JP2007187936A - Electrophoresis display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoresis display device wherein refreshing operation is timely executed. <P>SOLUTION: When image formation is required, the present temperature is acquired from a temperature sensor (S102), a value of a frequency counter counting an image writing frequency after the last refreshing operation is acquired (S103) and these values and respective coefficients stored in a weight table are used (S101) to calculate a timing value (S105). When the calculated timing value exceeds a threshold (S106:YES), refreshing operation is executed (S107), the frequency counter is reset (S108) and then image writing is performed (S111). When the calculated value does not exceed the threshold (S106:NO), image writing is continued (S111) and 1 is added to the value of the frequency counter (S112). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device that displays an image using an electrophoretic phenomenon.

  In general, an electrophoretic display device that displays an image using an electrophoretic phenomenon is known. In this electrophoretic display device, a sealed space having a predetermined interval is formed through a peripheral gap spacer by a transparent substrate on one side and a back substrate disposed opposite thereto. Then, a display medium is formed by filling the sealed space with a dispersion medium made of colored liquid or gas in which charged particles, which are colored spherical particles, are dispersed.

  Under such a configuration, for example, in an electrophoretic display device in which white charged particles are dispersed in a dispersion medium composed of a black liquid, an electric field is generated from two substrates in the display medium, The charged particles are moved to the display substrate side to display the white color of the charged particles on the surface of the display substrate, or the charged particles are moved to the back substrate side to display the black of the dispersion medium on the surface of the display substrate. As a result, a desired image is obtained.

  In such a conventional electrophoretic display device, charged particles may agglomerate over time, or charged particles may be biased to a part of the display unit, and if an image is not displayed for a long time, Charged particles sometimes settled in the display liquid. If such agglomeration, bias, or sedimentation of charged particles occurs, the charged particles cannot be sufficiently moved even if an electric field is generated in the display liquid, resulting in color unevenness or image contrast. There is a problem that image quality deteriorates due to a decrease in image quality.

  In order to prevent such deterioration of image quality, it is conceivable to eliminate aggregation of charged particles by applying a large voltage to the electrode to generate a strong electric field. However, this method has a problem that the power consumption of the electrophoretic display device is greatly increased and the device is difficult to handle due to high voltage.

Therefore, in Patent Document 1, a method of facilitating the electrophoresis of charged particles by facilitating peeling of charged particles adhering undesirably to the wall surface by alternately applying reverse polarity pulse voltages in the previous stage of image formation. Is disclosed.
JP 2000-321605 A

  It has been desired that such an operation of alternately applying reverse polarity pulse voltages (hereinafter referred to as a refresh operation) be performed in a timely manner according to the state of the display unit. In order to calculate the timing of the refresh operation, for example, it is conceivable to count the number of times of image formation from the previous refresh operation and execute the refresh operation when a certain number is reached. In consideration, the refresh operation may not be executed when necessary.

  For example, there are the following problems. The charged particles become easier to move as the temperature increases. Therefore, for example, in an electrophoretic display device in which white charged particles are dispersed in a dispersion medium made of a black liquid, a pixel displaying white color gradually changes to gray in a place where the temperature is high (hereinafter, "Gray deterioration") is likely to occur. When the image forming operation is performed in the gray-degraded state, charged particles adhere to the substrate.

  The present invention has been made to solve the above problems, and an object thereof is to provide an electrophoretic display device in which a refresh operation is performed in a timely manner.

  To achieve the above object, an electrophoretic display device according to claim 1 of the present invention includes a first substrate having a first electrode and a second substrate having a second electrode, which are arranged so as to face each other, A plurality of charged particles moving according to the direction of the electric field generated between the display unit formed in the gap between the first substrate and the second substrate and the first electrode and the second electrode are dispersed, When a dispersion medium filled in the display unit, a display panel including the first and second substrates and the display unit, and when an image formation request is made to the display unit, the first electrode and An image forming means for executing an image forming operation for generating an electric field with respect to the dispersion medium by applying a voltage to the second electrode; and before performing the image forming operation by the image forming means, the plurality of charged particles In order to disperse uniformly in the dispersion medium, Refresh control means for applying a voltage to one electrode and the second electrode and performing a refresh operation for generating an electric field on the dispersion medium while alternately switching the direction of the generated electric field at a predetermined timing. An electrophoretic display device comprising: an image formation number counting unit that counts the number of times an image forming operation is performed by the image forming unit after a refresh operation is performed by the refresh control unit; and an ambient temperature at a predetermined timing. Based on the temperature measurement means to be measured, the number of times counted by the image formation number counting means, and the temperature measured by the temperature measurement means, it is determined whether or not to cause the refresh control means to perform a refresh operation. And refresh determination means.

  Note that the refresh determination unit determines execution of the refresh operation based on a result determined based on the number of times and the temperature even if the number of times counted by the image formation number counting unit is equal to or less than a predetermined number. May be.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the electrophoretic display device includes the number of times the refresh determination unit counts the image formation number counting unit, and the image. Whether or not to perform the refresh operation is determined based on the temperature measured by the temperature measuring means when the formation request is made.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, the electrophoretic display device includes the number of times the refresh determination unit counts by the image formation number counting unit, and the refreshing unit. Whether or not to perform the refresh operation is determined based on the maximum temperature measured by the temperature measurement unit from the execution of the refresh operation by the control unit to the time when the image formation is requested.

  According to a fourth aspect of the present invention, in addition to the configuration of the first aspect, the electrophoretic display device includes the number of times the refresh determination unit counts the image forming number counting unit, and the refreshing unit. Whether or not to perform the refresh operation is determined based on an average value of the temperatures measured by the temperature measurement unit from the execution of the refresh operation by the control unit to the time when the image formation is requested.

  Further, in the electrophoretic display device according to claim 5 of the present invention, in addition to the configuration of the invention according to any one of claims 1 to 4, the refresh determination means is counted by the image formation number counting means. When the calculated value calculated based on the number of times and the temperature measured by the temperature measuring means exceeds a predetermined threshold, execution of the refresh operation is determined.

  An electrophoretic display device according to a sixth aspect of the present invention is the electrophoretic display device according to any one of the first to fourth aspects, wherein the refresh determination means counts the number of times the image formation is counted. When the cumulative value of the calculated values calculated based on the temperature measured by the temperature measuring means exceeds a predetermined threshold value, the execution of the refresh operation is determined.

  Further, an electrophoretic display device according to a seventh aspect of the present invention includes a detection means for detecting a predetermined user operation in addition to the configuration of the invention according to any one of the first to sixth aspects, The refresh determination unit determines execution of the refresh operation when an input is detected by the detection unit.

  An electrophoretic display device according to an eighth aspect of the present invention is the electrophoretic display device according to any one of the first to seventh aspects, wherein the temperature measuring means is the same as the surface on which the display panel is formed. It is a temperature sensor arranged on the surface.

  An electrophoretic display device according to a ninth aspect of the present invention is the electrophoretic display device according to any one of the first to eighth aspects, wherein the temperature measuring means includes a heat generating part in the electrophoretic display device. It is a temperature sensor that measures the temperature at a point where the straight line connecting the display panel and the display panel intersects.

  An electrophoretic display device according to a tenth aspect of the present invention is the electrophoretic display device according to any one of the first to ninth aspects, wherein the temperature measuring means includes a plurality of temperatures arranged on the display panel. A refresh determination unit that determines whether or not to cause the refresh control unit to perform a refresh operation based on a highest temperature among a plurality of temperatures measured by the plurality of temperature sensors. Features.

  The electrophoretic display device according to claim 1 of the present invention determines whether or not to perform the refresh operation based on the number of times that the image forming operation has been performed after the previous refresh operation and the measured ambient temperature. decide. The charged particles become easier to move as the temperature increases. Therefore, for example, in an electrophoretic display device in which white charged particles are dispersed in a dispersion medium composed of a black liquid, gray deterioration occurs in which a pixel displaying white gradually changes to gray in a place where the temperature is high. It becomes easy. When the image forming operation is performed in the gray-degraded state, charged particles adhere to the substrate. However, in order to determine the timing of the refresh operation in consideration of the temperature information in addition to the number of executions of the image forming operation, the temperature Even when gray deterioration occurs at a high place, even when the number of image formations so far is small, the refresh operation is performed, and the display quality can be improved.

  According to a second aspect of the present invention, in addition to the effect of the first aspect, the electrophoretic display device includes the number of execution times of the image forming operation and the temperature measuring unit when the image forming request is made. Whether or not to perform the refresh operation is determined based on the temperature measured by the above. Therefore, if there is an image formation request when the temperature is high, refreshing is facilitated, so that refreshing can be performed at a high frequency when used in a hot place.

  According to a third aspect of the present invention, in addition to the effect of the first aspect, the electrophoretic display device includes the number of executions of the image forming operation and the temperature between the execution of the refresh operation and the request for image formation. Whether or not to perform the refresh operation is determined based on the maximum temperature measured by the measuring means. Therefore, if there is a high temperature between the time of the last refresh and the time when the image formation is requested, it is easy to be refreshed, so it is possible to cope with gray deterioration due to a temporary rapid temperature rise.

  The electrophoretic display device according to claim 4 of the present invention, in addition to the effect of the invention according to claim 1, is measured from the number of executions of the image forming operation and from the execution of the refresh operation to the time of image formation request. Whether or not to perform the refresh operation is determined based on the average value of the measured temperatures. Accordingly, since it is easy to be refreshed when the temperature is high on average at the time of each write request between the time of the last refresh and the time of the image formation request, it is possible to cope with accumulation of gray deterioration due to the high temperature state continuing for a long time. .

  The electrophoretic display device according to claim 5 of the present invention takes into account the temperature information in addition to the number of executions of the image forming operation in addition to the effect of the invention according to any one of claims 1 to 4. Since the timing of the refresh operation is calculated and determined, the refresh operation is performed even when gray degradation occurs in a place with high temperature or the number of image formations so far is small, and display quality can be improved. .

  According to a sixth aspect of the present invention, in addition to the effect of the first aspect, the electrophoretic display device takes into account the temperature information in addition to the number of executions of the image forming operation. Since the timing of the refresh operation is calculated and determined based on the cumulative value, the refresh operation is performed even when gray deterioration occurs at a high temperature place or the number of image formations so far is reduced, improving display quality can do.

  According to a seventh aspect of the present invention, in addition to the effects of the first aspect, the electrophoretic display device decides to perform a refresh operation when a user operation is detected. Therefore, the refresh operation can be executed at the timing intended by the user.

  In addition to the effect of the invention according to any one of claims 1 to 7, the electrophoretic display device according to claim 8 has a temperature sensor disposed on the same surface as the surface on which the display panel is formed. The temperature applied to the display panel can be accurately detected. For example, in a situation where the temperature is affected by light, such as outdoor sunlight or indoor illumination light, a temperature difference is likely to occur on different planes.

  In addition to the effect of the invention according to any one of claims 1 to 8, the electrophoretic display device according to claim 9 measures a temperature at a position where heat is easily transmitted from a heat generating part such as a CPU in the device. Therefore, it is possible to cope with the gray deterioration of the portion of the display panel in which the gray deterioration easily occurs due to the heat received from the heat generating portion.

  In addition to the effect of the invention according to any one of claims 1 to 9, the electrophoretic display device according to claim 10 is based on the highest temperature among a plurality of temperatures measured by a plurality of temperature sensors. Since the timing of the refresh operation is determined, it is possible to cope with the gray deterioration of the display panel portion where the temperature is high and gray deterioration is likely to occur.

  Hereinafter, an image display device 1 embodying an electrophoretic display device according to the present invention will be described with reference to the drawings. An image display device 1 exemplified as the present embodiment is integrally provided with a small display panel 2 that can be provided in a portable electronic device and a control board 3 that controls image display on the display panel 2. .

  First, an outline of a physical configuration of the image display apparatus 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the image display device 1. FIG. 2 is a front view of the display panel 2. FIG. 3 is a cross-sectional view in the direction of the arrows along the line AA ′ (FIG. 2) of the display panel 2. FIG. 4 is a cross-sectional view in the direction of the arrows along the line BB ′ (FIG. 2) of the display panel 2. 3 and 4 is the front of the image display device 1.

  As shown in FIGS. 1 to 4, in the image display device 1, the display panel 2 has a vertically long rectangular parallelepiped shape as an example. As shown by a dotted line in FIG. 1, a control board 3 is provided on the back side of the display panel 2 when the image display device 1 is viewed from the front, and the display panel 2 and the control board 3 are electrically connected. ing.

  In the display panel 2, a lower substrate 10 provided on a lower surface portion thereof and an upper substrate 20 provided on an upper surface portion thereof are arranged to face each other, and a display unit 30 is provided between the lower substrate 10 and the upper substrate 20. The AA ′ line indicates a line parallel to the horizontal direction (the left-right direction in FIG. 2) of the image display device 1, and the BB ′ line indicates a line parallel to the vertical direction (the vertical direction in FIG. 2). Indicates. As shown in FIG. 1, a temperature sensor 81 and an operation button 95, which will be described later, are disposed on the surface of the display panel 2 of the image display device 1 on which the display surface is disposed.

  As shown in FIGS. 3 and 4, the lower substrate 10 includes a lower electrode 12 that generates an electric field in the display unit 30, and a lower electrode that is an insulating film formed by applying an insulating material on the upper surface side of the lower electrode 12. A protective film 11 and a housing support part 13 provided on the lower surface side of the lower electrode 12 and supporting the image display device 1 are provided. The lower electrode protective film 11 is formed of a material capable of exhibiting high insulation properties such as a resin film such as polyethylene terephthalate or silica, or an inorganic material such as glass. In the present embodiment, the lower electrode protective film 11 and the housing support portion 13 are plastic substrates (resin films) made of flexible polyethylene terephthalate. The lower electrode 12 includes a plurality of electrodes in which linear electric conductors are arranged in parallel to the horizontal direction (AA ′ line direction) and at a predetermined interval so that a constant voltage is applied. It is the board | substrate which comprises.

  In the upward direction of the lower substrate 10 (the upward direction in FIGS. 3 and 4), the upper substrate 20 is provided facing the lower substrate 10 and at a predetermined interval in parallel. The upper substrate 20 includes an upper electrode 22 that generates an electric field in the display unit 30, an upper electrode protective film 21 that is an insulating film formed by applying an insulating material on the lower surface side of the upper electrode 22, and an upper surface of the upper electrode 22. And a display layer 23 that is provided on the side and is configured by a transparent member and functions as a display screen. The upper electrode protective film 21 is formed of a material that can exhibit high transparency, such as polyimide, polyethylene terephthalate, or glass. The upper electrode 22 includes a plurality of electrodes in which linear electric conductors are arranged in parallel to the vertical direction (B-B ′ line direction) at predetermined intervals so that a constant voltage is applied. And a material that can exhibit high transparency. In the present embodiment, the upper electrode protective film 21 is a plastic substrate (resin film) made of polyethylene terephthalate. The upper electrode 22 is a transparent electrode formed of indium tin oxide (ITO), and the display layer 23 is a glass substrate. That is, since the upper substrate 20 is a transparent body, it functions as a display substrate that allows the user to visually recognize the display unit 30 from above the upper substrate 20 (upward in FIG. 2).

  Next, the display unit 30 will be described. A gap formed by the lower substrate 10 and the upper substrate 20 that are provided to face each other and the spacer 31 is the display unit 30. The spacer 31 is installed in a gap between the lower substrate 10 and the upper substrate 20, and the gap is equally divided into a lattice shape to form a plurality of small compartment cells, and supports the lower substrate 10 and the upper substrate 20. The spacer 31 is a flexible member configured as a plate-like member in which a plurality of through holes are formed in a lattice shape, and may be formed of a synthetic resin such as polyimide or polyethylene terephthalate.

  The display unit 30 is filled with charged particles 33 a and 33 b and a dispersion medium 34. The charged particles 33a and 33b are made of a material that can be charged in the dispersion medium 34, and are made of a pigment or dye made of an organic compound or an inorganic compound, or a pigment or dye wrapped with a synthetic resin. In the present embodiment, the charged particles 33a are a mixture of styrene resin and titanium dioxide, and have an average particle diameter of 5 μm (7 wt%), and the amount of titanium dioxide in the particles is 40 wt%. The charged particles 33b are a mixture of styrene resin and carbon black and have an average particle size of 5 μm (10 wt%), and the amount of carbon black in the particles is 30 wt%. Therefore, the charged particles 33a have a white color tone, and the charged particles 33b have a black color tone. The charged particles 33a and the charged particles 33b are charged so as to be different from each other positively or negatively. Here, it is assumed that the charged particles 33a are negatively charged and the charged particles 33b are positively charged.

  On the other hand, as the dispersion medium 34, alcohols, hydrocarbons, silicone oil, etc. that can exhibit high insulation properties and have low viscosity can be used. In the present embodiment, Isopar (73 wt%) manufactured by ExxonMobil, which is a paraffinic solvent, is used. Note that ethanol (10 wt%) is added to the dispersion medium 34 as an additive.

  Further, on the upper surface of the upper substrate 20 (the surface that does not face the lower substrate 10), the mask portion 40 for concealing the peripheral portion of the display portion 30 where there is no small partition cell from the front view so that the user cannot see it. Is provided. The mask part 40 is a square-shaped plate-like member provided with a constant width along the four sides of the upper substrate 20 and provided with a through-hole so that the user can visually recognize the display part 30. Polyethylene terephthalate What is necessary is just to form in the ink layer printed on the surface of the display layer 23, or the thing which colored synthetic resin, such as these, is adhere | attached. When the image display device 1 (display panel 2) is viewed from above, the display unit 30 can be viewed from the through-hole provided in the mask unit 40.

  Next, voltage application control during the refresh operation and the image forming operation will be described with reference to FIG. FIG. 5 shows the voltage V1 applied to the upper electrode 12 during the refresh operation and the image forming operation, the voltage V2 applied to the lower electrode 22 during the refresh operation and the image forming operation, and the refresh operation and the image formation. It is explanatory drawing explaining an example of the potential difference V1-V2 which generate | occur | produces between the upper electrode 12 and the lower electrode 22 at the time of operation | movement.

  FIG. 5A shows the voltage V1 applied to the upper electrode 12 during the refresh operation and the image forming operation, and FIG. 5B shows the voltage V2 applied to the lower electrode 22 during the refresh operation and the image forming operation. (C) shows the potential difference V1-V2 generated between the upper electrode 12 and the lower electrode 22 during the refresh operation and the image forming operation.

As shown in FIG. 5, during time t _1, after the refresh operation is performed during the time t _2, the image forming operation is performed. In the refresh operation of the present embodiment, a voltage is applied so that white charged particles 33a, black charged particles 33b, white charged particles 33a, black charged particles 33b, and white charged particles 33a are moved in this order to the upper substrate 12 side. Is applied. Further, the black charged particles 33b, the white charged particles 33a, the black charged particles 33b, the white charged particles 33a, and the black charged particles 33b are sequentially moved to the lower substrate 22 side.

  Thus, in the refresh operation of this embodiment, a voltage is applied so that the charged particles 33 are moved five times between the upper substrate 12 and the lower substrate 22.

Single time t _1/5 for applying a voltage to the migration of charged particles 33 is set to be shorter than the time t ₂ in the refresh operation. The time t _1/5, in a state where a gray degradation has occurred, while the potential difference V1-V is even given to between the electrodes, the time charged particles 33 do not adhere to the substrate is set.

  Next, the electrical configuration of the image display device 1 will be described. FIG. 6 is a block diagram showing an electrical configuration of the image display apparatus 1. As shown in FIG. 6, the control board 3 (see FIG. 1) of the image display device 1 includes a CPU 90 that controls the image display device 1, a ROM 91 that stores programs executed by the CPU 90, and the display unit 30. A display control unit 92 for controlling display contents; a RAM 93 for temporarily storing data; a timer 94 for measuring time and inputting to the CPU 90; an operation button 95; a temperature sensor 81; and a memory card insertion / removal sensor 82. A power button 83, a charging connector insertion / removal sensor 84, a USB insertion / removal sensor 85, and a memory card interface 86 as an interface with the memory card 87 are connected via a bus.

  Here, the image display device 1 is provided with a memory card slot (not shown), and the memory card insertion / removal sensor 82 indicates whether or not the memory card 87 storing the image data to be displayed on the display unit 30 is inserted into or removed from the memory card slot. To detect.

  The memory card 87 stores content data composed of a plurality of page unit image data. The display panel 2 displays image data of any page among the content data stored in the memory card 87. The memory card 87 may store a plurality of content data. Then, the CPU 90 executes reading and writing of content data to the memory card 87 inserted into the slot via the memory card interface 86.

  The power button 83 turns the power of the image display device 1 on and off. The charging connector insertion / removal sensor 84 detects whether or not the charging connector of the image display device 1 has been inserted / removed. The USB insertion / removal sensor 85 detects whether or not a USB connector for connecting to a PC has been inserted / removed. The temperature sensor 81 corresponds to the temperature measurement means of the present invention, and the memory card insertion / removal sensor 82, the power button 83, the charging connector insertion / removal sensor 84, the USB insertion / removal sensor 85, and the operation button 95 correspond to the detection means of the present invention.

  The operation button 95 transmits an instruction signal corresponding to the various operations to the CPU 90 when the user performs various operations. For example, as various operations, there are a refresh operation for causing the CPU 90 to execute a refresh operation at an arbitrary timing of the user, a screen rewriting operation for rewriting image data being displayed on the display panel 2, and the like.

  Here, as the screen rewriting operation, a page turning operation for turning the displayed page, a content switching operation for switching the displayed content, a content list screen for displaying a list of content data stored in the memory card 87, There are operations for displaying a predetermined screen such as a setting screen for performing various settings of the image display device 1. When this screen rewriting operation is performed, an image formation request which is an instruction signal for forming an image corresponding to each screen rewriting operation is transmitted to the CPU 90, and the CPU 90 displays the contents of the next image data to be displayed on the display panel 2. In response to this, the above-described image forming operation is executed.

  Further, the RAM 93 stores a weight table storage area 931 that stores a weight table for determining the timing for executing a refresh operation in a screen rewriting process described later, and an image forming operation to the display unit 30 from the previous refresh operation. A count counter storage area 932 that stores a count counter that is a counter that counts the number of times the image sensor has been executed, a temperature storage area 933 that stores the ambient temperature detected by the temperature sensor 81, and the number of executions of the image forming operation and the measured temperature A timing value storage area 934 for storing a timing value that is a value for determining the timing of performing a refresh operation calculated from the above, such as insertion of a memory card, presence / absence of charging, presence / absence of USB connection, etc. A state storage area 935 for storing the state is provided, and other storage areas not shown are provided. There.

  Next, operations performed by the image display apparatus 1 under the above configuration will be described with reference to FIGS. FIG. 7 is a flowchart of the main process of the image display device 1. FIG. 8 is a flowchart of the memory card check process executed in the main process. FIG. 9 is a flowchart of the refresh button check process executed in the main process. FIG. 10 is a flowchart of the charge state check process executed in the main process. FIG. 11 is a flowchart of the USB check process executed in the main process. FIG. 12 is a flowchart of the image formation request check process executed in the main process. FIG. 13 is a flowchart of the screen rewriting process executed in the image formation request check process.

  As shown in FIG. 7, when the power button 83 is pressed to turn on the power, the main process is started. First, initialization processing for resetting the state storage area 935 and the like is executed (S1). Next, a refresh operation is executed (S2). The refresh operation is executed based on a refresh operation control signal by reading refresh data stored in a refresh data memory (not shown) in the RAM 93. That is, a refresh operation control signal is transmitted through a driver (not shown), and a voltage is applied to the lower electrode 12 and the upper electrode 22, and a predetermined electric field is generated in the display panel 2. As a result, the charged particles 33a and 33b in the display unit 30 are evenly dispersed.

  Next, the timing value stored in the timing value storage area 934 and the value of the number counter stored in the number counter storage area 932 are reset (S3). Next, a memory card check process for determining whether or not the memory card 87 is inserted into the memory card slot (not shown) of the image display device 1 is executed (S4). Details of the memory card check process will be described later with reference to FIG.

  Next, a refresh operation check process for checking whether or not a refresh operation has been input by the operation button 95 is executed (S5). Details of the refresh operation check process will be described later with reference to FIG.

  Next, a charge state check process for checking whether or not the charge is completed is executed (S6). Details of the charge state check process will be described later with reference to FIG.

  Next, a USB connection state check process for checking whether the image display apparatus 1 is connected to the PC via the USB is executed (S7). Details of the USB connection state check process will be described later with reference to FIG.

  Next, it is checked whether or not there is an image formation request for forming an image on the display unit 30, and if there is a request, an image formation request check process for executing an image forming operation is executed (S8). Details of the image formation request check process will be described later with reference to FIGS.

  Next, it is determined whether or not the power button 83 is pressed (S9). If the power button 83 is pressed (S9: YES), the refresh operation is executed (S10), and the timing value and the number counter are counted. After resetting (S11), the process is terminated and the power is turned off. If the power button has not been pressed (S9: NO), the process returns to S4 and is repeated. In S10, the image before the refresh operation is finally displayed.

  Next, the memory card check process executed in the main process will be described with reference to FIG. First, the state of the previous memory card 87 (whether or not it has been inserted into the slot) is acquired from the state storage area 935 (S41). Next, the current state of the memory card 87 is acquired from the memory card insertion / removal sensor 82 (S42).

  Next, the previous state acquired in S41 and the current state acquired in S42 are compared to determine whether or not a memory card 87 has been inserted (S43). The memory card 87 is inserted only when the previous state is the state where the memory card 87 is not inserted into the slot and the current state is the state where the memory card 87 is inserted into the slot. Since it is predicted that an image forming operation will be required from now on, a refresh operation is executed in order to display a clear image (S44). That is, if the previous memory card 87 is inserted and the current memory card 87 is inserted, if the previous memory card 87 is inserted and the current memory card 87 is not inserted, the previous memory card 87 is inserted. In the three cases where the memory card 87 is not folded and the memory card 87 is not currently inserted, it is not determined that the memory card 87 has been inserted (S43: NO), and the process proceeds to S46 as described later. The current state acquired in step S1 is stored in the state storage area 935, and the process returns to the main process.

  After performing the refresh operation in S44, the timing value stored in the timing value storage area 934 and the value of the number counter stored in the number counter storage area 932 are reset (S45). Then, the process proceeds to S46. In S44, the image before the refresh operation is finally displayed.

  In S43 and S44 described above, the reason for performing the refresh operation only when it is determined that the memory card 87 is inserted from the state where the memory card 87 is not inserted is based on the content data stored in the memory card 87. This is because an image forming operation is expected to be required from now on.

  Next, the refresh operation check process executed in the main process will be described with reference to FIG. First, it is determined whether or not a refresh operation has been input by the operation button 95 (S51). When the refresh operation is input (S51: YES), the refresh operation is executed according to the user's request (S52), and the timing value stored in the timing value storage area 934 and stored in the number counter storage area 932 are stored. The value of the number counter being reset is reset (S53), and the process returns to the main process. If no refresh operation is input (S51: NO), the process directly returns to the main process. In S52, the image before the refresh operation is finally displayed.

  Next, with reference to FIG. 10, the charge state check process executed in the main process will be described. First, the previous charging state (whether charging is in progress) is acquired from the state storage area 935 (S61). Next, the current charging state is acquired from the charging connector insertion / removal sensor 84 (S62).

  Next, the previous state acquired in S61 and the current state acquired in S62 are compared, and it is determined whether or not the charging is completed depending on whether the charging connector is changed from the inserted state to the disconnected state. (S63). When charging is completed (S63: YES), an image forming operation is expected to be requested from now on, so a refresh operation is executed (S64), and the timing value stored in the timing value storage area 934, The value of the number counter stored in the number counter storage area 932 is reset (S65). Then, the process proceeds to S66. In S64, the image before the refresh operation is finally displayed.

  If charging has not ended (S63: NO), the current state acquired in S62 is stored in the state storage area 935 (S66), and the process returns to the main process.

  Next, the USB check process executed in the main process will be described with reference to FIG. First, the previous USB connection state (whether or not it is connected to the USB) is acquired from the state storage area 935 (S71). Next, the current USB connection state is acquired from the USB insertion / removal sensor 85 (S72).

  Next, it is determined whether or not the current USB connection state is being connected (S73). If the USB is connected (S73: YES), the state storage area 935 is referred to (S74), and it is determined whether or not the memory card 87 is currently inserted (S75).

  When the memory card 87 is inserted (S74: YES), a memory card rewriting process for writing or erasing arbitrary content data from the PC to the memory card 87 via the USB and the memory card interface 86 is performed. Start (S76).

  The memory card rewriting process (S76) is not directly related to the present invention and will not be described. However, in this process, the contents stored in the memory card 87 are rewritten based on an instruction from the PC. When the execution of the memory card rewriting process (S76) is completed, the process proceeds to S77 described later. In S76, the contents stored in the memory card 87 can be freely rewritten.

  If it is determined in S73 that the USB is not inserted (S73: NO), the process proceeds to S77 described later. When it is determined in S75 that the memory card 87 is not inserted (S75: NO), the process proceeds to S77 described later.

  Next, the previous state acquired in S71 is compared with the current state acquired in S72, and whether the USB has been disconnected (connection to the PC) depending on whether the state has changed from being inserted into the USB to being disconnected. (S77). If the USB is disconnected (S77: YES), it is expected that an image forming operation will be requested from now on, so a refresh operation is executed (S78), and the timing value stored in the timing value storage area 934 Then, the value of the number counter stored in the number counter storage area 932 is reset (S79). Then, the process proceeds to S80. In S78, the image before the refresh operation is finally displayed.

  If the USB is not disconnected (S77: NO), the current state acquired in S72 is stored in the state storage area 935 (S80), and the process returns to the main process.

  Further, as described above, when it is determined that the USB is disconnected (S77: YES), the refresh operation is executed (S78), and when the USB is disconnected, an image forming operation is requested from now on. Because it is expected. That is, during the execution of the memory card rewriting process with the USB connected, the user does not perform the screen rewriting operation much, and the user disconnects the USB and uses the image display device 1 while carrying it. This is because the screen rewriting operation is often executed.

  Next, the image formation request check process executed in the main process will be described with reference to FIGS. First, it is determined whether or not a screen rewriting operation is input by the operation button 95 (S81). When the screen rewriting operation is input (S81: YES), the screen rewriting process is executed (S82, FIG. 13), and the process returns to the main process. When the screen rewriting operation is not input (S81: NO), the process directly returns to the main process.

  Next, in the screen rewriting process, as shown in FIG. 13, first, the frequency coefficient (Count), temperature coefficient (Temp), and timing value threshold (Thre) are calculated from the weight table stored in the weight table storage area 931. Obtain (S101). Next, the current temperature (current_temp) is acquired from the temperature sensor 81, and the acquired temperature stored in the temperature storage area 933 is stored (S102).

  Next, the value (count) of the number counter stored in the number counter storage area 932 is acquired (S103). Next, the previous timing value (Prev_TimingVal) stored in the timing value storage area 934 is acquired (S104).

Next, a timing value (TimingVal) is calculated using the coefficient acquired in S101 to the value acquired in S102 to S104 (S105). Here, it calculates with the following formula | equation.
TimingVal = Prev_TimingVal + {Temp * current_temp} / {Count * count + 1}
In this case, the timing value (TimingVal) is a value obtained by accumulating the previous timing value (Prev_TimingVal).

  Then, it is determined whether or not the timing value calculated in S105 exceeds the threshold acquired in S101 (TimingVal> Thre is satisfied) (S106). When the threshold value is exceeded (S106: YES), it is determined that it is time to refresh based on the number of image forming operations from the previous refresh operation and the current temperature, and the refresh operation is executed ( S107). Then, the timing value stored in the timing value storage area 934 is reset to 0 (S108). Further, the value of the number counter stored in the number counter storage area 932 is reset to 0 (S109). In S107, the image before the refresh operation is finally displayed.

  Next, an image forming operation is performed on the display unit 30 in response to the image formation request (S111). Here, in this image forming operation, an image corresponding to the above-described screen rewriting operation is written (FIG. 12, S81). For example, if the screen rewriting operation operated in S81 is a page turning operation for turning the displayed page, an image is written based on the image data of the next page stored in the memory card 86, and is being displayed. In the case of a content switching operation for switching the content, an image is written based on image data of another content.

  Since the image forming operation is executed once after the refresh operation (S107), the number counter value stored in the number counter storage area 932 is updated to a value increased by one (S112). Then, the process returns to the image formation request check process.

  If the timing value calculated in S105 does not exceed the threshold (S106: NO), the timing value calculated in S105 is stored in the timing value storage area 934 (S110), and the image formation request is met. An image forming operation on the display unit 30 is executed (S111). Since the image forming operation has been executed, the value of the number counter stored in the number counter storage area 932 is updated to a value increased by 1 (S112). Then, the process returns to the image formation request check process.

  In the above case, according to the timing value calculation method in S105, refreshing is easily performed when the temperature is high on average at the time of each image formation request. Therefore, it is possible to cope with accumulation of gray deterioration due to the high temperature state continuing for a long time.

Further, all the temperatures measured at a predetermined interval from the previous refresh operation may be stored in the temperature storage area 933, and the maximum value (max_temp) among them may be calculated using the following formula.
TimingVal = {Temp * max_temp} + {Count * count}
When the timing value is calculated in this way, the refresh is easily performed if there is a high temperature between the last refresh time and the image formation request time. Therefore, it is possible to cope with gray deterioration due to a temporary rapid temperature rise between the time of the last refresh and the time of image formation request.

Further, all the temperatures measured at a predetermined interval from the previous refresh operation are stored in the temperature storage area 933, and the sum of those temperatures (sum_temp) is used to calculate with the following formula. Good.
TimingVal = {Temp * sum_temp} / {Count * (count + 1)}
When the timing value is calculated in this way, since it is easy to be refreshed between the last refresh time and the current image formation request, when the temperature is high on average at each image formation request, the high temperature state is long. It is possible to cope with accumulation of gray deterioration due to continuous time.

Furthermore, the calculation can be performed by using the value of the temperature sensor when there is an image formation request by the following equation.
TimingVal = {Temp * current_temp} + {Count * count}
When the timing value is calculated in this way, if there is an image formation request when the temperature is high, it is easily refreshed. Therefore, refreshing can be performed at a high frequency when used in a hot place.

  As described above, according to the image display apparatus of the present embodiment, the timing of the refresh operation is determined in consideration of the temperature information in addition to the number of image forming operations since the last refresh operation. To do. Therefore, when gray deterioration occurs in a place with a high temperature, the refresh operation is performed even when the number of image formations up to that point is small. In addition to the number of times and the temperature, the refresh operation is determined at a timing according to a specific operation performed by the user. If the user detects an operation that can be estimated to use the display from now on, a write operation is expected after that operation, so even if the number of times and temperature alone cannot detect that gray deterioration has occurred, perform a refresh operation Can do.

  In the above embodiment, the CPU 90 that executes the image forming operation in S111 of FIG. 13 functions as the image forming means of the present invention. Further, the CPU 90 that executes the refresh operation in S107 in FIG. 13 functions as a refresh control unit. Further, the CPU 90 that increments the value of the number counter in S112 of FIG. 13 functions as the image forming number measuring means of the present invention. Further, the CPU 90 that determines whether or not the timing value exceeds the threshold value in S106 of FIG. 13 functions as the refresh determination unit of the present invention.

  In the above-described embodiment, it has been described that when an image formation request is made in S81 (S81: YES), the temperature is acquired from the temperature sensor 81 in S102. However, the temperature sensor 81 has a predetermined interval (for example, 5 seconds). Temperature), and the temperature stored in the temperature storage area 933 is updated at a predetermined interval (for example, 5 seconds). In S102, the temperature stored in the temperature storage area 933 at that time is The timing value may be calculated as the temperature.

  In the above embodiment, the timing value is calculated once based on the counted number and the temperature measured by the temperature sensor 81, and the refresh operation is performed based on whether the timing value exceeds a predetermined threshold. However, it is also possible to determine whether or not to perform the refresh operation based on the number of times counted and the temperature measured by the temperature sensor 81 as a numerical value. Good. For example, the refresh operation may be determined to be executed when the number of times is a predetermined number and the average temperature measured by the temperature sensor 81 reaches a predetermined temperature.

  In the above embodiment, one temperature sensor 81 is arranged in the image display device 1 (see FIG. 1). However, a plurality of temperature sensors 81 are arranged as shown in FIG. Control may be performed so as to determine whether or not to perform the refresh operation based on the temperature indicating the highest temperature among the plurality of temperatures. FIG. 14 is a perspective view of the image display device 1 provided with a plurality of temperature sensors 81. If controlled in this way, the timing of the refresh operation is determined based on the temperature indicating the highest temperature among the plurality of temperatures measured by the plurality of temperature sensors 81, so that the display is likely to cause gray deterioration due to high temperature. It can cope with gray deterioration of the panel 2 part.

  Moreover, in the said embodiment, although the temperature sensor 81 has been arrange | positioned on the surface by which the display surface of the display panel 2 of the image display apparatus 1 is arrange | positioned, as shown in FIG. 81 may be arranged to measure the temperature of the display panel 2.

  Here, FIG. 15 is a schematic view of a cross section of the image display device 1. As shown in FIG. 15, when a straight line is drawn from the CPU 90 housed in the electrophoresis table device 1 so as to be orthogonal to the display panel 2, a temperature sensor 81 is placed at a position where the display panel 2 and the straight line intersect. If it is arranged, the temperature at a position where heat from the CPU 90 is easily transmitted can be measured, so that it is possible to cope with gray deterioration of the portion of the display panel 2 where gray deterioration is likely to occur due to heat received from the CPU 90. In the example of FIG. 15, the description has been made with the CPU 90, but the same can be said if it is an element (heat generating part) arranged on the control board 3 that generates its own heat.

  If the temperature sensor 81 is arranged at a position far from the operation button 95, the temperature of the display panel 2 can be measured without being affected by the human body temperature.

Also, the time t _1/5 during the refresh operation as was longer than the time t _2, when a potential difference which is generated when the refresh operation smaller than V1-V2, the substrate be performed when gray deteriorated charged A refresh operation in which the particles 33 do not adhere can be realized.

1 is a perspective view of an image display device 1. FIG. 3 is a front view of the display panel 2. FIG. FIG. 3 is a cross-sectional view in the direction of the arrow in the AA ′ line (FIG. 2) of the display panel 2. FIG. 6 is a cross-sectional view in the direction of the arrows along the line BB ′ (FIG. 2) of the display panel 2. The voltage V1 applied to the upper electrode 12 during the refresh operation and the image forming operation, the voltage V2 applied to the lower electrode 22 during the refresh operation and the image forming operation, and the upper voltage during the refresh operation and the image forming operation. It is explanatory drawing explaining an example of the potential difference V1-V2 which generate | occur | produces between the electrode 12 and the lower electrode 22. FIG. 2 is a block diagram illustrating an electrical configuration of the image display device 1. FIG. 3 is a flowchart of main processing of the image display device 1. It is a flowchart of a memory card check process executed in the main process. It is a flowchart of a refresh button check process executed in the main process. It is a flowchart of the charge condition check process performed by the main process. It is a flowchart of the USB check process performed by the main process. It is a flowchart of an image formation request check process executed in the main process. It is a flowchart of the screen rewriting process performed in an image formation request | requirement check process. 1 is a perspective view of an image display device 1 provided with a plurality of temperature sensors 81. FIG. 2 is a schematic view of a cross section of the image display device 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Display panel 3 Control apparatus 10 Lower board 11 Lower electrode protective film 12 Lower electrode 13 Case support part 20 Upper board 21 Upper electrode protective film 22 Upper electrode 23 Display layer 30 Display part 31 Spacer 33a, 33b Charged particle 34 Dispersion medium 40 Mask part 52 RAM
81 Temperature sensor 82 Memory card insertion / removal sensor 83 Power button 84 Charging connector insertion / removal sensor 85 USB insertion / removal sensor 90 CPU
91 ROM
92 Display control unit 93 RAM
94 Timer 95 Operation button 931 Weight table storage area 932 Count counter storage area 933 Temperature storage area 934 Timing value storage area 935 Status storage area

Claims (10)

A first substrate having a first electrode and a second substrate having a second electrode, disposed so as to face each other;
A display unit formed in a gap between the first substrate and the second substrate;
A dispersion medium in which a plurality of charged particles moving according to the direction of an electric field generated between the first electrode and the second electrode are dispersed and filled in the display unit;
A display panel comprising the first and second substrates and the display unit;
An image forming means for performing an image forming operation for generating an electric field with respect to the dispersion medium by applying a voltage to the first electrode and the second electrode when an image formation request is made to the display unit;
In order to uniformly disperse the plurality of charged particles in the dispersion medium before the image forming operation by the image forming means, a voltage is applied to the first electrode and the second electrode, and the direction of the electric field generated An electrophoretic display device comprising: refresh control means for executing a refresh operation for generating an electric field with respect to the dispersion medium while alternately switching at a predetermined timing;
An image forming number counting means for counting the number of times the image forming operation by the image forming means is executed after the refresh operation by the refresh control means;
Temperature measuring means for measuring the ambient temperature at a predetermined timing;
A refresh determination unit that determines whether or not to cause the refresh control unit to perform a refresh operation based on the number of times counted by the image formation number counting unit and the temperature measured by the temperature measurement unit;
An electrophoretic display device comprising:   Whether or not the refresh determination unit performs a refresh operation based on the number of times counted by the image formation number counting unit and the temperature measured by the temperature measurement unit when the image formation request is made. The electrophoretic display device according to claim 1, wherein the electrophoretic display device is determined.   The refresh determination unit is configured to set the number of times counted by the image formation number counting unit and the maximum value of the temperature measured by the temperature measurement unit from the execution of the refresh operation by the refresh control unit to the time of the image formation request. 2. The electrophoretic display device according to claim 1, wherein whether to perform a refresh operation is determined based on the determination.   The refresh determination means is a number counted by the image formation number counting means and an average value of the temperatures measured by the temperature measurement means from the execution of the refresh operation by the refresh control means to the time of the image formation request. 2. The electrophoretic display device according to claim 1, wherein whether to perform a refresh operation is determined based on the determination.   The refresh determination unit is configured to perform the refresh operation when a calculated value calculated based on the number of times counted by the image formation number counting unit and the temperature measured by the temperature measuring unit exceeds a predetermined threshold. 5. The electrophoretic display device according to claim 1, wherein execution is determined.   When the cumulative value of the calculated value calculated based on the number of times counted by the image forming number counting unit and the temperature measured by the temperature measuring unit exceeds a predetermined threshold, The electrophoretic display device according to claim 1, wherein execution of the refresh operation is determined. A detecting means for detecting a predetermined user operation;
The electrophoretic display device according to claim 1, wherein the refresh determination unit determines execution of the refresh operation when an input is detected by the detection unit.   The electrophoretic display device according to claim 1, wherein the temperature measuring unit is a temperature sensor arranged on the same surface as the surface on which the display panel is formed.   The temperature measuring means is a temperature sensor that measures the temperature at a point where the display panel and a straight line connecting the heat generating part in the electrophoretic display device and the display panel are orthogonal to each other. The electrophoretic display device according to claim 1. The temperature measuring means is a plurality of temperature sensors arranged on the display panel,
The refresh determination unit determines whether or not to cause the refresh control unit to perform a refresh operation based on a highest temperature among a plurality of temperatures measured by the plurality of temperature sensors. Item 10. The electrophoretic display device according to any one of Items 1 to 9.

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