JP6589061B2 - Camera structure, imaging device - Google Patents

Description

  The present invention relates to a camera structure provided in an imaging apparatus.

  In this century, an image pickup apparatus, that is, a camera, has become an image pickup apparatus using a solid-state image pickup element (image pickup element), a so-called digital camera. In addition, information communication devices such as personal computers (PCs), tablet PCs, and smartphones have become widespread and are used on a daily basis. These information communication devices often incorporate a small camera module, and at present, the information communication device may include a high-performance device in which the number of pixels of the image sensor exceeds 10 million. Information communication devices, particularly smartphones that are portable communication devices, tend to be thin and light, and the camera modules that are parts thereof are also required to be small 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 when the camera module is downsized.

  In recent years, there has been an increasing need for automatic driving of automobiles, and in some car models, car storage using an in-vehicle camera, automatic braking, and assistance for night driving have already been put into practical use. Camera modules used for in-vehicle cameras are also becoming smaller and higher in performance, and in order to recognize images, it is strongly required to remove noise such as ghosts from images.

  Note that when a lens included in the imaging apparatus is directed toward a light source having a high light intensity, light is repeatedly reflected on a lens surface or the like, and an unnecessary image appears in a flare phenomenon (ghost) 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 clear unnecessary image is reflected by repeated reflection of light on a lens surface is called a ghost phenomenon.

  As shown in FIG. 11A, the camera module 1 having a conventional camera structure mainly includes a lens unit 50, a lens carrier 40, a magnet holder 30, an optical filter 60, and an image sensor 70. It is fixed (for example, refer to JP2013-153361A). Among these, the optical filter 60 mainly plays a role of cutting light in the near infrared region. The human eye is sensitive to light in the visible region (visible light) with a wavelength of 380 nm to 780 nm. On the other hand, the image sensor generally has sensitivity to visible light and longer wavelength light, that is, light having a wavelength of about 1.1 μm. Therefore, if an image captured by the image sensor is used as it is as a photograph, it does not look natural to human eyes and causes a sense of discomfort. Therefore, the camera module 1 has a configuration in which an optical filter 60 (near infrared light cut filter) that cuts light in the near infrared region is incorporated.

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

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

  In this specification, an internal mechanism of an imaging apparatus essential for imaging such as a lens unit including an optical lens group, a lens carrier, an imaging element, and a magnet holder is defined as a camera module. A camera module including a cover glass that protects the internal mechanism of the imaging apparatus from the outside is defined as a camera structure.

  FIG. 11B is an explanatory diagram for explaining an experiment method of an experiment performed with a conventional camera structure. In the experiment, a light emitting diode having a specific center wavelength was used as a light source, and the emitted light was imaged. In the experiment, a light emitting diode having a central wavelength of 460 nm was used as the light source 300. In order to make it easy to see the flare phenomenon and the ghost phenomenon that occur, a low reflective material 320 is placed in the background of the light source 300, and a high reflective material 310 is placed around the low reflective material 320.

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

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

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

  FIG. 11E is an image captured by the image sensor 70 having the conventional camera structure described in FIGS. 11A to 11D. A petal-like ghost G is generated around the light source 300, indicating that the image quality is degraded. Such a ghost phenomenon can occur even when the center wavelength of the light source 300 is changed from 420 nm to 660 nm.

JP 2013-153361 A

  In order to reduce the ghost phenomenon and flare phenomenon, it is generally necessary to make the optical lens group provided in the camera a more advanced and complicated structure and to improve the antireflection coating of the lens element itself. However, this is a difficult problem in the camera module of the information communication device and the camera module of the in-vehicle camera that are required to be small and light and inexpensive.

  A main cause of the ghost phenomenon is that a near-infrared cut filter including a near-infrared light reflection film is in the vicinity of the image sensor. Therefore, the ghost phenomenon can be greatly suppressed by arranging the near-infrared light reflecting portion on the outside of the camera module as much as possible, for example, on the cover glass. In addition, by bringing the near-infrared light reflection part to the outside, in order to prevent the shift of the cutoff wavelength of the near-infrared light, which may occur when light with a large incident angle enters the camera module, The spectral characteristics of the infrared light absorbing unit and the spectral characteristics of the near infrared light reflecting unit are adjusted so that the image quality does not depend on the angle of incident light.

  (1) The present invention is a camera structure for imaging, an optical lens group disposed on a light incident side, an image sensor that receives light incident through the optical lens group, and a near-infrared region A near-infrared light reflecting portion that reflects light in the near-infrared region, and a near-infrared light absorbing portion that absorbs light in the near-infrared region, and the near-infrared light reflecting portion and the near-infrared light absorbing portion are The camera structure is characterized by being a separate body.

  According to the invention of the above (1), there is a degree of freedom in the place where the near infrared light reflecting part is arranged and the place where the near infrared light absorbing part is arranged. It is possible to achieve the remarkable effect of improving the image quality.

  (2) In the present invention, the near-infrared light reflection part and the near-infrared light absorption part are arranged in order from the light incident side with the near-infrared light reflection part and the near-infrared light absorption part. The camera structure described in (1) above is provided.

  In some cases, light having a longer wavelength than light having a wavelength that is absorbed by the near-infrared light absorbing portion is transmitted. Therefore, when the near-infrared light absorbing part and the near-infrared light reflecting part are arranged in order from the light incident side, the light on the longer wavelength side than the light of the wavelength absorbed by the near-infrared light absorbing part is It becomes easy to enter into the module, and before reaching the near-infrared light reflection part that can cut light on the long wavelength side, it is reflected on the lens surface or the like and becomes stray light, which causes a drop in image quality.

  According to the invention of (2) above, the near-infrared light reflecting portion and the near-infrared light absorbing portion are arranged in order from the light incident side with the near-infrared light reflecting portion and the near-infrared light absorbing portion. This has the effect of suppressing stray light on the long wavelength side.

  (3) The present invention is characterized in that the near-infrared light reflecting portion includes a lens element constituting the optical lens group in the camera structure, and is disposed closer to the light incident side than the lens element. The camera structure described in (1) or (2) above is provided.

  According to the invention of (3) above, the near-infrared light reflecting portion includes the lens element constituting the optical lens group, and is disposed closer to the light incident side than the lens element. The distance from the imaging device to the near-infrared light reflecting portion is larger than the position of the filter. The near-infrared light reflection unit may easily transmit light in the ultraviolet region when the incident angle of light deviates from the vertical in the axial direction. As the distance from the image sensor increases, the angle at which the image sensor is viewed from the near-infrared light reflection unit decreases, so extra light in the ultraviolet region that passes through the near-infrared light reflection unit and reaches the image sensor directly. There is an effect that it can be reduced.

  (4) The present invention is characterized in that the near-infrared light absorbing portion includes a lens element constituting the optical lens group in the camera structure, and is disposed closer to the image sensor than the lens element. A camera structure according to any one of (1) to (3) above is provided.

  According to the invention of (4) above, the near-infrared light absorber often has a transmittance that does not depend on the incident angle of light. Therefore, the near-infrared light absorption unit includes a lens element that constitutes an optical lens group in the camera structure, and is arranged closer to the image sensor than the lens element, so that the near-infrared light absorption unit attempts to enter the image sensor from various directions. There is a remarkable effect that stray light can be effectively suppressed.

  (5) The present invention is characterized in that an image sensor cover that covers at least a part of the image sensor as viewed from the light incident side is disposed between the optical lens group and the image sensor. A camera structure according to any one of 1) to (4) is provided.

  If dust that does not easily transmit light adheres to the image sensor, the image quality deteriorates. According to the invention of (5) above, the image sensor cover that covers at least a part of the image sensor as viewed from the light incident side is disposed at a position close to the image sensor between the optical lens group and the image sensor. Therefore, there is a remarkable effect that dust that can adhere to the image sensor can be reduced and deterioration in image quality can be prevented.

  (6) The present invention provides the camera structure as described in (5) above, wherein the image sensor cover is made of glass.

  According to the invention of (6), there is an effect that an image sensor cover that is less deformed by temperature change can be manufactured at low cost.

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

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

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

  According to the invention of the above (8), there is a remarkable effect that it is possible to provide a camera module that is thinner than the conventional one.

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

  The image sensor cover is disposed at a position close to the image sensor between the optical lens group and the image sensor. Therefore, when the image sensor cover reflects light, it causes a significant deterioration in the image quality of the image acquired by the image sensor.

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

  (10) The invention according to any one of (5) to (8), wherein an antireflection layer that prevents reflection of light in at least a visible region is provided on both surfaces of the imaging element cover. Provide the camera structure.

  According to the invention of (10), more incident light can be captured, and reflected light caused by the image sensor cover, particularly reflected light from the image sensor itself is further reflected by the image sensor cover. Thus, it is possible to prevent the image sensor from returning to the image sensor and to improve the image quality.

  (11) The camera according to (9) or (10), wherein the antireflection layer has a fine protrusion structure including fine protrusions formed on a surface of the image sensor cover. Provide structure.

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

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

A multilayer film in which two types of thin films having different refractive indexes of light are alternately laminated can form a light antireflection film. It is known that such a multilayer film can also 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 image pickup device cover provided with an antireflection film having a stable quality in a large amount at a low cost.

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

  According to the invention of (13), since the imaging element cover includes the near-infrared light absorbing portion, there are remarkable effects of reducing the number of parts and 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 includes an organic dye. ) Is provided.

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

  (15) In the present invention, the camera structure further includes a cover glass that protects an internal mechanism of the imaging apparatus from the outside, and the cover glass includes the near-infrared light reflection portion. ) To (14).

  According to the invention of (15) above, since the cover glass has the near-infrared light reflecting film that reflects light, an effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging apparatus can be achieved. In addition, it is not necessary to place a member having a near-infrared light reflecting film in a region close to the imaging device, so that reflection of light incident on the internal mechanism of the imaging device can be suppressed, and stray light can be suppressed as a result. , Can reduce the cause of ghosts and flares.

  (16) The present invention is a camera structure that performs imaging, an optical lens group disposed on a light incident side, an image sensor that receives light incident through the optical lens group, and a near-infrared region. A near-infrared light reflecting portion that reflects the light of the near-infrared region, and a near-infrared light absorbing portion that absorbs light in the near-infrared region, wherein the near-infrared light reflecting portion and the near-infrared light absorbing portion are The camera structure is included in an integrated optical element included in the optical lens group.

  According to the invention of (16) above, since the optical lens group includes the integrated optical element that includes the near-infrared light reflecting part and the near-infrared light absorbing part at the same time, the near-infrared light is located at a position close to the imaging element. There is no need to insert a member having a reflective film. Therefore, reflection of light incident on the internal mechanism of the imaging apparatus can be suppressed, and as a result, stray light can be suppressed and the cause of ghost and flare can be reduced.

  (17) The present invention includes a near-infrared light absorbing portion that absorbs light in the near-infrared region and a near-infrared light reflecting portion that reflects light in the near-infrared region, and the near-infrared light absorbing portion. Has a light absorption wavelength region in which the light transmittance is less than 2% in the region of 685 nm to 755 nm as the wavelength of light, and the wavelength of incident light to the near infrared light reflection portion increases. Accordingly, when the wavelength at which the light transmittance is reduced to 50% is defined as the near-infrared light cutoff wavelength, the near-infrared light reflecting portion has a wavelength longer than the near-infrared light cutoff wavelength. When the incident angle of the incident light to the near infrared light reflecting portion is changed in the range of 0 ° to 30 °, the near infrared light cutoff wavelength is always the above. Provided is a camera structure that is included in a light absorption wavelength region.

  As an effect of combining the near-infrared light absorbing portion and the near-infrared light reflecting portion, the acquired image is affected when the light transmittance at a predetermined wavelength is 1% or more. Therefore, as a spectral characteristic of the near-infrared light absorbing portion, when the light transmittance of the near-infrared light reflecting portion becomes 50% in the light wavelength region where the light transmittance is 2% or more, the image quality of the acquired image is seen with the naked eye. It will be different from the color. When the near-infrared light reflection part is formed of, for example, a dielectric multilayer film, the light transmittance changes depending on the incident angle of the incident light, so the transmittance depends on the light wavelength at the peripheral part and the central part of the acquired image. The image quality is deteriorated, so-called “red-out”. In particular, when the infrared reflection portion is arranged on the outside of the camera module, specifically, on the cover glass, light with a large incident angle can enter the camera module, and this image quality deterioration becomes remarkable.

  According to the invention described in (17) above, as the effect of combining the near-infrared light absorbing portion and the near-infrared light reflecting portion, light longer than the near-infrared light cutoff wavelength in the light wavelength region of 685 nm to 755 nm. Since the light transmittance is less than 1% in the wavelength region, there is also an excellent effect that the difference between the image quality of the acquired image and that seen with the naked eye is reduced. Further, when the incident angle of the incident light to the near-infrared light reflecting portion is changed in the range of 0 ° to 30 °, the near-infrared light cutoff wavelength of the near-infrared light reflecting portion always has a light transmittance of 2. Because it enters the light absorption wavelength region that is less than%, the incident angle dependency of the spectral characteristics for light in the near infrared region is reduced, and the light wavelength dependency of the transmittance does not change between the peripheral part and the central part of the acquired image. There is an excellent effect that 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. Has a light absorption wavelength region in which the light transmittance is less than 2% in the region of 685 nm to 755 nm as the wavelength of light, and the near-infrared light reflecting portion has a reduced light transmittance of 50%. % Is defined as the near-infrared light cutoff wavelength, and has a characteristic of substantially totally reflecting light having a wavelength longer than the near-infrared light cutoff wavelength, and is incident on the near-infrared light reflection portion. The near infrared light cutoff wavelength is always included in the light absorption wavelength region when the incident angle of light is changed in a range of 0 ° to 30 °. A camera structure according to any one of (16) is provided.

When the near-infrared light reflecting portion is provided on the side close to the outside of the camera structure, for example, on the cover glass, even the light having a large incident angle enters the camera structure. For example, when the near-infrared light reflecting portion is formed of a dielectric multilayer film, the light transmittance changes depending on the incident angle of incident light, so the light transmittance changes depending on the incident angle of incident light. And the central portion are different in the light wavelength dependency of the transmittance, and a so-called “red-out” image quality deterioration phenomenon occurs.
According to the invention described in (18) above, the near-red light of the near-infrared light reflecting portion is always changed when the incident angle of the incident light to the near-infrared light reflecting portion is changed in the range of 0 ° to 30 °. Since the external light cutoff wavelength enters the light absorption wavelength region where the light transmittance is less than 2%, the dependence of the spectral characteristic on the incident angle of light in the near infrared region is reduced, and the acquired image has a peripheral portion and a central portion. Since the wavelength of light that can be obtained does not change, the image quality is improved.

  Further, as an effect of combining the infrared light absorbing portion and the near infrared light reflecting portion, the light transmittance is 1% in the light wavelength region longer than the near infrared light cutoff wavelength in the light wavelength region of 685 nm to 755 nm 685 nm to 755 nm. Therefore, the excellent effect of reducing the difference between the image quality of the acquired image and what is seen with the naked eye is also achieved.

  (19) The present invention provides a cover glass that protects the internal mechanism of the imaging device from the outside, an optical lens group disposed on the cover glass side, and imaging that receives light incident through the cover glass and the optical lens group. An optical path from the optical lens group to the imaging device, the cover glass having a transparent substrate that transmits light, the near-infrared light absorbing unit, and the near-infrared light reflecting unit. The camera structure as described in (17) above, wherein no near infrared light cut filter for cutting light in the near infrared region is disposed between them.

  Since the near-infrared light reflection portion is provided on the side closest to the outside of the camera structure, that is, on the cover glass, even the light having a large incident angle enters the camera structure. For example, when the near-infrared light reflecting portion is formed of a dielectric multilayer film, the light transmittance changes depending on the incident angle of incident light, so the transmittance depends on the light wavelength at the peripheral portion and the central portion of the acquired image. The image quality is deteriorated, so-called “red-out”.

  According to the invention described in (19) above, the near-red light of the near-infrared light reflecting portion is always changed when the incident angle of the incident light to the near-infrared light reflecting portion is changed in the range of 0 ° to 30 °. Since the external light cutoff wavelength enters the light absorption wavelength region where the light transmittance is less than 2%, the dependence of the spectral characteristic on the incident angle of light in the near infrared region is reduced, and the acquired image has a peripheral portion and a central portion. Since the dependency of the transmittance on the light wavelength does not change, the image quality is improved.

  Further, as an effect of combining the infrared light absorbing portion and the near infrared light reflecting portion, light in a wavelength region longer than the near-infrared light cutoff wavelength among light wavelength regions from 685 nm to 755 nm in the light wavelength region from 685 nm to 755 nm is obtained. Since the transmittance is less than 1%, there is also an excellent effect that the difference between the image quality of the acquired image and what is seen with the naked eye is reduced.

  Furthermore, no near-infrared light cut filter for cutting light in the near-infrared region is arranged between the optical paths from the optical lens group to the image sensor, which contributes to a reduction in the overall height of the camera structure.

  (20) The present invention is a camera structure including a near-infrared light cut filter that blocks light in a near-infrared region, and the near-infrared light cut filter emits light when the wavelength of incident light is increased. Is defined as a near-infrared light cut-off wavelength, the near-infrared light cut-off wavelength when the incident angle of the incident light is changed in the range of 0 ° to 30 °. Provided is a camera structure characterized in that an angle-dependent change width 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 dependency of the light transmittance in the near-infrared light reflecting portion varies depending on the incident angle of incident light. . That is, for example, the near-infrared light blocking wavelength of the near-infrared light reflecting portion is about 700 nm when the incident angle of incident light is 0 °, and becomes about 675 nm when the incident angle of incident light is 30 °. Such incident angle dependency may occur. Then, assuming that the near-infrared light cut filter has a near-infrared light absorption part, the light transmittance realized in combination with the near-infrared light reflection part may greatly change depending on the incident angle of incident light. . Specifically, the near-infrared light cut filter having a near-infrared light reflection part and a near-infrared absorption part is capable of blocking near-infrared light when the incident angle of incident light is changed in the range of 0 ° to 30 °. The angle-dependent change width of the wavelength can be about 30 nm. In other words, the light transmittance of the near-infrared light cut filter varies greatly depending on the incident angle of incident light at a predetermined light wavelength in the near-infrared light region. For example, if light having 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 light is transmitted when the incident angle is large at the peripheral portion of the acquired image. As a result, a phenomenon that the rate becomes approximately 0% occurs, and as a result, the light wavelength dependency of the transmittance differs between the peripheral portion and the central portion of the acquired image, and so-called “red-out” image quality deterioration phenomenon occurs.

  According to the invention described in (20) above, in the near-infrared light cut filter, the angle-dependent change width of the near-infrared light cutoff wavelength when the incident angle of incident light is changed in the range of 0 ° to 30 °. Since the thickness is 5 nm or less, a difference in color expression in the acquired image hardly occurs, and an excellent effect of improving the image quality is obtained.

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

  According to the invention described in (21) above, even if a phenomenon occurs in which the wavelength dependency of the light transmittance in the near-infrared light reflecting portion changes depending on the incident angle of incident light, the near-infrared light reflecting portion and the near-red light The spectral characteristics of the light transmittance in the near-infrared light region when considering the external light absorbing part together are governed by the spectral characteristics of the light transmittance of the near-infrared light absorbing part. It is difficult to produce a difference in the expression, and the image quality is improved.

  (22) The present invention provides an image pickup apparatus having the camera structure according to any one of (1) to (21).

  According to the invention of the above (22), there is a remarkable effect that an image pickup apparatus equipped with a camera structure with improved image quality than before can be realized at low cost.

  According to the present invention, there is a degree of freedom in the place where the near-infrared light reflecting part is arranged and the place where the near-infrared light absorbing part is arranged, so that it can be arranged at the optimum positions in the camera structure. Thus, the remarkable effect of improving the image quality in the imaging apparatus can be obtained.

(A) It is sectional drawing of the camera structure applied to the mobile communication apparatus A which is an imaging device which concerns on 1st embodiment of this invention. (B) It is a structure figure of the cover glass with a near-infrared-light reflection function containing a near-infrared-light reflection part. (C) It is a structure figure of the image pick-up element cover with a near-infrared-light absorption function including a near-infrared-light absorption part. (A) It is structural drawing of the cover glass with an optical filter function. (B) It is a figure which shows the incident angle dependence of the spectral transmittance about a near-infrared-light reflection film. (C) It is explanatory drawing explaining the definition of an incident angle. It is a figure which shows the incident angle dependence of the spectral transmittance in the cover glass with an optical filter function provided with the near-infrared-light absorption film and the near-infrared-light reflection film. It is the figure which compared the spectral transmittance about the glass provided with the cover glass with an optical filter function, the glass provided with the near-infrared light absorption film, and the near-infrared light reflection film. It is explanatory drawing explaining the spectral transmittance about a dual band cover glass. (A) It is sectional drawing of the camera structure applied to the portable communication apparatus A which is an imaging device which concerns on 3rd embodiment of this invention. (B) It is a structure figure of the cover glass with a near-infrared-light reflection function containing a near-infrared-light reflection part. (C) It is a structural diagram of a plate with a near infrared light absorption function. (D) It is a structure figure of the image pick-up element cover provided with two or more antireflection layers by using transparent glass as a substrate. (E) It is a block diagram of the imaging cover which used as a base material the transparent synthetic resin film provided with the moth-eye structure which exhibits an antireflection function on both surfaces. (A) It is sectional drawing of the camera structure applied to the portable communication apparatus A which is an imaging device which concerns on 4th embodiment of this invention. (B) It is sectional drawing of the lens unit containing the optical lens element provided with the near-infrared-light absorption part. (C) It is sectional drawing of the lens unit containing the optical lens element provided with the near-infrared-light absorption part. (A) It is sectional drawing of the camera structure applied to the imaging device which concerns on 5th embodiment of this invention. (B) It is sectional drawing of a lens unit provided with the optical lens element containing a near-infrared-light reflection part and the optical lens element containing a near-infrared-light absorption part. (A) It is sectional drawing of the camera structure applied to the imaging device which concerns on the 6th embodiment of this invention. (B) It is sectional drawing of a lens unit provided with the optical element with a near-infrared-light absorption function containing a near-infrared-light absorption part. (C) It is a structural diagram of the optical element with a near infrared light absorption function. (A) It is sectional drawing of the camera structure applied to the imaging device which concerns on the 7th Embodiment of this invention. (B) It is sectional drawing of a lens unit provided with the optical element with an optical filter function containing a near-infrared-light reflection part and a near-infrared-light absorption part. (C) It is a structural diagram of the optical element 530 with an optical filter function. (A) It is sectional drawing of the conventional camera structure in a portable communication apparatus. (B) It is explanatory drawing explaining the experiment method of the experiment conducted with the conventional camera structure. (C) It is sectional drawing of the conventional cover glass. (D) It is sectional drawing of the conventional near-infrared light cut filter. (E) An image captured by a conventional camera structure. (A) It is a graph which shows the incident light angle dependence of the spectral characteristic of the light transmittance in the near-infrared-light absorption part using the conventional light absorption ink, and the spectral characteristic of the light transmittance in a near-infrared light reflection part. . (B) It is a graph which shows the incident light angle dependence of the spectral characteristic of the light transmittance at the time of combining a near-infrared-light absorption part and a near-infrared-light reflection part. (A) Spectral characteristics of light transmittance in the near-infrared light absorbing portion using light-absorbing ink having a wider light absorption band in the near-infrared light region, and light transmittance spectrum in the near-infrared light reflecting portion. It is a graph which shows the incident light angle dependence of a characteristic. (B) It is a graph which shows the incident light angle dependence of the spectral characteristic of the light transmittance at the time of combining a near-infrared-light absorption part and a near-infrared-light reflection part. (A) It is sectional drawing of the camera structure applied to the portable communication apparatus A which is an imaging device which concerns on 9th embodiment of this invention. (B) It is structural drawing of the cover glass with an optical filter function provided with two or more antireflection films.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 10 and FIGS. 12 to 14 are examples of embodiments for carrying out the invention. In the drawings, the same reference numerals denote the same components.

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

  The camera structure includes a cover glass 215 with a near-infrared light reflection function that protects the internal mechanism of the imaging apparatus from the outside and the camera module 1. The camera module 1 moves the lens unit 50 in the axial direction in order to realize an optical lens group that is an internal mechanism of the imaging apparatus, that is, a lens unit 50, a lens carrier 40 that holds the lens unit 50, and an autofocus function. The magnet holder 30, the image sensor 70 that receives light incident through the near-infrared light reflection function cover glass 215 and the lens unit 50, and is disposed between the lens unit 50 and the image sensor 70 and transmits light. An imaging element cover 244 with a near-infrared light absorption function using a transparent glass as a base material is provided. The image sensor cover 244 with a near infrared light absorption function covers at least a part of the surface of the image sensor 70 when the image sensor 70 is viewed from the lens unit 50 side in the axial direction.

  FIG. 1B is a structural diagram of a cover glass 215 with a near-infrared light reflecting function including a near-infrared light reflecting portion. The cover glass 215 with a near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate that transmits light, reflects the light in the ultraviolet region, and suppresses the reflection of the light in the visible region. Is formed on the light incident side with reference to the crystallized glass 130. An antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side where light enters. On the light emission side, an antireflection film 120 and a near-infrared light reflection film 150 that is a near-infrared reflection part that reflects light in the near-infrared region are formed in order from the farthest side with respect to the crystallized glass 130. To do.

  In addition, in the cover glass 215 with a near infrared light reflection function, the antireflection film 120 closest to the image sensor 70 may not be provided.

  1C includes a plurality of antireflection layers 230 that prevent reflection of light in at least the visible region, and further includes a near infrared light absorption film 140 that is a near infrared light absorption unit. 3 is a structural diagram of an image sensor cover 244. FIG. That is, the image sensor cover 244 with a near infrared light absorption function includes an antireflection layer 230 that prevents reflection of light in at least the visible region on both surfaces. The antireflection layer 230 has a material and a structure similar to those of the antireflection film 120, and the manufacturing method is the same.

  The imaging device cover 244 with a near infrared light absorption function uses the 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 light incident side with the transparent glass 220 as a reference, and the antireflection layer 230 and the near-infrared light absorbing film are formed on the light emission side in order from the farthest side with respect to the transparent glass 220. 140 is provided.

  That is, the camera structure applied to the mobile communication device A that is the imaging device according to the first embodiment of the invention is incident through the optical lens group (optical unit 50) disposed on the light incident side and the lens unit 50. Imaging device 70 that receives the transmitted light, a near-infrared light reflecting film 150 that is a near-infrared light reflecting portion that reflects light in the near-infrared region, and near-infrared light absorption that absorbs light in the near-infrared region. A near-infrared light absorption film 140, and the near-infrared light reflection part and the near-infrared light absorption part are formed separately from each other. A near-infrared light reflecting film 150 that is a near-infrared light reflecting part and a near-infrared light-absorbing film 140 that is a near-infrared light absorbing part are, in order from the light incident side, the near-infrared light reflecting film 150, The infrared light absorbing film 140 is disposed. A near-infrared light reflecting film 150 that is a near-infrared light reflecting portion includes a lens element constituting the lens unit 50 in the camera structure, and is disposed closer to the light incident side than the lens element. A near-infrared light absorbing film 140 that is a near-infrared light absorbing portion includes a lens element that constitutes the lens unit 50 in the camera structure, and is disposed closer to the imaging element 70 than the lens element. An image sensor cover 244 with a near infrared light absorption function that covers at least a part of the image sensor 70 when viewed from the light incident side is disposed between the lens unit 50 and the image sensor 70. The image sensor cover 244 with a near infrared light absorbing function includes the image sensor near infrared light absorbing portion. The near infrared light absorbing portion is a near infrared light absorbing film 140 that absorbs light in the near infrared region, and includes an organic dye. The camera structure further includes a near-infrared light reflecting cover glass 215 that protects the internal mechanism of the imaging apparatus from the outside, and the near-infrared light reflecting film 150, which is a near-infrared light reflecting portion, is provided on the cover glass. Including.

  As a means for realizing the imaging device cover 244 with a near-infrared light absorption function, for example, as a base material, a synthetic resin thin plate at least partially containing an organic dye that absorbs light in the near-infrared region is used. Also good. In addition, a so-called blue glass plate that absorbs light in the near-infrared region may be used in the same manner as a conventional near-infrared light cut filter. It can also be realized by attaching a film that cuts near-infrared light on a transparent plate.

  In general, crystallized glass is difficult to transmit light because of its large crystal grains. However, recent advances in technology have made it possible to control crystal particles to a nanometer size, such as impact-resistant and high-hardness clear glass ceramics manufactured by OHARA, Inc., thereby increasing light transmittance. By using such crystallized glass, it is possible to produce a cover glass having both impact resistance and fracture toughness in which cracks do not easily occur. And the cover glass 215 with a near-infrared-light reflection function is implement | achieved by forming said laminated structure in such a cover glass. Although it is theoretically possible to use blue glass as the cover glass 215 with a near-infrared light reflection function, it is not appropriate because it has low impact resistance and lacks fracture toughness that is difficult to crack. It is conceivable that a near-infrared light reflecting film 150 described later is formed on the tempered glass to form a cover glass 215 with a near-infrared light reflecting function, but the impact resistance is higher than when the crystallized glass 130 is used. Has low drawbacks. Further, it is conceivable to form a near-infrared light reflecting film 150 on the sapphire glass having a high hardness to form a cover glass 215 with a near-infrared light reflecting function, but the cost is remarkably increased and the crystallized glass 130 is used. Workability is low compared to the case.

  The antifouling coating film 110 prevents fingerprint stains and sebum stains and facilitates wiping off the stains. The antifouling coating film 110 is formed of a fluorine-based coating agent or the like, and is formed on the outermost side on the light incident side in the cover glass laminated structure by coating or spraying.

  The antireflection film 120 reflects light in the ultraviolet region and suppresses reflection of light in the visible region. The antireflection film 120 is a dielectric multilayer film, and is configured by alternately stacking nitride films and oxide films. 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. When silicon oxynitride is used, the stoichiometric ratio of oxygen to nitrogen (oxygen / nitrogen) is preferably 1 or less. As the oxide film, silicon oxide (SiO 2), aluminum oxide (Al 2 O 3), 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 described later. Process advantageous.

  As the antireflection film 120, an oxide film can be used instead of the nitride film. As a material for such an oxide film, in addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), or the like may be used. it can. In the case where the antireflection film 120 is composed of a plurality of types of oxide films having different refractive indexes, an appropriate selection is made from the oxides.

  The antireflection film 120 uses a known film formation method such as a vacuum deposition method, a sputtering method, an ion beam assisted deposition method (IAD method), an ion plating method (IP method), an ion beam sputtering method (IBS method), or the like. be able to. It is desirable to use a sputtering method or an ion beam sputtering method for forming the nitride film.

  The near-infrared light absorbing film 140 has a function of transmitting light in the visible region and absorbing part of light from the red region to the near-infrared 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 the broken line in FIG. 4). Since the near-infrared light absorbing film 140 is adjacent to the crystallized glass 130, it is desirable to reduce the difference in refractive index between the two to reduce the reflectance at the interface. By having such a near-infrared light absorbing film 140, it is possible to reduce the dependence of the spectral transmittance characteristics depending on the incident angle and to have excellent near-infrared light cut-off properties.

As the organic dye, an azo compound, a phthalocyanine compound, a cyanine compound, a diimonium compound, or the like can be used. Polyacryl, polyester, polycarbonate, polystyrene, polyolefin, or the like can be used as a resin material as a binder (pigment binder) 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. The resin material may be any material that has a high transmittance with respect to light in the visible region, and is selected in consideration of compatibility with an organic dye, a film formation process, cost, and the like. In order to improve the ultraviolet resistance of the near-infrared light absorbing film 140, a quencher (quenching dye) such as a sulfur compound may be added to the resin material.

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

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

  In the near-infrared light reflecting film 150, each oxide film is formed to have a thickness of λ / 4, where λ is the wavelength of light to be reflected. By doing this, the light reflected from all the interfaces of the alternating layers will be in the same phase when reaching the incident surface, and the light will be intensified, that is, the reflectance will increase near the wavelength λ, and as a light reflecting film Function. In the present embodiment, the film may be designed so that λ reflects light in the near infrared region. The near-infrared light reflection film 150 is also formed using the same film formation method and film formation apparatus as those of the antireflection film 120 described above.

  The human eye is sensitive to so-called visible light having a wavelength of 380 nm to 780 nm. On the other hand, the image sensor generally has sensitivity up to light having a longer wavelength, that is, light having a wavelength of about 1.1 μm, including visible light. Therefore, if the image captured by the image sensor is used as it is as a photograph, it does not look natural and causes a sense of discomfort.

  When the cover glass 100 with an integrated optical filter function having a near-infrared light reflecting portion and a near-infrared light absorbing portion is formed as a laminated structure as shown in FIG. Since the external light reflection film 150 is provided, it is possible to obtain a natural color image by cutting light having a wavelength of 700 nm or more that cannot be absorbed by the near-infrared light absorption film 140. Further, if the near-infrared light reflection film 150 alone is used to cut light in the near-infrared region, the reflectivity greatly changes depending on the incident angle of incident light, as will be described later. By combining the near-infrared light reflection film 150 and the near-infrared light absorption film 140 that does not depend on the incident angle with respect to the light absorption rate, the light transmission rate is less dependent on the incident angle of light. An infrared light cut filter can be configured.

  Moreover, since the cover glass 100 that protects the camera in the smartphone housing 20 from the outside can cut light in the ultraviolet region by the antireflection film 120, an optical lens group formed of a synthetic resin that is a component of the camera. It is possible to prevent the (lens unit 50) from being deteriorated by ultraviolet rays, and it is also possible to prevent the near-infrared light absorbing film 140 containing an organic dye from being deteriorated by ultraviolet rays. Further, the antireflection function for the light in the visible region can capture more incident light and acquire a bright image.

  The antireflection film 120 is configured by alternately laminating nitride films and oxide films. Generally, a nitride film has a higher hardness than an oxide film, and reaches a hardness of 9H or more in a pencil hardness test. Therefore, the antireflection film 120 including the nitride film has an effect of improving scratch resistance. Further, the nitride film is denser and denser than the oxide film. Since it does not contain oxygen as a component, it is not a source of oxygen. Therefore, providing the nitride film outside the near infrared light absorbing film 140 prevents the penetration of oxygen and moisture into the near infrared light absorbing film 140, and has an effect of suppressing deterioration of the near infrared light absorbing film 140. .

  In general, an optical filter has a large number of optical interfaces. On the other hand, the lens has an advanced antireflection film. It is difficult to achieve the same transmittance as a lens with an optical filter that cuts light in the near infrared region, and reflected light is returned to the lens side. This causes stray light that produces ghosts in the image. In the conventional camera structure, since the optical filter 60 is placed in the immediate vicinity of the image sensor 70 on the optical path between the lens unit 50 and the image sensor 70, it is difficult to avoid the ghost as described above. However, according to the camera structure according to the present embodiment, the stray light as described above is not generated, so that a remarkable effect of improving the image quality is obtained.

  Next, for reference, the spectral transmittance characteristics of the cover glass 100 with an integrated optical filter function having a near-infrared light reflection part and a near-infrared light absorption part will be described. Even when the functions of the cover glass 100 with an optical filter function are divided into, for example, a cover glass 215 with a near infrared light reflection function and an image sensor cover 244 with a near infrared light absorption function, which are separate bodies, the same effect is obtained. Is obtained.

  FIG. 2B shows an experimental result on how the spectral transmittance characteristics of the near-infrared light reflecting film formed of the dielectric film depend on the incident angle of light. The incident angle A is defined as shown in FIG. Further, “T” on the vertical axis represents spectral transmittance, and the unit is% (percent). “Λ” on the horizontal axis indicates the wavelength of light, and the unit is nm (nanometer) (the same applies to the following figures). The sample is obtained by alternately stacking 40 layers of titanium dioxide (TiO2) and silicon dioxide (SiO2) with a predetermined film thickness on glass. When the solid line indicates an incident angle of 0 °, the broken line indicates the spectral transmittance when the incident angle of light is 30 °. From FIG. 2 (B), it was confirmed that a significant spectral transmittance difference occurs at light incident angles of 0 degrees and 30 degrees with respect to light in the red region near a wavelength of 700 nm. If there is such a difference, the color tone of the image is greatly changed between the center and the peripheral portion of the image, which causes the final deterioration of the image quality.

  FIG. 3 shows an experiment on how the spectral transmittance of the cover glass 100 with an optical filter function including both a near-infrared light absorbing film and a near-infrared reflective film depends on the incident angle of light. Results are shown. As the near-infrared light absorbing film, a resin film containing an organic dye and having a thickness of 5 μm or less is used, and the near-infrared light reflecting film has the same configuration as in FIG. The solid line indicates the spectral transmittance when the incident angle of light is 0 degree, the broken line indicates the incident angle of light of 15 degrees, and the dashed line indicates the spectral transmittance when the incident angle of light is 30 degrees. It can be confirmed that the incident angle dependency is smaller than in the case of FIG.

  FIG. 4 shows a cover glass 100 with an optical filter function (solid line) provided with a near-infrared light absorbing film 140 and a near-infrared light reflecting film 150, and a cover glass (dashed line) on which only the near-infrared light absorbing film 140 is formed. It is the figure which compared the experimental result in the spectral transmittance measurement of the cover glass (one-dot chain line) which formed only the near-infrared-light reflection film 150. The configurations of the near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 are the same as those in FIGS. However, all incident angles of light are 0 degree. In the case of only the near-infrared light absorbing film 140, light having a wavelength of 650 to 750 nm is strongly absorbed, but light having a wavelength of 800 nm or more is almost transmitted. As described above, the human eye mainly has sensitivity to so-called visible light having a wavelength of 380 nm to 780 nm. Therefore, when the imaging element 70 is imaged to a region of 800 nm or more where sensitivity is obtained, the human eye as described above. Becomes an unnatural image. The near-infrared light reflection film 150 is designed to cut light having a wavelength of 700 nm or more, and a steep decrease in spectral transmittance is actually measured in the vicinity of 700 nm. The near-infrared light absorbing film 140 and the near-infrared light reflecting film 150 are combined to form a cover glass 100 with an optical filter function. As shown by the solid line in FIG. About 650 nm, it can confirm that the high transmittance | permeability is implement | achieved and the light of wavelength 700nm or more is cut.

  According to the camera structure according to the embodiment of the present invention, there is a degree of freedom in the place where the near infrared light reflecting unit is arranged and the place where the near infrared light absorbing unit is arranged. It becomes possible to arrange the image at the position, and there is a remarkable effect of improving the image quality.

  In some cases, light having a longer wavelength than light having a wavelength that is absorbed by the near-infrared light absorbing portion is transmitted. Therefore, when the near-infrared light absorbing part and the near-infrared light reflecting part are arranged in order from the light incident side, the light on the longer wavelength side than the light of the wavelength absorbed by the near-infrared light absorbing part is It becomes easy to enter into the module, and before reaching the near-infrared light reflection part that can cut light on the long wavelength side, it is reflected on the lens surface or the like and becomes stray light, which causes a drop in image quality.

  According to the camera structure of the embodiment of the present invention, the near-infrared light reflection unit and the near-infrared light absorption unit are arranged with the near-infrared light reflection unit, the near-infrared light absorption unit in order from the light incident side. Therefore, the effect of suppressing stray light on the long wavelength side is achieved.

  According to the camera structure of the embodiment of the present invention, the near-infrared light reflection unit includes a lens element that constitutes an optical lens group, and is disposed closer to the light incident side than the lens element. The distance from the near-infrared light reflection unit to the image sensor is larger than the position of the external light cut filter. The near-infrared light reflection unit may easily transmit light in the ultraviolet region when the incident angle of light deviates from the vertical in the axial direction. As the distance from the image sensor increases, the angle at which the image sensor is viewed from the near-infrared light reflection unit decreases, so extra light in the ultraviolet region that passes through the near-infrared light reflection unit and reaches the image sensor directly. There is an effect that it can be reduced.

  According to the camera structure according to the embodiment of the present invention, the transmittance of the near-infrared light absorber is often not dependent on the incident angle of light. Therefore, the near-infrared light absorption unit includes a lens element that constitutes an optical lens group in the camera structure, and is arranged closer to the image sensor than the lens element, so that the near-infrared light absorption unit attempts to enter the image sensor from various directions. There is a remarkable effect that stray light can be effectively suppressed.

  If dust that does not easily transmit light adheres to the image sensor, the image quality deteriorates. According to the camera structure of the embodiment of the present invention, the image sensor cover that covers at least a part of the image sensor as viewed from the light incident side is located between the optical lens group and the image sensor in a position close to the image sensor. Therefore, it is possible to reduce the dust that can adhere to the image sensor and to prevent the deterioration of the image quality.

  According to the camera structure of the embodiment of the present invention, there is an effect that it is possible to manufacture an image pickup device cover that is less deformed by a temperature change at a low cost.

  The image sensor cover is disposed at a position close to the image sensor between the optical lens group and the image sensor. Therefore, when the image sensor cover reflects light, it causes a significant deterioration in the image quality of the image acquired by the image sensor. According to the camera structure according to the embodiment of the present invention, the image pickup device cover includes an antireflection layer that prevents reflection of light in at least the visible region, thereby providing a remarkable effect that the image quality is improved.

  According to the camera structure according to the embodiment of the present invention, more incident light can be captured, and reflected light caused by the image sensor cover, in particular, reflected light from the image sensor itself is further captured by the image sensor cover. It is possible to prevent the light from being reflected back to the image sensor and to improve the image quality.

  According to the camera structure according to the embodiment of the present invention, since the image pickup device cover includes the near-infrared light absorbing portion, there are remarkable effects of reducing the number of parts and the number of steps in manufacturing the camera structure.

  According to the camera structure of the embodiment of the present invention, the near-infrared light absorbing portion has a near-infrared light absorbing film, and the near-infrared light absorbing film includes an organic dye that absorbs near-infrared light. Therefore, light in the near-infrared light region is suppressed without using the blue glass generally used as a filter material for absorbing light in the near-infrared region, with little dependency on the incident angle of light. There is an effect that it becomes possible.

  According to the camera structure of the embodiment of the present invention, since the cover glass has a near-infrared light reflecting film that reflects light, there is an effect that the near-infrared light from the outside does not enter the internal mechanism of the imaging device. sell. In addition, it is not necessary to place a member having a near-infrared light reflecting film in a region close to the imaging device, so that reflection of light incident on the internal mechanism of the imaging device can be suppressed, and stray light can be suppressed as a result. , Can reduce the cause of ghosts and flares.

  FIG. 5 is a diagram showing the spectral transmittance of the cover glass with an optical filter function included in the camera structure according to the second embodiment of the present invention. In this embodiment, a cover glass with a so-called dual-band optical filter function and a camera structure that can acquire images even at night are provided. The basic structure of the camera structure is the same as that of the first embodiment, but a cover with an optical filter function including a near infrared light absorbing film 140 and a near infrared light reflecting film 150 instead of the cover glass 215 with a near infrared light reflecting function. The glass 100 is disposed, and the image sensor cover 244 with a near infrared light absorption function is omitted (not shown).

  Moreover, the cover glass 215 with a near-infrared light reflecting function includes a near-infrared light reflecting film D in which the light transmittance is increased for a part of light in the near-infrared region. Since the film structure of the near-infrared light reflection film D is a known technique, the description thereof is omitted.

  When the near-infrared light absorbing film 140 indicated by the broken line in FIG. 5 and the near-infrared reflective film D having a higher light transmittance for a part of the light in the near-infrared region indicated by the one-dot chain line in FIG. As shown by the solid line, a dual band cover glass that transmits part of the light in the visible region and the light in the near infrared region can be realized. However, in FIG. 5, the spectral transmittance of the near-infrared light reflection film D and the dual-band cover glass represents a calculated value at a wavelength of 750 nm or more. According to the camera structure provided with such a dual band cover glass, a remarkable effect that the lane boundary line or the roadway outer line can be easily seen on the road at night can be obtained.

  FIG. 6A is a cross-sectional view of a camera structure applied to a mobile communication device A that is an imaging apparatus according to the third embodiment of the present invention. This camera structure includes a cover glass 215 with a near-infrared light reflecting function that reflects near-infrared light, a plate 217 with a near-infrared light absorbing function that absorbs near-infrared light, and an imaging using a transparent glass as a base material. An element cover 240 is provided. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  FIG. 6B is a structural diagram of a cover glass with a near infrared light reflecting function including a near infrared light reflecting portion. The cover glass 215 with a near-infrared light reflection function uses the crystallized glass 130 as a transparent substrate that transmits light, reflects the light in the ultraviolet region, and suppresses the reflection of the light in the visible region. Is formed on the light incident side with reference to the crystallized glass 130. An antifouling coating film 110 for preventing contamination from the outside is provided on the outermost side where light enters. On the light emission side, in order from the farthest side with respect to the crystallized glass 130, an antireflection film 120 that prevents reflection of light in at least the visible region, and a near infrared light reflection film that reflects light in the near infrared region 150 is formed.

  In addition, in the cover glass 215 with a near infrared light reflection function, the antireflection film 120 closest to the image sensor 70 may not be provided.

  FIG. 6C is a structural diagram of the plate 217 with a near infrared light absorption function. The plate 217 with a near infrared light absorption function includes a plurality of antireflection layers 230 that prevent reflection of light in at least the visible region, and further includes a near infrared light absorption film 140. The near-infrared light absorbing function-equipped plate 217 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 light incident side with reference to the transparent glass 220, and the antireflection layer 230 and the near-infrared light absorbing film are formed on the light emission side in order from the farthest side with respect to the transparent glass 220. 140 is provided.

  The plate 217 with a near infrared light absorption function is disposed on the inner structure side, that is, the lens unit 50 side from the cover glass 215 with a near infrared light reflection function.

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

  FIG. 6D is a structural diagram of an image sensor cover 240 using a transparent glass as a base material and including a plurality of antireflection layers 230 using the transparent glass 220 as a base material. The image sensor cover 240 includes antireflection layers 230 on both surfaces of the transparent glass 220.

  FIG. 6E shows a camera structure applied to the mobile communication device A which is an image pickup apparatus according to the third embodiment. The image pickup element cover 240 using a transparent glass as a base material and the transparent synthetic resin film 222 as a base material. This is a part of a modified example in which the imaging element cover 242 is replaced. That is, it is a structural diagram of the imaging element cover 242 using the transparent synthetic resin film 222 as a base material and the transparent synthetic resin film having a moth-eye structure that exhibits an antireflection function on both surfaces as a base material. The thickness of the image sensor cover 242 using the transparent synthetic resin film as a base material is 0.2 mm or less. The imaging element cover 242 having a transparent synthetic resin film as a base material includes a moth-eye structure 232 that prevents reflection of light in at least the visible region on both sides.

  The moth-eye structure does not reduce the reflection by using the interference effect as in the case of the dielectric multilayer film, but reduces the reflection by eliminating the interface where the refractive index changes rapidly. Specifically, a fine protrusion structure composed of a large number of fine protrusions having a height of about several hundred nm is formed on the surface, and the repetition period of the protrusions is related to the wavelength range in which the effect of reducing reflection appears. Since the moth-eye structure is a well-known technique, the description is omitted, but in the case of this modified embodiment, for example, a transparent acrylic resin is used as the transparent synthetic resin film 222, and the anti-reflection function is formed by forming the moth-eye structure by transfer or molding. Is realized.

  That is, a so-called moth-eye structure 232 formed of fine protrusions formed on the surface of the image sensor cover 242 using a transparent synthetic resin film as a base material prevents reflection of light over a wide band. The moth-eye structure 232 preferably has an antireflection function for light in the visible region, and preferably has an antireflection function for light in the ultraviolet region and light in the near infrared region.

  A synthetic resin film having a thickness of 100 μm or less can be easily produced. According to the camera structure of the embodiment of the present invention, there is an effect that a thin and inexpensive image sensor cover can be manufactured at low cost.

  According to the camera structure of the embodiment of the present invention, there is a remarkable effect that it is possible to provide a camera module that is thinner than the conventional one.

  An antireflection layer having a fine protrusion structure formed of fine protrusions formed on the surface of the image sensor cover, that is, a so-called moth-eye structure, prevents reflection of light over a wide band. Therefore, according to the camera structure of the embodiment of the present invention, by forming the antireflection layer having the moth-eye structure, the reflected light due to the image sensor cover can be significantly reduced over a wide band, and the image quality can be improved. Has an effect.

Further, as another modified example of the image pickup device cover 240, a multilayer film obtained by applying a synthetic resin as an antireflection layer on the surface of the transparent synthetic resin film 222 as a base material may be considered. . In general, a multilayer film obtained by alternately laminating two kinds of thin films having different light refractive indexes,
An antireflection film for light can be formed. It is known that such a multilayer film can also be obtained by applying a synthetic resin.

For example, two types of synthetic resins having different refractive indexes 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, a low-cost and stable quality antireflection film was provided.
The image sensor cover 240 can be manufactured. As a method of applying the synthetic resin to the transparent synthetic resin film 222, for example, a roller coating method can be considered.
According to this modified embodiment, there is a remarkable effect that the image pickup device cover provided with the antireflection film can be manufactured in a large quantity and at a low cost with a stable quality.

  FIG. 7A is a cross-sectional view of a camera structure applied to a mobile communication device A that is an imaging apparatus according to a fourth embodiment of the present invention. The camera structure includes a cover glass 215 with a near infrared light reflection function and a camera module 1. The camera module 1 includes a lens unit 50, a lens carrier 40 that holds the lens unit 50, an image sensor 70, and an image sensor cover 240. Since the structures of the cover glass 215 with a near infrared light reflection function and the image sensor cover 240 are the same as those described in the third embodiment, a description thereof will be omitted. Moreover, since the manufacturing method of the near-infrared reflective film 150 and the antireflection film 120 is the same as that of the first embodiment, the description is omitted.

  FIG. 7B is a cross-sectional view of a lens unit including a lens element provided with a near infrared light absorber. The lens unit 50, that is, the optical lens group is composed of a plurality of lens elements. The lens element arranged closest to the image sensor 70 in the optical lens group is a lens element 250 including a near-infrared light absorber. The near-infrared light absorbing portion is an organic dye and is uniformly contained in the synthetic resin that forms the lens element 250 including the near-infrared light absorbing portion.

  FIG. 7C is a cross-sectional view of a lens unit including a lens element provided with a near infrared light absorber. 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 closest to the image sensor 70. The method for producing the near-infrared light absorbing film 140 is the same as that described in the first embodiment, and is therefore omitted.

  An antireflection layer 230 may be provided further on the imaging element 70 side of the near infrared light absorption film 140.

  According to the embodiment of the present invention, since the near-infrared light reflecting portion that reflects light is provided, an effect of preventing near-infrared light from the outside from entering the internal mechanism of the imaging apparatus can be achieved. In addition, since it is not necessary to place a member having a near infrared light reflecting portion in a region close to the imaging element, reflection of light incident on the internal mechanism of the imaging device can be suppressed, and stray light can be suppressed as a result. , Can reduce the cause of ghosts and flares.

  According to the embodiment of the present invention, since the near-infrared light absorbing portion includes an organic dye that absorbs near-infrared light, blue glass generally used as a filter material for absorbing light in the near-infrared region. Without using the light, it is possible to suppress light in the near-infrared light region in a state with little dependency on the incident angle of light.

  FIG. 8A is a cross-sectional view of a camera structure applied to an imaging apparatus according to the fifth embodiment of the present invention. The camera module 1 having the camera structure includes a lens unit 50, a lens carrier 40 that holds the lens unit 50, and an imaging device 70, and is fixed to the vehicle body 22. That is, the camera structure is a so-called in-vehicle camera structure.

  FIG. 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 reflection film 150 is provided on the light incident side surface of the lens element 270 provided with the near-infrared light reflection portion. In the lens element 250 provided with the near infrared light absorbing part, the near infrared light absorbing part is an organic dye and is uniformly contained in the synthetic resin forming the lens element 250 provided with the near infrared light absorbing part. As a modified example, the lens element 250 including the near-infrared light absorbing portion may be a transparent lens element 255 provided with the near-infrared light absorbing film 140 closest to the imaging element 70 (FIG. 7C). reference). In the present embodiment, since a mechanically moving member such as an actuator is not included, dust is hardly generated. Further, since the surface of the image sensor 70 is substantially perpendicular to the ground, dust hardly adheres to the image sensor 70. Therefore, the image sensor cover 240 is omitted. A cover glass for preventing dirt may be provided on the light incident side of the lens unit 50. Of course, the image sensor cover 240 may be provided close to the image sensor 70.

  With such a structure, the number of parts can be reduced, and the production process can be remarkably omitted, so that it can be manufactured at low cost. Of course, since it has a near-infrared light reflection part and a near-infrared light absorption part, there also exists an effect of an improvement in image quality.

  As a modified example, the lens element 270 provided with the near-infrared light reflecting portion in the camera structure is left as it is, and the image sensor cover is provided with the near-infrared light absorption function shown in FIG. 1C of the first embodiment. By using the image sensor cover 244, it is also conceivable that the lens element does not have a light absorption function in the near infrared region.

  FIG. 9A is a cross-sectional view of a camera structure applied to an imaging apparatus according to the sixth embodiment of the present invention. The camera structure includes a cover glass 215 with a near infrared light reflection function and a camera module 1. The camera module 1 includes a lens unit 50, a lens carrier 40 that holds the lens unit 50, an image sensor 70, and an image sensor cover 240. Since the structures of the cover glass 215 with a near infrared light reflection function and the image sensor cover 240 are the same as those described in the third embodiment, a description thereof will be omitted.

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

  FIG. 9C is a structural diagram of an optical element 500 with a near infrared light absorption function. The optical element 500 with a near infrared light absorption function includes a plurality of antireflection layers 230 that prevent reflection of light in at least the visible region, and further includes a near infrared light absorption film 140. The near-infrared light absorbing function-equipped plate 217 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 light incident side with reference to the transparent glass 220, and the antireflection layer 230 and the near-infrared light absorbing film are formed on the light emission side in order from the farthest side with respect to the transparent glass 220. 140 is provided.

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

  In addition, since the manufacturing method of the near-infrared reflective film 150, the antireflection film 120, and the near-infrared light absorption film 140 is the same as that of the first embodiment, description thereof is omitted.

  FIG. 10A is a cross-sectional view of a camera structure applied to an imaging apparatus according to the seventh embodiment of the present invention. The 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 that holds the lens unit 50, an image sensor 70, and an image sensor cover 240. Since the structure of the image sensor cover 240 is the same as that described in the third embodiment, a description thereof will be omitted.

  The cover glass 550 may use conventional tempered glass or sapphire glass as a base material. Of course, crystallized glass may be used. The cover glass 550 has an antireflection film 120 that reflects light in the ultraviolet region and suppresses reflection of light in the visible region (not shown) on the surface of the imaging device 70 side.

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

  FIG. 10C is a structural diagram of the optical element 530 with an optical filter function. The optical element 530 with an optical filter function includes a plurality of antireflection layers 230 that prevent reflection of light in at least the visible region, and further includes a near infrared light absorption film 140. The optical element with optical filter function 530 uses 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 light incident side with respect to the transparent glass 220, and the antireflection layer 230 and the near-infrared light reflection film are formed on the light emission side in order from the farthest side with respect to the transparent glass 220. 150 and a near-infrared light absorbing film 140 are provided.

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

  According to the camera structure, it is only necessary to add the optical element with an optical filter function 530 to the lens unit 50, and other components can be used in the conventional configuration. In addition, since the optical lens group includes an integrated optical element that includes the near-infrared light reflection part and the near-infrared light absorption part at the same time, it is necessary to insert a member having a near-infrared light reflection film in the immediate vicinity of the imaging element Disappears. Therefore, reflection of light incident on the internal mechanism of the imaging apparatus can be suppressed, and as a result, stray light can be suppressed and the cause of ghost and flare can be reduced.

  As a result of further diligent research conducted by the inventors, it has been found that there is another problem in the conventional camera structure that a difference in color occurs between the central portion and the peripheral portion of the acquired image. This problem is particularly noticeable when the incident angle of incident light can be increased in an embodiment in which the near-infrared reflecting portion is provided on the cover glass.

  FIG. 12A shows the incident light angle dependence of the spectral characteristics of the light transmittance in the near-infrared light absorbing section using the conventional light-absorbing ink and the spectral characteristics of the light transmittance in the near-infrared light reflecting section. It is a graph to show. The vertical axis represents the light transmittance T (unit:%), and the horizontal axis represents the wavelength of incident light (unit: nm). Specifically, an image sensor cover 244 with a near infrared light absorption function having a near infrared light absorption film 140 as a near infrared light absorption part (see FIG. 1C) and a near infrared light reflection part as a near infrared light absorption part. Consider an optical system including a cover glass 215 with a near-infrared light reflection function, which has an infrared light reflection film 150 (see FIG. 1B).

  In FIG. 12A, a solid line A1 indicates the spectral characteristic of the light transmittance of the image sensor cover 244 with a near infrared light absorption function alone. The dotted line R1 indicates the spectral characteristic of the light transmittance of the single cover glass 215 with a near infrared light reflection function when the incident angle of incident light is 0 °, and the broken line R2 indicates when the incident angle of incident light is 30 °. The spectral characteristic of the light transmittance in the cover glass 215 single-piece | unit with a near-infrared-light reflection function is shown. A curve A1 indicating the spectral characteristics of the conventional near-infrared light absorbing ink and a broken line R2 indicating the spectral characteristics of the conventional near-infrared reflecting portion at an incident angle of 30 ° are 660 to 700 nm as the light wavelength region. 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 when the incident angle is 0 ° are substantially overlapped. There is no overlap.

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

  Here, the wavelength at which the light transmittance decreases to 10% when the wavelength of incident light is increased is defined as the near infrared light cutoff wavelength. Considering a near-infrared light cut filter having a near-infrared light reflection part and a near-infrared absorption part, 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 °. The dependence variation width may be about 30 nm. In other words, the light transmittance of the near-infrared light cut filter varies greatly depending on the incident angle of incident light at a predetermined light wavelength in the near-infrared light region. Specifically, for example, if light having 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 the incident angle at the peripheral portion of the acquired image. When the value is large, the phenomenon that the light transmittance becomes almost 0% occurs. As a result, the light wavelength dependency of the transmittance differs between the peripheral portion and the central portion of the acquired image, and so-called “red-out” image quality is obtained. Deterioration phenomenon occurs.

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

  FIG. 13A shows the spectral characteristics of the light transmittance in the near-infrared light absorbing section using the new light-absorbing ink and the dependence of the spectral characteristics of the light transmittance in the new near-infrared light reflecting section on the incident light angle. It is a graph which shows sex. The vertical axis represents the light transmittance T (unit:%), and the horizontal axis represents the wavelength of incident light (unit: nm). Specifically, an image sensor cover 244 with a near infrared light absorption function having a near infrared light absorption film 140 as a near infrared light absorption part (see FIG. 1C) and a near infrared light reflection part as a near infrared light absorption part. Consider an optical system including a cover glass 215 with a near-infrared light reflection function, which has an infrared light reflection film 150 (see FIG. 1B).

  In FIG. 13A, a solid line A2 indicates the spectral characteristics of the light transmittance of the image sensor cover 244 with a near infrared light absorption function alone. A dotted line R3 indicates the spectral characteristic of light transmittance in the cover glass 215 with near infrared light reflection function when the incident angle of incident light is 0 °, and a broken line R4 indicates when the incident angle of incident light is 30 °. The spectral characteristic of the light transmittance in the cover glass 215 single-piece | unit with a near-infrared-light reflection function is shown.

  Specifically, the camera structure according to the eighth embodiment of the present invention includes a near-infrared light absorbing unit 140 that absorbs light in the near-infrared region and a near-infrared light that reflects light in the near-infrared region. The near-infrared light absorption unit 140 includes a light absorption wavelength region 700 having a light transmittance of less than 2% in a region of 685 nm to 755 nm as a wavelength of light. When a wavelength at which the light transmittance is reduced to 50% as the wavelength of incident light on the light reflecting portion 150 increases is defined as a near infrared light cutoff wavelength, the near infrared light reflecting portion 150 is defined. Has a characteristic of substantially totally reflecting light having a wavelength longer than the near-infrared light cutoff wavelength, and the incident angle of the incident light to the near-infrared light reflecting portion 150 is changed in the range of 0 ° to 30 °. In some cases, the near-infrared light cutoff wavelength is always included in the light absorption wavelength region 700.

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

In addition, as a spectral characteristic with respect to light having a wavelength longer than the near-infrared light cutoff wavelength in the near-infrared light reflection unit 150, a light transmittance of less than 1% at about 750 nm to 1000 nm is desirable.
In a wavelength range longer than about 1000 nm, there may be some light transmittance of, for example, several percent.

  FIG. 13B is a graph showing the incident light angle dependence of the spectral characteristics of 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 broken line C4 is the spectral characteristic when the incident angle is 30 °. In other words, the spectral characteristic of the optical system combining the solid line A2 and the dotted line R3 in FIG. 13A is the dotted line C3, and the spectral characteristic of the optical system combining the solid line A2 and the broken line R4 in FIG. is there.

  Here, the wavelength at which the light transmittance decreases to 10% when the wavelength of incident light is increased is defined as the near infrared light cutoff wavelength.

  Considering a near-infrared light cut filter having a near-infrared light reflection unit 150 and a near-infrared absorption unit 140, the near-infrared light cutoff wavelength when the incident angle of incident light is changed in the range of 0 ° to 30 °. The angle-dependent change width 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 incident light.

  When the near-infrared light cut filter includes, for example, the near-infrared light reflection unit 150 including a dielectric multilayer film, the frequency dependency of the light transmittance in the near-infrared light reflection unit 150 depends on the incident angle of incident light. Change. That is, for example, the near-infrared light blocking wavelength of the near-infrared light reflecting portion 150 is about 700 nm when the incident angle of incident light is 0 °, but becomes about 675 nm when the incident angle of incident light becomes 30 °. Such an incident angle dependency may occur. Then, assuming that the near-infrared light cut filter has the near-infrared light absorption unit 140, the light transmittance realized in combination with the near-infrared light reflection unit 150 may greatly change depending on the incident angle of incident light. possible. Specifically, the near-infrared light cut filter including the near-infrared light reflection unit 150 and the near-infrared absorption unit 140 is a near-infrared when the incident angle of incident light is changed in the range of 0 ° to 30 °. The angle-dependent change width of the light blocking wavelength can be about 30 nm. In other words, the light transmittance of the near-infrared light cut filter varies greatly depending on the incident angle of incident light at a predetermined light wavelength in the near-infrared light region. For example, if light having 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 light is transmitted when the incident angle is large at the peripheral portion of the acquired image. As a result, a phenomenon that the rate becomes approximately 0% occurs, and as a result, the light wavelength dependency of the transmittance differs between the peripheral portion and the central portion of the acquired image, and so-called “red-out” image quality deterioration phenomenon occurs.

  According to the camera structure of the eighth embodiment of the present invention, in the near-infrared light cut filter, the angle dependency of the near-infrared light cutoff wavelength when the incident angle of incident light is changed in the range of 0 ° to 30 °. Since the change width is 5 nm or less, a difference in color expression in the acquired image hardly occurs, and an excellent effect of improving the image quality is obtained.

  As an effect of combining the near-infrared light absorption unit 140 and the near-infrared light reflection unit 150, an acquired image is affected when the light transmittance at a predetermined wavelength is 1% or more. Therefore, as the spectral characteristics 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 visually invisible. It will be different from the color you saw. Further, when the near-infrared light reflecting portion 150 is formed of, for example, a dielectric multilayer film, the light transmittance changes depending on the incident angle of incident light, so the transmittance depends on the light wavelength at the peripheral portion and the central portion of the acquired image. The so-called “red-out” image quality deterioration phenomenon occurs.

  According to the camera structure of the eighth embodiment of the present invention, the light transmittance is 1% in the light wavelength region of 685 nm to 755 nm as the combined effect of the near infrared light absorbing unit 140 and the near infrared light reflecting unit 150. Therefore, the excellent effect of reducing the difference between the image quality of the acquired image and what is seen with the naked eye is also achieved. Further, 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 cutoff wavelength of the near-infrared light reflecting unit 150 is always the light transmittance. Is less than 2% in the light absorption wavelength region 700, so that the incident angle dependence of the spectral characteristics with respect to the light in the near infrared region is reduced, and the light wavelengths that can be acquired at the peripheral portion and the central portion of the acquired image do not change. Therefore, an excellent effect of improving the image quality is achieved.

  FIG. 14A is a cross-sectional view of a camera structure applied to a mobile communication device A that is 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 or a portable communication device A. The camera structure includes a cover glass 400 with an optical filter function and a camera module 501 housed in a housing 520 of a mobile communication device A such as a smartphone from the light incident side. The camera module 501 includes a lens unit 450 that is an optical lens group disposed on the cover glass 400 with an optical filter function, and an image sensor 570 that receives light incident through the cover glass 400 with the optical filter function and the lens unit 450. And a near-infrared light cut filter that cuts light in the near-infrared region is not disposed between the optical paths from the lens unit 450 to the image sensor 570. Specifically, as shown in FIG. 14A, a cover glass 400 with an optical filter function, a lens unit 450, a lens carrier 540, and a magnet holder 430. The image sensor 570 and the substrate 580 are mainly configured to be fixed to the smartphone housing 520. The connection between the image sensor 570 and the substrate 580 may be connected by wire bonding or may be flip-chip mounted.

  A significant difference from the conventional camera structure of FIG. 11A is that the optical filter 60 (see FIG. 11A) that cuts near-infrared light, which has conventionally been necessary for improving image quality, is omitted. . Instead, a filter function for cutting light in the near-infrared region has been added to the cover glass 10 that has been mainly responsible for protecting the camera module 1 conventionally. By adopting such a structure, the length of the entire camera structure can be made shorter than before, and the optical filter 60 is not disposed in the vicinity of the image sensor 70. There is a remarkable effect that the granular dust (particles) adhering to the surface of the image sensor does not fall on the surface of the image sensor 70 and deteriorate the image. Further, in the assembly process of the camera module 1, a process for arranging and assembling the near-infrared light cut filter 60 is not necessary, which contributes to further cost reduction, yield improvement, and work efficiency.

  In addition, by providing the camera structure of FIG. 14A, the mobile communication device A can be manufactured more compactly, thinner, and more inexpensively.

  FIG. 14B shows a laminated structure of a cover glass 400 with an optical filter function that is continuously installed in the casing of the mobile communication device A and protects the camera module as an internal mechanism from the outside. The cover glass 400 with an optical filter function 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 has a crystal structure. It is formed on the light incident side with respect to the vitrified glass 630. Further, an antifouling coating film 610 for preventing contamination from the outside is provided on the outermost side where light enters. A near-infrared light reflecting film 650 as a near-infrared reflecting portion that reflects light in the near-infrared region in order from the farthest side with respect to the crystallized glass 630 on the light emission side, and light in the near-infrared region And a near-infrared light absorbing film 640 as a near-infrared light absorbing portion that absorbs light. An antireflection film 620 may be further formed on the farthest side of the light emission side.

  In general, crystallized glass is difficult to transmit light because of its large crystal grains. However, recent advances in technology have made it possible to control crystal particles to a nanometer size, such as impact-resistant and high-hardness clear glass ceramics manufactured by OHARA, Inc., thereby increasing light transmittance. By using such crystallized glass, it is possible to produce a cover glass having both impact resistance and fracture toughness in which cracks do not easily occur. And the cover glass 400 with an optical filter function is implement | achieved by forming said laminated structure in such a cover glass. Although it is theoretically possible to use blue glass as the cover glass 400 with an optical filter function, it is not suitable because it has low impact resistance and lacks fracture toughness that is difficult to crack. It is conceivable to form a near-infrared light absorbing film 640 or a near-infrared light reflecting film 650, which will be described later, on the tempered glass to form the cover glass 400 with an optical filter function, but compared with the case where the crystallized glass 630 is used. And has the disadvantage of low impact resistance. Further, it is conceivable to form a near-infrared light absorbing film 640 and a near-infrared light reflecting film 650 on sapphire glass having a high hardness to form a cover glass 400 with an optical filter function. Workability is low compared to the case of using the vitrified glass 630.

  The antifouling coating film 610 prevents fingerprint stains and sebum stains and facilitates wiping off the stains. The antifouling coating film 610 is formed of a fluorine-based coating agent or the like, and is formed on the outermost side on the light incident side in the cover glass laminated structure by coating or spraying.

  The antireflection film 620 reflects light in the ultraviolet region and suppresses reflection of light in the visible region. The antireflection film 620 is a dielectric multilayer film, and is configured by alternately stacking nitride films and oxide films. 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. When silicon oxynitride is used, the stoichiometric ratio of oxygen to nitrogen (oxygen / nitrogen) is preferably 1 or less. As the oxide film, silicon oxide (SiO 2), aluminum oxide (Al 2 O 3), 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 described later. Process advantageous.

  As the antireflection film 620, an oxide film can be used instead of the nitride film. As a material for such an oxide film, in addition to silicon oxide, titanium oxide (TiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), or the like may be used. it can. In the case where the antireflection film 120 is composed of a plurality of types of oxide films having different refractive indexes, an appropriate selection is made from the oxides.

  For the antireflection film 620, a known film formation method such as a vacuum deposition method, a sputtering method, an ion beam assisted deposition method (IAD method), an ion plating method (IP method), an ion beam sputtering method (IBS method), or the like is used. be able to. It is desirable to use a sputtering method or an ion beam sputtering method for forming the nitride film.

  The near-infrared light absorbing film 640 is formed on the surface of the crystallized glass 630 opposite to the above-described antireflection film 620, that is, on the image sensor 570 side of the cover glass 400 with an optical filter function (see FIG. 14A). Is done. The near-infrared light absorption film 640 has a function of transmitting light in the visible region and absorbing part of light from the red region to the near-infrared region. The near-infrared light absorbing film 640 includes an organic dye and is formed of a resin film having a maximum absorption wavelength in the range of 700 nm to 750 nm (see solid line A2 in FIG. 13A). Since the near-infrared light absorbing film 640 is adjacent to the crystallized glass 630, it is desirable to reduce the difference in refractive index between the two to reduce the reflectance at the interface. By having such a near-infrared light absorbing film 640, it is possible to reduce the dependency of the spectral transmittance characteristics depending on the incident angle and to have excellent near-infrared light cut-off properties.

  As the organic dye, an azo compound, a phthalocyanine compound, a cyanine compound, a diimonium compound, or the like can be used. Polyacryl, polyester, polycarbonate, polystyrene, polyolefin, or the like can be used as a resin material as a binder (pigment binder) 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. The resin material may be any material that has a high transmittance with respect to light in the visible region, and is selected in consideration of compatibility with an organic dye, a film formation process, cost, and the like. Further, in order to improve the ultraviolet resistance of the near-infrared light absorbing film 640, a quencher (quenching dye) such as a sulfur compound may be added to the resin material.

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

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

  In the near-infrared light reflection film 650, each oxide film is formed with a thickness of λ / 4, where λ is the wavelength of light to be reflected. By doing this, the light reflected from all the interfaces of the alternating layers will be in the same phase when reaching the incident surface, and the light will be intensified, that is, the reflectance will increase near the wavelength λ, and as a light reflecting film Function. In the present embodiment, the film may be designed so that λ reflects light in the near infrared region. Note that the near-infrared light reflection film 650 is also formed using the same film formation method and apparatus as those of the antireflection film 620 described above.

  The human eye is sensitive to so-called visible light having a wavelength of 380 nm to 780 nm. On the other hand, the image sensor generally has sensitivity up to light having a longer wavelength, that is, light having a wavelength of about 1.1 μm, including visible light. Therefore, if the image captured by the image sensor is used as it is as a photograph, it does not look natural and causes a sense of discomfort.

  When the cover glass 400 with an optical filter function has a laminated structure as shown in FIG. 14B, the near-infrared light absorbing film 640 cannot absorb the near-infrared light absorbing film 640 because the near-infrared light reflecting film 650 made of a dielectric multilayer film is provided. It is possible to obtain an image having a natural color by cutting light having a wavelength of 700 nm or longer.

  The light wavelength dependency of the light transmittance of the near-infrared light reflection film 650 is shown in FIG. Specifically, the dotted line R3 indicates the spectral characteristic of the light transmittance of the single near-infrared light reflecting film 650 when the incident angle of incident light is 0 °, and the broken line R4 indicates that the incident angle of incident light is 30 °. The spectral characteristic of the light transmittance in the near-infrared-light reflective film 650 simple substance at the time of is shown.

In this embodiment, when the wavelength at which the light transmittance decreases to 50% as the wavelength of incident light on the near-infrared light reflecting film 650 increases is defined as the near-infrared light cutoff wavelength. ,
Even if the incident angle of the incident light to the near-infrared light reflection unit 650 is changed in the range of 0 ° to 30 °, the near-infrared light cutoff wavelength of the near-infrared light reflection unit 650 always has a light transmittance. Since the light absorption wavelength region 700 is less than 2%, the incident angle dependency of the spectral characteristics with respect to light in the near infrared region is reduced, and the light wavelength that can be acquired at the peripheral portion and the central portion of the acquired image does not change. There is an excellent effect that the image quality is improved.

  That is, by combining the near-infrared light reflection film 650 and the near-infrared light absorption film 640 that does not depend on the incident angle with respect to the light absorption rate, the light transmittance is less dependent on the incident angle of light. A near-infrared light cut filter can be configured (see FIG. 13B).

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

  The antireflection film 620 is configured by alternately laminating nitride films and oxide films. Generally, a nitride film has a higher hardness than an oxide film, and reaches a hardness of 9H or more in a pencil hardness test. Therefore, the antireflection film 120 including the nitride film has an effect of improving scratch resistance. Further, the nitride film is denser and denser than the oxide film. Since it does not contain oxygen as a component, it is not a source of oxygen. Therefore, by providing the nitride film outside the near infrared light absorption film 640, it is possible to prevent oxygen and moisture from entering the near infrared light absorption film 640 and to suppress deterioration of the near infrared light absorption film 640. .

  In general, an optical filter has a large number of optical interfaces. On the other hand, the lens has an advanced antireflection film. It is difficult to achieve the same transmittance as a lens with an optical filter that cuts light in the near infrared region, and reflected light is returned to the lens side. This causes stray light that produces ghosts in the image. In the conventional camera structure, since the optical filter 60 is placed in the immediate vicinity of the image sensor 70 on the optical path between the lens unit 50 and the image sensor 70, it is difficult to avoid the ghost as described above ( (See FIG. 11A). However, according to the camera structure according to the present embodiment, the stray light as described above is not generated, so that a remarkable effect of improving the image quality is obtained.

  According to the ninth embodiment of the present invention, there is a remarkable effect that an image pickup apparatus equipped with a camera structure with improved image quality than before can be realized at low cost.

  It should be noted that the camera structure and the imaging apparatus according to the embodiment of the present invention are not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

1 Camera module
DESCRIPTION OF SYMBOLS 10 Cover glass 20 Smartphone housing | casing 22 Car body 30 Magnet holder 40 Lens carrier 50 Lens unit 60 Optical filter 70 Image sensor 80 Substrate 100 Cover glass with an optical filter function 110 Antifouling coating film 120 Antireflection film 130 Crystallized glass 140 Near infrared Light absorbing film 150 Near infrared light reflecting film 160 Incident surface 170 Outgoing surface 180 Measuring object 190 Incident light 200 Vertical axis 210 Cover glass with optical filter function 215 Cover glass with near infrared light reflecting function 217 With near infrared light absorbing function Plate 220 Transparent glass 222 Transparent synthetic resin film 230 Antireflection layer 232 Mosaic structure 240 Image sensor cover 242 Image sensor cover based on transparent synthetic resin film 244 Image sensor cover with near infrared light absorption function 250 Lens element provided with near infrared light absorbing portion 255 Transparent lens element 270 Lens element provided with near infrared light reflecting portion 300 Light source 310 High reflective material 320 Low reflective material 360 Transparent glass 370 Antireflection film 380 Blue glass 390 Near red External light reflection film 400 Cover glass with optical filter function 430 Magnet holder 450 Lens unit 500 Optical element with near infrared light absorption function 501 Camera module 520 Smartphone case 530 Optical element with optical filter function 540 Lens carrier 550 Cover glass 570 Imaging element 580 Substrate 610 Antifouling coating film 620 Antireflection film 630 Crystallized glass 640 Near infrared light absorption film (near infrared light absorption part)
650 Near-infrared light reflection film (near-infrared light reflection part)
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 Light Absorbing Ink C1 Spectral Characteristics When Incident Angle is 0 ° C2 When Incident Angle is 30 ° Spectral characteristics C3 Spectral characteristics when the incident angle is 0 ° C4 Spectral characteristics when the incident angle is 30 ° G Ghost R1 Spectral characteristics of the conventional near-infrared reflector when the incident angle is 0 ° R2 When the incident angle is 30 ° Spectral characteristics of conventional near-infrared reflector R3 Spectral characteristics of new near-infrared reflector R0 when the incident angle is 0 ° R4 Spectral characteristics of new near-infrared reflector when the incident angle is 30 °

Claims (15)

A camera structure for imaging,
An optical lens group arranged on the light incident side;
An image sensor for receiving light incident through the optical lens group;
In the camera structure, wherein formed on the optical lens optical arranged Ru cover glass on the incident side than the group, the light in the ultraviolet region, and the light reflection to reflect light in the near infrared region including a range of 750nm to 1000nm And
In the camera structure, a near-infrared light absorbing portion that is disposed closer to the image sensor than the optical lens group and absorbs light in a near-infrared region,
With
The light reflection unit, the optical lens group, and the near infrared light absorption unit are arranged separately from the light incident side, the light reflection unit, the optical lens group, and the near infrared light absorption unit. Provided,
There is no other light reflecting portion that reflects light in the ultraviolet region and light in the near infrared region including the range of 750 nm to 1000 nm between the optical paths from the near infrared light absorbing portion to the imaging device. And camera structure. The near-infrared light absorbing portion has a light absorption wavelength region in which light transmittance is less than 2% in a region of 685 nm to 755 nm as a wavelength of light,
The light reflecting portion substantially totally reflects light having a wavelength longer than the near-infrared light cutoff wavelength when a wavelength at which light transmittance is reduced to 50% is defined as a near-infrared light cutoff wavelength. Has characteristics,
The near-infrared light cutoff wavelength is always included in the light absorption wavelength region when an incident angle of incident light to the light reflecting portion is changed in a range of 0 ° to 30 °. The camera structure according to claim 1 . The near-infrared light absorbing portion has a light absorption wavelength region in which light transmittance is less than 2% in a region of 685 nm to 755 nm as a wavelength of light,
The light reflecting portion substantially totally reflects light having a wavelength longer than the near-infrared light cutoff wavelength when a wavelength at which light transmittance is reduced to 50% is defined as a near-infrared light cutoff wavelength. Has characteristics,
When the incident angle of the incident light to the light reflecting portion is changed in a range of 0 ° to 30 °, the near infrared light cutoff wavelength is always included in the light absorption wavelength region , 2. The camera structure according to claim 1 , wherein an angle-dependent change width between the light reflecting portion and the near infrared light absorbing portion is 5 nm or less . The camera structure according to claim 1, wherein the cover glass is directly fixed to a casing of a portable communication device.   5. The image sensor cover according to claim 1, further comprising an image sensor cover that is disposed between the optical lens group and the image sensor and covers at least a part of the image sensor as viewed from a light incident side. The camera structure as described in any one of them.   The camera structure according to claim 5, wherein the imaging element cover includes the near infrared light absorbing portion.   The said near-infrared light absorption part is a near-infrared light absorption film | membrane which absorbs the light of a near-infrared area | region, and contains an organic pigment | dye, It is any one of Claims 1-6 characterized by the above-mentioned. The camera structure described.   The camera structure according to claim 5, wherein the image sensor cover is made of glass.   The camera structure according to claim 5, wherein the image sensor cover is a synthetic resin film.   The camera structure according to claim 5, wherein a thickness of the image sensor cover is 0.2 mm or less.   11. The camera structure according to claim 5, wherein the imaging element cover includes an antireflection layer that prevents reflection of light in at least a visible region.   The camera structure according to claim 11, further comprising an antireflection layer for preventing reflection of light in at least a visible region on both surfaces of the image sensor cover.   The camera structure according to claim 11, wherein the antireflection layer has a fine protrusion structure including a fine protrusion formed on a surface of the image sensor cover.   The camera structure according to claim 11, wherein the antireflection layer is a coating film formed on a surface of the image sensor cover. Imaging apparatus characterized by having a camera structure as claimed in any one of claims 14.

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