Measurement and apparatus for electrical measurement of electrical drive parameters for a MEMS based display

• US 8,355,883 B2
• Filed: 06/18/2012
• Issued: 01/15/2013
• 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, Djordjev, Kostadin, Lewis, Alan, Van Lier, Wilhelmus Johannes Robertus
• Primary Examiner(s): Le, John H
• Application Number:
  US13/526,258
• Publication Number:
  US 20120256615A1
• Time in Patent Office: 211 Days
• Field of Search: 702/64, 702/65, 702/104, 702/116, 702/117, 341/152, 345/108, 324/73.1, 324/117.R, 324/658, 324/671, 359/254, 359/290, 359/291, 359/298, 359/318, 361/207
• US Class Current: 702/64
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 99/0045 End test of the packaged device
• CPC Class Codes: G01R 19/0046 characterised by a specific application or detail not covered by any other subgroup of G01R19/00
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: G09G 5/003 Details of a display terminal, the details relating to the control arrangement of the display terminal and to the interfaces thereto specific for a CRT G09G1/165; for a flat panel G09G3/2092

Abstract

Methods and devices to measure voltage margins of electromechanical devices are disclosed. The voltage margins are determined based on responses to test voltages which cause the devices to change states. State changes of the devices are detected by monitoring integrated current or charge used to drive the devices with the test voltages.

Claims

1. A method of measuring a margin for an electromechanical device, the device comprising an array of elements, the method comprising:

initializing the elements of the array to a first state;

applying a positive hold voltage to a first portion of the array;

applying a negative hold voltage to a second portion of the array;

while applying the positive and negative hold voltages, applying a test pulse to the elements of the array;

applying a negative voltage transition to the first portion of the array to apply the negative hold voltage to the first portion of the array;

applying a positive voltage transition to the second portion of the array to apply the positive hold voltage to the second portion of the array;

sensing a difference between charge induced by the positive voltage transition and charge induced by the negative voltage transition to determine whether the test pulse changed the state of one or more elements of the array; and

determining the margin based on whether the test pulse changed the state of one or more elements of the array.

2. The method of claim 1, wherein the positive and negative hold voltages and the positive and negative voltage transitions are applied with a dedicated driver.

3. The method of claim 1, wherein the first state is an actuated state and the margin is a release margin.

4. The method of claim 1, wherein the first state is a released state and the margin is an actuation margin.

5. The method of claim 1, wherein sensing the charge comprises integrating a current applied to the device.

6. The method of claim 1, wherein sensing the charge comprises digitally integrating a current applied to the device.

7. The method of claim 1, wherein sensing the charge comprises measuring current applied to the device.

8. The method of claim 1, wherein the voltage transitions are applied to the device in response to the device being actuated.

9. The method of claim 1, wherein the voltage transitions are applied to the device in response to the device being turned on.

10. An electromechanical device, comprising:

an array of elements configured to be driven to an actuated state as a result of being driven with an actuation voltage, to be driven to a released state as a result of being driven with a release voltage, and to maintain a current state as a result of being driven with a hold voltage;

a driver configured to;

initialize the elements to a first state,

apply a positive hold voltage to a first portion of the array,

apply a negative hold voltage to a second portion of the array,

apply a test pulse to the elements of the array while applying the positive and negative hold voltages,

apply a negative voltage transition to the first portion of the array to apply the negative hold voltage to the first portion of the array,

apply a positive voltage transition to the second portion of the array to apply the positive hold voltage to the second portion of the array;

a first circuit configured to sense a difference between charge induced by the positive voltage transition and charge induced by the negative voltage transition to determine whether the test pulse changed the state of one or more elements of the array; and

a second circuit configured to determine the margin based on whether the test pulse changed the state of one or more elements of the array.

11. The device of claim 10, wherein the first state is an actuated state and the margin is a release margin.

12. The device of claim 10, wherein the first state is a released state and the margin is an actuation margin.

13. The device of claim 10, wherein the first circuit is configured to integrate a current applied to the device to sense the charge difference.

14. The device of claim 10, wherein the first circuit is configured to measure a current applied to the device to sense the charge difference.

15. The device of claim 10, wherein the driver is configured to apply the voltage transitions in response to the device being turned on.

16. An electromechanical device, comprising:

an array of elements configured to be driven to an actuated state as a result of being driven with an actuation voltage, to be driven to a released state as a result of being driven with a release voltage, and to maintain a current state as a result of being driven with a hold voltage;

means for initializing the elements of the array to a first state;

means for applying a positive hold voltage to a first portion of the array;

means for applying a negative hold voltage to a second portion of the array;

means for applying a test pulse to the elements of the array while applying the positive and negative hold voltages;

means for applying a negative voltage transition to the first portion of the array to apply the negative hold voltage to the first portion of the array;

means for applying a positive voltage transition to the second portion of the array to apply the positive hold voltage to the second portion of the array;

means for sensing a difference between charge induced by the positive voltage transition and charge induced by the negative voltage transition to determine whether the test pulse changed the state of one or more elements of the array; and

means for determining the margin based on whether the test pulse changed the state of one or more elements of the array.

17. The device of claim 16, wherein the first state is an actuated state and the margin is a release margin.

18. The device of claim 16, wherein the first state is a released state and the margin is an actuation margin.

19. The device of claim 16, wherein the initializing means and each of the applying means comprise a driver.

20. The device of claim 18, wherein the sensing means and determining means each comprise a circuit.