Mirror device comprising drive electrode equipped with stopper function

• US 20090257110A1
• Filed: 09/04/2008
• Published: 10/15/2009
• Est. Priority Date: 08/14/2004
• Status: Active Grant

• Current Assignee: Ignite USA (Ignite)
• Original Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Inventors: Maeda, Yoshihiro, Ichikawa, Hirotoshi, Ishii, Fusao
• Granted Patent: US 8,115,986 B2
• Time in Patent Office: Days
• 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 27/1026 for use with reflective spatial light modulators
• CPC Class Codes: G02B 27/1033 having a single light modulator for all colour channels
• CPC Class Codes: G02B 27/146 with a tree or branched structure
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes

Abstract

The present invention provides a mirror device, comprising: a plurality of deflectable mirrors; an elastic member for deflectably supporting the mirror; a drive electrode for driving the mirror; a control circuit for giving electric charge to the drive electrode and controlling the deflecting direction of the mirror; and a substrate on which the drive electrode and the elastic member, wherein the drive electrode is placed within an area on the substrate the mirror is projected on, has an outer form constituted by sides approximately in parallel to the outer peripheral lines of the present mirror and by sides approximately parallel to the deflection axis of the present mirror, or a form obtained by dividing the aforementioned outer form into a plurality thereof, and also fills the role of a stopper for regulating the deflection angle of the mirror.

Claims

1. A mirror device, comprising:

a plurality of deflectable mirrors;

an elastic member for deflectably supporting the mirror;

a drive electrode for driving the mirror;

a control circuit for giving electric charge to the drive electrode and controlling the deflecting direction of the mirror; and

a substrate on which the drive electrode and the elastic member are formed, wherein

the drive electrode is placed within an area on the substrate the mirror is projected on,

has an outer form constituted by sides approximately in parallel to the outer peripheral lines of the present mirror and by sides approximately parallel to the deflection axis of the present mirror, or a form obtained by dividing the aforementioned outer form into a plurality thereof, and also fills the role of a stopper for regulating the deflection angle of the mirror.

2. The mirror device according to claim 1, wherein

the drive electrode is equipped with opposite surfaces which are opposite to the mirror and of which the distances from the present mirror are different.

3. The mirror device according to claim 1, wherein

the drive electrode has a plurality of surfaces in parallel to the bottom surface of the mirror.

4. The mirror device according to claim 3, wherein

the contact part of the drive electrode contacting with the mirror or a deflection member that deflects with the mirror is any of the border parts of the plurality of surfaces of the drive electrode.

5. The mirror device according to claim 1, satisfying the relationship of

d1≧

(L1*d2)/L2,

where

“

L1”

is the distance between the edge of the drive electrode on a side close to the deflection axis of the mirror and the present deflection axis,

“

L2”

is the distance between the edge of the drive electrode on a side far from the deflection axis of the mirror and the present deflection axis,

“

d1”

is the distance between the bottom surface of the mirror on the edge of the drive electrode on a side close to the deflection axis of the mirror and the drive electrode, and

“

d2”

is the distance between the bottom surface of the mirror on the edge of the drive electrode on a side far from the deflection axis of the mirror and the drive electrode.

6. The mirror device according to claim 1, wherein

the contact part of the drive electrode contacting with the mirror or a deflection member that deflects with the mirror is anywhere other than the edge of the drive electrode on a side far from the deflection axis of the present mirror.

7. The mirror device according to claim 1, wherein

the drive electrode has a form so that a contact with the mirror or a deflection member that deflects with the mirror is a point contact.

8. The mirror device according to claim 1, wherein

the drive electrode has a form so that a contact with the mirror or a deflection member that deflects with the mirror is a line contact.

9. The mirror device according to claim 1, wherein

the drive electrode has a form so that a contact with the mirror or a deflection member that deflects with the mirror is an area contact.

10. The mirror device according to claim 1, wherein

the contact part of the drive electrode contacting with the mirror or a deflection member that deflects with the mirror is a slope surface having the same slope angle as the deflection angle of the mirror.

11. The mirror device according to claim 1, wherein

there is a plurality of contact parts of the drive electrode contacting with the mirror or a deflection member that deflects with the mirror.

12. The mirror device according to claim 11, wherein

a plurality of the contact parts are individually placed apart from each other by no less than 30% of the deflection axis length of the mirror.

13. The mirror device according to claim 1, wherein

at least a part of the drive electrode including the contact part contacting with the mirror or a deflection member that deflects with the mirror is covered with an insulation member, and the dielectric strength voltage of the insulation member is no less than 2 times the drive voltage of the mirror.

14. The mirror device according to claim 13, wherein

the dielectric strength voltage of the insulation member is no less than 3 volts.

15. The mirror device according to claim 1, wherein

the mirror has an approximate square form, and

the deflection axis of the mirror is on the diagonal line thereof.

16. The mirror device according to claim 1, wherein

the pitch between the adjacent mirrors is between 4 μ

m and 10 μ

m.

17. The mirror device according to claim 1, wherein

the deflection angle of the mirror

is equal to an angle α

which is determined by an aperture ratio of a projection optical system satisfying a theoretical resolution determined by the pitch of the adjacent mirrors in a direction projecting a modulated light to a projection light path, while

the deflection angle is no less than the angle α

in a direction other than the direction projecting the modulated light to the projection light path.

18. The mirror device according to claim 1, wherein

at least a part of the drive electrode including the contact part contacting with the mirror or a deflection member that deflects with the mirror is covered with a passivation material.

19. The mirror device according to claim 1, wherein

the passivation material is a halide.

20. The mirror device according to claim 1, wherein

at least a part of the drive electrode is covered with a low reflection material.

21. The mirror device according to claim 1, wherein

at least a part of the drive electrode is covered with a film having a film thickness of ¼

of the wavelength of the visible light.

22. A projection apparatus, comprising:

a light source;

an illumination optical system for condensing the illumination light emitted from the light source and directing the light;

a mirror device array, comprising a plurality of deflectable mirror elements, for modulating the illumination light emitted from the light source; and

a projection optical system for projecting the light modulated by the mirror device array, wherein

the mirror element includes a mirror and a drive electrode for driving the mirror,

the deflection angle of the mirror is determined by the aperture ratio of the projection optical system satisfying a theoretical resolution that is determined on the basis of the pitch of the adjacent mirrors, and

the drive electrode also fills the function of a stopper for regulating the deflection angle.

23. The projection apparatus according to claim 22, wherein

the deflection angle of the mirror is between 2 degrees and 14 degrees relative to the horizontal state of the present mirror.

24. A projection apparatus, comprising:

a light source;

an illumination optical system for condensing the illumination light emitted from the light source and directing the light;

a mirror device array, comprising a plurality of deflectable mirror elements, for modulating the illumination light emitted from the light source; and

a projection optical system for projecting the light modulated by the mirror device array, wherein

the mirror element includes a mirror and a drive electrode for driving the mirror,

the deflection angle of the mirror is larger than an angle that is determined by the aperture ratio of the projection optical system satisfying a theoretical resolution that is determined on the basis of the pitch of the adjacent mirrors, and

the drive electrode also fills the role of a stopper for regulating the deflection angle.