Method and apparatus for sensing, measurement or characterization of display elements integrated with the display drive scheme, and system and applications using the same

• US 8,169,426 B2
• Filed: 02/11/2009
• Issued: 05/01/2012
• Est. Priority Date: 02/11/2008
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Govil, Alok
• Primary Examiner(s): HUBER, PAUL W
• Application Number:
  US12/369,678
• Publication Number:
  US 20100039409A1
• Time in Patent Office: 1,175 Days
• Field of Search: None
• US Class Current: 345/204
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 99/003 Characterising MEMS devices, e.g. measuring and identifying electrical or mechanical constants
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• 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 3/3466 based on interferometric effect

Abstract

Methods and systems for electrical sensing, measurement and characterization of display elements are described. An embodiment includes integrating the electrical sensing, measurement and characterization with the display drive scheme. This embodiment allows for measurement of DC or operational hysteresis voltages and/or response times of interferometric modulator MEMS devices, for example, to be fully integrated with the display driver IC and/or the display drive scheme. Another embodiment allows these measurements to be performed and used without resulting in display artifacts visible to a human user. Another embodiment allows the measurement circuitry to be integrated with the display driver IC and/or the display drive scheme re-using several existing circuitry components and features, thus allowing for integration of the measurement method and its use relatively easily.

Claims

1. A method, comprising:

applying a signal waveform across a first electrode and a second electrode of a device, wherein the signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer;

measuring an electrical response of the device in response to the applied signal; and

determining at least one operational characteristic of the device based on the measured electrical response.

2. The method of claim 1, wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds.

3. The method of claim 1, wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds.

4. The method of claim 1, further comprising repeating the applying, measuring and determining on a periodic time basis.

5. The method of claim 1, further comprising repeating the applying, measuring and determining on a pseudorandom time basis.

6. The method of claim 1, further comprising repeating the applying, measuring and determining at a time based on a temperature change.

7. The method of claim 1, further comprising performing the applying, measuring and determining based on an age of the device.

8. The method of claim 1, wherein applying the signal waveform is performed multiple times at various voltages and an operational characteristic is determined for each of the various voltages, the method further comprising:

storing information indicative of the operational characteristic and the voltage level for each of the various voltages, and

determining a drive voltage level based on the stored information and a predetermined operational characteristic.

9. The method of claim 1, wherein determining the at least one operational characteristic comprises determining one or more of an actuation voltage, a release voltage and a response time.

10. The method of claim 1, wherein the voltage waveform comprises one or more of a sinusoid, a saw tooth and a rectangular pulse.

11. An apparatus, comprising:

drive circuitry configured to apply a signal across a first electrode and a second electrode of a device, wherein the signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer;

feedback circuitry configured to measure an electrical response of the device in response to the applied voltage waveform; and

a processor configured to control the drive circuitry, receive information indicative of the measured electrical response, and determine at least one operational characteristic of the device based on the measured electrical response.

12. The apparatus of claim 11, wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds.

13. The apparatus of claim 11, wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds.

14. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the signal on a periodic time basis.

15. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the signal on a pseudorandom time basis.

16. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the signal at a time based on a temperature change.

17. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the signal based on the age of the device.

18. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the signal multiple times at various levels, determine an operational characteristic associated with each of the multiple levels, store information indicative of the operational characteristics and the levels, and determine a drive level based on the stored information and a predetermined operational characteristic.

19. The apparatus of claim 18, wherein the at least one operational characteristic comprises one or more of an actuation voltage, a release voltage and a response time.

20. The apparatus of claim 11, wherein the signal comprises one or more of a sinusoid, a saw tooth and a rectangular pulse.

21. The apparatus of claim 11, wherein the processor is configured to control the drive circuitry to apply the voltage waveform to provide temporal averaging of a displayed color.

22. A device, comprising:

means for applying a signal across a first electrode and a second electrode of the device, wherein the signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer;

means for measuring an electrical response of the device in response to the applied signal; and

means for receiving information indicative of the measured electrical response and for determining at least one operational characteristic of the device based on the measured electrical response.

23. The device of claim 22, wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds.

24. The device of claim 22, wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds.

25. The device of claim 22, wherein the applying means is configured to apply the signal at a time based on a temperature change.

26. The device of claim 22, wherein the applying means is configured to apply the signal at a time based on an age of the device.

27. The device of claim 22, the wherein the applying means is configured to apply the signal multiple times at various voltages and the means for receiving is configured to determine an operational characteristic for each of the various signals, the device further comprising:

means for storing information indicative of the operational characteristic and the voltage level for each of the various voltages, and

means for determining a drive voltage level based on the stored information and a predetermined operational characteristic.

28. The device of claim 22, wherein the means for receiving is configured to determine one or more of an actuation voltage, a release voltage and a response time.

29. A device comprising:

an array of interferometric modulators;

drive circuitry configured to apply a signal across a first electrode and a second electrode of at least one of the interferometric modulators, wherein the signal alters a state of the interferometric modulator from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer;

feedback circuitry configured to measure an electrical response of the interferometric modulator in response to the applied voltage waveform;

a processor configured control the drive circuitry, receive information indicative of the measured electrical response, and determine at least one operational characteristic of the interferometric modulator based on the measured electrical response; and

a memory device configured to communicate with the processor.

30. The device of claim 29, further comprising a controller configured to send at least a portion of the image data to the drive circuitry.

31. The device of claim 29, further comprising an image source module configured to send the image data to the processor.

32. The device of claim 31, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

33. The device of claim 29, further comprising an input device configured to receive input data and to communicate the input data to the processor.