JP2010204511A - Electrophoretic display, method for driving electrophoretic display, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small electrophoretic display whose switching speed of display is fast even under low temperature. <P>SOLUTION: The electrophoretic display sandwiches a microcapsule 3 containing charged particles and dispersion media for dispersing the charged particles between a semiconductor circuit board S1 in which a driving element having a pixel electrode 13 which is a heating resistor, a transistor 121 for display control, and a transistor 122 for warming control connected to the pixel electrode, a display part R1 having a data line 1D connected to the transistor for display control, a heater line 1H connected to the transistor for warming control, and a scanning line 1S connected to the transistor for display control and the transistor for warming control, and a driving circuit 14 which drives a display part are formed, and a visually transparent common electrode board S2 having an electrode. Thus, display rewriting at fast switching speed is allowed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device, an electrophoretic display device driving method, and an electronic apparatus using the same.

Generally, it is known that when an electric field is applied to a dispersion system in which charged fine particles are dispersed in a liquid, the fine particles move in the liquid by Coulomb force. This phenomenon is called electrophoresis. In recent years, an electrophoretic display device that displays characters and images using this electrophoresis has attracted attention as a new display device. This electrophoretic display device has characteristics such as a display memory property and a wide viewing angle property in a state where voltage application is stopped, and a high-contrast display with low power consumption.
In addition, since the electrophoretic display device is a non-light emitting (reflective) display device, the electrophoretic display device has a feature that it is easier on the eyes than a light emitting display device such as a cathode ray tube or an EL device.

  Such an electrophoretic display device encloses a dispersion medium in which white and black charged particles (fine particles) of different types of charge are dispersed between a pair of substrates having electrodes, in a container such as a microcapsule. Are arranged. In this electrophoretic display device, a voltage is applied between a pair of electrodes for each pixel to cause an electric field to act on charged particles (for example, see Patent Document 1). As a result, the charged particles move. For example, when white charged particles move to the incident light side and black particles move to the opposite side of the incident light, the reflectance with respect to the incident light changes. As a result, the reflected light can be controlled and desired information can be displayed.

  However, in such an electrophoretic display device, there is a problem that the display switching speed is slow because it takes time for the charged particles to move through the dispersion medium. In particular, there is a problem in that the display switching speed is slow because mobility decreases in a low temperature environment, and display switching is hardly possible particularly at 0 ° C. or lower.

JP 2000-66247 A

In order to improve the display switching speed, there is a method in which a heater is installed in the electronic device to warm the entire device. In installing the heater at that time, there are a method in which the heater is separated from the electrophoretic display device and a method in which the heater is incorporated in the electrophoretic display device.
Although the method of installing the heater separately from the electrophoretic display device is simple, there is a problem that the entire casing of the electronic device is enlarged. Furthermore, since heating is performed from the outside of the electrophoretic display device, in order to sufficiently warm the electrophoretic display device to about room temperature, the entire electrophoretic display device needs to be warmed, and it takes time to warm up. is there.

  On the other hand, in the conventional method of incorporating a heater in an electrophoretic display device, a planar heater and an electrode interfere with each other. Therefore, every time the heater is installed with a smaller electrode, the aperture ratio has to be lowered, or vice versa. In order to reduce the heater density so as not to reduce the aperture ratio, the distance between the heater and the pixel to which the display is to be switched has to be increased, and it takes time to heat the rewritten pixel, resulting in poor write response. There was a problem. An object of the present invention is to provide a small electrophoretic display device that has a high display switching speed even at low temperatures.

  The present invention can be realized as the following application examples or forms so as to solve at least one of the above problems.

  Application Example 1 An electrophoretic display device according to this application example includes a data line, a first thin film transistor connected to the data line, and a pixel electrode connected to the first thin film transistor. An electrophoretic display device comprising a microcapsule enclosing a dispersion medium containing charged particles, a heater line that runs parallel to the data line, and a second thin film transistor connected to the heater line, The second thin film transistor is connected to the pixel electrode.

  Application Example 2 In the electrophoretic display device according to the application example described above, the pixel electrode includes a curve between a connection point with the first thin film transistor and a connection point with the second thin film transistor. It is characterized by being formed in a linear shape.

  Application Example 3 In the electrophoretic display device according to the application example described above, the pixel electrode is formed of a heating resistor.

  Application Example 4 In the electrophoretic display device according to the application example, the heating resistor is at least one metal selected from the group including iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, and tungsten, It is characterized by comprising an alloy composed of two or more kinds of metals in the group, and at least one non-metal in the group containing silicon carbide, molybdenum-silicide, and carbon.

  Application Example 5 In the electrophoretic display device according to the application example, the charged particles are at least one of pigment particles, resin particles, and composite particles thereof.

  Application Example 6 In the electrophoretic display device according to the application example, the volume average particle diameter of the charged particles is 0.01 to 10 μm.

  Application Example 7 An electronic apparatus described in this application example includes the electrophoretic display device described in the application example.

  Application Example 8 The driving method of the electrophoretic display device described in this application example includes a heating operation for applying a current to the heater, and an operation for switching the display by applying a voltage between the common electrode and the pixel electrode. A driving method of an electrophoretic display device, wherein the pixel electrode has two connection points, a current flows through the pixel electrode during the heating operation, and a current does not flow through the pixel electrode during the switching operation. It is characterized by that.

  Application Example 9 In the method for driving an electrophoretic display device according to the application example described above, when the temperature is detected by a temperature sensor built in the electrophoretic display device and the temperature is equal to or lower than a preset temperature. The heating operation is performed.

It is sectional drawing which shows the outline of the electrophoretic display device of embodiment concerning this invention. It is a figure which shows the planar structure of the electrophoretic display device of embodiment concerning this invention. It is a top view which shows the structure of 1 pixel area | region of embodiment concerning this invention. It is sectional drawing which shows the structure of a drive element. It is a perspective view which shows the electronic paper which is an example of an electronic device.

  For example, one aspect of the electrophoretic display device includes a semiconductor circuit substrate, a front substrate that is visually transparent and provided with a common electrode, and a dispersion containing charged particles that is disposed between the semiconductor substrate and the front substrate. And a microcapsule enclosing a medium. The semiconductor circuit substrate includes a first thin film transistor, a second thin film transistor, and a pixel electrode, which are arranged in a matrix. Also, the data line, the scanning line, and the heater line are provided, the data line is connected to the first thin film transistor, the scanning line is connected to the gates of the first and second thin film transistors, and the heater line is the second thin film. Connected to the drain of the transistor. A pixel electrode, which is a heating resistor, is disposed between the drain region of the first thin film transistor and the source region of the second thin film transistor. That is, the pixel electrode is connected to the first and second transistors and forms a heating resistor.

In such a configuration, before switching the display in a low temperature environment, the first thin film transistor and the second thin film transistor are turned on, and a potential difference is generated between the data line and the heater line, thereby By energizing the electrodes, it is possible to perform a heating operation to the microcapsules containing the dispersion medium for dispersing the charged particles.
In such a heating operation, the pixel electrode is disposed immediately below the microcapsule element, so that the temperature of the microcapsule element can be raised most efficiently and power consumption during heating can be reduced. Further, the heating time can be shortened, and the time until the display can be switched can be shortened. Further, the required current amount can be reduced, and the reliability and durability of the entire apparatus can be improved. Further, a peripheral circuit with a small allowable current can be used, and the cost can be reduced.
Immediately after the heating operation, the second thin film transistor is turned off, a desired voltage is applied from the data line, and an electric field is applied to the microcapsule between the common electrode and the pixel electrode, thereby displaying Switching is possible. At this time, as display control in the X direction, it is only necessary to control whether or not a potential difference is generated between the potential of the common electrode and the potentials of the data line and the heater line. Display control in the Y direction may be controlled by sequentially scanning the scanning line potential in a time-sharing manner, and switching the display of an arbitrary pixel by aligning the timing of sequential scanning and the display control timing in the X direction. Can do.

  As described above, in this configuration, by performing the heating operation and the display switching operation for each pixel, in addition to a high heating effect on the pixel, a highly visible display can be performed at a sufficiently high speed even in a low temperature environment. It can be rewritten. Furthermore, since the pixel also serves as a heating resistor, there is no need to provide a separate heating element, and there is an advantage that the device can be downsized.

  A microcapsule containing charged particles and a dispersion medium for dispersing the charged particles has a memory property, and once the rewriting is completed, the display state can be maintained. Therefore, the heating operation may be performed just before the rewriting. . The memory property can be achieved by connecting the capacities in parallel or by setting the specific gravity of the electrophoretic particles and the specific gravity of the dispersion in the microcapsules to be approximately the same.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or related code | symbol is attached | subjected to what has the same function, and the repeated description is abbreviate | omitted.

1. Electrophoretic Display Device FIG. 1 is a diagram schematically showing a longitudinal section of an electrophoretic display device according to this embodiment. In the following description, for convenience of explanation, the upper side in FIG.
An electrophoretic display device 100 shown in FIG. 1 includes a circuit substrate (semiconductor circuit substrate, array substrate, TFT substrate, active matrix substrate) S1, a common electrode substrate S2, a microcapsule 3, a circuit substrate S1, and a common electrode substrate S2. And a sealing portion 5 that hermetically seals a gap between the circuit substrate (array substrate) S1 and the common electrode substrate S2.

  The circuit board S1 includes a flat substrate 11, a thin film transistor 12 provided on the upper surface of the substrate 11, a pixel electrode 13, a peripheral circuit 14 that drives the thin film transistor 12, a thin film transistor 12, and a peripheral circuit 14. Are electrically connected to each other. On the other hand, the common electrode substrate S <b> 2 includes a flat substrate 21 and a common electrode 22 provided on the lower surface of the substrate 21. The adhesive 4 includes a microcapsule 3 including a dispersion medium for dispersing charged particles, and is sandwiched between the circuit board S1 and the common electrode substrate S2.

[Whole circuit board]
For example, as illustrated in FIG. 2, the circuit board S <b> 1 includes a plurality of pixels arranged in a matrix in the display region (display unit) R <b> 1. This pixel is arranged at the intersection of the data line 1D, the heater line 1H, and the scanning line 1S. Each pixel includes a thin film transistor 12 (including a display control thin film transistor 121 and a heating control transistor 122 described later) and a pixel electrode 13. Further, each pixel may have an auxiliary capacitor (not shown) in parallel with the pixel electrode. The thin film transistor 12 is driven by a peripheral circuit 14 (including an X driver and a Y driver). For example, the data line 1D and the heater line 1H are driven by the X driver, and the scanning line 1S is driven by the Y driver. Driven. Such peripheral circuits 14 (X driver, Y driver, etc.) for driving the pixels are arranged around the display region R1. This region is referred to as a peripheral circuit region R2.

[Element plane and cross-sectional configuration]
Further, as shown in FIG. 3, the display control thin film transistor 121 which is the first thin film transistor is connected to the data line 1D and the pixel electrode (lower electrode) 13, respectively, and the heating control which is the second thin film transistor. The thin film transistor 122 is connected to the pixel electrode (lower electrode) 13 and the heater line 1H, respectively. As shown in FIG. 4, the display control thin film transistor 121 has a semiconductor film 181 on a gate electrode 16 formed on a base material 11 with a gate insulating film 17 interposed therebetween, and the semiconductor film 181 has a source on both sides. It has a region 181s and a drain region 181d. The source region 181s is connected to the data line 1D. The thin film transistor 122 for controlling heating has a semiconductor film 182 on the gate electrode 16 formed on the base material 11 via the gate insulating film 17, and the semiconductor film 182 has a source region 182s and a drain region 182d on both sides. is doing. The drain region 182d is connected to the heater line 1H. The display control thin film transistor 121 and the heating control thin film transistor 122, the heater line 1H, the data line ID, and the gate insulating film 17 are provided with an interlayer insulating film 19, and the drain region 181d is connected to the pixel electrode 13 and the through hole 191. Connected through. The source region 182s is connected to the pixel electrode 13 through the through hole 192. Note that the circuit diagrams, plan views, and cross-sectional views shown in FIGS. 2, 3, and 4 are examples, and various modifications are possible.

[Pixel electrode]
As long as the pixel electrode 13 is a heating resistor, the type is not limited. For example, a metal such as iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, and tungsten, and an alloy including two or more of these metals and , Non-metals such as silicon carbide, molybdenum-silicide, and carbon. The pattern and film thickness of the pixel electrode 13 are not particularly limited, but are determined in consideration of the resistance value Rp required per pixel in order to function as a heater. In the present embodiment, the pattern of the pixel electrode 13 is formed in a linear shape including a curve. The resistance value R is expressed by the following formula (1) from the resistivity ρ determined by the material, the film thickness d, the width W, and the length L.

  The resistance value required per pixel can be determined by dividing the applicable voltage V by the current Ip per pixel (the following formula (2)).

  The current Ip per pixel can be determined from a value obtained by dividing the current value I calculated from the required power P and the applicable voltage V by the number of pixels np (the following formula (3)).

  The required power P can be determined from the required heat quantity J and the target heating time t (the following formula (4)).

  The required heat quantity J can be determined from the temperature difference ΔT between the initial temperature T1 of the object to be heated and the target temperature T2, and the specific heat Cp and mass M of the object to be heated (the following formula (5)).

  For example, when an A4 size electrophoretic display element is heated from an initial temperature of −20 ° C. to a target temperature of 20 ° C., if the thickness of the element is 40 microns, the required amount of heat is approximately 200 joules. If this reaches the target temperature in 5 seconds, the required power is 40 watts. If the voltage that can be applied is 15 volts, the amount of current required for the entire device is 2.7 amperes. For example, if the number of pixels is about 3 million pixels, the amount of current required per pixel is 0.9 nanoamperes. Since the required resistance value per pixel is 1.7 gigaohms, the resistivity ρ, the film thickness d, the length L, and the width W may be determined so as to achieve this. In the layout of the pixel electrode, it is desirable that the pixel electrode is laid out without any deviation in the effective pixel area. It is desirable that the ratio of the electrode area in the effective pixel area is large.

[Electrophoresis sheet]
The electrophoretic display device 100 includes an adhesive 4 including a microcapsule (electrophoretic display) 3 including charged particles and a dispersion medium that disperses the charged particles, between the circuit substrate S1 and the common electrode substrate S2. . The common electrode substrate S <b> 2 has a common electrode (transparent electrode) 22 disposed on one surface of the base material 21. In the microcapsule 3, a liquid phase dispersion medium and charged particles are enclosed.

[Capsule type]
The microcapsule 3 is configured by encapsulating charged particles and a dispersion medium for dispersing the charged particles in a capsule body (shell). The constituent material of the capsule body (shell) is not particularly limited. For example, various resin materials such as a composite material of gum arabic and gelatin, urethane resin, melamine resin, urea resin, polyamide, and polyether. Of these, one or a combination of two or more can be used.

[Particle dispersion method]
The dispersion of the charged particles in the liquid phase dispersion medium can be performed, for example, by combining one or more of paint shaker method, ball mill method, media mill method, ultrasonic dispersion method, stirring dispersion method and the like. .

[Dispersion medium]
As the liquid phase dispersion medium, a medium having a relatively high insulating property is preferably used. Examples of the liquid phase dispersion medium include various waters (distilled water, pure water, ion exchange water, RO water, etc.), alcohols such as methanol, ethanol, isopropanol, butanol, octanol, ethylene glycol, diethylene glycol, and glycerin, methyl Cellosolves such as cellosolve, ethyl cellosolve, phenyl cellosolve, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl formate, ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, cyclohexanone, pentane , Aliphatic hydrocarbons such as hexane and octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, heptylbenzene, octylben , Aromatic hydrocarbons such as benzenes having a long-chain alkyl group such as nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, methylene chloride, chloroform, carbon tetrachloride, Halogenated hydrocarbons such as 1,2-dichloroethane, aromatic fluorinated rings such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone, nitriles such as acetonitrile, propionitrile, acrylonitrile, N, N- Examples include amides such as dimethylformamide and N, N-dimethylacetamide, carboxylates, and other various oils, and these can be used alone or as a mixture.

[Additive to dispersion medium]
Further, in the liquid phase dispersion medium, if necessary, for example, a charge control agent composed of particles of electrolyte, surfactant, metal soap, resin material, rubber material, oils, varnish, compound, etc., titanium-based cup You may make it add various additives, such as dispersing agents, such as a ring agent, an aluminum coupling agent, and a silane coupling agent, a lubricant, and a stabilizer.

[Dye coloring of dispersion medium]
Furthermore, liquid phase dispersion media include anthraquinone dyes, azo dyes, indigoid dyes, triphenylmethane dyes, pyrazolone dyes, stilbene dyes, diphenylmethane dyes, xanthene dyes, alizarin dyes as necessary. Various dyes such as dyes, acridine dyes, quinoneimine dyes, thiazole dyes, methine dyes, nitro dyes, and nitroso dyes may be dissolved.

[Particle type]
As the charged particles, any particles can be used as long as they are charged and can move in the liquid phase dispersion medium by the action of an electric field. Although not particularly limited, pigment particles, resin particles Alternatively, at least one of these composite particles is preferably used. These particles have the advantage that they are easy to manufacture and the charge can be controlled relatively easily.

  Examples of pigments constituting the pigment particles include black pigments such as aniline black, carbon black, and titanium black, white pigments such as titanium dioxide, antimony trioxide, barium sulfate, zinc sulfide, zinc white, and silicon dioxide, monoazo, and disazo. Azo pigments such as polyazo, yellow pigments such as isoindolinone, yellow lead, yellow iron oxide, cadmium yellow, titanium yellow, antimony, azo pigments such as monoazo, disazo, polyazo, quinacridone red, chrome vermilion, etc. Examples thereof include red pigments, blue pigments such as phthalocyanine blue, indanthrene blue, bitumen, ultramarine blue, and cobalt blue, and green pigments such as phthalocyanine green. Among these, one or a combination of two or more can be used.

  Examples of the resin material constituting the resin particles include acrylic resin, urethane resin, urea resin, epoxy resin, polystyrene, polyester, and the like, and one or more of these are combined. Can be used.

  The composite particles are, for example, composed of pigment particles whose surfaces are coated with a resin material, resin particles whose surfaces are coated with a pigment, or a mixture of a pigment and a resin material mixed in an appropriate composition ratio. Particles and the like.

[Particle size]
The average particle diameter (volume average particle diameter) of the charged particles is preferably from 0.01 to 10 μm, and more preferably from 0.1 to 7.5 μm. If the average particle diameter of the charged particles is too small, a sufficient concealment rate cannot be obtained mainly in the visible light region, and as a result, the display contrast of the electrophoretic display device may be lowered. If the average particle size is too large, depending on the type or the like, the liquid phase dispersion medium tends to settle, which may cause problems such as deterioration in display quality of the electrophoretic display device.

[Adhesive material]
As the adhesive 4, a resin material that is excellent in affinity (adhesion) with the pixel electrode 13, the common electrode 22, and the surface of the microcapsule (electrophoretic display) 3 and excellent in insulation is preferably used. . Examples of such an adhesive include polyethylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polypropylene, AS resin, ABS resin, methyl methacrylate resin, vinyl chloride resin, Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride acrylate 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 terephthalates, polymers Polymers such as butylene terephthalate, polyphenylene oxide, polysulfone, polyamideimide, polyaminobismaleimide, polyethersulfone, polyphenylenesulfone, polyarylate, grafted polyphenylene ether, polyetheretherketone, polyetherimide, polytetrafluoroethylene, polyfluoride Fluorinated resins such as fluorinated ethylene propylene, ethylene tetrafluoride-perfluoroalkoxyethylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polytrifluoroethylene chloride, fluororubber, silicone resin, silicone Silicone resins such as rubber, urethane resins such as polyurethane, and others, methacrylic acid-styrene copolymer, polybutylene, methyl methacrylate-butadiene-styrene Various resin materials, such as copolymers and the like, can be used singly or in combination of two or more of them.

2. Manufacturing method of electrophoretic display device [Coating]
Such an electrophoretic display device 100 is obtained as follows. For example, after the common electrode 22 is formed on the entire surface of the substrate 21, an adhesive 4 in which microcapsules (electrophoretic display) 3 are dispersed is applied on the common electrode 22, and a squeegee (a flat jig). The microcapsule 3 is uniformly arranged on the common electrode 22 by sweeping the surface of the solution using, then the adhesive 4 is solidified and the microcapsule 3 is fixed on the common electrode 22.

[laminate]
Next, the microcapsule 3 of the common electrode substrate S2 coated with the microcapsule 3 and the adhesive 4 is placed on the lower side and laminated (attached) on the circuit board S1. For example, the common electrode substrate S2 coated with the microcapsule 3 and the adhesive 4 is laminated on the circuit substrate S1, and the circuit substrate (array substrate) S1 and the common electrode substrate S2 are pressed while being pressed by a laminator (roller). Glue. The electrophoretic display device 100 is substantially completed through the above steps.

[Selection of base material]
Moreover, although there is no limitation in particular in the material of the base materials 11 and 21, the resin substrate etc. which have flexibility can be used. As the constituent materials, for example, polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, modified polyolefins, polyamides (for example, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, Nylon 12, nylon 6-12, nylon 6-66), thermoplastic polyimide, aromatic polyester and other liquid crystal polymers, polyphenylene oxide, polyphenylene sulfide, polycarbonate, polymethyl methacrylate, polyether, polyether ether ketone, polyether imide, Polyacetal, styrene, polyolefin, polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluorine And various thermoplastic elastomers such as chlorinated polyethylene and the like, or copolymers, blends, polymer alloys and the like mainly containing these, and one or more of these are used in combination. be able to.

[Lamination-related variations]
In the above embodiment, the common electrode substrate S2 having the common electrode 22 is used. However, the substrate 21 having the microcapsule 3 and the adhesive 4 is used on the base material 21. The common electrode 22 may be formed on the microcapsule 3 by peeling.
In the above embodiment, the common electrode substrate S2 having the microcapsule 3 and the adhesive 4 and the circuit substrate S1 are laminated, but the circuit substrate S1 having the microcapsule 3 and the adhesive 4 The common electrode substrate S2 may be laminated.
Alternatively, the common electrode 22 may be formed on the microcapsule 3 after the circuit board S <b> 1 having the microcapsule 3 and the adhesive 4 is formed.

3. Driving Method of Electrophoretic Display Device A driving method in the electrophoretic display device 100 manufactured by the above process will be described below.

  The heating operation is performed as follows. After the potential Vg is generated in the scanning line 1S and the display control transistor 121 and the heating control transistor 122 are turned on, the potential Vd of the data line 1D and the potential Vh of the heater line 1H are set to different values. To do. As a result, power is consumed by the pixel electrode 13 which is a heating resistor, and the microcapsule (electrophoretic display) 3 can be heated. The potential Vc of the common electrode 22 may be between the potential Vd of the data line 1D and the potential Vh of the heater line 1H, and is preferably an intermediate potential between the potential Vd of the data line 1D and the potential Vh of the heater line 1H ( Following formula (6)).

The heating operation may be performed for a predetermined required time from the temperature before heating and the power calculated in advance, but is performed until the temperature of the electrophoretic display device 100 reaches a desired temperature by the temperature sensor. It is desirable.
Whether or not the heating operation is performed may be detected by a temperature sensor incorporated in the electrophoretic display device 100 and a temperature decrease of the electrophoretic display device accompanying a decrease in ambient temperature. The upper limit of the temperature that requires the heating operation is not particularly limited, but it is desirable to perform the heating operation if it is 5 ° C. or less, and it is desirable to always perform the heating operation if it is 0 ° C. or less. In addition, if the electrophoretic display device 100 is heated so that the phenomenon that the previous display state remains in the current display state, i.e., the afterimage phenomenon, is preferable, the temperature of the electrophoretic display device 100 can be reduced. Regardless, the heating operation may be performed in the rewriting operation after the display state is maintained for a long time.

  The display switching operation after the sufficient heating operation is performed as follows. In a pixel that does not require display switching, the potential Vg of the data line 1D, the potential Vh of the heater line 1H, the potential Vc of the common electrode 22, while sequentially changing the potential Vg of the scanning line 1S for each line, May be the same (the following formula (7)).

  On the other hand, in the pixel whose display is to be switched, the potential Vd of the data line 1D and the potential Vh of the heater line 1H are made the same while sequentially changing the potential Vg of the scanning line 1S for each line, and the potential of the common electrode 22 is changed. A potential difference with Vc may be generated (the following formula (8)).

At this time, since Vd = Vh, there is no power consumption in the pixel electrode 13 which is a heating resistor, and display switching of the element is performed due to a potential difference with Vc. In accordance with the electric field generated between the pixel electrode 13 and the common electrode 22, charged particles (colored particles and white particles) are electrophoresed toward one of the electrodes.
For example, when a white particle having a positive charge is used and a colored particle (black particle) having a negative charge is used, if the common electrode 22 is set to a positive potential, the white particle moves to the pixel electrode 13 side. ,get together. On the other hand, the colored particles move to the common electrode 22 side and gather.
Conversely, when the common electrode 22 is set to a negative potential, the white particles move to the common electrode 22 side and gather. On the other hand, the colored particles move to the pixel electrode 13 side and gather.

In such a configuration, by appropriately setting the charge amount of the charged particles (white particles, colored particles), the polarity of the electrodes, the potential difference between the electrodes, and the like, the display surface side (here, FIG. 1) of the electrophoretic display device. On the upper middle side, desired information (image) is displayed according to the combination of the colors of the white particles and the colored particles, the number of particles gathered on the electrode, and the like.
The specific gravity of the charged particles is preferably set to be approximately equal to the specific gravity of the liquid phase dispersion medium. As a result, the charged particles can stay in a certain position in the liquid phase dispersion medium for a long time even after the application of the voltage between the electrodes is stopped. That is, information displayed on the electrophoretic display device is held for a long time.

4). Electronic device The electrophoretic display device as described above can be incorporated into various electronic devices. Hereinafter, an electronic apparatus including the electrophoretic display device will be described.
(Electronic paper)
First, an embodiment in which the electronic apparatus of this embodiment is applied to electronic paper will be described. FIG. 5 is a perspective view illustrating an electronic paper which is an example of the electronic apparatus. An electronic paper 1200 illustrated in FIG. 5 includes a main body 1201 formed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 1202. In such electronic paper 1200, the display unit 1202 includes the electrophoretic display device 100 as described above.

Note that the electronic apparatus according to the present invention is not limited to the application to the electronic paper 1200 described above. For example, a television, viewfinder type, monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, electronic The present invention can also be applied to newspapers, word processors, personal computers, workstations, videophones, POS terminals, devices equipped with touch panels, and the like. The electrophoretic display device can be incorporated in the display portion of these various electronic devices.
It should be noted that the examples and application examples described through the above embodiment can be used in appropriate combination according to the application, or can be used with modifications or improvements, and the present invention is limited to the description of the above embodiment. Is not to be done.

  DESCRIPTION OF SYMBOLS 11 ... Base material, 100 ... Electrophoretic display device, 121 ... Display control thin film transistor, 122 ... Heating control transistor, 13 ... Pixel electrode, 14 ... Peripheral circuit, 15 ... Conductive part, 16 ... Gate electrode, 17 ... Gate insulating film, 181 ... Semiconductor film, 181s ... Source region, 181d ... Drain region, 182 ... Semiconductor film, 182s ... Source region, 182d ... Drain region, 19 ... Interlayer insulating film, 191,192 ... Through hole, 1D ... Data Wire, 1H ... heater wire, 1S ... scanning line, 21 ... substrate, 22 ... common electrode, 3 ... microcapsule, 4 ... adhesive, 5 ... sealing part, 1200 ... electronic paper, 1201 ... main body, 1202 ... display Unit, R1 ... display area, R2 ... peripheral circuit area, S1 ... circuit board, S2 ... common electrode board.

Claims (9)

Data lines,
A first thin film transistor connected to the data line;
A pixel electrode connected to the first thin film transistor;
An electrophoretic display device comprising a microcapsule encapsulating a dispersion medium containing charged particles,
Furthermore, a heater wire running parallel to the data line,
A second thin film transistor connected to the heater wire,
The electrophoretic display device, wherein the second thin film transistor is connected to the pixel electrode. The electrophoretic display device according to claim 1.
The electrophoretic display device, wherein the pixel electrode is formed in a linear shape including a curve between a connection point with the first thin film transistor and a connection point with the second thin film transistor. The electrophoretic display device according to claim 1 or 2,
The electrophoretic display device, wherein the pixel electrode is made of a heating resistor. The electrophoretic display device according to claim 3.
The heating resistor is at least one metal in a group including iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, tungsten, an alloy composed of two or more metals in the group, or silicon carbide, An electrophoretic display device comprising at least one nonmetal selected from the group comprising molybdenum-silicide and carbon. The electrophoretic display device according to claim 1.
The electrophoretic display device, wherein the charged particles are at least one of pigment particles, resin particles, and composite particles thereof. The electrophoretic display device according to claim 5.
The electrophoretic display device, wherein the charged particles have a volume average particle diameter of 0.01 to 10 μm.   An electronic apparatus comprising the electrophoretic display device according to claim 1. A driving method of an electrophoretic display device including a heating operation for applying a current to a heater, an operation for switching a display by applying a voltage between a common electrode and a pixel electrode,
The driving of an electrophoretic display device, wherein the pixel electrode has two connection points, and current flows through the pixel electrode during the heating operation, and current does not flow through the pixel electrode during the switching operation. Method. The method of driving an electrophoretic display device according to claim 8.
A driving method of an electrophoretic display device, wherein a temperature is detected by a temperature sensor built in the electrophoretic display device, and the heating operation is performed when the temperature is equal to or lower than a preset temperature.

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