JP2013231848A - Image display device and driving method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device that can obtain excellent display characteristics, and a driving method of the image display device.SOLUTION: The image display device comprises: a display part that includes a display electrode, a common electrode facing the display electrode and a display medium disposed between the display electrode and the common electrode and having a spherical particle with a different charging polarity in a different coloring area dispersed, rotates the spherical particle by a potential difference between the display electrode and the common electrode and performs a display of a display area corresponding to the display electrode; and a control unit that applies a pulse to each of the display area and rewrites a display of the display part. A writing period for rewriting the display of the display part is composed of a first to third writing periods. The control unit applies a first pulse in the first period and a second pulse different in a polarity from the first pulse in the second period to a display area displaying one display color and applies to a display area displaying the other display color a third pulse having the same polarity as the second pulse in the second writing period and a fourth pulse having the same polarity as the first pulse in the third period.

Description

  The present invention relates to an image display device and a driving method thereof, and more particularly to an image display device that displays an image using a display medium in which particles having different charging polarities are dispersed in different colored regions and a driving method thereof.

  As a reflective image display device for displaying numerical values and character information on electronic price tags, shelf labels, digital watches, etc., or displaying numerical values and character information on electronic paper used for electronic books, etc., for example, different in different colored areas There is an image display device using a two-color spherical particle (twist ball) having a charging polarity as a display medium. Image display devices using twist balls are widely used in fields such as electronic shelf labels, digital signage, and electronic paper because they have a wider viewing angle and lower power consumption than other display devices, especially liquid crystal display devices. ing.

  Generally, a twist ball used as a display medium of an image display device has a colored hue / white hue (for example, black / white, red / white, etc.) or a colored hue / colored hue (for example, black / red, Blue / red, etc.) having at least two colored regions that are separated into at least two different hues, and the two different hues have different charging polarities. A desired image is displayed by rotating the twist ball by applying a voltage corresponding to two colored regions having different charging polarities of the twist ball. Normally, good display can be performed by adjusting the voltage applied when applying a voltage to the twist ball and the voltage application time (see, for example, Patent Documents 1 and 2).

JP 2011-8271 A JP 2010-49272 A

  However, when an image display device using a twist ball as a display medium performs multi-pixel display such as a 1-minute clock using bistability (memory property) using a multi-channel driver IC, the previous display state Due to this history effect, there is a problem that a good display rewriting cannot be performed by applying only one pulse at the time of writing, and an afterimage is generated. In addition, when a state in which no pulse is applied between the common electrode corresponding to the pixel that holds the display and the display electrode is held, the display color changes even in a short time of about 1 minute due to a change in memory characteristics over time. There is a problem. This is due to the fact that the twisted ball has a dipole moment because the colored regions of the twisted ball are charged with different polarities. That is, because the dipole moment is rotated by electrical interaction with the residual charge accumulated at the substrate interface, and the twist ball itself is also rotated at the same time, so that the display state retention is weakened. Here, “applying a pulse” means “producing a potential difference”.

  It is an object of the present invention to provide an image display device and a driving method thereof that can provide good display characteristics using a twist ball having two colored regions having different charging polarities as a display medium.

  According to an image display device of an embodiment of the present invention, a plurality of display electrodes, a common electrode facing the plurality of display electrodes, and a plurality of display electrodes and the common electrode are arranged and are different. A display medium in which spherical particles having different charged polarities are dispersed in a colored region, and the spherical particles are rotated by a potential difference between the plurality of display electrodes and the common electrode to correspond to the plurality of display electrodes A display section for displaying a plurality of display areas, and applying a pulse between the display electrode and the common electrode corresponding to each of the plurality of display areas to generate the potential difference, And a writing period for rewriting the display of the display unit, the writing period for rewriting the display of the display part having a predetermined time respectively, the first writing period, the second writing period, and the third writing The control unit includes a first write period between the display electrode corresponding to the display area for displaying one display color in the plurality of display areas and the common electrode during the first writing period. The display electrode corresponding to a display area that applies a pulse, applies a second pulse having a polarity different from that of the first pulse in the second period, and displays the other display color in the plurality of display areas And a third pulse having the same polarity as the second pulse in the second writing period, and the same polarity as the first pulse in the third period. A fourth pulse having the following is applied.

  According to the driving method of the image display device in one embodiment of the present invention, the plurality of display electrodes, the common electrode facing the plurality of display electrodes, and the plurality of display electrodes and the common electrode are disposed. And a display medium in which spherical particles having different charging polarities are dispersed in different colored regions, and the plurality of displays are obtained by rotating the spherical particles by a potential difference between the plurality of display electrodes and the common electrode. A display unit for displaying a plurality of display areas corresponding to the electrodes, and applying a pulse between the display electrode corresponding to each of the plurality of display areas and the common electrode to generate the potential difference, An image display device driving method comprising: a control unit that rewrites display on a display unit, wherein each of a first writing period, a second writing period, and a third writing period that has a predetermined time and is continuous The first writing is performed between the display electrode and the common electrode corresponding to the display area displaying one display color in the plurality of display areas in the writing period in which the display of the display unit is rewritten. A first pulse is applied in a period, a second pulse having a polarity different from that of the first pulse is applied in the second period, and a display area displaying the other display color in the plurality of display areas is displayed. The third pulse having the same polarity as the second pulse is applied between the corresponding display electrode and the common electrode in the second writing period, and the first pulse is applied in the third period. Applying the fourth pulse having the same polarity as the first pulse.

  According to the image display device and the driving method thereof of the present invention, it is possible to obtain good display characteristics with improved memory performance by suppressing afterimages during image rewriting.

  In addition, according to the present invention, since an image display device using a twist ball is used, image display using memory characteristics is possible, and application of pulses is not necessary during periods when there is no display rewriting, thereby suppressing power consumption. be able to.

1 is a functional block diagram of an image display device according to an embodiment of the present invention. It is a disassembled perspective view of the display part of the image display apparatus which concerns on one Embodiment of this invention. It is a fragmentary sectional view of the display part of the image display apparatus which concerns on one Embodiment of this invention. (A) It is a figure explaining rotation of a twist ball. (B) It is a figure explaining rotation of a twist ball. (C) It is a figure explaining rotation of a twist ball. FIG. 5 is a layout diagram of an example of display electrodes of a display unit when an image display device using a twist ball as a display medium is mounted as a segment drive type 1-minute clock. (A) It is a figure which shows an example of the waveform of the pulse applied between the common electrode and display electrode of the image display apparatus of this invention. (B) It is a figure which shows an example of the waveform of the pulse applied between the common electrode and display electrode of the image display apparatus of this invention. (A) It is a figure which shows another example of the waveform of the pulse applied between the common electrode and display electrode of the image display apparatus of this invention. (B) It is a figure which shows another example of the waveform of the pulse applied between the common electrode and display electrode of the image display apparatus of this invention. It is a figure which shows the clock display photograph at the time of mounting the image display apparatus of this invention as a 15 segment drive type 1 minute clock. It is a figure which shows the display color of each pixel corresponding to the timepiece display shown in FIG.

  FIG. 1 is a functional block diagram of an image display apparatus according to an embodiment of the present invention. The image display apparatus 100 includes a voltage generation circuit 101, a voltage application control unit 102, a voltage application unit 103, and a display unit 104.

  The voltage generation circuit 101 generates a voltage to be applied to the display unit 104. In one embodiment of the present invention, the voltage generation circuit 101 generates a voltage to be applied to each electrode described later of the display unit 104. For example, any voltage of 0 V or 200 V or less may be generated. Here, the arbitrary voltage of 200 V or less may be a voltage of 40 V to 150 V, and preferably 150 V. However, 40V to 150V is an example, and can be a value that matches the characteristics of the display unit 104.

  The voltage application control unit 102 performs control to apply the voltage generated by the voltage generation circuit 101 to the electrodes of the display unit 104. That is, the voltage applied to the electrodes of the display unit 104 is controlled so that a desired display is displayed on the display unit 104. For example, the voltage applied to each electrode of the display unit 104 is selected from the voltages generated by the voltage generation circuit 101. The result selected by the voltage application control unit 102 is supplied to the voltage application unit 103 as a control signal.

  The voltage application unit 103 applies a voltage generated by the voltage generation circuit 101 to each electrode of the display unit 104 in accordance with a control signal supplied from the voltage application control unit 102. In an embodiment of the present invention, the voltage application unit 103 and the voltage generation circuit 101 may be included in a driving IC.

  The display unit 104 includes an electrode for applying a voltage to the material including the twist ball, and the twist ball is rotated by the voltage applied to the electrode. Since the twist ball has different charging polarities in different colored regions, a desired image display is performed by rotation of the twist ball.

  FIG. 2 is an exploded perspective view of an example of the structure of the display unit 104, and FIG. 3 is a partial cross-sectional view of the display unit 104. As shown in FIG. 2, the display unit 101 includes a common electrode layer 201 including a first film layer 202 and a common electrode 204, a second film layer 206, a twist ball layer 208, a third film layer 212, and a display. A display electrode layer 213 including an electrode 214 and an insulating layer 216, a wiring layer 218, and a fourth film layer 220 are included, and the display portion 104 has a plurality of layer structures. 2 and 3, the same reference numerals are assigned to the same or similar components. In FIG. 3, the description of the first film layer 202, the insulating layer 216, the wiring layer 218, and the fourth film layer 220 is omitted.

  The common electrode layer 201 includes a first film layer 202 and a common electrode 204 disposed on the first film layer 201.

  The first film layer 202 is an insulating film formed of a transparent material. The material of the first film layer 202 is not particularly limited as long as it is a transparent material. For example, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyetherimide, cycloolefin copolymer, epoxy resin, silicone resin, and phenol resin can be used.

  The common electrode 204 is a transparent electrode. As the material of the common electrode 204, for example, a transparent conductive material such as ITO, IZO, SnO2, carbon nanotube, PEDOT / PSS, ZnO: Al, or the like can be used. Further, an electrode may be formed on the common electrode layer 204 in a mesh shape using a conductive material such as Al, Cu, Ag, or carbon on a transparent film. An arbitrary voltage of 0 V or 200 V or less is applied to the common electrode 204 from the voltage application unit 103. Here, as described above, the arbitrary voltage of 200 V or less may be a voltage of 40 V to 150 V, and preferably 150 V.

  The second film layer 206 is a film formed of a transparent material. The second film layer 206 may not have insulating properties, but since the common electrode layer 204 is conductive, the second film layer 206 preferably has insulating properties. The material of the second film layer 206 is not particularly limited as long as it is a transparent material. For example, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyetherimide, cycloolefin copolymer, epoxy resin, silicone resin, and phenol resin can be used. The second film layer 206 is preferably a base material on which a base film material and a sealant film material that can be laminated are laminated. As the base film material, polyimide, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyetherimide, epoxy resin, silicone resin, phenol resin may be used in consideration of heat resistance due to thermocompression bonding at the time of laminating. . As the sealant film material, an unstretched polypropylene film or a biaxially stretched polypropylene film may be used. Moreover, you may use the coating film etc. which consist of materials which have heat-sealing properties, such as a polyurethane, polyacryl, an epoxy resin, and silicone.

  The twist ball layer 208 is formed as an elastomer sheet including a low polarity solvent 209 and a plurality of twist balls 210. Specifically, a plurality of twist balls 210 are dispersed in an elastomer sheet formed using an elastomer material, and then the elastomer sheet is immersed in a low polarity solvent to swell the elastomer sheet with the low polarity solvent. To do. As a result, the twist ball 210 is covered with the low polarity solvent 209, and the twist ball 210 can be rotated.

  Examples of the elastomer material include a thermosetting resin. For example, a silicone resin, a slightly crosslinked acrylic resin, a slightly crosslinked styrene resin, a polyolefin resin, and the like can be used. The low polarity solvent is used after being swelled in the elastomer sheet. As such a low polarity solvent, for example, dimethyl silicone oil, isoparaffinic solvent, linear paraffinic solvent, dodecane, tridecane and the like can be used.

  The twist ball 210 is a substantially spherical body having a diameter of 10 μm to 1000 μm, preferably 50 μm to 150 μm. The twist ball 210 is also a bipolar spherical particle having at least two colored regions colored in at least two different colors, and different colored regions having different charging polarities. For example, it has a positively (+) charged black phase and a negative (−) charged white phase. However, the hue is not limited to the above-described black / white, and for example, a colored hue / white hue (for example, black / white, red / white, etc.) or a colored hue / colored hue (for example, black / red, blue) / Red, etc.).

  The colorant for forming the hue of the twist ball 210 is not particularly limited as long as it is a dye or pigment that is insoluble or uniformly dispersed in a fluid dispersion medium containing a polymerizable resin component described later. Can be used. The amount of colorant used varies depending on the use of the colored particles, and the desired color tone varies. In addition, from the viewpoint of dispersibility in the colored continuous phase described below, in the present invention, It can be suitably and suitably added in the range of 0.1 to 80 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of the total polymerizable resin component which is a polymerization curing component.

  The twist ball 210 can be manufactured by, for example, a microchannel manufacturing method. That is, in the oily or aqueous fluid dispersion medium containing the polymerizable resin component, the polymerizable resin component in the colored continuous phase separated into two colors containing the medium-insoluble colorant is charged with different polarities. The polymerizable monomer is formed and transferred to the first microchannel. Subsequently, this colored continuous phase is sequentially or continuously discharged into an aqueous or oily spherical particle phase flowing in the second microchannel. The discharged material discharged in the spherical particle phase is successively spheroidized in the spherical particle phase while being spherical particles during a series of discharge, dispersion and transfer in the microchannel. The polymerizable resin component in the spheroidized particles is polymerized and cured under ultraviolet irradiation and / or heating to have two colored areas colored in two different colors, and the different colored areas have different charging polarities. A twist ball 210, which is a bipolar two-color spherical particle having the following, is formed.

  As the polymerizable resin component or polymerizable monomer used in the twist ball 210 of the present invention, the chargeability of the twist ball 210 may be negative (−) charge or positive (+) depending on the type of functional group or substituent of the polymerizable monomer. ) Monomer species that tend to exhibit chargeability. Therefore, when using at least two or more kinds of monomers as the polymerizable resin component of the twist ball 210 of the present invention, preferably, in view of the tendency to exhibit (+) and (−) chargeability, A plurality of monomers having the same kind of chargeability tend to be used in combination as appropriate.

  4A to 4C are diagrams for explaining the rotation of the twist ball 210. FIG. 4, the same reference numerals are assigned to the same or similar configurations as the configuration of the display unit 101 described with reference to FIGS. In FIG. 4, the common electrode 204 side is the viewing side. Here, the potential of the common electrode 204 is controlled to the H level or the L level by using a driving IC whose output voltage is a binary level (H level or L level), and at the same time, the potential of the display electrode 214 is set to the L level or By appropriately selecting the H level, a predetermined potential difference is generated between the common electrode 204 and the display electrode 214 to obtain white display or black display. Here, the operation of the twist ball 210 will be described on the assumption that 0 V (L level) or 150 V (H level) is applied to the common electrode 204 and the display electrode 214. The at least two colored regions of the twist ball 210 may be in any charged state as long as they are in different positive and negative charged states.

  The twist ball 210 has a positive (+) charged black phase 210a and a negative (−) charged white phase 210b. However, the hue is not limited to the above-described black / white. The two colored regions of the twist ball 210 may be in any charged state as long as they are different from each other in positive and negative charged states. If the twist ball 210 has a positive (+) charged black phase 210a and a negative (−) charged white phase 210b, a voltage is applied to the common electrode 204 and the display electrode 214 sandwiching the twist ball 208 layer. Then, due to the potential difference generated by this, the positive (+) charged black phase 210a and the negative (−) charged white phase 210b of the twist ball 210 have voltages of opposite polarities to their charged polarities. The twist ball 210 rotates so as to face the applied electrode.

  As shown in FIGS. 4A to 4C, when observing from the common electrode 204 side, 0 V (L level) is applied to the display electrode 214 while 150 V (H level) is applied to the common electrode 204. When applied, as shown in FIG. 4A, the white phase 210b of the twisting ball 210 faces the common electrode 204 and “white” is displayed on the display unit 101. As shown in FIG. 4B, when 150 V (H level) is applied to the display electrode 214 while 0 V (L level) is applied to the common electrode 204, the black phase 210a of the twist ball 210 is common. “Black” is displayed facing the electrode 204. That is, the display on the display unit 101 is rewritten from white display to black display. Further, as shown in FIG. 4C, when 0 V (L level) is applied to the display electrode 214 while 150 V (H level) is applied to the common electrode 204, the white phase of the twist ball 210 is applied. 210b faces the common electrode 204 and “white” is displayed. That is, the display on the display unit 101 is rewritten from black display to white display.

  The third film layer 212 is a film formed of a transparent material, and is formed of the same material as the second film layer 206. However, in the display unit 101, the material of the third film layer 212 and the material of the second film layer 206 are not necessarily the same.

  As shown in FIG. 3, the twist ball layer 208 is sandwiched between the second film layer 206 and the third film layer 212, and the second film layer 206 and the third film layer 212 are laminated. It may be sealed. Further, the twist film layer 208 is placed between the second film layer 206 and the third film layer 212 and the twist ball layer 208 via a sealing material using a thermosetting resin such as an epoxy resin. 206 and the third film layer 212 may be sandwiched.

  The display electrode layer 213 includes an insulating layer 216 and a display electrode 214 disposed on the insulating layer 216. The display electrode 214 may be patterned into a desired shape in order to perform a desired display on the display unit 101, like the display electrodes 214a and 214b shown in FIG.

  The insulating layer 216 is an insulating film, such as polypropylene, polyethylene, polyvinyl chloride, polyvinyl alcohol, polyimide, polyethylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyetherimide, cycloolefin copolymer, epoxy resin. An insulating resin such as a polyimide resin, a phenol resin, or a silicone resin may be used. The insulating resin may be used alone, or two or more kinds of resins may be used in combination. A through electrode (not shown) that electrically connects the display electrode 214 and a wiring layer 218 described later is formed in the insulating layer 216.

  The display electrode 214 is formed by depositing a metal such as Au, Al, Ni, or Cu, ITO, IZO, SnO2, or ZnO on the insulating layer 216 by an inkjet method, a screen printing method, a gravure printing method, a convex printing method, or other printing methods. It is formed by disposing a conductive material such as a transparent conductor such as Al or a mixture of a conductive agent in a solvent or a synthetic resin binder.

  A voltage output from the voltage application unit 103 is applied to the display electrode 214 via a wiring described later. Thereby, a potential difference is generated between the display electrode 214 and the common electrode 204, and when viewed from the direction 222, the portion of the display electrode 214 can be viewed as an image display region. Therefore, the area below the display electrodes 214a and 214b shown in FIG. 3 is a display area (segment).

  The wiring layer 218 is a film in which wiring (not shown) connected to the display electrode 214 via a through electrode (not shown) provided on a film of an insulating resin material or the like is formed. As the insulating resin material, the above-described resin material or the like can be used.

  The fourth film layer 220 is formed of an insulating resin material or the like. As the insulating resin material, the above-described resin material or the like can be used.

  Note that a mask layer is further provided on the common electrode 204 or the display electrode layer 213 is displayed so that the color of the portion other than the display electrode 214 is equivalent to one of the hues of the twist ball 210 when viewed from the direction 222. A background electrode (not shown) may be provided in a portion other than the electrode 214 so that a constant voltage is applied to the common electrode 204.

  FIG. 5 is an arrangement diagram of an example of the display electrode 214 of the display unit 104 when the image display device 100 using a twist ball as a display medium is mounted as a segment drive type 1-minute clock. As shown in FIG. 5, when the image display device 100 using a twist ball as a display medium is mounted as a segment drive type 1-minute clock, the display unit includes display electrodes indicating 1-digit to 10-hour digits, for example. Has been placed. Here, in each digit of 1 minute digit to 10 hour digit, rectangular display electrodes are arranged in a total of seven black areas in an “8” shape as a whole, and the areas other than the display electrode areas are white. This is the background. A background electrode may be arranged in a region other than the display electrode. By controlling the voltage application to the display electrode and / or the background electrode of each digit by the voltage application control unit 102, it is possible to display numbers from 0 to 9. In FIG. 5, a 7-segment display that displays each timer display digit divided into 7 areas is shown. However, each display digit is not limited to 7 areas, and is composed of an arbitrary number of areas such as 15 areas. May be. In FIG. 5, the display area (hereinafter also referred to as a pixel) representing each digit is black and the background is white. However, the present invention is not limited to this.

  In the clock display shown in FIG. 5, the display period of the 1-minute digit is set as one unit time. That is, since the display of the 1-minute digit can change every minute, the unit time for displaying the 1-minute digit is 1 minute. Similarly, 10-minute digit display is 10 times unit time, 10 minutes, 1-hour digit display is 60 times unit time, 1 hour, 10-hour digit display is 600 times unit time, 10 hours. The display changes every time.

  In an image display device using a general twist ball as a display medium, a voltage is applied according to a display rewriting period (hereinafter referred to as a writing period) and a display holding period (hereinafter referred to as a holding period). The holding period is a predetermined period for holding the display on the display unit. Generally, when a display is continuously held beyond a predetermined holding period, the holding period is continuously repeated during the holding period. That is, when the display is continuously held beyond the predetermined holding period, the display holding period is an integral multiple of the predetermined unit time. The writing period is a predetermined period immediately before the holding period, and a predetermined voltage for writing a display on the display portion is applied to the common electrode and the display electrode. Here, in the case of the segment type 1-minute clock, the unit time of the 1-minute digit of the display unit is a display period of 1-minute digit, that is, 1 minute. Of the unit time, a voltage is applied to the common electrode and the display electrode so that a potential difference of a predetermined magnitude is generated between the common electrode and the display electrode in the writing period, and each electrode is used in the remaining holding period. The display is maintained depending on the memory characteristics of the twisting ball without applying a voltage.

  However, as described above, when multi-pixel display such as a 1-minute clock is performed using a multi-channel driver IC by utilizing the memory property, one pulse at the time of writing is caused by the history effect of the previous display state. There is a problem that a good display rewriting cannot be performed only by the application of, and an afterimage is generated. In addition, when the pixel holding the display is held in a state where no pulse is applied, there is a problem that the display color is changed even in a short time of about 1 minute due to a change in memory characteristics with time.

  The inventor of the present application has studied to suppress the occurrence of the above-described problem. As a result, in the writing period, a single pulse is not applied between the common electrode and the display electrode of the display portion, That is, it was conceived that a combination of a positive polarity (+) pulse and a negative polarity (-) pulse and a potential-less difference state was applied, and it was confirmed that an afterimage could be prevented during display rewriting. Further, not only the pixels for which display is rewritten, but also the display of all the pixels in the display unit is conceived to be rewritten by applying a combination of a bipolar pulse and a non-potential difference state every unit time, thereby improving the memory performance. It was confirmed. Hereinafter, the present invention which has been conceived by the present inventor will be described. Hereinafter, “applying a pulse between the common electrode and the display electrode” means “applying a predetermined voltage to the common electrode and the display electrode to cause a potential difference between the common electrode and the display electrode”. It means that.

  In the image display apparatus 100 of the present invention, when a multi-pixel display such as a 1-minute clock is performed using a multi-channel driver IC by utilizing a memory property, a bipolar pulse is used in a writing period in a unit time of 1-minute digit. That is, a combination of a positive polarity (+) pulse and a negative polarity (−) pulse and a non-potential difference state is applied between the common electrode and the display electrode corresponding to all pixels in the display portion.

  6 and 7 show the common electrode 204 when the image display device 100 of the present invention is mounted as a segment drive type 1-minute clock as shown in FIG. 5 and is driven using a binary driver IC. An example of a waveform of a pulse applied between the display electrode 214 is shown. Here, it is assumed that the twist ball has a black phase that is black and positively (+) charged and a white phase that is white and negatively (−) charged.

  FIG. 6A is applied between the common electrode 204 and the display electrode 214 corresponding to a pixel for black writing in a writing period in the next unit time after holding a predetermined display in a predetermined unit time. FIG. 6B is applied between the common electrode 204 and the display electrode 214 corresponding to the pixel for white writing in the same period as the writing period shown in FIG. A pulse waveform is shown. It is preferable that the pulse applied between the common electrode 204 and the display electrode 214 has a pulse width longer than the response time of the twisting ball. Each pulse width may be 200 ms or more and less than 1000 ms, and preferably about 500 ms.

  As shown in FIG. 6A, in a unit time t1 (hereinafter, referred to as “writing period t1”) in a writing period (t1 + t2 + t3), first, an H level (eg, 150 V) and applying a voltage of L level (for example, 0 V) to the display electrode 214, the first pulse having positive polarity (+) between the common electrode 204 and the display electrode 214. Is applied to perform white writing. Next, an L level voltage is applied to the common electrode 204 and an H level voltage is applied to the display electrode 214 in the structural unit time t2 (hereinafter referred to as “writing period t2”) in the writing period (t1 + t2 + t3). Thus, black writing is performed by applying a second pulse having a negative polarity (−) between the common electrode 204 and the display electrode 214. Finally, in the structural unit time t3 (hereinafter referred to as “writing period t3”) in the writing period (t1 + t2 + t3), the common electrode 204 and the display electrode are arranged so that there is no potential difference between the common electrode 204 and the display electrode 214. Appropriate voltage is applied to 214, and thereafter, no voltage is applied to the common electrode 204 and the display electrode 214, and black display is held until the end of the unit time due to memory characteristics. In order to make a potential difference between the common electrode 204 and the display electrode 214, an L level voltage or an H level voltage may be applied to both the common electrode 204 and the display electrode 214. Note that the writing periods t1, t2, and t3 are preferably equal to each other, but may be different.

  In addition, as shown in FIG. 6B, the pixel that performs white writing first displays the common electrode 204 and the display in the writing period t1 in the next unit time after holding the predetermined display in the predetermined unit time. An appropriate voltage is applied to the common electrode 204 and the display electrode 214 so that there is no potential difference between the electrode 214 and the electrode 214. Next, in the writing period t2, by applying an L level voltage to the common electrode 204 and an H level voltage to the display electrode 214, a negative polarity (− ) Is applied to perform black writing. Here, the third pulse may have the same magnitude and the same pulse width as the second pulse shown in FIG. 6A, and may have a different magnitude or a different pulse width. Also good. Finally, in the writing period t3, an H level voltage is applied to the common electrode 204, and an L level voltage is applied to the display electrode 214, whereby positive polarity (+ ) Is applied to perform white writing, and then the white display is held until the end of the unit time due to the memory property. Here, the fourth pulse may have the same magnitude and the same pulse width as the first pulse shown in FIG. 6A, and may have a different magnitude or a different pulse width. Also good.

  7A and 7B show a common electrode 204 and a display electrode corresponding to a pixel for performing black writing or white writing in a writing period in a next unit time after holding a predetermined display in a predetermined unit time. Another example showing a pulse waveform applied between the first and second electrodes is shown. As described above, each pulse width may be 200 ms or more and less than 1000 ms, and preferably about 500 ms.

  As shown in FIG. 7A, in the writing period t1, for the pixel that performs black writing, first, the common electrode 204 and the display electrode 214 are set so that there is no potential difference between the common electrode 204 and the display electrode 214. Apply an appropriate voltage. Next, in the writing period t2, by applying a voltage of H level (for example, 150 V) to the common electrode 204 and applying a voltage of L level (for example, 0 V) to the display electrode 214, the common electrode 204 and the display are displayed. White writing is performed by applying a first pulse having a positive polarity (+) to the electrode 214. Finally, in the writing period t3, an L level voltage is applied to the common electrode 204, and an H level voltage is applied to the display electrode 214, whereby a negative polarity (− ) Is applied to perform black writing, and then black display is held until the end of the unit time due to the memory property.

  Further, as shown in FIG. 7B, for the pixel that performs white writing, first, L is applied to the common electrode 204 in the writing period t1 in the next unit time after holding the predetermined display in the predetermined unit time. A black voltage is applied by applying a third pulse having a negative polarity (−) between the common electrode 204 and the display electrode 214 by applying a level voltage and applying an H level voltage to the display electrode 214. I do. Here, the third pulse may have the same magnitude and the same pulse width as the second pulse shown in FIG. 7A, and may have a different magnitude and a different pulse width. Also good. Next, in the writing period t2, by applying an H level voltage to the common electrode 204 and applying an L level voltage to the display electrode 214, positive polarity (+ ) Is applied to perform white writing. Here, the fourth pulse may have the same magnitude and the same pulse width as the first pulse shown in FIG. 7A, and may have a different magnitude and a different pulse width. Also good. Finally, in the writing period t3, an appropriate voltage is applied to the common electrode 204 and the display electrode 214 so that there is no potential difference between the common electrode 204 and the display electrode 214. Is held until the end of the unit time.

  In the image display device 100 of the present invention, the rewriting of the display by black writing and white writing as shown in FIGS. 6 and 7 is performed on the display unit 104 every unit time of 1 minute digit of the segment drive type 1 minute clock. Perform for all pixels simultaneously. In other words, not only the pixel whose display is rewritten, but also all pixels including the pixel whose display does not change between a predetermined unit time and the next unit time, the display of the pixel representing the one-minute digit is simultaneously displayed. Rewriting is performed.

  Hereinafter, switching of time display when the image display device 100 of the present invention is mounted on a segment drive type 1-minute clock will be specifically described.

  FIG. 8 shows a clock display photograph when the image display apparatus 100 of the present invention is mounted as a 15-segment drive type 1-minute clock. FIG. 9 shows the display color of each pixel corresponding to the clock display shown in FIG. The display unit 104 of the image display apparatus 100 includes pixels M1 to M15 that display 1-minute digits, pixels M16 to M30 that display 10-minute digits, pixels H1 to H15 that display 1-hour digits, and pixels that display 10-hour digits. H16 to H30 and background B are included. 8 and 9, in the 15-segment drive type 1-minute clock, the pixels representing the display of each digit are black and the background is white. However, the present invention is not limited to this. In addition, here, in the writing period in the next unit time after holding the predetermined display in the predetermined unit time, the common electrode 204 and the display electrode 214 corresponding to the pixel that performs black writing and the pixel that performs white writing. In the meantime, the pulses shown in FIGS. 6A and 6B were applied. However, the present invention is not limited to this, and the pulses shown in FIGS. 7A and 7B are provided between the common electrode 204 and the display electrode 214 corresponding to the pixel that performs black writing or the pixel that performs white writing. May be applied. Here, a pulse is also applied between the common electrode 204 and the background electrode provided in a region other than the display electrode 214 so that the background B displays white.

  8 and 9, the image display device 100 mounted as a 15-segment drive type 1-minute clock displays 13:53 and then 13:54. In the image display device 100, when the time display is switched from 13:53 to 13:54, the display color is changed only for the pixels S7, S9, and S10 that display the 1-minute digits, all of which are black. The display color changes to white.

  As shown in FIG. 8, in the writing period t1 in the next unit time immediately after the holding period ts of the previous unit time, first, for the pixel to be black-written, a voltage of H level (for example, 150 V) is applied to the common electrode 204. And a first pulse having a positive polarity (+) is applied between the common electrode 204 and the display electrode 214 by applying a voltage of L level (for example, 0 V) to the display electrode 214. Perform white writing. At the same time, with respect to the pixel for which white writing is performed and the background B, the common electrode 204, the display electrode 214, and the background are arranged such that there is no potential difference between the common electrode 204 and the display electrode 214 and between the common electrode 204 and the background electrode. Appropriate voltage is applied to the electrodes. Accordingly, as shown in FIG. 9, pixels M1 to M6, M8, M12 to M16, M19 to M25, M27 to M30, H1 to H9, H10, and H12 that display black in the next unit period for displaying 13:54. , H15 to H21 are written in white, and the remaining pixels M7, M9 to M11, M17 to M18, M26, H11, H13 to H14, H22 to display white in the next unit period for displaying 13:54. H30 and background B are in the same potential as the display color in the holding period ts of the previous unit time because there is no potential difference between the common electrode 204 and the display electrode 214 and between the common electrode 204 and the background electrode. The display color remains the same.

  Next, in the writing period t2 immediately after the writing period t1, by applying an L level voltage to the common electrode 204 and an H level voltage to the display electrode 214 for the pixel that performs black writing, the common electrode Black writing is performed by applying a second pulse having a negative polarity (−) between the display electrode 204 and the display electrode 214. At the same time, for the pixel that performs white writing and the background B, by applying an L level voltage to the common electrode 204 and applying an H level voltage to the display electrode 214 and the background electrode, the common electrode 204 and the display electrode 214 Black writing is performed by applying a third pulse having a negative polarity (−) between the common electrode 204 and the background electrode. That is, black writing is performed on all the pixels M1 to M30, H1 to H30, and the background B in the display unit 104 of the image display apparatus 100. Therefore, as shown in FIGS. 8 and 9, in the writing period t2, the display unit 104 of the image display apparatus 100 displays black for all pixels and the background B. Here, the second pulse and the third pulse may have the same magnitude and the same pulse width, or may have different magnitudes and different pulse widths.

  Lastly, in the writing period t3 immediately after the writing period t2, the common electrode 204 and the display electrode 214 are appropriately applied so that there is no potential difference between the common electrode 204 and the display electrode 214 with respect to the pixel performing black writing. Apply an appropriate voltage. At the same time, for the pixel that performs white writing and the background B, an H level voltage is applied to the common electrode 204 and an L level voltage is applied to the display electrode 214 and the background electrode. White writing is performed by applying a fourth pulse having positive polarity (+) between the common electrode 204 and the background electrode. Therefore, as shown in FIG. 9, the pixels M1 to M6, M8, M12 to M16, M19 to M25, M27 to M30, H1 to H10, H12, and H15 to H21 that display black are the common electrode 204 and the display electrode 214. The pixels M7, M9, M10 to M11 that display the same display color as the display color in the immediately preceding writing period t2, that is, the black display and display white, White writing is performed on M17 to M18, M26, H11, H13 to H14, H22 to H30, and the background B. After the writing period t3, all the pixels M1 to M30, H1 to H30 and the background B of the display unit 104 hold the display in the writing period t3 until the end of the unit time due to the memory property of the twist ball. Here, the fourth pulse may have the same magnitude and the same pulse width as the first pulse applied to the pixel performing black writing in the writing period t1, and may have a different magnitude and a different pulse. It may have a width.

  In the image display device 100 of the present invention, when a multi-pixel display such as a 1-minute clock is performed using a multi-channel driver IC using a memory property, bipolar pulses, That is, a combination of a positive polarity (+) pulse, a negative polarity (−) pulse, and a non-potential difference state is applied between the common electrode and the display electrode corresponding to all pixels in the display portion. In the writing period for rewriting the display, afterimages can be prevented by applying bipolar pulses having different polarities instead of applying a single pulse. In addition, since the bipolar pulses are continuously applied, the amount of charge accumulated at the layer interface of the image display device 100 can be reduced, and thus the interaction between the charge and the twist ball is reduced. There is an effect that the rotation of the twist ball in the display holding state is suppressed. Further, as is apparent from FIGS. 6A and 6B and FIGS. 7A and 7B, during the period in which the potential difference is 0, the pixels for displaying one display color and the other display color are displayed. For example, when one of the pulses is applied between the common electrode 204 and the display electrode 214 corresponding to the pixel displaying one display color, the other display color is displayed. Since there is a period in which the potential difference between the common electrode 204 corresponding to the pixel and the display electrode 214 is zero, it is possible to suppress accumulation of extra charges at the layer interface of the image display device 100 and the like. And the twist ball are reduced, and the rotation of the twist ball in the display holding state is suppressed.

  In addition, by providing a period in which the background color and the display color of all pixels are the same in the writing period, the memory properties of the previous display are reset, and the memory effect of the display is eliminated, and the next display is displayed with high contrast. And can be stabilized. This is because by making the display colors of all the pixels the same, a display refresh effect is produced, and all the twist balls are aligned in the same direction. Due to the refresh effect of the display, the next display is displayed with high contrast, and the display is stabilized, thereby improving the memory characteristics. There is no change in the memory characteristics over time even during the holding period when the display is not rewritten. It is possible to realize a good display without any change in the above.

  In addition, in the holding period ts excluding the writing period (t1 + t2 + t3), no voltage is applied to the common electrode 204, the display electrode 214, and the background electrode, and the display is held by the memory characteristics of the display. The current consumption of the battery can be reduced, and the battery life can be extended. As shown in FIGS. 8 and 9, when the image display device 100 of the present invention is mounted as a segment drive type 1-minute clock, a clock with a long battery life can be provided, which can contribute to energy saving. . Here, the case where the image display device 100 of the present invention is mounted as a segment drive type 1-minute clock has been described, but the present invention is not limited to this.

  Here, the case where the pulses shown in FIGS. 6A and 6B are applied between the common electrode 204 and the display electrode 214 corresponding to the pixel that performs black writing and the pixel that performs white writing will be described. However, the present invention is not limited to this, and the configuration shown in FIGS. 7A and 7B is provided between the common electrode 204 and the display electrode 214 corresponding to a pixel for black writing or a pixel for white writing. A pulse may be applied. When the pulses shown in FIGS. 7A and 7B are applied between the common electrode 204 and the display electrode 214 corresponding to the pixel for black writing and the pixel for white writing, the image is displayed in the writing period t2. The display unit 104 of the display device 100 displays white for all pixels and the background. Even when the pulses shown in FIGS. 7A and 7B are applied between the common electrode 204 and the display electrode 214 corresponding to the pixel that performs black writing and the pixel that performs white writing, FIG. The effect similar to the case where the pulse shown to (b) is applied can be acquired.

  Further, the background color and the segment display color may be inverted every writing period. For example, in the 15-segment clock display shown in FIGS. 8 and 9, taking the background color as an example, the background color of the first holding period ts and writing period t1 is white, the background color of writing period t2 is black, and writing The background color of the period t3 and the last holding period ts is white. On the other hand, when the background color and the segment display color are reversed every writing period, the background color of the first holding period ts, writing period t1, and writing period t2 is white, the background of the writing period t3 and the last holding period ts. The color becomes black. The display color of the segment is black in the first holding period ts, and is white in the writing period t3 and the last holding period ts.

  By reversing the background color and the segment display color from the background color and the segment display color in the previous display for each writing period, it becomes possible to compensate for memory characteristics and suppress the history effect of the previous display state. . By suppressing the history effect of the previous display state, it is possible to suppress the deterioration of display visibility due to insufficient rewriting, and at the same time, it is possible to further reduce the change in the display color of the segment over time, thereby improving the display visibility. be able to.

(Example)
The inventor of the present application has created a twist ball layer in which spherical two-color particles colored in two colors, black and white, which are positively and negatively charged are dispersed. The twist ball layer is prepared by preparing a plurality of twist balls having a black phase which is black and positively (+) charged and a white phase which is white and negatively charged (−), and having a particle diameter of about 100 μm. The twisted ball was dispersed in a thermosetting silicone resin, applied onto a glass substrate with a coater, heat-treated, and immersed in silicone oil for 24 hours to swell. The inventor of the present application prepared a PET film on which one of the uniform transparent electrodes was formed and a PET film on which the other was formed with an aluminum vapor deposition electrode patterned on a 7-segment display electrode, and the transparent electrode was formed. A twist ball sheet was prepared by sandwiching the twist ball layer between a PET film and a PET film on which an aluminum deposition electrode was formed. A DC voltage (80 V) is applied to the created twist ball sheet for a time longer than the response time of the twist ball of 200 ms between the transparent electrode and the display electrode by a control unit including a power source, a microcomputer, a booster circuit, and a driver IC. To a certain display color (for example, black). Next, a one-minute clock display was performed. In order to rewrite at least the minute digit of the clock, a voltage of 150 V (H level) or 0 V (L level) is selectively applied to the transparent electrode and the display electrode with a pulse width of 500 ms in a writing period of once per minute. Thus, when the first pulse, the second pulse, the third pulse, and the fourth pulse shown in FIGS. 6A and 6B are applied between the transparent electrode and the display electrode, the display is not rewritten. Even in the holding period in which the display is held without applying a pulse between the transparent electrode and the display electrode, the memory performance of the display can be obtained due to the display bistability of the twist ball, The display area such as the 10-minute digit, the 1-hour digit, and the 10-hour digit can be satisfactorily displayed. As a result, a good display with a contrast of about 8 was obtained, and the contrast hardly changed during the holding period. Therefore, a good display without a decrease in contrast was obtained even during the holding period.

  As described above, in an image display device using a twist ball, when a multi-pixel display such as a one-minute clock is performed using a driver IC, a bipolar pulse, that is, a positive electrode is used in a writing period for rewriting the display. By applying a combination of positive (+) and negative (-) pulses and a non-potential difference state between the common electrode corresponding to all pixels and the display electrode, it is possible to prevent afterimages during display rewriting. can do. In addition, by providing a period in which the display colors of all the pixels are the same in the writing period, it is possible to reset the display state until immediately before, eliminate the display history effect, and stabilize the next display. By stabilizing the display, it is possible to improve the memory property, and to realize a good display in which the memory property does not change with time even during the holding period in which display rewriting is not performed and the display color does not change.

  The image display device 100 according to the present invention uses the twist ball as a display medium and uses the memory property, so that the common electrode 204 of the display unit 104 and the display are displayed in the holding period in which the display rewritten in the writing period is held. Since it is not necessary to apply a voltage to the electrode 214 and the background electrode (not shown), power consumption can be reduced. A battery may be used as the power source of the image display apparatus 100 of the present invention. A plurality of batteries may be used, or may be used connected in series or in parallel. When batteries connected in parallel are used as a power source, the image display device 100 can be driven for a long time. Further, the photovoltaic power excited by the light energy around the image display device 100 may be used for part or all of the power consumption of the image display device 100. In this case, a dye-sensitized solar cell, a silicon-based solar cell, or the like may be used as a power source for the image display device 100. The dye-sensitized solar cell and the silicon-based solar cell may be used in combination with a battery as a power source of the image display device 100, or may be used alone. By using a dye-sensitized solar cell, a silicon-based solar cell, or the like as a power source for the image display device 100, the driving cost of the image display device 100 can be reduced.

  In particular, in the holding period other than the writing period, the applied voltage of each display region can be set to 0. Therefore, in the holding period, components of the image display device 100 of the present invention, such as a voltage generation circuit (such as a boost circuit) 101, the voltage application unit (driver IC, etc.) 103, and the voltage application control unit (microcomputer, etc.) 102 are all stopped or put into a low current consumption mode, so that even lower power consumption can be displayed. Long-term display operation is possible by connecting solar cells.

100 image display device 101 voltage generation circuit 102 voltage application control unit 103 voltage application unit 104 display unit 201 common electrode layer 206 second film layer 208 twist ball layer 210 twist ball 212 third film layer 213 display electrode layer 218 wiring layer 220 first 4 film layers

Claims (12)

A plurality of display electrodes, a common electrode facing the plurality of display electrodes, and spherical particles disposed between the plurality of display electrodes and the common electrode and having different charging polarities are dispersed in different colored regions. A display unit, and a display unit configured to display a plurality of display regions corresponding to the plurality of display electrodes by rotating the spherical particles by a potential difference between the plurality of display electrodes and the common electrode;
A controller that rewrites the display of the display unit by applying a pulse between the display electrode corresponding to each of the plurality of display regions and the common electrode to generate the potential difference;
Comprising
The writing period for rewriting the display on the display unit includes a first writing period, a second writing period, and a third writing period, each having a predetermined time.
The controller is
A first pulse is applied in the first writing period between the display electrode corresponding to the display area displaying one display color in the plurality of display areas and the common electrode, and the second period Applying a second pulse having a polarity different from that of the first pulse,
A third electrode having the same polarity as the second pulse in the second writing period between the display electrode corresponding to the display region displaying the other display color in the plurality of display regions and the common electrode. And applying a fourth pulse having the same polarity as the first pulse in the third period. In the third writing period, the potential difference between the display electrode and the common electrode corresponding to the display area displaying the one display color is 0,
2. The image display according to claim 1, wherein in the first writing period, a potential difference between the display electrode corresponding to the display area displaying the other display color and the common electrode is 0. 3. apparatus.   The said 2nd pulse and said 4th pulse have the polarity which determines the display color of each display area of these several display area, The Claim 1 or Claim 2 characterized by the above-mentioned. Image display device.   4. The image display device according to claim 1, wherein display colors of the plurality of display areas are the same in the second writing period. 5.   5. The voltage according to claim 1, wherein no voltage is applied to the plurality of display electrodes and the common electrode corresponding to the plurality of display regions in a period other than the writing period. The image display device according to item.   The image display device according to claim 1, wherein the display is a clock display in which the display is rewritten at regular intervals.   The image display apparatus according to claim 6, wherein the display colors of all the plurality of display areas are inverted at every predetermined time. A plurality of display electrodes, a common electrode facing the plurality of display electrodes, and spherical particles disposed between the plurality of display electrodes and the common electrode and having different charging polarities are dispersed in different colored regions. A display unit, and a display unit configured to display a plurality of display regions corresponding to the plurality of display electrodes by rotating the spherical particles by a potential difference between the plurality of display electrodes and the common electrode;
A controller that rewrites the display of the display unit by applying a pulse between the display electrode corresponding to each of the plurality of display regions and the common electrode to generate the potential difference;
A method of driving an image display device comprising:
Each of the first writing period, the second writing period, and the third writing period, each having a predetermined time, is composed of a writing period for rewriting the display on the display unit.
A first pulse is applied in the first writing period between the display electrode corresponding to the display area displaying one display color in the plurality of display areas and the common electrode, and the second period Applying a second pulse having a polarity different from that of the first pulse,
The second electrode having the same polarity as the second pulse in the second writing period between the display electrode corresponding to the display region displaying the other display color in the plurality of display regions and the common electrode. 3 is applied, and the fourth pulse having the same polarity as the first pulse is applied in the third period.
And a method for driving the image display apparatus. In the third writing period, the potential difference between the display electrode corresponding to the display area displaying the one display color and the common electrode is set to 0,
9. The image display according to claim 8, wherein, in the first writing period, a potential difference between the display electrode and the common electrode corresponding to a display area displaying the other display color is set to zero. Device driving method.   The said 2nd pulse and said 4th pulse have the polarity which determines the display color of each display area of these several display area, The Claim 8 or Claim 9 characterized by the above-mentioned. Driving method of image display apparatus.   11. The image display according to claim 8, wherein no voltage is applied to the plurality of display electrodes and the common electrode corresponding to the plurality of display regions in a period other than the writing period. Device driving method.   The method for driving an image display device according to claim 8, further comprising inverting display colors of all of the plurality of display areas at regular time intervals.