Lens unit, optical instrument including lens unit, and imaging apparatus

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 Art

[0002] Conventionally, when using a lens in an optical device or an imaging device, a lens unit may be configured by holding the lens with a holding member, and the entire lens unit may be attached and used in the optical device or the imaging device. In such a lens unit, for example, a holding hole for placing the lens is provided in the holding member, and the lens is placed in this holding hole to perform positioning in the optical axis direction. Then, the lens is fixed to the holding frame, for example, by an adhesive or the like. At that time, for the purpose of not deteriorating the optical performance of the optical device or the imaging device, a method for positioning with high precision for this position fixing is disclosed in Patent Document 1.

[0003] Patent Document 1 discloses a form in which a tapered shape is provided on the outside of the lens. Specifically, two lenses provided with a tapered shape on the outside of the lens are arranged such that their tapered surfaces face each other, and the lens positioning during lens assembly is made highly accurate by bringing the tapered surfaces into contact with each other.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the environmental temperature range in which an optical device or imaging apparatus is used is wide, the lens will deform according to the temperature. In such a case, even if a plurality of lenses are positioned with high precision during lens assembly, for example, at the upper limit or lower limit of the environmental temperature, or in the vicinity thereof, the desired optical performance may not be obtained due to lens deformation such as expansion or contraction.

[0006] In view of such a background, one object of the present disclosure 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 Problems

[0007] To solve the above problems, a lens unit according to one aspect of the present disclosure includes: a first lens having a first lens optical surface, a first lens first tapered portion and a first lens second tapered portion provided on the 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 the 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; and is provided with.

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 Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Exemplary embodiments for implementing the present disclosure will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, relative positions of the components, etc. described in the following embodiments are arbitrary, and the configuration of the device to which the present disclosure is applied can be changed according to various conditions. Also, when indicating elements that are the same or functionally similar, the same reference numerals are used between the drawings.

[0011] Note that the lens unit according to the present disclosure is assumed to be used, for example, in a temperature range from a low temperature of minus several tens of degrees to a high temperature of around 100 degrees, such as a surveillance camera used outdoors or an in-vehicle camera. And in the following description, for convenience, the direction along the optical axis of the lens unit is defined as the optical axis direction, and the direction along the plane orthogonal to the optical axis is defined as the horizontal direction.

[0012] The lens unit according to the present disclosure includes a first lens and a second lens, and a tapered contact portion and a tapered position regulating portion are provided on the outer peripheral portions of the respective lenses. And the position between the lenses is defined by the gap of the position regulating portion, and the deterioration of the position accuracy due to thermal deformation in the optical axis direction is reduced by the contacting taper portions.

[0013] <First Embodiment> Hereinafter, with reference to FIGS. 1 to 5, a first embodiment of the present disclosure will be described. FIG. 1 shows a plan view of a lens unit 1 according to the first embodiment of the present disclosure, and FIG. 2 shows a schematic configuration of a cross section taken along line A-A of the lens unit 1 in FIG. 1. Further, FIG. 3 is an exploded cross-sectional view of the lens unit in FIG. 2, and FIG. 4 is a cross-sectional view of the first lens 11 and the second lens 12, which is a diagram for explaining the relationship between the respective lens tapered portions.

[0014] The lens unit 1 according to the present embodiment includes a first lens 11, a second lens 12, a pressing member 13, and a holding member 14. In the present embodiment, the pressing member 13 has a ring shape. The holding member 14 has a cylindrical shape and has a holding member abutting portion 141 that protrudes inward on one end side of the cylindrical shape. The two lenses are inserted into the inside of 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 abutting portion 141. Then, the pressing member 13 is inserted from behind the first lens 11 inside the cylindrical shape, and these lenses are sandwiched between the holding member abutting portion 141 and the pressing member 13, thereby fixing these lenses in the holding member 14.

[0015] In order to be mounted on a surveillance camera or an in-vehicle camera, the lens unit 1 is assumed to be exposed to a low temperature environment of, for example, -40 degrees to a high temperature environment of 100 degrees. Here, the first lens 11 and the second lens 12 are often manufactured as glass lenses having different materials, and in this case, the linear expansion coefficients of the respective lenses are also different. When the environmental temperature changes, for example, in the shapes of the first lens and the second lens described in detail later, the positional relationship in the optical axis direction of the lens surface may change due to thermal expansion or the like. Such a change in the positional relationship caused by the environmental temperature may cause the optical performance not to be obtained at an environmental temperature of -40 degrees or 100 degrees, even if the predetermined optical performance could be achieved at the time of lens assembly at a room temperature environment of 25 degrees.

[0016] This disclosure is obtained from such a perspective. Even when thermal expansion or contraction occurs in individual lenses due to an environmental temperature of -40 degrees or 100 degrees, the lens unit 1 of this embodiment suppresses changes in the lens interval and reduces deterioration of optical performance. Next, a specific method for suppressing changes in the lens interval will be described.

[0017] FIG. 3 shows an exploded cross-sectional view of the above-described lens unit 1. As shown in FIG. 3, the first lens 11 includes 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 at a position facing the second lens 12 and constitutes the optical 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 of the surface 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 inside 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 provided so as to be continuous from the first lens optical surface 115 on the outer periphery of the first lens optical surface 115 and continuous with the first lens second tapered portion 112 on 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 as not to be continuous. Also, 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 as not to be continuous. The first lens pressing surface 117 is provided on the outer periphery of the surface on the side opposite to the second lens 12 and is a surface that abuts against the pressing member 13. The first lens side surface 119 is configured as a surface parallel to the optical axis and facing the inner peripheral surface of the holding member 14.

[0018] The second lens 12 has a second lens second taper portion 123, a second lens first taper 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 arranged to face the first lens optical surface 115 and constitutes the optically effective portion of the second lens 12. The second lens second taper portion 123 has a conical surface shape provided on the outer periphery of the second lens optical surface 126 on the surface on the side where the first lens 11 is located. The second lens first taper portion 124 is a surface provided on the outer periphery of the second lens optical surface 126 and inside the second lens second taper portion 123 and is configured to have a conical surface shape. In the present embodiment, the second lens first taper portion 124 is provided on the outer periphery of the second lens optical surface 126 so as to be continuous with 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 taper portion 124 so as not to be continuous. Also, a fourth rounded portion having a curvature may be provided between the second lens first taper portion 124 and the second lens second taper portion 123 so as not to be continuous. The holding member contact surface 128 is a surface that comes into contact with the holding member abutting portion 141. The second lens side surface 130 is configured as a surface parallel to the optical axis and facing the inner peripheral surface of the holding member 14.

[0019] At this time, the inner diameters and outer diameters of the first lens second taper portion 112 and the second lens second taper portion 123 are determined such that at least a part of each conical surface shape can come into contact. Also, the outer diameter and inner diameter of the first lens first taper portion 113 and the outer diameter and inner diameter of the second lens first taper portion 124 are determined such that they do not come into contact at the manufacturing temperature. More preferably, from the relationship between the linear expansion coefficients of the first lens 11 and the second lens 12, the outer diameter and inner diameter of the taper portion where the first lens first taper portion and the second lens first taper portion come into contact are defined at the assumed maximum or minimum environmental temperature. Also, in the above description, the second taper portion that comes into contact is provided on the outer periphery of the first taper portion, but the second taper portion that comes into contact may be provided on the inner periphery of the first taper portion.

[0020] The first lens first tapered portion 113 and the second lens first tapered portion 124 that do not contact at the manufacturing temperature can suppress the radial position variation of the first lens 11 and the second lens 12 due to thermal deformation caused by changes in the ambient temperature. As a result, even if thermal expansion or thermal contraction occurs in each lens, the possibility of losing the desired optical performance in the lens unit 1 can be reduced.

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

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

[0023] Here, the influence on the thermal deformation in the radial direction and the thermal deformation in the optical axis direction of the lens will be described. When the contact portion is flat, when the distance from the lens optical axis to the contact position is D / 2, the change amount of the lens position in the radial direction is ΔH×(α2 - α1)×D / 2. Here, as shown in FIG. 4(a), 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. Since the first lens second tapered portion 112 and the second lens second tapered portion 123 are both conical surfaces, ideally they are in surface contact. However, in practice, due to the influence of, for example, surface accuracy, they are actually in point contact or partial surface contact. In this embodiment, for the sake of convenience, it is assumed that the tapered portions of each other are in surface contact, and the center of the contact surface is defined as the contact portion. Also, the diameter related to the contact portion is denoted as D, but the contact portion is not limited to this, and it can be the portion where the first lens second tapered portion 112 and the second lens second tapered portion 123 actually contact. When the contact portion between the lenses of the present disclosure is tapered, slippage occurs between the first lens second tapered portion 112 and the second lens second tapered portion 123 due to the thermal deformation in the radial direction. Thereby, the positional relationship between the first lens 11 and the second lens 12 in the optical axis direction can be changed. When the angle formed by the horizontal direction of the first lens second tapered portion 112 and the second lens second tapered portion 123 is θ2, the change amount of the positional relationship of the optical axis is ΔH×(α2 - α1)×tanθ2×D / 2. Therefore, the angle of the tapered surface and the contact position are determined from the linear expansion coefficients of the first lens 11 and the second lens 12 so that ΔH×(α1×h1 - α2×h2), which is the difference between the thermal deformation amounts of the first lens 11 and the second lens 12, becomes small.

[0024] Specifically, the angle of the tapered surface and the contact position are determined by the following formula (1). The best form is to make the change amounts obtained from the thermal deformation difference ΔH×(h2×α2 - h1×α1) in the optical axis direction between the first lens and the second lens and ΔH×(α2 - α1)×tanθ2×D / 2 equal, and set the angle of the tapered surface and the contact position that cancel these out. |(h2×α2 - h1×α1)|≧|(h2×α2 - h1×α1)-(α2 - α1)×tanθ2×D / 2| ···· Formula (1)

[0025] At this time, when α1 > α2 and α1×h1 > α2×h2, and when α1 < α2 and α1×h1 < α2×h2, it is preferable to have a tapered shape with the outer periphery facing the second lens as shown in Fig. 4(a). Also, when α1 > α2 and α1×h1 < α2×h2, and when α1 < α2 and α1×h1 > α2×h2, by forming a tapered shape with the outer periphery facing the first lens as shown in Fig. 5, the directions of thermal deformation in the optical axis direction are the same, and the deterioration of the position between the lenses can be reduced.

[0026] Fig. 5 shows a modified example of the lens unit according to the present embodiment configured to correspond to the cases of α1 > α2 and α1×h1 < α2×h2, and α1 < α2 and α1×h1 > α2×h2. Regarding the same configurations as those in the lens unit 1 described with reference to Fig. 3 and the like, the same reference numerals are used here and the description thereof is omitted. The lens unit 5 shown as a modified example includes a first lens 51 and a second lens 52. On one surface of the first lens 51, in order from the first lens optical surface 515 provided substantially at the center, a first lens first tapered portion 513, a first lens flat portion 511, and a first lens second tapered portion 512 are provided. Also, on one surface of the second lens 52, in order from the second lens optical surface 526 provided substantially at the center, a second lens first tapered portion 524, a first lens flat portion 522, and a first lens second tapered portion 523 are provided. The first lens 51 and the second lens 52 are arranged such that the first lens optical surface 515 and the second lens optical surface 526 face each other. In this modified example, the arrangement of the first tapered portion and the second tapered portion with respect to the optical surface in each lens is different from that in the above-described embodiment. However, even in this arrangement, the same effect can be obtained if the above conditions are satisfied.

[0027] Next, the preferred 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] When thermal deformation in the radial direction of the first lens 11 and the second lens 12 occurs due to a change in the environmental temperature, the first lens first tapered portion 113 and the second lens first tapered portion 124 are required to function to prevent a change in the radial positional relationship between the lenses beyond the gap amount at the temperature during manufacturing. That is, a shape that receives a large radial load is preferable. Therefore, the taper angle θ1, which is the horizontal angle formed between the first lens first tapered portion 113 and the second lens first tapered portion 124, is preferably in the range of 45 degrees or more and 90 degrees or less. Also, it is preferable that the respective taper angles be equal so that the tapered portions of each other maintain a gap until immediately before contact.

[0029] As described above, the angles θ1 of the first lens first tapered portion 113 and the second lens first tapered portion 124 are equal, and from the viewpoint of lens position regulation, it is preferable that the horizontal angle formed be in the range of 45 degrees or more and 90 degrees or less. And the angles θ2 of the first lens second tapered portion 112 and the second lens second tapered portion 123 are preferably equal to each other so that these tapered portions can be in surface contact. Also, from the difference in the above viewpoints, it is preferable that the angle of θ1 be larger than the angle of θ2. By each taper angle satisfying this condition, even if thermal expansion or thermal contraction of each lens occurs, the lens unit 1 with a reduced possibility of losing the desired optical performance can be easily manufactured.

[0030] Next, the assembly of the lens unit 1 according to one aspect of the present disclosure will be described with reference to the flowchart of FIG. 6.

[0031] First, in step S601, based on the optical conditions required for the lens unit 1, the material of the first lens 11, the material of the second lens 12, and the shape of each optical surface are determined. Next, in step S602, 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 θ2 of the second tapered portion and the contact position are determined. Also, the angle θ1 of the first tapered portion is determined accordingly. Thereby, each dimension of the first lens 11 and each dimension of the second lens 12 are determined, and these lenses are manufactured.

[0032] Next, in step S603, the second lens 12 is inserted into the holding member 14. This operation is terminated in step S604 by bringing the holding member contact surface 128 of the second lens into contact with the holding member abutting portion 141. The holding member contact surface 128 of the second lens is provided at the outer peripheral portion of the surface opposite to the surface on which the second lens optical surface 126 of the second lens 12 is provided, and constitutes a flat surface 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 that time, the insertion is performed while applying vibration in a direction (horizontal direction) in a plane perpendicular to the insertion direction to the holding member 14 and the first lens 11. This operation is terminated in step S606 by bringing the first lens second tapered portion 112 into contact with the second lens second tapered portion 123.

[0034] As described above, by applying vibration in the horizontal plane when inserting the first lens 11, the optical axes of these lenses are aligned. Therefore, if either one of the first lens side surface 119 of the first lens 11 and 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 disposed at a desired position with respect to the holding member 14. Further, depending on the relationship between the assumed temperature during use and the reference temperature during manufacturing, by determining which of the first lens side surface 119 and the second lens side surface 130 abuts against the holding member 14, it is possible to eliminate the restraint from the abutting surface against the thermal deformation of the non-abutting lens. As described above, by making only one of these lenses abut against the inside of the holding member 14, the alignment of each lens in the optical axis direction becomes easy. However, for example, when the difference between the assumed temperature and the reference temperature during manufacturing is not so large, or when the holding member 14 is relatively easily deformed, etc., and the restraint of the holding member 14 on the outer diameter of the lens is not so much of a problem, both lenses may abut against the inside of the holding member 14.

[0035] Finally, in step S607, the pressing member 13 is inserted into the holding member 14. Then, in step S608, the pressing member 13 is brought into contact with the first lens pressing surface 117 to fix the pressing member 13 to the holding member 14. For example, by going through the above steps, the 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 component such as a caulking ring, but its form is not limited to the shape of the embodiment. For example, components such as a plurality of claws or screws can also be used as the pressing member 13. Further, the above-described manufacturing method is an example, and steps other than the method of determining the angle of the second tapered portion and the contact position in step S602 can be replaced by various known available methods.

[0037] In order to obtain the effects of the present disclosure, it is preferable that both lenses expand or contract thermally individually according to the environmental temperature. 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 separated from each other.

[0038] <Application Example of the First Embodiment> Next, an imaging device equipped with the lens unit 1 according to the above-described first embodiment will be described with reference to the drawings, taking an in-vehicle camera as an example. FIG. 7 is a diagram showing a schematic configuration of the in-vehicle camera according to the present disclosure, FIG. 7(a) shows an external perspective view, and FIG. 7(b) shows an outline of the components.

[0039] The in-vehicle camera 100 according to the present disclosure includes an internal optical system 102 having a plurality of lenses, an image sensor 103 that receives light that has passed through the optical system, and a housing 101 that encloses these components and to which the lens unit 1 described in the first embodiment is applied. The in-vehicle camera 100 is mounted, for example, on an automobile that is exposed to direct sunlight outdoors in summer and is assumed to be 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 desired optical performance cannot be obtained even in such an environment in the lens unit 1. The image sensor 103 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor. The image sensor has a function of converting light incident through 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 taper portion 113 provided on the outer periphery of the first lens optical surface 115, and a first lens second taper 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 taper portion 124 provided on the outer periphery of the second lens optical surface 126 facing the first lens first taper portion 113. The second lens 12 further has a second lens second taper portion 123 provided on the outer periphery of the second lens optical surface 126 and arranged to be in contact with the first lens second taper portion 112 at the contact portion. The first lens second taper portion 112 and the second lens second taper portion 123 have the same taper angle (θ2, the angle formed by the taper surface and the direction perpendicular to the optical axis) with each other and are arranged to be in contact with each other on the conical surfaces. The contact portion ideally becomes a contact surface, but in view of thermal deformation and the like, in order to define a reference portion for deformation, for example, the central portion of the contact surface (the contact portion of the taper portions 112 and 123 in FIG. 4(b)) can be used as the contact portion. Then, based on the optical conditions required for the lens unit 1, the material of the first lens 11, the material of the second lens 12, and the shapes of the respective optical surfaces are selected. This selection is made so that the change in the distance between the surfaces of the first lens 11 and the second lens 12 in the optical axis direction during thermal deformation is small.

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

[0042] Also, in the above-described embodiment, when the lower limit of the assumed temperature is -40 degrees, this case is adopted. However, for example, it may be set by multiplying a safety factor by the minimum value of the temperature of the in-vehicle camera actually measured outdoors.

[0043] Here, the angle formed by the first taper portion 113 of the first lens and the first taper portion 124 of the second lens in a direction perpendicular to the optical axis is preferably larger than the angle formed by the second taper portion 112 of the first lens and the second taper portion 123 of the second lens in a direction perpendicular to the optical axis. Also, the angle formed by the first taper portion 113 of the first lens 11 and the first taper portion 124 of the second lens 12 in a direction perpendicular to the optical axis is preferably 45 degrees or more and 90 degrees or less from the viewpoint of lens position regulation of the lens unit 1.

[0044] Note that, 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 abutting portion 141 that abuts against a holding member contact surface 128 provided on a surface opposite to the surface on which the second lens second tapered portion 123 is formed. The holding member abutting portion 141 can be provided so as to project inward from the inner peripheral surface of the cylindrical holding member 14. Further, the lens unit 1 further includes a pressing member 13 that abuts against a surface (117) provided on the side opposite to the surface on which the first lens second tapered portion 112 is provided, and sandwiches the first lens 11 and the second lens 12 together with the holding member abutting portion 141. And at least one or both of the outer peripheral surface (side surface 119) of the first lens 11 and the outer peripheral surface (side surface 130) of the second lens 12 can be brought into contact with the inner peripheral surface of the holding member 14. Also, in the illustrated embodiment, the first lens optical surface 115 and the second lens optical surface 126 are separated from each other.

[0045] Further, 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 inserting the first lens 11 into the holding member 14 and continuing the insertion until the first lens second tapered portion 112 abuts against the second lens second tapered portion 123 at the abutting portion. And the method further includes inserting the pressing member 13 into the holding member 14 to fix these lenses to the holding member 14. Also, when fixing the lens, the pressing member 13 presses and fixes the first lens 11 in the insertion direction of the first lens 11 from the first lens pressing surface 117, which is a surface opposite to the surface on which the first lens second tapered portion 112 of the first lens 11 is provided. Here, the first lens first tapered portion 113 and the second lens first tapered portion 124 are separated from each other. And the angle θ2 and the abutting position of the second tapered portion are determined based on Equation (1).

[0046] By using the lens unit 1 as described above or the lens unit 1 obtained by the manufacturing method, in the lens unit 1, it is possible to reduce the possibility that the desired optical performance cannot be obtained even in a usage environment such as an in-vehicle camera. Note that the present disclosure shows an example in which the lens unit 1 is applied to an in-vehicle camera. However, the lens unit 1 according to the present disclosure is also applicable 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. Further, as optical devices, it is also applicable to binoculars, microscopes, telescopes, and the like. These optical devices are composed of an optical system including the above-described lens unit 1 and a housing that encloses the optical system.

[0047] <Example> Hereinafter, the effects of the present disclosure will be described with reference to examples in which the present disclosure is embodied 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] Regarding the positional variation of each lens in the optical axis direction, CL-P015 and CL-P070 of the KEYENCE multi-color laser coaxial displacement meter CL-3000 series were arranged above and below the lens unit 1 for measurement.

[0049] [Example 1] In this example, for the first lens, M-TAFD305 (manufactured by HOYA: linear expansion coefficient α1 = 60×10 -7 / °C) was used. The lens shape was a convex meniscus lens with an outer diameter of φ36.6 mm, a center thickness of 6.8 mm, and a flange thickness of 1.7 mm. For the second lens, M-PCD55AR (manufactured by HOYA: linear expansion coefficient α2 = 92×10 -7 / °C) was used. The lens shape was a concave meniscus lens with an outer diameter of φ36.6 mm, an overall height of 8.0 mm, a center thickness of 1.8 mm, and a flange thickness of 2.8 mm.

[0050] At this time, using Equation (1), the dimensions of each lens were determined so that the amount of deformation due to thermal deformation would be small. Specifically, the outer diameter D of the contact portion was set to φ30 mm, the projection distance h1 in the optical axis direction from the contact portion to the first lens optical surface was set to 12 mm, the projection distance h2 in the optical axis direction from the contact portion to the second lens optical surface was set to 11 mm, and the angle θ2 of the second tapered portion was set to 31 degrees. Also, 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, and the tapered angle θ1 was set to 60 degrees.

[0051] Next, at a location with an indoor temperature of 25 degrees, the second lens and then the first lens were inserted into the holding member in this order. At this time, by applying a force in the optical axis direction, the first tapered portions of the first and second lenses were drawn in and these lenses were inserted into the holding member. After the insertion of the first lens, when observing the second tapered portion of the first lens and the second tapered portion of the second lens from above the first lens, it was confirmed that interference fringes were formed. Note that by the formation of these interference fringes, it was confirmed that the second tapered portion of the first lens and the second tapered portion of the second lens were in contact with each other's surfaces.

[0052] Finally, the first lens 11 was pressed from above using a caulking ring (pressing member 13), and the lens unit 1 was assembled. Thereafter, a KEYENCE multi-color laser coaxial displacement meter CL-3000 series CL-P015 was arranged 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 lens, the first lens 11 was aligned with the apex and the second lens 12 was aligned with the bottom surface. When measured, the total height of the central portion of the lens unit 1 was 10.360 mm.

[0053] Next, using a heater, the entire lens unit 1 was heated to a temperature of 100 degrees and measured again by the same method. As a result, the total height of the central portion of the lens unit 1 was 10.368 mm. Since the variation value of the total height of the central portion of the lens unit 1 calculated from the form and the linear expansion coefficient of the lens unit 1 was 8.5 μm, it was confirmed that the distance variation between the first lens 11 and the second lens 12 was 1 μm or less, which was good.

[0054] [Comparative Example 1] Next, as a comparative example, a lens unit 1 was created under the following conditions and the same measurements as in Example 1 were performed. The details are described below.

[0055] In this comparative example, as in Example 1, for the first lens 11, M-TAFD305 (manufactured by HOYA: linear expansion coefficient α1 = 60×10 -7 / °C) was used. Also, the lens shape was a convex meniscus lens with an outer diameter of φ36.6 mm, a center thickness of 6.8 mm, and a flange thickness of 1.7 mm. For the second lens 12, M-PCD55AR (manufactured by HOYA: linear expansion coefficient α2 = 92×10 -7 / °C) was used. The lens shape was a concave meniscus lens with an outer diameter of φ36.6 mm, an overall height of 8.0 mm, a center thickness of 1.8 mm, and a flange thickness of 2.8 mm.

[0056] At this time, the contact portion corresponding to the second tapered portion in Example 1 was made into a flat surface instead of a taper. For the first tapered portion, the outer diameter of the first tapered portion of the first lens was φ27.005 mm and 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, at a place where the indoor temperature was 25 degrees, these were inserted into the holding member in the order of the second lens and the first lens. At this time, by applying a force in the optical axis direction, the first tapered portions of the first and second lenses were pulled in and these lenses were inserted into the holding member. After the insertion of the first lens, when observing the flat surfaces of the first lens and the second lens, which are the contact portions, from above the first lens, it was confirmed that interference fringes were formed.

[0058] Finally, the first lens 11 was pressed from above using a caulking ring (pressing member 13), and the lens unit 1 was assembled. Thereafter, a KEYENCE multi-color laser coaxial displacement meter CL-3000 series CL-P015 was 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 lens, the first lens 11 was aligned with the vertex and the second lens 12 was aligned with the bottom surface. As a result of the measurement, the total height of the central portion of the lens unit 1 was 10.453 mm.

[0059] Next, the entire lens unit 1 was heated to 100 degrees using a heater and measured again by the same method. As a result, the total height of the central portion of the lens unit 1 was 10.464 mm. Since the variation value of the total height of the central portion of the lens unit 1 calculated from the form and the linear expansion coefficient of the lens unit 1 was 8.5 μm, the distance variation between the first lens 11 and the second lens 12 became 2 μm or more.

[0060] Note that the present disclosure includes the following configurations. (Configuration 1) A first lens having a first lens optical surface, a first lens first tapered portion and a first lens second tapered portion provided on the outer periphery of the first lens optical surface, A second lens optical surface facing the first lens optical surface, a second lens first tapered portion provided on the 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) The diameter of the first lens first tapered portion is larger than the diameter of the second lens second tapered portion, The linear expansion coefficient α1 of the first lens, the distance h1 in the optical axis direction between the vertex of the surface of the first lens on the side of the second lens and the contact portion, the linear expansion coefficient α2 of the second lens, the distance h2 in the optical axis direction between the vertex of the surface of the second lens on the side of the first lens and the contact portion, the outer diameter D of the contact portion, and when the angle formed by the tapered surface constituting the contact portion and the direction perpendicular to the optical axis is θ, the formula |(h2 × α2 - h1 × α1)| ≥ |(h2 × α2 - h1 × α1) - (α2 - α1) × tan θ × D / 2| The lens unit according to Configuration 1 that satisfies the above. (Configuration 3) The angle formed by the first tapered portion of the first lens and the first tapered portion of the second lens in the direction perpendicular to the optical axis is larger than the angle formed by the second tapered portion of the first lens and the second tapered portion of the second lens in the direction perpendicular to the optical axis. The lens unit according to Configuration 1 or 2. (Configuration 4) The angle formed by the first tapered portion of the first lens and the first tapered portion of the second lens in the direction perpendicular to the optical axis is 45 degrees or more and 90 degrees or less. The lens unit according to any one of Configurations 1 to 3. (Configuration 5) The optical surface of the first lens and the optical surface of the second lens are arranged separately. The lens unit according to any one of Configurations 1 to 4. (Configuration 6) The first lens and the second lens are glass lenses. The lens unit according to any one of Configurations 1 to 5. (Configuration 7) In the first lens, at least two of the optical surface of the first lens, the first tapered portion of the first lens, and the second tapered portion of the first lens are arranged continuously. 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. The lens unit according to any one of Configurations 1 to 6. (Configuration 8) A holding member that houses the first lens and the second lens and has an abutting portion that abuts against a flat portion of the second lens provided at an outer peripheral portion of a surface opposite to the surface on which the second lens optical surface is provided. A lens unit according to any one of Configurations 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 sandwiches the first lens and the second lens together with the abutting portion. (Configuration 9) Further comprising a cylindrical holding member that houses the first lens and the second lens. A 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 encloses the optical system, An optical device comprising the same. (Configuration 11) An optical system including the lens unit according to any one of Configurations 1 to 9, An imaging element that receives light that has passed through the optical system, A housing that encloses the optical system and the imaging element, An imaging device comprising the same.

[0061] The present disclosure has been described above with reference to embodiments and examples, but the present disclosure is not limited to these embodiments and the like. Inventions modified within a range not contrary to the spirit of the present disclosure, and inventions equivalent to the present disclosure are also included in the present disclosure. Further, the above-described embodiments, modifications, and examples can be appropriately combined within a range not contrary to the spirit of the present invention.

Explanation of Reference Numerals

[0062] 1...Lens unit 11...First lens 12...Second lens 13...Pressing member 14...Holding member 112 ··· First lens, second tapered portion 113 ··· First lens, first tapered portion 115 ··· First lens optical surface 117 ··· Pressing surface of the first lens 119 ··· First lens side surface 123 ··· Second lens, second tapered portion 124 ··· Second lens, first tapered portion 126 ··· Second lens optical surface 128 ··· Contact surface of the holding member 130 ··· Second lens side surface 130 141 ··· Contact portion of the holding member

Claims

1. A first lens having a first lens optical surface, a first lens first taper portion and a first lens second taper portion provided on the 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 taper portion provided on the outer periphery of the second lens optical surface spaced apart from and facing the first lens first taper portion, and a second lens second taper portion provided on the outer periphery of the second lens optical surface and abutting against the first lens second taper portion at an abutting portion; A lens unit comprising the same.

2. The diameter of the first lens first taper portion is larger than the diameter of the second lens second taper portion, The linear expansion coefficient α1 of the first lens, the distance h1 in the optical axis direction between the vertex of the surface of the first lens on the side of the second lens and the abutting portion, the linear expansion coefficient α2 of the second lens, the distance h2 in the optical axis direction between the vertex of the surface of the second lens on the side of the first lens and the abutting portion, the outer diameter D of the abutting portion, and the angle formed by the taper surface constituting the abutting portion and the direction perpendicular to the optical axis is θ, then the formula |(h2×α2 - h1×α1)| ≥ |(h2×α2 - h1×α1) - (α2 - α1)×tanθ×D / 2| The lens unit according to Claim 1, which satisfies the above formula.

3. The angle formed by the first lens first taper portion and the second lens first taper portion in the direction perpendicular to the optical axis is larger than the angle formed by the first lens second taper portion and the second lens second taper portion in the direction perpendicular to the optical axis. The lens unit according to Claim 1.

4. The angle formed by the first lens first taper portion and the second lens first taper portion in the direction perpendicular to the optical axis is 45 degrees or more and 90 degrees or less. The lens unit according to Claim 1.

5. The first lens optical surface and the second lens optical surface are arranged to be spaced apart. The lens unit according to Claim 1.

6. The first lens and the second lens are glass lenses. The lens unit according to Claim 1.

7. In the first lens, at least two of the first lens optical surface, the first lens first taper portion, and the first lens second taper portion are arranged continuously, In the second lens, at least two of the second lens optical surface, the second lens first taper portion, and the second lens second taper portion are arranged continuously. The lens unit according to Claim 1.

8. A holding member that houses the first lens and the second lens and has an abutting portion that abuts against a flat portion of the second lens provided at an outer peripheral portion of a surface opposite to the surface on which the second lens optical surface is provided. A lens unit according to claim 1, 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 sandwiches the first lens and the second lens together with the abutting portion.

9. Further comprising a cylindrical holding member that houses the first lens and the second lens. A 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.

10. An optical system including the lens unit according to any one of claims 1 to 9. A housing that encloses the optical system. An optical device comprising the above.

11. An optical system including the lens unit according to any one of claims 1 to 9. An imaging element that receives light that has passed through the optical system. A housing that encloses the optical system and the imaging element. An imaging device comprising the above.

Images