JP2015018117A - Driving method of reflection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method of a reflection type display device which suppresses a voltage load to a TFT and allows a longer life TFT.SOLUTION: A driving method of a reflection type display device is provided. The reflection type display device comprises a plurality of pixel electrodes. Each of the pixel electrodes is electrically connected to a TFT having a gate electrode, a source electrode and a drain electrode, via the drain electrode. The plurality of gate electrodes are connected by row or by column by a plurality of scan lines, and the plurality of source electrodes are connected by row or by column by a plurality of signal lines. The driving method includes: an image writing step; and a drive stopping step of, after the completion of the image writing step, switching all of the plurality of gate electrodes to a GND potential state, and also switching all of the plurality of source electrodes to the GND potential state.

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.

  As an electrophoretic device, a method is adopted in which a pixel electrode is disposed for each pixel, a TFT (Thin Film Transistor) electrode structure is disposed on the pixel electrode, and a voltage is applied to the pixel electrode in an active matrix format. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2009-222901) and Patent Document 2 (Japanese Patent Laid-Open No. 2010-2932) disclose conventional examples of driving methods of such types of electrophoretic display devices.

JP 2009-222901 A JP 2010-2932 A

  Incidentally, in order to extend the life of the TFT connected to the pixel electrode, it is necessary to suppress the voltage load on the TFT.

  The present invention has been made based on such circumstances, and an object of the present invention is to provide a driving method of a reflective display device that suppresses voltage load on the TFT and extends the lifetime of the TFT. .

  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 reflective display device that performs desired display when a predetermined electric field is applied between two substrates, the common electrode covering at least a display region between one substrate and the other substrate, A display medium layer in which a display medium is arranged and a plurality of pixel electrodes arranged in a matrix are provided in this order when viewed from the one substrate side toward the other substrate side. Each of the pixel electrodes is electrically connected to a TFT having a gate electrode, a source electrode, and a drain electrode via the drain electrode, and the plurality of gate electrodes are arranged in a matrix. The multiple Connected to each row or column by a plurality of parallel scanning lines extending in the row or column direction of the gate electrode array, and the ON potential corresponding to the ON state of the TFT and the OFF state of the TFT for each row or column. The state can be selectively switched to the corresponding OFF potential or GND potential state, and the plurality of source electrodes are arranged in a matrix, and the plurality of source electrode arrangement columns or Connected to each column or row by a plurality of parallel signal lines extending in the row direction, and a GND potential, a first potential that is relatively lower than the GND potential, and a potential that is relatively higher than the GND potential for each column or row. The gate electrode is in an ON potential state and the source electrode is in a first or second potential state. A method of driving a reflective display device, wherein a voltage is applied to the display medium in the display medium layer, wherein each scanning line is in an ON potential state. By setting each signal line to the first potential or the second potential, an image writing process for applying a voltage corresponding to image information to the display medium in the cell for each pixel electrode, and after the image writing process is completed And a drive suspension step of switching all of the plurality of gate electrodes of the plurality of pixel electrodes to the GND potential state and switching all of the plurality of source electrodes of the plurality of pixel electrodes to the GND potential state. It is the method characterized by this.

  Preferably, in the driving suspension step, the common electrode is also connected to GND.

  Preferably, the method includes a TFT-ON preceding step of switching all of the plurality of gate electrodes to an ON potential state for a predetermined TFT preceding preparation time before the image writing step, and the TFT-ON After the preceding step, all of the plurality of source electrodes are switched to the first potential or second potential state while maintaining all of the plurality of gate electrodes at the ON potential state for a predetermined first time, and thereafter All of the plurality of source electrodes are changed from the first potential or the second potential state to the second potential or the first potential while maintaining all of the plurality of gate electrodes at the ON potential state for a predetermined second time. And an image erasing step for switching to this state. For example, the TFT advance preparation time is 0.1 to 10 msec.

  In addition, for example, the image erasing process is repeated twice or more between the TFT-ON preceding process and the image writing process.

  Preferably, in the method, the plurality of source electrodes are maintained in an ON potential state for a predetermined third time between the image erasing step and the image writing step. Are all set to the first potential or the second potential, and then the plurality of source electrodes are maintained at the first potential or the second potential for the predetermined TFT-OFF preceding time. TFT-OFF preceding process in which all of the plurality of source electrodes are switched to the GND potential state while all of the plurality of gate electrodes are maintained in the OFF potential state after all of the gate electrodes are set to the OFF potential state. Is further provided. For example, the TFT-OFF time is 1 to 500 msec.

  According to the present invention, all the gate electrodes and all the source electrodes are switched to the GND potential state in the time not involved in the image rewriting after the image writing process, and are set to the same potential. For this reason, the voltage load on the TFT is suppressed, and the life of the TFT can be extended.

FIG. 1 is a cross-sectional view schematically showing a configuration of a reflective display device according to an embodiment of the present invention. FIG. 2 is a plan view showing a pixel electrode formed on the other substrate of the reflective display device shown in FIG. FIG. 3 is a diagram showing a circuit configuration of the reflective display device shown in FIG. FIG. 4 is a flowchart showing image rewriting processing according to an embodiment of the present invention. FIG. 5 is a timing chart showing the potential applied to the scanning line and the potential applied to the signal line in the TFT-ON preceding process, the image erasing process, and the TFT-OFF preceding process. FIG. 6 is a timing chart showing the potential applied to the scanning line and the potential applied to the signal line in the S-th scanning and driving suspension process of the image writing process.

  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.

  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 a control signal to the scanning line driver 17 and the signal line driver 18 based on an input signal input from an input unit (not shown).

  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.

  Based on the control signal input from the controller 19, the signal line driver 18 applies a second potential that is relatively lower than the GND potential or relatively higher than the GND potential to the n signal lines X <b> 1 to Xn. An electric potential is applied. When no control signal is input from the controller 19 to the signal line driver 18, the signal lines X1 to Xn are set to the GND 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 source electrode 165 is in the first potential state. 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 second electrode is in the second potential state. 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 first potential or the second 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.

  Next, a driving method of the reflective display device having such a configuration will be described with reference to FIGS.

  FIG. 4 is a flowchart showing image rewriting processing according to an embodiment of the present invention. FIG. 5 is a timing chart showing potentials applied to the scanning lines Y1 to Ym and potentials applied to the signal lines X1 to Xn in the TFT-ON preceding process, the image erasing process, and the TFT-OFF preceding process. FIG. 6 is a timing chart showing potentials applied to the scanning lines Y1 to Ym and potentials applied to the signal lines X1 to Xn in the S-th scanning and driving suspension process of the image writing process. In the present embodiment, the common electrode 111 is connected to GND, but is not connected to GND at least from the start of the TFT-ON preceding process described later to the end of the image writing process. May be. In the present embodiment, before the image rewriting process is started, all the scanning lines Y1 to Ym and all the signal lines X1 to Xm are connected to GND.

First, when a signal for starting the image 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. Input of the control signal is performed only prior TFT preceding preparation time T _ON than the start of the image erasing step which will be described later. 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. It is switched to a potential state (TFT-ON preceding process). The TFT advance preparation time T _ON is set so that all of the plurality of gate electrodes 164 are turned on when the image erasing process is started in consideration of a signal delay due to the resistance of the scanning lines Y1 to Ym, a response delay of the scanning line driver 17, and the like. It is a sufficient length of time to be in a potential state, and is 0.1 to 10 msec in this embodiment.

Next, in the image erasing process, all signals from the signal line driver 18 are generated based on the control signal 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. to to no line X1 Xn, the first potential is lower than the GND potential is applied for a predetermined first time _{T 1.} Accordingly, all of the plurality of source electrodes 165 are switched to the first potential state lower than the GND potential, and the pixel electrode 161 is set to a relatively lower potential than the common electrode 111. As a result, the negatively charged white electrically responsive material in the display medium 13 is drawn toward the common electrode 111, and the positively charged black electrically responsive material in the display medium 13 becomes the pixel electrode 161. Drawn to the side.

After that, all of the plurality of gate electrodes 164 of the plurality of pixel electrodes 161 are maintained in the ON potential state, and from the signal line driver 18 to all the signal lines X1 to Xn based on the control signal from the controller 19. second potential higher than the GND potential is applied for a predetermined second time T _2. Accordingly, all of the plurality of source electrodes 165 are switched from the first potential state to the second potential state, and the pixel electrode 161 is set to a relatively higher potential than the common electrode 111. As a result, the negatively charged white electroresponsive material in the display medium 13 is attracted to the pixel electrode 161 side, and the positively charged black electroresponsive material in the display medium 13 is Drawn to the side. In this way, the white and black electroresponsive materials are agitated, and the image displayed in the display area is erased. The image erasing process is performed only once in the present embodiment, but may be repeated a plurality of times between the TFT-ON preceding process and the TFT-OFF preceding process described later, preferably two or more times, more preferably Repeated 3 times or more.

  After the image erasing step, all of the plurality of gate electrodes 164 are maintained at the ON potential, and are lower than the GND potential from the signal line driver 18 to all the signal lines based on the control signal from the controller 19. A first potential is applied. Accordingly, all of the plurality of source electrodes 165 are switched to the first potential, and the pixel electrode 161 is set to a relatively lower potential than the common electrode 111. As a result, the negatively charged white electrically responsive material in the display medium 13 is drawn toward the common electrode 111, and the positively charged black electrically responsive material in the display medium 13 becomes the pixel electrode 161. Drawn to the side.

All signal lines to the third time T after ₃ from the first potential is applied to predetermined from the signal line driver 18 after the image erasing step, while all of the plurality of source electrodes 165 is maintained at the state of the first potential, Based on the control signal from the controller 19, an OFF potential corresponding to the OFF 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 in the OFF potential state. Is done. After the OFF potential is applied from the scanning line driver 17 to all the scanning lines Y1 to Ym, after the TFT-OFF preceding time _TOFF , the plurality of gate electrodes 164 are maintained at the OFF potential state, and the plurality of sources are maintained. All of the electrodes 165 are switched to the GND potential state (TFT-OFF preceding step). The TFT-OFF time T _OFF is a time length sufficient to turn off all the TFTs 163 and is 1 to 500 msec in the present embodiment.

  Next, in the image writing process, image data is input to the controller 19, and control signals are input from the controller 19 to the scanning line driver 17 and the signal line driver 18 based on the image data. Based on the control signal, an ON potential for switching the TFT to an ON state or an OFF potential corresponding to the OFF state of the TFT is applied from the scanning line driver 17 to the m scanning lines Y1 to Ym. The ON potential is sequentially applied exclusively to the scanning lines Y1 to Ym, and the OFF potential is applied to the scanning lines to which no ON potential is applied. Further, while the ON potential is applied to each of the scanning lines Y1 to Ym, the signal line driver 18 applies a first potential or a potential to each of the signal lines X1 to Xn corresponding to the image data input to the controller 19. A second potential is applied. As a result, the desired pixel electrode 161 corresponding to the image data is set to the first potential or the second potential, and the white and black electric responses in the display medium 13 correspond to the voltage state of the pixel electrode 161. The active material is moved to the pixel electrode 161 side or the common electrode 111 side. In the present embodiment, by performing such scanning S times, the movement state of the white and black electroresponsive materials in the display medium 13 is controlled so as to correspond to the image data input to the controller 19. The image corresponding to the image data is displayed in the display area of the reflective display device.

  Thereafter, in the driving suspension process, all of the plurality of gate electrodes 164 are switched to the GND potential state, and all of the plurality of source electrodes 165 are switched to the GND potential state. As a result, the display state of the image displayed in the display area of the reflective display device is maintained during the drive suspension process. When the common electrode 111 is not connected to GND, the common electrode 111 may be connected to GND in the drive suspension process.

  According to the present embodiment, all the gate electrodes 164 and all the source electrodes 165 are switched to the GND potential state and set to the same potential in a time not involved in image rewriting after the image writing process. For this reason, the voltage load on the TFT is suppressed, and the life of the TFT can be extended.

  In the drive suspension process, the common electrode 111 is also connected to the GND. In this case, the voltage load on the TFT can be further suppressed.

Further, prior to the image erasing step, a predetermined TFT preceding preparation time _{T ON} only, and a TFT-ON prior step of switching all of the plurality of gate electrodes 164 into the ON state voltage. In this case, before the potential is applied to the signal lines X1 to Xn in order to erase the image displayed on the reflective display device, the TFT is applied to the scanning lines Y1 to Ym connected to the plurality of gate electrodes 164. An ON potential for switching to the ON state is applied. Therefore, even if there is a delay in the transmission of the potential applied to the scanning lines Y1 to Ym to the gate electrode 164 due to the signal delay due to the resistance of the scanning lines Y1 to Ym, the response delay of the scanning line driver 17, etc. In addition, the amount of power consumed by applying potentials to the signal lines X1 to Xn is reduced. Note that when a delay occurs in the transmission of the potential applied to the scanning lines Y1 to Ym to the gate electrode 164, the timing at which the plurality of gate electrodes 164 in the display region are in the ON potential state varies. Even if the first potential or the second potential is applied to all the signal lines X1 to Xn while a part of the gate electrodes 164 is not in the ON potential state in the image erasing process, it corresponds to the part of the gate electrodes 164. The source electrode 165 to be set cannot be in the first potential state or the second potential state. Therefore, a voltage cannot be applied to the display medium 13 by the pixel electrodes 161 corresponding to some of the gate electrodes 164 that are not in the ON potential state. As a result, the electroresponsive material in the display medium layer 15 is not sufficiently stirred, and a part of the image displayed in the display area before the image erasing process may remain.

In addition, according to the present embodiment, a plurality of sources are maintained while maintaining all of the plurality of gate electrodes 164 at the ON potential for a predetermined third time between the image erasing process and the image writing process. All of the electrodes 165 are set to the first potential state, and then all of the plurality of gate electrodes 164 are maintained while maintaining all of the plurality of source electrodes 165 at the first potential state for a predetermined TFT-OFF preceding time T _OFF. Is provided with a TFT-OFF preceding step in which all of the plurality of source electrodes 165 are switched to the GND potential state while all of the plurality of gate electrodes 164 are maintained in the OFF potential state. . Thus, after the image erasing process, before the plurality of source electrodes 165 are switched to the GND potential state, the OFF potential is applied to all the scanning lines Y1 to Ym, and the TFT 163 is turned off. As a result, when the plurality of source electrodes 165 are switched to the GND potential state, the potential of the pixel electrode 161 is prevented from changing rapidly.

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

Claims (7)

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 common electrode that covers at least the display region between one substrate and the other substrate, a display medium layer in which the display medium is disposed, and a plurality of pixel electrodes arranged in a matrix are the one substrate Are provided in this order when viewed in the direction from the other side toward the other substrate side,
Each of the pixel electrodes is electrically connected to a TFT having a gate electrode, a source electrode, and a drain electrode via the drain electrode,
The plurality of gate electrodes are arranged in a matrix, and are connected for each row or column by a plurality of parallel scanning lines extending in the row or column direction of the arrangement of the plurality of gate electrodes, and for each row or column. An ON potential corresponding to the ON state of the TFT, an OFF potential corresponding to the OFF state of the TFT, or a GND potential can be selectively switched,
The plurality of source electrodes are arranged in a matrix, and are connected to each column or row by a plurality of parallel signal lines extending in the column or row direction of the plurality of source electrodes. The potential can be selectively switched between a GND potential, a first potential that is relatively lower than the GND potential, and a second potential that is relatively higher than the GND potential.
A voltage is applied to the display medium in the display medium layer when the gate electrode is in an ON potential state and the source electrode is in a first or second potential state. A method of driving a reflective display device,
An image in which a voltage corresponding to image information is applied to the display medium in the cell for each pixel electrode by setting each signal line to the first potential or the second potential while each scanning line is in the ON potential state. Writing process;
After completion of the image writing step, all of the plurality of gate electrodes of the plurality of pixel electrodes are switched to the GND potential state, and all of the plurality of source electrodes of the plurality of pixel electrodes are also switched to the GND potential state. A pause process;
A method characterized by comprising: The method according to claim 1, wherein the common electrode is also connected to GND in the driving suspension step. Before the image writing process,
A TFT-ON preceding process for switching all of the plurality of gate electrodes to an ON potential state for a predetermined TFT preceding preparation time;
After the TFT-ON preceding step, all of the plurality of source electrodes are kept in the first potential or second potential state while maintaining all of the plurality of gate electrodes in the ON potential state for a predetermined first time. After that, all of the plurality of source electrodes are kept from the first potential or the second potential state to the second potential while maintaining all the plurality of gate electrodes at the ON potential state for a predetermined second time. Or an image erasing step for switching to the first potential state;
The method according to claim 1, further comprising: 4. The method according to claim 3, wherein the TFT advance preparation time is 0.1 to 10 msec. 5. The method according to claim 3, wherein the image erasing step is repeated twice or more between the TFT-ON preceding step and the image writing step. Between the image erasing step and the image writing step,
All of the plurality of source electrodes are set to the first potential or the second potential state while maintaining all of the plurality of gate electrodes at the ON potential state for a predetermined third time, and then the predetermined TFT-OFF Only for the preceding time, all of the plurality of gate electrodes are kept in the state of the first potential or the second potential while keeping all of the plurality of gate electrodes in the OFF potential state, and then all of the plurality of gate electrodes are turned on. 6. The method according to claim 3, further comprising a TFT-OFF preceding step in which all of the plurality of source electrodes are switched to the GND potential state while maintaining the OFF potential state. . The method according to claim 6, wherein the TFT-OFF lead time is 1 to 500 msec.

Images