KR200460569Y1 - Auto focus lens module with piezoelectric actuator - Google Patents

Abstract

The autofocus lens module according to the present invention having a piezoelectric actuator includes a piezoelectric actuator, a tangent thrust element, a sliding fixture, a metal member, a guiding fixture, and a lens barrel. The tangential thrust generated from the tangential thrust element along the outer edge of the lens barrel creates friction between the lens barrel and the piezoelectric actuator. When a voltage is applied to the piezoelectric actuator, the lens barrel is driven by the piezoelectric actuator and driven to move along the optical axis under the guidance of the guide fixture for focus adjustment. Due to the smaller components, small size and light weight, the present invention can be applied to miniaturizing the autofocus lens module to achieve the effects of fast movement, stable focusing and reduced tilting.

Description

AUTO FOCUS LENS MODULE WITH PIEZOELECTRIC ACTUATOR}

The present invention relates to an autofocus lens module having a piezoelectric actuator, and more particularly, to an autofocus lens module having a piezoelectric actuator for driving an optical lens set.

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 903 has a complicated structure and a large volume condition and occupies a large space, and thus is not suitable for a 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 object of the present invention is to meet the requirements of simple structure, high precision, fast focusing and reduced tilting, and to provide an autofocus lens module that has a structure with high reliability and stability, which can be applied to a wider range. It is.

An autofocus 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 having a set of optical lenses fixed therein, a tangent thrust element, a guiding fixture, a sliding fixture, and a metal member. The metal member is fixed to the surface of the lens barrel and in contact with the piezoelectric actuator. The guide fixture is formed by guide slots and guide pins corresponding to each other. The guide slot is provided in the lens barrel. The lens module slides along an optical axis in the frame under the guidance of the guide pin. The sliding fixture includes a slide slot and a slide rod corresponding to each other. The lens barrel moves along the optical axis through the slide rod. The tangential thrust element is disposed outside of the lens barrel and has a plurality of balls and springs corresponding respectively to the plurality of balls. By the elastic force of the spring, the ball generates tangential thrust along the outer edge of the lens barrel, causing friction at the interface between the metal member and the piezoelectric actuator. When a voltage is applied to the piezoelectric actuator, the lens module is driven by the piezoelectric actuator so as to move along the optical axis in the frame for focusing.

For wider application of the autofocus lens module according to the present invention, the tangential thrust element may comprise two permanent magnets and a push board. The push board is disposed at one end of one of the two permanent magnets so as to contact the slide rod of the sliding fixture. A force for pressing the push board is generated by the repulsive force between the same poles of the two permanent magnets, and further, a tangential thrust is generated along the outer edge of the lens barrel, thereby forming a gap between the metal member and the piezoelectric actuator. Allow friction to form at the interface. When a voltage is applied to the piezoelectric actuator, the lens barrel is driven by the piezoelectric actuator to drive along the optical axis in the frame for focusing.

The autofocus lens module according to the present invention satisfies the requirements of simple structure, high precision, fast focusing and reduced tilting, has a structure with high reliability and stability, and has fewer components, smaller size and light weight. This has the 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 another exploded perspective view of an embodiment according to the present invention.
8 is an exploded perspective view of another embodiment according to the present invention.
9 is another exploded perspective view of another embodiment according to the present invention.

≪ Embodiment 1 >

4 to 7, the 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 includes a lens barrel 21, an optical lens set 22, a tangent thrust element 36, a metal member 33, a guiding fixture 23 and a sliding fixture. fixture: 24). The optical lens set 22 is fixed to the lens barrel 21 and is formed by at least one optical lens for concentrating light on an image sensor (not shown).

The metal member 33 is fixed to the surface of the lens barrel 21 and is in contact with the piezoelectric actuator 31. The guide fixture 23 is formed by a guide slot 211 and a guide pin 35 corresponding to each other. 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 a guide fixture 23 and a sliding fixture 24. The guide fixture 23 comprises at least one guide slot 211 and a guide pin 35 corresponding thereto, both parallel to the optical axis. The guide slot 211 is provided in the lens barrel 21. By the guide pin 35 connecting the guide slot 211 of the lens barrel 21 and the fixing ring 121 of the frame 12, the lens barrel 21 is movable to the frame. It is installed in the fixing ring 121 of (12). The sliding fixture 24 is formed by a slide slot 212 and a slide rod 37 corresponding thereto, both of which are parallel to the optical axis. The slide slot 212 is provided in the lens barrel 21 and slides up and down along the slide rod 37. By the guide fixture 23 and the sliding fixture 24, the lens module 11 can stably move up and down along the guide pin 35 and the slide rod 37 in the frame 12. Will be.

The tangential thrust element 36 is disposed outside of the lens barrel 21, one end surface of which leans against the slide rod 37, and the other end surface of which is fixed to an inner surface of the frame 12. By making the autofocus lens module 1 more compact, the problem of the prior art, that is, the disadvantage of the conventional lens module having a large volume caused by the leaf springs around the lens barrel, is eliminated. . The tangential thrust element 36 consists of four balls 361 symmetrically arranged and four springs 362 respectively corresponding to them. By the elastic force of each spring 362, such as a compression spring, the balls 361 are pushed to move forward and are leaned against the slide rod 37. Accordingly, the elastic force is transmitted to the slide rod 37 and the lens barrel 21 to generate tangential thrust along the outer edge of the lens barrel 21. Therefore, the lens barrel 21 presses the piezoelectric actuator 31 by the aforementioned tangential thrust. Further, the use of the balls 361 is to reduce friction and wear of the sliding fixture 24 with the slide rod 37.

The metal member 33 is fixed to one surface of the lens barrel 21 and is in contact with the piezoelectric actuator 31. By the tangential thrust of the tangential thrust element 36, friction is formed between the metal member 33 and the piezoelectric actuator 31. When the voltage controller outputs a voltage, a resonant frequency, and a phase angle, all of which are transmitted to the piezoelectric actuator 31 by the electrode 34, the piezoelectric actuator 31 generates waveform vibrations to friction the vibrations. The lens module 11 is transmitted through the lens module 11, and the lens module 11 moves forward / backward 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

8 and 9, this embodiment has a structure similar to that of the first embodiment described above. However, in this embodiment, the difference is that the tangential thrust element 36 includes two permanent magnets 363 and 364 and a push board 365. The push board 365 made of metal is disposed at one end of the permanent magnet 364 and contacts the slide rod 37 of the sliding fixture 24. In order to reduce friction and wear between the push board 365 and the slide rod 37, four knobs are arranged on the surface of the push board 365. There is no limitation on the material and shape of the push board 365. Both the slide rod 37 and the lens barrel 21 are made of non-magnetic conducting material. The two permanent magnets 363 and 364 are configured such that the same poles (N poles in this embodiment) are joined so as to face each other and push each other out so that they are tangential along the outer edge of the lens barrel 21. Thrust is generated. Therefore, the lens barrel 21 presses the piezoelectric actuator 31 by the aforementioned tangential thrust. In other words, the repulsive force between the same poles of the two permanent magnets 363 and 364 is used as thrust to propel the slide rod 37, so that the slide rod through the balls 361 in the above-described embodiment. Replaces the elastic force from the spring 362 used as thrust to propel 37.

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 (3)

In the auto focus lens module having a piezoelectric actuator,
A piezo actuator, a lens module and a frame,
The piezoelectric actuator and the lens module are mounted to the frame;
The piezoelectric actuator generates vibrations transmitted through friction to drive the lens module for focusing and to move along an optical axis;
The lens module includes a lens barrel having a set of optical lenses fixed therein, a tangent thrust element, a guiding fixture, a sliding fixture, and a metal member;
The metal member urges the piezoelectric actuator by tangential thrust generated from the tangential thrust element, causing sliding friction on the interface between the metal member and the piezoelectric actuator;
The guide fixture is formed by guide slots and guide pins parallel to and corresponding to the optical axis, the guide slots are provided in the lens barrel, and the lens barrel slides in the frame under the guidance of the guide pins so that the lens Cause the module to move up and down along the optical axis in the frame via the guide pin;
The sliding fixture includes a slide slot and a slide rod parallel to and corresponding to the optical axis, wherein the slide slot is provided in the lens barrel to move the lens barrel along the optical rod through the slide rod;
The tangential thrust element disposed outside of the lens barrel generates tangential thrust along the outer edge of the lens barrel, causing friction at the interface between the metal member and the piezoelectric actuator;
When a voltage is applied to the piezoelectric actuator, the lens barrel is driven by the piezoelectric actuator so as to move along the optical axis in the frame under the guidance of the guide fixture and the sliding fixture for focus adjustment. Focus lens module. The method of claim 1,
The tangential thrust element has a plurality of balls and springs corresponding to the plurality of balls, respectively, and the plurality of balls are reclined to the slide rod of the sliding fixture while being pressed to move forward by the elastic force of the springs, respectively. And the ball generates tangential thrust along the outer edge of the lens barrel by the elastic force of the spring. The method of claim 1,
The tangential thrust element includes two permanent magnets and a push board, wherein the push board is disposed at one end of either of the two permanent magnets so as to lean against the slide rod of the sliding fixture, and the two Auto-focus lens module, characterized in that it is elastically pressed by the repulsive force of the same pole of the two permanent magnets to generate a tangential thrust along the outer edge of the lens barrel.

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