Torsionally hinged devices with support anchors

• US 20040004749A1
• Filed: 01/02/2003
• Published: 01/08/2004
• Est. Priority Date: 07/08/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Turner, Arthur Monroe, Orcutt, John W.
• Granted Patent: US 6,900,918 B2
• Time in Patent Office: Days
• US Class Current: 359/224
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129

Abstract

A functional surface, such as a reflective surface, is supported by a pair of torsional hinges for pivoting about a first axis which in turn is supported by a pair of anchors, according to one embodiment. The reflective surface may be driven into resonant oscillations about the first axis by inertially coupling energy to the device. According to a dual axis embodiment, the reflective surface is attached by torsional hinges to a gimbals portion which in turn is attached to the support members by a second pair of torsional hinges which are orthogonal with the first pair of hinges so as to provide for pivoting of the surface about both pairs of torsional hinges. Thus, a light source may be reflected from a reflective surface to produce a beam sweep and moved orthogonally by the gimbals portion. The devices may be etched from silicon.

Claims

1. A device integrally formed from a single piece of material and adapted for mounting to a support structure comprising:

a pair of support anchors, said pair of support anchors being the only portions of said device adapted for mounting said device to said support structure;

a functional surface portion for pivoting about a first axis and located between said pair of anchors; and

a first pair of torsional hinges, each hinge of said pair having a first end terminating at one of said pair of support anchors adapted for mounting and a second end of each hinge for supporting said functional surface portion.

2. The device of claim 1 wherein said first pair of torsional hinges lie along said first axis for pivoting and said second end of each one of said first pair of torsional hinges terminating at said functional surface portion.

3. The device of claim 1 further comprising a gimbals portion and a second pair of torsional hinges lying along said first axis, each hinge of said second pair of torsional hinges having a first end terminating at said gimbals portion and a second end terminating at said functional surface portion, and wherein said second end of each hinge of said first pair of torsional hinges terminates at said gimbals portion and said first pair of torsional hinges located at substantially a right angle with said first pair of torsional hinges such that said gimbals portion pivots about a second axis orthogonal to said first axis.

4. The device of claim 1 and further comprising a driver circuit for pivoting said functional surface portion about said first axis.

5. The device of claim 4 having a resonant frequency at which said functional surface portion pivotally oscillates about said first axis and wherein said driver circuit generates vibrational energy in at least one anchor of said pair of support anchors such that said vibrational energy is inertially coupled through at least one of said pair of torsional hinges to said functional surface portion to generate said pivotal oscillations at substantially said resonant frequency.

6. The device of claim 5 wherein said driver circuit comprises at least one electrostatic plate spaced a selected distance from at least a portion of one of said pair of support anchors and an alternating voltage source having a frequency substantially at said resonant frequency connected between said at least one electrostatic plate and one of said pair of support anchors.

7. The device of claim 5 wherein said driver circuit comprises at least one portion of piezoelectric material having a first end and a second end, said piezoelectric material bonded to one of said pair of support anchors and an alternating voltage source having a frequency substantially at said resonant frequency connected between said first end and said second end.

8. The device of claim 5 wherein said driver circuit comprises at least one electromagnetic coil located to electromagnetically interact and pivot said functional surface portion and an alternating voltage source having a frequency substantially at said resonant frequency connected to said at least one coil.

9. The integrally formed device of claim 5 wherein said functional surface portion is a reflective surface portion.

10. The integrally formed device of claim 4 wherein said driver circuit comprises at least one electromagnetic coil located to magnetically interact and pivot about said functional surface and further comprises a voltage source connected across said at least one coil for moving said functional surface portion to a selected pivot position.

11. The integrally formed device of claim 10 wherein said functional surface portion is a reflective surface portion.

12. The integrally formed device of claim 10 wherein said functional surface portion is adapted to receive a source of light directed onto said functional surface portion and wherein said functional surface portion is a fresnel lens for focusing said source of light and positioning said focused light onto a particular target.

13. The integrally formed device of claim 10 wherein said functional surface portion is adapated to recieve a source of light having a multiplicity of frequencies directed onto said functional surface portion, and wherein said functional surface portion is a light gradient for separating selected ones of said frequencies and positioning at least one of said selected light frequency onto a particular target.

14. The integrally formed device of claim 1 further comprising at least one reinforcing member extending between said pair of support anchors.

15. The integrally formed device of claim 1 wherein said single piece of material containing silicon.

16. The integrally formed device of claim 1 wherein said single piece of material is single crystal silicon.

17. A mirror device for providing bi-directional beam movement, comprising:

a reflective surface portion positioned to intercept a beam of light from a light source, said reflective surface pivotally attached to a gimbals portion by a first pair of torsional hinges, and said gimbals portion supported by a second pair of torsional hinges extending to first and second support anchors such that pivoting of said device about said first pair of torsional hinges results in a light beam reflected from said reflective surface moving along a first path and pivoting of said device about said second pair of torsional hinges results in said reflective light moving in a direction substantially orthogonal to said first path;

a first driver for generating vibrational energy in at least one of said first and second support anchors and wherein said vibrational energy is inertially coupled through said second pair of torsional hinges to said gimbals portion and from said gimbals portion through said first pair of torsional hinges to said reflective surface portion for causing resonant pivoting in one direction about said first pair of said torsional hinges and then the opposite direction such that said reflected light beam sweeps or traces across a target area having a first dimension and a second dimension that is orthogonal to said first dimension, said reflected light beam sweeping along said first dimension of said target area as said mirror device pivots about said first pair of torsional hinges; and

a second driver for pivoting said mirror device about said second pair of torsional hinges such that consecutive beam sweeps across said target are repositioned substantially orthogonal with respect to said beam sweep.

18. The mirror device of claim 17 wherein said target area is a rotating cylindrical shaped photosensitive medium.

19. The mirror device of claim 17 wherein said target area is a display screen.

20. A printer comprising:

a light source providing a beam of light;

a first mirror device comprising a reflective surface portion positioned to intercept said beam of light, a first pair of torsional hinges attached to said reflective surface portion and extending to first and second support anchors for resonant pivoting about a first axis such that light reflected from said reflective surface sweeps along a first path, said first and second support anchors defining a pivotal axis extending through sad reflective surface portion for supporting said mirror device;

a first drive circuit for generating vibrational energy in at least one of said first and second support anchors, said vibrational energy inertially coupled through said first pair of torsional hinges to said reflective surface portion to cause resonant pivoting of said first device about said first axis to provide a resonant beam sweep;

a second mirror device for rotating about a second axis and positioned such that light from said reflective surface moves in a second direction substantially orthogonal to said first path;

a moving photosensitive medium having a first dimension and a second dimension orthogonal to said first dimension, and located to receive an image of said reflected light beam as said beam sweeps across said photosensitive medium along said first dimension, said photosensitive medium moving in a direction along said second dimension such that subsequent traces are spaced apart; and

a second drive circuit for rotating said second mirror device about said second axis such that light traces are received on said moving photosensitive medium along a line substantially orthogonal to the movement of said photosensitive medium.

21. A printer comprising:

a light source providing a beam of light;

a mirror device comprising a reflective surface portion positioned to intercept said beam of light from said light source, said reflective surface supported by a first pair of torsional hinges for pivoting about a first axis and supported by a second pair of torsional hinges extending one each to first and second support anchors for pivoting about a second axis substantially orthogonal to said first axis such that pivoting of said device about said first axis results in light reflected from said reflective surface defining a first path, and pivoting of said device about said second axis results in said reflective light moving in a second direction substantially orthogonal to said first path;

a first driver for generating vibrational energy inertially coupled through said second pair of torsional hinges and through said first pair of torsional hinges to said reflective surface portion to cause resonant pivoting of said reflective surface in one direction about said first axis and then the opposite direction;

a moving photosensitive medium having a first dimension and a second dimension orthogonal to said first dimension, and located to receive an image of said reflected light beam as it sweeps or traces across said medium along said first dimension as said mirror device is resonantly pivoting about said first axis, said photosensitive medium moving in a direction along said second dimension such that an image of a subsequent trace of light is spaced from a previous trace; and

a second driver for pivoting about said second axis such that traces are received on said moving photosensitive medium along a line substantially orthogonal to the movement of said photosensitive medium.

22. A display device comprising:

a light source providing a beam of light;

a first mirror device comprising a reflective surface portion positioned to intercept said beam of light, a first pair of torsional hinges attached to said reflective surface portion and extending to first and second support anchors for resonant pivoting about a first axis such that light reflected from said reflective surface sweeps along a first path, said first and second support anchors defining a pivotal axis extending through said reflective surface portion for supporting said mirror device;

a first drive circuit for generating vibrational energy in at least one of said first and second support anchors, said vibrational energy inertially coupled through said first pair of torsional hinges to said reflective surface portion to cause resonant pivoting of said first device about said first axis to provide a resonant beam sweep;

a second mirror device for rotating about a second axis such that light from said reflective surface moves in a second direction substantially orthogonal to said first plane;

a display screen having a first dimension and a second dimension orthogonal to said first dimension, and located to receive a multiplicity of modulated image lines of said reflected light beam as said beam sweeps across said display screen along said first dimension, each image line of said multiplicity being equally spaced from the preceding image line in a direction along said second dimension to generate an image frame; and

a second drive circuit for rotating said second mirror device about said second axis such that said multiplicity of image lines are spaced across said display screen along a line substantially orthogonal to said resonant beam sweep.

23. A display device comprising:

a light source providing a beam of light;

a mirror device comprising a reflective surface portion positioned to intercept said beam of light from said light source, said reflective surface supported by a first pair of torsional hinges for pivoting about a first axis and supported by a second pair of torsional hinges extending one each to first and second support anchors for pivoting about a second axis substantially orthogonal to said first axis such that pivoting of said device about said first axis results in light reflected from said reflective surface defining a first path, and pivoting of said device about said second axis results in said reflective light moving in a second direction substantially orthogonal to said first path;

a first driver for generating vibrational energy inertially coupled through said second pair of torsional hinges and through said first pair of torsional hinges to said reflective surface portion to cause resonant pivoting of said reflective surface in one direction about said first axis and then the opposite direction;

a display screen having a first dimension and a second dimension orthogonal to said first dimension, and located to receive a multiplicity of modulated image lines of said reflected light beam as it sweeps or traces across said display screen along said first dimension as said mirror device is pivoting substantially at its resonant frequency about said first axis, each image line of said multiplicity being equally spaced from the preceding image line in a direction along said second dimension to generate an image frame; and

a second driver for pivoting about said second axis such that said multiplicity of image lines are spaced across said display screen along a line substantially orthogonal to said resonant beam sweep.

24. A multiplicity of integrally formed devices defined on a wafer, each of said multiplicity of devices adapted for mounting to a support structure and each devise comprising:

a pair of support anchors, said pair of support anchors being the only portions of said device adapted for mounting said device to said support structure;

a functional surface portion for pivoting about a first axis and located between said pair of anchors; and

a first pair of torsional hinges, each hinge of said pair having a first end terminating at one of said pair of support anchors adapted for mounting and a second end of each hinge for supporting said functional surface portion.

25. The multiplicity of integrally formed devices of claim 24 wherein said first pair of torsional hinges of each device of said multiplicity lie along said first axis for pivoting, and said second end of each one of said first pair of torsional hinges terminating at said functional surface portion.

26. The multiplicity of integrally formed devices of claim 24 wherein each device of said multiplicity further comprises a gimbals portion and a second pair of torsional hinges lying along said first axis, each hinge of said second pair of torsional hinges having a first end terminating at said gimbals portion and a second end terminating at said functional surface portion, and wherein said second end of each hinge of said first pair of torsional hinges terminates at said gimbals portion and said first pair of torsional hinges located at substantially a right angle with said second pair of torsional hinges such that said gimbals portion pivots about a second axis orthogonal to said first axis.

27. The multiplicity of integrally formed devices of claim 25 wherein each of said devices have a resonant frequency at which said functional surface portion pivots about said first pair of torsional hinges.

28. The multiplicity of integrally formed devices of claim 26 wherein each of said devices have a resonant frequency at which said functional surface portion pivots about said first pair of torsional hinges.

29. The multiplicity of integrally formed devices of claim 24 wherein said wafer is a single crystal silicon wafer.

30. The multiplicity of integrally formed devices of claim 24 wherein said wafer contains silicon.

31. The multiplicity of integrally formed devices of claim 24 wherein at least one of said multiplicity of devices further comprising at least one reinforcing member extending between said pair of support anchors.