Display apparatus and method for driving the same, and display driver and method for driving the same

• US 20080036708A1
• Filed: 08/09/2007
• Published: 02/14/2008
• Est. Priority Date: 08/10/2006
• Status: Active Grant

• Current Assignee: Solas OLED Limited (Atlantic IP Services Limited)
• Original Assignee: Casio Computer Company Limited
• Inventors: Shirasaki, Tomoyuki, Ogura, Jun
• Granted Patent: US 7,907,105 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A display apparatus includes: a light-emitting device; a pixel circuit which is connected to the light-emitting device; a display driver having a voltage adjustment section which adjusts the potential of an adjustment voltage such that the potential thereof is approximated to a potential which is changed in accordance with the change amount of the characteristics inherent to the pixel circuit when a reference current having a predetermined current value is supplied to the pixel circuit; and a data line which connects the display driver and pixel circuit.

Claims

1. A display apparatus comprising:

a light-emitting device;

a pixel drive circuit which is connected to the light-emitting device;

a display driver having a voltage adjustment section which adjusts the potential of an adjustment voltage such that the potential thereof is approximated to a potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit when a reference current having a predetermined current value is supplied to the pixel drive circuit; and

a data line which connects the display driver and pixel drive circuit.

2. The display apparatus according to claim 1, wherein

the voltage adjustment section generates the adjustment voltage on the basis of a gradation voltage having a predetermined potential corresponding to a display data and an offset voltage set according to the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit.

3. The display apparatus according to claim 1, wherein

the display driver has a voltage comparison section which compares the potential in the voltage adjustment section and the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit when the reference current having a predetermined current value is supplied to the pixel drive circuit.

4. The display apparatus according to claim 3, wherein

the voltage comparison section has a current source which supplies the reference current having a predetermined current value to the pixel drive circuit.

5. The display apparatus according to claim 4, wherein

the voltage comparison section has a connection path switch which switchingly connects the current source or the voltage adjustment section to the data line.

6. The display apparatus according to claim 5, wherein

the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit while the reference current having a predetermined current value is being supplied to the pixel drive circuit, is output to the voltage comparison section when the connection path switch connects the current source to the data line.

7. The display apparatus according to claim 4, wherein

the display driver has an offset voltage generation section which generates an offset voltage on the basis of a result of comparison, which is made by the voltage comparison section, between the potential in the voltage adjustment section and the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit when the reference current having a predetermined current value is supplied to the pixel drive circuit.

8. The display apparatus according to claim 7, wherein

when the voltage comparison section determines that the potential in the voltage adjustment section is higher than the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit while the reference current having a predetermined current value is being supplied to the pixel drive circuit, the offset voltage generation section modulates the offset voltage.

9. The display apparatus according to claim 7, wherein

the offset voltage generation section counts the number of inputs of a signal output from the voltage comparison section when the potential in the voltage adjustment section is higher than the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit while the reference current having a predetermined current value is being supplied to the pixel drive circuit.

10. The display apparatus according to claim 9, wherein

the offset voltage generation section modulates the offset voltage according to an offset setting value which is changed depending on the number of inputs of the signal output from the voltage comparison section.

11. The display apparatus according to claim 10, wherein

the offset voltage has a value obtained by multiplying the offset setting value by a unit voltage.

12. The display apparatus according to claim 7, wherein

the offset voltage generation section outputs the offset setting value which is changed depending on the number of inputs of the signal output from the voltage comparison section according to the signal which is output from the voltage comparison section when the potential in the voltage adjustment section is equal to or lower than the potential which is changed in accordance with the change amount of the characteristics inherent to the pixel drive circuit while the reference current having a predetermined current value is being supplied to the pixel drive circuit.

13. The display apparatus according to claim 12, wherein

the display driver has a storage section which stores the offset setting value output from the offset voltage generation section.

14. The display apparatus according to claim 13 further comprising a plurality of display pixels each constituted by a set of the light-emitting device and pixel drive circuit, and

the storage section stores the offset setting value in units of each display pixel.

15. The display apparatus according to claim 10, wherein

the display driver has a storage section which stores the offset setting value output from the offset voltage generation section, and

the offset voltage generation section outputs an offset voltage obtained by multiplying the offset setting value output from the storage section by a unit voltage to the voltage adjustment section.

16. The display apparatus according to claim 1, wherein

the pixel drive circuit includes a driving transistor connected in series to the light-emitting device.

17. The display apparatus according to claim 16, wherein

the pixel drive circuit includes a selection transistor connected between the driving transistor and data line and a transistor for diode connection which sets the driving transistor in a diode connection state.

18. A method for driving a display apparatus, wherein

the display apparatus includes:

a light-emitting device;

a pixel circuit which is connected to the light-emitting device;

a display driver having a voltage adjustment section; and

a data line which connects the display driver and pixel circuit, and

the voltage adjustment section adjusting an voltage for activating display driver such that the potential thereof is approximated to a potential which is changed in accordance with the change amount of the characteristics of the pixel circuit when a reference current having a predetermined current value is supplied to the pixel circuit.

19. A display driver comprising:

a voltage adjustment section which adjusts the potential of an adjustment voltage such that the potential thereof is approximated to a potential which is changed in accordance with the change amount of the characteristics inherent to a pixel circuit connected to a light-emitting device when a reference current having a predetermined current value is supplied to the pixel circuit.

20. A method for driving a display driver comprising:

adjusting the potential of an adjustment voltage such that the potential thereof is approximated to a potential which is changed in accordance with the change amount of the characteristics inherent to a pixel circuit connected to a light-emitting device when a reference current having a predetermined current value is supplied to the pixel circuit.