Mirror drive device and driving method thereof

Patent metadata

Field	Value
Publication number	US-9678335-B2
Application number	US-201414330415-A
Country	US
Kind code	B2
Filing date	Jul 14, 2014
Priority date	Jul 17, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

In a mirror drive device, a first actuator section and a second actuator section are arranged on both sides of a mirror supporting section that supports a mirror section so as to sandwich the mirror supporting section. The upper electrode of a first actuator section includes a first electrode section and a second electrode section, and an upper electrode of a second actuator section includes a third electrode section and a fourth electrode section. The arrangements of the electrode sections correspond to stress distribution of principal stresses in the piezoelectric body in resonant mode vibration, and in a piezoelectric body portion that corresponds to positions of the first electrode section and the third electrode section and a piezoelectric body portion that corresponds to positions of the second electrode section and the fourth electrode section, stresses in opposite directions to each other are generated.

First claim

What is claimed is:

1. A mirror drive device comprising:
a mirror section that includes a reflective surface configured to reflect light;
a mirror supporting section that is coupled to the mirror section, the mirror supporting section configured to support the mirror section so that the mirror section rotates around a rotating axis;
a piezoelectric actuator section that is coupled to the mirror supporting section, the piezoelectric actuator section configured to generate driving force that causes the mirror section to rotate around the rotating axis; and
a fixture section configured to support the piezoelectric actuator section,
wherein the piezoelectric actuator section includes a first actuator section and a second actuator section that are deformed by an inverse piezoelectric effect obtained by applying a drive voltage,
the first actuator section and the second actuator section are piezoelectric unimorph actuators and have lamination structures in each of which a diaphragm, a lower electrode, a piezoelectric substance, and an upper electrode are laminated in this order in a lamination direction and the upper electrode is farther from the diaphragm than the piezoelectric substance in the lamination direction,
the first actuator section is arranged on one side of sides that sandwich the mirror supporting section, and the second actuator section is arranged on another side thereof,
a first base end section on an opposite side to the mirror supporting section in the first actuator section, and a second base end section on an opposite side to the mirror supporting section in the second actuator section are fixed to the fixture section,
tilting drive occurs in the mirror supporting section by bending the first actuator section and the second actuator section in opposite directions to each other,
the upper electrode of the first actuator section includes a first electrode section and a second electrode section each of which is constituted by one or plurality of electrodes, the first electrode section and the second electrode section are arranged side by side along a longitudinal direction of a shape from the first base end section of the first actuator section to a connection portion with the mirror supporting section,
the upper electrode of the second actuator section includes a third electrode section and a fourth electrode section each of which is constituted by one or plurality of electrodes, the third electrode section and the fourth electrode section are arranged side by side along a longitudinal direction of a shape from the second base end section of the second actuator section to the connection portion with the mirror supporting section,
an arrangement configuration of the first electrode section, the second electrode section, the third electrode section, and the fourth electrode section corresponds to stress distribution of principal stresses in an in-plane direction that is perpendicular to a film-thickness direction of the piezoelectric substance in a resonant mode vibration that is associated with the tilting displacement of the mirror section due to the rotation around the rotating axis,
in a piezoelectric substance portion that corresponds to positions of the first electrode section and the third electrode section, and a piezoelectric substance portion that corresponds to positions of the second electrode section and the fourth electrode section, stresses having opposite directions to each other are generated in a vibration of the resonant mode,
each of the first electrode section, the second electrode section, the third electrode section and the fourth electrode section is used as an electrode section for driving to which a driving voltage is applied, and an electrode section which is nearer to the second base end portion from among the third electrode section and the fourth electrode section in the second actuator section is divided to three electrodes, and
one electrode of the three electrodes is used as an electrode section for detecting a voltage generated by a piezoelectric effect that is associated with a deformation of the piezoelectric substance, other two electrodes of the three electrodes are used as electrodes for driving, and a drive voltage having a same phase is applied to the other two electrodes.

2. The mirror drive device according to claim 1 ,
wherein the first actuator section and the second actuator section are connected to each other, and
the mirror supporting section is coupled to a coupling section of the first actuator section and the second actuator section.

3. The mirror drive device according to claim 1 , further comprising
a first mirror supporting section and a second mirror supporting section that support the mirror section from both sides of the rotating axis in an axial direction, as the mirror supporting section.

4. The mirror drive device according to claim 1 ,
wherein the first actuator section and the second actuator section include cantilever structures in which the first base end section and the second base end section that are fixed by the fixture section are used as fixture ends.

5. The mirror drive device according to claim 1 ,
wherein the first actuator section and the second actuator section are actuator sections having a tuning-fork type shape in which two arm sections that are arranged so as to be divided on both sides of the mirror sections are provided.

6. The mirror drive device according to claim 1 , further comprising:
a drive circuit configured to supply a driving voltage to an electrode that is included in at least one of the first electrode section and the third electrode section, and supply driving voltage to an electrode that is included in at least one of the second electrode section and the fourth electrode section,
wherein a phase difference φ between the drive voltage that is applied to at least one of the first electrode section and the third electrode section and the drive voltage is applied to at least one of the second electrode section and the fourth electrode section is within a range of “130°≦φ≦230°”.

7. The mirror drive device according to claim 1 , further comprising:
a detection circuit configured to detect a voltage that is generated by a piezoelectric effect that is associated with deformation of the piezoelectric substance, from a part, which is set at a floating potential, of a plurality of electrodes that constitute the first electrode section, the second electrode section, the third electrode section, and the fourth electrode section.

8. The mirror drive device according to claim 1 , further comprising:
a drive circuit configured to supply a drive voltage to the piezoelectric actuator section, and supply a drive voltage that causes resonance driving to be performed on the mirror section near a resonant frequency fx of the resonant mode in which the mirror section performs a rotation movement around the rotating axis.

9. The mirror drive device according to claim 1 ,
wherein the piezoelectric substance that is used for the piezoelectric actuator section is a thin film that has 1 to 10 μm thickness, and is a thin film that is obtained by performing film-forming directly on a substrate that is a diaphragm.

10. The mirror drive device according to claim 1 ,
wherein the piezoelectric substance that is used for the piezoelectric actuator section is one or more kinds of perovskite-type oxides that are represented by a following formula (P)
general formula ABO 3   (P)

in the formula, “A” is an element of A-site, and at least one element including Pb,
“B” is an element of B-site, and at least one type of element selected from a group including Ti, Zr, V, Nb, Ta, Sb, Cr, Mo, W, Mn, Sc, Co, Cu, In, Sn, Ga,

Assignees

• Fujifilm Corp

Inventors

• Naono Takayuki

Classifications

• B81B3/00

  Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes (B81B5/00 takes precedence) · CPC title

• H02N2/103

  by pressing one or more vibrators against the rotor · CPC title

• H01L41/0933

  Electricity · mapped topic

• H02N2/147

  Multi-phase circuits · CPC title

• G02B26/0858 Primary

  the reflecting means being moved or deformed by piezoelectric means · CPC title