OLED display with aging compensation

• US 6,995,519 B2
• Filed: 11/25/2003
• Issued: 02/07/2006
• Est. Priority Date: 11/25/2003
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald S., Arnold, Andrew D.
• Primary Examiner(s): Dinh, Trinh Vo
• Application Number:
  US10/721,123
• Publication Number:
  US 20050110420A1
• Time in Patent Office: 805 Days
• Field of Search: 315/169.3, 315/169.1, 315/291, 345/76, 345/82, 345/84, 345/98, 345/214, 345/208, 345/83, 345/204
• US Class Current: 315/169.3
• 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 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3225 using an active matrix

Abstract

An organic light emitting diode (OLED) display includes an array of OLEDs, each OLED having two terminals; a voltage sensing circuit for each OLED including a transistor in each circuit connected to one of the terminals of a corresponding OLED for sensing the voltage across the OLED to produce feedback signals representing the voltage across the OLEDs; and a controller responsive to the feedback signals for calculating a correction signal for each OLED and applying the correction signal to data used to drive each OLED to compensate for the changes in the output of each OLED.

Claims

1. An organic light emitting diode (OLED) display, comprising:

a) an array of OLED display light-emitting elements, each OLED display light-emitting element having two terminals;

b) a voltage sensing circuit for each OLED display light-emitting element in the display array including a transistor in each circuit connected to one of the terminals of a corresponding OLED display light-emitting element for sensing the voltage across the OLED display light-emitting element to produce feedback signals representing the voltage across the OLED display light-emitting elements in the display array; and

c) a controller responsive to the feedback signals for calculating a correction signal for each OLED display light-emitting element and applying the correction signal to data used to drive each OLED display light-emitting element to compensate for the changes in the output of each OLED display light-emitting element.

2. The OLED display claimed in claim 1, wherein the output of the OLEDs change with temperature, and further comprising a temperature sensor for generating a temperature signal and wherein the controller is also responsive to the temperature signal to calculate the correction signal.

3. The OLED display claimed in claim 1, wherein the controller further includes a lookup table having a correction signal for each of the OLEDs.

4. The OLED display claimed in claim 1, wherein the controller sequentially activates individual OLED to measure the voltage associated with each OLED element.

5. The OLED display claimed in claim 1, wherein the controller activates one or more OLED elements at a plurality of different brightness levels to calculate the correction signal.