JP2010204377A - Electrophoretic display device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device having flexibility similar to that of paper, and to provide an electronic device thereof. <P>SOLUTION: In the electrophoretic display device 1 formed by bonding an electrophoretic sheet 3 having an electrophoretic display layer 31 and the display region of an element substrate 2, grooves 40 opening on at least two sides of the element substrate 2 are formed on a face of the element substrate 2 opposite to the electrophoretic sheet 3 side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device and an electronic apparatus.

  A flat display device typified by a liquid crystal display device is used in various fields such as an OA device, an information terminal, a clock, and a television by making use of features such as thinness, light weight, and low power consumption. Currently, these liquid crystal display devices including mobile phones are required to be thinner, lighter and more durable.

  On the other hand, although it is inferior to a liquid crystal display device in terms of color display and moving image display, an electrophoretic display (EPD) has attracted attention as a display body that can realize thinness, lightness, and low power consumption. This electrophoretic display (hereinafter referred to as EPD) has properties similar to paper, and is being developed as “electronic paper” for the purpose of reading.

  A microcapsule type EPD, which is a typical electronic paper, has an electrophoretic layer formed on a glass sheet (hereinafter referred to as an element substrate) on which an electric circuit such as a switching element is formed and a transparent sheet having a transparent conductive film. The electrophoretic display panel manufactured by sticking together the electrophoretic sheet which becomes through an adhesive layer is provided (for example, patent document 1).

JP 2005-114822 A

  By the way, the microcapsule type EPD is required to be flexible because it is assumed to be used like paper. The microcapsule type EPD replaces paper in that the display contrast is clear and the display image can be freely updated. However, although it has flexibility as compared with other display devices, since the glass plate is used as the element substrate as described above, its flexibility and flexibility are still lower than that of paper. There is room for improvement.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an electrophoretic display device and an electronic apparatus having flexibility closer to that of paper.

  In order to solve the above problems, an electrophoretic display device of the present invention is an electrophoretic display device in which an electrophoretic sheet having an electrophoretic display layer is bonded to a display region of an element substrate. A groove having openings on at least two sides of the element substrate is formed on a surface opposite to the electrophoretic sheet side.

  According to the present invention, by providing a groove in the element substrate, the element substrate made of glass or the like can be easily bent. When the element substrate is bent and deformed, the whole has flexibility close to that of paper, and can be applied to various products.

It is preferable that a resin having a lower elastic modulus than that of the element substrate is embedded in the groove.
According to the present invention, since the resin having a low elastic modulus is embedded in the groove, it is possible to reinforce the strength of the substrate partially thinned by the formation of the groove, and has appropriate rigidity and flexibility. An element substrate can be obtained.

It is preferable that a corner formed by the bottom surface and the wall surface of the groove is a curved surface.
According to the present invention, it is possible to prevent the element substrate from being cracked during deformation.

It is preferable that a plurality of the grooves are formed.
According to the present invention, the flexibility of an element substrate can be improved.

The plurality of grooves are preferably arranged in parallel in one direction.
According to the present invention, it is possible to allow bending deformation in one direction of the element substrate and to prevent bending deformation in the other direction.

The depth of the groove is preferably different depending on the part.
According to the present invention, for example, the curvature can be increased by increasing the depth of the groove. In this way, the degree of curvature of the element substrate can be adjusted by partially varying the depth of the groove.

It is preferable that the arrangement density of the grooves differs depending on the part.
According to the present invention, for example, by arranging the grooves densely, the curvature of the element substrate in that region can be increased. In this way, it is possible to adjust the degree of curvature of the element substrate by partially varying the groove arrangement density.

An electronic apparatus according to the present invention includes the electrophoretic display device described above.
The present invention can be applied to various products by including the above-described electrophoretic display device having high flexibility.

1 is a plan view illustrating a schematic configuration of an electrophoretic display device according to a first embodiment. 1 is a cross-sectional view illustrating a schematic configuration of an electrophoretic display device according to a first embodiment. The top view seen from the back surface side of the element substrate of 1st Embodiment. The figure which shows the state which curved the element substrate. Sectional drawing which shows the state which formed the slit-shaped groove | channel in the element substrate. Sectional drawing which shows the modification of an element substrate. The top view which shows the modification of an element substrate. Sectional drawing of the element board | substrate which varied the depth of the groove | channel according to the site | part. Sectional drawing of the element board | substrate which varied the arrangement density of the groove | channel according to the site | part. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(First embodiment)
FIG. 1 is a plan view showing a schematic configuration of an electrophoretic display device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view in FIG.
As shown in FIGS. 1 and 2, the electrophoretic display device 1 includes an electrophoretic display panel 6. The electrophoretic display panel 6 has a configuration in which the electrophoretic sheet 3 is attached to the surface of the element substrate 2.

  The electrophoretic display panel 6 is provided with a display area 7 for displaying images such as still images and moving images. A plurality of pixels arranged in a matrix are provided in the display area 7, and display is performed for each pixel. The area around the display area 7 is a non-display area 8 where no image is displayed. This non-display area 8 is not provided with pixels, but is provided with drive circuit elements, terminals, etc. (not shown).

  The element substrate 2 has a drive layer 21 including a base material 20, a pixel electrode 25 formed on the base material 20, a switching element (not shown), and the like. The base material 20 is a plate-like member having a thickness of about 30 μm to 100 μm, for example. As a constituent material of the base material 20, for example, an inorganic substrate such as a glass substrate, a quartz substrate, a silicon substrate, a gallium arsenide substrate, polyimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), Examples thereof include plastic substrates (resin substrates) composed of polycarbonate (PC), polyethersulfone (PES), aromatic polyester (liquid crystal polymer), and the like.

  The drive layer 21 is formed in an area corresponding to the display area 7 in the base material 20. In the driving layer 21, pixel electrodes 25 provided in each pixel, switching elements, data lines (not shown), scanning lines connected to the switching elements, and the like are formed. A planar formation region of the drive layer 21 substantially coincides with the display region 7, and the drive circuit elements 22 and 23 are provided on the peripheral portion (non-display region 8) of the drive layer 21. These drive circuit elements 22 and 23 are electrically connected to data lines and scanning lines, and supply signals to the drive layer 21.

  A plurality of terminals 24 are provided at the end portion (right end in the drawing) of the element substrate 2 and are connected to the drive circuit elements 22 and 23 by wiring (not shown) formed on the element substrate 2. The terminal 24 is connected to an external circuit board (not shown).

The electrophoretic sheet 3 includes a transparent substrate 30, a common electrode 35, an electrophoretic layer 31 as an electro-optical layer, and an adhesive layer 33.
The transparent substrate 30 is a light-transmitting substrate that holds the electrophoretic layer 31 and has a thickness of about 25 μm to 200 μm, for example.

  Examples of the constituent material of the transparent substrate 30 include materials having high light transmittance such as acrylic resin, polyethylene terephthalate (PET), polyethersulfone (PES), and polycarbonate (PC). For example, a moisture-proof sheet (not shown) may be disposed on the surface 30a of the transparent substrate 30.

  The common electrode 35 is an electrode made of a conductive material having high light transmittance such as ITO. The common electrode 35 is formed over substantially the entire inner surface 30 b of the transparent substrate 30. The vertical conductive material 9 is connected to the common electrode 35. The vertical conduction member 9 is electrically connected to the element substrate 2. The common electrode 35 is in a state of being electrically connected to the element substrate 2 through the vertical conduction member 9.

The electrophoretic layer 31 has a plurality of microcapsules 32.
The microcapsule 32 is a substantially spherical capsule in which an electrophoretic dispersion is enclosed, and the diameter of each capsule is substantially the same (30 μm to 100 μm). Examples of the material constituting the capsule wall film of the microcapsule 32 include compounds such as a gum arabic / gelatin composite film, a urethane resin, a urea resin, and a urea resin. The electrophoretic dispersion liquid enclosed in the microcapsule 32 includes a plurality of electrophoretic particles and a liquid layer dispersion medium for dispersing the electrophoretic particles.

  Examples of the liquid layer dispersion medium include water, alcohol solvents, various esters, ketones, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, carboxylates, and other various oils. It is possible to use a mixture of a surfactant or the like alone or a mixture thereof.

  As the electrophoretic particles, organic or inorganic particles (polymer or colloid) having a property of moving by electrophoresis due to a potential difference in a liquid phase dispersion medium can be used. Specifically, black pigments such as carbon black and aniline black, white pigments such as titanium dioxide, monoazo azo pigments, yellow pigments such as isoindolinone, monoazo azo pigments, red pigments such as quinacridone red, phthalocyanine One or more of blue pigments such as blue and green pigments such as phthalocyanine green can be used. These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, charge control agents composed of particles such as compounds, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added.

  In the microcapsule 32, for example, two types of electrophoretic particles of titanium dioxide which is a white pigment and carbon black which is a black pigment are encapsulated, one of which is negatively charged and the other of which is positively charged. Of course, other electrophoretic particles may be used, or only one type of electrophoretic particle may be used, and the electrophoretic particles may be moved to the common electrode side or the pixel electrode 25 side so that display is possible. .

  The adhesive layer 33 is an adhesive that also serves as a binder. As the adhesive layer 33, for example, it is preferable to use an adhesive having good affinity for the capsule wall film of the microcapsule 32, excellent adhesiveness to the common electrode 35 and the pixel electrode 25, and good insulating properties.

  In the electrophoretic display device 1 of the present embodiment, a region where the pixel electrodes 25 are arranged is a display region 7 in plan view. In the display area 7, the formation area of each pixel electrode 25 in a plan view is a pixel area, and an image such as a still image or a moving image is displayed for each pixel area. The periphery of the display area 7 is a non-display area 8 where no image is displayed.

  In the present embodiment, the element substrate 2 is easily curved by providing the lattice-shaped grooves 40 on the back surface 20b side of the element substrate 2. As shown in FIG. 3, the lattice-like grooves 40 are configured by a plurality of grooves 40 a and 40 b arranged at a predetermined pitch in each of the short side direction and the long side direction of the base material 20. Both ends of 40 b are open on at least two sides of the substrate 20. Here, the grooves 40 a and 40 b are formed by etching the base material 20 so that a plurality of prismatic protrusions 43 are scattered.

  The grooves 40a and 40b are formed with a width W of 0.2 mm and a pitch of 1 mm, and the depth t is 0.2 mm to 0.4 mm with respect to a substrate having a thickness of 0.3 mm to 0.5 mm. ing. The thickness of the base material in the grooves 40a and 40b can be easily reduced by reducing the thickness to about 0.1 mm. However, if the thickness is too thin, the mechanical strength is not preferable.

  A filling member 44 is embedded in the grooves 40a and 40b. As the filling member 44, a resin having a lower elastic modulus than that of the substrate 20 is selected, and examples thereof include a silicone resin. When glass is used for the base material 20, the elastic modulus of the base material 20 is several GPa, and when silicone resin is used for the filling member 44, the elastic modulus of the filling member 44 is approximately several. MPa. The elastic modulus of the filling member 44 can be appropriately changed according to the strength of the base material 20 on which the grooves 40a and 40b are formed, and may be 1 MPa or less if the strength of the base material 20 is sufficient. By filling the grooves 40a and 40b with an elastic resin, the element substrate 2 partially thinned by the formation of the grooves 40a and 40b can be reinforced, and the element substrate 2 having appropriate rigidity and flexibility. It can be.

  Although not shown in FIG. 2, a frame member in which the electrophoretic sheet 3 on the element substrate 2 is disposed at the peripheral edge of the element substrate 2 and a surface protection disposed to face the element substrate 2. It is desirable to seal with a member to ensure moisture resistance to the electrophoretic layer 31.

Next, the operation of the electrophoretic display device 1 configured as described above will be briefly described.
When a voltage is applied between the pixel electrode 25 and the common electrode 35 so that the voltage of the common electrode 35 becomes relatively high, the positively charged black electrophoretic particles are out of the pixels in the microcapsule 32 by the Coulomb force. It is drawn toward the electrode 25 side. On the other hand, negatively charged white electrophoretic particles are attracted toward the common electrode 35 in the microcapsule 32 by Coulomb force. As a result, white electrophoretic particles gather on the transparent substrate 30 side in the microcapsule 32, and the color (white) of the white electrophoretic particles is displayed in the display area 7 of the electrophoretic display device 1. The Rukoto.

  On the contrary, when a voltage is applied between the pixel electrode 25 and the common electrode 35 so that the potential of the pixel electrode 25 becomes relatively high, the negatively charged white electrophoretic particles are moved to the pixel electrode 25 side by Coulomb force. Be drawn to. On the other hand, the positively charged black electrophoretic particles are attracted toward the common electrode 35 by the Coulomb force. As a result, the black electrophoretic particles gather on the transparent substrate 30 side in the microcapsule 32, and the color (black) of the black electrophoretic particles is displayed in the display area 7 of the electrophoretic display device 1. It will be.

  In the electrophoretic display device 1 of this embodiment, the element substrate 2 made of glass or the like is easily bent by providing the lattice-shaped grooves 40 on the back surface side of the element substrate 2. That is, when the grooves 40a and 40b are deformed in a narrowing direction or a widening direction, the element substrate 2 is freely curved as shown in FIG. As a result, the electrophoretic display device 1 is more flexible than paper. The degree of curvature of the element substrate 2 can be controlled by changing the cross-sectional shape, size (width W), and pitch of the groove 40.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

As described above, the degree of curvature of the element substrate 2 can be controlled by changing the shape and pitch of the grooves 40 (40a, 40b).
For example, in the embodiment described above, the lattice-like grooves 40 are provided in a plan view, but the present invention is not limited to this, and any structure that can exhibit the same effect may be used. For example, as shown in FIG. 5, it may be slit-like grooves 51 arranged at equal intervals only in one direction. The slit-shaped groove 51 allows bending in only one direction, and is effective when it is desired to prevent bending in the other direction. Note that the lattice-like grooves 40 in the present embodiment described above have an advantage in that the degree of freedom of bending is higher than that of the slit-like grooves 51, and flexibility close to that of paper can be obtained.

  Further, in the previous embodiment, the cross section is not a substantially rectangular groove, and the corner portion 53 of the groove 52 may be curved into an R shape in a cross sectional view as shown in FIG. That is, as shown in FIG. 7, by forming the grooves 52 so that the columnar protrusions 54 of a predetermined height are scattered, the corner portions 53 (the protrusions 54) of the grooves 52 when the element substrate 2 is deformed. It is possible to prevent stress from being applied locally at the boundary between the groove 52 and the groove 52. As a result, it is possible to prevent the element substrate 2 from cracking and being damaged starting from the corner portion 53 of the groove 52 when being bent. Further, when the filling member 44 is filled, bubbles are prevented from being mixed into the corner portion 53 of the groove 51, and the filling property of the filling member 44 can be improved.

  The cross-sectional shape of the groove is not limited to this, and other shapes may be used as long as the same effect can be exhibited. For example, the cross section may be a trapezoidal polygonal groove or a hemispherical groove, or grooves having different cross sectional shapes may be mixed.

In the previous embodiment, the grooves 40a and 40b having a certain depth are provided. However, as shown in FIG. 8, a plurality of grooves 42a having different depths may be mixed depending on the part. Specifically, it is possible to increase the flexibility by increasing the depth of the groove 42a in the region of the element substrate 2 where the curvature rate is to be increased, and conversely, for the portion that is desired to have an appropriate rigidity. What is necessary is just to make the depth of the groove | channel 42a shallow. As an example, the groove 42a near the center of the element substrate 2 may be formed shallower than the groove 42a near the end. In this way, it is possible to relatively improve flexibility in the vicinity of the end portion that is relatively difficult to deform. The reason why the vicinity of the end portion is not easily deformed is that the force point, the fulcrum, and the action point are concentrated at relatively close positions when the deformation is attempted by a human hand. Conversely, the groove 42a near the end of the element substrate 2 may be formed shallower than the groove 42a near the center. In this way, the vicinity of the central portion can be easily deformed to ensure flexibility, and the vicinity of the end portion is hardly deformed, and the end portion that is easily damaged can be protected.
Alternatively, the depth may be changed in one groove by giving an inclination to the bottom of each groove.

Furthermore, in the previous embodiment, the grooves 40a and 40b were formed at a constant pitch. However, as shown in FIG. ) May be controlled. The region where the arrangement density of the grooves 43a is high has higher flexibility than the region where the arrangement density is low. As an example, the arrangement density of the grooves 43a near the center of the element substrate 2 may be smaller than the arrangement density of the grooves 43a near the end. In this way, it is possible to relatively improve flexibility in the vicinity of the end portion that is relatively difficult to deform. Conversely, the arrangement density of the grooves 43a near the end of the element substrate 2 may be smaller than the arrangement density of the grooves 43a near the center. In this way, the vicinity of the central portion can be easily deformed to ensure flexibility, and the vicinity of the end portion is hardly deformed, and the end portion that is easily damaged can be protected.
In addition, you may combine suitably the structure of each groove | channel described above.

  Further, as the filling member 44 embedded in the groove 40, a gel-like body, a liquid, or the like can be used instead of the elastic resin. When using these gel-like bodies, liquids, or the like, it is preferable to seal the opening of the groove 40 with a flexible film so that the filling member 44 does not leak out when the substrate is deformed.

  In the previous embodiment, the grooves 40 a and 40 b are formed by etching the base material 20. However, the present invention is not limited to this and may be formed by machining.

(Electronics)
Next, the case where the electrophoretic display device 1 of the above embodiment is applied to an electronic device will be described.
FIG. 10 is a front view of the wrist watch 1000. The wrist watch 1000 includes a watch case 1002 and a pair of bands 1003 connected to the watch case 1002.
A display unit 1005 including the electrophoretic display device 1 of each of the above-described embodiments, a second hand 1021, a minute hand 1022, and an hour hand 1023 are provided on the front surface of the watch case 1002. On the side surface of the watch case 1002, a crown 1010 and an operation button 1011 are provided as operation elements. The crown 1010 is connected to a winding stem (not shown) provided inside the case, and is integrally provided with the winding stem so that it can be pushed and pulled in multiple stages (for example, two stages) and can be rotated. . The display unit 1005 can display a background image, a character string such as date and time, or a second hand, a minute hand, and an hour hand.

  FIG. 11 is a perspective view illustrating a configuration of the electronic paper 1100. An electronic paper 1100 includes the electrophoretic display device 1 of the above embodiment in a display area 1101. The electronic paper 1100 is flexible and includes a main body 1102 made of a rewritable sheet having the same texture and flexibility as conventional paper.

  FIG. 12 is a perspective view showing a configuration of the electronic notebook 1200. An electronic notebook 1200 is obtained by bundling a plurality of the electronic papers 1100 and sandwiching them between covers 1201. The cover 1201 includes display data input means (not shown) for inputting display data sent from an external device, for example. Thereby, according to the display data, the display content can be changed or updated while the electronic paper is bundled.

  According to the wristwatch 1000, the electronic paper 1100, and the electronic notebook 1200 described above, since the electrophoretic display device 1 according to the present invention is employed, a display with excellent reliability that can maintain display quality over a long period of time. It becomes an electronic device provided with a section.

  In addition, said electronic device illustrates the electronic device which concerns on this invention, Comprising: The technical scope of this invention is not limited. For example, the electrophoretic display device 1 according to the present invention can be suitably used for a display unit of an electronic device such as a mobile phone or a portable audio device.

DESCRIPTION OF SYMBOLS 1 ... Electrophoretic display device, 2 ... Element substrate, 3 ... Electrophoresis sheet, 6 ... Electrophoretic display panel, 30 ... Transparent substrate, 31 ... Electrophoresis layer, 40 ... Lattice-like groove | channel, 40a, 40b, 42a, 43a ... Groove, 53 ... Corner, 44 ... Filling member, W ... Width, t ... Depth, 1000, 1100, 1200 ... Electronic equipment

Claims (8)

An electrophoretic display device in which an electrophoretic sheet having an electrophoretic display layer is bonded to a display region of an element substrate,
An electrophoretic display device, wherein grooves are formed on at least two sides of the element substrate on a surface opposite to the electrophoretic sheet side of the element substrate. 2. The electrophoretic display device according to claim 1, wherein a resin having a lower elastic modulus than that of the element substrate is embedded in the groove. 3. The electrophoretic display device according to claim 1, wherein a corner portion formed by a bottom surface and a wall surface of the groove is a curved surface. The electrophoretic display device according to claim 1, wherein a plurality of the grooves are formed. The electrophoretic display device according to claim 1, wherein the plurality of grooves are arranged in parallel in one direction. The electrophoretic display device according to claim 1, wherein a depth of the groove varies depending on a part. The electrophoretic display device according to claim 1, wherein the arrangement density of the grooves differs depending on a part.   An electronic apparatus comprising the electrophoretic display device according to claim 1.

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