CN117748991A - Piezoelectric ultrasonic motor, optical member driving device, camera device, and electronic apparatus - Google Patents

Abstract

The invention provides a piezoelectric ultrasonic motor, an optical component driving device, a camera device and an electronic device, which can restrain the influence of dimensional errors of components and have stable driving force. The piezoelectric ultrasonic motor is provided with: the drive shaft (71) has magnetism, a columnar body (74) having a through hole through which the drive shaft (71) is inserted, piezoelectric elements (73 a-73 d) provided on a side surface portion of the columnar body (74) and driving the drive shaft (71) via the columnar body (74), and a magnet (80) arranged so as to face the drive shaft (71) with the columnar body (74) and the piezoelectric element (73 a) interposed therebetween.

Description

Piezoelectric ultrasonic motor, optical member driving device, camera device, and electronic apparatus

Technical Field

The present invention relates to a piezoelectric ultrasonic motor, an optical member driving device using the piezoelectric ultrasonic motor, a camera device, and an electronic apparatus.

Background

With the development of IT industry, there is an increasing demand for a very small camera module for mounting on a smart phone or the like. In the camera module, a voice coil motor and a piezoelectric ultrasonic motor can be used as a driving mechanism for optical components such as a lens body. The piezoelectric ultrasonic motor has the advantages of high response speed, reverse driving prevention function and high transmission resolution. Accordingly, piezoelectric ultrasonic motors are expected as driving units for optical components such as ultra-small camera modules.

The piezoelectric ultrasonic motor described in patent document 1 includes an output member as a drive shaft, and a pressurizing actuator and a driving actuator each including a piezoelectric element. In this piezoelectric ultrasonic motor, the output member is sandwiched between the pressurizing actuator and the driving actuator from both sides in the width direction of the output member, and each piezoelectric element of the pressurizing actuator and the driving actuator is periodically deformed by applying an alternating voltage to each piezoelectric element, so that the output member is driven in the axial direction of the output member.

Prior art literature

Patent literature

Patent document 1, japanese patent laid-open publication No. 2009-303374

Disclosure of Invention

Problems to be solved by the invention

However, the piezoelectric ultrasonic motor disclosed in patent document 1 may cause an unstable driving force applied to the output member due to a dimensional error between the pressurizing actuator and the driving actuator that sandwich the output member from both sides in the width direction of the output member.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a piezoelectric ultrasonic motor, an optical member driving device, a camera device, and an electronic apparatus, which can suppress the influence of dimensional errors of constituent members and stabilize driving force.

Means for solving the problems

In order to solve the above-described problems, a piezoelectric ultrasonic motor according to a preferred embodiment of the present invention includes: the drive shaft assembly includes a magnetic drive shaft, a columnar body having a through hole through which the drive shaft is inserted, a piezoelectric element provided on a side surface portion of the columnar body and driving the drive shaft via the columnar body, and a magnet disposed so as to face the drive shaft with the columnar body and the piezoelectric element interposed therebetween.

In this aspect, the columnar body may have a plurality of side portions, and the magnet may be disposed on one side of one of the side portions.

Further, the motor may further include a yoke provided on an outer surface of the magnet when the drive shaft is centered.

The piezoelectric element may be mounted further to the housing, FPC (Flexible Printed Circuits) may be provided to supply driving power to the piezoelectric element, the FPC may be disposed outside the piezoelectric element when the driving shaft is centered, and the magnet may be disposed outside the FPC.

Further, a buffer may be provided on the outer side of the FPC, and the magnet may be disposed on the outer side of the buffer.

Another preferred embodiment of the optical member driving device according to the present invention is characterized by comprising the piezoelectric ultrasonic motor, a fixed portion, and a movable portion on which the optical member is mounted, wherein the columnar body is coupled to one of the fixed portion and the movable portion.

In this aspect, the fixed portion may have a base to which a main guide shaft and a sub guide shaft that guide the movable portion are fixed, the drive shaft may be fixed to the base, the columnar body may be coupled to the movable portion, and the magnet may be coupled to the movable portion via the columnar body without being directly fixed to the movable portion.

A still further preferred embodiment of the camera device according to the present invention is characterized by comprising the optical member driving device.

An electronic device according to another preferred embodiment of the present invention is provided with the camera device.

ADVANTAGEOUS EFFECTS OF INVENTION

The piezoelectric ultrasonic motor of the present invention is characterized by comprising: the drive shaft assembly includes a magnetic drive shaft, a columnar body having a through hole through which the drive shaft is inserted, a piezoelectric element provided on a side surface portion of the columnar body and driving the drive shaft via the columnar body, and a magnet disposed so as to face the drive shaft with the columnar body and the piezoelectric element interposed therebetween. In this piezoelectric ultrasonic motor, the columnar body and the drive shaft are pressed against each other with a constant force by the magnet, and the frictional force acting between the columnar body and the drive shaft becomes stable. Accordingly, it is possible to provide a piezoelectric ultrasonic motor, an optical member driving device, a camera device, and an electronic apparatus, which can suppress the influence of dimensional errors of constituent members and stabilize driving force.

Drawings

Fig. 1 is a front view of a smart phone 9 equipped with a camera device 8, and the camera device 8 includes an optical member driving device 5 using a piezoelectric ultrasonic motor 100 as an embodiment of the present invention.

Fig. 2 is a perspective view of the optical member driving apparatus 5.

Fig. 3 is a perspective view of the optical component driving apparatus 5 with the housing 10 removed.

Fig. 4 is a cross-sectional view of the optical member driving device 5 of fig. 3, taken along the XY plane, in the vicinity of the piezoelectric ultrasonic motor 100.

Fig. 5 is a perspective view of the piezoelectric ultrasonic motor 100 after the magnet 80 is removed.

Fig. 6 is a perspective view of the piezoelectric ultrasonic motor 100 of fig. 5 after the buffer material 75 and the FPC72 are removed.

Detailed Description

As shown in fig. 1, a camera device 8 including an optical member driving device 5 using a piezoelectric ultrasonic motor 100 (hereinafter, simply referred to as a motor 100) as an embodiment of the present invention is housed in a housing of a smartphone 9.

The camera device 8 includes a lens body 6, an image sensor 7, and an optical member driving device 5 for driving the lens body 6 as an optical member. The image sensor 7 converts light incident via the lens body 6 into an image signal and outputs the image signal. The optical member driving device 5 drives the lens body 6 in a direction parallel to the optical axis of the lens body 6.

Hereinafter, the structure of the optical component driving device 5 will be described assuming an XYZ orthogonal coordinate system composed of a Z axis parallel to the optical axis of the lens body 6, an X axis orthogonal to each other and orthogonal to the Z axis, and a Y axis. In the following, one side of the subject as viewed from the lens body 6 is referred to as +z side, and the opposite side (image sensor 7 side) is referred to as-Z side.

As shown in fig. 2, the optical member driving device 5 accommodates a carrier 20 in a rectangular parallelepiped case 10, and the carrier 20 has a hole 20a for supporting the lens body 6. Light from the subject passes through the center of the optical member driving device 5.

As shown in fig. 3, the carrier 20 as the movable portion is disposed on the base 30 as the fixed portion. The base 30 has: a bottom surface portion 31 which is a metal plate-like member and is parallel to the XY direction; and a side surface portion 32 which is bent at right angles to the +z side at the +y side end of the bottom surface portion 31. The carrier 20 is disposed on the +z side of the bottom surface 31. The carrier 20 has a shape in which an annular portion 20b is integrated with a substantially rectangular parallelepiped connecting portion 20c, wherein the annular portion 20b is formed around a hole 20a for accommodating the lens body 6, and the substantially rectangular parallelepiped connecting portion 20c is provided so as to face the side surface portion 32 on the +y side.

In the vicinity of the side surface portion 32 of the bottom surface portion 31 of the base 30, the main guide shaft 61 and the sub guide shaft 62 are arranged in the X-axis direction as fixing portions, and the base end portions thereof are fixed to stand toward the +z side. The main guide shaft 61 and the sub guide shaft 62 are accommodated in the hole 21 and the notch 22 formed in the connecting portion 20c of the carrier 20, respectively, and guide the carrier 20 so as to be movable in the Z-axis direction.

A yoke 51 is disposed in the center of the-Y side surface of the side surface portion 32 of the base 30, and a hall ic 52 is disposed in the center of the yoke 51. A magnet 53 is disposed on an opposing surface of the carrier 20 opposing the side surface portion 32 so as to oppose the yoke 51 and the hall ic 52. The hall ic 52 detects the magnetic field of the magnet 53, thereby detecting the position of the carrier 20 in the Z-axis direction. The yoke 51 and the magnet 53 attract each other, and the carrier 20 is pulled toward the side surface portion 32. As a result, the inner wall of the hole 21 and the inner wall of the cutout portion 22 of the carrier 20 are pressed by the main guide shaft 61 and the sub guide shaft 62 with appropriate pressure, and the posture and the driving in the Z-axis direction of the carrier 20 are stabilized.

A cutout 23 is formed in the +y side end surface of the carrier 20, and the motor 100 is accommodated in the cutout 23. Although described in detail later, the motor 100 includes: the drive shaft 71, the columnar body 74, the piezoelectric elements 73a, 73b, 73c, and 73d, and in the present embodiment, further include a magnet 80. The notch 23 includes a 1 st notch 23a and a 2 nd notch 23b, wherein the 1 st notch 23a is formed by cutting an end surface on the +y side, that is, an opposing surface opposing the side surface 32, and the 2 nd notch 23b is formed by further cutting the 1 st notch 23a toward the back side. The magnet 80 is accommodated in the 2 nd cutout 23b, and a portion of the motor 100 other than the magnet 80 is accommodated in the 1 st cutout 23a. The optical component driving device 5 drives the carrier 20 in the Z-axis direction using the motor 100 according to the present embodiment as a driving source.

The drive shaft 71 has magnetism as a fixing portion, is formed of a magnetic metal, has a columnar shape, and extends in the Z-axis direction. The base end portion 71b (see fig. 5) of the drive shaft 71 on the-Z side is smaller in diameter than the drive shaft main body portion 71a, and the base end portion 71b serving as the small diameter portion is inserted into a hole (not shown) formed in the bottom surface portion 31, is fixed by a method such as caulking or welding, and stands toward the +z side. The main guide shaft 61 and the sub guide shaft 62 are also configured in the same manner and fixed in the same manner.

As shown in fig. 5 and 6, the motor 100 has a non-magnetic metal column 74 as a movable portion. In the present embodiment, the columnar body 74 is a quadrangular prism having 2 bottom surface portions 74e and 74f and 4 side surface portions 74a, 74b, 74c, and 74d that face each other. The columnar body 74 has through holes 74g penetrating between 2 bottom surface portions 74e and 74 f. The drive shaft 71 is inserted into the through hole 74g of the columnar body 74. The diameter of the drive shaft 71 is slightly smaller than the diameter of the through hole 74g.

The FPC72 (Flexible Printed Circuits) has a mounting portion to which a plurality of (4 in the example of fig. 5) sheet-like piezoelectric elements 73a, 73b, 73c, and 73d are mounted, and a lead portion 72a that leads from the mounting portion to the outside of the motor 100. The mounting portion of the FPC72 is wound around the columnar body 74 from the outside of the piezoelectric elements 73a, 73b, 73c, and 73d so that the respective piezoelectric elements 73a, 73b, 73c, and 73d are in contact with the corresponding side portions 74a, 74b, 74c, and 74d of the columnar body 74. The lead portion 72a is led out in a direction parallel to the drive shaft 71, bent 180 degrees, and arranged on the-Y side surface of the side surface portion 32.

The piezoelectric elements 73a, 73b, 73c, and 73d have electrodes 73e formed on +z sides of the surfaces facing the FPC72, and electrodes 73f formed on-Z sides so as to be isolated from the electrodes 73 e. The electrodes 73e and 73f are electrically connected to the FPC72, respectively.

The piezoelectric elements 73a, 73b, 73c, and 73d are also formed with electrodes on the surfaces of the columnar bodies 74 facing the columnar bodies 74 on the opposite sides of the surfaces on which the electrodes 73e and 73f are formed, and the electrodes are electrically connected to the columnar bodies 74. The FPC72 has a common terminal portion 72b, and the common terminal portion 72b is electrically connected to the bottom surface portion 74e of the pillar 74.

The FPC72 supplies driving power to the piezoelectric elements 73a, 73b, 73c, and 73 d. As a result, the piezoelectric elements 73a, 73b, 73c, and 73d deform, respectively, and drive the drive shaft 71 in the axial direction (Z-axis direction) via the columnar body 74.

The mounting portion of the FPC72 is wound around the columnar body 74 in the order of the side portions 74c, 74b, 74a, 74d from the side of the lead portion 72a. The FPC72 has a rounded portion (R portion) 72R at each position facing each corner portion between the 4 side portions 74a, 74b, 74c, and 74d except for the corner portion between the side portion 74c and the side portion 74 d. The width of the rounded portion (R portion) 72R in the Z direction is the same as the width of the adjacent portion. Further, the outer surface of FPC72 wound around columnar body 74 is covered with buffer material 75. As the cushioning material 75, felt is used in the present embodiment. The motor 100 covered with the buffer material 75 is fixed to the +x side and the inner wall surface of the-X side of the 1 st cutout 23a of the carrier 20 and the +y side surface of the magnet 80. Thereby, the columnar body 74 is coupled to the carrier 20 as the movable portion.

In the present embodiment, the magnet 80 is housed in the 2 nd cutout 23b such that the yoke 81 is provided on the-Y side surface. The +y side surface of the magnet 80 to which the yoke 81 is fixed to the buffer material 75. In the present embodiment, the magnet 80 is not directly fixed to the carrier 20, but is coupled to the carrier 20 via the columnar body 74. The magnet 80 is magnetized in the Y-axis direction. The magnet 80 is disposed on one side of the one side surface portion 74a of the columnar body 74, and is disposed so as to face the drive shaft 71 with the columnar body 74 and the one piezoelectric element 73a interposed therebetween. Thereby, the magnet 80 and the drive shaft 71 as a magnetic body are pulled toward each other, and thereby the side surface on the +y side of the drive shaft 71 and the inner wall surface on the-Y side of the through hole 74g of the columnar body 74 are pressed against each other in the Y direction. When the drive shaft 71 is centered, the FPC72 is disposed outside the piezoelectric element 73a, the buffer material 75 is disposed outside the FPC72, and the magnet 80 is disposed outside the FPC72 and the buffer material 75. The arrangement from the drive shaft 71 to the buffer material 75 is the same as the arrangement of 3 faces where the magnets 80 are not arranged, so that the magnets 80 do not adversely affect the structure of the motor 100 other than the magnets 80.

In the above configuration, the same frequency, the same phase, and the same height voltage are applied to the electrodes 73e of the piezoelectric elements 73a, 73b, 73c, and 73d, and the same frequency, 90 degrees out of phase, and the same height voltage with respect to the voltage applied to the electrodes 73e are applied to the electrodes 73f. Thus, the piezoelectric elements 73a, 73b, 73c, and 73d at positions corresponding to the electrodes 73e and 73f expand and contract in the plate surface direction. Since the columnar body 74 does not expand and contract as described above, the entire portion up to the piezoelectric elements 73a, 73b, 73c, and 73d corresponding to the electrodes 73e and 73f and the through-hole 74g of the columnar body 74 is repeatedly deformed in a bowl shape and in an inverted shape. That is, the entire inner wall surface of the through hole 74g is repeatedly deformed in the bowl shape and the inverted shape. Thus, the piezoelectric elements 73a, 73b, 73c, and 73d and the columnar body 74 constitute a vibrator. Since the voltage applied to the electrode 73e and the voltage applied to the electrode 73f have a phase difference of 90 degrees, the deformation of the inner wall surface of the through hole 74g at the position corresponding to the electrode 73e and the deformation of the inner wall surface of the through hole 74g at the position corresponding to the electrode 73f also have a phase difference of 90 degrees. Accordingly, the inner wall surface of the through hole 74g moves in an elliptical manner along the axial direction of the through hole 74g, and the columnar body 74 and the drive shaft 71 move relatively in the +z direction or the-Z direction along the drive shaft 71. The direction of the relative movement of the columnar body 74 and the drive shaft 71 can be controlled by changing the phase difference of the applied voltage.

In the present embodiment, as described above, the drive shaft 71 is fixed to the base 30, and the carrier 20 is fixed to the columnar body 74. Therefore, according to the present embodiment, the carrier 20 can be moved in the Z-axis direction with respect to the base 30 by supplying driving power from the FPC72 to the piezoelectric elements 73a, 73b, 73c, and 73 d.

In the present embodiment, the frictional force acting between the columnar body 74 and the drive shaft 71 has a large influence on the driving of the drive shaft 71. In the present embodiment, the columnar body 74 and the drive shaft 71 are pressed against each other with a constant force by the magnet 80, and the frictional force acting between the columnar body 74 and the drive shaft 71 becomes stable. Therefore, according to the present embodiment, the influence of the dimensional error of the constituent members can be suppressed, and the driving of the drive shaft 71 can be stabilized.

In fig. 3, the magnet 80 of the motor 100 is disposed in the 2 nd notch 23b of the notch 23, but the magnet 80 may be disposed in the 2 nd notch 23b disposed on the-X side (+x side) of the 1 st notch 23a by rotating the motor 100 by 90 degrees in the clockwise direction (counterclockwise direction) together with the notch 23. In addition, the motor 100 may be rotated 180 degrees together with the notch 23. If the size allows, the motor 100 rotated by 90 degrees may be disposed between the hole 21 and the slit 22. In this case, it is preferable that the yoke 81 is not provided, and the magnet 80 can be used as the magnet 53 without providing the magnet 53. Therefore, the magnet 80 presses the drive shaft 71 and the columnar body 74 against each other, presses the main guide shaft 61 against the hole 21 of the coupling portion 20c of the carrier 20, and presses the sub guide shaft 62 against the cutout portion 22, so that the drive of the drive shaft 71 can be stabilized.

The columnar body 74 is formed as a quadrangular prism having 4 side portions, but is not limited thereto, and may be a triangular prism, a hexagonal prism, or the like, and may be a cylinder as long as mounting of a piezoelectric element or the like is possible. In the present embodiment, the piezoelectric ultrasonic motor 100 is configured to fix the drive shaft 71 and move the columnar body 74, but may be configured to fix the columnar body 74 and move the drive shaft 71. The cushion material 75 is not necessarily a felt, and may be a material that can hold the piezoelectric ultrasonic motor 100 and does not block the vibration of the vibrator, for example, silicone rubber or the like may be used.

The piezoelectric ultrasonic motor 100 may be further provided with a frame outside the cushioning material 75, and may be integrally formed as a single unit. In this case, the magnet 80 may be disposed inside the frame or outside the frame.

In the present embodiment, the magnet 80 is not directly fixed to the carrier 20, because the posture and the Y-direction position of the carrier 20 are determined by the main guide shaft 61, the sub guide shaft 62, the magnet 53, and the yoke 51, and the position of the drive shaft 71 is fixed, the effect due to the magnetic attraction force between the magnet 80 and the drive shaft 71 cannot be exhibited well when the magnet 80 is fixed to the carrier 20. Therefore, the magnet 80 may be directly fixed to the movable portion or the fixed portion, unless a mechanism for determining the posture and position of the movable portion at a position other than the piezoelectric ultrasonic motor 100 is used. For example, there is an optical member driving device that drives an aperture blade that adjusts the amount of light incident on a lens as an optical member. In this case, the driving pin provided to the driving shaft 71 is inserted into the guide hole provided to the diaphragm blade, and the driving shaft 71 is driven to linearly advance, thereby moving the diaphragm blade. In this case, even if the magnet 80 is directly fixed to the fixing portion, the drive shaft 71 is attracted to and driven by the magnet 80, and thus no problem occurs.

Symbol description:

5 … optical component drive means; 6 … lens body; 7 … image sensor; 8 … camera device; 9 … smart phone; 10 … shell; 20 … vector; 20a, 21 … wells; 20b … loop; 20c … connection; 22. 23 … cut-out portions; 30 … base; 31 … bottom portion; 32 … side portions; 51 … yoke; 52 … hall ics; 53 … magnets; 61 … main guide shaft; 62 … secondary guide shafts; 71 … drive shaft; 71a … drive shaft body portion; 71b … base end portion; 72 … FPC;72a … lead-out portion; 72b … common terminal portions; 72R … rounded (R); 73a, 73b, 73c, 73d … piezoelectric elements; 73e, 73f … electrodes; 74 … columns; 74a, 74b, 74c, 74d … side portions; 74e, 74f … bottom portions; 74g … through holes; 75 … buffer material; 80 … magnets; 81 … yoke; 100 … piezoelectric ultrasonic motor (motor).

Claims (9)

1. A piezoelectric ultrasonic motor is characterized by comprising:

a magnetic driving shaft,

A columnar body having a through hole through which the drive shaft is inserted,

Piezoelectric element provided on side surface portion of the columnar body and driving the drive shaft via the columnar body, and

and a magnet disposed to face the drive shaft so as to sandwich the columnar body and the piezoelectric element.

2. The piezoelectric ultrasonic motor according to claim 1, wherein,

the columnar body has a plurality of side portions, and the magnet is disposed on one side of one of the side portions.

3. The piezoelectric ultrasonic motor according to claim 1, wherein,

the motor further includes a yoke provided on an outer surface of the magnet when the drive shaft is centered.

4. The piezoelectric ultrasonic motor according to claim 1, wherein,

further comprises a piezoelectric element FPC (Flexible Printed Circuits) for mounting the piezoelectric element and supplying drive power to the piezoelectric element,

when the drive shaft is centered, the FPC is disposed outside the piezoelectric element, and the magnet is disposed outside the FPC.

5. The piezoelectric ultrasonic motor according to claim 4, wherein,

the FPC has a buffer material on an outer side thereof, and the magnet is disposed on an outer side of the buffer material.

6. An optical component driving apparatus, characterized in that,

a piezoelectric ultrasonic motor, according to claim 1, comprising a fixed part and a movable part for mounting an optical component,

the columnar body is coupled to one of the fixed portion and the movable portion.

7. The optical component driving apparatus according to claim 6, wherein,

the fixed portion has a base to which a main guide shaft and a sub guide shaft that guide the movable portion are fixed, the drive shaft is fixed to the base, the columnar body is coupled to the movable portion, and the magnet is coupled to the movable portion via the columnar body without being directly fixed to the movable portion.

8. A camera apparatus, characterized in that,

an optical component driving apparatus according to claim 6.

9. An electronic device, characterized in that,

the camera device according to claim 8.