JP2015169902A - Method for driving reflection-type display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for driving a reflection-type display that can suppress the decrease of life of an electronic circuit and the increase of power consumption and also suppress the degradation of a display color in each display area.SOLUTION: To a display electrode corresponding to a display area where a display color is switched from a second color to a first color, is connected a first electric potential for a first time length, and then a second electric potential. To a display electrode corresponding to a display area where a display color is switched from the first color to the second color, is connected a third electric potential, which has polarity reverse to that of the first electric potential relative to the second electric potential for a second time length, and then the second electric potential. To a display electrode corresponding to a display area where the first color is maintained as the display color, is connected the electric potential for 5% to 30% of the first time length, and then the second electric potential. To a display electrode corresponding to a display area where the second color is maintained as the display color, is connected the third electric potential for 5% to 30% of the second time length, and then the second electric 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. 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, one or two or more common electrodes that cover a plurality of display regions, and electrical responsiveness A display medium layer in which a display medium containing a material is disposed, 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. One or two or more common electrodes are connected to GND, and each of the plurality of display regions has a polarity depending on the polarity of the voltage applied to the display electrode corresponding to the display region. Either one of the first color and the second color can be selectively displayed on the common electrode side (viewing side).

  Specifically, for example, when a positively charged black electroresponsive material and a negatively charged white electroresponsive material are included in the display medium, when a positive voltage is applied to the display electrode, Electric force acts on the black electroresponsive material and the white electroresponsive material, respectively, and the white electroresponsive material moves to the display electrode side, and the black electroresponsive material is on the common electrode side. Move to. As a result, black is displayed on the common electrode side of the display region. On the other hand, when a negative voltage is applied to the display electrode, the white electroresponsive material moves to the common electrode side and the black electroresponsive material moves to the display electrode side. Thereby, white is displayed on the common electrode side of the display region. When GND is connected to the display electrode (that is, when voltage application to the display electrode is stopped), the electric force acting on the black electroresponsive material and the white electroresponsive material respectively. Disappears so that the black electro-responsive material and the white electro-responsive material each rest in place. Thereby, the display color of the display area is maintained.

  By the way, each display region of the electrophoretic display device can maintain its display color for a certain period of time as described above even when the voltage application to the display electrode is stopped. Cannot be maintained permanently. In the above example, when the voltage application to the display electrode is stopped, the black electroresponsive material (or white electroresponsive material) located on the common electrode side is moved to the display electrode side due to the influence of gravity or the like. The display color on the common electrode side deteriorates with time (grayish).

  In Japanese Patent Application Laid-Open No. 2007-206471 (Patent Document 1), in an electrophoretic display device, a voltage is applied to a display electrode corresponding to a display region whose display color should be changed, but the display color is maintained as it is. A method is disclosed in which no voltage is applied to the display electrode corresponding to the display region to be displayed. However, with this method, it is not possible to suppress display color deterioration in the display area where the display color should be maintained as it is.

JP 2007-206471 A

  The present inventor initially applied a voltage to the display electrode corresponding to the display region that should retain the display color as well as the display electrode corresponding to the display region whose display color should be switched at the same time length. It was considered that the application can suppress deterioration of the display color of each display area. However, in this method, an excessive voltage is applied to the display area where the display color should be kept as it is, so that there is a problem that the life of the electronic circuit is reduced and the power consumption is increased.

  The present invention has been made paying attention to such problems, and its purpose is to suppress deterioration of display color in each display area while suppressing a decrease in the lifetime of the electronic circuit and an increase in power consumption. Another object of the present invention is to provide a method for driving a reflective display device. 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, one covering a plurality of display regions between one substrate and the other substrate Alternatively, two or more common electrodes, a display medium layer on which the display medium is disposed, and a plurality of display electrodes corresponding to each of the plurality of display areas are provided from the one substrate side to the other substrate. The one or more common electrodes are connected to a second potential, and each of the plurality of display areas corresponds to the display area. Depending on the polarity of the voltage applied to the display electrode, the first color and A method of driving a reflective display device that can selectively display either one of the second colors, corresponding to a display area for switching the display color from the second color to the first color A display region for switching a display color from a first color to a second color by connecting a first potential different from the second potential to the display electrode for a first time length, and then connecting the second potential. The display electrode corresponding to is connected to the third potential having the opposite polarity to the second potential for the second time length, and then connected to the second potential, The display electrode corresponding to the display region that retains the display color is connected to the first potential for a time length of 5% to 30% of the first time length, and then the second potential is connected. The display electrode corresponding to the display area that retains the display color of the second color as it is is provided on the display electrode Connect the potential for a time length of from 5% to 30% of the second time length, then the driving method of the reflective display device, characterized by connecting said second potential.

  According to the present invention, 5% to 30% of the time length of voltage application required for switching from another display color to the display color corresponding to the display region that should keep the display color as it is. By applying the voltage for the length of time, it is possible to suppress deterioration of the display color in each display region while suppressing a decrease in the lifetime of the electronic circuit and an increase in power consumption.

  Preferably, at the display color rewriting timing, the first potential is connected to the display electrode corresponding to the display region for switching the display color from the second color to the first color all at once, for the first time length, Thereafter, the second potential is connected, and the third potential is connected to the display electrode corresponding to the display region for switching the display color from the first color to the second color for the second time length. The first potential is connected for a time length of 5% to 30% of the first time length to a display electrode corresponding to a display region that connects two potentials and maintains the display color of the first color as it is. Then, the third potential is applied to the display electrode corresponding to the display region that holds the second display color as it is after the second potential is connected, for a period of 5% to 30% of the second time length. Connect only the length, and then connect the second potential. According to such an aspect, at the display rewriting timing, the original display color can be displayed simultaneously in each display area. Thereby, the overall deterioration of the display state (display image) in the reflective display device can be effectively suppressed.

  However, the voltage application may be performed by providing a time difference for each display region.

  Preferably, the first potential is connected to a display electrode corresponding to a display region that maintains the display color of the first color as it is for a time length of 5% to 30% of the first time length, Thereafter, the third potential is applied to the display electrode corresponding to the display region that is connected to the second potential and retains the second display color as it is for a time length of 5% to 30% of the second time length. The voltage application of connecting only the second potential and then connecting the second potential is repeated at a predetermined cycle until the next display rewriting timing. According to such an aspect, the overall deterioration of the display state (display image) in the reflective display device can be effectively suppressed until the next display rewrite timing. Specifically, for example, the predetermined period is 30 min to 180 min.

  Preferably, the first potential is connected to a display electrode corresponding to a display region that holds the display color of the first color as it is for a time length of 5% to 20% of the first time length, Thereafter, the third potential is applied to the display electrode corresponding to the display region that is connected to the second potential and retains the second display color as it is for a time length of 5% to 20% of the second time length. And then the second potential is connected.

  According to such an aspect, although about 1% of the display area in which the deterioration of the display color cannot be suppressed occurs, it is possible to further suppress the decrease in the lifetime of the electronic circuit and the increase in the power consumption by about 10%.

  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 And one or more common electrodes provided on the display medium side surface of the one substrate, covering a plurality of display areas, and provided on the display medium side surface of the other substrate, A plurality of display electrodes corresponding to each of the plurality of display regions; and a voltage application control unit that applies a voltage to each of the display electrodes, and the one or more common electrodes include a first electrode The plurality of display areas connected to two potentials Each of the display colors can selectively display 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 region. The application control unit connects a first potential different from the second potential to the display electrode corresponding to the display region for switching the display color from the second color to the first color for a first time length, and then A third potential having a polarity opposite to the first potential with respect to the second potential is applied to the display electrode corresponding to the display region to which the second potential is connected and the display color is switched from the first color to the second color. Is connected for the second time length, and then the second potential is connected, and the first potential is applied to the display electrode corresponding to the display region that retains the display color of the first color as it is. Of 5% to 30% of the time, and then the second potential is connected. The third potential is connected to the display electrode corresponding to the display region that keeps the color as it is for 5 to 30% of the second time length, and then the second potential is connected. It is a reflection type display device characterized by being formed.

  According to the present invention, 5% to 30% of the time length of voltage application required for switching from another display color to the display color corresponding to the display region that should keep the display color as it is. By applying the voltage for the length of time, it is possible to suppress deterioration of the display color in each display region while suppressing a decrease in the lifetime of the electronic circuit and an increase in power consumption.

  Preferably, the voltage application control unit applies the first potential to the display electrode corresponding to the display region for switching the display color from the second color to the first color at the same time at the display rewrite timing. The third potential is applied to the display electrode corresponding to the display region that is connected for a time length and then the second potential is connected and the display color is switched from the first color to the second color for the second time length. Then, the second potential is connected, and the first potential is applied to the display electrode corresponding to the display region that retains the first display color as it is, from 5% to 30% of the first time length. The third potential is applied to the display electrode corresponding to the display region for connecting the second potential and then maintaining the second display color as it is. Connect for the time length of 30% to 30%, then connect the second potential It has become to so that. According to such an aspect, at the display rewriting timing, the original display color can be displayed simultaneously in each display area. Thereby, the overall deterioration of the display state (display image) in the reflective display device can be effectively suppressed.

  However, the voltage application control unit may implement the voltage application by providing a time difference for each display region.

  Preferably, the voltage application control unit applies the first potential to 5% to 30% of the first time length for a display electrode corresponding to a display region that retains the first display color as it is. The third potential is applied to the display electrode corresponding to the display region for connecting the second potential and then maintaining the second display color as it is. The voltage application of connecting for the time length of% to 30% and then connecting the second potential is repeated at a predetermined cycle until the next display rewrite timing. According to such an aspect, the overall deterioration of the display state (display image) in the reflective display device can be effectively suppressed until the next display rewrite timing. Specifically, for example, the predetermined period is 30 min to 180 min.

  Preferably, the voltage application control unit applies the first potential to 5% to 20% of the first time length for a display electrode corresponding to a display region that holds the display color of the first color as it is. The third potential is applied to the display electrode corresponding to the display region for connecting the second potential and then maintaining the second display color as it is. It is applied for a time length of% to 20%, and then the second potential is connected. According to such an aspect, although about 1% of the display area in which the deterioration of the display color cannot be suppressed occurs, it is possible to further suppress the decrease in the lifetime of the electronic circuit and the increase in the power consumption by about 10%.

  According to the driving method of the reflective display device of the present invention, the voltage application time required for switching from another display color to the display color corresponding to the display region where the display color should be kept as it is. By applying the voltage for a time length of 5% to 30% of the length, it is possible to suppress deterioration of the display color in each display region while suppressing a decrease in the lifetime of the electronic circuit and an increase in power consumption.

  Further, according to the reflection side display device according to the present invention, the voltage application control unit is required to switch the display color corresponding to the display area that should keep the display color from the other display color to the display color. By applying a voltage for a time length of 5% to 30% of the time length of the correct voltage application, the deterioration of the display color in each display area is suppressed while suppressing the decrease in the life of the electronic circuit and the increase in power consumption. it can.

FIG. 1 is a plan view schematically showing a configuration of a reflective display device according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA in the reflective display device shown in FIG. FIGS. 3A to 3D are schematic diagrams illustrating examples of display images displayed on the reflective display device illustrated in FIG. 1. FIG. 4 is a schematic diagram showing a waveform of a voltage applied to each display electrode when the display images shown in FIGS. 3A to 3D are rewritten in this order. FIG. 5 is a graph showing the relationship between the ratio of the connection time length of the first potential for the second time to the first time length and the number of display areas that have recovered the original display color (black). FIG. 6 is a graph showing a relationship between the ratio of the connection time length of the third potential for the second time to the second time length and the number of display areas in which the original display color (white) is restored.

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

  As shown in FIGS. 1 and 2, the reflective display device 10 according to the present embodiment has two opposing sheets, at least one of which has translucency and each of which electrodes 111 or 161a to 161d are formed. 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 FIG. 2, one (11 in the illustrated example) covering the display regions 15a to 15d is provided between one substrate 11 and the other substrate 16. Alternatively, two or more (one in the illustrated example) common electrode 111, a display medium layer in which the display medium 13 is disposed, and a plurality of (in the illustrated example) corresponding to each of the plurality of display regions 15a to 15d. The four display electrodes 161a to 161d are provided in this order from the 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, as the common electrode 111, A material with a translucent electrode such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO) is typically used. The common electrode 111 of the present embodiment is formed as a common electrode for segment driving.

  The common electrode 111 is formed so as to cover the plurality of display regions 15a to 15d 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 111 is not necessarily formed with a pattern, and the entire surface of the substrate may be an electrode.

  As shown in FIG. 2, the common electrode 111 is connected to a second potential (for example, GND). In the present embodiment, the second potential is 0V.

  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 caused by moisture entering the display medium layer. 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 13 side), or provided on the surface opposite to the surface on the display medium 13 side. May be. Further, the barrier layer may be provided between the one substrate 11 and the common electrode 111. In the present embodiment, since one substrate 11 is disposed on the viewing side, the barrier layer needs to be translucent. 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 formed in advance 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 surface on the display medium 13 side. Alternatively, one substrate 11 itself may have an ultraviolet absorbing function.

  Further, on the surface opposite to the surface on the display medium 13 side of one substrate 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, display electrodes 161 a to 161 d are formed of a conductive material such as metal on the surface of the display medium 13 side of a substrate such as a resin film, a resin plate, glass, or epoxy glass (glass epoxy). Can be used. The display electrodes 161a to 161d of the present embodiment are formed as segmented pattern pattern electrodes (segment electrodes). As shown in FIG. 2, the display regions 15 a to 15 d in the reflective display device 10 are defined by individual display electrodes 161 a to 161 d.

  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.

  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 surface of the other substrate 16 on the display medium 13 side (on the display electrodes 161a to 161d), or provided on the surface opposite to the surface of the display medium 13 side. May be.

  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 13 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. The display medium layer of this embodiment includes a partition wall 12 that partitions a plurality of cells between one substrate 11 and the other substrate 16. The display medium 13 is arranged in each cell. Here, the “cell” means an electrophoretic response that is divided between the two substrates 11 and 16 to prevent poor display due to sedimentation or uneven distribution of the electroresponsive material, in particular, a decrease in contrast. It means a minute migration space of a functional material, that is, a 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 electroresponsive material is low, the space between the two 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 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 12 and the display electrodes 161 a to 161 d on the other substrate 16 or other elements on the other substrate 16 or the other substrate 16, the top surface of the partition wall 12 and the other surface An adhesive layer (not shown) for adhering the display electrodes 161 a to 161 d on the substrate 16, other elements 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 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 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 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.

  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 represented 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, and a cholesteric liquid crystal material.

  In the present embodiment, the display medium 13 includes a dispersion medium, and a white electroresponsive material and a black electroresponsive material dispersed in the dispersion medium. The black electroresponsive material is positively charged and the white electroresponsive material is negatively charged. As a result, when the potentials of the display electrodes 161a to 161d are made lower than the potential of the common electrode 111, the positively charged black electroresponsive material migrates so that the dispersion medium is attracted to the common electrode 111 side. Then, the negatively charged white electroresponsive material migrates so that the dispersion medium is drawn toward the display electrodes 161a to 161d. Further, when the potentials of the display electrodes 161a to 161d are made higher than the potential of the common electrode 111, the positively charged black electroresponsive material is drawn toward the display electrodes 161a to 161d in the dispersion medium. The negatively charged white electroresponsive material migrates so that the dispersion medium is drawn toward the common electrode 111 side. Then, by controlling the migration of such white and black electroresponsive materials, in the reflective display device 10, the display color of either white or black is changed to the common electrode 111 side (that is, the viewing side). Can be selectively displayed.

  As shown in FIG. 2, the reflective display device 10 according to the present embodiment further includes a voltage application control unit 17 that applies a voltage to each of the display electrodes 161 a to 161 d.

  The voltage application controller 17 of the present embodiment has a plurality of output terminals and a GND terminal. Each output terminal is electrically connected to a different display electrode 161a to 161d, and the GND terminal is connected to GND.

  The voltage application control unit 17 according to the present embodiment applies the second potential to the display electrode corresponding to the display region where the display color should be switched from the second color to the first color at the same time at the display rewrite timing. A different first potential is connected for a first time length, and then a second potential is connected. The display electrode corresponding to the display region to be switched from the first color to the second color is connected to the second potential. On the other hand, a third potential having a polarity opposite to that of the first potential is connected for the second time length, and then the second potential is connected, and the display electrode corresponding to the display region that should hold the display color of the first color as it is. The first potential is connected for a time length of 5% to 30% of the first time length, and then the second potential is connected, and the display corresponding to the display area that should hold the second display color as it is. A third potential is connected to the electrode for a time length of 5% to 30% of the second time length, It is adapted to connect the second potential after.

  Specifically, for example, the voltage application control unit 17 applies the first potential (+15 V) to the display electrode corresponding to the display region whose display color should be switched from white to black at the display rewrite timing for the first time. The connection is made only for a long time (300 ms), and then the second potential (0 V) is connected. By connecting the first potential to the display electrode for the first time length, the positively charged black electroresponsive material moves to the common electrode 111 side, and the negatively charged white electroresponsive material becomes It moves to the display electrode side, and as a result, black is displayed on the common electrode 111 side (viewing side) of the display region. In addition, by subsequently connecting the second potential to the display electrode, the black electro-responsive material and the white electro-responsive material each stop in place (strictly move gradually due to the influence of weight, etc.) As a result, the black display color is maintained.

  In addition, the voltage application control unit 17 applies the third potential (−15V) to the second time length (300 ms) for the display electrode corresponding to the display region whose display color should be switched from black to white at the display rewrite timing. Only the second potential (0 V) is connected thereafter. By connecting the third potential to the display electrode for the second time length, the positively charged black electroresponsive material moves to the display electrode side, and the negatively charged white electroresponsive material becomes As a result, white is displayed on the common electrode 111 side (viewing side) of the display region. In addition, by subsequently connecting the second potential to the display electrode, the black electro-responsive material and the white electro-responsive material each stop in place (strictly move gradually due to the influence of weight, etc.) As a result, the white display color is maintained.

  On the other hand, at the display rewrite timing, the voltage application control unit 17 applies the first potential (+15 V) to the display electrode corresponding to the display region that should retain the black display color as it is from 5% of the first time length. The connection is made for a time length of 30% (15 ms to 90 ms), and then the second potential (0 V) is connected. By connecting the first potential to the display electrode for a time length of 5% to 30% of the first time length, the positively charged black that has gradually moved to the display electrode side due to the influence of gravity or the like , The negatively charged white electroresponsive material that gradually moved to the common electrode 111 side moved to the display electrodes 161a to 161d side. Therefore, the original black (that is, black immediately after switching from white to black) is displayed on the common electrode 111 side (viewing side) of the display region. In addition, by subsequently connecting the second potential to the display electrode, the black electro-responsive material and the white electro-responsive material each stop in place (strictly move gradually due to the influence of weight, etc.) As a result, the black display color is maintained.

  In addition, the voltage application control unit 17 applies the third potential (−15V) to 5% of the second time length for the display electrode corresponding to the display region where the white display color should be maintained as it is at the display rewrite timing. Connection is made for a time length of ˜30% (15 ms to 90 ms), and then the second potential is connected. By connecting the third potential to the display electrode for a time length of 5% to 30% of the second time length, the negatively charged white that has gradually moved to the display electrode side due to the influence of gravity or the like And the positively charged black electroresponsive material that gradually moved to the common electrode 111 side moved to the display electrodes 161a to 161d side. Accordingly, the original white color (that is, the white color immediately after switching from black to white) is displayed on the common electrode 111 side (viewing side) of the display area. In addition, by subsequently connecting the second potential to the display electrode, the black electro-responsive material and the white electro-responsive material each stop in place (strictly move gradually due to the influence of weight, etc.) As a result, the white display color is maintained.

  The “display rewriting timing” means a timing at which a desired display image is displayed again on the viewer in the reflective display device 10, and has a predetermined period (for example, 1 s) like a digital display clock, for example. It may be the timing that is repeated at the same time, or may be a timing that is manually given irregularly like a calculator.

  In addition, when the voltage application control unit 17 applies the voltage of the magnitude V for the time length T, the voltage application control unit 17 may apply the voltage of the magnitude V continuously for the time length T. Then, a pulse-like voltage having a time length (pulse width) W may be applied only T / W times.

  In addition, the voltage application control unit 17 according to the present embodiment applies the first potential to the display electrode corresponding to the display region that holds the display color of the first color as it is, from 5% to 30% of the first time length. The third potential is applied to the display electrode corresponding to the display region to which the second potential is connected and the display color of the second color is maintained as it is. The voltage application of connecting for the time length of% and then connecting the second potential is repeated at a predetermined cycle (for example, 30 min to 180 min) until the next display rewrite timing. Thus, for example, when the display rewriting cycle is relatively long, such as a daily calendar, or when the frequency of manual display rewriting is low, such as a barcode attached to a product, the display state (display) The overall deterioration of the image) can be effectively suppressed until the next display rewrite timing.

  Next, an example of a driving method of the reflective display device 10 having such a configuration will be described with reference to FIGS. 3 (a) to 3 (d) and FIG. Hereinafter, the display areas 15a to 15d are also referred to as first to fourth display areas 15a to 15d, respectively.

  FIG. 3A to FIG. 3D are schematic views illustrating examples of display images displayed on the reflective display device 10 according to the present embodiment, respectively. FIG. 4 is a schematic diagram showing waveforms of voltages applied to the display electrodes 161a to 161d when the display images shown in FIGS. 3A to 3D are switched in this order.

  In the present embodiment, an initial image as shown in FIG. 3A is displayed in the initial state. That is, the first display area 15a and the second display area 15b are displayed in white, and the third display area 15c and the fourth display area 15d are displayed in black. The display electrodes 161a to 161d corresponding to the display regions 15a to 15d are connected to a second potential (for example, 0 V).

  First, the step of rewriting the initial image shown in FIG. 3A to the first image shown in FIG. 3B, that is, the display color of the second display area 15b and the display of the fourth display area 15d. A process of switching the display color of the first display area 15a from white to black and switching the display color of the third display area 15c from black to white while maintaining the color as it is will be described.

  In this case, as shown in FIG. 4, the voltage application control unit 17 applies the first potential (for example, + 15V) to the display electrode 161a corresponding to the first display region 15a at the same time at the display rewrite timing. Connect for one hour length (for example, 300 ms), and then connect the second potential. As a result, the display color of the first display area 15a is switched from white to black. In addition, the display electrode 161c corresponding to the third display region 15c has a third potential (for example, −15V) having a polarity opposite to the first potential with respect to the second potential for a second time length (for example, 300 ms). ) And then the second potential is connected. As a result, the display color of the third display area 15c is switched from black to white. On the other hand, the third potential (ie, −15 V) is connected to the display electrode 161b corresponding to the second display region 15b for a time length of 5% to 30% of the second time length (ie, 15 ms to 90 ms). Then, the second potential is connected. Thereby, the display color of the second display area 15b is restored to the original white color. Further, the display electrode 161d corresponding to the fourth display region 15d is connected to the first potential (ie, + 15V) for a time length of 5% to 30% of the first time length (ie, 15 ms to 90 ms). Thereafter, the second potential is connected. As a result, the display color of the fourth display area 15d is restored to the original black color.

  Next, the step of rewriting the first image shown in FIG. 3B to the second image shown in FIG. 3C, that is, the display of the first display area 15a and the fourth display area 15d. A process of switching the color from black to white and switching the display color of the second display area 15b and the third display area 15c from white to black will be described.

  In this case, as shown in FIG. 4, at the next display rewrite timing, the voltage application control unit 17 displays the display electrode 161a corresponding to the first display region 15a and the display corresponding to the fourth display region 15d. A third potential (that is, −15 V) is connected to each of the electrodes 161d for a second time length (that is, 300 ms), and then the second potential is connected. As a result, the display color of the first display area 15a and the display color of the fourth display area 15d are each switched from black to white. Further, the display electrode 161b corresponding to the second display region 15b and the display electrode 161c corresponding to the third display region 15c are each supplied with the first potential (that is, + 15V) for the first time length (that is, + 15V). 300 ms) and then the second potential is connected. As a result, the display color of the second display area 15b and the display color of the third display area 15c are switched from white to black, respectively.

  Next, the step of rewriting the second image shown in FIG. 3C to the third image shown in FIG. 3D, that is, the display color of the second display area 15b and the fourth display area. A process of switching the display color of the first display area 15a from white to black and switching the display color of the third display area 15c from black to white while maintaining the display color of 15d as it is will be described.

  In this case, as shown in FIG. 4, the voltage application controller 17 applies the first potential (that is, + 15V) to the display electrode 161a corresponding to the first display region 15a all at once at the next display rewrite timing. Are connected for the first time length (ie, 300 ms), and then the second potential is connected. As a result, the display color of the first display area 15a is switched from white to black. Further, the third potential (ie, −15 V) is connected for the second time length (ie, 300 ms) to the display electrode 161 c corresponding to the third display region 15 c, and then the second potential is connected. As a result, the display color of the third display area 15c is switched from black to white. On the other hand, the display electrode 161b corresponding to the second display region 15b is connected to the first potential (ie, +15 V) for a time length of 5% to 30% of the first time length (ie, 15 ms to 90 ms). Thereafter, the second potential is connected. Thereby, the display color of the second display area 15b is restored to the original black color. Further, the third potential (ie, −15 V) is connected to the display electrode 161 d corresponding to the fourth display region 15 d for a time length of 5% to 30% of the second time length (ie, 15 ms to 90 ms). Then, the second potential is connected. Thereby, the display color of the fourth display area 15d is restored to the original white color.

  Although not shown, until the next display rewrite timing, the voltage application control unit 17 then displays the display electrode 161a corresponding to the first display region 15a and the display electrode 161b corresponding to the second display region 15b. The first potential (that is, + 15V) is connected for a time length of 5% to 30% of the first time length (that is, 15 ms to 90 ms), and then the second potential is connected to correspond to the third display region 15c. The display electrode 161c and the display electrode 161d corresponding to the fourth display region 15d are each supplied with a third potential (ie, −15 V) for a time length of 5% to 30% of the second time length (ie, 15 ms). (Approx. 90 ms), and then the voltage application of connecting the second potential is repeated at a predetermined cycle (for example, 30 min to 180 min). Thereby, the deterioration of the third image shown in FIG. 3D is effectively suppressed until the next display rewriting timing.

  Next, specific examples (evaluation experiment results) will be described.

  First, as a first example according to the present embodiment, +15 V (first potential) is connected for 300 ms (first time length) to each display electrode corresponding to 100 display regions, and then 0 V (first time). By connecting the two potentials, the display color of each display area is black. Then, the reflectance of each display area was measured, and the measurement result was stored as a reference value.

  Next, after leaving the second potential connected to each display electrode for 5 hours, the first potential is connected to each display electrode for a time length of 30% of the first time length (that is, 90 ms), and then A second potential was connected. Then, when the reflectance of each display area was measured, the display area where the original display color (black) was restored (that is, the display area whose measurement result is within 1% of the reference value) The number of was 100.

  Next, as a second example according to the present embodiment, the same process as in the first example, except that the connection time length of the second first potential is changed to 20% of the first time length (that is, 60 ms). Was repeated to measure the reflectance of each display area. As a result, 99 display areas were recovered from the original display color (black).

  Next, as a third example according to the present embodiment, the same process as in the first example, except that the connection time length of the second first potential is changed to 10% of the first time length (that is, 30 ms). Was repeated and the reflectance of each display region was measured. As a result, the number of display regions that were able to recover the original display color (black) was 98.

  Next, as a fourth example according to the present embodiment, the same steps as in the first example except that the connection time length of the first potential for the second time is changed to 5% of the first time length (that is, 15 ms). Was repeated and the reflectance of each display region was measured. As a result, the number of display regions that were able to recover the original display color (black) was 95.

  Next, as a first comparative example, the same steps as in the first embodiment are repeated except that the connection time length of the first potential for the second time is changed to 4% of the first time length (that is, 12 ms), When the reflectance of the display area was measured, the number of display areas that were able to recover the original display color (black) was 85.

  Next, as a second comparative example, the same steps as in the first embodiment are repeated except that the connection time length of the first potential for the second time is changed to 40% of the first time length (that is, 120 ms), When the reflectance of the display area was measured, the number of display areas that were able to recover the original display color (black) was 100.

  The above results are summarized in FIG. Here, the above results did not change even when the standing time (5 hours) was shortened to 1 hour or extended to 3 days.

  According to the above results, the voltage application time length required for switching from the white display color to the black display color is applied to the display electrodes corresponding to the 100 display regions that should keep the black display color as they are. When the voltage was applied for a time length of 5%, the 95 display areas were able to recover the original display color (that is, the black display color immediately after switching from the white display color to the black display color). Specifically, if the reflectance of the display area is within 1% of the reflectance immediately after switching from the white display color to the black display color, it is evaluated that the original display color can be recovered. If the difference was larger than 1%, it was evaluated that the original display color could not be recovered. When the time length was changed to 4%, the original display color could be recovered only for 85 display areas.

  From the above results, when the black display color is kept as it is, the value of 5% (that is, 15 ms) has a display color in each display area while suppressing the decrease in the life of the electronic circuit and the increase in power consumption. It can be said that there is a critical significance that it is possible to suppress the deterioration of the material. In addition, in a numerical range larger than 30% (that is, 90 ms), the effect does not change in that display color deterioration in each display area can be suppressed. Rather, the voltage application is excessive and the life of the electronic circuit is reduced. And it can be said that the increase in power consumption cannot be suppressed.

  Next, as a fifth example according to the present embodiment, −15 V (third potential) is connected for 300 ms (second time length) to each display electrode corresponding to 100 display regions, and then 0 V is applied. By connecting (second potential), the display color of each display region was set to white. Then, the reflectance of each display area was measured, and the measurement result was stored as a reference value.

  Next, after leaving the second potential connected to each display electrode for 5 hours, the third potential is connected to each display electrode for 30% of the second time length (ie, 90 ms), and then A second potential was connected. Then, when the reflectance of each display area was measured, the display area where the original display color (white) was recovered (that is, the display area where the measurement result is within 1% of the reference value). The number of was 100.

  Next, as a sixth example according to the present embodiment, the same process as the fifth example except that the connection time length of the second third potential is changed to 20% of the second time length (that is, 60 ms). Was repeated and the reflectance of each display area was measured. As a result, the number of display areas that were able to recover the original display color (white) was 99.

  Next, as a seventh example according to the present embodiment, the same process as the fifth example except that the connection time length of the third potential for the second time is changed to 10% of the second time length (that is, 30 ms). Was repeated and the reflectance of each display area was measured. As a result, the number of display areas which were able to recover the original display color (white) was 98.

  Next, as an eighth example according to the present embodiment, the same process as in the fifth example, except that the connection time length of the third potential for the second time is changed to 5% of the second time length (that is, 15 ms). Was repeated and the reflectance of each display area was measured. As a result, the number of display areas that were able to recover the original display color (white) was 95.

  Next, as a third comparative example, the same process as in the fifth embodiment is repeated except that the connection time length of the third potential for the second time is changed to 4% of the second time length (that is, 12 ms). When the reflectance of the display area was measured, the number of display areas that were able to recover the original display color (white) was 85.

  Next, as a fourth comparative example, the same process as in the fifth embodiment is repeated except that the connection time length of the third potential for the second time is changed to 40% (that is, 120 ms) of the second time length, When the reflectance of the display area was measured, the number of display areas that were able to recover the original display color (white) was 100.

  The above results are summarized in FIG. Here, the above results did not change even when the standing time (5 hours) was shortened to 1 hour or extended to 3 days.

  According to the above results, the voltage application time length required for switching from the black display color to the white display color is applied to the display electrodes corresponding to the 100 display regions that should retain the white display color. When the voltage was applied for a time length of 5%, the 95 display areas were able to recover the original display color (that is, the white display color immediately after switching from the black display color to the white display color). Specifically, if the reflectance of the display area is within 1% of the reflectance immediately after switching from the black display color to the white display color, it is evaluated that the original display color can be recovered. If the difference was larger than 1%, it was evaluated that the original display color could not be recovered. When the time length was changed to 4%, the original display color could be recovered only for 85 display areas.

  From the above results, even when the white display color is kept as it is, the value of 5% (that is, 15 ms) is displayed in each display area while suppressing the decrease in the life of the electronic circuit and the increase in the power consumption. It can be said that there is a critical significance that color deterioration can be suppressed. In addition, in a numerical range larger than 30% (that is, 90 ms), the effect does not change in that display color deterioration in each display area can be suppressed. Rather, the voltage application is excessive and the life of the electronic circuit is reduced. And it can be said that the increase in power consumption cannot be suppressed.

  That is, according to the present embodiment as described above, the display electrodes 161a to 161d corresponding to the display regions 15a to 15d that should hold the display colors as they are are switched from the other display colors to the display colors. The display color in each of the display areas 15a to 15d is controlled by applying the voltage for a time length of 5% to 30% of the required voltage application time length, while suppressing the decrease in the lifetime of the electronic circuit and the increase in power consumption, respectively. Can be prevented.

  More preferably, for the display electrode corresponding to the display region that holds the black display color as it is, the first potential (ie, +15 V) is applied to a time length of 5% to 20% of the first time length (ie, 15 ms). To the display electrode corresponding to the display region that maintains the white display color as it is, the third potential (that is, −15 V) is applied to the second time length. The connection is made only for a time length of 5% to 20% (that is, 15 ms to 60 ms), and then the second potential is connected. In this case, according to the above-described verification result, although a display area in which deterioration of display color cannot be suppressed occurs by about 1%, it is possible to further suppress a decrease in the lifetime of the electronic circuit and an increase in power consumption by about 10%.

DESCRIPTION OF SYMBOLS 10 Reflective display apparatus 11 One board | substrate 111 Common electrode 12 Partition 13 Display medium 15a Display area 15b Display area 15c Display area 15d Display area 16 The other board | substrate 161a Display electrode 161b Display electrode 161c Display electrode 161d Display electrode 17 Voltage application controller

Claims (10)

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, one or more common electrodes covering a plurality of display areas, a display medium layer on which the display medium is disposed, and the plurality of display areas A plurality of display electrodes corresponding to each are provided in this order from the one substrate side to the other substrate side,
The one or more common electrodes are connected to a second potential;
Each of the plurality of display regions selectively selects either 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 region. A method of driving a reflective display device capable of displaying,
A first potential different from the second potential is connected for a first time length to the display electrode corresponding to the display region for switching the display color from the second color to the first color, and then the second potential is connected. And
The display electrode corresponding to the display region for switching the display color from the first color to the second color is connected with a third potential having a polarity opposite to the first potential for the second time length with respect to the second potential. And then connecting the second potential,
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. A method for driving a reflective display device, characterized in that: At the time of display rewriting,
The display electrode corresponding to the display region for switching the display color from the second color to the first color is connected to the first potential for the first time length, and then connected to the second potential.
The display electrode corresponding to the display region for switching the display color from the first color to the second color is connected to the third potential for the second time length, and then connected to the second potential.
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. The method for driving a reflection type display device according to claim 1, wherein: The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. Connect,
The method of driving a reflective display device according to claim 1, wherein the voltage application is repeated at a predetermined cycle until the next display rewrite timing. The method for driving a reflective display device according to claim 3, wherein the predetermined period is 30 to 180 min. The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 20% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 20% of the second time length, and then the second potential. The method for driving a reflective display device according to claim 1, wherein: 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;
One or more common electrodes provided on the display medium side surface of the one substrate and covering a plurality of display regions;
A plurality of display electrodes provided on a surface of the other substrate on the display medium side and corresponding to each of the plurality of display regions;
A voltage application controller for applying a voltage to each display electrode;
With
The one or more common electrodes are connected to a second potential;
Each of the plurality of display regions selectively selects either 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 region. Can be displayed,
The voltage application controller is
A first potential different from the second potential is connected for a first time length to the display electrode corresponding to the display region for switching the display color from the second color to the first color, and then the second potential is connected. And
The display electrode corresponding to the display region for switching the display color from the first color to the second color is connected with a third potential having a polarity opposite to the first potential for the second time length with respect to the second potential. And then connecting the second potential,
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. A reflection type display device characterized by being connected. The voltage application control unit simultaneously at the display rewrite timing,
The display electrode corresponding to the display region for switching the display color from the second color to the first color is connected to the first potential for the first time length, and then connected to the second potential.
The display electrode corresponding to the display region for switching the display color from the first color to the second color is connected to the third potential for the second time length, and then connected to the second potential.
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. The reflection type display device according to claim 6, wherein the reflection type display device is connected. The voltage application controller is
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 30% of the first time length, and then the second potential. Connect
The third potential is connected to a display electrode corresponding to a display region that retains the display color of the second color as it is for a time length of 5% to 30% of the second time length, and then the second potential. Connect,
The reflective display device according to claim 6 or 7, wherein the voltage application is repeated at a predetermined cycle until the next display rewrite timing. The reflective display device according to claim 8, wherein the predetermined period is 30 min to 180 min. The voltage application controller is
The first potential is connected to a display electrode corresponding to a display region that retains the display color of the first color as it is for a time length of 5% to 20% of the first time length, and then the second potential. Connect
The third potential is applied to a display electrode corresponding to a display region that holds the display color of the second color as it is for a time length of 5% to 20% of the second time length, and then the second potential. The reflective display device according to claim 6, wherein the reflection type display device is connected.

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