阅读说明：本技术 改善眩光鬼影现象的红外截止滤光器及其制备方法 (Infrared cut-off filter for improving glare ghost phenomenon and preparation method thereof ) 是由 李涛 葛文志 翁钦盛 王懿伟 于 2020-07-16 设计创作，主要内容包括：一种改善眩光鬼影现象的红外截止滤光器,包括折射率为1.45～1.55的基板,所述基板两侧设有光学膜厚为70～100nm、折射率为1.38～1.50的第一膜层,所述第一膜层远离基板的一侧设有光学膜厚为80～110nm、折射率为1.15～1.23的第二膜层；所述基板对于波长在350～395nm范围内的光线的平均透过率≤3％,在425～565nm波段的最小透过率≥70％,在725～1100nm波段的最大透过率≤1.5％,在透过率为50％处的中心波长为640±5nm。本发明的基板可对700～1080nm波段进行深度截止,在基板上进行双面超低反射结构设计,采用涂布工艺,实现在可见光宽带波长范围内获得高性能、超低反射截止膜,减少像面与IRCF之间的发射,且在CRA变化时,可视域波长移位更小,眩光鬼影得到大大改善,解决了市场上手机成像时出现严重眩光鬼影的难题。(An infrared cut filter for improving glare ghost phenomenon comprises a substrate with a refractive index of 1.45-1.55, wherein first film layers with an optical film thickness of 70-100nm and a refractive index of 1.38-1.50 are arranged on two sides of the substrate, and second film layers with an optical film thickness of 80-110 nm and a refractive index of 1.15-1.23 are arranged on one side, away from the substrate, of each first film layer; the average transmittance of the substrate to light with the wavelength within the range of 350-395 nm is less than or equal to 3%, the minimum transmittance of the substrate in the waveband of 425-565 nm is more than or equal to 70%, the maximum transmittance of the substrate in the waveband of 725-1100 nm is less than or equal to 1.5%, and the central wavelength of the substrate at the position where the transmittance is 50% is 640 +/-5 nm. The substrate can carry out depth cutoff on a 700-1080 nm waveband, carries out double-sided ultra-low reflection structure design on the substrate, adopts a coating process, realizes that a high-performance and ultra-low reflection cutoff film is obtained in a visible light broadband wavelength range, reduces emission between an image plane and IRCF, has smaller visible domain wavelength shift when CRA changes, greatly improves glare ghost, and solves the problem of serious glare ghost when mobile phone imaging is carried out in the market.)

1. An infrared cut filter for improving a phenomenon of glare ghost, comprising: the optical film comprises a substrate with a refractive index of 1.45-1.55, wherein first film layers with the optical film thickness of 70-100nm and the refractive index of 1.38-1.50 are arranged on two sides of the substrate, a second film layer with the optical film thickness of 80-110 nm and the refractive index of 1.15-1.23 is arranged on one side, far away from the substrate, of the first film layer, and the refractive indexes are refractive indexes with the reference wavelength of 550 nm; the substrate has the average transmittance of less than or equal to 3% for light with the incident angle of 0 DEG and the wavelength of 350-395 nm, the minimum transmittance of more than or equal to 70% in a band of 425-565 nm, the average transmittance of more than or equal to 84%, the average transmittance of less than or equal to 2.5% in a band of 700-725 nm, the average transmittance of less than or equal to 0.5% in a band of 725-1100 nm, the maximum transmittance of less than or equal to 1.5%, and the central wavelength of 410 +/-5 nm or/and 640 +/-5 nm at the position where the transmittance is 50%.

2. The infrared cut filter for improving the phenomenon of glare ghost according to claim 1, wherein the substrate is mainly prepared from a silicon element-containing resin material.

3. The infrared cut filter for improving the phenomenon of glare ghosting according to claim 1 or 2, wherein: the substrate is mainly prepared from raw materials containing silicone resin.

4. The infrared cut filter for improving the phenomenon of glare ghosting of claim 1, wherein the first film layer consists essentially of an oxide containing silicon or a compound containing magnesium, and the second film layer consists essentially of hollow fine particles containing Si.

5. The infrared cut filter for improving the phenomenon of glare ghosting according to claim 1 or 4, wherein: the first film layer is SiO₂Or MgF₂The second film layer is mainly hollow SiO₂。

6. The infrared cut filter for improving the phenomenon of glare ghost according to claim 4, wherein the hollow fine particles containing Si have an average particle size of 50 nm.

7. The infrared cut filter for improving the phenomenon of glare ghosting of claim 1, wherein: the reflectivity of the first film layer and the second film layer to the light with the incident angle of 0 degree and the wavelength of 400 nm-700 nm is less than or equal to 0.6 percent, the average reflectivity is less than or equal to 0.21 percent, and the wave band at the lowest point of the curve is 500 +/-10 nm.

8. The method of manufacturing an infrared cut filter for improving a phenomenon of glare ghost according to claim 1, wherein: the method comprises the following preparation steps:

1) carrying out ultrasonic cleaning on the substrate, and centrifugally drying;

2) plating a first film layer on one side of the substrate in a sputtering mode, and centrifugally cleaning;

3) plating a first film layer on the other side of the substrate in a sputtering mode, and centrifugally cleaning;

4) vacuum adsorption is carried out on the periphery, the base material coated with the first film layer is placed on a coating table, AR ink with low refractive index is dripped on the surface of the first film layer of the base material under the condition of high-speed rotation, coating is carried out to form a second film layer, the base plate is turned over after one surface is coated, and the second film layer is formed on the other surface after the other surface is coated;

5) after finishing coating the double-sided AR ink, baking in vacuum;

6) pasting a UV film, and baking in a vacuum oven;

7) and cutting the cutter wheel into finished products.

9. The method of claim 8, wherein the AR ink has a vacuum baking temperature of 70-90 ℃ and the UV film has a vacuum baking temperature of 45 ℃.

10. The method of manufacturing an infrared cut filter for improving a phenomenon of glare ghost according to claim 8, wherein: and the vacuum adsorption in the step 4) is to suck the edge of the substrate in a suction hole groove arranged on the coating table for fixing.

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of optics, in particular to an infrared cut-off filter for improving a glare ghost phenomenon of a camera module and a preparation method thereof in the field of camera modules.

[ background of the invention ]

The camera module (CCM) is a core device for various novel portable camera equipment, is mainly applied to the fields of mobile phones, notebook computers, tablet computers, smart homes, vehicles, VR/AR, safety monitoring and the like, and has the advantages of miniaturization, low power consumption, low cost, high image quality and the like compared with the traditional camera system.

The imaging process of the camera is the process of digitizing the optical signal. The light firstly passes through the lens and reaches a photosensitive element (CCD or CMOS), the light is converted into a digital signal, and then the digital signal is transmitted to a processor (DSP), and the digital signal is subjected to image signal enhancement and compression optimization and then transmitted to a mobile phone or other storage devices. The camera module mainly comprises a glass Cover plate (Cover), a Lens (Lens), an infrared cut Filter (IRCF or IR Filter), an image Sensor (Sensor) and a Flexible Printed Circuit (FPC).

When the lens is affected by some non-ideal factors during the image transmission process, the light error can be deflected to cause aberration, and glare (Flare) and/or Ghost (Ghost) phenomena can occur. Glare and/or ghosting are directly related to the properties of the surface of the optical element. Most of optical elements such as lenses and optical filters included in an optical system use a transparent member such as optical glass or optical plastic as a substrate, and when the refractive index of the substrate increases, the reflectance of the light incident surface and the light emitting surface increases, and the amount of effective light reaching the image surface decreases; meanwhile, the phenomenon of internal reflection and re-reflection cannot be avoided among the optical elements, and finally the optical elements are incident on an image surface to form ghost images, so that the imaging quality and the user experience are seriously influenced.

There are two major improvements currently on the market to the glare and/or ghost problem: one is to optimize the coating process of the optical element and the dispersion correction of the lens by design (hardware mode), and the other is to perform software post correction (software mode). For example, CN106662676A discloses a camera module and a terminal, which includes an optical protection window, an infrared cut filter and an anti-reflection coating, where the anti-reflection coating includes several tapered anti-reflection structures, the diameter of the bottom of the anti-reflection structure is 40 nm-150 nm, the diameter of the top of the anti-reflection structure is 0-30% of the diameter of the bottom of the anti-reflection structure, the height of the anti-reflection coating is 150 nm-300 nm, two adjacent tapered anti-reflection structures have the wavelength of 1/5-1/3 of the visible light band, and the anti-reflection coating structure is set to reduce the light reflection, so as to solve the problems of ghost and glare; for another example, CN104299188B discloses an image correction method and system, in which an area in which a ghost and/or a glare are located in an image is determined according to a brightness value of each pixel in the image, and the area is processed by using methods such as opening operation, closing operation, and area filling, so as to correct the ghost and the glare in the image in a software manner. However, any means can only be applied to specific application environments, and cannot meet the requirements of the existing micro-miniature camera module (such as a mobile phone) on glare/ghost elimination.

For a micro camera module in an application environment such as a mobile phone, there are mainly 4 reflections, i.e., reflection between a Lens (Lens) and a Cover, reflection between lenses (Lens), reflection between an infrared cut filter (IRCF) and a Lens (Lens), and reflection between an image plane (Sensor side) and an infrared cut filter (IRCF), which are reflections caused by incident light entering the camera module, as shown in fig. 1.

The imaging problems caused by the above four reflections and the existing solutions are as follows:

the ghost image caused by the reflection between the Lens (Lens) and the Cover generally takes a visible part as a main part, the color is white or blue-green, the color is common, the shape is similar to that of an original object, and the existing common solution is to plate an AR (anti-reflection) film to reduce the reflection.

Secondly, the reflection between lenses (Lens) easily causes the formation of a string of spot images (glare), and because the reflected light rays causing the problem are all visible light parts, the spot images cannot be effectively improved through IRCF (infrared reflection filter), but the reflection can be reduced through coating, and the reflected light rays cannot be imaged on an image plane to be improved through the design of a Lens light path.

③ the reflection between the infrared cut filter (IRCF) and the Lens (Lens) causes the corner red light. For the incident light rays with different angles, the coating curve can have the offset phenomenon; the larger the angle of incidence, the larger the offset; the deviation of this part of the wavelength light is the main reason for the formation of corner red light. When large-angle incident light is reflected by a micro lens (Microlens) on the image surface, the light may re-pass through an infrared cut filter (IRCF) at a small angle, and most of the light wavelength is large-angle and small-angle offset partial wavelength (the offset partial wavelength is generally concentrated in a wavelength band of 600-700 nm), a corner red ghost is formed on the image surface. Since the wavelengths of the light forming the part of the ghost image mostly coincide with the absorption area of the blue glass, the part of the reflected light is reduced by the IRCF of the blue glass so as to improve the phenomenon.

The reflection between the image plane and the infrared cut-off filter (IRCF) can cause petal-shaped red ghost, the reason similar to the reason for forming corner red ghost is that after the incident light is reflected by the micro lens (microlenses), the incident light can be reflected back to the infrared cut-off filter (IRCF) at a large angle, and the light with the same large angle can reflect the partial light of the offset waveband to the image plane, and the petal-shaped ghost is formed after multiple reflections. The prior art also uses blue glass IRCF to attenuate this portion of the reflected light to ameliorate this phenomenon.

However, the existing infrared cut-off filter in the market adopts a film coating method, one surface is coated with AR, the other surface is coated with IR, the cost is high, the reflectivity of the AR surface and the IR surface is high, the emission between the image surface and the IRCF (infrared cut-off filter) is large, when the CRA (main incident angle) changes, the visible domain wavelength shift is large, the problem of ghost of light is serious during imaging, Ripple is serious (as shown in fig. 6), and the problem cannot be effectively improved only by using blue glass which has absorption characteristics for the offset part of light reflected by the IR surface, which becomes one of the main factors for limiting the imaging effect of the current miniature camera module; in order to obtain low reflectivity and high absorptivity, the existing blue glass infrared cut filter needs to be coated for many times, and the coating process is complex and needs to be further improved.

[ summary of the invention ]

The invention provides an infrared cut-off filter for improving a glare ghost phenomenon, which can effectively solve the glare/ghost problem in the imaging process of the existing mobile phone camera module. The invention also provides a preparation method of the infrared cut-off filter, which simplifies the preparation process and reduces the production cost.

The technical solution of the invention is as follows: an infrared cut-off filter for improving a glare ghost phenomenon comprises a substrate with a refractive index of 1.45-1.55, wherein first film layers with an optical film thickness of 70-100nm and a refractive index of 1.38-1.50 are arranged on two sides of the substrate, a second film layer with an optical film thickness of 80-110 nm and a refractive index of 1.15-1.23 is arranged on one side, away from the substrate, of each first film layer, and the refractive indexes are refractive indexes with a reference wavelength of 550 nm; the average transmittance of the substrate to light with the incident angle of 0 DEG and the wavelength of 350-395 nm is less than or equal to 3%, the transmittance of the substrate in a 350-380 nm band is less than or equal to 0.7%, the minimum transmittance in a 400-420 nm band is greater than or equal to 28%, the minimum transmittance in a 425-565 nm band is greater than or equal to 70%, the average transmittance is greater than or equal to 84%, the transmittance in a 450-600 nm band is greater than or equal to 80%, the average transmittance in a 700-725 nm band is less than or equal to 2.5%, the transmittance in a 755-1000 nm band is less than or equal to 0.2%, the average transmittance in a 725-1100 nm band is less than or equal to 0.5%, the maximum transmittance is less than or equal to 1.5%, the average transmittance in a 900-1000 nm band is less than or equal to 0.1%, the maximum transmittance is less than or equal to 0.2%, and the center wavelength at the transmittance of 50% is 410.

The structure of the invention can realize that a high-performance and ultra-low reflection cut-off film can be obtained in the wavelength range of the visible light broadband, the refractive index of the substrate is greater than the refractive index of the first film layer and greater than the refractive index of the second film layer, thereby reducing the sensitivity of the reflection characteristic, simultaneously, the substrate can realize the efficient passing of the visible light and the deep cut-off in the wave band of 750-1080 nm, the process of realizing the function by plating the film on the substrate in the existing market is cancelled, the structure is simplified, the effect is improved, and the infrared cut-off filter with the structure can effectively improve the glare/ghost problem when the existing mobile phone camera module is used for imaging, thereby greatly improving the imaging quality.

Preferably, the substrate is mainly prepared from a silicon-element-containing resin raw material.

Preferably, the substrate is prepared mainly from a raw material containing a silicone resin.

Preferably, the first film layer is mainly composed of an oxide containing silicon or a compound containing magnesium, and the second film layer is mainly composed of hollow fine particles containing Si.

Preferably, the first film layer is SiO₂Or MgF₂The second film layer is mainly hollow SiO₂。

Preferably, the average particle diameter (D) of the Si-containing hollow fine particles₅₀) Is 50 nm.

Preferably, the first film layer and the second film layer have the reflectivity of less than or equal to 0.6 percent and the average reflectivity of less than or equal to 0.21 percent for light rays with the incident angle of 0 degree and the wavelength of 400 nm-700 nm, and the wave band at the lowest point of the curve falls within 500 +/-10 nm.

A method for preparing an infrared cut filter for improving a glare ghost phenomenon includes the following steps:

1) carrying out ultrasonic cleaning on the substrate, and centrifugally drying;

2) plating a first film layer on one side of the substrate in a sputtering mode, and centrifugally cleaning;

3) plating a first film layer on the other side of the substrate in a sputtering mode, and centrifugally cleaning;

4) vacuum adsorption is carried out on the periphery, the base material coated with the first film layer is placed on a coating table, AR ink with low refractive index is dripped on the surface of the first film layer of the base material under the condition of high-speed rotation, coating is carried out to form a second film layer, the base plate is turned over after one surface is coated, and the second film layer is formed on the other surface after the other surface is coated;

5) after finishing coating the double-sided AR ink, baking in vacuum;

6) pasting a UV film, and baking in a vacuum oven;

7) and cutting the cutter wheel into finished products.

Preferably, the AR ink is baked at a vacuum baking temperature of 70-90 ℃ and the UV film is baked at a vacuum baking temperature of 45 ℃.

Preferably, the vacuum suction in step 4) is performed by sucking and fixing the edge of the substrate to a suction hole groove provided in the coating table.

The invention has the following beneficial effects:

1. the minimum transmittance of the substrate adopted by the invention in the wave band of 425-565 nm is more than or equal to 70 percent, the transmittance in the 700-725 nm wave band is less than or equal to 2.5 percent, the average transmittance in the 725-1100 nm wave band is less than or equal to 0.5 percent, the maximum transmittance is less than or equal to 1.5 percent, the transmittance in the 755-1000 nm wave band is less than or equal to 0.2 percent, the central wavelength at the 50 percent transmittance is 640 +/-5 nm, the high-performance and ultralow-reflection cut-off film is obtained in the visible light broadband wavelength range by combining the design of a double-sided ultralow-reflection structure, namely a first film layer with the refractive index of 1.38-1.50 and a second film layer with the refractive index of 1.15-1.23, the reflection between an image plane and an IRCF (infrared cut-off filter) is reduced, and when the CRA (main incidence angle) is changed, the wavelength shift of the visible domain is smaller (as shown in fig. 5), the glare/ghost phenomenon of the camera module is greatly improved, especially the petal-shaped ghost, and the problem of serious glare/ghost phenomenon in mobile phone imaging in the market is solved.

2. The invention has simple design structure, only comprises the substrate, the first film layer and the second film layer, adopts the coating processing technology, and adopts the hollow SiO₂Through AR printing ink dropwise add to the rotatory base plate dispersion coating at a high speed, can guarantee that the printing ink layer coating is even, avoids appearing badly such as radially, color spot, stripe, and the process flow is short, and coating efficiency is high, can control the coating layer thickness better, and the cost of manufacture is low, has two-sided ultralow reflection effect, and the membrane firmness is excellent.

[ description of the drawings ]

FIG. 1 illustrates the reflection of light in a conventional camera module;

FIG. 2 is a schematic diagram of a filter according to a first embodiment;

FIG. 3 is a graph showing transmittance characteristics of a substrate according to the first embodiment;

fig. 4 is a reflectance characteristic diagram of the infrared cut filter of the first embodiment at different incident angles (0 ° and 30 °);

fig. 5 is a graph showing transmittance characteristics at different incident angles (0 ° and 30 °) of the infrared cut filter of the first embodiment;

fig. 6 is a reflectance characteristic diagram of a conventional infrared cut filter at different incident angles (0 ° and 30 °);

FIG. 7 shows the effect of a conventional camera module (not shown) in a darkroom;

fig. 8 shows the effect of the camera module using the ir-cut filter according to the first embodiment on the lamp in the dark room (color not shown);

FIG. 9 is a schematic cross-sectional view illustrating a combination of a substrate and a UV film with an iron ring according to an embodiment.

Description of the labeling: 1-a substrate; 2-a first film layer; 3-a second film layer; 4-UV film; 5-iron ring.

[ detailed description ] embodiments

The present invention will be described in further detail with reference to the following examples, but the present invention is not limited to the following examples.

The following examples are not provided to limit the scope of the present invention, nor are the steps described to limit the order of execution, and the directions described are limited to the drawings. Modifications of the invention which are obvious to those skilled in the art in view of the prior art are also within the scope of the invention as claimed.