Solid state emissive display with on-demand refresh

• US 6,278,242 B1
• Filed: 03/20/2000
• Issued: 08/21/2001
• Est. Priority Date: 03/20/2000
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald S., Lee, Paul P.
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US09/528,900
• Time in Patent Office: 519 Days
• Field of Search: 315/169.3, 315/169.1, 315/169.2, 315/169.4, 313/495, 313/498
• US Class Current: 315/169.1
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• 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 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• 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 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
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A display device, including: a light controlling element; a drive circuit connected to the light controlling element, the drive circuit including a transistor having a gate for controlling the power applied to the light controlling element; a storage capacitor connected to the gate of the drive circuit transistor; a control circuit for depositing charge on the storage capacitor; a refresh circuit connected to the control circuit and responsive to an external signal for causing the control circuit to deposit charge on the storage capacitor; and a feedback mechanism including element for measuring a change in a performance characteristic of the display device and for signaling the refresh circuit in response to the measured characteristic, whereby the display is refreshed on demand as opposed to periodically.

Claims

1. A display device, comprising:

a) a light controlling element;

b) a drive circuit connected to the light controlling element, the drive circuit including a transistor having a gate for controlling the signal applied to the light controlling element;

c) a first storage capacitor connected to the gate of the drive circuit transistor;

d) a control circuit for depositing charge on the first storage capacitor;

e) a refresh circuit connected to the control circuit and responsive to an external signal for causing the control circuit to deposit charge on the first storage capacitor; and

f) a feedback mechanism including means for measuring a change in a performance characteristic of the display device and for signaling the refresh circuit in response to the measured performance characteristic, whereby the display is refreshed on demand as opposed to periodically.

2. The display device claimed in claim 1, wherein the performance characteristic is the charge level on the storage capacitor.

3. The display device claimed in claim 1, wherein the performance characteristic is the light output of the light controlling element.

4. The display device claimed in claim 1, wherein the performance characteristic is the power applied to the light controlling element.

5. The display device claimed in claim 1, including a plurality of light control elements and a separate feedback mechanism for each light control element.

6. The display device claimed in claim 1, including a plurality of light control elements, and a separate feed back mechanism for subsets of the light control elements.

7. The display device claimed in claim 1, including a plurality of light control elements and a further light control element that is not visible as part of the display, and the feedback mechanism being responsive to the characteristics of only the further light control element.

8. The display claimed in claim 1, wherein the feedback mechanism includes a second storage capacitor isolated from the first storage capacitor and bearing an identical charge to the first storage capacitor and a voltage comparator connected to the first and second storage capacitors for comparing the states of the first and second storage capacitors.

9. The display claimed in claim 1, including a plurality of colored light control elements and a further light control element for each color that is not visible as part of the display, and the feedback mechanism being responsive to the characteristics of only the further light control elements.

10. The display device claimed in claim 1, wherein the light control element is an organic light emitting diode (OLED).

11. The display device claimed in claim 10 wherein the OLED is deposited on a single-crystal Silicon substrate.

12. The display device claimed in claim 10 wherein the OLED is deposited on a glass substrate together with amorphous, polycrystalline, or continuous grain Silicon materials.