CN110749949A

CN110749949A - Optical filter

Info

Publication number: CN110749949A
Application number: CN201810822019.2A
Authority: CN
Inventors: 吕中汉; 欧俊尧; 廖家圣
Original assignee: Platinum Polytron Technologies Inc
Current assignee: Platinum Polytron Technologies Inc
Priority date: 2018-07-24
Filing date: 2018-07-24
Publication date: 2020-02-04
Anticipated expiration: 2038-07-24
Also published as: CN110749949B; KR102040606B1

Abstract

An optical filter includes a light absorbing portion and a filter layer. The light absorption portion includes at least one ultraviolet light absorption material, wherein a maximum absorption wavelength of any one of the ultraviolet light absorption materials in an ultraviolet light band is between 365 nm and 380 nm. The filter layer is formed on the light absorbing part. The ultraviolet cut-off wavelength of the filter is between 404 nm and 419 nm. The average transmittance of the filter in the wavelength range of 350 nm to 395 nm is less than 2%, and the average transmittance in the wavelength range of 430 nm to 450 nm is more than 87%.

Description

Optical filter

Technical Field

The present disclosure relates to optical assemblies, and particularly to an optical filter.

Background

Many electronic devices, such as smart phones, have image sensors (image sensors), and most of the chips (chips) in the image sensors are Complementary Metal-Oxide-Semiconductor (CMOS) or Charge-Coupled devices (CCD). The response wavelength (wavelength of response) of the cmos and the ccd covers the uv light, so that the conventional image sensor is additionally provided with a filter to filter out unnecessary uv light, thereby preventing the uv light from adversely affecting the color of the image captured by the image sensor. Therefore, the filter is good enough to control the image quality of the image sensor.

Disclosure of Invention

The invention provides a filter which can filter ultraviolet light to help reduce adverse effects of the ultraviolet light on the image quality of an image sensor.

The optical filter provided by the invention comprises an optical absorption part and a filter layer. The light absorption portion includes at least one ultraviolet light absorption material, wherein a maximum absorption wavelength of any one of the ultraviolet light absorption materials in an ultraviolet light band is between 365 nm and 380 nm. The filter layer is formed on the light absorbing part. The ultraviolet light cut-off wavelength (ultravioletcut-on wavelength) of the optical filter is between 404 nm and 419 nm, and the average transmittance of the optical filter in the wavelength range of 350 nm to 395 nm is less than 2%, and the average transmittance in the wavelength range of 430 nm to 450 nm is more than 87%.

In an embodiment of the invention, the ultraviolet light absorbing material is selected from a group consisting of heterocyclic rings and phenolic groups, and the heterocyclic rings include at least one of oxygen atoms and nitrogen atoms.

In one embodiment of the present invention, the maximum absorption wavelength of the ultraviolet light absorbing material in the ultraviolet light band is between 369 nm and 379 nm.

In an embodiment of the invention, the solid content of the ultraviolet light absorbing material is between 0.2% and 0.27%.

In an embodiment of the invention, the solid content of the uv-absorbing material is between 16% and 23%.

In an embodiment of the invention, the ultraviolet light absorbing material includes a plurality of ultraviolet light absorbing materials, and includes a first ultraviolet light absorbing material and a second ultraviolet light absorbing material. The first ultraviolet light absorbing material has a maximum absorption wavelength that is greater than a maximum absorption wavelength of the second ultraviolet light absorbing material.

In an embodiment of the invention, a weight ratio between the first uv-absorbing material and the second uv-absorbing material is between 0.14 and 0.64.

In an embodiment of the invention, the light absorbing part further includes a transparent substrate and an adhesive layer. The adhesion layer is formed on the transparent substrate and adheres the ultraviolet light absorption material and the transparent substrate, wherein the adhesion layer has hydrophobicity, and the ultraviolet light absorption material has hydrophilicity.

In an embodiment of the invention, the transparent substrate is a blue glass plate for absorbing infrared light.

In an embodiment of the invention, a material of the transparent substrate includes at least one of glass and resin.

In an embodiment of the invention, the light absorption portion further includes an infrared light absorption layer formed on the transparent substrate.

In an embodiment of the invention, the infrared light absorption layer and the ultraviolet light absorption material are not in contact with the transparent substrate.

In an embodiment of the invention, the light absorbing portion further includes a light-transmitting layer. The filter layer is formed on the light-transmitting layer, and the ultraviolet light absorbing material is distributed in the light-transmitting layer.

In an embodiment of the invention, the light absorbing portion further includes an infrared light absorbing material, and the infrared light absorbing material is distributed in the light transmitting layer.

In an embodiment of the invention, the infrared cut-off wavelength of the filter is between 615 nm and 635 nm.

In an embodiment of the present invention, the average transmittance of the filter in the wavelength range of 700 nm to 725 nm is less than 2%.

In an embodiment of the invention, an average transmittance of the filter in a wavelength range from 700 nm to 1200 nm is less than 1%.

In an embodiment of the invention, the optical filter further includes an anti-reflection layer. The anti-reflection layer is formed on the light absorbing portion.

In an embodiment of the invention, the anti-reflection layer is a multilayer film.

In an embodiment of the invention, the filter layer is a multilayer film.

Based on the above, the present invention employs the light absorption portion and the filter layer to filter the ultraviolet light, and the average transmittance of the optical filter of the present invention in the wavelength range of 350 nm to 395 nm is less than 2%, and the average transmittance in the wavelength range of 430 nm to 450 nm is greater than 87%, wherein the ultraviolet light cut-off wavelength of the optical filter is between 404 nm to 419 nm. Therefore, the filter layer can effectively filter and remove the ultraviolet light, and further helps to reduce the adverse effect of the ultraviolet light on the image quality of the image sensor.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the technical solutions of the present invention can be implemented according to the content of the description, and in order to make the above-mentioned and other features and advantages of the present invention more clearly understood, the following specific examples are described in detail with reference to the accompanying drawings.

Drawings

Fig. 1A is a schematic cross-sectional view of a filter according to an embodiment of the invention.

Fig. 1B is a schematic cross-sectional view of a filter according to another embodiment of the invention.

Fig. 2 is a schematic cross-sectional view of a filter according to an embodiment of the invention.

Fig. 3 is a schematic cross-sectional view of a filter according to another embodiment of the invention.

Fig. 4 is a schematic diagram of a transmission spectrum of a filter according to at least one embodiment of the invention.

Detailed Description

Fig. 1A is a schematic cross-sectional view of a filter according to an embodiment of the invention. Referring to fig. 1A, the optical filter 100a includes a filter layer 110, a light absorption portion 120a, and an anti-reflection layer 130. The filter layer 110 is formed on the light absorption portion 120a and may be a multilayer film, so the filter layer 110 may include a plurality of transparent film layers stacked on each other and achieve a filtering function by using optical interference (optical interference). The anti-reflection layer 130 is formed on the light absorbing portion 120a, and the light absorbing portion 120a may be located between the filter layer 110 and the anti-reflection layer 130. The anti-reflective layer 130 can reduce the reflection of light to allow most of the light to pass through, wherein the anti-reflective layer 130 can be a multi-layer film (as shown in fig. 1A) or a sub-wavelength structure (sub-wavelength structure).

The light absorbing part 120a includes at least one ultraviolet light absorbing material, so the light absorbing part 120a can absorb ultraviolet light to filter the ultraviolet light. The maximum absorption wavelength of any ultraviolet light absorbing material in the ultraviolet light band is between 365 nm and 380 nm, such as 369 nm and 379 nm. In the embodiment shown in fig. 1A, the light absorbing part 120a includes only a single ultraviolet light absorbing material 121A, and the maximum absorption wavelength thereof may be about 377 nm, but in other embodiments, the light absorbing part 120a may include at least two ultraviolet light absorbing materials, so the light absorbing part 120a is not limited to include only the single ultraviolet light absorbing material 121A.

The light absorbing part 120a may further include an adhesive layer 122 and a transparent substrate 123. The uv absorbing material 121a and the adhesive layer 122 are both formed on the transparent substrate 123, and the adhesive layer 122 adheres the uv absorbing material 121a and the transparent substrate 123, wherein the adhesive layer 122 is located between the uv absorbing material 121a and the transparent substrate 123 and can contact the uv absorbing material 121a and the transparent substrate 123, and the uv absorbing material 121a can not contact the transparent substrate 123. The material of the transparent substrate 123 may include at least one of glass and plastic. For example, the transparent substrate 123 may be a plastic plate or a glass plate, wherein the glass plate is, for example, a blue glass plate capable of absorbing infrared light, and the plastic plate may be made of polymethyl methacrylate (PMMA, i.e., acryl). Alternatively, the plastic plate may be made of resin, i.e., the transparent substrate 123 may include resin. In addition, the transparent substrate 123 may be formed by laminating at least one glass plate and at least one plastic plate, so that the material of the transparent substrate 123 may include glass and plastic.

The adhesive layer 122 has hydrophobicity, and the ultraviolet light absorbing material 121a has hydrophilicity. For example, the adhesive layer 122 may be a hydrophobic silica sol gel, a hydrophobic epoxy resin, or a hydrophobic Polycarbonate (PC) resin (hereinafter, referred to as a hydrophobic PC resin). Therefore, a distinct interface (boundary) can be formed between the adhesive layer 122 and the uv-absorbing material 121 a. The hydrophobicity of the adhesive layer 122 and the hydrophilicity of the ultraviolet light absorbing material 121a can also promote a steeper slope of a transmission spectrum (transmissive spectrum) of the optical filter 100a at an ultraviolet light cut-off wavelength, thereby facilitating to improve a filtering effect of the optical filter 100 a. In addition, it should be noted that the cut-off wavelength (regardless of the uv cut-off wavelength and the ir cut-off wavelength described later) described herein refers to the wavelength corresponding to the transmittance of the filter of 50%. In other words, when the wavelength of a certain light is the cut-off wavelength of the filter, the transmittance of the filter corresponding to the light is substantially 50%.

The uv absorbing material 121a is selected from the group consisting of a heterocyclic ring and a phenol group, wherein the heterocyclic ring contains at least one of an oxygen atom and a nitrogen atom. That is, the heterocyclic ring may contain an oxygen atom and a nitrogen atom. Alternatively, the heterocyclic ring may contain an oxygen atom or a nitrogen atom. The uv absorbing material 121a may be a film (layer) and may be formed by coating and drying the uv absorbing solution, wherein the uv absorbing solution may be coated by at least one of dip coating, cast coating (casting), spray coating (spraying), spin coating (spin coating), bead coating, bar coating, and blade coating. In addition, the ultraviolet light absorption liquid contains ultraviolet light absorption dye and solvent, wherein the solvent can be organic liquid and can be at least one of ketones, ethers, esters, alcohols, alcohol-ethers, hydrocarbons and terpenes.

The filter 100a may have different transmittance and uv-cut wavelengths according to different solid contents of the uv-absorbing material 121a, such as samples a1 through A3 shown in the following table (a).

Watch 1

From the above table (one), when the solid content of the uv-absorbing material 121a is between 0.2% and 0.27%, the uv-cut wavelength of the filter 100a is between 414 nm and 415 nm; the average transmittance of the filter 100a in the wavelength range of 350 nm to 395 nm is less than 2%, for example, between 0.57% and 1.96%; the average transmittance of the filter 100a in the wavelength range from 430 nm to 450 nm is greater than 87%, such as between 88% and 91%. Therefore, the filter 100a can effectively filter the ultraviolet light (e.g., wavelength 350 nm to 395 nm) and transmit most of the visible light (e.g., wavelength 430 nm to 450 nm). Thus, the filter 100a can effectively filter the ultraviolet light, so as to help reduce the adverse effect of the ultraviolet light on the image quality of the image sensor.

It should be noted that since the filter layer 110 utilizes optical interference to filter light, the transmittance of the filter layer 110 varies with different incident angles, so that it is difficult for the filter layer 110 to filter ultraviolet light incident along a larger incident angle. However, the ultraviolet light absorbing material 121a can absorb ultraviolet light, so the light absorbing part 120a including the ultraviolet light absorbing material 121a can absorb ultraviolet light incident along a large incident angle. Therefore, when the ultraviolet light is incident on the filter 100a along a large incident angle, the light absorption portion 120a can also filter the ultraviolet light. Thus, the filter 100a is not affected by the incident angle of the ultraviolet light, and the filtering effect is not reduced.

Fig. 1B is a schematic cross-sectional view of a filter according to another embodiment of the invention. Referring to fig. 1B, the filter 100B shown in fig. 1B is similar to the filter 100a shown in fig. 1A. For example, the

optical filters

100a and 100b have the same function and include the same components, such as the filter layer 110 and the anti-reflection layer 130. However, unlike the optical filter 100a of fig. 1A, the light absorbing part 120b of the optical filter 100b includes a plurality of ultraviolet light absorbing materials. Taking fig. 1B as an example, the light absorbing portion 120B includes two ultraviolet light absorbing materials. In addition, it should be noted that, in other embodiments, the light absorbing portion 120b may also include more than two ultraviolet light absorbing materials. Therefore, the light absorbing part 120b is not limited to include only two ultraviolet light absorbing materials.

In the filter 100b, the ultraviolet light absorbing materials include a first ultraviolet light absorbing material 121b and a second ultraviolet light absorbing material 121 c. The maximum absorption wavelengths of the first ultraviolet light absorbing material 121b and the second ultraviolet light absorbing material 121c in the ultraviolet light band are also between 365 nm and 380 nm, such as 369 nm to 379 nm. In the present embodiment, the maximum absorption wavelength of the first ultraviolet light absorbing material 121b may be about 379 nm, and the maximum absorption wavelength of the second ultraviolet light absorbing material 121c may be about 375 nm. Therefore, the maximum absorption wavelength of the first ultraviolet light absorbing material 121b is greater than the maximum absorption wavelength of the second ultraviolet light absorbing material 121 c.

The weight ratio between the first uv-absorbing material 121B and the second uv-absorbing material 121c is between 0.14 and 0.64, and the optical filter 100B may have different transmittance and uv-cut wavelengths according to different solid contents of the first uv-absorbing material 121B and the second uv-absorbing material 121c, as shown in the following table (two) of samples B1 to B4.

Watch 2

As can be seen from table (two), when the sum of the solid contents of the first ultraviolet light absorbing material 121b and the second ultraviolet light absorbing material 121c is between 16% and 23%, the ultraviolet light cut-off wavelength of the filter 100b is between 404 nm and 419 nm; the average transmittance of the filter 100b in the wavelength range of 350 nm to 395 nm is between 0.09% and 0.43%; and the average transmittance of the filter 100b in the wavelength range of 430 nm to 450 nm is greater than 87%, for example, between 87.4% and 92%.

Therefore, the transmittance of the filter 100b corresponding to the ultraviolet light (e.g., wavelength 350 nm to 395 nm) is lower than 2%, even lower than 1%, so that the filter 100b can filter the ultraviolet light more effectively and can also let most of the visible light (e.g., wavelength 430 nm to 450 nm) penetrate. In addition, it should be noted that in sample B1 in table (two), the solid content of the first uv-absorbing material 121B is zero, so the filter 100B may not include the first uv-absorbing material 121B, i.e., the filter 100B may include only a single uv-absorbing material, i.e., the second uv-absorbing material 121 c.

Fig. 2 is a schematic cross-sectional view of a filter according to another embodiment of the invention. Referring to fig. 2, the filter 200 is similar to the filter 100b in the previous embodiment. For example, both the filter 200 and the filter 100b have a function of filtering ultraviolet light, and include the same components: the filter layer 110 and the anti-reflective layer 130, and in the light absorption portion 220 included in the filter 200, the light absorption portion 220 includes an ultraviolet light absorbing material 221, which may be the ultraviolet light absorbing material 121a in the foregoing embodiment, or a first ultraviolet light absorbing material 121b and a second ultraviolet light absorbing material 121c stacked on each other.

Unlike the optical filter 100B of fig. 1B, the light absorbing part 220 further includes an infrared light absorbing layer 224 formed on the transparent substrate 123, wherein the adhesive layer 122 is disposed between the infrared light absorbing layer 224 and the transparent substrate 123 and adheres the infrared light absorbing layer 224 and the transparent substrate 123, and the infrared light absorbing layer 224 and the ultraviolet light absorbing material 221 may be stacked on each other and disposed between the ultraviolet light absorbing material 221 and the adhesive layer 122. Accordingly, the infrared light absorbing layer 224 and the ultraviolet light absorbing material 221 may not contact the transparent substrate 123. Since the light absorption portion 220 includes the ultraviolet light absorption material 221 and the infrared light absorption layer 224, the filter 200 can not only filter out ultraviolet light, but also filter out infrared light, so as to prevent the ultraviolet light and the infrared light from adversely affecting the color of the image captured by the image sensor.

In addition, in the present embodiment, the ultraviolet light absorbing material 221 is located between the infrared light absorbing layer 224 and the filter layer 110. However, in other embodiments, both the infrared light absorbing layer 224 and the ultraviolet light absorbing material 221 may be interchanged, i.e., the infrared light absorbing layer 224 may be located between the ultraviolet light absorbing material 221 and the filter layer 110. Therefore, the positions of the infrared light absorbing layer 224 and the ultraviolet light absorbing material 221 in fig. 2 are only used for reference, and the ultraviolet light absorbing material 221 is not limited to be located between the infrared light absorbing layer 224 and the filter layer 110.

Fig. 3 is a schematic cross-sectional view of a filter according to another embodiment of the invention. Referring to fig. 3, the optical filter 300 is similar to the optical filter 200 of the previous embodiment, and the optical filter 300 also includes an infrared light absorbing material 324 and at least one ultraviolet light absorbing material, so that the optical filter 300 can filter ultraviolet light and infrared light. The main differences between the filter 300 and the filter 200 are: the light absorbing portion 320 of the filter 300 includes an infrared light absorbing material 324 and at least one ultraviolet light absorbing material that are mixed with each other and distributed in a single film layer.

Specifically, the optical filter 300 includes a light absorption portion 320, and the light absorption portion 320 includes an infrared light absorption material 324 and two ultraviolet light absorption materials, wherein the ultraviolet light absorption materials include a first ultraviolet light absorption material 321a and a second ultraviolet light absorption material 321b, and main components of the first ultraviolet light absorption material 321a and the second ultraviolet light absorption material 321b may be respectively the same as main components of the first ultraviolet light absorption material 121b and the second ultraviolet light absorption material 121 c.

In addition, in the embodiment shown in fig. 3, the light absorption portions 320 include two types of ultraviolet light absorption materials (i.e., the first ultraviolet light absorption material 321a and the second ultraviolet light absorption material 321b), but in other embodiments, only one or more types of ultraviolet light absorption materials may be included in the light absorption portions 320. Therefore, it is emphasized that the light absorption portion 320 shown in fig. 3 is an example, and the light absorption portion 320 is not limited to include only two ultraviolet light absorbing materials.

The light absorbing portion 320 further includes a light transmitting layer 325, which is made of a polymer material, for example, polymethyl methacrylate (PMMA). The filter layer 110 is formed on the transparent layer 325 and located between the filter layer 110 and the anti-reflection layer 130, as shown in fig. 3. The first uv-absorbing material 321a, the second uv-absorbing material 321b and the infrared light-absorbing material 324 are all distributed in the transparent layer 325. Thus, the light absorption portion 320 can absorb the infrared light and the ultraviolet light at the same time, so that the optical filter 300 can effectively filter the infrared light and the ultraviolet light.

Fig. 4 is a schematic diagram of a transmission spectrum of a filter according to at least one embodiment of the invention. Referring to fig. 4, a curve C4 shown in fig. 4 represents a transmission spectrum of the filter in at least one embodiment, such as the transmission spectrum of at least one of the

filters

100a, 100b, 200, and 300 in the previous embodiments. From fig. 4, it can be seen that not only the uv cut-off wavelength of the filter (e.g., the

filter

100a, 100b, 200 or 300) is between 404 nm and 419 nm, but also the ir cut-off wavelength of the filter can be between 615 nm and 635 nm. Next, it can be seen from fig. 4 that the average transmittance of the filter in the wavelength range of 430 nm to 450 nm is greater than 87%, so as to allow most of the visible light to pass through.

In addition, fig. 4 also shows the transmittance of the filter in infrared light and ultraviolet light. According to fig. 4, the average transmittance of the optical filter in the wavelength range of 350 nm to 395 nm is less than 2%, and the average transmittance in the wavelength range of 700 nm to 1200 nm can be less than 1%, wherein the average transmittance of the optical filter in the wavelength range of 700 nm to 725 nm can be less than 2%. Therefore, the optical filter provided by at least one embodiment of the present invention not only can allow most of visible light to pass through, but also can effectively filter infrared light and ultraviolet light, thereby preventing the ultraviolet light and infrared light from adversely affecting the color of the image captured by the image sensor.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited to the above embodiments, and that various changes and modifications can be made by those skilled in the art without departing from the scope of the invention.

Claims

1. An optical filter, comprising:

a light absorption portion including at least one ultraviolet light absorption material, wherein a maximum absorption wavelength of any one of the ultraviolet light absorption materials in an ultraviolet light band is between 365 nm and 380 nm; and

a filter layer formed on the light absorbing part;

wherein the ultraviolet cut-off wavelength of the filter is between 404 nm and 419 nm, the average transmittance of the filter in the wavelength range of 350 nm to 395 nm is less than 2%, and the average transmittance in the wavelength range of 430 nm to 450 nm is more than 87%.

2. The filter of claim 1, wherein the UV-absorbing material is selected from the group consisting of a heterocyclic ring and a phenol group, and the heterocyclic ring contains at least one of oxygen and nitrogen atoms.

3. The filter of claim 1, wherein the maximum absorption wavelength of the uv-absorbing material in the uv band is from 369 nm to 379 nm.

4. The optical filter according to claim 1, 2 or 3, wherein the UV-absorbing material has a solid content of 0.2% to 0.27%.

5. The optical filter according to claim 1, 2 or 3, wherein the UV-absorbing material has a solid content of 16% to 23%.

6. The filter of claim 5, wherein said UV-absorbing material is a plurality of types, and comprises a first UV-absorbing material and a second UV-absorbing material, said first UV-absorbing material having a wavelength of maximum absorption greater than that of said second UV-absorbing material.

7. The filter of claim 5, wherein the weight ratio between the first UV-absorbing material and the second UV-absorbing material is between 0.14 and 0.64.

8. The optical filter according to claim 1, 2, 3, 6 or 7, wherein the light absorbing part further comprises:

a transparent substrate; and

an adhesive layer formed on the transparent substrate and bonding the ultraviolet light absorbing material and the transparent substrate, wherein the adhesive layer has hydrophobicity and the ultraviolet light absorbing material has hydrophilicity.

9. The optical filter according to claim 8, wherein the transparent substrate is a blue glass plate for absorbing infrared light.

10. The filter of claim 8, wherein the material of the transparent substrate comprises at least one of glass and resin.

11. The filter of claim 8, wherein the light absorbing part further includes an infrared light absorbing layer formed on the transparent substrate.

12. The filter of claim 11, wherein the infrared light absorption layer and the ultraviolet light absorption material do not contact the transparent substrate.

13. The optical filter according to claim 1, 2, 3, 6 or 7, wherein the light absorbing portion further comprises a light-transmitting layer, the filter layer is formed on the light-transmitting layer, and the ultraviolet light absorbing material is distributed in the light-transmitting layer.

14. The filter of claim 13, wherein the light absorbing portion further comprises an infrared light absorbing material, and the infrared light absorbing material is distributed in the light transmitting layer.

15. The filter of claim 1, 2, 3, 6 or 7, wherein the infrared cut-off wavelength of the filter is between 615 nm and 635 nm.

16. The filter of claim 1, 2, 3, 6 or 7, wherein the filter has an average transmittance of less than 2% at a wavelength ranging from 700 nm to 725 nm.

17. The filter of claim 1, 2, 3, 6 or 7, wherein the average transmittance of the filter is less than 1% at a wavelength ranging from 700 nm to 1200 nm.

18. The filter of claim 1, further comprising an anti-reflection layer formed on the light absorbing portion.

19. The filter of claim 18, wherein the anti-reflection layer is a multilayer film.

20. The optical filter of claim 1, wherein the filter layer is a multilayer film.