JP2007279583A - Drive unit for image display medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit for an image display medium that can avoid a case wherein although it is decided that a battery has sufficient remaining capacity, display driving ends in failure. <P>SOLUTION: A display device 1 includes an image display medium 20 having memory property and a drive unit 10 which drives the image display medium 20 by the battery 14. The drive unit 10 includes a driving circuit 11b which drives the image display medium 20 for display on the basis of image data, an initializing circuit 11c which initializes the image display medium 20 prior to the display driving by the driving circuit 11b, a control circuit 12 which performs display control, and a battery remaining capacity detecting circuit 15 which detects the remaining battery level 14. The battery remaining capacity detecting circuit 15 detects the remaining battery level by measuring a potential variation rate of a capacitive load (bypass capacitor) 11d during a period wherein the initializing circuit 11c initializes the image display medium 20, and sends an emergency display command Ce or normal display command Cn to the control circuit 12 according to the detection result. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display medium driving apparatus for driving an image display medium having a memory property by a battery.

  As an image display medium (electronic paper) having a memory property that can be rewritten repeatedly, for example, an image display medium using particles (toner) is known.

  In such an image display medium, after the display of the same image is continued for a long time, when the next image is displayed, a dot that is not driven may be generated, causing a display defect. Further, the display contrast may change (decrease) while the display is held for a long time.

  Therefore, prior to image display, initialization is performed so that each pixel has a uniform display density. In this initialization, the black particles and the white particles are forcibly moved between the substrates in the entire image display medium, so that the particles adhering to the substrate are surely separated from the substrate and the particles are sufficiently frictionally charged. It is what you want to do. Thereby, an image can be displayed favorably.

  In general, battery driving in a display device or an information processing device is a commonly used technique including a portable image display medium. Even a large-screen image display medium having a memory property can be driven by a battery, and does not require a power outlet.

  Further, the energy required for rewriting the image contents of the image display medium is smaller than the energy required for image initialization of the drive circuit and the medium. In particular, in order to move charged particles in the space to function as display pixels, initialization is performed for a sufficiently long time to charge the particles.

In view of this, the present applicant discloses in Japanese Patent Application Laid-Open No. H11-228707 a drive device that can apply different voltages by separating a circuit for initialization and a circuit for driving in an image display medium using particles. is doing. According to this configuration, it is possible to perform initialization directly without using a logic circuit that controls display contents in order to initialize an image.
Japanese Patent Laying-Open No. 2005-024833

  However, according to the conventional drive device, when the display content is rewritten using the battery, if the remaining battery level is low, the voltage drop occurs when the drive circuit that performs the display drive is operated, and only the initialization is performed. It may stop.

  In order to remedy this problem, the remaining capacity of the battery is measured and then replaced or charged before it becomes unusable. Conventionally, battery capacity is measured by measuring the battery voltage in no-load condition or by passing a weak current through a high-accuracy voltage detector. However, since the measured voltage is increased even though the remaining capacity of the battery is small, the presence of the remaining battery level is determined depending on the measurement result. For this reason, there is a problem that, after the initialization, when the display driving is started, power cannot be supplied from the battery, and the display device does not operate.

  Accordingly, an object of the present invention is to provide an image display medium driving apparatus capable of avoiding a situation in which display driving cannot be performed while it is determined that the remaining battery level is sufficient.

  In order to achieve the above object, one embodiment of the present invention provides the following image display medium driving device.

[1] In a driving device for driving an image display medium having a memory property by a battery, electric power is supplied from the battery to drive the display of the image display medium, and the battery is charged as electric power is supplied from the battery. Drive means having an element; and battery remaining amount detection means for measuring a potential change rate of the element during power supply from the battery to the drive means and detecting the battery remaining amount based on the potential change rate. An image display medium drive apparatus comprising:

  According to the drive device for the image display medium having the above configuration, the value corresponding to the discharge characteristics of the battery is obtained by detecting the remaining battery level based on the potential change rate of the element charged with the power supplied from the battery. Since it can be measured, the remaining battery level can be detected more accurately than when the voltage is measured.

[2] The battery remaining amount detecting means measures a time from the start of power supply from the battery to the driving means until the element reaches a predetermined potential, and detects the remaining battery capacity based on the time. The apparatus for driving an image display medium according to [1], wherein: According to this configuration, the potential change rate of the element can be accurately measured.

[3] The driving means includes the element, and initializes the image display medium, and writes an image on the image display medium initialized by the initialization circuit based on the image data. The image display medium according to [1], further comprising: a drive circuit, wherein the battery remaining amount detection unit measures the potential change rate during power supply from the battery to the initialization circuit. Drive device. According to this configuration, the potential change rate can be accurately measured by measuring the potential change rate of the element during the power supply to the initialization circuit having a large driving power (power consumption).

[4] The drive means includes an initialization mode for initializing the image display medium, and a writing mode for writing an image on the image display medium initialized by execution of the initialization mode based on the image data. The image display medium according to [1], wherein the battery remaining amount detecting unit measures the potential change rate during power supply from the battery to the driving unit in the initialization mode. Drive device. According to this configuration, the potential change rate can be accurately measured by measuring the potential change rate of the element during power supply in the initialization mode in which the driving power (power consumption) is large.

[5] The image display medium driving device according to [1], wherein the element is a bypass capacitor. By using a bypass capacitor as an element to be charged as an element having charging characteristics, noise can be removed and a driving voltage with little voltage fluctuation can be applied to the image display medium.

[6] The battery remaining amount detection means counts the oscillator signal generating the clock signal and the clock signal of the oscillator with the start of power supply from the battery to the driving means, and the count value is set in advance. A counter that generates an output signal when a value is reached, a reference voltage source that outputs a reference voltage, and a voltage comparator that generates an output signal when the potential of the element exceeds a reference voltage by the reference voltage source; When the counter generates the output signal prior to the voltage comparator, it issues a command to warn of low battery power, and the voltage comparator generates the output signal prior to the counter The image display medium drive device according to [2], further comprising: an information determination circuit that generates a command for causing the image display medium to perform normal display. According to this configuration, if the potential of the element reaches the reference voltage earlier, the remaining battery level is sufficient, and if it reaches the preset count value earlier, it is determined that the remaining battery level is low. can do.

[7] In a driving device for driving an image display medium having a memory property by a battery, electric power is supplied from the battery to drive the display of the image display medium, and the battery is charged as electric power is supplied from the battery. Driving means having an element; and a battery remaining amount detecting means for measuring a potential change rate of the element during power supply from the battery to the driving means, and detecting the remaining battery level based on the potential change rate; An image display medium drive device comprising: control means for controlling the drive means to display a warning on the image display medium when the battery remaining charge detection means detects a low battery charge. According to this configuration, the warning display by the image display medium allows the administrator and the user to visually recognize that the remaining battery level is low. The warning display may be a visible display using an LED or the like in addition to the display by the image display medium. Further, an audible display using a buzzer or the like may be performed.

[8] In a driving device for driving an image display medium having memory characteristics by a battery, power is supplied from the battery to drive display of the image display medium, and the battery is charged as power is supplied from the battery. Driving means having an element; and a battery remaining amount detecting means for measuring a potential change rate of the element during power supply from the battery to the driving means, and detecting the remaining battery level based on the potential change rate; An apparatus for driving an image display medium, comprising: radio wave transmitting means for transmitting a warning signal by radio waves when the remaining battery level detecting means detects a low battery level.
According to this configuration, it is possible to notify a remote manager or user of a low battery warning by transmitting a warning signal by radio waves from the radio wave transmitting means.

[9] The image display medium includes a pair of substrates arranged opposite to each other, and charged particles arranged between the substrates and moving between the substrates in accordance with an applied electric field. The image display medium drive device according to [1]. Since the image display medium that moves the charged particles in the air as described above requires initialization, the image display medium is suitable for a configuration in which the remaining battery level is detected during the initialization period. Note that as the image display medium having a memory property, in addition to the above method, a liquid crystal such as a guest-host liquid crystal, a ferroelectric liquid crystal, or a cholesteric liquid crystal, an electrophoresis method, a twist ball method, or the like can be used.

  According to the present invention, since the remaining battery level is detected based on the potential change rate of the element during the power supply from the battery to the driving means, the display drive cannot be performed while it is determined that the remaining battery level is sufficient. Can be avoided.

[First Embodiment]
(Configuration of display device)
FIG. 1 shows a display device according to a first embodiment of the present invention. The display device 1 includes a drive device 10 that generates a voltage for initialization and data for image display, and an image display medium 20 that is detachably attached to the drive device 10 and has a memory property.

  The driving device 10 stores a power supply circuit 11 that performs initialization drive of the image display medium 20 and display drive using image data, a control circuit 12 that controls the power supply circuit 11 according to a program stored in the program memory 12a, and image data. Including an image memory 13 to be operated, a battery 14 to be a power source, a battery remaining amount detection circuit 15 to detect the remaining amount of the battery 14, an interface for inputting information from a keyboard, an external device (not shown), and various switches Unit 16 and a battery remaining amount detection circuit 15 that determines that the remaining amount of the battery 14 is low, an alarm circuit 17 that is driven by the control circuit 12, and a speaker 18 that is connected to the alarm circuit 17 and emits an alarm sound or the like. And is configured.

  The power supply circuit 11 drives the image display medium 20 based on the changeover switch 11 a that selects one of the drive circuit 11 b and the initialization circuit 11 c in accordance with an instruction from the control circuit 12 and the image data stored in the image memory 13. The driving circuit 11b, the initialization circuit 11c for generating a voltage for initializing the image display medium 20, and a capacitive load (C) (C) as an element having charging characteristics provided in the initialization circuit 11c. For example, a bypass capacitor) 11d is provided.

  The change-over switch 11a is an electronic switch configured using a semiconductor element, IC, or the like, and has a circuit configuration for connecting the drive circuit 11b or the initialization circuit 11c to the image display medium 20 in accordance with a command from the control circuit 12. Have.

  The initialization circuit 11c includes a step-up transformer and a step-up circuit 101 including a DC-DC converter that outputs a high voltage to the secondary winding, and a low-voltage circuit from the battery 14 is connected to the primary winding of the step-up transformer. A rectifier circuit 102 for rectifying and smoothing a high voltage output from the booster circuit 101 to obtain a DC high voltage, and an FET for outputting a rectangular wave voltage (eg, +140 V, −140 V) of a predetermined frequency A rectangular wave voltage generation circuit 103 including a switching element such as the capacitor load 11d connected between the output terminals of the rectangular wave voltage generation circuit 103 and functioning as a bypass capacitor and functioning as a voltage stabilization element and a voltage detection element; It has. Since the initialization circuit 11c needs to generate an output for determining the background color and the same color for the entire screen of the image display medium 20, the power consumption is higher than that of the drive circuit 11b.

  The drive circuit 11b has a configuration similar to that of the initialization circuit 11c. However, the drive circuit 11b does not operate at a single drive frequency like the initialization circuit 11c, but performs writing according to image data read from the image memory 13. The voltage (+ 70V or -70V) is output. Moreover, the same bypass capacitor as the capacitive load 11d is provided.

  The control circuit 12 has an initialization mode and a writing mode. In the initialization mode, the changeover switch 11a is connected to the initialization circuit 11c each time the image display medium 20 is rewritten to operate the initialization circuit 11c. The initialization voltage is applied to the image display medium 20. In the writing mode after initialization, the changeover switch 11a is connected to the driving circuit 11b to operate the driving circuit 11b, and a writing voltage based on image data is applied to each pixel of the image display medium 20 by simple matrix driving. It is comprised so that.

  The control circuit 12 may be configured using an input / output function, a clock function, a power supply monitoring function, and the like provided in an FPGA (Field Programmable Gate Array), a PLD (Programmable Logic Device), etc. that control the image display sequence. it can.

  As the battery 14, for example, a rechargeable secondary battery such as a storage battery or a lithium ion battery is suitable. In FIG. 1, the battery 14 is connected only to the drive circuit 11b and the initialization circuit 11c. However, in FIG. 1, the connection with other circuits is omitted, and the display device 1 is actually configured. The other circuit is also powered by the battery 14.

  The alarm circuit 17 is configured to output sound from the speaker 18 using an alarm sound, a melody, a voice message, or the like. Instead of the sound output, a lighting circuit such as an LED lamp or a character such as a message is displayed on a liquid crystal display or the like. It may be a display circuit, and both audible output and visible display output may be performed simultaneously.

(Configuration of image display medium)
The image display medium 20 includes a display portion composed of a rectangular panel in which a plurality of row electrodes 21 and a plurality of column electrodes 22 are placed so as to be orthogonal to each other. Each row electrode 21 is driven by a row electrode drive circuit 23, Each column electrode 22 is driven by a column electrode drive circuit 24.

(Battery level detection circuit configuration)
FIG. 2 shows a detailed configuration of the battery remaining amount detection circuit. The remaining battery level detection circuit 15 starts counting the clock signal and counts up to a set value (for example, 30 ms) in response to an oscillator 15a that generates a predetermined clock signal and a calculation start command Ca from the control circuit 12. A counter 15b for generating an output signal, a voltage stabilizing circuit (reference voltage source) 15c for generating a desired stabilized power source Vb and a reference voltage Vs using the battery 14 as a power source, and a capacitive load 11d from the voltage stabilizing circuit 15c. A voltage comparator 15d that compares the potential Vc of the capacitive load 11d that rises after voltage application is started with the reference voltage Vs output from the voltage stabilization circuit 15c and generates an output signal when Vc ≧ Vs, Of the output of the voltage comparator 15d and the output of the counter 15b, the emergency display command Ce and the normal display command Cn And an information determination circuit 15e for outputting to the control circuit 12 selects the person.

  FIG. 3 shows a cross section taken along line AA of the image display medium of FIG. The image display medium 20 holds a translucent surface substrate 25, a back substrate 26 disposed so as to face the surface substrate 25, the front substrate 25 and the back substrate 26 so as to face each other, and the substrates 25, 26. The partition member 28 made of a thermosetting resin or the like that partitions the space in the direction parallel to the substrates 25 and 26 to form m × n cells 27 and the color and charging characteristics enclosed in the cells 27 are different. It has two types of particle groups composed of white particles 30A and black particles 30B.

  In this embodiment, one cell 27 corresponds to one pixel. However, the present invention is not limited to this, and a plurality of cells may form one pixel, and one cell includes a plurality of pixels. May be. Further, when the image display medium performs color display using three colors of RGB or CMY as one pixel, one pixel is constituted by three cells.

  The surface substrate 25 includes a plurality of stripe-shaped rows made of a transparent conductive film such as a surface substrate member 25a made of a transparent glass substrate and the like, and transparent indium tin oxide (ITO) formed on the surface substrate member 25a. The electrode 21 and a dielectric film 25b made of polycarbonate or the like that protect the row electrode 21 and stabilize the charging characteristics of the particles 30A and 30B are laminated.

  As the front substrate member 25a, a transparent plastic substrate having transparency, polycarbonate resin, acrylic resin, polyimide resin, polyester resin, or the like can be used in addition to the transparent glass substrate.

  In addition to the ITO, the row electrode 21 has transparency, oxides such as indyllium, tin, and antimony, composite oxides thereof, gold, silver, copper, carbon, nickel, and other single layer films, mixed films, Alternatively, a composite film having a thickness of 100 to 2000 angstroms formed by vapor deposition or sputtering, or an organic conductive material such as polypyrrole or polythiophene can be used.

  The dielectric film 25b is formed of polycarbonate, polyester, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate (PMMA), or copolymer depending on the charging characteristics of the particles 30A and 30B sealed in the cell 27. Nylon, ultraviolet curable acrylic resin, amorphous Teflon (registered trademark), or the like can be used.

  The back substrate 26 is made of a back substrate member 26a made of epoxy resin or the like, a copper or the like formed on the back substrate member 26a, and a plurality of stripe-like column electrodes 22 extending in the lateral direction, and the column electrodes 22 are protected. A dielectric film 26b made of polycarbonate or the like that stabilizes the charging characteristics of the particles 30A and 30B is laminated. As the back substrate member 26a, a substrate similar to the front substrate member 25a of the front substrate 25 may be used. For the dielectric film 26b, a material corresponding to the charging characteristics of the particles 30A and 30B enclosed in the cell 27 can be used, as with the dielectric film 25b of the surface substrate 25.

  In addition to the thermosetting resin, an insulating material such as a thermoplastic resin, an electron beam curable resin, a photocurable resin, or rubber can be used for the partition member 28.

  The white particles 30 </ b> A and the black particles 30 </ b> B are charged with different polarities due to, for example, frictional charging by mutual friction. Here, the white particles 30A are negatively charged, and the black particles 30B are positively charged.

  The white particles 30A are, for example, spherical fine particles of titanium oxide-containing crosslinked polymethyl methacrylate having a volume average particle diameter of 20 μm (manufactured by Sekisui Plastics Co., Ltd., classified as “Techpolymer MBX-20-White”) with 100 parts by weight of isopropyl It is obtained by externally adding 0.1 to 0.5 parts by weight of titania fine powder treated with trimethoxysilane. Silane-treated titania fine powder has the effect of suppressing the chargeability of the particles to a suitable level and keeping the fluidity of the particles at a high level. The addition amount of titania fine powder treated with silane is appropriately adjusted depending on the diameter of the white particles 30A and the diameter of the fine powder.

  As the black particles 30B, for example, spherical fine particles of carbon-containing crosslinked polymethylmethacrylate having a volume average particle diameter of 20 μm (manufactured by Sekisui Plastics Co., Ltd., classified as “Techpolymer MBX-20-Black”) are used.

(Operation of display device)
Next, the operation of the display device 1 will be described with reference to FIGS.

  FIG. 4 shows display contents associated with the determination of the remaining battery level. FIG. 5 shows the potential change of the capacitive load at the start of power supply, where (a) shows the potential change characteristic when the remaining battery level is high, and (b) shows the potential change characteristic when the remaining battery level is low. FIG. 6 is a flowchart showing initialization and image display processing.

  First, after the user turns on the power of the display device 1, the user executes an operation of taking image data from a host device or the like (not shown) via the input unit 16. By this operation, the control circuit 12 takes in the image data from the host device or the like via the input unit 16 and stores this image data in the image memory 13.

  Next, in the initialization mode, the control circuit 12 outputs an instruction to rewrite the image display medium 20 (writing instruction) to the power supply circuit 11 and outputs a command to connect the initialization circuit 11c to the changeover switch 11a. (S101) The initialization of the image display medium 20 by the initialization circuit 11c is started (S102). In initialization, the control circuit 12 controls the initialization circuit 11 c to apply the initialization voltage to the row electrode drive circuit 23 and the column electrode drive circuit 24.

  Since the image display medium 20 uses particles (toner), display driving by image data is performed so as to prevent the generation of particle aggregates and display images without display defects even when repeated display is performed. Prior to initialization, the image display medium 20 is initialized.

  The inventors investigated the voltage state within the period of initialization. As a result, it has been found that the simplest detection method for measuring the power consumption at the time of initialization can be measured by measuring the potential of the capacitive load 11d. That is, when the power consumption is measured by the display device including the image display medium 20, the power consumption of the initialization circuit 11c> the power consumption of the drive circuit 11b> the rewriting power of the image display medium 20 at the normal time. I understood. Therefore, the capacity characteristic of the battery 14 appears remarkably at the time of initialization, which is optimal as a period for detecting the remaining battery level. The inventors have also found that the remaining amount of the battery 14 can be measured as follows.

  When the remaining amount of the battery 14 is sufficient, as shown in FIG. 5A, the potential Vc of the capacitive load 11d reaches the applied voltage Vb by the voltage stabilization circuit 15c in a short time (for example, 5 milliseconds). However, when the remaining amount of the battery 14 is low, as shown in FIG. 5B, it takes a long time, for example, 50 milliseconds to reach the applied voltage Vb. Thus, since the time for the potential Vc of the capacitive load 11d to reach a constant state varies depending on the remaining amount of the battery 14, the remaining amount of the battery 14 can be estimated from the time to reach the constant state.

  Specifically, the comparison value is set to a reference voltage Vs lower than the applied voltage Vb, and the comparison value is compared with the potential Vc of the capacitive load 11d by the voltage comparator 15d, whereby the initialization power is displayed as an image. The remaining battery level can be measured while being supplied to the medium 20.

  For the initialization, the control circuit 12 first outputs a drive start command Ca and a calculation start command Cd to the counter 15b, the oscillator 15a, and the voltage stabilization circuit 15c (S103). The counter 15b starts counting the clock output from the oscillator 15a upon receiving the calculation start command Cd, and generates an output signal when a count number corresponding to a preset reference time (for example, 30 ms) ts is reached. .

  The voltage stabilization circuit 15c starts voltage application to the capacitive load 11d based on the drive start command Ca and charges the capacitive load 11d (S103). At this time, only the initialization circuit 11c is connected to the changeover switch 11a.

  The potential Vc of the capacitive load 11d is monitored by the voltage comparator 15d, and comparison with the reference voltage Vs is performed by the voltage comparator 15d.

  The information determination circuit 15e outputs one of the emergency display command Ce and the normal display command Cn based on whichever of the output signal from the counter 15b and the output signal from the voltage comparator 15d is output first. First, when there is an output signal from the counter 15b prior to the voltage comparator 15d (S104: Yes), the information determination circuit 15e sends an emergency display command Ce to the control circuit 12 (S108). The control circuit 12 controls the changeover switch 11a based on the emergency display command Ce, and connects the drive circuit 11b to the row electrode drive circuit 23 and the column electrode drive circuit 24.

  The control circuit 12 that has received the emergency display command Ce from the battery remaining amount detection circuit 15 reads the image data of the warning mark 61 from the program memory 12a, and displays the display data obtained by combining this image data with the image data from the image memory 13. Then, the driver circuit 11b is operated. As a result, an image including the warning mark 61 as shown in FIG. 4B is displayed on the image display medium 20 to warn the user that the remaining battery level is low (S109). Further, the control circuit 12 drives the alarm circuit 17 and issues a warning through the speaker 18 (S110).

  If there is an output signal from the voltage comparator 15d prior to the counter 15b (S104: No, S105: Yes), the information determination circuit 15e sends a normal display command Cn to the control circuit 12 (S106). The control circuit 12 controls the changeover switch 11a based on the normal display command Cn, and connects the drive circuit 11b to the row electrode drive circuit 23 and the column electrode drive circuit 24. At the same time, the control circuit 12 creates display data based on the image data, operates the drive circuit 11b, and causes the image display medium 20 to perform normal image display as shown in FIG. 4A (S107).

  In the case of this normal image display, the control circuit 12 connects the changeover switch 11a to the drive circuit 11b, controls the drive circuit 11b based on the image data stored in the image memory 13, and performs control via the changeover switch 11a. A DC voltage (for example, +70 V or −70 V) is applied to each pixel of the image display medium 20 as a writing voltage by simple matrix driving to the electrode driving circuit 23 and the column electrode driving circuit 24. As a result, an electric field is formed between the electrodes 25 and 26, the particles 30 </ b> A and 30 </ b> B move according to the direction of the electric field, and an image is displayed on the image display medium 20.

  Even if the application of voltage to the row electrode 21 and the column electrode 22 is stopped, the electrostatic adhesion force between the white particles 30A, the black particles 30B, and the dielectric layers 25b and 26b is maintained, so the particles 30A and 30B. Is held attached to the inner surfaces of the dielectric layers 25b and 26b, and an image is displayed for a long time.

(Effects of the first embodiment)
According to the first embodiment, the following effects are obtained.
(A) By measuring the potential change rate of the capacitive load 11d during the initialization period of the image display medium 20 that consumes the largest amount of power, it can be understood only when the battery 14 is measured alone (measured in a no-load state). The power consumption for rewriting the image display medium 20 that is not present can be investigated. As a result, the remaining battery level can be detected without using a dedicated element or the like, and without always detecting the remaining battery level.
(B) By detecting the remaining battery level during initialization of the image display medium 20, it is not necessary to constantly detect the remaining battery level.
(C) When a secondary battery is used for the battery 14, the residual voltage must be measured by predicting the ambient temperature and a rapid voltage drop. However, the battery replacement timing can be accurately grasped by the configuration (a). Battery replacement can be performed efficiently. Therefore, the image display medium 20 and the management system that require simultaneous broadcast are particularly effective.
(D) The battery remaining amount detection circuit 15 does not need a highly accurate circuit configuration because it only needs a circuit configuration for time measurement and voltage comparison.

[Second Embodiment]
FIG. 7 shows a display device according to the second embodiment of the present invention. In the present embodiment, a radio wave transmission circuit 19 and an antenna 19a are provided in place of the alarm circuit 17 and the speaker 18 in the first embodiment, and other configurations are the same as those of the first embodiment. It is. As a communication system of the radio wave transmission circuit 19, there are a mobile phone, Bluetooth (registered trademark), a wireless LAN, a communication system of a unique format, and the like.

  FIG. 8 is a flowchart illustrating the initialization and image display processing of the display device according to the second embodiment. In FIG. 8, the same reference numerals are used for the steps for performing the same processing as in FIG. Hereinafter, the operation in this embodiment will be described with reference to FIGS.

  Also in the present embodiment, after the display device 1 is turned on, image data is captured from a host device (not shown) or the like via the input unit 16 and stored in the image memory 13.

  Next, an instruction to rewrite the image display medium 20 is output from the control circuit 12 to the power supply circuit 11, and a command to connect the changeover switch 11a to the initialization circuit 11c is output (S101). Initialization of the display medium 20 is started (S102).

  Further, the control circuit 12 outputs a drive start command Ca and a calculation start command Cd to the counter 15b, the oscillator 15a, and the voltage stabilization circuit 15c together with an instruction to rewrite (S103). The counter 15b starts counting the clock output from the oscillator 15a upon receiving the calculation start command Cd, and generates an output signal when it reaches a preset count number (for example, equivalent to 30 milliseconds).

  The voltage stabilization circuit 15c applies the power source Vb to the capacitive load 11d based on the drive start command Ca and starts charging the capacitive load 11d (S103). At this time, only the initialization circuit 11c is connected to the changeover switch 11a.

  The potential Vc of the capacitive load 11d rises with time, and finally becomes equal to the output voltage Vb of the voltage stabilization circuit 15c. However, the potential Vc is monitored by the voltage comparator 15d, and the reference voltage Vs Is compared by the voltage comparator 15d.

  The information determination circuit 15e outputs one of the emergency display command Ce and the normal display command Cn based on whichever of the output signal from the counter 15b and the output signal from the voltage comparator 15d is output first. First, when there is an output signal from the counter 15b prior to the voltage comparator 15d (S104: Yes), the information determination circuit 15e sends an emergency display command Ce to the control circuit 12 (S108). The control circuit 12 controls the changeover switch 11a based on the emergency display command Ce, and connects the drive circuit 11b to the row electrode drive circuit 23 and the column electrode drive circuit 24.

  The control circuit 12 that has received the emergency display command Ce reads the image data of the warning mark 61 from the program memory 12a, creates display data by combining this image data with the image data from the image memory 13, and causes the drive circuit 11b to operate. Make it work. As a result, an image including the warning mark 61 as shown in FIG. 4B is displayed on the image display medium 20 to warn the user that the remaining battery level is low (S109). In addition, the control circuit 12 drives the radio wave transmission circuit 19 and transmits a warning by radio waves from the antenna 19a (S210) to warn the remote manager and user that the remaining battery level is low.

  If there is an output signal from the voltage comparator 15d prior to the counter 15b (S104: No, S105: Yes), the information determination circuit 15e sends a normal display command Cn to the control circuit 12 (S106). The control circuit 12 controls the changeover switch 11a based on the normal display command Cn, and connects the drive circuit 11b to the row electrode drive circuit 23 and the column electrode drive circuit 24. At the same time, the control circuit 12 creates display data based on the image data, operates the drive circuit 11b, and causes the image display medium 20 to perform normal image display as shown in FIG. 4A (S107).

(Effect of the second embodiment)
According to the second embodiment, the following effects are obtained.
(B) Since the battery remaining amount warning can be reported to a remote place by radio waves, the user or administrator does not need to stand by in the vicinity of the display device 1.
(B) Since the driving power of the radio wave transmission circuit 19 can be small, it can be configured to consume almost no power.
Other effects are the same as those of the first embodiment.

  In the second embodiment, the alarm circuit 17 and the speaker 18 described in the first embodiment can be further provided.

[Third Embodiment]
FIG. 9 shows a display device according to the third embodiment of the present invention. In the present embodiment, the drive circuit 11b and the initialization circuit 11c of the power supply circuit 11 are configured by a single circuit in the first embodiment. Since the operation of this embodiment is the same as that of the first embodiment, description thereof is omitted.

  The power supply circuit 11 of the present embodiment is similar to the power supply circuit 11 of the first embodiment. The initialization circuit 11c includes a step-up transformer and a low-voltage circuit from the battery 14 in the primary winding of the step-up transformer. A booster circuit 101 composed of a DC-DC converter that is connected and outputs a high voltage to the secondary winding; a rectifier circuit 102 that rectifies and smoothes the high voltage output from the booster circuit 101 to obtain a DC high voltage; and an FET A rectangular wave voltage generating circuit 103 including a switching element, a rectangular wave voltage generating circuit 103, and a voltage stabilizing element and a voltage detecting element that are connected between the output terminals of the rectangular wave voltage generating circuit 103 and function as a bypass capacitor And a discharge circuit 104 for discharging the charge accumulated in the capacitive load 11d at the time of initialization.

  The discharge circuit 104 discharges the electric charge of the capacitive load 11d because the write voltage becomes lower than the initialization voltage, so that the power supply circuit 11 can operate without any trouble. For example, a switch such as a relay or a transistor A current limiting resistor is connected in series. The discharge circuit 104 is turned on by the control circuit 12 when a normal display operation is performed after the initialization is completed. The on-time is set to a switch operation time in which the potential of the capacitive load 11d becomes equal to or lower than the write voltage, and the switch is turned off after the set time has elapsed. Note that when the initialization voltage and the write voltage are the same, the discharge circuit 104 can be omitted.

  The rectangular wave voltage generation circuit 103 is driven in the initialization mode and the drive mode under the control of the control circuit 12. In the initialization mode, the output of the rectifier circuit 102 is used as a power source and a rectangular wave voltage (for example, + 140V) of a predetermined frequency is used. , −140V) is output, and in the write mode, a DC voltage (for example, + 70V or −70V) write voltage is output using the output of the rectifier circuit 102 as a power source.

  The battery remaining amount detection circuit 15 detects the remaining amount of the battery 14 in the initialization mode as in the first embodiment, and controls the emergency display command Ce and the normal display command Cn according to the detection result. 12 is output.

  According to the third embodiment, the remaining battery level can be accurately detected by measuring the potential change rate of the capacitive load 11d during the execution of the initialization mode. Further, since the initialization circuit and the drive circuit are configured using a common circuit, the circuit can be simplified.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, the combination of the components between the embodiments can be arbitrarily performed.

  In each of the above embodiments, the warning mark 61 may be any mark or display as long as it can be authorized by the administrator. A method in which the subject who views the image display medium 20 cannot recognize may be used.

  In the first and second embodiments, the capacitive load 11d is the one provided in the initialization circuit 11c, but the capacitive load provided in another circuit, for example, the drive circuit 11b, For example, it may be configured to measure the voltage of the bypass capacitor.

  Further, the capacity load 11d may be provided exclusively for the remaining battery capacity without being shared with other functions.

  In addition to the configuration using a transformer, the booster circuit 101 can also use a non-insulated DC-DC converter that does not use a transformer. Such DC-DC converters include a charge pump system, a boost chopper system, and the like.

1 is a block diagram showing a display device according to a first embodiment of the present invention. It is a block diagram which shows the detailed structure of the battery remaining charge detection circuit of FIG. It is sectional drawing which shows the cross section of the AA line of the image display medium of FIG. The display content accompanying determination of a battery remaining charge is shown, (a) is a screen figure at the time of normal display, (b) at the time of warning display. The potential change of the capacitive load at the start of power supply is shown. (A) is the potential change characteristic when the remaining battery level is high, and (b) is the potential change characteristic when the battery level is low. It is a flowchart which shows the process of initialization of the display apparatus and image display which concern on 1st Embodiment. It is a block diagram which shows the display apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the initialization of the display apparatus and image display process which concern on 2nd Embodiment. It is a block diagram which shows the display apparatus which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 10 Drive apparatus 11 Power supply circuit 11a Changeover switch 11b Drive circuit 11c Initialization circuit 11d Capacity load 12 Control circuit 12a Program memory 13 Image memory 14 Battery 15 Battery remaining charge detection circuit 15a Oscillator 15b Counter 15c Voltage stabilization circuit 15d Voltage Comparator 15e Information determination circuit 16 Input unit 17 Alarm circuit 18 Speaker 19 Radio wave transmission circuit 19a Antenna 20 Image display medium 21 Row electrode 22 Column electrode 23 Row electrode drive circuit 24 Column electrode drive circuit 25 Surface substrate 25a Surface substrate member 25b Dielectric Film 26 Back substrate 26a Back substrate member 26b Dielectric film 27 Cell 28 Partition member 30A White particle 30B Black particle 60 Display image 61 Warning mark 101 Booster circuit 102 Rectifier circuit 103 Rectangular wave voltage generator circuit 104 Discharge circuit

Claims (9)

In a drive device for driving an image display medium having a memory property by a battery,
Driving means having power supplied from the battery to perform display driving of the image display medium and having an element to be charged in accordance with the power supply from the battery;
And a battery remaining amount detecting unit that measures a potential change rate of the element during power supply from the battery to the driving unit and detects the remaining battery level based on the potential change rate. Drive device for image display medium.   The battery remaining amount detecting means measures a time from the start of power supply from the battery to the driving means until the element reaches a predetermined potential, and detects the battery remaining amount based on the time. 2. The image display medium driving device according to claim 1, wherein The drive means includes the element, an initialization circuit that initializes the image display medium, and a drive circuit that writes an image on the image display medium initialized by the initialization circuit based on the image data. With
2. The image display medium driving device according to claim 1, wherein the battery remaining amount detecting unit measures the potential change rate during power supply from the battery to the initialization circuit. 3. The drive means includes an initialization mode for initializing the image display medium, and a writing mode for writing an image on the image display medium initialized by execution of the initialization mode based on the image data,
2. The image display medium driving device according to claim 1, wherein the battery remaining amount detecting unit measures the potential change rate during power supply from the battery to the driving unit in the initialization mode.   The image display medium driving apparatus according to claim 1, wherein the element is a bypass capacitor.   The battery remaining amount detecting means counts an oscillator that generates a clock signal and the clock signal of the oscillator as power supply from the battery to the driving means starts, and the count value reaches a preset count value. A counter that generates an output signal when the reference voltage is generated, a reference voltage source that outputs a reference voltage, a voltage comparator that generates an output signal when the potential of the element exceeds a reference voltage by the reference voltage source, and the counter When the output signal is generated prior to the voltage comparator, a command to warn of a low battery level is generated, and when the voltage comparator generates the output signal prior to the counter, The image display medium driving device according to claim 2, further comprising an information determination circuit that generates a command for causing the image display medium to perform normal display. In a drive device for driving an image display medium having a memory property by a battery,
Driving means having power supplied from the battery to perform display driving of the image display medium and having an element to be charged in accordance with the power supply from the battery;
A battery remaining amount detecting unit that measures a potential change rate of the element during power supply from the battery to the driving unit, and detects the remaining battery level based on the potential change rate;
An image display medium drive device comprising: control means for controlling the drive means to display a warning on the image display medium when the battery remaining charge detection means detects a low battery charge. In a drive device for driving an image display medium having a memory property by a battery,
Driving means having power supplied from the battery to perform display driving of the image display medium and having an element to be charged in accordance with the power supply from the battery;
A battery remaining amount detecting unit that measures a potential change rate of the element during power supply from the battery to the driving unit, and detects the remaining battery level based on the potential change rate;
An apparatus for driving an image display medium, comprising: radio wave transmitting means for transmitting a warning signal by radio waves when the remaining battery level detecting means detects a low battery level.   2. The image display medium according to claim 1, further comprising: a pair of substrates disposed opposite to each other, and charged particles disposed between the substrates and moving between the substrates in response to an applied electric field. The drive device of the image display medium described.

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