Method of Compensating an Aging Process of an Illumination Device

• US 20080252571A1
• Filed: 09/19/2006
• Published: 10/16/2008
• Est. Priority Date: 09/29/2005
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Hente, Dirk, Young, Edward Willem Albert
• Application Number:
  US12/088,435
• Publication Number:
  US 20080252571A1
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• 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 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: H05B 45/60 Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention relates to a method of compensating an aging process of an illumination device comprising at least one organic light emitting diode (1) (OLED) having a light output that changes with time and a driver (2) connected with the OLED (1) having an individual current-voltage characteristic.

Claims

1. A method of compensating an aging process of an illumination device comprising

at least one organic light emitting diode (1) (OLED) having a light output that changes with time,

a driver (2) connected with the OLED (1) having an individual current-voltage characteristic,

and comprising a correction calculation process including the following steps:

determining a first parameter including information about the slope of the actual current-voltage characteristic of the OLED (1) and producing a correction signal based at least on the first parameter, being indicative of aging, in order to compensate for the changes in the light output of the OLED (1).

2. The method as claimed in claim 1, characterized in that the slope of the actual semilog current-voltage characteristic of the OLED (1) is considered by the first parameter.

3. The method as claimed in claim 1, characterized in that the driver (2) comprises a measurement circuit (3) and a control circuit (4), wherein the measurement circuit (3) detects the actual value of the slope of the actual semilog current-voltage characteristic of the OLED (1) and the control circuit (4) produces the correction signal thereto.

4. The method according to claim 1, characterized in that the driver (2) detects the actual value of the slope of the actual semilog current-voltage characteristic above the threshold voltage of the OLED (1).

5. The method according to claim 1, characterized in that the measurement circuit (3) measures the on-time of the OLED (1), being a second parameter for aging.

6. The method according to claim 1, characterized in that a third parameter comprises the current-voltage characteristic of the unused OLED (1).

7. The method according to claim 1, characterized in that the driver (2) comprises a mathematical function and/or a lookup table to generate the correction signal based on the parameters.

8. The method according to claim 1, characterized in that the driver (2) comprises a hardware circuit, in particular a passive network, to determine the correction signal in response to the measured first parameter.

9. The method according to claim 1, characterized in that the parameters for aging and the calculated correction signal are stored in a memory device (5).

11. The illumination device comprising at least one organic light emitting diode (1) (OLED) having a light output that changes with time and

a driver (2) connected with the OLED (1) having an individual current-voltage characteristic, wherein the illumination device comprises:

a measurement circuit (3) for determining a first parameter including information about the slope of the actual current-voltage characteristic of the OLED (1) and a control circuit (4) for producing a correction signal based at least on the first parameter, being indicative of aging, in order to compensate for the changes in the light output of the OLED (1) with a method according to claim 1.

10. An illumination device comprising at least one organic light emitting diode (1) (OLED) having a light output that changes with time and

a driver (2) connected with the OLED (1) having an individual current-voltage characteristic, wherein the illumination device comprises:

a measurement circuit (3) for determining a first parameter including information about the slope of the actual current-voltage characteristic of the OLED (1) and a control circuit (4) for producing a correction signal based at least on the first parameter, being indicative of aging, in order to compensate for the changes in the light output of the OLED (1).