# US 2017/0256199 A1 · System and method for data sensing for compensation in an electronic display

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- Number: US 2017/0256199 A1
- Document ID: US20170256199A1
- Status: Published application
- Kind: A1
- Application number: 15/272,170
- Filed: 2016-09-21
- Published: 2017-09-07
- Earliest claimed: 2016-03-02
- Assignees: Apple Inc.
- Applicants: Apple Inc.
- Inventors: Yafei Bi; Mohammad B. Vahid Far
- Web page: https://patentgrep.com/patent/US20170256199A1

## CPC

- G09G 3/3233: with pixel circuitry controlling the current through 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 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters}
- G09G 3/3266: Details of drivers for scan electrodes
- G09G 3/3275: Details of drivers for data electrodes
- G09G 2300/0819: used for counteracting undesired variations, e.g. feedback or autozeroing
- G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit
- G09G 2310/08: Details of timing specific for flat panels, other than clock recovery
- G09G 2320/02: Improving the quality of display appearance
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
- G09G 2330/08: Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
- 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

Provided herein are systems and methods for measurement and compensation of display panel current leakage and/or display panel noise. A pixel data signal is received at sensing and compensation circuitry. Current leakage compensation circuitry compensates for current leakage of the display panel in the data signal, while panel noise mitigation circuitry configured to reduce panel noise from the data signal. After compensating for the current leakage and reducing the panel noise, the data signal is provided to downstream circuitry for subsequent processing.

## Claims

### Claim 1

An electronic device comprising:
a display panel comprising a plurality of pixels arranged in at least one row and at least one column;
an analog to digital converter; and
a sensing channel coupled to the at least one column and coupled to the analog to digital converter, the sensing channel configured to:
produce a signal representative of a current sourced from at least one of the plurality of pixels;
compensate for current leakage of the display panel in the signal;
compensate for ground noise of the display panel in the signal; and
after the compensation for the current leakage and the ground noise, provide the signal to the analog to digital converter for subsequent adjustment of the at least one of the plurality of pixels.

### Claim 2 (depends on 1)

The electronic device of claim 1, wherein the sensing channel comprises:
a sensing amplifier coupled to an integrating capacitor, wherein the sensing amplifier and the integrating capacitor are configured as an amplifier integrator configured to produce a signal representative of a current of the at least one of the plurality of pixels.

### Claim 3 (depends on 2)

The electronic device of claim 2, wherein:
a negative terminal of the sensing amplifier is configured to receive a pixel current input from the at least one of the plurality of pixels; and
a positive terminal of the sensing amplifier is configured to receive a voltage from a comparison voltage.

### Claim 4 (depends on 2)

The electronic device of claim 2, comprising:
correlated double sampling circuitry coupled to sensing amplifier, the correlated double sampling circuitry configured to compensate for the current leakage.

### Claim 5 (depends on 4)

The electronic device of claim 4, comprising:
automatic gain control circuitry coupled to the correlated double sampling circuitry, the automatic gain control circuitry configured to control a gain of an output signal of the correlated double sampling circuitry to an expected level for the analog to digital converter, wherein an output of the automatic gain control circuitry comprises the signal provided to the analog to digital converter.

### Claim 6 (depends on 2)

The electronic device of claim 2, comprising:
a data voltage source;
a data line coupling the data voltage source and the integrating capacitor;
a line capacitor coupled to the data line; and
a set of switches that, when selectively configured, cause programming of the integrating capacitor by:
discharging the integrating capacitor; and
charging the line capacitor to a voltage of the data voltage source.

### Claim 7 (depends on 6)

The electronic device of claim 6, wherein:
the set of switches, when selectively configured, cause a signal representative of the current leakage to be provided to correlated double sampling circuitry.

### Claim 8 (depends on 6)

The electronic device of claim 6, wherein:
the set of switches, when selectively configured, cause a signal representative of the current leakage combined with the pixel current to be provided to a correlated double sampling circuitry and the correlated double sampling circuitry is configured to isolate the pixel current, compensating for the current leakage.

### Claim 9 (depends on 6)

The electronic device of claim 6, comprising:
a second line capacitor;
wherein the line capacitor is coupled to a negative terminal of the sensing amp and panel ground noise;
wherein the second line capacitor is coupled to a positive terminal of the sensing amp and second panel ground noise; and
wherein the panel ground noise and the second panel ground noise cancel each other during integration of the sensing amplifier and the integrating capacitor.

### Claim 10 (depends on 9)

The electronic device of claim 9, wherein:
the set of switches, when selectively configured, cause the second line capacitor to charge to a comparison voltage source, such that any change in the second panel ground noise is inputted to the positive terminal of the sensing amplifier.

### Claim 11 (depends on 2)

The electronic device of claim 2, wherein a current leakage measurement is applied to a positive terminal of the sensing amplifier and a negative terminal of the sensing amplifier, such that the effects of the current leakage are rejected by the sensing amplifier.

### Claim 12

A hardware-circuitry implemented method, comprising:
programming a sensing channel, by programming an integrating capacitor and a line capacitor from a data voltage source;
integrating leakage current at the sensing channel and the integrating capacitor;
reprogramming the sensing channel;
integrating pixel current and the leakage current, using the sensing channel and integrating capacitor; and
isolating the pixel current; and
compensating for panel ground noise.

### Claim 13 (depends on 12)

The method of claim 12, wherein programming the sensing channel comprises:
programming an integrating capacitor and a line capacitor from a data voltage source.

### Claim 14 (depends on 13)

The method of claim 13, comprising triggering the programming of the sensing channel, by:
selectively closing:
a first switch of the integrating capacitor;
a second switch coupling the integrating capacitor with a data line; and
a third switch coupling the data line with the data voltage source; and
selectively opening:
a fourth switch coupling the integrating capacitor with correlated double sampling circuitry;
a fifth switch coupling a pixel current with the data line; and
a sixth switch coupling a current leakage signal with data line.

### Claim 15 (depends on 14)

The method of claim 14, comprising triggering the integrating the leakage current at the sensing channel and the integrating capacitor, by:
selectively closing:
the second switch;
the third switch;
the fourth; and
the sixth switch; and
selectively opening:
the first switch; and
the fifth switch.

### Claim 16 (depends on 14)

The method of claim 14, comprising triggering the reprogramming, by:
selectively closing:
the first switch;
the second switch; and
the third switch; and
selectively opening:
the fourth;
the fifth switch; and
the sixth switch.

### Claim 17 (depends on 16)

The method of claim 16, comprising triggering the integrating the pixel current and the leakage current, by:
selectively closing:
the second switch;
the fourth;
the third switch;
the fifth switch; and
the sixth switch; and
selectively opening:
the first switch.

### Claim 18

Display panel compensation circuitry, comprising:
a sensing channel configured to receive a data signal from at least one pixel of a plurality of pixels of a display panel;
correlated double sampling circuitry configured to compensate for current leakage of the display panel in the data signal;
panel noise mitigation circuitry configured to reduce panel noise from the data signal; and
circuitry that provides the data signal to an analog to digital converter after compensating for the current leakage and reducing the panel noise.

### Claim 19 (depends on 18)

The display panel compensation circuitry of claim 18, comprising:
a sensing amplifier selectively coupleable to the correlated double sampling circuitry via a first switch between the sensing amplifier and the correlated double sampling circuitry;
an integrating capacitor selectively coupleable to a data line via a second switch between the integrating capacitor and the data line;
a pixel current source selectively coupleable to data line via a third switch between the pixel current source and the data line; and
a line capacitor coupled to a voltage data source via the data line.

### Claim 20 (depends on 19)

The display panel compensation circuitry of claim 19, comprising:
a comparison voltage source coupled to a positive terminal of the sensing amplifier;
wherein the pixel current source, the voltage data source, and the integrating capacitor are configured to each be selectively coupled to a negative terminal of the sensing amplifier.