CN113709327A

CN113709327A - Piezoelectric actuator and camera module thereof

Info

Publication number: CN113709327A
Application number: CN202010429088.4A
Authority: CN
Inventors: 杨伟成; 杨鑫; 顾自明
Original assignee: Galaxycore Shanghai Ltd Corp
Current assignee: Galaxycore Shanghai Ltd Corp
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2021-11-26

Abstract

The invention provides a piezoelectric actuator and a camera module thereof.A driving rod is arranged between two piezoelectric elements, and a connecting structure positioned at the top is connected with the piezoelectric elements and the driving rod, so that the height of the piezoelectric actuator is reduced, the driving capability is improved, the driving stroke is increased under the same module height, and the module height is reduced under the same driving stroke, thereby meeting the product requirements of larger driving stroke and lower module height, improving the imaging quality, and realizing larger single-step stroke of the piezoelectric actuator and higher focusing efficiency under the same driving signal, thereby improving the overall performance of the camera module.

Description

Piezoelectric actuator and camera module thereof

Technical Field

The invention relates to a piezoelectric actuator and a camera module thereof.

Background

An existing camera module generally includes a lens assembly and an actuator for driving the lens assembly to move in an optical axis direction. With the rapid development of the portable electronic equipment industry, the requirements of people on the imaging effect of the camera module are gradually improved, the shooting quality is improved mainly by increasing the optical sizes of a lens and an image sensor at present, the increase of the lens also forms a challenge to the driving capability of an actuator, the movable stroke of the existing voice coil actuator and the memory alloy actuator is short, the effect of macro-shooting is poor, on the other hand, the lens of the existing camera module cannot perform telescopic motion at a large distance outside a mobile phone, and in order to meet the requirements, the piezoelectric actuator is a great trend of the industry development.

However, the conventional piezoelectric actuator generally includes a piezoelectric element and a driving rod disposed above the piezoelectric element, the piezoelectric element drives the driving rod to reciprocate up and down at high frequency during high-frequency vibration, and the height of the piezoelectric element and the height of the driving rod determine the driving capability and the driving stroke, so that if a large stroke is to be realized, the height of the piezoelectric actuator is difficult to further reduce, the height of the piezoelectric actuator is limited by the overall height of the portable electronic device, and the product requirements of a large driving stroke and a low module height are difficult to be considered.

Disclosure of Invention

The invention aims to provide a piezoelectric actuator and a camera module thereof, which can reduce the height of the piezoelectric actuator, improve the driving capability, meet the product requirements of larger driving stroke and lower module height, improve the imaging quality and improve the overall performance of the camera module.

In view of the above, the present invention provides a piezoelectric actuator including: two piezoelectric elements; a drive rod located between the two piezoelectric elements; a connecting structure for connecting the piezoelectric element and the driving rod; wherein the connecting structure is a rigid plate; the connecting structure is located on top of the piezoelectric element and the drive rod.

The invention also provides a camera module, which comprises the piezoelectric actuator with the technical characteristics, wherein the piezoelectric actuator is used for driving the lens component to move along the optical axis direction.

Preferably, the other side opposite to the two piezoelectric elements is provided with an elastic supporting structure, and the elastic supporting structure is abutted against the lens assembly through a ball so as to ensure the stability of the optical axis of the lens assembly.

Preferably, the elastic buckle fixedly connected with the lens component is in friction contact with the driving rod to drive the lens component to move along the optical axis direction.

Preferably, a position detection element provided in correspondence with the piezoelectric actuator is used to feed back position information of a corresponding portion of the lens assembly.

Preferably, the position detection element is a hall sensor or a capacitive grating sensor.

According to the piezoelectric actuator and the camera module thereof, the driving rod is arranged between the two piezoelectric elements, the connecting structure positioned at the top is connected with the piezoelectric elements and the driving rod, so that the height of the piezoelectric actuator is reduced, the driving capability is improved, the driving stroke is increased under the same module height, the module height is reduced under the same driving stroke, the product requirements of larger driving stroke and lower module height are met, the imaging quality is improved, and under the same driving signal, the piezoelectric actuator can have larger stroke and higher focusing efficiency, so that the overall performance of the single-step camera module is improved.

Drawings

Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments thereof, which proceeds with reference to the accompanying drawings.

Fig. 1 and 2 are schematic structural views of the camera module according to the present invention.

In the drawings, like or similar reference numbers indicate like or similar devices (modules) or steps throughout the different views.

Detailed Description

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof. The accompanying drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. The illustrated embodiments are not intended to be exhaustive of all embodiments according to the invention. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

The present invention will be described in detail with reference to specific examples.

As shown in fig. 1 and 2, the camera module of the present invention includes a lens assembly 1 and a piezoelectric actuator 2 for driving the lens assembly 1 to move in an optical axis direction. The piezoelectric actuator 2 includes two piezoelectric elements 21; a drive rod 22 located between the two piezoelectric elements 21; a connecting structure 23 for connecting the piezoelectric element 21 with the drive rod 22. Wherein the connecting structure 23 is a rigid plate; the connecting structure 23 is located on top of the piezoelectric element 21 and the drive rod 22.

Compared with the piezoelectric actuator in the prior art, the driving rod 22 is shifted from above the piezoelectric element 21 to between two piezoelectric elements 21, so that the overall height of the piezoelectric actuator 2 is effectively reduced, and therefore, a larger space is available for increasing the height of the piezoelectric element 21 or the driving rod 22, thereby improving the driving capability of the piezoelectric actuator 2. Therefore, the driving stroke can be increased under the same module height, the module height can be effectively reduced under the same driving stroke, the product requirements of a larger driving stroke and a lower module height are considered, the imaging quality is improved, the single-step stroke of the piezoelectric actuator is larger under the same driving signal due to the improvement of the driving capability, the focusing efficiency is higher, and the overall performance of the camera module is improved.

Specifically, the shape of the driving rod 22 can be set as required, which is illustrated as a cylinder as an example and not as a limitation, the piezoelectric elements 21 on both sides can transfer the vibration to the driving rod 22 in the middle through the rigid connection structure 23 on the top when vibrating at high frequency, so as to carry the driving rod 22 to reciprocate up and down with high frequency, the driving rod 22 is in friction contact with an elastic buckle 4 in the tangential direction, the other end of the elastic buckle 4 is fixedly connected with the lens assembly 1, and the driving rod 22 and the elastic buckle 4 can provide the lens assembly 1 with a driving force moving along the optical axis under the action of friction and inertia, so that the lens assembly 1 can move up and down smoothly in the optical axis direction.

In the preferred embodiment shown in fig. 1 and 2, a piezoelectric actuator 2 is disposed on one side of the lens assembly 1, and an elastic support structure, here shown as a flat spring plate 6, is disposed on the other side of the lens assembly 1 opposite to two piezoelectric elements 21 of the piezoelectric actuator 2, two balls 5 are disposed between the flat spring plate 6 and the lens assembly 1, the two balls 5 are respectively located at two ends of the flat spring plate 6, and the flat spring plate 6 abuts against the lens assembly 1 through the balls 5, so as to apply elastic pressure to the lens assembly 1. On the one hand, this ensures that the center of gravity of the lens assembly 1 moves along a fixed axis in the direction of the optical axis, thereby ensuring the stability of the optical axis of the lens assembly 1; on the other hand, the elastic pressure on the opposite side can ensure that the driving rod 22 and the elastic buckle 4 are better contacted in the normal direction, thereby providing effective friction force for the driving rod and the elastic buckle.

In other preferred embodiments, not shown, the other side of the lens assembly 1 can also be provided symmetrically with the same piezoelectric actuator 2, in which case the elastic support structure 6 and the ball 5 need not be provided.

Furthermore, a position detection element 3 (e.g., a hall sensor or a capacitive sensor) may also be provided at a position corresponding to the piezoelectric actuator 2, here shown between the two piezoelectric elements 21, the position detection element 3 being used to feed back position information of a corresponding portion of the lens assembly 1 to the piezoelectric actuator 2 to determine the movement distance of the lens assembly 1.

In summary, according to the piezoelectric actuator and the camera module thereof provided by the invention, the driving rod is arranged between the two piezoelectric elements, and the connecting structure at the top is connected with the piezoelectric elements and the driving rod, so that the height of the piezoelectric actuator is reduced, the driving capability is improved, the driving stroke is increased under the same module height, and the module height is reduced under the same driving stroke, so that the product requirements of larger driving stroke and lower module height are met, the imaging quality is improved, and under the same driving signal, the single-step stroke of the piezoelectric actuator is larger, the focusing efficiency is higher, and the overall performance of the camera module is improved.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Furthermore, it will be obvious that the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. Several elements recited in the apparatus claims may also be implemented by one element. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A piezoelectric actuator, comprising:

two piezoelectric elements;

a drive rod located between the two piezoelectric elements;

a connecting structure for connecting the piezoelectric element and the driving rod;

wherein the connecting structure is a rigid plate; the connecting structure is located on top of the piezoelectric element and the drive rod.

2. A camera module, comprising a piezoelectric actuator as claimed in claim 1 for driving the lens assembly in the direction of the optical axis.

3. The camera module according to claim 2, wherein an elastic support structure is disposed on the other side opposite to the two piezoelectric elements, and the elastic support structure abuts against the lens assembly through a ball to ensure stability of an optical axis of the lens assembly.

4. The camera module of claim 2, wherein the resilient latch fixedly coupled to the lens assembly frictionally engages the actuator rod to move the lens assembly in the direction of the optical axis.

5. The camera module according to claim 2, wherein a position detecting element provided in correspondence with the piezoelectric actuator is used for feeding back position information of a corresponding portion of the lens assembly.

6. The camera module of claim 5, wherein the position detection element is a Hall sensor or a capacitive grating sensor.