Lens module

A lens module includes a driving device, an image sensing device, a lens group frame, and an infrared filter. The driving device has a lens barrel for an optical signal passing through. The image sensing device is on a path of the optical signal to convert the optical signal into an electric signal. The lens group frame is provided in the lens barrel, and has a main body, which is driven by the driving device to be moved between a first position and a second position, and a lens holder, which is pivotally connected on the main body and is swung between a third position and a fourth position when the main body is respectively at the first and the second positions. The infrared filter is provided on the lens holder, and is precisely aligned with the image sensing device when the lens holder is at the fourth position.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to an optical lens, and more particularly to a lens module.

2. Description of Related Art

For those optical image devices such as cameras or camcorders that are usually carried on the body, the size and weight of zoom lenses are greatly reduced with the help of recent advances in imaging technology. In addition to miniature and lightweight, such optical image devices always pursue better optical performance for achieving higher resolution and contrast. In other words, miniature and high optical performance are two key design elements of zoom lenses nowadays.

For miniature, there is one kind of lens module, in which the lens and the zooming mechanism can be collapsed into the case of an optical image device. However, there is still room for improvement.

BRIEF SUMMARY OF THE INVENTION

In view of the above, the primary objective of the present invention is to provide a lens module, which is applied with an infrared filter and compatible with lens group composed of many (even more than 10) single lenses, but still able to reduce the thickness of a collapsed lens, and therefore achieves the purpose of miniature optical image devices.

The lens module provided in the present invention includes a driving device, an image sensing device, a lens group frame, and an infrared filter. The driving device has at least a lens barrel for an optical signal passing through; the image sensing device is provided on a side of the driving device, wherein the image sensing device is on a path of the optical signal to convert the optical signal into an electric signal accordingly; the lens group frame is provided in the lens barrel, wherein the lens group frame has a main body, which is driven by the driving device to be moved between a first position and a second position, and a lens holder pivotally connected to the main body; the lens holder is moved between a third position and a fourth position as the main body is moved between the first position and the-second position; the infrared filter is provided on the lens holder, wherein when the lens holder is at the fourth position, the infrared filter is precisely aligned with the image sensing device to filter out infrared rays within the optical signal which is projected to the image sensing device.

Whereby, with the aforementioned design to pivotally shift the infrared filter, the total thickness of arranged single lenses can be effectively reduced when collapsed. As a result, optical image devices applied with the lens module can be smaller and thinner.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIG. 1toFIG. 7, the lens module of the preferred embodiment of the present invention includes an image sensing device10, a driving device, a lens group frame30, a first lens group G1, a second lens group G2, and an infrared filter FT.

The image sensing device10receives an optical signal, and converts it into an electric signal accordingly. In the preferred embodiment, the image sensing device10is a complementary metal-oxide-semiconductor (CMOS), but this is not a limitation of the present invention. In other embodiments, the image sensing device10is a charge-coupled device (CCD) or other components which are able to receive the optical signal to convert it into the electric signal.

The driving device is provided in front of the image sensing device10, wherein the driving device includes a first lens barrel21, a second lens barrel22, a third lens barrel23, a fourth lens barrel24, and a fifth lens barrel25for the optical signal passing through. The first lens barrel21has a rod211therein, and an inner side of the first lens barrel21has three separated rails212thereon. The second lens barrel22is provided in the first lens barrel21, wherein an outer side of the second lens barrel22has three separated bumps221thereon, which are respectively engaged with the rails212of the first lens barrel21, and can be driven by a motor (not shown) to reciprocate in the rails212of the first lens barrel21. In addition, an inner side of the second lens barrel22has three separated cam grooves222. The third lens barrel23is provided in the first lens barrel21with a part thereof in the second lens barrel22. A wall of the third lens barrel23has three separated first straight slots231and three second straight slots232thereon. The fourth lens barrel24is provided in the second lens barrel22, and between the second lens barrel22and the third lens barrel23. An outer side of the fourth lens barrel24has three guide shafts241thereon, which are respectively received in the cam grooves222to make the fourth lens barrel24relative movable to the second lens barrel22along the cam grooves222. In addition, a wall of the fourth lens barrel24has three separated first guide slots242and three second guide slots243thereon, which are respectively corresponding to the first straight slots231and the second straight slots232of the third lens barrel23. An outer side of the fifth lens barrel25has three shafts251thereon, which respectively pass through the second guide slots243and then received in the second straight slots232of the third lens barrel23.

The lens group frame30is provided in the fourth lens barrel24, wherein the lens group frame30has a main body31, a lens holder32, a gear set33, and a torsion spring34. The main body31has an opening311at its center, which is precisely aligned with the image sensing device10behind the driving device. In addition, an outer side of the main body31has three separated protrusion shafts312thereon, which respectively pass through the first guide slots242and then received in the first straight slots231of the third lens barrel23to make the main body31drivable. More specifically, the main body31can be driven to move back and forth between a first position (as shown inFIG. 3) and a second position (as shown inFIG. 5) in the fourth lens barrel24along the first straight slots231and the first guide slots242. The lens holder32is pivotally provided on the main body31, wherein the lens holder32can be pivotally swung between a third position (as shown inFIG. 6) and a fourth position (as shown inFIG. 7) on the main body31as the main body31is moved back and forth between the first position and the second position. In more details, when the lens holder32is at the third position, it is deviated from the opening311; and when the lens holder32is at the fourth position, it is precisely aligned with the opening311. The gear set33is provided at where the lens holder32is hinged with the main body31, and is connected to the lens holder32. An end of the torsion spring34urges the main body31, and another end thereof urges the lens holder32. Therefore a force is provided by the torsion spring34to urge the lens holder32toward the fourth position from the third position.

The first lens group G1is fixed on the fifth lens barrel25, and can be moved simultaneously with the fifth lens barrel25. The second lens group G2is provided on the lens holder32of the lens group frame30. The infrared filter FT is provided on the lens holder32, and is closer to the image sensing device10than the second lens group G2.

Whereby, the second lens barrel22is driven by the motor to move along the rails212, which is somewhat in a spiral way. In other words, the second lens barrel22. Consequently, the fourth lens barrel24is moved along the cam grooves222, and therefore the fourth lens barrel24is either getting closer or moving away from the first lens barrel21. Furthermore, the main body31of the lens group frame30can be guided by the first guide slots242to move back and forth between the first position and the second position along the first straight slots231of the third lens barrel23. As a result, the lens module can be switched between a collapsing state (as shown inFIG. 2, where the lens module is collapsed) and an extension state (as shown inFIG. 4, where the lens module extends out).

In addition, when the lens module is switched from the collapsing state (as shown inFIG. 2andFIG. 3) to the extension state (as shown inFIG. 4andFIG. 5), the main body31of the lens group frame30is driven to move toward the second position from the first position. Meanwhile, the lens holder32is swung to the fourth position from the third position with the force provided by the torsion spring34to precisely align the second lens group G2and the infrared filter FT with the opening. Therefore, the second lens group G2and the infrared filter FT are aligned with each other, and together aligned with the image sensing device10as well. The infrared filter FT is between the second lens group G2and the image sensing device10.

In this way, the focal length of the lens module can be adjusted by moving the lens group frame30, and the optical features of the optical signal passing through the lens barrels21-25are changed accordingly to successfully focus the optical signal onto the image sensing device10. In addition, infrared rays within the optical signal projected to the image sensing device10can be filtered out with the infrared filter FT, which further enhances the optical performance of the lens module.

In addition, when the lens module is switched from the extension state (as shown inFIG. 4andFIG. 5) to the collapsing state (as shown inFIG. 2andFIG. 3), the main body31of the lens group frame30is driven to move gradually toward the first position from the second position. Meanwhile, as shown inFIG. 8, the rod211of the first lens barrel21abuts against the gear set33, and pushes the gear set33to rotate. The lens holder32is therefore driven by the gear set33to pivotally swing back to the third position from the fourth position. After that, the lens holder32is restricted from leaving the third position, for the rod211keeps abutting against the gear set33.

With the aforementioned way of pivotally swing the lens holder32, the lens module can stagger the main body31of the lens group frame30and the second lens group G2(with the infrared filter FT too) in the collapsing state. Therefore, the thickness of the lens module is reduced after being collapsed, and the purpose of designing miniature optical image devices can be achieved.

It is worth mentioning that, though the infrared filter FT is between the second lens group G2and the image sensing device10in the preferred embodiment, it can be provided among the second lens group G2, or, the second lens group G2can be provided between the infrared filter FT and the image sensing device10in other embodiments. All the arrangements have the same function of filtering out the infrared rays, and can equally reduce the thickness of the collapsed lens module.