Method and system for programming, calibrating and driving a light emitting device display

• US 8,736,524 B2
• Filed: 08/07/2012
• Issued: 05/27/2014
• Est. Priority Date: 12/15/2004
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Nathan, Arokia, Chaji, Gholamreza Reza, Servati, Peyman
• Primary Examiner(s): ABDULSELAM, ABBAS I
• Application Number:
  US13/568,784
• Publication Number:
  US 20130027381A1
• Time in Patent Office: 658 Days
• Field of Search: 345/76, 345/82, 345/204, 345/212, 3151691-1694
• US Class Current: 345/76
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• 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 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• 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 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 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A method and system for programming, calibrating and driving a light emitting device display is provided. The system may include extracting a time dependent parameter of a pixel for calibration.

Claims

1. A method of driving a display array, the display array including a plurality of pixel circuits, each pixel circuit including a driving transistor, at least one switch transistor, a storage capacitor and an organic light emitting device, the method comprising the steps of:

applying a current or voltage to the organic light emitting device;

monitoring a current or voltage flowing through the organic light emitting device;

predicting a shift in the voltage of the organic light emitting device, based on the monitored current or voltage and determining the state of the pixel circuit, the predicting including estimating an intermediate voltage of the organic light emitting diode, wherein the estimating includes adjusting the intermediate voltage based on a resolution of a driver circuit coupled to the driving transistor and increasing the intermediate voltage by the resolution of the driver circuit responsive to an actual voltage shift being larger than the intermediate voltage; and

providing, to the organic light emitting device, a bias associated with the shift in the voltage of the organic light emitting device.

2. A method according to claim 1, further comprising modifying a programming voltage by a voltage based on the monitored current or voltage such that a substantially constant output brightness of the light emitting device is maintained.

3. A method according to claim 1, wherein the monitoring a current or voltage comprises applying a first current or a first voltage to the light emitting device during a first phase and extracting the monitored voltage or monitored current from the light emitting device during a second phase following the first phase.

4. A method according to claim 3, wherein the monitoring and the extracting are carried out using the same line.

5. A method according to claim 1, wherein the estimating includes decreasing the intermediate voltage by the resolution of the driver circuit responsive to an actual voltage shift being larger than the intermediate voltage.

6. A method according to claim 1, wherein the applying the current or the voltage includes the providing the bias.

7. A method according to claim 1, wherein the monitoring a current or voltage includes:

during a first operating cycle of an extraction cycle, activating a first select line to couple a data line to a gate of the driving transistor through the at least one switch transistor, and

during the first operating cycle, activating a second select line to couple a monitor line to a drain of the driving transistor through a second switch transistor connected to the driving transistor;

during the first operating cycle, applying a first current or a first voltage to the light emitting device via the monitor line while maintaining the data line at a first potential; and

during a second operating cycle following the first operating cycle, deactivating the first select line switching while the second select line remains activated and the data line remains at the first potential, extracting a monitored voltage or monitored current from the light emitting device via the monitor line.

8. A method of driving a display array, the display array including a plurality of pixel circuits, each pixel circuit including a driving transistor, at least one switch transistor, a storage capacitor and an organic light emitting device (OLED), the method comprising the steps of:

applying a current or voltage to the OLED;

monitoring a current or voltage flowing through the OLED;

predicting a shift in the voltage of the OLED, based on the monitored current or voltage and determining the state of the pixel circuit; and

providing, to the OLED, a bias associated with the shift in the voltage of the OLED,

wherein the monitoring the current or voltage includes;

during a first operating cycle of an extraction cycle, activating a first select line to couple a data line to a gate of the driving transistor through the at least one switch transistor;

during the first operating cycle, activating a second select line to couple a monitor line to a drain of the driving transistor through a second switch transistor connected to the driving transistor;

during the first operating cycle, applying a first current or a first voltage to the light emitting device via the monitor line while maintaining the data line at a first potential; and

during a second operating cycle following the first operating cycle, deactivating the first select line while the second select line remains activated and the data line remains at the first potential; and

extracting a monitored voltage or monitored current from the OLED via the monitor line.

9. A method of driving a display array, the display array including a plurality of pixel circuits, each pixel circuit including a driving transistor, at least one switch transistor, a storage capacitor and an organic light emitting device (OLED), the method comprising the steps of:

applying a current or voltage to the OLED;

monitoring a current or voltage flowing through the OLED;

predicting a shift in the voltage of the OLED, based on the monitored current or voltage and determining the state of the pixel circuit, wherein the predicting includes estimating an intermediate voltage of the OLED, the estimating including adjusting the intermediate voltage based on a resolution of a driver circuit coupled to the driving transistor and decreasing the intermediate voltage by the resolution of the driver circuit responsive to an actual voltage shift being larger than the intermediate voltage; and

providing, to the OLED, a bias associated with the shift in the voltage of the OLED.