JP2007086280A - Driving circuit and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving circuit of an electrophoresis type display device which can be switched between a driving using a binary segment voltage and a driving using a ternary segment voltage. <P>SOLUTION: This driving circuit 1, which outputs a voltage to be applied to a segment electrode (5-1) and a voltage to be applied to a common electrode 6 and has a plurality of voltage values output by the driving circuit 1, is provided with: a first varying means (2-1) of varying the number of voltage values to be applied to segment electrode (5-1) from the plurality of voltage values; and a second varying means 3 of varying the number of voltage values to be applied to the common electrode from the plurality of voltage values. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device and a drive circuit for driving the display device.

  2. Description of the Related Art An electrophoretic display device that is highly visible, rewritable, has a memory property that maintains display even when power supply is cut off, and has excellent features such as low power consumption is widely known. For example, development of an electronic paper display using the electrophoretic display device is progressing. As a display panel and its driving circuit (driving voltage generator) used in such a display device, for example, there is one disclosed in Patent Document 1.

  The display panel described in Patent Document 1 includes a “front plate” in which a microcapsule-type electronic ink is coated on a film in which a transparent electrode is formed on a transparent film, and a “back plate” in which an electrode circuit is formed. However, when this is configured as a general display panel, the transparent electrode on the front plate is spread over the entire panel surface, and a plurality of electrodes on the back plate are formed corresponding to a plurality of dots or segments according to the display pattern. . In the following description, the transparent electrode on the front plate will be referred to as “common electrode”, and the plurality of electrodes on the back plate will be referred to as “segment electrodes”.

  When trying to display a desired pattern on such a display panel, a positive voltage is applied to the segment electrode to be changed from white display to black display with respect to the potential applied to the common electrode. A negative voltage is applied to the segment electrode to be changed from black display to white display with respect to the potential applied to the common electrode, and the segment electrode that is not changed is equal to the potential applied to the common electrode. I was trying.

  As a first conventional example, a drive circuit for applying a voltage to the common electrode and the segment electrode as described above has a drive circuit output that can take three values of -V, 0 v, and + V. In the following description, this type of driving is referred to as “three-value driving”. In this ternary drive, the common electrode is always set to 0 V, and the segment electrode is not changed to + V when it is desired to change from white display to black display, and to -V when it is desired to change from black display to white display. In this case, 0v is set.

  Hereinafter, ternary driving will be described in detail as a first conventional example. FIG. 9 is a cross-sectional view of a display body that is a display device. A common electrode 61 which is a transparent electrode is provided on the upper surface of the display body 60, a display element 62 is provided below the common electrode 61, and a plurality of segment electrodes 63 made of a conductor formed on the FPC 64 are further provided below the display element 62. The display element 62 is, for example, microcapsule electronic ink described in Patent Document 1. In addition to those described above, a substrate, a protective film, an adhesive layer, and the like are used as the constituent elements of the display body.

  In such a display body 60, when a positive voltage is applied to the segment electrode 62 with respect to the common electrode 61, the display element 62 portion sandwiched between the common electrode 61 and the segment electrode 63 has a white display to a black color when viewed from above. When the display is changed and a negative voltage is applied to the segment electrode 63 with respect to the common electrode 61, the display element portion sandwiched between the common electrode and the segment electrode changes from black display to white display as viewed from above. When the potentials of the common electrode 61 and the segment electrode 63 are equal, the display element 62 portion sandwiched between these electrodes does not change.

FIG. 10 is an example of a display panel configured using such a display body. Display panel 7
0 is composed of a display body that represents a seven-segment character composed of segments 0 to 6 by one digit. The numbers 0 to 6 assigned to the segments in the drawing of the display panel 70 correspond to the segments 0 to 6. The area around the segments 0 to 6 of the display panel 70 represents the background of the seven segment character.

  The display panel 70 has one common electrode COM and eight segment electrodes as electrodes. The eight segment electrodes are the segment electrodes SEG0 to SEG6 corresponding to the segment 0 to the segment 6 and the segment electrode BG corresponding to the background. The nine wires coming out from the lower part of the display panel 70 are lead wires connected to the common electrode and the eight segment electrodes, respectively, and the lead wires connected to the common electrode are segments corresponding to COM and segment 0, respectively. The electrode lead wires are named SEG0, the segment electrode lead wires corresponding to segment 1 are named SEG1, and the corresponding electrode names are given in order. Then, each lead wire is sequentially connected to an external drive circuit not shown.

  Next, a driving method driven by ternary driving will be described with reference to FIGS. FIG. 11 is a waveform diagram of a voltage applied to each electrode of the display panel 70, and FIG. 12 shows how the display state of the display panel 70 changes and the display state of the display panel 70. In the period 80 in FIG. 11, 0 v is applied to all the electrodes. Therefore, as shown in FIG. 12, it is assumed that the segment display state 85 on the display panel 70 does not change and all the segments are displayed in white.

  Next, in a period 81 in FIG. 11, the positive voltage V is applied from SEG0 to SEG6 while the applied voltage to the electrode COM and the electrode BG remains 0v. As a result, the segments 0 to 6 of the display panel 70 change from white display to black display, and change to the display state 86 in FIG.

  Next, in the period 82 in FIG. 11, since 0 v is applied to all the electrodes again, as shown in FIG. 12, the display state of the segment remains unchanged and the display state 86 is maintained. Subsequently, in the period 83 in FIG. 11, the negative voltage −V is applied from SEG0 to SEG6 while the applied voltage to the electrode COM and the electrode BG remains 0v. As a result, as shown in FIG. 12, the segments 0 to 6 of the seven segment characters on the display panel 70 change from black display to white display and return to the display state 85 in FIG. Further, in the period 84 in FIG. 11, since 0 v is applied to all the electrodes, as shown in FIG. 12, the display state does not change and the display state 85 in FIG. 12 is maintained.

  Thus, in ternary driving, the voltage values applied to the segment electrodes are three voltage values of −V, 0, and V, and the voltage value applied to the common electrode is one voltage value of 0 v. It is.

  As a second conventional example, for example, an existing liquid crystal segment driver is used, and the drive output can take only binary values of 0v and + V. In the following description, this type of driving is referred to as “binary driving”. In the above binary drive, when the segment is to be changed from white display to black display, the common electrode is 0 V, the segment electrode is + V, and when the segment is to be changed from black display to white display, the common electrode is + V. The segment electrode is set to 0v. Since the common electrode is common to all the segments, it is obvious that the above two operations cannot be performed simultaneously.

  The merit of the first conventional example is that, compared to the second conventional example, a certain segment can be changed from white display to black display, and another segment can be changed simultaneously from black display to white display. The time required is short. Disadvantages are that there are as many as three types of power supply voltages, and the accompanying total power consumption increases.

  The merit of the second conventional example is that there are two types of power supply voltages as compared with the first conventional example, and the total power consumption can be reduced accordingly. Further, the disadvantage is that the time required for the display change becomes longer because the change from white display to black display and from black display to white display cannot be performed simultaneously.

  Thus, in order to adapt to the characteristics of the application, conventionally, two types of drive circuits are prepared: a drive circuit for implementing the first conventional example and a drive circuit for driving the second example. It was necessary to keep it. In addition, there is a problem that even if there is a case where it is desired to use the two types of drive circuits properly in one application, there is a problem.

Japanese Patent Laying-Open No. 2005-18021 (page 13, FIG. 9)

  The present invention has been made in view of such problems, and is configured so that the above two types of driving can be performed by one type of driving circuit, and can be used properly according to the characteristics of the application. The type of drive can be changed as necessary.

  The drive circuit of the present invention is a drive circuit that outputs a voltage applied to the segment electrode and a voltage applied to the common electrode, and there are a plurality of voltage values output from the drive circuit, and the segment electrode is derived from the plurality of voltage values. And a first variable means for varying the number of voltage values applied to the common electrode, and a second variable means for varying the number of voltage values applied to the common electrode from a plurality of voltage values. Features.

  Further, the first variable means varies the number of voltage values output from the drive circuit to the segment electrodes from three to two. Alternatively, the second variable means varies the number of voltage values output from the drive circuit to the common from two to one.

  The three voltage values are -V, 0, V, and the two voltage values are preferably 0, V, or the three voltage values are 0, V, 2V, and the two voltages The value may be 0, V.

  Alternatively, two voltage values are 0 and V, and one voltage value is preferably 0, or two voltage values are 0 and V, and one voltage value is V. Good.

  A display device of the present invention is a display device that includes a segment electrode and a common electrode, and performs black display and white display by applying a segment voltage and a common voltage, and the number of segment voltage values applied to the segment electrode and Means are provided for varying the number of common voltage values applied to the common electrode.

  The segment voltage value can be changed to one of three values of -V, 0, and V and two values of 0 and V, and the common voltage value is one value of 0 and two values of 0 and V. When the segment voltage value is three, the common voltage value is one value, and when the black or white display does not change, the segment voltage value becomes 0 and the black display When the segment voltage value changes to V, the segment voltage value changes to -V when changing to white display, and when the segment voltage value is 2, the common voltage value is two values of 0 and V. Yes, when the display of black or white display does not change, the segment voltage value becomes equal to the common voltage value. When the display changes to black display, the segment voltage value becomes V, the common voltage value becomes 0, and the display changes to white display When the segment voltage value is And then, the common voltage value, characterized in that the V.

  Alternatively, the segment voltage value can be varied between three values of 0, V, and 2V, and two values of 0 and V, and the common voltage value is one value of V and two values of 0 and V When the segment voltage value is three values, the common voltage value is one value of V. When the black display or white display does not change, the segment voltage value becomes V and the black When changing to display, the segment voltage value is set to 2V. When changing to white display, the segment voltage value is set to 0. When the segment voltage value is two values, the common voltage value is two values of 0 and V. When the display of black display or white display does not change, the segment voltage value is made equal to the common voltage value. When the display changes to black display, the segment voltage value is set to V, the common voltage value is set to 0, and the display is changed to white display. Sometimes segment The voltage value is set to 0, characterized in that the common voltage value V.

  As described above, according to the driving circuit or the display device of the present invention, it is possible to select the above-described two types of driving methods that are adapted to the characteristics of the application with one type of driving circuit. That is, it is possible to select ternary driving if importance is attached to high speed, and binary driving if importance is attached to low power consumption. In one application, it is possible to select ternary driving if high speed is important, and binary driving if low power consumption is important.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the display circuit to which the drive circuit or display device according to the present invention is applied and the relationship between the voltage applied to the display body and the change in the display state will be described. In the present invention, the configuration of the conventional display shown in FIG. 9 or the electrode configuration shown in FIG. 10 can be adopted.

  FIG. 1 shows a driving circuit according to a first embodiment of the present invention, a display panel connected to the driving circuit, and their connections. In FIG. 1, the drive circuit 1 is composed of eight segment drivers (2-1) to (2-8) and one common driver 3. The display panel 4 has eight segment electrodes (5-1) to (5-8) and one common electrode 6. The display panel 4 has the same configuration and appearance as the display panel 70 in FIG. 10 described above, and the segment electrodes (5-1) to (5-8) in FIG. 1 correspond to SEG0 to 6 and BG in FIG. The common electrode 6 in FIG. 1 corresponds to the COM in FIG.

  In the following description, n represents a number from 1 to 8. The eight segment drivers (2-1) to (2-8) each have three input terminals (2-na), (2-nb) and (2-nc), and three electronic switches (2 -Nd), (2-ne) and (2-nf) and one output terminal (2-ng). The electronic switch here refers to an electronic switching element such as a MOS transistor, for example, and includes a total of three terminals S and D connected to a main signal to be opened and closed and a terminal G connected to an opening and closing control signal. Has a terminal.

  The terminal S of the electronic switch (2-nd) in the segment driver (2-n) is connected to the positive voltage V, and the terminal S of the electronic switch (2-ne) is connected to 0v, and the electronic switch (2- The terminal S of nf) is connected to a negative voltage -V. The terminals D of the electronic switches (2-nd), (2-ne), and (2-nf) of the segment driver (2-n) are all connected to the output terminal (2-ng).

The terminal G of the electronic switch (2-nd) of the segment driver (2-n) is connected to the input terminal (2-na), and the terminal G of the electronic switch (2-ne) is connected to the input terminal (2-nb). The terminal G of the electronic switch (2-nf) is connected to the input terminal (2-nc). The output terminal (2-ng) of the segment driver (2-n) is connected to the segment electrode (5-n) of the display panel 4.

  When an ON signal is applied to the input terminal (2-na) of the segment driver (2-n), the electronic switch (2-nd) is turned on and the potential of the output terminal (2-ng) becomes V, resulting in a display panel V is applied to the four segment electrodes (5-n). Further, when an ON signal is applied to the input terminal (2-nb) of the segment driver (2-n), the electronic switch (2-ne) is turned on, and the potential of the output terminal (2-ng) becomes 0v, and as a result. 0 v is applied to the segment electrode (5-n) of the display panel 4. Further, when an ON signal is applied to the input terminal (2-nc) of the segment driver (2-n), the electronic switch (2-nf) is turned on, and the potential of the output terminal (2-ng) becomes −V. -V is applied to the segment electrode (5-n) of the result display panel 4.

  In addition, an ON signal is applied to the input terminals (2-na), (2-nb) and (2-nc) of the segment driver (2-n) so that -V, 0v and V are not short-circuited to each other. There shall be only one at a time.

  The terminal S of the electronic switch 3d of the common driver 3 is connected to the positive voltage V, and the terminal S of the electronic switch 3e is connected to 0v. All terminals D of the electronic switches 3d and 3e of the common driver 3 are connected to the output terminal 3g. The terminal G of the electronic switch 3d of the common driver 3 is connected to the input terminal 3a, and the terminal G of the electronic switch 3e is connected to the input terminal 3b. The output terminal 3g of the common driver 3 is connected to the common electrode 6 of the display panel 4.

  When an on signal is applied to the input terminal 3 a of the common driver 3, the electronic switch 3 d is turned on, the potential of the output terminal 3 g becomes V, and as a result, V is applied to the common electrode 6 of the display panel 4. When an on signal is applied to the input terminal 3b of the common driver 3, the electronic switch 3e is turned on, the potential of the output terminal 3g becomes 0v, and as a result, 0v is applied to the common electrode 6 of the display panel 4. Note that only one ON signal is applied to the input terminals 3a and 3b of the common driver 3 at the same time so that 0v and V are not short-circuited.

  Next, a case where the drive circuit 1 is operated as a ternary drive circuit will be described. In this case, the drive circuit 1 always uses the input terminal 3a of the common driver 3 as OFF, the input terminal 3b as always ON, and the output terminal 3g as 0V. The segment driver (2-n) uses three voltage values -V, 0v, and V as outputs as shown.

  FIG. 2 is a drive waveform diagram when the drive circuit 1 is used as a ternary drive circuit. A period 10 is a driving period for changing the display state of the display panel 4, and a period 11 is a display period after the change. A waveform 12 is a voltage waveform applied to the common electrode 6, and waveforms 13 to 16 are voltage waveforms applied to any of the segment electrodes (5-1) to (5-8). In the waveforms 13, 14, 15 and 16, the applied segments are (1) from white display to white display (not actually changed), (2) from white display to black display, and (3) from black display to white display. This is a voltage waveform that is applied when changing the display state to four patterns, from display to (4) black display to black display (not actually changed).

  FIG. 4 is an explanatory diagram when the drive circuit 1 performs ternary driving as shown in FIG. 2 and the display panel 4 is changed from the display state 30 (number 2) to the display state 31 (number 3). is there. In the initial display state 30, segments 0, 1, 3, 4, and 6 are black and segments 2, 5 and the background are white. In the display state 31 after the change, the segments 0, 1, 2, 3, and 6 are black, and the segments 4, 5 and the background are white.

  To change the display state as shown in FIG. 4, the waveform 12 in FIG. 2 is applied to the common electrode, and the segment 5 and the background change from white display to white display, so the waveform 13 in FIG. Since the segment 2 is a change from white display to black display, the waveform 14 in FIG. 2 is applied. Since the segment 4 is a change from black display to white display, the waveform 15 in FIG. Since segments 0, 1, 3 and 6 are changes from black display to black display, waveform 16 in FIG. 2 is applied.

  Next, a case where the drive circuit 1 is operated as a binary drive circuit will be described. In this case, the drive circuit 1 in FIG. 1 always turns off the input terminal (2-nc) of the segment driver (2-n) and uses two output values of 0 v and V for the output terminal (2-ng). . At this time, since the electronic switch (2-nf) is always OFF, it is not necessary to supply -V to the terminal S. That is, the voltage values output from the drive circuit are a plurality of + V, 0v, and −V, which are plural, but the three electronic switches (2-nd), (2-ne), and Using (2-nf), the number of voltage values applied to the segment electrodes was varied from three to two.

  The common driver 3 is used as a binary output of 0v and V. That is, the number of voltage values applied to the common electrode is varied from one to two in the above-described three-value driving by using the two electronic switches 3d and 3e as the second variable means.

  FIG. 3 is a drive waveform diagram when the drive circuit 1 in FIG. 1 is used as a binary drive circuit. A period 20 is a driving period for changing the display state of the display panel 4 in FIG. 1 from black display to white display, and a period 21 is a display after changing the driving period for changing the display state from white display to black display. The period 22 is a display period after the change.

  The waveform 23 is a voltage waveform applied to the common electrode 6, the waveforms 24a to 27a are voltage waveforms applied to any of the segment electrodes 5-1 to 5-8, and the waveforms 24b to 27b are the waveforms 24a to 27a, respectively. It is the relative voltage waveform which looked at electric potential from common electric potential. The relative voltage actually applied between the common electrode 6 and any one of the segment electrodes (5-1) to (5-8) has waveforms 24b to 27b.

  Waveforms 24, 25, 26 and 27 in FIG. 3 indicate that the applied segments are (1) from white display to white display (not actually changed), (2) from white display to black display, (3) This is a voltage waveform applied when changing from black display to white display and (4) black display to black display. Unlike the waveform 16 in FIG. 2, the waveform 27 for changing from black display to black display changes the segment from black display to white display and then returns to black display. The reason for this will be described later.

  Here, the difference between the ternary driving in FIG. 2 and the binary driving in FIG. 3 will be described. In the ternary driving of FIG. 2, changes in (white display to black display) and (black display to white display) can be generated simultaneously in period 10, whereas in the binary driving of FIG. The change in white ideogram can only occur in period 20 and the change in (white display to black display) can only occur in period 21. That is, in the binary driving shown in FIG. 3, it is not possible to cause changes in (white display to black display) and (black display to white display) at the same time.

This is due to the following reason. That is, in the ternary drive, the potential of each segment voltage can take three values of -V, 0v, V with respect to the potential of the common voltage. And a negative voltage can be simultaneously applied to the other segments. On the other hand, in binary driving, the segment voltage can take only binary values of 0v and V. Therefore, in order to make the segment voltage potential positive with respect to the common voltage potential, the common potential is set to 0v and the segment potential is set to In order to set V and the segment potential to be negative with respect to the common potential, the common potential must be V and the segment potential must be 0 v. Therefore they cannot be generated simultaneously.

  FIG. 5 is an explanatory diagram in a case where the drive circuit 1 is binary driven to change the display panel 4 from the display state 32 (number 2) to the display state 34 (number 3). In display state 32 in FIG. 5, segments 0, 1, 3, 4, and 6 are black, and segments 2, 5 and the background are white. In the final display state 34, segments 0, 1, 2, 3, and 6 are black and segments 4, 5 and the background are white.

  In the case of implementing such a display state, the waveform 23 in FIG. 3 is applied to the common electrode, and the waveform 24 is applied to the segment 5 and the background because of the change from white display to white display. Waveform 25 is applied because 2 is a change from white to black, waveform 26 is applied because segment 4 is a change from black to white, and segments 0, 1, 3, and 6 are changes from black to black. Waveform 27 is applied.

  As shown in FIG. 5, in the process of changing from the display state 32 to the display state 34, a second display state 33 in which all the segments including the background once become white appears. This phenomenon is shown in FIG. It depends on the driving waveform of binary driving shown. The reason will be described below. In the period 20 in FIG. 3, since the drive can only be changed from (black display to white display) as described above, the segments 2 and 5 that change (white display to white display) and (white display to black display) change. The background does not change, and only the segments 0, 1, 3, 4, and 6 that change (black display to white display) and (black display to black display) change from black display to white display. As a result, all the segments including the background are once displayed in white as in the display state 33 in FIG.

  In the period 21 in FIG. 3, as described above, since the drive can only be changed from (white display to black display), the segments 4 that change (white display to white display) and (black display to white display) change. 5 and the background do not change, and segments 0, 1, 2, 3, and 6 that change from (white display to black display) and (black display to black display) change from white display to black display. As a result, the display panel 4 is in a final display state 34 in FIG.

  Next, a supplementary explanation of the waveform 27 for changing from black display to black display in the drive waveform diagram of FIG. The drive waveform 27 in FIG. 3 for changing from binary drive (black to black) is different from the waveform 16 in FIG. 2 in that the segment is temporarily changed from black display to white display and then returned to black display. FIG. 6 shows that the drive waveform 27 in FIG. 3 does not cause any display change, similar to the ternary drive waveform 16 in FIG. That is, the display change of the display panel 4 when the waveform 27b holds 0v in the periods 20 and 21 is shown.

  6, the initial display state 35 and the final display state 37 are the same as the initial display state 32 and the final display state 34 of FIG. 5 respectively, but the first display state 35 and the final display state 37 appear in the process of changing from the display state 35 to the display state 37 in FIG. In the second display state 36, the display state is not intended as shown in FIG. This is because segments 0, 1, 3 and 6 which change from black to black continue to be in a black state without any change.

In order to prevent such an unintended display state from appearing, the drive waveform 27 in FIG. 3 is a drive waveform in which when a segment changes (from black display to black display), the display is once displayed in white and then displayed in black. And

  FIG. 7 shows a drive circuit according to a second embodiment of the present invention, a display panel connected to the drive circuit, and their connections. In FIG. 7, the drive circuit 41 comprises eight segment drivers (42-1) to (42-8) and one common driver 43, and the display panel 4 is the same as that shown in FIG. 1 of the first embodiment. It has eight segment electrodes (5-1) to (5-8) and one common electrode 6.

  The eight segment drivers (42-1) to (42-8) each have three input terminals (42-na), (42-nb) and (42-nc), and 3 as a first variable means. There are one electronic switch (42-nd), (42-ne) and (42-nf) and one output terminal (42-ng). The terminal S of the electronic switch (42-nd) of the segment driver (42-n) is connected to the positive voltage 2V, the terminal S of the electronic switch (42-ne) is connected to V, and the electronic switch (42-nf) The terminal S is connected to a negative voltage 0v. The terminals D of the electronic switches (42-nd), (42-ne) and (42-nf) of the segment driver (42-n) are all connected to the output terminal (42-ng).

  The terminal G of the electronic switch (42-nd) of the segment driver (42-n) is connected to the input terminal (42-na), and the terminal G of the electronic switch (42-ne) is connected to the input terminal (42-nb). The terminal G of the electronic switch (42-nf) is connected to the input terminal (42-nc). The output terminal (42-ng) of the segment driver (42-n) is connected to the segment electrode (5-n) of the display panel 4.

When an on signal is applied to the input terminal (42-na) of the segment driver (42-n), the electronic switch (42-nd) is turned on, and the potential of the output terminal (42-ng) becomes 2V, resulting in a display panel. 2 V is applied to the four segment electrodes (5-n). When an ON signal is applied to the input terminal (42-nb) of the segment driver (42-n), the electronic switch (42-ne) is turned on, and the potential of the output terminal (42-ng) becomes V, resulting in a display panel. V is applied to the four segment electrodes (5-n). When an on signal is applied to the input terminal (42-nc) of the segment driver (42-n), the electronic switch (42-nf) is turned on, and the potential of the output terminal (42-ng) becomes 0v, resulting in a display panel. 0v is applied to the four segment electrodes (5-n). In addition, an ON signal is applied to the input terminals (42-na), (42-nb) and (42-nc) of the segment driver (42-n) so that 0v, V and 2V are not short-circuited to each other. There shall be only one at a time.

  The terminal S of the electronic switch 43d of the common driver 43 is connected to the positive voltage V, and the terminal S of the electronic switch 43e is connected to 0v. All terminals D of the electronic switches 43d and 43e of the common driver 43 are connected to the output terminal 43g. The terminal G of the electronic switch 43d of the common driver 43 is connected to the input terminal 43a, and the terminal G of the electronic switch 43e is connected to the input terminal 43b. The output terminal 43 g of the common driver 43 is connected to the common electrode 6 of the display panel 4.

  When an ON signal is applied to the input terminal 43a of the common driver 43, the electronic switch 43d is turned on, the potential of the output terminal 43g becomes V, and as a result, V is applied to the common electrode 6 of the display panel 4. When an on signal is applied to the input terminal 43b of the common driver 43, the electronic switch 43e is turned on, the potential of the output terminal 43g becomes 0v, and as a result, 0v is applied to the common electrode 6 of the display panel 4. Note that only one ON signal is applied to the input terminals 43a and 43b of the common driver 43 at the same time so that 0v and V are not short-circuited.

Next, the case where the drive circuit 41 is operated as a ternary drive circuit will be described. In this case, the drive circuit 41 always turns on the input terminal 43a of the common driver 43 and the input terminal 43b.
Is always OFF, and its output terminal 43g is always used as V. The segment driver (42-n) is used as a three-value output of 0v, V, and 2V.

  FIG. 8 is a drive waveform diagram when the drive circuit 41 is used as a ternary drive circuit. The period 50 is a drive period for changing the display state of the display panel 4, and the period 51 is a display period after the change. A waveform 52 is a voltage waveform applied to the common electrode 6, and waveforms 53 to 56 are voltage waveforms applied to any of the segment electrodes (5-1) to (5-8). Waveforms 53, 54, 55, and 56 indicate that the applied segment changes from white display to white display (not actually changed), white display to black display, black display to white display, black display to black display (actual This is a voltage waveform applied when changing to (not changing).

  The drive circuit 41 is ternary driven with reference to FIG. 4, and the display panel 4 is changed from the display state 30 (number 2) to the display state 31 (number 3) by the drive waveform shown in FIG. Do. In the initial display state 30, segments 0, 1, 3, 4, and 6 are black and segments 2, 5 and the background are white. In the display state 31 after the change, the segments 0, 1, 2, 3, and 6 are black, and the segments 4, 5 and the background are white.

  When the display state changes, the waveform 52 is applied to the common, the waveform 53 is applied because the segment 5 and the background are white to white, and the waveform 54 is applied because the segment 2 is the white to black. Since segment 4 is a change from black to white, waveform 55 is applied, and since segments 0, 1, 3 and 6 are a change from black to black, waveform 56 is applied.

  Next, a case where the drive circuit 41 is operated as a binary drive circuit will be described. In this case, the drive circuit 41 always turns off the input terminal (42-na) of the segment driver (42-n) and uses the output terminal (42-ng) as a binary output of 0v and V. The common driver 3 is used as a binary output of 0v and V. At this time, since the electronic switch (42-nd) is always OFF, it is not necessary to supply 2V to the terminal S.

  Changes in the drive waveform diagram and the display state of the display panel 4 when the display panel 4 is driven using the drive circuit 41 as a binary drive circuit are as shown in FIGS. 3 and 5, respectively. The reason why the waveform 27 for changing the segment of FIG. 3 from black to black is different from the waveform 56 of FIG. 8 is the same as in the first embodiment.

  In this way, the segment voltage can be easily varied by either binary driving or ternary driving. Therefore, if a mechanism that automatically switches according to the application or a mechanism that can be easily switched by an operator is provided, ternary driving can be achieved with one type of drive circuit if high speed is important. If the emphasis is placed on the binary driving, it is possible to carry out binary driving.

FIG. 3 is a connection diagram of a driving circuit and a display panel according to the first embodiment of the present invention. FIG. 3 is a drive waveform diagram of ternary drive according to the first embodiment of the present invention. FIG. 6 is a drive waveform diagram of binary drive according to the first and second embodiments of the present invention. The display panel display state transition diagram of ternary drive in the present invention. The display panel display state transition diagram of the binary drive in this invention. The display panel display state transition diagram of the unpreferable binary drive concerning this invention. FIG. 6 is a connection diagram of a drive circuit and a display panel according to a second embodiment of the present invention. The drive waveform figure of the ternary drive which concerns on the 2nd Example of this invention. Sectional drawing of the display body of this invention. The display panel figure comprised using the display body shown in FIG. The drive waveform figure of the drive circuit which concerns on this invention. The display state transition diagram of the display panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive circuit 2-1, 2-2, 2-3, 2-4, 2-5, 2-5, 2-6, 2-7, 2-8 ... Segment driver 3 ... Common driver 4 ... Display panel 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8 ... Segment electrode 6 ... Common electrode 41... Drive circuit 42-1, 42-2, 42-3, 42-4, 42-5, 42-5, 42-6, 42-7, 42-8 ... segment driver 43 ... Common driver 60 ... Display body 61 ... Common electrode 62 ... Display element 63 ... Segment electrode 64 ... FPC
70 ... Display panel

Claims (10)

  A drive circuit that outputs a voltage applied to the segment electrode and a voltage applied to the common electrode, wherein there are a plurality of voltage values output from the drive circuit, and a voltage value applied to the segment electrode from the plurality of voltage values And a second variable means for varying the number of voltage values applied to the common electrode from the plurality of voltage values. .   2. The drive circuit according to claim 1, wherein the first variable means varies the number of voltage values output from the drive circuit to the segment electrodes from three to two.   2. The drive circuit according to claim 1, wherein the second variable means varies the number of voltage values output from the drive circuit to the common electrode from two to one.   The drive circuit according to claim 2, wherein the three voltage values are -V, 0, and V, and the two voltage values are 0 and V.   3. The drive circuit according to claim 2, wherein the three voltage values are 0, V, and 2V, and the two voltage values are 0 and V.   4. The drive circuit according to claim 3, wherein the two voltage values are 0 and V, and the one voltage value is 0.   4. The drive circuit according to claim 3, wherein the two voltage values are 0 and V, and the one voltage value is V.   A display device having a segment electrode and a common electrode, and performing black display and white display by applying a segment voltage and a common voltage, the number of segment voltage values applied to the segment electrode and the common applied to the common electrode A display device comprising means for varying the number of voltage values. The segment voltage value is variable to one of three values of -V, 0, and V and two values of 0 and V,
The common voltage value is variable between one value of 0 and two values of 0 and V,
When the segment voltage value is the three values, the common voltage value is one value of 0, and when the display of black display or white display does not change, the segment voltage value becomes 0,
When changing to black display, set the segment voltage value to V,
When changing to white display, set the segment voltage value to -V,
When the segment voltage value is 2, the common voltage value is two values of 0 and V. When the display of black display or white display does not change, the segment voltage value is the same as the common voltage value. Equal,
When changing to black display, the segment voltage value is V, the common voltage value is 0,
9. The display device according to claim 8, wherein when changing to white display, the segment voltage value is set to 0 and the common voltage value is set to V. The segment voltage value is variable to one of three values of 0, V, and 2V, and two values of 0 and V,
The common voltage value is variable to one value of V and two values of 0 and V,
When the segment voltage value is three values, the common voltage value is one value of V;
When the display of black display or white display does not change, the segment voltage value becomes V,
When changing to black display, set the segment voltage to 2V,
When changing to white display, the segment voltage value is set to 0,
When the segment voltage value is two values, the common voltage value is two values of 0 and V. When the black display or white display does not change, the segment voltage value is made equal to the common voltage value. ,
When changing to black display, the segment voltage value is V, the common voltage value is 0,
9. The display device according to claim 8, wherein when the display is changed to white display, the segment voltage value is set to 0, and the common voltage value is set to V.

Images