Light modulation device and system

• US 6,433,917 B1
• Filed: 11/22/2000
• Issued: 08/13/2002
• Est. Priority Date: 11/22/2000
• Status: Active Grant

• Current Assignee: Disco Corporation
• Original Assignee: Ball Semiconductor, Inc.
• Inventors: Chan, Kin Foong, Mei, Wenhui
• Primary Examiner(s): Mack, Ricky
• Assistant Examiner(s): HINDI, OMAR Z
• Application Number:
  US09/718,619
• Time in Patent Office: 629 Days
• Field of Search: 359/291, 359/292, 359/295, 359/298, 359/290, 359/850, 359/851, 385/120, 345/84, 345/107
• US Class Current: 359/292
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 6/3516 the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70375 Multiphoton lithography or multiphoton photopolymerization; Imaging systems comprising means for converting one type of radiation into another type of radiation

Abstract

A light modulation element, device, and system is discussed. The light modulation element includes three electrodes, a flexible member, and a mirror. The flexible member is connected between the three electrodes so that the first and second electrodes are on one side and the third electrode is on the opposite side of the flexible member. The mirror is attached to the flexible member so that it can move therewith. The flexible member moves responsive to an external electrostatic force provided by one or more of the three electrodes so that the mirror is positioned in a predetermined position responsive to the state of the flexible member.

Claims

1. A light modulation element comprising:

a first, second, and third electrode;

a flexible member connected between the three electrodes so that the first and second electrodes are on one side of the flexible member and the third electrode is on the opposite side of the flexible member, wherein the flexible member is responsive to an external force provided by one or more of the three electrodes;

a mirror attached to the flexible member; and

a first gap between the flexible member and the first and second electrodes so that a portion the flexible member can move vertically between a first and second state;

wherein the mirror is vertically positioned in a predetermined position responsive to the state of the flexible member.

2. The element of claim 1 further comprising:

a second gap between the flexible member and the third electrode so that the flexible member can also move to a third state.

3. The element of claim 1 wherein the electrodes and flexible member are positioned so that when the flexible member is in the first state, the flexible member is more responsive to the third electrode than to the first or second electrode, thereby allowing the third electrode to hold the flexible member in the first state.

4. The element of claim 1 wherein the first state represents a natural, un-flexed state for the flexible member, and wherein the electrodes and flexible member are positioned so that when the flexible member is in the first state, the third electrode is closer to the flexible member than either the first or second electrodes.

5. The element of claim 1 wherein the third electrode is larger than the second electrode.

6. The element of claim 1 wherein, when the flexible member is in the first state, the third electrode can provide a stronger external force on the flexible mirror than either the first or second electrodes.

7. The element of claim 1 wherein, when the flexible member is in the second state, it is more responsive to the second electrode than the third electrode.

8. The element of claim 1 wherein, when the flexible member is in the second state, the second electrode is closer to the flexible member than the third electrode.

9. The element of claim 1 wherein, when the flexible member is in the second state, the second electrode can provide a stronger external force on the flexible mirror than the first electrode.

10. A light modulation element comprising:

a substrate;

first and second electrodes positioned adjacent to the substrate;

first and second support members connected to the substrate;

a flexible member spanning between the first and second support members and extending over and above the first and second electrodes, such that the second electrode is near a center portion of the flexible member;

a third electrode positioned above the flexible member; and

a mirror connected to and extending above the flexible member, the mirror operable to be perpendicularly displaced relative to the substrate when the flexible member is displaced.

11. The element of claim 10 further comprising:

a gap between the second and third electrodes in which the flexible member can move.

12. The element of claim 10 wherein all three electrodes include a material capable of affecting an electrostatic force and the flexible member is made of a material that is responsive to the electrostatic force.

13. The element of claim 12 wherein the first and third electrodes are electrically tied together.

14. The element of claim 13 wherein the first, second, and third electrodes are positioned so that when the first and third electrodes are affecting an electrostatic force, the flexible member is not responsive to an electrostatic force affected by the second electrode.

15. The element of claim 13 wherein the first and third electrodes are capable of producing an electrostatic force that is greater in magnitude than an electrostatic force produced by the second electrode.

16. The element of claim 13 wherein the first and third electrodes are larger than the second electrode.

17. The element of claim 13 wherein, when no electrostatic force is being affected by any electrode, the flexible member is in a free state, and wherein, when an electrostatic force is affected by the second electrode, the flexible member is in a lower state.

18. The element of claim 17 wherein, when the flexible member is in the free state, it is closer to the third electrode than either the first or second electrodes.

19. A light modulation element comprising:

a substrate;

first, second, and third electrodes connected to the substrate;

a flexible member;

means connected to the substrate for supporting the flexible member to extend over and above the three electrodes, so that a gap is formed between the flexible member and the three electrodes thereby allowing the flexible member to move between a first and second state;

a mirror extending above the flexible member; and

means for connecting the mirror to the flexible member so that the mirror stays parallel with the substrate and a distance between the substrate and the mirror is controlled by the state of the flexible member;

wherein the first and second electrodes are situated to hold the flexible member in a prior state responsive to a hold voltage applied thereto, and

wherein the third electrode is situated to selectively move the flexible member between the first and second states responsive to a data voltage applied thereto.

20. The element of claim 19 wherein, when the three electrodes are situated by being sized to produce an electrostatic force of a predetermined quantity.

21. A device comprising a substrate and an array of light modulation elements, each light modulation element comprising:

first and second electrodes positioned proximate to the substrate;

a flexible member extending over and above the first and second electrodes, such that the flexible member can move between a first and second state;

a third electrode positioned above the flexible member; and

a mirror connected to and extending above the flexible member such that a vertical distance of the mirror from the substrate is controlled by the state of the flexible member.

22. The device of claim 21 wherein each light modulation element further comprises:

a gap between the three electrodes in which the flexible member can move.

23. The device of claim 21 wherein all three electrodes of each element include a material capable of affecting an electrostatic force and the flexible member of each element is made of a material that is responsive to the electrostatic force.

24. The device of claim 21 wherein the elements are arranged in rows and columns, and wherein the second electrode of each element in a common row is electrically connected to produce a data line for the elements in that row, and wherein the first and third electrodes of each element in a common column are electrically connected to produce a hold line for the elements in that column.

25. The device of claim 21 wherein the first, second, and third electrodes of each element are situated so that, when an electrostatic force is being affected by the first and third electrodes of any particular column, a state of the flexible member is held, regardless of any electrostatic force being affected by the second electrode of any element in that column.

26. A projection system comprising:

a light source for producing a light of wavelength λ

;

a beamsplitter having a reflective surface for receiving the light and directing a first portion of the light to a micro-mirror device and a second portion of the light to a reflecting device;

the micro-mirror device comprising a plurality of individual mirrors manipulatable between a first and second state, wherein the micro-mirror device is positioned a distance (d) between a point on the reflective surface and a mirror of the micro-mirror device, when in the first state; and

the reflecting device positioned the distance (d) between the point on the reflecting device and the reflective surface;

wherein the micro-mirror device, beamsplitter, and reflecting device are positioned so that the first and second portions of light will meet after reflecting off the micro-mirror device and reflecting device, respectively; and

wherein the states of the micro-mirror device are for controlling a distance traveled by the first portion of light so that when the first and second portions of light meet, an aspect of the light can be selectively modulated.

27. The projection system of claim 26 wherein the first and second states of the individual mirrors of the micro-mirror device are separated by a distance of one-fourth fourth λ

.

28. The projection system of claim 26 wherein the micro-mirror device includes at least one electrode, such that the distance between the first and second states of the individual mirrors is controlled by a voltage level on the at least one electrode.

29. The projection system of claim 26 wherein the micro-mirror device further comprises a plurality of elements associated with each mirror, each element comprising:

first and second electrodes;

a flexible member extending over and above the first and second electrodes, such that the flexible member can move between a first and second state;

a third electrode positioned above the flexible member; and

means for connecting the corresponding mirror to the flexible member.

30. The projection system of claim 28 wherein each element further comprises:

a gap between the three electrodes in which the flexible member can move.

31. The projection system of claim 28 wherein all three electrodes of each element include a material capable of affecting an electrostatic force and the flexible member of each element is made of a material that is responsive to an electrostatic force.

32. The projection system of claim 28 wherein the elements are arranged in rows and columns, and wherein the second electrode of each element in a common row is electrically connected, and wherein the first and third electrodes of each element in a common column are all electrically connected.

33. The projection system of claim 28 wherein the first, second, and third electrodes of each element are situated so that, when an electrostatic force is being affected by the first and third electrodes of any particular column, a state of the flexible member is held, regardless of any electrostatic force being affected by the second electrode of any element in that column.

34. The projection system of claim 26 wherein the reflecting device is a second micro-mirror device;

wherein a distance traveled by the second portion of light is controllable so that when the first and second portions of light meet, two different aspects of the light can be modulated.

35. A projection system comprising:

a light source for producing a light of wavelength λ

;

means for reflecting the light

a micro-mirror device comprises a substrate and a plurality of elements connected to the substrate, with each element comprising first, second and third electrodes, a flexible member extending over and above the first and second electrodes, and a mirror connected to the flexible member so that the mirror can move between a first and second state responsive to movement of the flexible member, the mirror being connected to the flexible member so that a plane of the mirror when in the first state is parallel to the plane of the mirror when in the second state;

a beamsplitter having a reflective surface for receiving the light and directing a first portion of the light to the micro-mirror device and a second portion to the means for reflecting light,

wherein the micro-mirror device, beamsplitter, and means for reflecting light are positioned so that the first and second portions of light will meet after reflecting off the micro-mirror device and means for reflecting light, respectively.

36. The projection system of claim 35 wherein the first and second states of the individual mirrors of the micro-mirror device are separated by a distance of one-fourth fourth λ

.

37. The projection system of claim 36 wherein the distance between the first and second states of the individual mirrors is controlled by a voltage level on at least one electrode.

38. The projection system of claim 35 wherein each element of the micro-mirror device further comprises:

a gap between the three electrodes and the flexible member to allow the movement of the flexible member.

39. The projection system of claim 35 wherein all three electrodes of each element include a material capable of affecting an electrostatic force and the flexible member of each element is made of a material that is responsive to an electrostatic force.

40. The projection system of claim 35 wherein the elements are arranged in rows and columns, and wherein the second electrode of each element in a common row is electrically connected, and wherein the first and third electrodes of each element in a common column are all electrically connected.

41. The projection system of claim 35 wherein the first, second, and third electrodes of each element are situated so that, when an electrostatic force is being affected by the first and third electrodes of any particular column, a state of the flexible member is held, regardless of any electrostatic force being affected by the second electrode of any element in that column.

42. The projection system of claim 35 wherein the means for reflecting light includes means for controlling a distance traveled by the second portion of light so that when the first and second portions of light meet, two different aspects of the light can be modulated.