CN111474805A

CN111474805A - MEMS lens driver

Info

Publication number: CN111474805A
Application number: CN202010453233.2A
Authority: CN
Inventors: 邓伟; 苗晓丹; 高翔
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2020-05-26
Filing date: 2020-05-26
Publication date: 2020-07-31
Anticipated expiration: 2040-05-26
Also published as: CN111474805B

Abstract

The invention discloses an MEMS lens driver, which comprises a supporting frame with an opening at the top, wherein a permanent magnet is arranged at the central part of the inner bottom of the supporting frame, a lens supporting frame is coaxially arranged at the inner upper part of the supporting frame, a spring is connected between the lens supporting frame and the supporting frame, an optical lens is arranged at the central part of the upper part of the lens supporting frame, a driving coil assembly is arranged on the top surface of the lens supporting frame, the driving coil assembly comprises two transverse driving coils, two longitudinal driving coils and an annular driving coil, and the annular driving coil is annularly arranged outside the optical lens along the circumferential direction. The MEMS lens driver of the invention takes electromagnetic drive as a driving mode, can realize the anti-shake of the optical lens X, Y, Z in the three-axis direction, can better adjust the position of the optical lens, realizes the functions of focusing and image collection of the optical lens, and has the advantages of short anti-shake response time, low cost, low driving voltage, large driving displacement, anti-shake, anti-falling and anti-shock functions, simple structure and convenient use.

Description

MEMS lens driver

Technical Field

The invention relates to an MEMS lens driver, and belongs to the technical field of micro-electro-mechanical systems and optics.

Background

The MEMS (Micro Electro-Mechanical System) is a Mechanical device or System developed on the basis of an integrated circuit process, which integrates a Micro sensor, a Micro mechanism, a Micro actuator, a signal processing and control circuit, a communication interface, a power supply and other components into a whole and can perform a certain function. At present, the MEMS technology has been widely applied to the fields of aerospace, automobile industry, biomedical, communications, etc. due to its characteristics of miniaturization, integration, diversification, intellectualization, etc., and is gradually developing toward smaller size. A Micro Actuator (Micro Actuator) is a core component of a MEMS, and is a Micro device capable of outputting physical quantities such as force, moment, displacement, etc., and converting various forms of energy such as light, electricity, heat, etc. into mechanical energy according to a control signal to output. At present, the micro-actuator can be divided into an electrothermal drive, an electromagnetic drive, a piezoelectric drive, a shape memory alloy drive and the like according to an energy conversion form.

MEMS is widely used in smart phones, cameras, scanning mirrors, and other devices having an imaging function, and for the imaging device, the stability of the lens has an important influence on the imaging effect, so that the lens has a good anti-shake function by using a certain measure. The chinese patent "CN 201920281755.1 an optical anti-shake MEMS driver" adopts the sensor shift principle, and controls the movement of the image sensor through the MEMS electrostatic driver installed below the image sensor, and makes it generate translation and rotation to compensate the shake of the mobile phone, but the patent adopts electrostatic driving, the driving voltage is large, the cost is high, and the power consumption is large; the Chinese patent "CN 201910038259.8 an MEMS scanning mirror" adopts piezoelectric drive, and makes the torsion beam drive the reflection mirror surface to deflect by applying opposite voltage, but is limited by the drive mode, and the deflection angle of the mirror surface is influenced; in the Chinese patent 'CN 201910839155.7 MEMS scanning mirror', the movable comb teeth are inclined by applying potential difference between the fixed comb teeth and the movable comb teeth, and the torsion beam drives the mirror surface to deflect.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide a MEMS lens actuator with low cost and low driving voltage, which can prevent lens from shaking.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a MEMS lens driver, includes open-top's braced frame, the central point of braced frame's inside bottom is equipped with the permanent magnet, the coaxial lens support frame that is equipped with in inside upper portion of braced frame, be connected with the spring between lens support frame and the braced frame, the upper portion central point of lens support frame is equipped with optical lens, the top surface of lens support frame is equipped with the drive coil subassembly that can let in forward current or reverse current, the drive coil subassembly includes two symmetric distribution's horizontal drive coil, two symmetric distribution's vertical drive coil and is located the annular drive coil in the middle of horizontal drive coil and vertical drive coil, the optical lens outside is located along the circumferencial direction ring to annular drive coil.

In one embodiment, the center lines of the support frame, the permanent magnet, the lens support frame, the optical lens and the annular driving coil are coincident.

In one embodiment, the transverse drive coils, the longitudinal drive coils, and the annular drive coils are wound in the same direction.

In one embodiment, the drive coil assembly includes a plurality of transverse drive coils, a plurality of longitudinal drive coils, and a plurality of annular drive coils.

In one embodiment, the permanent magnet is provided with a through hole for passing the incident light, at a position facing the optical lens.

In one embodiment, a plurality of springs are connected between the lens supporting frame and the supporting frame, and the plurality of springs are uniformly distributed between the lens supporting frame and the supporting frame.

Compared with the prior art, the invention has the beneficial technical effects that:

the MEMS lens driver of the invention takes electromagnetic drive as a driving mode, and drives the optical lens to move up and down and deflect by changing the magnitude and the direction of current in the driving coil assembly and selectively switching on the transverse driving coil, the longitudinal driving coil and the annular driving coil in the driving coil assembly so as to compensate the shake of the optical lens, thereby realizing the shake prevention of the optical lens X, Y, Z in three-axis directions, better adjusting the position of the optical lens, realizing the functions of focusing and image collection of the optical lens, and having the characteristics of shake prevention, short response time, low cost, low driving voltage and large driving displacement.

Drawings

Fig. 1 is a perspective view of a MEMS lens actuator provided in an embodiment of the present invention;

FIG. 2 is a side view of a MEMS lens actuator provided in an embodiment of the present invention;

FIG. 3 is a top view of a MEMS lens actuator provided in an embodiment of the present invention;

FIG. 4 is a bottom view of a MEMS lens actuator provided in an embodiment of the present invention with the support frame bottom plate removed;

the numbers in the figures are as follows: 1. a support frame; 11. a base plate; 12. a side plate; 2. a permanent magnet; 21. a through hole; 3. a lens support frame; 4. a spring; 5. an optical lens; 6. a drive coil; 61/62, transverse drive coil; 63/64, longitudinal drive coil; 65. an annular drive coil.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and examples.

Examples

As shown in fig. 1 to 4, the present invention provides a MEMS lens actuator, which includes a support frame 1 with an open top, a permanent magnet 2 is arranged at the central part of the inner bottom of the supporting frame 1, a lens supporting frame 3 is coaxially arranged at the inner upper part of the supporting frame 1, a spring 4 is connected between the lens supporting frame 3 and the supporting frame 1, an optical lens 5 is arranged at the central part of the upper part of the lens supporting frame 3, the top surface of the lens holder 3 is provided with a driving coil assembly 6 into which a forward current or a reverse current (not shown) can be introduced, the drive coil assembly 6 includes two symmetrically distributed lateral drive coils 61/62, two symmetrically distributed longitudinal drive coils 63/64, and an annular drive coil 65 positioned intermediate the lateral drive coils 61/62 and the longitudinal drive coils 63/64, the annular drive coil 65 being circumferentially disposed around the exterior of the optical lens 5.

Specifically, the supporting frame 1 with the top opening is composed of a bottom plate 11 and a side plate 12 which surrounds the top of the bottom plate 11 and is perpendicular to the bottom plate 11, in this embodiment, the supporting frame 1 includes a bottom plate 11 and four side plates 12, and both the bottom plate 11 and the side plates 12 are rectangular. Accordingly, the cross section of the lens holder 3 is also rectangular.

The working principle of the MEMS lens driver is as follows:

the permanent magnet 2 is arranged at the central part of the inner bottom of the support frame 1, the lens support frame 3 is coaxially arranged at the inner upper part of the support frame 1, namely the permanent magnet 2 is arranged under the lens support frame 3 and has a distance with the lens support frame 3, the permanent magnet 2 has magnetism all the time, the drive coil assembly 6 arranged on the top surface of the lens support frame 3 generates an induction magnetic field when being electrified, and the drive coil assembly 6 and the permanent magnet 2 generate magnetic interaction, so that forward current or reverse current can be introduced into the drive coil assembly 6, and the drive coil assembly 6 and the permanent magnet 2 generate mutually attracted or mutually repelled acting force (namely Lorentz force, the size of the introduced current determines the size of the induction magnetic field and further determines the size of the Lorentz force); the spring 4 has elasticity, and can provide elastic force for the lens support frame 3 and the optical lens 5 on the lens support frame 3, and elastically deform under the action of Lorentz force, so that the lens support frame 3 connected with the spring and the optical lens 5 on the lens support frame 3 are driven to move up and down and deflect;

referring to fig. 1, the drive coil assembly 6 of the present invention is comprised of two symmetrically distributed transverse drive coils 61/62, two symmetrically distributed longitudinal drive coils 63/64, and an annular drive coil 65 disposed intermediate the transverse drive coils 61/62 and the longitudinal drive coils 63/64, wherein the transverse driving coils represented by 61 and 62 correspond to the positive direction of the X axis and the negative direction of the X axis respectively, the longitudinal driving coils represented by 63 and 64 correspond to the positive direction of the Y axis and the negative direction of the Y axis respectively, and the annular driving coil represented by 65 corresponds to the direction of the Z axis, therefore, when the optical lens 5 is shaken by external interference, the driving coils in the corresponding directions can be closed, and the magnitude and direction of the current can be adjusted, so that the lens support frame 3 is displaced and is shaken against the optical lens 5, and the specific steps are as follows:

in this embodiment, when a forward current is supplied to the driving coil 61/62/63/64/65, the driving coil 61/62/63/64/65 generates an attractive force with the permanent magnet 2;

when the optical lens 5 shakes in the Z-axis direction, namely shakes vertically upwards or vertically downwards, current is introduced into the annular driving coil 65, when the optical lens 5 shakes upwards, forward current is introduced into the annular driving coil 65, the annular driving coil 65 generates an acting force which is mutually attracted with the permanent magnet 2, and the permanent magnet 2 is fixed at the central part of the inner bottom of the supporting frame 1, so that under the acting force, the original stress balance of the spring 4 connected between the lens supporting frame 3 and the supporting frame 1 is damaged by the acting force to generate elastic deformation, the lens supporting frame 3 connected with the spring 4 moves downwards until reaching a new mechanical balance, and the optical lens 5 arranged on the lens supporting frame 3 moves vertically downwards together, so that the shaking of the optical lens 5 vertically upwards is counteracted; on the contrary, when the optical lens 5 shakes downwards, a reverse current is introduced into the annular driving coil 65, and the annular driving coil 65 generates an acting force mutually repelling with the permanent magnet 2, so that the lens supporting frame 3 drives the optical lens 5 to vertically move upwards together, and the shaking of the optical lens 5 vertically downwards is counteracted;

when the optical lens 5 shakes towards the positive direction of the X axis, positive current is introduced into the transverse driving coil 62, the transverse driving coil 62 generates an acting force which is mutually attracted with the permanent magnet 2, and under the acting force and the action of the spring 4, the optical lens 5 arranged on the lens supporting frame 3 deflects towards the negative direction of the X axis to counteract the shaking; on the contrary, when the optical lens 5 shakes in the negative direction of the X axis, a positive current is introduced into the transverse driving coil 61, so that the optical lens 5 arranged on the lens supporting frame 3 deflects in the positive direction of the X axis to counteract the shaking;

similarly, when the optical lens 5 shakes in the positive Y-axis direction, a positive current is applied to the longitudinal driving coil 64, so that the optical lens 5 mounted on the lens holder 3 deflects in the negative Y-axis direction to counteract the shake; on the contrary, when the optical lens 5 shakes towards the Y-axis negative direction, a positive current is introduced into the longitudinal driving coil 63, so that the optical lens 5 arranged on the lens supporting frame 3 deflects towards the Y-axis positive direction to counteract the shaking;

in addition, when the optical lens 5 shakes violently instantaneously, a forward current is simultaneously introduced into five groups of driving coils 61/62/63/64/65 in the driving coil assembly 6, so that the driving coil assembly 6 generates a larger acting force which is mutually attracted with the permanent magnet 2 instantaneously, and the lens support frame 3 and the optical lens 5 arranged on the lens support frame 3 are adsorbed on the permanent magnet 2 instantaneously, thereby playing the roles of preventing falling and vibration.

In the above-mentioned using process, in order to better implement the anti-shake and anti-falling and anti-vibration functions of the optical lens 5, the magnitude and direction of the current flowing into the associated driving coil can be adjusted according to the specific shake condition, therefore, the lens driver of the present invention can drive the optical lens 5 to move up and down and to deflect by changing the magnitude and direction of the current in the driving coil assembly 6 and the selective switch-on of the driving coil 61/62/63/64/65 in the driving coil assembly, so as to compensate the shake of the optical lens 5, thereby implementing the anti-shake of the optical lens 5 in the three-axis direction of X, Y, Z, and also playing the role of anti-falling and anti-vibration for the optical lens 5.

In the invention, the lens driver can realize electromagnetic driving through the permanent magnet 2 and the driving coil assembly 6, the permanent magnet 2 is fixed at the central part of the inner bottom of the supporting frame 1 and keeps unchanged, the lens supporting frame 3, the optical lens 5 and the driving coil assembly 6 arranged on the lens supporting frame 3 move in corresponding directions under the action of the elastic force and the restoring force of the spring 4 and the Lorentz force of an electromagnetic field until reaching a balanced static state, the load of the lens supporting frame 3 is the optical lens 5 and the driving coil assembly 6, the driving coil assembly 6 has light weight and can be ignored, so that the magnitude of the applied current is changed to amplify the moving effect of the optical lens 5, namely, the optical lens 5 can move in a larger distance only by applying a smaller current, the driving displacement is large, the driving consumption is small, and the applied current is small, the driving voltage is low, correspondingly, the load of the driving coil assembly 6 is correspondingly reduced, and further the sensitivity of the lens driver is improved, so that the anti-shaking response time is short; in addition, the permanent magnet 2 is arranged to provide key source power for electromagnetic driving, when the driving coil assembly 6 is switched on to generate an induced magnetic field, the fact that the driver starts to work is indicated, and the stable magnetic field of the permanent magnet 2 provides the condition that the driver moves stably and linearly, so that the optical lens 5 in the driver is ensured to be linear when moving, and a good anti-shake effect is achieved. In the present invention, the current loaded by the driving coil assembly 6 when the optical lens 5 focuses the external light to a point is the working current of the anti-shake focusing of the lens driver.

In this embodiment, the center lines of the support frame 1, the permanent magnet 2, the lens support frame 3, the optical lens 5, and the annular driving coil 65 are overlapped. The two

lateral drive coils

61 and 62 are symmetrically distributed on both sides of the annular drive coil 65, and the two

longitudinal drive coils

63 and 64 are also symmetrically distributed on both sides of the annular drive coil 65. The stability of the whole driver is ensured, and the anti-shake focusing effect of the optical lens 5 is further ensured.

In this embodiment, the transverse driving coil 61/62, the longitudinal driving coil 63/64 and the annular driving coil 65 are wound in the same direction, that is, when the power is turned on, induced magnetic fields (electromagnetic fields) in the same direction are generated, so that the operation is simplified.

In this embodiment, the transverse drive coil 61/62, the longitudinal drive coil 63/64 and the annular drive coil 65 of the drive coil assembly 6 are connected in parallel to facilitate the connection of appropriate drive coils depending on the situation.

Referring to fig. 4, a through hole 21 through which incident light can pass is formed in a portion of the permanent magnet 2 facing the optical lens 5, and the incident light passes through the through hole 21 after passing through the optical lens 5 mounted on the lens holder 3. In this embodiment, the permanent magnet 2 is provided in a ring shape, and a hollow portion of the ring-shaped permanent magnet 2 is the through hole 21.

Be connected with a plurality of springs 4 between lens support frame 3 and braced frame 1, a plurality of springs 4 evenly distributed is between lens support frame 3 and braced frame 1. In this embodiment, referring to fig. 1/3/4, it can be seen that four springs 4 are provided, and the four springs 4 are uniformly and symmetrically disposed between the lens support frame 3 and the support frame 1, so as to effectively ensure the overall balance of the driver, effectively ensure the balance of the elastic force and the restoring force applied by the springs 4 to the lens support frame 3, and further ensure the linearity of the up-and-down movement or the deflection at a certain angle of the lens support frame 3 and the optical lens 5.

It is finally necessary to point out here: the above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A MEMS lens actuator, comprising: including open-top's braced frame, the central point of braced frame's inside bottom is equipped with the permanent magnet, the coaxial lens support frame that is equipped with in inside upper portion of braced frame, be connected with the spring between lens support frame and the braced frame, the upper portion central point of lens support frame is equipped with optical lens, the top surface of lens support frame is equipped with the drive coil subassembly that can let in forward current or reverse current, the drive coil subassembly includes two symmetric distribution's horizontal drive coil, two symmetric distribution's vertical drive coil and the annular drive coil that is located horizontal drive coil and vertical drive coil's centre, the optical lens outside is located along the circumferencial direction ring to annular drive coil.

2. The MEMS lens actuator of claim 1, wherein: the central lines of the supporting frame, the permanent magnet, the lens supporting frame, the optical lens and the annular driving coil are overlapped.

3. The MEMS lens actuator of claim 1, wherein: the winding directions of the transverse driving coil, the longitudinal driving coil and the annular driving coil are the same.

4. The MEMS lens actuator of claim 1, wherein: the transverse driving coil, the longitudinal driving coil and the annular driving coil in the driving coil assembly are connected in parallel.

5. The MEMS lens actuator of claim 1, wherein: the part of the permanent magnet, which is right opposite to the optical lens, is provided with a through hole through which the incident light can pass.

6. The MEMS lens actuator of claim, wherein: a plurality of springs are connected between the lens supporting frame and the supporting frame, and the springs are uniformly distributed between the lens supporting frame and the supporting frame.