Optical scanner having piezoelectric drive

• US 5,982,528 A
• Filed: 01/20/1998
• Issued: 11/09/1999
• Est. Priority Date: 01/20/1998
• Status: Expired due to Term

• Current Assignee: Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Melville, Charles D.
• Primary Examiner(s): Phan, James
• Application Number:
  US09/009,760
• Time in Patent Office: 658 Days
• Field of Search: 359/223, 359/224, 359/213, 359/214, 359/198-199
• US Class Current: 359/224.1
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 27/01 Head-up displays

Abstract

A piezoelectric circuit drives mirror movement along a scan path. The scanner includes a support, a reflective surface and a piezoelectric circuit. The support alternately rotates about an axis of rotation in a first direction and a second direction. The reflective surface moves with the support. The piezoelectric circuit is mechanically coupled to the support, and includes a first piezoelectric volume and a second piezoelectric volume. During a first portion of a drive cycle drive signals of opposite polarity cause the volumes to deform in opposing manner. The deformation causes the support to rotate in the first direction. During a second portion of the drive cycle the polarity of the drive signals switches again causing the volumes to deform, but in opposite manner than during the first portion of the drive cycle. The deformation causes the support to rotate in the second direction.

Claims

1. An optical scanner, comprising:

a torsional support for alternately twisting in a periodic manner about an axis of rotation in a first direction and a second direction, wherein the twisting in the first direction occurs between a first extreme rotational position and a second extreme rotational position, and wherein the twisting in the second direction occurs between the second extreme rotational position and the first extreme rotational position;

a reflective surface for deflecting light, the reflective surface moving with the support, wherein the alternate rotation of the support about the axis of rotation defines an oscillatory motion of the reflective surface;

a piezoelectric circuit mechanically coupled to the support, the piezoelectric circuit comprising a first piezoelectric volume and a second piezoelectric volume, wherein during a first portion of a drive cycle the first piezoelectric volume receives a first drive signal causing the first piezoelectric volume to deform and the second piezoelectric volume receives a second drive signal causing the second piezoelectric volume to deform, the second drive signal of opposite polarity to the first drive signal causing the second piezoelectric volume to deform in a manner opposite deformation of the first piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume in response to the first drive signal and second drive signal causes the support to twist in the first direction between the first extreme rotational position and the second extreme rotational position, and wherein during a second portion of the drive cycle the polarity of the first drive signal and the second drive signal reverse again causing the first piezoelectric volume to deform and the second piezoelectric volume to deform, the first piezoelectric volume deforming in a manner opposite deformation of the second piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume during the second portion of the drive cycle causes the support to twist in the second direction between the second extreme rotational position and the first extreme rotational position.

2. The scanner of claim 1, wherein the piezoelectric circuit further comprises a frame which is attached to the support and to which are attached the first piezoelectric volume and the second piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume bends the frame, which in turn twists the support.

3. The scanner of claim 1, in which the support has a first portion and a second portion, wherein the piezoelectric circuit is a first piezoelectric circuit coupled to the first portion of the axle, and further comprising:

a second piezoelectric circuit mechanically coupled to the support, the second piezoelectric circuit comprising a third piezoelectric volume and a fourth piezoelectric volume, wherein during the first portion of the drive cycle the third piezoelectric volume receives the first drive signal causing the third piezoelectric volume to deform and the fourth piezoelectric volume receives the second drive signal causing the fourth piezoelectric volume to deform, the second drive signal of opposite polarity to the first drive signal causing the fourth piezoelectric volume to deform in a manner opposite deformation of the third piezoelectric volume, wherein the deformation of the third piezoelectric volume and the fourth piezoelectric volume in response to the first drive signal and second rive signal causes the support to twist in the first direction between the first extreme rotational position and the second extreme rotational position, and wherein during the second portion of the drive cycle the polarity of the first drive signal and the second drive signal reverse again causing the third piezoelectric volume to deform and the fourth piezoelectric volume to deform, the third piezoelectric volume deforming in a manner opposite deformation of the fourth piezoelectric volume, wherein the deformation of the third piezoelectric volume and the fourth piezoelectric volume during the second portion of the drive cycle causes the support to twist in the second direction between the second extreme rotational position and the first extreme rotational position.

4. The scanner of claim 3, in which the support comprises an elongated portion having a first end portion and a second end portion, and wherein said first portion of the support is said first end portion and said second portion of the support is the second end portion.

5. The scanner of claim 3, in which the support further comprises a first end portion adjacent to said first portion and a second end portion adjacent to said second portion, and wherein the scanner further comprises a base for supporting the first end portion and second end portion.

6. An optical scanner, comprising:

a base;

a support for alternately moving about an axis of rotation in a first direction and a second direction, wherein the movement in the first direction occurs between a first extreme position and a second extreme position, and wherein the movement in the second direction occurs between the second extreme position and the first extreme position, wherein the support comprises a first portion and a second portion;

a reflective surface for deflecting light, the reflective surface moving with the support, wherein the alternate rotation of the support about the axis of rotation defines an oscillatory motion of the reflective surface;

a first piezoelectric circuit comprising a first piezoelectric volume, a second piezoelectric volume, and a first frame, wherein the first frame is attached to the base, the first portion of the support, the first piezoelectric volume and the second piezoelectric volume, and wherein during a first portion of a drive cycle the first piezoelectric volume receives a first drive signal causing the first piezoelectric volume to deform and the second piezoelectric volume receives a second drive signal causing the second piezoelectric volume to deform, the second drive signal of opposite polarity to the first drive signal causing the second piezoelectric volume to deform in a manner opposite deformation of the first piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume in response to the first drive signal and second drive signal causes the first frame to bend, which in turn causes the support to move in the first direction between the first extreme position and the second extreme position, and wherein during a second portion of the drive cycle the polarity of the first drive signal and the second drive signal reverse again causing the first piezoelectric volume to deform and the second piezoelectric volume to deform, the first piezoelectric volume deforming in a manner opposite deformation of the second piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume during the second portion of the drive cycle causes the first frame to bend, which in turn causes the support to move in the second direction between the second extreme position and the first extreme position;

a second piezoelectric circuit comprising a third piezoelectric volume, a fourth piezoelectric volume and a second frame, wherein the second frame is attached to the base, the second portion of the support, the third piezoelectric volume and the fourth piezoelectric volume, and wherein during the first portion of the drive cycle the third piezoelectric volume receives the first drive signal causing the third piezoelectric volume to deform and the fourth piezoelectric volume receives the second drive signal causing the fourth piezoelectric volume to deform, the second drive signal of opposite polarity to the first drive signal causing the fourth piezoelectric volume to deform in a manner opposite deformation of the third piezoelectric volume, wherein the deformation of the third piezoelectric volume and the fourth piezoelectric volume in response to the first drive signal and second drive signal causes the second frame to bend, which in turn causes the support to move in the first direction between the first extreme position and the second extreme position, and wherein during the second portion of the drive cycle the polarity of the first drive signal and the second drive signal reverse again causing the third piezoelectric volume to deform and the fourth piezoelectric volume to deform, the third piezoelectric volume deforming in a manner opposite deformation of the fourth piezoelectric volume, wherein the deformation of the third piezoelectric volume and the fourth piezoelectric volume during the second portion of the drive cycle causes the second frame to bend, which in turn causes the support to move in the second direction between the second extreme position and the first extreme position.

7. The scanner of claim 6, in which the support comprises an elongated portion having a first end portion and a second end portion, and wherein said first portion of the support is said first end portion and said second portion of the support is the second end portion.

8. The scanner of claim 6, in which the support further comprises a first end portion adjacent to said first portion and a second end portion adjacent to said second portion, and wherein the base supports the first end portion and second end portion.

9. A method for driving cyclic motion of an optical scanner having a support, a reflective surface and a piezoelectric circuit, wherein the support alternately moves about an axis in a first direction and a second direction, wherein the movement in the first direction occurs between a first extreme position and a second extreme position, and wherein the movement in the second direction occurs between the second extreme position and the first extreme position, and wherein the reflective surface is for deflecting light, the reflective surface moving with the support, and wherein the alternate motion of the support about the axis defines an oscillatory motion of the reflective surface;

and wherein the piezoelectric circuit comprises a first piezoelectric volume and a second piezoelectric volume, the method comprising the steps of;

during a first portion of a first drive cycle for the scanner, inputting a first drive signal to the first piezoelectric volume and a second drive signal to the second piezoelectric volume, the first drive signal and second drive signal being of opposite polarity, the first drive signal causing the first piezoelectric volume to deform, the second drive signal causing the second piezoelectric volume to deform, the first drive signal causing the first piezoelectric volume to deform in a manner opposite deformation of the second piezoelectric volume, wherein the deformation of the first piezoelectric volume and the second piezoelectric volume in response to the first drive signal and second rive signal causes the support to move in the first direction between the first extreme position and the second extreme position; and

reversing the polarity of the first drive signal and of the second drive signal during a second portion of the first drive cycle causing the first piezoelectric volume to deform in a manner opposite deformation of the second piezoelectric volume, and in turn causing the support to move in the second direction between the second extreme position and the first extreme position; and

repeating the steps of inputting and reversing for subsequent drive cycles to generate oscillatory motion of the support in alternating first and second directions during the respective first and second portions of said subsequent drive cycles.

10. The method of claim 9, wherein the support is a torsion spring which twists in response to deformation of the first piezoelectric volume and second piezoelectric volume.

11. The method of claim 9, wherein the oscillatory motion of the reflective surface occurs at a resonant frequency.