# US 2014/0198092 A1 · Driving scheme for emissive displays providing compensation for driving transistor variations

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0198092 A1
- Document ID: US20140198092A1
- Status: Published application
- Kind: A1
- Application number: 14/154,945
- Filed: 2014-01-14
- Published: 2014-07-17
- Earliest claimed: 2013-01-14
- Assignees: Ignis Innovation Inc.
- Applicants: Ignis Innovation Inc.
- Inventors: Yaser Azizi; Joseph Marcel Dionne; Nino Zahirovic; Gholamreza Chaji
- Web page: https://patentgrep.com/patent/US20140198092A1

## CPC

- G09G 3/3258: with pixel circuitry controlling the voltage across the light-emitting element
- 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)}
- G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element
- 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
- G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
- G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements
- G09G 2330/12: Test circuits or failure detection circuits included in a display system, as permanent part thereof
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

Systems and methods detect and compensate for process or performance-related non-uniformities and/or degradation in displays. The systems and methods can compare a device current with one or more reference currents to generate an output signal indicative of the difference between the device and reference currents. This output voltage can be amplified, and quantized and then be used to determine how the device current differs from the reference current and to adjust the programming voltage for the device of interest accordingly.

## Claims

### Claim at position 1

1-11. (canceled)

### Claim 12

A method of compensating for deviations by a measured device current from a reference current 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:
performing a first reset operation on an integration circuit, the reset operation restoring the integration circuit to a first known state;
performing a first current integration operation at the integration circuit, the integration operation operative to integrate a first input current corresponding to a difference between a reference current and a measured first device current flowing through the drive transistor or the light emitting device of a selected one of the pixel circuits;
storing a first voltage corresponding to the first current integration operation on a first storage capacitor;
performing a second reset operation on the integration circuit, the reset operation restoring the integration circuit to a second known state;
performing a second current integration operation at the integration circuit, the integration operation operative to integrate a second input current corresponding to the leakage current on a reference line;
storing a second voltage corresponding to the second current integration operation on a second storage capacitor;
generating an amplified output voltage corresponding to the difference between the first voltage and the second voltage using one or more amplifiers; and
quantizing the amplified output voltage.

### Claim 13 (depends on 12)

The method of claim 12, further comprising performing a third reset operation while quantizing the amplified output voltage.

### Claim 14 (depends on 12)

The method of claim 12, wherein performing a reset operation on the integration circuit comprises setting the integration circuit in a unity gain configuration.

### Claim 15 (depends on 12)

The method of claim 12, further comprising cancelling the offset of one or more amplification circuits.

### Claim 16

A method of compensating for deviations by a measured device current from a reference current 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:
performing a first reset operation on an integration circuit, the reset operation restoring the integration circuit to a first known state;
performing a first current integration operation at the integration circuit, the integration operation operative to integrate a first input current corresponding to a difference between a reference current and a measured first device current flowing through the drive transistor or the light emitting device of a selected one of the pixel circuits;
storing a first voltage corresponding to the first current integration operation on a first storage capacitor;
performing a second reset operation on the integration circuit, the reset operation restoring the integration circuit to a second known state;
performing a second current integration operation at the integration circuit, the integration operation operative to integrate a second input current corresponding to the leakage current on a reference line;
storing a second voltage corresponding to the second current integration operation on a second storage capacitor; and
performing a multibit quantization operation based on the first stored voltage and the second stored voltage.

### Claim 17

A system for compensating for deviations by a measured device current from a reference current in a display having a plurality of pixel circuits each including a storage device, a drive transistor, and a light emitting device, the system comprising:
a readout system configured to: a) process a voltage corresponding to a difference between a reference current and a measured first device current flowing through the drive transistor or the light emitting device of a selected one of the pixel circuits and b) convert the voltage into a corresponding quantized output signal indicative of the difference between the reference current and the measured first device current; and
a controller configured to adjust 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.

### Claim 18 (depends on 17)

The system of claim 17, wherein the readout system is further configured to:
receive the reference current during a first phase;
receive the measured first device current during a second phase; and
generate the voltage by processing the reference current and the measured first device current.

### Claim 19 (depends on 18)

The system of claim 18, wherein the readout system is further configured to receive a noise current and a leakage current during at least one of the first phase and the second phase.

### Claim 20 (depends on 19)

The system of claim 19, wherein the readout system is further configured to compensate for the received noise current and leakage current.

### Claim 21 (depends on 20)

The system of claim 20, wherein the readout system is further configured to receive the noise current and the leakage current on a plurality of monitor lines.

### Claim 22 (depends on 17)

The system of claim 17, wherein the readout system is configured to process a generated analog output voltage using a multibit quantizer in order to convert the voltage into the corresponding quantized output signal.

### Claim 23 (depends on 17)

The system of claim 17, wherein the reference current is generated by a voltage-to-current conversion circuit.

### Claim 24 (depends on 17)

The system of claim 17, wherein a switch matrix selects the measured first device current from a plurality of received device currents.

### Claim 25 (depends on 17)

The system of claim 17, wherein the polarity of the reference current is reversed prior to being transmitted.

### Claim 26 (depends on 17)

The system of claim 17, wherein the readout system is further configured to generate the first input current and compensate for noise signals over a multiple-stage current readout operation.

### Claim 27 (depends on 17)

The system of claim 17, wherein the conversion circuit comprises at least one of a current comparator circuit and a current integrator circuit.

### Claim at position 18

28-32. (canceled)