Electro-optical measurement of hysteresis in interferometric modulators
View Patent ↗Disclosed herein are methods and apparatus for testing interferometric modulators. The interferometric modulators may be tested by applying a time-varying voltage stimulus and measuring the resulting reflectivity from the modulators.
1. A method of testing a plurality of interferometric modulators, comprising:
applying a triangular voltage waveform to the interferometric modulators; and
detecting reflectivity of light from the interferometric modulators, wherein the detecting includes measuring reflectivity through a diffuser positioned between a light detector and the interferometric modulators.
2. The method of claim 1 , wherein the step of applying a triangular waveform causes the interferometric modulators to vary between an actuated and a non-actuated state.
3. The method of claim 1 , wherein the triangular waveform has a frequency of less than about 20 Hz.
4. The method of claim 3 , wherein the triangular waveform has a frequency from about 1 Hz to about 15 Hz.
5. The method of claim 1 , wherein the amplitude of the triangular waveform is greater than the voltage necessary to cause a positive or negative going actuation of the interferometric modulators.
6. The method of claim 5 , wherein the amplitude of the triangular waveform is less than about 1.5 times the voltage necessary to cause a positive or negative going actuation of the interferometric modulators.
7. The method of claim 1 , wherein the triangular voltage waveform is simultaneously applied to all interferometric modulators in a reflective display.
8. The method of claim 1 , wherein the detecting step includes detecting reflectivity from less than all interferometric modulators in a reflective display.
9. The method of claim 1 , wherein the detecting step includes measuring reflectivity with a photodetector.
10. The method of claim 1 , wherein the detecting step includes measuring reflectivity at an angle that is substantially perpendicular to the interferometric modulators.