Display systems with compensation for line propagation delay

• US 9,368,063 B2
• Filed: 11/20/2014
• Issued: 06/14/2016
• Est. Priority Date: 05/23/2012
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza, Azizi, Yaser
• Primary Examiner(s): Edun, Muhammad N
• Application Number:
  US14/549,030
• Publication Number:
  US 20150077315A1
• Time in Patent Office: 572 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G09G 1/002 Intensity circuits G09G1/06 - G09G1/28 take precedence
• CPC Class Codes: G09G 1/12 the deflection signals being produced by essentially analogue means
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• 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 3/18 using liquid crystals
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A method for characterizing and eliminating the effect of propagation delay on data and monitor lines of AMOLED panels is introduced. A similar technique may be utilized to cancel the effect of incomplete settling of select lines that control the write and read switches of pixels on a row.

Claims

1. A method of extracting a propagation delay effect in a display system having a pixel circuit to allow the pixel circuit sufficient time during a programming budget to settle, the pixel circuit having a light emitting device driven by a driving transistor, the pixel circuit connected to a signal line for providing programming information to the pixel circuit for influencing the current through the driving transistor and a monitor line for measuring current levels through at least the driving transistor, the method comprising:

first programming the pixel circuit with a first time duration sufficient to avoid settling effects on the signal line;

responsive to the first programming, measuring, from the monitor line, a current from the pixel circuit to produce a first measurement;

second programming the pixel circuit with a second time duration different from the first time duration;

responsive to the second programming, measuring, from the monitor line, a current from the pixel circuit to produce a second measurement;

comparing the first measurement and the second measurement to extract a propagation delay effect on the signal line; and

storing a representation of the extracted propagation delay effect in a memory device.

2. The method of claim 1, further comprising using the propagation delay as a feedback for compensating for aging of the pixel circuit and hysteresis.

3. The method of claim 1, wherein the extracting the propagation delay effect on the signal line is carried out during an initial factory calibration and used in future operation of the display system.

4. The method of claim 1, further comprising calibrating the measured current using the extracted propagation delay effect.

5. The method of claim 1, further comprising calibrating the programming information for the pixel circuit to account for at least the extracted propagation delay effect.

6. The method of claim 5, wherein the calibration accounts for at least the extracted propagation delay effect and at least one of pixel non-uniformity or hysteresis.

7. The method of claim 5, wherein the first time duration or the second time duration varies as a function of a physical distance of the pixel circuit from a readout circuit that carries out the measuring.

8. The method of claim 5, wherein the first time duration or the second time duration is a function of a row position of the pixel circuit in the display system.

9. The method of claim 5, further comprising determining a pixel non-uniformity effect using the extracted propagation delay effect.

10. The method of claim 5, further comprising extracting aging information associated with the pixel circuit during non-active frame times.

11. The method of claim 10, wherein the non-active frame times include a reset frame, a blanking frame, or during a display standby time.