Focusing-free microlens assembly and the method of making the same

Abstract

A focusing-free microlens assembly includes a holder and a plurality of optical lenses mounted on the holder. Each of the holder and the optical lenses has a tolerance, and a combinative tolerance of the tolerances of the holder and the optical lenses is less than a depth of focus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of conventional image catch unit;

FIG. 2 is a perspective of a preferred embodiment of the present invention; and

FIG. 3 is a sectional view of the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1 to FIG. 4, a focusing-free microlens assembly 10 of the preferred embodiment of the present invention has a depth of focus of 17 μm. The depth of focus includes a 12 μm front depth of focus and a 5 μm rear depth of focus. The microlens assembly 10 includes a holder 12 made of metallic or plastic with a 5 μm tolerance of height, a barrel 22 with a connecting base 24 at an end thereof and an optical lens 14. The barrel 22 is opening at opposite ends, one of which is closed by the connecting base 24. The connecting base 24 has a plurality of apertures 26, each of which has a flowing space 28 at a bottom thereof. The optical lens 14, which is made of plastic or glass, has a 5 μm tolerance at a center thickness. The optical lens 14 is mounted in the barrel 22.

Adhesive 30 is added in the apertures 26 of the connecting base 24 to adhere to an image sensor 32. The connecting base 24 will be connected to the image sensor 32 tightly because the redundant adhesive 30 will flows into the flowing spaces 28 rather than between the connecting base 24 and the image sensor 32. As a result, the combinative tolerance of the holder 12 and the lens 14 is less than the depth of focus (17 μm) that cause the microlens assembly has a real function of focusing-free.

The present invention also provides a method of making the microlens assembly of focusing-free. In other words, in fabrication, the combinative tolerance of the optical lens and the holder is kept less than the depth of focus that may achieve the focusing-free function.

In conclusion, the present invention provides the optical lens mounted in the barrel-like holder directly. As compared with the conventional lens assembly, which the optical lens is mounted in the barrel, the microlens assembly of the present invention has less components and a less combinative tolerance. In addition, the combinative tolerance is kept less than the depth of focus that the microlens assembly of the present invention doesn't need the focusing adjustment process. It reduce the cost of fabrication.

The description above is a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of the claim of the present invention.

Claims

1. A focusing-free microlens assembly, comprising a holder and a plurality of optical lenses mounted on the holder, wherein each of the holder and the optical lenses has a tolerance, and a combinative tolerance of the tolerances of the holder and the optical lenses is less than a depth of focus.

2. The focusing-free microlens assembly as defined in claim 1, wherein the holder has a barrel with opposite opening ends, on the opposite opening ends of which the lenses and an image sensor are provided respectively.

3. The focusing-free microlens assembly as defined in claim 2, wherein the holder is provided with a plurality of apertures, in which adhesive is provided, associated with the image sensor.

4. The focusing-free microlens assembly as defined in claim 3, wherein the holder further has a plurality of flowing spaces communicated with the apertures.

5. The focusing-free microlens assembly as defined in claim 4, wherein the holder further includes a connecting base on an end of the barrel to be connected to the image sensor, and the apertures are provided on the connecting base and the flowing spaces are provided in the connecting in the connecting space.

6. The focusing-free microlens assembly as defined in claim 2, wherein the lenses are received in the barrel through the opening end opposite the image sensor.

7. A method of making a focusing-free microlens assembly comprising the step of keeping a combinative tolerance of optical lenses and a holder less than a depth of focus.