JP2010020213A - Electrophoretic display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display, which achieves a live-action display effect having movement produced using a gradation change of display even in a still image, by dynamically changing the gradation of the display. <P>SOLUTION: The electrophoretic display includes: charging particles enclosed between a pair of substrates having electrodes on surfaces opposite to each other; a display panel having a memory property that performs the display by movement of the charging particles; a driving means which receives input of display data to output a driving voltage waveform to the electrodes, wherein the driving voltage waveform is composed of a driving pulse array formed by combining a plurality of display inversion pulses B11 to B14 and a plurality of pause pulses C11 to C13, and the display inversion pulses have pulse widths smaller than those of the pause pulses. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a low power consumption display device including a display panel having a memory property for performing display by movement of charged particles.

  Conventionally, as thin display devices, liquid crystal display devices have been widely used in various electronic devices, and in recent years, they have also been used as large color displays such as computers and televisions. Plasma displays are also used as large color displays for televisions. However, although liquid crystal display devices and plasma displays are much thinner than CRT display devices, they are still not thin enough for some applications and cannot be bent. Moreover, when using as a display of a portable device, further reduction of power consumption is desired.

  Therefore, as a display device that realizes further thinning and low power consumption, a display panel called an electronic paper using an electrophoretic display element has been developed. An electronic book, an electronic newspaper, an electronic advertisement signboard, and a guidance display board are developed. Attempts have been made to use it. A display panel using this electrophoretic display element is provided with an image display layer in which charged particles are sealed between a pair of substrates each having an electrode on an opposing surface, and a voltage applied between the electrodes of the pair of substrates. Depending on the polarity, the charged particles move by electrophoresis and display is performed.

  This electrophoretic display panel has a memory property because charged particles do not move even if the drive voltage applied between the electrodes is removed, and can maintain a display state even when the drive power is zero. The display period in which this display state is maintained may last from several seconds to several hours or months. For this reason, this electrophoretic display panel can be driven with very little electric power, and thus is promising as a display device for portable devices that require low power consumption.

  An electrophoretic display device capable of performing matrix driving and performing gradation display using this electrophoretic display element is disclosed (for example, see Patent Document 1). The principle of gradation display by the conventional display device disclosed in Patent Document 1 will be described with reference to the drawings. Here, FIGS. 12A and 12B are cross-sectional views showing a simplified structure of the divided cells of the electrophoretic display panel disclosed in Patent Document 1. FIG.

  In FIG. 12A, a conventional electrophoretic display panel 100 has a common electrode 101 and a device electrode 102 facing each other for each divided cell, and has a black dispersion medium 103 between them. The electrophoretic particles 104 are dispersed in the medium 103. The electrophoretic particles 104 are white particles made of titanium oxide, and are positively charged. Here, when a positive voltage is applied to the common electrode 101 and a negative voltage is applied to the element electrode 102, the electrophoretic particles 104 charged with a positive charge are attracted to the element electrode 102. At this time, since the incident light A from the viewing side is absorbed by the black dispersion medium 103, the cell display is black.

  Next, in FIG. 12B, when the applied voltage is switched and a negative voltage is applied to the common electrode 101 and a positive voltage is applied to the element electrode 102, the electrophoretic particles 104 move to the common electrode 101 side by Coulomb force. When the application of voltage is stopped after a certain time, the Coulomb force stops working, and thus the electrophoretic particles 104 are stopped by the viscous resistance of the dispersion medium 103. Here, the moving distance of the electrophoretic particles 104 is determined according to the voltage applied to the common electrode 101 and the device electrode 102 and the application time.

  If the applied voltage is made constant, the position of the electrophoretic particles 104 can be controlled in the thickness direction by adjusting the application time. Here, incident light A from the common electrode 101 side is reflected by the electrophoretic particles 104, and this reflected light passes through the common electrode 101 and reaches the eyes of an observer positioned on the viewing side. Thereby, the observer can recognize the intensity of the reflected light (gradation display) according to the position of the electrophoretic particle 104 in the thickness direction.

  That is, if the applied voltage is made constant, the position of the electrophoretic particles 104 in the thickness direction is determined according to the application time. Key display can be obtained. In FIG. 12B, a negative voltage is applied to the common electrode 101 and a positive voltage is applied to the device electrode 102 for a predetermined time, and the electrophoretic particles 104 are stopped near the middle of the two electrodes. This is an example in which tonal gradation display is realized.

  Next, FIG. 13 is a timing chart for explaining gradation display writing of the electrophoretic display panel disclosed in Patent Document 1. In this conventional electrophoretic display panel, writing is performed for each cell, and writing is performed for each cell every horizontal scanning period Th. Here, the scanning signal Y1 becomes logic “1” in the horizontal scanning period Th, a specific cell is selected, and the drive signal X1 has an active period Tv and a non-biased period Tb in the horizontal scanning period Th. Yes. The active period Tv is a period in which a positive voltage + V (or a negative voltage −V) is applied as the drive signal X1 to the element electrode 102 shown in FIGS. 12A and 12B, and a non-bias period Tb is a period during which 0 V having the same potential as that of the common electrode 101 is applied to the element electrode 102.

  The luminance I1 is the ratio of reflected light viewed from the viewing side. As shown in FIG. 12A, a negative voltage is applied to the device electrode 102, and the electrophoretic particles 104 are attracted to the device electrode 102, and almost all The state in which the incident light A is absorbed by the dispersion medium 103 is set to 0% luminance, and a positive voltage is applied to the element electrode 102 so that the electrophoretic particles 104 are attracted to the common electrode 101. A state where most of the light is reflected is defined as 100% luminance.

  Here, when the horizontal scanning period Th starts with the luminance I1 being 0% and the drive signal X1 of the positive voltage + V is applied to the element electrode 102, the electrophoretic particles 104 attracted to the element electrode 102 are The movement in the direction of the common electrode 101 starts, and the luminance I1 begins to increase. Here, if the active period Tv of the drive signal X1 ends at Tv1 (indicated by a broken line) where the position of the electrophoretic particle 104 is near the middle of both electrodes and returns to 0 V, the electrophoretic particle 104 is in the middle of both electrodes. Stop nearby. Since the electrophoretic particles 104 are held at their positions by the viscous resistance of the dispersion medium 103, the luminance I1 is maintained at about 50%.

  Further, if the active period Tv of the drive signal X1 continues until Tv2 (indicated by a solid line) where the electrophoretic particles 104 move to the common electrode 101, the electrophoretic particles 104 move to the common electrode 101, and the dispersion medium 103 Since the position is held by the viscous resistance, the luminance is held at about 100%. Thus, Patent Document 1 discloses an electrophoretic display device that enables gradation display by setting a voltage application time according to gradation.

Japanese Patent No. 3750565 (7th, 11th page, 4th and 13th figures)

However, the gray scale display of the electrophoretic display panel is a general still image gray scale display technique. For example, the same display is gradually blackened (darkened) or gradually whitened (lightened). When displaying a variety of displays, it is difficult to control the pulse width, and the drive circuit for controlling the voltage applied to the electrophoretic display panel has become complicated.

  An object of the present invention is to provide an electrophoretic display device that solves the above-described problems and has an animation-like display effect that moves even when the image is a still image by dynamically changing the density of the display even if the image is a still image. It is.

  In order to solve the above problems, the electrophoretic display device of the present invention employs the following configuration.

  In the electrophoretic display device of the present invention, a charged particle is sealed between a pair of substrates having electrodes on opposite surfaces, and a display panel having a memory property for performing display by movement of the charged particle, and display data are input. And a driving means for outputting a driving voltage waveform to the electrode, wherein the driving voltage waveform is composed of a driving pulse train in which a plurality of display inversion pulses and a plurality of pause pulses are combined, and the display inversion pulse is paused. The pulse width is shorter than the pulse.

  The driving means outputs the next display inversion pulse while the display shade of the display panel is changing due to the application of the display inversion pulse.

  Further, the drive means is characterized in that at least two of the display inversion pulses are pulses having the same pulse width and the same voltage value. Alternatively, the driving means outputs the last display inversion pulse of the drive pulse train with a pulse width longer than the display inversion pulse output before that.

  The driving means is characterized in that the pulse width of the display inversion pulse and the pulse width of the pause pulse are selected so that the display shade of the display panel changes with a predetermined curve.

  The drive means is characterized in that the drive voltage waveform is configured such that the individual pulse width of the display inversion pulse is 200 mS or less and the total pulse width of the display inversion pulse is 250 mS or less.

  The display panel is an electrophoretic display panel in which charged particles move by electrophoresis according to the polarity of a voltage applied between the electrodes of a pair of substrates, and the electrodes are provided on each of the pair of substrates. The electrode on one of the substrates is a plurality of segment electrodes, the electrode on the other substrate is a common electrode facing the plurality of segment electrodes, and the drive voltage waveform is applied to each of the plurality of segment electrodes. It is characterized by that.

  As described above, according to the present invention, even in the case of a still image, the shade of the display changes dynamically over a predetermined time, so that a unique display that attracts attention is given with an animation display effect. An electrophoretic display device can be provided. Further, since the display shade can be changed smoothly, the display shade can be changed beautifully to realize a unique display that attracts attention. Furthermore, since the change curve of the display shade can be appropriately selected, the shade of the display can be changed beautifully.

  In addition, since the contrast after the change of display density is increased and high contrast can be maintained, an electrophoretic display device with excellent visibility can be realized. Further, it is possible to realize an electrophoretic display device that prevents deterioration of the display panel and has excellent reliability.

In addition, an electrophoretic display panel can provide a display device with extremely low power consumption. In addition, since the drive waveform is applied to each segment electrode of the electrophoretic display panel, it is possible to provide an electrophoretic display device having good contrast and excellent visibility.

  In this way, even in the case of a still image, since the display shade changes dynamically over a predetermined time, an electrophoretic display device that has an animated display effect and performs eye-catching unique display is provided. Can be provided. In addition, since an animation-like display effect can be provided without requiring a large-scale circuit configuration, a display device having an excellent display effect can be realized with a simple circuit configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, a schematic configuration of Embodiment 1 of the electrophoretic display device of the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes an electrophoretic display device of the present invention. The electrophoretic display device 1 includes a display panel 50 and a drive IC 30 in which a plurality of segment drivers as drive means for driving the display panel 50 are integrated.

  Here, in the display panel 50, charged particles 63 are encapsulated between a common electrode COM and a segment electrode SEG formed on opposite surfaces of a pair of substrates by a transparent resin substrate 51 and a flexible printed circuit board (hereinafter abbreviated as FPC) 55. The electrophoretic display panel in which the charged particles 63 move by electrophoresis according to the polarity of the voltage applied to the common electrode COM and the segment electrode SEG. The structure and operation of the display panel 50 will be described later.

  Next, the drive IC 30 includes a plurality of segment drivers 10a to 10h as drive means for driving the display panel 50, the input circuit 3, and the like. Here, the segment drivers 10 a to 10 h output drive voltages SEGVa to SEGVh to the display panel 50. The drive IC 30 is also provided with a clock circuit that generates a clock signal, a power supply circuit that generates a positive voltage + V and a negative voltage −V, and the like, but is not shown because it is not a special circuit.

  Further, the segment drivers 10a to 10h built in the drive IC 30 of this embodiment are configured by eight and drive each segment electrode SEG of the display panel 50. However, the number of segment drivers is not limited, and the segments of the display panel 50 are not limited. Segment drivers are provided according to the number of electrodes. Note that the common electrode COM of the display panel 50 is not shown, but is connected to 0V.

  Next, the input circuit 3 in the driving IC 30 has a function of inputting an input signal P1 including display data and a control signal from the outside of the driving IC 30 and transmitting the input signal P1 to the segment drivers 10a to 10h. That is, the input circuit 3 receives the input signal P1, and outputs display data P2a to P2h corresponding to each segment electrode, a clock signal P3, and a display rewrite signal P4. Note that, outside the electrophoretic display device 1, although not shown, there is a control unit of an electronic device in which the electrophoretic display device 1 is incorporated, and an input signal P 1 including display data and control signals is output from this control unit. .

Next, the internal configuration of the segment drivers 10a to 10h will be described in detail. Since the segment drivers 10a to 10h have the same configuration, the segment driver 10a will be described. Here, 11 inside the segment driver 10a is a shift register, which receives display data P2a, stores it at the timing of the clock signal P3, and displays the current display data P5a which is the current display data and the display to be rewritten next. Next display data P5b, which is data, is sequentially output.

  Next, reference numeral 12 denotes a display transition detection unit which inputs current display data P5a and next display data P5b, which are stored information of the shift register 11, detects display data transitions, classifies them, and outputs display transition signals P6a to P6d. To do. Here, the display transition signal P6a indicates that when the segment to be driven is white (current display data P5a = "0") and the next display is white (next display data P5b = "0"), This signal is a logic “1”. In addition, the display transition signal P6b is a logical signal when the segment to be driven is black when the current display is black (current display data P5a = "1") and the next display is black (next display data P5b = "1"). This signal is “1”.

  In addition, the display transition signal P6c is logical when the segment being driven is white (current display data P5a = "0") and black (next display data P5b = "1"). This signal is “1”. Further, the display transition signal P6d is logical when the segment to be driven is black when the current display is black (current display data P5a = "1") and the next display is white (next display data P5b = "0"). This signal is “1”. That is, the display transition detection unit 12 classifies the transition of display data into four, and outputs the detection results as display transition signals P6a to P6d. The display transition detection unit 12 can be configured with only a gate circuit.

  Next, reference numeral 20 denotes a drive pulse generator, which receives display transition signals P6a to P6d, and generates and outputs drive control pulses P7a, P7b, and P7c for driving the display panel 50 in synchronization with the display rewrite signal P4. The display rewrite signal P4 is a timing signal input from the outside every time the display contents of the display panel 50 are rewritten. The display rewrite signal P4 is generated inside the drive IC 30 by slightly delaying the clock signal P3 of the shift register 11. May be. The details of the internal configuration of the drive pulse generator 20 will be described later.

  Next, reference numeral 40 denotes a drive voltage output unit that receives the drive control pulses P7a, P7b, and P7c described above, converts the pulses into positive voltages + V, 0V, and negative voltage −V, and drives the drive voltage waveform. The voltage is output as the voltage SEGVa, and the corresponding segment electrode SEG of the display panel 50 is driven. As an example of the voltage value, the positive voltage + V is a DC voltage of about + 15V, and the negative voltage −V is a DC voltage of about −15V. The segment drivers 10b to 10h also output drive voltages SEGVb to SEGVh, respectively, to drive the segment electrodes SEG of the display panel 50. The details of the internal configuration of the drive voltage output unit 40 will be described later.

  Next, the internal configuration of the drive pulse generator 20 and the drive voltage output unit 40 will be described in detail with reference to FIG. In FIG. 2, the drive pulse generator 20 includes a counter circuit 21 and a display inversion ROM 22. Here, the counter circuit 21 receives the display rewrite signal P4, counts an internal clock signal (not shown), and outputs a multi-bit count signal P8. Note that the number of bits of the count signal P8 is not limited, but is composed of, for example, 8 bits.

  The display inversion ROM 22 is a ROM (READ ONLY MEMORY) that stores and outputs the pattern information of the drive control pulses P7a to P7c. The count inversion ROM 22 inputs the count signal P8 to the lower address (for example, 8 bits) and outputs the upper address of 4 bits. Display transition signals P6a to P6d. With this configuration, the pattern information of the drive control pulses P7a, P7b and P7c stored in the display inversion ROM 22 is switched by the logic of the display transition signals P6a to P6d, and the time is changed by the transition of the counter signal P8 input to the lower address. Sequentially output sequentially.

Next, the operation of the drive pulse generator 20 will be described. Here, when the display rewrite signal P4 is input to the counter circuit 21 of the drive pulse generator 20, the counter circuit 21 starts counting the internal clock signal. If the counter circuit 21 has an 8-bit specification,
The count from “0” to “255” is counted, and the transition of the count value is input to the lower address of the display inversion ROM 22 by the count signal P8. The counter circuit 21 returns from the count “255” to the count “0” and stops the count operation until the next display rewrite signal P4 is input.

  Here, the cycle of the internal clock signal of the counter circuit 21 may be arbitrary. For example, if the cycle of the clock signal is about 2 mS, the counter circuit 21 continues the count operation for a period of 500 mS or more and outputs the count signal P8. To do. The display transition signals P6a to P6d are input to the upper address of the display inversion ROM 22 to select the previously stored pattern information, and the count signal P8 is counted from “0” to “255” as the lower address. By being input, the selected pattern information is sequentially output in time series as drive control pulses P7a, P7b, P7c.

  That is, the drive pulse generator 20 starts operation using the display rewrite signal P4 as a start signal, and sequentially selects the drive control pulses P7a, P7b, and P7c selected by the display transition signals P6a to P6d in a predetermined time series. Output. The period during which the drive control pulses P7a, P7b, and P7c are output can be arbitrarily determined according to the cycle of the clock signal counted by the counter circuit 21 and the number of bits of the counter circuit 21. Note that a period during which the drive pulse generator 20 operates is a display inversion period T1 described later.

  Next, the internal configuration of the drive voltage output unit 40 will be described with reference to FIG. The drive voltage output unit 40 includes three semiconductor switches 41 to 43. The input terminal 41a of the semiconductor switch 41 is connected to the positive voltage + V, the output terminal 41b is connected to the drive voltage SEGV line, and the control terminal 41c is connected to the drive control pulse P7a. The input terminal 42a of the semiconductor switch 42 is connected to 0V, the output terminal 42b is connected to the line of the drive voltage SEGV, and the control terminal 42c is connected to the drive control pulse P7b. The input terminal 43a of the semiconductor switch 43 is connected to the negative voltage −V, the output terminal 43b is connected to the line of the drive voltage SEGV, and the control terminal 43c is connected to the drive control pulse P7c.

  With this configuration, when the drive control pulse P7a becomes logic “1”, the semiconductor switch 41 is turned ON, the positive voltage + V is applied as the drive voltage SEGV, and when the drive control pulse P7b becomes logic “1”, the semiconductor switch 42 is turned on. Is turned ON and 0V is applied to the drive voltage SEGV, and when the drive control pulse P7c becomes logic “1”, the semiconductor switch 43 is turned ON and the negative voltage −V is applied to the drive voltage SEGV. As a result, the drive voltage SEGV outputs a ternary voltage of positive voltage + V, 0 V, and negative voltage −V, and is supplied to the segment electrode of the display panel 50. Note that two or more drive control pulses P7a, P7b, and P7c do not simultaneously become logic “1”.

  Next, based on FIG. 3 which is a schematic enlarged sectional view of the display panel 50, the structure and operation principle of the display panel 50 will be described. In FIG. 3, a display panel 50 is a microcapsule electrophoretic display panel. In the display panel 50, a transparent common electrode COM made of an ITO (indium tin oxide) film is formed on the entire back surface of a transparent resin substrate 51 (see FIG. 1). Further, a segment electrode SEG for each pixel is formed on the FPC 55 (see FIG. 1) so as to face the common electrode COM, and a microcapsule display layer 53, also referred to as electronic ink, is formed between the two electrodes. In the microcapsule display layer 53, a large number of microcapsules 60 having a diameter of about several tens of μm are dispersed in a mixture such as a binder, a surfactant, a thickener, and pure water.

In this microcapsule 60, white particles 63a made of titanium oxide or the like as charged particles and black particles 63b made of carbon black or the like are charged inside a capsule shell 61 made of transparent methacrylic resin or the like. It is enclosed in a state of being dispersed in an appropriate dispersion medium 62. The white particles 63a are negatively charged, and the black particles 63b are positively charged.

  In addition, among the electrodes arranged so as to sandwich the microcapsule display layer 53, in the pixel portion in which one whole common electrode COM is grounded and a negative voltage is applied to the segment electrode SEG on the other FPC 55, Since the negatively charged white particles 63a in the microcapsule 60 are moved to the transparent common electrode COM side by the electric field, and the positively charged black particles 63b are moved to the segment electrode SEG side, the incident light B incident from the viewing side is white. Reflected by the particles 63a, the pixels appear white.

  On the other hand, in the pixel portion where a positive voltage is applied to the segment electrode SEG, the positively charged black particles 63b in the microcapsule 60 by the opposite electric field are transferred to the transparent common electrode COM side, and the negatively charged white particles 63a are Since it moves to the segment electrode SEG side, the incident light B incident from the viewing side is absorbed by the black particles 63b and the pixels appear black.

  Accordingly, the display state of the corresponding pixel can be changed to white or black depending on the polarity of the voltage applied between the common electrode COM and the segment electrode SEG. At this time, the white particles 63a and the black particles 63b move in the dispersion medium 62 by electrophoresis. However, since the dispersion medium 62 has a high viscosity, the display state is changed by applying a voltage, and then the application of the voltage is stopped. Even so, the intermolecular force of each particle can provide a memory effect that maintains its display state. As a result, the display panel 50 only needs to apply the drive voltage when changing the display, and thus a display device with extremely low power consumption can be realized.

  In this embodiment, microcapsules are used, and two charged particles of white and black are used, which is different from the conventional example (see FIGS. 12A and 12B). The principle of operation as an electrophoretic display panel that moves by electrophoresis is the same as in the conventional example.

  Next, based on the timing chart of FIG. 4, the drive voltage waveform of Example 1 of this invention is demonstrated. Here, the drive voltage waveform of the first embodiment has four display inversion pulses and their display inversions in order to change the display shade of the display panel 50 from white to black or from black to white over a predetermined time. It consists of three pause pulses that separate the pulses.

  In FIG. 4, COMV is a drive voltage applied to the common electrode COM of the display panel 50, and SEGV11 to SEGV14 are four types of drive voltage waveforms applied to any of the segment electrodes SEG. These drive voltage waveforms maintain the display inversion period T1 in which the display inversion pulse for rewriting the display corresponding to the display data (white or black data) is applied, and the display state before the application of the display inversion pulse. Display period T2a and a display period T2b for maintaining a display state corresponding to the display data after application of the display inversion pulse.

  Here, as described above, the drive voltage COMV to the common electrode COM is always grounded to have a potential of 0V. Next, when a display rewrite signal P4 that is included in the input signal P1 from the external control unit (not shown) and rewrites the display content arrives, the display panel 50 starts display from the display period T2a that holds the display. The display shifts to a display inversion period T1 for rewriting. That is, the drive pulse generator 20 outputs drive control pulses P7a, P7b, P7c based on the display transition signals P6a to P6d shown in FIG. 1 in synchronization with the display rewrite signal P4, and the drive voltage output unit 40 The drive voltages SEGV11 to SEGV14 shown in FIG. 4 are output by the drive control pulses P7a, P7b, and P7c.

  Here, SEGV11 is a drive voltage output when the display transition signal P6a is logic “1” (that is, the transition of the display data is white → white). When the display transition signal P6a having the logic “1” is input to the display inversion ROM 22 of the drive pulse generation unit 20 and the display rewrite signal P4 is input to the counter circuit 21, the drive control pulses P7a and P7c are output from the display inversion ROM 22. The logic “0” is continuously output, and the logic “1” is continuously output as the drive control pulse P7b.

  This is because the display inversion ROM 22 sets the drive control pulses P7a, P7b, and P7c as outputs to logic "0", "1", and "0" in the entire area of the lower address in the logic "1" of the display transition signal P6a. I remember it. According to the logic of the drive control pulses P7a, P7b, and P7c, the semiconductor switches 41 and 43 of the drive voltage output unit 40 are turned off and the semiconductor switch 42 is turned on, and the drive voltage SEGV11 that is always 0V is output. Thereby, the segment electrode SEG to which the drive voltage SEGV11 is applied continues white display.

  Next, SEGV12 is a drive voltage output when the display transition signal P6b is logic “1” (that is, the transition of the display data is black → black). When the display transition signal P6b having the logic “1” is input to the display inversion ROM 22 of the drive pulse generator 20 and the display rewrite signal P4 is input to the counter circuit 21, the drive control pulses P7a and P7c are output from the display inversion ROM 22. The logic “0” is continuously output, and the logic “1” is continuously output as the drive control pulse P7b.

  Accordingly, 0 V is always output as the drive voltage SEGV12, so the segment electrode SEG to which the drive voltage SEGV12 is applied continues to display black.

  Next, SEGV13 is a drive voltage output when the display transition signal P6c is logic “1” (that is, the transition of display data is white → black). That is, it is a drive voltage for changing the display content of the corresponding segment from white to black over a predetermined time. When the display is white, a plurality of display inversion pulses of positive voltage + V and 0 V are used for rewriting to black. A plurality of pause pulses are sequentially output.

  Here, when the display transition signal P6c of logic “1” is input to the display inversion ROM 22 of the drive pulse generator 20 and the display rewrite signal P4 is input to the counter circuit 21, the count operation starts. The drive control pulses P7a, P7b, and P7c become logic “1”, “0”, and “0” only for a predetermined period. As a result, a display inversion pulse B11 having a positive voltage + V is output as the drive voltage waveform. Thereafter, the drive control pulses P7a, P7b, and P7c become logic “0”, “1”, and “0” for a predetermined period, thereby outputting a pause pulse C11 that is 0V.

  Thereafter, the same operation is repeated according to the pattern stored in the display inversion ROM 22, and during the display inversion period T1, four display inversion pulses B11 to B14 and three pause pulses C11 to C11 that separate the display inversion pulses B11 to B14 are displayed. A drive pulse train of C13 is output. As an example, each pulse width is about 10 mS for the display inversion pulse B11, about 20 mS for the display inversion pulses B12 and B13, and about 80 mS for the display inversion pulse B14 at the end of the drive pulse train. Further, the pause pulse C11 is about 100 mS, the pause pulse C12 is about 110 mS, and the pause pulse C13 is about 120 mS. Thereby, the display inversion period T1 becomes about 460 mS. The pause pulse seems to change continuously by setting it shorter than the response time of the electronic ink. Since the response time of the display device used in this example is about 200 mS at room temperature, the pause pulse needs to be shorter than 200 mS.

When the count value of the counter circuit 21 returns to “0”, the drive control pulses P7a and P7b
, P7c is fixed to logic “0”, “1”, “0”, and shifts to a display period T2b in which 0 V having the same potential as the drive voltage COMV is output.

  Next, SEGV14 is a drive voltage output when the display transition signal P6d is logic “1” (that is, the transition of the display data is black → white). That is, a drive voltage for changing the display content of the corresponding segment from black to white over a predetermined time, and when the display is black, a plurality of display inversion pulses of negative voltage −V for rewriting to white A plurality of pause pulses of 0V are sequentially output.

  Here, when the display transition signal P6d of logic “1” is input to the display inversion ROM 22 of the drive pulse generator 20 and the display rewrite signal P4 is input to the counter circuit 21, the count operation starts. The drive control pulses P7a, P7b, P7c become logic “0”, “0”, “1” only for a predetermined period, and as a result, a display inversion pulse W11 having a negative voltage −V is output as a drive voltage waveform. Thereafter, the drive control pulses P7a, P7b, and P7c become logic “0”, “1”, and “0” for a predetermined period, thereby outputting a pause pulse C11 that is 0V.

  Thereafter, the same operation is repeated according to the pattern stored in the display inversion ROM 22, and in the display inversion period T1, four display inversion pulses W11 to W14 and three pause pulses C11 to C11 for separating the display inversion pulses W11 to W14 are separated. C13 is output. Here, as shown in the figure, the drive voltage SEGV14 is a drive waveform having a voltage polarity inverted from that of the drive voltage SEGV13, and each pulse width is the same as that of the drive voltage SEGV13.

  Next, based on FIGS. 5 and 6, the display operation of the display panel 50 according to the drive voltage waveform of the first embodiment will be described. FIG. 5 shows an example of a change in the reflectance R1 of the display panel 50 when the drive voltage SEGV14 of the first embodiment is applied to a specific segment of the display panel 50. FIG. 6 shows an example of the movement of the charged particles in the microcapsules of the display panel 50 when the drive voltage SEGV14 of the first embodiment is applied. As a premise for explanation, it is assumed that the display state of the segment in the display period T2a is black, and therefore the reflectance R1 at this time is the minimum.

  That is, as shown in (1) of FIG. 6, in the display period T2a, the black particles 63b are concentrated in the vicinity of the common electrode COM, and the white particles 63a are concentrated in the vicinity of the segment electrode SEG. ) Is mostly absorbed by the black particles 63b.

  Here, when the display inversion period T1 starts in FIG. 5 and the first display inversion pulse W11 is output, the segment electrode SEG becomes negative voltage −V for a period of about 10 mS, so that the Coulomb force acts. The white particles 63a and the black particles 63b start to move, and the white particles 63a are separated from the segment electrodes SEG and the black particles 63b are separated from the common electrode COM as shown in (2) of FIG. As a result, part of the incident light reaches the white particles 63a and is reflected, so that the reflectance R1 slightly increases.

  As a result, the reflectance R1 increases while drawing a reflectance curve R11 as shown in FIG. The white particles 63a and black particles 63b that have started to move by the application of the display inversion pulse W11 continue to move slightly due to inertia even during the period of the pause pulse C11, so that the reflectance curve R11 continues to increase slightly.

Next, when the second display inversion pulse W12 is output while the reflectance curve R11 continues to rise, the segment electrode has a negative voltage −V for a period of about 20 mS. 63a and the black particles 63b move further, and a part of the white particles 63a and the black particles 63b are mixed as shown in (3) of FIG. As a result, the rate at which incident light reaches the white particles 63a and is reflected increases, and thus the reflectance R1 increases while drawing a reflectance curve R12. Then, the white particles 63a and the black particles 63b that have moved by the application of the display inversion pulse W12 continue to move slightly due to inertia even during the period of the pause pulse C12, and thus the reflectance curve R12 continues to increase slightly.

  Similarly, the third display inversion pulse W13 and the fourth display inversion pulse W14 are sequentially output, and the reflectance R1 rises while drawing the reflectance curve R13 and the reflectance curve R14. That is, the white particles 63a and the black particles 63b are further moved by the application of the display inversion pulse W13, and the white particles 63a and the black particles 63b are mixed as shown in (4) of FIG. 6, and the white particles 63a and the black particles 63b are mixed. The positional relationship of is reversed.

  Further, since the pulse width of the display inversion pulse W14 output last is longer than that of the other display inversion pulses, the Coulomb force continues to act on the white particles 63a and the black particles 63b, as shown by (5) in FIG. Thus, the white particles 63a are concentrated in the vicinity of the common electrode COM, the black particles 63b are concentrated in the vicinity of the segment electrode SEG and cannot move any more, and the reflectance R1 is maximized and saturated. Accordingly, even when the display inversion period T1 ends and the display period T2b starts, the maximum reflectance R1 is maintained, so that a display with high contrast and excellent visibility is continued.

  As described above, in the display panel 50, when the drive voltage SEGV14 is applied, the reflectance R1 changes over time from the minimum to the maximum in the period of about 460 mS which is the display inversion period T1. The fact that the reflectance R1 of the display panel 50 changes from the minimum to the maximum means that the gradation gradually changes from black to white.

  Further, when the drive voltage SEGV13 constituted by the display inversion pulses B11 to B14 of the positive voltage + V and the pause pulses C11 to C13 is applied, the reflectance R1 changes from the maximum to the minimum over time. The state of change is the same as the curve obtained by inverting the reflectance R1 shown in FIG.

  Next, a display example in the case where the drive voltage waveform of the present embodiment is applied will be described by taking the display panel 50 that displays one-digit seven segment characters as an example. First, an example of the display panel 50 composed of seven segment characters will be described with reference to FIG. In FIG. 7, the display panel 50 is composed of a display body that represents a seven-segment character SC composed of segments S0 to S6 by one digit. S7 represents the background area of the seven segment character SC.

  The display panel 50 has one common electrode COM and eight segment electrodes as electrodes. Here, the eight segment electrodes are the segment electrodes SEG0 to SEG6 corresponding to the segment S0 to the segment S6 and the segment electrode BG corresponding to the background region S7. Further, the nine lines coming out from the lower part of the display panel 50 are lead wires connected to the common electrode COM and the eight segment electrodes SEG0 to SEG6, BG, respectively, and the respective lead wires are connected. The same name as each electrode is attached and shown. Each lead wire is connected to the drive voltages SEGVa to SEGVh output from the drive IC 30 described above.

Next, according to FIGS. 8A to 8C, the background area S7 of the seven segment character SC shown in FIG. 7 is displayed in white, and the segments S0, S1, S6, S4, and S3 are gradually displayed in black. A case where the display is performed will be described. Here, the drive voltage SEGV11 shown in FIG. 4 is output to the segment electrode BG in the background region S7 for white display. Then, the drive voltage SEGV13 shown in FIG. 4 is output to the segment electrodes SEG0, SEG1, SEG6, SEG4, and SEG3 of the segments S0, S1, S6, S4, and S3.

  Here, in the initial state, that is, in the display period T2a of FIG. 4, the background region S7 and the segments S0, S1, S6, S4, and S3 are displayed in white. When the first display inversion pulse B11 is output to the segments S0, S1, S6, S4, and S3 in the display inversion period T1 in FIG. 4, the white particles 63a and the black particles 63b start to move, and the white particles 63a. Is away from the common electrode COM (see FIG. 6 (4)). As a result, a part of the incident light does not reach the white particles 63a, so the reflectance R1 slightly decreases, and the segments S0, S1, S6, S4, and S3 are thin as shown in FIG. 8A. The display is black and the number “2” is displayed slightly. The white particles 63a and the black particles 63b continue to move slightly due to inertia even during the pause pulse C11, so that the reflectance curve continues to slightly decrease.

  Next, when the second display inversion pulse B12 is output while the reflectance curve continues to fall, the segment electrode becomes the positive voltage + V again, so that the white particles 63a and the black particles 63b are Further moving, the ratio of incident light reaching the white particles and reflecting is further reduced, and as shown in FIG. 8B, the numeral “2” is gradually displayed darker. Then, the white particles 63a and the black particles 63b that have moved by the application of the display inversion pulse B12 continue to move slightly due to inertia even during the pause pulse C12, so that the reflectance curve continues to decrease slightly.

  Similarly, the third display inversion pulse B13 and the fourth display inversion pulse B14 are sequentially output, the white particles 63a and the black particles 63b further move, and the positional relationship between the white particles 63a and the black particles 63b is as follows. Inverted (see FIG. 6 (2) and FIG. 6 (1)).

  Further, since the pulse width of the display inversion pulse B14 output last is longer than that of the other display inversion pulses, the black particles 63b are concentrated near the common electrode COM, and the white particles 63a are concentrated near the segment electrode SEG. It cannot move any more, and the reflectance is minimized and becomes saturated. As a result, as shown in FIG. 8C, even when the display inversion period T1 ends and shifts to the display period T2b, the black display state with the minimum reflectance continues, so the number “2”. Is displayed in black, and display with high contrast and excellent visibility can be performed.

  Here, the background area S7 is displayed in white, the initial state of the segments S0, S1, S6, S4, and S3 is displayed in white, and the number “2” is displayed on the white background so as to gradually rise. The background region S7 can be displayed in black, and the initial state of the segments S0, S1, S6, S4, and S3 can be displayed in black, and the white number “2” can be displayed on the black background so as to gradually rise. In this case, the drive waveform of SEGV12 shown in FIG. 4 is output to the segment electrode BG in the background region S7, and the segment electrodes SEG0, SEG1, SEG6, SEG4, and SEG3 of the segments S0, S1, S6, S4, and S3 are output. Outputs the drive waveform of SEGV14 shown in FIG. In either case, it is preferable to unify all segment electrodes in black or white display in the initial state, that is, in the display period T2a in FIG.

  Next, an example of a display operation using the drive voltage waveform of the present embodiment will be described based on the flowchart of FIG. When display is started in FIG. 9, display refresh is performed first (step ST11). Here, the display refresh is an operation of removing the DC component remaining on the display panel and making all pixels display white.

  Next, in step ST12, based on the pattern 1 data stored in advance, a drive voltage SEGV13 (see FIG. 4) for turning white display to black display is output to a predetermined pixel. As a result, the pixel changes from white to black over a predetermined time. That is, it operates so that the pattern 1 gradually emerges from the all white state.

  Next, in step ST13, the display is stopped after waiting for a predetermined time.

  Next, in step ST14, based on the pattern 2 data stored in advance, the drive voltage SEGV14 (see FIG. 4) for making the black display white display is output to a predetermined pixel, and the white display is made to other pixels. The drive voltage SEGV13 (see FIG. 4) for black display is output. As a result, the pattern 1 gradually disappears, and at the same time, the pattern 2 gradually emerges.

  Next, in step ST15, the display is stopped after waiting for a predetermined time.

  Next, in step ST16, the value of the display count is increased by one.

  Next, in step ST17, the display count is checked. If the predetermined display count has been reached, the display is terminated. If the predetermined display count has not been reached, the process returns to step ST12, and steps ST12 to ST17 are executed. The display of pattern 1 and pattern 2 is repeated.

  By performing such a display operation, it is possible to perform a display operation in which various patterns gradually appear and gradually disappear. Further, in the flowchart shown in FIG. 9, a step of displaying all pixels in white may be inserted while the pattern 1 proceeds from the pattern 1 to the pattern 2 and between the pattern 2 and the pattern 1. As a result, the pattern that appears and disappears does not mix in time, and a beautiful display that is easy to recognize can be realized.

  As described above, the electrophoretic display device of the present invention is characterized in that the drive voltage waveform is composed of a drive pulse train in which a plurality of display inversion pulses and a plurality of pause pulses are combined, and the display inversion pulse has a shorter pulse width than the pause pulses. It is said. As a result, a display inversion pulse with a short pulse width is applied to the display panel at intervals, so that the reflectivity of the display panel gradually changes in accordance with the display inversion pulse, and therefore the display gray level is changed to display inversion. In the period T1, it gradually changes over time from black to white or from white to black.

  As a result, even if the display content is a static image, the shade of the display changes dynamically, so that the pattern gradually appears or disappears (fade in / fade out) and can be expressed with an animated display effect. Thus, it is possible to provide an electrophoretic display device that performs a unique display that attracts attention.

  Further, the electrophoretic display device of the present invention outputs the next display inversion pulse while the reflectance of the display panel is increased by the display inversion pulse, that is, while the display shade is changing, the display inversion pulse is output. The shade of the image can be changed smoothly, the shade of the display changes beautifully, and a unique display that is even more eye-catching can be realized.

  Also, the electrophoretic display device of the present invention outputs the last display inversion pulse of the drive pulse train with a pulse width longer than the display inversion pulse output before that, so that the reflectance of the display panel is maximized or minimized. In addition, it is possible to realize an electrophoretic display device that enhances display contrast, maintains high contrast, and has excellent visibility.

Further, the electrophoretic display device of the present invention can arbitrarily set a change curve of the reflectance of the display panel by selecting a plurality of display inversion pulses and pause pulse widths, respectively. Thus, for example, if the display shading is selected to change substantially linearly, the display shading change can be made constant and continuous with respect to time, so that the shading change can be expressed more beautifully and smoothly. I can do it.

  Further, the present invention can be realized only by setting the number of display inversion pulses and pause pulses and the pulse width, so that an animation-like display with a circuit scale comparable to the conventional one without requiring a large-scale circuit configuration. It is possible to achieve a display device that can have an effect, is low in cost, and has an excellent display effect.

  In the block diagram of the present invention shown in FIG. 1, the drive pulse generation unit 20, the display transition detection unit 12 and the like are placed independently for each segment driver, but this is for easy understanding of the configuration. Actually, the drive pulse generation unit 20, the display transition detection unit 12, and the like may be configured as a single unit, and each drive control pulse may be supplied to each segment driver. Further, the upper address of the display inversion ROM 22 in FIG. 2 is composed of 4 bits, but this is also for easy understanding of the configuration. In practice, the output of the display transition detection unit 12 is coded to be 2 bits. The upper address of the display inversion ROM 22 can be composed of 2 bits.

  Next, based on the timing chart of FIG. 10, the drive voltage waveform of Example 2 of this invention is demonstrated. The configuration of the electrophoretic display device according to the second embodiment is the same as that of the first embodiment, and a description thereof will be omitted. Further, the basic operations of the display panel 50 and the drive IC 30 are the same as those in the first embodiment, so that the description thereof is omitted. In the second embodiment, only the configuration of the drive voltage waveform and the display operation of the display panel 50 will be described. Here, the drive voltage waveform of the second embodiment has seven display inversions higher than those of the first embodiment in order to change the display shade of the display panel 50 from white to black or from black to white over a predetermined time. It is composed of six pause pulses that separate the pulse and its display inversion pulse.

  In FIG. 10, the drive voltage COMV is the same as that in the first embodiment, and a description thereof is omitted. SEGV21 is a drive voltage that is output when the transition of display data is from white to white, and is the same as SEGV11 of the first embodiment. SEGV22 is output when the transition of display data is from black to black. The driving voltage is the same as that of the SEGV12 of the first embodiment.

  Next, SEGV23 is a drive voltage output when the display transition signal P6c is logic “1” (that is, the transition of the display data is white → black), and the display content of the corresponding segment is changed from white to black. It can change over time.

  That is, the drive voltage SEGV23 is configured by a drive pulse train of seven display inversion pulses B21 to B27 having a positive voltage + V and six pause pulses C21 to C26 that separate the display inversion pulses B21 to B27 in the display inversion period T1. The Here, as an example, the display inversion pulses B21 to B26 are each about 10 mS, and the display inversion pulse B27 at the end of the drive pulse train is about 100 mS. The rest pulses C21 to C26 are all about 100 mS. Thereby, the display inversion period T1 is about 760 mS, and the display can be changed more slowly than in the first embodiment. The pulse width of the display inversion pulse B27 at the end of the drive pulse train may be exceptionally longer than the pause pulse. Further, in the display periods T2a and T2b, the driving voltage SEGV23 outputs 0 V having the same potential as the driving voltage COMV.

  Next, the SEGV 24 is a drive voltage output when the display transition signal P6d is logic “1” (that is, the transition of the display data is black → white), and the display content of the corresponding segment is changed from black to white. It can change over time.

  That is, the drive voltage SEGV24 is output during the display inversion period T1 as a drive pulse train of seven display inversion pulses W21 to W27 having a negative voltage −V and six pause pulses C21 to C26 that separate the display inversion pulses W21 to W27. Is done. Here, as shown in the figure, the drive voltage SEGV24 is a drive waveform having a voltage polarity inverted from that of the drive voltage SEGV23, and each pulse width is the same as that of the drive voltage SEGV23.

  Next, based on FIG. 11, the display operation of the display panel 50 by the drive voltage waveform of Example 2 is demonstrated. FIG. 11 shows an example of a change in the reflectance R2 of the display panel 50 when the drive voltage SEGV24 of Example 2 is applied to a specific segment of the display panel 50. As a premise for the explanation, it is assumed that the display state of the segment in the display period T2a is black as in the first embodiment, and the reflectance R2 at this time is the minimum. That is, as shown in (1) of FIG. 6, in the display period T2a, the black particles 63b are concentrated in the vicinity of the common electrode COM, and the white particles 63a are concentrated in the vicinity of the segment electrode SEG. ) Is mostly absorbed by the black particles 63b.

  Here, when the display inversion period T1 starts in FIG. 11 and the first display inversion pulse W21 is output, the segment electrode SEG becomes negative voltage −V for a period of about 10 mS, so that the Coulomb force acts. The white particles 63a and the black particles 63b start to move, whereby a part of the incident light reaches the white particles 63a and is reflected, so that the reflectance R2 slightly increases. As a result, the reflectance R2 increases while drawing a reflectance curve R21 as shown. Then, the white particles 63a and the black particles 63b that have started moving due to the application of the display inversion pulse W21 continue to move slightly due to inertia even during the period of the pause pulse C21, and thus the reflectance curve R21 continues to increase slightly.

  Next, when the second display inversion pulse W22 is output while the reflectance curve R21 continues to rise, the segment electrode is again at a negative voltage −V for a period of about 10 mS. The particles 63a and the black particles 63b further move, and the reflectance R2 increases while drawing a reflectance curve R22. Then, the white particles 63a and the black particles 63b moved by the application of the display inversion pulse W22 continue to move slightly due to inertia even during the period of the pause pulse C22, so that the reflectance curve R22 continues to increase slightly.

  Similarly, display inversion pulses W23 to W26 are sequentially output, and the reflectance R2 rises while drawing reflectance curves R23 to R26. The pulse width of the display inversion pulse W27 output at the end of the drive pulse train is longer than that of the other display inversion pulses. Therefore, the reflectance R2 is maximized and saturated at the reflectance curve R27, and after the change in display density. It is possible to maintain a display with excellent visibility by increasing the contrast.

  As described above, the drive voltage waveform of Example 2 is composed of seven display inversion pulses and six pause pulses that separate the display inversion pulses in a period of about 760 mS, which is the display inversion period T1. As a result, the change in reflectance that changes with the passage of time changes more finely and smoothly than the change in the first embodiment, and the display shade changes smoothly and beautifully in a long time, thereby realizing a unique display that is even more eye-catching. I can do it.

  The number of display inversion pulses and pause pulses is not limited. For example, if the number of display inversion pulses and pause pulses is increased from the number of pulses in the second embodiment, it is possible to realize a smoother change in shading. . In addition, the drive voltage waveform of Example 2 was configured such that the display inversion pulses were arranged at equal intervals so that the density changed substantially linearly. As a result, since the rate of change in display density is constant and continuous, the display density can be changed beautifully.

In addition, the change curve of the display shade is not limited to changing almost linearly, but by adjusting the pulse width of the display inversion pulse and pause pulse, the rise of the change can be made faster or slower. A characteristic may be given to the change curve of light and shade. The individual pulse width of the display inversion pulse in the display inversion period T1 is preferably 200 mS or less, and the total pulse width of the display inversion pulse is preferably 250 mS or less at room temperature. As a result, it is possible to provide an electrophoretic display device that prevents deterioration of the electrophoretic display panel and is excellent in reliability. Further, by changing the pulse width, pause pulse width, number of pulses, and total pulse width depending on the temperature, it is possible to provide an electrophoretic display device that is easier to see and more reliable.

  Further, the display inversion period T1 as the change time of the reflectivity of the display panel, that is, the display change time of the display has been described as being around 460 mS in the first embodiment and around 760 mS in the second embodiment. T1 is not limited. That is, the display inversion period T1 may be shortened so that the shade of the pattern to be displayed changes quickly, or the display inversion period T1 may be lengthened so that the shade of the pattern to be displayed changes slowly. It can be selected arbitrarily according to the specifications of the display device.

  As described above, according to the present invention, in the driving of an electrophoretic display panel with extremely low power consumption, the display shade changes dynamically within a predetermined time even for a still image. It is possible to provide an electrophoretic display device that has an effect and performs eye-catching and unique display.

  The display panel of the electrophoretic display device of the present invention has been described as an electrophoretic display panel in which charged particles move by electrophoresis. However, the present invention is not limited to this method, and a transparent dispersion medium is used. Instead, the present invention can also be applied by using a toner type or electronic powder fluid type display panel using air. Further, the display panel 50 in the embodiment has been described as a microcapsule type electrophoretic display panel, but the present invention is not limited to the microcapsule type, and for example, like the electrophoretic display panel 100 shown in the conventional example. It can also be applied to a system that does not use microcapsules.

  The electrophoretic display device of the present invention is suitable for a display panel that displays seven segment characters and various patterns as segments, but is not limited to such a form, and faces the common electrode. There are no limitations on the shape, arrangement, size, etc. of the electrodes to be pixels, such as a dot matrix pixel electrode that can display arbitrary characters, figures, and the like.

  In the embodiments, the display data displayed on the display device according to the present invention and the display state thereof have been described as white and black. However, this is not limited to general achromatic white and black, but similar colors or different hues. The two colors can be clearly distinguished from each other, such as bright and dark colors (two-tone colors), or two colors having a complementary color relationship. As the display panel in that case, for example, a microcapsule 60 shown in FIG. 3 in which charged particles charged in positive and negative colors of the two colors are encapsulated may be used.

  In addition, the segment driver as the driving means in the embodiment of the present invention may be realized by a custom IC using a logic circuit, or may be realized by incorporating firmware in a general-purpose microcomputer, and its form is not limited. . Further, the block diagrams, timing charts, and the like shown in the embodiments of the present invention are not limited thereto, and can be arbitrarily changed as long as they satisfy the gist of the present invention.

  In the present invention, the display transition detection unit 12 and the drive pulse generation unit 20 are built in the drive IC 30. However, the display transition detection unit and the drive pulse generation unit can be configured by an external CPU or an external circuit. is there.

It is a block diagram which shows schematic structure of the electrophoretic display device of this invention. It is a circuit diagram which shows the internal structure of the drive pulse generation part of the electrophoretic display device of this invention, and a drive voltage output part. It is an expanded sectional view explaining the structure and operation | movement of an electrophoretic type display panel used by this invention. 3 is a timing chart for explaining a driving voltage of the electrophoretic display device according to the first exemplary embodiment of the present invention. It is a graph which shows an example of the change of the reflectance of the display panel by the drive voltage of the electrophoretic display device concerning Example 1 of this invention. It is explanatory drawing explaining the motion of the charged particle of the electrophoretic display device concerning Example 1 of this invention. It is explanatory drawing which shows an example of the display panel comprised by the seven segment character concerning Example 1 of this invention. It is an example of a display when a display panel is driven by the drive voltage waveform concerning Example 1 of this invention, and is explanatory drawing which shows a mode that the number "2" is displayed lightly. It is an example of a display when the display panel is driven by the drive voltage waveform according to the first embodiment of the present invention, and is an explanatory diagram showing a state in which the numeral “2” is displayed gradually darker. It is a display example at the time of driving a display panel with the drive voltage waveform concerning Example 1 of this invention, and is explanatory drawing which shows a mode that the number "2" is displayed black. It is a flowchart which shows an example of the display operation | movement of the electrophoretic display apparatus concerning Example 1 of this invention. It is a timing chart explaining the drive voltage of the electrophoretic display device concerning Example 2 of the present invention. It is a graph which shows an example of the change of the reflectance of the display panel by the drive voltage of the electrophoretic display apparatus concerning Example 2 of this invention. Sectional drawing which shows the structure of the divided | segmented cell of the conventional electrophoretic display panel, and demonstrates that the electrophoretic particle is attracted to the element electrode side by applying a positive voltage to the common electrode 101, and a negative voltage to the element electrode 102 It is. FIG. 10 is a cross-sectional view illustrating the structure of a divided cell of a conventional electrophoretic display panel and explaining that electrophoretic particles move to the common electrode side when a negative voltage is applied to the common electrode 101 and a positive voltage is applied to the element electrode 102. . It is a timing chart explaining the writing of the gradation display of the conventional electrophoretic display panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophoretic display device 3 Input circuit 10a-10h Segment driver 11 Shift register 12 Display transition detection part 20 Drive pulse generation part 21 Counter circuit 22 Display inversion ROM
30 Drive IC
40 Drive Voltage Output Unit 41, 42, 43 Semiconductor Switch 50 Display Panel 51 Resin Substrate 53 Microcapsule Display Layer 55 Flexible Printed Circuit Board (FPC)
60 Microcapsule 61 Capsule shell 62 Dispersion medium 63 Charged particle 63a White particle 63b Black particle COM Common electrode SEG Segment electrode S0-S6 Segment S7 Background region SEGV, COMV Drive voltage P1 Input signal P2a-P2h Display data P3 Clock signal P4 Display rewrite Signal P5a Current display data P5b Next display data P6a to P6d Display transition signal P7a to P7c Drive control pulse P8 Counter signal B11 to B14, B21 to B27, W11 to W14, W21 to W27 Display inversion pulses C11 to C13, C21 to C26 Pause pulse

Claims (7)

Charged particles are enclosed between a pair of substrates having electrodes on opposite surfaces, and a display panel having a memory property for displaying by movement of the charged particles, and display data is input and a drive voltage waveform is output to the electrodes. A display device comprising: driving means;
2. The electrophoretic display device according to claim 1, wherein the drive voltage waveform includes a drive pulse train in which a plurality of display inversion pulses and a plurality of pause pulses are combined, and the display inversion pulse has a shorter pulse width than the pause pulses.   2. The electrophoresis according to claim 1, wherein the driving unit outputs the next display inversion pulse while the display density of the display panel is changed by the application of the display inversion pulse. Display device.   The electrophoretic display device according to claim 1, wherein at least two of the plurality of display inversion pulses are pulses having the same pulse width and the same voltage value.   The said drive means outputs the said display inversion pulse of the last of the said drive pulse train by the pulse width longer than the said display inversion pulse output before it, The one of Claim 1 to 3 characterized by the above-mentioned. The electrophoretic display device described.   5. The drive means according to claim 1, wherein the display inversion pulse and the pause pulse are selected so that the display shade of the display panel changes with a predetermined curve. The electrophoretic display device according to any one of the above.   2. The drive voltage waveform is configured such that the individual pulse widths of the display inversion pulses are 200 mS or less and the total pulse width of the display inversion pulses is 250 mS or less. 6. The electrophoretic display device according to any one of items 1 to 5. The display panel is an electrophoretic display panel in which the charged particles move by electrophoresis according to the polarity of a voltage applied between the electrodes of the pair of substrates.
The electrodes are provided on each of the pair of substrates, one of the pair of substrates is an electrode of a plurality of segments, and an electrode of the other substrate is a common electrode facing the plurality of segment electrodes. The electrophoretic display device according to claim 1, wherein the drive voltage waveform is applied to each of the plurality of segment electrodes.

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