Method and apparatus for driving a capacitive flat matrix display panel

• US 5,206,631 A
• Filed: 04/22/1991
• Issued: 04/27/1993
• Est. Priority Date: 04/25/1990
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Harada, Shigeyuki, Yamamoto, Kyoichi, Sakamoto, Atsushi, Ohba, Toshihiro, Kishishita, Hiroshi
• Primary Examiner(s): Chin, Tommy
• Assistant Examiner(s): Au, A.
• Application Number:
  US07/688,144
• Time in Patent Office: 736 Days
• Field of Search: 340/781, 340/760, 340/805, 340/811, 340/825.11, 315/169.3
• US Class Current: 345/79
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0281 Arrangement of scan or data electrode driver circuits at the periphery of a panel not inherent to a split matrix structure
• CPC Class Codes: G09G 3/30 using electroluminescent panels

Abstract

In a display device having a plurality of scanning-side electrodes arranged in one direction, a plurality of data-side electrodes arranged in a second direction intersection the first direction, and dielectric layers interposed therebetween, a modulated voltage the magnitude of which is varied according to the emission or non-emission of light is applied to the data-side electrodes, while applying a write voltage in line sequential fashion to the scanning-side electrodes, thereby performing the display control. In such a display device, the polarity of the voltage applied between the data-side electrode and the scanning-side electrode corresponding to the picture element to be driven for light emission is reversed one or more times during the period in which the write voltage is being applied to the scanning-side electrode. This serves to reduce the modulated voltage and the write voltage, thus contributing to the reduction in power consumption. Even when the modulated voltage or the write voltage is reduced, the desired brightness of emitted light can be obtained. In the case of not lowering the modulated voltage or the write voltage, it is possible to further enhance the brightness of emitted light.

Claims

1. A method of driving a display device having a plurality of scanning-side electrodes extending in one direction, a plurality of data-side electrodes extending in a second direction intersecting the first direction, and dielectric layers interposed therebetween, picture elements being formed at intersections of the scanning-side electrodes and data-side electrodes, the picture elements being driven by applying a modulated voltage, the magnitude thereof being varied according to the emission or non-emission of light, to the data-side electrodes, while applying a write voltage in line sequential fashion to alternately divided odd number scanning-side electrodes and even number scanning-side electrodes, so that a voltage including the applied modulated and write voltage exceeding the emitting threshold voltage of the picture element is applied for emission of light and a voltage including the applied modulated and write voltages below the emitting threshold voltage is applied for non-emission of light, the method comprising:

reversing the polarity of the voltage including the modulated and write voltages applied between the data-side electrode and the scanning-side electrode corresponding to the picture element to be driven for light emission, one or more times during a period required to scan a single picture element on the scanning-side electrode.

12. A method according to claim 1, wherein the polarity of the voltage including the applied modulated and write voltages is reversed twice during the period required to scan a single scanning-side electrode.

13. A method according to claim 1, wherein the polarity of the voltage including the applied modulated and write voltages is reversed three times during the period required to scan a single scanning-side electrode.

14. A method according to claim 1, wherein the magnitude of the reversed polarity voltage is substantially constant.

2. A driving device for a display device having a plurality of scanning-side electrodes, a plurality of data-side electrodes, and dielectric layers interposed therebetween, picture elements being formed at intersections of the scanning-side electrodes and data-side electrodes, comprising:

scanning-side electrode driving means connected to the plurality of odd number scanning-side electrodes and even number scanning-side electrodes for applying a positive or negative polarity write voltage to the scanning-side electrodes;

data-side electrode driving means connected to the plurality of data-side electrodes which, when a picture element on the scanning-side electrode supplied with a write voltage is to be driven for light emission, applies a modulating voltage that cooperates with each write voltage to set a cumulative voltage of the applied modulated and write voltages applied to picture element above a threshold voltage, to the corresponding data-side electrode, and when the picture element is not driven for light emission, applies a modulating voltage, which cooperates with each write voltage to set a cumulative voltage of the applied modulated and write voltages applied to picture element below a threshold voltage, to the corresponding data-side electrode; and

display control means for controlling the scanning-side electrode driving means and the data-side electrode driving means and reversing the polarity of said cumulative voltage applied between the data-side electrode and the scanning-side electrode corresponding to the picture element to be driven for light emission, one or more times during the period required to scan a single picture element on the scanning-side electrode.

3. A driving device for a display device as set forth in claim 2, wherein the scanning-side electrode driving means comprising:

odd-numbered electrode driving circuits for applying the write voltage to the odd-numbered scanning-side electrodes; and

even-numbered electrode driving circuits for applying the write voltage to the even-numbered scanning-side electrodes.

4. A driving device for a display device as set forth in claim 3, wherein the scanning-side electrode driving means comprises:

a first potential switching circuit for switching the voltage applied to odd-numbered and even-numbered electrode driving circuits between a voltage of positive polarity and a voltage of 0 V; and

a second potential switching circuit for switching the voltage applied to odd-numbered and even-numbered electrode driving circuits between a voltage of negative polarity and a voltage of 0 V.

5. A driving device for a display device as set forth in claim 4, wherein the odd-numbered electrode driving circuits comprise:

a first driving circuit for applying the voltage supplied from the first potential switching circuit to the scanning-side electrodes; and

a second driving circuit for applying the voltage supplied from the second potential switching circuit to the scanning-side electrodes.

6. A driving device for a display device as set forth in claim 5, wherein the even-numbered electrode driving circuits comprise:

a third driving circuit for applying the voltage supplied from the first potential switching circuit to the scanning-side electrodes; and

a fourth driving circuit for applying the voltage supplied from the second potential switching circuit to the scanning-side electrodes.

7. A driving device for a display device as set forth in claim 5, wherein the first driving circuit comprises:

a plurality of p-channel MOS transistors to the drains of which the scanning-side electrodes are connected and to the sources of which the first potential switching circuit is connected; and

a first logic circuit to which the gates of the plurality of p-channel MOS transistors are connected and which applies a high level signal to the gate of the p-channel MOS transistor connected to the scanning electrode to be supplied with the write voltage.

8. A driving device for a display device as set forth in claim 5, wherein the second driving circuit comprises:

a plurality of n-channel MOS transistors to the drains of which the scanning-side electrodes are connected and to the sources of which the second potential switching circuit is connected; and

a second logic circuit to which the gates of the plurality of n-channel MOS transistors are connected and which applies a high level signal to the gate of the n-channel MOS transistor connected to the scanning electrode to be supplied with the write voltage.

9. A driving device for a display device as set forth in claim 6, wherein the third driving circuit comprises:

a plurality of p-channel MOS transistors to the drains of which the scanning-side electrodes are connected and to the sources of which the first potential switching circuit is connected; and

a third logic circuit to which the gates of the plurality of p-channel MOS transistors are connected and which applies a high level signal to the gate of the p-channel MOS transistor connected to the scanning electrode to be supplied with the write voltage.

10. A driving device for a display device as set forth in claim 6, wherein the fourth driving circuit comprises:

a plurality of n-channel MOS transistors to the drains of which the scanning-side electrodes are connected and to the sources of which the second potential switching circuit is connected; and

a fourth logic circuit to which the gates of the plurality of n-channel MOS transistors are connected and which applies a high level signal to the gate of the n-channel MOS transistor connected to the scanning electrode to be supplied with the write voltage.

11. A driving device for a display device as set forth in claim 2, wherein the data-side driving means comprises:

a plurality of pull-up switching elements, one each provided for each data-side electrode, for applying the modulated voltage to the data-side electrodes;

a plurality of pull-down switching elements, one each provided for each data-side electrode, for applying the reference voltage of 0 V to the data-side electrodes; and

element control circuits for controlling the switching of the pull-up switching elements and pull-down switching elements for every one of the data-side electrodes in such a manner that when either one of the switching elements is on, the other is off.

15. A driving device for a display device as set forth in claim 2, wherein the display control means reverses the polarity of the cumulative voltage twice during the period required to scan a single scanning-side electrode.

16. A driving device for a display device as set forth in claim 2, wherein the display control means reverses the polarity of the cumulative voltage three times during the period required to scan a single scanning-side electrode.

17. A driving device according to claim 2, wherein the magnitude of the reversed polarity voltage is substantially constant.