Flat-panel light emitting pixel with luminance feedback

• US 6,720,942 B2
• Filed: 02/12/2002
• Issued: 04/13/2004
• Est. Priority Date: 02/12/2002
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Lee, Paul P., Cok, Ronald S.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): NGUYEN, KEVIN M
• Application Number:
  US10/074,541
• Publication Number:
  US 20030151569A1
• Time in Patent Office: 791 Days
• Field of Search: 345/76, 345/77, 345/78, 345/82, 345/83
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0833 forming a linear amplifier or follower
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

An image display includes an addressable image display pixel, having a substrate; a light emitter formed on the substrate; a photo-sensor formed on the substrate and optically coupled to the light emitter to detect light emitted by the light emitter to generate a feedback voltage signal in response to light emitted by the light emitter; and, a feedback readout circuit formed on the substrate and responsive to the feedback voltage signal to provide a feedback signal representing the light output of the light emitter, the feedback readout circuit including a transistor amplifier, means for resetting the readout circuit, and a select switch.

Claims

1. An addressable image display pixel, comprising:

a) a substrate;

b) a light emitter formed on the substrate;

c) a photo-sensor formed on the substrate and optically coupled to the light emitter to detect light emitted by the light emitter to generate a feedback voltage signal in response to light emitted by the light emitter; and

,

d) a feedback readout circuit formed on the substrate and responsive to the feedback voltage signal to provide a feedback signal representing the light output of the light emitter, the feedback readout circuit including a transistor amplifier, means for resetting the readout circuit, and a select switch.

2. The addressable image display pixel claimed in claim 1, wherein the photo-sensor is a photodiode.

3. The addressable image display pixel claimed in claim 1, wherein the photo-sensor is a photo-capacitor, and wherein the feedback readout circuit further includes a transfer gate for transferring photo charge from the photo-capacitor to the transistor amplifier.

4. The addressable image display pixel claimed in claim 2, wherein the photo-sensor is an organic or silicon semiconductor.

5. The addressable image display pixel claimed in claim 1, wherein the light emitter is an organic light emitting diode.

6. The addressable image display pixel claimed in claim 1, wherein the means for resetting the feedback circuit is a reset transistor switch responsive to a reset signal for initializing the photo-sensor.

7. The addressable image display pixel claimed in claim 1, wherein the means for resetting the feedback circuit is a reset line for initializing the photo-sensor.

8. The addressable image display pixel claimed in claim 1, wherein the addressable light emitter is addressable by a select signal and the feedback readout circuit is responsive to the select signal to output the feedback signal.

9. The addressable image display pixel claimed in claim 1, wherein the addressable light emitter is addressable by a select signal and the feedback readout circuit is responsive to a separate photo-sensor select signal to output the feedback signal.

10. The addressable image display pixel claimed in claim 1, further comprising a plurality of light emitters formed on the substrate.

11. The addressable image display pixel claimed in claim 1, wherein the light emitters are colored light emitters in a color pixel.

12. A display device, comprising:

a) display pixel array, having

i) a substrate; and

ii) a plurality of addressable image display pixels formed on the substrate, each image display pixel including a light emitter, a photo-sensor optically coupled to the light emitter to detect light emitted by the light emitter to generate a feedback voltage signal in response to light emitted by the light emitter; and

, a feedback readout circuit formed on the substrate and responsive to the feedback voltage signal to provide a feedback signal representing the light output of the light emitter, the feedback readout circuit including a transistor amplifier, means for resetting the readout circuit, and a select switch; and

b) a display control circuit for receiving display input signals and modifying the display input signals in response to the feedback signals from the addressable display pixels.

13. The display device claimed in claim 12, wherein the photo-sensors are photodiodes.

14. The display device claimed in claim 12, wherein the photo-sensors are photo-capacitors, and wherein the feedback readout circuits further include a transfer gate for transferring photo charge from the photo-capacitors to the transistor amplifiers.

15. The display device claimed in claim 12, wherein the photo-sensors are organic or silicon semiconductors.

16. The display device claimed in claim 12, wherein the light emitters are organic light emitting diodes.

17. The display device claimed in claim 12, wherein the means for resetting the feedback circuit are reset transistor switches responsive to a reset signal for initializing the photo-sensors.

18. The display device claimed in claim 12, wherein the means for resetting the feedback circuit is a reset line for initializing the photo-sensors.

19. The display device claimed in claim 12, wherein the addressable light emitters are addressable by a select signal and the feedback readout circuits are responsive to the select signal to output the feedback signal.

20. The display device claimed in claim 12 wherein the addressable light emitter is addressable by a select signal and the feedback readout circuit is responsive to a separate photo-sensor select signal to output the feedback signal.

21. The display device claimed in claim 12, wherein the image display pixels include a plurality of individually addressable light emitters.

22. The display device claimed in claim 21, wherein the plurality of light emitters are differently colored light emitters and the image display pixel is a color pixel.

23. The display device claimed in claim 21, wherein the plurality of light emitters emit the same color of light.

24. The display device claimed in claim 12, further comprising a plurality of addressable display pixels without photo-sensors.

25. The display device claimed in claim 12, further comprising an address control circuit for applying the modified display input signals to the display pixel array.