Lens unit

Abstract

To provide a lens unit that can suppress changes from its initial assembled condition.SOLUTION: A lens unit according to one embodiment of the present invention includes: multiple lenses arranged along an optical axis of the lens unit, the multiple lenses including at least one resin lens; a lens barrel housing the multiple lenses, the lens barrel including a fit-receiving portion; and a pressure member configured to press the multiple lenses housed in the lens barrel. The resin lens includes a fit-in portion fittable into the fit-receiving portion. Each of the fit-in portion and the fit-receiving portion has a tapered shape such that the diameter of a circle centered on the optical axis varies depending on its position in a direction along the optical axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lens unit.

Background Art

[0002] Conventionally, a lens unit is known that includes at least one resin lens, a plurality of lenses arranged along an optical axis, a lens barrel that houses the plurality of lenses, and a pressing member that presses the plurality of lenses housed in the lens barrel. Such a lens unit is used in a camera mounted on a moving body such as an automobile or a drone, or a surveillance camera provided in a building or the like.

[0003] As the above lens unit, in order to suppress a change in the performance of the lens unit due to deformation of the resin lens, the resin lens has a lens portion that acts as a lens and a flange portion provided outside the lens portion, and a configuration in which the stress applied to the resin lens is concentrated on the flange portion is disclosed (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of Patent Document 1, the performance of the lens unit may change when the lens unit changes from the state at the time of assembly.

[0005] An object of the present invention is to provide a lens unit capable of suppressing changes from the state at the time of assembly.

Means for Solving the Problems

[0006] A lens unit according to one aspect of the present invention includes a plurality of lenses arranged along the optical axis, including at least one resin lens; a lens barrel including a fitting portion for housing the plurality of lenses; and a pressing member for pressing the plurality of lenses housed in the lens barrel, wherein the resin lens includes a fitting portion that can be fitted into the fitting portion, and each of the fitting portion and the fitting portion includes a tapered shape in which the diameter of the circle centered on the optical axis differs depending on the position in the direction along the optical axis. The resin lens includes a ring-shaped first portion that abuts against the first member, and a ring-shaped second portion that abuts against the second member on the opposite side of the direction along the optical axis from the first portion, and when the resin lens is viewed from the direction along the optical axis, the second portion is located between the fitting portion and the first portion. . [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a lens unit that can suppress changes from its assembled state. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view of the lens unit according to the first embodiment. [Figure 2] Figure 1 is a plan view of the resin lens in the lens unit. [Figure 3] This is a longitudinal cross-sectional view of a lens unit relating to a comparative example. [Figure 4] This is a longitudinal cross-sectional view of the lens unit according to the second embodiment. [Figure 5] This is a plan view of the second resin lens in the lens unit shown in Figure 4. [Figure 6] This is a longitudinal cross-sectional view of a lens unit according to the third embodiment. [Figure 7] Figure 6 is a plan view of the resin lens in the lens unit. [Modes for carrying out the invention]

[0009] A lens unit according to an embodiment of the present invention will be described in detail with reference to the drawings. The following embodiments are illustrative examples of lens units that embody the technical concept of this embodiment and are not limited thereto. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present invention to those described, but are merely illustrative examples. The size, positional relationships, etc. of the members shown in each drawing may be exaggerated for clarity of explanation. In addition, in the following description, the same name and reference numerals indicate the same or similar members, and detailed explanations will be omitted as appropriate.

[0010] [First Embodiment] <Example configuration of lens unit 100> The configuration of the lens unit 100 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a longitudinal cross-sectional view illustrating the configuration of the lens unit 100. Figure 2 is a plan view of the resin lens 2 in the lens unit 100 of Figure 1. Figure 2 shows the resin lens 2 viewed from the negative Z-axis direction. Note that the positive Z-axis direction means the direction in which the arrow representing the Z-axis points. The negative Z-axis direction means the direction opposite to the positive Z-axis direction.

[0011] As shown in Figure 1, the lens unit 100 includes a lens barrel 1, a resin lens 2, a light-shielding member 3, a spacing ring 4, a glass lens 5, and a pressing member 6.

[0012] The lens barrel 1 includes a fitting portion B and houses the resin lens 2 and the glass lens 5. The material of the lens barrel 1 is metal, for example, aluminum. However, the material of the lens barrel 1 may be resin or the like.

[0013] In this embodiment, the lens barrel 1 is formed in a hollow, substantially cylindrical shape. The lens barrel 1 houses a resin lens 2, a light-shielding member 3, a spacing ring 4, and a glass lens 5 in that order on the inside. The lens barrel 1 includes a small diameter portion 11 and a contact surface 12.

[0014] The small-diameter portion 11 is an annular portion provided on a part inside the lens barrel 1. The inner diameter of the small-diameter portion 11 is smaller than the outer diameter of the resin lens 2 accommodated in the lens barrel 1. The small-diameter portion 11 includes the fitting portion B.

[0015] The fitting portion B includes a tapered shape with different diameters centered on the optical axis C according to the position in the direction along the optical axis C. In the present embodiment, the fitting portion B includes a substantially conical tapered shape in which the diameter of the circle centered on the optical axis C increases as it goes in the direction (negative Z-axis direction) of the image formed by the lens unit 100.

[0016] The contact surface 12 is a surface substantially orthogonal to the optical axis C of the lens unit 100 in the small-diameter portion 11. The contact surface 12 abuts against the resin lens 2 accommodated in the lens barrel 1.

[0017] The resin lens 2 and the glass lens 5 correspond to a plurality of lenses arranged along the optical axis C. In the present embodiment, the resin lens 2 is a resin lens made of resin. The glass lens 5 is made of glass. However, the lens unit 100 may have a resin lens different from the resin lens 2 instead of the glass lens 5.

[0018] At least a part of the outer periphery of the resin lens 2 is formed in a substantially cylindrical shape. The outer diameter of the substantially cylindrical shape in the resin lens 2 is smaller than the inner diameter of the lens barrel 1. Thereby, the resin lens 2 can be accommodated in the lens barrel 1 with a gap (air layer) left between the resin lens 2 and the lens barrel 1.

[0019] The resin lens 2 includes a lens portion 21 and a flange portion 22. The lens portion 21 includes the optical axis C at its center and acts as a lens with respect to the light incident on the resin lens 2.

[0020] The flange portion 22 is provided outside the lens portion 21. The flange portion 22 does not act as a lens with respect to the light incident on the resin lens 2. The flange portion 22 includes a fitting portion A, a first portion 221, and a second portion 222.

[0021] The fitting portion A can be fitted into the fitted portion B. The diameter of the tapered shape in the fitting portion A is slightly smaller than the diameter of the tapered shape in the fitted portion B as a whole. The fitting portion A is formed on the surface on the side in the direction (positive Z-axis direction) where the object in the flange portion 22 is located. The fitting portion A includes a tapered shape with different diameters centered on the optical axis C according to the position in the direction along the optical axis C. In the present embodiment, the fitting portion A includes a tapered shape of a substantially conical shape in which the diameter of a circle centered on the optical axis C increases as it goes in the negative Z-axis direction.

[0022] The first part 221 is an annular part that abuts against the lens barrel 1. The lens barrel 1 corresponds to an example of the first member. The first part 221 is a surface substantially orthogonal to the optical axis C formed on the positive Z-axis side of the flange portion 22. The first part 221 abuts against the surface substantially orthogonal to the optical axis C in the small-diameter portion 11 of the lens barrel 1 in an annular region.

[0023] The second part 222 is an annular part that abuts against the spacer ring 4 on the side opposite to the first part 221 in the direction along the optical axis C. The spacer ring 4 corresponds to an example of the second member. The second part 222 is a surface substantially orthogonal to the optical axis C formed on the negative Z-axis side of the flange portion 22. The surface substantially orthogonal to the optical axis C in the spacer ring 4 is abutted against the second part 222 in an annular region via the light-shielding member 3.

[0024] As shown in FIG. 2, when the resin lens 2 is viewed from the direction along the optical axis C, the second part 222 is located between the fitting portion A and the first part 221. In other words, the positional relationship among the fitting portion A, the first part 221, and the second part 222 is the fitting portion A, the second part 222, and the first part 221 in this order from the closest to the optical axis C.

[0025] As shown in FIG. 1, the light-shielding member 3 has a function of blocking external light, unintended reflected light, etc. that enter the lens unit 100. The light-shielding member 3 is, for example, a sheet-like member having a thickness of about several tens of μm. The material of the light-shielding member 3 is not particularly limited, and resin, metal, etc. can be applied. Note that the light-shielding member 3 is not an essential component.

[0026] The spacing ring 4 restricts the distance between the resin lens 2 and the glass lens 5 to a predetermined interval (distance). The spacing ring 4 is formed in a substantially cylindrical shape and is housed in the lens barrel 1 with the glass lens 5 supported internally. The outer diameter of the spacing ring 4 is slightly smaller than the inner diameter of the lens barrel 1. This allows the spacing ring 4 to be fitted into the lens barrel 1. There are no particular restrictions on the material of the spacing ring 4, but resin or metal can be used.

[0027] The pressing member 6 presses the resin lens 2 and glass lens 5 housed in the lens barrel 1. The pressing member 6 has a threaded portion on a part of its outer surface. The pressing member 6 presses the spacing ring 4 that supports the resin lens 2, the light-shielding member 3, and the glass lens 5 by connecting its threaded portion to a threaded portion provided on the inner side of the lens barrel 1 on the negative Z-axis side. In this way, the pressing member 6 can fix each of these components to the lens barrel 1. There are no particular restrictions on the material of the pressing member 6, but resin or metal can be used.

[0028] <Function of lens unit 100> Next, with reference to Figure 1, the assembly method and operation of the lens unit 100 will be explained.

[0029] When assembling the lens unit 100, the resin lens 2 is first inserted into the inside of the lens barrel 1. The first portion 221 of the resin lens 2 abuts against the contact surface 12 of the small diameter portion 11 of the lens barrel 1.

[0030] Before the pressing force is applied by the pressing member 6, there is a slight gap between the fitting portion A of the resin lens 2 and the fitted portion B of the lens barrel 1. The radial positioning of the resin lens 2 is performed while this gap is present.

[0031] Next, the spacing ring 4 is inserted into the inside of the lens barrel 1. The surface of the spacing ring 4 that is approximately perpendicular to the optical axis C abuts against the second portion 222 of the resin lens 2 via the light-shielding member 3. After that, the spacing ring 4 supports the glass lens 5 from the inside.

[0032] Next, by connecting the threaded portion of the pressing member 6 to the threaded portion of the lens barrel 1, a pressing force is applied to the resin lens 2 in the direction along the optical axis C. The applied pressing force is transmitted to each component housed in the lens barrel 1. In the resin lens 2, a pressing force F is applied from the spacing ring 4 to the second portion 222. As a reaction to the pressing force F, a resistance force N is generated in the first portion 221 of the resin lens 2 in the direction opposite to the pressing force F.

[0033] Comparing the first part 221 and the second part 222, the second part 222 is located closer to the optical axis C. In this positional relationship, the resin lens 2 is subjected to moments M1 and M2. Due to moments M1 and M2, the resin lens 2 deforms so that its central portion protrudes in the positive Z-axis direction.

[0034] Due to the above deformation of the resin lens 2, the gap between the fitting portion A and the fitted portion B is filled, and the fitting portion A and the fitted portion B come into contact. Due to the contact between the fitting portion A and the fitted portion B, a resistance force N from the fitting portion A acts on the resin lens 2, and the resistance force N balances the moments M1 and M2. Because the resistance force N balances the moments M1 and M2, changes in the shape of the resin lens 2 due to ambient temperature around the lens unit 100 and the passage of time are suppressed.

[0035] The larger the taper angles of the mating portion A and the mated portion B, that is, the larger the inclination angle of each surface of mating portion A and the mated portion B with respect to the optical axis C, the closer the direction of the drag force N becomes to parallel with respect to the optical axis C. As a result, a small drag force N can balance the moments M1 and M2, so it is preferable for the taper angles of mating portion A and the mated portion B to be large.

[0036] <Comparative Example> Here, we will explain a comparative example of the lens unit.

[0037] In recent years, the use of lens units containing resin lenses has been increasing in applications such as automotive systems, where performance must be guaranteed over a wide temperature range. Among such lens units, those that clamp and fix the lens to the lens barrel are well-known.

[0038] Resin lenses undergo significant shape changes due to temperature fluctuations and over time. Therefore, it is preferable to set the pressing force applied to the resin lens as high as possible during assembly, i.e., during the manufacturing of the lens unit, to ensure sufficient pressure during use. However, because resin lenses are softer than glass lenses, a higher pressing force results in greater deformation. Lens deformation alters the performance of the lens unit. Therefore, lens units are required to maintain the pressing force applied to the resin lens during use while suppressing performance changes due to resin lens deformation.

[0039] Figure 3 is a longitudinal cross-sectional view showing the configuration of a lens unit 100X according to a comparative example. The lens unit 100X includes a first light-shielding member 7, a resin lens 2X, a first lens 5X, a second light-shielding member 8, a spacing ring 4X, a second lens 9, and a pressing member 6X. These members are arranged in the above order in the direction along the optical axis CX and housed in the lens barrel 1X.

[0040] The resin lens 2X and the first lens 5X are made of resin. The second lens 9 is made of glass. Both the resin lens 2X and the first lens 5X have at least a portion of their outer circumference formed in a substantially cylindrical shape. The outer diameter of the substantially cylindrical shape of the resin lens 2X and the first lens 5X is smaller than the inner diameter of the lens barrel 1X. As a result, the resin lens 2X and the first lens 5X can be housed with a gap between them and the lens barrel 1X.

[0041] The resin lens 2X has a first lens portion 21X and a first flange portion 22X. The first lens portion 21X is located in the center of the resin lens 2X and acts as a lens for light incident on the resin lens 2X. The first flange portion 22X is located on the outside of the first lens portion 21X. The surface of the first flange portion 22X on the positive Z-axis side presses the lens barrel 1X in a direction along the optical axis CX. The surface of the first flange portion 22X on the negative Z-axis side is pressed from the first lens 5X in a direction along the optical axis CX.

[0042] The first lens 5X has a second lens portion 51X and a second flange portion 52X. The second lens portion 51X is located in the center of the first lens 5X and acts as a lens for light incident on the first lens 5X. The second flange portion 52X is located on the outside of the second lens portion 51X. The surface of the second flange portion 52X on the positive Z-axis side presses the resin lens 2X in a direction along the optical axis CX. The surface of the second flange portion 52X on the negative Z-axis side is pressed from the spacing ring 4X in a direction along the optical axis CX.

[0043] The spacing ring 4X is formed in a substantially cylindrical shape and supports the second lens 9 on its inside. The spacing ring 4X restricts the distance between the first lens 5X and the second lens 9 to a predetermined distance. The outer diameter of the spacing ring 4X is slightly smaller than the inner diameter of the lens barrel 1X. This allows the spacing ring 4X to be fitted into the lens barrel 1X with a small gap between them.

[0044] The first light-shielding member 7 and the second light-shielding member 8 block ambient light incident on the lens unit 100X and unintended reflected light inside the lens unit 100X.

[0045] The pressing member 6X has a threaded portion on a part of its outer surface. The pressing member 6X presses each component housed in the lens barrel 1X by connecting with the threaded portion formed on the inner surface of the lens barrel 1X.

[0046] In the assembly of the lens unit 100X, after inserting the first light-shielding member 7, the resin lens 2X is inserted into the lens barrel 1X and positioned in the direction along the optical axis CX by contacting the lens barrel 1X via the first light-shielding member 7. The spacing ring 4X supporting the second lens 9 and the second light-shielding member 8 are also sequentially inserted into the lens barrel 1X.

[0047] The radial positioning of each component is achieved by fitting each component with either the lens barrel 1X, the first lens 5X, or the spacing ring 4X. The first lens 5X is positioned by fitting with the resin lens 2X, and the second lens 9 is positioned by fitting with the spacing ring 4X. Of the components, all components except the first lens 5X and the second lens 9 are positioned within the lens barrel 1X. After each component has been positioned, it is pressed by the pressing member 6X, thereby fixing the components housed within the lens barrel 1X.

[0048] (Deformation of the lens during assembly of lens unit 100X) When a compressive force is applied to the lens unit 100X during assembly, the lens deforms. More specifically, the lens is compressed by pressure in the direction along the optical axis CX. If the distortion caused by this compression is not balanced with the moment acting on the lens, the lens may bend.

[0049] The deflection of the lens is determined by the second moment of area, which depends on the shape of the lens, and the moment acting on the lens. Since the second moment of area depends on the thickness of the lens, the thinner the lens, the greater the deformation due to deflection. When the lens deflects, the flange portion cannot absorb the deformation, and the lens portion deforms.

[0050] It is also conceivable to suppress lens deflection by adjusting the position where the pressing force is applied to both the lens and the lens barrel 1X, thereby canceling out the moment. However, due to manufacturing tolerances of the lens or lens barrel 1X, it may not be possible to properly cancel out the moment, and the lens may deform.

[0051] For example, if the flatness error of the lens or lens barrel (1X) is large due to manufacturing tolerances, the radial position where the pressing force is applied changes, altering the direction and amount of lens deformation.

[0052] In addition to manufacturing tolerances, changes in the amount of deflection due to the pressing force also contribute to the inability to properly cancel out the moment. The pressing force is controlled by torque, but it fluctuates due to variations in tightening torque and errors in the relationship between pressing force and torque. Since the amount of deflection is proportional to the pressing force, variations in the pressing force lead to larger variations in the amount of deflection.

[0053] When attaching the lens unit 100X to an imaging device having an image sensor, it is conceivable to compensate for changes in the performance of the lens unit 100X by adjusting the relative position between the image sensor and the lens unit 100X. However, if the lens deforms due to the above factors, the performance of the lens unit 100X may change without proper compensation, potentially leading to a decrease in the quality of the image captured by the imaging device.

[0054] (Lens deformation due to changes in ambient temperature) When the ambient temperature around the lens unit 100X changes, each component of the lens unit 100X, including the lens barrel 1X, expands or contracts according to its respective coefficient of linear expansion. The compressive force applied to each component also changes according to the differences in the amount of expansion or contraction between the components.

[0055] The amount of lens deflection is proportional to the pressing force. Therefore, variations in the deformation state of the lens unit 100X during assembly cause the amount of deflection to change with changes in the ambient temperature around the lens unit 100X. In other words, the greater the deflection of the lens unit 100X in its assembled state, the greater the deformation, and the smaller the deflection, the smaller the deformation of the lens unit 100X. As a result, the variation in the amount of deflection among multiple lens units 100X increases according to the variation in deformation during assembly.

[0056] Furthermore, if there is a difference in expansion between the lens and the component in contact with the lens, a shear force due to friction will be generated in the radial direction. If the shear force occurs locally, an imbalance in moment will occur, causing the lens to bend. For this reason, even if the deformation is small during the assembly of the lens unit 100X, a large lens deformation that affects the performance of the lens unit 100X may occur due to changes in ambient temperature.

[0057] (Changes in lens deformation over time) Since resin lenses have viscoelastic properties, it is preferable to consider the effects of stress relaxation and creep deformation. Stress relaxation refers to the phenomenon in which stress is relieved over time when stress is applied. Stress relaxation reduces the pressing force applied to the lens unit 100X. Since the amount of lens deflection is approximately proportional to the pressing force, the deformation of the resin lens may change over time depending on the deformation state of the resin lens during the assembly of the lens unit 100X.

[0058] Creep deformation refers to the phenomenon in which deformation changes when a constant force is applied. Depending on the shape of the resin lens during assembly of the lens unit 100X, the stress distribution inside the resin lens differs, and therefore, the amount of deformation of the resin lens may change over time due to creep deformation.

[0059] In addition to the deformations described above, lens units containing resin lenses may also experience significant misalignment of the lens axis. Because the difference in linear expansion coefficients between the lens barrel and the lens is larger in lens units containing resin lenses compared to glass lenses, it is preferable to increase the radial clearance to prevent the lens from becoming press-fitted due to radial expansion when the ambient temperature around the lens unit changes. Therefore, during assembly, the lens axis may shift relative to the lens barrel by the amount of this clearance. Furthermore, changes in the ambient temperature around the lens unit, or changes in the lens unit over time, may cause components to move within the clearance. This movement can increase the radial misalignment of the lens axis compared to the assembly state.

[0060] <Effects of the lens unit 100 according to the first embodiment> The lens unit 100 according to this embodiment includes a resin lens 2 and a glass lens 5 (multiple lenses) arranged along the optical axis C, a lens barrel 1 that includes a fitting portion B and houses the resin lens 2 and the glass lens 5, and a pressing member 6 that presses the resin lens 2 and the glass lens 5 housed in the lens barrel 1. The resin lens 2 includes a fitting portion A that can be fitted into the fitting portion B, and each of the fitting portion A and the fitting portion B includes a tapered shape in which the diameter of the circle centered on the optical axis C differs depending on the position in the direction along the optical axis C.

[0061] The resin lens 2, housed in the lens barrel 1 and positioned by fitting, deforms under pressure from the pressing member 6 during the assembly of the lens unit 100. This deformation of the resin lens 2 fills the gap between the fitting portion A and the fitted portion B, causing them to come into contact. This suppresses further deformation of the resin lens 2, thereby preventing changes in the performance of the lens unit 100 due to the deformation of the resin lens 2. Furthermore, even if the pressing force applied by the pressing member 6 changes, the increase in the amount of deflection of the resin lens 2 is suppressed, thus preventing changes in the performance of the lens unit 100 due to changes in the pressing force.

[0062] By ensuring that the moments are balanced during the assembly of the lens unit 100, even in response to changes in pressing force due to temperature changes, the sensitivity of deformation to pressing force can be reduced. This makes it possible to suppress variations in the amount of change of the resin lens among multiple lens units 100.

[0063] Even when frictional forces are generated at the contact points between components due to differences in expansion between components of the lens unit 100 caused by changes in ambient temperature around the lens unit 100, the balance between the drag force N and the moment is maintained, and the shape change of the resin lens 2 is suppressed. As a result, the amount of deformation of the resin lens 2 predicted by structural analysis during the design of the lens unit 100 can be utilized in the lens design, making it possible to design the lens while taking into account the amount of deformation of the resin lens 2.

[0064] The lens unit 100 has low sensitivity to deformation of the resin lens 2 in response to changes in pressing force. Therefore, even if the pressing force changes due to stress relaxation or creep deformation occurs over time compared to the time of assembly of the lens unit 100, the change in the amount of deformation of the resin lens 2 will be small. In the case of creep deformation, for example, since the variation in the shape change of the resin lens 2 during assembly is small for each of the multiple lens units 100, the variation in the amount of deformation of the resin lens 2 due to creep deformation can be suppressed.

[0065] In the lens unit 100, the mating portion B of the lens barrel 1 and the mating portion A of the resin lens 2 come into contact during assembly, and a radial force is applied at the contact point, thereby suppressing the radial movement of the resin lens 2. As long as the contact between the mating portion B and the mating portion A is maintained, the amount of radial movement of the first resin lens will be suppressed even if temperature changes or changes over time occur. As a result, the lens unit 100 can suppress axial misalignment of the resin lens 2 and suppress eccentricity of the resin lens 2.

[0066] As described above, this embodiment provides a lens unit that can suppress changes from the assembled state.

[0067] The number of lenses is not limited to two, but may be three or more. The number of resin lenses is not limited to one, but may be two or more. The tapered shape of the mating portion A and the mated portion B is not limited to a shape in which the diameter increases as you move in the negative Z-axis direction, but may also be a shape in which the diameter increases as you move in the positive Z-axis direction.

[0068] In this embodiment, the resin lens 2 includes a lens portion 21 and a flange portion 22 formed on the outside of the lens portion 21. The flange portion 22 includes a fitting portion A. With this configuration, when the resin lens 2 deforms, the flange portion 22 can be actively deformed, thereby suppressing deformation of the lens portion 21. As a result, in this embodiment, a lens unit 100 capable of suppressing performance changes can be provided. However, the invention is not limited to this configuration.

[0069] In this embodiment, the resin lens 2 includes a ring-shaped first portion 221 that abuts against the lens barrel 1 (first member), and a ring-shaped second portion 222 that abuts against the spacing ring 4 (second member) on the opposite side of the first portion 221 in the direction along the optical axis C. When the resin lens 2 is viewed from the direction along the optical axis C, the second portion 222 is located between the fitting portion A and the first portion 221. With this configuration, a resistance force N and a pressing force F can be applied to the resin lens 2 at different positions in the radial direction, thereby suppressing the moment acting on the resin lens 2.

[0070] [Second Embodiment] The lens unit according to the second embodiment will be described with reference to Figures 1 and 2. Note that the same reference numerals are used for components identical to those in the first embodiment, and redundant explanations are omitted as appropriate. This also applies to other embodiments described later.

[0071] Figure 4 is a longitudinal cross-sectional view illustrating the configuration of the lens unit 100a according to the first embodiment. Figure 5 is a plan view of the second resin lens 30 in the lens unit 100a of Figure 4. Figure 5 shows the second resin lens 30 viewed from the negative Z-axis direction.

[0072] As shown in Figure 4, the lens unit 100a includes a first resin lens 2a, a second resin lens 30, and a light-shielding member 40. The first resin lens 2a, the second resin lens 30, and the glass lens 5 correspond to a plurality of lenses aligned along the optical axis C. The first resin lens 2a and the second resin lens 30 correspond to two resin lenses and are arranged adjacent to each other.

[0073] The first resin lens 2a has at least a portion of its outer circumference formed in a substantially cylindrical shape. The outer diameter of the substantially cylindrical shape of the first resin lens 2a is smaller than the inner diameter of the lens barrel 1. As a result, the first resin lens 2a can be housed in the lens barrel 1 with a gap between it and the lens barrel 1.

[0074] The first resin lens 2a includes a lens portion 21a and a flange portion 22a. The lens portion 21a has an optical axis C at its center and acts as a lens for light incident on the first resin lens 2a.

[0075] The flange portion 22a is formed on the outside of the lens portion 21a. The flange portion 22a does not act as a lens for light incident on the first resin lens 2a. The flange portion 22a includes the mating portion E.

[0076] The mating portion E includes a tapered shape with different diameters around the optical axis C, depending on its position in the direction along the optical axis C. In this embodiment, the mating portion E includes a substantially conical tapered shape in which the diameter of the circle around the optical axis C increases as it moves toward the negative Z-axis direction.

[0077] The second resin lens 30 has at least a portion of its outer circumference formed in a substantially cylindrical shape. The outer diameter of the substantially cylindrical shape of the second resin lens 30 is smaller than the inner diameter of the lens barrel 1. As a result, the second resin lens 30 can be housed in the lens barrel 1 with a gap between it and the lens barrel 1.

[0078] The second resin lens 30 includes a lens portion 31 and a flange portion 32. The lens portion 31 has an optical axis C at its center and acts as a lens for light incident on the second resin lens 30.

[0079] The flange portion 32 is formed on the outside of the lens portion 31. The flange portion 32 does not act as a lens for light incident on the second resin lens 30. The flange portion 32 includes a fitting portion D, a first portion 321, and a second portion 322.

[0080] The mating portion D is matable with the mated portion E. The diameter of the tapered shape in the mating portion D is slightly smaller than the diameter of the tapered shape in the mated portion E. The mating portion D is formed on the Z-axis positive side of the flange portion 32. The mating portion D includes a tapered shape with a different diameter around the optical axis C depending on its position in the direction along the optical axis C. In this embodiment, the mating portion D includes a substantially conical tapered shape in which the diameter of the circle around the optical axis C increases as it moves toward the Z-axis negative direction.

[0081] The first portion 321 is a ring-shaped portion that abuts against the first resin lens 2a. The first resin lens 2a corresponds to an example of the first member. The first portion 321 is a surface formed on the positive Z-axis side of the flange portion 32 that is approximately perpendicular to the optical axis C. The first portion 321 abuts against the surface of the first resin lens 2a that is approximately perpendicular to the optical axis C in a ring-shaped region.

[0082] The second portion 322 is a ring-shaped portion that abuts against the spacing ring 4 on the opposite side from the first portion 321 in the direction along the optical axis C. The second portion 322 is a surface formed on the negative Z-axis side of the flange portion 32 that is approximately perpendicular to the optical axis C. The surface of the spacing ring 4 that is approximately perpendicular to the optical axis C abuts against the second portion 322 in a ring-shaped region via the light-shielding member 40.

[0083] As shown in Figure 5, when the second resin lens 30 is viewed from a direction along the optical axis C, the second portion 322 is located between the fitting portion D and the first portion 321. In other words, the positional relationship between the fitting portion D, the first portion 321, and the second portion 322 is such that the fitting portion D, the second portion 322, and the first portion 321 are in order of proximity to the optical axis C.

[0084] As shown in Figure 4, the light-shielding member 40 has the function of blocking ambient light and unintended reflected light that enters the lens unit 100a. The light-shielding member 40 is, for example, a sheet-like member with a thickness of several tens of micrometers. There are no particular restrictions on the material of the light-shielding member 40, but resin or metal can be used. Note that the light-shielding member 40 is not an essential component.

[0085] In the lens unit 100 according to the first embodiment described above, a fitted portion B made of metal or the like is fitted to a fitted portion A made of resin, whereas in this embodiment, both the fitted portion D and the fitted portion E are made of resin. Therefore, when the ambient temperature around the lens unit 100a changes, the difference in expansion between the fitted portion D and the fitted portion E becomes smaller. As a result, the pressing force required to maintain the contact between the fitted portion D and the fitted portion E may be small. In addition, since the shear force due to the difference in expansion at the contact point between the fitted portion D and the fitted portion E is also small, the amount of deformation of the first resin lens 2a and the second resin lens 30 due to changes in ambient temperature can be reduced.

[0086] Other effects are the same as in the first embodiment.

[0087] [Third Embodiment] The lens unit according to the third embodiment will be described with reference to Figures 6 and 7. Figure 6 is a longitudinal cross-sectional view illustrating the configuration of the lens unit 100b according to the third embodiment. Figure 7 is a plan view of the resin lens 2b in the lens unit 100b of Figure 6. Figure 7 shows the resin lens 2b viewed from the negative Z-axis direction.

[0088] As shown in Figure 6, the lens unit 100b comprises a lens barrel 1b and a resin lens 2b.

[0089] The lens barrel 1b includes a mating portion Bb and houses the resin lens 2b and the glass lens 5. The material of the lens barrel 1b is metal, for example, aluminum. However, the material of the lens barrel 1b may be resin or the like.

[0090] In this embodiment, the lens barrel 1b is formed in a hollow, substantially cylindrical shape, and houses a resin lens 2b, a light-shielding member 3, a spacing ring 4, and a glass lens 5 inside in that order. The lens barrel 1b includes a small diameter portion 11b and a contact surface 12b.

[0091] The small-diameter portion 11b is a ring-shaped part provided on a part of the inside of the lens barrel 1. The inner diameter of the small-diameter portion 11b is smaller than the outer diameter of either the resin lens 2b or the glass lens 5 housed in the lens barrel 1b. The small-diameter portion 11b includes a fitting portion Bb.

[0092] The mating portion Bb includes a tapered shape with different diameters around the optical axis C, depending on its position in the direction along the optical axis C. In this embodiment, the mating portion Bb includes a substantially conical tapered shape in which the diameter of the circle around the optical axis C increases as it moves toward the positive Z-axis direction.

[0093] The contact surface 12b is a surface formed on the small-diameter portion 11b that is approximately perpendicular to the optical axis C of the lens unit 100b. The contact surface 12b abuts against the resin lens 2b housed in the lens barrel 1b.

[0094] The resin lens 2b has at least a portion of its outer circumference formed in a substantially cylindrical shape. The outer diameter of the substantially cylindrical shape of the resin lens 2b is smaller than the inner diameter of the lens barrel 1b. As a result, the resin lens 2b can be housed in the lens barrel 1b with a gap between it and the lens barrel 1b.

[0095] The resin lens 2b includes a lens portion 21b and a flange portion 22b. The lens portion 21b has the optical axis C at its center and acts as a lens for light incident on the resin lens 2b.

[0096] The flange portion 22b is formed on the outside of the lens portion 21b. The flange portion 22b does not act as a lens for light incident on the resin lens 2b. The flange portion 22b includes a fitting portion Ab, a first portion 221b, and a second portion 222b.

[0097] The mating portion Ab is matable with the mated portion Bb. The diameter of the tapered shape in the mating portion Ab is slightly smaller overall than the diameter of the tapered shape in the mated portion Bb. The mating portion Ab is formed on the face facing the positive Z-axis direction. The mating portion Ab includes a tapered shape with a different diameter around the optical axis C depending on its position along the optical axis C. In this embodiment, the mating portion Ab includes a substantially conical tapered shape in which the diameter of the circle around the optical axis C increases as it moves toward the positive Z-axis direction.

[0098] The first portion 221b is a ring-shaped portion that abuts against the lens barrel 1b. The lens barrel 1b corresponds to an example of the first member. The first portion 221b is a surface formed on the positive Z-axis side of the flange portion 22b that is approximately perpendicular to the optical axis C. The first portion 221b abuts against the surface of the small diameter portion 11 of the lens barrel 1b that is approximately perpendicular to the optical axis C in a ring-shaped region.

[0099] The second portion 222b is a ring-shaped portion that abuts against the spacing ring 4 on the opposite side from the first portion 221b in the direction along the optical axis C. The second portion 222b is a surface formed on the negative Z-axis side of the flange portion 22b that is approximately perpendicular to the optical axis C. The surface of the spacing ring 4 that is approximately perpendicular to the optical axis C abuts against the second portion 222b in a ring-shaped region via the light-shielding member 3.

[0100] As shown in Figure 7, when the resin lens 2b is viewed from a direction along the optical axis C, the second portion 222b is located between the fitting portion Ab and the first portion 221. In other words, the positional relationship between the fitting portion Ab, the first portion 221b, and the second portion 222b is such that, in order of proximity to the optical axis C, it is the first portion 221b, the second portion 222b, and the fitting portion Ab.

[0101] Moments M1a and M2a represent the moments acting on the resin lens 2b. Moment M1a is in the opposite direction to moment M1 in Figure 1, i.e., it is directed from the negative Z-axis direction to the positive Z-axis direction. Moment M2a is in the opposite direction to moment M2 in Figure 1, i.e., it is directed from the negative Z-axis direction to the positive Z-axis direction.

[0102] The same effects and advantages as those of the lens unit 100 according to the first embodiment can be obtained with the lens unit 100b.

[0103] The embodiments described above are presented as examples only and are not intended to limit the scope of the present invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications are possible without departing from the spirit of the invention. Such embodiments and variations thereof are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0104] 1, 1b Lens barrel 11, 11b Small diameter section 12, 12b contact surface 2, 2b resin lens 2a First resin lens 21, 21a, 21b Lens section 22, 22a, 22b Flange section 221, 221b Part 1 222, 222b 2nd part 3, 40 Light-shielding material 4 Interstraining rings 5 Glass lenses 6 Pressing member 30. Second resin lens 31 Lens section 32 Flange section 321 Part 1 322 Part 2 100, 100a, 100b lens units A, Ab, D mating part B, Bb, E Mated part C optical axis F Pressing force M1, M2, M1b, M2b moments N drag force [Prior art documents] [Patent Documents]

[0105] [Patent Document 1] Japanese Patent Publication No. 2020-046562

Claims

1. It includes at least one resin lens and multiple lenses arranged along the optical axis, A lens barrel that includes a fitting portion and houses the plurality of lenses, It has a pressing member that presses the plurality of lenses housed in the lens barrel, The resin lens includes a fitting portion that can be fitted into the fitting portion, Each of the fitting portion and the fitted portion includes a tapered shape in which the diameter of the circle centered on the optical axis differs depending on the position in the direction along the optical axis. The resin lens includes a ring-shaped first portion that abuts against the first member, and a ring-shaped second portion that abuts against the second member on the opposite side of the direction from the first portion in the direction along the optical axis. When the resin lens is viewed from a direction along the optical axis, the second portion is a lens unit located between the fitting portion and the first portion.

2. The resin lens includes a lens portion and a flange portion formed on the outside of the lens portion. The lens unit according to claim 1, wherein the flange portion includes the fitting portion.

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