Patent Application
20110031822
1. Technical Field
The present disclosure relates to voice coil motors, and particularly, to a voice coil motor for driving a lens.
2. Description of Related Art
Voice coil motors are widely used as actuators for driving lenses in camera modules.
A typical voice coil motor includes a fixing member, a movable member, and a housing shell which houses the fixing member and the movable member therein. The fixing member has a number of permanent magnets mounted thereon, the movable member has a number of coils of wire mounted thereon, and one of the permanent magnets faces one of the coils of wire.
Generally, the magnetic field density is higher at the two ends of the permanent magnet, and the magnetic fields are more spread apart at the middle portion of the permanent magnets. Thus, the magnetic force is stronger at the ends. That is, the magnetic force provided in the middle portion becomes too weak.
What is needed, therefore, is a voice coil motor which can overcome the above shortcoming.
Many aspects of the present voice coil motor can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present voice coil motor. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Embodiments of the present voice coil motor will now be described in detail below and with reference to the drawings.
Referring to
The shell 10 is mounted on the base 50. The shell 10 and the base 50 cooperatively define a housing space or receiving space therein and two openings 110, 510 at the shell 10 and the base 50, respectively, in communication with the housing space or receiving space. The base 50 further includes four engaging holes 520 formed at four corners thereof. The shell 10 includes a top cover 11 and four side covers 12. The top cover 11, the side covers 12, and the base 50 cooperatively enclose the housing space. The housing space is configured for receiving the fixing member 30, movable member 20, first elastic member 40a and second elastic member 40b therein.
The fixing member 30 includes a square bracket 31 and a first magnetic member in the form of four coils of wire 32. The bracket 31 is made up of eight horizontal bars 320 and four vertical bars 330. The vertical bars 330 extend through the horizontal bars 320 and thus form four protrusions 350 on the top of the bracket 31 and four protrusions 360 on the bottom of the bracket 31. The horizontal bars 320 and the vertical bars 330 cooperatively define a through hole 310 therein and four side retaining spaces 321 in communication with the through hole 310. The coils of wire 32 (the first magnetic member) are retained in the side retaining spaces 321, respectively.
The movable member 20 is movably received in the through hole 310 of the bracket 31. The movable member 20 includes a retainer 21 and four magnetic members 22. The retainer 21 defines a through hole 210 therein, and includes a quadrate first tab 230 and a quadrate second tab 240 extending from a top surface and a bottom surface thereof, respectively. The retainer 21 further includes four protrusions 220 extending from a top thereof, and four protrusions (not labeled) extending from a bottom thereof. The magnetic members 22 are mounted on an outer wall of the retainer 21, and sandwiched between the first and second tabs 230, 240.
Each of the magnetic members 22 includes a first permanent magnet 221 and a second permanent magnet 222 abutting against the first permanent magnet 221. Referring also to
It is understood that the magnetic members 22 can be mounted to the bracket 31, and the coils of wire 32 can be mounted to the retainer 21, i.e., the positions of the magnetic members 22 and the coils of wire 32 can switch place with each other.
The first and second elastic members 40a, 40b are located on a top and a bottom of the fixing member 30 and the movable member 20, respectively, and are structured and arranged for connecting the movable member 20 to the fixing member 30. Each of the first and second elastic members 40a, 40b is square and includes a central elastic portion 412 attached to the retainer 21 and a peripheral portion 411 fixed to the bracket 31. A number of L-shaped cutouts 413 are located between the peripheral portion 411 and the central elastic portion 412 to provide elasticity for the central elastic portion 412. Each of the peripheral portions 411 includes four through holes 420 at four corners thereof, respectively. Each of the central elastic portions 412 includes four through holes 430 at four corners thereof, respectively.
The protrusions 350, 360 of the bracket 31 engage in and extend through the through holes 420 of the peripheral portions 411 of the first and second elastic members 40a, 40b, respectively, such that the first and second elastic members 40a, 40b are fixed to the bracket 31. The protrusions 360 are further engaged in the engaging holes 520 of the base 50. The protrusions 220 at the top of the retainer 21 and the protrusions 220 at the bottom of the retainer 21 engage in and extend through the through holes 430 of the central elastic portions 412 of the first and second elastic members 40a, 40b, such that the retainer 21 is attached to the central elastic portions 412 of the first and second elastic members 40a, 40b. The central elastic portions 412 of the first and second elastic members 40a, 40b provide elasticity for the retainer 21, thereby providing activity space for the retainer 21. The protrusions 220 and the through holes 430 ensure the movement direction does not deviate from a central axis of the retainer 21.
A lens or a lens group can be received in the through hole 210 of the retainer 21, such that the lens or the lens group can be driven.
It is understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments and methods without departing from the spirit of the disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200910305302.9 | Aug 2009 | CN | national |
