Cleaning common unwanted signals from pixel measurements in emissive displays

• US 9,830,857 B2
• Filed: 09/23/2014
• Issued: 11/28/2017
• Est. Priority Date: 01/14/2013
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza
• Primary Examiner(s): Bukowski, Kenneth
• Application Number:
  US14/494,127
• Publication Number:
  US 20150009204A1
• Time in Patent Office: 1,162 Days
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• 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 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

Methods of compensating for common unwanted signals present in pixel data measurements of a pixel circuit in a display having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device. First pixel data is measured from a first pixel circuit through a monitor line. Second pixel data from the first pixel circuit or a second pixel circuit is measured through the monitor line or another monitor line. The first measured pixel data or the second measured pixel data or both are used to clean the other of the first measured pixel data or the second measured pixel data of common unwanted signals to produce cleaned data for parameter extraction from the first pixel and/or second pixel.

Claims

1. A method of compensating for common unwanted signals present in pixel data measurements of a pixel circuit in a display having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the method comprising:

programming a first pixel circuit with first data;

measuring a first sample of pixel data from the first pixel circuit through a monitor line;

programming the first pixel circuit with second data that is different from the first data;

measuring a second sample of pixel data from the first pixel circuit through the monitor line wherein said second sample of pixel data is different from said first sample of pixel data; and

producing cleaned pixel data by subtracting one of the first and second measured samples of pixel data from the other of the first and second measured samples of pixel data in an analog or a digital domain to remove any common unwanted signals.

2. The method of claim 1, wherein the programming of the first pixel circuit with the second pixel data comprises turning off the first pixel circuit.

3. The method of claim 1, further comprising extracting one or more pixel parameters based on the data produced by said subtracting.

4. The method of claim 3, wherein the one or more pixel parameters includes any one or more of aging of the drive transistor, aging of the light emitting device, a process non-uniformity parameter, a mobility parameter, a threshold voltage of the drive transistor or a change thereof, or a threshold voltage of the light emitting device or a change thereof.

5. The method of claim 1, further comprising sampling a reference signal from a circuit external to any of the plurality of pixel circuits of the display simultaneously with the measuring of the first sample of pixel data or the measuring of the second sample of pixel data.

6. The method of claim 5, wherein the measuring of the first sample of pixel data includes sampling a difference between the first sample of pixel data and a first sample of the reference signal.

7. The method of claim 6, wherein the measuring of the second sample of pixel data includes sampling a difference between the first sample of pixel data and a second sample of the reference signal.

8. The method of claim 7, wherein the first sample has a zero value, and the second sample has a non-zero value.

9. A method of compensating for common unwanted signals present in pixel data measurements of a pixel circuit in a display having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the method comprising:

programming a first pixel circuit with first data;

measuring first pixel data from the first pixel circuit through a monitor line;

programming the first pixel circuit with second data that is different from the first data;

measuring a second pixel data from the first pixel circuit through the monitor line so that said second sample of pixel data is different from said first sample of pixel data; and

producing cleaned pixel data by comparing the first measured sample of pixel data and the second measured sample of pixel data to clean one of the first measured pixel data or the second measured pixel data of common unwanted signals.

10. The method of claim 9, wherein the common unwanted signals include any one or more of noise, leakage, or offset.