Protecting structure for movable mechanism in a miniature lens

A protecting structure for movable mechanism in a miniature lens is mounted in a housing of a focusing mechanism of the miniature lens and includes an upper cover defining a central opening and fixed in the housing; a lens holder for holding a lens therein; at least one elastic member connecting the lens holder to the upper cover, so that the lens holder is suspended in the housing and axially displaceable forward and rearward to achieve the purpose of focusing; and at least one protective member being received in the central opening of the upper cover to locate outside the elastic member relative to the lens holder for restricting the lens holder from moving laterally, and limiting a torsion force produced at the time of screwing the lens into the lens holder, so as to protect the elastic member against deformation due to the torsion force.

FIELD OF THE INVENTION

The present invention relates to a protecting structure for movable mechanism in a miniature lens, and more particularly to a structure for protecting elastic members in a miniature lens focusing driving mechanism against deformation.

BACKGROUND OF THE INVENTION

With the advancement in scientific technologies and the modularization and miniaturization of camera lens, it is now possible to produce digital cameras having a very small volume, and most of currently available mobile phones are provided with the function of a digital camera. In a miniature lens, there are many different auto-focusing driving mechanisms. Among others, voice coil motor (VCM) is the currently most widely adopted auto-focusing driving mechanism. The VCM has the advantages of small volume, low power consumption, accurately actuated displacement, and cost-effective, and is therefore very suitable for short-distance driving in miniature lens auto-focusing.

FIG. 1is an exploded perspective view showing that a conventional movable lens focusing mechanism includes an upper cover10, a lower cover11, a lens holder12, and a an outer frame13being provided at four inner wall surfaces with a magnet14each. The lens holder12is internally provided with screw threads15for a lens16to screw thereinto. A winding17is wound around the lens holder12. The lens holder12is supported by an upper plate spring18and a lower plate spring19to be axially movably located at a center in the outer frame13and surrounded by the four magnets14. When the winding17is supplied with an amount of electric current to thereby produce a magnetic field polarity, the lens holder12and the four magnets14mutually repulse or attract, bringing the lens holder12and accordingly, the lens16to displace for focusing.

When the lens16is being screwed into the lens holder12, a torsion force is produced and applied to the lens holder12. Since the upper and the lower plate spring18,19connected to and supporting the lens holder12have a relatively small thickness, which is generally as small as 0.06 cm, and include relatively thin elastic bendable portions, as shown inFIG. 2, the two plate springs18,19tend to deform or even break due to the torsion force produced at the time the lens16is screwed into the lens holder12.

To enable a movable lens focusing mechanism with low power consumption and quick displacement, the elastic members for supporting the lens holder12have been designed to be elastically movable in an axial direction without any elastic protection in lateral directions. Under this condition, a lens just could not afford to fall because a big impact due to falling would cause the lens to displace laterally and result in damage of the elastic members. That is, the lens would become damaged or useless due to lack of elastic protection in the lateral directions.

It is therefore tried by the inventor to develop a structure for protecting the elastic members in the miniature lens against deformation.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a protecting structure for movable mechanism in a miniature lens, so that elastic members in a movable miniature lens focusing mechanism are protected against deformation.

To achieve the above and other objects, the protecting structure for movable mechanism in a miniature lens according to the present invention is mounted in a housing of a miniature lens focusing mechanism, and includes an upper cover, a lens holder, at least one elastic member, and at least one protective member. The lens holder is configured to hold a lens therein. The at least one elastic member connects the lens holder to the upper cover, so that the lens holder is supported by the elastic member to suspend in the housing and is axially displaceable forward or rearward for focusing. The protective member is located outside the elastic member relative to the lens holder and received in a central opening of the upper cover for restricting the lens holder from displacing laterally, and limiting the torsion force produced at the time of screwing the lens into the lens holder, so as to protect the elastic member against deformation.

In the present invention, the upper cover is provided with at least one notch, and the protective member is provided with at least one tongue corresponding to the notch on the upper cover. The protective member is received in the central opening of the upper cover with the at least one tongue engaged with the at least one notch, so as to limit an extent within which the elastic member can be turned or horizontally moved.

DETAILED DESCRIPTION OF THE INVENTION

Please refer toFIG. 3that is an exploded perspective view of a protecting structure for movable mechanism in a miniature lens according to the present invention mounted in a housing50of a focusing mechanism of the miniature lens. The housing50consists of an upper case51and a base52, and the present invention is received in the upper case51. As shown, the protecting structure of the present invention includes an upper cover30, a protective member31, a first elastic member32, a frame33, a plurality of magnetic elements34, a winding35, a lens holder36, and a second elastic member37. The lens holder36is a hollow ring member defining a through hole40, on a peripheral wall thereof screw threads41are provided, so that a lens39may be correspondingly screwed into the lens holder36.

FIG. 4is an assembled perspective view ofFIG. 3with the lens39and the upper case51omitted therefrom. As shown, the upper cover30defines a central opening, along a peripheral edge of which at least one notch42is provided. The first elastic member32and the second elastic member37also have a central opening each, and are used to support the lens holder36in a suspended state. More specifically, the lens holder36is connected to the upper case30via the first elastic member32, and to the base52via the second elastic member37.

The winding35is wound around the lens holder36. The frame33is located around the winding35. The magnetic elements34are permanent magnets fixed to a wall of the frame33. When an amount of electric current is supplied to the winding35to produce a magnetic field polarity, the lens holder36and the magnetic elements34mutually repulse or attract, bringing the lens holder36and accordingly, the lens39to axially displace forward or rearward for focusing. With the first and the second elastic member32,37, the lens holder36supported thereon is allowed to elastically return to an original position in the frame33. The base52is a hollow structure having an inner contour corresponding to an outer contour of the lens holder36, so that the lens holder36could be received in the base52.

The protective member31has a central opening and is made of a rigid material, such as a metal sheet or a plastic sheet. The protective member31is located on or around the first elastic member32, and received in the central opening of the upper cover30with a clearance as small as 0.12 cm left between the protective member31and the upper cover30. The protective member31is provided along its peripheral edge with at least one tongue43corresponding to the at least one notch42on the upper cover30. The protective member31is fixed to the upper cover30through engagement of the at least one tongue43with the at least one notch42, so as to limit the elastic members32,37to turn or laterally displace only within the range of 0.12 cm.

FIG. 5is a cutaway view showing the position of the protective member31relative to the upper cover30and the first elastic member32. To mount the lens39in the lens holder36, the lens39must be turned to screw into the through hole40defined in the lens holder36. At this point, a torsion force is produced and applied to the upper and the lower elastic members32,37with which the lens holder36is supported. However, since the protective member31is associated with the upper cover30through engagement of the at least one tongue43with the at least one notch42, an extent by which the protective member31can be turned is limited. Moreover, since the protective member31has only limited range of turning, it further limits the torsion force of the elastic member32, protecting the elastic member32against deformation due to the torsion force produced at the time of screwing the lens39into the lens holder36.

With the above arrangements, the protective member31can only axially move forward and rearward while its lateral movement is limited due to the engaged tongues43and notches42. Moreover, the protective member31may have a thickness up to 0.25 cm, and this thickness is high enough for the protective member31to absorb an impact caused by a fallen camera. Therefore, the protective member31functions to limit the lateral displacement and accordingly, the deformation of the first elastic member32possibly caused by a big impact from a fallen camera, and further protect the lens39against adverse influences by the impact.

In brief, in the protecting structure for movable mechanism in a miniature lens according to the present invention, the protective member31is provided on or around the first elastic member32to limit both the torsion force and the lateral movement of the lens39, so that the first elastic member32is effectively protected against deformation.