JP2016009031A - 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 capable of preventing a malfunction from being caused by long-time standing or continuous driving.SOLUTION: The driving method includes: a display rewriting process of setting the potential of a common electrode at a third potential between a first potential and a second potential, and setting the potential of each display electrode at one of the first potential, second potential, and third potential on the basis of the information of the image to be displayed; and a reset process of alternately repeating a first reset step of setting the potential of the common electrode at the first potential and setting the potential of each display electrode at the second potential, and a second reset step of setting the potential of the common electrode at the second potential and setting the potential of each display electrode at the first potential.

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. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2008-176337) discloses a conventional example of such an electrophoretic display device. 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.

  The structure of one type of electrophoretic display device will be described in more detail. Between one substrate and the other substrate, a common electrode that covers a plurality of display areas and a display medium including an electrophoretic body are arranged. A display medium layer and a plurality of display electrodes corresponding to each of the plurality of display regions are provided in this order from one substrate side to the other substrate side, and are set to the potential of the common electrode and the GND potential. Each of the plurality of display areas has a display color of one of the first color and the second color according to the polarity of the voltage applied to the display electrode corresponding to the display area. (Viewing side) can be selectively displayed.

  Specifically, for example, when the display medium includes positively charged black electrophoretic particles and negatively charged white electrophoretic particles, when a positive voltage is applied to the display electrode, Electric force acts on the electrophoretic particles and the white electrophoretic particles, respectively, and the white electrophoretic particles move to the display electrode side, and the black electrophoretic particles move to the common electrode side. As a result, black is displayed on the common electrode side of the display area. On the other hand, when a negative voltage is applied to the display electrode, the white electrophoretic particles move to the common electrode side, and the black electrophoretic particles move to the display electrode side. Thereby, white is displayed on the common electrode side of the display area. When the potential of the display electrode is changed to the GND potential (that is, when the voltage application to the display electrode is stopped), the electric force acting on the black electrophoretic particles and the white electrophoretic particles disappears. Therefore, the black electrophoretic particles and the white electrophoretic particles are each stopped in place. As a result, the display color of the display area is maintained.

JP 2008-176337 A

  By the way, in the electrophoretic display device, when continuous driving is performed, there is a problem that afterimages are accumulated, the number of electrophoretic particles that are attracted to the electrode and cannot be separated from each other increases. In addition, if the display medium is left for a long time without performing the display rewriting operation, the fluidity of the display medium is lowered (that is, the viscosity is increased), so that the response speed is lowered.

  In order to solve such a problem, the display medium is agitated by alternately applying electric fields opposite to each other between the two substrates and forcibly reciprocating the electrophoretic particles. A reset method is conceivable in which the electrophoretic particles adhering to the electrode are peeled off by the pressure of the flowing display medium and the accumulation of afterimages is suppressed.

  However, this method has the following problems. That is, in order to improve the fluidity of the display medium, it is necessary to reciprocate the electrophoretic particles with a sufficient amplitude. However, when the same voltage as that at the time of display rewriting is used, the display rewriting time per reciprocating electrophoretic particles. It takes about twice as long as that, and a longer time is required by repeating the reciprocating movement.

  Paying attention to such problems, the present inventor conducted extensive research and found that resetting was performed using a voltage higher than that at the time of display rewriting. It has been found that the same effect can be obtained with a small number of reciprocations as compared with the case of performing it. In addition, even if the voltage is applied for a time shorter than the voltage application time at the time of display rewriting, the pressure of the flowing display medium is high, which is effective in suppressing the accumulation of afterimages, and shortening the reset process time. I found out that it was connected.

  On the other hand, in the reflective display device of the twist ball system, there is a problem that a malfunction due to aggregation of rotating particles is caused by being left for a long time or continuously driven.

  Paying attention to such problems, the present inventor has conducted extensive research, and by performing a reset using a higher voltage than during display rewriting, rotating particles are rotated with a strong electric field, causing malfunctions. I found out that it can be resolved.

  The present invention is based on such knowledge of the present inventor, and an object of the present invention is to provide a driving method of a reflective display device that can eliminate malfunctions caused by long-term standing or continuous driving. 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 reflective display device that performs a desired display when a predetermined electric field is applied between two substrates, wherein a common electrode that covers a plurality of display regions is provided between one substrate and the other substrate. The display medium layer on which the display medium is arranged and the plurality of display electrodes corresponding to each of the plurality of display areas are provided in this order from the one substrate side to the other substrate side. And each of the plurality of display areas is selected from a first color and a second color according to a polarity of a potential applied to a display electrode corresponding to the display area with respect to a potential applied to the common electrode. The display color of either can be displayed selectively In which the potential of the common electrode is set to a third potential that is between the first potential and the second potential, and the potential of each display electrode is set to the level of the image to be displayed. Based on the information, the display rewriting step of setting one of the first potential, the second potential, and the third potential, and setting the potential of the common electrode to the first potential, and setting the potential of each display electrode to A reset step of alternately repeating a first reset step for setting the second potential and a second reset step for setting the potential of the common electrode to the second potential and the potential of each display electrode to the first potential. And a method for driving the reflective display device.

  Preferably, the voltage application time length in the first reset step and the voltage application time length in the second reset step are each shorter than the voltage application time length in the display rewriting step.

  Preferably, the reset process is performed after the reflective display device is powered on.

  Preferably, the reset process is performed before each display rewrite timing. Alternatively, the reset process may be performed every time the display rewriting timing is repeated a predetermined number of times.

  Preferably, the reset process is performed every time a predetermined time length elapses.

  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, and is provided between one substrate and the other substrate, and the display medium layer on which the display medium is disposed A common electrode that is provided on the one substrate and covers a plurality of display areas; a plurality of display electrodes that are provided on the other substrate and that correspond to each of the plurality of display areas; and A voltage application control unit that applies a voltage to each of the plurality of display regions, wherein each of the plurality of display regions corresponds to a polarity of a potential applied to the display electrode corresponding to the display region with respect to a potential applied to the common electrode The first color and the second color Any one of the display colors can be selectively displayed, and the voltage application control unit sets the potential of the common electrode to a third potential that is between the first potential and the second potential. A display rewriting step of setting the potential of the common electrode to any one of the first potential, the second potential, and the third potential based on information of an image to be displayed, and the potential of the common electrode as the first potential. A first reset step of setting the potential of each display electrode to the second potential; a second reset step of setting the potential of the common electrode to the second potential and setting the potential of each display electrode to the first potential; The reflective display device is characterized in that it is configured to perform a reset step of alternately repeating and.

  Preferably, the voltage application time length in the first reset step and the voltage application time length in the second reset step are each shorter than the voltage application time length in the display rewriting step.

  Preferably, the voltage application control unit is configured to perform the reset process after the reflective display device is powered on.

  Preferably, the voltage application control unit is configured to perform the reset process before each display rewriting process. Alternatively, the voltage application control unit may be configured to perform the reset process every time the display rewriting process is repeated a predetermined number of times.

  Preferably, the voltage application control unit is configured to perform the reset process every time a predetermined time length elapses.

  According to the present invention, in a reflective display device, it is possible to eliminate malfunctions caused by long-term standing or continuous driving.

FIG. 1 is a plan view schematically showing a reflective display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of the reflective display device shown in FIG. FIG. 3 is a diagram for explaining a driving method of the reflective display device shown in FIG. FIG. 4 is a diagram for explaining a driving method of the reflective display device shown in FIG. FIG. 5 is a diagram for explaining a driving method of the reflective display device shown in FIG. FIG. 6 is a schematic diagram illustrating an example of a waveform of a voltage applied to the common electrode and each display electrode in the reset process. FIG. 7 is a schematic diagram illustrating another example of a waveform of a voltage applied to the common electrode and each display electrode in the reset process.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view schematically showing a reflective display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of the reflective display device shown in FIG.

  As shown in FIG. 1 and FIG. 2, the reflective display device 10 according to the present embodiment includes two opposing sheets, at least one of which is translucent and each has electrodes 12 or 15a to 15h. A display medium 13 containing at least one kind of electrically responsive material is sealed between the substrates 11 and 16 so that a desired display is performed when a predetermined electric field is applied between the two substrates 11 and 16. It has become. Here, in the specification and claims of the present application, “translucent” means a property of transmitting light. In this embodiment mode, the substrate disposed on the viewing side has a light-transmitting property such that the total light transmittance is 50% or more, preferably 80% or more, and more preferably 90% or more.

  In the present embodiment, as shown in FIGS. 1 and 2, a plurality of (eight in the illustrated example) display areas 18 a to 18 h are covered between one substrate 11 and the other substrate 16. One or two or more (one in the illustrated example) common electrode 12, a display medium layer in which the display medium 13 is disposed, and a plurality (in the illustrated example) corresponding to each of the plurality of display regions 18a to 18h. 8) display electrodes 15a to 15h are provided in this order from one substrate 11 side to the other substrate 16 side. Here, the “display area” means an area used for a desired display in the reflective display device 10.

  In the present embodiment, as shown in FIG. 2, 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, and the common electrode 12 as A material with a translucent electrode such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO) is typically used. The common electrode 12 of the present embodiment is formed as a common electrode for segment driving.

  The common electrode 12 is formed so as to cover the plurality of display regions 18a to 18h of at least one substrate 11 by a coating method, a sputtering method, a vacuum deposition method, a CVD method, or the like. The common electrode 12 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.

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

  As the other substrate 16, a base material such as a resin film, a resin plate, glass, epoxy glass (glass epoxy) or the like is used, and a display electrode made of a conductive material such as metal on the surface of the base material on the display medium 13 side. What formed 15a-15h may be used. The display electrodes 15a to 15h of the present embodiment are formed as patterned electrodes (segment electrodes) for segment driving.

  More specifically, as shown in FIG. 1, the display electrodes 15a to 15h constitute a drive electrode of a so-called 7-segment display, and the first display electrode 15a that is horizontally long and downward from the left end of the first display electrode 15a. A vertically long second display electrode 15b, a vertically long third display electrode 15c extending downward from the right end of the first display electrode 15a, and a lower end of the second display electrode 15b and a lower end of the third display electrode 15c. A horizontally long fourth display electrode 15d extending left and right, a vertically long fifth display electrode 15e extending downward from the left end of the fourth display electrode 15d, and a vertically long sixth display electrode 15f extending downward from the right end of the fourth display electrode 15d. And the horizontally long seventh display electrode 15g extending left and right between the lower end of the fifth display electrode 15e and the lower end of the sixth display electrode 15f, and the outer sides of the first to seventh display electrodes 15a to 15f. It includes a eighth display electrodes 15h which kicked, the.

  The display areas 18a to 18h in the reflective display device 10 are defined by individual display electrodes 15a to 15h. In this specification, the display area 18a defined by the first display electrode 15a is defined by the first display area, and the display area 18b defined by the second display electrode 15b is defined by the second display area and the third display electrode 15c. The display area 18c to be displayed is the third display area, the display area 18d defined by the fourth display electrode 15d is the fourth display area, the display area 18e defined by the fifth display electrode 15e is the fifth display area, and the sixth display The display area 18f defined by the electrode 15f is the sixth display area, the display area 18g defined by the seventh display electrode 15g is the seventh display area, and the display area 18h defined by the eighth display electrode 15h is the eighth display area. , Sometimes called.

  For the other substrate 16, a base material having translucency may be used. 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, as shown in FIG. 2, the other substrate 16 is disposed at a position opposite to the viewing side, and thus does not necessarily have 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 increases. Because. A suitable thickness range that is difficult to break and easy to handle is about 50 μm to 300 μm.

The other substrate 16 can be applied in either a roll shape or a sheet shape.
The display medium layer according to the present embodiment includes a partition wall 14 that partitions a plurality of cells between one substrate 11 and the other substrate 16, and the display medium 13 is disposed in each cell. . Here, the “cell” refers to a minute electrophoretic body divided between the two substrates 11 and 16 in order to prevent poor display due to sedimentation or uneven distribution of the electrophoretic body, particularly a decrease in contrast. It means migration space, that is, movement space. In addition, the said movement space may be divided | segmented by other structures, such as a microcapsule. Further, when the risk of sedimentation or uneven distribution of the electrophoretic body is low, the space between the two substrates 11 and 16 may not be divided by such a structure.

  The partition wall 14 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 14, a mold transfer method such as embossing can be adopted in addition to a 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 14 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 14 is 5 μm to 50 μm, preferably 10 μm to 50 μm. If the thickness is 5 μm or less, the amount of ink to be filled is small, and sufficient display characteristics, in particular, contrast cannot be obtained. On the other hand, if the thickness is 50 μm or more, the panel is too thick and the drive voltage increases excessively. From the viewpoint of obtaining good display characteristics at a low driving voltage, a height in the range of 10 μm to 50 μm is preferable.

  Between the top surface of the partition wall 14 and the display electrodes 15 a to 15 h on the other substrate 16 or the other substrate 16, the top surface of the partition wall 14 and the display electrodes 15 a to 15 h on the other substrate 16 or the other substrate 16. An adhesive layer (not shown) for adhering the 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 the composition is reversible when cooling and heating are repeated. It is a material that is kept in a safe manner.

  Specific examples of the adhesive layer include thermoplastic base polymers such as ethylene-vinyl acetate copolymer, polyester, polyamide, polyolefin, and polyurethane, natural rubber, styrene-butadiene block copolymer, and styrene-isoprene block copolymer. Resins mainly composed of thermoplastic elastomers such as polymers, styrene-ethylene-butylene-styrene block copolymers, styrene-ethylene-propylene-styrene copolymers and blended with tackifier resins and plasticizers. Is done.

  In order to improve the adhesion between the partition wall 14 and the adhesive layer, the partition wall 14 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 layer.

  The display medium 13 includes at least one kind of electrically responsive material. Examples of electro-responsive materials include electrophoretic particles in which colored particles such as white, black, and color move in response to an electric field, or twist balls that are colored in two colors and rotated by the electric field. Rotating particles, or nanoparticle materials that move by an electric field are used.

  In the present embodiment, the display medium 13 includes a liquid dispersion medium, and white electrophoretic particles and black electrophoretic particles dispersed in the dispersion medium. The black electrophoretic particles are positively charged, and the white electrophoretic particles are negatively charged. As a result, when the potentials of the display electrodes 15a to 15h are made lower than the potential of the common electrode 12, the positively charged black electrophoretic particles migrate so as to be attracted to the display electrodes 15a to 15h in the dispersion medium. The negatively charged white electrophoretic particles migrate so as to be drawn toward the common electrode 12 in the dispersion medium. Further, when the potential of the display electrodes 15a to 15h is made higher than the potential of the common electrode 12, the positively charged black electrophoretic particles migrate so as to be attracted to the common electrode 12 side in the dispersion medium, and become negative. The charged white electrophoretic particles migrate so as to be drawn through the dispersion medium toward the display electrodes 15a to 15h. Then, by controlling the migration of the white electrophoretic particles and the black electrophoretic particles, in each of the display regions 18a to 18h, one of the display colors of white and black is changed to the common electrode 12 side (that is, , The viewing side) can be selectively displayed.

  In the present embodiment, as shown in FIGS. 1 and 2, the display medium 13 is surrounded by an outer peripheral seal 17. In the illustrated example, the reflective display device 10 has a rectangular shape, and the outer peripheral seal 17 is disposed in a rectangular shape correspondingly.

  The outer peripheral seal 17 is formed by applying an adhesive such as an ultraviolet curable resin on one substrate 11 or the other substrate 16 in a rectangular shape using a dispenser, and then being cured by ultraviolet rays. Is formed. In addition to the ultraviolet curable resin, it can be constituted by a thermosetting resin, a room temperature curable resin, a heat seal resin, or the like. In addition to the dispenser, the outer peripheral seal 17 can be arranged by various printing methods or by thermocompression bonding.

  As shown in FIG. 1, the reflective display device 10 further includes a voltage application control unit 19 that applies a voltage to each of the display electrodes 15a to 15h.

  The voltage application control unit 19 is electrically connected to the common electrode 12 and the display electrodes 15a to 15h, and individually sets the potential of the common electrode 12 and the potential of the display electrodes 15a to 15h to at least a first potential (for example, 0 V), a second potential (eg, +30 V), and a third potential (eg, +15 V) that is between the first potential and the second potential. In other words, the voltage application control unit 19 individually sets the potential of the common electrode 12 and the potentials of the display electrodes 15a to 15h individually to at least a third potential (that is, + 15V) and a negative polarity with respect to the third potential. It is possible to selectively select a potential (that is, 0V) and a second potential (that is, + 30V) having a positive polarity with respect to the third potential. Note that the third potential is not limited to the exact middle between the first potential and the second potential as long as it is between the first potential and the second potential, and is closer to the first potential than the second potential. Alternatively, it may be closer to the second potential than the first potential.

  In the present embodiment, the voltage application control unit 19 sets the potential of the common electrode 12 to the third potential (that is, +15 V) at the display rewrite timing, and sets the potentials of the display electrodes 15a to 15h to information on the image to be displayed. Based on the above, the display rewriting process is performed such that one of the first potential (that is, 0 V), the second potential (that is, +30 V), and the third potential (that is, +15 V) is set.

  Specifically, for example, for the display region (for example, the first display region 18a) whose display color should be switched from black to white at the display rewrite timing, the voltage application control unit 19 sets the potential of the common electrode 12 to the third potential. (Ie, + 15V), and the potential of the first display electrode 15a is set to the first potential (ie, 0V) for a predetermined writing time length (eg, 300 ms to 400 ms). As a result, the polarity of the potential of the first display electrode 15a with respect to the potential of the common electrode 12 becomes negative, and the negatively charged white electrophoretic particles are adsorbed to the common electrode 12, and the positively charged black electrophoretic particles Is adsorbed by the first display electrode 15a, and as a result, white is displayed on the common electrode 12 side (viewing side) of the first display region 18a. Thereafter, the voltage application control unit 19 sets the potential of the first display electrode 15a to the third potential (that is, + 15V). Thereby, the electric potential of the common electrode 12 and the electric potential of the first display electrode 15a become the same electric potential, and the black electrophoretic particles and the white electrophoretic particles are stopped in place, and as a result, the first display region 18a. The white display color is maintained as it is.

  In the display rewrite timing, for the display region (for example, the second display region 18b) whose display color should be switched from white to black, the voltage application control unit 19 changes the potential of the common electrode 12 to the third potential (that is, + 15V). In addition, the potential of the second display electrode 15b is set to the second potential (that is, +30 V) for a predetermined writing time length (for example, 300 ms to 400 ms). As a result, the polarity of the potential of the second display electrode 15b with respect to the potential of the common electrode 12 becomes positive, and the positively charged black electrophoretic particles are adsorbed to the common electrode 12, and the negatively charged white electrophoretic particles are absorbed. Is adsorbed by the second display electrode 15b, and as a result, black is displayed on the common electrode 12 side (viewing side) of the second display region 18b. Thereafter, the voltage application control unit 19 sets the potential of the second display electrode 15b to the third potential (that is, + 15V). As a result, the potential of the common electrode 12 and the potential of the second display electrode 15b become the same potential, and the black electrophoretic particles and the white electrophoretic particles are stopped in place, and as a result, the second display region 18b. The white display color is maintained as it is.

  For the display area (for example, the third display area 18c) in which the display color should be maintained as it is at the display rewrite timing, the voltage application control unit 19 sets the potential of the common electrode 12 to the third potential (that is, + 15V). The potential of the third display electrode 15c is also set to the third potential (that is, + 15V). Since the potential of the common electrode 12 and the potential of the third display electrode 15c are set to the same potential (that is, + 15V), the black electrophoretic particles and the white electrophoretic particles are stopped in place, and as a result, The display color of the third display area 18c is maintained as it is.

  In the present specification, the “display rewriting timing” means a timing at which a desired display image is displayed again to the observer on the reflective display device 10, for example, a predetermined cycle such as a digital display clock. For example, the timing may be repeated in 1 s, or may be manually given irregularly like a calculator.

  In addition, when the voltage application control unit 19 applies the voltage of the magnitude V for the time length T, the voltage application control unit 19 may apply the voltage of the magnitude V continuously for the time length T. In this case, a pulse voltage having a time length (pulse width) W may be repeatedly applied T / W times.

  Further, the voltage application control unit 19 is common with the first reset step S1 in which the potential of the common electrode 12 is set to the first potential (that is, 0V) and the potentials of the display electrodes 15a to 15h are set to the second potential (that is, + 30V). A reset process is performed in which the second reset step S2 in which the potential of the electrode 12 is set to the second potential (ie, +30 V) and the potential of the display electrodes 15a to 15h is set to the first potential (ie, 0 V) is alternately repeated. It is configured.

  FIG. 6 is a schematic diagram illustrating an example of a waveform of a voltage applied to the common electrode 12 and the display electrodes 15a to 15h in the reset process.

  As shown in FIG. 6, the voltage application control unit 19 sets the potential of the common electrode 12 to the first potential (that is, 0 V) and sets the potentials of the display electrodes 15a to 15h to the second potential as the first reset step S1. (That is, + 30V). As a result, the polarity of the potentials of the display electrodes 15a to 15h with respect to the potential of the common electrode 12 becomes positive, and the positively charged black electrophoretic particles move to the common electrode 12 side and the negatively charged white electrophoretic particles. The particles move to the second display electrode 15b side. Here, since the potential difference between the common electrode 12 and each of the display electrodes 15a to 15h is about twice the potential difference at the time of display rewriting, each electrophoretic particle has an electric force of 2 acting upon display rewriting. Electric force twice as large acts. Therefore, each electrophoretic particle moves between the common electrode 12 and each display electrode 15a-15h at a movement speed faster than the movement speed at the time of display rewriting. Therefore, the voltage application time length in the first reset step S1 can be shorter than the write time length, for example, 30 ms.

  In addition, as the second reset step S2, the voltage application control unit 19 sets the potential of the common electrode 12 to the second potential (ie, + 30V) and sets the potentials of the display electrodes 15a to 15h to the first potential (ie, 0V). It is supposed to be. As a result, the polarity of the potentials of the display electrodes 15a to 15h with respect to the potential of the common electrode 12 becomes negative, and the negatively charged white electrophoretic particles move to the common electrode 12 side, and the positively charged black electrophoretic particles. The particles move to the second display electrode 15b side. Again, since the potential difference between the common electrode 12 and each of the display electrodes 15a to 15h is about twice the potential difference at the time of display rewriting, each electrophoretic particle has an electric force of 2 acting upon display rewriting. Electric force twice as large acts. Therefore, each electrophoretic particle moves between the common electrode 12 and each display electrode 15a-15h at a movement speed faster than the movement speed at the time of display rewriting. Therefore, the voltage application time length in the second reset step S2 can also be shorter than the write time length, for example, 30 ms.

  As shown in FIG. 6, the voltage application control unit 19 uses a set of one first reset step S1 and one second reset step S2 as a unit reset cycle, and sets the unit reset cycle (S1 + S2) as a predetermined value. The number of times, for example, 30 times is repeated. By repeating the unit reset cycle (S1 + S2) a predetermined number of times, the electrophoretic particles are forcibly reciprocated a predetermined number of times between the common electrode 12 and the display electrodes 15a to 15h. The fluidity of the display medium 13 can be increased by being stirred, that is, the viscosity of the display medium 13 can be reduced. Further, the electrophoretic particles attached to the common electrode 12 and / or the display electrodes 15a to 15h are peeled off by the pressure of the flowing display medium 13, and accumulation of afterimages can be suppressed.

  In the present embodiment, the voltage application control unit 19 is configured to perform a reset process after the reflective display device 10 is powered on.

  Further, in the present embodiment, the voltage application control unit 19 is configured to perform the reset process before each display rewriting process.

  Next, an example of a method for driving the reflective display device 10 having such a configuration will be described with reference to FIGS.

  As shown in FIG. 3, in the initial state, an initial image representing the number “3” is displayed on the common electrode 12 side (viewing side) of the reflective display device 10. That is, the first display area 18a, the third display area 18c, the fourth display area 18d, the sixth display area 18f, and the seventh display area 18g are displayed in black, and the second display area 18b and the fifth display area are displayed. White is displayed in the area 18e and the eighth display area 18h. In the initial state, the power source of the reflective display device 10 is turned off, and the potentials of the common electrode 12 and the display electrodes 15a to 15h are set to the GND potential (0 V) due to free discharge.

  First, as shown in FIG. 3, the process of rewriting the display from the initial image representing the number “3” to the first image representing the number “2” after the reflective display device 10 is turned on will be described. .

In this case, the voltage application control unit 19 performs a reset process, preferably in conjunction with the power-on after the reflective display device 10 is powered on. That is, the first reset step S1 in which the potential of the common electrode 12 is set to the first potential (that is, 0V) and the potentials of the display electrodes 15a to 15h are set to the second potential (that is, + 30V); The second reset step S2 in which the potential (that is, + 30V) is set and the potential of each display electrode 15a to 15h is set to the first potential (that is, 0V) is alternately repeated. Specifically, for example, a set of one first reset step S1 and one second reset step S2 is set as a unit reset cycle, and the unit reset cycle (S1 + S2) is repeated N _ini = 30 times. The voltage application time length in the first reset step S1 is, for example, 30 ms, and the voltage application time length in the second reset step S2 is, for example, 30 ms.

  In the first reset step S1, the polarity of the potentials of the display electrodes 15a to 15h with respect to the potential of the common electrode 12 becomes positive, and the positively charged black electrophoretic particles move to the common electrode 12 side and are negatively charged. White electrophoretic particles move to the display electrodes 15a to 15h, and black is displayed in the display regions 18a to 18h.

  Further, in the second reset step S2, the polarity of the potentials of the display electrodes 15a to 15h with respect to the potential of the common electrode 12 becomes negative, and the negatively charged white electrophoretic particles move to the common electrode 12 side. The charged black electrophoretic particles move to the display electrodes 15a to 15h, and white is displayed in the display regions 18a to 18h.

  The first reset step S1 and the second reset step S2 are alternately repeated, so that the electrophoretic particles are forcibly reciprocated between the common electrode 12 and the display electrodes 15a to 15h. The display medium 13 is agitated to improve the fluidity of the display medium 13, that is, the viscosity of the display medium 13 is reduced.

  Further, the potential difference between the common electrode 12 and the display electrodes 15a to 15h in the first reset step S1 and the second reset step S2 is about twice the potential difference at the time of display rewriting. An electric force that is about twice as large as an electric force acting at the time of display rewriting acts, and each electrophoretic particle is placed between the common electrode 12 and each of the display electrodes 15a to 15h at the time of display rewriting. It moves at a movement speed faster than the movement speed. Therefore, the fluidity of the display medium 13 can be improved in a relatively short time compared to the case where the same voltage as that used for display rewriting is used.

  In the present embodiment, the reset process ends in the second reset step S2, and white is displayed in each of the display areas 18a to 18h immediately after the reset process.

  Next, the voltage application control unit 19 sets the potential of the common electrode 12, the potential of the second display electrode 15b, the potential of the sixth display electrode 15f, and the potential of the eighth display electrode 15h to the third potential (that is, + 15V). The potential of the first display electrode 15a, the potential of the third display electrode 15c, the potential of the fourth display electrode 15d, the potential of the fifth display electrode 15e, and the potential of the seventh display electrode 15g are the second potential (ie, + 30V). For a predetermined writing time length (for example, 300 ms to 400 ms), and then set to the third potential (that is, +15 V). As a result, the display colors of the second display area 18b, the sixth display area 18f, and the eighth display area 18h are kept white. On the other hand, the display colors of the first display area 18a, the third display area 18c, the fourth display area 18d, the fifth display area 18e, and the seventh display area 18g are switched from white to black. Accordingly, the first image representing the number “2” is displayed on the common electrode 12 side (viewing side) of the reflective display device 10.

  In the present embodiment, since the fluidity of the display medium 13 is improved by performing the reset process after the reflective display device 10 is turned on, the response speed when displaying the first image can be improved. .

  Next, as shown in FIG. 4, the process of rewriting the display from the first image representing the number “2” to the second image representing the number “6” will be described.

In this case, the voltage application control unit 19 performs a reset process before the display rewriting process. That is, the first reset step S1 in which the potential of the common electrode 12 is set to the first potential (that is, 0V) and the potentials of the display electrodes 15a to 15h are set to the second potential (that is, + 30V); The second reset step S2 in which the potential (that is, + 30V) is set and the potential of each of the display electrodes 15a to 15h is set to the first potential (that is, 0V) is alternately repeated. Specifically, for example, a set of one first reset step S1 and one second reset step S2 is set as a unit reset cycle, and the unit reset cycle (S1 + S2) is repeated N _reset = 30 times. The voltage application time length in the first reset step S1 is, for example, 30 ms, and the voltage application time length in the second reset step S2 is, for example, 30 ms.

  As described above, the first reset step S1 and the second reset step S2 are alternately repeated, so that the electrophoretic particles are forcibly reciprocated between the common electrode 12 and the display electrodes 15a to 15h. Thus, the display medium 13 is agitated. Furthermore, the electrophoretic particles adhering to the common electrode 12 or the display electrodes 15a to 15h are peeled off by the pressure of the flowing display medium 13, and the afterimage of the first image is reduced.

  Further, as described above, the potential difference between the common electrode 12 and the display electrodes 15a to 15h in the first reset step S1 and the second reset step 2 is about twice the potential difference at the time of display rewriting. The electrophoretic particles are subjected to an electric force that is about twice as large as the electric force that is applied during display rewriting, and each electrophoretic particle passes between the common electrode 12 and the display electrodes 15a to 15h. Move at a faster movement speed than the display rewriting speed. Therefore, it is possible to suppress the accumulation of afterimages in a relatively short time as compared with the case where the same voltage as that used for display rewriting is used.

  In the present embodiment, the reset process ends in the second reset step S2, and white is displayed in each of the display areas 18a to 18h immediately after the reset process.

  Next, the voltage application control unit 19 sets the potential of the common electrode 12, the potential of the third display electrode 15c, and the potential of the eighth display electrode 15h to the third potential (that is, + 15V), and the potential of the first display electrode 15a. The potential of the second display electrode 15b, the potential of the fourth display electrode 15d, the potential of the fifth display electrode 15e, the potential of the sixth display electrode 15f, and the potential of the seventh display electrode 15g are set to the second potential (ie, +30 V). Only a predetermined writing time length (for example, 300 ms to 400 ms) is set, and then the third potential (ie, +15 V) is set. Thereby, the display colors of the third display area 18c and the eighth display area 18h are kept white. On the other hand, the display colors of the first display area 18a, the second display area 18b, the fourth display area 18d, the fifth display area 18e, the sixth display area 18f, and the seventh display area 18g are switched from white to black. As a result, a second image representing the number “6” is obtained on the common electrode 12 side (viewing side) of the reflective display device 10.

  In this embodiment, since the reset process is performed before the display rewriting process, the afterimage of the first image is prevented from being accumulated before the second image is displayed, so that the display contrast of the second image is improved. Can be done.

  As described above, according to the present embodiment, the first reset step S1 and the second reset step S2 are repeated in the reset process, so that electrophoresis is performed between the common electrode 12 and the display electrodes 15a to 15h. The particles are forcibly reciprocated, so that the fluidity of the display medium 13 can be enhanced and the accumulation of afterimages can be suppressed. Here, in the first reset step S1 and the second reset step S2, a voltage about twice as large as the applied voltage at the time of writing is applied between the common electrode 12 and the display electrodes 15a to 15h. The moving speed of the electrophoretic particles is faster than the moving speed at the time of writing, and the time required for one reciprocation of the electrophoretic particles is shortened. Therefore, it is possible to improve the fluidity of the display medium 13 and suppress the accumulation of afterimages in a relatively short time as compared with the case of using the same voltage as that at the time of writing. In other words, according to the present embodiment, it is possible to eliminate a malfunction due to long-term standing or continuous driving.

  Also, normally, before the reflective display device 10 is turned on, the display state is not rewritten for a long time and left unattended, and the fluidity of the display medium 13 is reduced, so the response speed is slowed down. However, according to the present embodiment, the reset process is performed after the reflective display device 10 is turned on, so that the fluidity of the display medium 13 is enhanced, and as a result, the response speed can be improved.

  In addition, according to the present embodiment, since the reset process is performed before each display rewriting process, the accumulation of afterimages can be suppressed, and thereby the contrast of the display image can be improved.

In the present embodiment, the unit reset cycle repetition number N _reset in the reset step before each display rewriting step is equal to the unit reset cycle repetition number N _ini in the reset step after power-on of the reflective display device 10. Although it was the same, it is not limited to this, You may differ.

  In the present embodiment, the voltage application control unit 19 is configured to perform the reset process before each display rewriting process. However, the present invention is not limited to this, and the display rewriting process is performed a predetermined number of times, for example, 100. You may comprise so that a reset process may be performed every time it repeats. In this case, the display rewriting time interval can be shortened as compared with the present embodiment in which the resetting process is performed before each display rewriting process.

  In the present embodiment, as shown in FIG. 6, the reset process starts from the first reset step S1 and ends at the second reset step S2. However, the present invention is not limited to this. For example, As shown in FIG. 7, the reset process may be started from the second reset step S2, and may be ended at the first reset step S1. Alternatively, the reset process may start from the first reset step S1 and end at the first reset step S1, or the reset process starts from the second reset step S2 and ends at the second reset step S2. You may come to do. Even in these cases, the same effect as the present embodiment can be obtained.

  Moreover, the voltage application control part 19 may be comprised so that a reset process may be performed whenever predetermined time length, for example, 10 hours, passes. In other words, the voltage application control unit 19 may be configured to repeat the reset process at a predetermined time period, for example, 10 hours. For example, if the display state is rewritten for a long time, for example, for 10 hours or longer, the response speed is reduced due to a decrease in the fluidity of the display medium 13, but a predetermined time length, for example, 10 hours. Since the reset process is automatically performed every time elapses, the response speed can be prevented from slowing down.

  In this embodiment, electrophoretic particles are included in the display medium 13 as an electroresponsive material. However, the present invention is not limited to this. For example, the display medium 13 is represented by a twist ball as an electroresponsive material. Rotating particles may be included (second embodiment). In the reflective display device of the twist ball system, a malfunction due to aggregation of rotating particles is caused by being left for a long time or continuously driven. In other words, in the reflective display device of the twist ball method, the rotating particles are aggregated by being left for a long time or continuously driven, but once the aggregation occurs, the tendency to maintain the stable state works, so the response speed becomes slow. To do. However, according to the second embodiment, in the reset process, the first reset step S1 and the second reset step S2 are repeated, and in each reset process, between the common electrode 12 and each of the display electrodes 15a to 15h. By applying a voltage about twice as large as the applied voltage at the time of writing, the rotating particles try to maintain a stable state by a strong electric field between the common electrode 12 and the display electrodes 15a to 15h. It is forcibly rotated against the tendency, and as a result, aggregation of the rotating particles can be eliminated. Therefore, it is possible to eliminate malfunction caused by long-term standing or continuous driving, that is, slowing down of the response speed.

DESCRIPTION OF SYMBOLS 10 Reflective type display apparatus 11 One board | substrate 12 Common electrode 13 Display medium 14 Partition 15a-15h Display electrode 16 The other board | substrate 17 Perimeter seals 18a-18h Display area 19 Voltage application control part

Claims (12)

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,
Between one substrate and the other substrate, a common electrode covering a plurality of display areas, a display medium layer in which the display medium is disposed, and a plurality of display electrodes corresponding to each of the plurality of display areas, Are provided in this order from the one substrate side to the other substrate side,
Each of the plurality of display areas is one of a first color and a second color according to a polarity of a potential applied to a display electrode corresponding to the display area with respect to a potential applied to the common electrode. A reflective display device that can selectively display the display color of
The potential of the common electrode is set to a third potential that is between the first potential and the second potential, and the potential of each display electrode is set based on the information of the image to be displayed. And a display rewriting step of making any one of the third potentials,
A first reset step in which the potential of the common electrode is set to the first potential and the potential of each display electrode is set to the second potential; the potential of the common electrode is set to the second potential; and the potential of each display electrode is set to the first potential A reset step of alternately repeating a second reset step of setting one potential;
A method for driving a reflective display device, comprising: 2. The reflective type according to claim 1, wherein the voltage application time length in the first reset step and the voltage application time length in the second reset step are shorter than the voltage application time length in the display rewriting step, respectively. A driving method of a display device. The method of driving a reflective display device according to claim 1, wherein the resetting step is performed after powering on the reflective display device. 4. The method of driving a reflective display device according to claim 1, wherein the resetting step is performed before each display rewriting step. 4. The method of driving a reflective display device according to claim 1, wherein the reset process is performed every time the display rewriting process is repeated a predetermined number of times. 6. The method of driving a reflective display device according to claim 1, wherein the reset process is performed every time a predetermined time length elapses. 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 display medium layer provided between one substrate and the other substrate on which the display medium is disposed;
A common electrode provided on the one substrate and covering a plurality of display areas;
A plurality of display electrodes provided on the other substrate and corresponding to each of the plurality of display regions;
A voltage application controller for applying a voltage to each display electrode;
With
Each of the plurality of display areas is one of a first color and a second color according to a polarity of a potential applied to a display electrode corresponding to the display area with respect to a potential applied to the common electrode. Can be displayed selectively,
The voltage application controller is
The potential of the common electrode is set to a third potential that is between the first potential and the second potential, and the potential of each display electrode is set based on the information of the image to be displayed. And a display rewriting step of making any one of the third potentials,
A first reset step in which the potential of the common electrode is set to the first potential and the potential of each display electrode is set to the second potential; the potential of the common electrode is set to the second potential; and the potential of each display electrode is set to the first potential A reset step of alternately repeating a second reset step of setting one potential;
A reflection type display device configured to perform 8. The reflective type according to claim 7, wherein the voltage application time length in the first reset step and the voltage application time length in the second reset step are shorter than the voltage application time length in the display rewriting step, respectively. Display device. The reflective display device according to claim 7, wherein the voltage application control unit is configured to perform the reset process after the reflective display device is powered on. The reflective display device according to claim 7, wherein the voltage application control unit is configured to perform the reset process before each display rewriting process. 10. The reflective display device according to claim 7, wherein the voltage application control unit is configured to perform the reset process every time the display rewriting process is repeated a predetermined number of times. . The reflective display device according to claim 7, wherein the voltage application control unit is configured to perform the reset process every time a predetermined time length elapses.

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