Pixels and reference circuits and timing techniques

• US 10,657,895 B2
• Filed: 10/30/2017
• Issued: 05/19/2020
• Est. Priority Date: 07/24/2015
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza, Azizi, Yaser, Moradi, Arash, Liu, Hongxin
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): Frank, Emily J
• Application Number:
  US15/797,661
• Publication Number:
  US 20180068611A1
• Time in Patent Office: 932 Days
• Field of Search: None
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2330/10 Dealing with defective pixels
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: 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
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

What is disclosed are systems and methods of compensation of images produced by active matrix light emitting diode device (AMOLED) and other emissive displays. Anomalies in luminance produced by pixel circuits and bias currents produced by current biasing circuits for driving current biased voltage programmed pixels are corrected through calibration and compensation while re-using existing data or other lines that can be controlled individually to perform said calibration and compensation.

Claims

1. A display system, including a plurality of pixels, comprising:

a controller for receiving digital data indicative of information to be displayed on the display system;

a source driver for receiving data from the controller and for transmitting data signals to each pixel during a programming phase, and including a monitoring system integrated therewith for measuring a current or voltage associated with each pixel for extracting information indicative of a degradation of each pixel during a measurement phase;

a plurality of combined data/monitor lines extending from the source driver for transmitting both data and monitor signals during alternating programming and measurement phases, respectively;

a plurality of data lines extending to each pixel;

a plurality of monitor lines extending to each pixel for measuring a current or voltage associated with each pixel after the programming phase; and

a switching system coupled to each pixel via a data line and via a monitor line different from said data line, and coupled via a combined data/monitor line to the source driver, said switching system for alternatively connecting each combined data/monitor line with the data line and the monitor line respectively to steer to the pixel over the data line, signals received from the source driver over the combined data/monitor line, and to steer to the source driver over the combined data/monitor line, signals received from the pixel over the monitor line.

2. The display system according to claim 1, wherein each pixel comprises:

a light-emitting device;

a storage element coupled to one of the data lines for storing a programming signal during the programming phase;

a driving transistor switch for conveying a drive current from a first supply line to the light emitting device according to the programming signal to emit light at a desired amount of luminance during an emission phase;

an access transistor switch for selectively connecting the storage element to the source driver during the programming phase, and disconnecting the storage element from the source driver during the emission phase; and

a monitor transistor switch for selectively connecting the respective pixel to the respective monitor line.

3. The display system according to claim 2, wherein the source driver is capable of:

charging each storage element to a defined level, based on the respective data signal, during a programming cycle; and

subsequent to the programming cycle, during a calibration cycle, partially discharging the storage element as a function of characteristics of the driving transistor switch.

4. The display system of claim 3, wherein the source driver is capable of:

during the programming cycle, charging the storage element connected to a gate terminal of the driving transistor switch to include at least a threshold voltage of the driving transistor switch, such that during the emission cycle, a voltage across the source terminal and the drain terminal is a function of the threshold voltage of the driving transistor switch.

5. The display of claim 2, further comprising first and second supply lines connected to each pixel for providing a first and a second potential, respectively, thereto from a voltage supply for supplying the drive current to the light emitting device via the driving transistor switch;

wherein the controller is capable of raising the second potential to equal the first potential to avoid interference from the light emitting device during the measurement phase.

6. The display system according to claim 1, wherein each switching system comprises a first switch for selectively connecting the respective data line to the respective combined data/monitor line;

and a second switch for selectively connecting the respective monitor line to the respective combined data/monitor line.

7. The display system according to claim 6, wherein the source driver is capable of actuating the first switch and deactivating the second switch during the programming phase;

and actuating the second switch and deactivating the first switch during the measurement phase.

8. The display system according to claim 6, further comprising a biasing circuit coupled to each monitor line;

wherein each switching system also comprises a third switch for selectively connecting the respective biasing circuit to each monitor line.

9. The display system according to claim 8, wherein the source driver is capable of actuating the first and third switches and deactivating the second switch during the programming phase;

and actuating the second switch and deactivating the first and third switches during the measurement phase.

10. The display system according to claim 1, wherein each combined data/monitor line is connected to respective first and second data lines;

wherein each switching system comprises a first switch for selectively connecting the first data line to the combined data/monitor line;

a second switch for selectively connecting the second data line to the combined data/monitor line; and

a third switch for selectively connecting the monitor line to the combined data/monitor line.

11. The display system according to claim 10, wherein the source driver is capable of actuating the first and second switches in sequence and deactivating the third switch during the programming phase;

and actuating the third switch and deactivating the first and second switches during the measurement phase.

12. The display system according to claim 10, further comprising a biasing circuit coupled to each monitor line;

wherein each switching system also comprises a fourth switch for selectively connecting the biasing circuit to each monitor line.

13. The display system according to claim 12, wherein the source driver is capable of actuating the first and second switches, in sequence, actuating the fourth switch, and deactivating the third switch during the programming phase;

and actuating the third switch and deactivating the first, second and fourth switches during the measurement phase.