MEASUREMENT AND APPARATUS FOR ELECTRICAL MEASUREMENT OF ELECTRICAL DRIVE PARAMETERS FOR A MEMS BASED DISPLAY

• US 20090204349A1
• Filed: 02/11/2009
• Published: 08/13/2009
• Est. Priority Date: 02/11/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Lewis, Alan, Govil, Alok, Van Lier, Wilhelmus Johannes Robertus, Djordjev, Kostadin
• Granted Patent: US 8,204,703 B2
• Time in Patent Office: Days
• 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 threshold voltages of MEMS devices are disclosed. The threshold voltages are based on test voltages which cause the devices to change states. State changes of the device are detected by monitoring integrated current or charge used to drive the test voltages.

Claims

1. A method of measuring a threshold voltage for a microelectromechanical system (MEMS) device, the method comprising:

applying a plurality of voltage transitions to the device and sensing an amount of charge applied to the device during one or more transitions;

determining, based on the amount of charge sensed, whether each of the one or more transitions changes the state of the device; and

determining the threshold voltage based at least in part on a transition resulting in a state change.

2. The method of claim 1, wherein the voltage transitions are applied to the MEMS device with a dedicated driver.

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

4. The method of claim 1, wherein determining the threshold voltage comprises determining a voltage sufficient to cause a movable element of the device to move.

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 measuring current applied to the device.

7. The method of claim 1, wherein sensing the charge comprises at least one of digitally integrating a signal and analog integrating a signal.

8. The method of claim 1, further comprising:

connecting a terminal of the device to a ground and applying an initialization voltage, wherein the device is thereafter in an initial state;

connecting the terminal of the device to an integrator circuit prior to applying the plurality of voltage transitions; and

sensing the charge with the integrator circuit.

9. The method of claim 8, further comprising:

connecting the terminal of the device to a first integrator prior to a positive voltage transition;

sensing the charge with the first integrator circuit to determine a first threshold;

connecting the terminal of the device to a second integrator prior to a negative voltage transition; and

sensing the charge with the second integrator circuit to determine a second threshold.

10. The method of claim 1, wherein the device comprises a plurality of elements, the method further comprising:

applying a plurality of voltage transitions to each of the elements and sensing an amount of charge applied to the device during one or more transitions;

determining, based on the amount of charge sensed, whether each of the one or more transitions changes the state of a determined number of elements; and

determining the threshold voltage based at least in part on a transition resulting in a state change of the determined number of elements.

11. The method of claim 1, further comprising:

sensing the charge applied to the device while applying one or more positive voltage transitions to the device;

applying a test voltage to the device;

sensing the charge applied to the device while applying one or more negative voltage transitions to the device; and

determining whether the test voltage changed the state of the device based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

12. The method of claim 1, wherein the device comprises an array of elements and the plurality of transitions comprises positive voltage transitions and negative voltage transitions, the method further comprising:

applying positive voltage transitions to a first portion of the array; and

applying negative voltage transitions to a second portion of the array; and

determining whether the state of a number of elements changed based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

13. The method of claim 12, wherein the first and second portions of the array each comprise one or more columns, and each of the columns of the first portion is adjacent to at least one column of the second portion.

14. The method of claim 1, wherein the threshold voltage is one of an actuation threshold and a release threshold, and the method further comprises:

determining that a state change has occurred;

determining a next voltage transition to apply, the next voltage transition determined so as to measure a second threshold, the second threshold being the other of the actuation threshold and the release threshold; and

applying the next transition to the device.

15. The method of claim 1, wherein the threshold voltage is one of a positive threshold and a negative threshold, and the method further comprises:

determining a second threshold, the second threshold being the other of the positive threshold and the negative threshold; and

determining an offset voltage, wherein the offset voltage is substantially the average of the positive threshold and the negative threshold.

16. The method of claim 2, further comprising determining a release threshold voltage based at least in part on a transition resulting in the device changing from an actuated state to a released state.

17. The method of claim 16, wherein the release threshold voltage is a DC threshold voltage.

18. The method of claim 16, wherein the transitions each have a starting voltage and an ending voltage, and the starting and ending voltages have the same polarity.

19. The method of claim 2, further comprising determining an actuation threshold voltage based at least in part on a transition resulting in the device changing from a released state to an actuated state.

20. The method of claim 19, wherein the actuation threshold voltage is a DC threshold voltage.

21. The method of claim 2, further comprising determining an actuation threshold voltage based at least in part on a particular transition resulting in the device changing from a released state to an actuated state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

22. The method of claim 21, wherein the actuation threshold voltage is about equal to the ending voltage of the particular transition.

23. The method of claim 21, wherein the starting voltage and the ending voltage have substantially equal magnitude with respect to an offset voltage.

24. The method of claim 21, wherein the actuation threshold voltage is a flash threshold voltage.

25. The method of claim 21, further comprising:

determining a second threshold prior to applying the transitions; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

26. The method of claim 25, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a flash threshold voltage.

27. The method of claim 2, further comprising determining a release threshold voltage based at least in part on a particular transition resulting in the device changing from an actuated state to a released state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

28. The method of claim 27, wherein the release threshold voltage is about equal to the ending voltage of the particular transition.

29. The method of claim 27, wherein the starting voltage and the ending voltage have substantially equal magnitude with respect to an offset voltage.

30. The method of claim 27, wherein the release threshold voltage is a flash threshold voltage.

31. The method of claim 27, further comprising:

determining a second threshold prior to applying the transitions; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

32. The method of claim 31, wherein the second threshold voltage is a DC threshold voltage, and the release threshold voltage is a flash threshold voltage.

33. The method of claim 2, the device comprising a plurality of elements, the method further comprising determining a release threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from a released to an actuated state.

34. The method of claim 33, wherein the release threshold voltage is about equal to the ending voltage of the particular transition.

35. The method of claim 33, wherein the device comprises an array of elements, and the first element is in a first column of the array and the second element is in a second column of the array.

36. The method of claim 35, wherein the first and second elements are in the same row of the array.

37. The method of claim 33, wherein the device comprises an array of elements, and the first and second elements are separated from the array.

38. The method of claim 33, wherein the release threshold voltage is a crosstalk threshold voltage.

39. The method of claim 33, further comprising:

determining a second threshold prior to applying the transitions; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

40. The method of claim 39, wherein the second threshold is a DC threshold, and the release threshold voltage is a crosstalk threshold voltage.

41. The method of claim 39, wherein the second threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

42. The method of claim 33, further comprising:

determining a second threshold prior to applying the transitions;

determining a third threshold prior to applying the transitions, the third threshold being determined subsequent to determining the second threshold; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

43. The method of claim 40, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

44. The method of claim 2, the device comprising a plurality of elements, the method further comprising determining an actuation threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from an actuated state to a released state.

45. The method of claim 44, wherein the actuation threshold voltage is about equal to the ending voltage of the particular transition

46. The method of claim 44, wherein the actuation threshold voltage is a crosstalk threshold voltage.

47. The method of claim 44, further comprising:

determining a second threshold prior to applying the transitions; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

48. The method of claim 47, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

49. The method of claim 47, wherein the second threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

50. The method of claim 44, further comprising:

determining a second threshold prior to applying the transitions;

determining a third threshold prior to applying the transitions, the third threshold being determined subsequent to determining the second threshold; and

determining at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

51. The method of claim 50, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

52. The method of claim 1, further comprising determining one or more driving voltages based on the measured threshold voltage.

53. A MEMS device, comprising:

a pair of electrodes;

a driver configured to apply a plurality of voltage transitions across the electrodes;

a sensor configured to indicate an amount of charge applied to the electrodes during one or more transitions;

a comparison circuit configured to determine, based on the amount of charge sensed, whether each of the transitions changes the state of the device; and

a processor configured to determine a threshold voltage based at least in part on a transition resulting in a state change.

54. The MEMS device of claim 53, wherein the driver is dedicated to the MEMS device.

55. The MEMS device of claim 53, wherein the driver is configured to apply the voltage transitions to the MEMS device in response to the MEMS device being turned on.

56. The MEMS device of claim 53, wherein the sensor is further configured to integrate a current applied to the device.

57. The MEMS device of claim 53, wherein the sensor is further configured to measure current applied to the device.

58. The MEMS device of claim 53, wherein the sensor is further configured to at least one of digitally integrate a signal and analog integrate a signal.

59. The MEMS device of claim 53, wherein:

the sensor comprises an integrator circuit, and

the driver is further configured to apply an initialization voltage to the electrodes, wherein the device is thereafter in an initial state, and to thereafter connect one of the electrodes to the integrator circuit prior to applying the plurality of voltage transitions, wherein the integrator circuit is configured to sense the charge applied to the electrodes during the voltage transitions.

60. The MEMS device of claim 59, wherein:

the integrator circuit comprises first and second integrators;

the driver is configured to connect the one electrode to the first integrator prior to a positive voltage transition;

the sensor is configured to sense charge applied to the one electrode with the first integrator circuit during the positive voltage transition;

the processor is configured to determine a first threshold based on the charge sensed during the positive voltage transition;

the driver is further configured to connect the one electrode to the second integrator prior to a negative voltage transition;

the sensor is further configured to sense charge applied to the one electrode with the second integrator circuit during the negative voltage transition;

the processor is further configured to determine a second threshold based on the charge sensed during the negative voltage transition.

61. The MEMS device of claim 53, further comprising a plurality of elements, wherein:

the driver is further configured to apply a plurality of voltage transitions to each of the elements;

the sensor is further configured to sense charge applied to the electrodes during one or more transitions;

the processor is further configured to determine, based on the amount of charge sensed, whether each of the one or more transitions changes the state of a determined number of elements and to determine a second threshold based on the charge sensed during a transition resulting in a state change of the determined number of elements.

62. The MEMS device of claim 53, wherein:

the driver is further configured to apply one or more positive voltage transitions to the electrodes, apply a test voltage to the electrodes, and apply one or more negative voltage transitions to the electrodes;

the sensor is configured to sense the charge applied to the electrodes at least during the applications of the one or more positive voltage transitions and the one or more negative voltage transitions to the electrodes; and

the processor is further configured to determine whether the test voltage changed the state of the device based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

63. The MEMS device of claim 53, further comprising an array of elements and the transitions comprise positive voltage transitions and negative voltage transitions, wherein the driver is further configured to apply one or more positive voltage transitions to a first portion of the array and to apply one or more negative voltage transitions to a second portion of the array, and the comparison circuit is configured to determine whether the state of a number of elements changed based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

64. The MEMS device of claim 63, wherein the first and second portions of the array each comprise one or more columns, and each of the columns of the first portion is adjacent to at least one column of the second portion.

65. The MEMS device of claim 53, wherein the threshold voltage is one of an actuation threshold and a release threshold, and the processor is configured to determine a next voltage transition to apply, the next voltage transition determined so as to measure a second threshold, the second threshold being the other of the actuation threshold and the release threshold, and the driver is configured to apply the next transition to the device.

66. The MEMS device of claim 53, wherein the threshold voltage is one of a positive threshold and a negative threshold, and the processor is configured to determine a second threshold, the second threshold being the other of the positive threshold and the negative threshold and to determine an offset voltage, wherein the offset voltage is substantially equal to the average of the positive threshold and the negative threshold.

67. The MEMS device of claim 53, wherein the transitions each have a starting voltage and an ending voltage, and the starting and ending voltages have the same polarity.

68. The MEMS device of claim 67, wherein the threshold voltage is a DC release threshold voltage.

69. The MEMS device of claim 67, wherein the actuation threshold voltage is a DC actuation threshold voltage.

70. The MEMS device of claim 53, the processor further configured to determine an actuation threshold voltage based at least in part on a particular transition resulting in the device changing from a released state to an actuated state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

71. The MEMS device of claim 70, wherein the actuation threshold voltage is a flash threshold voltage.

72. The MEMS device of claim 70, wherein the processor is further configured to determine a second threshold prior to the driver applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

73. The MEMS device of claim 72, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a flash threshold voltage.

74. The MEMS device of claim 53, wherein the processor is configured to determine a release threshold voltage based at least in part on a particular transition resulting in the device changing from an actuated state to a released state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

75. The MEMS device of claim 74, wherein the release threshold voltage is a flash threshold voltage.

76. The MEMS device of claim 74, wherein the processor is configured to determine a second threshold prior to the driver applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

77. The MEMS device of claim 76, wherein the second threshold voltage is a DC threshold voltage, and the release threshold voltage is a flash threshold voltage.

78. The MEMS device of claim 53, further comprising a plurality of elements, wherein the processor is configured to determine a release threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from a released to an actuated state.

79. The MEMS device of claim 78, wherein the device comprises an array of elements, and the first element is in a first column of the array and the second element is in a second column of the array.

80. The MEMS device of claim 79, wherein the first and second elements are in the same row of the array.

81. The MEMS device of claim 78, wherein the device comprises an array of elements, and the first and second elements are separated from the array.

82. The MEMS device of claim 78, wherein the release threshold voltage is a crosstalk threshold voltage.

83. The MEMS device of claim 78, wherein the processor is configured to determine a second threshold prior to applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

84. The MEMS device of claim 83, wherein the second threshold is a DC threshold, and the release threshold voltage is a crosstalk threshold voltage.

85. The MEMS device of claim 83, wherein the second threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

86. The MEMS device of claim 78, wherein the processor is configured to determine second and third thresholds prior to the driver applying the transitions, the third threshold being determined subsequent to determining the second threshold and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

87. The MEMS device of claim 86, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

88. The MEMS device of claim 53, further comprising a plurality of elements, the processor configured to determine an actuation threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from an actuated state to a released state.

89. The MEMS device of claim 88, wherein the actuation threshold voltage is a crosstalk threshold voltage.

90. The MEMS device of claim 88, wherein the processor is configured to determine a second threshold prior to applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

91. The MEMS device of claim 90, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

92. The MEMS device of claim 90, wherein the second threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

93. The MEMS device of claim 88, wherein the processor is configured to determine second and third thresholds prior to applying the transitions, the third threshold being determined subsequent to determining the second threshold, and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

94. The MEMS device of claim 93, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

95. The MEMS device of claim 53, further comprising determining one or more driving voltages based on the measured threshold voltage.

96. The apparatus of claim 53, further comprising:

a display;

a second processor that is configured to communicate with said display, said second processor being configured to process image data; and

a memory device that is configured to communicate with said second processor.

97. The apparatus of claim 96, further comprising a driver circuit configured to send at least one signal to the display.

98. The apparatus of claim 97, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

99. The apparatus of claim 96, farther comprising an image source module configured to send said image data to said second processor.

100. The apparatus of claim 99, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

101. The apparatus of claim 96, further comprising an input device configured to receive input data and to communicate said input data to said second processor.

102. The method of claim 53, wherein the device comprises an array of elements and the plurality of transitions comprises positive voltage transitions and negative voltage transitions, the method further comprising:

applying a positive voltage transition to a first portion of the array; and

applying a negative voltage transition to a second portion of the array,

wherein sensing the amount of charge applied to the device comprises sensing a difference between charge induced by the positive voltage transition and charge induced by the negative voltage transition.

103. The method of claim 102, wherein the positive voltage transition and the negative voltage transition are applied substantially simultaneously.

104. The method of claim 102, further comprising:

applying a first reference voltage to the entire array while applying the positive and negative transitions;

sensing a first difference between the charge induced by the positive voltage transition and the charge induced by the negative voltage transition;

applying a second reference voltage to the entire array while applying additional positive and negative transitions;

sensing a second difference between the charge induced by the additional positive voltage transition and the charge induced by the additional negative voltage transition;

comparing the first and second differences; and

determining an offset voltage to be equal to the reference voltage associated with the minimum of the first and second differences.

105. The method of claim 102, further comprising:

initializing the elements of the array to a first state;

applying a first transition to the first portion of the array;

applying a second transition to the second portion of the array, wherein the polarities of the first and second transitions are opposite;

sensing a difference between charge induced by the first transition and charge induced by the second transition;

after applying the first and second transitions, reinitializing the elements of the array to the first state;

after reinitializing the elements of the array, applying a third transition to the first portion of the array; and

after reinitializing the elements of the array, applying a fourth transition to the second portion of the array, wherein the polarities of the third and fourth transitions are opposite; and

sensing a difference between charge induced by the third transition and charge induced by the fourth transition.

106. The method of claim 105, wherein the first transition and the second transition are applied substantially simultaneously, and the third transition and the fourth transition are applied substantially simultaneously.

107. The method of claim 102, further comprising:

initializing the elements of the array to a released state;

applying a series of positive voltage transitions of different magnitudes to the first portion of the array;

applying a series of negative voltage transitions of different magnitudes to the second portion of the array,

wherein determining the threshold comprises determining an actuation threshold based the magnitudes of the positive and negative transitions and on whether the transitions having the magnitudes changes the state of the device to an actuated state.

108. The method of claim 107, wherein the positive voltage transitions are applied at substantially the same time as the negative voltage transitions.

109. The method of claim 102, further comprising:

initializing the elements of the array to a first state;

applying a first transition to the first portion of the array, wherein the first transition causes the elements of the first portion to be in the first state;

applying a second transition to the second portion of the array, wherein the polarities of the first and second transitions are opposite; and

determining whether the second transition caused the elements of the second portion of the array to change states by sensing a difference between charge induced by the first transition and charge induced by the second transition.

110. The method of claim 109, wherein the first transition and the second transition are applied substantially simultaneously.

111. The method of claim 102, further comprising:

initializing the elements of the array to an actuated state;

applying a series of positive voltage transitions of different magnitudes to the first portion of the array;

applying a series of negative voltage transitions of different magnitudes to the second portion of the array,

wherein determining the threshold comprises determining an actuation threshold based the magnitudes of the positive and negative transitions and on whether the transitions having the magnitudes changes the state of the device to a released state.

112. The method of claim 111, wherein the positive voltage transitions are applied at substantially the same time as the negative voltage transitions.

113. The method of claim 102, further comprising:

applying a first reference voltage to the entire array while applying the positive and negative transitions;

sensing a first difference between the charge induced by the positive voltage transition and the charge induced by the negative voltage transition;

applying a second reference voltage to the entire array while applying additional positive and negative transitions;

sensing a second difference between the charge induced by the additional positive voltage transition and the charge induced by the additional negative voltage transition;

comparing the first and second differences; and

determining an offset voltage to be equal to the reference voltage associated with the minimum of the first and second differences.

114. A method of measuring a margin for a microelectromechanical system (MEMS) device, 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.

115. The method of claim 114, wherein the positive and negative hold voltages and the positive and negative voltage transitions are applied with a dedicated driver.

116. The method of claim 114, further comprising generating a signal indicating that the MEMS device has been turned on.

117. The method of claim 114, wherein the first state is an actuated state and the margin is a release margin.

118. The method of claim 114, wherein the first state is a released state and the margin is an actuation margin.

119. A MEMS device 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, the device comprising:

first and second means for actuating and releasing according to a voltage;

means for applying a plurality of voltage transitions to the first and second actuating and releasing means;

means for indicating an amount of charge applied to the device during one or more transitions;

means for determining, based on the amount of charge sensed, whether each of the one or more transitions changes the state of the device; and

means for determining the threshold voltage based at least in part on a transition resulting in a state change.

120. The MEMS device of claim 119, wherein the first and second actuating and releasing means comprise electrodes.

121. The MEMS device of claim 120, wherein the applying means comprises a driver.

122. The MEMS device of claim 121, wherein the indicating means comprises a sensor.

123. The MEMS device of claim 122, wherein the state change determining means comprises a comparison circuit.

124. The MEMS device of claim 123, wherein the threshold voltage determining means comprises a processor.

125. The MEMS device of claim 119, wherein the applying means is dedicated to the MEMS device.

126. The MEMS device of claim 119, wherein the applying means is configured to apply the voltage transitions to the MEMS device in response to the MEMS device being turned on.

127. The MEMS device of claim 119, wherein the indicating means is further configured to at least one of digitally integrate a signal and analog integrate a signal.

128. The MEMS device of claim 119, wherein:

the indicating means comprises an integrator circuit, and

the applying means is further configured to apply an initialization voltage to the actuating and releasing means, wherein the device is thereafter in an initial state, and to thereafter connect one of the actuating and releasing means to the integrator circuit prior to applying the plurality of voltage transitions, wherein the integrator circuit is configured to sense the charge applied to the actuating and releasing means during the voltage transitions.

129. The MEMS device of claim 128, wherein:

the integrator circuit comprises first and second integrators;

the applying means is configured to connect the one actuating and releasing means to the first integrator prior to a positive voltage transition;

the indicating means is configured to sense charge applied to the one actuating and releasing means with the first integrator circuit during the positive voltage transition;

the threshold voltage determining means is configured to determine a first threshold based on the charge sensed during the positive voltage transition;

the applying means is further configured to connect the one actuating and releasing means to the second integrator prior to a negative voltage transition;

the indicating means is further configured to sense charge applied to the one actuating and releasing means with the second integrator circuit during the negative voltage transition;

the threshold voltage determining means is further configured to determine a second threshold based on the charge sensed during the negative voltage transition.

130. The MEMS device of claim 119, further comprising a plurality of elements, wherein:

the applying means is further configured to apply a plurality of voltage transitions to each of the elements;

the indicating means is further configured to sense charge applied to the actuating and releasing means during one or more transitions;

the threshold voltage determining means is further configured to determine, based on the amount of charge sensed, whether each of the one or more transitions changes the state of a determined number of elements and to determine a second threshold based on the charge sensed during a transition resulting in a state change of the determined number of elements.

131. The MEMS device of claim 119, wherein:

the applying means is further configured to apply one or more positive voltage transitions to the actuating and releasing means, apply a test voltage to the actuating and releasing means, and apply one or more negative voltage transitions to the actuating and releasing means;

the indicating means is configured to sense the charge applied to the actuating and releasing means at least during the applications of the one or more positive voltage transitions and the one or more negative voltage transitions to the actuating and releasing means; and

the threshold voltage determining means is further configured to determine whether the test voltage changed the state of the device based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

132. The MEMS device of claim 119, further comprising an array of elements and the transitions comprise positive voltage transitions and negative voltage transitions, wherein the applying means is further configured to apply one or more positive voltage transitions to a first portion of the array and to apply one or more negative voltage transitions to a second portion of the array, and the state change determining means is configured to determine whether the state of a number of elements changed based on the difference between the charge sensed for positive voltage transitions and the charge sensed for negative voltage transitions.

133. The MEMS device of claim 119, wherein the threshold voltage is one of an actuation threshold and a release threshold, and the threshold voltage determining means is configured to determine a next voltage transition to apply, the next voltage transition determined so as to measure a second threshold, the second threshold being the other of the actuation threshold and the release threshold, and the applying means is configured to apply the next transition to the device.

134. The MEMS device of claim 119, wherein the threshold voltage is one of a positive threshold and a negative threshold, and the threshold voltage determining means is configured to determine a second threshold, the second threshold being the other of the positive threshold and the negative threshold and to determine an offset voltage, wherein the offset voltage is substantially equal to the average of the positive threshold and the negative threshold.

135. The MEMS device of claim 119, wherein the transitions each have a starting voltage and an ending voltage, and the starting and ending voltages have the same polarity.

136. The MEMS device of claim 135, wherein the threshold voltage is a DC release threshold voltage.

137. The MEMS device of claim 135, wherein the actuation threshold voltage is a DC actuation threshold voltage.

138. The MEMS device of claim 119, the threshold voltage determining means further configured to determine an actuation threshold voltage based at least in part on a particular transition resulting in the device changing from a released state to an actuated state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

139. The MEMS device of claim 138, wherein the actuation threshold voltage is a flash threshold voltage.

140. The MEMS device of claim 138, wherein the threshold voltage determining means is further configured to determine a second threshold prior to the applying means applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

141. The MEMS device of claim 140, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a flash threshold voltage.

142. The MEMS device of claim 119, wherein the threshold voltage determining means is configured to determine a release threshold voltage based at least in part on a particular transition resulting in the device changing from an actuated state to a released state, the particular transition having a starting voltage and an ending voltage, the starting and ending voltages having opposite polarities.

143. The MEMS device of claim 142, wherein the release threshold voltage is a flash threshold voltage.

144. The MEMS device of claim 142, wherein the threshold voltage determining means is configured to determine a second threshold prior to the applying means applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

145. The MEMS device of claim 144, wherein the second threshold voltage is a DC threshold voltage, and the release threshold voltage is a flash threshold voltage.

146. The MEMS device of claim 119, further comprising a plurality of elements, wherein the threshold voltage determining means is configured to determine a release threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from a released to an actuated state.

147. The MEMS device of claim 146, wherein the device comprises an array of elements, and the first and second elements are separated from the array.

148. The MEMS device of claim 146, wherein the release threshold voltage is a crosstalk threshold voltage.

149. The MEMS device of claim 146, wherein the threshold voltage determining means is configured to determine a second threshold prior to applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

150. The MEMS device of claim 149, wherein the second threshold is a DC threshold, and the release threshold voltage is a crosstalk threshold voltage.

151. The MEMS device of claim 149, wherein the second threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

152. The MEMS device of claim 146, wherein the threshold voltage determining means is configured to determine second and third thresholds prior to the applying means applying the transitions, the third threshold being determined subsequent to determining the second threshold and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

153. The MEMS device of claim 152, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the release threshold voltage is a crosstalk threshold voltage.

154. The MEMS device of claim 119, further comprising a plurality of elements, the threshold voltage determining means configured to determine an actuation threshold voltage of a first element based at least in part on a particular transition applied to a second element resulting in the first element changing from an actuated state to a released state.

155. The MEMS device of claim 154, wherein the actuation threshold voltage is a crosstalk threshold voltage.

156. The MEMS device of claim 154, wherein the threshold voltage determining means is configured to determine a second threshold prior to applying the transitions and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the second threshold.

157. The MEMS device of claim 156, wherein the second threshold is a DC threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

158. The MEMS device of claim 156, wherein the second threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

159. The HEMS device of claim 154, wherein the threshold voltage determining means is configured to determine second and third thresholds prior to applying the transitions, the third threshold being determined subsequent to determining the second threshold, and to determine at least one of the starting voltage and the ending voltage of at least one transition based on the third threshold.

160. The MEMS device of claim 159, wherein the second threshold is a DC threshold, the third threshold is a flash threshold, and the actuation threshold voltage is a crosstalk threshold voltage.

161. The MEMS device of claim 119, further comprising determining one or more driving voltages based on the measured threshold voltage.

162. The MEMS device of claim 119, wherein the device comprises an array of elements and the plurality of transitions comprises positive voltage transitions and negative voltage transitions, the device further comprising:

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

means for applying a negative voltage transition to a second portion of the array,

wherein the indicating means is configured to sense a difference between charge induced by the positive voltage transition and charge induced by the negative voltage transition.

163. The MEMS device of claim 162, wherein the applying means are configured to apply the positive voltage transition and the negative voltage transition substantially simultaneously.

164. The MEMS device of claim 162, further comprising:

means for applying a first reference voltage to the entire array while applying the positive and negative transitions;

means for sensing a first difference between the charge induced by the positive voltage transition and the charge induced by the negative voltage transition;

means for applying a second reference voltage to the entire array while applying additional positive and negative transitions;

means for sensing a second difference between the charge induced by the additional positive voltage transition and the charge induced by the additional negative voltage transition;

means for comparing the first and second differences; and

means for determining an offset voltage to be equal to the reference voltage associated with the minimum of the first and second differences.

165. The MEMS device of claim 162, further comprising:

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

means for applying a first transition to the first portion of the array;

means for applying a second transition to the second portion of the array, wherein the polarities of the first and second transitions are opposite;

means for sensing a difference between charge induced by the first transition and charge induced by the second transition;

means for reinitializing the elements of the array to the first state after applying the first and second transitions;

means for applying a third transition to the first portion of the array after reinitializing the elements of the array; and

means for applying a fourth transition to the second portion of the array after reinitializing the elements of the array, wherein the polarities of the third and fourth transitions are opposite; and

means for sensing a difference between charge induced by the third transition and charge induced by the fourth transition.

166. The MEMS device of claim 165, wherein the applying means are configured to apply the first transition and the second transition substantially simultaneously, and to apply the third transition and the fourth transition substantially simultaneously.

167. The MEMS device of claim 162, further comprising:

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

means for applying a series of positive voltage transitions of different magnitudes to the first portion of the array;

means for applying a series of negative voltage transitions of different magnitudes to the second portion of the array,

wherein the determining means is configured to determine an actuation threshold based the magnitudes of the positive and negative transitions and on whether the transitions having the magnitudes changes the state of the device to an actuated state.

168. The MEMS device of claim 167, wherein the applying means are configured to apply the positive voltage transitions at substantially the same time as the negative voltage transitions.

169. The MEMS device of claim 119, further comprising:

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

means for applying a first transition to the first portion of the array, wherein the first transition causes the elements of the first portion to be in the first state;

means for applying a second transition to the second portion of the array, wherein the polarities of the first and second transitions are opposite; and

means for determining whether the second transition caused the elements of the second portion of the array to change states by sensing a difference between charge induced by the first transition and charge induced by the second transition.

170. The MEMS device of claim 169, wherein the applying means are configured to apply the first transition and the second transition substantially simultaneously.

171. The MEMS device of claim 119, further comprising:

means for initializing the elements of the array to an actuated state;

means for applying a series of positive voltage transitions of different magnitudes to the first portion of the array;

means for applying a series of negative voltage transitions of different magnitudes to the second portion of the array,

wherein the determining means is configured to determine an actuation threshold based the magnitudes of the positive and negative transitions and on whether the transitions having the magnitudes changes the state of the device to a released state.

172. The MEMS device of claim 171, wherein the applying means are configured to apply the positive voltage transitions at substantially the same time as the negative voltage transitions.

173. The MEMS device of claim 119, further comprising:

means for applying a first reference voltage to the entire array while applying the positive and negative transitions;

means for sensing a first difference between the charge induced by the positive voltage transition and the charge induced by the negative voltage transition;

means for applying a second reference voltage to the entire array while applying additional positive and negative transitions;

means for sensing a second difference between the charge induced by the additional positive voltage transition and the charge induced by the additional negative voltage transition;

means for comparing the first and second differences; and

means for determining an offset voltage to be equal to the reference voltage associated with the minimum of the first and second differences.

174. A MEMS device 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, the device comprising:

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

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.

175. A MEMS device of claim 174, wherein the first state is an actuated state and the margin is a release margin.

176. A MEMS device of claim 175, wherein the first state is a released state and the margin is an actuation margin.