Cleaning common unwanted signals from pixel measurements in emissive displays
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.
1. A method of compensating for common unwanted signals present in pixel measurement data for a display having an array of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the method comprising:
programming the pixels circuits of the array;
performing a first pixel circuit measurement on the array via a monitor line generating first pixel measurement data;
performing a second pixel circuit measurement on the array via the monitor line generating second pixel measurement data, each of the first and second pixel measurement data including common unwanted signals; and
generating cleaned pixel data by removing the common unwanted signals from the first pixel measurement data with use of the second pixel measurement data.
2. The method of claim 1 , wherein performing the first pixel circuit measurement on the array and performing the second pixel measurement on the array are carried out simultaneously or one after another.
3. The method of claim 1 , wherein generating cleaned pixel data by removing the common unwanted signals from the first pixel measurement data with use of the second pixel measurement data includes generating a difference between the first pixel measurement data and the second pixel measurement data in an analog or a digital domain.
4. The method of claim 1 , wherein generating cleaned pixel data by removing the common unwanted signals from the first pixel measurement data with use of the second pixel measurement data includes comparing the first pixel measurement data and the second pixel measurement data.
5. The method of claim 1 , wherein the common unwanted signals include any one or more of noise, leakage, or offset.
6. The method of claim 1 , further comprising extracting one or more pixel parameters based on the cleaned data.
7. The method of claim 6 , 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.
8. The method of claim 1 , wherein performing a first pixel circuit measurement on the array generating first pixel measurement data includes measuring a first pixel circuit of the array at a first time, and wherein performing a second pixel circuit measurement on the array generating second pixel measurement data includes measuring the first pixel circuit of the array at a second time different from the first time.
9. The method of claim 8 , further comprising:
extracting a pixel parameter for the first pixel circuit based on the cleaned pixel data.
10. The method of claim 8 , wherein programming the pixels circuits of the array includes: before measuring the first pixel circuit of the array at the first time, programming the first pixel circuit with first programming data; and before measuring the first pixel circuit at the second time, programming the first pixel circuit with second programming data different from the first programming data.
11. The method of claim 10 , further comprising adjusting at least one of the first programming data and the second programming data so that the first pixel measurement data is the same as the second pixel measurement data.
12. The method of claim 1 , wherein performing a first pixel circuit measurement on the array generating first pixel measurement data includes measuring a first pixel circuit of the array, and wherein performing a second pixel circuit measurement on the array generating second pixel measurement data includes measuring a second pixel circuit of the array in a different row from the row of the first pixel circuit of the array.
13. The method of claim 12 , further comprising:
extracting a pixel parameter for the first pixel circuit or the second pixel circuit based on the cleaned pixel data.
14. The method of claim 12 , wherein programming the pixels circuits of the array includes: before measuring the first pixel circuit of the array, programming the first pixel circuit with first programming data; and before measuring the second pixel circuit, programming the second pixel circuit with second programming data different from the first programming data.
15. The method of claim 14 , further comprising adjusting at least one of the first programming data and the second programming data so that the first pixel measurement data is the same as the second pixel measurement data.
16. The method of claim 1 , further comprising sampling a signal external to the array of pixel circuits simultaneously with said performing the pixel circuit measurements.
17. The method of claim 16 , wherein said performing the first pixel circuit measurement on the array generating first pixel measurement data includes sampling a difference between the first pixel measurement data and a first sample of the sampled external signal.
18. The method of claim 16 , further comprising sampling at least one difference between the pixel circuit measurements and the sampled external signal.
19. The method of claim 18 , wherein one of a first and a second sample of the sampled external signal has a zero value, and the other of the first and the second sample of the sampled external signal has a non-zero value.