Lens unit, optical device equipped with lens unit, and imaging device

Abstract

To provide a lens unit that can reduce the possibility that a desired optical performance cannot be obtained even when a use environment has a wide temperature range.SOLUTION: A lens unit comprises: a first lens that has a first lens optical surface, and a first lens first tapered part and a first lens second tapered part that are provided on the outer periphery of the first lens optical surface; and a second lens that has a second lens optical surface that faces the first lens optical surface, a second lens first tapered part that is separate from and face the first lens first tapered part and is provided on the outer periphery of the second lens optical surface, and a second lens second tapered part that is provided on the outer periphery of the second lens optical surface and is in contact with the first lens second tapered part at a contact part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a lens unit, an optical device including the lens unit, and an imaging device. [Background technology]

[0002] Conventionally, when a lens is used in an optical instrument or an imaging device, a lens unit is formed by holding the lens on a holding member, and the entire lens unit is installed in the optical instrument or imaging device. In such a lens unit, for example, a holding hole for mounting the lens is provided in the holding member, and the lens is mounted in this holding hole to position it in the optical axis direction. The lens is then fixed to the holding frame, for example, with an adhesive. In this case, a method for achieving high-precision positioning for this positioning fixation is disclosed in Patent Document 1, with the aim of not deteriorating the optical performance of the optical instrument or imaging device.

[0003] Patent Document 1 discloses a configuration in which a lens has a tapered shape on the outside. Specifically, two lenses with tapered shapes on the outside are arranged with their tapered surfaces facing each other and the tapered surfaces abut against each other, thereby increasing the precision of lens positioning during lens assembly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-067474 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when an optical device or an imaging device is used over a wide range of environmental temperatures, the lenses can deform depending on the temperature. In such cases, even if multiple lenses are positioned with high precision during lens assembly, the desired optical performance may not be achieved due to lens deformation such as expansion or contraction at or near the upper or lower limits of the environmental temperature.

[0006] The present disclosure has been made in consideration of such a background, and one of its objectives is to provide a lens unit that can maintain desired optical performance even when the temperature range of the usage environment is wide. [Means for solving the problem]

[0007] In order to solve the above problems, a lens unit according to one aspect of the present disclosure comprises: A lens unit having a first lens and a second lens facing each other in a first direction along an optical axis, a first lens having a first lens first tapered portion and a first lens second tapered portion provided continuously on the outside of the first lens first tapered portion, the first lens second tapered portion having an angle with a second direction perpendicular to the optical axis different from an angle between the first lens first tapered portion and the second direction; a second lens facing the first lens, the second lens having: a second lens first tapered portion provided so as to be spaced apart from and face the first lens first tapered portion; and a second lens second tapered portion abutting the first lens second tapered portion at an abutting portion, being provided contiguous to the outside of the second lens first tapered portion, and having an angle with the second direction different from an angle formed between the second lens first tapered portion and the second direction; Equipped with The angle formed between the first lens first tapered portion and the second direction is equal to the angle formed between the second lens first tapered portion and the second direction, and the angle formed between the first lens second tapered portion and the second direction is equal to the angle formed between the second lens second tapered portion and the second direction. . [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide a lens unit that can maintain desired optical performance even when the temperature range of the usage environment is wide. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view of a lens unit according to an embodiment of the present disclosure. [Figure 2] 2 is a cross-sectional view of the lens unit shown in FIG. 1 taken along the line AA. [Figure 3] FIG. 3 is an exploded cross-sectional view of the lens unit shown in FIG. [Figure 4] 2 is a cross-sectional view of the first lens and the second lens shown in FIG. 1, illustrating the relationship between the individual lens tapered portions. FIG. [Figure 5] FIG. 10 is a cross-sectional view showing a modified example of the lens unit. [Figure 6] 10 is a flowchart illustrating an embodiment of a method for manufacturing a lens unit. [Figure 7] 1 is a schematic diagram of an optical device or an imaging device equipped with a lens unit according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Exemplary embodiments for carrying out the present disclosure will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, and relative positions of components described in the following embodiments are arbitrary, and the configuration of an apparatus to which the present disclosure is applied can be changed according to various conditions. Furthermore, the same reference numerals are used between drawings to indicate identical or functionally similar elements.

[0011] It is anticipated that the lens unit according to the present disclosure will be used in a temperature range from as low as several tens of degrees below zero to as high as around 100 degrees Celsius, for example, in surveillance cameras used outdoors, in-vehicle cameras, etc. In the following description, for convenience, the direction along the optical axis of the lens unit will be defined as the optical axis direction, and the direction along a plane perpendicular to the optical axis will be defined as the horizontal direction.

[0012] The lens unit according to the present disclosure includes a first lens and a second lens, and each lens has a tapered abutment portion and a tapered position restriction portion on its outer periphery. The gap in the position restriction portion restricts the position between the lenses, and the tapered abutment portion reduces deterioration of positional accuracy due to thermal deformation in the optical axis direction.

[0013] First Embodiment A first embodiment of the present disclosure will be described below with reference to Figures 1 to 5. Figure 1 shows a plan view of a lens unit 1 according to the first embodiment of the present disclosure, and Figure 2 shows a schematic configuration of the AA cross section of the lens unit 1 of Figure 1. Also, Figure 3 is an exploded cross section of the lens unit of Figure 2, and Figure 4 is a cross section of a first lens 11 and a second lens 12, illustrating the relationship between the individual lens taper portions.

[0014] The lens unit 1 according to this embodiment includes a first lens 11, a second lens 12, a presser member 13, and a holding member 14. In this embodiment, the presser member 13 is ring-shaped. The holding member 14 is cylindrical and has a holding member abutment portion 141 that protrudes inward from one end of the cylindrical shape. The two lenses are inserted into the cylindrical shape in the order of the second lens 12 and the first lens 11 until the second lens 12 abuts against the holding member abutment portion 141. The presser member 13 is then inserted into the cylindrical shape after the first lens 11, and these lenses are sandwiched between the holding member abutment portion 141 and the presser member 13, thereby fixing these lenses in the holding member 14.

[0015] When mounted on a surveillance camera or an in-vehicle camera, the lens unit 1 is expected to be exposed to a low-temperature environment of -40°C to a high-temperature environment of 100°C. The first lens 11 and the second lens 12 are often manufactured as glass lenses made of different materials, and in this case, the linear expansion coefficients of the lenses are also different. When the ambient temperature changes, for example, the positional relationship between the lens surfaces in the optical axis direction may change due to thermal expansion or the like, in the shapes of the first and second lenses described in detail below. Such a change in positional relationship due to ambient temperature may result in the lens not achieving the desired optical performance at ambient temperatures of -40°C or 100°C, even if the lens achieved a desired optical performance at room temperature of 25°C during assembly.

[0016] The present disclosure has been achieved from this perspective. The lens unit 1 of this embodiment suppresses changes in lens spacing and reduces deterioration of optical performance even when thermal expansion or thermal contraction occurs in individual lenses due to environmental temperatures of -40° C. or 100° C. Next, a specific method for suppressing changes in lens spacing will be described.

[0017] FIG. 3 shows an exploded cross-sectional view of the lens unit 1 described above. As shown in FIG. 3, the first lens 11 has a first lens second tapered portion 112, a first lens first tapered portion 113, a first lens optical surface 115, a first lens pressing surface 117, and a first lens side surface 119. The first lens optical surface 115 is a surface disposed opposite the second lens 12 and constitutes the optically effective portion of the first lens 11. The first lens second tapered portion 112 has a conical surface shape provided on the outer periphery of the first lens optical surface 115 on the side where the second lens 12 is located. The first lens first tapered portion 113 is a surface provided on the outer periphery of the first lens optical surface 115 and on the inner periphery of the first lens second tapered portion 112, and is configured to have a conical surface shape. In this embodiment, the first lens first tapered portion 113 is continuous with the first lens optical surface 115 at the outer periphery of the first lens optical surface 115 and continuous with the first lens second tapered portion 112 at the inner periphery of the first lens second tapered portion 112. However, a first rounded portion having a curvature different from that of the first lens optical surface 115 may be provided between the outer periphery of the first lens optical surface 115 and the first lens first tapered portion 113, so that they are not continuous. Alternatively, a second rounded portion having a curvature may be provided between the first lens first tapered portion 113 and the first lens second tapered portion 112, so that they are not continuous. The first lens pressing surface 117 is provided on the outer periphery of the surface opposite the second lens 12 and serves as a surface that abuts against the pressing member 13. The first lens side surface 119 is configured as a surface that is parallel to the optical axis and faces the inner periphery of the holding member 14.

[0018] The second lens 12 has a second lens second tapered portion 123, a second lens first tapered portion 124, a second lens optical surface 126, a holding member contact surface 128, and a second lens side surface 130. The second lens optical surface 126 is a surface disposed opposite the first lens optical surface 115 and constitutes the optically effective portion of the second lens 12. The second lens second tapered portion 123 has a conical surface shape provided on the outer periphery of the second lens optical surface 126, which is the surface on the side where the first lens 11 is located. The second lens first tapered portion 124 is a surface provided on the outer periphery of the second lens optical surface 126 and on the inner periphery of the second lens second tapered portion 123, and is configured to have a conical surface shape. In this embodiment, the second lens first tapered portion 124 is provided so as to be continuous with the second lens optical surface 126 on the outer periphery of the second lens optical surface 126. However, a third rounded portion having a curvature different from that of the second lens optical surface 126 may be provided between the outer periphery of the second lens optical surface 126 and the second lens first tapered portion 124, so that they are not continuous. Also, a fourth rounded portion having a curvature may be provided between the second lens first tapered portion 124 and the second lens second tapered portion 123, so that they are not continuous. The holding member contact surface 128 is a surface that abuts against the holding member abutment portion 141. The second lens side surface 130 is configured as a surface that is parallel to the optical axis and faces the inner circumferential surface of the holding member 14.

[0019] In this case, the inner and outer diameters of the first lens second tapered portion 112 and the second lens second tapered portion 123 are determined so that at least a portion of their conical surfaces can abut. The inner and outer diameters of the first lens first tapered portion 113 and the inner and outer diameters of the second lens first tapered portion 124 are determined so that they do not abut at temperatures during manufacturing. More preferably, the outer and inner diameters of the tapered portions where the first lens first tapered portion and the second lens first tapered portion abut are determined at the highest or lowest expected ambient temperature based on the relationship between the linear expansion coefficients of the first lens 11 and the second lens 12. Although the abutting second tapered portion is provided on the outer periphery of the first tapered portion in the above description, the abutting second tapered portion may be provided on the inner periphery of the first tapered portion.

[0020] The first lens first tapered portion 113 and the second lens first tapered portion 124, which do not abut at the temperature during manufacturing, can suppress fluctuations in the radial position of the first lens 11 and the second lens 12 due to thermal deformation caused by changes in environmental temperature. As a result, even if thermal expansion or thermal contraction occurs in each lens, it is possible to reduce the possibility that the desired optical performance will not be achieved in the lens unit 1.

[0021] Next, the preferred shape of the contact position and taper angle θ2 of first lens second tapered portion 112 and second lens second tapered portion 123, which are the contact portions between first lens 11 and second lens 12, will be described with reference to Figure 4. Figure 4(a) is a cross-sectional view showing the dimensions and physical properties related to thermal deformation of the first lens and second lens, and Figure 4(b) is an enlarged cross-sectional view of the contact portion between first lens 11 and second lens 12. In the following description, taper angles θ1 and θ2 are defined as the angles between the horizontal direction and the tapered surface on cross section AA.

[0022] First, we will explain thermal deformation of the lenses in the optical axis direction. When the amount of change in ambient temperature is ΔH, the projected distance in the optical axis direction from the contact portion to the optical surface of the first lens is h1, and the linear expansion coefficient is α1, the amount of thermal deformation of first lens 11 in the optical axis direction is ΔH×h1×α1. When the projected distance in the optical axis direction from the contact portion to the optical surface of second lens 12 is h2, and the linear expansion coefficient is α2, the amount of thermal deformation of second lens 12 in the optical axis direction is ΔH×h2×α2. In this case, the distance between the lenses changes by an amount ΔH×(α1×h1-α2×h2), which is the difference between the amount of thermal deformation of first lens 11 and the amount of thermal deformation of second lens 12.

[0023] Here, we will explain the influence of thermal deformation in the radial direction and the optical axis direction of the lens. When the contact portion is flat, if the distance from the lens optical axis to the contact position is D / 2, the change in the lens position in the radial direction is ΔH × (α2 - α1) × D / 2. Here, D represents the diameter of the contact portion between the first lens second tapered portion 112 of the first lens 11 and the second lens second tapered portion 123 of the second lens 12, as shown in FIG. 4(a). Since the first lens second tapered portion 112 and the second lens second tapered portion 123 are both conical, they ideally make surface contact. However, due to factors such as surface accuracy, in reality, they make point contact or partial surface contact. In this embodiment, for convenience, the tapered portions are assumed to be in surface contact, and the center of the contact surface is defined as the contact portion. Furthermore, although the diameter of the abutting portion is designated as D, the abutting portion is not limited to this and can be the portion where the first lens second tapered portion 112 and the second lens second tapered portion 123 actually abut. In the present disclosure, if the portion where the lenses abut is tapered, thermal deformation in the radial direction causes slippage between the first lens second tapered portion 112 and the second lens second tapered portion 123. This allows the positional relationship between the first lens 11 and the second lens 12 in the optical axis direction to be changed. When the angle between the first lens second tapered portion 112 and the second lens second tapered portion 123 and the horizontal direction is designated as θ2, the amount of change in the positional relationship of the optical axis is ΔH×(α2-α1)×tan θ2×D / 2. Therefore, the angle and contact position of the tapered surface are determined based on the linear expansion coefficients of the first lens 11 and the second lens 12 so that the difference between the thermal deformation amounts of the first lens 11 and the second lens 12, ΔH×(α1×h1-α2×h2), becomes small.

[0024] Specifically, the angle and contact position of the tapered surface are determined by the following formula (1): In the best case, the amount of change calculated from the difference in thermal deformation in the optical axis direction between the first lens and the second lens, ΔH×(h2×α2-h1×α1), is equal to the amount of change calculated from ΔH×(α2-α1)×tan θ2×D / 2, and the angle and contact position of the tapered surface are set to cancel these out. |(h2×α2-h1×α1)|≧|(h2×α2-h1×α1)-(α2-α1)×tanθ2×D / 2|...Equation (1)

[0025] In this case, when α1>α2 and α1×h1>α2×h2 or when α1<α2 and α1×h1<α2×h2, it is advisable to use a tapered shape with the outer periphery toward the second lens, as shown in Figure 4(a). Also, when α1>α2 and α1×h1<α2×h2 or when α1<α2 and α1×h1>α2×h2, by using a tapered shape with the outer periphery toward the first lens, as shown in Figure 5, the thermal deformation directions in the optical axis direction will coincide, and it will be possible to reduce positional deterioration between the lenses.

[0026] FIG. 5 shows modified examples of the lens unit according to the present embodiment, which are configured to accommodate the conditions α1 > α2 and α1 × h1 < α2 × h2 and α1 < α2 and α1 × h1 > α2 × h2. Note that the same reference numerals are used for the same components as those in the lens unit 1 described with reference to FIG. 3 and other figures, and their descriptions will be omitted. Lens unit 5 shown as the modified example includes a first lens 51 and a second lens 52. One surface of the first lens 51 is provided with, in order from a first lens optical surface 515 located approximately at the center, a first lens first tapered portion 513, a first lens flat portion 511, and a first lens second tapered portion 512. One surface of the second lens 52 is provided with, in order from a second lens optical surface 526 located approximately at the center, a second lens first tapered portion 524, a first lens flat portion 522, and a first lens second tapered portion 523. First lens 51 and second lens 52 are arranged so that first lens optical surface 515 and second lens optical surface 526 face each other. In this modified example, the arrangement of the first tapered portion and the second tapered portion relative to the optical surface of each lens differs from that of the above-described embodiment. However, even with this arrangement, the same effect can be obtained as long as the above conditions are met.

[0027] Next, suitable taper angles of the first lens second tapered portion 112, the first lens first tapered portion 113, the second lens second tapered portion 123, and the second lens first tapered portion 124 will be described with reference to Fig. 4(b). Note that the taper angles (θ1, θ2) described below are the angles formed by each tapered portion and the horizontal direction.

[0028] The first lens first tapered portion 113 and the second lens first tapered portion 124 are required to have the function of preventing a change in the radial positional relationship between the lenses that exceeds the gap amount at the temperature during manufacturing when radial thermal deformation of the first lens 11 and the second lens 12 occurs due to changes in environmental temperature. In other words, a shape that can withstand a large radial load is preferable. Therefore, the taper angle θ1, which is the angle between the first lens first tapered portion 113 and the second lens first tapered portion 124 in the horizontal direction, is preferably in the range of 45 degrees to 90 degrees. Furthermore, since the tapered portions need to maintain a gap until just before they come into contact, it is preferable that the taper angles be equal.

[0029] For the above reasons, it is preferable that the angle θ1 of the first lens first tapered portion 113 and the second lens first tapered portion 124 be equal, and that the angle they form with respect to the horizontal direction be in the range of 45 degrees or more and 90 degrees or less from the perspective of lens position regulation. It is also preferable that the angle θ2 of the first lens second tapered portion 112 and the second lens second tapered portion 123 be equal so that these tapered portions can be in surface contact. Furthermore, due to the difference in the above-mentioned viewpoints, it is preferable that the angle θ1 of the first tapered portion and the angle of the second tapered portion be greater than the angle θ2. By ensuring that each tapered angle satisfies this condition, it is possible to easily manufacture a lens unit 1 that is less likely to lose the desired optical performance even if thermal expansion or thermal contraction occurs in each lens.

[0030] Next, assembly of the lens unit 1 according to one embodiment of the present disclosure will be described with reference to the flowchart of FIG.

[0031] First, in step S601, the material of the first lens 11 and the material of the second lens 12 and the shape of each optical surface are determined based on the optical conditions required for the lens unit 1. Next, in step S602, the angle θ2 of the second tapered portion and the abutment position are determined based on the linear expansion coefficient α1 of the first lens 11, the linear expansion coefficient α2 of the second lens 12, and the distance between the optical surfaces of the first lens 11 and the second lens 12. The angle θ1 of the first tapered portion is also determined. This determines the dimensions of the first lens 11 and the second lens 12, and these lenses are manufactured.

[0032] Next, in step S603, the second lens 12 is inserted into the holding member 14. This operation is completed in step S604 when the holding member contact surface 128 of the second lens is brought into contact with the holding member abutment portion 141. The holding member contact surface 128 of the second lens is provided on the outer periphery of the surface opposite to the surface on which the second lens optical surface 126 of the second lens 12 is provided, and forms a flat portion. At this time, it does not matter whether the second lens side surface 130 of the second lens is in contact with the holding member 14 or not.

[0033] Next, in step S605, the first lens 11 is inserted into the holding member 14. At this time, the insertion is performed while applying vibrations to the holding member 14 and the first lens 11 in a direction within a plane perpendicular to the insertion direction (horizontal direction). This operation ends in step S606 when the first lens second tapered portion 112 is brought into contact with the second lens second tapered portion 123.

[0034] As described above, the optical axes of the first lens 11 are aligned by applying vibration in a horizontal plane when the first lens 11 is inserted. Therefore, if either the first lens side surface 119 of the first lens 11 or the second lens side surface 130 of the second lens 12 is fixed to the inner periphery of the holding member 14, the other lens will also be positioned at a desired position relative to the holding member 14. Furthermore, by determining whether either the first lens side surface 119 or the second lens side surface 130 abuts the holding member 14 based on the relative height between the expected temperature during use and the reference temperature at the time of manufacture, the constraint from the abutting surface on thermal deformation of the non-abutting lens can be eliminated. As described above, by having only one of the lenses abut the inside of the holding member 14, alignment of the optical axes of each lens is facilitated. However, if the constraint on the lens outer diameter by the holding member 14 is not a significant issue, for example, if the expected temperature is not significantly different from the reference temperature at the time of manufacture or if the holding member 14 is relatively easily deformed, both lenses may abut the inside of the holding member 14.

[0035] Finally, in step S607, pressing member 13 is inserted into holding member 14. Then, in step S608, pressing member 13 is brought into contact with first lens pressing surface 117, and the pressing member 13 is fixed to holding member 14. For example, by going through the above steps, a lens unit according to the present disclosure can be manufactured.

[0036] In the above-described embodiment, the pressing member 13 is shown as a cylindrical part such as a crimping ring, but the form is not limited to the shape of the embodiment. For example, parts such as multiple pawls or screws can also be used as the pressing member 13. Furthermore, the above-described manufacturing method is one example, and steps other than the method of determining the angle and contact position of the second tapered portion in step S602 can be replaced by various known and available methods.

[0037] Furthermore, in order to obtain the effects of the present disclosure, it is preferable that both lenses thermally expand or contract individually depending on the ambient temperature, and therefore it is preferable that the first lens optical surface 115 of the first lens 11 and the second lens optical surface 126 of the second lens 12 are spaced apart.

[0038] <Application example of the first embodiment> An imaging device equipped with the lens unit 1 according to the first embodiment described above, and an example of such an imaging device, an in-vehicle camera, will now be described with reference to the drawings. Fig. 7 shows a schematic configuration of an in-vehicle camera according to the present disclosure, with Fig. 7(a) showing an external perspective view and Fig. 7(b) showing an outline of the components.

[0039] The vehicle-mounted camera 100 according to the present disclosure includes an internal optical system 102 having multiple lenses, an image sensor 103 that receives light passing through the optical system, and a housing 101 that contains these components and to which the lens unit 1 described as the first embodiment is applied. The vehicle-mounted camera 100 is assumed to be mounted in a vehicle exposed to direct sunlight outdoors in the summer, for example, and placed in a temperature environment of several tens of degrees. By using the lens unit 1 according to the first embodiment, it is possible to reduce the possibility that the lens unit 1 will not achieve the desired optical performance, even in such an environment. The image sensor 103 is, for example, a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor. The image sensor converts light incident via the optical system 102 into an electrical signal.

[0040] As described above, the lens unit 1 according to the present disclosure includes at least a first lens 11 and a second lens 12. The first lens 11 has, for example, a first lens optical surface 115, a first lens first tapered portion 113 provided on the outer periphery of the first lens optical surface 115, and a first lens second tapered portion 112 provided on the outer periphery of the first lens optical surface 115. The second lens 12 has, for example, a second lens optical surface 126 facing the first lens optical surface 115, and a second lens first tapered portion 124 provided on the outer periphery of the second lens optical surface 126 facing the first lens first tapered portion 113. The second lens 12 further has a second lens second tapered portion 123 provided on the outer periphery of the second lens optical surface 126 and arranged to abut against the first lens second tapered portion 112 at an abutment portion. The first lens second tapered portion 112 and the second lens second tapered portion 123 have the same taper angle (θ2, the angle between the tapered surface and the direction perpendicular to the optical axis) and are arranged so that their conical surfaces abut against each other. Ideally, the abutting portion would be the abutting surface, but in order to define a portion that serves as a reference for deformation in consideration of thermal deformation and the like, the abutting portion can be, for example, the central portion of the abutting surface (the contact portion of the tapered portions 112, 123 in FIG. 4(b)). Then, the material of the first lens 11, the material of the second lens 12, and the shape of each optical surface are selected based on the optical conditions required for the lens unit 1. This selection is made so that the change in the inter-surface distance between the first lens 11 and the second lens 12 in the optical axis direction during thermal deformation is minimized.

[0041] Furthermore, in this case, in an environment with a temperature of 25°C, the distance between the outer peripheral end of the first lens first tapered portion 113 and the outer peripheral end of the second lens first tapered portion 124 is set to a predetermined distance. More specifically, the angle θ2 of the second tapered portion and the abutment position are determined by α1, α2, and D as shown in Equation (1). In the above-described embodiment, the reference temperature is described as 25°C, but the reference temperature is not limited to this. For example, when considering mounting the lens unit on an in-vehicle camera, the reference temperature may be the average temperature of the environment in which the in-vehicle camera is used. Furthermore, in the embodiment, a temperature of 100°C is used as the assumed temperature, but the upper limit of the assumed temperature is not limited to 100°C. For example, the upper limit may be set by multiplying the maximum temperature of the in-vehicle camera actually measured outdoors by a safety factor.

[0042] In the above-described embodiment, the lower limit of the expected temperature is set to -40°C. However, the lower limit may be set by multiplying the lowest temperature actually measured outdoors by a safety factor, for example.

[0043] Here, it is preferable that the angle formed by the first lens first tapered portion 113 and the second lens first tapered portion 124 in the direction perpendicular to the optical axis is larger than the angle formed by the first lens second tapered portion 112 and the second lens second tapered portion 123 in the direction perpendicular to the optical axis. Furthermore, from the viewpoint of lens position regulation of the lens unit 1, it is preferable that the angle formed by the first lens first tapered portion 113 of the first lens 11 and the second lens first tapered portion 124 of the second lens 12 in the direction perpendicular to the optical axis is between 45 degrees and 90 degrees.

[0044] As described above, the lens unit 1 according to the present disclosure also includes a holding member 14 that houses the first lens 11 and the second lens 12. The holding member 14 can have a holding member abutment portion 141 that abuts against a holding member contact surface 128 provided on the surface opposite to the surface on which the second lens second tapered portion 123 is formed. The holding member abutment portion 141 can be provided so as to protrude inward from the inner circumferential surface of the cylindrical holding member 14. The lens unit 1 also includes a pressing member 13 that abuts against a surface (117) provided on the opposite side to the surface on which the first lens second tapered portion 112 is provided, and that clamps the first lens 11 and the second lens 12 together with the holding member abutment portion 141. At least one of the outer circumferential surface (side surface 119) of the first lens 11 and the outer circumferential surface (side surface 130) of the second lens 12, or both, can abut against the inner circumferential surface of the holding member 14. Additionally, in the illustrated embodiment, first lens optical surface 115 and second lens optical surface 126 are spaced apart.

[0045] The present disclosure can also be configured as a method for manufacturing the above-described lens unit. The method includes inserting the second lens 12 into the holding member 14 and continuing to insert the first lens 11 into the holding member 14 until the first lens second tapered portion 112 abuts against the second lens second tapered portion 123 at the abutment portion. The method further includes inserting a pressing member 13 into the holding member 14 to fix the lenses to the holding member 14. When fixing the lenses, the pressing member 13 presses and fixes the first lens 11 in the insertion direction of the first lens 11 from a first lens pressing surface 117, which is the surface of the first lens 11 opposite to the surface on which the first lens second tapered portion 112 is provided. Here, the first lens first tapered portion 113 and the second lens first tapered portion 124 are spaced apart. The angle θ2 of the second tapered portion and the abutment position are determined based on equation (1).

[0046] By using the lens unit 1 described above or the lens unit 1 obtained by the manufacturing method, it is possible to reduce the possibility that the desired optical performance will not be achieved in the lens unit 1, even in an environment in which the lens unit 1 is used, for example, in an in-vehicle camera. This disclosure has shown an example in which the lens unit 1 is applied to an in-vehicle camera. However, the lens unit 1 according to this disclosure can also be applied to imaging devices other than in-vehicle cameras, such as compact digital cameras, single-lens reflex digital cameras, mirrorless digital cameras, and mobile devices such as smartphones and tablets. It can also be applied to optical devices such as binoculars, microscopes, and telescopes. These optical devices are composed of an optical system including the lens unit 1 described above and a housing that houses the optical system.

[0047] <Example> The effects of the present disclosure will be described below with reference to examples that embody the present disclosure and comparative examples for the examples. Note that the following examples are examples of the present disclosure, and the present disclosure is not limited to the following examples.

[0048] Furthermore, the positional fluctuation of each lens in the optical axis direction was measured by placing CL-P015 and CL-P070 multicolor laser coaxial displacement meters of the CL-3000 series manufactured by KEYENCE above and below the lens unit 1.

[0049] [Example 1] In this embodiment, the first lens is made of M-TAFD305 (manufactured by HOYA: linear expansion coefficient α1 = 60 × 10 -7 The lens shape was a convex meniscus lens with an outer diameter of 36.6 mm, a center thickness of 6.8 mm, and an edge thickness of 1.7 mm. The second lens was made of M-PCD55AR (manufactured by HOYA; linear expansion coefficient α = 92 × 10 -7 The lens shape was a concave meniscus lens with an outer diameter of 36.6 mm, a total height of 8.0 mm, a center thickness of 1.8 mm, and an edge thickness of 2.8 mm.

[0050] The dimensions of each lens were determined using equation (1) to minimize the amount of thermal deformation. Specifically, the outer diameter D of the contact portion was set to φ30 mm, the projected distance h1 from the contact portion to the optical surface of the first lens in the optical axis direction was set to 12 mm, the projected distance h2 from the contact portion to the optical surface of the second lens in the optical axis direction was set to 11 mm, and the angle θ2 of the second tapered portion was set to 31 degrees. The outer diameter of the first tapered portion of the first lens was set to φ27.005 mm, the outer diameter of the first tapered portion of the second lens was set to φ27.000 mm, and the taper angle θ1 was set to 60 degrees.

[0051] Next, at a room temperature of 25°C, the second lens and the first lens were inserted into the holding member in this order. At this time, by applying force from the optical axis direction, the first tapered portions of the first and second lenses acted as guides, and the lenses were inserted into the holding member. After the first lens was inserted, when the second tapered portion of the first lens and the second tapered portion of the second lens were observed from above the first lens, it was confirmed that interference fringes were formed. The formation of these interference fringes confirmed that the surfaces of the second tapered portion of the first lens and the second tapered portion of the second lens were in contact with each other.

[0052] Finally, the first lens 11 was held down from above using a caulking ring (holding member 13) to assemble the lens unit 1. After that, KEYENCE CL-3000 series CL-P015 multi-color laser coaxial displacement meters were placed above and below the lens unit to measure the positional relationship of the lenses. At this time, in order to bring the horizontal position closer to the center of the lenses, the first lens 11 was aligned with the apex and the second lens 12 with the bottom, and the measurement showed that the overall height of the center of the lens unit 1 was 10.360 mm.

[0053] Next, the entire lens unit 1 was heated to a temperature of 100°C using a heater, and measurement was performed again using the same method, revealing that the overall height of the center of the lens unit 1 was 10.368 mm. The variation in the overall height of the center of the lens unit 1 calculated from the shape and linear expansion coefficient of the lens unit 1 was 8.5 μm, confirming that the variation in the distance between the first lens 11 and the second lens 12 was favorable at 1 μm or less.

[0054] [Comparative Example 1] Next, as a comparative example, a lens unit 1 was produced under the following conditions, and measurements were carried out in the same manner as in Example 1. Details are described below.

[0055] In this comparative example, similar to Example 1, the first lens 11 is made of M-TAFD305 (manufactured by HOYA; linear expansion coefficient α1=60×10 -7 / °C). The lens shape was a convex meniscus lens with an outer diameter of 36.6 mm, a center thickness of 6.8 mm, and an edge thickness of 1.7 mm. The second lens 12 was made of M-PCD55AR (manufactured by HOYA; linear expansion coefficient α = 92 × 10 -7 The lens shape was a concave meniscus lens with an outer diameter of 36.6 mm, a total height of 8.0 mm, a center thickness of 1.8 mm, and an edge thickness of 2.8 mm.

[0056] In this case, the contact portion, which corresponds to the second tapered portion in Example 1, was made flat rather than tapered. As for the first tapered portion, the outer diameter of the first tapered portion of the first lens was φ27.005 mm, the outer diameter of the first tapered portion of the second lens was φ27.000 mm, as in Example 1, and the taper angle θ1 was 60 degrees.

[0057] Next, the second lens and the first lens were inserted into the holding member in this order at an indoor temperature of 25°C. At this time, by applying force from the optical axis direction, the first tapered portions of the first and second lenses acted as guides, allowing these lenses to be inserted into the holding member. After the first lens was inserted, when the flat surfaces of the first and second lenses, which are the contact points, were observed from above the first lens, it was confirmed that interference fringes were formed.

[0058] Finally, the first lens 11 was held down from above using a caulking ring (holding member 13) to assemble the lens unit 1. After that, KEYENCE CL-3000 series CL-P015 multi-color laser coaxial displacement meters were placed above and below the lens unit to measure the positional relationship of the lenses. At this time, in order to bring the horizontal position closer to the center of the lenses, the first lens 11 was aligned with the apex and the second lens 12 with the bottom, and the measurement showed that the total height of the center of the lens unit 1 was 10.453 mm.

[0059] Next, the entire lens unit 1 was heated to a temperature of 100°C using a heater, and measurement was performed again using the same method, revealing that the overall height of the center of the lens unit 1 was 10.464 mm. The variation in the overall height of the center of the lens unit 1 calculated from the shape and linear expansion coefficient of the lens unit 1 was 8.5 μm, which means that the variation in the distance between the first lens 11 and the second lens 12 was 2 μm or more.

[0060] The present disclosure includes the following configurations. (Configuration 1) a first lens having a first lens optical surface, and a first lens first tapered portion and a first lens second tapered portion provided on an outer periphery of the first lens optical surface; a second lens having a second lens optical surface facing the first lens optical surface, a second lens first tapered portion provided on an outer periphery of the second lens optical surface, spaced apart from and facing the first lens first tapered portion, and a second lens second tapered portion provided on the outer periphery of the second lens optical surface and abutting against the first lens second tapered portion at an abutting portion; A lens unit comprising: (Configuration 2) a diameter of the first tapered portion of the first lens is larger than a diameter of the second tapered portion of the second lens; When the linear expansion coefficient of the first lens is α1, the distance in the optical axis direction between the vertex of the surface of the first lens that faces the second lens and the abutting portion is h1, the linear expansion coefficient of the second lens is α2, the distance in the optical axis direction between the vertex of the surface of the second lens that faces the first lens and the abutting portion is h2, the outer diameter of the abutting portion is D, and the angle formed by the tapered surface that constitutes the abutting portion and the direction perpendicular to the optical axis is θ, the following equation is satisfied: |(h2×α2-h1×α1)|≧|(h2×α2-h1×α1)-(α2-α1)×tanθ×D / 2| The lens unit according to configuration 1, (Configuration 3) The lens unit described in configuration 1 or 2, wherein the angle formed by the first lens first tapered portion and the second lens first tapered portion in a direction perpendicular to the optical axis is larger than the angle formed by the first lens second tapered portion and the second lens second tapered portion in a direction perpendicular to the optical axis. (Configuration 4) 4. The lens unit according to any one of configurations 1 to 3, wherein the angle formed by the first lens first tapered portion and the second lens first tapered portion with respect to the optical axis and the perpendicular direction is 45 degrees or more and 90 degrees or less. (Configuration 5) 5. The lens unit according to any one of configurations 1 to 4, wherein the first lens optical surface and the second lens optical surface are disposed apart from each other. (Configuration 6) 6. The lens unit according to any one of configurations 1 to 5, wherein the first lens and the second lens are glass lenses. (Configuration 7) In the first lens, at least two of the first lens optical surface, the first lens first tapered portion, and the first lens second tapered portion are arranged continuously, The lens unit described in any one of configurations 1 to 6, wherein in the second lens, at least two of the second lens optical surface, the second lens first tapered portion, and the second lens second tapered portion are arranged continuously. (Configuration 8) a holding member that houses the first lens and the second lens, and has an abutment portion that abuts against a flat surface of the second lens and is provided on an outer periphery of a surface opposite to a surface on which the second lens optical surface is provided; The lens unit described in any one of structures 1 to 7, further comprising a pressing member that abuts against a surface of the first lens opposite to the surface on which the first lens optical surface is provided, and that, together with the abutment portion, holds the first lens and the second lens together. (Configuration 9) a cylindrical holding member that houses the first lens and the second lens; 9. The lens unit according to any one of configurations 1 to 8, wherein at least one of an outer peripheral surface of the first lens and an outer peripheral surface of the second lens abuts against an inner peripheral surface of the holding member. (Configuration 10) an optical system including the lens unit according to any one of configurations 1 to 9; a housing that houses the optical system; An optical instrument comprising: (Configuration 11) an optical system including the lens unit according to any one of configurations 1 to 9; an image sensor that receives light that has passed through the optical system; a housing that houses the optical system and the imaging element; An imaging device comprising:

[0061] Although the present disclosure has been described above with reference to embodiments and examples, the present disclosure is not limited to these embodiments. Inventions modified within the scope of the present disclosure and inventions equivalent to the present disclosure are also included in the present disclosure. Furthermore, the above-described embodiments, modifications, and examples can be combined as appropriate within the scope of the present invention. [Explanation of symbols]

[0062] 1. Lens unit 11. First lens 12. Second lens 13. Retaining member 14. Retaining member 112....First lens, second tapered portion 113 First lens first tapered portion 115...First lens optical surface 117 First lens pressing surface 119···First lens side 123... Second lens, second tapered section 124... 2nd lens 1st tapered section 126... Second lens optical surface 128....Holding member contact surface 130 Second lens side 130 141... Holding member abutment portion

Claims

1. A lens unit having a first lens and a second lens facing each other in a first direction along an optical axis, a first lens having a first lens first tapered portion and a first lens second tapered portion provided continuously outside the first lens first tapered portion, the first lens second tapered portion having an angle with a second direction perpendicular to the optical axis different from an angle between the first lens first tapered portion and the second direction; a second lens facing the first lens, the second lens having: a second lens first tapered portion provided so as to be spaced apart from and face the first lens first tapered portion; and a second lens second tapered portion abutting the first lens second tapered portion at an abutting portion, being provided contiguous to the outside of the second lens first tapered portion, and having an angle with the second direction different from an angle formed between the second lens first tapered portion and the second direction; Equipped with an angle formed between the first tapered portion of the first lens and the second direction is equal to an angle formed between the first tapered portion of the second lens and the second direction; The lens unit wherein an angle formed between the first lens second tapered portion and the second direction is equal to an angle formed between the second lens second tapered portion and the second direction.

2. 2. The lens unit according to claim 1, wherein the first lens first tapered portion, the first lens second tapered portion, the second lens first tapered portion, and the second lens second tapered portion all form an angle of 90 degrees or less with respect to the second direction.

3. The lens unit according to claim 1 , wherein an angle formed between the first tapered portion of the first lens and the second direction is larger than an angle formed between the second tapered portion of the first lens and the second direction.

4. a diameter of the first tapered portion of the first lens is larger than a diameter of the second tapered portion of the second lens; When a linear expansion coefficient α1 of the first lens, a distance h1 in the first direction between the vertex of the surface of the first lens facing the second lens and the abutting portion, a linear expansion coefficient α2 of the second lens, a distance h2 in the first direction between the vertex of the surface of the second lens facing the first lens and the abutting portion, an outer diameter D of the abutting portion, and an angle θ formed by the tapered surface constituting the abutting portion and the second direction are expressed by the following formula: |(h2×α2−h1×α1)|≧|(h2×α2−h1×α1)−(α2−α1)×tanθ×D / 2| The lens unit according to claim 1 , wherein

5. 2. The lens unit according to claim 1, wherein an angle formed between the first lens first tapered portion and the second lens first tapered portion and the second direction is larger than an angle formed between the first lens second tapered portion and the second lens second tapered portion and the second direction.

6. 2. The lens unit according to claim 1, wherein an angle formed between the first lens first tapered portion and the second lens first tapered portion and the second direction is equal to or greater than 45 degrees and equal to or less than 90 degrees.

7. The lens unit according to claim 1 , wherein the optical surface of the first lens and the optical surface of the second lens are spaced apart from each other.

8. The lens unit according to claim 1 , wherein the first lens and the second lens are glass lenses.

9. In the first lens, at least two of the optical surface of the first lens, the first lens first tapered portion, and the first lens second tapered portion are arranged continuously, 2. The lens unit according to claim 1, wherein in the second lens, at least two of the optical surface of the second lens, the first tapered portion of the second lens, and the second tapered portion of the second lens are arranged continuously.

10. a holding member that houses the first lens and the second lens, and has an abutment portion that abuts against a flat surface of the second lens and is provided on an outer periphery of a surface opposite to a surface on which an optical surface of the second lens is provided; 2. The lens unit according to claim 1, further comprising: a pressing member that abuts against a surface of the first lens opposite to a surface on which the optical surface of the first lens is provided, and that, together with the abutment portion, holds the first lens and the second lens together.

11. a cylindrical holding member that houses the first lens and the second lens; The lens unit according to claim 1 , wherein at least one of an outer peripheral surface of the first lens and an outer peripheral surface of the second lens abuts against an inner peripheral surface of the holding member.

12. an optical system including the lens unit according to any one of claims 1 to 11; a housing that houses the optical system; An optical instrument comprising:

13. an optical system including the lens unit according to any one of claims 1 to 11; an image sensor that receives light that has passed through the optical system; a housing that houses the optical system and the imaging element; An imaging device comprising:

Images