Infrared cut-off filter structure

Abstract

An infrared cut-off filter structure includes a glass substrate, a first multilayer film, and a second multilayer film. The first multilayer film is disposed on the upper side of the glass substrate and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, such that the first multilayer film has an optical density of OD3 to OD7 for light with an incident angle of 0 degrees and 30 degrees and a wavelength range of 900 nm to 1100 nm. The second multilayer film is disposed on the lower side of the glass substrate and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, such that the second multilayer film has an optical density of OD3 to OD6 for light with a wavelength range of 700 nm to 900 nm. The thus-formed infrared cut-off filter can achieve a transmittance of 0.1% to 0.00001% for light with a wavelength range of 700 nm to 1100 nm.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared cut-off filter structures, and particularly to an infrared cut-off filter structure that can effectively filter infrared light and transmit visible light, thereby generating a normal color image. Background Art

[0002] With the development of high-end smart phones, the requirements for the camera modules of mobile phones are getting higher and higher. In the camera module, an infrared cut-off filter is usually provided in front of a CCD (Charge-Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) image sensor to filter infrared light and transmit visible light, so that it can generate a normal color image (that is, the color seen by the average human eye, without color distortion). Therefore, the infrared cut-off filter is a key component in the camera module. As the pixel of the mobile phone gets higher and higher, more stringent requirements are put forward for the infrared cut-off filter, especially for the color reproducibility and clarity of imaging without noise. The visible light wavelength range that can be recognized by the average human eye is between 320nm and 760nm. Light waves outside the range of 320nm to 760nm cannot be seen by the human eye, but the imaging elements CCD or CMOS of the camera can see light of most wavelengths. Due to the participation of various lights, there is a deviation in the color restored by the camera module from that seen by the naked eye. For example, green plants become grayish white, red pictures become light red, and black becomes purple. As mentioned above, it is particularly important to use the infrared light cut-off function of an excellent infrared cut-off filter to improve the original color of the imaging as close to perfection.

[0003] For the known infrared cut-off filter structures, such as the patents announced in Taiwan, China, No. I557439 and I557440, the best effect of their structural design can only make the transmittance of light with wavelengths of 850 - 1300nm (infrared light) less than but close to 1%. This transmittance range was acceptable for the camera modules of early mobile phones with relatively low requirements. However, as the pixel of the mobile phone gets higher and higher, there will be a significant deviation in the color restored by the current camera module from that seen by the naked eye. Therefore, the infrared filtering effect achieved by this known infrared cut-off filter structure is no longer sufficient for the camera modules of current high-end mobile phones.

[0004] In view of this, the inventor of the present invention deeply considered the above problems, actively studied and improved, and developed and designed the present invention through trial production. Summary of the Invention

[0005] The main object of the present invention is to effectively filter infrared light and transmit visible light, so that the camera module of current high-pixel mobile phones can restore normal color images, and an infrared cut-off filter structure is provided.

[0006] To achieve the above object, the technical solution adopted by the present invention is: an infrared cut-off filter structure, which includes a glass substrate, a first multilayer film and a second multilayer film; wherein, the first multilayer film is disposed on the upper side of the glass substrate and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, so that the optical density of the first multilayer film for light in the wavelength range of 900 nm to 1100 nm at incident angles of 0 degrees and 30 degrees is OD3 to OD7. The second multilayer film is disposed on the lower side of the glass substrate and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, so that the optical density of the second multilayer film for light in the wavelength range of 700 nm to 900 nm is OD3 to OD6.

[0007] The infrared cut-off filter structure provided by the present invention, through the infrared cut-off filter formed by its special structural design, can make the transmittance of light (infrared light) in the wavelength range of 700 nm to 1100 nm reach 0.1% to 0.00001%, so it can effectively filter infrared light and transmit visible light, and then produce normal color images, which can meet the requirements of the camera module of high-end mobile phones. Description of the Drawings

[0008] Figure 1 It is a schematic structural diagram of the present invention.

[0009] Figure 2 It is a transmittance spectrogram of the first multilayer film of the present invention.

[0010] Figure 3 It is an optical density spectrogram of the first multilayer film of the present invention.

[0011] Figure 4 It is a transmittance spectrogram of the second multilayer film of the present invention.

[0012] Figure 5 It is an optical density spectrogram of the second multilayer film of the present invention.

[0013] Figure 6 It is a transmittance spectrogram when the glass substrate of the present invention is traditional white glass.

[0014] Figure 7 It is an optical density spectrogram when the glass substrate of the present invention is traditional white glass.

[0015] Figure 8 It is a transmittance spectrogram of the blue glass of the present invention.

[0016] Figure 9It is the transmittance spectrum diagram when the glass substrate of the present invention is blue glass.

[0017] Figure 10 It is the optical density spectrum diagram when the glass substrate of the present invention is blue glass.

[0018] Figure 11 It is the transmittance spectrum diagram of the blue glass-like of the present invention.

[0019] Figure 12 It is the transmittance spectrum diagram when the glass substrate of the present invention is blue glass-like.

[0020] Figure 13 It is the optical density spectrum diagram when the glass substrate of the present invention is blue glass-like.

[0021] In each of the above optical density spectrum diagrams, the ordinate OD refers to the cut-off depth (Optical Density).

[0022] Symbol Explanation:

[0023] 10: Glass substrate

[0024] 20: First multi-layer film

[0025] 30: Second multi-layer film. Detailed Embodiment

[0026] Please refer to Figure 1 as shown, showing that the infrared cut-off filter structure of the present invention includes a glass substrate 10, a first multi-layer film 20 and a second multi-layer film 30, wherein:

[0027] The glass substrate 10 has a thickness of 0.1 mm to 1.1 mm and can be a traditional white glass (First Embodiment), blue glass (Second Embodiment) or blue glass-like with an infrared light absorbing organic film layer coated on the white glass (Third Embodiment).

[0028] The first multi-layer film 20 is formed on the upper side of the glass substrate 10 by using physical vapor deposition (PVD) and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, so that the optical density of the first multi-layer film 20 for light with an incident angle of 0 degrees and 30 degrees and a wavelength range of 900 nm to 1100 nm is OD3 to OD7 (please refer to Figure 2 and Figure 3As shown). The high refractive index material is one or more oxides with a refractive index of 2 to 3 and an extinction coefficient close to 0 in the wavelength range of 300 nm to 1100 nm, such as Ti3O5, TiO2, Ta2O5, Nb2O5, etc. The low refractive index material is one or more oxides with a refractive index of 1.3 to 2 and an extinction coefficient close to 0 in the wavelength range of 300 nm to 1100 nm, such as SiO2, MgF2, etc. The structure of the first multilayer film 20 in a preferred embodiment is as shown in Table 1 below:

[0029] Table 1 Structure Table of the First Multilayer Film

[0030]

[0031] The second multilayer film 30 is formed on the lower side of the glass substrate 10 by means of physical vapor deposition (PVD) of vacuum coating, and is formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, so that the optical density of the second multilayer film 30 for light in the wavelength range of 700 nm to 900 nm is OD3 to OD6 (please refer to Figure 4 and Figure 5 as shown). The high refractive index material is one or more oxides with a refractive index of 2 to 3 and an extinction coefficient close to 0 in the wavelength range of 300 nm to 1100 nm, such as Ti3O5, TiO2, Ta2O5, Nb2O5, etc. The low refractive index material is one or more oxides with a refractive index of 1.3 to 2 and an extinction coefficient close to 0 in the wavelength range of 300 nm to 1100 nm, such as SiO2, MgF2, etc. The structure of the second multilayer film 30 in a preferred embodiment is as shown in Table 2 below:

[0032] Table 2 Structure Table of the Second Multilayer Film

[0033]

[0034] In this way, the formed infrared cut-off filter can make the transmittance of light (infrared light) in the wavelength range of 700 nm to 1100 nm reach 0.1% to 0.00001%, so it can effectively filter out infrared light and transmit visible light, and then produce normal color images, thus meeting the requirements of the camera module of high-end mobile phones.

[0035] In the first embodiment, that is, when the glass substrate 10 is a traditional white glass, the first multilayer film 20 is provided on the upper side of the glass substrate 10, and the second multilayer film 30 is provided on the lower side of the glass substrate 10, the transmittance spectrum diagram of the formed infrared cut-off filter is as shown in Figure 6 as shown, and the optical density spectrum diagram is as shown in Figure 7 as shown.

[0036] In the second embodiment, i.e., the glass substrate 10 is blue glass, when the first multilayer film 20 is provided on the upper side of the glass substrate 10 and the second multilayer film 30 is provided on the lower side of the glass substrate 10, the material property of the blue glass itself is that it has an absorption effect on near-infrared light, and there is a very small shift in the 0-degree angle and 30-degree angle at the position of T50% of about 640 nm ± 10 nm. Its transmittance spectrogram is as shown in Figure 8 shown, and the transmittance spectrogram of the infrared cut-off filter formed thereby is as shown in Figure 9 shown, and the optical density spectrogram is as shown in Figure 10 shown.

[0037] In the third embodiment, i.e., the glass substrate 10 is blue-like glass, when the first multilayer film 20 is provided on the upper side of the glass substrate 10 and the second multilayer film 30 is provided on the lower side of the glass substrate 10, the material property of the blue-like glass itself is that it has an absorption effect on the near-infrared light region, and there is a very small shift in the 0-degree angle and 30-degree angle at the position of T50% of about 640 nm ± 10 nm. Its transmittance spectrogram is as shown in Figure 11 shown, and the light cut-off rate OD3 - OD6 of the infrared cut-off filter formed thereby in the wavelength range of 700 nm to 1100 nm, and the T50% offset is less than 5 nm. Its transmittance spectrogram is as shown in Figure 12 shown, and the optical density spectrogram is as shown in Figure 13 shown.

Claims

1. An infrared cut-off filter structure, characterized in that, It includes: A glass substrate, which is a traditional white glass; A first multi-layer film, disposed on the upper side of the glass substrate, formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, such that the optical density of the first multi-layer film for light with an incident angle of 0 degrees, 30 degrees, and wavelengths in the range of 900 nm to 1100 nm is OD3 to OD7; and A second multi-layer film, disposed on the lower side of the glass substrate, formed by alternately stacking a plurality of high refractive index materials and a plurality of low refractive index materials, such that the optical density of the second multi-layer film for light in the wavelength range of 700 nm to 900 nm is OD3 to OD6; The structure of the first multi-layer film is as shown in Table 1 below: Table 1 Structure Table of the First Multi-layer Film ； The structure of the second multi-layer film is as shown in Table 2 below: Table 2 Structure Table of the Second Multi-layer Film 。 2. The infrared cut-off filter structure according to claim 1, characterized in that, An infrared light-absorbing organic film layer is plated on the glass substrate to form a blue-like glass substrate.

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