CN102981237A - Lens module - Google Patents

Abstract

The invention provides a lens module, which includes a lens barrel and a first lens, a second lens and a third lens accommodated in the lens barrel. The lens barrel includes an object side and an image side opposite to the object side. The first lens, the second lens and the third lens are sequentially arranged from the object side to the image side. The second lens includes a second object end surface facing the object side and a second image end surface facing the image side. A layer of anti-reflection film is coated on the surface of the second image end, and the reflectivity of the anti-reflection film to light with a wavelength of 700nm-740nm is less than 2.25%. The invention effectively reduces the generation of half-moon-shaped stray light by coating the surface of the second image end of the second lens with a layer of anti-reflection film whose reflectivity to long waves with a wavelength of 700nm to 740nm is less than 2.25%.

Description

Lens module

technical field

The invention relates to a lens module, in particular to a lens module capable of reducing half-moon stray light.

Background technique

The lens module includes a lens barrel and at least one lens accommodated in the lens barrel. When the light enters the lens barrel from the object side of the lens barrel, most of the light will directly pass through the lens sheet, and a small part of the light will be absorbed by the lens. reflected by the optical surface. And this part of the reflected light forms stray light after multiple reflections in the lens barrel, resulting in strange light and shadow in the imaged image.

Traditional lens modules have a high reflectivity for long waves with a wavelength of 700nm~740nm. When the lens module and the light source form an angle of 35 degrees to shoot, a half-moon-shaped stray light will be generated at the corner of the image, resulting in abnormal images.

Contents of the invention

In view of this, it is necessary to provide a lens module capable of reducing half-moon stray light.

A lens module includes a lens barrel and a first lens, a second lens and a third lens accommodated in the lens barrel. The lens barrel includes an object side and an image side opposite to the object side. The first lens, the second lens and the third lens are sequentially arranged from the object side to the image side. The second lens includes a second object end surface facing the object side and a second image end surface facing the image side. A layer of anti-reflection film is plated on the surface of the second image end, and the reflectivity of the anti-reflection film to long waves with a wavelength of 700nm-740nm is less than 2.25%.

In this way, a layer of anti-reflection film with a reflectivity of less than 2.25% for long waves with a wavelength of 700nm-740nm is coated on the surface of the second image end of the second lens, effectively reducing the generation of half-moon-shaped stray light.

Description of drawings

FIG. 1 is a cross-sectional view of a lens module provided by an embodiment of the present invention.

Figure 2 is an image taken when the traditional lens module and the light source form an included angle of 35 degrees.

Fig. 3 is an image captured when the lens module provided by the embodiment of the present invention forms an included angle of 35 degrees with the light source.

Description of main component symbols

Lens module 100 lens barrel 10 object side 11 image side 12 Accommodating space 13 first lens 20 first object side surface twenty one first image side surface twenty two second lens 30 second object side surface 31 Second image side surface 32 Anti-reflection film 321 third lens 40 third object side surface 41 third side surface 42 Shading film 50 filter 60

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

Detailed ways

As shown in FIG. 1 , a lens module 100 provided in an embodiment of the present invention includes a lens barrel 10 and a first lens 20 , a second lens 30 , a The third lens 40 , two shading sheets 50 and a filter 60 .

The lens barrel 10 is cylindrical and includes a half-closed object side 11 , an unclosed image side 12 and an accommodating space 13 communicating with both the object side 11 and the image side 12 . The first lens 20 , the second lens 30 and the third lens 40 are sequentially accommodated in the accommodating space 13 from the object side 11 to the image side 12 .

The first lens 20 includes a first object end surface 21 and a first image end surface 22 opposite to the first object end surface 21 . The first object end surface 21 protrudes toward the object side 11 , and the first image end surface 22 is concave toward the image side 12 . The second lens 30 includes a second object end surface 31 and a second image end surface 32 opposite to the second object end surface 31 . The second object end surface 31 is concave toward the object side 11 , and the second image end surface 32 is convex toward the image side 12 . The third lens 40 includes a third object end surface 41 and a third image end surface 42 opposite to the third object end surface 41 . The third object end surface 41 protrudes toward the object side 11 , and the second image end surface 32 is concave toward the image side 12 .

In this embodiment, the first lens 20 , the second lens 30 and the third lens 40 are all made of glass or plastic, and are spherical lenses or aspheric lenses. It can be understood that the lens module 100 may further include a fourth lens, a fifth lens, and the like.

The second image side 32 of the second lens 30 is coated with a layer of anti-reflection film 321 , and the reflectivity of the anti-reflection film 321 for long waves with a wavelength of 700nm-740nm is less than 2.25%. The antireflection film 321 includes the first to fourth film layers stacked alternately from the second image end surface 32 to the image side 12, wherein the material of the odd film layers is titanium dioxide, and the material of the even film layers is silicon dioxide. The specific structure is shown in Table 1. In this embodiment, the anti-reflection film 321 has a reflectivity of less than 2% for long waves with a wavelength of 700 nm to 740 nm.

Table 1 Anti-reflection film structure

film layer Material Thickness (nm) 1st film TiO2 11.52 2nd film SIO2 28.93 3rd layer TiO2 111.15 4th film SIO2 83.78

It can be understood that the anti-reflection film 321 can also use other materials and other film structures to achieve an anti-reflection effect on long wavelengths of 700 nm to 740 nm, and is not limited to the technical solution provided in this embodiment.

The two shading sheets 50 are disposed between the first lens 20 and the second lens 30 and between the second lens 30 and the third lens 40 at intervals, respectively. The shading sheet 50 is used to further absorb stray light in the lens module 100 .

The filter 60 is made of glass material, and is fixed on the side of the third lens 40 close to the image side 12 of the lens barrel 10 . The filter 60 is used to filter out infrared light in the light passing through the third lens 40 .

During use, the light entering from the object side 11 of the lens barrel 10 is projected on the first lens 20 , the light passes through the first lens 20 and then projects to the second lens 30 , when the light projects to the second lens 30 of the second lens 30 When looking at the end surface 32, the incident angle of the light rays is less than 6.85 degrees. Since the incident angle of the light is small, the reflection of the light by the second image end surface 32 is effectively reduced. In addition, since the anti-reflection film 321 plated on the second image end surface 32 has the effect of increasing transmission and reducing reflection, the reflectance of long-wave wavelengths of 700nm to 740nm in the light projected on the second image end surface 32 is less than 2.25%, thereby reducing the light reflected by the second mirror 30. The light passing through the second lens 30 is projected on the filter 60 after passing through the third lens 40, and the filter 60 filters out near-infrared rays in the light. The light passing through the filter 60 is projected on an image sensor (not shown) to form an image.

The image in FIG. 2 is an image taken when the angle between the traditional lens module 100 and a light source (not shown) is 35 degrees. It can be seen from the image that a half-moon-shaped stray light is formed on the right side of the image . The image in Fig. 3 is the image taken when the lens module 100 provided by the embodiment of the present invention forms an angle of 35 degrees with the light source. After comparing with the image in Fig. 2, it can be clearly seen that the lens provided by the embodiment The half-moon-shaped stray light in the image imaged by the module 100 is obviously reduced.

In the lens module provided by the present invention, the surface of the second image end of the second lens is coated with an anti-reflection film with a reflectivity of less than 2.25% for long waves with a wavelength of 700nm to 740nm, so as to effectively reduce the generation of half-moon-shaped stray light .

It can be understood that, for those skilled in the art, various other corresponding changes and deformations can be made according to the technical concept of the present invention, and all these changes and deformations should belong to the protection scope of the claims of the present invention .

Claims (7)

1. camera lens module, it comprises a lens barrel and is contained in first eyeglass in this lens barrel, second eyeglass and a prismatic glasses; This lens barrel comprises a thing side and a picture side relative with this thing side; This first eyeglass, the second eyeglass and prismatic glasses set gradually as side to this from this thing side; This second eyeglass comprises one towards the second thing end surfaces and second a picture end surfaces towards the picture side of thing side; This second is provided with one deck anti-reflective film as plating on the end surfaces, and this anti-reflective film is that the reflectivity of long wave of 700nm ~ 740nm is less than 2.25% to wavelength.

2. camera lens module as claimed in claim 1 is characterized in that: described the second thing end surfaces is towards thing side depression, and described the second picture end surfaces protrudes towards the picture side.

3. camera lens module as claimed in claim 1 is characterized in that: when ray cast to the second picture end surfaces, the incident angle of light is less than 6.85 degree.

4. camera lens module as claimed in claim 1, it is characterized in that: described anti-reflective film comprise from this second as end surfaces to replacing the 1st to the 4th stacking rete as side direction, wherein the material of odd number rete is titania, and the material of even number tunic is silicon dioxide.

5. camera lens module as claimed in claim 4 is characterized in that: this anti-reflective film to the reflectivity of the light of wavelength 700nm ~ 740nm less than 2%.

6. camera lens module as claimed in claim 1, it is characterized in that: described camera lens module also comprises an optical filter, described optical filter is arranged on prismatic glasses near a side of picture side.

7. camera lens module as claimed in claim 1 is characterized in that: be provided with an anti-dazzling screen between described the first eyeglass and the second eyeglass and between the second eyeglass and the prismatic glasses.

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