JP2013235049A - Display device and manufacturing method of display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device hard to suffer a break and a crack in a barrier plate.SOLUTION: A display device 1 includes a first substrate 10 provided with a first electrode, a second substrate 20 provided with a second electrode facing to the first electrode, a plurality of barrier plates 32 protruding from a side of the first substrate 10 to a side of the second substrate 20 and partitioning a space between the first substrate 10 and the second substrate 20 into a plurality of unit spaces 40, and a display medium encapsulated in each of the unit spaces and including charging particles. When the width of a first end face 35, facing the second substrate 20, of the barrier plate 32 is expressed as α, the width of a second end face 36, facing the first substrate 10, of the barrier plate 32 is expressed as β, and the width of a central portion, at the hight of the middle between the first end face 35 and the second end face 36, of the barrier plate 32 is expressed as γ, the α, the β, and the γ satisfy a relation expressed by equations (1)-(3) at least at an intersection between the barrier plates 32, where the equation (1) is: (α+β)/2<γ, (2) is: γ≤β, and (3) is: α<β.

Description

  The present invention relates to a display device and a method for manufacturing the display device.

  Display devices that display by moving charged particles such as EPD (Electrophoretic Display) and QRLPD (Quick Response Liquid Powder Display) are close to zero power consumption during the display period, and power consumption during the display switching period is also very high. Since it can be made small, it has come to be widely used especially in the field of portable information terminals such as electronic paper. In this type of display device, charged particles are enclosed between a pair of substrates, and an electric field is generated between electrodes formed on the inner surface of each substrate to control the movement of the charged particles. At this time, in order to prevent the charged particles from being biased in the substrate surface, the charged particle enclosing space is partitioned by a partition wall to restrict the movement of the charged particles in the substrate surface direction (see Patent Documents 1 to 3). . Each unit space partitioned by the partition walls is called a cell.

JP 2010-262309 A JP 2009-75346 A JP 2007-322665 A

  Since the partition wall is formed using a mold transfer method such as nanoimprinting or a photolithography method, the cross-sectional shape is usually a trapezoidal shape with a tapered tip. The planar shape of the partition includes a lattice shape and a honeycomb shape, but the width of the partition is very thin, so the strength tends to be weak. For example, when the display screen is pressed, the partition breaks or cracks occur. There is a risk of doing.

  An object of the present invention is to provide a display device and a method for manufacturing the display device in which cracks and cracks of the partition walls are unlikely to occur.

  The display device of the present invention includes a first substrate on which a first electrode is formed, a second substrate on which a second electrode facing the first electrode is formed, and from the first substrate side to the second substrate side. A plurality of partition walls that project toward the first substrate and divide a space between the first substrate and the second substrate into a plurality of unit spaces, and are enclosed in the unit spaces, and the first electrode and the second electrode A display medium including charged particles that move between the first electrode and the second electrode by an electric field generated between the first electrode and the second substrate, wherein the width of the first end surface of the partition facing the second substrate is α. When the width of the second end surface of the partition facing the first substrate is β, and the width of the central portion of the partition located at the intermediate height between the first end surface and the second end surface is γ. , Α, β, and γ at least in the portion where the partition walls intersect, the formula (1) to the formula Is configured to satisfy the relation 3).

(Α + β) / 2 <γ (1)
γ ≦ β (2)
α <β (3)

  According to this structure, since the center part of a partition becomes thick, the mechanical strength of a partition increases. Therefore, it is possible to provide a display device in which partition walls are not easily cracked or cracked.

  As for the width of the first end face of the partition wall, a portion where the partition walls cross each other may be thicker than other portions.

  According to this configuration, the corner of the unit space has a rounded shape. Therefore, the charged particles are prevented from staying at the corners of the unit space, and a display device with excellent display quality is provided.

  The display device manufacturing method of the present invention includes a first step of forming a plurality of partition walls made of a semi-cured resin on a first substrate, and a display medium including charged particles in a region partitioned by the plurality of partition walls. A second step of arranging the second substrate, a third step of bonding the second substrate onto the first substrate from above the partition, and pressurizing the second substrate toward the first substrate so that the entire partition is the first partition A fourth step of curing the resin of the partition wall in a state in which the partition wall is deformed until it is in close contact with the two substrates. In the fourth step, the partition wall is pressurized and deformed, thereby The width of the first end surface facing the two substrates is α, the width of the second end surface of the partition facing the first substrate is β, and is positioned at an intermediate height between the first end surface and the second end surface. When the width of the central part of the partition wall is γ, α, β, and γ , At least in the area where the barrier rib cross each other, to satisfy following formula (1) through (3).

(Α + β) / 2 <γ (1)
γ ≦ β (2)
α <β (3)

  According to this structure, since the center part of a partition becomes thick, the mechanical strength of a partition increases. Therefore, it is possible to provide a display device in which partition walls are not easily cracked or cracked.

It is sectional drawing which shows schematic structure of the electrophoretic display apparatus which is an example of a display apparatus. It is a schematic diagram which shows the cross-sectional shape and planar shape of a partition. It is a schematic diagram for demonstrating the manufacturing method of an electrophoretic display device. It is a schematic diagram for demonstrating the manufacturing method of an electrophoretic display device. It is a schematic diagram for demonstrating the manufacturing method of an electrophoretic display device. It is a schematic diagram for demonstrating the manufacturing method of an electrophoretic display device. It is a top view which shows the other structural example of a partition.

  Embodiments of the present invention will be described below with reference to the drawings. This embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, an actual structure and a scale, a number, and the like in each structure are different.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an electrophoretic display device which is an example of the display device of the present invention.

  The electrophoretic display device (display device) 1 includes an element substrate (first substrate) 10, a counter substrate (second substrate) 20, a partition wall layer 30, and an electrophoretic layer 41.

  The element substrate 10 is a substrate in which a pixel electrode (first electrode) 12 and an insulating layer 13 are formed on an element substrate body 11. The element substrate body 11 uses a resin substrate made of an insulating resin material such as polycarbonate (PC) or polyethylene terephthalate (PET), or a glass substrate. The element substrate body 11 has a thickness in the range of 100 μm to 500 μm, for example.

  The pixel electrode 12 is connected to the pixel transistor via a wiring, and a voltage can be selectively applied to the pixel electrode 12 by turning the pixel transistor on and off. The insulating layer 13 is formed to cover the pixel transistor on the element substrate body 11.

  The pixel electrode 12 is formed on the surface of the element substrate body 11 that faces the electrophoretic layer 41. The pixel electrode 12 is made of a conductive film such as aluminum (Al) or indium tin oxide (hereinafter abbreviated as ITO). The thickness of the pixel electrode 12 is, for example, about 50 nm.

  The counter substrate 20 is a substrate in which a counter electrode (second electrode) 22 is formed on a counter substrate body 21. The counter substrate body 21 uses a transparent substrate such as a glass substrate. The counter electrode 22 is formed on the surface of the counter substrate main body 21 that faces the electrophoretic layer 41. The counter electrode 22 is made of, for example, a transparent conductive film such as ITO. In the present embodiment, the surface of the counter substrate 20 constitutes the display surface 21a of the electrophoretic display device 1, and characters, images, and the like displayed on the display screen of the electrophoretic display device 1 are viewed from the counter substrate 20 side. It can be done.

  The partition layer 30 has a plurality of partition walls 32 that project from the element substrate 10 side toward the counter substrate 20 side and partition a space sandwiched between the element substrate 10 and the counter substrate 20 into a plurality of unit spaces 40. As a material for forming the partition layer 30, for example, various resin materials such as an epoxy resin, an acrylic resin, a urethane resin, a melamine resin, and a phenol resin can be used. Hereinafter, the unit space is referred to as a cell.

  In the present embodiment, the plurality of pixel electrodes 12 are formed corresponding to one cell 40, but the present invention is not limited to this, and one pixel electrode 12 may be formed corresponding to one cell 40. .

  The electrophoretic layer 41 is a layer made of an electrophoretic material (display medium) 41A having a plurality of electrophoretic particles (charged particles) 42 and a dispersion medium 43 in which the electrophoretic particles 42 are dispersed. The electrophoretic layer 41 is formed by the electrophoretic material 41 </ b> A enclosed in the cell 40. The electrophoretic particles 42 move between the pixel electrode 12 and the counter electrode 22 by an electric field generated between the pixel electrode 12 and the counter electrode 22.

  The electrophoretic particles 42 are, for example, pigment particles, resin particles, or composite particles thereof. Examples of the pigment constituting the pigment particles include black pigments such as aniline black and carbon black, and white pigments such as titanium oxide and antimony oxide. Examples of the resin material constituting the resin particles include an acrylic resin, a urethane resin, a urea resin, an epoxy resin, polystyrene, and polyester. Examples of composite particles include those in which the surface of pigment particles is coated with a resin material or other pigment, the surface of resin particles coated with a pigment, or a mixture in which pigments and resin particles are mixed in an appropriate composition ratio. There are particles and so on. The electrophoretic particles 42 made of these various materials are dispersed in a dispersion medium, for example, in a positively or negatively charged state.

  The dispersion medium 43 is, for example, a lipophilic hydrocarbon solvent, and includes, for example, Isopar (registered trademark). That is, the dispersion medium 43 is, for example, a liquid containing any one of Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M, or a liquid in which two or more of these are mixed, or these It is the liquid which mixed any one or more of these, and the hydrocarbon solvent of another kind.

  Alternatively, the dispersion medium 43 includes, for example, aliphatic hydrocarbons such as pentane, hexane, and octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, heptylbenzene, octylbenzene, Aromatic hydrocarbons such as benzenes (alkylbenzene derivatives) having a long-chain alkyl group such as nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, pyridine, pyrazine, furan, pyrrole , Aromatic heterocycles such as thiophene and methylpyrrolidone, methyl acetate, ethyl acetate, butyl acetate, ethyl formate and other esters, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, rutile isopropyl ketone, Ketones such as clohexanone, nitriles such as acetonitrile, propionitrile, acrylonitrile, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, carboxylates or other various oils, etc. These can be used alone or as a mixture.

  FIG. 2 is a schematic diagram showing a cross-sectional shape (FIG. 2A) and a planar shape (FIG. 2B) of the partition wall 32. FIG. 2B is a view seen through the partition wall layer 30 from the counter substrate 20 side, and FIG. 2A is a view taken along the line AA in FIG.

  As shown in FIG. 2A, the partition wall 32 has a taper shape whose width tapers from the lower end portion toward the upper end portion. The cross-sectional shape of the partition wall 32 is generally trapezoidal, but the side of the trapezoid slightly bulges outward. For example, the width of the first end surface 35 of the partition wall 32 facing the counter substrate 20 is α, the width of the second end surface 36 of the partition wall 32 facing the element substrate 10 is β, and the first end surface 35 and the second end surface 36 When the width of the central portion of the partition wall 32 located at the intermediate height is γ, α, β, and γ are at least a portion where the partition walls 32 intersect with each other (portion indicated by reference numeral 35 i in FIG. 2B). It is comprised so that the relationship of Formula (1) thru | or Formula (3) may be satisfy | filled. The width of the partition wall 32 refers to the width in the direction orthogonal to the extending direction of the partition wall 32 (up and down direction and left and right direction in the example of FIG. 2B).

(Α + β) / 2 <γ (1)
γ ≦ β (2)
α <β (3).

  When the partition wall 32 is configured as described above, the central portion of the partition wall 32 is thickened, and the mechanical strength of the partition wall 32 is increased. Therefore, an electrophoretic display device in which the partition wall 32 is not easily broken or cracked is provided. In the case of this embodiment, the relationship of the above formulas (1) to (3) is not limited to any position of the partition wall 32, that is, not only in the portion indicated by reference numeral 35i in FIG. It is configured to meet. Therefore, an electrophoretic display device with higher mechanical strength is provided.

  As shown in FIG. 2B, the partition wall layer 30 is formed so that a plurality of partition walls extending in the illustrated vertical direction and a plurality of partition walls extending in the horizontal direction in the figure are orthogonal to each other. As for the width of the first end face 35 of the partition wall 32, a portion 35i where the partition walls 32 intersect each other is thicker than the other portion 35m. The planar shape of the cell 40 is generally square, but since the width of the intersecting portion 35i of the partition wall 32 is large, the four sides of the square are in a state where the central portion is slightly bulged outward. Therefore, the cell 40 has a shape with rounded corners, and this prevents the electrophoretic particles from staying in the corners 40C of the cell 40. The width of the second end face 36 of the partition wall 32 is substantially uniform throughout the partition wall.

  3 to 6 are schematic views for explaining a method for manufacturing the electrophoretic display device 1.

  First, as shown in FIG. 3, a resin 30 </ b> A that is a partition wall forming material is applied on the element substrate 10. Then, the mold 50 is pressed from above the resin 30A, and the uneven shape of the mold 50 is transferred to the resin 30A. In the mold 50, trapezoidal grooves 51 for forming partition walls are formed in a lattice shape. Then, in a state where the mold 50 is pressed against the resin 30A, the resin 30A is subjected to heat treatment or ultraviolet irradiation treatment, and the resin 30A is semi-cured.

  Here, “semi-cured” refers to a state where the resin is not completely polymerized. In the present specification, polymerizing a resin to a target degree of polymerization is referred to as “curing”, and stopping the polymerization before reaching the target degree of polymerization is referred to as “semi-curing”. Generally, when the degree of polymerization of the resin increases, the resin becomes hard, and when the degree of polymerization of the resin decreases, the resin becomes soft. By semi-curing the resin, flexibility that can be deformed by external stress can be imparted.

  FIG. 4 is a schematic diagram showing a cross-sectional shape (FIG. 4A) and a planar shape (FIG. 4B) of a partition wall 32B obtained by semi-curing the resin 30A. 4B is a view seen through the partition wall 32B from the first end face 37 side (the side opposite to the element substrate 10), and FIG. 4A is a view taken along the line BB in FIG. 4B. It is.

  As shown in FIG. 4A, when the mold 50 is peeled in a state where the resin 30 </ b> A is semi-cured, a partition wall 32 </ b> B having a trapezoidal cross section is formed on the element substrate 10. The partition wall 32 shown in FIG. 2A has a cross-sectional shape in which the central portion in the height direction swells, but the cross-sectional shape of the partition wall 32B is a substantially accurate trapezoidal shape, and the height direction of the partition wall 32B. The width of the central portion is an intermediate value between the width of the first end surface 37 of the partition wall 32B and the width of the second end surface (end surface on the element substrate) 38 of the partition wall 32B.

  The height of the partition wall 32B is slightly between the part where the partition walls 32B intersect (the part indicated by reference numeral 37i in FIG. 4B) and the other part (the part indicated by reference numeral 37m in FIG. 4B). It varies. This variation is due to the occurrence of a phenomenon called “sink” in which the height of the partition wall 32B is locally reduced when the partition wall 32B is molded with a mold. The height d ′ of the partition wall 32B in the portion where the partition walls 32B intersect and in the vicinity thereof is higher than the design height d of the partition wall 32 shown in FIG. The height of the partition wall 32B at the intermediate position 39 is lower by c than d ′. In order to prevent the occurrence of a gap between the partition wall and the counter substrate due to “sink marks”, the lowest part of the partition wall 32B is set higher than the design height d (d′−c> d). The depth of the groove 51 of the mold 50 is designed with a certain margin.

  As shown in FIG. 4B, the partition walls 32B are generally formed in a lattice shape in two directions orthogonal to each other. The width of the first end surface 37 of the partition wall 32B is equal in the portion 37i where the partition walls 32B intersect each other and the other portion 37m, and the width of the first end surface 37 of the partition wall 32B is substantially uniform throughout the partition wall. Yes. The width of the second end face 38 of the partition wall 32B is also substantially uniform throughout the partition wall.

  After the partition wall 32B is formed on the element substrate 10, as shown in FIG. 5, the electrophoretic material 41A is disposed in a region partitioned by the partition wall 32B, and is opposed to the element substrate 10 from above the partition wall 32B in a reduced pressure atmosphere. The substrate 20 is bonded. Then, as shown in FIG. 6, the counter substrate 20 is pressurized toward the element substrate 10, and the partition wall 32 </ b> B is deformed until the entire first end surface 37 of the partition wall 32 </ b> B is in close contact with the counter substrate 20. Then, heat treatment or ultraviolet irradiation treatment is performed on the partition wall 32B to completely cure the resin of the partition wall 32B. By pressurizing and deforming the partition wall 32B, the width α of the first end surface 37 of the partition wall 32B, the width β of the second end surface 38, and the height of the partition wall 32B positioned at an intermediate height between the first end surface 37 and the second end surface 38 are obtained. The width γ of the central portion is set so as to satisfy the relationships of the above-described formulas (1) to (3).

  Thus, the electrophoretic display device 1 is completed.

  According to the electrophoretic display device 1 of the present embodiment having the above configuration, the central portion of the partition wall 32 is thick, so that the mechanical strength of the partition wall 32 is increased. Therefore, it is possible to provide the electrophoretic display device 1 in which the partition wall 32 is not easily cracked or cracked. Further, since the entire first end face 35 of the partition wall 32 is in close contact with the counter substrate 20, the bonding strength between the counter substrate 20 and the partition wall 32 is increased, and the electrophoretic particles 42 are sufficiently moved in the substrate surface direction. Can be regulated.

[Deformation]

  In the above-described embodiment, the plurality of partition walls 32 are arranged in a lattice shape, and the rectangular cell 40 is surrounded by the four partition walls 32. However, the structure of the partition walls 32 is not limited thereto. For example, a structure in which the periphery of the triangular cell 40 is surrounded by three partition walls, or a structure in which the hexagonal cell 40 is surrounded by six partition walls (see FIG. 7) may be employed.

  In the above embodiment, the mold transfer method is used as a method for forming the partition wall layer 30, but is not limited thereto. For example, a photolithography method may be used as a method for forming the partition layer 30. Moreover, you may form by printing processes, such as a screen printing method, a relief printing method, and a gravure printing method.

  In the above embodiment, an electrophoretic display device using an electrophoretic material as a display medium has been described as an example of a display device, but the present invention is not limited to this. The present invention can also be applied to other display devices such as an electronic powder fluid display (QRLPD) using an electronic powder fluid (registered trademark) as a display medium.

DESCRIPTION OF SYMBOLS 1 ... Electrophoretic display device (display device), 10 ... Element substrate (first substrate), 12 ... Pixel electrode (first electrode), 20 ... Counter substrate (second substrate), 22 ... Counter electrode (second electrode) 32 ... partition wall, 32B ... partition wall, 35 ... first end surface, 36 ... second end surface, 37 ... first end surface, 38 ... second end surface, 40 ... cell (unit space), 41A ... electrophoretic material (display medium) 42 Electrophoretic particles (charged particles)

Claims (3)

A first substrate on which a first electrode is formed;
A second substrate on which a second electrode facing the first electrode is formed;
A plurality of partition walls projecting from the first substrate side toward the second substrate side and partitioning a space sandwiched between the first substrate and the second substrate into a plurality of unit spaces;
A display medium encapsulated in each unit space and including charged particles that move between the first electrode and the second electrode by an electric field generated between the first electrode and the second electrode;
The width of the first end surface of the partition wall facing the second substrate is α, the width of the second end surface of the partition wall facing the first substrate is β, and the width between the first end surface and the second end surface is intermediate. When the width of the central part of the partition wall located at the height is γ, the relationship of the formulas (1) to (3) at least in the portion where the partition wall intersects the α, the β, and the γ. A display device configured to satisfy the above.
(Α + β) / 2 <γ (1)
γ ≦ β (2)
α <β (3)   2. The display device according to claim 1, wherein a width of the first end face of the partition wall is larger at a portion where the partition walls intersect than at other portions. A first step of forming a plurality of partition walls made of a semi-cured resin on the first substrate;
A second step of disposing a display medium containing charged particles in a region partitioned by the plurality of partition walls;
A third step of bonding a second substrate onto the first substrate from above the partition;
Pressurizing the second substrate toward the first substrate, and curing the resin of the partition wall in a state where the partition wall is deformed until the entire partition wall is in close contact with the second substrate,
In the fourth step, by pressurizing and deforming the partition, the width of the first end surface of the partition facing the second substrate is α, and the width of the second end surface of the partition facing the first substrate is α. Is β, and the width of the central portion of the partition wall located at the intermediate height between the first end surface and the second end surface is γ, the α, the β, and the γ are at least between the partition walls. A method of manufacturing a display device that satisfies the relations of the formulas (1) to (3) at the intersecting portion.
(Α + β) / 2 <γ (1)
γ ≦ β (2)
α <β (3)

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