Light modulator with concentric control-electrode structure

• US 20060017689A1
• Filed: 09/21/2005
• Published: 01/26/2006
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Nikkel, Eric L., Jilani, Adel, Faase, Kenneth James, Przybyla, James R., Yeh, Bao, McKinnell, James, Piehl, Arthur R.
• Granted Patent: US 7,447,891 B2
• Time in Patent Office: Days
• US Class Current: 345/108
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• 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 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

An electronic 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 a concentric control structure comprising at least an inner and an outermost electrode, the optical cavity being controlled only by the inner electrode.

Claims

1. An electronic 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 a concentric control structure comprising at least an inner and an outermost electrode, and the optical cavity being controlled by the inner electrode.

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

3. The electronic 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 devices of claim 1.

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

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

concentric means for controlling at least one of the at least two means for reflecting, having at least inner and outer portions, the means for reflecting being controlled by the inner portion of the concentric means for controlling.

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) a fixed electrostatic control structure adapted to control the variable optical gap by application of a control voltage,

the control structure 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, and

the control structure comprising at least two concentric electrodes.

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

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 control structure comprising at least two concentric electrodes is disposed below the second reflecting plate.

11. The Fabry-Perot interferometer of claim 7, wherein the at least two concentric electrodes include at least an inner electrode and an outermost electrode.

12. The Fabry-Perot interferometer of claim 11, wherein the variable optical gap is controllable by applying a control voltage to the inner electrode.

13. The Fabry-Perot interferometer of claim 7, wherein the electrostatic control structure is centered under the second reflecting plate.

14. The Fabry-Perot interferometer of claim 7, wherein the variable optical gap is controlled by variably pulling the second reflecting plate toward the electrostatic control structure.

15. The Fabry-Perot interferometer of claim 7, wherein the variable optical gap is controlled by moving the second reflecting plate toward the electrostatic control structure substantially without tilting the second reflecting plate.

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

17. The Fabry-Perot interferometer of claim 7, wherein the control voltage is continuously controllable by an analog signal.

18. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 17.

19. The Fabry-Perot interferometer of claim 7, wherein the control voltage is controllable by a digital signal.

20. The Fabry-Perot interferometer of claim 19, wherein the digital signal has a binary value, and wherein a binary zero sets a first optical state and a binary one sets a second optical state.

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

22. The Fabry-Perot interferometer of claim 19, wherein the digital signal has a plurality of values determined by a plurality of bits.

23. An optical interference pixel display comprising a plurality of the Fabry-Perot interferometers of claim 22.

24. The Fabry-Perot interferometer of claim 7, wherein at least one of the at least two concentric electrodes is held at a fixed electric potential, and wherein the second reflecting plate is electrically coupled to a signal source.

25. The Fabry-Perot interferometer of claim 24, wherein the first reflecting plate is held at a fixed electric potential.

26. The Fabry-Perot interferometer of claim 25, wherein the fixed electric potential is above ground.

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

28. The Fabry-Perot interferometer of claim 7, wherein the inner electrode of the at least two concentric electrodes is electrically coupled to a signal source.

29. The Fabry-Perot interferometer of claim 28, wherein the first and second reflecting plates are electrically coupled.

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

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

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

b) depositing and patterning a concentric conductive electrode structure 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.