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 operating a display device having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the method comprising:
processing, at a readout system, a voltage corresponding to a difference between a reference current flowing in the readout system and a measured first device current flowing through the drive transistor or the light emitting device of a selected one of the pixel circuits, including,
receiving the reference current during a first phase,
receiving the measured first device current during a second phase, and
generating the voltage by processing the reference current and the measured first device current;
converting, at the readout system, the voltage into a corresponding quantized output signal indicative of the difference between the reference current and the measured first device current; and
adjusting, using a controller, a programming value for the selected pixel circuit by an amount based on the quantized output signal such that the storage device of the selected pixel circuit is subsequently programmed with a current or voltage related to the adjusted programming value.
2. The method of claim 1 , wherein the readout system adds at least one of a noise current and a leakage current to the reference current during the first phase.
3. The method of claim 2 , wherein the readout system receives at least one of the noise current and the leakage current on a plurality of monitor lines when the selected one of the pixel circuits is not driven.
4. The method of claim 1 , wherein converting the voltage into the corresponding quantized output signal comprises performing a multi-bit quantization operation.
5. The method of claim 1 , wherein converting the voltage into the corresponding quantized output signal comprises performing a single bit quantization operation to generate a single-bit signal as the quantized output signal.
6. The method of claim 1 , wherein the processing comprises providing, depending on a predefined criterion, the reference current and the measured first device current, or signals related thereto, to one of a current integrator and a current comparator to generate the voltage.
7. The method of claim 1 , comprising using a switch matrix to select the measured first device current from a plurality of received device currents.
8. The method of claim 1 , comprising converting an adjustable voltage value into the reference current using a voltage to current conversion circuit.
9. The method of claim 1 , wherein the converting comprises selecting at least one of a current comparator circuit and a current integrator circuit.
10. A method of operating a display device having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the method comprising:
processing, at a readout system, a voltage corresponding to a difference between a reference current flowing in the readout system and a measured first device current flowing through the drive transistor or the light emitting device of a selected one of the pixel circuits, including,
receiving at least one of a noise current and a leakage current during a first phase;
receiving the measured first device current during a second phase;
receiving the reference current during one of the first and second phases; and
adding or subtracting the reference current to a current received in one of the first and second phases;
converting, at the readout system, the voltage into a corresponding quantized output signal indicative of the difference between the reference current and the measured first device current; and
adjusting, using a controller, a programming value for the selected pixel circuit by an amount based on the quantized output signal such that the storage device of the selected pixel circuit is subsequently programmed with a current or voltage related to the adjusted programming value.
11. The method of claim 10 , wherein the readout system receives the at least one of the noise current and the leakage current on a plurality of monitor lines when the selected one of the pixel circuits is not driven.
12. The method of claim 10 , comprising:
a providing the at least one of a noise current and a leakage current during the first phase to an integration circuit;
providing the measured first device current to the integration circuit during the second phase; and,
performing reset operations on the integrated circuit prior to the first and second phases.
13. The method of claim 12 , wherein the reset operations prior to the first and second phases restore the integration circuit to different states.