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 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.