Light modulator with tunable optical state

• US 20070064295A1
• Filed: 09/21/2005
• Published: 03/22/2007
• Est. Priority Date: 09/21/2005
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Piehl, Arthur, Jilani, Adel, Przybyla, James, Nikkel, Eric, McKinnell, James, Faase, Kenneth, Yeh, Bao-Sung
• Granted Patent: US 7,733,553 B2
• Time in Patent Office: Days
• US Class Current: 359/245
• 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

Abstract

An electronic light modulator device for at least partially displaying a pixel of an image, the device comprising first and second reflectors defining an optical cavity therebetween, the optical cavity being selective of an electromagnetic wavelength at an intensity by optical interference, the device having at least first and second optical states, at least one of the optical states being tunable and the other not tunable.

Claims

1. An electronic light modulator device for at least partially displaying a pixel of an image, the device comprising first and second reflectors defining an optical cavity therebetween, the optical cavity being selective of an electromagnetic wavelength at an intensity by optical interference, the device having at least first and second optical states, the first optical state being tunable, and the second optical state not being tunable.

2. The electronic light modulator device of claim 1 formed as a MEMS device.

3. The electronic light modulator device of claim 1 wherein the first and second reflectors form a Fabry-Perot interferometer.

4. An optical interference pixel display comprising a plurality of the electronic light modulator devices of claim 1.

5. An electronic device for displaying a pixel of an image, comprising in combination:

means for interference of electromagnetic radiation including at least two substantially parallel means for reflecting the electromagnetic radiation, and

means for controlling at least one of the at least two means for reflecting to form at least two distinct optical states, at least one of the two distinct optical states being tunable.

6. An optical interference pixel display comprising a plurality of the electronic devices of claim 5.

7. A Fabry-Perot interferometer, comprising:

a) substantially parallel first and second reflector plates having first and second reflecting surfaces respectively, at least one of the first and second reflecting plates being movable, the first and second reflecting surfaces being spaced apart by a variable optical gap between the first and second reflecting surfaces, and

b) at least one fixed electrostatic control plate adapted to control the variable optical gap by application of a control voltage,

the control plate being spaced apart from the first reflector plate by a first distance and being spaced apart from the second reflector plate by a second distance smaller than the first distance.

8. The Fabry-Perot interferometer of claim 7, wherein the second reflector plate is disposed between the first reflector plate and the control plate.

9. The Fabry-Perot interferometer of claim 7, wherein the first reflecting plate is disposed above the second reflecting plate.

10. The Fabry-Perot interferometer of claim 7, wherein the variable optical gap is controllable from a rest state with no control voltage applied to a first optical state and a second optical state, wherein the optical gap in the rest state is smaller than the optical gap in the first optical state, and the optical gap in the first optical state is smaller than the optical gap in the second optical state.

11. The Fabry-Perot interferometer of claim 10, wherein the first optical state is tunable.

12. The Fabry-Perot interferometer of claim 11, wherein the first optical state is tunable to a black state.

13. The Fabry-Perot interferometer of claim 11, wherein the first optical state is tunable for maximum contrast ratio.

14. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 11.

15. The Fabry-Perot interferometer of claim 10, wherein the control voltage is continuously controllable by an analog signal.

16. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 15.

17. The Fabry-Perot interferometer of claim 10, wherein the control voltage is controllable by a digital signal.

18. The Fabry-Perot interferometer of claim 17, wherein the digital signal has a binary value, and wherein a binary zero sets one of the first and second optical states, and wherein a binary one sets the other of the first and second optical states.

19. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 18.

20. The Fabry-Perot interferometer of claim 7, wherein the control plate is grounded, and the second reflecting plate is electrically coupled to a signal source.

21. The Fabry-Perot interferometer of claim 20, wherein the first reflecting plate is held at a fixed electric potential.

22. The Fabry-Perot interferometer of claim 21, wherein the fixed electric potential is above ground.

23. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 21.

24. The Fabry-Perot interferometer of claim 7, wherein the control plate is electrically coupled to a signal source.

25. The Fabry-Perot interferometer of claim 24, wherein the first and second reflecting plates are electrically coupled.

26. The Fabry-Perot interferometer of claim 24, wherein the first and second reflecting plates are electrically grounded.

27. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 24.

28. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 7.

29. An electronic light modulator device for at least partially displaying a pixel of an image, the device comprising first and second reflectors defining an optical cavity therebetween, the optical cavity being selective of an electromagnetic wavelength at an intensity by optical interference, the device having at least first and second optical states characterized by first and second optical gaps respectively, neither of the first and second optical states being tunable by applying an electric potential, and the device having a range of intermediate optical gaps between the first and second optical gaps, any of the intermediate optical gaps being selectable by varying an electric field applied to at least one of the first and second reflectors.

30. An electronic light modulator device for at least partially displaying a pixel of an image, the device comprising:

a) first and second reflectors defining an optical cavity therebetween, the optical cavity being selective of an electromagnetic wavelength at an intensity by optical interference, and

b) first, second, and third electrodes, the first electrode being coupled to the first reflector, the second electrode being coupled to the second reflector, and the third electrode being coupled to a control plate, whereby a number of optical states are selectable by selectively applying an electric potential between at least two of the first, second, and third electrodes,

wherein the number of selectable optical states include at least a first optical state that is tunable and a second optical state that is not tunable.

31. A method for making a light modulator, comprising:

a) providing a substrate having at least an insulating surface,

b) depositing and patterning a conductive electrode on the insulating surface,

c) depositing a first layer of sacrificial material,

d) forming a first reflecting plate having a reflective surface,

e) depositing a second layer of sacrificial material,

f) forming a second reflecting plate having an at least partially reflective surface, and

g) removing the first and second layers of sacrificial material to release at least the second reflecting plate.

32. A light modulator made by the method of claim 31.