Lens unit and camera module

Abstract

To provide a lens unit with snow melting capability without increasing the size.SOLUTION: A lens unit 100 provided herein comprises a cylindrical lens barrel 10, multiple lenses 1-4 arranged on the inside of the lens barrel 10 along an axis of the lens barrel 10, and a heater unit 40 provided between a flange portion (flat portion) 1b of a lens 1 located on the most object side in the lens barrel 10 and a flange portion (flat portion) 2b of a lens 2 located next to the lens 1, the heater unit being configured to generate heat when energized.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lens unit and a camera module. [Background technology]

[0002] Cameras installed outdoors, such as surveillance cameras and in-vehicle cameras, are well known. In cameras installed outdoors, ice and snow can accumulate on the front of the lens during snowfall. Furthermore, when the outside temperature drops below freezing, the front of the lens can freeze and form frost. In this case, the accumulation of snow on the front of the lens can blur the captured image, reducing the camera's imaging performance.

[0003] In recent years, cameras (on-board cameras) have been installed in vehicles, and images captured by on-board cameras are used for functions such as automatic braking and automatic driving. These functions control the driving of the vehicle, and a decline in the imaging function of the on-board camera may lead to accidents or the like. Therefore, there is a demand for the development of a camera equipped with a snow melting function that melts deposits adhering to the front of the lens. An example of a camera equipped with a snow melting function is disclosed in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-10983 Summary of the Invention [Problem to be solved by the invention]

[0005] The camera disclosed in Patent Document 1 contains a CCD, circuit elements, and other components that generate heat during operation. The camera is equipped with a fan that circulates air inside the camera to prevent condensation on the cover glass installed in front of the lens. However, the camera's fan-equipped design increases its size, which is problematic. As a result, the camera cannot be installed in vehicles and other vehicles where installation space is limited.

[0006] The present invention has been made in view of the above circumstances, and has as its object to realize a lens unit and a camera module that have a snow-melting function without increasing the size. [Means for solving the problem]

[0007] In order to solve the above problems, the lens unit of the present invention comprises: A lens unit comprising: a cylindrical lens barrel; and a plurality of lenses arranged in a line along an axial direction of the lens barrel on an inner peripheral side of the lens barrel, A heater section that generates heat when electricity is applied is provided between a flat section of a first lens that is positioned closest to the object side of the lens barrel and a flat section of a second lens that is adjacent to the first lens.

[0008] With this configuration, a heater portion is provided between the flat portion of the first lens and the flat portion of the second lens, so that a lens unit with a snow-melting function can be realized without increasing the size.

[0009] In the above-described configuration of the present invention, the heater portion includes a conductive carbon film having a temperature self-regulating function and a light-shielding function, and a circuit pattern for energizing the conductive carbon film. With this configuration, a lens unit including a heater portion having a temperature self-regulating function and a light-shielding function can be realized without increasing the size.

[0010] In the above-described configuration of the present invention, the circuit pattern is characterized in that it has a comb shape with a plurality of protrusions that protrude radially and are evenly spaced along the circumferential direction. With this configuration, the entire heater generates heat uniformly, thereby achieving an even snow melting function and more reliably preventing a decrease in imaging performance.

[0011] In the above-described configuration of the present invention, the heater section includes a flexible substrate on which a heater circuit is formed, and a thermistor mounted on the flexible substrate and having a self-temperature control function. With this configuration, a lens unit equipped with a heater section having a self-temperature control function can be realized without increasing the size.

[0012] In the above-described configuration of the present invention, the heater section includes a flexible substrate, a conductive carbon film formed on the flexible substrate and having a temperature self-regulating function and a light-blocking function, and a circuit pattern electrically connected to the flexible substrate and passing a current through the conductive carbon film. With this configuration, a lens unit including a heater section having a temperature self-regulating function and a light-blocking function can be realized without increasing the size.

[0013] In the above-described configuration of the present invention, the circuit pattern is characterized in that it has a comb shape having a plurality of protrusions that protrude radially and are equally spaced along the circumferential direction. With this configuration, the entire heater generates heat uniformly, thereby realizing a snow melting function without bias and more reliably preventing a decrease in imaging performance.

[0014] In the above-described configuration of the present invention, the heater portion is made of ceramics having a self-temperature control function. With this configuration, a lens unit having a heater portion with a self-temperature control function can be realized without increasing the size.

[0015] In addition, in the above-described configuration of the present invention, the heater unit has a PTC characteristic and a Curie point temperature of 80°C or higher and 120°C or lower. Because the Curie point temperature is 80°C or higher and 120°C or lower, the first lens located on the object side of the heater unit can be heated in a short time after the start of power supply, thereby achieving snow melting. Furthermore, deformation of the second lens located on the image side of the heater unit due to the heater unit becoming too hot can be prevented. This prevents a deterioration in optical performance due to deformation of the second lens.

[0016] In the above-described configuration of the present invention, the heater section is formed in an annular shape and includes an inner electrode pattern provided along the inner periphery and side surface of the image-side surface of the heater section, and an outer electrode pattern provided along the outer periphery and side surface of the image-side surface of the heater section, with conductors bonded to the ends of the inner electrode pattern and the outer electrode pattern, respectively. This configuration can increase the contact area between the electrode patterns and the heater section, thereby enabling more efficient heating of the heater section.

[0017] In the above-described configuration of the present invention, the lens barrel has a through-hole through which the conductor connected to the heater unit is drawn to the outside of the lens barrel through an opening provided on the outer surface of the lens barrel, and the conductor is fixed to the opening on the outer surface of the lens barrel with adhesive or a fixing member. Because the conductor is fixed to the opening with adhesive or a fixing member, even if the conductor is pulled, force is prevented from being applied to the joint between the conductor and the heater unit, thereby improving the conductor's resistance to pulling. This prevents the conductor from coming off the heater unit even if the conductor is pulled during the manufacturing process of the camera module.

[0018] In addition, in the above-described configuration of the present invention, the through holes are provided in two locations, and one of the conductors is inserted into each of the through holes. With this configuration, since the through holes are provided in two locations, it is possible to prevent the outer peripheral surface of the lens barrel on which the lenses are arranged from easily bending radially outward. This prevents the problem of water or the like entering the interior of the lens barrel, which would occur if, for example, the through hole were a single elongated hole, the outer peripheral surface of the lens barrel were easily bent radially outward.

[0019] In the above-described configuration of the present invention, the fixing member is formed in a substantially cylindrical shape and is inserted into the opening with the conductor wire passing through it. By using a substantially cylindrical fixing member, the conductor wire can be fixed even when a fluororesin wire such as PTFE is used as the conductor wire.

[0020] In the above-described configuration of the present invention, the fixing member is made of an elastically deformable material and is tapered so that the outer diameter decreases from one end to the other end, and is inserted into the opening from the end with the smaller outer diameter, and the inner diameter decreases when inserted into the opening. By using such a tapered, elastically deformable fixing member, when the fixing member is inserted into the opening, the inner diameter decreases and the conductor is tightened. This ensures that the conductor is securely fixed and prevents it from coming loose from the heater unit.

[0021] In addition, in the above-described configuration of the present invention, the heater section has a thickness such that the distance between the flat portion of the first lens and the flat portion of the second lens is 0.5 mm or less, and the plurality of lenses constitute an ultra-wide-angle lens with a horizontal angle of view exceeding 180°. With this configuration, it is possible to realize a high-performance ultra-wide-angle lens with a snow-melting function and a horizontal angle of view exceeding 180°.

[0022] A camera module of the present invention includes a lens unit having the above-described configuration and an image sensor that captures an image formed by the lens unit. With this configuration, the camera module can achieve the same effects as the lens unit of the present invention described above.

[0023] The camera module of the present invention also includes a lens unit having the above-described configuration, an image sensor for capturing an image formed by the lens unit, and a camera case that encloses the lens unit while exposing the object-side end of the lens unit. An O-ring is disposed between the camera case and a flange-shaped portion formed on the outer periphery of the lens barrel to form a seal, and the opening of the through-hole on the outer periphery of the lens barrel is located closer to the image side than the seal in the axial direction of the lens barrel. With this configuration, the opening of the through-hole on the outer periphery of the lens barrel is located closer to the image side than the seal, so that the opening is located inside the camera case, ensuring airtightness. This prevents water from entering the lens barrel through the opening, eliminating the need to insulate the heater. This reduces costs and improves productivity. [Effects of the Invention]

[0024] According to the present invention, it is possible to realize a lens unit and a camera module that have a snow-melting function without increasing the size. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a lens unit according to a first embodiment of the present invention. [Figure 2] 1A is a diagram illustrating the heater section, and FIG. 1B is a diagram illustrating the PTC function. [Figure 3] 10A and 10B are diagrams showing modified examples of the wiring portion of the same; [Figure 4]10(a) is a cross-sectional view showing a lens unit according to a second embodiment of the present invention, and (b) and (c) are diagrams for explaining the relationship between the holes and wiring inside the lens barrel. [Figure 5] FIG. 2 is a diagram for explaining a heater portion of the first embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a lens unit according to a third embodiment of the present invention. [Figure 7] FIG. 2 is a diagram for explaining a heater portion of the first embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing a lens unit according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example in which a cap is used in the lens unit according to the first to fourth embodiments. [Figure 10] FIG. 10 is a cross-sectional view showing a lens unit according to a fifth embodiment of the present invention. [Figure 11] 1A and 1B show the heater portion of the same, where (a) is a view from the image side, and (b) is a cross-sectional view taken along line GG shown in (a). [Figure 12] This is a graph showing the relationship between the current value supplied to the heater, the elapsed time from the start of power supply, and the surface temperature of the PTC heater and lens when the Curie point of the heater is 80°C and the environment is at room temperature. [Figure 13] This is a graph showing the relationship between the current value supplied to the heater, the elapsed time from the start of power supply, and the surface temperature of the PTC heater and lens in an environment where the Curie points of the heater are 80°C and -30°C. [Figure 14] This is a graph showing the relationship between the current value supplied to the heater, the elapsed time from the start of power supply, and the surface temperature of the PTC heater and lens when the Curie point of the heater is 120°C and the environment is at room temperature. [Figure 15] This is a graph showing the relationship between the current value supplied to the heater, the elapsed time from the start of power supply, and the surface temperature of the PTC heater and lens in an environment where the Curie points of the heater are 120°C and -30°C. [Figure 16]1A and 1B show axial cross-sectional views of a camera module equipped with a lens unit, where (a) is a cross-sectional view taken along a plane passing through a first through-hole, and (b) is a cross-sectional view taken along a plane passing through a second through-hole. [Figure 17] 1A is a diagram showing a part of the lens barrel as seen from the object side, and FIG. 1B is a diagram showing the lens barrel as seen from the side. [Figure 18] FIG. 10 is a side view of the lens unit with the lead wires drawn out. [Figure 19] 10 is an axial cross-sectional view of the lens unit in a state where a fixing member is inserted into the opening of the through-hole of the lens barrel. FIG. [Figure 20] 1A shows a first example of a fixing member, FIG. 1B shows a second example of a fixing member, and FIG. 1C shows a third example of a fixing member. DETAILED DESCRIPTION OF THE INVENTION

[0026] A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an axial cross-sectional view of a lens unit 100 according to a first embodiment. Hatching indicating a cross section is omitted in FIG. 1. The lens unit 100 forms an image of an object on the image side and is used, for example, in an in-vehicle camera. An example of an in-vehicle camera is one that is mounted on a side mirror of a vehicle and captures an image behind the vehicle. As shown in FIG. 1, the lens unit 100, together with a camera case 201, an O-ring 202, etc., constitutes a camera module 200.

[0027] As shown in FIG. 1, the lens unit 100 includes lenses 1 to 4, a lens barrel 10, an optical filter 20, an O-ring 30, a heater section 40, a wiring section 50, and the like.

[0028] Within the lens barrel 10, lenses 1 to 4 that make up one lens group are arranged along the axial direction of the lens barrel 10. The lenses 1 to 4 are arranged with their respective optical axes aligned and aligned along the optical axes. In this case, the axis of the lens barrel 10 and the optical axis of the lens group (referred to as the optical axis OA) are approximately aligned. Hereinafter, the term optical axis OA refers to the optical axis of each of the lenses 1 to 4 as well as the optical axis of the lens group.

[0029] Lens barrel 10 is disposed so that one end in the axial direction faces image sensor 91 as the image side, and the other end in the axial direction faces the object side as the image target. In this embodiment, the lens 4 side is the image side, and the lens 1 side is the object side.

[0030] Lenses 1 to 4 are arranged inside lens barrel 10 in the order of lens 1, lens 2, lens 3, and lens 4 from the object side to the image side. Optical filter 20 is arranged at the end of lenses 1 to 4 on the side where the image is formed (image side). Optical filter 20 is arranged for the purpose of removing specific frequency components.

[0031] The lens barrel 10 is cylindrical. The lens barrel 10 is made of resin. Note that a case where the lens barrel 10 is made of metal will be described later. The inner diameter of the lens barrel 10 decreases in stages from the object side to the image side. Here, the inner circumferential surfaces of the lens barrel 10 are referred to as inner circumferential surface A, inner circumferential surface B, inner circumferential surface C, inner circumferential surface D, and inner circumferential surface E, from the object side to the image side. The image-side portion of inner circumferential surface E is formed with a support portion 11, which is a portion that protrudes radially inward so that the inner diameter decreases. The support portion 11 is configured to abut against the image-side surface of a flange portion of the lens 4. The flange portion is a portion formed on the outer periphery of the lens effective diameter and has a flat portion.

[0032] Lens barrel 10 is provided with a holding portion 12 formed at the object-side end and abutting against the outer periphery of the object-side surface of lens 1. Holding portion 12 is a portion formed by caulking after components are housed inside lens barrel 10. The inner diameter of holding portion 12 is smaller than the outer diameter of lens 1. The components housed inside lens barrel 10 are supported by being sandwiched between support portion 11 and holding portion 12. In other words, the components housed inside lens barrel 10 are held in a state where they are pressed against support portion 11 by holding portion 12. This prevents gaps from being formed between the components.

[0033] Lenses 1 to 4 are circular lenses that are fitted into lens barrel 10. Lens 1 is made of glass, and lenses 2 to 4 are made of resin. Lenses 1 to 4 are positioned in a direction perpendicular to the optical axis OA by having their outer circumferential surfaces abut against the inner circumferential surface of lens barrel 10.

[0034] A reduced diameter portion 1c, which is a portion formed with a smaller diameter than other portions, is formed on the image side of the outer peripheral surface of lens 1. An O-ring 30 is disposed between reduced diameter portion 1c and inner peripheral surface A of lens barrel 10. O-ring 30 is made of rubber and seals the gap, preventing water, dust, etc. from entering the interior of lens barrel 10.

[0035] A flange portion 13, which is a plate-like portion that protrudes radially outward, is formed on the outer peripheral surface of lens barrel 10. Camera case 201 is made up of upper camera case 201a and lower camera case 201b, and is shaped to cover the rest of lens unit 100 while exposing the object side end of lens unit 100 to the outside through a circular opening. O-ring 202 is made of rubber, and is arranged between the outer peripheral surface of lens barrel 10, flange portion 13 of lens barrel 10, and the inner peripheral surface of camera case 201 to ensure airtightness inside camera case 201.

[0036] The lens 1 (first lens) has a lens portion 1a and a flange portion 1b. The flange portion (flat portion) is a portion formed on the outer periphery of the lens effective diameter and has a flat surface. The flange portion 1b has a flat surface on the image side. The lens 2 (second lens) has a lens portion 2a and a flange portion 2b. The flange portion 2b has flat portions on the object side and the image side. A heater section 40, which will be described later, is provided on the image-side surface of the flange section 1b of the lens 1. A part of the image-side surface of the heater section 40 is in contact with the object-side surface of the flange section 2b of the lens 2. In other words, the heater section 40 is provided at a position between the flange section 1b of the lens 1 and the flange section 2b of the lens 2. The heater section 40 is provided at a position that does not affect the imaging performance of the lens unit 100.

[0037] FIG. 2(a) is a diagram for explaining the heater section 40. As shown in FIG. The heater portion 40 is made up of a conductive carbon film 41 and a circuit pattern 42. The conductive carbon film 41 is applied to the image side of the flange portion 1b of the lens 1. Note that the conductive carbon film 41 may also be printed on that location.

[0038] The circuit pattern 42 is printed on the conductive carbon film 41 on the flange portion 1b of the lens 1. The printing is performed, for example, by a screen printer. The circuit pattern 42 is a circular electrode and includes an outer circumferential circuit pattern 43 and an inner circumferential circuit pattern 44. The circuit pattern 42 passes electricity through the conductive carbon film 41. The outer circumferential circuit pattern 43 includes multiple protrusions 43a protruding radially inward and formed in a comb shape. The inner circumferential circuit pattern 44 includes multiple protrusions 44a protruding radially outward and formed in a comb shape. The multiple protrusions 43a and the multiple protrusions 44a are formed alternately and at equal intervals along the circumferential direction. The outer circumferential circuit pattern 43 and the inner circumferential circuit pattern 44 are formed so that the distance between the electrodes is constant. This ensures a constant current value across the entire surface. This prevents temperature unevenness when the conductive carbon film 41 generates heat, resulting in a uniform temperature distribution. The occurrence of temperature unevenness when the conductive carbon film 41 generates heat affects the symmetry of the optical performance, resulting in deterioration of the optical performance, so it is preferable that the circuit pattern 42 has a symmetrical shape except for the ends.

[0039] The heater section 40 is formed as follows. First, 60 wt % of EVA (a vinyl acetate and polyethylene copolymer) with a vinyl acetate content of 17 wt % and 40 wt % of carbon black are kneaded for about 10 minutes while heating to a temperature of 120°C to obtain a mixture X. For example, a planetary mixer is used for the kneading.

[0040] Next, the mixture X is dispersed and stirred using a tetralin solvent, and diluted to a solvent viscosity of 3500 centipoise to obtain an ink Y.

[0041] Next, while rotating the lens 1 using a glass lens ink coater, ink Y is applied to the image side of the flange portion 1b of the lens 1 to a thickness of 15 μm. After application, the ink Y is dried. This forms a conductive carbon film 41.

[0042] Next, using the blackened surface (conductive carbon film 41) of the lens 1 as a base, a screen printer is used to print silver paste in a comb-shaped pattern, thereby forming a circuit pattern 42 that is a comb-shaped electrode.

[0043] The conductive carbon film 41 has a conductive function and generates heat when electricity is passed through it. That is, the conductive carbon film 41 has a heater function. The conductive carbon film 41 also has a light-shielding function, preventing unwanted light that causes ghosts and flares from entering the interior of the lens barrel 10.

[0044] Furthermore, the conductive carbon film 41 has a PTC (Positive Temperature Coefficient) function, that is, a self-temperature control function, so that the heating temperature can be kept constant. Figure 2(b) is a diagram illustrating the PTC function. At normal temperatures (including low temperatures), the carbon black particles are in close contact with each other, resulting in low resistance and allowing current to flow smoothly. However, as the temperature rises, the EVA expands, separating the carbon black particles and causing them to come out of contact. This increases resistance, making it difficult for current to flow, and the temperature rise stops. When the temperature drops back down from the high temperature to normal, the EVA contracts, allowing current to flow again. This cycle is repeated to maintain a constant heating temperature. PTC materials with PTC function are not limited to the organic materials shown in Figure 2(b). Inorganic materials, such as ceramics containing additives such as rare earth elements added to barium titanate, can also be used. Materials with PTC function exhibit a rapid increase in resistance when the temperature rises above a certain level, starting from room temperature (25°C). The temperature at which this increase begins is called the Curie temperature (Tc), and is defined as the temperature at which the resistance doubles from that at 25°C.

[0045] Returning to FIG. 1, the wiring section 50 will be described. The wiring section 50 is provided to supply power to the heater section 40. The wiring section 50 is made up of a spring member 51 and a conductor 52. In this embodiment, two spring members 51 are used, and the spring members 51 are connected to an end 43b of the outer circumferential circuit pattern 43 and an end 44b of the inner circumferential circuit pattern 44 shown in FIG. 2, respectively.

[0046] The spring member 51 is made of phosphor bronze and is electrically conductive. The spring member 51 also has elasticity. The end of the spring member 51 opposite to the end connected to the circuit pattern 42 is connected to a conductor 52 (shown in FIG. 1). The conductor 52 is a metal wire for carrying electric current, and is covered with PVC (polyvinyl chloride). The covering material may be PTFE (fluororesin), which has excellent heat resistance.

[0047] Next, the wiring of the wiring section 50 will be described. Step portion 15, which is a stepped surface in the axial direction, is formed at the boundary between inner peripheral surface A and inner peripheral surface B of lens barrel 10. Step portion 15 of lens barrel 10 has hole 14, which is formed parallel to the axial direction of lens barrel 10, connecting the inside of lens barrel 10 with the outside of lens barrel 10. Hole 14 is provided to guide conducting wire 52 into the inside of lens barrel 10.

[0048] The opening of hole 14 on the exterior side of lens barrel 10 is located in the axial direction of lens barrel 10 closer to the image side than the seal between camera case 201 and O-ring 202. Because the interior of camera case 201 is airtight, water will not enter the interior of lens barrel 10 through hole 14. This eliminates the need to insulate heater section 40.

[0049] Conductive wire 52 is led from the outside of barrel 10 to the inside of barrel 10 via hole 14, and one end is connected to spring member 51. Although not shown, the other end of conductive wire 52 is connected to wiring board 92 which is equipped with a power supply circuit to heater section 40. Wiring board 92 is configured to be provided on the camera case 201 side.

[0050] During assembly, lenses 2 to 4 are inserted into lens barrel 10, and then lens 1, on which heater portion 40 is formed, is installed inside lens barrel 10. Spring member 51 is embedded in lens barrel 10 and electrically connects to heater portion 40 of lens 1. Spring member 51 is connected to conductor 52, which is led out to the outside of lens barrel 10 through hole 14 in lens barrel 10. This electrically connects the inside and outside of lens barrel 10. When the lens 1 is assembled into the lens barrel 10, the spring member 51 and the heater portion 40 of the lens 1 come into mechanical contact and are electrically connected. This eliminates the need for troublesome wire connection work, improving assembly efficiency.

[0051] In the above, a case where the spring member 51 is used to connect the circuit pattern 42 and the conductor 52 has been described. In other words, a case where the wiring section 50 is made up of the spring member 51 and the conductor 52 has been described. However, this is not limiting, and the wiring section 50 may be made up of only the conductor 52. FIGS. 3(a) and 3(b) are diagrams showing a case where the wiring section 50 is made up of only the conductor 52. In this case, the ends 43b and 44b of the circuit pattern 42 are connected to the conductor 52 by soldering or by an anisotropic conductive film (ACF).

[0052] Camera module 200 includes lens unit 100, camera case 201, O-ring 202, imaging element 91 (image sensor), wiring board 92, signal processing circuit, flexible wiring sheet, connector, etc. Camera module 200 refers to a module including at least lens unit 100 and imaging element 91. Imaging element 91 is provided on the camera case 201 side. Imaging element 91 is arranged on the image side of lens unit 100, and is configured to capture an image formed by lens unit 100.

[0053] Camera module 200 operates as follows: Light incident from the object side is incident on image sensor 91 via the lens group of lens unit 100. Image sensor 91 converts the incident image into an electrical signal. A signal processing circuit performs signal processing (A / D conversion, image correction processing, etc.) on the electrical signal from image sensor 91. The electrical signal output from the signal processing circuit is connected to an external electronic device via a flexible wiring sheet and a connector.

[0054] When power is supplied to the heater unit 40 via the wiring unit 50, the heater unit 40 generates heat due to the current flow. The heat from the heater unit 40 is transferred to the lenses 1 and 2. When the temperature of the lens 1 rises, the ice, snow, or frost adhering to the object-side surface of the lens 1 (the front surface of the lens 1) melts. Lens 1 is made of glass and has a thermal conductivity of 0.5 (W m -1 ·K -1 ) or more 1.5 (W m -1 ·K -1 ) or less. On the other hand, lens 2 is made of plastic and has a thermal conductivity of 0.5 (W m -1 ·K -1 ) or less. That is, lens 1 is configured to have a higher thermal conductivity than lens 2. Heater section 40 can efficiently transfer heat to the object side and efficiently melt ice, snow, and frost adhering to lens 1.

[0055] According to this embodiment, a heater section 40 that generates heat when electricity is applied is provided inside the lens barrel 10, between the flange section 1b of the lens 1 and the flange section 2b of the lens 2, so that the snow melting function can be achieved without increasing the size of the lens unit 100 (camera module 200).

[0056] Furthermore, since the captured image will not become unclear due to snow or the like adhering to the lens 1, it is possible to prevent a decrease in the imaging performance of the lens unit 100. Therefore, for example, when the lens unit 100 is used in an in-vehicle camera, it is possible to prevent snow or the like adhering to the front surface of the lens 1 from affecting the automatic braking function, automatic driving function, etc. of the vehicle. This makes it possible to provide a comfortable drive for the driver and ensure the safety of the passengers.

[0057] Next, a second embodiment of the present invention will be described. Figure 4(a) is an axial cross-sectional view of a lens unit 300 according to the second embodiment. Note that in Figure 4(a), some of the hatching indicating a cross section has been omitted. Hereinafter, components that have the same or corresponding functions as those described in the first embodiment will be assigned the same reference numerals, and their description will be omitted or simplified.

[0058] The lens unit 300 includes a heater section 60. The heater section 60 is sandwiched between the lens 1 and the lens 2.

[0059] 5(a) and 5(b) are diagrams for explaining the heater section 60. The heater section 60 includes an FPC (Flexible Printed Circuits) 61 and a thermistor 62. The FPC 61 is a flexible substrate. The material of the FPC 61 is a PET film or a polyimide film. The FPC 61 is a film on which an electric circuit is wired.

[0060] As shown in FIG. 5(b), the FPC 61 includes an annular portion 61A, a linear portion 61B, and an FPC connector portion 61C. A heater circuit 63 and a thermistor circuit 64 are formed on the annular portion 61A and the linear portion 61B. The heater circuit 63 and thermistor circuit (wiring) 64 are made of materials with a predetermined resistance value and generate heat when current is applied. In this embodiment, the heater circuit 63 and thermistor circuit 64 are formed by printing silver paste using a screen printer. The heater circuit 63 on the annular portion 61A is formed with a narrow line width to increase resistance so that it functions as a heater. Meanwhile, the heater circuit on the linear portion 61B is formed with a wide line width to decrease resistance and reduce heat generation. While silver paste is used as the material in this embodiment, carbon paste may also be used. To improve the accuracy of the circuit pattern, a composite film, for example, made by bonding copper foil, aluminum foil, stainless steel foil, or the like to a polyimide film, may be etched into the desired circuit pattern. The Curie temperature of the heater section 60 configured as above is defined as the entirety of the heater circuit 63, thermistor circuit (wiring) 64, and thermistor 62. That is, when the resistance starts from room temperature (25°C) and the temperature rises above a certain value, the resistance suddenly increases, and the Curie temperature is defined as the temperature at which the resistance becomes twice the resistance at 25°C.

[0061] The thermistor 62 is an electronic component with a PTC function, and is an element whose electrical resistance increases rapidly with an increase in temperature, exhibiting a positive temperature coefficient. The thermistor 62 has a substantially constant resistance value near room temperature, but the resistance value increases rapidly above a certain temperature. The thermistor 62 generally achieves this characteristic by adding a small amount of a bright earth element to barium titanate.

[0062] Chip-type thermistors 62 are widely used. Thermistors 62 detect the ambient temperature, and when a certain temperature is reached, their resistance increases rapidly, reducing the current flowing through the heater circuit 63. Thermistors 62 with this characteristic are used in constant-temperature heating elements, heaters, and the like. Thermistors 62 make it possible to maintain a constant temperature without the need for ON / OFF control. For example, by inserting thermistor 62 in series with heater circuit 63, the current flowing through heater circuit 63 can be controlled without the need for a control circuit. In this embodiment, for proper temperature management, thermistor 62 is disposed in annular portion 61A and mounted on thermistor circuit (wiring) 64. Alternatively, a method is possible in which the voltage across the thermistor 62 is monitored by a monitor circuit, and the output of the monitor circuit is A / D converted by a control circuit and input to an internal microcomputer, thereby controlling the voltage to be applied to the heater circuit 63. This allows for highly accurate temperature control. Note that the control circuit may be configured with an analog circuit rather than a digital circuit. In such an embodiment configured with a monitor circuit and control circuit, the predetermined temperature below which temperature control is performed is considered to be the Curie temperature.

[0063] In this embodiment, wiring section 50 is formed by straight section 61B of FPC 61. An FPC connector section 61C is provided at the end of FPC 61 that is exposed to the outside of lens barrel 10. FPC connector section 61C is connected to a heater control section (not shown) that is formed on the camera case 201 side. Power is supplied to heater circuit 63 and thermistor circuit 64 via FPC connector section 61C.

[0064] Returning to FIG. 4(a), the wiring of the wiring section 50 will be described. Step portion 15 in lens barrel 10 has hole 16, which connects the inside of lens barrel 10 with the outside of lens barrel 10, formed parallel to the axial direction of lens barrel 10. Hole 16 is provided to guide a thin, flat film-like FPC 61 into the inside of lens barrel 10. The opening of hole 16 on the outside side of lens barrel 10 is located on the image side, in the axial direction of lens barrel 10, of the seal portion between camera case 201 and O-ring 202. Because the inside of camera case 201 is airtight, water will not enter the inside of lens barrel 10 through hole 16. This eliminates the need to insulate heater portion 60.

[0065] 4(b) and 4(c) are diagrams for explaining the relationship between hole 16 and FPC 61. Hole 16 has first and second flat portions 16a and 16b that are parallel to each other. As shown in FIG. 4(b), point M is a point on the surface of step portion 15 that is in the center of first flat portion 16a in the width direction. First flat portion 16a is formed on the surface of step portion 15 so as to be perpendicular to the line segment connecting the center of lens barrel 10 and point M. The width of the hole 16 is determined to match the width of the wiring portion 50 (FPC 61), so that the hole 16 allows the FPC 61 to pass through.

[0066] When passing the FPC 61 through the hole 16, the FPC 61 is passed along the first and second flat portions 16a and 16b of the lens barrel 10 and then bent at an approximately right angle at the end of the first flat portion 16a. The FPC 61 abuts against the end of the first flat portion 16a and is bent at an approximately right angle, electrically connecting the inside and outside of the lens barrel 10 through the hole 16. By providing the hole 16, power can be supplied via the FPC 61 to the limited space inside the lens barrel 10. This configuration allows the FPC 61 to pass through the minimum space in the lens barrel 10, thereby achieving a compact design. In addition, an O-ring 30 is disposed between the outer periphery of the lens 1 and the inner circumferential surface of the lens barrel 10. The O-ring 30 is compressed radially to ensure airtightness. However, by minimizing the size of the hole 16, the inner diameter of the lens barrel 10 can be prevented from expanding due to the repulsive force of the O-ring 30, thereby maintaining airtightness.

[0067] Next, the mounting location of the thermistor 62 will be described. As shown in Fig. 5(a), the thermistor 62 is mounted on the image-side surface of the annular portion 61A of the FPC 61. As shown in Fig. 4(a), the thermistor 62 is positioned radially inside the outer diameter of the lens 1 and outside the outer diameter of the lens 2. The diameter of the lens 2 is smaller than the diameter of the lens 1. The thermistor 62 is positioned axially within the range of the thickness of the lens 2.

[0068] 4(b), lens barrel 10 is provided with recess 17, which is a concave shape for accommodating thermistor 62, at a position facing thermistor 62. Thermistor 62 is accommodated inside recess 17 without interfering with lens barrel 10. This allows thermistor 62 to be mounted in a space-saving manner without increasing the size of lens barrel 10. In other words, this configuration in which recess 17 is provided to accommodate thermistor 62 contributes to the realization of compact lens unit 300 and camera module 200.

[0069] In an ultra-wide-angle lens, to ensure a horizontal angle of view exceeding 180°, the distance (gap) between the flange portion 1b of lens 1 and the flange portion 2b of lens 2 is preferably 0.05 mm or more and 0.5 mm or less. If this distance exceeds 0.5 mm, the horizontal angle of view will be less than 180°, making it difficult to achieve an ultra-wide angle. On the other hand, if this distance is less than 0.05 mm, it will be difficult to sandwich the heater portion 60 between the lens 1 and the lens 2. In this embodiment, the thickness of the heater portion 60 in the axial direction is approximately 0.2 mm, and the distance is 0.5 mm or less, ensuring a horizontal angle of view exceeding 180°.

[0070] The heater unit 60 is in contact with the lens 1 and the lens 2. When power is supplied to the heater unit 60 via the wiring unit 50, the heater unit 60 generates heat as a result of the current flow. The heat from the heater unit 60 is transferred to the lens 1 and the lens 2. When the temperature of the lens 1 rises, the ice, snow, or frost adhering to the object-side surface of the lens 1 (the front surface of the lens 1) melts.

[0071] In this embodiment, a black coating is applied to the image-side surface of the flange portion 1b of the lens 1 to achieve a light-blocking function. For example, black paint is used for the black coating.

[0072] In the above, the heater unit 60 is sandwiched between the lens 1 and the lens 2, but the heater unit 60 may also be attached to the lens 1 via an adhesive or the like having high thermal conductivity.

[0073] According to this embodiment, as with the first embodiment, a snow melting function can be achieved without increasing the size of the lens unit 300 (camera module 200). Furthermore, since the captured image is not blurred due to snow or the like adhering to the lens 1, a decrease in the imaging performance of the lens unit 300 can be prevented. Furthermore, by configuring a heater unit 60 including a thermistor 62 inside the lens barrel 10, a heater unit 60 with a PTC function can be achieved without increasing the size. Because the heater unit 60 has this PTC function, it is controlled to a constant temperature simply by being energized without requiring any special control.

[0074] Furthermore, since the thickness of the heater section 60 located between the lens 1 and the lens 2 is set to 0.5 mm or less, it is possible to realize an ultra-wide-angle lens with a horizontal angle of view exceeding 180° while still including the heater section 60.

[0075] Next, a third embodiment of the present invention will be described. Figure 6 is an axial cross-sectional view of a lens unit 400 according to the third embodiment. Note that hatching indicating a cross section has been partially omitted in Figure 6. Hereinafter, components that have the same or corresponding functions as those described in the first and second embodiments will be given the same reference numerals, and their description will be omitted or simplified.

[0076] The lens unit 400 includes a heater section 70. The heater section 70 is sandwiched between the lens 1 and the lens 2.

[0077] 7(a) and 7(b) are diagrams for explaining the heater section 70. FIG. The heater unit 70 includes an FPC 61 made of a PET film, a conductive carbon film 41, and a circuit pattern 42. The FPC 61 includes an annular portion 61A, a linear portion 61B, and an FPC connector portion 61C. The conductive carbon film 41 is printed on the annular portion 61A, and a comb-shaped circuit pattern 42 is printed on the conductive carbon film 41. The conductive carbon film 41 has a light-shielding function and a PTC function. In this embodiment, the wiring unit 50 is formed by the linear portion 61B of the FPC 61. The conductive carbon film 41 and the circuit pattern 42 can be manufactured using the same techniques as those in the first embodiment.

[0078] A conductive circuit (not shown) is formed on the straight portion 61B of the FPC 61, and the conductive circuit is electrically connected to the ends 43b and 44b of the circuit pattern 42. Power is supplied to the conductive circuit via the FPC connector portion 61C.

[0079] In this embodiment, the heater section 70 has an axial thickness of approximately 0.215 mm, ensuring a horizontal angle of view exceeding 180°.

[0080] According to this embodiment, as with the first and second embodiments, a snow melting function can be realized without increasing the size of the lens unit 400 (camera module 200). Furthermore, since the captured image is not blurred due to snow or the like adhering to the lens 1, a decrease in the imaging performance of the lens unit 400 can be prevented. Furthermore, a heater section 70 having a PTC function can be realized without increasing the size. Because the heater section 70 has the PTC function, it is controlled to a constant temperature simply by energizing it, without requiring any special control.

[0081] Furthermore, since the thickness of the heater section 70 located between the lens 1 and the lens 2 is set to 0.5 mm or less, it is possible to realize an ultra-wide-angle lens with a horizontal angle of view exceeding 180° while still including the heater section 70.

[0082] Next, a fourth embodiment of the present invention will be described. Figure 8 is an axial cross-sectional view of a lens unit 500 according to the fourth embodiment. Note that some of the hatching indicating a cross-sectional view has been omitted in Figure 8. Hereinafter, components that have the same or corresponding functions as those described in the first to third embodiments will be given the same reference numerals, and their description will be omitted or simplified.

[0083] The lens unit 500 includes a heater section 80. The heater section 80 is sandwiched between the lens 1 and the lens 2.

[0084] The heater unit 80 is made of ceramics whose main component is barium titanate and has a PTC function. This ceramic has a Curie temperature (Curie point), and when the temperature exceeds the Curie temperature, the crystal system undergoes a phase transition from tetragonal to cubic, causing a sudden increase in electrical resistance. The heater unit 80 detects the ambient temperature, and when the temperature exceeds the Curie temperature, the resistance suddenly increases, reducing the flow of current. This makes it possible to maintain a constant temperature without requiring ON / OFF control. The Curie temperature (Curie point) is defined as the temperature at which the resistance value is twice the resistance value at 25°C.

[0085] An electrode (single-sided electrode) may be formed on the lens 1 side (glass lens side) of the heater section 80. The electrode may be, for example, a comb-shaped circuit pattern 42 shown in Fig. 2(a). In other words, the circuit pattern 42 may be formed on a ceramic mainly composed of barium titanate to form the heater section 80. Heat is also transferred to the surface opposite the electrode-formed surface, causing the temperature to rise, but by heating the lens 1 side, it is possible to suppress the temperature rise on the lens 2 side. In other words, it is possible to efficiently heat only the lens 1 side that needs to be heated. Also, because the electrode is formed on only one side, the thickness of the heater section 80 can be made thin, which is ideal for ensuring a horizontal angle of view of more than 180°.

[0086] In this embodiment, the wiring section 50 is made up of a conductor 52. The conductor 52 and the heater section 80 are bonded and electrically connected by, for example, soldering.

[0087] In this embodiment, the image-side surface of the flange portion 1b of the lens 1 is blackened to provide a light-blocking function. For example, black paint is used for the blackening.

[0088] In this embodiment, the heater section 80 has an axial thickness of 0.5 mm, which ensures a horizontal angle of view exceeding 180°.

[0089] According to this embodiment, as with the first to third embodiments, a snow melting function can be realized without increasing the size of the lens unit 500 (camera module 200). Furthermore, since the captured image is not blurred due to snow or the like adhering to the lens 1, a decrease in the imaging performance of the lens unit 500 can be prevented. Furthermore, a heater section 80 having a PTC function can be realized without increasing the size. Because the heater section 80 has the PTC function, it is controlled to a constant temperature simply by energizing it, without requiring any special control.

[0090] Furthermore, since the thickness of the heater section 80 located between the lens 1 and the lens 2 is set to 0.5 mm or less, it is possible to realize an ultra-wide-angle lens with a horizontal angle of view exceeding 180° while still including the heater section 80.

[0091] Furthermore, according to the first to fourth embodiments, the heater sections 40, 60, 70, and 80 are provided at positions that come into contact with the lens 1, so power consumption can be reduced compared to when the heater section and fan are provided outside the lens barrel 10.

[0092] In the first to fourth embodiments, the lens barrel 10 is made of resin, and the lens barrel 10 has the holding portion 12 formed by caulking. Here, a case where the lens barrel 10 is made of metal will be described. The lens barrel 10 is made of aluminum, for example.

[0093] 9 is a cross-sectional view of a lens unit 600 that includes a metal lens barrel 10 and a cap 90. The cap 90 is made of metal, for example, aluminum. A male thread is formed on the outer periphery of the object side end of the lens barrel 10. A cap 90 can be attached to the male thread.

[0094] Cap 90 is annular, and a female thread is formed on the inner periphery of cap 90 to thread onto the male thread of lens barrel 10. The inner diameter of the portion of cap 90 that abuts against the object-side surface of lens 1 is smaller than the outer diameter of lens 1.

[0095] The components housed inside lens barrel 10 are supported by being sandwiched between support portion 11 and cap 90. In other words, the components housed inside lens barrel 10 are held in a state where they are pressed toward support portion 11 by cap 90. This prevents gaps from being formed between the components.

[0096] Furthermore, in the second to fourth embodiments, if an air layer is interposed between the heater parts 60, 70, 80 and the lens 1, the thermal conductivity from the heater parts 60, 70, 80 to the lens 1 generally deteriorates. For this reason, by interposing a thermally conductive sheet or a thermally conductive adhesive material between the heater parts 60, 70, 80 and the lens 1, the heat from the heater parts 60, 70, 80 can be efficiently transferred to the lens 1.

[0097] Next, a fifth embodiment of the present invention will be described. Fig. 10 is an axial cross-sectional view of a camera module 200 according to the fifth embodiment. Note that hatching indicating a cross-sectional view has been partially omitted in Fig. 10. Hereinafter, configurations that have the same or corresponding functions as those described in the first to third embodiments will be assigned the same reference numerals, and their description will be omitted or simplified.

[0098] The lens unit 700 according to this embodiment includes a heater section (doughnut-shaped ceramic heater) 80, similar to the fourth embodiment. An electrode 81 (shown in FIG. 11) is formed on the heater section 80 according to this embodiment. Furthermore, a conducting wire 52 (shown in FIG. 8) is adhesively fixed to the electrode 81 by, for example, soldering.

[0099] FIG. 11(a) is a view of the heater section 80 as seen from the image side, and FIG. 11(b) is a cross-sectional end view taken along line GG shown in FIG. 11(a). The electrode 81 is composed of an inner electrode pattern 81a and an outer electrode pattern 81b, with the inner electrode pattern 81a being positive and the outer electrode pattern 81b being negative, for example. The inner electrode pattern 81a is provided in an annular shape along the inner periphery and inner side surface of the image-side surface of the heater section 80. The outer electrode pattern 81b is provided in an annular shape along the outer periphery and outer side surface of the image-side surface of the heater section 80. Conductive wires 52 are bonded to the ends of the inner electrode pattern 81a and the outer electrode pattern 81b, respectively, by soldering or the like. By providing the electrodes 81 on the side surfaces of the heater section 80 in this way, the contact area between the electrodes 81 (inner peripheral electrode pattern 81a and outer peripheral electrode pattern 81b) and the heater section 80 is increased, further improving the adhesion between them. Furthermore, since the area of ​​the electrodes 81 is increased, it is possible to prevent the resistance of the electrodes 81 from becoming too large when current is applied. Furthermore, it is possible to reduce the size of the heater section 80 (ceramic heater), and it is possible to heat the entire surface of the heater section 80 more efficiently.

[0100] As mentioned above, the heater section 80 is made of ceramics whose main component is barium titanate and has PTC functionality (PTC characteristics). The ceramics have a Curie temperature (Curie point), and when the temperature exceeds the Curie point, the resistance value rises sharply. The Curie point is defined as the temperature at which the resistance value becomes twice the resistance value at room temperature (25°C). PTC (Positive Temperature Coefficient) is a characteristic where electrical resistance increases as temperature increases (i.e., it exhibits a positive temperature coefficient). Generally, PTC characteristics can be obtained by adding a small amount of rare earth elements to barium titanate. PTC characteristics are a property where the ambient temperature is detected, and when a specific temperature (detected temperature) is reached, the resistance value increases rapidly, reducing the flow of current. This characteristic makes it possible to maintain a constant temperature without the need for ON / OFF control.

[0101] The Curie point of the heater unit 80 is preferably within the range of 80°C to 120°C. In other words, the heater unit 80 is preferably configured so that its electrical resistance rises sharply between 80°C and 120°C. This configuration allows the lens 1 (made of glass) located on the object side of the heater unit 80 to be heated in a short time after power is turned on, thereby melting the snow. Furthermore, because the temperature of the heater unit 80 does not become too high, deformation of the lens 2 (plastic lens) located on the image side of the heater unit 80 can be prevented, preventing a deterioration in the optical performance of the lens unit due to deformation of the lens 2. The heat resistance of plastic lenses is around 110°C, and if the temperature of the plastic lens rises above 110°C, deformation occurs, which may result in a deterioration in the optical performance of the lens unit.

[0102] Furthermore, if the Curie point is lower than 80°C, it takes a long time to melt the snow, and a clear image cannot be obtained in a short time after the start of power supply to the heater unit 80. The snow melting effect must be visible to a human 30 seconds after the start of snow melting (start of power supply to the heater unit 80). Furthermore, the snow melting effect must be sufficiently visible 60 seconds after the start of snow melting. This 60-second period is considered to be the average time required to prevent dangerous driving caused by starting the vehicle before the snow has sufficiently melted. From this perspective, it is preferable that the Curie point is 80°C or higher.

[0103] Furthermore, if the Curie point is higher than 120°C, the snow melting time effect will be extremely long, but this will have undesirable effects on the lens (particularly the plastic lens 2 adjacent to the image side of the heater unit 80) and the lens barrel 10. Specific examples of undesirable effects include deformation of the lens 2, deformation of the lens barrel 10, and cracking of the anti-reflection film coated on the surface of the lens 2, which will degrade the optical performance of the lens unit. Furthermore, if the Curie point is higher than 120°C, power consumption will increase and it will be necessary to increase the voltage supplied to the heater unit 80. However, in an environment with limited battery capacity, such as a vehicle, it will be impossible to increase the voltage due to the relationship with other devices, and increasing the voltage could result in a voltage drop.

[0104] 12 is a graph showing the relationship between the current value [mA] supplied to heater unit 80, the time [sec] elapsed since the start of power supply, and the surface temperatures [°C] of heater unit 80 and lens 1 when a heater unit with a Curie point of 80°C is powered in a room temperature (25°C) environment. Note that the surface temperature of lens 1 refers to the object-side surface of lens 1 (made of glass), which is the surface exposed to the outside of the vehicle.

[0105] 12, in the case of a Curie point of 80°C and a room temperature environment, the surface temperature of lens 1 reaches approximately 52°C after 30 seconds and approximately 60°C after 60 seconds. Furthermore, after approximately 150 seconds have passed since the start of current application, the current value becomes approximately constant, the rise in the surface temperature of lens 1 is suppressed, and the temperature remains constant at approximately 73°C.

[0106] FIG. 13 is a graph showing the relationship between the current value [mA] supplied to the heater unit 80, the time [sec] elapsed from the start of power supply, and the surface temperatures [°C] of the heater unit 80 and the lens 1 when power is supplied to the heater unit 80, which has a Curie point of 80°C, in an environment of -30°C. 13, in an environment with a Curie point of 80°C and a temperature of -30°C, the surface temperature of lens 1 reaches approximately 13°C after 30 seconds and approximately 33°C after 60 seconds. Furthermore, after approximately 150 seconds have passed since the start of power supply, the current value becomes approximately constant, the rise in the surface temperature of lens 1 is suppressed, and the temperature remains constant at approximately 50°C.

[0107] FIG. 14 is a graph showing the relationship between the current value [mA] supplied to the heater unit 80, the time [sec] elapsed from the start of power supply, and the surface temperatures [°C] of the heater unit 80 and the lens 1 when power is supplied to the heater unit 80, which has a Curie point of 120°C, in a room temperature (25°C) environment. 14, in the case of a room temperature environment with a Curie point of 120°C, the surface temperature of lens 1 reaches approximately 80°C after 30 seconds and approximately 96°C after 60 seconds. Furthermore, after approximately 150 seconds have passed since the start of current application, the current value becomes approximately constant, the rise in the surface temperature of lens 1 is suppressed, and the temperature remains constant at approximately 109°C.

[0108] FIG. 15 is a graph showing the relationship between the current value [mA] supplied to the heater unit 80, the time [sec] elapsed from the start of power supply, and the surface temperatures [°C] of the heater unit 80 and the lens 1 when power is supplied to the heater unit 80, which has a Curie point of 120°C, in an environment of -30°C. 15, in an environment with a Curie point of 120°C and a temperature of -30°C, the surface temperature of lens 1 reaches approximately 55°C after 30 seconds and approximately 82°C after 60 seconds. Furthermore, after approximately 150 seconds have passed since the start of power supply, the current value becomes approximately constant, the rise in the surface temperature of lens 1 is suppressed, and the temperature remains constant at approximately 92°C.

[0109] In this way, by setting the Curie point of the heater section 80 within the range of 80°C to 120°C, the surface temperature of the lens 1 adjacent to the object side can be raised to a temperature at which snow can melt within 60 seconds, making it possible to achieve snow melting, and since the plastic lens 2 adjacent to the image side does not reach a temperature of 110°C or higher, it is possible to prevent a deterioration in optical performance due to deformation of the lens 2.

[0110] The voltage applied to heater unit 80 is, for example, 6 V. If a higher voltage is applied by heater unit 80, the time required to reach the Curie point will be shorter, and the time required to complete snow melting will be shortened accordingly. However, in the case of a vehicle, it is difficult to increase the voltage due to the relationship with other devices, and increasing the voltage may result in a voltage drop. Furthermore, if the voltage applied to heater unit 80 is lower, the Curie point may not be reached, and the snow melting time may be longer.

[0111] Next, a method for leading out the conductive wire (lead wire) 52 from the lens barrel 10 will be described. Figure 16(a) is an axial cross-sectional view of camera module 200 taken on a plane passing through through hole 111, which will be described later, and Figure 16(b) is an axial cross-sectional view of camera module 200 taken on a plane passing through through hole 112, which will be described later. At the boundary between lens 1 and lens 2 in lens barrel 10, step 15 is formed, which is a surface perpendicular to the axial direction. 17(a) is a diagram showing a portion of the lens barrel 10 as seen from the object side, and FIG. 17(b) is a diagram showing the lens barrel 10 as seen from the side. Two through holes 111, 112 are provided in the step portion 15 for guiding (pulling out) the conductive wire 52 to the outside of the lens barrel 10. One through hole is for the positive electrode, and the other through hole is for the negative electrode. The through holes 111, 112 are formed in a substantially elliptical shape. Note that the shape of the through holes 111, 112 is not limited to this, and they may be, for example, circular.

[0112] As shown in FIG. 16, the through holes 111 and 112 are provided so that the portion provided along the axial direction and the portion provided along the radial direction are perpendicular to each other, and the cross section is substantially L-shaped. 18 is a side view of the lens unit with the lead wires 52 drawn out. The lead wires 52 are inserted into the through holes 111 and 112, one each. As shown in Fig. 16(a), one end of one conducting wire 52 is connected to the heater section 80, and the other end is drawn out to the outside via a through-hole 111. Also, as shown in Fig. 16(b), one end of one conducting wire 52 is connected to the heater section 80, and the other end is drawn out to the outside via a through-hole 112. 16, of the openings of through holes 111, 112, the openings provided on the outer peripheral surface side of barrel 10 will be referred to as openings 111a, 112a. Also, the portions of the internal spaces of through holes 111, 112 on the openings 111a, 112a side will be referred to as conductor lead-out portions (openings) 111b, 112b.

[0113] As shown in FIG. 16 , an O-ring 202 is disposed between camera case 201 and brim-shaped flange 13 formed on the outer circumferential surface of lens barrel 10, forming a seal. In this case, openings 111a and 112a are provided at positions closer to the image side than the seal between camera case 201 and O-ring 202 in the axial direction of lens barrel 10. By positioning openings 111a and 112a in this way, the interior (inside) of camera case 201 is ensured to be airtight, and water will not enter the interior of lens barrel 10 through openings 111a and 112a on the outer circumferential side of lens barrel 10. This eliminates the need to insulate heater 80. Furthermore, because there is no need to insulate heater 80, costs can be reduced.

[0114] Furthermore, if through-holes 111 and 112 were not formed as parallel circular holes as viewed from the object side in the axial direction as shown in FIG. 17( a), but rather were each formed as a groove that communicates with the space inside lens-barrel 10 (a U-shaped groove as viewed from the object side in the axial direction), or if two through-holes were brought close together to form a single elongated hole, the rigidity of lens-barrel 10 would decrease. Specifically, the interior of lens-barrel 10 is constantly subjected to a radially outward force by O-ring 30 (see FIG. 16 ), and when this force is applied, the outer circumferential surface of lens-barrel 10 is likely to bend radially outward. If the outer circumferential surface of lens-barrel 10 bends radially outward, the airtightness of the seal (O-ring 30) would be reduced, potentially allowing water or other contaminants to enter the interior of lens-barrel 10. In contrast, when the through holes are made substantially round and provided in two spaced apart locations (i.e., when through holes 111 and 112 are provided), there are shapes that separate the through holes from the internal space of barrel 10 and between the through holes themselves, so the rigidity of barrel 10 does not decrease, thereby preventing the occurrence of the above-mentioned problems.

[0115] Furthermore, if the bonding strength between the conductor 52 and the heater section 80 is low, there is a risk that the conductor 52 will come off the heater section 80 if the conductor 52 is pulled during the manufacturing process of the camera module. Therefore, an adhesive (e.g., an ultraviolet curing resin) is filled into the conductor lead-out sections 111b, 112b as a fixing member to adhere and fix the conductor 52. This prevents a direct force from being applied to the joint between the conductor 52 and the heater section 80 even if the conductor 52 is pulled, and improves the resistance of the conductor 52 to pulling without increasing the bonding strength of the joint between the conductor 52 and the heater section 80. In other words, even if the conductor 52 is pulled, the conductor 52 can be prevented from coming off the heater section 80.

[0116] Furthermore, a fluororesin electric wire such as PTFE may be used as the conductor 52. This fluororesin electric wire has excellent solder heat resistance, but also excellent chemical resistance, making it difficult to adhere. Therefore, when a fluororesin electric wire is used as the conductor 52, the conductor 52 is fixed to the conductor lead-out portions 111b, 112b using a cylindrical fixing member 120, as shown in FIG.

[0117] Here, the fixing member 120 will be described with reference to Figure 20. Figure 20(a) is a diagram showing the fixing member 120, and Figures 20(b) and 20(c) are diagrams showing modified examples of the fixing member 120. The fixing member 120 shown in FIG. 20(a) is formed in a substantially cylindrical shape and has an outer diameter that allows it to be inserted into the through-holes 111 and 112. The inner diameter of the fixing member 120 is also a diameter that allows the conductive wire 52 to be inserted therethrough. The material of the fixing member 120 is preferably the same as the material of the lens barrel 10, which is made of resin. The resin is, for example, PA, PPS, or the like, and is a material that can be welded or adhered to the lens barrel 10. By inserting the conductive wire 52 into the fixing member 120 and inserting the fixing member 120 into the through-holes 111 and 112, the fixing member 120 can be welded or adhered to the lens barrel 10, thereby reliably fixing the conductive wire 52. This prevents the conductive wire 52 from coming off the heater section 80 even if the conductive wire 52 is pulled.

[0118] 20(b) is formed in a tapered shape so that the outer diameter gradually decreases from one end to the other. This fixing member 120 is made of an elastically deformable material such as rubber, and is inserted into the through-holes 111, 112 from the end with the smaller outer diameter. By tapering the outer circumferential surface of the fixing member 120, it can be more reliably pushed into the through-holes 111, 112. When the fixing member 120 is pressed into the through holes 111, 112, the outer diameter is tightened (a force acting radially inward) and the inner diameter becomes smaller, thereby tightening the conductor 52. This allows the conductor 52 to be reliably fixed, and even if the conductor 52 is pulled, it is possible to prevent the conductor 52 from coming off the heater unit 80. Note that the larger the outer diameter of the portion of the fixing member 120, the smaller the inner diameter becomes when inserted into the through holes 111, 112, and the greater the force tightening the conductor 52. Furthermore, if the fixing member 120 is made of an elastically deformable material, the bonding or welding process is optional.

[0119] The fixing member 120 shown in Fig. 20(c) is the fixing member 120 shown in Fig. 20(b) with an additional slit 121 provided along the axial direction. By providing the slit 121 in this manner, the outer diameter becomes easier to tighten, and the inner diameter becomes smaller by the width of the slit, so that the conducting wire 52 can be tightened more easily.

[0120] In the camera module 200 shown in FIG. 16, lens 1 is a glass lens, and lens 2 is a plastic lens. A reduced-diameter portion 2c is provided at the object-side end of flange portion 2b of lens 2, with the diameter reduced from the image-side outer peripheral surface. In other words, the object-side surface of lens 2 protrudes from the object-side surface of flange portion 2b with a step. The inner diameter of heater portion 80 is set to allow it to fit into reduced-diameter portion 2c (the protruding portion on the object-side surface of lens 2). By fitting heater portion 80 into reduced-diameter portion 2c in this manner, heater portion 80 can be positioned while maintaining the inter-surface distance between lens 1 and lens 2. This ensures a wider angle of view.

[0121] A thermally conductive sheet with a higher thermal conductivity than that of lens 1 may be interposed between the image-side surface of lens 1 and heater unit 80. The thermal conductivity of the thermally conductive sheet is preferably 0.5 W / m·K or more and 5.0 W / m·K or less. Interposing a thermally conductive sheet improves the thermal conductivity between the image-side surface of lens 1 and heater unit 80. To prevent the formation of a gap between lens 1 and heater unit 80, the thermally conductive sheet preferably has a Shore A hardness of at least 10. Furthermore, since a sheet that is too soft will not provide dimensional accuracy in the optical axis direction, a Shore A hardness of 50 or less is preferable. Interposing a thermally conductive sheet with such softness between lens 1 and lens 2 can also prevent cracking of lens 1 due to the impact of pebbles striking lens 1 while the vehicle is traveling. From the perspective of improving productivity, it is preferable to use adhesive double-sided tape between the thermally conductive sheet and lens 1. The double-sided tape is preferably made of a material that does not emit gas at high temperatures, such as acrylic. On the other hand, a heat insulating sheet having a thermal conductivity lower than that of the lens 2 may be interposed between the object-side surface of the lens 2 and the heater section 80. By interposing a heat insulating sheet, for example, if the lens 2 is coated with an AR coating (anti-reflection coating), it is possible to prevent the AR coating from cracking due to the heat from the heater section 80. Alternatively, by roughening the object-side surface of the lens 2 (flange section of the lens 2) that contacts the heater section 80 by forming a textured surface or forming a fine uneven shape, the contact area of ​​the lens 2 that contacts the heater section 80 can be reduced, and the conduction of heat from the heater section 80 to the lens 2 can be suppressed. Furthermore, a heat insulating sheet may be used in combination.

[0122] In the fifth embodiment, it was stated that the Curie point of heater section 80 is preferably within the range of 80° C. to 120° C., and of course this is the same in all embodiments of the present invention. In addition, the method of leading out conductor wire (lead wire) 52 from lens barrel 10 described in the fifth embodiment can also be applied to all embodiments of the present invention. [Explanation of symbols]

[0123] 1,2,3,4 Lens 10 Telescope tube 40,60,70,80 heater section 41 Conductive carbon film 42 Circuit Pattern 61 Flexible PCB 62 Thermistor 100,300,400,500 Lens Unit 200 Camera Module 52 Conductor 81a Inner electrode pattern 81b Outer electrode pattern 111,112 (optical tube) through-hole 111a, 112a (optical tube) opening 111b, 112b (of the lens barrel) lead-out section (opening) 120 Fixing member

Claims

1. A lens unit comprising a cylindrical lens barrel and a plurality of lenses arranged in an axial direction of the lens barrel, a flat surface is provided on an image side surface of a first lens arranged closest to an object among the plurality of lenses, and a flat surface is provided on an object side surface of a second lens adjacent to the image side of the first lens, a heater portion that generates heat when energized is provided between the flat surface of the first lens and the flat surface of the second lens; a wiring portion electrically connected to the heater portion and supplying power to the heater portion is provided at an end portion on the outer circumferential side of the heater portion; an annular seal member is disposed between the flat surface of the first lens and the lens barrel; The heater portion is positioned within a space defined by the seal member. A lens unit characterized by:

2. The heater section includes a conductive carbon film having a self-temperature control function and a light-shielding function, and a circuit pattern for energizing the conductive carbon film.

2. The lens unit according to claim 1.

3. The circuit pattern has a comb shape that includes a plurality of protruding portions that protrude in the radial direction and are arranged at equal intervals along the circumferential direction.

3. The lens unit according to claim 2.

4. The heater section includes a flexible substrate on which a heater circuit is formed, and a thermistor mounted on the flexible substrate and having a self-temperature control function.

2. The lens unit according to claim 1.

5. The heater unit includes a flexible substrate, a conductive carbon film formed on the flexible substrate and having a self-temperature control function and a light-shielding function, and a circuit pattern electrically connected to the flexible substrate and passing current through the conductive carbon film.

2. The lens unit according to claim 1.

6. The circuit pattern has a comb shape having a plurality of protruding portions that protrude in the radial direction and are arranged at equal intervals along the circumferential direction.

6. The lens unit according to claim 5.

7. The heater section is made of ceramics with a self-temperature control function.

2. The lens unit according to claim 1.

8. The heater section has a PTC characteristic and a Curie point temperature of 80°C to 120°C.

8. The lens unit according to claim 7.

9. The heater section is formed in an annular shape and includes an inner peripheral electrode pattern provided along the inner peripheral portion and the side surface of the inner peripheral of the image-side surface of the heater section, and an outer peripheral electrode pattern provided along the outer peripheral portion and the side surface of the outer peripheral of the image-side surface of the heater section, and conductors serving as the wiring section are bonded to the ends of the inner peripheral electrode pattern and the outer peripheral electrode pattern, respectively.

9. The lens unit according to claim 7 or 8.

10. the lens barrel has a through hole through which the conductor wire connected to the heater unit is drawn to the outside of the lens barrel via an opening provided in an outer circumferential surface of the lens barrel, The conducting wire is fixed to the opening on the outer peripheral surface side of the lens barrel by adhesive or a fixing member.

10. The lens unit according to claim 7, wherein the lens unit is a lens unit having a first surface and a second surface.

11. The through holes are provided at two locations, and one of the conductors is inserted into each of the through holes.

11. The lens unit according to claim 10.

12. The fixing member is formed in a substantially cylindrical shape and is inserted into the opening with the conducting wire passing through the inside.

12. The lens unit according to claim 10 or 11.

13. The fixing member is made of an elastically deformable material and is tapered so that the outer diameter becomes smaller from one end to the other end. The fixing member is inserted into the opening from the end with the smaller outer diameter, and the inner diameter becomes smaller when inserted into the opening.

13. The lens unit according to claim 12.

14. the heater portion has a thickness such that the distance between the flat surface of the first lens and the flat surface of the second lens is 0.5 mm or less; The plurality of lenses constitute an ultra-wide-angle lens with a horizontal angle of view exceeding 180°.

14. The lens unit according to claim 1, wherein the first lens element is a lens element.

15. A lens unit according to any one of claims 1 to 14, and an imaging element that captures an image formed by the lens unit. A camera module characterized by:

16. a lens unit according to any one of claims 10 to 13; and an image pickup element that captures an image formed by the lens unit; a camera case that covers the periphery of the lens unit while leaving the object side end of the lens unit exposed; A camera module comprising:

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