Imaging device, vehicle-mounted camera, and transportation equipment

Abstract

To provide an imaging apparatus, an on-vehicle camera, and a transportation apparatus capable of maintaining excellent performance even when a back focus is fluctuated due to an environmental temperature change and an influence of sunlight.SOLUTION: An imaging device comprising a lens, a lens holding member that holds the lens and has a first thermal conductivity, an imaging unit including an image sensor and an image sensor holder, and a housing that houses the lens holding member and the imaging unit, wherein the imaging unit is configured such that a position of the image sensor changes toward the lens as a temperature of the image sensor holder increases, wherein the image pickup apparatus further comprises a heat conduction member having a second thermal conductivity, the heat conduction member being different from the housing, a part of the heat conduction member being connected to the element holder and another part of the heat conduction member being connected to the lens holding member, the heat conduction member being housed in the housing, and the second thermal conductivity is equal to or higher than the first thermal conductivity.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an imaging device, an in-vehicle camera, and transportation equipment. [Background technology]

[0002] In recent years, automobiles have been equipped with on-board cameras, such as sensing cameras for driving assistance and autonomous driving functions, and cameras for capturing images of the vehicle's surroundings. Images captured by on-board cameras are used to detect road lines, obstacles, etc., through desired image processing, and are then used to control the vehicle.

[0003] From the perspective of cost and device miniaturization, many in-vehicle cameras are fixed-focus type and do not have the autofocus function used in general digital still cameras, etc. In addition, in-vehicle cameras are required to operate stably and maintain excellent performance across a wide range of environmental temperatures and various solar radiation conditions.

[0004] Changes in ambient temperature lead to changes in back focus (the distance from the edge of the lens closest to the image sensor to the focal point). When ambient temperature rises, the back focus of the optical system usually shortens due to factors such as an increase in the distance between lenses and changes in the temperature characteristics of the refractive index of the lens glass material. In addition, because in-vehicle cameras are often positioned facing the windshield of a vehicle, the temperature of the lens and lens barrel can rise due to sunlight. This temperature increase in the lens and lens barrel due to sunlight also leads to a shortening of the back focus of the optical system.

[0005] In order for a fixed-focus vehicle-mounted camera to maintain excellent performance across a wide range of ambient temperatures and sunlight conditions, the image sensor must be kept within the focal depth of the optical system to follow the back focus, which changes depending on the ambient temperature and sunlight conditions.

[0006] Document 1 describes that an image sensor substrate is held by an image sensor plate, and by curving the image sensor substrate so that it becomes convex toward the lens as the ambient temperature changes, it is possible to suppress an increase in flange back (the distance from the lens barrel mounting surface to the image sensor) that accompanies temperature changes. Also, Document 2 describes that by providing a back plate that supports the image sensor with a two-material element designed to bend as the ambient temperature changes, it is possible to make the image sensor follow thermal displacement of the back focus.

[0007] The conventional techniques disclosed in the above-mentioned patent documents are capable of dealing with changes in back focus that accompany changes in environmental temperature, such as when the temperature of the entire image pickup device rises or falls uniformly. However, in all of the conventional techniques, the position of the image pickup element in the optical axis direction depends on the environmental temperature, making it difficult to deal with changes in back focus that occur due to partial temperature rise or fall of the vehicle-mounted camera caused by sunlight, which has a particularly large impact on vehicle-mounted cameras. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2024-2151 [Patent Document 2] Special Publication No. 2019-530887 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an imaging device, an on-board camera, and transportation equipment that can maintain excellent imaging performance even when back focus fluctuations occur due to changes in environmental temperature and the influence of solar radiation. [Means for solving the problem]

[0010] The above object can be achieved by the present invention, which provides an imaging device including a lens, a lens holding member having a first thermal conductivity and holding the lens, an imaging unit including an imaging element and an imaging element holder, and a housing that houses the lens holding member and the imaging unit, the imaging unit is configured such that the position of the imaging element changes toward the lens as the temperature of the imaging element holder increases; The imaging device further includes a thermal conductive member having a second thermal conductivity housed in the housing, separate from the housing, one part of which is connected to the imaging element holder and the other part of which is connected to the lens holding member, and the second thermal conductivity is equal to or greater than the first thermal conductivity. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an imaging device, an on-board camera, and transportation equipment that can maintain excellent performance even when back focus fluctuations occur due to changes in ambient temperature and the influence of solar radiation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an in-vehicle camera according to the present invention; [Figure 2] FIG. 2 is a cross-sectional view of the lens barrel unit of the present invention. [Figure 3] 1A and 1B are diagrams illustrating an image pickup element and an image pickup element substrate according to the present invention. [Figure 4] 1A and 1B are diagrams illustrating a configuration of an imaging element holder according to the present invention. [Figure 5] 10A to 10C are diagrams illustrating a method for fixing an imaging element to an imaging element holder according to the present invention. [Figure 6] 10A to 10C are diagrams showing a method for fixing the lens barrel unit and the imaging unit to the housing of the present invention. [Figure 7] 1A to 1C are diagrams illustrating a method for attaching the heat conducting member of the present invention. [Figure 8] 10A to 10C are diagrams illustrating deformation of an imaging element holder and a position of an imaging element due to changes in environmental temperature and the influence of sunlight in the present invention. [Figure 9] 1 is a diagram illustrating a configuration of a transportation device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] An example of an embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example, and the present invention is not limited to the illustrated configurations, etc.

[0014] In this specification, the temperature of the environment in which an object exists is referred to as “environmental temperature.” Examples of environmental temperature include air temperature, room temperature, the temperature inside a vehicle, and the temperature inside a housing.

[0015] FIG. 1 shows a schematic diagram of a camera module 600, which is an example of an imaging device of the present invention. The camera module 600 is connected to an information processing unit 700 to form an in-vehicle camera 1000. The camera module 600 is composed of a lens-barrel unit 100, a housing 200, an imaging unit 300, a heat-conducting member 400, and a housing 500. The housing 500 houses the lens-barrel unit 100, the housing 200, the imaging unit 300, and the heat-conducting member 400, and fulfills functions such as shock resistance and dustproofing. The lens-barrel unit 100 is held in the housing 200, and as described below, the imaging unit 300 is adhesively fixed to the housing 200 in an optically adjusted state. Furthermore, a portion of the heat-conducting member 400 is connected to the imaging unit 300, and another portion is connected to the lens-barrel unit 100.

[0016] 2 is a cross-sectional view showing a cross section including the optical axis at the center of barrel unit 100. Barrel unit 100 includes barrel 10. Barrel unit 100 further includes lenses 11, 12, 13, and 14, and a retaining ring 18, which are held within barrel 10 and spaced apart from one another using ring-shaped spacers 15, 16, and 17, which are lens holding members. Barrel 10 is made of a metal material or a resin material, and lenses 11, 12, 13, and 14 are made of a light-transmitting material such as glass or a resin material to allow light to pass through.

[0017] A male screw portion (not shown) provided on the outer diameter portion of the pressing ring 18, which is one of the lens holding members, is screwed into a female screw portion (not shown) provided on the inner diameter portion of the lens barrel 10, whereby the lenses 11, 12, 13, 14 and the spacers 15, 16, 17 are fixed. Further, the lens barrel 10 includes a male screw portion 10a for fixing the lens barrel unit 100 to the housing 200 on the outer diameter portion. Furthermore, the lens barrel 10 includes an outer diameter portion 10b for connecting to the heat conductive member 400.

[0018] The plane A shown in FIG. 2 indicates the focal position at the environmental temperature T0 where the solar radiation influence is negligibly small, and the plane A' indicates the focal position at the environmental temperature T1 (T0 < T1). When the environmental temperature changes, the back focus of the optical system fluctuates due to changes in the thickness dimensions of the spacers 15, 16, 17, changes in the shapes of the lenses 11, 12, 13, 14, and changes in the refractive index (temperature characteristics). Generally, when the environmental temperature rises, as shown in FIG. 2, the back focus changes in the direction of shortening the back focus. Let this amount of change in the back focus be D a be.

[0019] Furthermore, when the temperature of the entire or a part of the constituent members of the lens barrel unit 100 rises due to solar radiation, the back focus changes in the direction of shortening the back focus due to changes in the thickness dimensions of the spacers, changes in the shapes of the lenses, and changes in the refractive index (temperature characteristics). Let this amount of change in the back focus due to solar radiation be D s be. The amount of change in the back focus D s varies depending on the solar radiation state, increases as the solar radiation intensity increases, and may occur even when the environmental temperature does not necessarily rise. Therefore, it is important to maintain the excellent imaging performance even when the camera module 600 is placed in a widely varying environmental temperature and solar radiation state. For this purpose, it is necessary to hold the imaging unit 300 so as to follow the back focus that varies due to the above-described environmental temperature change and solar radiation state.

[0020] Next, the imaging element 31 and the imaging element substrate 32 will be described with reference to Fig. 3. Fig. 3(a) is a side view of the imaging element 31 mounted on the imaging element substrate 32, and Fig. 3(b) is a rear view of the imaging element 31.

[0021] The image sensor 31 has a photoelectric conversion unit inside and is mounted on an image sensor substrate 32 as shown in FIG. 3( a). A subject image formed on the imaging surface by light transmitted through the lens of the lens barrel unit 100 and received by the image sensor 31 is photoelectrically converted into an electrical signal by the photoelectric conversion unit. In this embodiment, a CMOS sensor is used as the image sensor 31, but this is not limiting and other imaging devices such as CCD or CID types may also be used. The front side (the side where light is incident) of the image sensor 31 is covered by a cover glass 30. An electrode pad 31g is provided on the back side (the side opposite to the side where light is incident) of the image sensor 31, and the electrode pad 31g is electrically connected to the photoelectric conversion unit of the image sensor 31.

[0022] The imaging element substrate 32 is electrically connected to the photoelectric conversion unit of the imaging element 31 via electrode pads 31g, and receives electrical signals from the imaging element 31. A substrate connector 32a is provided on the rear side of the imaging element substrate 32, and is electrically connected to a control circuit (not shown) of the information processing unit 700.

[0023] The electrode pads 31g of the imaging element 31 are soldered to lands (not shown) of the imaging element substrate 32 by automatic mounting, thereby electrically connecting the imaging element 31 to the imaging element substrate 32, thereby integrating the imaging element 31 with the imaging element substrate 32. The imaging element substrate 32 may be a flexible substrate such as a flexible printed circuit (FPC). The cover glass 30 is adhesively fixed to the imaging element 31 while overlapping the surface of the imaging element 31, preventing foreign matter from adhering to the imaging surface of the imaging element 31.

[0024] The electrical signal output from the photoelectric conversion unit of the image sensor 31 is transmitted to the image sensor board 32 via the electrode pad 31g, and then transmitted from the image sensor board 32 to a control circuit (not shown) of the information processing unit 700 via the board connector 32a, where the desired image processing is performed.

[0025] Next, the imaging element holder 33 to which the imaging element 31 is positioned and fixed will be described with reference to Fig. 4. Fig. 4(a) is an exploded perspective view of the imaging element holder 33, Fig. 4(b) is a perspective view of a first element holder part 33A, and Fig. 4(c) is a perspective view of a second element holder part 33B.

[0026] 4(a), the imaging element holder 33 is composed of a first element holder part 33A including a first material, a second element holder part 33B including a second material, and a low thermal conductive member 35. These members are arranged in the order of first element holder part 33A, low thermal conductive member 35, and second element holder part 33B when viewed from the front side of the camera module 600, that is, in the order of closest to the lens in the optical path direction along the optical axis of the lens.

[0027] The first material contained in the first element holder component 33A can be at least one selected from the group consisting of stainless steel, aluminum alloy, copper alloy, polycarbonate resin (PC resin), and polyphenylene sulfide resin (PPS resin). The polycarbonate resin and polyphenylene sulfide resin may contain glass fiber to improve strength. To ensure sufficient deformation, the first material is preferably the main component of the first element holder component 33A. Here, the term "main component" refers to a material that accounts for 50 wt% or more of the component.

[0028] The second material may be at least one selected from the group consisting of carbon steel, stainless steel, copper alloy, and aluminum alloy. Furthermore, from the viewpoint of sufficient deformation, the second material is preferably the main component of the second element holder component 33B. Here, the term "main component" refers to a material that accounts for 50 wt% or more of the component.

[0029] The first element holder component 33A has an opening 33A1 for exposing the imaging surface of the imaging element 31, and protrusions 33A2 and 33A3 for positioning it in the second element holder component 33B. The surface of the first element holder component 33A is preferably subjected to an anti-reflection treatment such as plating or coating. That is, the surface of the first element holder component 33A is preferably coated with a material different from the first material, which is the main component of the first element holder component 33A. Here, the main component refers to a material that accounts for 50 wt% or more of the component.

[0030] The second element holder part 33B has an opening 33B1 to expose the imaging surface of the imaging element 31. Protrusions 33B2 and 33B3 that protrude toward the rear surface of the second element holder part 33B are formed in the opening 33B1, and protrusions 33B4 and 33B5 that protrude toward the rear surface are formed on a portion of the outer edge of the second element holder part 33B. The second element holder part 33B also has a pair of positioning holes 33B6 and a vibration prevention hole 33B7. In this embodiment, both protrusions 33B4 and 33B5 protrude toward the rear surface, but this is not limited thereto. The protrusions 33B4 and 33B5 may both protrude toward the front surface, or may protrude in different directions.

[0031] The first element holder part 33A is configured with the low thermal conductive member 35 inserted between it and the second element holder part 33B. The position is determined by fitting the protrusions 33A2 and 33A3 into a pair of positioning holes 33B6 and a vibration prevention hole 33B7 provided in the second element holder part 33B. The positioned first element holder part 33A is integrally joined to the second element holder part 33B and the low thermal conductive member 35 by fastening them with screws 44 at four locations.

[0032] In this embodiment, the first element holder part 33A is configured to be joined by fastening with screws at four locations, but this is not limited to this. They may be joined and integrated at at least two locations. In other words, the first element holder part 33A and the second element holder part 33B are effectively integrated by being joined at two or more locations.

[0033] Furthermore, the joining means is not limited to screwing. The joining means may be at least one selected from the group consisting of screwing, caulking, welding, adhesion, and bonding. Furthermore, in this embodiment, the connection portions 33B2 and 33B3 with the imaging element 31 and the connection portions 33B4 and 33B5 with the housing 200 are provided on the second element holder component 33B, but the above-mentioned multiple connection portions may be provided on the first element holder component 33A.

[0034] As will be described later, image sensor 31 moves in the optical axis direction due to deformation of image sensor holder 33 caused by changes in environmental temperature and sunlight, so that image sensor 31 is maintained within a range that ensures the performance of vehicle-mounted camera 1000 over a wide range of environmental temperatures and various sunlight conditions. Normally, when the temperature of barrel unit 100 rises due to environmental temperature or sunlight, the back focus changes to become shorter, so image sensor 31 needs to be configured to move closer to barrel unit 100.

[0035] That is, in order to move the image sensor 31 in the above-mentioned direction and to realize the miniaturization of the device, the linear expansion coefficient α of the first material is a is the linear expansion coefficient of the second material, α b Furthermore, in order to increase the amount of movement of the imaging element 31, the linear expansion coefficient α of the first material must be selected to be larger than a and the linear expansion coefficient α of the second material b The difference is 3.5 x 10 ―6 / °C or more.

[0036] Here, the linear expansion coefficient α is defined as the elongation rate per unit temperature change. If a solid sample with a length of L0 at a temperature of T0°C elongates by ΔL when heated to T1°C, the linear expansion coefficient α ( / °C) is (ΔL / L0) {1 / (T1-T0)}.

[0037] In order to reduce the variation in the amount of deformation caused by the variations in the shape and physical properties of the individual parts, the linear expansion coefficient α of the first material is a is 14.0 x 10 ―6 / ℃ or more 24.0×10 ―6 / °C or less. From the same viewpoint, the linear expansion coefficient α of the second material is preferably b is 9.9 x 10 ―6 / ℃ or more 20.5×10 ―6 / °C or less is preferable.

[0038] As will be described later, when there is the effect of solar radiation, the low thermal conductor 35 functions to create a difference in the amount of temperature rise between the first element holder component 33A and the second element holder component 33B. To effectively perform this function, it is desirable that the thermal conductivity of the low thermal conductor 35 be 0.5 W / m°C or less, and preferably 0.4 W / m°C or less.

[0039] Next, a method for fixing the imaging element 31 to the imaging element holder 33 will be described with reference to Fig. 5. Fig. 5(a) is a front view showing the state in which the imaging element 31 is fixed to the imaging element holder 33, and Fig. 5(b) is a cross-sectional view taken along line A-A in Fig. 5(a).

[0040] The imaging unit 300 is assembled into the imaging element holder 33 from the rear side so that the imaging element 31 fits into the opening 33B1 of the second element holder part 33B. When assembling the imaging element 31 into the imaging element holder 33, the imaging element holder 33 is fixed, and a position adjustment jig is used to adjust the center of the imaging surface in the imaging element 31 to approximately align with the center of the opening 33B1 provided in the second element holder part 33B.

[0041] After the position adjustment is complete, adhesive 50 is filled into the space between the side surfaces 31a and 31b of the imaging element 31 and the protrusions 33B2 and 33B3 inclined a predetermined amount toward the rear surface in the optical axis direction, and then cured. The imaging element 31 is fixed to the imaging element holder 33 by the adhesive 50. Since the imaging element 31 is inserted into the imaging element holder 33 from the rear surface side and the side surfaces 31a and 31b of the imaging element 31 are adhesively held in place, the second element holder part 33B is shaped so as not to overlap with the imaging element 32 in the optical axis direction.

[0042] As will be described later, the amount of deformation of the imaging element holder 33 varies depending on the thickness of the first element holder part 33A and the second element holder part 33B. In other words, by changing the thickness of the first element holder part 33A and the second element holder part 33B, it is possible to design an imaging element holder 33 that allows a desired amount of deformation.

[0043] By configuring the protrusions 33B2 and 33B3 to adhere to the imaging element 31, it is possible to ensure a sufficient adhesion area between the second element holder 33B and the imaging element 31 regardless of the thickness of the second element holder part 33B. In other words, it is possible to ensure the impact resistance of the imaging unit 300. Furthermore, when the adhesive 50 hardens, the protrusions 33B2 and 33B3 of the second element holder 33B deform, thereby alleviating the stress acting on the imaging element 31 and suppressing deformation of the imaging element 31.

[0044] The protrusions 33B2 and 33B3 are preferably shaped to be inclined a predetermined amount toward the rear surface with respect to the optical axis. This causes the space between the side surfaces 31a and 31b of the imaging element 31 and the protrusions 33B2 and 33B3 to gradually narrow toward the rear surface. This shape prevents the adhesive 50 from flowing toward the imaging element substrate 32. The adhesive 50 is preferably highly heat-resistant, and specifically, has a glass transition temperature (Tg) of 85°C or higher.

[0045] Next, a method for attaching barrel unit 100 to housing 200 and a method for fixing imaging unit 300 to housing 200 will be described with reference to Fig. 6. Fig. 6(a) is a rear view of housing 200, Fig. 6(b) is a cross-sectional view of barrel unit 100 fixed to housing 200, and Fig. 6(c) shows the state when imaging unit 300 is incorporated into housing 200 and then bonded and fixed with adhesive 51.

[0046] The rear side of housing 200 is provided with four adhesive grooves 200a into which adhesive 51 is filled to secure imaging unit 300. Lens-barrel unit 100 is fixed to housing 200 by threading male thread 10a provided on lens-barrel 10 into a female thread (not shown) provided on housing 200.

[0047] The imaging unit 300 is adjusted so that the imaging surface of the imaging element 31 is positioned within an allowable error range that ensures the desired imaging performance of the vehicle-mounted camera 1000, centered on the focal position of the lens barrel unit 100 incorporated in the housing 200. After the adjustment is complete, the imaging unit 300 is fixed to the housing 200 by filling and curing adhesive 51 into the space between the protrusions 33B5 and 33B6 provided on the second element holder 33B and the adhesive groove 200a provided on the housing 200. The adhesive 51 preferably has high heat resistance, and specifically, one with a glass transition temperature (Tg) of 85°C or higher is suitable.

[0048] Next, a method for assembling heat conducting member 400 will be described with reference to Fig. 7. Fig. 7 is a perspective view of camera module 600 (housing 500 is not shown).

[0049] Heat conduction member 400 has an adhesive layer on at least one side in the thickness direction. A portion of heat conduction member 400 is attached to first element holder component 33A via the adhesive layer, and another portion is attached to outer diameter portion 10b of barrel 10 via the adhesive layer. Heat conduction member 400 serves to transfer solar radiation energy irradiated onto barrel unit 100 to imaging unit 300. To achieve efficient transfer of solar radiation energy, it is preferable that the thermal conductivity of heat conduction member 400 (second thermal conductivity) be equal to or higher than the thermal conductivity of barrel 10 (first thermal conductivity).

[0050] Furthermore, it is desirable that the heat conduction member 400 be flexible so as not to inhibit the deformation (bending) of the image sensor holder 33. In this embodiment, the heat conduction member 400 has an adhesive layer and is attached to the first sensor holder part 33A and the outer diameter part 10b of the lens barrel 10 via the adhesive layer, but this is not limiting. The attachment method may be fixation with an adhesive or fixation by pressing a mechanical part or the like. The above-mentioned adhesive preferably has high thermal conductivity, specifically, one with a thermal conductivity of 1.5 W / m°C or more is suitable.

[0051] The materials used for the lens barrel 10 and the heat conduction member 400 are not particularly limited as long as they satisfy the above relationships, and various materials can be suitably used. As the material mainly constituting the lens barrel 10, a metal member such as an aluminum alloy can be used. The thermal conductivity of the aluminum alloy is approximately 130 to 230 (W / m·°C). As the material mainly constituting the heat conduction member 400, copper or a graphite sheet can be used. The thermal conductivity of copper is approximately 360 to 370 (W / m·°C). The thermal conductivity of the graphite sheet is as high as 700 to 1000 (W / m·°C) in the in-plane direction, but in the thickness direction, it is about 1 / 200 of that value, showing anisotropy in thermal conductivity. Therefore, when using a graphite sheet as the heat conduction member 400, it is preferable to arrange it so that heat is transferred in the in-plane direction of the sheet to thermally connect the lens barrel 10 and the first element holder component 33A. When configured as described above, since the second thermal conductivity is greater than the first thermal conductivity, excellent performance can be maintained even when back focus fluctuations occur due to ambient temperature changes and solar radiation effects.

[0052] Next, referring to FIG. 8, the deformed state of the image pickup element holder 33 and the movement in the optical axis direction of the image pickup element 31 due to environmental temperature changes and solar radiation effects, which are the features of the present invention, will be described. FIG. 8(a) is a cross-sectional view of the camera module 600 at an environmental temperature T0 when the solar radiation effect is negligibly small, and FIG. 8(b) is a cross-sectional view of the camera module 600 at an environmental temperature T1 (T0 < T1). P0 shown in FIG. 8(a) is the position in the optical axis direction of the imaging surface of the image pickup element 31 at the environmental temperature T0, and P1 shown in FIG. 8(b) is the position in the optical axis direction of the imaging surface of the image pickup element 31 at the environmental temperature T1. FIG. 8(c) is a cross-sectional view of the camera module 600 at an environmental temperature T1 when there is a solar radiation effect, and P' is the position in the optical axis direction of the imaging surface of the image pickup element 31. Hereinafter, the state of the environmental temperature T0 when the solar radiation state is negligibly small will be described as the "reference state".

[0053] First, referring to FIGS. 8(a) and 8(b), we will explain the behavior when the environmental temperature changes when the influence of solar radiation is negligible. When the environmental temperature rises from the reference state to T1, the first element holder part 33A and the second element holder part 33B each expand, but because they have different linear expansion coefficients, the expansion amounts differ. Because the first element holder part 33A and the second element holder part 33B are integrally formed, the difference in the expansion amounts causes deformation (bending) of the image sensor holder 33. Because the linear expansion coefficient αa of the first material and the linear expansion coefficient αb of the second material have the relationship αa > αb as described above, the image sensor holder 33 deforms so that the lens barrel unit 100 side becomes convex. Because the image sensor 31 is fixed to the image sensor holder 33 via adhesive, as the image sensor holder 33 deforms, the image sensor 31 moves in the optical axis direction and approaches the lens barrel unit 100. If the amount of movement of the imaging surface of imaging element 31 in the optical axis direction due to this change in environmental temperature is B, when the environmental temperature rises in a state where solar radiation is negligible, the imaging surface of imaging element 31 moves by B in the optical axis direction on the barrel unit 100 side. As a result, the position of the imaging surface of imaging element 31 changes from P0 to P1.

[0054] Next, referring to FIG. 8(c), behavior when solar radiation is present will be described. When solar radiation is present at ambient temperature T1, barrel unit 100 absorbs radiant energy from the sun, causing its temperature to rise compared to when solar radiation is not present. Because imaging unit 300 is connected to barrel unit 100 via thermally conductive member 400, some of the radiant energy absorbed by barrel unit 100 is transmitted, causing its temperature to rise compared to when solar radiation is not present. As the temperature of imaging unit 300 rises, the difference in the amount of expansion between first element holder component 33A and second element holder component 33B becomes greater than when solar radiation is not present. In other words, the amount of deformation of imaging element holder 33 also increases, and the amount of movement of imaging element 31 along the optical axis is greater than when solar radiation is not present. Let B' be the amount of movement of the imaging surface of imaging element 31 along the optical axis due to solar radiation. When the ambient temperature rises from the reference state to T1 and there is the effect of sunlight, the imaging surface of the imaging element 31 moves by B+B' in the optical axis direction on the barrel unit 100 side, and the imaging surface position of the imaging element 31 changes from P0 to P'.

[0055] As described above, the image sensor 31 moves in the optical axis direction due to deformation of the image sensor holder 33. The amount of movement of the image sensor 31 in the optical axis direction is proportional to the amount of deformation of the image sensor holder 33. The amount of deformation of the image sensor holder 33 can be changed by adjusting the linear expansion coefficient, thickness, fastening position, and elastic modulus of the first and second element holder components 33A and 33B. Therefore, the aforementioned movement amounts B and B' of the imaging surface of the image sensor 31 in the optical axis direction can be set arbitrarily. That is, by appropriately designing the movement amounts B and B' of the imaging surface of the image sensor 31 in the optical axis direction, taking into account the back focus fluctuations (Da and Ds) of the optical system due to changes in ambient temperature and solar radiation, it is possible to always maintain the imaging surface of the image sensor 31 within the aforementioned allowable error range. As a result, the vehicle-mounted camera 1000 can maintain excellent performance over a wide range of ambient temperatures and various solar radiation conditions.

[0056] In this embodiment, a low-thermal-conductivity member 35 is disposed between the first element holder component 33A and the second element holder component 33B. Due to the low-thermal-conductivity member 35, a difference in the amount of temperature rise between the first element holder component 33A and the second element holder component 33B occurs when exposed to sunlight, resulting in the first element holder component 33A always experiencing a larger amount of temperature rise. Because the linear expansion coefficient αa of the first material and the linear expansion coefficient αb of the second material are related by αa > αb, as described above, the difference in the amount of expansion between the first element holder component 33A and the second element holder component 33B is larger than when the low-thermal-conductivity member 35 is not present. As a result, the amount of movement of the image sensor 31 in the optical axis direction can be increased compared to when the low-thermal-conductivity member 35 is not present, thereby enabling the image sensor holder 33 to be made smaller, i.e., the camera module 600 to be made smaller. Furthermore, by connecting barrel unit 100 and imaging unit 300 with heat conduction member 400, it is possible to suppress the temperature rise of barrel unit 100 due to solar radiation and reduce the amount of back focus variation (Ds) due to solar radiation. As a result, it is possible to suppress the amount of deformation required for imaging element holder 33, and it is possible to reduce the size of imaging element holder 33, that is, the size of camera module 600.

[0057] The embodiments of the present invention are not limited to those described above, and may also be transportation equipment having a vehicle or moving body equipped with a camera module 600 and an information processing unit 700. FIG. 9 shows a schematic diagram of the configuration of the present invention. Transportation equipment is, for example, an automobile, a ship, or an aircraft. Transportation equipment 2000 of the present invention has an imaging unit 300 that deforms toward the lens as the ambient temperature rises, and imaging unit 300 and barrel unit 100 are connected by a heat conductive member 400. This allows images to be captured with high accuracy even in a wide range of ambient temperatures and various solar radiation conditions.

[0058] The disclosure of this embodiment includes the following configuration.

[0059] (Configuration 1) An imaging device comprising: a lens; a lens holding member having a first thermal conductivity and holding the lens; an imaging unit including an imaging element and an imaging element holder; and a housing containing the lens holding member and the imaging unit, the imaging unit is configured such that the position of the imaging element changes toward the lens as the temperature of the imaging element holder increases; The imaging device further includes a thermally conductive member having a second thermal conductivity housed in the housing, the second thermal conductivity being separate from the housing, a portion of which is connected to the imaging element holder and another portion of which is connected to the lens holding member, and the second thermal conductivity is equal to or greater than the first thermal conductivity.

[0060] (Configuration 2) The imaging device according to configuration 1, wherein the heat conducting member has an adhesive layer, and the heat conducting member is connected to the lens holding member and the imaging element holder via the adhesive layer.

[0061] (Configuration 3) The imaging device according to configuration 1, wherein the heat conducting member is adhered to the lens holding member and the imaging element holder with an adhesive.

[0062] (Configuration 4) The imaging device described in any one of configurations 1 to 3, characterized in that the imaging element holder includes, in order of proximity to the lens in an optical path direction along the optical axis of the lens, a first member including a first material and a second member including a second material different from the first material, and the first material has a linear expansion coefficient greater than that of the second material.

[0063] (Configuration 5) 5. The imaging device according to configuration 4, wherein the first member and the second member are joined at two or more locations.

[0064] (Configuration 6) The imaging device according to the fourth or fifth aspect, wherein the first member and the second member are joined by at least one of screw fastening, caulking, welding, melt-adhesion, and adhesive. (Configuration 7) 7. The imaging device according to any one of configurations 4 to 6, wherein the thermally conductive member is connected to the first member.

[0065] (Configuration 8) The imaging device according to configuration 4, wherein a third member is disposed between the first member and the second member, and the thermal conductivity of the third member is 0.5 W / m·°C or less.

[0066] (Configuration 9) 9. The imaging device according to any one of configurations 1 to 8, further comprising a housing that holds the lens holding member and the imaging element holder.

[0067] (Configuration 10) 10. The imaging device according to configuration 9, wherein the housing holds the imaging element holder via a resin material having a glass transition temperature (Tg) of 85° C. or higher.

[0068] (Configuration 11) 9. The imaging device according to any one of configurations 4 to 8, wherein the first member is covered with a material different from the first material.

[0069] (Configuration 12) 12. The imaging device according to any one of configurations 1 to 11, wherein the heat conducting member includes a copper or graphite sheet.

[0070] (Configuration 13) 13. The imaging device according to any one of configurations 1 to 12, wherein the lens holding member includes an aluminum alloy.

[0071] (Configuration 14) 14. An in-vehicle camera comprising: the imaging device according to any one of configurations 1 to 13; and an information processing unit that processes an electrical signal photoelectrically converted by the imaging element.

[0072] (Configuration 15) 14. A transportation device comprising: the imaging device according to any one of configurations 1 to 13; an information processing unit that processes an electrical signal photoelectrically converted by the imaging element; and a vehicle body or a moving body. [Explanation of symbols]

[0073] 10 Telescope tube 11, 12, 13, 14 Lenses 15, 16, 17 spacers 18 Retaining ring 30 cover slips 31 Image sensor 32 Image sensor board 33 Image sensor holder 33A First element holder part 33B Second element holder part 35 Low thermal conductivity materials 50, 51 Adhesive 100 Telescope unit 200 Housing 300 Imaging unit 400 Thermal Conductive Materials 500 cabinets 600 Camera Module 700 Information Processing Department 1000 in-car cameras 2000 Transportation equipment

Claims

1. An imaging device comprising: a lens; a lens holding member having a first thermal conductivity and holding the lens; an imaging unit including an imaging element and an imaging element holder; and a housing containing the lens holding member and the imaging unit, the imaging unit is configured such that the position of the imaging element changes toward the lens as the temperature of the imaging element holder increases; The imaging device further comprises a thermal conductive member having a second thermal conductivity housed in the housing, separate from the housing, a portion of which is connected to the element holder and another portion of which is connected to the lens holding member, the second thermal conductivity being equal to or greater than the first thermal conductivity.

2. 2. The imaging device according to claim 1, wherein the heat conducting member has an adhesive layer, and the heat conducting member is connected to the lens holding member and the element holder via the adhesive layer.

3. 2. The imaging device according to claim 1, wherein the heat conducting member is bonded to the lens holding member and the element holder with an adhesive.

4. The imaging device described in claim 1, characterized in that the imaging element holder includes, in order of proximity to the lens in an optical path direction along the optical axis of the lens, a first member including a first material and a second member including a second material different from the first material, and the first material has a linear expansion coefficient greater than that of the second material.

5. 5. The imaging device according to claim 4, wherein the first member and the second member are joined at two or more locations.

6. 5. The imaging device according to claim 4, wherein the first member and the second member are joined by at least one of screw fastening, caulking, welding, melt-adhesion, and adhesive.

7. 5. The imaging device according to claim 4, wherein the thermally conductive member is connected to the first member.

8. 5. The imaging device according to claim 4, wherein a third member is disposed between the first member and the second member, and the thermal conductivity of the third member is 0.5 W / m.degree. C. or less.

9. 2. The imaging device according to claim 1, further comprising a housing for holding the lens holding member and the imaging element holder.

10. 10. The imaging device according to claim 9, wherein the housing holds the imaging element holder via a resin material having a glass transition temperature (Tg) of 85[deg.] C. or higher.

11. 5. The imaging device according to claim 4, wherein the first member is covered with a material different from the first material.

12. 2. The imaging device according to claim 1, wherein the heat conducting member includes a copper or graphite sheet.

13. The imaging device according to claim 1 , wherein the lens holding member includes an aluminum alloy.

14. 14. An on-vehicle camera comprising: the imaging device according to claim 1; and an information processing unit that processes an electric signal photoelectrically converted by the imaging element.

15. 14. A transportation device comprising: the imaging device according to claim 1; an information processing unit that processes an electric signal photoelectrically converted by the imaging element; and a vehicle body or a moving body.

Images