CN108700688B - Laminated structure of glass cover plate, camera structure and imaging device - Google Patents

Laminated structure of glass cover plate, camera structure and imaging device Download PDF

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Publication number
CN108700688B
CN108700688B CN201780013236.0A CN201780013236A CN108700688B CN 108700688 B CN108700688 B CN 108700688B CN 201780013236 A CN201780013236 A CN 201780013236A CN 108700688 B CN108700688 B CN 108700688B
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light
film
glass cover
infrared light
camera
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CN108700688A (en
Inventor
小泉达也
小泉直哉
岛田修一
长谷川大刀夫
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Optorun Co Ltd
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Optorun Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/113—Anti-reflection coatings using inorganic layer materials only
    • G02B1/115—Multilayers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/18—Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B11/00—Filters or other obturators specially adapted for photographic purposes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/02—Bodies
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Studio Devices (AREA)
  • Blocking Light For Cameras (AREA)
  • Optical Filters (AREA)
  • Surface Treatment Of Optical Elements (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

The present invention provides a laminated structure of a glass cover plate for protecting an internal structure of an image forming apparatus, such as an information communication device, from the outside, comprising: a transparent substrate which transmits light; a near-infrared light absorbing film that absorbs light in the near-infrared region; and a near-infrared light reflecting film that reflects light in the near-infrared region. Thereby providing a new camera structure that eliminates the filter.

Description

Laminated structure of glass cover plate, camera structure and imaging device
Technical Field
The present invention relates to a laminated structure of a glass cover plate provided to an image forming apparatus.
Background
In the imaging apparatus, i.e., a camera, an imaging apparatus using a solid-state imaging element (imaging element), i.e., a so-called digital camera, has become the mainstream in the present century. In recent years, information communication devices such as Personal Computers (PCs), tablet PCs, and smart phones have become widespread and become devices for daily use. Many of these information communication devices incorporate a small camera module, and a high-performance device having an imaging element with a number of pixels exceeding 1000 ten thousand has been developed (see fig. 11 a). Information communication devices, particularly smart phones as mobile communication devices, are strongly becoming thinner and lighter, and camera modules as components thereof are also required to be short in length in the optical axis direction, and are also strongly required to be compact and space-saving.
In the present specification, an internal mechanism of an imaging device necessary for imaging, such as a lens unit including an optical lens group, a lens holder, an imaging element, and a magnet holder, is defined as a camera module. In addition, a structure including a glass cover plate that protects the internal mechanism of the imaging device from the outside in the camera module is defined as a camera structure.
As shown in fig. 11B, the camera module 1 is mainly composed of a lens unit 50, a lens holder 40, a magnet holder 30, a filter 60, and an imaging element 70 (see, for example, japanese patent application laid-open No. 2013-153361). Among them, the optical filter mainly plays a role of blocking light in a near infrared region. The human eye has sensitivity to light (visible light) in the visible light region having a wavelength of 380nm to 780 nm. On the other hand, the imaging element generally has sensitivity to light of longer wavelengths including visible light, i.e., light having a wavelength up to about 1.1 μm. Therefore, if an image captured by the imaging element is directly photographed, natural color tones are not seen by human eyes, resulting in discomfort. Therefore, the camera module is configured to incorporate a filter (near-infrared light cut filter) for blocking light in the near-infrared region.
As the near-infrared light cut filter, for example, a glass containing phosphate or fluorophosphate, which absorbs light in the near-infrared region, called blue glass, can be used.
Disclosure of Invention
Technical problem
As described above, the camera module 1 is strongly required to be downsized and to be space-saving, and therefore, the length D1 of the camera structure including the camera module 1 is intended to be shortened and thinned (see fig. 11B). As one of the methods, a thin filter has been developed for the filter 60, but the blue glass has low strength, and is technically difficult to be processed into a thin plate of 0.2mm or less, and is fragile, so that the thin filter is difficult to handle. Further, if granular dust called particles generated in the thinning and polishing process or the mounting process falls on the image forming element disposed directly below the filter, the image quality is degraded. The production of a thin, low-particle, high-quality near-infrared cut filter using blue glass itself leads to poor yield and high cost. The present invention has been made in view of such circumstances, and it is desirable to provide a new camera structure in which a filter is omitted.
Technical scheme
(1) The present invention provides a laminated structure of a glass cover plate for protecting an internal mechanism of an imaging device from external influences, the laminated structure comprising: a transparent substrate which transmits light; a near-infrared light absorbing film that absorbs light in the near-infrared region; and a near-infrared light reflecting film that reflects light in the near-infrared region.
According to the invention of the above (1), the glass cover plate for protecting the internal mechanism of the imaging device such as a digital camera from the outside can block the light in the near infrared ray region, and the effect of improving the image without incorporating the near infrared ray cut filter in the camera is achieved.
(2) The present invention provides the laminated structure of the glass cover plate according to the above (1), wherein the transparent substrate is crystallized glass.
According to the invention (2), a high-strength glass cover plate having good processability and high impact resistance can be produced.
(3) The present invention provides the laminated structure of the glass cover plate according to the item (1) or (2), wherein the near-infrared light absorbing film contains an organic dye.
According to the invention of the above (3), there is no incident angle dependency with respect to light absorption without using a commonly used blue glass as a material of a filter for absorbing light in the near infrared region, and an effect of being able to block light in the near infrared region is obtained.
(4) The present invention provides the laminated structure of a glass cover plate according to any one of the above (1) to (3), wherein the near-infrared light reflecting film is a dielectric multilayer film.
The human eye has sensitivity to so-called visible light with wavelengths of 380nm to 780 nm. On the other hand, the imaging element generally has sensitivity to light of longer wavelengths including visible light, i.e., light having a wavelength up to about 1.1 μm. Therefore, if an image captured by the imaging element is directly photographed, a natural color tone is not seen, resulting in discomfort. According to the invention described in the above (4), by providing the near-infrared light reflecting film formed of the dielectric multilayer film, it is possible to block the near-infrared light absorbing film from absorbing light having a wavelength of a length of 700nm or more, which is incomplete, and to obtain an image having a natural color tone.
(5) The present invention provides the laminated structure of a glass cover plate according to the above (4), wherein the dielectric multilayer film is formed by laminating a plurality of kinds of oxide films having different refractive indices, and the adjacent oxide films are different kinds of oxide films.
According to the invention described in the above (5), the wavelength of light to be reflected can be controlled by changing the material, the film thickness, and the number of layers constituting the oxide film.
(6) The present invention provides the laminated structure of a glass cover plate according to any one of the above (1) to (5), further comprising an antireflection film that reflects light in an ultraviolet region and suppresses reflection of light in a visible region.
According to the invention of the above (6), since the glass cover plate for protecting the camera in the apparatus from the outside can block the light in the ultraviolet region, the optical lens formed of the synthetic resin as the constituent member of the camera can be prevented from being deteriorated by the ultraviolet rays, and the incident light can be taken more by the antireflection function for the light in the visible region, and a brighter image can be obtained.
(7) The present invention provides the laminated structure of a glass cover plate according to the above (6), wherein the antireflection film is a dielectric multilayer film and is formed by alternately laminating a nitride film and an oxide film.
Generally, the nitride film has a higher hardness than the oxide film. According to the invention described in the above (7), the use of a nitride film as a material constituting the antireflection film has an effect of improving scratch resistance.
(8) The present invention provides the laminated structure of the glass cover plate according to the item (6) or (7), wherein the antireflection film is formed on a light incidence side with respect to the transparent substrate, and the near-infrared light reflection film and the near-infrared light absorption film are formed in this order from a side farthest from the transparent substrate on a light emission side with respect to the transparent substrate.
According to the invention of the above (8), since the antireflection film that reflects light in the ultraviolet region and suppresses reflection of light in the visible light region is provided on the light incidence side, the near infrared light absorption film formed on the imaging element side of the antireflection film is prevented from being deteriorated by light in the ultraviolet region. Further, since the near-infrared light reflecting film is provided on the light emission side and on the side farthest from the transparent substrate, there is an effect that substances deteriorated by moisture or the like are less likely to enter the near-infrared light absorbing film formed on the transparent substrate side than the near-infrared light reflecting film.
(9) The present invention provides the laminated structure of a glass cover plate according to any one of the above (1) to (7), further comprising an antifouling coating film for preventing contamination from the outside on the outermost side of the light incidence side.
The glass cover of the imaging device is frequently contaminated by daily contact with clothing, fingers, and the like. If the glass cover plate is contaminated, it causes deterioration of an image photographed by the camera. According to the invention of the above (9), the outermost side of the glass cover plate is covered with the antifouling coating film, whereby the stain is easily removed and an image with excellent image quality is always captured.
(10) The present invention provides the laminated structure of the glass cover plates described in (1) to (9), wherein the image forming apparatus is an information communication device, and the glass cover plates are continuously provided in a housing of the information communication device.
According to the invention of the above (10), in the case of a camera attached to an information communication device such as a tablet PC or a smartphone, light in the near infrared region can be blocked by adding a filter function to a glass cover plate which mainly plays a role of protecting internal mechanisms from the viewpoint of contamination or impact. Further, a significant effect of improving an image is obtained without incorporating a near infrared light cut filter in the camera. This effect is particularly great for a camera module of a smartphone, which is a mobile communication terminal for which miniaturization of the camera module is strongly demanded.
(11) The present invention provides a camera structure including a glass cover plate having a laminated structure of the glass cover plates described in (1) to (9), the camera structure including: an optical lens group disposed on the side of the glass cover plate; and an imaging element that receives light incident through the glass cover plate and the optical lens group, and a near infrared light cut filter that cuts off light in a near infrared region is not disposed between optical paths from the optical lens group to the imaging element.
According to the invention of the above (11), since the near-infrared light cut filter does not need to be built in, the length of the entire camera structure can be shortened and the camera can be miniaturized, and since the near-infrared light cut filter is not arranged in the vicinity of the imaging element, a remarkable effect is obtained in that the granular trash (particles) attached to the surface of the filter does not fall onto the surface of the imaging element and the image is deteriorated in the manufacturing process of the near-infrared light cut filter. In addition, in the assembly process of the camera module, a process for arranging and assembling the near-infrared light cut filter is not required, which is advantageous in further reducing the cost, improving the yield, and improving the operation efficiency.
(12) The present invention provides an imaging device having the camera structure described in (11) above.
According to the invention described in (12) above, since light in the near-infrared region can be blocked by the glass cover plate, an imaging device having a small and inexpensive camera structure without incorporating a near-infrared light cut filter can be realized.
(13) The present invention provides a laminated structure of a glass cover plate for protecting an internal mechanism of an imaging device from external influences, the laminated structure comprising: a transparent substrate which transmits light; and a near-infrared light reflecting film that reflects light in the near-infrared region.
According to the invention of the above (13), since the glass cover plate has the near-infrared light reflecting film that reflects light, it is possible to achieve an effect of preventing near-infrared light from outside from entering the internal mechanism of the imaging device. Further, since it is not necessary to place a member having a near-infrared light reflecting film in a region close to the imaging element, reflection of light incident on an internal mechanism of the imaging device can be suppressed, and as a result, stray light is suppressed, and a significant effect of reducing causes of ghost and flare can be obtained.
(14) The present invention provides the laminated structure of a glass cover plate described in the above (13), further comprising an antireflection film that reflects light in an ultraviolet region and prevents reflection of light in at least a visible light region.
According to the invention of item (14), since the glass cover plate for protecting the internal mechanism of the imaging device from the outside can block the light in the ultraviolet range, it is possible to prevent the optical lens or the like formed of synthetic resin, which is a component of the camera, from being deteriorated by ultraviolet rays, which is advantageous for the long life. Further, since the glass cover has an antireflection function for preventing reflection of light in at least the visible light region, incident light can be captured more, and a brighter image can be obtained.
(15) The present invention provides a camera structure including a glass cover plate having a laminated structure of the glass cover plate described in the above (13) or (14), the camera structure including: an optical lens group disposed on the side of the glass cover plate; an imaging element that receives light incident through the glass cover plate and the optical lens group; and an inner transparent plate which is disposed between the optical lens group and the imaging element and transmits light.
According to the invention of the above (15), since the camera structure includes the inner transparent plate that is disposed between the optical lens group and the imaging element and transmits light, dust adhering to the surface of the imaging element can be reduced, and as a result, a significant effect of improving image quality can be achieved.
(16) The present invention provides the camera structure according to the above (15), wherein the inner transparent plate is a synthetic resin film.
In a small camera module which is often incorporated in an information communication device such as a tablet PC or a smartphone, a near infrared light cut filter which mainly cuts light in the near infrared region is provided near an imaging element in the optical path between an optical lens group and the imaging element. The near-infrared cut filter needs to include a near-infrared light reflecting film that reflects near-infrared light and a near-infrared light absorbing film that absorbs near-infrared light.
Although a glass containing phosphate or fluorophosphate, which absorbs light in the near-infrared region, called blue glass, has been used in many cases for the near-infrared light cut filter, it is generally difficult to produce blue glass having a thickness of 200 μm or less, which has few dust particles, with good yield. In addition, it is also conceivable to use a synthetic resin film instead of glass, but the near-infrared light reflecting film needs to have a dielectric multilayer structure formed by sputtering or the like, and it is difficult to form a film having good uniformity on the synthetic resin film.
According to the invention as recited in the above (16), since the glass cover plate can exhibit the near-infrared light reflecting function, the synthetic resin film can be used as the inner transparent plate. The synthetic resin film can be made thin to a thickness of 100 μm or less, and the length of the camera structure can be shortened and reduced, and as a result, a significant effect is obtained that the thickness of the information communication device incorporating the camera can be made thinner.
(17) The camera structure according to the above (15) or (16), wherein the thickness of the inner transparent plate is 0.2mm or less.
According to the invention of the above (17), since the thickness of the inner transparent plate is as thin as 0.2mm or less, the length of the camera structure can be shortened and made thin, and as a result, the thickness of the information communication device incorporating the camera can be made thinner.
(18) The camera structure according to any one of the above (15) to (17), wherein the inner transparent plate has an antireflection layer for preventing reflection of at least light in a visible light region.
According to the invention of (18) above, if the antireflection layer is provided on the lens group side surface of the inner transparent plate, the antireflection function of preventing reflection of light in at least the visible light region enables more incident light to be captured, which results in a brighter image. Further, if the antireflection film is provided on the imaging element side of the inner transparent plate, reflected light from the inner transparent plate, particularly reflected light from the imaging element itself, is prevented from being further reflected by the inner transparent plate and returned to the imaging element, and a remarkable effect of improving image quality is achieved.
(19) The camera structure according to any one of the above (15) to (17), wherein both surfaces of the inner transparent plate are provided with antireflection layers for preventing reflection of light in at least a visible light region.
According to the invention of the above (19), it is possible to obtain more incident light, and to prevent reflected light from the inner transparent plate, particularly reflected light from the imaging element itself, from being further reflected by the inner transparent plate and returning to the imaging element, thereby achieving a remarkable effect of improving image quality.
(20) The camera structure according to the above (18) or (19), wherein the antireflection layer is a fine projection structure formed of fine projections formed on the surface of the inner transparent plate.
An antireflection layer of a fine protrusion structure formed of fine protrusions formed on the surface of the inner transparent plate, a so-called moth-eye structure, prevents light from being reflected in a wide frequency band. Therefore, according to the invention of the above (20), by forming the antireflection film having the moth-eye structure, reflected light by the inner transparent plate is significantly reduced in a wide frequency band, and the image quality can be significantly improved.
(21) The present invention provides the camera structure according to the item (18) or (19), wherein the antireflection layer is a coating film formed on a surface of the inner transparent plate.
A multilayer film obtained by alternately laminating 2 kinds of thin films having different refractive indices of light can form a light antireflection film. Further, it is known that such a multilayer film can also be obtained by coating a synthetic resin. According to the invention of the above (21), the inner transparent plate having the antireflection film of stable quality can be manufactured inexpensively and in large quantities.
(22) The present invention provides the camera structure according to any one of the above (15) to (21), wherein the inner transparent plate further includes a near-infrared light absorbing portion that absorbs light in a near-infrared region.
According to the invention described in the above (22), the effect of suppressing light in the near infrared region is obtained in a state where the incident angle dependency of light is small.
(23) The present invention provides the camera structure according to the above (21), wherein the near-infrared light absorbing portion contains an organic dye.
According to the invention of the above (23), there is no incident angle dependency with respect to light absorption without using a commonly used blue glass as a material of a filter for absorbing light in the near infrared region, and an effect of being able to block light in the near infrared region is obtained.
(24) The present invention provides an imaging device having the camera structure described in (15) to (23) above.
According to the invention of (24), since the glass cover plate has the near-infrared light reflecting film that reflects light, it is possible to achieve an effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging device. Further, since it is not necessary to place a member having a near-infrared light reflecting film in a region close to the imaging element, reflection of light incident on an internal mechanism of the imaging device can be suppressed, and as a result, stray light is suppressed, and an effect of reducing causes of ghost and flare can be obtained. Further, since the optical lens unit includes the inner transparent plate which is disposed between the optical lens group and the imaging element and transmits light, dust attached to the surface of the imaging element can be reduced. Therefore, a significant effect is achieved in that an imaging device having a small camera structure can be mounted at a lower cost with an improved image quality than the conventional imaging device.
Effects of the invention
According to the present invention, the glass cover plate that protects the internal mechanism of the camera provided in the imaging device, particularly the mobile communication device, from the outside can block the light in the near infrared region, and the significant effects of improvement in the image quality of the image, miniaturization, cost reduction, and simplification of the assembly process can be achieved without incorporating a near infrared light cut filter in the camera.
Drawings
Fig. 1(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of the first embodiment of the present invention. Fig. 1(B) is a structural view of a glass cover plate with a filter function. Fig. 1(C) is a structural view of a glass cover plate with a filter function, which is provided with a plurality of antireflection films.
Fig. 2(a) is a graph showing the incident angle dependence of the spectral transmittance of the near-infrared light reflecting film. Fig. 2(B) is an explanatory diagram explaining the definition of the incident angle.
Fig. 3 is a graph showing the incident angle dependence of the spectral transmittance of a glass cover plate with a filter function, which is provided with a near-infrared light absorbing film and a near-infrared light reflecting film.
Fig. 4 is a graph comparing the spectral transmittance of a glass cover plate with a filter function, the spectral transmittance of a glass having a near-infrared light absorbing film, and the spectral transmittance of a glass having a near-infrared light reflecting film.
Fig. 5 is an explanatory view for explaining the spectral transmittance of the dual-band glass cover.
Fig. 6(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a third embodiment of the present invention. Fig. 6(B) is a structural view of the glass cover plate with a filter function. Fig. 6(C) is a structural view of an inner transparent plate having transparent glass as a base material and a plurality of antireflection films. Fig. 6(D) is a structural view of an inner transparent plate having a moth-eye structure with a transparent synthetic resin film as a base material and having antireflection functions on both surfaces.
Fig. 7(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of the fourth embodiment of the present invention. Fig. 7(B) is a structural view of the glass cover plate with a near infrared light reflection function. Fig. 7(C) is a structural view of an inner transparent plate having transparent glass as a base material and a plurality of antireflection films.
Fig. 8(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a fifth embodiment of the present invention. Fig. 8(B) is a structural view of the glass cover plate with a near infrared light reflection function. Fig. 8(C) is a structural view of an inner transparent plate provided with a plurality of antireflection films and a near-infrared light absorption film.
Fig. 9(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a sixth embodiment of the present invention. Fig. 9(B) is a structural view of the glass cover plate with a near-infrared light reflection function. Fig. 9(C) is a structural diagram of a board with a near infrared light absorbing function. Fig. 9(D) is a structural view of an inner transparent plate having transparent glass as a base material and a plurality of antireflection films.
Fig. 10(a) is an explanatory diagram for explaining an experimental method using a conventional camera configuration. Fig. 10(B) is a sectional view of a conventional glass cover plate. Fig. 10(C) is a cross-sectional view of a conventional near-infrared light cut filter. Fig. 10(D) is an image captured by a conventional camera configuration. Fig. 10(E) is an explanatory diagram for explaining an experimental method using the camera configuration of the present invention. Fig. 10(F) is a cross-sectional view of a glass cover plate with a filter function in the camera structure of the present invention. Fig. 10(G) is a sectional view of an inside transparent plate in the camera structure of the present invention. Fig. 10(H) is an image captured by the camera structure of the present invention.
Fig. 11(a) is an explanatory diagram for explaining a conventional camera configuration in the mobile communication device. Fig. 11(B) is a sectional view of a conventional camera structure in a mobile communication apparatus.
Description of the symbols
1: camera module
10: glass cover plate
20: smart phone frame
30: magnet support
40: lens holder
50: lens unit
60: optical filter
70: imaging element
80: substrate
100: glass cover plate with light filtering function
110: antifouling coating film
120: anti-reflection film
130: crystallized glass
140: near-infrared light absorbing film
150: near-infrared light reflecting film
160: incident surface
170: emitting surface
180: object of measurement
190: incident light
200: vertical axis
210: glass cover plate with light filtering function
215: glass cover plate with near infrared light reflection function
217: board with near infrared light absorption function
220: transparent glass
222: transparent synthetic resin film
230: anti-reflection film
232: moth eye structure
240: inner transparent plate
242: inner transparent plate using transparent synthetic resin film as base material
244: inner transparent plate with near infrared light absorption function
300: light source
310: high reflective material
320: low reflection material
330: optical lens group
340: near infrared light cut-off filter
350: glass cover plate
360: transparent glass
370: anti-reflection film
380: blue glass
390: near-infrared light reflecting film
395: near infrared light cut-off layer
400: glass cover plate with light filtering function
450: inner transparent plate
A: mobile communication device
G: double images
Detailed Description
Embodiments of the present invention will be described below with reference to the drawings.
Fig. 1 to 10 show an example of an embodiment of the present invention, and in the drawings, the same components are denoted by the same reference numerals.
Fig. 1(a) shows a camera structure applied to an imaging device according to a first embodiment of the present invention. In the present embodiment, the imaging device is an information communication apparatus or a mobile communication apparatus a. The camera structure includes a glass cover 100 having a filter function from the side on which light enters, and a camera module 1 housed in a housing 20 of a mobile communication device a such as a smartphone. The camera module 1 includes a lens unit 50 as an optical lens group disposed on the side of the glass cover 100 with a filter function, and an imaging element 70 that receives light incident through the glass cover 100 with a filter function and the lens unit 50, and is characterized in that a near-infrared light cut filter that cuts light in the near-infrared region is not disposed between optical paths from the lens unit 50 to the imaging element 70. Specifically, as shown in fig. 1(a), the camera module 1 mainly includes a glass cover 100 with a filter function, a lens unit 50, a lens holder 40, and a magnet holder 30. The imaging element 70 and the substrate 80 are fixed to the smartphone case 20. For the connection of the imaging element 70 and the substrate 80, the connection may be performed by wire bonding, or flip chip packaging may be performed.
The configuration is largely different from the conventional camera configuration of fig. 11B in that a filter 60 (see fig. 11B) for blocking near infrared light, which is conventionally required for improving image quality, is omitted. Instead, the glass cover plate 10, which has conventionally been mainly used to protect the camera module 1, is provided with a filter function of blocking light in the near infrared region. With such a configuration, the length D2 of the entire camera structure can be made shorter than that of the conventional D1 (see fig. 11B), and since the optical filter 60 is not disposed in the vicinity of the imaging element 70, there is a significant effect that the granular dust (particles) adhering to the surface of the optical filter does not fall onto the surface of the imaging element 70 during the manufacturing process of the optical filter 60, and the image is not deteriorated. In addition, the process for disposing and assembling the near-infrared light cut filter 60 is not required in the assembly process of the camera module 1, which contributes to further cost reduction, yield improvement, and operation efficiency.
Further, the provision of the camera structure of fig. 1(a) has an effect that the mobile communication device a can be manufactured in a smaller size, thinner thickness, and at a lower cost.
Fig. 1(B) shows a laminated structure of a glass cover plate 100 with a filter function which is continuously provided in a housing of a mobile communication device a and protects a camera module as an internal mechanism from the outside. The glass cover plate 100 with a filter function uses the crystallized glass 130 as a transparent substrate that transmits light, and the antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region is formed on the light incident side with respect to the crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side of the light incidence side. On the light emission side, a near-infrared light reflecting film 150 that reflects light in the near-infrared region and a near-infrared light absorbing film 140 that absorbs light in the near-infrared region are formed in this order from the farthest side with respect to the crystallized glass 130. An antireflection film 120 may be formed on the farthest side from the light emission side (see fig. 1C).
In general, crystallized glass has large crystal grains and therefore is not easily transparent to light. However, due to recent technological development, for example, as impact-resistant and high-hardness transparent glass ceramics manufactured by OHARA corporation, crystal grains can be controlled to a nano size, and light transmittance can be improved (OHARA, Inc. [ ONLINE ], New information > sales guide for impact-resistant and high-hardness transparent glass ceramics (news distribution), [ search for 2.9.9.2.28 years in average ], and network (URL: http:// www.ohara-inc. co. jp/jp/news/dl/pressrelese 151216. pdf)). When such a crystallized glass is used, a glass cover plate having both impact resistance and fracture toughness in which cracks are less likely to occur can be produced. The glass cover plate 100 with the optical filter function is realized by forming the above-described laminated structure on such a glass cover plate. Although it is theoretically possible to use blue glass as the glass cover plate 100 with a filter function, it is not preferable because of low impact resistance and poor fracture toughness, which is less likely to cause cracking. It is also conceivable that a near-infrared light absorbing film 140 and/or a near-infrared light reflecting film 150, which will be described later, is formed on tempered glass to form the glass cover 100 with a filter function, but the glass cover has a disadvantage of lower impact resistance than the case of using crystallized glass 130. Further, it is also conceivable to form the near infrared light absorbing film 140 and/or the near infrared light reflecting film 150 on sapphire glass having high hardness to form the glass cover 100 with a filter function, but the cost is significantly increased and the workability is lower than that in the case of using the crystallized glass 130.
The antifouling coating film 110 prevents fingerprint fouling, sebum fouling, and easily wipes off the fouling. The stain-proofing coating film 110 is formed of a fluorine-based coating agent or the like, and is formed on the outermost side of the laminated structure of the glass cover plate on the light incident side by coating and/or spraying.
The antireflection film 120 reflects light in the ultraviolet region and suppresses reflection of light in the visible region. The antireflection film 120 is a dielectric multilayer film, and is configured by alternately stacking a nitride film and an oxide film. The dielectric film constituting the antireflection film 120 is formed by alternately laminating a plurality of nitride films and oxide films. As the nitride film, silicon nitride, silicon oxynitride, aluminum nitride, or the like can be used. In the case of using silicon oxynitride, the stoichiometric ratio of oxygen to nitrogen (oxygen/nitrogen) is preferably 1 or less. As the oxide film, silicon oxide (SiO) can be used2) Alumina (Al)2O3) And the like. By using silicon nitride or silicon oxynitride as the film of the antireflection film 120, the antireflection film 120 can be formed by using the same film formation method and film formation apparatus as those of the near-infrared light reflecting film 150 described later, which is advantageous in terms of process.
Instead of the nitride film, an oxide film may be used as the antireflection film 120. As a material for such an oxide filmAs the material, in addition to silicon oxide, titanium oxide (TiO) may be used2) Alumina (Al)2O3) Zirconium oxide (ZrO)2) Tantalum oxide (Ta)2O5) Niobium oxide (Nb)2O5) And the like. When the antireflection film 120 is formed using a plurality of types of oxide films having different refractive indices, the oxide is appropriately selected from the above oxides.
The antireflection film 120 can be formed by a known film forming method, for example, a vacuum deposition method, a sputtering method, an ion beam assisted deposition method (IAD method), an ion plating method (IP method), an ion beam sputtering method (IBS method), or the like. For forming the nitride film, a sputtering method or an ion beam sputtering method is preferably used.
The near-infrared light absorbing film 140 is formed on the surface of the crystallized glass 130 opposite to the anti-reflection film 120, that is, on the side of the imaging element 70 of the glass cover plate 100 with a light filtering function. The near-infrared light absorbing film 140 has a function of transmitting light in the visible light region and absorbing a part of light in the red region to the near-infrared region. The near-infrared light absorbing film 140 contains an organic dye and is formed of a resin film having a maximum absorption wavelength in a wavelength range of 650nm to 750nm (see a broken line in fig. 4). Since near-infrared light absorbing film 140 is adjacent to crystallized glass 130, it is preferable to reduce the difference in refractive index between the two to reduce the reflectance at the interface. By providing such a near-infrared light absorbing film 140, the dependence of the spectral transmittance characteristics on the incident angle can be reduced, and excellent near-infrared light cut-off properties can be obtained.
As the organic dye, azo compounds, phthalocyanine compounds, cyanine compounds, diimmonium compounds, and the like can be used. As a resin material as a binder (binder of pigment) constituting the near-infrared light absorbing film 140, polyacrylic acid, polyester, polycarbonate, polystyrene, polyolefin, or the like can be used. The resin material may be a mixture of a plurality of resins, or may be a copolymer of monomers using the above resins. The resin material may be selected in consideration of compatibility with the organic dye, film formation process, cost, and the like, as long as it has high transmittance for light in the visible light region. In addition, in order to improve the ultraviolet resistance of the near-infrared light absorbing film 140, a quencher (a delustering dye) such as a sulfur compound may be added to the resin material.
For forming the near-infrared light absorbing film 140, for example, the following method can be used. First, a resin binder is dissolved in a known solvent such as methyl ethyl ketone or toluene, and then the organic dye is added to prepare a coating liquid. Next, the coating liquid is applied to the crystallized glass 130 in a desired film thickness by, for example, a spin coating method, and dried and cured in a drying furnace.
The near-infrared light reflecting film 150 is a dielectric multilayer film in which a plurality of dielectric materials having different refractive indices are alternately stacked, as in the antireflection film 120. The dielectric multilayer film constituting the near-infrared light reflecting film 150 is formed by laminating a plurality of kinds of oxide films having different refractive indices, and the adjacent oxide films are different kinds of oxide films. In the first embodiment, the near-infrared light reflecting film 150 is formed by alternately laminating several tens of layers of two kinds of oxide films. As the oxide film, silicon oxide, titanium oxide (TiO) may be used in addition to silicon oxide2) Alumina (Al)2O3) Zirconium oxide (ZrO)2) Tantalum oxide (Ta)2O5) Niobium oxide (Nb)2O5) And the like.
In the near-infrared light reflecting film 150, the wavelength of light to be reflected is represented as λ, and the thickness of each oxide film is formed to be λ/4. As described above, if the light reflected from all the interfaces of the alternating layers reaches the incident surface, the light has the same phase, and as a result, the reflectance becomes large in the vicinity of the wavelength λ, which is a result of the enhancement of the light, and the light reflects as a light reflecting film. In this embodiment, the film can be designed so that λ reflects light in the near infrared region. The near-infrared light reflecting film 150 is formed by the same film forming method and film forming apparatus as the antireflection film 120.
The human eye has sensitivity to so-called visible light with wavelengths of 380nm to 780 nm. On the other hand, the imaging element generally has sensitivity to light of longer wavelengths including visible light, i.e., light having a wavelength up to about 1.1 μm. Therefore, if an image captured by the imaging element is directly photographed, a natural color tone is not seen, resulting in discomfort.
If the glass cover plate 100 with the optical filter function is formed into a laminated structure as shown in fig. 1(B) and 1(C), since the near-infrared light reflecting film 150 formed of the dielectric multilayer film is provided, light having a wavelength of 700nm or more, which cannot be completely absorbed by the near-infrared light absorbing film 140, can be blocked, and an image having a natural color tone can be obtained. In addition, if it is desired to block light in the near infrared region only by the near infrared light reflecting film 150, the reflectance greatly changes depending on the incident angle of incident light as described later. By combining the near-infrared light reflecting film 150 and the near-infrared light absorbing film 140 having no incident angle dependency on the light absorption rate, a near-infrared light cut filter having a small light transmittance dependency on the incident angle of light can be formed.
In addition, since the glass cover 100 that protects the camera inside the smartphone case 20 from the outside can block light in the ultraviolet region by the antireflection film 120, it is possible to prevent the optical lens group (lens unit 50) formed of synthetic resin, which is a constituent component of the camera, from being deteriorated by ultraviolet rays, and also prevent the near infrared light absorption film 140 including an organic pigment from being deteriorated by ultraviolet rays. Further, incident light can be captured more by the antireflection function for light in the visible light region, and a bright image can be obtained.
The antireflection film 120 is formed by alternately laminating a nitride film and an oxide film, but the nitride film generally has a hardness higher than that of the oxide film and reaches a hardness of 9H or more in a pencil hardness test. Therefore, the anti-reflection film 120 is configured to include a nitride film, thereby providing an effect of improving scratch resistance. In addition, the nitride film has a higher packing density and is denser than the oxide film. Since the components do not contain oxygen, they do not become a source of oxygen. Therefore, by providing the nitride film at a position outside the near-infrared light absorbing film 140, oxygen and moisture are prevented from entering the near-infrared light absorbing film 140, and the near-infrared light absorbing film 140 is prevented from deteriorating.
Typically, the filter has a number of optical interfaces. On the other hand, advanced antireflection films are applied to lenses. It is difficult to achieve lens-like transmittance with a filter that blocks light in the near infrared region, resulting in reflected light returning to the lens side. This may result in stray light that creates ghosts in the image. In the existing camera structure, since the optical filter 60 is disposed closest to the imaging element 70 on the optical path between the lens unit 50 and the imaging element 70, the ghost image as described above is prevented from being generated. However, according to the camera structure of the present embodiment, since the stray light is not generated as described above, the effect of significantly improving the image quality is obtained.
Next, the spectral transmittance characteristics of the glass cover plate 100 with the filter function will be described.
Fig. 2(a) shows the experimental result of how the spectral transmittance characteristics of the near-infrared light reflecting film composed of a dielectric film depend on the incident angle of light. The incident angle a is defined as fig. 2 (B). In addition, "T" on the vertical axis represents the spectral transmittance in% (percentage). In addition, "λ" on the horizontal axis represents the wavelength of light and has a unit of nm (nanometers) (the same applies to the following figures). The samples were prepared by alternately laminating 40 layers of titanium dioxide (TiO) on glass at a predetermined film thickness2) With silicon dioxide (SiO)2) And then obtaining the product. The solid line indicates the spectral transmittance when the incident angle of light is 0 degrees, and the broken line indicates the spectral transmittance when the incident angle of light is 30 degrees. As can be seen from fig. 2, it was confirmed that the incident angles of light of about 700nm wavelength, which is a red region, were 0 degrees and 30 degrees, which resulted in a significant difference in spectral transmittance. If there is such a difference, the color tone of the image is largely changed at the center and the peripheral portion of the image, and finally the image quality is degraded.
Fig. 3 shows the experimental result of how the spectral transmittance of the glass cover plate with a filter function 100 of the present embodiment, which includes both the near-infrared light absorbing film and the near-infrared light reflecting film, depends on the incident angle of light. The near-infrared light absorbing film is a resin film containing an organic dye and having a thickness of 5 μm or less, and the near-infrared light reflecting film has the same structure as that of fig. 2. The solid line indicates the spectral transmittance when the incident angle of light is 0 degrees, the broken line indicates the spectral transmittance when the incident angle of light is 15 degrees, and the one-dot chain line indicates the spectral transmittance when the incident angle of light is 30 degrees. It was confirmed that the incident angle dependency was smaller than that in the case of fig. 2.
Fig. 4 is a graph obtained by comparing the results of experiments of measuring the spectral transmittance of the glass cover plate 100 with a filter function (solid line) having the near infrared light absorbing film 140 and the near infrared light reflecting film 150, the glass cover plate having only the near infrared light absorbing film 140 formed thereon (broken line), and the glass cover plate having only the near infrared light reflecting film 150 formed thereon (single-dot chain line). The configurations of the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 are the same as those in fig. 2 and 3, and therefore, the description thereof is omitted. However, all the light incident angles are 0 degrees. In the case of only the near-infrared light absorbing film 140, although the absorption of light having a wavelength of 650nm to 750nm is strong, almost all light having a wavelength of 800nm or more is transmitted. As described above, the human eye has sensitivity mainly to so-called visible light having a wavelength of 380nm to 780nm, and therefore, if the imaging element 70 performs imaging up to a region of light having a wavelength of 800nm or more having sensitivity, it is an unnatural image to the human eye as described above. The near-infrared light reflecting film 150 is designed to block light having a wavelength of 700nm or more, and actually a sharp decrease in spectral transmittance is measured in the vicinity of the wavelength of 700 nm. The glass cover 100 having the optical filter function, which is formed by combining the near infrared light absorbing film 140 and the near infrared light reflecting film 150, is confirmed to have high transmittance for light having a wavelength of 400nm to 650nm in the visible light range and to block light having a wavelength of 700nm or more, as shown by a solid line in fig. 4.
Fig. 5 is a diagram showing the spectral transmittance of the glass cover plate with a filter function provided in the camera structure according to the second embodiment of the present invention. In the present embodiment, a glass cover plate and a camera structure having a so-called dual-band filter function are provided, which can obtain an image even at night. The basic configuration of the camera structure is the same as that of the first embodiment, but the glass cover plate 100 with a filter function includes a near-infrared light reflecting film D having a light transmittance that is improved with respect to a part of light in the near-infrared region. Since the film structure of the near-infrared light reflecting film D is a known technique, the description thereof is omitted.
If the near infrared light absorbing film 140 indicated by a dotted line of fig. 5 and the near infrared light reflecting film D indicated by a one-dot chain line of fig. 5, in which the light transmittance is improved for a part of the light in the near infrared region, are combined, a dual-band glass cover plate that transmits both the light in the visible region and the light in the near infrared region can be realized as indicated by a solid line of fig. 5. However, in fig. 5, the spectral transmittances of the near-infrared light reflecting film D and the dual-band glass cover plate are calculated at wavelengths of 750nm or more. According to the camera structure including the dual-band glass cover, a significant effect that the lane boundary line and the lane outer line are easily visible on the road at night is obtained, and thus the camera structure is applied to an in-vehicle camera.
Fig. 6(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a third embodiment of the present invention. The camera structure includes a glass cover 210 having a filter function for protecting the internal mechanism of the imaging device from the outside, and a camera module 1. The camera module 1 includes a lens unit 50 as an optical lens group serving as an internal mechanism of the imaging device, a lens holder 40 holding the lens unit 50, a magnet holder 30 moving the lens unit 50 in an axial direction to realize an autofocus function, an imaging element 70 receiving light incident through a glass cover 210 with a light filtering function and the lens unit 50, and an inner transparent plate 240 disposed between the lens unit 50 and the imaging element 70 and having transparent glass transmitting light as a base material. The inner transparent plate 240 has a thin plate-like structure, and the inner transparent plate 240 covers at least a part of the surface of the imaging element 70 when the imaging element 70 is viewed from the lens unit 50 side in the axial direction.
Fig. 6(B) is a structural view of the glass cover 210 with a filter function. The glass cover 210 with a filter function uses the crystallized glass 130 as a transparent substrate that transmits light, and the antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region is formed on the incident side of light with respect to the crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side of the light incidence side. On the light emission side, a near-infrared light reflecting film 150 that reflects light in the near-infrared region and a near-infrared light absorbing film 140 that absorbs light in the near-infrared region are formed in this order from the farthest side with respect to the crystallized glass 130. An antireflection film 120 may be formed on the farthest side from the light emission side (see fig. 1C).
That is, the glass cover 210 with a filter function protects the internal mechanism of the image forming apparatus from the outside, and has a laminated structure of glass covers, which is characterized by including the crystal glass 130 as a transparent substrate through which light is transmitted and the near-infrared light reflecting film 150 that reflects light in the near-infrared region. The glass cover 210 with a filter function further includes an antireflection film 120 that reflects light in the ultraviolet range and prevents reflection of light in at least the visible range.
The glass cover 210 with a filter function further includes a near infrared light absorbing film 140 that absorbs light in the near infrared region, and the near infrared light absorbing film 140 contains an organic pigment.
The camera configuration applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention includes: the image pickup device includes an optical lens group (lens unit 50) having the glass cover 210 with the optical filter function and disposed on the glass cover 210 with the optical filter function, an imaging element 70 receiving light incident through the glass cover 210 with the optical filter function and the lens unit 50, and an inner transparent plate 240 disposed between the lens unit 50 and the imaging element 70 and transmitting the light.
The methods of manufacturing the near-infrared light reflecting film 150, the near-infrared light absorbing film 140, and the antireflection film 120 are the same as those of the first embodiment, and therefore, description thereof is omitted.
Fig. 6(C) is a structural view of an inner transparent plate 240 having a transparent glass 220 as a base material and provided with a plurality of antireflection films. The inner transparent plate 240 includes an antireflection layer 230 on both surfaces of the transparent glass 220, which prevents reflection of light in at least a visible light region. The antireflection layer 230 is produced by the same method as that for the antireflection film 120.
That is, the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention is a laminated structure of a glass cover plate for protecting the internal mechanism of the imaging apparatus from the outside, and the camera structure includes: a crystal glass 130 as a transparent substrate for transmitting light, a near infrared light reflecting film 150 for reflecting light in a near infrared region, an antireflection film 120 for reflecting light in an ultraviolet region and preventing reflection of light in at least a visible light region, a glass cover 210 with a filter function having a near infrared light absorbing film 140 for absorbing light in a near infrared region, an optical lens group disposed on the side of the glass cover 210 with the filter function, an image forming element 70 for receiving light incident through the glass cover 210 with the filter function and the optical lens group, and an inner transparent plate 240 disposed between the optical lens group and the image forming element 70 and having a transparent glass 220 as a base material for transmitting light.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention, since the glass cover 210 with the filter function has the near infrared light reflecting film 150 that reflects light, it is possible to achieve an effect of preventing near infrared light from the outside from entering the internal mechanism of the imaging apparatus. Further, since it is not necessary to place a member including the near-infrared light reflecting film 150 in a region close to the imaging element 70, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, stray light can be suppressed, which has a significant effect of reducing causes of ghost and flare.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention, since the glass cover 210 with a filter function for protecting the internal mechanism of the imaging apparatus from the outside can block the light in the ultraviolet region, it is possible to prevent the optical lens formed of synthetic resin, which is a component of the camera, from being deteriorated by ultraviolet rays, which is advantageous for the long life. Further, since the glass cover 210 with a filter function has the antireflection film 120 that prevents reflection of light in at least the visible light region, incident light can be captured in a larger amount, and a brighter image can be obtained.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention, since the near-infrared light absorbing film 140 formed on the glass cover 210 with a filter function contains an organic pigment that absorbs near-infrared light, it is possible to suppress light in the near-infrared region with a small dependency on the incident angle of light without using a commonly used blue glass as a material of a filter for absorbing light in the near-infrared region.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention, since the camera structure includes the inner transparent plate 240 that is disposed between the optical lens group and the imaging element 70 and transmits light, dust attached to the surface of the imaging element can be reduced, and as a result, a significant effect of improving image quality is achieved.
According to the camera structure of the mobile communication device a applied to the imaging apparatus according to the third embodiment of the present invention, since the antireflection layer 230 that prevents reflection of light in at least the visible light region is provided on both surfaces of the inner transparent plate 240, it is possible to obtain more incident light, and to prevent reflected light from the inner transparent plate 240, particularly reflected light from the imaging element 70 itself, from being further reflected by the inner transparent plate 240 and returning to the imaging element 70, thereby achieving a significant effect of improving image quality.
The specific configurations and manufacturing methods of the near-infrared light reflecting film 150, the near-infrared light absorbing film 140, the antireflection film 120, and the antireflection layer 230 are the same as those of the first embodiment, and therefore, the description thereof is omitted.
Fig. 6(D) is a part of a modified example in which an inner transparent plate 240 having a transparent glass as a base material is replaced with an inner transparent plate 242 having a transparent synthetic resin film as a base material, in addition to a camera structure applied to a mobile communication device a as an imaging apparatus of the third embodiment. That is, fig. 6(D) is a structural view of an inner transparent plate 242 made of a transparent synthetic resin film having a moth-eye structure which is made of a transparent synthetic resin film 222 as a base material and has an antireflection function on both surfaces. The thickness of the inner transparent plate 242 made of a transparent synthetic resin film is 0.2mm or less. The inner transparent plate 242 made of a transparent synthetic resin film has moth-eye structures 232 on both surfaces thereof, which prevent reflection of light in at least the visible light range.
The moth-eye structure is intended to reduce reflection by eliminating a boundary surface where the refractive index abruptly changes, instead of reducing reflection by utilizing a disturbance effect as in the case of a dielectric multilayer film. Specifically, a fine projection structure is formed on the surface of the substrate, the fine projection structure being composed of a large number of fine projections having a height of about several hundred nm, and the repetition period of the projections is related to the wavelength range in which the reflection reduction effect is exhibited. Although the description of the moth-eye structure is omitted because it is a known technique, in the case of the present modified example, the moth-eye structure is formed by, for example, transfer or molding using a transparent acrylic resin as the transparent synthetic resin film 222, thereby realizing the antireflection function.
That is, the antireflection film 232 having a fine protrusion structure formed of fine protrusions formed on the surface of the inner transparent plate 242 made of a transparent synthetic resin film as a base material, i.e., a so-called moth-eye structure, prevents light from being reflected in a wide frequency band. The moth-eye structure 232 has an antireflection function for light in at least the visible region, and preferably has an antireflection function for light in the ultraviolet region and light in the near-infrared region.
As another modified example of the inner transparent plate 240, it is also conceivable to form a multilayer film obtained by applying a synthetic resin as an antireflection layer on the surface of the transparent synthetic resin film 222 as a base material. In general, a multilayer film in which 2 kinds of films having different optical refractive indices are alternately stacked can form a light antireflection film. Further, it is known that such a multilayer film can also be obtained by coating a synthetic resin.
For example, 2 kinds of synthetic resins having different refractive indices of light are prepared, and the refractive indices of the synthetic resins are all larger than the refractive index of air and all smaller than the refractive index of the transparent synthetic resin film 222. By applying these layers alternately to the transparent synthetic resin film 222, the inner transparent plate 240 having an antireflection film with stable quality can be produced at low cost. As a method of applying the synthetic resin to the transparent synthetic resin film 222, for example, a roll coating method or the like is considered. According to the present modified example, a significant effect is obtained that the inner transparent plate having the antireflection film can be manufactured in a large amount at low cost with stable quality.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the third embodiment of the present invention, the antireflection film 232 having the moth-eye structure is formed on both surfaces of the inner transparent plate 242 made of the transparent synthetic resin film as the base material, so that reflected light caused by the inner transparent plate 242 made of the transparent synthetic resin film as the base material is significantly reduced in a wide frequency band including the visible light region, thereby achieving a significant effect of improving the image quality.
Fig. 7(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of the fourth embodiment of the present invention. The camera structure includes a glass cover 215 with a near-infrared light reflecting function for reflecting near-infrared light and an inner transparent plate 240 made of transparent glass. Other structures are the same as those of the third embodiment, and therefore, description thereof is omitted.
Fig. 7(B) is a structural view of the glass cover 215 having a near infrared light reflection function. The glass cover 215 having a near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate for transmitting light, and the antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region is formed on the light incidence side with respect to the crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side of the light incidence side. A near infrared light reflecting film 150 for reflecting light in the near infrared region is formed on the light emitting side of the crystal glass 130. An antireflection film 120 may be formed on the farthest side of the light emission side (see fig. 1C).
Fig. 7(C) is a structural view of an inner transparent plate 240 having a transparent glass 220 as a base material and provided with a plurality of antireflection layers 230. The inner transparent plate 240 includes the anti-reflection layer 230 on both surfaces of the transparent glass 220.
That is, a camera structure applied to a mobile communication device a as an imaging apparatus according to a fourth embodiment of the present invention is a laminated structure of a glass cover plate for protecting an internal mechanism of the imaging apparatus from the outside, and the camera structure includes: a crystal glass 130 as a transparent substrate for transmitting light, a near infrared light reflecting film 150 for reflecting light in the near infrared region, a glass cover plate 215 with a near infrared light reflecting function having an antireflection film 120 for reflecting light in the ultraviolet region and preventing reflection of light in at least the visible region, an optical lens group disposed on the side of the glass cover plate 215 with a near infrared light reflecting function, an image forming element 70 for receiving light incident through the glass cover plate 215 with a near infrared light reflecting function and the optical lens group, and an inner transparent plate 240 disposed between the optical lens group and the image forming element 70 and having a transparent glass 220 as a base material for transmitting light.
The inner transparent plate 240 having the transparent glass 220 as a base material may be replaced with an inner transparent plate 242 having a transparent synthetic resin film as a base material (see fig. 6D).
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the fourth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function has the near infrared light reflection film 150 that reflects light, it is possible to obtain an effect that near infrared light from the outside is not incident on the internal mechanism of the imaging apparatus. Further, since it is not necessary to place a member including the near-infrared light reflecting film 150 in a region close to the imaging element 70, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, stray light can be suppressed, which has a significant effect of reducing causes of ghost and flare.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the fourth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function for protecting the internal mechanism of the imaging apparatus from the outside can block the light in the ultraviolet region, it is possible to prevent the optical lens formed of synthetic resin, which is a component of the camera, from being deteriorated by ultraviolet rays, which is advantageous for the long life. Further, since the glass cover 215 having the near infrared light reflection function has the antireflection film 120 for preventing reflection of light in at least the visible light region, it is possible to obtain more incident light and to obtain a brighter image.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the fourth embodiment of the present invention, since the camera structure includes the inner transparent plate 240 that is disposed between the optical lens group and the imaging element 70 and transmits light, dust attached to the surface of the imaging element can be reduced, and as a result, a significant effect of improving image quality is achieved.
According to the camera structure of the mobile communication device a applied to the imaging apparatus according to the fourth embodiment of the present invention, since the antireflection layer 230 that prevents reflection of light in at least the visible light region is provided on both surfaces of the inner transparent plate 240, it is possible to obtain more incident light, and to prevent reflected light from the inner transparent plate 240, particularly reflected light from the imaging element 70 itself, from being further reflected by the inner transparent plate 240 and returning to the imaging element 70, thereby achieving a remarkable effect of improving image quality.
Fig. 8(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a fifth embodiment of the present invention. The camera structure includes a glass cover 215 with a near-infrared light reflecting function for reflecting near-infrared light and an inner transparent plate 244 with a near-infrared light absorbing function using transparent glass as a base material. Other structures are the same as those of the third embodiment, and therefore, description thereof is omitted.
Fig. 8(B) is a structural view of the glass cover 215 having a near infrared light reflection function. The glass cover 215 having a near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate for transmitting light, and the antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region is formed on the incident side of light with reference to the crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side of the light incidence side. A near-infrared light reflecting film 150 that reflects light in the near-infrared region is formed on the light emission side of the crystal glass 130. An antireflection film 120 may be formed on the farthest side of the light emission side (see fig. 1C).
Fig. 8(C) is a structural diagram including a plurality of antireflection layers 230 for preventing reflection of light in at least the visible light region, and an inner transparent plate 244 with a near-infrared light absorbing function of the near-infrared light absorbing film 140 serving as a near-infrared light absorbing portion. The inner transparent plate 244 having a near infrared light absorbing function uses the transparent glass 220 as a base material, and the near infrared light absorbing film 140 is provided on the transparent glass 220.
The antireflection layer 230 is formed on the light incident side with reference to the transparent glass 220, and on the light emission side, the antireflection layer 230 and the near-infrared light absorbing film 140 are provided in this order from the farthest side with reference to the transparent glass 220. The near-infrared light absorbing film 140 contains an organic pigment.
The specific configurations and manufacturing methods of the near-infrared light reflecting film 150, the near-infrared light absorbing film 140, the antireflection film 120, and the antireflection layer 230 are the same as those of the first embodiment, and therefore, the description thereof is omitted.
Further, the inner transparent plate 244 having a near infrared light absorbing function may be replaced with an inner transparent plate 242 similar to the base material of a transparent synthetic resin film (see fig. 6D). However, in this case, it is preferable to provide the near-infrared light absorbing film 140 adjacent to the transparent synthetic resin film 222. That is, the moth-eye structure 232 as an antireflection film is formed on the light incident side with reference to the transparent synthetic resin film 222, and on the light emitting side, the moth-eye structure 232 and the near-infrared light absorption film 140 are provided in this order from the farthest side with reference to the transparent synthetic resin film 222.
As a means for realizing the inner transparent plate 244 having a near-infrared light absorbing function, for example, a thin plate of a synthetic resin containing at least a part of an organic dye that absorbs light in the near-infrared region can be used as a base material. In addition, a glass plate of so-called blue glass that absorbs light in the near-infrared region can be used as in the case of a conventional near-infrared light cut filter. It is also considered to attach a near-infrared light blocking film to a transparent glass plate.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the fifth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function has the near infrared light reflection film 150 that reflects light, it is possible to obtain an effect that near infrared light from the outside does not enter the internal mechanism of the imaging apparatus. Further, since it is not necessary to place a member including the near-infrared light reflecting film 150 in a region close to the imaging element 70, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, stray light can be suppressed, which has a significant effect of reducing causes of ghost and flare.
According to the camera structure applied to the mobile communication device a as the imaging device according to the fifth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function for protecting the internal mechanism of the imaging device from the outside can block the light in the ultraviolet region, it is possible to prevent the optical lens formed of synthetic resin, which is a component of the camera, from being deteriorated by ultraviolet rays, which is advantageous for the long life. Further, since the glass cover 215 having the near infrared light reflection function has the antireflection film 120 for preventing reflection of light in at least the visible light region, it is possible to obtain more incident light and to obtain a brighter image.
According to the camera structure of the mobile communication device a applied to the imaging apparatus according to the fifth embodiment of the present invention, since the near-infrared light absorbing film 140 formed on the inner transparent plate 244 having a near-infrared light absorbing function contains an organic pigment that absorbs near-infrared light, there is no incident angle dependency with respect to light absorption and an effect of being able to block light in the near-infrared region without using a commonly used blue glass as a material of a filter for absorbing light in the near-infrared region.
According to the camera structure of the mobile communication device a applied to the imaging apparatus according to the fifth embodiment of the present invention, since the antireflection layer 230 that prevents reflection of at least light in the visible light region is provided on both surfaces of the inner transparent plate 244 having a near infrared light absorption function, more incident light can be acquired. Further, since reflected light from the inner transparent plate 244 having a near infrared light absorbing function, particularly reflected light from the imaging element 70 itself, can be prevented from being further reflected by the inner transparent plate 244 having a near infrared light absorbing function and returning to the imaging element 70, a significant effect of improving image quality can be achieved.
Fig. 9(a) is a sectional view of a camera structure applied to a mobile communication apparatus a as an imaging device of a sixth embodiment of the present invention. The camera structure includes, in order from the light incident side, a glass cover 215 with a near infrared light reflection function that reflects near infrared light, a plate 217 with a near infrared light absorption function that absorbs near infrared light, and an inner transparent plate 240 made of transparent glass as a base material. Other structures are the same as those of the third embodiment, and therefore, description thereof is omitted.
Fig. 9(B) is a structural view of the glass cover 215 having a near infrared light reflection function. The glass cover 215 having a near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate for transmitting light, and the antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region is formed on the light incidence side with respect to the crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side of the light incidence side. A near infrared light reflecting film 150 for reflecting light in the near infrared region is formed on the light emitting side of the crystal glass 130. An antireflection film 120 may be formed on the farthest side from the light emission side (see fig. 1C).
Fig. 9(C) is a structural diagram of the board 217 with a near infrared light absorbing function. The near-infrared light absorbing plate 217 has a plurality of antireflection layers 230 having a thin plate-like structure and preventing reflection of light at least in the visible light region, and the near-infrared light absorbing plate 217 having a near-infrared light absorbing film 140 has a transparent glass 220 as a base material, and the near-infrared light absorbing film 140 is provided adjacent to the transparent glass 220. The antireflection layer 230 is formed on the light incident side with reference to the transparent glass 220, and on the light emission side, the antireflection layer 230 and the near-infrared light absorption film 140 are provided in this order from the farthest side with reference to the transparent glass 220.
The near-infrared light absorbing plate 217 is disposed on the inner structure side of the glass cover plate 215 having the near-infrared light reflecting function.
As a means for realizing the plate 217 having a near-infrared light absorbing function, for example, a thin plate of a synthetic resin containing at least a part of an organic dye that absorbs light in the near-infrared region can be used as a base material. In addition, a glass plate of so-called blue glass that absorbs light in the near-infrared region can be used as in the case of a conventional near-infrared light cut filter. It is also considered to attach a film for blocking near infrared light to the transparent plate.
Fig. 9(D) is a structural diagram of an inner transparent plate 240 made of transparent glass and having a transparent glass 220 as a base material and a plurality of antireflection layers 230. The inner transparent plate 240 includes the anti-reflection layer 230 on both surfaces of the transparent glass 220.
The inner transparent plate 240 having the transparent glass 220 as a base material may be replaced with an inner transparent plate 242 having a transparent synthetic resin film as a base material (see fig. 6D).
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the sixth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function has the near infrared light reflection film 150 that reflects light, it is possible to obtain an effect that near infrared light from the outside is not incident on the internal mechanism of the imaging apparatus. Further, since it is not necessary to place a member including the near-infrared light reflecting film 150 in a region close to the imaging element 70, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, stray light can be suppressed, which has a significant effect of reducing causes of ghost and flare.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the sixth embodiment of the present invention, since the glass cover 215 having the near infrared light reflection function for protecting the internal mechanism of the imaging apparatus from the outside can block the light in the ultraviolet region, it is possible to prevent the optical lens formed of synthetic resin, which is a component of the camera, from being deteriorated by ultraviolet rays, which is advantageous for the long life. Further, since the glass cover 215 having the near infrared light reflection function has the antireflection film 120 for preventing reflection of light in at least the visible light region, it is possible to obtain more incident light and to obtain a brighter image.
According to the camera structure applied to the mobile communication device a as the imaging apparatus according to the sixth embodiment of the present invention, since the near-infrared light absorbing film 140 formed on the near-infrared light absorbing plate 217 contains an organic pigment that absorbs near-infrared light, there is no incident angle dependency on light absorption and there is an effect that light in the near-infrared region can be blocked without using a commonly used blue glass as a material of a filter for absorbing light in the near-infrared region.
According to the camera structure of the mobile communication device a applied to the imaging apparatus according to the sixth embodiment of the present invention, since the antireflection layer 230 that prevents reflection of light in at least the visible light region is provided on both surfaces of the inner transparent plate 240 having the transparent glass 220 as a base material, it is possible to obtain more incident light, and to prevent reflected light from the inner transparent plate 240, particularly reflected light from the imaging element 70 itself, from being further reflected by the inner transparent plate 240 and returning to the imaging element 70, thereby achieving a remarkable effect of improving the image quality.
Fig. 10 is a diagram for explaining the effect of the present invention by comparing an image captured by a conventional camera configuration with an image captured by a camera configuration according to a third embodiment of the present invention.
Fig. 10(a) is an explanatory view for explaining an experimental method of an experiment performed using a conventional camera configuration. In the experiment, a light emitting diode having a specific center wavelength was used as a light source, and light emission was photographed. In the experiment, a light emitting diode having a center wavelength of 460nm was used as the light source 300. In order to easily observe the generated glare phenomenon and/or ghost phenomenon, a low reflective material 320 is disposed in the background of the light source 300, and a high reflective material 310 is disposed around the low reflective material 320.
Note that, if the lens is oriented in the light source direction with high light intensity, the phenomenon in which light is repeatedly reflected on the lens surface or the like and an unnecessary image is mapped is referred to as a glare phenomenon or a ghost phenomenon. The phenomenon of local overexposure of an image is called a glare phenomenon, and the phenomenon of repeated reflection of light at a lens surface to thereby significantly reflect an unnecessary image is called a ghost phenomenon.
The conventional camera structure includes a glass cover 350, an optical lens group 330, a near infrared light cut filter 340, and an imaging element 70 in this order from the light incident side. The near infrared light cut filter 340 is disposed between the optical lens group 330 and the imaging element 70.
Fig. 10(B) is a sectional view of a conventional glass cover plate 350. The glass cover 350 includes the antireflection film 120 on the transparent glass 360. The antireflection film 120 is provided on the optical lens group 330 side of the transparent glass 360.
Fig. 10(C) is a cross-sectional view of a conventional near-infrared cut filter 340. The near-infrared light cut filter 340 includes a near-infrared light reflecting film 390 on the light incident side and an antireflection layer 230 on the imaging element 70 side with reference to a blue glass 380 as a base material. Here, the blue glass 380 has a function of absorbing light in the near infrared region.
Fig. 10(D) shows an image captured by the imaging element 70 having the conventional camera structure described with reference to fig. 10(a) to 10 (C). It is known that a double image G like a petal is generated around the light source 300, and the image quality is deteriorated. Such a ghost phenomenon occurs even when the center wavelength of the light source 300 is 420nm to 660 nm.
Fig. 10(E) is an explanatory diagram for explaining an experimental method of an experiment performed by the camera configuration of the third embodiment of the present invention. In the experiment, as in the experiments of fig. 10(a) to 10(D), a light emitting diode having a center wavelength of 460nm was used as the light source 300. The camera structure according to the third embodiment of the present invention includes a glass cover 400 having a light filtering function, an optical lens group 330, an inner transparent plate 450, and an imaging element 70 in this order from the light incident side. The inner transparent plate 450 is disposed between the optical lens group 330 and the imaging element 70.
Fig. 10(F) is a sectional view of the glass cover plate 400 with a filter function in the camera structure according to the embodiment of the present invention. The glass cover plate 400 with a filter function has a transparent glass 360 as a base material, and has an antireflection film 120 on the light incidence side and a near infrared light cut layer 395 on the optical lens group 330 side with respect to the transparent glass 360. The near-infrared light cut layer 395, although not described in detail here, includes a near-infrared light absorbing film 140 and a near-infrared light reflecting film 150 (see fig. 6B).
Fig. 10(G) is a sectional view of the inside transparent plate 450 in the camera structure of the embodiment of the present invention. The inner transparent plate 450 is made of transparent glass 360, and the antireflection layer 230 is provided on both surfaces of the transparent glass 360.
The specific configurations and manufacturing methods of the near-infrared light reflecting film 150, the near-infrared light absorbing film 140, and the antireflection layer 230 are the same as those of the first embodiment, and therefore, the description thereof is omitted.
Fig. 10(H) is an image captured by the camera structure of the embodiment of the present invention. It is found that although the light source 300 receives strong light, ghost images such as those in fig. 10(D) are not generated, and the image quality is improved.
The camera structure, the imaging device, and the laminated structure of the glass cover plate according to the present invention are not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.
For example, the laminated structure of the glass cover plate and the camera structure of the present invention can be applied to a so-called dual camera in which two camera modules used as a camera of a mobile communication device such as a smartphone are combined to produce a great effect. In a dual camera, 2 camera modules are generally arranged in parallel. In the dual camera, images are recorded under two different conditions, and by combining them, exposure and aperture adjustment can be performed as in the case of a single-lens reflex camera. In the conventional camera structure, 2 filters are required, but if the glass cover plate with the filter function of the present invention is used, the filter in the camera module is omitted, so that the assembly process is simplified, and an image with excellent image quality can be obtained by using only one glass cover plate as compared with the case of using the filter.
In general, as shown in fig. 11(a), a glass cover of a camera of a mobile communication device such as a smartphone is provided independently of a smartphone housing 20. However, in order to improve the design, it is also conceivable to cover the surface of the smartphone case 20 with one continuous piece of glass with a filter function. In this case, the glass cover plate with filter function 100, the glass cover plate with filter function 210, and the glass cover plate with near-infrared light reflection function 215 according to the first embodiment of the present invention may be used in the same laminated structure. With such a configuration, the smartphone case 20 having a smooth surface as a whole including the camera portion can be realized.
As another modified example, it is also conceivable to reverse the order of lamination of the near infrared light absorbing film 140 and the near infrared light reflecting film 150. That is, the near infrared light absorbing film 140, the near infrared light reflecting film 150, and the crystallized glass 130 are formed in this order from the imaging element 70 side. With this configuration, since the near-infrared light absorbing film 140 relatively sensitive to heat can be formed after the near-infrared light reflecting film 150 is laminated, a film forming means such as a vapor deposition apparatus which is inexpensive but easily becomes high in temperature can be used for forming the near-infrared light reflecting film 150. In addition, such a method can be used as long as the glass cover plate structure and the inner transparent plate of the present invention can be realized by attaching films having a near infrared light absorbing function, a near infrared light reflecting function, an antireflection function, and the like to glass or a synthetic resin film as a base material.
For example, as a means for realizing the near-infrared light absorbing function, for example, a thin sheet of synthetic resin at least partially containing an organic dye that absorbs light in the near-infrared region can be used as the base material. In addition, a glass plate of so-called blue glass that absorbs light in the near-infrared region can be used as in the case of a conventional near-infrared light cut filter. It is conceivable to bond a near-infrared light blocking film to a transparent glass plate.

Claims (15)

1. A camera structure is characterized by comprising:
a glass cover plate directly fixed to a housing of the information communication apparatus to protect an internal camera module from the outside; and
the camera module is disposed inside the glass cover plate as a separate body from the frame body and the glass cover plate,
the camera module includes an optical lens group, a lens holder for holding the optical lens group, an imaging element, and an inner transparent plate, so that the lens holder is configured not to hold any optical component in a space on the side of the glass cover plate with respect to the optical lens group,
the imaging element receives light incident via the glass cover plate and the optical lens group,
the inner transparent plate is disposed between the optical lens group and the imaging element and transmits light,
the glass cover plate on the frame side of the information communication apparatus has:
a near-infrared light absorbing film that absorbs light in the near-infrared region; and
a light reflection film which reflects light in an ultraviolet region and light in a near infrared region,
the surface of the glass cover plate on the camera module side is provided with the near infrared light absorption film and the light reflection film in this order from the light incidence side,
the light reflecting film is a dielectric multilayer film,
in the camera module independent from the glass cover plate, no optical member is disposed in a space between the optical lens group and the glass cover plate, and no filter that reflects light in the near infrared region is disposed.
2. The camera structure according to claim 1, wherein the dielectric multilayer film is formed by laminating a plurality of kinds of oxide films having different refractive indices, and the adjacent oxide films are different kinds of oxide films.
3. The camera structure according to claim 1, wherein the inner transparent plate is further provided with a near-infrared light absorbing portion that absorbs light in a near-infrared region.
4. The camera structure according to claim 2, wherein the inner transparent plate is further provided with a near-infrared light absorbing portion that absorbs light in a near-infrared region.
5. The camera structure according to claim 3, wherein the near-infrared light absorbing portion contains an organic pigment.
6. The camera structure according to claim 4, wherein the near-infrared light absorbing portion contains an organic pigment.
7. The camera structure according to any one of claims 1 to 6, wherein the inner transparent plate is a synthetic resin film.
8. The camera structure according to any one of claims 1 to 6, wherein the thickness of the inner transparent plate is 0.2mm or less.
9. The camera structure according to any one of claims 1 to 6, wherein the inner transparent plate has an antireflection layer for preventing reflection of light in at least a visible light region.
10. The camera structure according to claim 9, wherein antireflection layers for preventing reflection of light in at least a visible light region are provided on both surfaces of the inner transparent plate.
11. The camera structure according to claim 9, wherein the antireflection layer is a fine projection structure composed of fine projections formed on a surface of the inner transparent plate.
12. The camera structure according to claim 10, wherein the antireflection layer is a fine projection structure composed of fine projections formed on a surface of the inner transparent plate.
13. The camera structure according to claim 9, wherein the antireflection layer is a coating film formed on a surface of the inner transparent plate.
14. The camera structure according to claim 10, wherein the antireflection layer is a coating film formed on a surface of the inner transparent plate.
15. An information communication apparatus having the camera structure according to any one of claims 1 to 14.
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