ORGANIC LIGHT EMITTING DISPLAY DEVICE AND DRIVING VOLTAGE SETTING METHOD THEREOF

• US 20110025676A1
• Filed: 12/14/2009
• Published: 02/03/2011
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Mobile Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kawashima, Shingo
• Granted Patent: US 8,766,966 B2
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

An organic light emitting display device with reduce power consumption is disclosed. Some embodiments include a current detector which measures current over varying drive voltages. The current measurements are used to determine drive voltages for driving the display array.

Claims

1. An organic light emitting display device, comprising:

a display panel;

a power supplier configured to supply a driving voltage to the display panel, wherein the power supplier comprises a variable circuit configured to vary the driving voltage; and

a current detector configured to detect a panel current flowing into the display panel while the driving voltage is supplied from the power supplier to the display panel,

wherein an optimal driving voltage is determined by calculating the variations of the panel current as a result of variations in the driving voltage.

2. The organic light emitting display device as claimed in claim 1, wherein the optimal driving voltage is a driving voltage at a point where the derivative of the panel current with respect to the driving voltage is changed.

3. The organic light emitting display device as claimed in claim 2, wherein the optimal driving voltage is a driving voltage at a point where the derivative of the panel current with respect to the increase in the driving voltage is reduced.

4. The organic light emitting display device as claimed in claim 1, wherein the power supplier is configured to output a first power voltage to a positive output terminal and a second power voltage to a negative output terminal, and the driving voltage is a voltage difference between the first power voltage and the second power voltage.

5. The organic light emitting display device as claimed in claim 4, wherein the first power voltage is a high power voltage and the second power voltage is a low power voltage.

6. The organic light emitting display device as claimed in claim 4, wherein the power supplier is configured to vary the driving voltage by varying the first power voltage.

7. The organic light emitting display device as claimed in claim 4, wherein the current detector is connected to a first power supply line that transfers the first power voltage from the power supplier to the display panel and is configured to detect the panel current flowing in the first power supply line.

8. The organic light emitting display device as claimed in claim 1, wherein the current detector includes:

a current sensor that detects the panel current; and

a variation calculator that calculates the variations of the panel current.

9. The organic light emitting display device as claimed in claim 8, wherein the variation calculator outputs the derivative of the panel current with respect to the driving voltage.

10. The organic light emitting display device as claimed in claim 8, wherein the variation calculator comprises an analog differentiator that outputs the derivative of the panel current with respect to the driving voltage.

11. The organic light emitting display device as claimed in claim 8, wherein the current detector further includes a control signal generator that generates a control signal for controlling the power supplier according to the variations of the panel current.

12. The organic light emitting display device as claimed in claim 1, wherein the display panel displays a still image while data for calculating the variations of the panel current is taken.

13. The organic light emitting display device as claimed in claim 1, wherein the display panel is supplied with the data corresponding to the maximum gray scale while data for calculating the variations of the panel current is taken.

14. The organic light emitting display device as claimed in claim 1, wherein the optimal driving voltage is determined by selecting the greatest of multiple driving voltages, each of the multiple driving voltages being determined as an optimal driving voltage for one of multiple display colors.

15. A method of setting a driving voltage for an organic light emitting display device, the method comprising:

supplying a varying driving voltage to a display panel;

detecting a panel current flowing into the display panel while the driving voltage is supplied;

calculating variations of the panel current resulting from the variations in the driving voltage; and

determining an optimal driving voltage based on the variations of the panel current.

16. The method as claimed in claim 15, wherein the optimal driving voltage is determined as a driving voltage at a point where the derivative of the panel current with respect to the driving voltage is changed.

17. The method as claimed in claim 15, wherein the optimal driving voltage is determined as a driving voltage at a point where the derivative of the panel current with respect to the driving voltage is reduced below a threshold.

18. The method as claimed in claim 15, wherein the display panel displays a still image while data for calculating the variations of the panel current is taken.

19. The method as claimed in claim 15, wherein the display panel is supplied with the data corresponding to the maximum gray scale while data for calculating the variations of the panel current is taken.

20. The method as claimed in claim 15, wherein the optimal driving voltage is determined by selecting the greatest of multiple driving voltages, each of the multiple driving voltages being determined as an optimal driving voltage for one of multiple display colors.