WO2017013973A1 - Display device - Google Patents

Abstract

This display device is provided with: a plurality of display elements, each of which comprises a display body between a first electrode and a second electrode facing each other, and the display state of which changes in accordance with the voltage applied thereto; thin film transistors which are provided for respective display elements, and each of which performs switching for the application of a voltage to the first electrode; a pressure-sensitive conductive layer that is formed below the thin film transistors; a third electrode which is connected to the first electrode via the pressure-sensitive conductive layer; and a switch which selects, as a voltage application path to the first electrode, either a first path that contains the thin film transistor or a second path that contains the pressure-sensitive conductive layer and the third electrode.

Description

Display device

The present disclosure relates to a display device that displays an image using reflected light.

Recently, in a display device using an electrophoretic display element, a driving method capable of displaying a locus drawn with a finger or a pen (handwriting input) has been developed (for example, Patent Document 1).

In the method disclosed in Patent Document 1, by providing a pressure-sensitive switch in a pixel, a portion pressed by a pen or the like can be partially driven to display a drawn locus.

JP 2008-191324 A

However, in the method of Patent Document 1, a pressure-sensitive switch is newly provided inside the pixel circuit. For this reason, the resolution and the aperture ratio are reduced.

It is desirable to provide a display device capable of realizing video display and handwriting input while suppressing a decrease in resolution and aperture ratio.

A display device according to an embodiment of the present disclosure includes a plurality of display elements each having a display body between a first electrode and a second electrode facing each other, and a display state changing according to an applied voltage. A thin film transistor provided for each display element, which performs switching for applying a voltage to the first electrode, a pressure sensitive conductive layer formed below the thin film transistor, and connected to the first electrode via the pressure sensitive conductive layer And a switch for selecting one of a first path including a thin film transistor and a second path including a pressure-sensitive conductive layer and a third electrode as a voltage application path to the first electrode. It is equipped with.

In the display device according to the embodiment of the present disclosure, as a voltage application path to the first electrode, a first path including a thin film transistor and a second path including a pressure-sensitive conductive layer and a third electrode are formed. These first and second paths are selected by a switch. Thereby, when the first path is selected, display driving (active matrix driving) using a thin film transistor is possible. On the other hand, when the second path is selected, the surface of the apparatus is pressurized (pressed), so that a voltage can be directly applied to the display element at the pressurized location. In addition, since the pressure-sensitive conductive layer is disposed below the thin film transistor, the influence on the circuit layout is small as compared with the case where the pressure-sensitive conductive layer is disposed in the pixel circuit.

According to the display device of one embodiment of the present disclosure, the first path including the thin film transistor and the second path including the pressure-sensitive conductive layer and the third electrode are formed as the voltage application path to the first electrode. In addition, a switch for selecting these first and second paths is provided. As a result, it is possible to switch between display by driving using a thin film transistor (video display) and display by partial direct drive (handwriting input). In addition, since the pressure-sensitive conductive layer is arranged below the thin film transistor, the influence on the circuit layout is reduced and the decrease in resolution and aperture ratio is suppressed compared to the case where it is arranged in the pixel circuit. it can. Therefore, it is possible to realize video display and handwriting input while suppressing a decrease in resolution and aperture ratio. The above content is an example of the present disclosure. The effects of the present disclosure are not limited to those described above, and other effects may be included or further effects may be included.

It is sectional drawing showing the structure of the display apparatus which concerns on one embodiment of this indication. It is a plane schematic diagram for demonstrating the structural example of the display body shown in FIG. It is a schematic diagram for demonstrating the function of the pressure-sensitive conductive layer shown in FIG. It is a schematic diagram for demonstrating the function of the pressure-sensitive conductive layer shown in FIG. FIG. 2 is a cross-sectional view illustrating configurations of a first electrode, a TFT layer, a first substrate, a pressure-sensitive conductive layer, a third electrode, and a switch illustrated in FIG. 1. It is a circuit diagram showing the circuit structure for driving one display element with a switch. It is sectional drawing for demonstrating the manufacturing process of the display apparatus shown in FIG. It is sectional drawing for demonstrating the process following FIG. 6A. FIG. 6B is a cross-sectional view for explaining a process following the process in FIG. 6B. It is sectional drawing for demonstrating the process following FIG. 6C. It is sectional drawing for demonstrating the process following FIG. 6D. It is sectional drawing for demonstrating the process following FIG. 7A. It is sectional drawing for demonstrating the process following FIG. 7B. FIG. 7D is a cross-sectional view for illustrating a step following the step in FIG. 7C. It is sectional drawing for demonstrating the process following FIG. 7D. It is sectional drawing for demonstrating the process following FIG. 7E. FIG. 7D is a cross-sectional view for illustrating a step following the step in FIG. 7F. It is sectional drawing for demonstrating the process following FIG. 7G. FIG. 9 is a cross-sectional view for explaining a step following the step in FIG. 8. FIG. 10 is a cross-sectional view for explaining a step following the step in FIG. 9. It is sectional drawing for demonstrating the manufacturing process of the display apparatus shown in FIG. It is sectional drawing for demonstrating the process following FIG. 11A. It is sectional drawing for demonstrating the process following FIG. 11B. It is a flowchart for demonstrating the processing flow at the time of TFT drive (at the time of video display). It is a circuit diagram for demonstrating the voltage application path | route to the display element (1st electrode) at the time of TFT drive. It is a cross-sectional schematic diagram for demonstrating the display state at the time of TFT drive. It is a flowchart for demonstrating the processing flow at the time of handwriting input. It is a circuit diagram for demonstrating the voltage application path | route to the display element (1st electrode) at the time of handwriting input. It is a cross-sectional schematic diagram for demonstrating the display state at the time of handwriting input. 10 is a schematic diagram for explaining the operation (large parallax) of the display device according to Comparative Example 1. FIG. It is a schematic diagram for demonstrating an effect | action (small parallax) of the display apparatus shown in FIG. 10 is a schematic diagram for explaining a driving operation (partial erasing operation) according to Modification 1. FIG. It is a schematic diagram for demonstrating the drive operation | movement following FIG. 19A. FIG. 20B is a schematic diagram for explaining the driving operation subsequent to FIG. 19B. It is a circuit diagram for demonstrating the voltage application path | route to the display element (1st electrode) at the time of partial erasing. It is a functional block diagram showing the structure of the display apparatus which concerns on the modification 2 with an input pen. FIG. 22 is a schematic diagram illustrating an example of a partial erasing operation using the input pen of the display device illustrated in FIG. 21. 10 is a schematic cross-sectional view illustrating a configuration of a pressure-sensitive conductive layer according to Modification 3. FIG. 10 is a schematic cross-sectional view for explaining the action of the pressure-sensitive conductive layer according to Comparative Example 2. FIG. It is a cross-sectional schematic diagram for demonstrating an effect | action of the pressure-sensitive conductive layer shown in FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to modification example 4. FIG. FIG. 26 is a schematic diagram illustrating a perspective configuration of a third electrode illustrated in FIG. 25. It is a cross-sectional schematic diagram for demonstrating the display state at the time of the handwriting input of the display apparatus shown in FIG. 10 is a cross-sectional view illustrating a configuration of a display device according to Modification Example 5. FIG. It is a perspective view showing the external appearance of the tablet personal computer which concerns on an application example.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (Example of a reflective display device capable of selectively switching between TFT driving and driving using a pressure-sensitive conductive layer by a switch)
2. Modification 1 (example of partial erase drive)
3. Modification 2 (Example of partial erasure driving using an input pen equipped with a tilt sensor)
4). Modification 3 (example in which a groove is provided in the pressure-sensitive conductive layer)
5). Modification 4 (example in which the third electrode is divided and arranged in the color reflection type display device)
6). Modification 5 (example in which the third electrode is divided and arranged in a monochrome reflection type display device)
7). Application example (electronic equipment)

<1. Embodiment>
[Constitution]
FIG. 1 illustrates a cross-sectional configuration of a display device (display device 1) according to an embodiment of the present disclosure. The display device 1 is a monochrome reflection type display device that displays an image by light reflectance control using a display element (display element 10) such as an electrophoretic display element.

The display device 1 includes a TFT (thin film transistor) layer 12 and a plurality of display elements 10 arranged in a matrix, for example, on a first substrate 11. Each display element 10 has a display body 10 </ b> A between the first electrode 13 and the second electrode 16. The display body 10 </ b> A is separated for each display element 10 (for each pixel) by a spacer (partition wall) 15. A second substrate 17 is provided on the second electrode 16. A seal layer 14 is interposed between the first electrode 13 and the display body 10A. FIG. 1 schematically shows the configuration of the display device 1 and may differ from actual dimensions and shapes. Hereinafter, the configuration of each unit will be described.

The first substrate 11 is formed of, for example, one or more of inorganic materials, metal materials, plastic materials, and the like. The inorganic material is, for example, silicon (Si), silicon oxide (SiO _x ), silicon nitride (SiN _x ), aluminum oxide (AlO _x ), or the like. Examples of the silicon oxide include glass or spin-on-glass (SOG). Etc. are included. Examples of the metal material include aluminum (Al), nickel (Ni), and stainless steel. Examples of the plastic material include polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethyl ether ketone (PEEK), cycloolefin polymer (COP), polyimide (PI), and polyether sulfone (PES). Etc.

The first substrate 11 may or may not have optical transparency. Further, the first substrate 11 may be a rigid substrate such as a wafer, or may be a flexible thin-layer glass or film. However, since a flexible (foldable) electronic paper display can be realized, it is desirable to be made of a flexible material. Although details will be described later on the first substrate 11, for example, a through electrode 11 </ b> A is formed for each display element 10.

The TFT layer 12 is a layer in which, for example, a pixel circuit including a TFT 12A described later is formed. The detailed configuration of the TFT layer 12 will be described later.

The first electrode 13 is provided for each display element 10. The first electrode 13 is one of conductive materials such as Al, Mo, ITO, Ni, Ti, Cr, Zn, C (carbon), Au (gold), Ag (silver), or Cu (copper). Includes one or more types. A voltage (Vsig) set for each display element 10 can be applied to the first electrode 13 via a TFT 12A described later or a pressure-sensitive conductive layer 18.

The seal layer 14 is made of a resin material such as a thermosetting resin and an ultraviolet curable resin. The spacer 15 is made of, for example, a photosensitive resin. The shape of the spacer 15 is not particularly limited, but is preferably a shape that does not hinder the movement of the migrating particles 32 between the first electrode 13 and the second electrode 16 and can uniformly distribute the migrating particles 32. Is. The thickness of the spacer 15 is not particularly limited, but in particular, it is preferably as thin as possible in order to reduce power consumption, and is, for example, 10 μm to 100 μm.

The second electrode 16 includes, for example, one kind or two or more kinds of light-transmitting conductive materials (transparent conductive materials). Examples of the conductive material include indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO). The thickness of the second electrode 16 is, for example, not less than 0.001 μm and not more than 1 μm. For example, the second electrode 16 is formed on one surface of the second substrate 17 over, for example, the entire displayable region, and is an electrode common to the display elements 10. However, similarly to the first electrode 13, it may be divided into a plurality of elements for each element.

When an image is displayed on the surface (display surface S1) of the second substrate 17, the display body 10A is viewed through the second electrode 16, and therefore the light transmittance of the second electrode 16 is as high as possible. For example, 80% or more. The electric resistance of the second electrode 16 is preferably as low as possible, for example, 100Ω / □ (square) or less.

The second substrate 17 is made of, for example, PET, TAC, PEN, PC, acrylic, glass, or the like. In addition to this, as the second substrate 17, a material having optical transparency can be used from the materials listed as the constituent material of the first substrate 11. This is because an image is displayed on the upper surface side of the second substrate 17, and the second substrate 17 needs to be light transmissive. The thickness of the second substrate 17 is, for example, not less than 10 μm and not more than 250 μm.

The display body 10 </ b> A changes its display state (light reflectance) in accordance with a change in voltage applied through the first electrode 13 and the second electrode 16. The display body 10A generates contrast using, for example, an electrophoretic phenomenon. The display body 10A includes electrophoretic particles 32 that can move between a pair of electrodes (first electrode 13 and second electrode 16) according to an applied electric field. Contains.

Examples of the display element 10 having such a display body 10A include a microcup type or microcapsule type electrophoretic display element. In the microcup method, for example, the display body 10A includes electrophoretic particles (electrophoretic particles 32) colored black and a liquid or porous layer colored white, and a rib (spacer 15) having a high elastic modulus. It has the structure separated by. Moreover, in this microcup system, a 1 particle type may be sufficient and a 2 particle type may be sufficient. Alternatively, a two-particle type microcapsule method may be used. In the microcapsule method, for example, a plurality of capsules each encapsulating electrophoretic particles colored in white and electrophoretic particles colored in black are used. However, the line width displayed (drawn) by handwriting input is more easily controlled when the microcup method is used than when the microcapsule method is used. In addition to this, as the display element 10, it is also possible to use a colored liquid itself without using the porous layer 33. Alternatively, an electrochromic display element or the like may be used. Here, as an example, a one-particle type microcup electrophoretic display element will be described.

(Configuration example of display 10A)
FIG. 2 shows an example of the display body 10A. The display body 10 </ b> A includes, for example, a porous layer 33 and migrating particles 32 in an insulating liquid 31.

The insulating liquid 31 is a nonaqueous solvent such as an organic solvent, and specifically includes paraffin or isoparaffin. It is preferable that the viscosity and refractive index of the insulating liquid 31 are as low as possible. This is because the mobility (response speed) of the migrating particles 32 is improved, and the energy (power consumption) required to move the migrating particles 32 is lowered accordingly. In addition, since the difference between the refractive index of the insulating liquid 31 and the refractive index of the porous layer 33 is increased, the light reflectance of the porous layer 33 is increased.

The insulating liquid 31 may contain various materials as necessary. For example, the insulating liquid 31 may include a colorant, a charge control agent, a dispersion stabilizer, a viscosity adjusting agent, a surfactant, or a resin. Further, a weak conductive liquid may be used instead of the insulating liquid 31.

The migrating particles 32 are one type or two or more types of charged particles that can move between the first electrode 13 and the second electrode 16, and are dispersed in the insulating liquid 31. The migrating particles 32 have arbitrary optical reflection characteristics (light reflectivity). The light reflectance of the migrating particles 32 is not particularly limited, but is preferably set so that at least the migrating particles 32 can shield the porous layer 33. This is because contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32 and the light reflectance of the porous layer 33.

As the constituent material of the migrating particles 32, for example, one kind or two or more kinds of particles (organic pigment, inorganic pigment, dye, carbon material, metal material, metal oxide, glass, polymer material (resin), etc. ( Powder). The migrating particles 32 may be pulverized particles or capsule particles of resin solids containing the above-described particles. However, materials corresponding to carbon materials, metal materials, metal oxides, glass, or polymer materials are excluded from materials corresponding to organic pigments, inorganic pigments, or dyes. As the electrophoretic particles 32, any one of the above may be used, or a plurality of types may be used.

Organic pigments include, for example, azo pigments, metal complex azo pigments, polycondensed azo pigments, flavanthrone pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, perylene pigments, perinones. Pigments, anthrapyridine pigments, pyranthrone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments or indanthrene pigments. Inorganic pigments include, for example, zinc white, antimony white, carbon black, iron black, titanium boride, bengara, mapico yellow, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfide, cadmium selenide, calcium carbonate, barium sulfate, Lead chromate, lead sulfate, barium carbonate, lead white or alumina white. Examples of the dye include nigrosine dyes, azo dyes, phthalocyanine dyes, quinophthalone dyes, anthraquinone dyes, and methine dyes. The carbon material is, for example, carbon black. The metal material is, for example, gold, silver or copper. Examples of metal oxides include titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, and copper-chromium-manganese oxide. Or copper-iron-chromium oxide. The polymer material is, for example, a polymer compound in which a functional group having a light absorption region in the visible light region is introduced. As long as the polymer compound has a light absorption region in the visible light region, the type of the compound is not particularly limited.

The specific forming material of the migrating particles 32 is selected from the above materials according to the role of the migrating particles 32 in order to cause contrast, for example. For example, the material in the case of dark display (black display) by the migrating particles 32 is a black material such as a carbon material or a metal oxide. The carbon material is, for example, carbon black, and the metal oxide is, for example, copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, copper-chromium-manganese oxide, or copper-iron. -Chromium oxide and the like. Among these, a carbon material is preferable. This is because excellent chemical stability, mobility and light absorption are obtained. On the other hand, the material in the case of bright display (white display) by the migrating particles 32 is a white material, for example, a metal oxide such as titanium oxide, zinc oxide, zirconium oxide, barium titanate or potassium titanate, Titanium oxide is preferred. This is because it is excellent in electrochemical stability and dispersibility and has high reflectance.

The content (concentration) of the migrating particles 32 in the insulating liquid 31 is not particularly limited, and is, for example, 0.1 wt% to 10 wt%. This is because shielding (concealment) and mobility of the migrating particles 32 are ensured. In this case, if it is less than 0.1% by weight, the migrating particles 32 may not easily shield the porous layer 33. On the other hand, when the amount is more than 10% by weight, the dispersibility of the migrating particles 32 is lowered, so that the migrating particles 32 are difficult to migrate, and in some cases, there is a possibility of aggregation.

The average particle diameter of the migrating particles 32 is preferably in the range of 0.1 μm to 10 μm, for example.

In addition, it is preferable that the migrating particles 32 are easily dispersed and charged in the insulating liquid 31 over a long period of time and are not easily adsorbed by the porous layer 33. For this reason, in order to disperse the electrophoretic particles 32 by electrostatic repulsion, a dispersant (or a charge adjusting agent) may be used, or the electrophoretic particles 32 may be subjected to a surface treatment. Moreover, you may use both together.

The dispersing agent is, for example, Solsperse series manufactured by Lubrizol, BYK series or Anti-Terra® series manufactured by BYK-Chemie, or Span series manufactured by ICI® Americas®.

The surface treatment is, for example, rosin treatment, surfactant treatment, pigment derivative treatment, coupling agent treatment, graft polymerization treatment or microencapsulation treatment. Among these, graft polymerization treatment, microencapsulation treatment, or a combination thereof is preferable. This is because long-term dispersion stability and the like can be obtained.

The surface treatment material is, for example, a material (adsorbing material) having a functional group and a polymerizable functional group that can be adsorbed on the surface of the migrating particle 32. The type of functional group that can be adsorbed is determined according to the material for forming the migrating particles 32. For example, carbon materials such as carbon black are aniline derivatives such as 4-vinylaniline, and metal oxides are organosilane derivatives such as 3- (trimethoxysilyl) propyl methacrylate. . Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group.

Further, the material for surface treatment is, for example, a material (graftable material) that can be grafted on the surface of the migrating particles 32 into which a polymerizable functional group is introduced. The graft material preferably has a polymerizable functional group and a dispersing functional group that can be dispersed in the insulating liquid 31 and can maintain dispersibility due to steric hindrance. The kind of polymerizable functional group is the same as that described for the adsorptive material. The dispersing functional group is, for example, a branched alkyl group when the insulating liquid 31 is paraffin. In order to polymerize and graft the graft material, for example, a polymerization initiator such as azobisisobutyronitrile (AIBN) may be used.

For reference, the details of the method for dispersing the migrating particles 32 in the insulating liquid 31 as described above are described in “Dispersion Technology of Ultrafine Particles and Its Evaluation—Surface Treatment / Fine Grinding and Air / Liquid / Polymer” It is published in books such as “Dispersion Stabilization ~ (Science & Technology)”.

The porous layer 33 is, for example, a three-dimensional structure (irregular network structure such as a nonwoven fabric) formed by a fibrous structure 331 as shown in FIG. The porous layer 33 has a plurality of gaps (pores 333) through which the migrating particles 32 pass in places where the fibrous structure 331 does not exist.

The fibrous structure 331 includes one or more non-migrating particles 332, and the non-migrating particles 332 are held by the fibrous structure 331. In the porous layer 33 which is a three-dimensional structure, one fibrous structure 331 may be entangled at random, or a plurality of fibrous structures 331 may be gathered and overlap at random. In addition, both may be mixed. When there are a plurality of fibrous structures 331, each fibrous structure 331 preferably holds one or more non-migrating particles 332. FIG. 2 shows a case where the porous layer 33 is formed by a plurality of fibrous structures 331.

The reason why the non-migrating particles 332 are included in the fibrous structure 331 is that the light reflectance of the porous layer 33 is higher because external light is more easily diffusely reflected. Thereby, compared with the case where the non-electrophoretic particle 332 is not contained, contrast can be raised more.

The fibrous structure 331 is a fibrous substance having a sufficiently large length with respect to the fiber diameter (diameter). The fibrous structure 331 includes, for example, any one type or two or more types such as a polymer material or an inorganic material, and may include other materials. Polymer materials include, for example, nylon, polylactic acid, polyamide, polyimide, polyethylene terephthalate, polyacrylonitrile, polyethylene oxide, polyvinyl carbazole, polyvinyl chloride, polyurethane, polystyrene, polyvinyl alcohol, polysulfone, polyvinyl pyrrolidone, polyvinylidene fluoride, polyhexa Fluoropropylene, cellulose acetate, collagen, gelatin, chitosan or copolymers thereof. The inorganic material is, for example, titanium oxide. Among these, a polymer material is preferable as a material for forming the fibrous structure 331. This is because the reactivity (photoreactivity, etc.) is low (chemically stable), so that the unintended decomposition reaction of the fibrous structure 331 is suppressed. Note that in the case where the fibrous structure 331 is formed of a highly reactive material, the surface of the fibrous structure 331 is preferably covered with an arbitrary protective layer.

The shape (appearance) of the fibrous structure 331 is not particularly limited as long as the fibrous structure 331 has a sufficiently long length with respect to the fiber diameter as described above. Specifically, it may be linear, may be curled, or may be bent in the middle. Moreover, you may branch to 1 or 2 or more directions on the way, not only extending in one direction. The formation method of the fibrous structure 331 is not particularly limited. For example, a phase separation method, a phase inversion method, an electrostatic (electric field) spinning method, a melt spinning method, a wet spinning method, a dry spinning method, a gel spinning method, A sol-gel method or a spray coating method is preferred. This is because a fibrous substance having a sufficiently large length with respect to the fiber diameter can be easily and stably formed.

This fibrous structure 331 preferably has an optical reflection characteristic different from that of the migrating particles 32. For example, when dark display is performed by the migrating particles 32, black migrating particles 32 and white fibrous structures 331 are used. When a bright display is performed by the migrating particles 32, white migrating particles 32 and a black fibrous structure 331 are used.

Non-electrophoretic particles 332 are particles that are fixed to the fibrous structure 331 and do not migrate electrically. The material for forming the non-electrophoretic particles 332 is the same as the material for forming the electrophoretic particles 32, for example, and is selected according to the role that the non-electrophoretic particles 332 play. The non-migrating particles 332 have optical reflection characteristics different from those of the migrating particles 32.

In the present embodiment, in the display device 1 as described above, the pressure-sensitive conductive layer 18 and the third electrode 19 are formed in this order below the TFT layer 12, for example, on the back surface of the first substrate 11. .

The pressure-sensitive conductive layer 18 is a structure in which the electric resistance changes according to the pressure (pressurized state), and specifically, the electric resistance is reduced (exhibits conductivity) by being pressurized. It is made of a material such as a pressure-sensitive conductive rubber. An example is shown in FIGS. 3A and 3B. However, FIG. 3A schematically illustrates a cross-sectional configuration in a non-pressurized state, and FIG. 3B schematically illustrates a cross-sectional configuration in a pressurized state. Thus, the pressure-sensitive conductive layer 18 is obtained by dispersing the conductive elements 182 in the insulating layer 181 made of, for example, a rubber material. In the non-pressurized state (FIG. 3A), since each conductive element 182 is discrete in the insulating layer 181, the electrical resistance is high. On the other hand, as shown in FIG. 3B, in a pressurized state (a state where pressure P is applied along the Y-axis direction), the pressure-sensitive conductive layer 18 bends (deforms), and each conductive element 182 in the insulating layer 181. Are connected or close together. As a result, a conductive path R is formed in the pressure-sensitive conductive layer 18 (electrical resistance is reduced). The thickness of the pressure-sensitive conductive layer 18 is not particularly limited, but is preferably 1 mm or less, for example.

The constituent material of the pressure-sensitive conductive layer 18 includes, for example, pressure-sensitive ink, anisotropic conductive film, adhesive containing charged particles, or anisotropic conductive rubber in addition to the pressure-sensitive conductive rubber as described above. Etc. can be used.

The pressure-sensitive conductive layer 18 is formed continuously over the entire surface of the first substrate 11, for example, as a layer common to the plurality of display elements 10.

The third electrode 19 includes one or more of conductive materials such as Al, Mo, ITO, Ni, Ti, Cr, Zn, C, Au, Ag, or Cu, for example. The thickness of the third electrode 19 is, for example, not less than 0.01 μm and not more than 100 μm. For example, the third electrode 19 is formed continuously on the back surface of the pressure-sensitive conductive layer 18 (here, between the pressure-sensitive conductive layer 18 and the support substrate 20) as a layer common to the plurality of display elements 10. ing. A support substrate (support film) 20 is further bonded to the back surface of the third electrode 19.

In the present embodiment, a switch 41 that selectively switches between the TFT layer 12 and the third electrode 19 and connects to the voltage application unit 40 (power source) is provided. Here, as the switch 41, a switch 41 </ b> A is provided between the TFT layer 12 and the voltage application unit 40, and a switch 41 </ b> B is provided between the third electrode 19 and the voltage application unit 40.

FIG. 4 shows the detailed configuration of the TFT layer 12 together with the configuration of the first electrode 13, the first substrate 11, the pressure-sensitive conductive layer 18, the third electrode 19, and the switch 41. FIG. 5 shows a circuit configuration of a region corresponding to one display element 10 (region corresponding to a pixel). As described above, the TFT layer 12 includes, for example, the TFT 12A and the storage capacitor 12B.

Specifically, a gate electrode 122a and a lower electrode 122b are formed in a selective region on the first substrate 11 with a planarizing film 121 interposed therebetween. A gate insulating film 123 is formed so as to cover these gate electrode 122a and lower electrode 122b. A semiconductor layer 124 is formed in a region on the gate insulating film 123 facing the gate electrode 122a. Source / drain electrodes 125 </ b> A and 125 </ b> B are formed by being electrically connected to the semiconductor layer 124 (overlapping with part of the semiconductor layer 124). A part of the source / drain electrode 125B is stacked on the lower electrode 122b via the gate insulating film 123, and these stacked portions form the storage capacitor 12B. Of the upper surface of the semiconductor layer 124, portions exposed from the source / drain electrodes 125 </ b> A and 125 </ b> B are covered with a protective film 126. An interlayer insulating film 127 is formed so as to cover the TFT 12A and the storage capacitor 12B, and the first electrode 13 is disposed on the interlayer insulating film 127.

The TFT 12A is a thin film transistor having a bottom gate structure, for example, and is composed of an n-channel or p-channel MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor). The gate electrode 122a is connected to the gate line 131, and the on state and the off state of the TFT 12A are switched (a switching operation is performed) by application of the gate voltage Vg via the gate line 131. One of the source / drain electrodes 125A and 125B functions as a source electrode and the other functions as a drain electrode. Of these, the source / drain electrode 125A (for example, the source electrode) is connected to the switch 41 (switch 41A) via the wiring 132a. The source / drain electrode 125B (for example, the drain electrode) is electrically connected to the first electrode 13 through a contact hole H3 provided in the interlayer insulating film 127. Part of the source / drain electrode 125B also serves as an upper electrode of the storage capacitor 12B (connected to one end of the storage capacitor 12B). The semiconductor layer 124 is made of, for example, an oxide semiconductor, an organic semiconductor, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

One end (upper electrode) of the storage capacitor 12B is electrically connected to the source / drain electrode 125B and the first electrode 13. The other end (lower electrode 122b) of the holding capacitor 12B is connected to the common potential line 133, and is held at a constant voltage Vcom, for example. The second electrode 16 of the display element 10 is also connected to the common potential line 133 (the second electrode 16 is held at the voltage Vcom).

In this embodiment, the pressure-sensitive conductive layer 18 and the third electrode 19 are disposed below the TFT layer 12. The pressure-sensitive conductive layer 18 is adjacent to the through electrode 11 </ b> A provided on the first substrate 11, and the through electrode 11 </ b> A is electrically connected to the first electrode 13. Here, the source / drain electrode 125B of the TFT 12A extends to the formation position of the through electrode 11A, and the extended portion is electrically connected to the through electrode 11A through the contact hole H2. The pressure-sensitive conductive layer 18 and the third electrode 19 are connected to the switch 41 (switch 41B) via the wiring 132b. The through electrode 11 </ b> A is provided, for example, for each display element 10, that is, one through electrode 11 </ b> A is provided for one first electrode 13.

The through electrode 11A is made of a conductive material such as Al, Au, Cu, or Ni. The through electrode 11A is not limited to the illustrated configuration, and one through electrode 11A may be provided for two or more display elements 10, or two or more through electrodes may be provided for one display element 10. The electrode 11A may be provided. The shape, size, pitch, and the like of the through electrode 11A can take various configurations.

With the above configuration, in the present embodiment, as a voltage application path to the first electrode 13, a first path including the TFT 12 </ b> A (path R <b> 1 to be described later), a second including the pressure-sensitive conductive layer 18 and the third electrode 19. This route (route R2 described later) can be selected by the switch 41. In other words, the switch 41 is configured to selectively connect the source / drain electrode 125A (source electrode) of the TFT 12A and the third electrode 19 to the power supply (voltage application unit 40). The switch 41 may be switched automatically or based on an external input signal (for example, an input signal from a user or the like). Although details will be described later, by switching the switch 41, the signal voltage Vsig can be supplied to the first electrode 13 via the TFT 12 </ b> A or the pressure-sensitive conductive layer 18.

[Production method]
The display device 1 of the present embodiment can be manufactured as follows, for example.

First, as shown in FIG. 6A, the first substrate 11 is bonded to one surface of the support substrate 210 via the release layer 220. Thereafter, as shown in FIG. 6B, a contact hole H1 is formed in a selective region of the first substrate 11. Subsequently, as shown in FIG. 6C, the conductive layer 11a1 is formed by plating, for example, so as to fill the contact hole H1. Thereafter, as shown in FIG. 6D, the surface of the formed conductive layer 11a1 is etched back to form the through electrode 11A.

Next, the TFT layer 12 is formed. Specifically, first, as shown in FIG. 7A, a planarizing film 121 is formed. Note that a barrier film may be formed instead of the planarizing film 121, or the planarizing film 121 and the barrier film may be laminated. Thereafter, as shown in FIG. 7B, the gate electrode 122a and the lower electrode 122b are patterned in a selective region on the planarizing film 121. Then, as shown in FIG. Subsequently, as illustrated in FIG. 7C, a gate insulating film 123 is formed so as to cover the gate electrode 122a and the lower electrode 122b. Thereafter, as shown in FIG. 7D, a semiconductor layer 124 is patterned in a selective region on the gate insulating film 123. Thereafter, as shown in FIG. 7E, the contact hole H2 is formed by partially etching the region of the gate insulating film 123 and the planarizing film 121 that faces the through electrode 11A. Thus, the through electrode 11A is exposed from the planarization film 121 and the gate insulating film 123. Subsequently, as shown in FIG. 7F, the source / drain electrodes 125A and 125B are patterned. At this time, the source / drain electrode 125B is patterned so as to be in contact with the through electrode 11A via the contact hole H2. After that, as shown in FIG. 7G, the protective film 126 is patterned so as to cover the portions of the semiconductor layer 124 exposed from the source / drain electrodes 125A and 125B. Thereby, the TFT 12A and the storage capacitor 12B can be formed.

Subsequently, as shown in FIG. 8, an interlayer insulating film 127 is formed. At this time, a contact hole H3 is formed to face part of the source / drain electrode 125B. In this way, the TFT layer 12 can be formed.

Next, as shown in FIG. 9, the first electrode 13 is patterned on the interlayer insulating film 127 so as to fill the contact hole H3.

Thereafter, as shown in FIG. 10, the support substrate 210 is peeled from the first substrate 11. Thereby, an element substrate (driving substrate) in which the TFT layer 12 is formed on the first substrate 11 having the through electrode 11A can be formed.

On the other hand, as shown in FIG. 11A, the second electrode 16 is formed on one surface of the second substrate 17 by a film forming method such as sputtering. Thereafter, as shown in FIG. 11B, the spacers 15 are pattern-formed on the second electrode 16 by, for example, an imprint method. Specifically, after a solution containing the constituent material of the spacer 15 (for example, a photosensitive resin material) is applied on the second electrode 16, a mold having a recess is pressed against the coating film and exposed to light, and then the mold is formed. Remove. Thereby, the columnar spacer 15 can be formed. By making the spacer 15 have a reverse taper shape as shown in the figure, the mold can be easily removed.

Subsequently, as shown in FIG. 11C, the porous layer 33 is formed in the region (cell 150) surrounded by the spacer 15. Specifically, first, for example, titanium oxide is added to the spinning solution as non-electrophoretic particles 332 and stirred sufficiently, and then this is spun. The spinning solution is prepared, for example, by dispersing or dissolving polyacrylonitrile as the fibrous structure 331 in N, N′-dimethylformamide. Examples of the spinning method include an electrostatic spinning method. Instead of the electrostatic spinning method, a phase separation method, a phase inversion method, a melt spinning method, a wet spinning method, a dry spinning method, a gel spinning method, a sol-gel method, a spray coating method, or the like may be used.

In addition, it is preferable to use the spinning method as described above for forming the fibrous structure 331. As a method for forming the fibrous structure 331, in addition to the spinning method, for example, there is a method of making a hole in a polymer film using laser processing. However, in such a method, the pore diameter tends to increase. There is. By using the spinning method, the pore diameter can be easily controlled to be small, and the migrating particles 32 can be easily shielded by the fibrous structure 331.

After forming the fibrous structure 331 by spinning as described above, it is divided and stored in each cell 150. When the formed fibrous structure 331 is pressed from above (the direction opposite to the second substrate 17), it is slid by the spacer 15. By accommodating the divided fibrous structure 331 in the region surrounded by the spacer 15, the porous layer 33 in which the non-electrophoretic particles 332 are held in the fibrous structure 331 is formed in each cell 150. can do.

Thereafter, the display body 10A is formed by applying the insulating liquid 31 in which the migrating particles 32 are dispersed in the cell 150 in which the porous layer 33 is formed (not shown in FIG. 11C). Subsequently, a peeling member (not shown) provided with a seal layer 14 is opposed to the display body 10A, for example, via a sealant (not shown). Then, after peeling off a peeling member, the drive board | substrate with 11 A of penetration electrodes formed by the above-mentioned flow is bonded on the sealing layer 14 via the adhesion layer (not shown).

Finally, the pressure-sensitive conductive layer 18, the third electrode 19, and the support substrate 20 are bonded to the back surface of the first substrate 11 via a conductive adhesive or the like. Note that the support substrate 20 is used as necessary and may not be used. The display device 1 is completed through the above steps.

[Driving method]
In the display device 1 of the present embodiment, the switch 41 is controlled based on a control signal from a control unit (not shown). For example, one of the switch 41A and the switch 41B is turned on and the other is turned off. This makes it possible to selectively switch between display driving using the TFT 12A (video display by active matrix driving) and display driving using the pressure-sensitive conductive layer 18 (handwriting input). Hereinafter, each driving operation will be described.

(Video display by TFT drive)
FIG. 12 shows a processing flow when driving the TFT. FIG. 13 is a circuit diagram for explaining a voltage application path during TFT driving. In this way, TFT driving is selected (the switch 41A is turned on and the switch 41B is turned off) (step S11), and the TFT 12A (source / drain electrode 125A) is connected to the power supply (voltage application unit 40). (Step S12).

Thereafter, image data is fetched from the outside (step S13), and predetermined signal processing is performed on the fetched image data (step S14). Based on the image data subjected to this signal processing, the signal voltage Vsig is applied to the source / drain electrode 125A of the TFT 12A. On the other hand, a predetermined ON voltage is applied to the gate electrode 122a of the TFT 12A for each display element 10. As a result of the switching of the TFT 12A (step S15), the source and drain of the TFT 12A become conductive, and the path R1 is formed (the path R1 is selected). A signal voltage Vsig (for example, −100 V to +100 V) corresponding to the video signal is supplied to the first electrode 13 of each display element 10 via the path R1 including the TFT 12A.

Here, since the second electrode 16 is connected to the common potential line 133 and is held at a constant voltage Vcom (for example, 0 V, GND), each display element 10 includes the first electrode 13 and the second electrode 16. A bias voltage of about 0 to 100 V, for example, is applied between the electrodes (display body 10A). For example, when the migrating particle 32 is a negatively charged black particle, as shown in FIG. 14, in the pixels a1 and a3 in which 0 V is applied to the first electrode 13, the migrating particle 32 is the first particle, for example. It stays on the 1 electrode 13 side and becomes white display (bright display). On the other hand, in the pixel a2 in which −15 V is applied to the first electrode 13, for example, the migrating particles 32 move to the second electrode 16 side, so that black display (dark display) is obtained. In this way, video display (display display) for each pixel is performed on the display surface S1 (step S16). As described above, by selecting the TFT 12A (path R1) by the switch 41, display driving for each display element 10 (for each pixel), that is, video display by active matrix driving is realized.

(Handwriting input using pressure-sensitive conductive layer 18)
FIG. 15 shows a processing flow at the time of handwriting input. FIG. 16 is a circuit diagram for explaining a voltage application path during handwriting input. FIG. 17 is a schematic diagram for explaining a display state during handwriting input. Thus, handwriting input is selected (the switch 41B is turned on and the switch 41A is turned off) (step S21), and the third electrode 19 (one end side of the pressure-sensitive conductive layer 18) is connected to the power source ( The voltage application unit 40) is connected (step S22). As a result, a predetermined signal voltage Vsig (for example, −15 V) can be applied to the third electrode 19.

In this state, when the display surface S1 is pressed (pressed) with a pen or the like (step S23), the portion of the pressure-sensitive conductive layer 18 corresponding to the pressed portion is locally deformed, and the electric resistance of the portion is reduced. Lower. Thereby, the route R2 is formed (the route R2 is selected). That is, the first electrode 13 and the third electrode 19 of the display element 10 corresponding to the pressurization location are electrically connected through the pressure-sensitive conductive layer 18 and the through electrode 11A. As a result, the signal voltage Vsig (for example, −15 V) is supplied to the first electrode 13 of the display element 10 corresponding to the pressed portion.

Here, as described above, since the second electrode 16 is held at a constant voltage Vcom (for example, 0 V, GND), the first electrode 13 and the second electrode 16 in the display element 10 corresponding to the pressurization location. A bias voltage is applied between the electrodes 16 (display body 10A). For example, when the migrating particle 32 is a negatively charged black particle, as shown in FIG. 17, in the pixels a4 and a6 to which the pressure P is not applied, the migrating particle 32 is on the first electrode 13 side. The white display (bright display). On the other hand, in the pixel a5 corresponding to the location to which the pressure P is applied, the migrating particles 32 move to the second electrode 16 side and display black (dark display). In this way, the plurality of display elements 10 are partially driven, and the locus drawn with a pen or the like is displayed (displayed on the display surface S1) (step S24). As described above, the path 41 including the pressure-sensitive conductive layer 18 and the third electrode 19 is selected by the switch 41, so that the display element 10 corresponding to the pressurization location is directly connected (via a display drive circuit or the like). A voltage is applied (an electric field is generated). In the display element 10, the migrating particles 32 move to the second electrode 16 side, and the display state changes. Thereby, a black line is drawn on the display surface S1 of the display device 1 along the trace traced with a pen or the like. That is, handwriting input is realized.

Note that the pen that pressurizes the display surface S1 does not need to be a pen dedicated to the display device 1, and the shape and structure thereof are not particularly limited as long as the pressure can be applied to the display surface S1. In the above example, the case of drawing a black line on a white background (white background color) has been described. However, it is also possible to draw a white line on a black background (black background color).

[Action, effect]
In the present embodiment, two paths of a path R1 including the TFT 12A and a path R2 including the pressure-sensitive conductive layer 18 and the third electrode 19 are formed as voltage application paths to the first electrode 13 of the display element 10. These routes R1 and R2 are selected by the switch 41. Thereby, when the path R1 is selected, display driving (active matrix driving) using the TFT 12A is possible. On the other hand, when the path R2 is selected, the display surface S1 is pressed (pressed), whereby a voltage can be directly applied to the display element 10 at the pressed position. In addition, the pressure-sensitive conductive layer 18 is disposed below the TFT layer 12, and the electrical connection between the pressure-sensitive conductive layer 18 and the first electrode 13 is performed through the through electrode 11 </ b> A provided on the first substrate 11. Secured through. Compared with the case where the pressure-sensitive conductive layer 18 is disposed in the pixel circuit (in the TFT layer 12), the influence on the circuit layout is small.

This makes it possible to switch between display by driving using the TFT 12A (video display) and display by direct driving of the display element 10 (handwriting input). In addition, the influence of the pressure-sensitive conductive layer 18 on the circuit layout can be reduced, and the reduction in resolution and aperture ratio can be suppressed.

In the present embodiment, the first electrode 13 and the through electrode 11A are formed for each display element 10, so that the locus of the pressed portion can be displayed in units of pixels. For this reason, it is possible to refine the drawing line width. In addition, since the pressure-sensitive conductive layer 18 is connected to the first electrodes 13 via the through electrodes 11A, the display for each display element 10 can be made uniform and sharp lines with little unevenness can be drawn. it can.

Here, the deformation range of the pressure-sensitive conductive layer 18 varies depending on the magnitude of the pressure applied to the display surface S1. That is, when the pressure is high (when strongly pressed), the deformation is in a wide range, and when the pressure is low (when lightly pressed), the deformation is in a narrow range. For this reason, the number of pixels to which a voltage is applied in the width direction is large when the pressure is strongly applied and decreases when the pressure is lightly applied. Therefore, since the display can be performed in units of pixels as described above, it is possible to draw with a thick line width when strongly pressed and with a thin line width when lightly pressed. The drawing line width can be expressed by the writing pressure during handwriting.

Furthermore, in the present embodiment, at the time of handwriting input, it is possible to change the display state by directly applying a voltage to the display element 10 using the pressure-sensitive conductive layer 18. Compared with a display device, latency (delay) is less likely to occur. That is, in a display device using a touch panel, after the position of a part input by a pen or the like is detected by a sensor, the signal processing system performs arithmetic processing on the detected position information. On the basis of the result of this calculation process, the locus of pen input is displayed on the display. As described above, when a touch panel is used, it takes time for position detection and calculation processing between input (pressurization) and display, so that it is perceived as latency by human eyes. On the other hand, in the present embodiment, the pressure-sensitive conductive layer 18 is used, so that it is directly applied to the display element 10 at the pressurization location without going through the position detection and calculation processing steps as in the case of using the touch panel. The display state can be changed by applying a voltage to. For this reason, it is possible to shorten the time from input to image display, and to realize a comfortable writing feeling as if drawing on paper without latency.

In addition, since the pressure-sensitive conductive layer 18 is disposed below the TFT layer 12, the following effects can be obtained. Here, FIG. 18A schematically shows a main configuration of a display device according to Comparative Example 1. In this display device, a support substrate 1017 is provided on a display body 1015, and a pressure-sensitive conductive layer 1020 is further disposed on the support substrate 1017. In this case, although direct handwriting input is possible, since the thickness of the pressure-sensitive conductive layer 1020 is in addition to the thickness of the support substrate 1017, the surface of the display body 1015 on which an image is actually formed and the input pen (stylus) The distance between the 50 nibs increases. For this reason, for example, the appearance when viewed from an oblique direction is different from that when viewed from the front direction (parallax dp ₁₀₀ is generated). In addition, in order to dispose the pressure-sensitive conductive layer 1020 on the display surface side, it is desirable that the pressure-sensitive conductive layer 1020 is transparent and has excellent optical characteristics so as not to cause a decrease in luminance or resolution. There are few such material choices and it is not practical. Further, when the pressure-sensitive conductive layer 1020 is disposed on the display surface, the extraction efficiency of display light (reflected light) is reduced, and it is difficult to secure desired brightness.

In contrast, in the present embodiment, the pressure-sensitive conductive layer 18 is disposed below the TFT layer 12A, that is, below the display body 10A (the pressure-sensitive conductive layer 18 is disposed above the display body 10A). It has not been). Accordingly, as schematically illustrated in FIG. 18B, the distance between the surface of the display body 10 </ b> A on which an image is actually formed and the pen tip of the input pen 50 becomes smaller than that of the first comparative example. As a result, for example, the parallax can be reduced (dp ₁ <dp ₁₀₀ ) so that the appearance when viewed from an oblique direction is almost the same as when viewed from the front direction.

Further, since the pressure-sensitive conductive layer 18 is disposed below the display body 10A, the transparency and optical characteristics of the pressure-sensitive conductive layer 18 are not particularly limited. For this reason, the choice of the material which comprises the pressure-sensitive conductive layer 18 spreads.

As described above, in the present embodiment, as the voltage application path to the first electrode 13 of each display element 10, the path R1 including the TFT 12A, the path R2 including the pressure-sensitive conductive layer 18 and the third electrode 19 Is formed, and a switch 41 for selecting these paths R1 and R2 is provided. This makes it possible to switch between display (video display) by driving using the TFT 12A and display (handwriting input) by direct driving of the display element 10. In addition, since the pressure-sensitive conductive layer 18 is disposed below the TFT layer 12, the influence on the circuit layout is reduced compared with the case where the pressure-sensitive conductive layer 18 is disposed in the pixel circuit, and the resolution and aperture ratio are reduced. Reduction can be suppressed. Therefore, it is possible to realize video display and handwriting input while suppressing a decrease in resolution and aperture ratio.

Hereinafter, modifications of the above embodiment will be described. In addition, the same code | symbol is attached | subjected about the component similar to the said embodiment, and the description is abbreviate | omitted suitably.

<Modification 1>
19A to 19C are schematic cross-sectional views for explaining the drive operation (partial erase operation) of the display device according to this modification. FIG. 20 is a circuit diagram for explaining a voltage application path in the erase mode. In the display device 1 of the above-described embodiment, it has been described that the switch 41 can switch between video display by TFT driving and handwritten input using the pressure-sensitive conductive layer 18, but as in this modification example, It is also possible to drive to partially erase displayed characters and pictures.

For example, as shown in FIG. 19A, when handwriting is input (when the path R2 is selected by the switch 41), the voltage Vsig (for example, −15V) is applied to the third electrode 19, and the voltage Vcom (for example, 0V) is applied to the second electrode 16. ) Are applied, and when the pressure P is applied to the display surface S1, for example, the black and negatively charged migrating particles 32 move to the second electrode 16 side at this pressurization portion, and a black display is obtained. As a result, the locus traced with a pen or the like is drawn as a black line on the display surface S1 (writing mode). This is as described in the above embodiment.

However, in this modification, thereafter, as shown in FIG. 19B, the display body 10A is driven to apply an electric field having a polarity opposite to that in the handwriting input (writing mode). That is, the polarity of the bias voltage applied between the first electrode 13 and the second electrode 16 is reversed. For example, the voltage Vsig (for example, +15 V) is applied to the third electrode 19, and the voltage Vcom (for example, 0 V) is applied to the second electrode 16.

In this state, when the pressure P is applied to the display surface S1, as shown in FIG. 19C and FIG. 20, the voltage Vsig (for example, +15 V) is applied to the first electrode 13 at the pressurization location via the path R2. Supplied. Thereby, for example, the black and negatively charged electrophoretic particles 32 move to the first electrode 13 side and display white. That is, it is possible to erase any part of the black lines drawn on the display surface S1 with a pen or the like (erase mode). In this way, by switching the polarity of the bias voltage applied between the first electrode 13 and the second electrode 16, the migrating particles 32 are moved to the electrode side opposite to that at the time of writing, and the display state is inverted. Can do. Therefore, a part of the line drawn on the display surface S1 can be selectively erased. Alternatively, it is possible to erase all the drawn lines and display the whole as white. As described above, in this modification, the writing mode and the erasing mode can be switched at an arbitrary timing. For example, rewriting or repetitive writing can be performed. These drive operations can be performed by a display control unit (a display control unit 30 and a drive circuit unit 30A described later).

In the first modification, the case where the line drawn on the display surface S1 by handwriting input is manually erased has been described. However, the erase mode in the first modification is executed after the image is displayed by TFT driving. It may be. For example, in a state where the path R1 is selected by the switch 41, the TFT 12A is driven for each display element 10 to display an image on the display surface S1, and then the switch 41 switches from the path R1 to the path R2. Thereafter, for example, a voltage capable of transitioning from black display to white display is applied to the third electrode 19 as the voltage Vsig. In this state, by partially pressurizing the display surface S1, any part of the displayed video (image) can be erased corresponding to the pressurization location.

Further, when the above writing and partial erasure are performed in a state where auxiliary lines such as ruled lines are displayed on the display surface S1, some of the ruled lines may be erased in the erase mode. In such a case, the TFT drive may be selected by the switch 41, and the ruled line may be displayed (redrawn) on the display surface S1 again using the TFT 12A.

<Modification 2>
FIG. 21 is a block diagram for explaining operation control of the display device 1 using the input pen 50 according to the second modification. FIG. 22 is a schematic cross-sectional view illustrating an example of a display state in the erase mode. In the first modification, it has been described that the writing mode and the erasing mode can be switched at an arbitrary timing. However, in the present modification, these two modes are automatically changed according to the direction of the tip of the input pen 50. Switching control is performed. In the present modification, the switch 41 is controlled such that the switch 41A is turned off and the switch 41B is turned on (the third electrode 19 is connected to the voltage application unit 40).

The display device 1 includes the display element 10 described above, and a display control unit 30 and a drive circuit unit 30A for driving and controlling each display element 10. The display control unit 30 generates signals necessary for display driving of the plurality of display elements 10, and includes, for example, a timing controller and a display signal generation unit. The drive circuit unit 30A includes a gate drive circuit unit and a source drive circuit unit for driving each display element 10 based on a control signal supplied from the display control unit 30, and a power source for the voltage application unit 40 and the like. It is a circuit part containing. The input pen 50 used in this modification has an inclination sensor 51 inside. The tilt sensor 51 has a function of recognizing the direction of the tip of the input pen 50, that is, whether the pen tip is facing upward or downward. The inclination sensor 51 recognizes (detects) the direction of the tip of the input pen 50, and information (information Ds) regarding the detected direction can be transmitted to the display control unit 30 by wireless, for example. Note that the display control unit 30 and the drive circuit unit 30A in the present modification correspond to a specific example of the “display control unit” of the present disclosure.

The display control unit 30 can receive the information Ds transmitted from the tilt sensor 51, and switches the display state of each display element 10 based on the received information Ds. Specifically, the display control unit 30 sets the sign of the bias voltage applied to the display body 10A (specifically, the value of the voltage Vsig supplied to the first electrode 13) based on the information Ds (or Switch).

As an example, when the information Ds indicates that the tip of the input pen 50 (the pen tip 50A) is facing down, the “write mode” is set as, for example, black and negatively charged electrophoretic particles. The polarity of the bias voltage is set (switched) so that 32 moves to the second electrode 16 side. Accordingly, when the pen tip 50A is pressed against the display surface S1, the “writing mode” is executed, and the voltage Vsig corresponding to the writing mode is supplied to the first electrode 13 through the path R2. As a result, the migrating particles 32 at the pressurized location move to the second electrode 16 side, for example, and display black. That is, a black line corresponding to the locus of the input pen 50 is drawn on the display surface S1.

On the other hand, when the information Ds indicates that the pen tip 50A is facing upward, as an “erasing mode”, for example, the black and negatively charged migrating particles 32 are directed to the first electrode 13 side. The polarity of the bias voltage that moves is set (switched). Thereby, for example, as shown in FIG. 22, when the pen tip 50A is pressed upward, that is, when the pen bottom 50B is pressed against the display surface S1, the “erase mode” is executed. Then, the voltage Vsig corresponding to the erase mode is supplied to the first electrode 13 via the path R2. As a result, the migrating particles 32 at the pressurization location move to the first electrode 13 side, and white display is performed. That is, some or all of the lines drawn on the display surface S1 can be erased.

As in this modification, by using the input pen 50 having the tilt sensor 51, for example, the user can automatically switch between the writing mode and the erasing mode only by changing the direction of the tip of the input pen 50. Thereby, the user can perform a series of input operations such as writing lines and characters on the display surface S1 and partially erasing the written part as if using a pencil with an eraser. it can.

<Modification 3>
FIG. 23 schematically illustrates a cross-sectional configuration of the pressure-sensitive conductive layer 18 according to the third modification. In the pressure-sensitive conductive layer 18 of this modification, a plurality of grooves 18a are provided on at least one surface (for example, the surface S21) side of the surface S22 on the display element 10 side and the surface S21 on the third electrode 19 side. ing.

The plurality of grooves 18a are formed so as to extend in one direction in plan view (in the XZ plane), and as a whole have a so-called stripe shape or lattice shape. The cross-sectional shape (XY cross-sectional shape) of each groove 18a is, for example, a triangular shape. However, the cross-sectional shape of the groove 18a is not limited to this triangular shape, and may take various shapes such as a rectangular shape, a semicircular shape, and an elliptical shape. The inside of the groove 18a may be, for example, a cavity, or may be filled with resin, rubber, adhesive, or the like. When filling with a resin or the like, for example, it is preferable to fill with a material softer than the pressure-sensitive conductive layer 18. The groove 18a may penetrate the pressure-sensitive conductive layer 18, and the pressure-sensitive conductive layer 18 may be divided into a plurality of parts. Further, the arrangement pitch, number, size, and the like of the grooves 18a are not particularly limited. The layout of the grooves 18a may be appropriately set according to the material used for the pressure-sensitive conductive layer 18, the thickness, the required line width, and the like. As a constituent material of the pressure-sensitive conductive layer 18 of this modification, the same materials as those in the above embodiment can be exemplified.

Here, FIG. 24A schematically shows a change in shape of the pressure-sensitive conductive layer 18 having no groove 18a in a pressurized state as Comparative Example 2 of the present modification. When the pressure-sensitive conductive layer 18 is made of pressure-sensitive conductive rubber, when the pressure P is applied, the pressure-sensitive conductive layer 18 is in a range where the pen tip is actually in contact with the display surface S1 (pressure application range). It bends (deforms) in a wider range B1. For this reason, a voltage is applied to the display elements 10 arranged in this range B1, and the display state of these display elements 10 changes. Therefore, the drawn line width may be thicker than the actually used pen tip width.

Therefore, by providing a plurality of grooves 18a in the pressure-sensitive conductive layer 18 as in this modification, for example, as shown in FIG. 24B, the expansion of deformation due to the application of pressure P is blocked by the grooves 18a. . That is, the deformation range (range B2) of the pressure-sensitive conductive layer 18 when pressure is applied is limited by the groove 18a, and a voltage is applied only to the display element 10 arranged in this range B2. Therefore, in the pressure-sensitive conductive layer 18, the range B <b> 2 that is deformed by pressure application can be brought close to the actual pressure application range. Compared to the second comparative example, the drawing line width can be made thinner.

It should be noted that the interval (pitch) of the grooves 18A is desirably as small as possible, thereby enabling drawing with a line having a finer width.

<Modification 4>
FIG. 25 illustrates a cross-sectional configuration of a display device (display device 2) according to Modification 4. The display device 2 is a reflective display device that displays an image by light reflectance control using a display element (display element 10) such as an electrophoretic display element, for example, as in the display device 1 of the above-described embodiment. . The display device 2 includes a TFT layer 12 and a plurality of display elements 10 arranged in a matrix, for example, on a first substrate 11. In each display element 10, a display body 10 </ b> A and a spacer 15 are provided between the first electrode 13 and the second electrode 16, and a second substrate 17 is provided on the second electrode 16. A seal layer 14 is interposed between the first electrode 13 and the display body 10A. FIG. 1 schematically shows the configuration of the display device 1 and may differ from actual dimensions and shapes.

Similarly to the above embodiment, the pressure-sensitive conductive layer 18, the third electrode (third electrode 19 </ b> A), and the support substrate 20 are provided below the TFT layer 12, specifically, on the back surface of the first substrate 11. ing. Although not shown in FIG. 25, also in this modification, the path 41 including the TFT 12A and the path R2 including the pressure-sensitive conductive layer 18 can be switched by the switch 41.

However, in this modification, unlike the above embodiment, a color filter layer (color filter layer 21) is provided between the second electrode 16 and the second substrate 17. That is, the display device 2 of the present modification is a color reflection type electrophoretic display device. In the present modification, the third electrode 19A includes a plurality of sub-electrodes 19R, 19G, and 19B (the third electrode 19A is divided into a plurality of sub-electrodes 19R, 19G, and 19B). . For the sake of explanation, FIG. 25 shows a region including the color filter 21G and the display element 10 facing the pixel a7, and a region including the color filter 21B and the display element 10 facing the pixel a8. A region including 21R and the display element 10 opposed thereto is shown as a pixel a9.

The display state of the pixel a7 changes between green (green display) and black (black display) according to the bias voltage applied to the display body 10A. The display state of the pixel a8 changes between blue (blue display) and black (black display) according to the bias voltage applied to the display body 10A. The display state of the pixel a9 changes between red (red display) to black (black display). Depending on the combination of the display states of these pixels a7, a8, and a9, in addition to white display and black display, display of any color can be performed.

The color filter layer 21 includes multiple color filters 21R, 21G, and 21B such as red (R), green (G), and blue (B). The color filters 21R, 21G, and 21B are arranged in a stripe shape in plan view, for example. The color filter 21R selectively transmits, for example, light having a wavelength corresponding to red in light (white light) emitted from the display body 10A. The color filter 21G selectively transmits, for example, light having a wavelength corresponding to green among light (white light) emitted from the display body 10A. The color filter 21B selectively transmits light having a wavelength corresponding to blue out of light (white light) emitted from the display body 10A, for example.

The sub-electrodes 19R, 19G, and 19B constituting the third electrode 19A are opposed to the color filters 21R, 21G, and 21B, respectively, and have a stripe shape as a whole. That is, the sub electrode 19R is disposed to face the color filter 21R, the sub electrode 19G is disposed to face the color filter 21G, and the sub electrode 19B is disposed to face the color filter 21B. FIG. 26 shows a configuration example of the sub electrodes 19R, 19G, and 19B. A plurality of display elements 10 (for example, a plurality of display elements 10 arranged side by side in the row direction or the column direction) are arranged in a region facing each of the sub-electrodes 19R, 19G, 19B.

These sub-electrodes 19R, 19G, and 19B can be supplied with different (or the same) voltages when handwriting input is selected by the switch 41.

With the above configuration, in this modification, the same or different voltage Vsig is supplied to each of the sub-electrodes 19R, 19G, and 19B in the third electrode 19A, for example, at the time of handwriting input. This makes it possible to draw with a line of any color.

For example, a voltage Vcom (0V) is applied to the second electrode 16 by a voltage application unit 40 (not shown), -15V is supplied to the sub-electrodes 19R and 19G, and 0V is supplied to the sub-electrode 19B. In this state, when the display surface S1 is pressurized by the input pen 50, the pressure-sensitive conductive layer 18 is deformed and the path R2 is formed at the pressure locations (here, the pixels a7, a8, and a9). Thereby, −15 V is supplied to the first electrode 13 in the pixels a7 and a9, and 0 V is supplied to the first electrode 13 in the pixel a8. As a result, as shown in FIG. 27, for example, the black and negatively charged migrating particles 32 move to the second electrode 16 side in the pixels a7 and a9, and remain on the first electrode 13 side in the pixel a8. Therefore, the pixels a7 and a9 display black, and the pixel a8 emits blue light LB. That is, in this example, the locus traced by the input pen 50 is drawn as a blue line.

As in the present modification, in the color reflective display device 2, the third electrode 19A is divided into a plurality of sub-electrodes 19R, 19G, and 19B, whereby handwritten input (drawing with a colored pen) is performed with an arbitrary color line. ) Can be performed.

Further, since the third electrode 19A is subdivided into sub-electrodes 19R, 19G, and 19B, a finer drawing line width can be realized than in the above embodiment. For example, as schematically shown in FIG. 27, the pen tip 50A of the input pen 50 is larger than the scale of one pixel. Further, as described in Modification 3 above, the deformation range of the pressure-sensitive conductive layer 18 is wider than the range where the pen tip 50A is actually in contact with the display surface S1. For this reason, the drawing line width tends to be thick, but in this modification, the voltage can be driven in units of sub-electrodes even during handwriting input, so the drawing line width can be refined. .

<Modification 5>
FIG. 28 illustrates a cross-sectional configuration of a display device according to the fifth modification. In the fourth modification, in the color reflective display device 2, the third electrode 19A is divided into a plurality of sub-electrodes 19R, 19G, and 19B corresponding to the filter arrangement of the color filter layer 21, but the third electrode 19A This configuration can also be applied to a monochrome reflection type display device as in this modification. In the present modification, the TFT layer 12, the first electrode 13, the seal layer 14, the display body 10 </ b> A, the second electrode 16, and the second substrate 17 are provided on the first substrate 11 as in the above embodiment. A pressure-sensitive conductive layer 18 and a third electrode 19A are formed on the back surface of the first substrate 11. The third electrode 19A is divided into a plurality of sub-electrodes 19A1, 19A2, and 19A3.

The sub-electrodes 19A1, 19A2, and 19A3 are formed in a stripe shape as a whole, similarly to the sub-electrodes 19R, 19G, and 19B of the fourth modification. In addition, a plurality of display elements 10 (for example, a plurality of display elements 10 arranged side by side in the row direction or the column direction) are arranged in regions facing the sub-electrodes 19A1, 19A2, and 19A3. Each of the sub-electrodes 19A1, 19A2, and 19A3 can be supplied with different (or the same) voltages when handwriting input is selected by the switch 41.

Thus, even in a monochrome reflection type display device, the third electrode 19A may be divided. In this case, as in the case of the modification example 4, a finer drawing line width can be realized than in the embodiment. That is, since voltage driving can be performed in units of sub-electrodes, lines can be displayed regardless of the deformation range of the pressure-sensitive conductive layer 18 (in a range narrower than the deformation range).

<Application example>
Next, application examples of the display device (display device 1 is taken as an example) described in the above embodiments and modifications will be described. However, the configuration of the electronic device described below is merely an example, and the configuration can be changed as appropriate.

FIG. 29 shows the appearance of a tablet personal computer. The tablet personal computer has, for example, a display unit 310 and a housing 320, and the display unit 310 is configured by the display device 1 of the above embodiment.

In addition, the display device 1 of the above embodiment may be applied to an electronic bulletin board or the like.

As described above, the embodiments and modifications have been described, but the present disclosure is not limited to the aspects described in the above-described embodiments and the like, and various modifications are possible. For example, in the above-described embodiment, the configuration including the insulating liquid 31, the migrating particles 32, and the porous layer 33 is illustrated as the display body 10A of the display element 10 (electrophoretic display element). Are not limited to those using such a porous layer 33, but may be any as long as the contrast can be formed by light reflection for each pixel using the electrophoresis phenomenon. For example, a capsule type or a type without a fibrous structure (colored liquid itself) may be used.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

Further, the present disclosure can take the following configurations.
(1)
A plurality of display elements each having a display body between a first electrode and a second electrode facing each other, and a display state changing according to an applied voltage;
A thin film transistor that is provided for each display element and performs switching for applying a voltage to the first electrode;
A pressure-sensitive conductive layer formed below the thin film transistor; and
A third electrode connected to the first electrode via the pressure-sensitive conductive layer;
As a voltage application path to the first electrode, a switch for selecting one of a first path including the thin film transistor and a second path including the pressure-sensitive conductive layer and the third electrode is provided. Display device.
(2)
A first substrate provided between the thin film transistor and the pressure-sensitive conductive layer;
The display device according to (1), further including a through electrode provided through the first substrate and electrically connecting the pressure-sensitive conductive layer and the first electrode.
(3)
The display device according to (2), wherein the through electrode is provided for each display element.
(4)
The thin film transistor has a gate electrode, a source electrode, and a drain electrode,
The drain electrode of the thin film transistor is electrically connected to the first electrode;
The switch is configured to selectively connect one of the source electrode and the third electrode of the thin film transistor to a power source. The switch according to any one of (1) to (3), Display device.
(5)
A display control unit for controlling the voltage applied to the display element to drive the display element;
The display control unit, when writing to a part of the plurality of display elements, and the second path is selected by the switch,
The display device according to any one of (1) to (4), wherein a voltage having a polarity opposite to a voltage at the time of writing is applied.
(6)
When writing is performed using a pen that can recognize the direction of the tip and has a sensor capable of transmitting information on the direction of the tip.
The display control unit
Receiving information about the orientation of the tip from the pen;
The display device according to (5), wherein driving is performed to change a display state of the display element based on the received information.
(7)
The display device according to any one of (1) to (6), wherein the pressure-sensitive conductive layer has a groove on at least one of the third electrode side and the display element side.
(8)
The display device according to any one of (1) to (7), wherein the third electrode is provided as a common electrode in each region corresponding to each of the plurality of display elements.
(9)
The third electrode includes a plurality of electrically separated sub-electrodes;
When the second path is selected by the switch, a voltage can be applied to a selective sub-electrode of the plurality of sub-electrodes. (1) to (8) The display device according to any one of the above.
(10)
Provided with a color filter layer including a plurality of color filters on the light emitting side of the display element,
The display device according to (9), wherein each of the plurality of sub-electrodes is provided in a region corresponding to any one of the color filter layers.
(11)
The display device according to (9) or (10), wherein the plurality of sub-electrodes form a stripe shape as a whole.
(12)
The display device according to any one of (1) to (11), wherein the display element is an electrophoretic display element.
(13)
The display device according to (12), wherein the electrophoretic display element is a microcup type electrophoretic display element.
(14)
The display device according to (12), wherein the electrophoretic display element is a microcapsule electrophoretic display element.

This application claims priority on the basis of Japanese Patent Application No. 2015-142644 filed on July 17, 2015 at the Japan Patent Office. The entire contents of this application are incorporated herein by reference. This is incorporated into the application.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims (14)

A plurality of display elements each having a display body between a first electrode and a second electrode facing each other, and a display state changing according to an applied voltage;
A thin film transistor that is provided for each display element and performs switching for applying a voltage to the first electrode;
A pressure-sensitive conductive layer formed below the thin film transistor; and
A third electrode connected to the first electrode via the pressure-sensitive conductive layer;
As a voltage application path to the first electrode, a switch for selecting one of a first path including the thin film transistor and a second path including the pressure-sensitive conductive layer and the third electrode is provided. Display device. A first substrate provided between the thin film transistor and the pressure-sensitive conductive layer;
The display device according to claim 1, further comprising: a through-electrode that is provided through the first substrate and electrically connects the pressure-sensitive conductive layer and the first electrode. The display device according to claim 2, wherein the through electrode is provided for each display element. The thin film transistor has a gate electrode, a source electrode, and a drain electrode,
The drain electrode of the thin film transistor is electrically connected to the first electrode;
The display device according to claim 1, wherein the switch is configured to selectively connect one of the source electrode and the third electrode of the thin film transistor to a power source. A display control unit for controlling the voltage applied to the display element to drive the display element;
The display control unit, when writing to a part of the plurality of display elements, and the second path is selected by the switch,
The display device according to claim 1, wherein a voltage having a polarity opposite to a voltage at the time of writing is applied. When writing is performed using a pen that can recognize the direction of the tip and has a sensor capable of transmitting information on the direction of the tip.
The display control unit
Receiving information about the orientation of the tip from the pen;
The display device according to claim 5, wherein driving for changing a display state of the display element is performed based on the received information. The display device according to claim 1, wherein the pressure-sensitive conductive layer has a groove on at least one of the third electrode side and the display element side. The display device according to claim 1, wherein the third electrode is provided as a common electrode in each region corresponding to each of the plurality of display elements. The third electrode includes a plurality of electrically separated sub-electrodes;
The display device according to claim 1, wherein when the second path is selected by the switch, a voltage can be applied to a selective sub-electrode among the plurality of sub-electrodes. Provided with a color filter layer including a plurality of color filters on the light emitting side of the display element,
The display device according to claim 9, wherein each of the plurality of sub-electrodes is provided in a region corresponding to any one of the color filter layers. The display device according to claim 9, wherein the plurality of sub-electrodes form a stripe shape as a whole. The display device according to claim 1, wherein the display element is an electrophoretic display element. The display device according to claim 12, wherein the electrophoretic display element is a microcup type electrophoretic display element. The display device according to claim 12, wherein the electrophoretic display element is a microcapsule electrophoretic display element.

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