CN115379074A

CN115379074A - Optical actuator and corresponding camera module

Info

Publication number: CN115379074A
Application number: CN202110539951.6A
Authority: CN
Inventors: 王明珠; 戎琦; 阙嘉耀; 黄桢; 陈卓
Original assignee: Ningbo Sunny Opotech Co Ltd
Current assignee: Ningbo Sunny Opotech Co Ltd
Priority date: 2021-05-18
Filing date: 2021-05-18
Publication date: 2022-11-22

Abstract

The invention relates to an optical actuator comprising: a housing; a lens carrier; an outer frame; and at least two piezoelectric actuators, each of the piezoelectric actuators being disposed between a bearing surface of the lens carrier and a first sidewall of the outer frame; each piezoelectric driving device comprises a linear piezoelectric element, a rotor, a friction part and an excitation source; the length direction of the linear piezoelectric element is consistent with the direction of an optical axis, and the linear piezoelectric element comprises at least three polarization area sections, wherein a first polarization area section and a second polarization area section are alternately arranged; the mover is fixed on the bearing surface, and the friction part is arranged between the inner side surface of the linear piezoelectric element and the mover; when a drive signal is input to the linear piezoelectric element, a surface of the linear piezoelectric element is deformed to drive the mover to move in the direction of the optical axis. The invention also provides a corresponding camera module. The invention has the advantages of small occupied space and large driving force.

Description

Optical actuator and corresponding camera module

Technical Field

The invention relates to the technical field of camera modules, in particular to an optical actuator and a corresponding camera module.

Background

The mobile phone camera module is one of the important components of the intelligent equipment, and the application range and the application amount of the mobile phone camera module in the market are continuously increased. Along with the progress of technique, no matter work or life are all advocating the intellectuality, and realize that one of the intelligent important prerequisite can realize the good interaction with external environment, wherein realize that an important mode of good interaction is the visual perception, and the module of making a video recording is mainly relied on to the visual perception. It can be said that the camera module has been transformed from a silent smart device accessory to one of the key components of smart devices.

In recent years, in order to meet the increasingly wide market demand, high pixels, large chips, and small sizes have become an irreversible trend of development of camera modules. As the photo chip is developed toward high pixels and large chips, the size of optical components fitted to the photo chip is also gradually increased, for example, an optical lens, a filter element, and the like, which brings new challenges to a driving element for driving the optical components for optical performance adjustment, for example, a driving element for driving the optical lens for optical focusing. On the other hand, with the continuous development of intelligent terminal devices (such as smart phones), the functions provided by the camera module of the mobile phone are more and more abundant. The functions of optical zooming and the like are important functions of some mobile phone camera modules. The realization of functions such as auto-focus and optical zoom generally requires that the lens has the ability of moving in the axial direction, that is, the lens can move along the optical axis under the action of a driving signal, and the moving direction and the moving amount are controlled by the input driving signal. Therefore, it is necessary to provide such a camera module with an optical actuator that can drive the lens to move axially.

In the prior art, a main camera of a mobile phone usually adopts a photosensitive chip with a large image plane so as to provide a larger photosensitive pixel area, improve the light incoming amount of a single pixel, and simultaneously arrange a higher number of pixels to realize high pixels. However, the large image plane of the photo-sensing chip causes a size and weight of the optical lens to be increased correspondingly. In particular, the large image plane module usually adopts a vertical structure, and the optical axis direction of the large image plane module is usually consistent with the thickness direction of the mobile phone, that is, the height of the module is very limited. Therefore, how to mount an optical actuator with a large driving force in a narrow space inside a mobile phone (or other electronic terminal devices) to achieve axial driving of a heavy optical lens is one of the issues urgently needed to be solved in the current market.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a piezoelectric optical actuator with small occupied space and large driving force and a solution of a corresponding camera module.

To solve the above technical problem, the present invention provides an optical actuator including: a housing; a lens carrier, the inner side of which is suitable for mounting a lens or a lens group, and the outer side of which is provided with at least two planar bearing surfaces which are parallel to each other (the two bearing surfaces are respectively arranged at the two sides of the lens carrier); the outer frame is arranged between the lens carrier and the shell and comprises at least two first side walls which are parallel to each other, and each first side wall is opposite to one bearing surface; and at least two piezoelectric driving devices, wherein each piezoelectric driving device is arranged between one bearing surface and one first side wall of the outer frame opposite to the bearing surface. Wherein each of the piezoelectric driving devices includes a linear piezoelectric element, a mover, a friction portion, and an excitation source; the length direction of the linear piezoelectric element is consistent with the optical axis direction of the lens or the lens group, the linear piezoelectric element comprises at least three polarization area sections polarized along the thickness direction of the linear piezoelectric element, the polarization area sections are first polarization area sections or second polarization area sections, the polarization directions of the first polarization area sections and the second polarization area sections are opposite, and the first polarization area sections and the second polarization area sections are alternately arranged along the length direction of the linear piezoelectric element; the mover is fixed to the bearing surface, and the friction portion is attached between an inward surface of the linear piezoelectric element and the mover; and both ends of the friction portion are pressed by the linear piezoelectric element and the mover, respectively, in an initial state, and a surface of the linear piezoelectric element is deformed when a driving signal is input to the linear piezoelectric element to drive the mover to move in the direction of the optical axis.

Wherein the driving signal comprises a first driving voltage applied to the first polarization region segment and a second driving voltage applied to the second polarization region segment, and a phase difference between the first driving voltage and the second driving voltage is pi/2 or-pi/2.

Wherein the friction portion has a plurality of friction portions, and the friction portions are uniformly arranged on an inner side surface of the linear piezoelectric element along a length direction of the linear piezoelectric element.

The lens carrier is connected with the outer frame through an elastic element so as to form pretightening force between the lens carrier and the outer frame.

The lens carrier and the outer frame are respectively provided with a magnet and a coil, so that pretightening force is formed between the lens carrier and the outer frame.

An elastic layer is arranged between the outer side surface of the linear piezoelectric element and the outer frame, and the elastic layer is pressed to generate stress so as to press the linear piezoelectric element and the friction part on the surface of the mover.

Wherein one of the friction portions is provided on an inner side surface of each of the first polarization region segments and the second polarization region segments.

The lens carrier is a lens barrel, and the outer side surface of the lens barrel is rectangular.

The lens carrier is a lens barrel, and the outer side surface of the lens barrel is in a cutting circle shape.

The lens carrier is an inner frame, the inner frame is arranged on the outer side surface of the lens barrel, and the inner frame is provided with at least two flat second side walls which are oppositely arranged and are parallel to each other.

Wherein the linear piezoelectric element has a length of less than 20mm and a width of less than 1mm, and the sum of the thickness of the linear piezoelectric element and the thickness of the friction portion is less than 1.5mm.

Wherein the linear piezoelectric element has a length of less than 10mm and a width of less than 0.7mm, and the sum of the thickness of the linear piezoelectric element and the thickness of the friction portion is less than 1mm.

The piezoelectric driving device further comprises a friction layer arranged on the inner side surface of the linear piezoelectric element, and the friction part is arranged on the friction layer.

Wherein the linear piezoelectric element has a length greater than a length of the friction layer.

The piezoelectric driving device further comprises a friction layer, wherein the friction layer is arranged on the outer surface of the rotor, or the rotor is made of a friction material.

Wherein the thickness of the elastic layer is 10-50 μm.

Wherein fixing portions made of a non-piezoelectric material are provided at both ends of the linear piezoelectric element, and the fixing portions are fixed together with the outer frame; a gap is formed between the back surface of the linear piezoelectric element and the outer frame.

According to another aspect of the present application, there is also provided a camera module, which includes: a lens or a lens group; a photosensitive assembly; and the aforementioned optical actuator; the lens or lens group is mounted on the inner side surface of the lens carrier of the optical actuator; the optical actuator is mounted on the top surface of the photosensitive assembly.

Compared with the prior art, the application has at least one of the following technical effects:

1. in some embodiments of the present application, an outer side surface of the lens barrel is designed to be rectangular, an outer frame is disposed between the lens barrel and the actuator housing, the linear piezoelectric element and the mover are disposed between the outer frame and the lens barrel, the mover is supported by the outer side surface of the lens barrel, a back surface of the linear piezoelectric element is supported by the outer frame, and a pre-tightening force for making the linear piezoelectric element and the mover approach each other is applied between the outer frame and the lens barrel, so that the linear piezoelectric element and the mover are coupled to drive the lens barrel to move along the optical axis direction relative to the actuator housing by surface fluctuation (e.g., fluctuation in the form of a traveling wave) of the linear piezoelectric element. This design has the advantage of a small footprint and a large driving force, especially in the direction perpendicular to the optical axis, the footprint of the piezoelectric driving device is small.

2. In some embodiments of the present application, the piezoelectric driving devices may be symmetrically disposed on two sides of the lens barrel, and this design may make the axial movement of the carrier of the optical axis actuator more balanced than when only the piezoelectric driving devices are disposed on a single side.

3. In some embodiments of the present application, an elastic layer may be disposed between the back surface of the linear piezoelectric element and the outer frame, and then the linear piezoelectric element and the friction portion thereof are pressed against the mover by the elastic layer, so as to achieve a pre-tightening force required by the traveling wave piezoelectric driving device with a very small occupied space.

4. In some embodiments of the present application, the side wall of the outer frame for supporting the piezoelectric driving device may be made of metal, and the side wall may have a flat inner surface, so as to provide a flat supporting surface for the back surface of the linear piezoelectric element, thereby ensuring that the surface fluctuation of the linear piezoelectric element has higher precision.

Drawings

Fig. 1 shows a schematic longitudinal cross-sectional view of a camera module according to an embodiment of the present application;

fig. 2 shows a schematic top view of a camera module according to an embodiment of the present application;

FIG. 3 illustrates a linear piezoelectric actuator in one embodiment of the present application;

fig. 4 illustrates a moving direction of a mover in an embodiment of the present application;

fig. 5a is a schematic view showing the operational relationship of the mover, the friction portion, and the linear piezoelectric element when the surface of the linear piezoelectric element fluctuates in one embodiment of the present application;

fig. 5b is a schematic view showing the action relationship of the mover, the friction portion, and the linear piezoelectric element in the second state;

FIG. 6 shows the direction of motion of a micro-amplitude elliptical motion of a particle at the surface of a linear piezoelectric element;

FIG. 7 illustrates a linear piezoelectric actuator in another embodiment of the present application;

FIG. 8 is a schematic diagram illustrating the structure and connection of the linear piezoelectric devices to the outer frame according to an embodiment of the present application;

FIG. 9 is a schematic view showing the structure and connection of the linear piezoelectric devices to the outer frame according to another embodiment of the present application;

FIG. 10 shows a schematic top view of an optical actuator in an embodiment of the present application;

FIG. 11 shows a schematic top view of an optical actuator in another embodiment of the present application;

FIG. 12 shows a perspective view of one of the subframes of FIG. 11;

FIG. 13 shows a schematic top view of an optical actuator of one variant embodiment of the present application;

FIG. 14 shows a schematic top view of an optical actuator of another variant embodiment of the present application;

figure 15 shows a schematic top view of an optical actuator of a further variant embodiment of the present application;

fig. 16 shows a schematic structural diagram of a piezoelectric actuator in a modified embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that the expressions first, second, etc. in this specification are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, a first body discussed below may also be referred to as a second body without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of an object have been slightly exaggerated for convenience of explanation. The figures are purely diagrammatic and not drawn to scale.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "including," and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

As used herein, the terms "substantially," "about," and the like are used as terms of table approximation and not as terms of table degree, and are intended to account for inherent deviations in measured or calculated values that will be recognized by those of ordinary skill in the art.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Fig. 1 shows a longitudinal cross-sectional view of a camera module according to an embodiment of the present application. Referring to fig. 1, in the present embodiment, the image capturing module includes a photosensitive assembly 100, an optical actuator 200 mounted on a top surface of the photosensitive assembly 100, and an optical lens 300 mounted in the optical actuator 200. Further, fig. 2 shows a schematic top view of the camera module according to an embodiment of the present application. Referring to fig. 1 and fig. 2 in combination, in the present embodiment, the optical lens 300 includes a lens barrel 310 and at least one optical lens 320 (for example, the number of the optical lenses in fig. 1 is four) installed in the lens barrel 310. In a top view, the outer side of the lens barrel 310 is rectangular, and the inner side thereof is circular, that is, a circular through hole is provided inside the lens barrel 310 to accommodate and mount the optical lens 320 on the inner side of the lens barrel 310. The optical actuator 200 includes a housing 210 (also referred to as an actuator case), an outer frame 220 disposed between the housing 210 and a lens barrel 310, the outer frame 220 having at least two first side walls 221 parallel to each other, and the two first side walls 221 being parallel to an optical axis of the optical lens 300. In this embodiment, the linear piezoelectric driving device 230 is disposed between the first sidewall 221 of the outer frame 220 and the outer side surface of the lens barrel 310. Fig. 3 shows a linear piezoelectric actuator in one embodiment of the present application. Referring to fig. 3, the linear piezoelectric driving device 230 includes a linear piezoelectric element 231, a mover 232, and a friction portion 233. The mover 232 may be supported and fixed on an outer surface of the lens barrel 310, and the friction portion 233 is disposed between the mover 232 and the linear piezoelectric element 231. That is, the mover 232, the friction portion 233, and the linear piezoelectric element 231 are arranged in this order from the inside to the outside. A spring elastic sheet 240 (or other type of elastic element) is disposed between the lens barrel 310 and the outer frame 220, the lens barrel 310 and the outer frame 220 are connected by the spring elastic sheet 240, and the spring elastic sheet 240 provides an elastic force to provide a pre-pressure (or called pre-pressure) for the linear piezoelectric driving device 230. The housing 210 accommodates the optical lens 300, the outer frame 220, and the optical actuator 200 therein, and the housing 210 has a substantially rectangular outer shape. The top of the housing 210 may have a circular opening so that light may be incident on the optical lens 300 through the housing 210. Further, in this embodiment, the linear piezoelectric element 231 has a first polarization region section A1 and a second polarization region section A2, and the first polarization region section A1 and the second polarization region section A2 may have a plurality of polarization region sections, and the two polarization region sections are alternately arranged along the length direction of the linear piezoelectric element 231. The first polarization region section A1 and the second polarization region section A2 are each polarized in the thickness direction of the linear piezoelectric element 231, and the polarization directions thereof are opposite to each other. When a first driving voltage is applied to the first polarization region segment A1 and a second driving voltage is applied to the second polarization region segment A2, the linear piezoelectric element 231 changes its surface shape by the inverse piezoelectric effect. Specifically, when the phase difference between the first driving voltage and the second driving voltage is pi/2, the particles on the surfaces of the first polarization section A1 and the second polarization section A2 both vibrate, and the vibration is an ultrasonic microscopic vibration, which may also be referred to as a microscopic elliptical motion. The micro-amplitude elliptical motion of the particles on the surface of the linear piezoelectric element 231 may make the surface of the linear piezoelectric element 231 undulate as a whole, and the undulation directions of the surfaces of the first polarization region section A1 and the second polarization region section A2 are the same, so that the surface of the linear piezoelectric element 231 may be coupled in a traveling wave type undulation state. When the surface of the linear piezoelectric element 231 performs traveling wave type motion, the piezoelectric element has a motion tendency relative to the mover, and a friction portion between the linear piezoelectric element and the mover may generate a static friction force to prevent the motion tendency, and the static friction force may drive the mover to move, where the moving direction is a direction parallel to the optical axis, and the direction may be marked as a positive direction of the optical axis, for example. Similarly, when the phase difference between the first driving voltage and the second driving voltage is-pi/2, each particle on the surface of the first polarization area section A1 and the second polarization area section A2 generates a micro-amplitude elliptical motion, and the direction of the micro-amplitude elliptical motion of the particle is opposite to the motion direction when the phase difference is pi/2. For example, if the first driving voltage and the second driving voltage have a phase difference of pi/2, the particles on the surfaces of the first polarized section A1 and the second polarized section A2 generate clockwise micro-amplitude elliptical motion, and the particles on the surfaces of the first polarized section A1 and the second polarized section A2 generate counterclockwise micro-amplitude elliptical motion when the first driving voltage and the second driving voltage have a phase difference of-pi/2. In this embodiment, when a mass point on the surface of the linear piezoelectric element generates a counterclockwise motion, the friction force drives the mover to move in a reverse direction, i.e., in a negative direction along the optical axis. Fig. 4 shows a moving direction of a mover in an embodiment of the present application. Referring to fig. 4, in the present embodiment, the moving direction of the mover 232 is parallel to the length direction of the linear piezoelectric element 231.

Further, fig. 5a is a schematic diagram showing an action relationship of the mover, the friction portion, and the linear piezoelectric element when the surface of the linear piezoelectric element fluctuates in one embodiment of the present application. Referring to fig. 5a, in the present embodiment, a first driving voltage is applied to the first polarization region section A1, a second driving voltage is applied to the second polarization region section A2, and the phase difference between the first driving voltage and the second driving voltage is pi/2, so that each particle on the surface of the linear piezoelectric element 231 forms a micro-amplitude elliptical motion with an elliptical motion trajectory (fig. 6 shows the motion direction of the micro-amplitude elliptical motion of one particle on the surface of the linear piezoelectric element), the micro-amplitude elliptical motion of each particle macroscopically appears as a wavy fluctuation on the surface of the linear piezoelectric element 231, and the fluctuation moves in a traveling wave manner along the first direction D1. That is, both the peak and the trough of the wavy surface of the linear piezoelectric element 231 move in the first direction D1 while the above-described driving voltage combination (in which the first driving voltage and the second driving voltage are out of phase by pi/2) is applied. Since the friction portion 233 is fixed to the surface of the linear piezoelectric element 231, when the traveling wave on the surface of the linear piezoelectric element 231 moves in the first direction D1, the friction portion 231 also moves in the first direction D1 or a movement tendency to move in the first direction D1 is generated. Referring to fig. 5a, the surface of the first polarized region segment A1 is in a wave crest state, that is, the first polarized region segment A1 is arched to a side close to the lens 300 (that is, arched to the inner side of the module), so that the friction part 233 at the first polarized region segment A1 is in close contact with the mover 232, thereby forming a friction force (generally, a static friction force) at the contact surface of the friction part 233 and the stator 232, the direction of the friction force is opposite to the direction of the wave crest of the linear piezoelectric element 231 moving, thereby driving the mover to move in the opposite direction, that is, in the second direction D2. With respect to the second polarization zone A2, since the surface of the second polarization zone A2 is in a valley state in the state shown in fig. 5a, that is, the surface of the second polarization zone A2 is arched to the side away from the lens 300 (i.e., arched to the outside of the module), so that the friction part 233 at the second polarization zone A2 is out of contact with the mover 232, the movement of the valley of the surface of the second polarization zone A2 does not act on the mover 232. Further, when the traveling wave of the surface of the linear piezoelectric element 231 continues to move, the fluctuation of the surface of the linear piezoelectric element 231 can be made to enter the second state. Fig. 5b is a schematic view showing the operational relationship of the mover, the friction portion, and the linear piezoelectric element in the second state. Referring to fig. 5b, in the second state, the surface of the first polarized region section A1 is in a valley state where the friction part 233 is out of contact with the mover 232, and the surface of the second polarized region section A2 is in a peak state where the friction part 233 is in close contact with the mover 232. At this time, a friction force (generally, a static friction force) is generated at a contact surface of the friction part 233 at the second polarization area segment A2 with the mover 232 to overcome a movement tendency of the friction part 233 with respect to the mover 232 in the first direction D1, so that the mover 232 is urged to move in an opposite direction, i.e., in the second direction D2 by the friction force. Since the mover 232 is fixed on the outer side surface of the lens barrel, under the action of the first driving voltage combination (i.e. the phase difference between the first driving voltage and the second driving voltage is pi/2), the lens barrel and the optical lens 300 can be moved along the second direction D2 under the driving of the mover 232, so as to realize the movement of the optical lens 300 along the positive direction of the optical axis.

Further, when the second driving voltage combination is applied to the first polarization area section A1 and the second polarization area section A2, i.e. the first driving voltage and the second driving voltage have a phase difference of-pi/2, the moving direction of the wave on the surface of the linear piezoelectric element 231 is the second direction D2, and at this time, the mover 232 will move along the first direction D1, thereby realizing the movement of the optical lens along the negative direction of the optical axis. The specific principle of the method can be similar to the movement under the combined driving of the first driving voltage in the foregoing, and the detailed description is omitted here.

It can be seen that, based on the linear piezoelectric element, the first and second driving voltage combinations are applied to the first and second polarization region segments A1 and A2, so as to achieve bidirectional driving in the optical axis direction of the optical lens. In some embodiments of the present application, the linear piezoelectric element may have a length of less than 20mm, a width of less than 1mm, and a thickness of less than 1.5mm. The thickness may be the total thickness of the linear piezoelectric element itself plus the thickness of the friction portion, that is, the total thickness of the linear piezoelectric element and the friction portion may be less than 1.5mm. Since the thickness of the linear piezoelectric element and its attachment members is extremely small, the linear piezoelectric element can be directly provided in the gap between the outer surface of the lens barrel and the inner surface of the housing, and there is no need to provide a special drive element mounting structure on the lens barrel. Specifically, in some existing piezoelectric driving schemes, a dedicated mounting boss needs to be fabricated on one side of the lens barrel, so that the piezoelectric driving device applies an acting force to the lens barrel through the mounting boss, and further drives the optical lens to move axially. The mounting boss tends to increase the thickness of the lens barrel, resulting in an increase in the volume of the camera module. In the scheme of the application, a linear piezoelectric element (as shown in fig. 1 and fig. 2) can be respectively arranged at symmetrical positions in a gap between the outer shell and the outer side surface of the lens barrel, so that on one hand, the camera module can keep a smaller volume, and on the other hand, the linear piezoelectric element is arranged at the symmetrical positions, so that the stress of the lens barrel can be more balanced, the precision of the axial movement of the lens barrel is improved, and the inclination of the axial movement of the lens barrel is avoided.

Further, in some preferred embodiments of the present application, the linear piezoelectric element may have a length of less than 10mm (e.g., 6mm or 4.2 mm), a width of less than 0.7mm, and a thickness of less than 1mm (which refers to the total thickness of the linear piezoelectric element plus the friction portion).

Further, in some embodiments of the present application, the number of polarization region segments of a single linear piezoelectric element is at least three (the polarization region segments include a first or a second polarization region segment, and the number of polarization region segments refers to the sum of the number of first and second polarization region segments), thereby facilitating the formation of a traveling wave motion of the surface of the linear piezoelectric element. When the number of the polarization region segments of the linear piezoelectric element is small, for example, when the number of the polarization region segments is three, by applying a driving voltage having a set phase difference to adjacent polarization region segments having different polarization directions, the surface of the linear piezoelectric element can be formed into a desired wavy shape, and this design also contributes to reducing the length of the linear piezoelectric element due to the small number of the polarization region segments. In the present application, the length direction of the linear piezoelectric element coincides with the optical axis direction of the image pickup module, and therefore, reducing the length of the linear piezoelectric element contributes to reducing the height of the image pickup module.

Further, in the embodiment corresponding to fig. 5a and 5b, the friction portion 233 is provided in both the first polarization region section A1 and the second polarization region section A2 of the linear piezoelectric element 231, but it should be noted that the present invention is not limited thereto. For example, fig. 7 shows a linear piezoelectric actuator in another embodiment of the present application. Referring to fig. 7, in this embodiment, the friction portion 233 may be provided only in the first polarization region section A1 or only in the second polarization region section A2. In this embodiment, when the linear piezoelectric element 231 is energized and the first or second driving voltage combination is applied, and the friction part 233 of the first or second polarization region section A1 or A2 presses the mover, a frictional force opposite to the traveling direction of the traveling wave formed by the micro-elliptical motion of the surface particles is generated, and the mover 232 is driven to move along the optical axis. However, since the friction portion 233 is only disposed in the first polarization section A1 or only in the second polarization section A2, the driving time of the mover 232 is relatively short and the moving speed of the mover 232 is relatively slow compared to the embodiments corresponding to fig. 5a and 5 b.

Further, fig. 16 shows a schematic structural diagram of a piezoelectric driving device in one modified embodiment of the present application. Referring to fig. 16, in the present embodiment, a friction layer 234 is disposed on a surface (i.e., a front surface or an inner surface) of the linear piezoelectric element 231 on a side close to the mover 232, and the friction portion 233 is disposed on the friction layer 234. Preferably, the length of the linear piezoelectric element 231 is greater than that of the friction layer, so as to ensure the linearity of the linear piezoelectric element and ensure the driving stroke of the piezoelectric driving device. Further, in another modified embodiment, the friction layer may be provided on the surface of the mover on the side close to the linear piezoelectric elements, or the material of the mover may be a friction material (i.e., a material having a large friction force).

Further, fig. 8 is a schematic diagram illustrating a structure and a connection relationship between the linear piezoelectric device and the outer frame in an embodiment of the present application. Referring to fig. 8, in an embodiment of the present application, the linear piezoelectric elements 231 may be fixed to the outer frame 220 to serve as a stator of the piezoelectric driving unit 230. Here, the back surface of the linear piezoelectric element 231 (which refers to the outer surface of the linear piezoelectric element, i.e., the side surface close to the housing) may be supported by the elastic layer 212 against the inner side surface of the first side wall 221 (refer to fig. 1 and 2 in combination) of the outer frame 220. Thus, when the linear piezoelectric element 231 is deformed and the particles on the surface thereof enter a slight elliptical motion, the elastic layer 212 has elasticity, and therefore the deformation of the back surface of the linear piezoelectric element 231 and the slight elliptical motion thereof are not hindered. This is because the stress generated by the deformation of the piezoelectric element is much greater than the elastic force generated by the deformation of the elastic layer 212. Meanwhile, when the linear piezoelectric elements 231 are not energized, the pre-stress between the outer frame 220 and the lens barrel 310 (refer to fig. 1 and 2 in combination) may also be transmitted to the linear piezoelectric elements and the friction portions 233 thereof through the elastic layer 212, so that the optical lens 300 may be held at its initial position. In this embodiment, the thickness of the elastic layer 212 may be 10 to 50 μm. During manufacturing, a glue material with the thickness of 10-50 μm is coated on the inner side surface of the side wall of the outer frame, then the back surface of the linear piezoelectric element is pasted, and an elastic layer with elasticity is formed after the glue material is solidified, and the elastic layer is positioned between the back surface of the linear piezoelectric element and the side wall of the outer frame.

Further, fig. 9 is a schematic diagram illustrating the structure and connection relationship between the linear piezoelectric devices and the outer frame in another embodiment of the present application. In another embodiment, the elastic layer on the back surface of the linear piezoelectric element 231 may be eliminated. In this embodiment, fixing portions 235 (the fixing portions 235 may be made of a non-piezoelectric material) are provided at both ends of the linear piezoelectric element 231, and the fixing portions 235 are fixed to the outer frame 220. The linear piezoelectric element 231 can be fixed to the outer frame 220 by the fixing portions 235 at both ends thereof, and can be used as a stator of the piezoelectric driving unit 230. In this embodiment, a gap (e.g., an air gap) may be formed between the back surface of the linear piezoelectric element 231 and the outer frame 220. In this embodiment, when the power is not supplied, the linear piezoelectric element 231 is linear and has a certain rigidity, so that the pre-pressure of the spring elastic piece 240 between the outer frame 220 and the lens barrel 310 can be transmitted to the linear piezoelectric element 231 and the friction portion 233 thereof, so that the friction portion 233 can press the mover 232, and the optical lens 300 can be maintained at its initial position when the power is not supplied. In this embodiment, the elastic layer may not be disposed on the back surface of the linear piezoelectric element, so that the deformation of the back surface of the linear piezoelectric element is not disturbed by the elastic layer, that is, the actual condition of the micro-amplitude elliptical motion of the mass point on the back surface of the linear piezoelectric element is more consistent with the theoretical value, thereby facilitating to improve the control accuracy of the axial movement of the lens.

It should be noted that, in the present application, the above-mentioned manner of generating the pre-pressure by the spring elastic sheet is not exclusive. For example, in a variant embodiment of the present application, the spring blades may also be replaced by electromagnetic assemblies. The electromagnetic assembly may include a magnet and a coil, which may be disposed at the lens barrel and the outer frame, respectively. In this arrangement, pre-compression may be provided to the piezoelectric actuator by interaction of the magneto coils. Further, in this embodiment, the housing may be made of a magnetically conductive material, which may be, for example, a ferromagnetic material, including iron, nickel, cobalt, or alloys thereof. In this embodiment, the housing may have six pins extending in a direction parallel to the optical axis for holding magnetism and enhancing magnetic force.

Further, in another embodiment of the present application, an elastic layer is disposed on the back surface of the linear piezoelectric elements, the number of the linear piezoelectric elements may be an even number, and each pair of linear piezoelectric elements is disposed on two opposite sides of the camera module, for example, refer to fig. 1 and fig. 2. In this embodiment, the elastic layer may be pressed toward the center by two opposite side walls of the outer frame to form a pre-tightening force, so that the elastic layer presses the linear piezoelectric element toward the inner side, and the friction portion presses the mover. In the solution of this embodiment, the spring elastic sheet may be omitted, and the pre-tightening force applied to the piezoelectric driving device may be provided by the elastic layer on the back surface of the linear piezoelectric element. According to the scheme of the embodiment, the spring elastic sheet can be omitted, the device structure and the assembly process are simplified, and the production efficiency and the production yield are improved.

Further, fig. 10 shows a schematic top view of an optical actuator in an embodiment of the present application. Referring to fig. 10, in the present embodiment, four linear piezoelectric elements may be disposed around a rectangular lens barrel 310. In the optical actuator, the outer frame 220 may have four first sidewalls, and spring strips 240 are disposed at corners of the outer frame 220, wherein the spring strips 240 connect the outer frame 220 and the lens barrel 310 to apply a pre-load force to the piezoelectric driving device 230 therebetween. In this embodiment, each piezoelectric driving device 230 realizes its driving function based on one linear piezoelectric element, and the driving principle is described in the foregoing, which is not described herein again.

Further, fig. 11 shows a schematic top view of an optical actuator in another embodiment of the present application. Fig. 12 shows a perspective view of one of the subframes of fig. 11. Referring to fig. 11 and 12, the present embodiment substantially corresponds to the embodiment shown in fig. 10, except that the outer frame 220 of the present embodiment is formed by combining a first subframe and a second subframe. Referring to fig. 12, in this embodiment, two sides of the first sub-frame may be disposed with two oppositely disposed first sidewalls, and the other two sides are hollowed out, and the hollowed-out side 222 in fig. 12 shows a state that two sides of the sub-frame are hollowed out. The second subframe may be shaped to conform to the first subframe. The combination of the two sub-frames allows the optical actuator housing to have corresponding outer frame sidewalls (i.e., the first sidewall 221) at each of the four sides thereof, thereby facilitating installation and pre-tensioning of the corresponding piezoelectric drivers.

Further, in the present application, the shape of the outer side surface of the lens barrel is not limited to a rectangle. For example, in some embodiments, the outer side of the barrel can take other shapes. Fig. 13 shows a schematic top view of an optical actuator of one variant embodiment of the present application. Referring to fig. 13, in the present embodiment, the barrel outer side 311 of the optical lens 300 may be a cut circle. Herein, the cutting circle means a shape formed by cutting a circle straight. In this embodiment, the outer side surface of the lens barrel has two parallel planes, and the two planes can be used as the bearing surfaces 311a of the movers of the two piezoelectric driving devices. In fact, in the present application, the outer side surface of the lens barrel may have an even number of symmetrically arranged planes as the bearing surfaces of the mover. For example, the outer side surface of the lens barrel may have a hexagonal shape, an octagonal shape, or the like.

Further, in some embodiments of the present application, the piezoelectric driving device may be disposed at four corner regions of the optical actuator housing. For example, fig. 14 shows a schematic top view of an optical actuator according to another variant embodiment of the present application. Referring to fig. 14, in the present embodiment, the barrel outer side surface 311a is substantially circular, and at two diagonal positions corresponding to the housing, the barrel outer side surface 311 protrudes outward to form two symmetrical parallel bearing surfaces 311a. An outer frame 220 may be disposed between the outer housing and the bearing surface 311a of the lens barrel 310, the outer frame 220 having two first sidewalls disposed at an angle of 45 degrees. The piezoelectric driving device 230 may be disposed between the first sidewall of the outer frame 220 and the bearing surface 311a of the lens barrel. In this embodiment, each piezoelectric driving device 230 provides a driving force based on the linear piezoelectric element 231, and the driving principle is described above and will not be described herein again. In the solution of the present embodiment, the piezoelectric driving device 230 can be disposed in the gap between the rectangular housing and the substantially circular lens barrel in the four corner region of the housing, and therefore the radial dimensions of the optical actuator and the camera module can be effectively reduced. Wherein radial refers to a direction perpendicular to the optical axis.

Further, fig. 15 shows a schematic top view of an optical actuator of yet another variant embodiment of the present application. Referring to fig. 15, in the present embodiment, the outer surface 311 of the lens barrel is substantially circular, and at four corners of the housing, the outer surface 311 of the lens barrel protrudes outwards to form four bearing surfaces, and two bearing surfaces on each diagonal line are symmetrically arranged and parallel to each other. An outer frame 220 having four first sidewalls disposed at 45 degrees may be disposed between the outer housing 210 and the bearing surface 311a of the lens barrel. The piezoelectric driving device 230 may be disposed between the first sidewall of the outer frame 220 in the four corner regions and the bearing surface of the lens barrel. In this embodiment, each piezoelectric driving device 230 provides a driving force based on a linear piezoelectric element, and the driving principle is described above and will not be described herein again. In the aspect of the present embodiment, the piezoelectric driving device can be disposed in the gap between the rectangular housing and the substantially circular lens barrel in the four corner region of the housing, and therefore the radial dimensions of the optical actuator and the camera module can be effectively reduced. Wherein radial refers to a direction perpendicular to the optical axis.

Further, in some embodiments of the present application, the optical actuator may further comprise an inner frame. The inner frame may be fixed to an outer side surface of the lens barrel. The inner frame may have a side wall (may be referred to as a second side wall) corresponding to the outer frame, and the piezoelectric driving device may be disposed between the side wall of the outer frame and the side wall of the inner frame. The spring elastic sheet is connected with the outer frame and the inner frame, so that pretightening force is applied to the piezoelectric driving device. In this embodiment, each piezoelectric driving device provides a driving force based on a linear piezoelectric element, and the driving principle is described above and is not described herein again.

In some embodiments of the present application, the linear piezoelectric element may be formed by splicing a plurality of piezoelectric ceramic pieces end to end. Specifically, the end faces of any two adjacent piezoelectric ceramic plates can be bonded through the adhesive material, so that the two piezoelectric ceramic plates are spliced together end to end. The piezoelectric ceramic pieces are polarized along the thickness direction of the piezoelectric ceramic pieces, and the polarization directions of any two adjacent piezoelectric ceramic pieces are opposite.

In another embodiment of the present application, the linear piezoelectric element is a traveling wave linear piezoelectric element, and two identical piezoelectric bodies may be bonded together with a half polarization region length offset from each other.

In some embodiments of the present application, each of the first polarization region segment A1 and the second polarization region segment A2 of the linear piezoelectric element is connected to a wire, and further connected to an excitation source. The excitation source applies corresponding piezoelectric drive signals to the first polarization zone segment A1 and the second polarization zone segment A2, respectively. The excitation source may be disposed in a circuit board of the photosensitive assembly. The wires may laterally connect the respective first and second polarization region sections A1 and A2. That is, the connecting end positions of the lead wires and the respective first polarized area sections A1 and second polarized area sections A2 are kept away from the surface of the linear piezoelectric element (i.e., from the front and back surfaces of the linear piezoelectric element that is required to generate a slight elliptical motion). The other end of the lead is connected to a circuit board of the photosensitive assembly, or can be connected to a circuit board arranged in other areas of the camera module, and the excitation source can be arranged on the circuit board.

In the above embodiments, the surfaces of the linear piezoelectric elements all exhibit a traveling wave type fluctuation state. However, the present application is not limited thereto, and in some modified embodiments of the present application, the surface fluctuation mode of the linear piezoelectric element may be configured as a standing wave type fluctuation state. Specifically, in a modified embodiment, the first polarization section A1 and the second polarization section A2 may have the same polarization direction, wherein after the linear piezoelectric element is turned on, by inputting alternate voltage signals into the first polarization section A1 and the second polarization section A2, a plurality of sets of the first polarization section A1 and the second polarization section A2 alternately arranged with each other are deformed in different directions, so as to drive the friction portion to move along a preset direction in a standing wave manner, and further drive the mover to move along the direction of the optical axis.

Further, in an embodiment of the present application, the photosensitive assembly includes a circuit board, a photosensitive chip mounted on a surface of the circuit board, a filter holder mounted on the surface of the circuit board and surrounding the photosensitive chip, and a filter mounted on the filter holder. The top surface of the filter holder may be a flat surface for mounting a base of the optical actuator. In another embodiment, the photosensitive assembly may also be manufactured based on an MOC process, that is, the filter holder may be replaced by a mold support, which may be directly formed on the circuit board based on a module process, and the mold support extends inward and covers an edge area of the photosensitive chip. The optical filter is mounted to the mold support, and a top surface of the mold support is adapted to mount the optical actuator. In yet another embodiment, the photosensitive assembly may also be fabricated based on a MOB process, which is different from a MOC process in that the mold support does not contact the photosensitive chip.

In the present invention, a linear piezoelectric element may be provided in a gap between the housing and the lens barrel, a surface of the linear piezoelectric element may be brought into a wave state (for example, a traveling wave state) by an appropriate driving voltage, and a friction portion provided on the wave surface may act on the mover to drive the mover to move in a longitudinal direction (i.e., an optical axis direction) of the linear piezoelectric element. In the scheme, the piezoelectric driving device can be arranged in a gap between the shell and the lens barrel, so that the occupied space is small, the driving force is large, and the lens with larger weight can be driven. For example, based on the piezoelectric driving scheme of the present application, on the premise that the number of linear piezoelectric elements is greater than or equal to two and the length of each linear piezoelectric element is less than 2mm, a lens with a mass of 400mg or more can be driven.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An optical actuator, comprising:

a housing;

the inner side surface of the lens carrier is suitable for mounting a lens or a lens group, and the outer side surface of the lens carrier is provided with at least two planar bearing surfaces which are parallel to each other;

the outer frame is arranged between the lens carrier and the shell and comprises at least two first side walls which are parallel to each other, and each first side wall is opposite to one bearing surface; and

at least two piezoelectric actuators, each of the piezoelectric actuators being disposed in a gap between one of the bearing surfaces and one of the first sidewalls opposite the bearing surface;

wherein each of the piezoelectric driving devices includes a linear piezoelectric element, a mover, a friction portion, and an excitation source; the length direction of the linear piezoelectric element is consistent with the optical axis direction of the lens or the lens group, the linear piezoelectric element comprises at least three polarization area sections polarized along the thickness direction of the linear piezoelectric element, the polarization area sections are first polarization area sections or second polarization area sections, the polarization directions of the first polarization area sections and the second polarization area sections are opposite, and the first polarization area sections and the second polarization area sections are alternately arranged along the length direction of the linear piezoelectric element; the mover is fixed to the bearing surface, and the friction portion is attached between an inward surface of the linear piezoelectric element and the mover; and both ends of the friction portion are pressed by the linear piezoelectric element and the mover, respectively, in an initial state, and a surface of the linear piezoelectric element is deformed to drive the mover to move in the direction of the optical axis when a drive signal is input to the linear piezoelectric element.

2. An optical actuator according to claim 1, wherein the drive signal comprises a first drive voltage applied to the first polarization zone segment and a second drive voltage applied to the second polarization zone segment, the first and second drive voltages being out of phase by pi/2 or-pi/2.

3. The optical actuator according to claim 1, wherein the friction portion has a plurality of friction portions, and the friction portions are arranged uniformly on an inner side surface of the linear piezoelectric element along a length direction of the linear piezoelectric element.

4. An optical actuator according to claim 1, wherein the lens carrier and the outer frame are connected by an elastic element to form a preload between the lens carrier and the outer frame.

5. An optical actuator according to claim 1, wherein the lens carrier and the outer frame are provided with a magnet and a coil, respectively, to form a preload between the lens carrier and the outer frame.

6. An optical actuator according to claim 1, wherein an elastic layer is provided between an outer side surface of the linear piezoelectric element and the outer frame, and the elastic layer is pressed to generate stress to press the linear piezoelectric element and the friction portion against the mover surface.

7. An optical actuator according to claim 3, wherein one of the friction portions is provided on an inner side surface of each of the first and second polarization region segments.

8. An optical actuator according to claim 1, wherein the lens carrier is a lens barrel, an outer side surface of the lens barrel being rectangular.

9. An optical actuator according to claim 1, wherein the lens carrier is a lens barrel, an outer side surface of the lens barrel being in a cut circle shape.

10. An optical actuator according to claim 1, wherein the lens carrier is an inner frame mounted to an outer side surface of the lens barrel, the inner frame having at least two flat second side walls arranged opposite and parallel to each other.

11. An optical actuator according to claim 1, wherein the linear piezoelectric element has a length of less than 20mm and a width of less than 1mm, and a sum of a thickness of the linear piezoelectric element itself and a thickness of the friction portion is less than 1.5mm.

12. An optical actuator according to claim 1, wherein the linear piezoelectric element has a length of less than 10mm and a width of less than 0.7mm, and the sum of the thickness of the linear piezoelectric element itself and the thickness of the friction portion is less than 1mm.

13. An optical actuator according to claim 1, wherein the piezoelectric driving device further comprises a friction layer provided on an inner side surface of the linear piezoelectric element, the friction portion being provided on the friction layer.

14. An optical actuator according to claim 13, wherein the linear piezoelectric element has a length greater than a length of the friction layer.

15. An optical actuator according to claim 13, wherein the piezoelectric driving means further comprises a friction layer provided on an outer surface of the mover, or the material of which the mover is made is a friction material.

16. An optical actuator according to claim 6, wherein the thickness of the elastic layer is 10-50 μm.

17. The optical actuator according to claim 4, wherein fixing portions made of a non-piezoelectric material are provided at both ends of the linear piezoelectric element, and the fixing portions are fixed together with the outer frame; a gap is formed between the back surface of the linear piezoelectric element and the outer frame.

18. The utility model provides a module of making a video recording which characterized in that includes:

a lens or a lens group;

a photosensitive assembly; and

the optical actuator of any one of claims 1-17; the lens or lens group is mounted on the inner side surface of the lens carrier of the optical actuator; the optical actuator is mounted on the top surface of the photosensitive component.