Display device

• US 5,748,169 A
• Filed: 03/12/1996
• Issued: 05/05/1998
• Est. Priority Date: 03/15/1995
• Status: Expired due to Term

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Itoh, Goh, Okumura, Haruhiko
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US08/615,161
• Time in Patent Office: 784 Days
• Field of Search: 345/98, 345/99, 345/100, 345/94, 345/95, 345/96, 345/90, 345/92, 345/93, 345/87, 345/88, 345/89, 345/101, 345/103, 348/790, 348/791, 348/792, 348/793, 349/33, 349/34, 349/37, 349/38, 349/39
• US Class Current: 345/100
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A display device comprises a plurality of address lines arranged in a horizontal direction, a plurality of signal lines, arranged in a vertical direction, for transmitting an image signal, a plurality of pixels, arranged in a matrix at intersections between the plurality of address lines and the plurality of signal lines, each pixel including a display element, and a switch element which is connected between a corresponding one of the plurality of signal lines and the display element and which is controlled to be on or off under control of a corresponding one of the plurality of address lines, and compensating means for supplying, through the corresponding one of the plurality of address lines to the display element, a compensation signal for compensating a change in potential applied to the display element.

Claims

1. A display device comprising:

a substrate;

a plurality of address lines arranged in a horizontal direction on the substrate;

a plurality of signal lines, arranged in a vertical direction on the substrate, for transmitting an image signal;

a plurality of pixels, arranged in a matrix at intersections between the plurality of address lines and the plurality of signal lines on the substrate, each pixel including a display element, and a switch element which is connected between a corresponding one of the plurality of signal lines and the display element and which is controlled to be on or off by a corresponding one of the plurality of address lines; and

compensating means for supplying, through the corresponding one of the plurality of address lines to the display element, a compensation signal for compensating a change in potential, the potential being applied to the display element while the switch element is controlled to be on, in a period between just after the switch element is controlled to be off and before the switch element is controlled to be on again, in order to compensate the chance in the potential.

2. The display device according to claim 1, wherein the compensating means output as the compensation signal, a signal having a potential which varies stepwise in one of positive and negative directions with a lapse of time in the period in which the switch element is controlled to be off.

3. The display device according to claim 1, wherein the compensating means output as the compensation signal, a signal having a potential which varies linearly in one of positive and negative directions with a lapse of time.

4. The display device according to claim 1, wherein the compensating means output as the compensation signal, a signal having a potential which varies in accordance with at least one of a polarity of the image signal supplied to the corresponding one of the signal lines, a potential thereof, and a position of the pixel in the matrix.

5. The display device according to claim 2, wherein the compensating means output as the compensation signal, a signal having a cyclic period of about 1/n (n=an integer ≧

2) of that of a signal for driving the switch element.

6. The display device according to claim 3, wherein the compensating means output as the compensation signal, a signal having a cyclic period of about 1/n (n=an integer ≧

2) of that of a signal for driving the switch element.

7. The display device according to claim 2, further comprising driver circuits for driving the plurality of address lines, each of the driver circuits including a sample-hold circuit for maintaining a value of the compensation signal to be stepwise.

8. The display device according to claim 1, wherein the compensating means output as the compensation signal, a signal in which at least one of an absolute value of the potential applied to the display element and a period of change of the potential is varied in accordance with an amount of light applied to the switch element.

9. The display device according to claim 1, wherein the compensating means output as the compensation signal, a signal in which at least one of an absolute value of the potential applied to the display element and a period of change of the potential is varied in accordance with a period in which the switch element is driven.

10. The display device according to claim 1, wherein each of the pixels further comprises a capacitor element connected to the display element to store the image signal and a capacitor line for applying a potential to the capacitor element, and the compensating means supply the compensation signal to the capacitor line.

11. The display device according to claim 10, wherein the capacitor line is connected to one of the plurality of address lines, which is assigned to one of the plurality of pixels adjacent in the vertical direction.

12. A liquid crystal display device comprising:

a substrate;

a plurality of pixels arranged in rows and columns on the substrate, each of the pixels including a liquid crystal display element having a first and a second electrode, a capacitor element having a first and a second terminal and a switch element for selecting the liquid crystal display element, the switch element including a conductive path having a first and a second terminal and a control electrode for controlling a conduction state of the conductive path, wherein the first terminal of the switch element is connected to the first electrode of the liquid crystal display element and the first terminal of the capacitor element, and the second terminal of the capacitor element is connected to the control electrode of a switch element adjacent in a row direction;

a plurality of address lines arranged in the row direction on the substrate, each of the address lines being connected to the control electrode of the switch element of each of the plurality of pixels arranged along the address lines;

a plurality of signal lines arranged in a column direction on the substrate, each of the signal lines being connected to the second terminal of the conductive path of each of the plurality of pixels arranged along the signal lines and supplying an image signal to the liquid crystal display element through the switch element; and

an address line driver for selectively driving the plurality of address lines,

wherein the address line driver comprises compensation signal supplying means for performing an interlaced driving operation for selecting desired ones of the address lines separated from one another with a predetermined number of address lines interposed therebetween, the interlaced driving operation dividing one frame into a predetermined number of fields, and for supplying a compensation signal for compensating a change in potential, the potential being applied to the liquid crystal display element while the switch element is controlled to be on, to one of the address lines which is adjacent in the row direction and is coupled to the control electrode of the switch element adjacent in the row direction, the control electrode being connected to the second terminal of the capacitor element, in a period between just after the switch element of each of the plurality of pixels connected to one of the desired address lines is controlled to be off and before the same is controlled to be on again, in order to compensate the change in the potential.

13. The liquid crystal display device according to claim 12, wherein the address line driver further comprises:

a plurality of address signal generating means for generating an address signal corresponding to the plurality of address lines;

address signal selecting means for determining an address signal to be driven, based on the address signal and an interlace selection signal supplied from an external device; and

compensation signal generating means for generating the compensation signal from the address signal and a compensation source signal supplied from an external device.

14. The liquid crystal display device according to claim 13, wherein the compensation signal generating means includes sample-hold means for sample-holding in synchronization with the address signal a voltage of the compensation source signal, having an absolute value which varies linearly every frame with a lapse of time, and outputting a step-like signal as the compensation signal.

15. The liquid crystal display device according to claim 12, wherein the compensation signal supplying means output, as the compensation signal, a signal which is varied greatly in one field, in a case where the image signal supplied to the signal line in a preceding field has a polarity the same as that of a pixel signal applied to the liquid crystal display element, and varied little in one field, in a case where the image signal supplied to the signal line in a preceding field has a polarity opposite to that of a pixel signal applied to the liquid crystal display element.

16. The liquid crystal display device according to claim 12, wherein each of the plurality of signal lines supplies, as the image signal, a signal whose polarity is varied every field, to the liquid crystal display element.

17. The liquid crystal display device according to claim 12, wherein the compensation signal supplying means output, as the compensation signal, a signal having an absolute value which varies linearly with a lapse of time, and a potential of the pixel is maintained to be substantially constant in each frame.

18. A liquid crystal display device comprising:

a substrate;

a plurality of pixels arranged in rows and columns on the substrate, each of the pixels including a liquid crystal display element having a first and a second electrode, a capacitor element having a first and a second terminal and a switch element for selecting the liquid crystal display element, the switch element including a conductive path having a first and a second terminal and a control electrode for controlling a conduction state of the conductive path, wherein the first terminal of the switch element is connected to the first electrode of the liquid crystal display element and the first terminal of the capacitor element, and the second terminal of the capacitor element is connected to the control electrode of the switch element in an adjacent one of the pixels in a row direction;

a plurality of address lines arranged in the row direction on the substrate, each of the address lines being connected to the control electrode of the switch element of each of the plurality of pixels arranged along the address lines; and

a plurality of signal lines arranged in a column direction on the substrate, each of the signal lines being connected to the second terminal of the conductive path of each of the plurality of pixels arranged along the signal lines and supplying an image signal to the liquid crystal display element through the switch element,

wherein the image signal is cyclically applied to the liquid crystal display element at a predetermined period by means of the switch; and

a compensation signal is superimposed on each of the address lines, to compensate a change in potential of the liquid crystal display element, which has been applied while the control gate of the switch is controlled to be on, and is cyclically applied every about 1/n (n=an integer which is equal to two or more) of the predetermined period, in a period between just after the switch is controlled to be off and before the switch is controlled to be on again.

19. A liquid crystal display device comprising:

a substrate;

a plurality of pixels arranged in rows and columns on the substrate, each of the pixels including a liquid crystal display element having a first and a second electrode, a capacitor element having a first and a second terminal and a switch element for selecting the liquid crystal display element, the switch element including a conductive path having a first and a second terminal and a control electrode for controlling a conduction state of the conductive path, wherein the first terminal of the switch element is connected to the first electrode of the liquid crystal display element and the first terminal of the capacitor element;

a plurality of capacitor lines formed on the substrate, each connected to the second terminal of the capacitor element;

a plurality of address lines arranged in the row direction on the substrate, each of the address lines being connected to the control electrode of the switch element of each of the plurality of pixels arranged along the address lines;

a plurality of signal lines arranged in a column direction on the substrate, each of the signal lines being connected to the second terminal of the conductive path of the switch element of each of the plurality of pixels arranged along the signal lines and supplying an image signal to the liquid crystal display element through the switch element; and

an address line driver for selectively driving the plurality of address lines,

wherein each of the capacitor lines supplies a compensation signal for compensating a change in potential of the liquid crystal element, the potential having been applied to the liquid crystal display element while the control gate of the switch is controlled to be on, in a period between just after the switch element is controlled to be off and before the switch is controlled to be on again, in order to compensate the change in the potential.

20. A liquid crystal display device comprising:

a substrate;

a plurality of address lines arranged in a horizontal direction on the substrate;

a plurality of signal lines, arranged in a vertical direction on the substrate, for transmitting an image signal;

a plurality of pixels, arranged on the substrate at intersections between odd number-th address lines counted from an end of the plurality of address lines and odd number-th signal lines counted from an end of the plurality of signal lines, and intersections between even number-th address lines counted from the end of the plurality of address lines and even number-th signal lines counted from the end of the plurality of signal lines, each pixel including a display element, and a switch element which is connected between a corresponding one of the plurality of signal lines and the display element and which is controlled to be on or off under control of a corresponding one of the plurality of address lines; and

compensating means for supplying, through the corresponding one of the plurality of address lines to the display element, a compensation signal for compensating a change in potential applied to the display element.

21. The liquid crystal display device according to claim 20, wherein the plurality of signal lines supply, as the image signal, signals having polarities, which are different from each other in adjacent lines and inverted every screen.

22. The liquid crystal display device according to claim 20, wherein the compensating means output as the compensation signal, a signal having a potential which varies stepwise in one of positive and negative directions with a lapse of time in a period in which the switch element is controlled to be off, in order to compensate the change in the potential applied to the display element in a period in which the switch element is controlled to be on.

23. The liquid crystal display device according to claim 20, wherein the compensating means output as the compensation signal, a signal having a potential which varies linearly in one of positive and negative directions with a lapse of time.

24. The liquid crystal display device according to claim 20, wherein the compensating means output as the compensation signal, a signal having a potential which varies in accordance with at least one of a polarity of the image signal supplied to the corresponding one of the signal lines, a potential thereof, and a position of the pixel in the matrix.

25. The liquid crystal display device according to claim 22, wherein the compensating means output as the compensation signal, a signal having a period of about 1/n (n=an integer ≧

2) of that of a signal for driving the switch element.

26. The liquid crystal display device according to claim 23, wherein the compensating means output as the compensation signal, a signal having a period of about 1/n (n=an integer ≧

2) of that of a signal for driving the switch element.

27. The liquid crystal display device according to claim 22, further comprising driver circuits for driving the plurality of address lines, each of the driver circuits including a sample-hold circuit for maintaining a value of the compensation signal to be stepwise.

28. The liquid crystal display device according to claim 20, wherein the compensating means output as the compensation signal, a signal in which at least one of an absolute value of the potential applied to the display element and a period of change of the potential is varied in accordance with an amount of light applied to the switch element.

29. The liquid crystal display device according to claim 20, wherein the compensating means output as the compensation signal, a signal in which at least one of an absolute value of the potential applied to the display element and a period of change of the potential is varied in accordance with a period in which the switch element is driven.

30. The liquid crystal display device according to claim 20, wherein each of the pixels further comprises a capacitor element connected to the display element to store the image signal and a capacitor line for applying a potential to the capacitor element, and the compensating means supply the compensation signal to the capacitor line.

31. The liquid crystal display device according to claim 30, wherein the capacitor line is connected to one of the plurality of address lines, which is assigned to one of the plurality of pixels adjacent in the vertical direction.

32. A liquid crystal display device comprising:

a substrate;

a plurality of pixels arranged in rows and columns on the substrate, each of the pixels including a liquid crystal display element having a first and a second electrode, a capacitor element having a first and a second terminal, a first and a second switch element for selecting the liquid crystal display element, each of the first and the second switch element including a conductive path having a first and a second terminal and a control electrode for controlling a conduction state of the conductive path, wherein the first terminal of the first switch element is connected to the control electrode of the second switch element and the first terminal of the capacitor element, and the first terminal of the second switch element is connected to the first electrode of the liquid crystal display element;

a plurality of capacitor lines formed on the substrate, each connected to the second terminal of the capacitor element;

a plurality of liquid crystal element driving lines formed on the substrate, each connected to the second terminal of the second switch element;

a plurality of address lines arranged in the row direction on the substrate, each of the address lines being connected to the control electrode of the first switch element of each of the plurality of pixels arranged along the address lines;

a plurality of signal lines arranged in a column direction on the substrate, each of the signal lines being connected to the second terminal of the conductive path of the first switch element of each of the plurality of pixels arranged along the signal lines and supplying an image signal to the liquid crystal element through the first switch element; and

an address line driver for selectively driving the plurality of address line,

wherein each of the capacitor lines supplies a compensation signal for compensating a change in potential applied to the liquid crystal display element.

33. The liquid crystal display device according to claim 32, wherein each of the capacitor lines is connected to one of the plurality of address lines adjacent in the vertical direction.