resin containing silver nanowires can be given.

  In this case, if a color tone to be emphasized when performing desired display of the reflective display device is selected as the color tone of the BM layer 164bm, the desired color tone can be displayed clearly.

  Note that the pixel electrode in which the light reflection characteristics of the region where the pixel electrode 161 is formed and the light reflection property of the region 166 between the pixel electrodes 161 of the substrate 16 on which the pixel electrode 161 is formed are substantially the same. As the material of 161, or the material of the pixel electrode 161 and the insulating film 164, other materials can be employed.

  For example, when the BM layer 164bm is formed of a material having a low transmittance of 10% or less as in this embodiment, the material of the pixel electrode 161 has substantially the same light reflection characteristics as the BM layer 164bm. A material having a low transmittance of 10% or less can be selected. In this case, the pixel electrode 161 sufficiently blocks light reflected by the insulating film 164 when viewed from the pixel electrode 161 side toward the other substrate 16 side. It is suppressed that the color tone is affected by the color tone of the insulating film 164. For example, when the BM layer 164bm is formed of a titanium oxide black matrix, if carbon is selected as the material of the pixel electrode 161, the titanium oxide black matrix and carbon have the same color tone and are made of carbon. The pixel electrode 161 is sufficiently shielded from the reflected light from the insulating film 164 side when viewed from the pixel electrode 161 side toward the other substrate 16 side, and is not affected by the color tone of the insulating film 164. The color tone of the pixel electrode 161 and the color tone of the insulating film 164 are substantially the same. As a result, the color tone of the pixel electrode 161 and the color tone of the region 166 between the pixel electrodes 161 are substantially the same. Further, in this case, a portion where the via hole 162 of the TFT electrode structure 163 is electrically connected, that is, a portion not covered with the BM layer 164bm can be prevented from being seen from the pixel electrode 161 side.

  Furthermore, also in this case, if a color tone to be emphasized when performing a desired display of the reflective display device is selected as the color tone of the BM layer 164bm and the pixel electrode 161, the desired color tone can be clearly displayed.

  Thereafter, the adhesive layer 22 on the partition wall 12 and the other substrate 16 facing the one substrate 11 are bonded while extruding excess ink exceeding the cell volume in the partition wall 12 (opposing substrate placement step: FIG. Step 2 (6)). Thereby, the display medium (ink 13) is sealed in each cell. The positioning of one substrate 11 and the other substrate 16 does not have to be precisely performed using a microscope or the like. For example, the alignment mark provided on one substrate 11 and the other substrate 16 are not provided. The alignment mark provided on the substrate may be observed and matched with the naked eye.

  In the counter substrate bonding step, as shown in FIG. 13, the adhesive 221 transferred as the adhesive layer 22 is heated to obtain an adhesive force. Specifically, the partition wall 12 and the other substrate are softened by heating the adhesive 221 from the periphery to a temperature exceeding the softening temperature while applying a predetermined thermocompression bonding pressure (laminating pressure) by the laminator 91. 16 is bonded. However, other thermocompression bonding modes may be employed.

  Further, in the present embodiment, after bonding by the laminator 91, a four-side thermocompression bonding process is performed in which the four sides (peripheral portions) of both the substrates 11 and 16 are further thermocompression bonded. Specifically, a hot plate 92 is laid under the four sides (peripheral parts) of both substrates 11 and 16, and the lamination pressure is applied to the four sides of both substrates 11 and 16 with metal pieces 93 from the inside to the outside. Will be implemented.

  Thereafter, as shown in FIG. 2, the sheet is cut into a predetermined size by a cutting device 51 such as a guillotine, an upper blade slide device, a laser cutting device, or a laser cutter (cutting step: step (7) in FIG. 2) and desired reflection. The production of the mold display device is completed.

  As described above, according to the present embodiment, the light reflection characteristic of the region excluding at least the via hole 162 in the pixel electrode 161 and the light reflection property of the region 166 between the pixel electrodes 161 are substantially the same. The visibility of the period of the pattern of the pixel electrode 161 from the substrate 11 side is reduced. Thereby, the expression of the moire phenomenon is suppressed.

  An insulating film 164 is provided in a region 166 between the pixel electrodes 161 and a region on the other substrate 16 side of each pixel electrode 161, and the insulating film 164 has a low transmittance of 10% or less. The pixel electrode 161 includes a layer 164bm, and is formed using a material having a high transmittance of 80% or more. In this case, since the pixel electrode 161 sufficiently transmits the light reflected by the insulating film 164, the light reflection characteristic of the region where the pixel electrode 161 is disposed should be substantially the same as the light reflection characteristic of the insulating film 164. Easy. As a result, it is easy to make the light reflection characteristics of the region where the pixel electrode 161 is formed substantially the same as the light reflection property of the region 166 between the pixel electrodes 161.

  Note that the object of the present invention can be achieved even when the pixel electrode 161 is formed of a material having a low transmittance of 10% or less. That is, if the pixel electrode is formed of the low-transmittance material, the pixel electrode 161 sufficiently blocks light reflected by the insulating film 164, so that the light reflection characteristics of the region where the pixel electrode 161 is disposed The influence of the light reflection characteristics of the insulating film 164 is suppressed. Therefore, the light reflection characteristics of the pixel electrode 161 and the light reflection characteristics of the insulating film 164 can be made substantially the same. As a result, it is easy to make the light reflection characteristics of the pixel electrodes 161 and the light reflection characteristics of the region 166 between the pixel electrodes 161 substantially the same.

  Further, if the color tone of the BM layer 164bm or the color tone of the BM layer 164 and the pixel electrode 161 is set to the same color tone as that to be emphasized when performing a desired display on the reflective display device, the desired color tone becomes clearer. Can be displayed.

  Furthermore, if the partition wall 12 is formed in a pattern that does not generate moire fringes with respect to the periodic pattern of the pixel electrodes, for example, an aperiodic pattern, the occurrence of the moire phenomenon is remarkably suppressed.

  Next, practical examples actually performed will be described.

<Example of Reflective Display Device>
<Example 1>
As one substrate 11, an indium tin oxide (ITO) vapor deposition film (thickness 0.2 μm) is provided as a translucent electrode on one surface of a 300 mm × 400 mm × 0.1 mm thick PET substrate (Toyobo A4100). A prepared board was prepared. The translucent electrode is formed by a general film forming method such as sputtering, vacuum evaporation, or CVD, and in addition to indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO), etc. Can be formed.

Next, a negative photosensitive resin material (a dry film resist manufactured by DuPont MRC Dry Film Resist Co., Ltd.) is laminated on the one substrate 11 to a thickness of 20 μm and heated at 100 ° C. for 1 minute. Then, exposure is performed using an exposure mask (exposure amount: 500 mJ / cm ² ), and thereafter development using a 1% KOH aqueous solution is performed for 30 seconds, followed by baking at 200 ° C. for 60 minutes. A 20 μm partition wall 12 was formed. As the pattern of the partition walls 12, a honeycomb pattern (pitch: 300 μm) in which regular hexagonal unit patterns are regularly arranged is adopted.

  Then, a polyethylene terephthalate (PET) film 21 (manufactured by Teijin DuPont) having a thickness of 50 μm is used as the transfer film substrate 21, and a heat sealant 221 (Byron made by Toyobo Co., Ltd.) is used as the adhesive 221 for forming the adhesive layer 22. 630) was applied with a die coder with a thickness of 20 μm and dried. Thereby, a roll-shaped transfer sheet 20 having a 10 μm adhesive layer was produced. The softening temperature of the heat sealant 221 was about 110 ° C.

  Then, one substrate 11 was placed on the transfer sheet 20 with the surface on which the partition wall 12 was formed facing down, and was laminated at room temperature with a pressing force of about 1 kPa in this state. . Thereafter, the periphery of the heat sealant 221 was heated to a temperature exceeding its softening temperature, for example, about 130 ° C., and one substrate 11 was peeled from the transfer sheet 20 in that state. As a result, the heat sealant 221 was thermally transferred to the entire top surface of the partition wall 12. The height of the heat sealant 221 transferred to the top surface of the partition wall 12, that is, the height from the top surface of the partition wall 12 to the top of the heat sealant 221 was about 7 μm.

Subsequently, an ink 13 having the following components is used as a display medium, dropped from the dispenser 31, and squeezed with a central squeegee 32 (Neurong squeegee 1: made of urethane resin), and then in each cell. Filled. Excess ink that protruded in the substrate width direction was scraped off by another squeegee 33a, 33b (Nelogue Squeegee 2: made of urethane resin), and further wiped off by a roll wiper 34.
<Ink component>
・ Electrophoretic particles (titanium dioxide): 60 parts by weight ・ Dispersion liquid: 40 parts by weight

  Subsequently, a silver paste (manufactured by Fujikura Kasei Co., Ltd.) was spot-coated by a dispenser 41 on a part of the outer periphery of the partition wall pattern (2 mm × 2 mm square region).

  Next, as the other substrate 16, a substrate having an organic TFT array formed on one surface of non-alkali glass (OA-10G manufactured by Nippon Electric Glass Co., Ltd.) having a size of 300 mm × 400 mm × 0.5 mm was prepared. The organic TFT array includes a 300 nm × 300 nm square ITO pixel electrode 161 (light transmittance 80%), a TFT electrode structure 163 formed to correspond to the pixel electrode 161, and an acrylic resin (PV layer 164pv). FX-V550 manufactured by Adeka (thickness 4 μm, light transmittance 93%) and resin as BM layer 164bm (V259-BK739P manufactured by Nippon Steel Chemical Co., Ltd.) (thickness 1 μm, light transmittance 0.01% or less) And so as to include. The combined transmittance of the PV layer 164pv and the BM layer 164bm was 0.01% or less. The pixel electrodes 161 were formed in a matrix-like periodic pattern formed by 600 × 800 and aligned in the matrix direction.

  Then, in the atmosphere, the other substrate 16 is provided on the adhesive layer 22 on the partition wall 12 of the one substrate 11, and the alignment mark provided on the one substrate 11 and the other substrate 16 are provided. The alignment mark and the alignment mark were overlapped while being observed and matched with the naked eye. While applying a certain thermocompression pressure to the superposed one substrate 11 and the other substrate 16 with a laminator 91 and extruding excess ink exceeding the cell volume in the partition wall 12, The other substrate 16 was brought into close contact.

  The temperature at the time of thermocompression bonding is preferably higher than the softening point or near the melting point of the heat sealant 221, and is 80 ° C. to 150 ° C., preferably 80 ° C. to 90 ° C., and in this example, 80 ° C. The thermocompression bonding pressure is preferably 0.01 MPa to 0.7 MPa, particularly preferably 0.1 MPa to 0.4 MPa, and 0.3 MPa in this example.

Thereafter, the sheet is cut into a predetermined size by the cutting device 51, and a UV curable resin (LCB-610, manufactured by E-Heat Sea Co., Ltd.) is applied to the periphery of both substrates 11 and 16 using a dispenser (not shown). Then, it was cured by exposure to ultraviolet rays (exposure amount 700 mJ / cm ² ) (peripheral sealing treatment). Thus, a display panel was produced.

  The display quality of the display panel obtained as described above was evaluated, but there was no unevenness due to the moire phenomenon and the display was uniform.

  In addition, for the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161, the wavelength is 400 nm to 800 nm using a near infrared microspectrophotometer (Olympus: USPM-RU-W). With respect to the light in the range, the reflectance in the two regions of the light of various wavelengths having different wavelengths by 10 nm was measured for the light of each wavelength. For each region, the average value of the obtained measurement values, that is, the value representing the color tone, was obtained. The value representing the color tone of the region in which the pixel electrodes 161 were formed was 20%, and between the pixel electrodes 161 The value representing the color tone of the area 166 was 15%. Further, the absolute value of the difference in reflectance for each light of the same wavelength in the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161 is obtained, and the average value of the obtained absolute values is calculated. The average value of the absolute values, that is, the value indicating the difference in color tone was within about 5%. That is, the color difference between the two areas was substantially the same.

<Example 2>
In contrast to Example 1, a carbon electrode was formed as the pixel electrode 161 by a printing method, and the other processes were the same and a display panel was manufactured.

  The display quality of the display panel obtained as described above was evaluated, but there was no unevenness due to the moire phenomenon and the display was uniform.

  Further, in the same manner as in Example 1, a value indicating the color tone of the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161 and a value indicating the difference in color tone between the two regions are obtained. As a result, the value representing the color tone of the region where the pixel electrode 161 is formed is 4%, the value representing the color tone of the region 166 between the pixel electrodes 161 is 15%, and the difference in color tone between the two regions is shown. The represented value was within about 10%. That is, the color difference between the two areas was substantially the same.

<Example 3>
A partition panel 12 was formed in a non-periodic pattern as shown in FIG.

  The display quality of the display panel obtained as described above was evaluated, but there was no unevenness due to the moire phenomenon, and the display was more uniform than in Example 1.

  Further, in the same manner as in Example 1, a value indicating the color tone of the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161 and a value indicating the difference in color tone between the two regions are obtained. As a result, the value representing the color tone of the region where the pixel electrode 161 is formed is 20%, the value representing the color tone of the region 166 between the pixel electrodes 161 is 15%, and the difference in color tone between the two regions is shown. The represented value was within about 5%. That is, the color difference between the two areas was substantially the same.

<Comparative example>
In contrast to Example 1, an electrode having a Ti layer / Al layer / Ti layer in that order from the other substrate 16 side to the side on which the other substrate 16 is disposed is formed as the pixel electrode 161. In the same process, a display panel was manufactured.

  When the display quality of the display panel obtained as described above was evaluated, unevenness due to the moire phenomenon occurred. This is because the difference between the light reflection characteristic of the Ti layer on the one substrate 11 side of the pixel electrode 161 and the light reflection characteristic of the region 166 between the pixel electrodes 161 is too large, and the one substrate 11 side to the other. This is considered to be because the pattern of the periodic change in the light reflection characteristics of the substrate 16 was clearly recognized to such an extent that a moire phenomenon was developed with respect to the pattern of the high transmittance portion of the periodic pattern of the partition wall 12. .

  Further, in the same manner as in Example 1, a value indicating the color tone of the region where the pixel electrode 161 is formed and the region 166 between the pixel electrodes 161 and a value indicating the difference in color tone between the two regions are obtained. As a result, the value representing the color tone of the region where the pixel electrode 161 is formed is 80%, the value representing the color tone of the region 166 between the pixel electrodes 161 is 15%, and the difference in color tone between the two regions is shown. The represented value was about 60% or more. That is, the color tone of the two areas was significantly different.

11 One substrate 12 Partition 13 Ink (display medium)
14 Conductive paste 16 Other substrate 161 Pixel electrode 162 Via hole 163 TFT electrode structure 164 Insulating film 164pv Passivation (PV) layer 164bm Black matrix (BM) layer 166 Inter-pixel electrode region 20 Transfer sheet 21 PET film 22 Adhesive layer 221 Heat seal Agent 31 Dispenser 32 Applicator 33a Squeegee 33b Squeegee 34 Roll wiper 51 Cutting device 91 Laminator 92 Hot plate 93 Metal piece

Claims (5)

Desirable when a display medium containing at least one or more kinds of electrically responsive materials is sealed between two opposing substrates on which electrodes are formed, and a predetermined electric field is applied between the two substrates. A reflective display device that displays
One substrate has translucency,
A common translucent electrode that covers at least a display region, a partition wall that partitions a plurality of cells, a plurality of pixel electrodes arranged in a periodic pattern, between the one substrate and the other substrate; A plurality of electrode structures corresponding to a plurality of pixel electrodes are provided in this order when viewed from the one substrate side toward the other substrate side,
Each of the pixel electrodes is formed with a via hole for electrically connecting the corresponding pixel electrode and the electrode structure,
When viewed in the direction from the side of the one substrate toward the side of the other substrate, the light reflection characteristic of the region excluding the via hole in the pixel electrode and the light reflection property of the region between the pixel electrodes are substantially the same. A reflective display device characterized by that. Desirable when a display medium containing at least one or more kinds of electrically responsive materials is sealed between two opposing substrates on which electrodes are formed, and a predetermined electric field is applied between the two substrates. A reflective display device that displays
One substrate has translucency,
A common translucent electrode that covers at least a display region, a partition wall that partitions a plurality of cells, a plurality of pixel electrodes arranged in a periodic pattern, between the one substrate and the other substrate; A plurality of electrode structures corresponding to a plurality of pixel electrodes are provided in this order when viewed from the one substrate side toward the other substrate side,
Each of the pixel electrodes is formed with a via hole for electrically connecting the corresponding pixel electrode and the electrode structure,
Reflection characterized in that the light reflection characteristic of the pixel electrode and the light reflection characteristic of the region between the pixel electrodes are substantially the same when viewed in the direction from the one substrate side toward the other substrate side. Type display device. The reflection type display device according to claim 1, wherein the light reflection characteristic is a color tone. 4. The reflective display device according to claim 1, wherein the electrode structure is a TFT electrode structure. The reflective display device according to claim 1, wherein the partition walls are formed in an aperiodic pattern.

Images