KR20110001232U - Compact auto focus lens module with piezoelectric actuator - Google Patents

Abstract

The compact autofocus lens module according to the present invention with a piezoelectric actuator comprises a lens barrel having a piezoelectric actuator, an elastic element, at least two guiding fixtures and a set of optical lenses. The elastic force of the elastic element causes friction between the lens barrel and the piezoelectric actuator. When a voltage is applied, the lens barrel is driven by the movement of the piezoelectric actuator to move along the optical axis under the guidance of the guide fixture. Due to the smaller components, small size and light weight, the present invention can be applied to miniaturizing the autofocus lens module to achieve fast movement, stable focusing and reduced tilting.

Description

Compact Auto Focus Lens Module with Piezoelectric Actuator {COMPACT AUTO FOCUS LENS MODULE WITH PIEZOELECTRIC ACTUATOR}

The present invention relates to a compact autofocus lens module having a piezoelectric actuator, and more particularly, to the displacement and friction caused by the deformation of the piezoelectric actuator for focusing, when the movement of the optical lens set is adjusted. It relates to an autofocus lens module, characterized in that controlled by.

Digital cameras or mobile phone cameras include a lens module that drives the optical lens set to move along the optical axis to achieve autofocus and / or zoom in / zoom out. . One way of moving the optical lens set is by a voice coil motor (VCM). In order to drive the optical lens set to move along the optical axis, after a current is applied to the coil, a driving force is generated in the electromagnetic field formed by the permanent magnet. The design as described above can reduce the size of the lens module, so as disclosed in US Patent US 2008/0013196, US 6,594,450, US 7,145,738, Taiwan Patent TW M317027, Japanese Patent JP 3124292, JP 3132575, etc. It has been widely applied to mobile phones or web cameras.

The ultrasonic motor USM is a kind of electric motor formed from ultrasonic vibration of a piezoelectric material that deforms when a voltage is applied. As disclosed in the prior art, such as US patents US 2009/0153987, US 2008/0297923, US 2008/0174889 and the like, ultrasonic motors with a friction drive design move in a rotary or linear manner. Referring to FIG. 1, as disclosed in US 2008/0246353, the ultrasonic motor is applied to an autofocus lens module. A piezoelectric actuator 902 is disposed on a fixed element 9091 and is connected to the lens drive element 9092 by a connector 9021 to generate a piezoelectric driving force. Coil element 907 also generates electromagnetic forces with magnet element 908. By the balance between the piezoelectric drive force and the electromagnetic force, the lens drive element 9902 and lens set 901 are driven to move along the axis 904 for focusing.

Referring to FIG. 2, as disclosed in US Pat. No. 7,480,109, US 2008/0085110, etc., the piezoelectric driving optical lens module includes a guiding rod 904 having a friction surface 9021 and a lens barrel for focusing. a piezo actuator 902 mounted to the elastic element 903 to drive the barrel 9011 and the lens set 9012 to move along the guide pin 9043 by the guide slot 9042. do.

Referring to FIG. 3, another ultrasonic motor type autofocus lens module disclosed in US 2008/0231970 includes a leaf spring 903. An elastic force from the leaf spring 903 against the two piezoelectric actuators 902 creates a friction force between the guide rail 904 and the lens barrel 901. However, the leaf spring has a complicated structure and a large volume condition, and occupies a large space, and thus is not suitable for the compact lens module.

Apparatuses for stably moving the lens module without tilting are disclosed in US Pat. No. 2008/0144201, Japanese Patent JP 2004020935, and the like, the apparatuses comprising the housing of the lens module and the lens barrel to stabilize the lens barrel. It includes a guide rod disposed between. In the case of US 2007/0153404, a rail is used. Referring to Taiwan Patent TW I265357, two sets of piezoelectric actuators are disposed at the edges of the lens barrel so that the movement of the lens barrel is made stable. However, conventional ultrasonic motors for moving the lens barrel are difficult to be applied to a small autofocus lens module because of the disadvantages of complicated structure, high cost or large volume in the design of the guide rod or friction generation. Therefore, there is a need for the development of a driving member having a high reliability and stability structure that replaces conventional friction generating methods. In addition, the requirements of simple structure, high precision, fast focusing and reduced tilting need to be met.

The objective of the present invention is to meet the requirements of simple structure, high precision, fast focusing and reduced tilting, and to have a highly reliable and stable structure, which can be applied to a wider range. To provide.

The compact auto focus lens module according to the present invention for achieving the above object includes a piezoelectric actuator, a lens module and a frame. The piezoelectric actuator and the lens module are mounted to the frame. The lens module includes a lens barrel, an elastic element and at least two guiding fixtures in which an optical lens set is fixed. The elastic element disposed between the lens barrel and the piezoelectric actuator includes an elastic member and a metal member. The elastic force of the elastic element causes friction at the interface between the elastic element and the piezoelectric actuator. The guide fixture is formed by a guide slot and a guide pin corresponding thereto. The guide slot is provided in the lens barrel. The lens module slides in the frame under the guidance of the guide pin. Upon application of voltage, the lens barrel is driven by the piezoelectric actuator to move along the optical axis of the frame for focusing.

For wider application of the compact autofocus lens module according to the present invention, a coil spring may be used as the elastic member. Furthermore, in order to minimize the volume, the elastic member may be an elastic pad made of rubber or foam material. The elastic member may also be a leaf spring.

The compact auto focus lens module according to the present invention satisfies the requirements of simple structure, high precision, fast focusing and reduced tilting, has a structure of high reliability and stability, has fewer components, smaller size and Due to the light weight, there is an advantage that it can be widely applied to small optical systems.

Other advantages and features of the present invention will become more apparent from the claims in the embodiments and the utility model registration claims described in detail below with reference to the accompanying drawings.

1 is a perspective view of a conventional auto focus lens module having a VCM (Voice Coil Motor) and a piezoelectric actuator.
2 is an exploded perspective view of a conventional auto focus lens module having another piezoelectric actuator.
3 is a perspective view of another conventional autofocus lens module having two piezoelectric actuators.
4 is a perspective view of one embodiment according to the present invention.
5 is an exploded perspective view of an embodiment according to the present invention.
6 is another exploded perspective view of an embodiment according to the present invention.
7 is an exploded perspective view of another embodiment according to the present invention.
8 is an exploded perspective view of yet another embodiment according to the present invention.

First Embodiment

4 to 6, the compact autofocus lens module 1 according to the present invention having a piezoelectric actuator includes a piezoelectric actuator 31, a lens module 11, and a frame 12. The piezoelectric actuator 31 and the lens module 11 are mounted to the frame 12. The electrode 34 of the piezoelectric actuator 31 is connected to a voltage controller (not shown) and fixed to the frame 12. In general, due to the converse piezoelectric effect of the piezoelectric material, the application of the electric field causes mechanical deformation in the material and further leads to displacement. Depending on the motion of the piezoelectric material, the piezoelectric actuators are classified as follows: (1) linear vertical motion: a single layer having the advantages of high strength and large axial thrust force. -layer type and multi-layer type. (2) Curved horizontal motion: Includes unimorph type and bimorph type. The piezoelectric actuator moving in this way has a large displacement. In this embodiment, a bimorph piezoelectric material with curved horizontal motion is used. When the voltage controller outputs a voltage, a resonant frequency, and a phase angle and transmits the voltage to the piezoelectric actuator 31 through the electrode 34, the piezoelectric actuator 31 generates waveform vibrations, and the lens is subjected to friction. The module 11 is driven to move back and forth.

The lens module 11 consists of a lens barrel 21, an optical lens set 22, an elastic element 30 and two guiding fixtures 23, 23 ′. The optical lens set 22 is fixed to the lens barrel 21 and has at least one optical lens for concentrating light on an image sensor (not shown). In the case of the autofocus lens module 1, the lens barrel 21 moves along the optical axis, and the optical lens set 22 also moves together with the movement of the lens barrel 21, thereby providing various imaging effects ( The distance between the optical lens set 22 and the image sensor can be varied to have imaging effects. However, the lens barrel 21 requires stability without tilt for the optical imaging effect. This embodiment includes two guide fixtures 23 and 23 ', each having corresponding guide slots 211/211' and guide pins 35/35 '. The guide slots 211/211 ′ are provided in the lens barrel 21. The lens barrel 21 is provided by guide pins 35/35 ′ connecting the guide slots 211/211 ′ of the lens barrel 21 and a fixing ring 121 of the frame 12. ) Is installed in the frame 12 to be movable. Accordingly, the lens module 11 may move in the vertical direction along the guide pins 35/35 ′ in the frame 12.

The elastic element 30 is disposed between the lens barrel 21 and the piezoelectric actuator 31. By the arrangement described above, the autofocus lens module 1 becomes more compact, a problem of the prior art, that is, a disadvantage of the conventional lens module having a large volume caused by the leaf springs around the lens barrel. This is solved. In this embodiment, the elastic element 30 is formed by the elastic member 32 and the metal member 33. The elastic member 32 may be a pad made of elastic rubber or a foam material that generates an elastic force. As shown in FIG. 6, the elastic member 32 is an elastic pad 321 made of ethylene-propylene rubber (EPDM), but is not necessarily limited to the aforementioned materials. One end of the elastic pad 321 is bonded to one side of the lens barrel 21 designed as a flat surface for the convenience of adhesion. The other end of the elastic pad 321 is adhered to the metal member 33 to allow the metal member 33 to press the piezoelectric actuator 31 by the elastic force of the elastic pad 321. And friction occurs at the interface between the metal member 33 and the piezoelectric actuator 31. When the voltage controller outputs a voltage, a resonant frequency, and a phase angle and transmits the voltage to the piezoelectric actuator 31 by the electrode 34, the piezoelectric actuator 31 generates waveform vibrations to generate the vibrations through friction. Transfer to the lens barrel 21. This is because the lens barrel 21 is guided along the optical axis under the guidance of the guide fixtures 23 and 23 'so as to prevent tilting in the frame 12 by the movement of the piezoelectric actuator 31. It means to move. Therefore, the focus is adjusted by the movement of the lens barrel 21 moving back and forth in a straight line.

Compared with the conventional lens modules, the above-described embodiment allows the lens module 11 to move stably and quickly, and the tilting of the lens module 11 is reduced. In addition, the autofocus lens module 1 is minimized for use in small optical systems.

Second Embodiment

4 and 7, this embodiment is similar in structure to the first embodiment described above, except that the elastic member 32 of the elastic element 30 is the coil spring 322. One end of the coil spring 322 is bonded to one side of the lens barrel 21, the other end is bonded to the metal member 33. By the spring tension of the coil spring 322, the metal member 33 presses the piezoelectric actuator 31, and at the interface between the metal member 33 and the piezoelectric actuator 31. Create friction.

Third Embodiment

4 and 8, this embodiment is similar in structure to the above-described embodiments, except that the elastic member 32 of the elastic element 30 is a leaf spring 323. One end of the leaf spring 323 is bonded to one side of the lens barrel 21, the other end is bonded to the metal member 33. By the recovery force of the leaf spring 323, the metal member 33 presses the piezoelectric actuator 31, thereby friction on the interface between the metal member 33 and the piezoelectric actuator 31. To produce this.

Those skilled in the art will be able to easily envision additional advantages and modifications. Accordingly, the present invention is not limited to the individual specific embodiments described above, and does not depart from the spirit or scope of the inventive concept as a whole, as defined by the claims in the appended Utility Model Claims and their equivalents. Various modifications can be made.

Claims (5)

In a small auto focus lens module having a piezoelectric actuator,
The small auto focus lens module
frame;
A piezoelectric actuator provided in the frame and used to generate vibration; And
It includes a lens module provided in the frame,
The lens module
Lens barrels;
An optical lens set provided in the lens barrel;
An elastic element disposed between the lens barrel and the piezoelectric actuator, the elastic element including an elastic member and a metal member; And
A two guiding fixture configured to slidably fix the lens barrel to the frame such that the lens module moves in a vertical direction along an optical axis in the frame,
The elastic member fixed between the metal member and the lens barrel is used to press the metal member toward the piezoelectric actuator so that the piezoelectric actuator and the metal member contact each other.
When the voltage is applied to the piezoelectric actuator, the lens barrel is driven by friction between the piezoelectric actuator and the metal member to move along the optical axis in the frame. The method of claim 1,
Each guide fixture includes a guiding slot and a guide pin corresponding thereto, wherein the guide slot is provided in the lens barrel, and the lens barrel is slidably moved by the guide pin. Small auto focus lens module is fixed to the frame to move the lens module in the vertical direction along the optical axis in the frame under the guide pin guide. The method of claim 1,
Small auto focus lens module, characterized in that the elastic member of the elastic element is an elastic pad made of rubber or foam material. The method of claim 1,
Small auto focus lens module, characterized in that the elastic member of the elastic element is a coil spring or a leaf spring (leaf spring). The method of claim 1,
And said elastic member is adhered between said metal member and said lens barrel.

Images