KR102169130B1 - Camera structure, imaging device - Google Patents

Abstract

A camera structure that performs imaging, comprising: an optical lens group disposed on an incident side of light; an imaging element receiving light incident through the optical lens group; a near-infrared light reflecting portion that reflects light in a near-infrared region; and a near-infrared A camera structure, comprising: a near-infrared light absorbing portion for absorbing light in a region, and wherein the near-infrared light reflecting portion and the near-infrared light absorbing portion are separate bodies. This provides a camera structure capable of reducing ghosting and flare.

Description

Camera structure, imaging device

The present invention relates to a camera structure installed in an imaging device.

In this century, as an imaging device, that is, a camera, an imaging device using a solid-state imaging device (imaging device), a so-called digital camera, has become mainstream. In addition, information communication devices such as personal computers (PCs), tablet PCs, and smartphones are widely used and are being used on a daily basis. These information and communication devices often incorporate a small camera module, and at present, there are cases with high-performance ones in which the number of pixels of the imaging device exceeds 10 million. Information and communication devices, particularly smart phones, which are portable communication devices, tend to be thin and light, and camera modules, which are parts, also require miniaturization and space saving. In addition, since smartphones are often the only imaging device for users, there is a strong demand for better image quality even if the camera module becomes small.

BACKGROUND ART In recent years, the demand for automatic driving of automobiles is also increasing, and in some vehicle models, automatic garage wear, automatic brakes, and night driving assistance using on-vehicle cameras have already been put into practical use. Camera modules used in on-vehicle cameras are also being made smaller and higher in performance, and there is a strong demand for removing noise such as ghosts from images for image recognition.

In addition, when the lens of the imaging device is directed toward a light source having a high light intensity, a phenomenon in which an unnecessary image is reflected by repeating light reflection on the lens surface is called a flare phenomenon (flare) or a ghost phenomenon (ghost). A phenomenon in which a part of an image is excessively exposed is called a flare phenomenon, and a phenomenon in which a clearly unnecessary image is reflected by repeating light reflection from the lens surface is called a ghost phenomenon.

As shown in Fig. 11A, the camera module 1 having a conventional camera structure includes a lens unit 50, a lens carrier 40, a magnet holder 30, an optical filter 60, and an image pickup device. It is mainly composed of 70, and is fixed to the smartphone housing 20 (for example, see Japanese Laid-Open Patent No. 2013-153361). Among these, the optical filter 60 mainly serves to cut light in the near-infrared region. The human eye has sensitivity to light (visible light) in the visible region with a wavelength of 380 nm to 780 nm. On the other hand, the imaging device 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, if the image captured by the imaging device is taken as a photograph, it is not visible to the human eye as a natural color tone and causes a sense of discomfort. Therefore, the camera module 1 was configured to incorporate an optical filter 60 (near-infrared light cut filter) that cuts light in the near-infrared region.

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

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

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

Fig. 11B is an explanatory diagram illustrating an experimental method of an experiment conducted 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 having a center wavelength of 460 nm was used as the light source 300. To make it easier to see the flare or ghost phenomenon that occurs, a low reflective material 320 is disposed in the background of the light source 300 and a high reflective material 310 is placed around the low reflective material 320.

A 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 cutting filter 60 is disposed between the optical lens group 50 and the imaging element 70.

11C is a cross-sectional view of the cover glass 10. The cover glass 10 includes an antireflection film 370 on the transparent glass 360. The antireflection film 370 is provided on the optical lens group 50 side of the transparent glass 360.

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

FIG. 11E is an image captured by the imaging element 70 of the conventional camera structure described in FIGS. 11A to 11D. It can be seen that a petal-shaped ghost G occurs around the light source 300 and the image quality is deteriorated. This ghost phenomenon may occur even when the central wavelength of the light source 300 is changed to 420 nm to 660 nm.

Patent Document 1: Japanese Laid-Open Patent No. 2013-153361

In order to reduce the ghost phenomenon and the flare phenomenon, it is generally necessary to make the optical lens group provided in the camera a more complex structure, and to improve the anti-reflection coating of the lens element itself. However, this has been a difficult problem for a camera module of an information communication device or a camera module of an on-vehicle camera, which is required to be small and light and inexpensive.

As a major cause of the ghost phenomenon, a near-infrared cut filter including a reflective film for near-infrared light is located in the vicinity of the imaging element. Therefore, by arranging the near-infrared light reflecting part on the outer field side of the camera module as far as possible, for example, on the cover glass, it is possible to significantly suppress the ghost phenomenon. In addition, by bringing the near-infrared light reflector to the outside, in order to prevent shifting of the cut-off wavelength of the near-infrared light that may occur when light having a large incident angle enters the camera module, the spectral characteristics of the near-infrared light absorber and the near-infrared light reflector By adjusting the spectral characteristics, the image quality does not depend on the angle of the incident light.

(1) The present invention is a camera structure that performs image pickup, comprising: an optical lens group disposed on the incident side of light; an imaging element that receives light incident through the optical lens group; and a near-product that reflects light in the near-infrared region. An external light reflecting unit and a near infrared light absorbing unit for absorbing light in a near infrared region are provided, and the near infrared light reflecting unit and the near infrared light absorbing unit are provided as separate bodies.

According to the invention of the above (1), since the degree of freedom is generated in the place where the near-infrared light reflecting unit is disposed and the place where the near-infrared light absorbing unit is disposed, it is possible to place the camera at an optimum position in each of the camera structures, resulting in a remarkable effect of improving image quality .

(2) In the present invention, the near-infrared light reflecting part and the near-infrared light absorbing part are sequentially arranged from the incident side of light to the near-infrared light reflecting part and the near-infrared light absorbing part. Provides structure.

Light on the longer wavelength side than the light of the wavelength absorbed by the near-infrared light absorbing unit may be transmitted through. Therefore, if the light from the incident side is sequentially arranged as a near-infrared light absorbing unit and a near-infrared light reflecting unit, light on the long wavelength side is more likely to enter the camera module than light of the wavelength absorbed by the near-infrared light absorption unit, and light on the long wavelength side is cut. Before reaching the possible near-infrared light reflector, it reflects on the lens surface and becomes stray light, resulting in deterioration of image quality.

According to the invention of the above (2), since the near-infrared light reflecting portion and the near-infrared light absorbing portion are sequentially arranged as a near-infrared light reflecting portion and a near-infrared light absorbing portion from the incident side of light, the effect of suppressing stray light on the long wavelength side is exhibited.

(3) In the present invention, the near-infrared light reflecting unit includes a lens element constituting the optical lens group in the camera structure, and is disposed on an incident side of light rather than the lens element. Alternatively, the camera structure described in (2) is provided.

According to the invention of the above (3), since the near-infrared light reflecting portion includes a lens element constituting the optical lens group, and is disposed on the incident side of light than the lens element, from the near-infrared light reflecting portion than the position of the conventional near-infrared light cut filter. The distance from the imaging device increases. In the near-infrared light reflecting portion, if the incident angle of light deviates from the vertical in the axial direction, the light in the ultraviolet region may easily pass through. As the distance from the imaging device increases, the angle at which the imaging device is viewed from the near-infrared light reflecting unit decreases, and thus, the light in the extra ultraviolet region that passes through the near-infrared light reflecting unit and directly reaches the imaging device can be reduced.

(4) In the present invention, the near-infrared light absorbing portion includes a lens element constituting the optical lens group in the camera structure, and is disposed on an imaging element side than the lens element. The camera structure according to any one of to (3) is provided.

According to the invention of the above (4), the transmittance of the near-infrared light absorbing portion does not depend on the incident angle of light in many cases. Therefore, the near-infrared light absorbing unit includes a lens element constituting the optical lens group in the camera structure, and is disposed on the side of the image pickup device rather than this lens element, thereby effectively suppressing stray light that is intended to enter the image pickup device from various directions. Represents.

(5) In the present invention, the image pickup device cover covering at least a part of the image pickup device as viewed from the side to which light is incident is disposed between the optical lens group and the image pickup device. The camera structure according to any one of (4) is provided.

When dust, which is difficult to transmit light, adheres on the imaging device, image quality deteriorates. According to the invention of (5) above, the imaging device cover covering at least a part of the imaging device as viewed from the side where light is incident is disposed in a position close to the imaging device between the optical lens group and the imaging device, so that it is attached to the imaging device. It has a remarkable effect in that it can prevent deterioration of image quality by reducing possible dust.

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

According to the invention of (6) above, it is possible to produce an image pickup device cover with little deformation due to temperature change at low cost.

(7) The present invention provides the camera structure according to (5), characterized in that the imaging device cover is a synthetic resin film.

The synthetic resin film can be easily manufactured with a thickness of 100 μm or less. According to the invention of the above (7), there is an effect that a thin and inexpensive imaging device cover can be manufactured at low cost.

(8) The present invention provides the camera structure according to any one of (5) to (7), wherein the thickness of the image pickup device cover is 0.2 mm or less.

According to the invention of (8) above, a remarkable effect can be achieved in that a camera module having a thinner thickness than the conventional one can be provided.

(9) The present invention provides the camera structure according to any one of (5) to (8), wherein the image pickup device cover includes an antireflection layer that prevents reflection of light in at least a visible region. .

The imaging element cover is disposed at a position close to the imaging element between the optical lens group and the imaging element. Therefore, when the image pickup device cover reflects light, it becomes a cause of remarkably deteriorating the image quality of an image acquired by the image pickup device.

According to the invention of the above (9), the image pickup device cover has a remarkable effect that the image quality is improved by including an antireflection layer that prevents reflection of light in at least the visible region.

(10) The present invention provides the camera structure according to any one of (5) to (8), characterized in that, on both surfaces of the imaging device cover, an antireflection layer for preventing reflection of light in at least a visible region is provided. to provide.

According to the invention of the above (10), it is possible to introduce more incident light, and it is possible to prevent the reflected light caused by the imaging element cover, especially the reflected light from the imaging element itself, from being reflected back to the imaging element cover and returning to the imaging element. As a result, the image quality is improved.

(11) The present invention provides the camera structure according to (9) or (10), wherein the antireflection layer is a fine protrusion structure made of fine protrusions formed on the surface of the imaging device cover.

An antireflection layer having a fine protrusion structure made of fine protrusions formed on the surface of the imaging device cover, a so-called Mohs eye structure, prevents reflection of light over a wide area. Accordingly, according to the invention of the above (12), by forming the anti-reflection layer having a Mohs-eye structure, the reflected light caused by the image pickup device cover is remarkably reduced over a wide area, and the image quality can be improved.

(12) The present invention provides the camera structure according to (9) or (10), wherein the antireflection layer is a coating film formed on the surface of the inner transparent plate.

A multilayer film in which two types of thin films having different refractive indices of light are alternately stacked can form an antireflection film of light. In addition, it is known that such a multilayer film can be obtained by applying a synthetic resin. According to the invention of the above (12), there is a remarkable effect that it is possible to manufacture an inner transparent plate provided with an anti-reflection film of stable quality in a large amount at low cost.

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

According to the invention of the above (13), since the imaging device cover includes a near-infrared light absorbing portion, it has a remarkable effect of reducing the number of parts and reducing the number of steps in manufacturing the camera structure.

(14) In the present invention, the near-infrared light absorbing portion is a near-infrared light absorbing film that absorbs light in the near-infrared region, and contains an organic dye, according to any one of (1) to (13) above. Provides a camera structure.

According to the invention of (14) above, since the near-infrared light absorbing portion has a near-infrared light absorbing film, and the near-infrared light absorbing film contains an organic pigment that absorbs near-infrared light, it is generally used as a filter material for absorbing light in the near-infrared region. It is possible to suppress the light in the near-infrared light region without using the blue glass to be used and with little dependence on the incident angle of light.

(15) In the present invention, the camera structure further includes a cover glass that protects the internal mechanism of the imaging device from the outside, and the cover glass includes the near-infrared light reflecting portion, the above (1) to ( The camera structure described in any one of 14) is provided.

According to the invention of the above (15), since the cover glass has a near-infrared light reflecting film that reflects light, the effect of not allowing near-infrared light from outside to enter the internal mechanism of the imaging device can be exhibited. In addition, since there is no need to put a member having a near-infrared light reflecting film in an area close to the image pickup device, reflection of light incident on the internal mechanism of the image pickup device can be suppressed, and as a result, stray light is suppressed to reduce the cause of ghost or flare. It can have a reducing effect.

(16) The present invention is a camera structure that performs imaging, comprising: an optical lens group disposed on the incident side of light; an imaging element that receives light incident through the optical lens group; and a near-infrared reflecting light in the near-infrared region. An external light reflecting part and a near-infrared light absorbing part for absorbing light in a near-infrared region, wherein the near-infrared light reflecting part and the near-infrared light absorbing part are included in an integrated optical element included in the optical lens group. Provides a camera structure.

According to the invention of (16) above, since an integrated optical element including a near-infrared light reflecting portion and a near-infrared light absorbing portion at the same time is included in the optical lens group, it is not necessary to put a member having a near-infrared light reflecting film in a position close to the imaging element. . Accordingly, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and consequently, stray light can be suppressed to reduce the cause of ghosts and flares.

(17) The present invention includes a near-infrared light absorbing unit that absorbs light in the near-infrared region, and a near-infrared light reflecting unit that reflects light in the near-infrared region, and the near-infrared light absorbing unit includes a wavelength of 685 nm to 755 nm. In the case of defining the wavelength to be 50% by having a light-absorption wavelength range in which the light transmittance is less than 2%, the transmittance of light decreases as the wavelength of the incident light to the near-infrared light reflecting unit increases and becomes 50%, the near-infrared light cutoff wavelength The external light reflecting unit has a property of almost totally reflecting light of a wavelength longer than the near-infrared light cutoff wavelength, and when the incident angle of incident light to the near-infrared light reflecting unit is changed in a range of 0° to 30°, the near-infrared light cutoff It provides a camera structure, characterized in that the wavelength is always included in the light absorption wavelength region.

As an effect of combining the near-infrared light absorbing portion and the near-infrared light reflecting portion, an acquired image is affected when the transmittance of light at a predetermined wavelength is 1% or more. Accordingly, as a spectral characteristic of the near-infrared light absorbing unit, when the light transmittance of the near-infrared light reflecting unit is 50% in the light wavelength region where the light transmittance is 2% or more, the image quality of the acquired image is different from the color sense seen by the naked eye. In addition, when the near-infrared light reflector is formed of, for example, a dielectric multilayer film, the light transmittance changes according to the incident angle of the incident light, so that the dependence of the light wavelength of the transmittance at the periphery and center of the acquired image changes, so-called ``redness disappears''. Deterioration phenomenon occurs. In particular, when the infrared reflector is disposed on the outside of the camera module, specifically on the cover glass, since light having a large incident angle can enter the camera module, this image quality deteriorates remarkably.

According to the invention described in (17) above, as the effect of combining the near-infrared light absorbing unit and the near-infrared light reflecting unit, the transmittance of light is less than 1% in the optical wavelength region longer than the near-infrared cutoff wavelength among the 685 nm to 755 nm optical wavelength region. It also shows an excellent effect that the difference between the image quality of and what is seen with the naked eye becomes smaller. In addition, when the incident angle of the incident light to the near-infrared light reflector is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength of the near-infrared light reflector always enters the light absorption wavelength region where the light transmittance is less than 2%. Since the dependence of the incident angle of the spectral characteristic on the light in the infrared region becomes small, and the light wavelength dependence of the transmittance at the periphery and center of the acquired image does not change, the image quality is improved.

(18) The present invention includes a near-infrared light absorbing unit that absorbs light in the near-infrared region, and a near-infrared light reflecting unit that reflects light in the near-infrared region, and the near-infrared light absorbing unit includes a wavelength of 685 nm to 755 nm. Has a light-absorption wavelength region in which the light transmittance is less than 2%, and the near-infrared light reflector has a wavelength longer than the near-infrared light cut-off wavelength when the wavelength at which the transmittance of light decreases and becomes 50% is defined as the near-infrared light cutoff wavelength. It has a property of almost total reflection, and when the incident angle of the incident light to the near-infrared light reflecting unit is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength is always included in the light absorption wavelength range. The camera structure according to any one of the above (1) to (16) is provided.

When the near-infrared light reflecting part is provided on the side close to the outside of the camera structure, for example, on a cover glass, even light having a large incident angle enters the camera structure. When the near-infrared light reflecting part, for example, is formed of a dielectric multilayer film, the light transmittance changes according to the incident angle of the incident light, so that the dependence of the light wavelength of the transmittance at the periphery and center of the acquired image changes, resulting in a deterioration of the so-called ``redness''. A phenomenon occurs.

According to the invention described in (18) above, when the incident angle of the incident light to the near-infrared light reflecting unit is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength of the near-infrared light reflecting unit is always light with a light transmittance of less than 2%. Since it enters the absorption wavelength region, the dependence of the incident angle of the spectral characteristics on the light in the near-infrared region becomes small, and since the optical wavelength that can be acquired in the peripheral and central portions of the acquired image is not changed, the image quality is improved.

In addition, as an effect of combining the near-infrared light absorbing unit and the near-infrared light reflecting unit, the transmittance of light is less than 1% in the light wavelength region longer than the near-infrared cutoff wavelength among the 685 nm to 755 nm light wavelength ranges, so the difference between the quality of the acquired image and the visual view It also exhibits an excellent effect of becoming smaller.

(19) The present invention provides a cover glass that protects the internal mechanism of an imaging device from the outside, an optical lens group disposed on the cover glass side, and an imaging for receiving light incident through the cover glass and the optical lens group. An element is provided, and the cover glass has a transparent substrate that transmits light, the near-infrared light absorbing part, and the near-infrared light reflecting part, and between the optical paths from the optical lens group to the imaging device, light in a near-infrared region A camera structure according to (17) above, characterized in that no near-infrared light cut filter for cutting is provided is provided.

Since the near-infrared light reflector is installed at the side closest to the outside world of the camera structure, that is, on the cover glass, even light with a large incident angle enters the camera structure. When the near-infrared light reflecting part, for example, is formed of a dielectric multilayer film, the light transmittance changes according to the incident angle of the incident light, so that the dependence of the light wavelength of the transmittance at the periphery and center of the acquired image changes, resulting in a deterioration of the so-called ``redness''. A phenomenon occurs.

According to the invention described in (19) above, when the incident angle of the incident light to the near-infrared light reflecting unit is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength of the near-infrared light reflecting unit is always light with a light transmittance of less than 2%. Since it enters the absorption wavelength region, the incident angle dependence of the spectral characteristics on the light in the near-infrared region becomes small, and the light wavelength dependence of the transmittance at the periphery and the center of the acquired image does not change, thereby exhibiting an excellent effect that the image quality is improved.

In addition, as an effect of combining the near-infrared light absorbing unit and the near-infrared light reflecting unit, the transmittance of light is less than 1% in the light wavelength region longer than the near-infrared cutoff wavelength among the 685 nm to 755 nm light wavelength ranges, so the difference between the quality of the acquired image and the visual view It also exhibits an excellent effect of becoming smaller.

Furthermore, since the near-infrared light cut filter for cutting the light in the near-infrared region is not disposed between the optical path from the optical lens group to the image pickup device, it is helpful to reduce the overall camera structure.

(20) The present invention is a camera structure including a near-infrared light cut filter that blocks light in the near-infrared region, wherein the near-infrared light cut filter has a wavelength of 10% by decreasing the transmittance of light when the wavelength of incident light is increased. Defined as the near-infrared light blocking wavelength, when the incident angle of the incident light is changed in the range of 0° to 30°, the angle-dependent change width of the near-infrared light blocking wavelength 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 at the near-infrared light reflecting portion changes according to the incident angle of incident light. That is, for example, the near-infrared light blocking wavelength of the near-infrared light reflecting part was about 700 nm when the incident angle of the incident light was 0°, and the incident angle dependence of about 675 nm occurs when the incident angle of the incident light reaches 30°. have. Then, assuming that the near-infrared light cut filter has a near-infrared light absorbing portion, the light transmittance realized in combination with the near-infrared light reflecting portion may vary greatly depending on the incident angle of the incident light. Specifically, in the near-infrared light cut filter having a near-infrared light reflecting part and a near-infrared light absorbing part, the angle-dependent change width of the near-infrared light blocking wavelength when the incident angle of incident light is changed within the range of 0° to 30° becomes about 30 nm. It may be discarded. Conversely, the light transmittance of the near-infrared light cut filter at a predetermined light wavelength in the near-infrared light region varies greatly depending on the incident angle of the incident light. For example, if light with a wavelength of 660 to 690 nm is incident, the light transmittance is about 20% when the incident angle is small at the center of the acquired image, and when the incident angle is large at the periphery of the acquired image, the light transmittance is almost 0%. As a result, the light wavelength dependence of the transmittance changes at the periphery and the center of the acquired image, resulting in a phenomenon of deterioration of the so-called "redness".

According to the invention described in (20) above, in the near-infrared light cut filter, when the incident angle of incident light is changed in the range of 0° to 30°, the angle-dependent change width of the near-infrared light cut-off wavelength is 5 nm or less. It has an excellent effect of improving the image quality because it becomes difficult to generate a difference in the color expression of.

(21) The present invention includes a near-infrared light absorbing unit that absorbs light in the near-infrared region and a near-infrared light reflecting unit that reflects light in the near-infrared region, and the light transmittance of the near-infrared light absorbing unit is 700 nm with respect to the wavelength of light. The frequency dependence curve of the light transmittance of the near-infrared light absorbing unit is less than 2% in the range of ~750nm, the range of 630nm~750nm with respect to the wavelength of light, and the transmittance of light is 2% or more, It provides a camera structure, characterized in that the shorter wavelength side than the frequency-dependent curve of the light transmittance of the near-infrared light reflector when the incident angle is 0° to 30°.

According to the invention described in (21) above, even if a phenomenon in which the wavelength dependence of the light transmittance at the near-infrared light reflecting part changes with the incident angle of the incident light occurs, the near-product when the near-infrared light reflecting part and the near-infrared light absorbing part are considered together Since the spectral characteristics of the light transmittance in the external light region are dominated by the spectral characteristics of the light transmittance of the near-infrared light absorbing portion, a difference in color expression in the acquired image is less likely to occur, and the image quality is improved.

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

According to the invention of (22) above, a remarkable effect can be achieved in that an imaging device incorporating a camera structure with improved image quality can be realized at low cost.

According to the present invention, since the degree of freedom is generated in the place where the near-infrared light reflector is disposed and the place where the near-infrared light absorber is disposed, it is possible to arrange it at an optimum position in the camera structure, and a remarkable effect of improving the image quality in the imaging device is achieved. Can be indicated.

1A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a first embodiment of the present invention. (B) is a structural diagram of a cover glass to which a near-infrared light reflecting function including a near-infrared light reflecting part is added. (C) is a structural diagram of an imaging device cover to which a near-infrared light absorbing function including a near-infrared light absorbing portion is added.
2A is a structural diagram of a cover glass to which an optical filter function is added. (B) is a diagram showing the dependence of the incident angle of the spectral transmittance on the near-infrared light reflecting film. (C) is an explanatory diagram for explaining the definition of the incident angle.
Fig. 3 is a diagram showing the incidence angle dependence of the spectral transmittance in a cover glass to which an optical filter function including a near-infrared light absorbing film and a near-infrared light reflecting film is added.
Fig. 4 is a diagram comparing spectral transmittances of a cover glass to which an optical filter function is added, a glass with a near-infrared light absorbing film, and a glass with a near-infrared light reflecting film.
5 is an explanatory diagram illustrating the spectral transmittance of a dual band cover glass.
6A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a third embodiment of the present invention. (B) is a structural diagram of a cover glass to which a near-infrared light reflecting function including a near-infrared light reflecting part is added. (C) is a structural diagram of a plate to which a near-infrared light absorption function is added. (D) is a structural diagram of an imaging element cover provided with a plurality of antireflection layers using transparent glass as a base material. (E) is a structural diagram of an imaging cover using as a base material a transparent synthetic resin film having a moth-eye structure that exhibits an antireflection function on both sides.
7A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a fourth embodiment of the present invention. (B) is a cross-sectional view of a lens unit including an optical lens element provided with a near-infrared light absorbing portion. (C) is a cross-sectional view of a lens unit including an optical lens element provided with a near-infrared light absorbing portion.
8A is a cross-sectional view of a camera structure applied to an imaging device according to a fifth embodiment of the present invention. (B) is 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.
9A is a cross-sectional view of a camera structure applied to an imaging device according to a sixth embodiment of the present invention. (B) is a cross-sectional view of a lens unit including an optical element to which a near-infrared light absorbing function including a near-infrared light absorbing portion is added. (C) is a structural diagram of an optical element to which a near-infrared light absorption function is added.
10A is a cross-sectional view of a camera structure applied to an imaging device according to a seventh embodiment of the present invention. (B) is a cross-sectional view of a lens unit including an optical element to which an optical filter function including a near-infrared light reflecting portion and a near-infrared light absorbing portion is added. (C) is a structural diagram of the optical element 530 to which an optical filter function has been added.
11A is a cross-sectional view of a conventional camera structure in a portable communication device. (B) is an explanatory diagram for explaining an experiment method of an experiment conducted with a conventional camera structure. (C) is a cross-sectional view of a conventional cover glass. (D) is a cross-sectional view of a conventional near-infrared light cut filter. (E) is an image captured by a conventional camera structure.
Fig. 12A is a graph showing the spectral characteristics of the light transmittance in the near-infrared light absorbing unit using a conventional light-absorbing ink and the incident light angle dependence of the spectral characteristics of the light transmittance in the near-infrared light reflecting unit. (B) is 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.
13A shows the incident light angle of the spectral characteristics of the light transmittance in the near-infrared light absorbing unit using a light-absorbing ink having a wider light absorption band in the near-infrared light region, and the spectral characteristics of the light transmittance in the near-infrared light reflecting unit. It is a graph showing the dependence. (B) is 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.
14A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a ninth embodiment of the present invention. (B) is a structural diagram of a cover glass to which an optical filter function provided with a plurality of antireflection films is added.

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

1 to 10 and FIGS. 12 to 14 are examples of embodiments in which the invention is implemented, and portions of the drawings to which the same reference numerals are assigned indicate the same.

1A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a first embodiment of the present invention.

This camera structure includes a cover glass 215 to which a near-infrared light reflection function is added to protect the internal mechanism of the imaging device from the outside, and a camera module 1. The camera module 1 includes an optical lens group, that is, a lens unit 50, which is an internal mechanism of an imaging device, a lens carrier 40 holding the lens unit 50, and a lens unit ( A magnet holder 30 for moving 50 in the axial direction, a cover glass 215 to which a near-infrared light reflection function is added, and an imaging element 70 for receiving light incident through the lens unit 50, and a lens unit An imaging device cover 244 to which a near-infrared light absorbing function is added is provided, which is disposed between 50 and the imaging device 70 and made of transparent glass that transmits light as a base material. The imaging element cover 244 to which the near-infrared light absorption function is added 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.

1B is a structural diagram of a cover glass 215 to which a near-infrared light reflecting function including a near-infrared light reflecting part is added. The cover glass 215 to which the near-infrared light reflection function has been added uses a crystallized glass 130 as a transparent substrate that transmits light, and an anti-reflection film 120 that reflects light in the ultraviolet region while suppressing reflection of light in the visible region It is formed on the incident side of light based on this crystallized glass 130. In addition, an antifouling coating film 110 for preventing contamination from outside is provided on the outermost side of the side where light is incident. On the light emission side, an anti-reflection film 120 and a near-infrared light reflecting film 150, which is a near-infrared reflecting part for reflecting light in the near-infrared region, are formed sequentially from the farthest side based on the crystallized glass 130.

Moreover, in the cover glass 215 to which the near-infrared light reflection function was added, the antireflection film 120 on the side of the imaging element 70 may not be necessary.

FIG. 1C is an image pickup with a near-infrared light absorbing function further comprising a plurality of anti-reflection layers 230 for preventing reflection of light in at least a visible region, and a near-infrared light absorbing film 140 as a near-infrared light absorbing unit It is a structural diagram of the element cover 244. That is, the imaging device cover 244 to which the near-infrared light absorbing function is added includes anti-reflection layers 230 for preventing reflection of light in at least a visible region on both sides of the imaging device cover 244. The antireflection layer 230 has a material and structure similar to those of the antireflection film 120 and the manufacturing method is the same.

The imaging element cover 244 to which the near-infrared light absorption function is added has 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 antireflection layer 230 is formed on the incident side of the light based on the transparent glass 220, and on the emission side of the light, from the farthest side based on the transparent glass 220, the antireflection layer 230 and the An external light absorbing film 140 is provided.

That is, the camera structure applied to the portable communication device A, which is the imaging device according to the first embodiment of the invention, includes an optical lens group (optical unit 50) and a lens unit 50 disposed on the incident side of light. An imaging element 70 that receives the light incident through it, a near-infrared light reflecting film 150 that is a near-infrared light reflecting unit that reflects light in the near-infrared region, and a near-infrared light absorbing film that is a near-infrared light absorbing unit that absorbs light in the near-infrared region A camera structure having 140, wherein the near-infrared light reflecting part and the near-infrared light absorbing part are formed as separate bodies. A near-infrared light reflecting film 150 as a near-infrared light reflecting part and a near-infrared light absorbing film 140 as a near-infrared light absorbing part are sequentially arranged as a near-infrared light reflecting film 150 and a near-infrared light absorbing film 140 from the incident side of light. The near-infrared light reflecting film 150, which is a near-infrared light reflecting portion, includes a lens element constituting the lens unit 50 in this camera structure, and is disposed on the incident side of the light rather than the lens element. The near-infrared light absorbing film 140, which is a near-infrared light absorbing portion, includes a lens element constituting the lens unit 50 in this camera structure, and is disposed on the image pickup element 70 side from the lens element. An imaging device cover 244 to which a near-infrared light absorbing function is added that covers at least a part of the imaging device 70 when viewed from the side to which the light enters is disposed between the lens unit 50 and the imaging device 70. The imaging element cover 244 to which a near-infrared light absorption function is added includes a near-infrared light absorbing portion of the imaging element. The near-infrared light absorbing part is a near-infrared light absorbing film 140 that absorbs light in the near-infrared region, and contains an organic dye. This camera structure further has a cover glass 215 to which a near-infrared light reflecting function is added to protect the internal mechanism of the imaging device from the outside, and the cover glass includes a near-infrared light reflecting film 150 as a near-infrared light reflecting portion.

In addition, as a means of realizing the imaging element cover 244 to which the near-infrared light absorbing function is added, for example, a thin plate of synthetic resin containing at least a part of an organic dye absorbing light in the near-infrared region may be used as a base material. do. Further, similarly to the conventional near-infrared light cut filter, a so-called blue glass plate that absorbs light in the near-infrared region may be used. It is also conceivable to realize a transparent plate by attaching a film that cuts near-infrared light.

In general, crystallized glass has a large crystal grain, so it is difficult to pass light. However, with recent advances in technology, it is possible to control the crystal grains to a nanometer size and to increase the transmittance of light, for example, similar to the impact resistance and high hardness clear glass ceramics manufactured by Ohara Corporation. If such crystallized glass is used, it is possible to manufacture a cover glass having both impact resistance and fracture toughness in which cracks are less likely to occur. Then, by forming the above-described laminated structure on the cover glass, the cover glass 215 to which the near-infrared light reflection function is added is realized. In addition, it is theoretically conceivable to use blue glass as the cover glass 215 to which the near-infrared light reflecting function is added, but it is not appropriate because the impact resistance is low and the fracture toughness is difficult to generate cracks. It is also conceivable to form a cover glass 215 to which a near-infrared light reflecting function is added by forming a near-infrared light reflecting film 150 to be described later on the tempered glass, but it has a disadvantage of low impact resistance compared to the case of using the crystallized glass 130. Have. In addition, it is also conceivable to form a near-infrared reflective film 150 on a sapphire glass having high hardness to form a cover glass 215 to which a near-infrared light reflecting function is added, but the cost is remarkably increased, and the use of the crystallized glass 130 Processability is lower than that of the case.

The antifouling coating film 110 prevents fingerprint contamination and sebum contamination and makes it easier to wipe off contamination. The antifouling coating film 110 is formed of a fluorine-based coating agent or the like, and is formed on the outermost side of the incident side of light in the laminated structure of the cover glass by coating or spraying.

The antireflection film 120 suppresses reflection of light in the visible region while reflecting light in the ultraviolet region. The antireflection film 120 is a dielectric multilayer film, and is formed by alternately stacking a nitride film and an oxide film. The dielectric film constituting the antireflection film 120 is formed by alternately stacking a plurality of nitride films and oxide films. As the nitride film, silicon nitride, silicon oxynitride, aluminum nitride, or the like can be used. In the case of using silicon oxynitride, it is preferable that the stoichiometric ratio (oxygen/nitrogen) of oxygen and nitrogen is 1 or less. As the oxide film, silicon oxide (SiO2), aluminum oxide (Al2O3), or the like can be used. By using silicon nitride or silicon oxynitride as the film of the antireflection film 120, the antireflection film 120 can be formed using the same film formation method and film formation apparatus as the near-infrared light reflection film 150 to be described later, which is advantageous in a process.

As the antireflection film 120, an oxide film may be used instead of a nitride film. In addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), and the like can be used as the material of the oxide film. Further, when the antireflection film 120 is formed of a plurality of types of oxide films having different refractive indices, it is appropriately selected from the above oxides.

As the antireflection film 120, a known film formation method, for example, 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), etc. can be used. have. It is preferable to use a sputtering method or an ion beam sputtering method for forming a nitride film.

The near-infrared light absorbing film 140 transmits light in the visible region and absorbs a part of light in the near-infrared region from the red region. The near-infrared light absorbing film 140 includes an organic dye and is composed of a resin film having a maximum absorption wavelength in the range of 650 nm to 750 nm (see dotted line in FIG. 4). Since the near-infrared light absorbing film 140 is adjacent to the crystallized glass 130, it is preferable to reduce the refractive index difference between the two to reduce the reflectance at the interface. By having the near-infrared light absorbing film 140, the dependence of the spectral transmittance characteristic according to the incident angle can be reduced, and thus excellent near-infrared light cutability can be obtained.

As the organic dye, an azo compound, a phthalocyanine compound, a cyanine compound, a dimonium compound, or the like can be used. Polyacrylic, polyester, polycarbonate, polystyrene, polyolefin, or the like can be used as the resin material as the binder (the binder of the pigment) constituting the near-infrared light absorbing film 140. The resin material may be a mixture of a plurality of resins, or may be a copolymer using a monomer of the resin. In addition, the resin material may have a high transmittance with respect to light in the visible region, and is selected in consideration of the correspondence with the organic dye, film formation process, cost, and the like. In addition, in order to improve the UV resistance of the near-infrared light absorbing film 140, a sulfur compound or the like 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, a resin binder is dissolved with a known solvent such as methyl ethyl ketone and toluene, and the above-described organic dye is further added to prepare a coating liquid. Next, this coating liquid is applied to the crystallized glass 130 to a desired film thickness by, for example, a spin coating method, and dried and cured in a drying furnace.

The near-infrared light reflective film 150 is a dielectric multilayer film formed by alternately stacking a plurality of dielectrics having different refractive indices, such as the antireflection film 120. However, the dielectric multilayer film constituting the near-infrared light reflecting film 150 is formed by stacking a plurality of oxide films having different refractive indices, and the adjacent oxide films are oxide films of different types. In the first embodiment, the near-infrared light reflecting film 150 is formed by alternately stacking several dozen layers of two types of oxide films. As the oxide film, in addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), and the like are used.

In the near-infrared light reflecting film 150, each oxide film has a thickness of λ/4 with the wavelength of light to be reflected as λ. By doing this, the light reflected from all the interfaces of the alternating layer becomes the same phase when it reaches the incidence surface, resulting in the light being intensified with each other. That is, the reflectance increases near the wavelength λ, and functions as a light reflective film. In this embodiment, the film may be designed to reflect light in the near-infrared region as λ. Further, the near-infrared light reflecting film 150 is also formed by using the same film forming method and film forming apparatus as the antireflection 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, the imaging device generally includes visible light, and has a sensitivity to light having a longer wavelength, that is, light having a wavelength of about 1.1 μm. Therefore, if the image captured by the imaging device is taken as a photograph, it does not appear as a natural color tone and causes a sense of incongruity.

When the cover glass 100 to which an integrated optical filter function having a near-infrared light reflecting part and a near-infrared light absorbing part is added is formed as a laminated structure as shown in Fig. 2A, for example, a near-infrared light reflecting film ( Since 150) is provided, it becomes possible to cut light having a wavelength of 700 nm or more that cannot be absorbed by the near-infrared light absorbing film 140 to obtain an image with a natural color tone. In addition, if the near-infrared light reflecting film 150 is used to cut the light in the near-infrared region, the reflectance greatly changes according 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 having no dependence on the incident angle on the light absorption rate, it becomes possible to construct a near-infrared light cut filter in which the light transmittance is less dependent on the incident angle of light.

In addition, since the cover glass 100 that protects the camera in the smartphone housing 20 from the outside world can cut light in the ultraviolet region by the antireflection film 120, an optical lens group formed of synthetic resin, which is a component of the camera ( It is possible to prevent the lens unit 50 from being deteriorated by ultraviolet rays, and also to prevent the near-infrared light absorbing film 140 including an organic dye from being deteriorated by ultraviolet rays. Further, by the anti-reflection function for light in the visible region, more incident light can be introduced and a bright image can be obtained.

In addition, the antireflection film 120 is formed by alternately stacking a nitride film and an oxide film. In general, the nitride film has a higher hardness than the oxide film, and reaches a hardness of 9H or more in a pencil hardness test. Therefore, by configuring the antireflection film 120 also including a nitride film, the effect of increasing the scratch resistance is exhibited. Further, the nitride film has a higher packing density and is denser than the oxide film. Since it does not contain oxygen as a component, it is not also a source of oxygen. Therefore, by providing the nitride film outside the near-infrared light absorbing film 140, the intrusion of oxygen and moisture into the near-infrared light absorbing film 140 is prevented, thereby suppressing deterioration of the near-infrared light absorbing film 140.

In general, optical filters have a large number of optical interface surfaces. On the other hand, a highly antireflective film is applied to the lens. It is difficult to achieve the same level of transmittance as the lens with an optical filter that cuts the light in the near-infrared region, and there is a case where the reflected light is returned to the lens side. This is the cause of stray light that creates ghosts in burns. In the conventional camera structure, since the optical filter 60 is placed near the imaging device 70 on the optical path between the lens unit 50 and the imaging device 70, it has been difficult to avoid causing the ghost as described above. However, according to the camera structure according to the present embodiment, since stray light as described above does not occur, a remarkable effect of improving image quality is exhibited.

Next, for reference, the spectral transmittance characteristics of the cover glass 100 to which an integrated optical filter function having a near-infrared light reflecting portion and a near-infrared light absorbing portion is added will be described. The functions of the cover glass 100 to which an optical filter function is added, for example, to a cover glass 215 to which a near-infrared light reflection function is added, which is a separate body, and an imaging device cover 244 to which a near-infrared light absorption function is added. In the case of dividing, the same effect can be obtained.

Fig. 2B shows the experimental results of how the spectral transmittance characteristics of the near-infrared light reflecting film composed of the dielectric film depend on the incident angle of light. Incident angle A is defined as shown in FIG. 2C. In addition, "T" on the vertical axis represents the spectral transmittance, and the unit is% (percent). In addition, "λ" on the horizontal axis represents the wavelength of light, and the unit is nm (nanometers) (the same also applies in the following drawings). The sample was obtained by alternately stacking 40 layers of titanium dioxide (TiO2) and silicon dioxide (SiO2) on glass with a predetermined film thickness. The solid line represents the spectral transmittance when the incident angle of light is 0 degrees, and the dotted line represents the spectral transmittance when the incident angle of light is 30 degrees. From Fig. 2B, it was confirmed that a significant difference in spectral transmittance occurs at an incident angle of 0 and 30 degrees for light in the red region, which is a wavelength around 700 nm. If there is such a difference, the color tone of the image leads to a large change in the center and the peripheral portion of the image, resulting in a deterioration in image quality.

3 shows the experimental results of how the spectral transmittance of the cover glass 100 to which the optical filter function having both a near-infrared light absorbing film and a near-infrared light reflecting film is added depends on the incident angle of light. As the near-infrared light absorbing film, a resin film having a thickness of 5 μm or less containing an organic dye is used, and the near-infrared light reflecting film has the same configuration as in the case of Fig. 2. The solid line represents the spectral transmittance when the incident angle of light is 0 degrees, the dotted line represents the incident angle of light at 15 degrees, and the dashed line represents the spectral transmittance when the incident angle of light is 30 degrees. It can be seen that the incidence angle dependence is decreasing compared to the case of FIG. 2.

4 is a cover glass 100 (solid line) to which an optical filter function is added having a near-infrared light absorbing film 140 and a near-infrared light reflecting film 150, and a cover glass having only the near-infrared light absorbing film 140 ( It is a diagram comparing the experimental results in measuring the spectral transmittance of a cover glass (dashed-dotted line) in which only the near-infrared light reflecting film 150 is formed. The configurations of the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 are the same as those of FIGS. 2 and 3, and thus a description thereof will be omitted. However, the incident angle of all light is 0 degrees. In the case of only the near-infrared light absorbing film 140, light of 650 to 750 nm is strongly absorbed, but light of 800 nm or more is mostly transmitted. As described above, since the human eye mainly has sensitivity to so-called visible light with a wavelength of 380 nm to 780 nm, if the image pickup device 70 is imaged to an area of 800 nm or more with sensitivity, it is unnatural to the human eye as described above. It becomes a burn. The near-infrared light reflecting film 150 is designed to cut light with a wavelength of 700 nm or more, and in fact, a sharp decrease in spectral transmittance around 700 nm is measured. The cover glass 100 to which an optical filter function is added is formed by combining the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150, and as shown by the solid line in FIG. 4, 400 to 650 nm of light in the visible region It can be seen that high transmittance is realized and light having a wavelength of 700 nm or more is cut.

According to the camera structure according to the embodiment of the present invention, since the degree of freedom is generated in the place where the near-infrared light reflector is disposed and the place where the near-infrared light absorber is disposed, it is possible to arrange it at an optimum position in the camera structure. It shows a remarkable effect.

In some cases, light at a longer wavelength side than light at a wavelength absorbed by the near-infrared light absorbing unit may transmit. Therefore, if the light from the incident side is sequentially arranged as a near-infrared light absorbing unit and a near-infrared light reflecting unit, light on the long wavelength side is more likely to enter the camera module than light of the wavelength absorbed by the near-infrared light absorption unit, and light on the long wavelength side is cut. Before reaching the possible near-infrared light reflecting unit, it reflects on the lens surface and becomes stray light, which causes deterioration in image quality.

According to the camera structure according to the embodiment of the present invention, since the near-infrared light reflecting unit and the near-infrared light absorbing unit are sequentially arranged as a near-infrared light reflecting unit and a near-infrared light absorbing unit from the incident side of light, the effect of suppressing stray light on the long wavelength side is achieved. Show.

According to the camera structure according to the embodiment of the present invention, since the near-infrared light reflecting portion includes a lens element constituting the optical lens group, and is disposed on the incident side of the light than the lens element, the near-infrared light is more than the position of the conventional near-infrared light cut filter. The distance from the reflecting part to the imaging device increases. In the near-infrared light reflecting portion, when the incident angle of light deviates from perpendicular to the axial direction, the light in the ultraviolet region may easily pass through. As the distance from the imaging device increases, the angle at which the imaging device is viewed from the near-infrared light reflecting unit decreases, and thus, the light in the extra ultraviolet region that passes through the near-infrared light reflecting unit and directly reaches the imaging device can be reduced.

According to the camera structure according to the embodiment of the present invention, the transmittance of the near-infrared light absorbing portion does not depend on the incident angle of light in many cases. Therefore, it is remarkable that the near-infrared light absorbing unit includes a lens element constituting the optical lens group in the camera structure, and is disposed on the side of the imaging element rather than this lens element, thereby effectively suppressing stray light that is intended to enter the imaging element from various directions. Shows the effect.

When dust, which is difficult to transmit light, adheres on the imaging device, image quality deteriorates. According to the camera structure according to the embodiment of the present invention, the imaging device cover covering at least a part of the imaging device as viewed from the side to which light is incident is disposed between the optical lens group and the imaging device at a position close to the imaging device. It has a remarkable effect that it can prevent deterioration of image quality by reducing dust that may adhere to the device.

According to the camera structure according to the embodiment of the present invention, it is possible to produce an image pickup device cover with little deformation due to temperature change at low cost.

The imaging element cover is disposed at a position close to the imaging element between the optical lens group and the imaging element. Therefore, when the image pickup device cover reflects light, it becomes a cause of remarkably deteriorating the image quality of an image acquired by the image pickup device. According to the camera structure according to the embodiment of the present invention, the image pickup device cover has a remarkable effect in that the image quality is improved by including an antireflection layer that prevents reflection of light in at least a visible region.

According to the camera structure according to the embodiment of the present invention, it is possible to introduce more incident light, and the reflected light caused by the imaging element cover, particularly the reflected light from the imaging element itself, is reflected back to the imaging element cover and returned to the imaging element. It has a remarkable effect of improving image quality by preventing it from coming.

According to the camera structure according to the embodiment of the present invention, since the imaging element cover includes a near-infrared light absorbing portion, the remarkable effect of reducing the number of parts and reducing the number of steps in manufacturing the camera structure is exhibited.

According to the camera structure according to the embodiment of the present invention, since the near-infrared light absorbing portion has a near-infrared light absorbing film, and the near-infrared light absorbing film contains an organic pigment that absorbs near-infrared light, the material for a filter for absorbing light in the near-infrared region The effect of suppressing the light in the near-infrared light region is achieved in a state where the light incident angle dependence is small without the use of blue glass, which is generally used.

According to the camera structure according to the embodiment of the present invention, since the cover glass has a near-infrared light reflecting film that reflects light, the effect of not allowing near-infrared light from outside to enter the internal mechanism of the imaging device can be exhibited. In addition, since there is no need to put a member having a near-infrared light reflecting film in an area close to the image pickup device, reflection of light incident on the internal mechanism of the image pickup device can be suppressed, and as a result, stray light is suppressed to reduce the cause of ghost or flare. It can have a reducing effect.

5 is a diagram showing the spectral transmittance of a cover glass to which an optical filter function has been added, which the camera structure according to the second embodiment of the present invention has. In this embodiment, there is provided a cover glass and a camera structure to which a so-called dual-band optical filter function capable of acquiring an image even at night is added. The basic configuration of the camera structure is the same as in the first embodiment, but instead of the cover glass 215 to which the near-infrared light reflecting function is added, an optical filter function including the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 is provided. The added cover glass 100 is disposed, and the imaging element cover 244 to which the near-infrared light absorption function is added is omitted (not shown).

In addition, the cover glass 215 to which the near-infrared light reflecting function has been added includes a near-infrared light reflecting film D having a high light transmittance for a part of light in the near-infrared region. Since the film structure of the near-infrared light reflecting film D is a known technique, a description thereof will be omitted.

When the near-infrared light absorbing film 140 shown by the dotted line in FIG. 5 and the near-infrared light reflecting film D having a high light transmittance for a part of the light in the near-infrared region shown by the dashed-dotted line in FIG. 5 are combined, the solid line in FIG. Likewise, it is possible to realize a dual band cover glass that transmits light in the visible region and a part of light in the near infrared region. 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. The camera structure provided with such a dual band cover glass is suitable for an on-vehicle camera because it can obtain a remarkable effect that the lane boundary line and the outside line of the lane can be easily seen on a road at night.

6A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a third embodiment of the present invention. This camera structure includes a cover glass 215 to which a near-infrared light reflecting function is added to reflect near-infrared light, a plate 217 to which a near-infrared light absorbing function is added to absorb near-infrared light, and an image using transparent glass as a base material. A device cover 240 is provided. Since other configurations are the same as those of the first embodiment described above, description is omitted.

6B is a structural diagram of a cover glass to which a near-infrared light reflecting function including a near-infrared light reflecting part is added. The cover glass 215 to which the near-infrared light reflection function has been added uses a crystallized glass 130 as a transparent substrate that transmits light, and an anti-reflection film 120 that reflects light in the ultraviolet region while suppressing reflection of light in the visible region It is formed on the incident side of light based on this crystallized glass 130. Further, an antifouling coating film 110 for preventing contamination from outside is provided on the outermost side of the side where light is incident. On the light emitting side, an antireflection film 120 that prevents reflection of light in at least the visible region in sequence from the farthest to the crystallized glass 130, and a near-infrared light reflective film 150 that reflects light in the near-infrared region To form.

Moreover, in the cover glass 215 to which the near-infrared light reflection function was added, the antireflection film 120 on the side of the imaging element 70 may not be necessary.

6C is a structural diagram of the plate 217 to which the near-infrared light absorption function is added. The plate 217 to which the near-infrared light absorption function is added includes a plurality of anti-reflection layers 230 for preventing reflection of light in at least a visible region, and further includes a near-infrared light absorption film 140. The plate 217 to which the near-infrared light absorption function is added has a transparent glass 220 as a base material, and a near-infrared light absorbing film 140 is provided adjacent to the transparent glass 220. The antireflection layer 230 is formed on the incident side of the light based on the transparent glass 220, and on the light exit side, the antireflection layer 230 and the near-infrared light are sequentially formed from the farthest side based on the transparent glass 220 An absorbing film 140 is provided.

The plate 217 to which the near-infrared light absorption function is added is disposed on the inner structure side, that is, on the lens unit 50 side, than the cover glass 215 to which the near-infrared light reflection function is added.

Further, as a means for realizing the plate 217 to which the near-infrared light absorption function is added, for example, a thin plate of synthetic resin containing at least part of an organic dye absorbing light in the near-infrared region may be used as a base material. Further, similarly to the conventional near-infrared light cut filter, a so-called blue glass plate that absorbs light in the near-infrared region may be used. It is also conceivable to realize a transparent plate by attaching a film that cuts near-infrared light.

FIG. 6D is a structural diagram of an imaging element cover 240 using transparent glass as a base material, provided with a plurality of antireflection layers 230 using a transparent glass 220 as a base material. The imaging device cover 240 includes antireflection layers 230 on both surfaces of the transparent glass 220.

Fig. 6(E) is a camera structure applied to a portable communication device (A) which is an imaging device according to a third embodiment, in which an imaging element cover 240 made of transparent glass as a base material is provided with a transparent synthetic resin film ( This is a part of a modified embodiment in which 222 is replaced with an imaging device cover 242 made as a base material. In other words, it is a structural diagram of the imaging device cover 242 using the transparent synthetic resin film 222 as a base material and a transparent synthetic resin film having a moth-eye structure that exhibits anti-reflection function on both sides as a base material. The thickness of the imaging device cover 242 using the transparent synthetic resin film as a base material is 0.2 mm or less. The imaging device cover 242 made of a transparent synthetic resin film as a base material has a Morse-eye structure 232 for preventing reflection of light in at least a visible region on both surfaces.

The Mohs-eye structure does not reduce reflection by using an interference effect like a dielectric multilayer film, but reduces reflection by excluding a boundary surface where the refractive index changes rapidly. Specifically, a fine protrusion structure composed of a plurality of fine protrusions having a height of about several hundred nm is formed on the surface, and the repetition period of the protrusion is related to the wavelength range in which the reflection reduction effect appears. The description of the moss-eye structure is a well-known technique, so the description is omitted, but in the case of this modified embodiment, for example, a transparent synthetic resin film 222 is used as a transparent acrylic resin to form a moss-eye structure by transfer or molding processing to prevent reflection. To realize.

That is, the fine protrusion structure made of fine protrusions formed on the surface of the imaging device cover 242 using a transparent synthetic resin film as a base material, the so-called Mohs-eye structure 232, prevents reflection of light over a wide area. It is preferable that the MOS-eye structure 232 has a function of preventing reflection of light in at least the visible region, and also having a function of preventing reflection of light in the ultraviolet region and light in the near infrared region.

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

According to the camera structure according to the embodiment of the present invention, a remarkable effect is exhibited in that a camera module having a thickness smaller than that of the prior art can be provided.

An antireflection layer having a fine protrusion structure made of fine protrusions formed on the surface of the imaging device cover, a so-called Mohs eye structure, prevents reflection of light over a wide area. Accordingly, according to the camera structure according to the embodiment of the present invention, by forming the anti-reflection layer of the Morse-eye structure, the reflected light caused by the image pickup device cover is remarkably reduced over a wide area, and the image quality can be improved.

Further, as another modified example for the inner transparent plate 240, a multilayer film obtained by applying a synthetic resin as an antireflection layer may be formed on the surface of the transparent synthetic resin film 222 as a base material. In general, a multilayer film obtained by alternately laminating two types of thin films having different refractive indices of light can form an antireflection film of light. In addition, it is known that such a multilayer film can be obtained by applying a synthetic resin.

For example, two types of synthetic resins having different refractive indices of light are prepared, both of which are larger than the refractive index of air and smaller than the refractive index of the transparent synthetic resin film 222. By alternately applying these to the transparent synthetic resin film 222, it is possible to manufacture the inner transparent plate 240 provided with an anti-reflection film of stable quality at low cost. As a method of applying the synthetic resin to the transparent synthetic resin film 222, for example, a roller coating method or the like can be considered. According to the present modified embodiment, there is a remarkable effect that the inner transparent plate provided with the antireflection film can be manufactured in a large quantity and at low cost under stable quality.

7A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a fourth embodiment of the present invention. This camera structure includes a cover glass 215 to which a near-infrared light reflection function is added and a camera module 1. The camera module 1 includes a lens unit 50, a lens carrier 40 holding the lens unit 50, an imaging element 70, and an imaging element cover 240. The structures of the cover glass 215 to which the near-infrared light reflection function has been added and the imaging device cover 240 are the same as those described in the third embodiment, and thus are omitted. In addition, since the manufacturing method of the near-infrared reflective film 150 and the anti-reflective film 120 is the same as that of the first embodiment, descriptions are omitted.

7B 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, an optical lens group, is composed of a plurality of lens elements. Among the optical lens groups, a lens element disposed at the most side of the imaging element 70 is a lens element 250 having a near-infrared light absorbing portion. The near-infrared light absorbing portion is an organic dye, and is uniformly contained in the synthetic resin forming the lens element 250 having the near-infrared light absorbing portion.

7C 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 provided with 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 on the most imaging element 70 side. Since the manufacturing method of the near-infrared light absorbing film 140 is the same as that described in the first embodiment, it is omitted.

Further, an antireflection layer 230 may be provided on the near-infrared light absorbing film 140 on the imaging element 70 side.

According to the embodiment of the present invention, since it has a near-infrared light reflecting portion that reflects light, the effect of preventing near-infrared light from outside enter the internal mechanism of the imaging device can be exhibited. In addition, since there is no need to put a member having a near-infrared light reflecting part in an area close to the image pickup device, reflection of light incident on the internal mechanism of the image pickup device can be suppressed, and as a result, stray light is suppressed to reduce the cause of ghost or flare. It can have a reducing effect.

According to an embodiment of the present invention, since the near-infrared light absorbing portion includes an organic dye that absorbs near-infrared light, the incidence angle dependence of light without using blue glass, which is generally used as a filter material for absorbing light in the near-infrared region In this small state, it is possible to suppress light in the near-infrared region.

8A is a cross-sectional view of a camera structure applied to an imaging device according to a fifth embodiment of the present invention. The camera module 1 of this camera structure has a lens unit 50, a lens carrier 40 holding the lens unit 50, and an image pickup device 70, and is fixed to the vehicle body 22. That is, this camera structure is a structure of a so-called in-vehicle camera.

8B 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 having a near-infrared light reflecting portion. In the lens element 250 having the near-infrared light absorbing portion, the near-infrared light absorbing portion is an organic dye, and is uniformly contained in the synthetic resin forming the lens element 250 having the near-infrared light absorbing portion. As a modified embodiment, the lens element 250 having a near-infrared light absorbing part may be a transparent lens element 255 in which the near-infrared light absorbing film 140 is provided at the most side of the imaging element 70 (Fig. 7(C)). ) Reference). In this embodiment, since no mechanically moving member such as an actuator is included, dust is less likely to be generated. Further, since the surface of the imaging device 70 is substantially perpendicular to the ground, dust is less likely to adhere to the imaging device 70. Therefore, the imaging element cover 240 is omitted. A cover glass for preventing contamination may be provided on the light incident side of the lens unit 50. Of course, the imaging element cover 240 may be provided close to the imaging element 70.

With such a structure, it is possible to manufacture at low cost because the number of parts is reduced and the production process can be remarkably omitted. Of course, since it has a near-infrared light reflecting part and a near-infrared light absorbing part, it also has an effect of improving image quality.

In addition, as a modified example, the lens element 270 including the near-infrared light reflecting part in the camera structure is left as it is, and the near-infrared light absorbing function shown in Fig. 1C of the first embodiment is added to the imaging element cover. It is also conceivable that the lens element does not have a light absorbing function in the near-infrared region by using the image pickup element cover 244 thus obtained.

9A is a cross-sectional view of a camera structure applied to an imaging device according to a sixth embodiment of the present invention. This camera structure includes a cover glass 215 to which a near-infrared light reflection function is added and a camera module 1. The camera module 1 includes a lens unit 50, a lens carrier 40 holding the lens unit 50, an imaging element 70, and an imaging element cover 240. The structures of the cover glass 215 to which the near-infrared light reflection function has been added and the imaging device cover 240 are the same as those described in the third embodiment, and thus are omitted.

9B is a cross-sectional view of a lens unit including an optical element 500 to which a near-infrared light absorbing function including a near-infrared light absorbing portion is added. The lens unit 50 is provided with an optical element 500 to which a near-infrared light absorption function is added, on the most incident side of light. However, the optical element 500 to which the near-infrared light absorption function is added may be positioned at any position on the axis as long as it is inside the lens unit 50.

9C is a structural diagram of an optical element 500 to which a near-infrared light absorption function is added. The optical element 500 to which the near-infrared light absorbing function is added includes a plurality of anti-reflection layers 230 for preventing reflection of light in at least a visible region, and further includes a near-infrared light absorbing film 140. The plate 217 to which the near-infrared light absorption function is added has a transparent glass 220 as a base material, and a near-infrared light absorbing film 140 is provided adjacent to the transparent glass 220. The antireflection layer 230 is formed on the incident side of the light based on the transparent glass 220, and on the light exit side, the antireflection layer 230 and the near-infrared light are sequentially formed from the farthest side based on the transparent glass 220 An absorbing film 140 is provided.

In addition, as a means for realizing the optical element 500 to which the near-infrared light absorption function is added, for example, a thin plate of synthetic resin containing at least part of an organic dye absorbing light in the near-infrared region may be used as a base material. . Further, similarly to the conventional near-infrared light cut filter, a so-called blue glass plate that absorbs light in the near-infrared region may be used. It is also conceivable to realize a transparent plate by attaching a film that cuts near-infrared light.

In addition, since the manufacturing method of the near-infrared light reflective film 150, the anti-reflective film 120, and the near-infrared light absorbing film 140 is the same as that of the first embodiment, descriptions are omitted.

10A is a cross-sectional view of a camera structure applied to an imaging device according to a seventh embodiment of the present invention. This camera structure includes a cover glass 550 and a camera module 1. The camera module 1 includes a lens unit 50, a lens carrier 40 holding the lens unit 50, an imaging element 70, and an imaging element cover 240. The structure of the imaging element cover 240 is the same as described in the third embodiment, and thus is omitted.

The cover glass 550 may use conventional tempered glass, sapphire glass, or the like as a base material. Moreover, of course, you may use crystallized glass. The cover glass 550 has an antireflection film 120 that suppresses reflection of light in the visible region while reflecting the light in the ultraviolet region on the surface on the side of the imaging element 70 (not shown).

10B is a cross-sectional view of a lens unit including an optical element 530 to which an optical filter function including a near-infrared light reflecting portion and a near-infrared light absorbing portion is added. The lens unit 50 is provided with an optical element 530 to which an optical filter function has been added on the most incident side of light. However, the optical element 530 to which the optical filter function has been added may be located at any position on the axis as long as it is inside the lens unit 50.

10C is a structural diagram of an optical element 530 to which an optical filter function has been added. The optical element 530 to which the optical filter function is added includes a plurality of antireflection layers 230 for preventing reflection of light in at least a visible region, and further includes a near-infrared light absorbing film 140. The optical element 530 to which the optical filter function has been added has a transparent glass 220 as a base material, and a near-infrared light absorbing film 140 is provided adjacent to the transparent glass 220. The antireflection layer 230 is formed on the incident side of the light based on the transparent glass 220, and on the light exit side, the antireflection layer 230 and the near-infrared light are sequentially formed from the farthest side based on the transparent glass 220 A reflective film 150 and a near-infrared light absorbing film 140 are provided.

In addition, as a means for realizing the optical element 530 to which the optical filter function is added, for example, a thin plate of synthetic resin containing at least a part of an organic dye absorbing light in the near infrared region may be used as a base material. Further, similarly to the conventional near-infrared light cut filter, a so-called blue glass plate that absorbs light in the near-infrared region may be used. It is also conceivable to realize a transparent plate by attaching a film that cuts near-infrared light.

In addition, since the manufacturing methods of the near-infrared light absorbing film 140, the near-infrared light reflecting film 150, and the anti-reflection film 120 are the same as those of the first embodiment, descriptions are omitted.

According to this camera structure, it is only necessary to add the optical element 530 to which the optical filter function is added to the lens unit 50, and other configurations may utilize a conventional member. Further, since an integrated optical element including a near-infrared light reflecting portion and a near-infrared light absorbing portion at the same time is included in the optical lens group, there is no need to put a member having a near-infrared light reflecting film near the imaging element. Accordingly, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and consequently, stray light can be suppressed to reduce the cause of ghosts and flares.

By the way, as a result of the inventor's more closely researching, it has been found that another problem has arisen in the conventional camera structure, in which a difference in color sense occurs between the central portion and the peripheral portion of the acquired image. This problem occurs remarkably in the case where the incident angle of incident light can be increased, particularly in the sun where the near-infrared light reflecting portion is provided on the cover glass.

Fig. 12A is a graph showing the spectral characteristics of the light transmittance in the near-infrared light absorbing unit using a conventional light-absorbing ink and the incident light angle dependence of the spectral characteristics of the light transmittance in the near-infrared light reflecting unit. The vertical axis represents the transmittance (T) of light (unit is %), and the horizontal axis represents the wavelength of incident light (unit is nm). Specifically, an imaging device cover 244 to which a near-infrared light absorbing function is added having a near-infrared light absorbing film 140 as a near-infrared light absorbing part (see Fig. 1C), and a near-infrared light reflecting film as a near-infrared light reflecting part. Consider an optical system provided with a cover glass 215 to which a near-infrared light reflection function having 150 (see Fig. 1B) is added.

In Fig. 12A, a solid line A1 represents the spectral characteristics of the light transmittance for a single image pickup device cover 244 to which a near-infrared light absorption function is added. The dotted line R1 represents the spectral characteristics of the light transmittance in the cover glass 215 to which the near-infrared light reflection function is added when the incident angle of the incident light is 0°, and the dotted line R2 indicates the incident angle of the incident light. It shows the spectral characteristics of the light transmittance in the cover glass 215 to which the near-infrared light reflection function was added at 30°. 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 conventional near-infrared reflector at an incidence angle of 30° overlap each other at 660 to 700 nm as the wavelength region of light. In addition, the solid line A1 indicating the spectral characteristics of the conventional near-infrared light absorbing ink and the dotted line R1 indicating the spectral characteristics of the conventional near-infrared reflecting portion at an incidence angle of 0° do not overlap up to the intersection point around 720 nm.

Fig. 12B is 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. Specifically, the dotted line C1 is the spectral characteristic when the incident angle is 0°, and the dotted line C2 is the spectral characteristic when the incident angle is 30°. In other words, the spectral characteristics of the optical system combining the solid line A1 and the dotted line R1 in FIG. 12A are dotted lines C1, and the solid lines A1 and R2 in FIG. 12A. The spectral characteristics of the optical system combined with) are dotted lines (C2). A gap G1 is formed between the dotted line C1 and the dotted line C2 in the range of 660 nm to 690 nm.

Here, when the wavelength of incident light is increased, a wavelength of 10% by decreasing the transmittance of light is defined as a near-infrared light blocking wavelength. Considering a near-infrared light cut filter having a near-infrared light reflecting part and a near-infrared light absorbing part, when the angle of incidence of incident light is changed within the range of 0° to 30°, the angle-dependent change width of the near-infrared light blocking wavelength becomes about 30 nm. There may be. Conversely, in a predetermined light wavelength in the near-infrared light region, the light transmittance of the near-infrared light cut filter varies greatly depending on the incident angle of the incident light. Specifically, for example, if light with a wavelength of 660 to 690 nm is incident, the light transmittance is about 20% when the incident angle is small at the center of the acquired image, and when the incident angle is large at the periphery of the acquired image, the light transmittance A phenomenon that this becomes almost 0% occurs, and as a result, the light wavelength dependence of the transmittance at the periphery and the center of the acquired image is different, resulting in a phenomenon of deterioration of the so-called "redness".

As a camera structure according to an eighth embodiment of the present invention, Fig. 13A shows a camera structure including a combination of a near-infrared light absorbing portion and a new near-infrared light reflecting portion using a novel light-absorbing ink exhibiting spectral characteristics. The configuration of the near-infrared light absorbing part is the same as that of the imaging device cover 244 to which the near-infrared light absorbing function is added shown in FIG. 1C, and the configuration of the near-infrared light reflecting part is shown in FIG. 1B. It is the same as the cover glass 215 to which the function is added. Specifically, an imaging device cover 244 to which a near-infrared light absorbing function is added having a near-infrared light absorbing film 140 as a near-infrared light absorbing part (see Fig. 1C), and a near-infrared light reflecting film as a near-infrared light reflecting part. It is an optical system provided with the cover glass 215 to which the near-infrared light reflection function which has 150 (refer FIG. 1(B)) is added.

13A is a graph showing the spectral characteristics of the light transmittance in the near-infrared light absorbing portion using a new light-absorbing ink, and the incident light angle dependence of the spectral characteristics of the light transmittance in the new near-infrared light reflecting portion. The vertical axis represents the transmittance (T) of light (unit is %), and the horizontal axis represents the wavelength of incident light (unit is nm). Specifically, an imaging device cover 244 to which a near-infrared light absorbing function is added having a near-infrared light absorbing film 140 as a near-infrared light absorbing part (see Fig. 1C), and a near-infrared light reflecting film as a near-infrared light reflecting part. Consider an optical system provided with a cover glass 215 to which a near-infrared light reflection function having 150 (see Fig. 1B) is added.

In Fig. 13A, the solid line A2 represents the spectral characteristics of the light transmittance for the imaging element cover 244 to which the near-infrared light absorption function is added. The dotted line R3 represents the spectral characteristics of the light transmittance of the cover glass 215 to which the near-infrared light reflection function is added when the incident angle of the incident light is 0°, and the dotted line R4 indicates the incident angle of the incident light. It shows the spectral characteristics of the light transmittance in the cover glass 215 to which the near-infrared light reflection function was added at 30°.

Specifically, the camera structure according to the eighth embodiment of the present invention includes a near-infrared light absorbing unit 140 for absorbing light in the near-infrared region and a near-infrared light reflecting unit 150 for reflecting light in the near-infrared region. The near-infrared light absorbing unit 140 has a light absorption wavelength region 700 having a light transmittance of less than 2% in a range of 685 nm to 755 nm as a wavelength of light, and the wavelength of incident light to the near-infrared light reflecting unit 150 is increased. As the transmittance of light decreases and the wavelength of 50% is defined as the near-infrared light cutoff wavelength, the near-infrared light reflecting unit 150 has a property of almost totally reflecting light of a wavelength longer than the near-infrared light cutoff wavelength. When the incident angle of the incident light to the reflector 150 is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength is always included in the light absorption wavelength region 700.

In other words, the near-infrared light cut-off wavelength CF1 of the near-infrared light reflecting unit 150 at the incident angle of 0° and the near-infrared light cut-off wavelength of the near-infrared light reflecting unit 150 at 30° (CF2) is included in the light absorption wavelength region 700.

In addition, as a spectral characteristic for light having a wavelength longer than the near-infrared light cutoff wavelength in the near-infrared light reflecting unit 150, a light transmittance of less than 1% is preferable in the range of about 750 nm to 1000 nm. , For example, there may be several% of light transmittance.

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

Here, when the wavelength of incident light is increased, a wavelength of 10% by decreasing the transmittance of light is defined as a near-infrared light blocking wavelength.

Considering a near-infrared light cut filter having a near-infrared light reflecting unit 150 and a near-infrared light absorbing unit 140, the angle-dependent change width of the near-infrared light blocking wavelength when the incident angle of incident light is changed in the range of 0° to 30°. (G2) is 5 nm or less. That is, it is difficult for the light transmittance of the near-infrared light cut filter to depend on the incident angle of the incident light.

When the near-infrared light cut filter has, for example, the near-infrared light reflecting unit 150 including a dielectric multilayer film, the frequency dependence of the transmittance of light at the near-infrared light reflecting unit 150 changes according to the incident angle of incident light. That is, for example, the near-infrared light blocking wavelength of the near-infrared light reflecting unit 150 is about 700 nm when the incident angle of the incident light is 0°. When the incident angle of the incident light reaches 30°, the incident angle dependence becomes about 675 nm. It may occur. Then, assuming that the near-infrared light cut filter has the near-infrared light absorbing unit 140, the light transmittance realized by combining with the near-infrared light reflecting unit 150 may vary greatly depending on the incident angle of the incident light. Specifically, the near-infrared light cut filter having the near-infrared light reflecting unit 150 and the near-infrared light absorbing unit 140 is the angle of the near-infrared light cutoff wavelength when the incident angle of incident light is changed in the range of 0° to 30°. There may be cases where the dependent change width is about 30 nm. Conversely, in a predetermined light wavelength in the near-infrared light region, the light transmittance of the near-infrared light cut filter varies greatly depending on the incident angle of the incident light. For example, if light with a wavelength of 660 to 690 nm is incident, the light transmittance is about 20% when the incident angle is small at the center of the acquired image, and when the incident angle is large at the periphery of the acquired image, the light transmittance is almost 0%. As a result, the light wavelength dependence of the transmittance changes at the periphery and the center of the acquired image, resulting in a phenomenon of deterioration of the so-called "redness".

According to the camera structure according to the eighth embodiment of the present invention, in the near-infrared light cut filter, the angle-dependent change width of the near-infrared light blocking wavelength when the incident angle of incident light is changed in the range of 0° to 30° is 5 nm or less. , It exhibits an excellent effect that a difference in color expression in the acquired image is less likely to occur, and thus the image quality is improved.

As an effect of combining the near-infrared light absorbing unit 140 and the near-infrared light reflecting unit 150, when the transmittance of light at a predetermined wavelength is 1% or more, the acquired image is affected. Therefore, as a spectral characteristic of the near-infrared light absorbing unit 140, when the light transmittance of the near-infrared light reflecting unit 150 is 50% in the light wavelength region where the light transmittance is 2% or more, the image quality of the acquired image is different from the color sense seen by the naked eye. It becomes different. In addition, when the near-infrared light reflecting part 150 is formed of, for example, a dielectric multilayer film, the light transmittance changes according to the incident angle of the incident light, so that the light wavelength dependence of the transmittance at the periphery and center of the acquired image changes, so-called ``red There is a phenomenon of deterioration of image quality such as "omission".

According to the camera structure according to the eighth embodiment of the present invention, as the effect of combining the near-infrared light absorbing unit 140 and the near-infrared light reflecting unit 150, the transmittance of light is less than 1% in the light wavelength region of 685 nm to 755 nm, It also exhibits an excellent effect that the difference between the image quality and what is seen with the naked eye is reduced. In addition, when the incident angle of the incident light to the near-infrared light reflecting unit 150 is changed in the range of 0° to 30°, the near-infrared light cut-off wavelength of the near-infrared light reflecting unit 150 is always a light absorption wavelength whose light transmittance is less than 2%. Since entering the region 700, the dependence of the incident angle of the spectral characteristics on the light in the near-infrared region becomes small, and the optical wavelength that can be acquired in the peripheral and central portions of the acquired image is not changed, thereby exhibiting an excellent effect that the image quality is improved.

14A is a cross-sectional view of a camera structure applied to a portable communication device A as an imaging device according to a ninth embodiment of the present invention. In the case of this embodiment, the solid-state imaging device is an information communication device and a portable communication device (A). The camera structure includes a cover glass 400 to which an optical filter function is added from the side where light enters, and a camera module 501 accommodated in a housing 520 of a portable communication device A such as a smartphone. The camera module 501 includes a lens unit 450, which is an optical lens group disposed on the side of the cover glass 400 to which the optical filter function is added, and the cover glass 400 and the lens unit 450 to which the optical filter function is added. A near-infrared light cut filter for cutting the light in the near-infrared region is not disposed between the optical path from the lens unit 450 to the image pickup device 570, provided with an imaging device 570 that receives light incident through I am doing it. In detail, as shown in FIG. 14A, a cover glass 400 to which an optical filter function is added, a lens unit 450, a lens carrier 540, a magnet holder 430, an imaging device 570, and a substrate It is mainly composed of 580, and is fixed to the smartphone housing 520. The connection between the imaging device 570 and the substrate 580 may be connected by wire bonding or flip chip mounting may be performed.

What is greatly different from the conventional camera structure of Fig. 11A is that the optical filter 60 (refer to Fig. 11A) for cutting near-infrared light, which has been required for improving image quality, is omitted. Instead, a filter function for cutting near-infrared light is added to the cover glass 10, which has been mainly responsible for protecting the camera module 1 in the past. With such a structure, the entire length of the camera structure can be made shorter than the conventional one, and since the optical filter 60 is not disposed in the vicinity of the imaging element 70, the filter is used in the manufacturing process of the optical filter 60. It exhibits a remarkable effect that granular dust (particles) adhering to the surface of the image pickup device 70 does not fall on the surface of the imaging device 70 to deteriorate the image. In addition, in the assembling step of the camera module 1, a step for arranging and assembling the near-infrared light cut filter 60 is also eliminated, which further reduces cost, improves yield, and improves work efficiency.

Further, by providing the camera structure of Fig. 14A, the portable communication device A exhibits an effect of being able to be manufactured in a smaller size, thinner, and inexpensively.

14B shows a laminated structure of a cover glass 400 to which an optical filter function is added, which is continuously installed in the housing of the portable communication device A and protects the camera module as an internal mechanism from the outside. The cover glass 400 to which an optical filter function has been added uses a crystallized glass 630 as a transparent substrate that transmits light, and an antireflection film 620 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region. It is formed on the incident side of light based on the crystallized glass 630. Further, an antifouling coating film 610 for preventing contamination from outside is provided on the outermost side of the side where light is incident. On the light-emission side, the near-infrared light reflecting film 650 as a near-infrared light reflecting unit that sequentially reflects the light in the near-infrared region from the farthest with respect to the crystallized glass 630, and the near-infrared light reflecting film 650 as a near-infrared light reflecting unit. A near-infrared light absorbing film 640 as an external light absorbing part is formed. An antireflection film 620 may be further formed on the farthest side of the light emission side.

In general, crystallized glass has a large crystal grain, so it is difficult to pass light. However, with recent advances in technology, it is possible to control the crystal grains to a nanometer size and to increase the transmittance of light, for example, similar to the impact resistance and high hardness clear glass ceramics manufactured by Ohara Corporation. If such crystallized glass is used, it is possible to manufacture a cover glass having both impact resistance and fracture toughness in which cracks are less likely to occur. Then, the cover glass 400 to which the optical filter function is added is realized by forming the above-described laminated structure on the cover glass. In addition, it is theoretically conceivable to use blue glass as the cover glass 400 to which the optical filter function is added, but it is not appropriate because the impact resistance is low and the fracture toughness is difficult to generate cracks. It is also conceivable to form a cover glass 400 to which an optical filter function is added by forming a near-infrared light absorbing film 640 or a near-infrared light reflecting film 650 to be described later on the tempered glass, but in the case of using the crystallized glass 630 Compared to this, it has a disadvantage of low impact resistance. In addition, it is also conceivable to form a near-infrared light absorbing film 640 or a near-infrared light reflecting film 650 on a sapphire glass having high hardness to form a cover glass 400 with an optical filter function added, but the cost increases significantly and crystallization Compared to the case of using the glass 630, the workability is low.

The antifouling coating film 610 prevents fingerprint contamination and sebum contamination and makes it easier to wipe off 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 incident side of light in the laminated structure of the cover glass by coating or spraying.

The antireflection film 620 suppresses reflection of light in the visible region while reflecting light in the ultraviolet region. The antireflection film 620 is a dielectric multilayer film and is formed by alternately stacking a nitride film and an oxide film. The dielectric film constituting the antireflection film 620 is formed by alternately stacking a plurality of nitride films and oxide films. As the nitride film, silicon nitride, silicon oxynitride, aluminum nitride, or the like can be used. In the case of using silicon oxynitride, it is preferable that the stoichiometric ratio (oxygen/nitrogen) of oxygen and nitrogen is 1 or less. As the oxide film, silicon oxide (SiO2), aluminum oxide (Al2O3), or the like can be used. By using silicon nitride or silicon oxynitride as the film of the antireflection film 620, the antireflection film 620 can be formed using the same film formation method and film formation apparatus as the near-infrared light reflection film 150 to be described later, which is advantageous in a process.

As the antireflection film 620, an oxide film may be used instead of a nitride film. In addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), and the like can be used as the material of the oxide film. Further, when the antireflection film 120 is formed of a plurality of types of oxide films having different refractive indices, it is appropriately selected from the above oxides.

As the antireflection film 620, a known film formation method, for example, 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), etc. can be used. have. It is preferable to use a sputtering method or an ion beam sputtering method for forming a nitride film.

The near-infrared light absorbing film 640 is a surface of the crystallized glass 630 opposite to the antireflection film 620 described above, that is, the side of the imaging element 570 of the cover glass 400 to which an optical filter function is added (Fig. It is formed in 14(A)). The near-infrared light absorbing film 640 transmits light in the visible region and absorbs a part of light in the near-infrared region from the red region. The near-infrared light absorbing film 640 contains an organic dye and is composed of a resin film having a maximum absorption wavelength in the range of 700 nm to 750 nm (refer to the solid line (A2) in FIG. 13A). Since the near-infrared light absorbing film 640 is adjacent to the crystallized glass 630, it is preferable to reduce the refractive index difference between the two to reduce the reflectance at the interface. By having the near-infrared light absorbing film 640, the dependence of the spectral transmittance characteristic according to the incident angle can be reduced, and thus excellent near-infrared light cut property can be obtained.

As the organic dye, an azo compound, a phthalocyanine compound, a cyanine compound, a dimonium compound, or the like can be used. Polyacrylic, polyester, polycarbonate, polystyrene, polyolefin, or the like can be used as the resin material as the binder (the binder of the pigment) constituting the near-infrared light absorbing film 640. The resin material may be a mixture of a plurality of resins, or may be a copolymer using a monomer of the resin. In addition, the resin material may have a high transmittance with respect to light in the visible region, and is selected in consideration of the correspondence with the organic dye, film formation process, cost, and the like. In addition, in order to improve the UV resistance of the near-infrared light absorbing film 640, a sulfur compound or the like may be added to the resin material.

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

The near-infrared light reflecting film 650 is a dielectric multilayer film formed by alternately stacking a plurality of dielectrics having different refractive indices like the antireflection film 620. However, the dielectric multilayer film constituting the near-infrared light reflecting film 650 is formed by stacking a plurality of oxide films having different refractive indices, and the adjacent oxide films are oxide films of different types. In the first embodiment, the near-infrared light reflecting film 650 is formed by alternately stacking tens of layers of two types of oxide films. As the oxide film, in addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), and the like are used.

In the near-infrared light reflecting film 650, each oxide film is formed to have a thickness of λ/4 with the wavelength of light to be reflected as λ. By doing this, the light reflected from all the interfaces of the alternating layer becomes the same phase when it reaches the incidence surface, resulting in the light being intensified with each other. That is, the reflectance increases near the wavelength λ, and functions as a light reflective film. In this embodiment, the film may be designed to reflect light in the near-infrared region as λ. Further, the near-infrared light reflecting film 650 is also formed using the same film forming method and film forming apparatus as the antireflection 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, the imaging device generally includes visible light, and has a sensitivity to light having a longer wavelength, that is, light having a wavelength of about 1.1 μm. Therefore, if the image captured by the imaging device is taken as a photograph, it does not appear as a natural color tone and causes a sense of incongruity.

When the cover glass 400 to which the optical filter function is added has a laminated structure as shown in Fig. 14B, since a near-infrared light reflecting film 650 formed of a dielectric multilayer film is provided, the near-infrared light absorbing film 640 absorbs It becomes possible to obtain an image with a natural color tone by cutting light with a wavelength of 700 nm or more that cannot be achieved.

The dependence of the light transmittance of the near-infrared light reflecting film 650 on the light wavelength is shown in Fig. 13A. Specifically, the dotted line R3 represents the spectral characteristics of the light transmittance of the near-infrared light reflecting film 650 alone when the incident angle of the incident light is 0°, and the dotted line R4 indicates the incident angle of the incident light at 30° The spectral characteristics of the light transmittance in the near-infrared light reflecting film 650 alone are shown.

In the present embodiment, when the wavelength of light incident on the near-infrared light reflecting layer 650 decreases as the wavelength of light incident on the near-infrared light reflecting film 650 increases, the wavelength at which the transmittance of light decreases to 50% is defined as the near-infrared light cutoff wavelength. Even if the incident angle is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength of the near-infrared light reflector 650 always enters the light absorption wavelength region 700 where the light transmittance is less than 2%, The dependence of the angle of incidence of the spectral characteristic on is small, and since the optical wavelength that can be acquired at the peripheral and central portions of the acquired image does not change, the image quality is improved.

That is, by combining the near-infrared light reflecting film 650 and the near-infrared light absorbing film 640 that does not depend on the incident angle on the light absorption rate, it is possible to construct a near-infrared light cut filter in which the transmittance of light is less dependent on the incident angle of light. It becomes (see Fig. 13(B)).

In addition, since the cover glass 400 that protects the camera in the smartphone housing 520 from the outside world can cut the light in the ultraviolet region by the anti-reflection film 620, an optical lens group formed of synthetic resin, which is a component of the camera ( The lens unit 450 may be prevented from being deteriorated by ultraviolet rays, and the near-infrared light absorbing film 640 including an organic dye may be prevented from being deteriorated by ultraviolet rays. Further, by the anti-reflection function for light in the visible region, more incident light can be introduced and a bright image can be obtained.

In addition, the antireflection film 620 is formed by alternately stacking a nitride film and an oxide film. In general, the nitride film has a higher hardness than the oxide film and reaches a hardness of 9H or more in a pencil hardness test. Therefore, the anti-reflection film 120 is configured to include a nitride film, thereby improving the scratch resistance. Further, the nitride film has a higher packing density and is denser than the oxide film. Since it does not contain oxygen as a component, it is not also a source of oxygen. Therefore, by providing the nitride film outside the near-infrared light-absorbing film 640, the invasion of oxygen and moisture into the near-infrared light-absorbing film 640 is prevented and deterioration of the near-infrared light-absorbing film 640 is suppressed.

In general, optical filters have a large number of optical interface surfaces. On the other hand, a highly antireflective film is applied to the lens. It is difficult to achieve the same level of transmittance as a lens with an optical filter that cuts light in the near-infrared region, and there are cases in which the reflected light is returned to the lens side. This is the cause of stray light that creates ghosts in burns. In the conventional camera structure, since the optical filter 60 is placed near the imaging device 70 on the optical path between the lens unit 50 and the imaging device 70, it was difficult to avoid causing the ghost as described above (Fig. 11). See (A)). However, according to the camera structure according to the present embodiment, since stray light as described above does not occur, a remarkable effect of improving image quality is exhibited.

According to the ninth embodiment of the present invention, a remarkable effect can be achieved in that an imaging device incorporating a camera structure with improved image quality than the conventional one can be realized at low cost.

In addition, it goes without saying that the camera structure and the imaging device according to the embodiment of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope not departing from the gist of the present invention.

1 camera module
10 cover glass
20 smartphone housing
22 body
30 magnet holder
40 lens carrier
50 lens units
60 optical filter
70 Imaging element
80 substrate
100 cover glass with optical filter function
110 antifouling coating film
120 anti-reflective film
130 crystallized glass
140 Near-infrared light absorbing film
150 Near-infrared light reflective film
160 incident surface
170 exit plane
180 measurement objects
190 incident light
200 vertical axis
Cover glass with 210 optical filter function
Cover glass with 215 near-infrared light reflection function
Plate with 217 near-infrared light absorption function
220 clear glass
222 transparent synthetic resin film
230 anti-reflective layer
232 Morse Eye Structure
240 image sensor cover
242 Transparent synthetic resin film base material image pickup device cover
244 Imaging element cover with near-infrared light absorption function
Lens element having 250 near-infrared light absorber
255 transparent lens element
Lens element having 270 near-infrared light reflector
300 light source
310 High reflective material
320 Low reflective material
360 clear glass
370 anti-reflective film
380 blue glass
390 Near-infrared light reflective film
Cover glass with 400 optical filter function
430 magnet holder
450 lens unit
500 Optical element with near-infrared light absorption function added
501 camera module
520 smartphone housing
Optical element with 530 optical filter function added
540 lens carrier
550 cover glass
570 imaging element
580 substrate
610 antifouling coating film
620 anti-reflective film
630 crystallized glass
640 Near-infrared light absorbing film (near-infrared light absorbing part)
650 Near-infrared light reflective film (near-infrared light reflector)
700 light absorption wavelength range
A mobile communication device
A1 Spectral characteristics of conventional near-infrared light absorbing ink
A2 Spectral Characteristics of New Near Infrared Absorption Ink
C1 Spectral characteristics at an incident angle of 0°
C2 Spectral characteristics at an incident angle of 30°
C3 Spectral characteristics at an incident angle of 0°
C4 Spectral characteristics at an incident angle of 30°
G ghost
Spectral characteristics of the conventional near-infrared reflector when the R1 incident angle is 0°
Spectral characteristics of a conventional near-infrared reflector at an incident angle of R2 of 30°
R3 Spectral Characteristics of New Near-Infrared Reflector at 0° Incidence Angle
R4 Spectral Characteristics of New Near-Infrared Reflector at Incidence Angle of 30°

Claims (22)

As a camera structure for imaging,
An optical lens group disposed on the incident side of the light,
An imaging device that receives light incident through the optical lens group,
In the camera structure, a light reflecting portion formed on a cover glass disposed on an incident side of light than the optical lens group, and reflecting light in an ultraviolet region and light in a near-infrared region including a range of 750 nm to 1000 nm;
In the above camera structure, it is disposed on the side of the imaging device than the optical lens group, and includes a near-infrared light absorbing portion for absorbing light in the near-infrared region,
The light reflecting part, the optical lens group, and the near-infrared light absorbing part are arranged as the light reflecting part, the optical lens group, and the near-infrared light absorbing part sequentially from the incident side of light, and provided as separate bodies,
A camera structure, characterized in that, between the light path from the near-infrared light absorbing unit to the image pickup device, there is no other light reflecting unit that reflects light in the ultraviolet region and light in the near-infrared region including a range of 750 nm to 1000 nm. The method according to claim 1,
The near-infrared light absorbing unit has a light absorption wavelength region having a light transmittance of less than 2% in a region of 685 nm to 755 nm as a wavelength of light,
The light reflecting unit has a characteristic of substantially totally reflecting light having a wavelength longer than the near-infrared light cut-off wavelength when the wavelength at which the transmittance of light is reduced to 50% is defined as a near-infrared light cutoff wavelength,
When the angle of incidence of the incident light to the light reflecting unit is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength is always included in the light absorption wavelength range. The method according to claim 1,
The near-infrared light absorbing unit has a light absorption wavelength region having a light transmittance of less than 2% in a region of 685 nm to 755 nm as a wavelength of light,
The light reflecting unit has a characteristic of substantially totally reflecting light having a wavelength longer than the near-infrared light cut-off wavelength when the wavelength at which the transmittance of light is reduced to 50% is defined as a near-infrared light cutoff wavelength,
When the incident angle of the incident light to the light reflecting unit is changed in the range of 0° to 30°, the near-infrared light cutoff wavelength is always included in the light absorption wavelength region, so that the angle of the light reflecting unit and the near-infrared light absorbing unit Camera structure, characterized in that the dependent change width is 5 nm or less. The method according to any one of claims 1 to 3,
The camera structure, wherein the cover glass is directly fixed to a housing of a portable communication device. The method according to any one of claims 1 to 3,
A camera structure, wherein an imaging device cover that covers at least a part of the imaging device when viewed from the side to which light is incident is disposed between the optical lens group and the imaging device. The method of claim 5,
The camera structure, wherein the imaging device cover is made of glass. The method of claim 5,
The camera structure, wherein the imaging device cover is a synthetic resin film. The method of claim 5,
The camera structure, wherein the thickness of the imaging device cover is 0.2 mm or less. The method of claim 5,
The camera structure, wherein the imaging device cover includes an antireflection layer for preventing reflection of light in at least a visible region. The method of claim 5,
A camera structure comprising an antireflection layer for preventing reflection of light in at least a visible region on both surfaces of the imaging device cover. The method of claim 9,
The anti-reflection layer is a camera structure, characterized in that the fine protrusion structure consisting of fine protrusions formed on the surface of the imaging device cover. The method of claim 9,
The camera structure, wherein the antireflection layer is a coating film formed on a surface of the image pickup device cover. The method of claim 5,
The camera structure, wherein the imaging device cover includes the near-infrared light absorbing part. The method according to any one of claims 1 to 3,
The near-infrared light absorbing unit is a near-infrared light absorbing film that absorbs light in a near-infrared region, and includes an organic pigment. An imaging device having the camera structure according to any one of claims 1 to 3. delete delete delete delete delete delete delete

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