DRIVING MECHANISM

A driving mechanism for moving an optical unit is provided, including a fixed part, a movable part, and a driving unit. The movable part is connected to the optical unit and the fixed part, and the movable part is movable relative to the fixed part. The driving unit is configured to drive the movable part and the optical unit to move relative to the fixed part.

BACKGROUND OF THE INVENTION

Field of the Invention

The application relates in general to a driving mechanism, and in particular, to a variable aperture (VA) mechanism.

Description of the Related Art

As technology has developed, it has become more common to include image-capturing and video-recording functions into many types of modern electronic devices, such as smartphones and digital cameras. These electronic devices are used more and more often, and new models have been developed that are convenient, thin, and lightweight, offering more choices to consumers.

Electronic devices that have image-capturing or video-recording functions normally include an optical module, and require functions of using an optical element driving mechanism to adjust the size of an aperture in order to change amount of light entering the module. Light may pass through the optical module and the optical element driving mechanism and may form an image on an optical sensor. However, the trend in modern mobile devices is to have a smaller size and a higher durability. As a result, how to effectively reduce the size of the optical module and how to increase its durability has become an important issue.

BRIEF SUMMARY OF INVENTION

In view of the aforementioned problems, the object of the invention is to provide a driving mechanism for moving an optical unit. The driving mechanism includes a fixed part, a movable part, and a driving unit. The movable part is movably connected to the optical unit and the fixed part. The driving unit is configured to impel the movable part and the optical unit relative to the fixed part.

In some embodiments, the driving unit comprises an SMA element that has a first length when the movable part is in a first position relative to the fixed part, and when a current signal is applied to the SMA element, the SMA element shrinks from a first length to a second length and impels the movable part from the first position to a second position relative to the fixed part.

In some embodiments the driving mechanism further includes a slider movably disposed on the movable part and connected to the SMA element, wherein the fixed part forms a longitudinal guiding structure, the slider contacts a first end of the guiding structure when the movable part is in the first position relative to the fixed part, and when the slider is impelled by the SMA element along the guiding structure from the first end to a second end of the guiding structure, the movable part is pushed by the slider from the first position to the second position.

In some embodiments, the guiding structure comprises a longitudinal slot.

In some embodiments, the fixed part has a polygonal shape, and a tilt angle is formed between the guiding structure and a side of the fixed part.

In some embodiments, the tilt angle is 45 degree.

In some embodiments, the movable part has an annular structure that forms a longitudinal rail, and the slider extends through the rail to the guiding structure.

In some embodiments, the rail extends in a first direction, and the guiding structure extends in a second direction that is not parallel to the first direction.

In some embodiments, the second direction is not perpendicular to the first direction.

In some embodiments, an included angle is formed between the first and second directions, and the included angle ranges from 20 degree to 70 degree.

In some embodiments, the driving mechanism further includes a housing and a smooth element, wherein the movable part and the fixed part are received in the housing, and the smooth element is disposed on an inner surface of the housing and faces the slider.

In some embodiments, the fixed part has a polygonal shape, and the slider is located close to a corner of the fixed part.

In some embodiments, the driving mechanism further includes a bottom plate that forms a longitudinal cavity, wherein the fixed part is located between the movable part and the bottom plate, and the slider extends through the movable part and the fixed part to the cavity.

In some embodiments, the longitudinal cavity is parallel to the guiding structure.

In some embodiments, the driving mechanism further includes a sensing assembly disposed on the movable part and the bottom plate for measuring the displacement of the movable part relative to the fixed part.

In some embodiments, the driving mechanism further includes a resilient element disposed on the fixed part, wherein the slider is located between the resilient element and the SMA element.

In some embodiments, the driving mechanism further includes a magnetic element disposed on the fixed part, wherein the SMA element is located between the magnetic element and the slider.

In some embodiments, the optical unit includes a first blade and a second blade pivotally connected to the fixed part for partially covering an opening of the fixed part, light enters the driving mechanism and propagates through the opening along an entry direction, and the first and second blades at least partially overlap when viewed along the entry direction.

In some embodiments, the optical unit further includes a third blade for partially covering the opening of the fixed part, and when viewed along the entry direction, the first and third blades at least partially overlap, and the second and third blades at least partially overlap.

In some embodiments, the driving mechanism further includes a protecting element, wherein the protecting element and the optical unit at least partially overlap when viewed along the entry direction.

DETAILED DESCRIPTION OF INVENTION

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, and in which specific embodiments of which the invention may be practiced are shown by way of illustration. In this regard, directional terminology, such as “top,” “bottom,” “left,” “right,” “front,” “back,” etc., is used with reference to the orientation of the figures being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for the purposes of illustration and is in no way limiting.

FIGS.1and2are exploded diagrams of a driving mechanism100in accordance with an embodiment of the invention.FIGS.3and4are perspective diagrams of the driving mechanism100inFIGS.1and2.FIG.5is a perspective diagram of the driving mechanism100inFIG.3with the housing10omitted therefrom.FIG.6is an exploded diagram of the driving mechanism100inFIG.4with the housing10omitted therefrom.

As shown inFIGS.1-6, an embodiment of a driving mechanism100primarily comprises a housing10, two protecting elements B1, B2, several blades S, an annular movable part30, at least a slider P, a fixed part40, at least a driving unit50, a resilient element R, a bottom plate20, a sensing magnet HM, and a sensor HS.

The driving mechanism100in this embodiment may be a variable aperture (VA) mechanism. The movable part30is rotatably disposed around an annular flange42on the inner side of the fixed part40. The blades S constitute an optical unit, and the hinges301,401on the movable part30and the fixed part40extend through the holes h1, h2of the blades S, whereby the blades S can rotate relative to the movable part30and the fixed part40. The blades S are configured to partially cover an opening H at the center of the fixed part40, so as to regulate the quantity of light through the driving mechanism100.

The sensing magnet HM and the sensor HS constitute a sensing nodule, wherein the sensor HS is disposed on the bottom plate20(e.g. PCB), and the sensing magnet HM is disposed on the movable part30and extends through the fixed part40. In this embodiment, the sensor HS is a Hall sensor that can measure the displacement of the movable part30relative to the fixed part40by detecting the sensing magnet HM.

The fixed part40has a polygonal shape (e.g. quadrilateral shape), and the slider P comprises a guide pin located close to a corner of the fixed part40. During assembly, the slider P extends through the rail31and the guiding structure41of the movable part30and the fixed part40to the longitudinal cavity21of the bottom plate20, wherein the cavity21is parallel to the guiding structure41.

Here, the rail31, the guiding structure41, and the cavity21are all longitudinal slots respectively formed through the movable part30, the fixed part40, and the bottom plate20.

The driving units50and the resilient element R are disposed at the bottom of the fixed part40. Each of the driving units50comprises a shaped-memory alloy (SMA) element. In this embodiment, the driving unit50can be electrically connected to the bottom plate20(e.g. PCB) or external circuits via the conductive terminals C. The resilient element R may be a spring sheet, wherein the slider P are disposed between the driving unit50and the resilient element R.

It should be noted that the slider P can be driven by the driving unit50and the resilient element R to move back and forth along the rail30and the guiding structure41. Therefore, rotation of the blades S and the movable part30can be controlled to appropriately regulate the quantity of light through the driving mechanism100.

Still referring toFIGS.1-6, two protecting elements B1, B2are disposed on the top and bottom sides of the blades S, so as to block light and protect the blades S.

FIG.7is a schematic diagram showing that the blades S partially cover the opening H of the fixed part40when the movable part30in a first position relative to the fixed part40.FIG.8is a schematic diagram showing that the slider P is at the first end411of the guiding structure41when the movable part30in the first position relative to the fixed part40.

Referring toFIGS.7and8, before a current signal is applied to the driving unit50(SMA element), the resilient element R can exert an outward spring force on the slider P that extends through the movable part30and the fixed part40, whereby the slider P is in contact with and positioned at the first end411of the guiding structure41(FIG.8). In this state, the movable part30can be held in a first position relative to the fixed part40, and the driving unit50(SMA element) has a first length.

FIG.9is a schematic diagram showing that the movable part30rotates from the first position ofFIG.7to a second position relative to the fixed part40.FIG.10is a schematic diagram showing that the slider P is at the second end412of the guiding structure41when the movable part30in the second position relative to the fixed part40.

Referring toFIGS.9and10, the driving unit50(SMA element) shrinks from the first length to a second length when a current signal is applied thereto. In this state, the driving unit50can exert a shrinkage force on the slider P that extends through the movable part30and the fixed part40. As a result, the slider P slides from the first end411along the guiding structure41to contact the second end412, as the arrow indicates inFIG.10. Moreover, the movable part30moves from the first position to the second position relative to the fixed part40, and the blades S rotate relative to the movable part30and the fixed part40, thus increasing the quantity of light through the driving mechanism100.

It should be noted that the central axis A41of the guiding structure41extends along a first direction and has a tilt angle (e.g. 45 degree) relative to a side of the fixed part40. Specifically, the central axis A31of the rail31extends along a second direction that is neither parallel nor perpendicular to the first direction.

In this embodiment, the included angle between the first and second directions ranges from 20 degree to 70 degree. It can be seen inFIGS.7-10that the distance between the first end411to the center of the opening H is further than the distance between the second end412to the center of the opening H.

As shown inFIGS.7and9, the blades S (optical unit) include a first blade S1, a second blade S2, a third blade S3, a fourth blade S4, a fifth blade S5, and a sixth blade S6. Light can enter the driving mechanism100along an entry direction and propagate through the opening H. When viewed along the entry direction (Z direction), the first and second blades S1, S2at least partially overlap, the first and third blades S1, S3at least partially overlap, and the second and third blades S2, S3at least partially overlap. Moreover, when viewed along the entry direction (Z direction), both of the protecting elements B1and B2at least partially overlap each one of the blades S.

FIG.11is an enlarged partial cross-sectional view of the driving mechanism100.

As shown inFIG.11, the sensing magnet HM and the sensor HS constitute a sensing nodule, wherein the sensor HS is disposed on the bottom plate20(e.g. PCB), and the sensing magnet HM is disposed on the movable part30and extends through an opening of the fixed part40. In this embodiment, the sensor HS is a Hall sensor that can detect the sensing magnet HM to measure the displacement of the movable part30relative to the fixed part40.

Additionally,FIG.11shows that the movable part30and the fixed part40are both disposed in the housing10, wherein a smooth element W is disposed on the inner surface of the housing10and located adjacent to the slider P.

It should be noted that the smooth element W may be in contact with or spaced apart from the slider P. When the slider P moves along the rail31and the guiding structure41, the slider P can also slide on a smooth surface of the smooth element W, thereby preventing tilt of the slider P relative to the movable part30and the fixed part40.

FIG.12is a partial perspective diagram showing a magnetic element M and a heart-shaped spring R′ disposed on the outer and inner sides of the slider P.

In another embodiment, the resilient element R may be replaced by the magnetic element M or the heart-shaped spring R′, as shown inFIG.12. The magnetic element M (e.g. magnet) may be affixed to the fixed part40or the bottom plate20, and the driving unit50(SMA element) is located between the magnetic element M and the slider P. The magnetic element M can exert a magnetic force on the slider P (e.g. metal guide pin) toward the outside of the driving mechanism100, whereby the slider P can be positioned at the first end411of the guiding structure41.

In summary, the invention provides a driving mechanism100that comprises a driving unit50(SMA element) for impelling the slider P along the guiding structure41. Thus, the blades S and the movable part30can be driven to rotate relative to the fixed part40, whereby the quantity of light through the driving mechanism100can be effectively regulated. Moreover, miniaturization of the driving mechanism100(e.g. variable aperture mechanism) can also be achieved.