TWI743874B - Camera structure, camera device - Google Patents

Abstract

[Subject] Provides a camera structure that can reduce ghosting and flashing phenomena. [Solution] A camera structure for imaging, including: an optical lens group arranged on the incident side of light; an imaging element that receives light incident through the optical lens group; a near-infrared light reflector that reflects light in the near-infrared region; A near-infrared light absorbing part of light in the infrared light region; wherein the near-infrared light reflecting part and the near-infrared light absorbing part are separate from each other.

Description

Camera structure, camera device

The present invention relates to the structure of a camera provided in an imaging device.

In this century, imaging devices, that is, cameras, using solid-state imaging elements (imaging elements), so-called digital cameras, have become mainstream. In addition, with the popularization of information communication devices such as personal computers (PCs), tablet PCs, and smart phones, they are used in daily life. Most of these information and communication devices have built-in small camera modules, and there are also high-performance ones with imaging elements that have more than 10 million pixels. Information and communication devices, especially smart phones, which are portable communication devices, tend to be thinner and lighter, and their components, namely camera modules, also need to be miniaturized and space-saving. In addition, for users, because smartphones often become the only camera device, with the miniaturization of camera modules, better image quality is required.

In recent years, the demand for automatic driving of automobiles has become higher. In some vehicle types, car storage, automatic braking, and night driving subsidies using on-board cameras have been put into practical use. Camera modules used in vehicle-mounted cameras have also continued to be miniaturized and improved in performance. In order to perform image recognition, it is strongly required to remove noise such as ghosts from images.

In addition, when the lens with the imaging device is directed toward the direction of the light source with high light intensity, the phenomenon in which the light is repeatedly reflected on the lens surface, etc., and the unwanted image is reflected is called the flash phenomenon (flash) and ghost phenomenon (ghost image). . The phenomenon that a part of the image is overexposed is called the flash phenomenon, and the phenomenon that light repeatedly reflects on the lens surface and clearly reflects the unwanted image is called the ghost phenomenon.

As shown in FIG. 11(A), the camera module 1 of the conventional camera structure is mainly composed of a lens unit 50, a lens carrier 40, a magnet holder 30, an optical filter 60, and an imaging element 70, and is fixed to a smartphone Frame 20 (refer to Patent Document 1). Among them, the optical filter 60 mainly exerts an effect of cutting off light in the near-infrared light region. The human eye has sensitivity to light in the visible light region (visible light) with a wavelength of 380 nm to 780 nm. On the other hand, an imaging element generally has a sensitivity to light having a longer wavelength including visible light, that is, light having a wavelength of about 1.1 μm. Therefore, after the image captured by the imaging element is maintained as a photo, the human eye cannot match the natural color tone, which causes a sense of disharmony. Among them, the camera module 1 has a built-in optical filter 60 (near-infrared light cut filter) that cuts off light in the near-infrared light region.

As the near-infrared light cut filter 60, for example, a glass containing phosphate or fluorophosphate that absorbs light in the near-infrared light region called blue glass is used.

In addition, the protective glass 10 provided in the conventional camera structure uses tempered glass or sapphire glass as a material.

In this specification, a lens unit including an optical lens group, a lens carrier, an imaging element, a magnet holder, etc., and the internal mechanism of an imaging device necessary for imaging are defined as a camera module. In addition, in the camera module, a glass structure is defined as a cover glass that protects the internal mechanism of the imaging device from the outside.

FIG. 11(B) shows an explanatory diagram explaining an experiment method of an experiment performed with a conventional camera structure. In the experiment, a light-emitting diode having a specific center wavelength was used as a light source, and the light emission was imaged. In the experiment, a light-emitting diode with a center wavelength of 460 nm was used as the light source 300. In order to make it easier to see the generated flash phenomenon and ghosting phenomenon, a low-reflective material 320 is arranged in the background of the light source 300, and a high-reflective material 310 is arranged around the low-reflective material 320.

The conventional camera structure includes a cover glass 10, an optical lens group 50, a near-infrared light cut filter 60, and an imaging element 70 in order from the light incident side. The near-infrared light cut filter 60 is arranged between the optical lens group 50 and the imaging element 70.

FIG. 11(C) is a cross-sectional view of the cover glass 10. The protective glass 10 is provided with an anti-reflection film 370 on the transparent glass 360. The anti-reflection film 370 is provided on the side of the optical lens group 50 of the transparent glass 360.

FIG. 11(D) is a cross-sectional view of the near-infrared light cut filter 60. The near-infrared light cut filter 60 is based on the blue glass 380 as a base material, and has a near-infrared light reflection film 390 on the incident side, and an anti-reflection film 370 on the imaging element 70 side. The blue glass 380 has the function of absorbing near-infrared light.

FIG. 11(E) is an image captured by the imaging element 70 of the conventional camera structure described in FIGS. 11(A) to 11(D). It is understood that a petal-like ghost image G is generated centered on the light source 300, and the image quality is degraded. This kind of ghosting phenomenon also occurs when the center wavelength of the light source 300 becomes 420 nm to 660 nm. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2013-153361

[The problem to be solved by the invention]

In order to reduce ghosting and flashing phenomena, it is generally necessary to have a higher and more complicated structure than an optical lens group equipped with a camera, and a better anti-reflection coating of the lens element itself. However, this can be a difficult subject in camera modules for information and communication equipment requiring small, lightweight and inexpensive information communication equipment, or camera modules for vehicle-mounted cameras. [Means to Solve the Problem]

As the main cause of the ghost phenomenon, it can be cited that the near-infrared light cut filter including the reflection film of near-infrared light is located in the vicinity of the imaging element. Therefore, by arranging the near-infrared light reflecting part on the outer side of the camera module as much as possible, for example, on the protective glass, the ghost phenomenon can be greatly suppressed. In addition, by arranging the near-infrared light reflecting part on the outside, in order to prevent the conversion of the cut-off wavelength of the near-infrared light that may be generated by the light with a large incident angle entering the camera module, the spectral characteristics of the near-infrared light absorbing part are adjusted And the spectral characteristics of the near-infrared light reflector, so that the image quality does not depend on the angle of the incident light.

(1) The present invention is to provide a camera structure for imaging, including: an optical lens group arranged on the incident side of light; an imaging element that receives light incident through the optical lens group; Infrared light reflecting part; a near-infrared light absorbing part that absorbs light in the near-infrared light region; wherein the near-infrared light reflecting part and the near-infrared light absorbing part are separate from each other.

According to the above-mentioned invention (1), since the degree of freedom is created in the position where the near-infrared light reflecting part is arranged and the position where the near-infrared light absorbing part is arranged, it can be arranged in the most suitable position in the camera structure, and the image quality can be achieved. Improve this remarkable effect.

(2) The present invention provides the camera structure described in (1) above, wherein the near-infrared light reflecting part and the near-infrared light absorbing part are arranged in this order from the incident side of the light. Light absorption part.

The light on the longer wavelength side than the light of the wavelength absorbed by the near-infrared light absorbing portion may be transmitted. Therefore, after arranging the near-infrared light absorbing part and the near-infrared light reflecting part in order from the light incident side, light with a longer wavelength than the light of the wavelength absorbed by the near-infrared light absorbing part becomes easier to enter the camera module. Before reaching the near-infrared light reflecting part capable of cutting off the light on the long-wavelength side, it becomes diffused light due to reflection on the lens surface or the like, which causes degradation of image quality.

According to the invention of (2) above, since the near-infrared light reflecting part and the near-infrared light absorbing part are arranged in order from the light incident side, the near-infrared light reflecting part and the near-infrared light absorbing part are arranged in order to suppress the diffused light on the long-wavelength side. Effect.

(3) The present invention provides the camera structure described in (1) or (2) above, wherein the near-infrared light reflecting section includes lens elements constituting the optical lens group in the camera structure and is arranged in a ratio The lens element is also close to the incident side of the light.

According to the invention of (3) above, the near-infrared light reflector includes the lens element constituting the optical lens group and is arranged closer to the incident side of the light than the lens element, compared with the position of the conventional near-infrared light cut filter. , The distance from the near-infrared light reflecting part and the imaging element becomes larger. In the near-infrared light reflector, after the incident angle of light is shifted from the axis direction perpendicularly, light in the ultraviolet region may easily pass through. If the distance from the imaging element becomes larger, the angle at which the imaging element can be seen from the near-infrared light reflector becomes smaller, which can reduce the light that passes through the near-infrared light reflector and directly reaches the excess ultraviolet region of the image sensor. .

(4) The present invention provides the camera structure described in any one of (1) to (3) above, wherein the near-infrared light absorbing portion includes a lens element constituting the optical lens group in the camera structure, And it is arranged closer to the imaging element than the lens element.

According to the invention of (4) above, there are many cases where the transmittance of the near-infrared light absorbing portion is independent of the incident angle of light. Therefore, the near-infrared light absorption part in the camera structure includes the lens elements that constitute the optical lens group and is arranged on the side of the imaging element than the lens elements, which can effectively suppress the diffuse incident on the imaging element from all directions. This remarkable effect of shooting light.

(5) The present invention provides the camera structure described in any one of (1) to (4) above, wherein an imaging element cover that covers at least a part of the imaging element when viewed from the side where light is incident is arranged on the optical Between the lens group and the aforementioned imaging element.

If dust, which is difficult for light to pass through, adheres to the image sensor, the image quality will be degraded. According to the invention of (5) above, the imaging device cover that covers at least a part of the imaging device when viewed from the light incident side is arranged between the optical lens group and the imaging device at a position close to the imaging device, thereby reducing adhesion to the imaging device. This remarkable effect of dust on the components and preventing the deterioration of picture quality.

(6) The present invention provides the camera structure described in (5) above, wherein the imaging element cover is glass.

According to the invention of (6) above, it is possible to produce an imaging element cover that is less deformed by temperature changes at a low cost.

(7) The present invention provides the camera structure described in (5) above, wherein the imaging element cover is a synthetic resin film.

A synthetic resin film having a thickness of 100 μm or less can be easily produced. According to the above-mentioned invention (7), it is possible to produce a thin and inexpensive imaging element cover at a low cost.

(8) The present invention provides the camera structure described in any one of (5) to (7) above, wherein the thickness of the imaging element cover is 0.2 mm or less.

According to the invention of (8) above, it is possible to achieve such a remarkable effect of providing a camera module with a thinner thickness than before.

(9) The present invention provides the camera structure described in any one of (5) to (8) above, wherein the imaging element cover includes an anti-reflection layer that prevents at least reflection of light in the visible light region.

The imaging device cover is arranged at a position close to the imaging device between the optical lens group and the imaging device. Therefore, when the imaging device cover reflects light, it becomes a cause of significant deterioration of the image quality of the image obtained by the imaging device.

According to the above-mentioned invention (9), since the imaging element cover is provided with an anti-reflection layer that prevents reflection of light in at least the visible light region, it is possible to achieve such a remarkable effect of improving image quality.

(10) The present invention provides the camera structure described in any one of (5) to (8) above, wherein the imaging element cover is provided with anti-reflection layers that prevent at least reflection of light in the visible light region on both surfaces of the imaging element cover.

According to the invention of (10) above, it is possible to absorb more incident light and prevent reflected light caused by the imaging element cover, especially to prevent the reflected light from the imaging element itself from being reflected by the imaging element cover and returning to the imaging element, and Achieve this remarkable effect of image quality improvement.

(11) The present invention is the camera structure described in (9) or (10) above, wherein the anti-reflection layer is a fine protrusion structure composed of fine protrusions formed on the surface of the imaging element cover.

The anti-reflection layer of the so-called moth-eye structure formed on the surface of the imaging element cover made of fine protrusions can prevent the reflection of light in a wide frequency band. Therefore, according to the above-mentioned invention (12), since the anti-reflection layer of the moth-eye structure is formed, the reflected light caused by the imaging element cover can be significantly reduced in a wide frequency band, and this remarkable effect of image quality improvement can be achieved.

(12) The present invention provides the camera structure described in (9) or (10) above, wherein the anti-reflection layer is a coating film formed on the surface of the inner transparent flat plate.

A multilayer film obtained by alternately laminating two types of thin films having mutually different refractive indexes of light can form a light anti-reflection film. Next, it is known that such a multilayer film can be obtained by suppressing the application of synthetic resin. According to the above-mentioned invention (12), it is possible to obtain a remarkable effect of being able to manufacture a large amount of an inner transparent flat plate of an anti-reflection film with stable quality at low cost.

(13) The present invention provides the camera structure described in any one of (5) to (12) above, wherein the imaging element cover includes the near-infrared light absorbing portion.

According to the above-mentioned invention (13), since the imaging element cover includes the near-infrared light absorbing portion, it is possible to achieve remarkable effects such as a reduction in the number of parts and a reduction in the number of processes in the construction of the camera.

(14) The present invention provides the camera structure described in any one of (1) to (13) above, wherein the near-infrared light absorbing portion is a near-infrared light absorbing film that absorbs light in the near-infrared light region, and includes Organic pigments.

According to the invention of (14) above, since the near-infrared light absorbing portion has a near-infrared light absorbing film, the near-infrared light absorbing film contains an organic pigment that absorbs near-infrared light, and it is not used as a light for absorbing near-infrared light. The material of the filter is generally blue glass, and with the low dependency of the incident angle of light, it achieves the effect of suppressing the light in the near-infrared light region.

(15) The present invention provides the camera structure described in any one of (1) to (14) above, wherein the camera structure further has a protective glass for protecting the internal mechanism of the imaging device from the outside, and the protective glass includes the aforementioned Near-infrared light reflection part.

According to the above-mentioned invention (15), since the cover glass has a near-infrared light reflecting film that reflects light, it is possible to achieve the effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging device. In addition, in the area close to the imaging element, it is not necessary to put in a member with a near-infrared light reflecting film, so that the reflection of light incident on the internal mechanism of the imaging device can be suppressed. The effect of reducing the cause of ghosting or flashing.

(16) The present invention is to provide a camera structure for imaging, including: an optical lens group arranged on the incident side of light; an imaging element that receives light incident through the optical lens group; Infrared light reflecting part; a near-infrared light absorbing part that absorbs light in the near-infrared light region; wherein the near-infrared light reflecting part and the near-infrared light absorbing part are included in the integrated optics included in the optical lens group Component.

According to the above-mentioned invention (16), because the integrated optical element including the near-infrared light reflecting part and the near-infrared light absorbing part is included in the optical lens group, it is not necessary to provide a near-infrared light reflecting film at a position close to the imaging element. Component grouping. Therefore, the reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, the diffused light can be suppressed, and the effect of reducing the cause of ghosting or flashing can be achieved.

(17) The present invention provides a camera structure including a near-infrared light absorbing part that absorbs light in the near-infrared light region; a near-infrared light reflecting part that reflects light in the near-infrared light region; The wavelength of 685nm-755nm has a light absorption wavelength region with a light transmittance of less than 2%; as the wavelength of the incident light to the near-infrared light reflector increases, the light transmittance decreases. When 50% of the wavelength is defined as the cut-off wavelength of the near-infrared light, the near-infrared light reflecting part has the characteristic of slightly totally reflecting light of a wavelength longer than the cut-off wavelength of the near-infrared light; When the incident angle of light changes in the range of 0° to 30°, the cutoff wavelength of the near-infrared light is usually included in the light absorption wavelength region.

As an effect of combining the near-infrared light absorbing part and the near-infrared light reflecting part, if the transmittance of light at a predetermined wavelength becomes 1% or more, the acquired image will be affected. Therefore, as the spectral characteristics of the near-infrared light absorption part, in the light wavelength region with a light transmittance of 2% or more, when the light transmittance of the near-infrared light reflection part becomes 50%, the image quality of the acquired image will be less than that of the naked eye. The tones are different. In addition, when the near-infrared light reflecting part is formed of a dielectric multilayer film, for example, the light transmittance changes according to the incident angle of the incident light. The light wavelength dependence of the transmittance will be affected at the periphery and the center of the image. The difference causes the so-called "red-leakage" to deteriorate the picture quality. Especially when the infrared reflector is arranged on the outside of the camera module, specifically on the protective glass, since light with a large incident angle may enter the camera module, the image quality deterioration becomes significant.

According to the invention described in (17) above, as an effect of combining the near-infrared light absorbing part and the near-infrared light reflecting part, since the light transmittance in the light wavelength region of 685nm to 755nm is less than 1%, it is possible to achieve image capturing. This is an excellent effect that the difference between the quality and the naked eye becomes smaller. When the incident angle of the incident light to the near-infrared light reflecting part is changed in the range of 0°～30°, usually, the cut-off wavelength of the near-infrared light of the near-infrared light reflecting part enters the light whose light transmittance is less than 2%. In the absorption wavelength region, the incidence angle dependence of the spectral characteristics of light in the near-infrared light region becomes smaller, because the light wavelength dependence of the transmittance at the periphery and the center of the acquired image does not change, and the image quality can be improved. This excellent effect.

(18) The present invention provides the camera structure according to any one of (1) to (16) above, including: a near-infrared light absorbing portion that absorbs light in the near-infrared light region; and near-infrared light that reflects light in the near-infrared light region Reflecting part; wherein, the aforementioned near-infrared light absorbing part, as the light wavelength in the region of 685nm to 755nm, has a light absorption wavelength region with a light transmittance of less than 2%; the aforementioned near-infrared light reflecting part, which transmits light When the wavelength at which the efficiency decreases to 50% is defined as the near-infrared light cut-off wavelength, it has the characteristic of slightly totally reflecting light of a wavelength longer than the aforementioned near-infrared light cut-off wavelength; When the incident angle is changed in the range of 0° to 30°, the cutoff wavelength of the near-infrared light is usually included in the light absorption wavelength region.

When the near-infrared light reflector is located close to the outside of the camera structure, such as a protective glass, even light with a large incident angle will enter the camera structure. When the near-infrared light reflecting part is formed with a dielectric multilayer film, for example, the light transmittance changes according to the incident angle of the incident light, and the light wavelength dependence of the transmittance will be the same between the peripheral part and the central part of the acquired image. However, the so-called "red-leakage" is a phenomenon of deterioration in image quality. According to the invention described in (18) above, when the incident angle of the incident light to the near-infrared light reflecting part is changed in the range of 0° to 30°, usually, the cut-off wavelength of the near-infrared light of the near-infrared light reflecting part enters In the light absorption wavelength region where the light transmittance is less than 2%, the incident angle dependence of the spectral characteristics of the light in the near-infrared light region becomes smaller, because the wavelength of the light acquired at the periphery and the center of the acquired image does not change , Can achieve this excellent effect of image quality improvement.

In addition, as an effect of combining the near-infrared light absorbing part and the near-infrared light reflecting part, in the light wavelength range of 685nm to 755nm, the light transmittance is less than 1 in the light wavelength range longer than the cutoff wavelength of the near-infrared light. %, it is possible to achieve the excellent effect that the difference between the image quality of the acquired image and that of the naked eye becomes smaller.

(19) The present invention provides a camera structure as described in (17) above, comprising: a protective glass that protects the internal mechanism of the imaging device from the outside; an optical lens group arranged on the protective glass side; receiving through the protective glass and The image pickup element for light incident on the optical lens group; wherein the cover glass has: a transparent substrate that transmits light; the near-infrared light absorbing portion; the near-infrared light reflecting portion; Between the optical paths of the elements, there is no near-infrared light cut filter that cuts off the light in the near-infrared light region.

Because the near-infrared light reflector is located on the side closest to the outside of the camera structure, that is, on the protective glass, even light with a large incident angle will enter the camera structure. When the near-infrared light reflecting part is formed with a dielectric multilayer film, for example, the light transmittance changes according to the incident angle of the incident light, and the light wavelength dependence of the transmittance will be the same between the peripheral part and the central part of the acquired image. However, the so-called "red-leakage" is a phenomenon of deterioration in image quality.

According to the invention described in (19) above, when the incident angle of the incident light to the near-infrared light reflecting part is changed in the range of 0° to 30°, usually, the cut-off wavelength of the near-infrared light of the near-infrared light reflecting part enters In the light absorption wavelength region where the light transmittance is less than 2%, the incidence angle dependence of the spectral characteristics of the light in the near-infrared light region becomes small, because the wavelength dependence of the light obtained at the periphery and the center of the image is not Will change, can achieve this excellent effect of image quality improvement.

In addition, as an effect of combining the near-infrared light absorbing part and the near-infrared light reflecting part, in the light wavelength range of 685nm to 755nm, the light transmittance is less than 1 in the light wavelength range longer than the cutoff wavelength of the near-infrared light. %, it is possible to achieve the excellent effect that the difference between the image quality of the acquired image and that of the naked eye becomes smaller.

Furthermore, because there is no near-infrared light cut filter that cuts off the light in the near-infrared light region between the optical lens group and the aforementioned imaging element, it contributes to the reduction of the overall thickness of the camera structure.

(20) The present invention provides a camera structure with a near-infrared light cutoff filter that blocks light in the near-infrared light region; wherein the near-infrared light cutoff filter increases the wavelength of incident light and reduces the light transmittance When the wavelength that becomes 10% is defined as the near-infrared light blocking wavelength, the angle-dependent change width of the near-infrared light blocking wavelength when the incident angle of the incident light is changed in the range of 0° to 30° is 5 nm or less.

When the near-infrared light cut filter has, for example, a near-infrared light reflecting portion including a dielectric multilayer film, the wavelength dependence of the transmittance of light in the near-infrared light reflecting portion changes depending on the incident angle of incident light. That is, for example, the blocking wavelength of the near-infrared light of the near-infrared light reflector is about 700nm when the incident angle of the incident light is 0°, but when the incident angle of the incident light is 30°, an incident angle of about 675nm occurs. Dependence situation. In this case, when the near-infrared light cut filter has a near-infrared light absorbing part, the light transmittance achieved by combining with the near-infrared light reflecting part may vary greatly depending on the incident angle of incident light. Specifically, a near-infrared light-cutting filter with a near-infrared light reflecting part and a near-infrared absorbing part depends on the angle of the blocking wavelength of the near-infrared light when the incident angle of the incident light is varied in the range of 0° to 30° The range of change may become about 30nm. Conversely, in the predetermined light wavelength of the near-infrared light region, the light transmittance of the near-infrared light cutoff filter varies more depending on the incident angle of the incident light. For example, when light with a wavelength of 660 to 690 nm is incident, the light transmittance will be about 20% when the incident angle is small at the center of the acquired image, and the light transmittance will be almost zero when the incident angle is large at the periphery of the acquired image. As a result, the light wavelength dependence of transmittance will be different between the peripheral part and the center part of the acquired image, resulting in the deterioration of image quality such as "redness".

According to the invention described in (20) above, in the near-infrared light cut filter, the angle-dependent change width of the blocking wavelength of the near-infrared light when the incident angle of the incident light is changed in the range of 0° to 30° is Below 5nm, it is difficult to make a difference in the performance of the color in the obtained image, and the good effect of image quality improvement can be achieved.

(21) The present invention provides a camera structure including: a near-infrared light absorbing part that absorbs light in the near-infrared light region; a near-infrared light reflecting part that reflects light in the near-infrared light region; wherein the light of the near-infrared light absorbing part The transmittance is less than 2% as far as the wavelength of light is in the range of 700nm to 750nm; as far as the wavelength of light is in the range of 630nm to 750nm, and the light transmittance is in the range of 2% or more, the aforementioned near-infrared light absorption part The frequency dependence curve of the light transmittance of the light transmittance is on the shorter wavelength side than the frequency dependence curve of the light transmittance of the near-infrared light reflector when the incident angle to the near-infrared light reflector is 0°-30°.

According to the invention described in (21) above, even if the wavelength dependence of the light transmittance in the near-infrared light reflector changes due to the incident angle of the incident light, it is because when the near-infrared light reflector and the near-infrared light reflector are combined The spectral characteristics of the light transmittance in the near-infrared light region when considering the absorbing part are dominated by the spectral characteristics of the light transmittance of the near-infrared light absorbing part. It is difficult to produce differences in the color performance of the obtained image, and the image quality can be achieved. Enhance this excellent effect.

(22) The present invention provides an imaging device having the camera structure described in any one of (1) to (21) above.

According to the above-mentioned invention (22), it is possible to achieve such a remarkable effect that an imaging device equipped with a camera structure with a higher image quality than before can be realized at a low price. [Effects of the invention]

According to the present invention, since the degree of freedom is created in the position where the near-infrared light reflecting part is arranged and the position where the near-infrared light absorption part is arranged, it can be arranged in the most suitable position in the camera structure, and the image quality in the imaging device can be improved. This remarkable effect.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figs. 1 to 10 and Figs. 12 to 14 are examples of the form of implementing the invention, and the parts with the same reference numerals in the figures indicate the same thing.

FIG. 1(A) is a cross-sectional view of the camera structure of the imaging device according to the first embodiment of the present invention, which is suitable for the portable communication device A. FIG.

This camera structure includes a protective glass 215 with a near-infrared light reflecting function for protecting the internal mechanism of the camera from the outside, and a camera module 1. The camera module 1 includes an optical lens group that is the internal mechanism of the imaging device, that is, a lens unit 50, a lens carrier 40 that holds the lens unit 50, and a magnet holder 30 that moves the lens unit 50 in the axial direction in order to realize an autofocus function. , The imaging element 70 that receives the light incident through the cover glass 215 and the lens unit 50 with a near-infrared light reflection function is arranged between the lens unit 50 and the imaging element 70, and the transparent glass that transmits light is attached as a base material. An imaging element cover 244 with a near-infrared light absorption function. The imaging element cover 244 with a near-infrared light absorption function 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. 1(B) is a structural diagram of a cover glass 215 with a near-infrared light reflecting function including a near-infrared light reflecting portion. The cover glass 215 with near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate that transmits light. The anti-reflection film 120 that reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region is formed on the basis of the crystallized glass 130 On the incident side of light. Next, on the outermost side of the light incident side, an antifouling coating film 110 for preventing contamination from the outside is provided. On the light emission side, an anti-reflection film 120 and a near-infrared light reflection film 150 that is a reflection near-infrared reflector that reflects light in the near-infrared light region are sequentially formed from the farthest side with the crystallized glass 130 as a reference.

In addition, in the cover glass 215 with a near-infrared light reflection function, the anti-reflection film 120 closest to the imaging element 70 may not be provided.

Fig. 1(C) is an imaging element cover 244 with a near-infrared light absorbing function, which is provided with a plurality of anti-reflection layers 230 that prevent at least the reflection of light in the visible light region, and further has a near-infrared light absorbing portion, which is a near-infrared light absorbing film 140 structure map. That is, the imaging element cover 244 with a near-infrared light absorption function is provided with anti-reflection layers 230 on both surfaces to prevent reflection of light in the visible light region at least. The anti-reflective layer 230 has a material and structure similar to the anti-reflective film 120, and the manufacturing method is also the same.

The imaging element cover 244 with a near-infrared light absorption function uses a transparent glass 220 as a base material, and a near-infrared light absorption film 140 is provided adjacent to the transparent glass 220. The anti-reflection layer 230 is formed on the light incident side with the transparent glass 220 as a reference, and on the light exit side, an anti-reflection layer 230 and a near-infrared light absorbing film 140 are sequentially provided from the farthest side with the transparent glass 220 as a reference.

That is, the imaging device of the first embodiment of the invention, that is, the camera structure suitable for the portable communication device A includes: an optical lens group (optical unit 50) arranged on the incident side of light, and an optical lens group (optical unit 50) that receives light incident through the lens unit 50 The light-receiving imaging element 70, the near-infrared light reflecting part that reflects light in the near-infrared light region, that is, the near-infrared light reflecting film 150, the near-infrared light absorbing part that absorbs light in the near-infrared light region, that is, the near-infrared light absorbing film 140, and The infrared light reflecting part and the near-infrared light absorbing part are formed as separate cameras. The near-infrared light reflecting film 150 as the near-infrared light reflecting part and the near-infrared light absorbing film 140 as the near-infrared light absorbing part are arranged in this order from the light incident side. The near-infrared light reflecting part, which is the near-infrared light reflecting film 150, in this camera structure includes lens elements constituting the lens unit 50, and is arranged on the light incident side than the lens elements. The near-infrared light absorbing part, which is the near-infrared light absorbing film 140, includes lens elements constituting the lens unit 50 in the camera structure, and is arranged closer to the imaging element 70 than the lens elements. An imaging element cover 244 with a near-infrared light absorbing function that covers at least a part of the imaging element 70 when viewed from the light incident side is arranged between the lens unit 50 and the imaging element 70. The imaging element cover 244 with a near-infrared light absorption function includes the aforementioned imaging element near-infrared light absorption portion. The near-infrared light absorbing part is a near-infrared light absorbing film 140 that absorbs light in the near-infrared light region, and contains an organic pigment. The camera structure further has a protective glass 215 with a near-infrared light reflecting function for protecting the internal mechanism of the camera from the outside, and the protective glass includes a near-infrared light reflecting film 150 that is a near-infrared light reflecting part.

In addition, as a means for realizing the imaging element cover 244 with a near-infrared light absorption function, for example, as a base material, a synthetic resin sheet containing at least a part of an organic dye that absorbs light in the near-infrared light region may be used. Also, like the conventional near-infrared light cut filter, a flat plate of so-called blue glass that absorbs light in the near-infrared light region may be used. It can also be realized by attaching a film that cuts off near-infrared light to a transparent plate.

Generally, crystallized glass is difficult for light to pass through because of its large crystal particles. However, due to recent advances in technology, such as the impact-resistant and high-hardness transparent glass ceramics manufactured by Ohara Corporation, the crystal particles can be controlled to a nanometer size and the light transmittance can be improved. By using such crystallized glass, it is possible to manufacture a protective glass that has both impact resistance and fracture toughness that is hard to generate cracks. Next, by forming the above-mentioned laminated structure on this cover glass, a cover glass 215 with a near-infrared light reflection function is realized. In addition, it is theoretically possible to use blue glass as the protective glass 215 with a near-infrared light reflecting function, but it is not suitable because it has low impact resistance and lacks the fracture toughness that cracks are hard to generate. Although it is possible to form a near-infrared light reflecting film 150 described later on the strengthened glass as a protective glass 215 with a near-infrared light reflecting function, it has the disadvantage of low impact resistance compared to the case where the crystallized glass 130 is used. . In addition, it is possible to form the near-infrared light reflecting film 150 on the sapphire glass with high hardness as the protective glass 215 with near-infrared light reflecting function, but the cost increases significantly and is compared with the case of using the crystallized glass 130 Processability is low.

The anti-fouling coating film 110 prevents fingerprint contamination and sebum contamination, and at the same time, it is easy to wipe off the contamination. The antifouling coating film 110 is formed with a fluorine-based coating agent or the like, and is formed on the outermost side of the light incident side in the laminated structure of the protective glass by coating or spraying.

The anti-reflection film 120 reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region. The anti-reflection film 120 is a dielectric multilayer film, and is formed by alternately laminating a nitride film and an oxide film. The dielectric film constituting the anti-reflection 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. When silicon oxynitride is used, the stoichiometric ratio of oxygen to nitrogen (oxygen/nitrogen) is preferably 1 or less. As the nitride film, silicon oxide (SiO ₂ ), aluminum nitride (Al ₂ O ₃ ), or the like can be used. By using silicon nitride or silicon oxynitride as the anti-reflective film 120, the anti-reflective film 120 can be formed using the same film forming method and film forming device as the near-infrared light reflective film 150 described later. Is advantageous.

The anti-reflective film 120 may also use an oxide film instead of the nitride film. As the material of this oxide film, in addition to silicon oxide, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide ( Nb ₂ O ₅ ) and so on. In addition, when the anti-reflection film 120 is composed of a plurality of types of oxide films having different refractive indexes, it can be appropriately selected from the foregoing oxides.

The anti-reflection film 120 can be formed using a known film forming method, such as a vacuum vapor deposition method, a sputtering method, an ion beam assisted vapor deposition method (IAD method), an ion plating method (IP method), an ion beam sputtering method (IBS method) Wait. For the formation of the nitride film, a sputtering method or an ion beam sputtering method is preferably used.

The near-infrared light absorbing film 140 has a function of absorbing part of the light in the near-infrared light region from the red region while transmitting light in the visible light region. The near-infrared light absorption film 140 contains an organic dye and is composed of a resin film having a maximum absorption wavelength in the range from 650 nm to 750 nm (refer to the dashed line in FIG. 4). Because the near-infrared light absorbing film 140 is adjacent to the crystallized glass 130, the refractive index difference between the two is reduced and the reflectance at the interface is preferably reduced. Because of having such a near-infrared light absorbing film 140, the dependence of the spectral transmittance characteristics due to the incident angle is reduced, and it is possible to have good near-infrared light cutoff.

As the organic dye, azo-based compounds, phthalocyanine-based compounds, cyanine-based compounds, diiminium-based compounds, and the like can be used. As the resin material of the binder (binder of pigment) constituting the near-infrared light absorbing film 140, polyacrylic acid, polyester fiber, polycarbonate, polystyrene, polyolefin, etc. can be used. The resin material may be a mixture of plural resins, or a copolymer of monomers using the above-mentioned resins. In addition, the resin material may be selected as long as it has a high transmittance to light in the visible light region, and it is selected in consideration of compatibility with organic dyes, film formation process, cost, and the like. In addition, in order to improve the ultraviolet light resistance of the near-infrared light absorbing film 140, an inhibitor (matting dye) such as a sulfur compound may be added to the resin material.

For the formation of the near-infrared light absorbing film 140, the following method can be used, for example. First, the resin binder is dissolved in a conventional solvent such as methyl ethyl ketone and toluene, and the above-mentioned organic dye is added to prepare a coating liquid. Next, this coating liquid is applied to the crystallized glass 130 with a desired film thickness by, for example, a spin coating method, and is dried and cured in a drying oven.

The near-infrared light reflection film 150 is, like the anti-reflection film 120, a dielectric multilayer film formed by alternately laminating a plurality of dielectric materials with different refractive indexes. However, the dielectric multilayer film constituting the near-infrared light reflecting film 150 is formed by laminating a plurality of oxide films of different refractive indexes, and the adjacent oxide films are different kinds of oxide films. In the first embodiment, the near-infrared light reflection film 150 is formed by alternately laminating two types of oxide films with dozens of layers. As the oxide film, in addition to silicon oxide, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), etc. are used .

In the near-infrared light reflection film 150, the film thickness of each oxide film is formed at a thickness of λ/4 when the wavelength of the light to be reflected is λ. The light reflected from all the interfaces laminated in this way becomes the same phase when it reaches the incident surface, and as a result of the light strengthening each other, that is, the reflectivity becomes larger near the wavelength λ and functions as a light reflecting film. In this embodiment, the design of the film may be performed so as to reflect light in the near-infrared light region as λ. In addition, the near-infrared light reflection film 150 is also formed by the same film-forming method and film-forming apparatus as the anti-reflection film 120 described above.

The human eye has sensitivity to so-called visible light with a wavelength of 380 nm to 780 nm. On the other hand, an imaging element generally has a sensitivity to light having a longer wavelength including visible light, that is, light having a wavelength of about 1.1 μm. Therefore, after the image captured by the imaging element is made into a photo, it cannot match the natural color tone, which causes a sense of disharmony.

The integrated protective glass 100 with an optical filter function, which has a near-infrared light reflecting part and a near-infrared light absorbing part, is formed as a laminated structure of FIG. 2(A), for example, because it has a dielectric The near-infrared light reflecting film 150 formed of a bulk multilayer film can cut off light with a wavelength of 700 nm or more that cannot be absorbed by the near-infrared light absorbing film 140, and obtain an image with a natural color tone. In addition, if only the near-infrared light reflection film 150 is intended to cut off the light in the near-infrared light region, the reflectance greatly changes due to the incident angle of the incident light as described later. By combining the near-infrared light reflecting film 150 and the near-infrared light absorbing film 140 that has no incident angle dependence on light absorptivity, a near-infrared light cut filter with low light transmittance dependence on the incident angle of light can be constructed .

In addition, because the protective glass 100, which can protect the camera in the smartphone housing 20 from the outside, has the anti-reflection film 120 to cut off light in the ultraviolet region, it is possible to prevent the optical lens group ( The lens unit 50) is degraded by ultraviolet light, and can prevent the near-infrared light absorbing film 140 containing an organic pigment from deteriorating due to ultraviolet light. In addition, with the anti-reflection function of light in the visible light region, more incident light can be absorbed and bright images can be obtained.

In addition, although the anti-reflection film 120 is formed by alternately laminating a nitride film and an oxide film, the nitride film generally has a higher hardness than the oxide film, and in a pencil hardness test, it reaches a hardness of 9H or higher. Therefore, by making the anti-reflection film 120 also include a nitride film, the effect of improving the scratch resistance can be achieved. In addition, the nitride film has a higher filling density and denser than an oxide film. Because its composition does not contain oxygen, it will not become a supply source of oxygen. Therefore, by providing the nitride film on the outside of the near-infrared light absorbing film 140, the intrusion of oxygen and moisture into the near-infrared light absorbing film 140 is prevented, and the effect of suppressing the deterioration of the near-infrared light absorbing film 140 is achieved.

Generally, optical filters have many optical boundary surfaces. On the other hand, a high degree of anti-reflection film is applied to the lens. It is difficult to achieve the same transmittance as that of a lens with an optical filter that cuts off the light in the near-infrared region, and the reflected light is refracted on the lens side. This becomes a cause of diffuse light that generates ghosts in the image. In the conventional camera structure, since the optical filter 60 is placed on the optical path between the lens unit 50 and the imaging element 70, it is difficult to avoid the above-mentioned ghost image because it is placed quite close to the imaging element 70. However, according to the camera structure of this embodiment, since the above-mentioned diffused light is not generated, the effect of significantly improving the image quality can be achieved.

Next, for reference, the spectral transmittance characteristics of the integrated optical filter-equipped cover glass 100 having a near-infrared light reflecting portion and a near-infrared light absorbing portion will be described. The function of the protective glass 100 with the optical filter function, for example, can be divided into the protective glass 215 with the near-infrared light reflection function and the imaging element cover 244 with the near-infrared light absorption function which are separate. Get the same effect.

FIG. 2(B) shows experimental results regarding how the spectral transmittance characteristics of the near-infrared light reflecting film made of a dielectric film depend on the incident angle of light. The incident angle A is defined as shown in Figure 2(C). In addition, "T" on the vertical axis represents the spectral transmittance, and the unit is% (percentage). The "λ" on the horizontal axis represents the wavelength of light in nm (nanometers) (the same applies to the following figure). The sample is one in which _{40 layers of titanium dioxide (TiO 2} ) and silicon _{dioxide (SiO 2} ) are alternately laminated with a predetermined film thickness on glass. The solid line shows the spectral transmittance when the incident angle of light is 0 degrees, and the broken line shows the spectral transmittance when the incident angle of light is 30 degrees. From Fig. 2(B), it can be confirmed that there is a significant difference in the spectral transmittance between 0 degrees and 30 degrees of light incident angles with respect to the light in the red region, that is, the wavelength near 700 nm. If there is such a difference, the tones of the image will change greatly between the center and the periphery of the image, which will cause the final image quality to deteriorate.

FIG. 3 shows experimental results on how the spectral transmittance of the cover glass 100 with an optical filter function including both a near-infrared light absorbing film and a near-infrared light reflecting film depends on the incident angle of light. As the near-infrared light absorption film, a resin film with a thickness of 5 μm or less containing an organic dye is used, and the near-infrared light reflection film has the same configuration as in the case of FIG. 2. The solid line represents the light incident angle of 0 degrees, the dotted line represents the light incident angle of 15 degrees, and the one-dot chain line represents the spectral transmittance when the light incident angle of 30 degrees. It can be confirmed that the incident angle dependence becomes smaller than in the case of FIG. 2.

4 is a comparison of a protective glass 100 (solid line) with an optical filter function provided with a near-infrared light reflecting film 140 and a near-infrared light reflecting film 150, and a protective glass (dashed line) with only a near-infrared light absorbing film 140, A graph of experimental results in the measurement of the spectral transmittance of the protective glass (one-dot chain line) in which only the near-infrared light reflection film 150 is formed. Since the configurations of the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 are the same as in the case of FIGS. 2 and 3, the description is omitted. However, the incident angle of all light is 0 degrees. In the case of only the near-infrared light absorbing film 140, the light of 650 to 750 nm has a strong light absorption, but almost all light of 800 nm or more is transmitted. As mentioned above, since the human eye has the main sensitivity to so-called visible light with a wavelength of 380 nm to 780 nm, if the imaging element 70 is imaged in the region of 800 nm or more with sensitivity, it will become an unnatural image in the human eye as described above. The near-infrared light reflecting film 150 is designed to cut off light with a wavelength of 700 nm or more, but in fact, a rapid decrease in the spectral transmittance is measured near 700 nm. The combination of the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 constitutes a protective glass 100 with an optical filter function. As shown by the solid line in FIG. 4, it can be confirmed that 400 is within the visible light region. ~650nm achieves high transmittance and cuts off light with wavelengths above 700nm.

According to the camera structure of the embodiment of the present invention, the degree of freedom is created in the position where the near-infrared light reflecting part is arranged and the position where the near-infrared light absorbing part is arranged. This remarkable effect of qualitative improvement.

The light on the longer wavelength side than the light of the wavelength absorbed by the near-infrared light absorbing portion may be transmitted. Therefore, after arranging the near-infrared light absorbing part and the near-infrared light reflecting part in order from the light incident side, light with a longer wavelength than the light of the wavelength absorbed by the near-infrared light absorbing part becomes easier to enter the camera module. Before reaching the near-infrared light reflecting part capable of cutting off the light on the long-wavelength side, it becomes diffused light due to reflection on the lens surface or the like, which causes degradation of image quality.

According to the camera structure of the embodiment of the present invention, since the near-infrared light reflecting part and the near-infrared light absorbing part are arranged in order from the light incident side, the near-infrared light reflecting part and the near-infrared light absorbing part are arranged in order to suppress the diffusion on the long wavelength side. The effect of shooting light.

According to the camera structure of the embodiment of the present invention, the near-infrared light reflecting section includes the lens element constituting the optical lens group, and is arranged on the light incident side than the lens element, and at the same position as the previous near-infrared light cut filter. In comparison, the distance from the near-infrared light reflecting part and the imaging element becomes larger. In the near-infrared light reflector, after the incident angle of light is shifted from the axis direction perpendicularly, light in the ultraviolet region may easily pass through. If the distance from the imaging element becomes larger, the angle at which the imaging element can be seen from the near-infrared light reflector becomes smaller, which can reduce the light that passes through the near-infrared light reflector and directly reaches the excess ultraviolet region of the image sensor. .

According to the camera structure of the embodiment of the present invention, the transmittance of the near-infrared light absorbing portion is often independent of the incident angle of light. Therefore, the near-infrared light absorption part in the camera structure includes the lens elements that constitute the optical lens group and is arranged on the side of the imaging element than the lens elements, which can effectively suppress the diffuse incident on the imaging element from all directions. This remarkable effect of shooting light.

If dust, which is difficult for light to pass through, adheres to the imaging element, the image quality will be degraded. According to the camera structure of the embodiment of the present invention, the imaging device cover that covers at least a part of the imaging device when viewed from the light-incident side is arranged between the optical lens group and the imaging device at a position close to the imaging device, so that adhesion can be reduced. This has a remarkable effect on the dust of the imaging element and prevents the deterioration of image quality.

According to the camera structure of the embodiment of the present invention, it is possible to produce an imaging element cover that is less deformed by temperature changes at a low cost.

The imaging device cover is arranged at a position close to the imaging device between the optical lens group and the imaging device. Therefore, when the imaging device cover reflects light, it becomes a cause of significant deterioration of the image quality of the image obtained by the imaging device. According to the camera structure of the embodiment of the present invention, since the imaging element cover is provided with an anti-reflection layer that prevents at least the reflection of light in the visible light region, it is possible to achieve such a remarkable effect of improving image quality.

According to the camera structure of the embodiment of the present invention, it is possible to absorb more incident light and prevent reflected light caused by the imaging element cover, especially to prevent the reflected light from the imaging element itself from being reflected by the imaging element cover and returning to the imaging element , And achieve this remarkable effect of image quality improvement.

According to the camera structure of the embodiment of the present invention, since the imaging element cover includes the near-infrared light absorbing portion, it is possible to achieve remarkable effects such as a reduction in the number of parts and a reduction in the number of processes in the production of the camera structure.

According to the camera structure of the embodiment of the present invention, since the near-infrared light absorbing portion has a near-infrared light absorbing film, the near-infrared light absorbing film contains an organic pigment that absorbs near-infrared light, and is not used as a region for absorbing near-infrared light. The blue glass is generally used as the material of the light filter, and with the low dependency of the incident angle of light, it achieves the effect of suppressing the light in the near-infrared light region.

According to the camera structure of the embodiment of the present invention, since the cover glass has a near-infrared light reflecting film that reflects light, it is possible to achieve the effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging device. In addition, in the area close to the imaging element, it is not necessary to put in a member with a near-infrared light reflecting film, so that the reflection of light incident on the internal mechanism of the imaging device can be suppressed. The effect of reducing the cause of ghosting or flashing.

5 is a graph showing the spectral transmittance of a cover glass with an optical filter function included in the camera structure of the second embodiment of the present invention. In this embodiment, there is provided a so-called dual-band optical filter-equipped cover glass and camera structure capable of capturing images at night. The basic structure of the camera structure is the same as the first embodiment, but instead of the protective glass 215 with the near-infrared light reflection function, a near-infrared light absorbing film 140 and a near-infrared light reflection film 150 with an optical filter function are arranged. The glass 100 is protected, and the imaging element cover 244 (not shown) with a near-infrared light absorption function is omitted.

In addition, the cover glass 215 with a near-infrared light reflecting function is provided with a near-infrared light reflecting film D that increases the light transmittance of a part of the light in the near-infrared light region. Since the film structure of the near-infrared light reflecting film D is a well-known technology, the description is omitted.

Combining the near-infrared light absorbing film 140 shown by the dotted line in FIG. 5 and the near-infrared reflecting film D that increases the light transmittance of a part of the light in the near-infrared light region shown by the one-dot chain line in FIG. The solid line shows the dual-band protective glass that allows part of the light in the visible light region and the light in the near-infrared light region to pass through. However, in FIG. 5, the spectral transmittance of the near-infrared light reflecting film D and the dual-band cover glass is a calculated value at a wavelength of 750 nm or more. According to the glass structure provided with such dual-band protective glass, the remarkable effect of being able to easily see the lane boundary or the outside line of the lane on the road at night can be obtained, and it is suitable for a vehicle-mounted camera.

FIG. 6(A) is a cross-sectional view of the camera structure of the imaging device according to the third embodiment of the present invention, which is suitable for the portable communication device A. FIG. The camera structure includes a protective glass 215 with a near-infrared light reflection function that reflects near-infrared light, a flat plate 217 with a near-infrared light absorption function that absorbs near-infrared light, and an imaging element cover 240 using transparent glass as a base material. Since the other configuration is the same as that of the aforementioned first embodiment, the description is omitted.

Fig. 6(B) is a structural diagram of a protective glass with a near-infrared light reflecting function including a near-infrared light reflecting portion. The cover glass 215 with near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate that transmits light. The anti-reflection film 120 that reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region is formed on the basis of the crystallized glass 130 On the incident side of light. Next, on the outermost side of the light incident side, an antifouling coating film 110 for preventing contamination from the outside is provided. On the light emitting side, an anti-reflection film 120 that prevents at least reflection of light in the visible light region, and a near-infrared light reflection film 150 that reflects light in the near-infrared light region are sequentially formed from the farthest side with the crystallized glass 130 as a reference.

In addition, in the cover glass 215 with a near-infrared light reflection function, the anti-reflection film 120 closest to the imaging element 70 may not be provided.

Fig. 6(C) is a structural diagram of a flat plate 217 with a near-infrared light absorption function. The flat plate 217 with a near-infrared light absorbing function includes a plurality of anti-reflection layers 230 that prevent at least the reflection of light in the visible light region, and further includes a near-infrared light absorbing film 140. The flat plate 217 with a near-infrared light absorption function uses a transparent glass 220 as a base material, and a near-infrared light absorption film 140 is provided adjacent to the transparent glass 220. The anti-reflection layer 230 is formed on the incident side of light based on the transparent glass 220, and on the light-emitting side, the anti-reflection layer 230 and the near-infrared light absorbing film 140 are sequentially provided from the farthest side based on the transparent glass 220.

The flat plate 217 with the near-infrared light absorption function is arranged on the inner structure side, that is, the lens unit 50 side, than the cover glass 215 with the near-infrared light reflection function.

In addition, as a means for realizing the flat plate 217 with a near-infrared light absorption function, for example, as a base material, a synthetic resin sheet containing at least a part of an organic dye that absorbs light in the near-infrared light region may be used. Also, like the conventional near-infrared light cut filter, a flat plate of so-called blue glass that absorbs light in the near-infrared light region may be used. It can also be realized by attaching a film that cuts off near-infrared light to a transparent plate.

FIG. 6(D) is a structural view of an imaging device cover 240 using transparent glass as a base material and a plurality of antireflection layers 230 using transparent glass 220 as a base material. The imaging element cover 240 is provided with anti-reflection layers 230 on both surfaces of the transparent glass 220.

Fig. 6(E) is the camera structure suitable for the portable communication device A in the imaging device of the third embodiment, replacing the imaging element cover 240 with transparent glass as the base material with a transparent synthetic resin film 222 as A part of a modified example of the imaging element cover 242 of the base material. That is, a structural view of the imaging device cover 242 using a transparent synthetic resin film 222 as a base material and a transparent synthetic resin film having a moth-eye structure exhibiting an anti-reflection function on both sides as the base material. The thickness of the imaging element cover 242 using a transparent synthetic resin film as a base material is 0.2 mm or less. The imaging element cover 242 which uses a transparent synthetic resin film as a base material is equipped with the moth-eye structure 232 which prevents at least the reflection of light in a visible light region on both surfaces.

The moth-eye structure does not use interference effects to reduce reflection like a dielectric multilayer film, but reduces reflection by eliminating the boundary surface where the refractive index changes rapidly. Specifically, a fine protrusion structure formed by a large number of fine protrusions having a height of about several hundred nm is formed on the surface, and the repetition period of the protrusions is related to the wavelength range in which the reflection reduction effect appears. Regarding the moth-eye structure because it is a conventional technology, the description is omitted, but in the case of this modified embodiment, for example, a transparent acrylic resin is used as the transparent synthetic resin film 222, and the moth-eye structure is formed by transfer or molding. Anti-reflection function.

That is, the so-called moth-eye structure 232 formed on the surface of the imaging element cover 242 with a transparent synthetic resin film as a base material can prevent light reflection in a wide frequency band. The moth-eye structure 232 has at least an anti-reflection function for light in the visible light region, and it is also desirable to have an anti-reflection function for light in the ultraviolet region and light in the near-infrared light region.

A synthetic resin film having a thickness of 100 μm or less can be easily produced. According to the camera structure of the embodiment of the present invention, it is possible to produce a thin and inexpensive imaging element cover at a low cost.

According to the camera structure of the embodiment of the present invention, it is possible to achieve such a remarkable effect of providing a camera module with a thinner thickness than before.

The anti-reflection layer of the so-called moth-eye structure formed on the surface of the imaging element cover made of fine protrusions can prevent the reflection of light in a wide frequency band. Therefore, according to the camera structure of the embodiment of the present invention, since the anti-reflection layer of the moth-eye structure is formed, the reflected light caused by the imaging element cover can be significantly reduced in a wide frequency band, and this remarkable effect of image quality improvement can be achieved.

As another modified example of the inner transparent flat plate 240, it is also considered that the surface of the transparent synthetic resin film 222, which is the substrate, is formed as an anti-reflection layer by coating a synthetic resin to obtain a multilayer film. Generally, a multilayer film obtained by alternately laminating two types of thin films having mutually different refractive indexes of light can form a light anti-reflection film. Next, it is known that such a multilayer film can be obtained by suppressing the application of synthetic resin.

For example, for two types of synthetic resins with different refractive indexes of light, the refractive index of each of them is higher than that of air and smaller than the refractive index of the transparent synthetic resin film 222. By alternately coating these on the transparent synthetic resin film 222, it is possible to manufacture the inner transparent flat plate 240 having an anti-reflection film of stable quality at a low price. As a method of applying synthetic resin to the transparent synthetic resin film 222, for example, there is a roller coating method. According to this modified embodiment, it is possible to achieve the remarkable effect that the inner transparent flat plate provided with the anti-reflection film can be manufactured in large quantities and at low cost on the basis of stable quality.

FIG. 7(A) is a cross-sectional view of the camera structure of the imaging device according to the fourth embodiment of the present invention, which is suitable for the portable communication device A. FIG. The camera structure includes a protective glass 215 with a near-infrared light reflection function, and a camera module 1. The camera module 1 includes a lens carrier 40 that holds the lens unit 50 and the lens unit 50, an imaging element 70, and an imaging element cover 240. The structure of the cover glass 215 with the near-infrared light reflecting function and the imaging element cover 240 are omitted because they are the same as those described in the third embodiment. Moreover, since the manufacturing method of the near-infrared reflective film 150 and the anti-reflection film 120 is the same as that of 1st Embodiment, description is abbreviate|omitted.

Fig. 7(B) is a cross-sectional view of a lens unit including a lens element having a near-infrared light absorbing portion. The lens unit 50, that is, the optical lens group, is composed of a plurality of lens elements. The lens element arranged closest to the imaging element 70 in the optical lens group is a lens element 250 having a near-infrared light absorbing portion. The near-infrared light absorbing part is an organic dye and is uniformly contained in the synthetic resin forming the lens element 250 having the near-infrared light absorbing part.

Fig. 7(C) is a cross-sectional view of a lens unit including a lens element having a near-infrared light absorbing portion. In this modified embodiment, the lens element having the near-infrared light absorbing portion is realized by providing the near-infrared light absorbing film 140 on the surface of the transparent lens element 255 that is closest to the imaging element 70. The manufacturing method of the near-infrared light absorbing film 140 is omitted because it is the same as that described in the first embodiment.

In addition, the anti-reflection layer 230 may be provided on the near-infrared light absorbing film 140 on the side of the imaging element 70.

According to the embodiment of the present invention, since the near-infrared light reflecting portion that reflects light is provided, it is possible to achieve the effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging device. In addition, in the area close to the imaging element, it is not necessary to put in a member with a near-infrared light reflecting part, and the reflection of light incident on the internal mechanism of the imaging device can be suppressed. As a result, the diffused light can be suppressed, and the The effect of reducing the cause of ghosting or flashing.

According to the embodiment of the present invention, since the near-infrared light absorbing part contains an organic pigment that absorbs near-infrared light, the blue glass that is generally used as a filter material for absorbing light in the near-infrared light region is not used, and light-based The low dependency of the incident angle achieves the effect of suppressing light in the near-infrared light region.

FIG. 8(A) is a cross-sectional view of a camera structure suitable for an imaging device, which is an imaging device according to a fifth embodiment of the present invention. The camera module 1 of this camera structure has a lens carrier 40 holding the lens unit 50 and the lens unit 50 and an imaging element 70, and is fixed to the vehicle body 22. That is, the camera is configured as a so-called vehicle-mounted camera.

8(B) is a cross-sectional view of a lens unit including an optical lens element 270 including a near-infrared light reflecting portion and an optical lens element 250 including a near-infrared light absorbing portion. A near-infrared light reflecting film 150 is provided on the light incident side surface of the lens element 270 provided with a near-infrared light reflecting portion. In the lens element 250 equipped with a near-infrared light absorption part, the near-infrared light absorption part is an organic dye, and it is uniformly contained in the synthetic resin which forms the lens element 250 equipped with a near-infrared light absorption part. As a modified example, the lens element 250 provided with the near-infrared light absorbing portion may be a transparent lens element 255 in which the near-infrared light absorbing film 140 is provided closest to the imaging element 70 (see FIG. 7(C)). In this embodiment, since components that move mechanically such as actuators are not included, dust is unlikely to be generated. In addition, since the surface of the imaging element 70 is slightly perpendicular to the ground, it is difficult for dust to adhere to the imaging element 70. Therefore, the imaging element cover 240 is omitted. On the light incident side of the lens unit 50, a protective glass for preventing contamination may be provided. Of course, the image sensor cover 240 may be provided close to the image sensor 70.

According to this structure, since it can be completed with a small number of parts, the production process can be significantly reduced, and it can be manufactured at low cost. Of course, because it has a near-infrared light reflecting part and a near-infrared light absorbing part, this effect of improving image quality can be achieved.

As a modified example, the lens element 270 equipped with a near-infrared light reflecting portion in the camera structure is in its original state, and the imaging element cover is shown in FIG. 1(C) of the first embodiment by using a near-infrared The imaging element cover 244 having a light absorption function is also considered to have a light absorption function that does not have a near-infrared light region in the lens element.

Fig. 9(A) is a cross-sectional view of a camera structure suitable for an imaging device according to a sixth embodiment of the present invention. The camera structure includes a protective glass 215 with a near-infrared light reflection function, and a camera module 1. The camera module 1 includes a lens carrier 40 that holds the lens unit 50 and the lens unit 50, an imaging element 70, and an imaging element cover 240. The structure of the cover glass 215 with the near-infrared light reflecting function and the imaging element cover 240 are omitted because they are the same as those described in the third embodiment.

FIG. 9(B) is a cross-sectional view of a lens unit including an optical element 500 with a near-infrared light absorption function including a near-infrared light absorption portion. The lens unit 50 includes an optical element 500 with a near-infrared light absorption function on the side closest to the incident side of light. However, if the optical element 500 with a near-infrared light absorption function is inside the lens unit 50, any position on the axis may be sufficient.

FIG. 9(C) is a structural diagram of an optical element 500 with a near-infrared light absorption function. The optical element 500 with a near-infrared light absorbing function includes a plurality of anti-reflection layers 230 that prevent at least the reflection of light in the visible light region, and further includes a near-infrared light absorbing film 140. The flat plate 217 with a near-infrared light absorption function uses a transparent glass 220 as a base material, and a near-infrared light absorption film 140 is provided adjacent to the transparent glass 220. The anti-reflection layer 230 is formed on the light incident side with the transparent glass 220 as a reference, and on the light exit side, an anti-reflection layer 230 and a near-infrared light absorbing film 140 are sequentially provided from the farthest side with the transparent glass 220 as a reference.

In addition, as a means for realizing the optical element 500 with a near-infrared light absorption function, for example, as a base material, a synthetic resin sheet containing at least a part of an organic dye that absorbs light in the near-infrared light region may be used. Also, like the conventional near-infrared light cut filter, a flat plate of so-called blue glass that absorbs light in the near-infrared light region may be used. It can also be realized by attaching a film that cuts off near-infrared light to a transparent plate.

In addition, since the manufacturing method of the near-infrared reflective film 150, the anti-reflection film 120, and the near-infrared light absorption film 140 is the same as that of 1st Embodiment, description is abbreviate|omitted.

Fig. 10(A) is a cross-sectional view of a camera structure suitable for an imaging device according to a seventh embodiment of the present invention. The camera structure includes: a protective glass 550 and a camera module 1. The camera module 1 includes a lens carrier 40 that holds the lens unit 50 and the lens unit 50, an imaging element 70, and an imaging element cover 240. Since the structure of the imaging element cover 240 is the same as that described in the third embodiment, it is omitted.

The cover glass 550 may use conventional strengthened glass, sapphire glass, or the like as the base material. Also, of course, crystallized glass may be used. The cover glass 550 has an anti-reflection film 120 (not shown) that reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region on the surface of the imaging element 70 side.

FIG. 10(B) is a cross-sectional view of a lens unit including an optical element 530 with an optical filter function including a near-infrared light reflecting portion and a near-infrared light absorbing portion. The lens unit 50 includes an optical element 530 with an optical filter function on the side closest to the incidence of light. However, if the optical element 530 with an optical filter function is inside the lens unit 50, any position on the axis may be sufficient.

FIG. 10(C) is a structural diagram of an optical element 530 with an optical filter function. The optical element 530 with an optical filter function includes a plurality of anti-reflection layers 230 that prevent at least the reflection of light in the visible light region, and further includes a near-infrared light absorption film 140. The optical element 530 with an optical filter function uses a transparent glass 220 as a base material, and a near-infrared light absorption film 140 is provided adjacent to the transparent glass 220. The anti-reflection layer 230 is formed on the light incident side based on the transparent glass 220. On the light exit side, the anti-reflection layer 230, the near-infrared light reflecting film 150, and the near-infrared light are sequentially provided from the farthest side based on the transparent glass 220. Light absorption film 140.

In addition, as a means for realizing the optical element 530 with an optical filter function, for example, as a base material, a synthetic resin sheet containing at least a part of an organic dye that absorbs light in the near-infrared light region may be used. Also, like the conventional near-infrared light cut filter, a flat plate of so-called blue glass that absorbs light in the near-infrared light region may be used. It can also be realized by attaching a film that cuts off near-infrared light to a transparent plate. In addition, since the manufacturing method of the near-infrared light absorption film 140, the near-infrared reflective film 150, and the anti-reflection film 120 is the same as that of 1st Embodiment, description is abbreviate|omitted.

According to this camera structure, only the optical element 530 with an optical filter function may be added to the lens unit 50, and the conventional components can be used for other structures. In addition, because an integrated optical element including both the near-infrared light reflecting part and the near-infrared light absorbing part is included in the optical lens group, it is not necessary to incorporate a member having a near-infrared light reflecting film at the position closest to the imaging element. Therefore, the reflection of light incident on the internal mechanism of the imaging device can be suppressed, and as a result, the diffused light can be suppressed, and the effect of reducing the cause of ghosting or flashing can be achieved.

In addition, as a result of further research, the inventor has discovered another problem with the conventional camera structure that a difference in color tone occurs between the center part and the peripheral part of the acquired image. This problem remarkably occurs when the incident angle of incident light becomes large especially in the aspect of the cover glass provided with the near-infrared reflecting part.

FIG. 12(A) is a graph showing the dependence of the spectral characteristics of the light transmittance in the near-infrared light absorbing portion of the conventional light-absorbing ink and the incident light angle of the spectral characteristics of the light transmittance in the near-infrared light reflecting portion . The vertical axis represents the light transmittance T (unit: %), and the horizontal axis represents the wavelength of incident light (unit: nm). Specifically, it is considered to have: an imaging element cover 244 with a near-infrared light absorbing function (refer to FIG. 1(C)) having a near-infrared light absorbing film 140 as a near-infrared light absorbing portion, and as a near-infrared light reflecting portion On the other hand, an optical system with a near-infrared light reflecting film 150 (refer to FIG. 1(B)) and a protective glass 215 with a near-infrared light reflecting function.

In FIG. 12(A), the solid line A1 represents the spectral characteristics of the light transmittance of the imaging element cover 244 alone with the near-infrared light absorption function. The dotted line R1 represents the spectral characteristics of the light transmittance in the protective glass 215 with a near-infrared light reflection function when the incident angle of the incident light is 0°, and the dotted line R2 represents the incident angle of the incident light when the incident angle is 30°. Spectroscopic characteristics of light transmittance in a single protective glass 215 with a near-infrared light reflection function. The curve A1 representing the spectral characteristics of the conventional near-infrared light absorbing ink and the dotted line R2 representing the spectral characteristics of the former near-infrared reflector at an incident angle of 30° almost overlap in the wavelength region of light from 660 to 700 nm. The solid line A1 representing the spectral characteristics of the previous near-infrared light absorbing ink does not overlap with the dotted line R1 representing the spectral characteristics of the previous near-infrared reflector at an incident angle of 0° until the point of intersection near 720 nm.

FIG. 12(B) shows a graph of the incident light angle dependence of the spectral characteristics of the light transmittance when the near-infrared light absorbing portion and the near-infrared light reflecting portion are combined. Specifically, the dotted line C1 is the spectral characteristic when the incident angle is 0°, and the dashed line C2 is the spectral characteristic when the incident angle is 30°. In other words, the spectral characteristic of the optical system combining the solid line A1 and the broken line R1 in FIG. 12(A) is the dashed line C1, and the spectral characteristic of the optical system combining the solid line A1 and the broken line R2 in FIG. 12(A) is the dashed line C2. A gap G1 is generated between the dotted line C1 and the broken line C2 in the range of 660 nm to 690 nm.

Here, the wavelength at which the light transmittance decreases to 10% by increasing the wavelength of incident light is defined as the near-infrared light blocking wavelength. Considering a near-infrared light cut filter with a near-infrared light reflecting part and a near-infrared absorbing part, there may be an angle of the blocking wavelength of the near-infrared light when the incident angle of the incident light is changed within the range of 0° to 30° A situation where the dependent change width becomes about 30 nm occurs. Conversely, in the predetermined light wavelength of the near-infrared light region, the light transmittance of the near-infrared light cut filter greatly varies according to the incident angle of incident light. Specifically, for example, when light with a wavelength of 660 to 690 nm is incident, the light transmittance will be about 20% when the incident angle is small at the center of the acquired image, and the light is transmitted when the incident angle is large at the periphery of the acquired image. As a result, the light wavelength dependence of transmittance differs between the peripheral part and the center part of the acquired image, resulting in a phenomenon where the rate becomes almost 0%, resulting in a phenomenon of deterioration in image quality such as "redness".

As the camera structure of the eighth embodiment of the present invention, there is a camera structure provided with a combination of a near-infrared light absorbing portion using a new light-absorbing ink having spectral characteristics shown in FIG. 13(A) and a new near-infrared light reflecting portion. . The composition of the near-infrared light absorption part is the same as the imaging element cover 244 with near-infrared light absorption function shown in FIG. 1(C), and the composition of the near-infrared light reflection part is the same as that shown in FIG. The protective glass 215 of the light reflection function is the same. Specifically, it is provided with: an imaging element cover 244 with a near-infrared light absorbing function (refer to FIG. 1(C)) having a near-infrared light absorbing film 140 as a near-infrared light absorbing portion, and a near-infrared light reflecting portion On the other hand, an optical system with a near-infrared light reflecting film 150 (refer to FIG. 1(B)) and a protective glass 215 with a near-infrared light reflecting function.

FIG. 13(A) shows the spectral characteristics of light transmittance in the near-infrared light absorbing portion using a new light-absorbing ink, and the dependence of the incident light angle on the spectral characteristics of light transmittance in the new near-infrared light reflecting portion Graphics. The vertical axis represents the light transmittance T (unit: %), and the horizontal axis represents the wavelength of incident light (unit: nm). Specifically, it is considered to have: an imaging element cover 244 with a near-infrared light absorbing function (refer to FIG. 1(C)) having a near-infrared light absorbing film 140 as a near-infrared light absorbing portion, and as a near-infrared light reflecting portion On the other hand, an optical system with a near-infrared light reflecting film 150 (refer to FIG. 1(B)) and a protective glass 215 with a near-infrared light reflecting function.

In FIG. 13(A), the solid line A2 represents the spectral characteristics of the light transmittance of the imaging element cover 244 alone with the near-infrared light absorption function. The dotted line R3 represents the spectral characteristics of the light transmittance in the protective glass 215 with a near-infrared light reflection function when the incident angle of the incident light is 0°, and the dotted line R4 represents the incident angle of the incident light when the incident angle is 30°. Spectroscopic characteristics of light transmittance in a single protective glass 215 with a near-infrared light reflection function.

Specifically, the camera structure of the eighth embodiment of the present invention includes: an absorbing near-infrared light absorbing section 140 that absorbs light in the near-infrared light region; a near-infrared light reflecting section 150 that reflects light in the near-infrared light region; The light absorbing part 140 has a light absorbing wavelength region 700 with a light transmittance of less than 2% in the light wavelength range from 685nm to 755nm. When the wavelength at which the transmittance is reduced by 50% is defined as the cut-off wavelength of near-infrared light, the near-infrared light reflector 150 has the characteristic of slightly totally reflecting light of a wavelength longer than the cut-off wavelength of near-infrared light, and reflects the near-infrared light. When the incident angle of the incident light of the portion 150 changes in the range of 0° to 30°, the near-infrared light cut-off wavelength is usually included in the light absorption wavelength region 700.

In other words, the near-infrared light cut-off wavelength CF1 of the near-infrared light reflector 150 when the incident angle of the incident light is 0° and the near-infrared light cut-off wavelength CF1 of the near-infrared light reflector 150 when the incident angle of the incident light is 30° The wavelength CF2 is included in the light absorption wavelength region 700.

In addition, in the near-infrared light reflecting section 150, as a spectral characteristic of light having a longer wavelength than the cut-off wavelength of near-infrared light, it is preferable that the light transmittance is less than 1% at about 750 nm to 1000 nm. In the wavelength range longer than about 1000 nm, light transmittance of some, for example, several %, may be sufficient.

FIG. 13(B) shows a graph of the incident light angle dependence of the spectral characteristics of the light transmittance when the near-infrared light absorbing portion 140 and the near-infrared light reflecting portion 150 are combined. Specifically, the dotted line C3 is the spectral characteristic when the incident angle is 0°, and the dashed line C4 is the spectral characteristic when the incident angle is 30°. In other words, the spectral characteristic of the optical system combining the solid line A2 and the dashed line R3 in FIG. 13(A) is the dashed line C3, and the spectral characteristic of the optical system combining the solid line A2 and the dashed line R4 in FIG. 13(A) is the dashed line C4.

Here, the wavelength at which the light transmittance decreases to 10% by increasing the wavelength of incident light is defined as the near-infrared light blocking wavelength.

Considering the near-infrared light cut filter having the near-infrared light reflecting part 150 and the near-infrared absorbing part 140, the angle of the blocking wavelength of the near-infrared light when the incident angle of the incident light is changed in the range of 0° to 30° The dependent change width G2 is approximately 5 nm or less. That is, the light transmittance of the near-infrared light cut filter is difficult to make the incident angle of incident light dependent.

When the near-infrared light cut filter has, for example, a near-infrared light reflecting portion 150 provided with a dielectric multilayer film, the frequency dependence of the transmittance of light in the near-infrared light reflecting portion 150 changes depending on the incident angle of incident light. That is, for example, the blocking wavelength of the near-infrared light of the near-infrared light reflector 150 is about 700nm when the incident angle of the incident light is 0°, but when the incident angle of the incident light becomes 30°, an incident of about 675nm occurs. The situation of angular dependence. In this case, when the near-infrared light cut filter has the near-infrared light absorbing part 140, the light transmittance achieved by combining with the near-infrared light reflecting part 150 may vary greatly depending on the incident angle of the incident light. happen. Specifically, a near-infrared light cut filter having a near-infrared light reflecting part 150 and a near-infrared absorbing part 140 blocks the wavelength of the near-infrared light when the incident angle of the incident light varies within the range of 0° to 30°. The angle-dependent change amplitude may become about 30nm. Conversely, in the predetermined light wavelength of the near-infrared light region, the light transmittance of the near-infrared light cutoff filter varies more depending on the incident angle of the incident light. For example, when light with a wavelength of 660 to 690 nm is incident, the light transmittance will be about 20% when the incident angle is small at the center of the acquired image, and the light transmittance will be almost zero when the incident angle is large at the periphery of the acquired image. As a result, the light wavelength dependence of transmittance will be different between the peripheral part and the center part of the acquired image, resulting in the deterioration of image quality such as "redness".

According to the camera structure of the eighth embodiment of the present invention, in the near-infrared light cut filter, the angle of the blocking wavelength of the near-infrared light when the incident angle of the incident light is changed in the range of 0° to 30° is changed depending on the angle If the amplitude is less than 5nm, it is difficult to make a difference in the performance of the color in the image, and the good effect of image quality improvement can be achieved.

As an effect of combining the near-infrared light absorbing portion 140 and the near-infrared light reflecting portion 150, if the transmittance of light at a predetermined wavelength becomes 1% or more, the acquired image will be affected. Therefore, as the spectral characteristics of the near-infrared light absorbing portion 140, in the light wavelength region with a light transmittance of 2% or more, when the light transmittance of the near-infrared light reflecting portion 150 becomes 50%, the image quality of the acquired image will be less than that of the naked eye. The hue when viewed is different. In addition, when the near-infrared light reflecting portion 150 is formed of, for example, a dielectric multilayer film, since the light transmittance changes according to the incident angle of the incident light, the transmittance depends on the light wavelength in the peripheral and central portions of the image. It will be different, causing the so-called "red-leaking" to deteriorate the picture quality.

According to the camera structure of the eighth embodiment of the present invention, the effect of combining the near-infrared light absorbing portion 140 and the near-infrared light reflecting portion 150 is that the light transmittance in the light wavelength region of 685nm to 755nm is less than 1%, which can achieve This is an excellent effect that the difference between the image quality of the image and that of the naked eye becomes smaller. In addition, when the incident angle of the incident light to the near-infrared light reflecting part 150 is changed in the range of 0° to 30°, usually, the cut-off wavelength of the near-infrared light of the near-infrared light reflecting part 150 enters the light transmittance of less than 2 % Of the light absorption wavelength region 700, the incidence angle dependence of the spectral characteristics of light in the near-infrared light region becomes small, because the wavelength of the light acquired at the periphery and the center of the acquired image does not change, and the image quality can be achieved This excellent effect of promotion.

FIG. 14(A) is a cross-sectional view of the camera structure of the imaging device according to the ninth embodiment of the present invention, which is suitable for the portable communication device A. FIG. In the case of this embodiment, the solid-state imaging device is an information communication device or a portable communication device A. The camera is configured to include a cover glass 400 with an optical filter function from the light incident side, and a camera module 501 housed in a housing 520 of a portable communication device A such as a smartphone. The camera module 501 is equipped with a lens unit 450 which is an optical lens group arranged on the side of the cover glass 400 with an optical filter function, and an imaging device that receives light incident through the cover glass 400 and the lens unit 450 with the optical filter function. In the element 570, a near-infrared light cut filter that cuts off light in the near-infrared light region is not arranged between the optical path from the lens unit 450 to the image pickup element 570. As shown in detail in Figure 14(A), it is mainly composed of: a protective glass 400 with an optical filter function, a lens unit 450, a lens carrier 540, a magnet holder 430, an imaging element 570, and a substrate 580, and is fixed to the smart Mobile phone frame 520. The connection between the imaging element 570 and the substrate 580 may be wire bonding or flip chip mounting.

The biggest difference from the conventional camera structure of FIG. 11(A) is that the optical filter 60 (see FIG. 11(A)) that cuts off near-infrared light, which is necessary to improve image quality, is omitted. Instead of this, a filter function that cuts off the light in the near-infrared light region is added to the protective glass 10 that has previously mainly played a role of protecting the camera module 1. By adopting this structure, the overall length of the camera structure can be made shorter than before, and the optical filter 60 is not arranged near the imaging element 70. During the manufacturing process of the optical filter 60, it is possible to achieve The granular dust (particles) adhering to the surface of the filter drops to the surface of the imaging element 70 and has a remarkable effect of deteriorating the image. In addition, in the assembly process of the camera module 1, the process for disposing and assembling the near-infrared light cut filter 60 becomes unnecessary, which can further reduce the cost, increase the yield, and achieve operational efficiency.

In addition, due to the camera structure shown in Fig. 14(A), the portable communication device A can achieve the effect of being smaller, thinner, and cheaper to manufacture.

FIG. 14(B) shows a laminated structure of a cover glass 400 with an optical filter function, which is provided continuously to the housing of the portable communication device A, and protects the internal mechanism camera module from the outside. The cover glass 400 with an optical filter function uses crystallized glass 630 as a transparent substrate that transmits light, reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region, and an anti-reflection film 620 is formed on the basis of the crystallized glass 630 The incident side of the light. Next, on the outermost side of the light incident side, an antifouling coating film 610 for preventing contamination from the outside is provided. On the light emitting side, the crystallized glass 630 is used as a reference to form a near-infrared light reflecting film 650 as a near-infrared reflecting part that reflects light in the near-infrared region, and a near-infrared light reflecting film 650 that absorbs light in the near-infrared region. The near-infrared light absorbing film 640 of the infrared light absorbing part. On the farthest side of the light exit side, an anti-reflection film 620 may be further formed.

Generally, crystallized glass is difficult for light to pass through because of its large crystal particles. However, due to recent advances in technology, such as the impact-resistant and high-hardness transparent glass ceramics manufactured by Ohara Corporation, the crystal particles can be controlled to a nanometer size and the light transmittance can be improved. By using such crystallized glass, it is possible to manufacture a protective glass that has both impact resistance and fracture toughness that is hard to generate cracks. Next, by forming the above-mentioned laminated structure on this cover glass, a cover glass 400 with an optical filter function is realized. In addition, it is theoretically possible to use blue glass as the protective glass 400 with the optical filter function, but it is not suitable because of its low impact resistance and lack of fracture toughness which is difficult to generate cracks. On the strengthened glass, it is possible to form a near-infrared light absorbing film 640 or a near-infrared light reflecting film 650 described later as a protective glass 400 with an optical filter function, but it is compared with the case where crystallized glass 630 is used. , Has the shortcoming of low impact resistance. In the case of high-hardness sapphire glass, it is also possible to form a near-infrared light absorbing film 640 or a near-infrared light reflecting film 650 as a protective glass 400 with an optical filter function, but the cost increases significantly, and it is crystallized when used. In the case of glass 630, the workability is lower than that of the glass 630.

The antifouling coating film 610 prevents fingerprint contamination and sebum contamination, and at the same time, it is easy to wipe off the contamination. The antifouling coating film 610 is formed of a fluorine-based coating agent or the like, and is formed on the outermost side of the light incident side in the laminated structure of the protective glass by coating or spraying.

The anti-reflection film 620 reflects light in the ultraviolet region and suppresses the reflection of light in the visible light region. The anti-reflection film 620 is a dielectric multilayer film, and is formed by alternately laminating a nitride film and an oxide film. The dielectric film constituting the anti-reflection film 620 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. When silicon oxynitride is used, the stoichiometric ratio of oxygen to nitrogen (oxygen/nitrogen) is preferably 1 or less. As the nitride film, silicon oxide (SiO ₂ ), aluminum nitride (Al ₂ O ₃ ), or the like can be used. By using silicon nitride or silicon oxynitride as the anti-reflective film 620, the anti-reflective film 620 can be formed using the same film forming method and film forming apparatus as the near-infrared light reflective film 150 described later. Is advantageous.

The anti-reflection film 620 may also use an oxide film instead of the nitride film. As the material of this oxide film, in addition to silicon oxide, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide ( Nb ₂ O ₅ ) and so on. In addition, when the anti-reflection film 120 is composed of a plurality of types of oxide films having different refractive indexes, it can be appropriately selected from the foregoing oxides.

The anti-reflection film 620 can be formed using a known film forming method, such as a vacuum vapor deposition method, a sputtering method, an ion beam assisted vapor deposition method (IAD method), an ion plating method (IP method), and an ion beam sputtering method (IBS method) Wait. For the formation of the nitride film, a sputtering method or an ion beam sputtering method is preferably used.

The near-infrared light absorbing film 640 is formed on the surface of the crystallized glass 630 on the opposite side of the anti-reflection film 620, that is, on the imaging element 570 side of the cover glass 400 with the optical filter function (see FIG. 14(A)) . The near-infrared light absorbing film 640 has a function of absorbing part of the light in the near-infrared light region from the red region while transmitting light in the visible light region. The near-infrared light absorption film 640 contains an organic dye, and is composed of a resin film having a maximum absorption wavelength in the range from 700 nm to 750 nm (see FIG. 13(A) solid line A2). Since the near-infrared light absorbing film 640 is adjacent to the crystallized glass 630, the refractive index difference between the two is reduced and the reflectance at the interface is preferably reduced. With such a near-infrared light absorbing film 640, the dependence of the spectral transmittance characteristics due to the angle of incidence is reduced, and it is possible to have good near-infrared light cutoff.

As the organic dye, azo-based compounds, phthalocyanine-based compounds, cyanine-based compounds, diiminium-based compounds, and the like can be used. As the resin material of the binder (binder for pigment) constituting the near-infrared light absorbing film 640, polyacrylic acid, polyester fiber, polycarbonate, polystyrene, polyolefin, etc. can be used. The resin material may be a mixture of plural resins, or a copolymer of monomers using the above-mentioned resins. In addition, the resin material may be selected as long as it has a high transmittance to light in the visible light region, and it is selected in consideration of compatibility with organic dyes, film formation process, cost, and the like. In addition, in order to improve the ultraviolet light resistance of the near-infrared light absorbing film 640, an inhibitor (matting dye) such as a sulfur compound may be added to the resin material.

For the formation of the near-infrared light absorption film 640, the following method can be used, for example. First, the resin binder is dissolved in a conventional solvent such as methyl ethyl ketone and toluene, and the above-mentioned organic dye is added to prepare a coating liquid. Next, this coating liquid can be applied to the crystallized glass 630 with a desired film thickness by, for example, a spin coating method, and it can be dried and cured in a drying oven.

The near-infrared light reflection film 650 is, like the anti-reflection film 620, a dielectric multilayer film formed by alternately laminating a plurality of dielectric materials with different refractive indexes. However, the dielectric multilayer film constituting the near-infrared light reflection film 650 is formed by laminating a plurality of oxide films of different types of refractive index, and the adjacent oxide films are different types of oxide films. In the first embodiment, the near-infrared light reflection film 650 is formed by alternately laminating two types of oxide films in several dozen layers. As the oxide film, in addition to silicon oxide, titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), etc. are used .

In the near-infrared light reflection film 650, the film thickness of each oxide film is formed at a thickness of λ/4 when the wavelength of the light to be reflected is λ. The light reflected from all the interfaces that are alternately laminated in this way becomes the same phase when it reaches the incident surface, and the lights strengthen each other, that is, the reflectance increases near the wavelength λ and functions as a light reflection film. In this embodiment, the design of the film may be performed so as to reflect light in the near-infrared light region as λ. In addition, the near-infrared light reflective film 650 is also formed by the same film forming method and film forming apparatus as the anti-reflection film 620 described above.

The human eye has sensitivity to so-called visible light with a wavelength of 380 nm to 780 nm. On the other hand, an imaging element generally has a sensitivity to light having a longer wavelength including visible light, that is, light having a wavelength of about 1.1 μm. Therefore, after the image captured by the imaging element is made into a photo, it cannot match the natural color tone, which causes a sense of disharmony.

After the cover glass 400 with optical filter function is formed, for example, as the laminated structure shown in FIG. The infrared light absorbing film 640 cuts off light with a wavelength of 700 nm or more that cannot be absorbed completely, and an image with a natural color tone is obtained.

The wavelength dependence of the light transmittance of the near-infrared light reflection film 650 is shown in FIG. 13(A). Specifically, the dotted line R3 represents the spectral characteristics of the light transmittance of the near-infrared light reflecting film 650 when the incident angle of incident light is 0°, and the dotted line R4 represents the near-infrared light when the incident angle of incident light is 30°. The spectral characteristics of the light transmittance in the reflective film 650 alone.

In this embodiment, as the wavelength of the incident light to the near-infrared light reflecting film 650 increases, the light transmittance decreases and the wavelength at which 50% becomes 50% is defined as the near-infrared light cutoff wavelength. When the incident angle of the incident light of the reflecting part 650 changes in the range of 0° to 30°, usually, the cut-off wavelength of the near-infrared light of the near-infrared light reflecting part 650 enters the light absorption wavelength region 700 where the light transmittance is less than 2%. , The incidence angle dependence of the spectral characteristics of light in the near-infrared light region becomes smaller, because the wavelength of the light acquired at the periphery and the center of the acquired image does not change, and the excellent effect of image quality improvement can be achieved. .

That is, by combining the near-infrared light reflecting film 650 and the near-infrared light absorbing film 640 that has no incident angle dependence on light absorptivity, it is possible to form a near-infrared light cutoff with low light transmittance dependence on the incident angle of light. Filter (refer to Figure 13(B)).

In addition, because the protective glass 400 that can protect the camera in the smartphone housing 520 from the outside is blocked by the anti-reflection film 620, it is possible to prevent the optical lens group ( The lens unit 450) is degraded by ultraviolet light, and can prevent the near-infrared light absorption film 640 containing an organic pigment from deteriorating due to ultraviolet light. In addition, with the anti-reflection function of light in the visible light region, more incident light can be absorbed and bright images can be obtained.

In addition, although the anti-reflection film 620 is formed by alternately laminating a nitride film and an oxide film, the nitride film generally has a higher hardness than the oxide film, and in a pencil hardness test, it reaches a hardness of 9H or higher. Therefore, by making the anti-reflection film 120 also include a nitride film, the effect of improving the scratch resistance can be achieved. In addition, the nitride film has a higher filling density and denser than an oxide film. Because its composition does not contain oxygen, it will not become a supply source of oxygen. Therefore, by providing the nitride film on the outside of the near-infrared light absorbing film 640, the intrusion of oxygen and moisture into the near-infrared light absorbing film 640 is prevented, and the effect of suppressing the deterioration of the near-infrared light absorbing film 640 is achieved.

Generally, optical filters have many optical boundary surfaces. On the other hand, a high degree of anti-reflection film is applied to the lens. It is difficult to achieve the same transmittance as that of a lens with an optical filter that cuts off the light in the near-infrared region, and the reflected light is refracted on the lens side. This becomes a cause of diffuse light that generates ghosts in the image. In the conventional camera structure, the optical filter 60 is placed on the optical path between the lens unit 50 and the imaging element 70, and because it is placed quite close to the imaging element 70, it is difficult to avoid the above-mentioned ghost image (refer to FIG. 11( A)). However, according to the camera structure of this embodiment, since the above-mentioned diffused light is not generated, the effect of significantly improving the image quality can be achieved.

According to the ninth embodiment of the present invention, it is possible to achieve such a remarkable effect that an imaging device equipped with a camera structure with improved image quality can be realized at a low price.

In addition, the camera structure and imaging device of the embodiments of the present invention are not limited to those defined in the above-mentioned embodiments, and it is of course possible to add various changes without departing from the scope of the gist of the present invention.

1: Camera module 10: Protective glass 20: Smartphone frame 22: car body 30: Magnet bracket 40: lens carrier 50: lens unit 60: Optical filter 70: image sensor 80: substrate 100: Protective glass with optical filter function 110: Antifouling coating film 120: Anti-reflective film 130: Crystallized glass 140: Near infrared light absorption film 150: Near-infrared light reflecting film 160: incident surface 170: exit surface 180: Measurement object 190: Incident light 200: vertical axis 210: Protective glass with optical filter function 215: Protective glass with near-infrared light reflection function 217: Flat panel with near-infrared light absorption function 220: clear glass 222: Transparent synthetic resin film 230: Anti-reflective film 232: Moth Eye Structure 240: Camera element cover 242: Image sensor cover using transparent synthetic resin film as base material 244: Imaging element cover with near-infrared light absorption function 250: Lens element with near-infrared light absorption part 255: Transparent lens element 270: Lens element with near-infrared light reflecting part 300: light source 310: High reflective material 320: Low reflection material 360: clear glass 370: Anti-reflective film 380: blue glass 390: Near-infrared light reflecting film 400: Protective glass with optical filter function 430: Magnet bracket 450: lens unit 500: Optical element with near-infrared light absorption function 501: Camera Module 520: smart phone frame 530: Optical components with optical filter function 540: lens carrier 550: protective glass 570: image sensor 580: substrate 610: Antifouling coating film 620: Anti-reflective film 630: Crystallized glass 640: Near-infrared light absorption film (near-infrared light absorption part) 650: Near-infrared light reflecting film (near-infrared light reflecting part) 700: Light absorption wavelength region A: Carry communication equipment A1: The spectroscopic characteristics of the previous near-infrared light absorption ink A2: Spectroscopic characteristics of the new near-infrared light absorption ink C1: Spectroscopic characteristics at an incident angle of 0° C2: Spectroscopic characteristics at an incident angle of 30° C3: Spectroscopic characteristics at an incident angle of 0° C4: Spectroscopic characteristics at an incident angle of 30° G: Ghost R1: Spectral characteristics of the former near-infrared reflector at an incident angle of 0° R2: Spectral characteristics of the former near-infrared reflector at an incident angle of 30° R3: Spectral characteristics of the new near-infrared reflector at an incident angle of 0° R4: Spectral characteristics of the new near-infrared reflector at an incident angle of 30°

[Fig. 1] (A) A cross-sectional view of the camera structure of the imaging device according to the first embodiment of the present invention, which is suitable for use in a portable communication device A. (B) The structure diagram of the protective glass with the near-infrared light reflecting function including the near-infrared light reflecting part. (C) A structural diagram of an imaging device cover with a near-infrared light absorbing function including a near-infrared light absorbing portion. [Fig. 2] (A) A structural diagram of a cover glass with an optical filter function. (B) shows the dependence of the incident angle on the spectral transmittance of the near-infrared light reflecting film. (C) An explanatory diagram explaining the definition of the incident angle. [Fig. 3] A graph showing the incidence angle dependence of the spectral transmittance in a cover glass with an optical filter function including a near-infrared light absorbing film and a near-infrared light reflecting film. [Fig. 4] A graph comparing the spectral transmittance of cover glass with an optical filter function, glass with a near-infrared light-absorbing film, and glass with a near-infrared light-reflecting film. [Fig. 5] An explanatory diagram explaining the spectral transmittance of a dual-band cover glass. [FIG. 6] (A) A cross-sectional view of the camera structure of the imaging device according to the third embodiment of the present invention, which is suitable for the portable communication device A. (B) The structure diagram of the protective glass with the near-infrared light reflecting function including the near-infrared light reflecting part. (C) A structural diagram of a flat panel with near-infrared light absorption function. (D) A structural view of an imaging device cover provided with a plurality of antireflection layers using transparent glass as a base material. (E) A structural diagram of an imaging device cover provided with a transparent synthetic resin film of a moth-eye structure exhibiting an anti-reflection function on both sides as a base material. [FIG. 7] (A) A cross-sectional view of the camera structure of the imaging device according to the fourth embodiment of the present invention, which is suitable for the portable communication device A. (B) A cross-sectional view of a lens unit including an optical lens element including a near-infrared light absorbing portion. (C) A cross-sectional view of a lens unit including an optical lens element provided with a near-infrared light absorption portion. [Fig. 8] (A) A cross-sectional view of a camera structure suitable for an imaging device according to a fifth embodiment of the present invention. (B) A cross-sectional view of a lens unit including an optical lens element including a near-infrared light reflecting portion and an optical lens element including a near-infrared light absorbing portion. [FIG. 9] (A) A cross-sectional view of a camera structure suitable for an imaging device according to a sixth embodiment of the present invention. (B) A cross-sectional view of a lens unit including an optical element with a near-infrared light absorbing function including a near-infrared light absorbing portion. (C) A structural diagram of an optical element with near-infrared light absorption function. [Fig. 10] (A) A cross-sectional view of a camera structure suitable for an imaging device according to a seventh embodiment of the present invention. (B) A cross-sectional view of a lens unit including an optical element with an optical filter function including a near-infrared light reflecting portion and a near-infrared light absorbing portion. (C) A structural diagram of an optical element 530 with an optical filter function. [FIG. 11] (A) A cross-sectional view of the structure of a conventional camera in a portable communication device. (B) An explanatory diagram explaining the experimental method of the experiment conducted with the conventional camera structure. (C) Sectional view of protective glass. (D) A cross-sectional view of a conventional near-infrared light cut filter. (E) The image captured by the previous camera structure. [FIG. 12] (A) shows the dependence of the spectral characteristics of the light transmittance in the near-infrared light absorbing portion of the conventional light absorbing ink and the incident light angle of the spectral characteristics of the light transmittance in the near-infrared light reflecting portion Graphics. (B) A graph showing the incident light angle dependence of the spectral characteristics of the light transmittance when the near-infrared light absorbing portion and the near-infrared light reflecting portion are combined. [Figure 13] (A) shows the spectral characteristics of the light transmittance in the near-infrared light absorption portion of the light-absorbing ink with a wider absorption band than before in the near-infrared light region, and the light transmittance in the near-infrared light reflecting portion A graph of the dependence of the incident light angle on the spectroscopic characteristics. (B) A graph showing the incident light angle dependence of the spectral characteristics of the light transmittance when the near-infrared light absorbing portion and the near-infrared light reflecting portion are combined. [FIG. 14] (A) A cross-sectional view of the camera structure of the imaging device according to the ninth embodiment of the present invention, which is suitable for the portable communication device A. (B) A structural diagram of a cover glass with an optical filter function provided with a plurality of anti-reflection films.

1: Camera module

20: Smartphone frame

30: Magnet bracket

40: lens carrier

50: lens unit

70: image sensor

80: substrate

110: Antifouling coating film

120: Anti-reflective film

130: Crystallized glass

140: Near infrared light absorption film

150: Near-infrared light reflective film

215: Protective glass with near-infrared light reflection function

220: clear glass

230: Anti-reflective film

244: Imaging element cover with near-infrared light absorption function

A: Carry communication equipment

Claims (5)

A camera structure including: a near-infrared light absorbing part that absorbs light in the near-infrared light region; a near-infrared light reflecting part that reflects light in the near-infrared light region; wherein the aforementioned near-infrared light absorbing part has a light wavelength of 685nm~ In the 755nm region, there is a light absorption wavelength region with a light transmittance of less than 2%; as the wavelength of the incident light to the near-infrared light reflector increases and the light transmittance decreases, the wavelength is defined as 50% When it is the cut-off wavelength of the near-infrared light, the near-infrared light reflecting section has the characteristic of slightly totally reflecting light of a wavelength longer than the cut-off wavelength of the near-infrared light; the incident angle of the incident light to the near-infrared light reflecting section is When the range of 0°~30° is changed, the aforementioned near-infrared light cut-off wavelength is usually included in the aforementioned light absorption wavelength region. The camera structure described in claim 1, including: a protective glass that protects the internal mechanism of the imaging device from the outside; an optical lens group arranged on the protective glass side; receiving light incident through the protective glass and the optical lens group The imaging element; wherein the aforementioned protective glass has: a transparent substrate that transmits light; the aforementioned near-infrared light absorbing portion; The near-infrared light reflecting portion; wherein, between the optical lens group to the optical path of the imaging element, there is no near-infrared light cut filter that cuts off light in the near-infrared light region. A camera structure with a near-infrared light cut-off filter that blocks light in the near-infrared light region; wherein the aforementioned near-infrared light cut-off filter increases the wavelength of incident light and reduces the light transmittance to a wavelength of 10% When defined as the cut-off wavelength of near-infrared light, the angular dependence of the cut-off wavelength of the near-infrared light when the incident angle of the incident light is changed in the range of 0° to 30° is 5 nm or less. A camera structure including: a near-infrared light absorbing part that absorbs light in the near-infrared light region; a near-infrared light reflecting part that reflects light in the near-infrared light region; The wavelength is less than 2% in the range of 700nm~750nm; as far as the wavelength of light is in the range of 630nm~750nm, and the light transmittance is in the range of 2% or more, the frequency of the light transmittance of the aforementioned near-infrared light absorption part The dependence curve is on the shorter wavelength side than the frequency dependence curve of the light transmittance of the near-infrared light reflecting portion when the incident angle to the near-infrared light reflecting portion is 0° to 30°. An imaging device having the camera structure described in any one of claims 1 to 4.

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