# Patent

## Title
Lens module with filter element

## Abstract

A lens module includes a lens barrel, at least one lens, and a filter element. The lens barrel includes an object-side end and an image-side end opposite to the object-side end. The at least one lens is received in the lens barrel. The filter element is received in the lens barrel, and includes a transparent substrate, an anti-reflection film, and an infrared filtering film. The transparent substrate includes an object-side surface facing the object-side end and an image-side surface facing the image-side end. The anti-reflection film is coated on the object-side surface, and the infrared filtering film is coated on the image-side surface.

## Background
BACKGROUND
1. Technical Field
The present disclosure relates to lens modules and, particularly, to a lens module with a filter element.
2. Description of Related Art
Lens modules include at least one lens and a filter element generally positioned at an image side of the lens. The filter element includes a transparent substrate and an infrared filtering film coated on an object side of the transparent substrate. The filter element is for filtering infrared light rays while transmitting visible light rays. However, current filter elements cannot transmit 100% visible light rays and reflect a minority of visible light rays, more than about 5%, which form a glare in an image after multiple reflections.
Therefore, it is desirable to provide a lens module, which can overcome the limitations described.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional schematic view of a lens module of an exemplary embodiment.
FIG. 2 is a spectrum chart of an infrared filtering film of a filter element of the lens module of FIG. 1.
FIG. 3 is a spectrum chart of an anti-reflection film of a filter element of the lens module of FIG. 1.
FIG. 4 is a cross-sectional schematic view of an arrangement of an antireflection film of FIG. 1.
FIG. 5 is a cross-sectional schematic view of an arrangement of an infrared filtering film of FIG. 1.



DETAILED DESCRIPTION
Embodiments of the disclosure will now be described in detail, with reference to the accompanying drawings.
FIG. 1, shows a lens module 100, according to an exemplary embodiment. The lens module 100 includes a lens barrel 10, at least one lens 20, a filter element 30, and an image sensor 40.
The lens barrel 10 is tubular and includes an object-side end 11 and an image-side end 12 opposite to the object-side end 11. The lens barrel 10 defines a receiving room 13 extending through the object-side end 11 and the image-side end 12. In this embodiment, the lens barrel 10 is made of light-shielding/opaque/black material(s).
The at least one lens 20 is received in the receiving room 13, adjacent to the object-side end 11. Each of the at least one lens 20 is made of plastic, glass, or other transparent materials, and is spherical or aspherical. In this embodiment, the lens module 100 includes two lenses 20 arranged in the receiving room 13 from the object-side end 11 to the image side end 12.
The filter element 30 is received in the receiving room 13, adjacent to the image side end 12. The filter element 30 includes a transparent substrate 31, an anti-reflection film 32, and an infrared filtering film 33. The transparent substrate 31 includes an object-side surface 311 facing the object-side end 11 and an image-side surface 312 facing the image-side end 12. The anti-reflection film 32 is coated on the object-side surface 311, and the infrared filtering film 33 is coated on the image-side surface 312.
In this embodiment, the transparent substrate 31 is made of glass, and a thickness of transparent substrate 31 is from about 0.2 mm to about 0.8 mm. A little of copper oxide (CuO) is doped in the materials of making the transparent substrate 31 for absorbing a part of infrared light rays. The anti-reflection film 32 includes first to fourth layers orderly stacked on the object-side surface 311. The odd numbered layers of the anti-reflection film 32 are made from titanium dioxide (TiO2) and the even numbered layers of the anti-reflection film 32 are made from silicon dioxide (SiO2). The material and thickness of each layer of the anti-reflection film 32 are shown in Table 1.











TABLE 1







Layers
Material
Thickness (nm)




















First layer
TiO2
11.52



Second layer
SiO2
28.93



Third layer
TiO2
111.15



Fourth layer
SiO2
83.78










The infrared filtering film 33 includes first to fifty fourth layers orderly stacked on the image-side surface 312. The odd numbered layers of the infrared filtering film 33 are made from TiO2, and the even numbered layers of the infrared filtering film 33 are made from SiO2. The material and thickness of each layer of the infrared filtering film 33 are shown in Table 2.











TABLE 2







Layers
Material
Thickness (nm)




















First layer
TiO2
7.28



Second layer
SiO2
18.67



Third layer
TiO2
86.78



Fourth layer
SiO2
142.53



Fifth layer
TiO2
80.33



Sixth layer
SiO2
132.59



Seventh layer
TiO2
81.28



Eighth layer
SiO2
128.33



Ninth layer
TiO2
81.96



Tenth layer
SiO2
124.34



Eleventh layer
TiO2
83.38



Twelfth layer
SiO2
121.71



Thirteenth layer
TiO2
83.92



Fourteenth layer
SiO2
123.09



Fifteenth layer
TiO2
84.08



Sixteenth layer
SiO2
124.78



Seventeenth layer
TiO2
84.81



Eighteenth layer
SiO2
134.73



Nineteenth layer
TiO2
97.58



Twentieth layer
SiO2
192.39



Twenty first layer
TiO2
104.2



Twenty second layer
SiO2
148.59



Twenty third layer
TiO2
83.66



Twenty fourth layer
SiO2
143.14



Twenty fifth layer
TiO2
93.6



Twenty sixth layer
SiO2
177.52



Twenty seventh layer
TiO2
105.92



Twenty eighth layer
SiO2
158.12



Twenty ninth layer
TiO2
87.79



Thirtieth layer
SiO2
152.72



Thirty first layer
TiO2
96.32



Thirty second layer
SiO2
174.89



Thirty third layer
TiO2
104.29



Thirty fourth layer
SiO2
163.45



Thirty fifth layer
TiO2
100.46



Thirty sixth layer
SiO2
180.21



Thirty seventh layer
TiO2
115.65



Thirty eighth layer
SiO2
188.01



Thirty ninth layer
TiO2
117.25



Fortieth layer
SiO2
191.74



Forty first layer
TiO2
118.28



Forty second layer
SiO2
192.04



Forty third layer
TiO2
116.57



Forty fourth layer
SiO2
192.79



Forty fifth layer
TiO2
117.32



Forty sixth layer
SiO2
190.86



Forty seventh layer
TiO2
118.16



Forty eighth layer
SiO2
190.44



Forty ninth layer
TiO2
116.69



Fiftieth layer
SiO2
191.4



Fifty first layer
TiO2
114.71



Fifty second layer
SiO2
186.74



Fifty third layer
TiO2
113.18



Fifty fourth layer
SiO2
92.44










The anti-reflection film 32 can be stacked by any number of layers with other materials for anti-reflecting light rays. The infrared filtering film 33 can be stacked by any number of layers with other materials for filtering infrared light rays.
The image sensor 40 is positioned at the image-side end 12 for covering the receiving room 13. The light rays penetrating the at least one lens 20 and the filter element 30 are projected on an imaging surface of the image sensor 40 for converting the light rays to electrical signals.
Referring to FIGS. 2-3, in use, light rays enter into the lens module 100 from the object-side end 11 of the lens barrel 10 and strike the filter element 30. The light rays orderly penetrate the anti-reflection film 32, the transparent substrate 31, and the infrared filtering film 33. The infrared light rays of the light rays penetrating the anti-reflection film 32 are filtered by the infrared filtering film 33. As the anti-reflection film 32 enhances transmissivity of the light rays projected on the filter element 30, the light rays reflected by the anti-reflection film 32 are less than about 5%. Therefore, the light rays can form reducing a glare in an image, and the quality of the image is enhanced.
Particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.

## Claims

1. A lens module, comprising:
a lens barrel comprising an object-side end and an image-side end opposite to the object-side end;
at least one lens received in the lens barrel; and
a filter element received in the lens barrel, and comprising a transparent substrate, an anti-reflection film, and an infrared filtering film; the transparent substrate comprising an object-side surface facing the object-side end and an image-side surface facing the image-side end; the anti-reflection film coated on the object-side surface, and the infrared filtering film coated on the image-side surface;
wherein the anti-reflection film comprises first to fourth layers orderly stacked on the object-side surface, the odd numbered layers of the anti-reflection film are made from titanium dioxide (TiO2), and the even numbered layers of the anti-reflection film are made from silicon dioxide (SiO2); the thicknesses of the first, second, third and fourth layers of the anti-reflection film are respectively 11.52 nm, 28.93 nm, 111.15 nm, and 83.78 nm;
wherein the infrared filtering film comprises first to fifty fourth layers orderly stacked on the image-side surface, the odd numbered layers of the infrared filtering film are made from TiO2, and the even numbered layers of the infrared filtering film are made from SiO2; the thicknesses of the first to fifty fourth layers of the infrared filtering film are respectively 7.28 nm, 18.67 nm, 86.78 nm, 142.53 nm, 80.33 nm, 132.59 nm, 81.28 nm, 128.33 nm, 81.96 nm, 124.34 nm, 83.38 nm, 121.71 nm, 83.92 nm, 123.09, 84.08 nm, 124.78 nm, 84.81 nm, 134.73 nm, 97.58 nm, 192.39 nm, 104.2 nm, 148.59 nm, 83.66 nm, 143.14 nm, 93.6 nm, 177.52 nm, 105.92 nm, 158.12 nm, 87.79 nm, 152.72 nm, 96.32 nm, 174.89 nm, 104.29 nm, 163.45 nm, 100.46 nm, 180.21 nm, 115.65 nm, 188.01 nm, 117.25 nm, 191.74 nm, 118.28 nm, 192.04 nm, 116.57 nm, 192.79 nm, 117.32 nm, 190.86 nm, 118.16 nm, 190.44 nm, 116.69 nm, 191.4 nm, 114.71 nm, 186.74 nm, 113.18 nm, and 92.44 nm.

2. The lens module of claim 1, wherein the anti-reflection film is configured for enhancing transmissivity of light rays projected thereon, and the infrared filtering film is configured for filtering infrared light rays.

3. The lens module of claim 2, further comprising an image sensor positioned at the image-side end, wherein the filter element is positioned between the least one lens and the image sensor.

4. The lens module of claim 3, wherein the anti-reflection film faces the at least one lens, and the infrared filtering film faces the image sensor.

5. The lens module of claim 1, wherein the transparent substrate is made of glass, and a thickness of the transparent substrate is from about 0.2 mm to about 0.8 mm.