TECHNICAL FIELD

The present invention generally relates to lens modules used in photography and imaging equipment and, more particularly, to a lens module for a digital camera.

BACKGROUND

Currently, digital camera modules are included as a feature in a wide variety of portable electronic devices. Most portable electronic devices are becoming progressively more miniaturized over time, and digital camera modules are correspondingly becoming smaller and smaller. Nevertheless, in spite of the small size of a contemporary digital camera module, consumers still demand excellent imaging.

Most digital camera modules contain lens modules for taking high quality photos. Aspheric lenses are typically used in lens modules for miniaturizing digital cameras. Plastic aspherical lenses have low cost, and are widely used in lens modules. However, plastic aspherical lenses may become deformed at high or low temperatures. Thus, plastic aspherical lenses have a lower optical stability at high or low temperatures, and the digital camera has a lower image quality when using plastic aspheric lenses in extreme conditions.

Therefore, a lens module for a digital camera which can overcome the above-described problems is desired.

SUMMARY

In one embodiment, a lens module includes a lens barrel, a base, and a temperature compensation module. A first lens is disposed in the lens barrel. The lens barrel is disposed in the base. The temperature compensation module is detachably installed in the base, and the temperature compensation module includes a temperature compensation lens. The temperature compensation lens is configured for compensating for deformation of the first lens caused by temperature changes.

Other objects, advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the lens module 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 lens module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a schematic view of a lens module in accordance with a preferred embodiment; and

FIG. 2 is a schematic, cross-sectional view of the lens module along line II-II in FIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to FIGS. 1 and 2, in a preferred embodiment, a lens module 800 includes a base 10, a lens barrel 20, and a temperature compensation element 30.

The base 10 is a hollow cylinder, and a through hole 100 is formed in a central area of the base 10. The base 10 has an inner wall 102 and an outer wall 101. An upper portion of the inner wall 102 has a first screw thread 1021, and a lower portion of the inner wall 102 has an annular groove 1022. An arcuate hole 103 is formed on the outer wall 101 of the base 10, and the arcuate hole 103 penetrates through the outer wall 101 and the inner wall 102 at the position of the annular groove 1022. Thus, the arcuate hole 103 communicates with the through hole 100. A first screw hole 104 is formed at an opposite position to the arcuate hole 103 on the outer wall 101, and the first screw hole 104 communicates with the annular groove 1022. The first screw hole 104 is configured for securing the temperature compensation element 30 cooperating with a screw bolt 40. The base 10 also includes a step portion 1023 along the through hole 100 for holding an image sensor 105. The image sensor 105 can be a charge coupled device (CCD) or a complementary metal-oxide-semiconductor transistor (CMOS).

The lens barrel 20 has a second screw thread 202 in accordance with the first screw thread 1021 of the base 10, and the lens barrel 20 is installed in the through hole 100 of the base 10 by cooperation of the first and second screw threads 1021, 202. A first lens group 201 is disposed in the lens barrel 20. In this embodiment, the first lens group 201 includes two lenses. The lenses can be aspherical lenses, spherical lenses, or combinations thereof. The lenses are typically made of transparent plastic material, such as polycarbonate, polymethyl methacrylate, or any desired combination thereof.

The temperature compensation element 30 includes a cylindrical holder 301, and at least one temperature compensation lens 302 disposed in the cylindrical holder 301. A second screw hole 301 is formed on the cylindrical holder 301, and the cylindrical holder 301 is secured in the annular groove 1022 of the base 10 using a screw bolt 40 extending through the first screw hole 104 into the second screw hole 3011. The temperature compensation lens 302 is configured for compensating for deformation of the first lens group 201 at high and low temperatures. The temperature compensation lens 302 is typically a glass lens, because a glass lens has a lower deformation at different temperatures.

An exemplary method for designing the temperature compensation lens 302 is provided. Firstly, a first group of optical parameter of the first lens group 201 is measured at room temperature. Secondly, a second group of optical parameter of the first lens group 201 is measured at low temperature and high temperatures. Thirdly, the first and second optical parameters are compared, and a difference in optical parameter is obtained. Finally, the temperature compensation lens 302 is designed in accordance with the difference in optical parameters. The optical parameters can be refractive index or dispersive power. Understandably, different temperature compensation lenses 302 can be designed for compensating for the deformations of the first lens group at different temperatures.

When assembling the lens module 800, firstly, the lens barrel 20 is installed in the base 10 by the cooperation of the first and second screw threads 1021, 202. Then, the temperature compensation element 30 is installed in the annular groove 1022 of the base 10 through the arcuate hole 103, and secured using the screw bolt 40 through the first screw hole 104 and the second screw hole 3011. Understandably, the temperature compensation element 30 can be changed by loosening the screw bolt 40.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples here before described merely being preferred or exemplary embodiments of the invention.