JP2017138563A - Optical element and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element effective for sensing a human body.SOLUTION: There is provided an optical element 3 comprising: a lens 31 that includes an incident surface and an emission surface; and an antireflection film 32 that is provided on at least one of the incident surface and emission surface of the lens 31, where the transmittance of light transmitting through the lens 31 and antireflection film 32 has one peak within a wavelength range of 8 to 12 μm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical element including a lens and an antireflection film, and an imaging apparatus.

  2. Description of the Related Art An imaging device having an imaging element and a condensing lens is used in an imaging device for a moving body such as a vehicle driving support camera. External light reaches the image sensor through the lens and is imaged. The imaging device in this case is set on the vehicle body so as to face forward as viewed from the vehicle, for example. A pedestrian or the like is detected from an image obtained by the imaging device, and driving assistance such as automatic braking is performed.

  In general, an antireflection film is provided on a lens in order to improve light transmittance. Since it is necessary to accurately detect an object such as a pedestrian from various objects existing in front of the vehicle, the antireflection film can increase the light transmittance to the image sensor in a wide wavelength band. Things are used.

JP 2001-108758

  In recent years, in an imaging device for driving assistance of a vehicle, it has been required to increase the detection sensitivity of a person (human body) such as a pedestrian. On the other hand, in a conventional imaging device and an imaging apparatus using the same, an object other than a human body is imaged with the same level of sensitivity as a human body, so that it is difficult to effectively detect a pedestrian or the like.

  An optical element according to one aspect of the present invention includes a lens having an entrance surface and an exit surface, and an antireflection film provided on at least one of the entrance surface and the exit surface of the lens, The transmittance of light transmitted through the antireflection film has one peak in the light wavelength range of 8 to 12 μm.

  An image pickup apparatus according to one aspect of the present invention includes the optical element having the above-described configuration and an image pickup element disposed on the exit surface side of the lens and away from the lens.

  According to the optical element of one aspect of the present invention, since the light transmittance is relatively large at a wavelength corresponding to the temperature of the human body, the human body is effectively distinguished from other objects. Can be sensed. Therefore, it is possible to provide an optical element that makes it easy to produce an imaging device effective for sensing a human body (such as a pedestrian).

  According to the imaging apparatus according to one aspect of the present invention, since the optical element having the above-described configuration is included, an imaging apparatus effective for sensing a human body (pedestrian or the like) can be provided.

It is sectional drawing which shows the optical element and imaging device of embodiment of this invention. It is sectional drawing which expands and shows the A section of FIG. It is an overhead view which shows typically the situation where the imaging device of an embodiment of the present invention is used in a mobile object. It is an example of the detection image by the imaging device in the situation shown in FIG. It is a graph which shows an example of the transmittance | permeability of the antireflection film which the optical element of embodiment of this invention has. It is a graph which shows an example of the transmittance | permeability of the lens which the optical element of embodiment of this invention has. It is an example of the transmittance | permeability of the optical element of embodiment of this invention. It is a graph which shows an example of the light received with an image sensor in the imaging device of an embodiment of the present invention. (A) is a top view which shows an example of the image pick-up element periphery of the imaging device shown in FIG. 1, (b) is sectional drawing in the AA of (a), (c) is B of (a). It is sectional drawing in the -B line. It is the graph which showed the spherical aberration in case a lens is a spherical lens. (A) is a top view which shows the other example of the image pick-up element periphery in the imaging device of embodiment of this invention, (b) is sectional drawing in the AA of (a), (c) is ( It is sectional drawing in the BB line of a). (A) is a top view which shows the other example of the image pick-up element periphery in the imaging device of embodiment of this invention, (b) is sectional drawing in the AA of (a), (c) is ( It is sectional drawing in the BB line of a). (A) is a top view which shows the other example of the image pick-up element periphery in the imaging device of embodiment of this invention, (b) is sectional drawing in the AA of (a), (c) is ( It is sectional drawing in the BB line of a).

  An optical element and an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings. The drawings used in the following description are schematic, and the distinction between upper and lower is for convenience of explanation and does not regulate the upper and lower when the optical element and the image pickup apparatus are actually used. Absent. In the following description, the refractive index of light including infrared rays in each member (A) is simply referred to as the refractive index of (A).

  FIG. 1 is a cross-sectional view showing an optical element and an imaging apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a portion A in FIG.

  1 and 2, the optical device 1 includes a flat optical member (lid) 2 and an optical element 3 including a lens 31. The optical element 3 and the lid 2 are disposed in the housing 4. One end of the housing 4 (the left end in FIG. 1) is opened, and external light enters from the opening. At the other end of the housing 4 (the right end in FIG. 1), a fixed plate 5 to which a package 7 that accommodates the image sensor 6 is fixed is disposed. External light that has entered the housing 4 is collected by the optical element 3, and the light is converted into an electrical signal by the imaging element 6 to perform imaging.

  In the example shown in FIG. 1, two optical elements 3 are combined for adjusting the focal length. Moreover, the object imaged with the imaging device 1 contains infrared rays. In the case of imaging with infrared rays, infrared rays emitted from an object to be imaged (hereinafter referred to as an object) such as various objects such as animals such as animals including humans and buildings are imaged by the imaging element 6.

  As shown in FIG. 2, the optical element 3 of the embodiment includes a lens 31 having an entrance surface and an exit surface, an entrance surface of the lens 31 (a left side surface of the lens 31), and an exit surface (a surface on the right side of the lens 31). And an antireflection film 32 provided on the surface.

  The antireflection film 32 may be provided on only one of the entrance surface and the exit surface of the lens 31. When the imaged light is infrared, an antireflection film 32 that prevents reflection of infrared is used. Details of the antireflection film 32 will be described later.

  The image pickup device 6 is arranged on the exit surface side of the lens 31 of the optical element 3, and the image pickup apparatus 1 of the embodiment is basically configured. The image sensor 6 is arranged away from the lens 31 according to the focal length of the lens 31 and the like.

  The optical element 3 is for collecting (condensing) light such as infrared rays so as to be focused by the image sensor 6. When the optical element 3 condenses light, the image pickup by the image pickup element 6 is easily performed.

  The lens 31 of the optical element 3 is a portion having a function of actually condensing light, for example, a convex lens. The lens is made of an infrared transmitting material such as silicon (Si) or germanium (Ge).

  Light that has entered the housing 4 from the outside is collected by the optical element 3, refracted, and imaged by the image sensor 6 (with a focal point). That is, light passes through the lens 31 and the antireflection film 32 and is received by the image sensor 6. For example, infrared rays as light radiated from the object and incident from the outside into the housing 4 are refracted by the lens after passing through the antireflection film 32 on the incident side of the optical element 3 and imaged at the position of the imaging element 6. Guided to tie.

  The received information is transmitted from the imaging device 1 to an external electric circuit or the like as image data of an electric signal.

  The antireflection film 32 is for suppressing the reflection of light on the surface of the lens 31 and increasing the transmittance of infrared light in the optical element 3. The antireflection film 32 is formed to have a refractive index intermediate between the refractive index of the lens and the refractive index of air, for example.

  More specifically, the antireflection film 32 is made of a material whose refractive index is smaller than that of the lens 31. This material is made of a material that transmits infrared rays as described above. The antireflection film 32 may be set, for example, so that the product of its thickness and refractive index becomes 1/4 of the light (infrared) wavelength at which the transmittance is maximum.

  The antireflection film 32 is formed by applying a material having a refractive index as described above to the surface of the lens 31 (at least one of the entrance surface and the exit surface) with a predetermined thickness by various thin film forming methods. It is formed by wearing.

  Further, the antireflection film 32 can also be formed by processing the surface of the lens 31 into a fine protrusion shape or attaching a protrusion-shaped substance. That is, the antireflection film 32 having a refractive index smaller than the refractive index of the lens 31 may be created by manipulating the material density, and the antireflection film 32 may be provided by a method of obtaining an equivalent effect.

  The light transmittance in the optical element 3 is a light transmittance obtained by combining the transmittance of the antireflection film 32 and the transmittance of the lens 31. That is, in one optical element 3, the ratio of the amount of light emitted from the exit-side antireflection film 32 to the amount of light incident from the entrance-side antireflection film 32 corresponds to the transmittance (%). To do.

In the optical element 3 and the imaging device 1 according to the embodiment, the transmittance of light such as infrared rays transmitted through the lens 31 and the antireflection film 32 has one peak in the light wavelength range of 8 to 12 μm. . A detailed description of the absorption peak will be given later.

Light having a wavelength of 8 to 12 μm is infrared light emitted from an object having a temperature of about 0 to 100 ° C.
This temperature corresponds to a general range including the temperature of a person (human body), and in particular, there is a high possibility that the maximum value of absorption corresponds to the temperature range of the human body. The wavelength of light in this temperature range is about 9.4 μm. Since the optical element 3 of the embodiment has a relatively high light transmittance at a wavelength corresponding to the temperature of the human body, the human body can be effectively sensed by being distinguished from other objects. Therefore, it is possible to provide the optical element 3 that makes it easy to produce the imaging device 1 effective for sensing a human body (such as a pedestrian).

  Note that an image (video) captured in this case is a thermal image using infrared rays, and a plurality of objects having different temperatures have different brightness. Therefore, it is possible to easily identify a human body that is an object whose temperature is often different from each other and other objects (buildings, road surfaces, other vehicles, and the like) by a difference in brightness in an infrared image (thermal image). In other words, a pedestrian or the like can be easily detected as long as the absorptance of the optical element 3 has one peak in the wavelength band.

Regarding the optical element 3 of the embodiment, the light transmittance may be the highest when the wavelength of light is 9.4 μm. As described above, the temperature of light with a wavelength of 9.4 μm is about 35 to 37.
Infrared rays emitted from an object at ° C. In this case, the optical element 3 and the imaging device 1 that can capture an image of a human body such as a pedestrian in a so-called pinpoint manner in a narrower range can be obtained.

  The light transmittance in the optical element 3 can be set as described above by adjusting at least one of the refractive index and the thickness of the antireflection film 32, for example. Further, the refractive index and thickness of the antireflection film 32 may be appropriately adjusted according to the thickness or refractive index of the lens 31.

Specifically, in order to transmit a wavelength of 9.4 μm with the highest transmittance, when the lens is made of single crystal silicon (Si), the refractive index of silicon is 3.42. In this case, for example, when zinc sulfide (ZnS) is used as the antireflection film 32, if the refractive index (n) of zinc sulfide is 2.20, the refractive index is approximately halfway between air and silicon. Reflection on the surface of the surface is reduced. At that time, the thickness (d) of the antireflection film 32 is 1/4 wavelength because the thickness of the antireflection film 32 is 1 / 2.2 of 9.4 μm of the wavelength in air in zinc sulfide having a refractive index of 2.2. What is necessary is just to set to about 1.1 micrometer of the physical thickness which becomes.

  Examples of the material for the antireflection film 32 having a refractive index in the above range include zinc sulfide (ZnS) and diamond-like carbon (DLC).

  In the imaging device 1 of the embodiment, two optical elements 3 are arranged in the housing 4. As for both of these optical elements 3, as described above, the transmittance is larger than the other wavelengths when the wavelength of light is in the range of 8 to 12 μm.

  However, the two optical elements 3 do not necessarily have to be the same as long as the above conditions are satisfied, and the transmittance at each wavelength of light (or a certain wavelength range) is slightly different. There may be.

  The imaging element 6 is a photoelectric conversion element, and if the light to be imaged is an infrared ray, an infrared imaging element such as a quantum type or a thermal type is used.

  The package 7 is for housing the image sensor 6 such as an infrared image sensor and electrically connecting it to the outside. The package 7 includes an insulating base (not indicated as an insulating base) made of, for example, an aluminum oxide sintered body, and a wiring conductor (not shown) provided on the surface or inside of the insulating base. In the example shown in FIG. 1, a concave portion is provided on the main surface (left surface in FIG. 1) of a rectangular parallelepiped insulating base, and the image sensor 6 is accommodated in the concave portion.

  For example, the image pickup element 6 can be electrically connected to an external electric circuit by a wiring conductor provided from the inside of the recess to the outer surface of the insulating base.

The recess of the package 7 is closed by the lid 2. The image sensor 6 is hermetically sealed in a container constituted by the lid 2 and the recess. The lid 2 is the optical member 2 as described above, and similarly to the optical element 3, the base 21 made of an infrared transmitting material such as silicon or germanium and the antireflection film 22 made of zinc sulfide or diamond-like carbon on the front and back are optically provided. 9.4 same as element 3
The infrared ray having a wavelength of μm is formed to have the highest transmittance.

  The fixing plate 5 is for fixing an image pickup device (no symbol) constituted by the package 7 in which the image pickup element 6 is accommodated and the lid 2. The positional relationship between the image sensor 6 and the optical element 3 is fixed by being fixed to the fixed plate 5. That is, the imaging element 6 is fixed at a position where the light condensed by the optical element 3 normally forms an image.

  The fixing plate 5 can be fixed to the housing 4 by various bonding methods such as bonding via a bonding material such as an adhesive (not shown), screwing, and the like. You may enable it to perform fine adjustment for exact alignment with a focus and an optical axis.

  FIG. 3 is an overhead view schematically showing a situation where the imaging device 1 according to the embodiment of the present invention is used in a moving body. FIG. 4 is an example of an image detected by the imaging apparatus 1 in the situation shown in FIG.

  The moving body in the example shown in FIG. 3 is a vehicle (four-wheeled automobile), and the imaging device 1 is set toward the front of the vehicle. The image (detected image) imaged by the imaging device 1 is a situation in front of the vehicle, and various objects existing in front are detected. The imaging device 1 in this case is used by being mounted, for example, on a device for driving assistance of an automobile.

  When an infrared imaging device is used as the imaging device 6, an infrared image of an object in front of the vehicle is taken. Since infrared rays are emitted by the object itself, effective imaging can be performed even when the amount of visible light is small such as at night or in the rainy weather where visual confirmation tends to be insufficient. Therefore, effective driving support regarding safety and the like is performed.

As described above, the optical element 3 in the imaging device 1 of the embodiment has one peak in the transmittance of light (infrared rays) transmitted through the lens 31 and the antireflection film 32 in the wavelength range of 8 to 12 μm. doing. In addition, the infrared ray having this wavelength corresponds to a temperature of about 0 to 100 ° C., and is likely to reach a maximum value at a temperature of about 35 to 37 ° C. The wavelength included in the above wavelength band is 9.4μm
The infrared ray having a peak is emitted from an object having a temperature of 35 to 37 ° C., that is, a human body such as a pedestrian. Therefore, the driving support device in which the imaging device 1 of the embodiment is mounted can effectively detect the presence of a pedestrian in the direction in which the vehicle moves (front) even at night.

In this case, light having a wavelength of less than 8 μm (such as infrared and visible light emitted from a relatively high temperature object of 100 ° C. or more) and light having a wavelength of more than 12 μm (emitting from a relatively low temperature object of less than 0 ° C. For example, the transmittance of the optical element 3 is relatively small. Therefore, for example, an object other than a human body (pedestrian or the like) that is particularly desired to be sensed in driving assistance is difficult to be imaged. That is, it is possible to provide the optical element 3 and the imaging apparatus 1 that can perform imaging while effectively identifying only pedestrians from buildings, trees (planting), other vehicles, roads, and the like. In this case, as described above, if the transmittance of the optical element 3 is maximum at a wavelength of 9.4 μm, more effective detection of a pedestrian or the like can be performed.

  In other words, the human body is preferentially sensed by the image sensor 6 by making the transmittance of infrared rays generated from an object near the human body temperature of the optical element 3 highest and lowering the transmittance of other wavelengths. In the imaging apparatus 1 including the optical element 3, it is possible to easily increase the sensitivity of the human body by making it less sensitive to unnecessary objects other than the human body such as trees and other vehicles. Therefore, it becomes easy to detect a human body by imaging with the imaging element 6 (two-dimensional infrared imaging).

  By mounting this imaging device 1 (two-dimensional imaging device) on a vehicle and using it for monitoring the moving direction, a relative position between a human body such as a pedestrian in the moving direction of the moving body and the traveling direction of the vehicle The relationship can be easily recognized. In addition, since it is easy to simplify the algorithm for avoiding danger in the above-mentioned device for driving support, it is easy to speed up the imaging process. This makes it easier to avoid danger such as contact between the vehicle and the pedestrian.

  Note that in the above-described driving support device, the imaging device 1 may be mounted toward the rear of the vehicle or the like. In this case, driving assistance related to safety when the vehicle moves backward is possible.

  In the optical element 3 and the imaging device 1 of the embodiment, the average light transmittance when the wavelength of light transmitted through the optical element 3 is in the range of 8 to 12 μm is T1, and the wavelength of light is in the range of 4 to 8 μm. T2 <T3 <T1, where T2 is the average light transmittance and T3 is the average light transmittance when the light wavelength is in the range of 12 to 16 μm.

In this case, from the human body temperature range of 35-37 ° C, the peak wavelength light is 9.4μ
Infrared rays are emitted on both the short wavelength side and the long wavelength side with a weak intensity with increasing distance from the peak wavelength as well as the peak wavelength. Make sense. Moreover, the surface temperature of a person (pedestrian as an object) tends to be lower than the temperature of the human body due to clothes or the like. Therefore, the transmittance of light having a wavelength of 12 to 16 μm emitted from an object having a temperature lower than that of the human body is sensed next higher. Further, the transmittance of light of 4 to 8 μm, which is light having a wavelength generated from an object having a higher temperature than that of the human body, which is unlikely to be emitted from the person, is set to be the lowest so that the imaging element 6 is difficult to detect. With these, it is only 9.4 in the range of 8-12 μm.
Sensing accuracy and the like are higher than those of the optical element 3 having a transmittance peaking in the vicinity of μm.

  That is, the level of the infrared ray (T1) emitted from the human body due to, for example, the object to be detected being far away is reduced by decreasing the transmittance of the optical element 3 in the infrared range where the possibility of being emitted from the human body is low. Even if it is small, it is advantageous because the level of unnecessary infrared rays (T2 and T3) is lowered, and the relative detection sensitivity is increased. Therefore, the transmittance of T2 <T3 <T1 is effective for human body sensing. Note that infrared light of less than 4 μm and infrared light of longer than 16 μm are significantly out of the wavelength range of infrared rays emitted from the human body. That is, since the wavelength range is unnecessary for detecting a human body, the above range can be sensed with better sensitivity when blocked by a filter or the like (not shown).

(Specific example of transmittance)
A specific example of light transmittance in the optical element 3 and the imaging apparatus 1 according to the embodiment will be described with reference to FIGS. FIG. 5 is a graph showing an example of the transmittance of the antireflection film 32 included in the optical element 3 according to the embodiment of the present invention. FIG. 6 is a graph showing an example of the transmittance of the lens 31 included in the optical element 3 according to the embodiment of the present invention. FIG. 7 shows an optical element 3 (lens 31) according to the embodiment of the present invention.
And the antireflection film 32) is a graph showing an example of the transmittance. FIG. 8 is a graph illustrating an example of light received by the imaging device 6 in the imaging device 1 according to the embodiment of the present invention.

In the optical element 3 and the imaging device 1 of the specific example, the lens 31 is made of oxygen-free polycrystalline silicon. The lens 31 had a refractive index (n1) of 3.42 and a thickness (d1) of 0.5 mm at the center (transmittance measured at the center). In addition, the antireflection film 32
Used was made of zinc sulfide. The antireflective film 32 had a refractive index (n2) of 2.2 and a thickness (d2) of 0.11 μm.

  Based on the above conditions, the results of performing a transmittance simulation at each wavelength for the optical element 3 are graphs shown in FIGS. In each graph, the horizontal axis represents the wavelength of infrared light (light) transmitted through the optical element 3, and the vertical axis represents the transmittance. FIG. 8 is a graph showing the result of performing a transmittance simulation at each wavelength in a situation where the imaging device 1 passes through two optical elements 3 and one lid 2 and is imaged by the imaging element 6. .

As can be seen from this result, for example, by performing the setting as described above, it is possible to manufacture the optical element 3 having a larger average transmittance in the wavelength range of 8 to 12 μm than in the other wavelength ranges. Further, in this example, the optical element 3 having the largest light transmittance when the light wavelength is 9.5 μm can be manufactured.

  9A to 9C are enlarged views showing an example of the imaging element 6 and its periphery (including the package 7 to be used) in the imaging apparatus 1 shown in FIG. FIG. 9A is a plan view of the imaging device 6 viewed from the direction along the optical axis of the lens 3, and FIG. 9B is a cross-sectional view taken along the line AA in FIG. 9 (c) is a cross-sectional view taken along line BB in FIG. 9 (a). In FIG. 9, for convenience of explanation, the direction along the optical axis of the lens 3 is the vertical direction in the figure. In the following description, a surface facing the optical element 3 such as the imaging element 6 and the package 7 may be referred to as an upper surface. Further, the surface opposite to the upper surface may be referred to as the lower surface.

  As in the example shown in FIG. 9, for example, the package 7 has an element mounting region 7 a for mounting an image sensor 6 such as an infrared image sensor. The image pickup device 6 is arranged in the device mounting area 7a, the terminals of the image pickup device 6 and the internal terminals (not shown) of the package 7 are electrically connected by bonding wires 8 or the like, and the external formed on the lower surface of the package 7 Electrically connected to the outside through a terminal. With this electrical connection, the image sensor 6 and the outside are electrically connected to each other.

  The package 7 has a structure including an insulating base made of, for example, an aluminum oxide sintered body as described above, and a wiring conductor including the internal terminal provided on the surface or inside of the insulating base. Such a package 7 can be produced by a so-called green sheet lamination method.

  The package 7 is fixed to the fixed plate 5, but an inexpensive spherical lens is used as the optical element 3 (lens 31), which can easily shorten the design and manufacturing process. As a result, the productivity and economy of the imaging device 1 including the lens 31 are increased.

  In this case, the image is sharpened from the optical axis portion of the lens 31 (the central portion of the image sensor 6) to the outer peripheral portion (the peripheral portion) of the detected image due to the spherical aberration of the lens 31 (so-called focusing). ) Tends to be difficult. This is because when the lens 31 which is a spherical lens is arranged so as to be focused at the center of the image sensor 6, as shown in the example shown in FIG. 10, the periphery of the image sensor 6 is in front of the image sensor 6. This is because it comes to focus.

When the optical element 3 is sufficiently larger than the image sensor 6 or uses an image with a narrow angle of view, the influence of spherical aberration is reduced, but the optical element 3 can be downsized relative to the image sensor 6, When an image with a wide angle of view is to be captured, the influence of spherical aberration increases. For this reason, when the image sensor 6 is arranged on a plane as shown in FIG. 9, if the focus is focused at the center of the image sensor 6, the focus is not achieved at the periphery, and the image is easily blurred, improving the accuracy of the sensor. It tends to be difficult. On the other hand, in another example of the embodiment shown below, the imaging device 1
It is also possible to further improve the accuracy of detecting pedestrians and the like while ensuring high productivity and economic efficiency.

  In each of the following examples, the imaging device 6 is closer to the optical element 3 in the outer peripheral portion (peripheral portion) that is farther from the central portion than the central portion that faces the optical axis of the optical element 3 (specifically, the lens 31). . In this case, the distance (far / near) between the imaging element 6 and the optical element 3 is a distance between the mutually facing surfaces of the imaging element 6 and the optical element 3 in a direction parallel to the optical axis of the lens 31. Thereby, it is possible to reduce the influence of aberration caused by the lens 31 being a spherical lens. In other words, the position of the image sensor 6 can be brought closer to the optical element 3 by the amount of displacement of the position connecting the images due to aberration, and the influence of the displacement can be reduced or canceled.

  FIG. 11 is another example of the periphery of the image sensor 6 (portion including the package 7) used in the image pickup apparatus 1 of the embodiment. FIG. 11A is a plan view of the image sensor 6 as viewed from above. 11B is a cross-sectional view taken along the line AA in FIG. 11A, and FIG. 11C is a cross-sectional view taken along the line BB in FIG. 11A. In the example shown in FIG. 11, the image sensor 6 is arranged along the shape of the element mounting area 7a of the package 7 having the concave element mounting area 7a along the spherical aberration of the optical element 3.

  The imaging device 1 shown in FIG. 11 has an element mounting area 7a on which the imaging element 6 is mounted, and the element mounting area 7a has a package 7 having a concave shape along the aberration of the optical element 3. The imaging element 6 is arranged along the element mounting area 7a.

  In this example, the package 7 includes a frame 7b and an element mounting portion 7c including a concave element mounting region 7a having a curvature corresponding to spherical aberration as shown in FIG.

  The frame 7b includes an insulating base (not indicated as an insulating base) made of, for example, an aluminum oxide sintered body and a wiring conductor (not shown) provided on the surface or inside of the insulating base, as in the package 7 described above. ). Similarly, the element mounting portion 7c is an insulating base made of, for example, an aluminum oxide sintered body and has a concave element mounting region 7a using a technique such as powder molding. The package 7 having the above-described configuration can be manufactured by bonding the frame 7b and the element mounting portion 7c to each other with an adhesive such as an epoxy resin.

  For example, the imaging element 6 is shaved by polishing or the like on the back surface (the surface opposite to the optical element 3), and after thinning, an adhesive is used to form the imaging element 6 with a jig or the like having a convex portion corresponding to the element mounting region 7a. By pressing, it can be arranged in a predetermined shape at a predetermined position. Since the height of the surface of the peripheral portion can be increased by the amount of spherical aberration as compared with the center of the image sensor 6, high-accuracy infrared image detection can be performed using the optical element 3 using an inexpensive spherical lens.

  The element mounting area 7a is not limited to the curved surface shape as described above, and may be a stepped surface that is closer to the optical element 3 as the outer peripheral portion of the mounted image sensor 6 is. Also in this case, the influence of the aberration due to the spherical lens can be reduced, and the imaging apparatus 1 capable of imaging with reduced possibility of blurring can be obtained.

FIG. 12 is another example of the periphery of the image sensor 6 (part including the package 7) used in the image pickup apparatus 1 of the embodiment. FIG. 12A is a plan view of the image sensor 6 as viewed from above. Yes, Figure 12 (
FIG. 12B is a sectional view taken along line AA in FIG. 12A, and FIG. 12C is a sectional view taken along line BB in FIG. The element mounting region 7 has a shape having a long side and a short side when viewed from the optical element side, that is, the upper surface in FIG. 12, for example, a rectangular shape.

  As can be seen from FIG. 12C, the element mounting area 7c has a cross section that is linear in the short side direction of the element mounting area 7a, and in the direction perpendicular to the element (long side direction), for example, the lens 31 It is curved along the aberration. In other words, the element mounting region 7a is a curved surface only in the long side direction.

  In this case as well, the package 7 can be produced by dividing the package 7 into the frame 7b and the element mounting portion 7c and bonding them.

  In this case, for example, when the imaging apparatus 1 is used for driving assistance (for pedestrian recognition) in a vehicle, image blurring occurs in the left-right direction (such as both left and right ends) where a wider effective angle of view is required. Can be effectively reduced. That is, when the package 7 is used so that the long side direction is horizontal, the focal point can be focused on the surface of the image sensor 6 with a wide angle of view with respect to the horizontal direction. Although the angle of view that is in focus in the vertical direction is narrow, the maximum height of a human subject to be detected in the vertical direction is smaller than the maximum value of the road width in the horizontal direction of the target for a vehicle driving support camera. Since it is obviously small, even if the angle of view in the vertical direction is narrower than the angle of view in the width direction, it is unlikely to be a big problem in practice.

  Further, when the image sensor 6 is deformed to the shape of the element mounting region 7a in FIG. 10, the image sensor 6 needs to be cut thinner because the stress applied to the image sensor 6 is large, but in this example, only the long side direction is required. This is effective in increasing productivity. Further, when the imaging element 6 is deformed in accordance with the shape of the element mounting region 7a, the stress applied to the imaging element 6 can be reduced, and thus the reliability is improved. In addition, since the time required for polishing the image sensor 6 can be reduced, productivity is improved.

  FIG. 13 is another example of the periphery of the image sensor (portion including the package 7) used in the image pickup apparatus 1 of the embodiment, and FIG. 13A is a plan view of the image sensor 6 as viewed from above. 13B is a cross-sectional view taken along line AA in FIG. 13A, and FIG. 13C is a cross-sectional view taken along line BB in FIG. 13A.

  As can be seen from FIG. 13C, the element mounting region 7c is linear in the short side direction, and is stepped along the aberration of the lens in the direction perpendicular thereto. In this case, similarly to the above, the package 7 can be created by dividing it into the frame 7b and the element mounting portion 7c and bonding them. However, as with the package of FIG. If the step is formed by making the outer dimensions of the green sheets different from each other by a sheet lamination method or the like, the package 7 having a stepped surface (element mounting region 7a) can be manufactured.

  Also in this case, when the package 7 is used so that the long side direction is horizontal, the package 7 can be focused on the surface of the image sensor 6 with a wide angle of view with respect to the horizontal direction. In addition, the image sensor 6 can be divided into a plurality of parts in accordance with the steps (upper surface of each step). In this way, a polishing process for bending the image sensor is unnecessary, and productivity is improved. Further, since the divided imaging elements (not shown) may be bonded to each step in a planar manner, the adhesion stability can be improved as compared with the case of bonding to a curved surface.

  When conduction between the plurality of divided image pickup devices 6 is necessary, a terminal is formed on the back surface of the image pickup device 6 and electrically connected to the terminal formed on the bottom surface of the recess of the package 7.

1. Imaging device 2. Lid (optical member)
21 ... Base material
22 ... Antireflection film 3 ... Optical element
31 ... Lens
32... Antireflection film 4... Case 5... Fixing plate 6... Image sensor 7. .... Frame part 7c ... Element mounting part 8 ... bonding wire

Claims (7)

A lens having an entrance surface and an exit surface;
An antireflection film provided on at least one of the entrance surface and the exit surface of the lens,
The transmittance of light transmitted through the lens and the antireflection film is an optical element having one peak in the light wavelength range of 8 to 12 μm. The optical element according to claim 1, wherein the transmittance of the light at the one peak is the largest when the wavelength of light is 9.4 μm. T1 is the light transmittance when the light wavelength is in the range of 8 to 12 μm, T2 is the light transmittance when the light wavelength is in the range of 4 to 8 μm, and the light wavelength is 12 to 16 μm. 2. The optical element according to claim 1, wherein T <b> 2 <T <b> 3 <T <b> 1, where T <b> 3 is the light transmittance in the range. An optical element according to any one of claims 1 to 3,
An image pickup apparatus comprising: an image pickup element disposed away from the lens on the exit surface side of the lens. The image pickup device according to claim 4, wherein the image pickup device is closer to the optical element at an outer peripheral portion away from the central portion than a central portion facing the optical axis of the optical element. An element mounting area on which the imaging element is mounted, and the element mounting area further includes a package having a concave shape or a step shape along the aberration of the optical element;
The imaging device according to claim 4, wherein the imaging element is arranged along the element mounting region. The element mounting region has a shape having a long side and a short side when viewed from the optical element side, a cross section in a direction along the optical axis is linear in the short side direction, and the long side The imaging device according to claim 5, wherein the imaging device has a curved shape or a step shape along the aberration of the lens in the direction.

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