JP2015064499A - Drive method of reflection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive method of a reflection type display device that enables a voltage to be effectively applied in a display rewrite step of rewriting displays by applying voltages corresponding to contents of desired displays even with a simple method.SOLUTION: A drive method of a reflection type display device comprises, between an electrode of one substrate and an electrode of other substrate: a display rewrite step of applying a voltage corresponding to a content of a desired display and rewriting the display; and a display retain step of retaining the display rewritten in the display rewrite step. In the display rewrite step, an application of the voltage is executed that follows a preliminarily set reference drive sequence, and furthermore, an additional application of the voltage is repeatedly executed that follows the reference drive sequence.

Description

  The present invention relates to a driving method of a reflective display device applied to electronic paper or the like.

  Recently, as a reflective display device, an electrophoretic display device using an electrophoretic material as an electroresponsive material contained in a display medium has been widely used. An electrophoretic display device is a device that displays information by using electrophoretic migration, that is, particle movement, of an electrophoretic body (usually electrophoretic particles) in air or in a solvent. In general, an electrophoretic state is controlled by applying an electric field between two substrates, thereby realizing a desired display. As the electrophoretic body, charged powder as well as charged particles can be used. In that case, the charged powder electrophoreses in the gas.

  In recent years, the electrophoretic display device has attracted attention especially as an electronic paper. When applied as an electronic paper, it is possible to enjoy advantages such as visibility at the printed matter level (easy for eyes), ease of information rewriting, low power consumption, and light weight.

  More specifically, as a display element of electronic paper, a display element having a memory property with respect to a potential state can be used, so that a display state corresponding to image data can be maintained without continuously supplying energy such as voltage. . In general, air-moving, electrophoretic particle, and two-color rotating particle types are known as display elements for electronic paper. These can change the state of the charged particles in the cell by applying a voltage, thereby making the display state variable. On the other hand, even if voltage application is stopped, the display state can be maintained for a long time.

  In these systems, the position and orientation of the charge particles are changed by applying voltage to electrically move the charge particles. Therefore, in principle, the response to an electric field is extremely high, that is, it is very sensitive to the external environment. For this reason, a display device employing these methods is easily affected by the temperature or humidity around the device. In addition, the electric field response of the display device may change depending on the interval at which the display is switched, the number of times of total rewriting (number of times of cumulative voltage application), and the like.

  Conventionally, since the signal pattern of the driving sequence is fixed, when the electric field responsiveness has changed due to a change in the external environment, the optimum display state cannot be obtained, that is, the contrast is low, An optical defect such as failure to realize a desired reflectance has occurred.

  In order to solve this problem, it has been proposed that a sensor is mounted on a display device to acquire information on the external environment, and the drive sequence is directly corrected accordingly (Patent Document 1, Patent Document 2). . It has also been proposed to store rewrite information such as the number of rewrites and correct the drive sequence in accordance with the information (Patent Documents 3 and 4).

Japanese Patent No. 4196615 JP 2010-256516 A Japanese Patent No. 4621678 Patent No. 4659992

  When correcting a drive sequence based on sensor acquisition information or rewrite information, it is necessary to determine a correction method (program) in advance. However, when factors that affect responsiveness are complexly correlated, it is difficult to specify such a method (program). Further, for example, the correction method (program) is different between an initial state within one week after the display device is manufactured and a state where three years or more have elapsed.

  In addition, when a sensor for measuring the temperature and humidity around the device is mounted, it is necessary to deal with problems such as individual differences in the sensor and deterioration with time of the sensor.

  The present invention has been made based on such circumstances, the purpose thereof is a simple method, but in a display rewriting process in which a display is rewritten by applying a voltage according to the content of a desired display. It is an object of the present invention to provide a driving method of a reflective display device that can effectively apply a voltage. Another object of the present invention is to provide a reflective display device that can cope with such a driving method.

  In the present invention, a display medium including at least one kind of electrically responsive material is sealed between two opposing substrates on which at least one has translucency and each has electrodes formed thereon, A method of driving a reflective display device that performs a desired display when a predetermined electric field is applied between two substrates, wherein a desired display is provided between an electrode on one substrate and an electrode on the other substrate. A display rewriting step of rewriting the display by applying a voltage according to the content of the display, and a display holding step of holding the display rewritten in the display rewriting step, and a reference set in advance in the display rewriting step The method is characterized in that a voltage is applied in accordance with the driving sequence, and the additional application of the voltage in accordance with the reference driving sequence is repeated.

  According to the present invention, since it is a simple method of additionally applying a voltage according to a preset reference drive sequence, it is possible to effectively apply a voltage while not requiring a complicated configuration. A desired display rewriting operation can be realized.

  Preferably, the number of times of additional application of the voltage according to the reference drive sequence repeated in the display rewriting process can be changed. In this case, the voltage can be applied more effectively by changing the setting of the number of times of application in accordance with the degree of change in the responsiveness of the reflective display device.

  Further, depending on the nature of the electrically responsive material, the memory property is strong, and it may be preferable to erase the previous display when rewriting the display. In such a case, in the display rewriting process, it is preferable that the voltage according to the preset reset sequence is applied before the voltage according to the preset reference drive sequence is applied.

  Further, the present invention is a reflective display device that can cope with the driving method as described above. That is, a display medium containing at least one or more kinds of electrically responsive materials is sealed between two opposing substrates on which at least one has translucency and each has electrodes formed thereon. A reflective display device that performs a desired display when a predetermined electric field is applied between the substrates, a signal generation unit that generates a preset reference drive sequence, and the number of times the reference drive sequence is applied Application control for repeatedly applying the reference drive sequence generated by the signal generator between the electrode of one substrate and the electrode of the other substrate by the number of times set in the number setting unit. And a reflection type display device.

  According to the present invention, it is possible to effectively apply a voltage and realize a desired display rewriting operation by repeating the application of a voltage according to a preset reference drive sequence while not requiring a complicated configuration. be able to.

  Preferably, the number-of-times setting unit includes an input unit for inputting the number of times of application by an operator. In this case, for example, the operator can input the number of times of application while looking at the degree of change in the response of the actual reflective display device, so that the voltage can be applied more effectively.

  According to the driving method of the reflective display device according to the present invention, since it is a simple method of additionally applying a voltage according to a preset reference driving sequence, it is effective while not requiring a complicated configuration. Thus, a desired display rewriting operation can be realized.

  Further, according to the reflective display device of the present invention, it is possible to effectively apply a voltage by repeating the application of a voltage according to a preset reference drive sequence while not requiring a complicated configuration. The display rewrite operation can be realized.

It is sectional drawing which shows schematically the structure of the reflection type display apparatus by one embodiment of this invention. FIG. 2 is a plan view showing a pixel electrode formed on the other substrate of the reflective display device shown in FIG. 1. It is a figure which shows the circuit structure of the reflection type display apparatus shown in FIG. It is a voltage waveform diagram which shows the example of a positive reference | standard drive sequence. It is a voltage waveform diagram which shows the example of a negative reference | standard drive sequence. It is a flowchart which shows the image rewriting process by one embodiment of this invention. FIG. 7 is a voltage waveform diagram applied in the case of FIG. 6. It is a flowchart which shows the image rewriting process by other one Embodiment of this invention. FIG. 9 is a voltage waveform diagram applied in the case of FIG. 8. It is a voltage waveform diagram which shows the other example of a reset sequence. It is a figure which shows the example of the voltage waveform corresponding to FIG. 7 for segment type reflection type display apparatuses. It is a voltage waveform diagram which shows the example of the reset sequence for a segment type reflective display apparatus.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a reflective display device according to an embodiment of the present invention. In the reflective display device according to the present embodiment, at least one kind of electricity is provided between two opposing substrates 11 and 16 on which at least one has translucency and electrodes 111 and 161 are respectively formed. A display medium 13 containing a responsive material is sealed, and the display medium 13 displays a desired display when a predetermined electric field is applied between the two substrates 11 and 16. Here, in the specification and claims of the present application, “translucent” means a property of transmitting light. In the present embodiment, the substrate (one substrate 11) arranged on the viewing side has a light-transmitting property such that the total light transmittance is 50% or more, preferably 80% or more, more preferably 90% or more. have.

  In the present embodiment, a common electrode 111 covering at least the display region, a display medium layer 15 in which the display medium 13 is disposed, and a matrix are arranged between one substrate 11 and the other substrate 16. A plurality of electrodes 161 are provided in this order when viewed from the one substrate 11 side toward the other substrate 16 side. Here, in the specification and claims of the present application, the “display area” means an area used for desired display in the reflective display device.

  In the present embodiment, one substrate 11 is disposed on the viewing side, and the other substrate 16 is disposed on the non-viewing side.

  As one substrate 11, a transparent electrode such as polyethylene (PE), polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), or transparent glass, as the common electrode 111, What attached | subjected translucent electrodes, such as an indium tin oxide (ITO), a zinc oxide (ZnO), and a tin oxide (SnO), can typically be used. The common electrode 111 of this embodiment is formed as a common electrode for active matrix driving.

  The common electrode 111 is formed so as to cover at least the display region of the substrate 11 by a coating method, sputtering, vacuum deposition method, CVD method or the like. The common electrode 111 is not necessarily formed with a pattern, and the entire surface of the substrate may be an electrode.

  The thickness of one substrate 11 is preferably 10 μm to 1 mm. If it is thinner than 10 μm, the strength as a panel cannot be obtained and the risk of breakage increases. On the other hand, if it is thicker than 1 mm, the panel weight becomes too heavy and the handling becomes inconvenient and the cost also increases. Because. A suitable thickness range that is difficult to break and easy to handle is about 50 μm to 300 μm.

  A barrier layer may be provided on one substrate 11. The function of the barrier layer is to prevent display deterioration due to moisture entering the cells. The barrier layer may be disposed on the surface of one substrate 11 on which the display medium 13 is disposed (the surface on the display medium side), or provided on the surface opposite to the surface on the display medium side. Also good. Further, the barrier layer may be provided between the one substrate 11 and the common electrode 111. In this embodiment, since one substrate is disposed on the viewing side, the barrier layer needs to be light-transmitting. The barrier layer may be obtained by depositing an inorganic film on one substrate 11, or may be obtained by pasting a film on which a barrier layer has been previously formed on one substrate 11. .

  Further, an ultraviolet cut film or an ultraviolet absorption layer may be provided on the surface of one substrate 11 opposite to the display medium side surface. Alternatively, one substrate 11 itself may have an ultraviolet absorbing function.

  In addition, on the surface opposite to the display medium side surface of one of the substrates 11, as other surface coating layers, an antiglare layer (AG layer), a scratch prevention layer (HC layer), an antireflection layer (AR layer) Etc. may be added.

  One substrate 11 can be applied in either a roll shape or a sheet shape.

  As the other substrate 16, a substrate in which a pixel electrode 161 is formed of a conductive material such as a metal on a display medium side surface such as a resin film, a resin plate, glass, epoxy glass (glass epoxy), or the like can be used. As the pixel electrode 161, a pixel electrode electrically connected to a TFT (Thin Film Transistor) for driving an active matrix is used.

  The other substrate 16 may be a translucent base material. Furthermore, it may be an opaque base material that is translucent, but an opaque glass base material, resin film, resin plate, glass, epoxy glass with the other surface different from the electrode surface roughened. (Garaepo) or the like can be used. In the present embodiment, since the other substrate 16 is disposed at a position opposite to the viewing side, there is no necessity of having translucency. However, when the same physical properties as the one substrate 11 such as thermal expansion characteristics are required, a light-transmitting member similar to the one substrate 11 can be used.

  The thickness of the other substrate 16 is preferably 10 μm to 1 mm, similarly to the thickness of the one substrate 11. If it is thinner than 10 μm, the strength as a panel cannot be obtained and the risk of breakage increases. On the other hand, if it is thicker than 1 mm, the panel weight becomes too heavy and the handling becomes inconvenient and the cost also increases. Because. A suitable thickness range that is difficult to break and easy to handle is about 50 μm to 300 μm.

  Further functional layers can be added to the other substrate 16. For example, a barrier film can be attached on the other substrate 16. Even if a transparent film in which a barrier layer of a transparent inorganic film is formed in advance by vapor deposition or a film in which a non-transparent barrier layer such as a metal film is formed is used as the other substrate 16, the same as this The function can be demonstrated. The barrier film or barrier layer may be provided on the display medium side surface of the other substrate 16 (on the pixel electrode 161), or may be provided on the surface opposite to the display medium side surface.

  Further, an ultraviolet cut film or an ultraviolet absorption layer may be provided on the surface of the other substrate 16 opposite to the surface on the display medium side. Alternatively, the other substrate 16 itself may have an ultraviolet absorbing function.

  The other substrate 16 can be applied in either a roll shape or a sheet shape.

  Here, the circuit configuration of the display region of the reflective display device of this embodiment will be described with reference to FIGS. FIG. 2 is a plan view showing the pixel electrode 161 formed on the other substrate 16, and FIG. 3 is a diagram showing a circuit configuration of the display area of the reflective display device shown in FIG.

  As shown in FIG. 2, in the present embodiment, m × n pixel electrodes 161 are arranged in a matrix so as to cover the display area of the other substrate 16. Each of the pixel electrodes 161 is electrically connected to the TFT 163 including the gate electrode 164, the source electrode 165, and the drain electrode 166 through the drain electrode 166.

  Specifically, in the present embodiment, as shown in FIG. 3, the gate electrodes 164 correspond to m × n pixel electrodes 161 arranged in a matrix, and m × n in a matrix. It is arranged. The m × n gate electrodes 164 are m parallel scanning lines extending in the row direction (lateral direction in FIG. 3) of the arrangement of the plurality of gate electrodes 164, and one end portion is connected to the scanning line driver 17. The scanning lines Y1 to Ym are connected for each row. In addition, m × n source electrodes 165 are arranged in a matrix corresponding to m × n pixel electrodes 161 arranged in a matrix. The m × n source electrodes 165 are n parallel signal lines extending in the column direction (vertical direction in FIG. 3) of the array of the plurality of source electrodes 165, and one end thereof is connected to the signal line driver 18. The signal lines X1 to Xn are connected for each column. In the present embodiment, the common electrode 111 is connected to the GND (hereinafter referred to as “GND”) of the driving device 100. The scanning line driver 17 and the signal line driver 18 are connected to the controller 19.

  The controller 19 outputs control signals for realizing individual pixel electrode control to the scanning line driver 17 and the signal line driver 18 according to the desired display contents.

  Based on the control signal input from the controller 19, the scanning line driver 17 applies an ON potential corresponding to the ON state of the TFT 163 to the gate electrode 164 connected to the m scanning lines Y 1 to Ym at a desired timing. An OFF potential corresponding to the OFF state of the TFT 163 is applied. When no control signal is input from the controller 19 to the scanning line driver 17, the gate electrode 164 connected to the scanning lines Y1 to Ym is in the GND potential state.

  The signal line driver 18 functions as an application control unit of the present invention, and is connected to a signal generation unit 20 that generates a preset reference drive sequence and a number setting unit 21 that sets the number of times of application of the reference drive sequence. On the basis of the control signal input from the controller 19 to the signal line driver 18, the necessity / unnecessity of voltage application to each of the n signal lines X1 to Xn and the sign in the case where necessary are obtained. The positive reference drive sequence generated by the signal generation unit 20 is repeatedly applied by the number of times set by the number setting unit 21 to the positive signal line that requires voltage application and is positive. For a signal line that requires voltage application and is negative, the negative reference drive sequence generated by the signal generation unit 20 is applied the number of times set by the number setting unit 21. Ri is returning adapted to apply. A GND potential is applied to a signal line that does not require voltage application (when a control signal is not input to the signal line driver 18 from the controller 19).

  FIG. 4 is a voltage waveform diagram showing an example of a positive reference drive sequence. According to the positive reference drive sequence shown in FIG. 4, a pulse having a predetermined width (predetermined time width) w1 of the first potential + a (V) that is relatively higher than the GND potential by applying the reference drive sequence once. Is applied five times at a predetermined frequency f1 during a predetermined time t1. On the other hand, FIG. 5 is a voltage waveform diagram showing an example of a negative reference drive sequence. According to the negative reference drive sequence shown in FIG. 5, the second potential −b (V) having a predetermined width (predetermined time width) w2 that is relatively lower than the GND potential by applying the reference drive sequence once. A pulse is applied five times at a predetermined frequency f2 during a predetermined time t2.

  The number setting unit 21 of the present embodiment has an input unit 21A for inputting the number of application times by an operator. Thereby, the operator can input the number of times of application while observing the degree of change in the response of the actual reflective display device.

  When the second potential is applied to the signal line connected to the source electrode 165 while the gate electrode corresponding to the source electrode 165 is in the ON potential state, the source electrode 165 enters the second potential state. When the first potential is applied to the signal line connected to the source electrode 165 while the gate electrode corresponding to the source electrode 165 is in the ON potential state, the first potential state is obtained. Further, the source electrode 165 is in a GND potential state when the signal line connected to the source electrode 165 is connected to GND.

  When the gate electrode 164 of the TFT 163 is in the ON potential state and the source electrode 165 of the TFT 163 is in the second potential state or the first potential state, a voltage is applied to the display medium 13 in the display medium layer 15. It has become.

  Returning to FIG. 1, the display medium layer 15 of the present exemplary embodiment includes a partition wall 12 that partitions a plurality of cells between one substrate 11 and the other substrate 16. Here, the “cell” is an electrophoretic electrophoretic divided between the upper and lower electrode substrates 11 and 16 in order to prevent a display defect, particularly a decrease in contrast, due to sedimentation or uneven distribution of the electroresponsive material. It means a minute migration space of a responsive material, that is, a movement space. In addition, the said movement space may be divided | segmented by other structures, such as a microcapsule. In addition, when the risk of sedimentation or uneven distribution of the electrically responsive material is low, the space between the upper and lower electrode substrates 11 and 16 may not be divided by such a structure.

  The partition wall 12 can be composed of an ultraviolet curable resin, a thermosetting resin, a room temperature curable resin, or the like. As a method for forming the partition wall 12, a mold transfer method such as embossing can be adopted in addition to the photolithography method. Further, a method of manufacturing a structure having a desired pattern as a partition and sticking the structure to one substrate 11 may be employed. The aperture ratio is preferably 70% or more, and particularly preferably 90% or more. The higher the aperture ratio, the wider the displayable area, so that high contrast can be obtained.

  The shape of the unit pattern of the partition wall 12 is basically arbitrary, such as a circle, a lattice, a hexagon, and other polygons. The cell size (pitch) is 0.05 mm to 1 mm, preferably 0.1 mm to 0.5 mm, although it depends on the size of the display panel. Here, the pitch means the distance between the center points of adjacent cells.

  The height of the partition wall 12 is 5 to 50 μm, preferably 10 to 50 μm. If the thickness is 5 μm or less, the amount of ink to be filled is small and sufficient display characteristics, particularly contrast, cannot be obtained. From the viewpoint that good display characteristics can be obtained at a low driving voltage, a height in the range of 10 to 50 μm is preferable.

  Between the top surface of the partition wall 12 and the pixel electrode 161 on the other substrate 16 or another element on the other substrate 16 or the other substrate 16, the top surface of the partition wall 12 and the other substrate 16 An adhesive layer (not shown) for adhering the pixel electrode 161 or the other element on the other substrate 16 or the other substrate 16 may be provided.

  The adhesive layer is formed of a thermoplastic resin such as a polyester-based thermoplastic adhesive with a thickness of 1 μm to 100 μm by, for example, a transfer method or a printing method. Preferably, it is formed with a thickness of 1 μm to 50 μm, particularly preferably with a thickness of 1 μm to 20 μm.

  As an adhesive for forming the adhesive layer, an adhesive using a thermoplastic material is preferable. It has a property of softening by heating and solidifying when cooled, and plasticity is reversible when repeated cooling and heating. It is a material that is kept in a safe manner.

  When an adhesive made of a thermoplastic material is used as the adhesive layer, the adhesive solidified on the transfer sheet substrate is softened by heating to a temperature exceeding the softening temperature, and only on the upper surface of the partition wall. The adhesive can be reliably thermally transferred. Moreover, since the adhesive after thermal transfer is cooled to room temperature and solidified again, tackiness, that is, stickiness, is eliminated. Further, since there is no tack or stickiness, the display medium 13 filled in the cell does not adhere to the adhesive. Then, the adhesive on the top surface of the partition wall is heated again to a temperature exceeding the softening temperature to be softened, so that it has tackiness, that is, stickiness, so that it is securely bonded to the other substrate 16. Since the adhesive after being bonded to the other substrate 16 is not tacked again at room temperature, i.e., there is no stickiness, the display medium 13 does not adhere to the adhesive, and the display quality is not deteriorated. .

  Specifically, thermoplastic base polymers such as ethylene-vinyl acetate copolymer, polyester, polyamide, polyolefin, polyurethane, natural rubber, styrene-butadiene block copolymer, styrene-isoprene block copolymer, styrene-ethylene. A resin mainly composed of a thermoplastic elastomer such as a butylene-styrene block copolymer or a styrene-ethylene-propylene-styrene copolymer, and a tackifier resin or a plasticizer is mainly used.

  In order to increase the adhesion between the partition wall 12 and the adhesive, the partition wall 12 may be subjected to surface treatment by ultraviolet irradiation, plasma treatment, or the like, or a primer may be formed. Alternatively, a silane coupling agent may be added to the adhesive 221.

  The display medium 13 includes at least one kind of electrically responsive material. Examples of the electroresponsive material include a charged particle material and a liquid crystal material, and the charged particle material includes a so-called electrophoretic material in which colored particles such as white, black, and color move in response to an electric field, or two particles. There are materials typified by twist balls that are color-coded and rotated by an electric field, or nanoparticle materials that move by an electric field. On the other hand, the liquid crystal material includes a material for electrically controlling transmission and scattering known as PDLC (Polymer Dispersed Liquid Crystal), a material in which a liquid crystal is mixed with a dye, a cholesteric liquid crystal material, and the like.

  In the present embodiment, the display medium 13 includes a white electrical responsive material and a black electrical responsive material, and the white electrical responsive material is negatively charged and has a black electrical responsiveness. The material is positively charged. As a result, when a potential lower than that of the common electrode 111 is applied to the pixel electrode 161, the negatively charged white electroresponsive material is drawn toward the common electrode 111, and the positively charged black in the display medium 13. The electrically responsive material is drawn toward the pixel electrode 161 side. When a higher potential than the common electrode 111 is applied to the pixel electrode 161, the negatively charged white electroresponsive material is drawn toward the pixel electrode 161, and the positively charged black in the display medium 13 is drawn. The electrically responsive material is drawn toward the common electrode 111 side.

  FIG. 6 is a flowchart showing display rewriting processing according to an embodiment of the present invention, and FIG. 7 is a voltage waveform diagram applied in the case of FIG. In the present embodiment, the common electrode 111 is connected to GND. In the present embodiment, before the first display rewriting process is started, all the scanning lines Y1 to Ym and all the signal lines X1 to Xm are connected to GND.

  When a signal for starting the display rewriting process is input to the controller 19, a control signal corresponding to the input signal is input from the controller 19 to the scanning line driver 17. When the control signal is input to the scanning line driver 17, an ON potential corresponding to the ON state of the TFT 163 is applied from the scanning line driver 17 to all the scanning lines Y1 to Ym, and all of the plurality of gate electrodes 164 are turned on. Switch to potential state.

  Then, based on the control signal for realizing the individual pixel electrode control according to the desired display contents from the controller 19 while all the plurality of gate electrodes 164 of the plurality of pixel electrodes 161 are maintained in the ON potential state. Thus, the signal line driver 18 distinguishes between necessity / unnecessity of voltage application to each of the n signal lines X1 to Xn and a sign in case of necessity, and a signal that requires voltage application and is positive. For the line, the positive reference drive sequence (see FIG. 4) generated by the signal generation unit 20 is repeatedly applied by the number of application times set by the number setting unit 21, and voltage application is necessary and is negative. The negative reference drive sequence (see FIG. 5) generated by the signal generation unit 20 is repeatedly applied to the signal line by the number of applications set by the number setting unit 21. A GND potential is applied to a signal line that does not require voltage application (when a control signal is not input to the signal line driver 18 from the controller 19).

  The positive reference drive sequence is repeatedly applied for the number of times set by the number setting unit 21, so that the negatively charged white electrically responsive material in the display medium 13 is effectively attracted to the pixel electrode 161 side. Thus, the positively charged black electroresponsive material in the display medium 13 is effectively attracted to the common electrode 111 side. Thereby, a desired black and white display can be effectively realized.

  Alternatively, the negative reference drive sequence is repeatedly applied for the number of times set by the number setting unit 21, so that the negatively charged white electroresponsive material in the display medium 13 is effectively applied to the common electrode 111 side. Thus, the positively charged black electroresponsive material in the display medium 13 is effectively attracted to the pixel electrode 161 side. Thereby, a desired black and white display can be effectively realized.

  As described above, according to the present embodiment, the voltage is effectively applied to the display medium 13 in spite of the simple method of additionally repeating the application of the voltage according to the preset reference drive sequence. And a desired display rewriting process can be realized.

  In particular, since the number setting unit 21 having the input unit 21A to which the number of times of application is input by the operator is provided, the operator can set the number of times of application according to the degree of change in the responsiveness of the actual reflective display device. Can be adjusted and input. For this reason, a voltage can be applied much more effectively.

  The input unit 21A may be a button-type device that allows the operator to actually press a number, a device that operates on a screen such as a touch panel, or another type of input device. Also good. The input operation may be performed each time the reflective display device is used, or after the input content is stored and a predetermined period has elapsed since the previous input operation, or when the operator thinks that the input operation is necessary Only may be implemented. In addition, it is preferable that a display device that displays information related to evaluation of display characteristics of the reflective display device is installed in the vicinity of the input unit 21A. In such a case, it is easy to adjust and input the number of times of application while comparing and examining the actual display characteristics of the reflective display device. The display characteristics of the reflective display device are, for example, reflectance and contrast. Moreover, the information regarding the evaluation of such display characteristics is, for example, a gray scale chart or a color chart. These are, for example, color samples formed by printing on the surface other than the display area or on the display area viewing side. When the display color contrast is lower than the information, that is, when the light color reflectance is low and the dark color reflectance is high, input is performed to increase the number of times of application, and conversely, the display color contrast is low. When the information is higher than the information, that is, when the light color reflectance is high and the dark color reflectance is low, it is preferable to perform an input to reduce the number of times of application. Note that instead of the input operation by the operator's manual input, the input operation may be automatically performed according to the output of the sensor that detects the information related to the evaluation of the display characteristics. Furthermore, an input operation may be directly and automatically performed according to the output of a sensor that detects external environment information (such as temperature and humidity).

  The inventor of the present invention has the following knowledge about the change in the responsiveness of the reflective display device. In other words, in charged particle type electrically responsive materials, the responsiveness changes depending on temperature and moisture, and in particular, changes in threshold and response speed are important. These are changes in adsorption energy and charge amount on the interface. This is caused by a change in viscosity of the electroresponsive material.

  Specifically, for example, when the viscosity of the liquid in which the electrophoretic particles are suspended is increased at a low temperature, the resistance of particle movement is increased, so that the response speed is decreased. Alternatively, when water is mixed in the electrically responsive material, the charge balance is lost and the responsiveness speed decreases. In addition, the responsiveness is also changed by the so-called change with time, when the solvent of the electrically responsive material is removed or the charge of the particles themselves is changed.

  The responsiveness of the electrically responsive material also changes depending on the frequency of rewriting. For example, if the particles are in contact with the electrode surface for a long time, the particles are stabilized at the interface and the adsorption becomes strong, and even if an electric field is applied to the particles, it becomes difficult to move. In addition, when the particles repeatedly move, or conversely, when the particles remain stationary for a long time, neighboring particles are adsorbed and aggregated, resulting in a slow response speed.

  When the change in responsiveness as described above occurs, it may occur that the display rewriting process is not sufficient in the conventional one-time reference driving sequence. Specifically, in a single reference driving sequence, the electric energy applied to the electroresponsive material is insufficient, and for example, the reflectance and dynamic range are reduced, the contrast is lowered, and the gradation expression is not good. It is enough.

  In the case where such a concern exists, according to the present embodiment, by additionally applying the reference drive sequence repeatedly, the shortage of electrical energy is compensated, and a desired voltage is reliably applied to the electrically responsive material. As a result, a desired display rewriting operation can be realized.

  The number of times of additional application of the reference drive sequence is one in the examples of FIGS. 6 and 7, but may be two or more. As the number of times increases, the display rewriting operation becomes more reliable, but the time required for the operation becomes longer. Further, it is preferable that the setting of the gap time (interval) between successive reference drive sequences can be changed. Further, it is preferable that the gap time between successive reference drive sequences is short in order to shorten the display rewriting time. Normally, the gap time between successive reference drive sequences is set to a time shorter than the duration of the reference drive sequence, and may be 0 seconds. The present embodiment is characterized in that the reference drive sequence is additionally applied. However, compared with the conventional technique that directly corrects the entire voltage waveform, the memory property that is a feature of the electronic paper is described. There are structural advantages in that it is easy to recognize the visual image quality at the time of additional writing setting that uses overwriting of the image and the electric circuit configuration that simply overwrites the image repeatedly is simple. The difference from the prior art can be determined by knowing in what sequence signal control is performed from the drive circuit configuration.

  As the waveform of the reference drive sequence, for example, a drive sequence that is necessary and sufficient to make a transition between white display and black display in an environment of 40% RH at 25 degrees immediately after the production of the reflective display device is adopted. Can do. Alternatively, a drive sequence that is necessary and sufficient to shift from halftone to white display or black display in an environment of 35% and 10% RH after one day has elapsed after the production of the reflective display device may be adopted. it can. Or you may employ | adopt the drive sequence which gives the electrical energy equivalent to 150% of them.

  Note that depending on the properties of the electrically responsive material, the memory property of the potential state is strong, and it may be preferable to erase the previous display when the display is rewritten. In such a case, in the display rewriting process, it is preferable that the voltage according to the preset reset sequence is applied before the voltage according to the preset reference drive sequence is applied. FIG. 8 is a flowchart showing the image rewriting process in such a case, and FIG. 9 is a voltage waveform diagram applied in the case of FIG.

  When the reset sequence is used as shown in FIGS. 8 and 9, the previous display is effectively erased by stirring the electrically responsive material. As a result, the so-called afterimage remains effectively suppressed, and the display rewriting operation becomes more reliable.

  As the waveform of the reset sequence, a waveform as shown in FIG. 10 can be adopted in addition to the pre-pulse signal as shown in FIG.

  The above description is made for a reflective display device having a pixel electrode 161 electrically connected to a TFT. However, the present invention is also applicable to a segment type reflective display device. is there. FIG. 11 shows an example of a voltage waveform corresponding to FIG. 7 that can be applied to the segment type reflective display device. FIG. 12 shows an example of a reset sequence applicable to the segment type reflective display device. As shown in FIGS. 11 and 12, in the case of a segment type reflective display device, it is not necessary to configure the voltage waveform with a plurality of pulse waveforms, and it is sufficient to simply apply a DC voltage.

11 One substrate 111 Common electrode 12 Partition 13 Ink (display medium)
16 Other substrate 161 Pixel electrode 163 TFT
164 Gate electrode 165 Source electrode 17 Scan line driver 18 Signal line driver 19 Controller 20 Signal generation unit 21 Number setting unit 21A Input unit

Claims (5)

A display medium containing at least one or more kinds of electrically responsive materials is sealed between two opposing substrates, at least one of which has a light-transmitting property and on which electrodes are respectively formed, and the two substrates A method of driving a reflective display device that performs a desired display when a predetermined electric field is applied therebetween,
A display rewriting step of rewriting the display by applying a voltage according to the desired display content between the electrode of one substrate and the electrode of the other substrate;
A display holding step for holding the display rewritten in the display rewriting step;
With
In the display rewriting process, a voltage is applied according to a preset reference drive sequence, and an additional voltage according to the reference drive sequence is further repeated. The method according to claim 1, wherein the number of times of additional application of the voltage according to the reference driving sequence repeated in the display rewriting step can be changed. 3. The method according to claim 1, wherein in the display rewriting step, the voltage is applied according to a preset reset sequence before the voltage is applied according to a preset reference drive sequence. . A display medium containing at least one or more kinds of electrically responsive materials is sealed between two opposing substrates, at least one of which has a light-transmitting property and on which electrodes are respectively formed, and the two substrates A reflective display device that performs a desired display when a predetermined electric field is applied therebetween,
A signal generator for generating a preset reference drive sequence;
A number setting unit for setting the number of application times of the reference drive sequence;
An application controller that repeatedly applies the reference drive sequence generated by the signal generator between the electrode of one substrate and the electrode of the other substrate by the number of application times set in the frequency setting unit;
A reflection type display device comprising: The reflective display apparatus according to claim 4, wherein the number setting unit includes an input unit through which an application number is input by an operator.

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