Display apparatus and drive control method thereof

• US 7,868,880 B2
• Filed: 05/23/2006
• Issued: 01/11/2011
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: Solas OLED Limited (Atlantic IP Services Limited)
• Original Assignee: Casio Computer Company Limited
• Inventors: Ozaki, Tsuyoshi, Ogura, Jun
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US11/438,967
• Publication Number:
  US 20060267886A1
• Time in Patent Office: 1,694 Days
• Field of Search: 345 76- 84, 345 87-104, 345204-215, 345690-699, 3151691-1694
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0847 being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0218 with collection of electrodes in groups for n-dimensional addressing
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/062 Waveforms for resetting a plurality of scan lines at a time
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

A display apparatus is disclosed. A display panel includes a plurality of display pixels arranged at intersections of a plurality of scanning lines and a plurality of data lines. A scanning drive unit sequentially applies a scanning signal to each of the scanning lines and sets the corresponding display pixels to a selection state. A data drive unit generates a gradation signal corresponding to the display data and supplies the gradation signal to the display pixels. A power source drive unit supplies to the display pixels a drive voltage for controlling a drive state of each of the display pixels. A drive control unit controls the power source drive unit to operate to set the display pixels to a non-display operation state during a non-display period, and controls the scanning drive unit to operate to set the display pixels to the selection state during the non-display period.

Claims

1. A display apparatus for displaying image information corresponding to display data, comprising:

a display panel including a plurality of display pixels arranged thereon in vicinities of respective intersections of a plurality of scanning lines arranged in a row direction and a plurality of data lines arranged in a column direction;

a plurality of bias lines provided on the display panel along the scanning lines, respectively;

a scanning drive unit which sequentially applies a scanning signal to each of said plurality of scanning lines and sets the display pixels corresponding to each said scanning line to a selection state;

a data drive unit which generates a gradation signal corresponding to the display data and supplies the gradation signal to the display pixels set to the selection state;

a power source drive unit which supplies to the display pixels a drive voltage for controlling a drive state of each of the display pixels;

a state setting unit; and

a drive control unit which controls the power source drive unit to operate to set the display pixels to a non-display operation state during a non-display period in which the display pixels do not display the display data, and controls the scanning drive unit to operate to set the display pixels to the selection state during the non-display period,

wherein each of the plurality of display pixels comprises an optical element and a display drive circuit which controls an operation of the optical element, the display drive circuit comprising an electric charge accumulation circuit which holds a voltage component corresponding to the gradation signal, a supply control circuit which generates a drive current having a predetermined current value based on the voltage component held in the electric charge accumulation circuit, and which supplies the drive current to the optical element, and a writing control circuit which controls a supply state of electric charges, based on the gradation signal, to the electric charge accumulation circuit, and

wherein the state setting unit eliminates a bias state set corresponding to the display data based on the gradation signal to the display drive circuit of the display pixels in each row, generates a setting signal for setting a specific bias state, applies the setting signal to each of the bias lines, and applies the setting signal to the display pixels for each row of the display panel.

2. A drive control method of controlling a display apparatus to display image information corresponding to display data, wherein the display apparatus comprises a display panel including a plurality of display pixels arranged thereon in vicinities of intersections of a plurality of scanning lines arranged in a row direction and a plurality of data lines arranged in a column direction, and each of the plurality of display pixels has an optical element and a display drive circuit which controls an operation of the optical element, the method comprising:

sequentially setting the display pixels to a selection state, row by row;

sequentially supplying a gradation signal corresponding to the display data to the display pixels in each row set to the selection state;

setting each of the display pixels to a display operation state with said display pixels in a bias state corresponding to the gradation signal; and

in a non-display period including a period in which the display pixels are set to a selection state, setting the display pixels to a non-display operation state in which the display data is not displayed,

wherein the setting the display pixels to the display operation state is performed by applying to the display drive circuit a first voltage for setting the optical element to a forward bias state, and by holding a voltage component corresponding to the gradation signal in the display drive circuit, and

wherein the setting of each display pixel to the non-display operation state comprises setting a specific bias state by eliminating the bias state set, corresponding to the gradation signal, to the display drive circuit of the display pixel.

3. A display apparatus for displaying image information corresponding to display data, comprising:

a display panel including a plurality of display pixels arranged thereon in vicinities of respective intersections of a plurality of scanning lines arranged in a row direction and a plurality of data lines arranged in a column direction;

a scanning drive unit which sequentially applies a scanning signal to each of said plurality of scanning lines and sets the display pixels corresponding to each said scanning line to a selection state;

a data drive unit which generates a gradation signal corresponding to the display data and supplies the gradation signal to the display pixels set to the selection state;

a power source drive unit which supplies to the display pixels a drive voltage for controlling a drive state of each of the display pixels; and

a drive control unit which sets a period including a select period in which the scanning drive unit sets the display pixels to the selection state as a non-display period in which the display pixels do not display the display data, and controls a voltage value of the drive voltage supplied from the power source drive unit to set the display pixels to a non-display operation state during the non-display period,

wherein each of the plurality of display pixels has an optical element and a display drive circuit which controls an operation of the optical element, the display drive circuit having a first switch circuit including a control terminal and a conduction channel having a first end and a second end, the drive voltage being applied to the first end of the conduction channel, a first end of the optical element being connected to the second end of the conduction channel, and a second end of the optical element being set to a given potential.

4. The display apparatus according to claim 3, wherein the power source drive unit selectively supplies, as the drive voltage, a first voltage for setting the display pixels to a display operation state in a bias state corresponding to the gradation signal, and a second voltage for setting the display pixels to the non-display operation state.

5. The display apparatus according to claim 4, wherein the drive control unit controls the power source drive unit to supply the first voltage as the drive voltage in a display period in which the display pixels display the display data, and to supply the second voltage as the drive voltage in the non-display period.

6. The display apparatus according to claim 3, further comprising:

a plurality of bias lines provided on the display panel along the scanning lines, respectively; and

a state setting unit which eliminates a bias state set corresponding to the display data based on the gradation signal to the display drive circuit of the display pixels in each row, generates a setting signal for setting a specific bias state, applies the setting signal to each of the plurality of bias lines, and applies the setting signal to the display pixels for each row of the display panel.

7. The display apparatus according to claim 6, wherein the drive control unit controls the state setting unit to supply the setting signal to the bias lines corresponding to the display pixels during a portion of the non-display period.

8. The display apparatus according to claim 6, wherein each of the display pixels comprises:

an electric charge accumulation circuit which holds a voltage component corresponding to the gradation signal;

a supply control circuit which generates a drive current having a predetermined current value based on the voltage component held in the electric charge accumulation circuit, and which supplies the drive current to the optical element; and

a writing control circuit which controls a supply state of electric charges, based on the gradation signal, to the electric charge accumulation circuit,

wherein the supply control circuit includes the first switch circuit and is configured to supply the drive current to the optical element via the conduction channel, and wherein the electric charge accumulation circuit is connected to the control terminal of the first switch circuit.

9. The display apparatus according to claim 8, wherein the optical element comprises a light emitting element which performs a light emitting operation at a luminance corresponding to a value of the drive current applied thereto.

10. The display apparatus according to claim 9, wherein the data drive unit comprises a circuit which generates, as the gradation signal, a gradation current having a current value to cause the light emitting element to perform a light emitting operation with a luminance gradation corresponding to the display data.

11. The display apparatus according to claim 9, wherein the light emitting element comprises an organic electroluminescent element.

12. The display apparatus according to claim 8, wherein the display panel includes a plurality of power source lines corresponding respectively to rows of the display panel, and the drive voltage is supplied to the power source lines, and

wherein the first end of the conduction channel of the first switch circuit of each of the display pixels is connected to one of the power source lines.

13. The display apparatus according to claim 12, wherein the writing control circuit of each of the display pixels comprises:

a conduction channel having a first end connected with one of the data lines and a second end connected with the control terminal of the first switch circuit of the supply control circuit via the electric charge accumulation circuit; and

a control terminal connected with one of the scanning lines.

14. The display apparatus according to claim 8, wherein the display drive circuit further comprises a bias control circuit which discharges electric charges accumulated in the electric charge accumulation circuit, and applies one of no voltage and a reverse bias voltage to the supply control circuit.

15. The display apparatus according to claim 14, wherein the bias control circuit comprises:

a conduction channel having a first end connected with one of the scanning lines and a second end connected with the control terminal of the first switch circuit of the supply control circuit; and

a control terminal connected with one of the bias lines.

16. The display apparatus according to claim 14, wherein the display drive circuit comprises:

a second switch circuit including a control terminal connected with one of the scanning lines, and a conduction channel having a first end to which the drive voltage is applied and a second end to which a control terminal of the first switch circuit is connected;

a third switch circuit including a control terminal connected with one of the scanning lines, and a conduction channel having a first end to which one of the data lines is connected and a second end to which a connection contact point is connected;

a capacitance element connected between the control terminal of the first switch circuit and the connection contact point; and

a fourth switch circuit including a control terminal connected with one of the bias lines, and a conduction channel having a first end connected with one of the scanning lines and a second end connected with the control terminal of the first switch circuit,

wherein the bias control circuit comprises the fourth switch circuit, and

wherein the electric charge accumulation circuit comprises the capacitance element.

17. The display apparatus according to claim 16, wherein each of the first through fourth switch circuits comprises an amorphous silicon thin film transistor.

18. The display apparatus according to claim 4, wherein said plurality of image pixels of the display panel are divided into a plurality of groups each including a plurality of rows, and

wherein the drive control unit controls the power source drive unit to supply the first voltage to the display pixels for each said group as the drive voltage in a display period for operating the display pixels to display the display data, and, within each said group, simultaneously sets the display pixels to a display operation state.

19. The display apparatus according to claim 18, wherein the plurality of rows of each said group comprises a plurality of adjacent rows.

20. The display apparatus according to claim 18, wherein the plurality of rows of each said group comprises a plurality of separated rows.

21. The display apparatus according to claim 18, wherein the drive control unit controls the power source drive unit to supply the second voltage to the display pixels for each said group as the drive voltage in the non-display period, and, within each said group, simultaneously sets the display pixels to the non-display operation state.

22. The display apparatus according to claim 21, wherein the display panel includes a plurality of power source lines corresponding respectively to rows of the display panel, and the drive voltage is applied via the power source lines,

wherein the power source lines are divided into groups in correspondence to the plurality of rows of each said group, and

wherein, within each said group, the power source drive unit commonly supplies the drive voltage to each of the power source lines in the group, and simultaneously supplies the drive voltage to the display pixels in the group.

23. The display apparatus according to claim 18, further comprising:

a plurality of bias lines provided on the display panel along the scanning lines, respectively; and

a state setting unit which eliminates a bias state set corresponding to the display data based on the gradation signal to the display drive circuit of the display pixels in each row, generates a setting signal for setting a specific bias state, and applies the setting signal to each of the bias lines;

wherein the plurality of bias lines are divided into groups each including a plurality of bias lines corresponding to the plurality of rows of each said group, and

wherein, within each said group, the state setting unit supplies the setting signal to said plurality of bias lines in the group, and simultaneously supplies the setting signal to said plurality of display pixels in the group.

24. The display apparatus according to claim 18, further comprising:

a plurality of bias lines provided on the display panel along the scanning lines, respectively; and

a state setting unit which eliminates a bias state set corresponding to the display data based on the gradation signal to the display drive circuit of the display pixels in each row, generates a setting signal for setting a specific bias state, and applies the setting signal to each of the bias lines;

wherein the state setting unit sequentially supplies the setting signal to the plurality of bias lines corresponding to the plurality of rows of each said group, and, within each said group, sequentially supplies the setting signal to the display pixels in the plurality of rows in the group.

25. A drive control method of controlling a display apparatus to display image information corresponding to display data, wherein the display apparatus comprises a display panel including a plurality of display pixels arranged thereon in vicinities of intersections of a plurality of scanning lines arranged in a row direction and a plurality of data lines arranged in a column direction, and wherein each of the plurality of display pixels has an optical element and a display drive circuit which controls an operation of the optical element, the display drive circuit having a first switch circuit including a control terminal and a conduction channel having a first end and a second end, a drive voltage being applied to the first end of the conduction channel, a first end of the optical element being connected to the second end of the conduction channel, and a second end of the optical element being set to a given potential, the method comprising:

sequentially setting the display pixels to a selection state, row by row;

sequentially supplying a gradation signal corresponding to the display data to the display pixels in each row set to the selection state;

in a display period, supplying as the drive voltage a voltage which sets each of the display pixels to a display operation state, and setting the display drive circuit of each of the display pixels to the display operation state in a bias state corresponding to the gradation signal; and

in a non-display period including a period in which the display pixels are set to the selection state, supplying as the drive voltage a voltage which sets each of the display pixels to a non-display operation state, and setting each of the display pixels to the non-display operation state in which the display data is not displayed.

26. The drive control method according to claim 25, wherein the setting of each display pixel to the display operation state comprises supplying to the display pixel a first voltage for setting the optical element to a forward bias, as the drive voltage, and

wherein the setting of each display pixel to the non-display operation state comprises supplying to the display pixel a second voltage for setting the optical element to the non-display operation state, as the drive voltage.

27. The drive control method according to claim 25, wherein the setting of each display pixel to the non-display operation state comprises setting the display pixel to a specific bias state by eliminating the bias state corresponding to the gradation signal set in the display pixel.

28. The drive control method according to claim 27, wherein the setting the display pixel to the specific bias state is performed by applying one of a no-voltage and a reverse bias voltage.

29. The drive control method according to claim 27, wherein the setting the display pixels to the display operation state is performed by applying to the display drive circuit a first voltage for setting the optical element to a forward bias state, as the drive voltage, and by holding a voltage component corresponding to the gradation signal in the display drive circuit.

30. The drive control method according to claim 29, wherein the setting the display pixels to the specific bias state is performed by discharging the voltage component held in the display drive circuit, and by applying and holding one of a no-voltage and a reverse bias voltage in the display drive circuit.

31. The drive control method according to claim 29, wherein the optical element comprises a light emitting element which performs a light emitting operation at a luminance corresponding to a current value of a current applied thereto, and wherein the display pixels are caused to perform a display operation by causing the light emitting element to perform a light emitting operation with a luminance gradation corresponding to the gradation signal.

32. The drive control method according to claim 31, wherein the light emitting element comprises an organic electroluminescent element.

33. The drive control method according to claim 31, wherein the supplying the gradation signal to the display pixels comprises supplying to the display pixels a gradation current having a current value which causes the light emitting element to perform the light emitting operation with a luminance gradation corresponding to the display data.

34. The drive control method according to claim 25, wherein said plurality of display pixels of the display panel are divided into a plurality of groups, each including a plurality of rows, and

wherein the setting the display pixels to the display operation state comprises supplying to the display pixels for each said group a first voltage for setting the optical element to a forward bias, as the drive voltage, such that, within each said group, the display pixels are simultaneously set to the display operation state.

35. The drive control method according to claim 34, wherein the plurality of rows of each said group comprises a plurality of continuous rows.

36. The drive control method according to claim 34, wherein the plurality of rows of each said group comprises a plurality of separated rows.

37. The drive control method according to claim 34, wherein the setting the display pixels to the non-display operation state comprises supplying to the display pixels for each said group a second voltage for setting the optical element to the non-display operation state, as the drive voltage, such that, within each said group, the display pixels are simultaneously set to the non-display operation state.

38. The drive control method according to claim 34, wherein the setting the display pixels to the non-display operation state comprises eliminating the bias state corresponding to the gradation signal set to the display pixels to set the display pixels to a specific bias state.

39. The drive control method according to claim 38, wherein the operation of setting the display pixels to the specific bias state comprises, within each said group, simultaneously setting said plurality of display pixels to the specific bias state.

40. The drive control method according to claim 38, wherein the setting the display pixels to the specific bias state comprises, within each said group, sequentially setting rows of the display pixels to the specific bias state.