System for providing pulse amplitude modulation for oled display drivers

• US 20020167471A1
• Filed: 12/20/2001
• Published: 11/14/2002
• Est. Priority Date: 05/09/2001
• Status: Active Grant

• Current Assignee: Clare Micronix Integrated Systems, Inc.
• Original Assignee: Clare Micronix Integrated Systems, Inc.
• Inventors: Everitt, James W.
• Granted Patent: US 6,943,761 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• 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 2320/0285 using tables for spatial correction of display data
• 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 3/3216 using a passive matrix

Abstract

A pulse width modulation driver for an organic light emitting diode display. One embodiment of a video display comprises a voltage driver for providing a selected voltage to drive an organic light emitting diode in a video display. The voltage driver may receive voltage information from a correction table that accounts for aging, column resistance, row resistance, and other diode characteristics.

Claims

1. A video display, comprising:

a voltage correction table;

a calibration unit configured to generate data in the voltage correction table; and

at least one driver configured to drive at least one organic light emitting diode at a voltage defined, at least in part, by the voltage correction table.

2. The video display of claim 1, wherein the voltage correction table includes a current to voltage lookup table, and wherein the driver uses data in the voltage lookup table, at least in part, to determine the driving voltage.

3. The video display of claim 2, wherein the data in the current to voltage correction table is generated by providing a plurality of reference currents across at least the diode, measuring the corresponding output voltage, and storing the output voltage in the voltage correction table.

4. The video display of claim 1, wherein the voltage correction table includes a pixel offset compensation table, and wherein the driver uses the pixel offset compensation table, at least in part, to determine the driving voltage.

5. The video display of claim 1, wherein the voltage correction table includes a column resistance lookup table, and wherein the driver uses the pixel offset compensation table, at least in part, to determine the driving voltage.

6. The video display of claim 1, wherein the organic light emitting diode is part of a passive matrix of light emitting diodes.

7. The video display of claim 1, wherein the driver includes at least two capacitors, wherein the first of the at least two capacitors is chargeable to a first voltage to drive current across an organic light emitting diode in a first row of the video display, and wherein the second of the at least two capacitors is chargeable to a second voltage to drive current across an organic light emitting diode in a second row of the video display.

8. A video display, comprising:

a current to voltage correction table, wherein data in the current to voltage correction table is generated by;

providing a plurality of reference currents across a plurality of organic light emitting diodes, measuring a first set of output voltages for each of the reference currents, averaging the measured voltages for each of the reference currents, and storing the averaged output voltage in the voltage correction table for each of the reference currents;

a pixel offset compensation table, wherein data in the pixel offset compensation table is generated by;

driving each of the diodes with a known current, measuring a second set of output voltages, subtracting the stored average from the measured output voltages that corresponds to the known current, and storing the differences in the pixel offset compensation table;

a column resistance correction lookup table that indicates the column resistance of at least one of the organic light emitting diodes in the video display;

a calibration unit configured to generate the data in the current to voltage correction table, the pixel offset compensation table and the column resistance correction table; and

at least one driver configured to drive at least one organic light emitting diode at a voltage defined, at least in part, by the current to voltage correction table, the pixel offset compensation table and the column resistance correction table.

9. A video display, comprising:

a calibration unit configured to generate data for storage in a voltage correction table; and

at least one driver configured to drive a determined voltage and cause illumination of at least one pixel in the display, wherein the driver uses the data in the voltage correction table, at least in part, in determining an output voltage, wherein the driver includes at least two capacitors, wherein the first of the at least two capacitors is chargeable to a first voltage to drive current across a first organic light emitting diode in a first row of the video display, and wherein the second of the at least two capacitors is chargeable to a second voltage to drive current across a second organic light emitting diode in a second row of the video display.

10. The video display of claim 9, wherein the first organic light emitting diode and the second organic light emitting diode are each part of a passive matrix of light emitting diodes.

11. A video display, comprising at least one driver for driving a determined voltage and causing illumination of a pixel in the video display, wherein the driver uses the data in a voltage correction table, at least in part, in determining an output voltage, and wherein the at least one driver drives at least one organic light emitting diode.

12. The video display of claim 11, wherein the driver includes at least two capacitors, wherein the first of the at least two capacitors is chargeable to a first voltage to drive current across an organic light emitting diode in a first row of the video display, and wherein the second of the at least two capacitors is chargeable to a second voltage to drive current across an organic light emitting diode in a second row of the video display.

13. The video display of claim 11, wherein the organic light emitting diode is part of a passive matrix of light emitting diodes.

16. The video display of claim 14, wherein the driver includes at least two capacitors, wherein the first of the at least two capacitors is chargeable to a first voltage to drive current across an organic light emitting diode in a first row of the video display, and wherein the second of the at least two capacitors is chargeable to a second voltage to drive current across an organic light emitting diode in a second row of the video display.

17. The video display of claim 14, wherein the organic light emitting diode is part of a passive matrix of light emitting diodes.

19. The system of claim 18, additionally comprising means for generating the data for storage in the correction table.

20. The system of claim 18, additionally comprising:

means for charging a first capacitor, wherein the first capacitor is charged to a first voltage to drive current across an organic light emitting diode in a first row of the video display; and

means for concurrently using a second capacitor to drive a current across an organic light emitting diode in a second row of the video display.

14. A video display, comprising:

at least one driver configured to provide a determined voltage;

a current to voltage correction table that includes voltage data which identifies a voltage that is needed to provide a selected current to an average organic light emitting diode;

a pixel offset compensation table that includes voltage data which identifies a at least one voltage characteristic of a particular organic light emitting diode in the video display; and

a column resistance correction lookup table that includes voltage data that is used by the driver to compensate for resistance of columns in the video display.

15. A video display, comprising:

a matrix of organic light emitting diodes; and

at least one driver configured to drive a determined voltage across at least one of the organic light emitting diodes in the matrix and, wherein the at least one driver causes illumination of at least one of the organic light emitting diodes.

18. A system, comprising:

means for storing voltage data in a correction table;

means for determining a voltage using at least in part the voltage data from the correction table; and

means for applying the determined voltage across an organic light emitting diode.