JP2008180954A - Display device, display device manufacturing method, and electronic paper - Google Patents

Abstract

[PROBLEMS] To cope with an increase in screen size while maintaining low power consumption, and to be able to directly input and display an underline or a memo on a display screen, and to read out the displayed image from the outside. A display device capable of performing the above, a manufacturing method thereof, and electronic paper.
A TFT element 22 that performs switching control of signal supply to the pixel area in each of the plurality of pixel areas, and a switching element that controls switching of signal supply to the pixel area in response to an external pressure input 23 and a holding capacitor 24 for holding a signal, and the switching element 23 includes a semiconductor layer 42 having a channel region 42a and a piezoelectric ferroelectric film 34 formed on the channel region 42a. The capacitor 24 includes a capacitor electrode 44 and a branch portion 28a, and a piezoelectric ferroelectric film 34 sandwiched therebetween, and the branch portion 28a and the data line 25 are made of the same material and are on the same layer. Is formed.
[Selection] Figure 4

Description

  The present invention relates to a display device such as an electrophoretic display device, a method for manufacturing the display device, and electronic paper.

  In recent years, display devices using various electro-optic materials in electrophoretic materials and liquid crystal materials have been provided. Conventionally, a digitizing tablet (digitizing device) for a display panel (display device) using, for example, a light emitting diode has been proposed (see, for example, Patent Document 1). Various types of digitizing devices are known as described in the prior art in Patent Document 1.

The digitizer device allows a user to directly input data by writing a character or a figure or instructing the digitizer array the position of a stylus. Specifically, the following are known.
(1) The stylus tip is in direct contact with the capacitive-resistive array.
(2) An electromagnetic digitizer that interacts with a stylus having a magnetic tip structure or an electromagnetic field generating stylus when a user inputs data and executes a desired operation.
(3) A stylus provided with an RF transmitter for transmitting a signal to the digitizing array.
(4) A light source such as a visible light source or an infrared light source that reflects from the pad is incorporated in the tip of the stylus.
Generally, the digitizer device is prepared separately from the display device when a large work area is required compared to the size of the monitor serving as the display device, and is integrated with the display device when portability is required. ing.
JP 2003-223272 A

  However, the following problems remain in the conventional digitizer apparatus. That is, the conventional digitizer device has a processing speed proportional to the capacity of the processor, and thus it is difficult to cope with an increase in screen size. In addition, it is difficult to reduce power consumption because power is required even during standby when direct input is not performed. Furthermore, it is also required to output the image displayed on the display device as data to the outside.

  The present invention has been made in view of the above-described conventional problems, and can cope with a large screen while maintaining low power consumption. In addition, an underline or a memo is directly input and displayed on the display screen. An object of the present invention is to provide a display device capable of reading out a displayed image from the outside, a method for manufacturing the display device, and electronic paper.

  The present invention employs the following configuration in order to solve the above problems. That is, the display device according to the present invention is an active matrix drive display device in which a plurality of pixel regions having display holding properties are arranged in a plane, and each of the plurality of pixel regions is connected to the pixel region. A selection switching element that performs switching control of signal supply, a pressure-sensitive switching element that is connected to a signal line and performs switching control of signal supply to the pixel area in response to an external pressure input, and the pixel area. A holding capacitor for holding the supplied signal is provided, and the pressure-sensitive switching element includes a semiconductor layer having a channel region, and a piezoelectric film laminated on the channel region, and the holding capacitor has a pair And the ferroelectric film sandwiched between the pair of capacitor electrodes, the one capacitor electrode and the signal line are made of the same material, Characterized in that it is formed on more.

In the present invention, by providing the pressure sensitive switching element, another display by direct input with a pen or the like can be performed on the normal display via the selection switching element. In addition, since the pixel region has display retention, low power consumption and a large screen can be achieved. Then, electric charges are also accumulated in the storage capacitor by supplying an electric signal to the pixel region, so that the display state of the pixel region can be read from the outside. Furthermore, since one capacitor electrode and the signal line can be formed in the same process, the manufacturing is simplified and the cost can be reduced.
That is, when pressure is applied to the pressure-sensitive switching element, charges are generated by piezoelectric conversion in the piezoelectric film provided on the channel region of the semiconductor layer. The pressure-sensitive switching element is turned on by the generated charge. Therefore, a signal is supplied from the signal line to the pixel region. In this way, in addition to the normal display by supplying a signal through the selection switching element, another display such as an underline or a memo by direct input through the pressure-sensitive switching element can be performed. Here, since the pressure-sensitive switching element is a pressure sensor, direct input can be performed using a normal pen capable of applying pressure instead of a power source or a dedicated pen having a special function.
At this time, since the pixel area itself has display retention, it is not always necessary to detect the coordinate position of each pixel area. This eliminates the need for a separate processor for detecting the coordinate position. As a result, no power is required to maintain the display state even during standby, and power consumption can be reduced. Since the pressure-sensitive switching element is provided for each of the pixel regions and functions independently, and the pixel region has display retention, the display screen can be enlarged. Easy.
Further, a 1T1C type ferroelectric nonvolatile memory is constituted by the storage capacitor and the selective switching element. Therefore, the display state in the pixel region can be read out as data by detecting the amount of charge (direction of polarization) accumulated in the storage capacitor via the pressure-sensitive switching element or the selective switching element.
Since the pressure-sensitive switching element has a laminated structure and no movable part is provided when pressure is applied from the outside, for example, pressure is input to a pair of electrodes opposed to each other through a gap. By doing so, as compared with a mechanical switching element in which electrodes are in contact with each other, high reliability can be obtained as a switching element and the life can be extended. That is, for example, in the mechanical switching element having the above-described configuration, the electrodes are deformed by repeated use, so that the electrodes are in contact with each other but are not separated and are short-circuited, or the electrodes are not in contact with each other. Sometimes. Then, such a short circuit state and an open state can be suppressed by utilizing piezoelectric conversion. In addition, the laminated structure facilitates the manufacture of the pressure sensitive switching element.

In the display device according to the present invention, the selection switching element has another semiconductor layer, and the other capacitor electrode, the semiconductor layer, and the other semiconductor layer are made of the same material. It is preferable to form on one layer.
In this invention, since the other capacitor electrode, the semiconductor layer, and the other semiconductor layer can be formed in the same process, the manufacturing can be further simplified and the cost can be reduced.

In the display device according to the present invention, the semiconductor layer may include a source region that is electrically connected to the signal line.
In the present invention, when the pressure-sensitive switching element is turned on, a signal is supplied from the signal line to the pixel region via the source region.

In the display device according to the present invention, it is preferable that the selection switching element is connected to the signal line.
In this invention, the number of signal lines can be reduced and the structure can be simplified by supplying the signal supplied from the selective switching element to the pixel area and the signal supplied from the pressure-sensitive switching element to the pixel area from a common signal line. become.

In the display device according to the present invention, the selection switching element is preferably connected to another signal line.
In the present invention, driving for performing normal display and driving by direct input can be adjusted to have different display characteristics. In addition, when direct input is performed, voltage application to other signal lines to which the selective switching element is connected is not performed, so that generation of leakage current due to the selective switching element can be suppressed. Similarly, when performing normal display, by not applying a voltage to the signal line to which the pressure-sensitive switching element is connected, it is possible to suppress the occurrence of leakage current due to the pressure-sensitive switching element.

In the display device according to the present invention, it is preferable that the piezoelectric film and the ferroelectric film are made of the same material.
In the present invention, the piezoelectric film and the ferroelectric film can be formed in the same process, and the manufacturing process can be simplified.

In the display device according to the present invention, it is preferable that the piezoelectric film and the ferroelectric film are made of an organic material.
In the present invention, since the piezoelectric film and the ferroelectric film can be formed by using a liquid phase method such as a droplet discharge method or a spin coating method, the manufacturing cost can be reduced. Further, a low temperature process can be used as compared with the case where the piezoelectric film and the ferroelectric film are formed of an inorganic material.

The display device according to the present invention may include a microcapsule enclosing the electrophoretic dispersion and a pair of substrates sandwiching the microcapsule.
In the present invention, a pixel region having display retention is formed by a microcapsule enclosing an electrophoretic dispersion.

The display device manufacturing method according to the present invention is an active matrix drive display device in which a plurality of pixel regions having display retention properties are arranged in a planar shape, and switching the supply of signals to the pixel regions is performed. Forming a selective switching element to be controlled; forming a pressure-sensitive switching element that is connected to a signal line and performs switching control of signal supply to the pixel region in response to external pressure input; and Forming a storage capacitor that holds a signal supplied to the region, and forming the pressure-sensitive switching element includes forming a semiconductor layer having a channel region, and a piezoelectric layer stacked on the channel region. Forming the body capacitor, and the step of forming the storage capacitor is sandwiched between the pair of capacitor electrodes and the pair of capacitor electrodes. Characterized by a step of forming a ferroelectric film.
In the present invention, as described above, another display can be performed on the normal display, and the power consumption and the screen can be increased. Further, the display state of the pixel area can be read from the outside. Since one capacitor electrode and the signal line can be formed in the same process, the manufacturing is simplified and the cost can be reduced.

In the method for manufacturing a display device according to the present invention, the selective switching element has another semiconductor layer, and the other capacitor electrode, the semiconductor layer, and the other semiconductor layer are made of the same material. At the same time, it is preferably formed on the same layer.
In the present invention, similar to the above, the manufacturing can be further simplified and the cost can be reduced.

In the method for manufacturing a display device according to the present invention, it is preferable that the piezoelectric film and the ferroelectric film are made of the same material.
In the present invention, as described above, the piezoelectric film and the ferroelectric film can be formed in the same process, and the manufacturing process can be simplified.

An electronic paper according to the present invention includes the above-described display device.
In the present invention, as described above, another display can be performed on the normal display, and the power consumption and the screen can be increased. Further, the display state of the pixel area can be read from the outside.

[Electrophoretic display device]
Hereinafter, an embodiment of an electrophoretic display device according to the present invention will be described with reference to the drawings. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size. Here, FIG. 1 is a schematic sectional view of an electrophoretic display device, FIG. 2 is an equivalent circuit diagram of the electrophoretic display device, FIG. 3 is a plan configuration diagram showing a pixel region of the electrophoretic display device, and FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 3, and FIG. 4B is a cross-sectional view taken along the line BB ′ of FIG.

First, a schematic configuration of the electrophoretic display device (display device) 1 in the present embodiment will be described.
As shown in FIG. 1, an electrophoretic display device 1 according to the present embodiment includes a first substrate (one substrate) 11 that is an active matrix substrate, and a second substrate (the other substrate) that is disposed to face the first substrate 11. ) 12 and an electrophoretic layer 13 sandwiched between the first substrate 11 and the second substrate 12. Here, in the electrophoretic display device 1, the outer surface of the second substrate 12 (side away from the electrophoretic layer 13) is the display surface. In addition, the electrophoretic display device 1 includes a protective film 14 that covers the entire outer surface of the second substrate 12.
In the electrophoretic display device 1, an image display area is provided in the area where the electrophoretic layer 13 is formed.

In the image display area of the electrophoretic display device 1, a plurality of pixel areas 15 are arranged in a matrix as shown in FIG.
In each of the plurality of pixel regions 15, a pixel electrode 21, a TFT (Thin Film Transistor) element (selection switching element) 22 and a switching element (pressure-sensitive switching element) 23 for controlling the switching of the pixel electrode 21 are provided. Is provided. In the image display area, a plurality of data lines (signal lines) 25, scanning lines 26, polarization processing lines 27, and capacitance lines 28 are arranged in a grid pattern.

The TFT element 22 has a source connected to the data line 25, a gate connected to the scanning line 26, and a drain connected to the pixel electrode 21. The switching element 23 has the same configuration as the TFT element 22, and has a source connected to the data line 25, a gate connected to the polarization processing line 27, and a drain connected to the pixel electrode 21. The storage capacitor 24 is provided so as to be connected in parallel with a capacitor component formed between the pixel electrode 21 and the common electrode 29, and is configured to hold an image signal and a signal by direct input.
The data line 25 is configured to supply an image signal supplied from a drive circuit (not shown) provided outside the image display area to each pixel area 15. The scanning line 26 is configured to supply a scanning signal supplied from the driving circuit to the pixel region 15. The capacitor line 28 connects the storage capacitor 24 provided in each pixel region 15. Further, the polarization processing line 27 connects the gates of the switching elements 23 provided in each pixel region 15.

Next, a detailed configuration of the electrophoretic display device 1 will be described with reference to FIGS. 3 and 4. 3 and 4 show an example of the configuration of the pixel region 15, and the arrangement of each member may be appropriately changed according to the design. Here, in FIG. 3, illustration of the second substrate 12 is omitted. In FIG. 2, the direction along one side of the substantially rectangular pixel region 15 in plan view is defined as the X-axis direction, and the direction along the other side perpendicular thereto is defined as the Y-axis direction.
The first substrate 11 includes a substrate main body 31, a gate insulating film 32, an interlayer insulating film 33, and a piezoelectric ferroelectric film (piezoelectric film, which are sequentially stacked on the inside (electrophoretic layer 13 side) surface of the substrate main body 31. Ferroelectric film) 34 and protective film 35 are provided. The first substrate 11 includes a semiconductor layer (another semiconductor layer) 41, a semiconductor layer 42, a connection electrode 43, a capacitor electrode 44, and an inner surface of the gate insulating film 32 disposed on the inner surface of the substrate body 31. Are arranged on the inner surface of the protective film 35, the scanning line 26 disposed on the inner surface of the piezoelectric ferroelectric film 34, the data line 25 disposed on the inner surface of the piezoelectric ferroelectric film 34, the polarization processing line 27, the capacitor line 28, The pixel electrode 21 is provided.

The substrate main body 31 is made of a material having resistance to process damage when forming an orientation semiconductor such as polysilicon such as glass or quartz.
The gate insulating film 32 is made of an insulating material such as SiO ₂ (silicon dioxide), for example, and is provided so as to cover the semiconductor layers 41 and 42, the connection electrode 43, and the capacitor electrode 44 formed on the substrate body 31. ing.
The interlayer insulating film 33 is made of an insulating material such as SiO ₂ or SiNx (silicon nitride), for example, and is provided so as to cover the gate insulating film 32 and the scanning line 26 formed on the gate insulating film 32. .

The piezoelectric ferroelectric film 34 is, for example, a copolymer of vinylidene fluoride (VDF) and ethylene trifluoride (TrFE) (dielectric constant is 6 to 13, and piezoelectric constant is 0.32 to 0.38 Vm / N, for example). ) Or the like, and a ferroelectric material made of an organic material having a piezoelectric effect. The piezoelectric ferroelectric film 34 is provided so as to cover the entire upper surface of the interlayer insulating film 33. The piezoelectric ferroelectric film 34 covers a channel region 42a (to be described later) of the semiconductor layer 42 through a contact hole H1 penetrating the gate insulating film 32 and the interlayer insulating film 33, and also forms a capacitive electrode through the contact hole H2. 44 is covered.
The protective film 35 is made of, for example, acrylic, and is provided so as to cover the polarization treatment line 27 and the capacitance line 28 formed on the piezoelectric ferroelectric film 34.

As shown in FIGS. 3 and 4, the semiconductor layer 41 is formed to include a region overlapping the scanning line 26 through the gate insulating film 32 in plan view, and is made of an inorganic semiconductor such as polysilicon. In the semiconductor layer 41, a channel region 41a is provided in a region overlapping with the scanning line 26 through the gate insulating film 32 in plan view. Further, the semiconductor layer 41 is provided with a source region 41b and a drain region 41c formed by implanting impurity ions into polysilicon. The TFT element 22 is composed mainly of the semiconductor layer 41.
As the TFT element 22, a high concentration region having a relatively high impurity concentration and a lightly doped drain (LDD) region having a relatively low impurity concentration are formed in the source region 41b and the drain region 41c of the semiconductor layer 41, respectively. An LDD structure may be adopted.

Similar to the semiconductor layer 41, the semiconductor layer 42 is formed to include a region overlapping the polarization treatment line 27 through the gate insulating film 32 in plan view, and is made of an inorganic semiconductor such as polysilicon. In the semiconductor layer 42, a channel region 42 a is provided in a region overlapping the polarization processing line 27 through the piezoelectric ferroelectric film 34 in plan view. Further, the semiconductor layer 42 is provided with a source region (one doped region) 42b and a drain region (the other doped region) 42c formed by implanting impurity ions into polysilicon. The switching element 23 is composed mainly of the semiconductor layer 42 and the piezoelectric ferroelectric film 34.
As the switching element 23, an LDD structure may be adopted as in the TFT element 22.

The connection electrode 43 is formed integrally with the semiconductor layers 41 and 42, and is made of a semiconductor such as polysilicon like the semiconductor layers 41 and 42. The connection electrode 43 connects the drain region 41 c of the semiconductor layer 41 and the drain region 42 c of the semiconductor layer 42. The connection electrode 43 is formed by implanting impurity ions into polysilicon.
The capacitor electrode 44 is formed integrally with the connection electrode 43 and is made of a semiconductor such as polysilicon like the semiconductor layers 41 and 42 and the connection electrode 43. The capacitive electrode 44 overlaps a later-described branching portion 28a of the capacitive line 28 with the piezoelectric ferroelectric film 34 interposed therebetween. The capacitor electrode 44 is formed by implanting impurity ions into polysilicon.

  The scanning lines 26 are arranged along one side direction (Y-axis direction) of the rectangular pixel region 15 in plan view, and are made of a metal material such as Al (aluminum), for example. Further, the scanning line 26 is provided with a branch portion 26a that functions as a gate electrode so as to overlap the channel region 41a through the gate insulating film 32 in plan view.

  The data line 25 is arranged along the other side direction (X-axis direction) of the pixel region 15 in a plan view, and is composed of, for example, a metal material such as Ag or Ni, an electronic conductive polymer material such as polyaniline, or the like. Has been. Since the data line 25 is a wiring that is in direct contact with the piezoelectric ferroelectric film 34, the film forming method of the material forming the data line 25 is a method that does not cause thermal process damage such as plasma to the piezoelectric ferroelectric film 34. That is, a liquid phase film forming method such as a plating method, an ink jet film forming method, or a spin coating method is suitable. In addition, the data line 25 includes a branch portion 25 a that overlaps the source region 41 b of the semiconductor layer 41 through the gate insulating film 32 and the interlayer insulating film 33 in plan view, and a branch portion 25 b that overlaps the source region 42 b of the semiconductor layer 42. Is provided. The branch portion 25 a is connected to the source region 41 b of the semiconductor layer 41 through a contact hole H 3 that penetrates the gate insulating film 32 and the interlayer insulating film 33. Further, the branch portion 25 b is connected to the source region 42 b of the semiconductor layer 42 through a contact hole H 4 that penetrates the gate insulating film 32 and the interlayer insulating film 33.

The polarization processing line 27 is disposed along the other side direction (X-axis direction) of the pixel region 15 in plan view, and is the same material as the data line 25, for example, a metal material such as Ni, or an electronic conductivity such as polyaniline. It is composed of a polymer. Further, the polarization processing line 27 overlaps the channel region 42a of the semiconductor layer 42 through the piezoelectric ferroelectric film 34 in plan view. The polarization treatment line 27 is configured to perform polarization treatment of the piezoelectric ferroelectric film 34 constituting the switching element 23 in each pixel region 15 by applying a voltage.
The capacitance line 28 is arranged along one side direction (X-axis direction) of the pixel region 15 in plan view, and is made of a metal material such as Al / Cu, which is the same material as the data line 25 and the polarization processing line 27. Has been. In addition, the capacitor line 28 is provided with a branch portion (the other capacitor electrode) 28a that overlaps the capacitor electrode 44 through the piezoelectric ferroelectric film 34 in plan view. The capacitor electrode 44, the piezoelectric ferroelectric film 34, and the branch portion 28a constitute a storage capacitor 24.
The relay electrode 45 is made of a metal material such as Ni, which is the same material as the data line 25, the polarization treatment line 27, and the capacitor line 28, or an electron conductive polymer such as polyaniline. The relay electrode 45 is connected to the connection electrode 43 through a contact hole H5 that penetrates the gate insulating film 32, the interlayer insulating film 33, and the piezoelectric ferroelectric film 34.

The pixel electrode 21 is made of, for example, a metal material such as Cu, and has a substantially rectangular shape in plan view. The pixel electrode 21 may be made of metal such as Al, Au (gold), Ag (silver), Pt (platinum), Ni (nickel), Sn (tin), or an alloy thereof, or ITO (indium tin oxide). ) And other conductive oxides such as polyaniline, ionic conductivity such as NaCl, LiClO ₄ and KCl dispersed in matrix resins such as polyvinyl alcohol resin and polycarbonate resin. Polymers may be used.
The pixel electrode 21 is connected to the relay electrode 45 through a contact hole H6 that penetrates the piezoelectric ferroelectric film 34 and the protective film 35. Thereby, the pixel electrode 21 is electrically connected to the drain region 41 c of the semiconductor layer 41 and the drain region 42 c of the semiconductor layer 42.

On the other hand, as shown in FIG. 4, the second substrate 12 includes a substrate body 50 and a common electrode 29 stacked on the surface of the substrate body 50 on the electrophoretic layer 13 side.
The substrate body 50 is made of a flexible material having translucency such as transparent glass or a resin film. Here, as the substrate body 50, polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), or polyethylene (PE) can be used.
The common electrode 29 is made of a translucent conductive material such as ITO. In addition, as the common electrode 29, an ionic substance such as NaCl, LiClO ₄ , KCl or the like is contained in other conductive oxides, electronic conductive polymers such as polyaniline, and matrix resins such as polyvinyl alcohol resin and polycarbonate resin. Dispersed ion conductive polymers are used.

  The electrophoretic layer 13 has a configuration in which a large number of microcapsules 51 are densely arranged. The microcapsule 51 encloses an electrophoretic dispersion liquid 54 composed of electrophoretic particles 52 and a liquid phase dispersion medium 53 that disperses the electrophoretic particles 52, and all of them are formed to have substantially the same diameter. Here, the diameter of the microcapsule 51 is, for example, 50 μm. In the electrophoretic dispersion liquid 54, the distribution state of the electrophoretic particles 52 is changed by applying an electric field, and the optical characteristics of the electrophoretic dispersion liquid 54 are changed.

Here, the electrophoretic particles 52 are organic or inorganic particles (polymer or colloid) having a property of moving by electrophoresis due to a potential difference in the liquid phase dispersion medium 53. Examples of the electrophoretic particles 52 include black pigments such as aniline black, carbon black, and titanium black, white pigments such as titanium dioxide, zinc white, and antimony trioxide, azo pigments such as monoazo, diisazone, and polyazo; Yellow pigments such as indolinone, yellow lead, yellow iron oxide, cadmium yellow, titanium yellow, antimony, azo pigments such as monoazo, disazo, polyazo, red pigments such as quinacridone red, chrome vermilion, phthalocyanine blue, indanthrene blue One type or two or more types of anthraquinone dyes, blue pigments such as bitumen, ultramarine blue, and cobalt blue, and green pigments such as phthalocyanine green can be used. In addition, these pigments include, as necessary, charge control agents composed of particles of electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compounds, titanium-based coupling agents, aluminum-based couplings. A dispersant such as a silane coupling agent, a lubricant, a stabilizer, and the like may be added.
As the electrophoretic particles 52, two types of carbon black, which is a positively charged black pigment, and titanium dioxide, which is a negatively charged white pigment, are used.

As the liquid phase dispersion medium 53, water, methanol, ethanol, isopropanol, butanol, octanol, methyl cellosolve and other alcohol solvents, ethyl acetate, butyl acetate and other esters, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. Ketones, aliphatic hydrocarbons such as pentane, hexane and octane, cycloaliphatic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, Aromatic hydrocarbons such as benzenes with long chain alkyl groups such as decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, methylene chloride, chloroform, carbon tetrachloride, 1,2-di Halogenated hydrocarbons such as Roroetan, it may also be used blended with such surfactant carboxylate or alone, such as a variety of other oils or mixtures thereof.
As a material for forming the wall film of the microcapsule 51, a compound such as a gum arabic / gelatin composite film, a urethane resin, a melanin resin, or a urea resin is used.

  The microcapsule 51 is fixed to the first and second substrates 11 and 12 by a binder (not shown). Here, a binder having good affinity for the wall film of the microcapsule 51, excellent adhesion to the common electrode 29, and insulating properties is used. And as the binder material used for the binder, for example, polyethylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polypropylene, ABS resin, methyl methacrylate resin, vinyl chloride resin, Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride acrylate ester copolymer, vinyl chloride-methacrylic acid copolymer, vinyl chloride-acrylonitrile copolymer, ethylene-vinyl alcohol-chloride Vinyl copolymers, propylene-vinyl chloride copolymers, vinylidene chloride resins, vinyl acetate resins, polyvinyl alcohol, polyvinyl formal, cellulose resins, and other thermoplastic resins, polyamide resins, polyacetals, polycarbonates, polyethylene teres Polymers such as tarate, polybutylene terephthalate, polyphenylene oxide, polysulfone, polyamideimide, polyaminobismaleimide, polyethersulfone, polyphenylenesulfone, polyarylate, grafted polyfinylene ether, polyetheretherketone, polyetherimide Fluorine-based resins such as fluorinated ethylene, polyfluorinated ethylene propylene, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polytrifluoroethylene chloride, and fluororubber , Silicone resins such as silicone resin and silicone rubber, and others include methacrylic acid-styrene copolymer, polybutylene, methyl methacrylate-butadiene-styrene copolymer, etc.

[Method of manufacturing electrophoretic display device]
Next, a method for manufacturing the electrophoretic display device 1 having the above configuration will be described with reference to FIGS. Here, FIGS. 5 and 6 are process diagrams showing the manufacturing process of the first substrate 11.
First, the semiconductor layers 41 and 42, the connection electrode 43, and the capacitor electrode 44 are formed on the substrate body 31. Here, an amorphous semiconductor layer made of amorphous silicon is first deposited using a PECVD (plasma enhancement chemical vapor deposition (plasma CVD)) method or the like. Then, for example, an amorphous semiconductor layer is crystallized by irradiation with an excimer laser of XeCl (xenon chloride) or the like to form a polycrystalline semiconductor layer. Next, patterning is performed using a photolithography technique to form the semiconductor layers 41 and 42, the connection electrode 43, and the capacitor electrode 44 (FIG. 5A).

Next, the gate insulating film 32 that covers the semiconductor layers 41 and 42, the connection electrode 43, the capacitor electrode 44, and the substrate body 31 is formed. Here, the gate insulating film 32 is formed using a CVD method or the like.
Subsequently, the scanning line 26 is formed on the gate insulating film 32. Here, a metal film constituting the scanning line 26 is formed on the gate insulating film 32 using a sputtering method or the like, and this metal film is patterned using a photolithography technique or the like. Thereby, the scanning line 26 is formed.
Then, low-concentration impurity ions are implanted into the connection electrode 43 and the capacitor electrode 44. Here, a resist layer (not shown) that covers the semiconductor layers 41 and 42 is formed. Subsequently, low concentration impurity ions (phosphorus ions) are implanted into the opening region of the resist layer. Thereafter, the resist layer is removed. Thereby, the connection electrode 43 and the capacitor electrode 44 are formed.
Further, high concentration impurity ions are implanted into the semiconductor layers 41 and 42. Here, a resist layer (not shown) that covers the region of the semiconductor layer 42 that becomes the channel region 42a, the connection electrode 43, and the capacitor electrode 44 is formed. Then, high-concentration impurity ions (phosphorus ions) are implanted into the opening region of the resist layer. At this time, the resist layer and the scanning line 26 function as a mask. Thereafter, the resist layer is removed. As a result, source regions 41b and 42b and drain regions 41c and 42c are formed (FIG. 5B).

  Next, an interlayer insulating film 33 that covers the scanning lines 26 is formed on the gate insulating film 32. Here, the interlayer insulating film 33 is formed using a CVD method or the like. Then, contact holes H1 and H2 penetrating the gate insulating film 32 and the interlayer insulating film 33 are formed. At this time, the channel region 42a of the semiconductor layer 42 is exposed by the contact hole H1, and the capacitor electrode 44 is exposed by the contact hole H2 (FIG. 5C).

Next, a piezoelectric ferroelectric film 34 that covers the interlayer insulating film 33 is formed. Here, a liquid material in which an organic material constituting the piezoelectric ferroelectric film 34 is dispersed or dissolved in a solvent is used by a spin coating method, an inkjet method, an LSMCD (Liquid Source Misted Chemical Deposition) method, or the like. After applying and removing the solvent, low-temperature heat treatment (about 140 ° C.) is performed. If necessary, lyophilic treatment may be performed on the application region, or lyophobic treatment may be performed on other regions. Here, the LSMCD method creates a mist with a uniform particle size and forms a uniform film at room temperature. Thereby, the piezoelectric ferroelectric film 34 is formed (FIG. 6A).
Subsequently, the data line 25, the polarization processing line 27, the capacitor line 28 and the relay electrode 45 are formed on the piezoelectric ferroelectric film 34. Here, a metal film constituting the data line 25, the polarization treatment line 27, the capacitor line 28 and the relay electrode 45 is formed on the piezoelectric ferroelectric film 34 by using a liquid phase method such as an electroless plating method. Patterning is performed so as to remove the formation regions of the contact holes H <b> 3 to H <b> 5 in the metal film using a lithography technique, a wet etching method, or the like. Then, contact holes H3 to H5 that penetrate through the gate insulating film 32, the interlayer insulating film 33, and the piezoelectric ferroelectric film 34 are formed using the remaining metal film as a mask. Further, a metal film constituting the data line 25, the polarization treatment line 27, the capacitance line 28, and the relay electrode 45 is formed, and this metal film is formed on the data line 25, the polarization treatment line 27 using a photolithography technique or a wet etching method. Then, patterning is performed in the shape of the capacitor line 28 and the relay electrode 45. Thereby, the data line 25, the polarization processing line 27, the capacitor line 28, and the relay electrode 45 are formed (FIG. 6B). At this time, the branch portion 25a of the data line 25 is connected to the source region 41b via the contact hole H3, the branch portion 25b is connected to the source region 42b via the contact hole H4, and the relay electrode 45 is connected via the contact hole H5. To the connection electrode 43.

Next, a protective film 35 that covers the data line 25, the polarization processing line 27, the capacitor line 28, the relay electrode 45, and the piezoelectric ferroelectric film 34 is formed. Here, a liquid material in which acrylic constituting the protective film 35 is dispersed or dissolved in a solvent is applied using a spin coating method or the like, and the solvent is removed. Thereby, the protective film 35 is formed (FIG. 6C). Then, a contact hole H6 that penetrates the protective film 35 is formed.
Subsequently, the pixel electrode 21 is formed on the protective film 35. Here, a conductive material constituting the pixel electrode 21 is formed using a liquid phase method such as an electroless plating method, and is patterned using a photolithography technique or a wet etching method. Thereby, the pixel electrode 21 is formed. Note that the pixel electrode 21 may be formed using other methods. At this time, the pixel electrode 21 is connected to the relay electrode 45 through the contact hole H6 (see FIG. 4). The first substrate 11 is manufactured as described above.

  Thereafter, the microcapsule 51 is fixed between the first substrate 11 and the second substrate 12 using a binder, and the electrophoretic layer 13 is formed. As described above, the electrophoretic display device 1 as shown in FIGS. 1 to 4 is manufactured.

[Operation of electrophoretic display device]
Next, the operation of the electrophoretic display device 1 having the above configuration will be briefly described.
First, a normal image display method will be described. When a scanning signal is input from the scanning line 26 by a driving circuit provided outside the image display area, the TFT element 22 is turned on for a certain period. Then, when an image signal is input to the TFT element 22 that has been turned on, the image signal is written to the pixel electrode 21. The written image signal is held between the pixel electrode 21 and the common electrode 29. Therefore, for example, when an image signal in which the pixel electrode 21 is positive and the common electrode 29 is negative is input, the electrophoretic layer 13 disposed between the pixel electrode 21 and the common electrode 29 is configured to be positively charged. The black electrophoretic particles 52 are moved to the common electrode 29. Thereby, black display of the pixel region 15 is performed. As described above, normal image display is performed.
At this time, since the electrophoretic layer 13 has display retention, the display state of the pixel region 15 is maintained. Therefore, once a desired display is performed, it is not necessary to supply power until another display is performed, and the display state is maintained until a signal is supplied again. The image signal input to the pixel electrode 21 is held by the holding capacitor 24. In addition, by inputting a reverse voltage between the pixel electrode 21 and the common electrode 29, that is, a signal that makes the pixel electrode 21 negative and the common electrode 29 positive, the image display state is returned to the initial state. Can do.

Next, in addition to normal image display, another image display method by direct input such as an underline or a memo will be described. When pressure is applied to the pixel region 15 from the second substrate 12 side with, for example, a pen, charges are generated in the piezoelectric ferroelectric film 34 due to piezoelectric conversion. As a result, the switching element 23 is turned on for a certain period. Then, when a signal is input from the data line 25 to the switching element 23 that is turned on, the signal is written to the pixel electrode 21 as described above. Thereby, the black display of the pixel area 15 to which pressure is applied is performed as described above. As described above, another image is displayed by direct input.
At this time, since it is only necessary to apply an appropriate pressure to the switching element 23, it is not necessary to use a power source or a dedicated pen having a special function. Similarly to the above, once a desired display is performed, it is not necessary to supply power until another display is performed, and the display state is maintained until a signal is supplied again. Similarly to the above, the signal input to the pixel electrode 21 is also held in the holding capacitor 24. Note that an image display state can be returned to an initial state by inputting a signal having a reverse voltage between the pixel electrode 21 and the common electrode 29.
Here, when the switching element 23 is turned on, a signal having a reverse voltage is input between the pixel electrode 21 and the common electrode 29 to bring the white electrophoretic particles 52 to the common electrode 29 side. The electrophoretic display device 1 may be provided with a partial erase button for moving the black electrophoretic particles 52 to the pixel electrode 21 side. Thereby, in a state where the image is displayed, it is possible to erase like a “eraser” by tracing a desired portion in the display with a pen. Here, partial erasing can be performed efficiently by using a pen with a thick pen tip.

  Next, a method for reading an image in the pixel area 15 will be described. When a read signal that is a pulse signal is input from the capacitor line 28 toward the storage capacitor 24, the input signal is output to the outside from the data line 25 through the storage capacitor 24 and the TFT element 22. At this time, by inputting a scanning signal from the scanning line 26 to the TFT element 22 in accordance with the input of the readout signal, the TFT element 22 provided in the pixel region 15 to which the readout signal is input is turned on. Here, the intensity of the read signal to be output changes according to the direction of polarization held in the holding capacitor 24. As described above, the display state of the pixel region 15 is read from the outside.

[Electronic paper]
The electrophoretic display device 1 having the above configuration is used as a display unit 101 of an electronic paper 100 as shown in FIG. The electronic paper 100 includes a display unit 101, a main body unit 102, and an operation unit 103.
The electronic paper 100 displays data and the like recorded in a recording unit (not shown) provided in the main body unit 102 on the display unit 101, and in the state where the data is displayed, a desired content is displayed by the pen 104. It is a so-called “electronic drawing board” that can be rewritten. In addition, the operation unit 103 is provided with an all clear button for completely erasing the image displayed on the display unit 101 and the above-described partial erase button.
Such an electronic paper 100 is suitable for use by a salesman when explaining a product in a small-scale business negotiation. For example, in a state where a catalog of products is displayed, the electronic paper 100 is described with emphasis on the appeal points of the products. can do.

Further, the electrophoretic display device 1 may be used as a display unit 111 of an electronic paper 110 as shown in FIG. The electronic paper 110 includes a substrate body 31 made of a flexible material, a body portion 112 having flexibility similar to that of the substrate body 31, and an operation unit 113 made up of a plurality of membrane switches. ing. In order to configure the element substrate 31 with a flexible material such as a polyolefin-based resin film, for example, the techniques described in Japanese Patent Application Laid-Open Nos. 10-125929 and 10-125931 by the applicant are preferably used. Can be used.
The operation unit 113 includes the above-described all clear button, partial erase button, and the like, and a desired function can be realized by pressing the button portion with the pen 114 or a finger. The plurality of buttons may have the same configuration as the switching element 23. In this case, the necessary number of switching elements 23 are formed on the outer periphery of the display unit 111 by the same process as described above.
The aspect of the electronic paper 110 is close to that of paper, and can be configured to have a thickness of 1 mm or less, for example. For this reason, it is lightweight and easy to hold. For example, it is easy to use by carrying around with a thin paper folder, taking it out when necessary, and explaining the point while marking the point.

  As described above, according to the electrophoretic display device 1 and the manufacturing method of the electrophoretic display device 1 and the electronic paper 100 according to the present embodiment, in addition to the normal image display via the TFT element 22, the switching element 23 directly Images can be displayed by input. In addition, since the electrophoretic layer 13 constituting the pixel region 15 has display retention, low power consumption and a large screen can be achieved. Since the charge amount corresponding to the image signal or the signal directly input is accumulated in the storage capacitor 24, the display state of the pixel region 15 can be output to the outside.

Further, since the switching element 23 is a pressure sensor, direct input using a normal pen or the like that does not require a power source or the like is possible. At this time, the switching element 23 has a configuration in which the semiconductor layer 42 and the piezoelectric ferroelectric film 34 are laminated, and no movable part is provided when pressure is applied from the outside. Improves.
Since the TFT element 22 and the switching element 23 are connected to the common data line 25, the configuration can be simplified.
Furthermore, the data line 25, the polarization processing line 27, the capacitor line 28, and the relay electrode 45 can be formed in the same process, and the semiconductor layers 41, 42, the connection electrode 43, and the capacitor electrode 44 can be formed in the same process. Simplification and cost reduction can be achieved.
Further, by using the piezoelectric ferroelectric film 34 as the piezoelectric film constituting the switching element 23 and the ferroelectric film constituting the storage capacitor 24, it can be formed in the same process as described above. The piezoelectric ferroelectric film 34 is made of an organic material, so that an inexpensive liquid phase method can be applied and the manufacturing cost can be reduced, and a low-temperature process can be used as compared with the case where the piezoelectric ferroelectric film 34 is made of an inorganic material. it can.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the switching element has a configuration in which a semiconductor layer and a piezoelectric ferroelectric film are stacked in this order from the substrate body side, but may also have a configuration in which a piezoelectric ferroelectric film and a semiconductor layer are stacked in order from the substrate body side. Good.
In each pixel region, the TFT element and the switching element are connected to a common data line. However, the TFT element and the switching element may be connected to different data lines (signal lines). As a result, the drive for performing normal display and the drive by direct input can have different display characteristics. For example, the voltage applied to the data line connected to the switching element is made lower than that of the other data line, and the amount of charge accumulated when the switching element is turned on is reduced, thereby making it easier and darker Can be expressed. In addition, when direct input is performed, the application of voltage to the data line connected to the TFT element is not performed, whereby generation of a leakage current due to the TFT element can be suppressed. Similarly, when performing normal display, by not applying a voltage to the data line connected to the switching element, it is possible to suppress the occurrence of leakage current due to the switching element.

In addition, the piezoelectric ferroelectric film is provided so as to cover the interlayer insulating film, but at least in the region corresponding to the channel region of the semiconductor layer constituting the switching element and the capacitor electrode constituting the storage capacitor. Therefore, it may be partially formed only in a desired region using a droplet discharge method or the like. In this way, by forming the piezoelectric ferroelectric film only in the region corresponding to the switching element and the storage capacitor, it is possible to prevent the formation of parasitic capacitance components in other regions.
The piezoelectric film constituting the switching element and the ferroelectric film constituting the storage capacitor are made of the same material, but different materials may be used. Here, the piezoelectric film and the ferroelectric film may be formed on different layers.
In each pixel region, a polarization processing line for connecting the switching element and performing polarization processing of the piezoelectric ferroelectric film is provided, but the polarization processing line may not be provided.
The two semiconductor layers, the connection electrode, and the capacitor electrode are formed of the same material by the same process, but the capacitor electrode is formed of a material different from that of the two semiconductor layers. Also good.

  Further, although the TFT element is used as the selection switching element, other elements such as a TFD (Thin Film Diode) may be used as long as the element controls switching of the pixel electrode.

The electrophoretic layer uses two types of electrophoretic particles, black and white. However, the electrophoretic layer may be composed of black electrophoretic particles and a white liquid phase dispersion medium. Alternatively, the electrophoretic particles and the liquid phase dispersion medium may be sealed between the first and second substrates.
The display device is an electrophoretic display device having an electrophoretic layer. However, the display region only needs to have a display retention property. For example, a display device including a liquid crystal element using a cholesteric liquid crystal or an oxidation-reduction reaction is used. Other display devices such as a display device made of an electrochromic element and a display device made of an element that performs display by inverting particles having two different colors may be used.

It is a schematic sectional drawing which shows the electrophoretic display apparatus of one Embodiment. FIG. 2 is an equivalent circuit diagram of FIG. 1. It is a plane block diagram which shows a pixel area. It is A-A 'arrow sectional drawing of FIG. 3, and B-B' arrow sectional drawing. It is process drawing which shows the manufacturing process of a 1st board | substrate. Similarly, it is process drawing which shows the manufacturing process of a 1st board | substrate. It is a perspective view which shows the electronic paper which has an electrophoretic display apparatus. It is a perspective view which shows the other electronic paper which has an electrophoretic display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophoretic display apparatus (display apparatus), 11 1st board | substrate (one board | substrate), 12 2nd board | substrate (other board | substrate), 15 pixel area, 22 TFT element (selection switching element), 23 switching element (pressure-sensitive switching) Element), 24 storage capacitor, 25 data line (signal line), 28a branch (the other capacitor electrode), 34 piezoelectric ferroelectric film (piezoelectric film, ferroelectric film), 41 semiconductor layer (other semiconductor layers) ), 42 semiconductor layer, 42a channel region, 42b source region, 44 capacitive electrode (one capacitive electrode), 51 microcapsule, 54 electrophoretic dispersion, 100, 110 electronic paper

Claims (12)

An active matrix driving display device in which a plurality of pixel regions having display holding properties are arranged in a plane,
Each of the plurality of pixel regions is supplied with a selection switching element that performs switching control of signal supply to the pixel region, and a signal is supplied to the pixel region in response to an external pressure input connected to the signal line. A pressure-sensitive switching element that performs switching control, and a holding capacitor that holds a signal supplied to the pixel region;
The pressure-sensitive switching element has a semiconductor layer having a channel region, and a piezoelectric film laminated with the channel region,
The storage capacitor has a pair of capacitor electrodes and a ferroelectric film sandwiched between the pair of capacitor electrodes,
The display device, wherein the one capacitor electrode and the signal line are made of the same material and are formed on the same layer. The selective switching element has another semiconductor layer;
The display device according to claim 1, wherein the other capacitor electrode, the semiconductor layer, and the other semiconductor layer are made of the same material and are formed on the same layer.   The display device according to claim 1, wherein the semiconductor layer includes a source region that is electrically connected to the signal line.   The display device according to claim 1, wherein the selection switching element is connected to the signal line.   The display device according to claim 1, wherein the selection switching element is connected to another signal line.   6. The display device according to claim 1, wherein the piezoelectric film and the ferroelectric film are made of the same material.   The display device according to claim 1, wherein the piezoelectric film and the ferroelectric film are made of an organic material.   The display device according to claim 1, comprising: a microcapsule enclosing the electrophoretic dispersion liquid; and a pair of substrates sandwiching the microcapsule. An active matrix driving display device in which a plurality of pixel regions having display holding properties are arranged in a plane,
Forming a selective switching element that performs switching control of signal supply to the pixel region;
Forming a pressure-sensitive switching element that is connected to a signal line and performs switching control of signal supply to the pixel region in response to an external pressure input;
Forming a storage capacitor for holding a signal supplied to the pixel region,
The step of forming the pressure-sensitive switching element includes a step of forming a semiconductor layer having a channel region, and a step of forming a piezoelectric film laminated on the channel region;
The step of forming the storage capacitor includes a step of forming a pair of capacitor electrodes, and a step of forming a ferroelectric film sandwiched between the pair of capacitor electrodes,
The method for manufacturing a display device, wherein the one capacitor electrode and the signal line are made of the same material. The selective switching element has another semiconductor layer;
10. The method for manufacturing a display device according to claim 9, wherein the other capacitor electrode, the semiconductor layer, and the other semiconductor layer are made of the same material and are formed on the same layer.   The method for manufacturing a display device according to claim 9, wherein the piezoelectric film and the ferroelectric film are made of the same material.   An electronic paper comprising the display device according to claim 1.

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