JP2014170124A - Lens unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens unit which employs a structure with a cemented lens press-fitted into a lens holder and is less susceptible to separation of the cemented lens even under temperature variation.SOLUTION: A lens unit 100 includes a lens 4 (cemented lens) comprising two plastic lenses (first lens 41 and second lens 42), of which only the first lens 41 is press-fitted inside a medium diameter section 52 of a holder 5, by which the lens 4 is held by the holder 5. No less than 50%, in an optical axis direction, of a portion of the first lens 41 inside a press-fitted surface 45 in contact with the holder 5 in a radial direction makes up a virtual tabular portion 46 (portion shown with dashed-dotted lines L46) located at a distance in the optical axis direction from a bonding surface 40 of the lens 4 (cemented lens) in all directions perpendicular to the optical axis.

Description

  The present invention relates to a lens unit in which a cemented lens is held by a cylindrical holder.

  The lens unit may have a structure in which a lens is press-fitted inside a cylindrical holder (see Patent Document 1). In this case, from the viewpoint of preventing the tilt of the lens, the press-fitted portion of the lens into the holder requires a certain dimension or more in the optical axis direction. As a result, as in Patent Document 1, a press-fit portion is provided on the radially outer side with respect to the concave surface of the lens.

  On the other hand, as shown in FIG. 6A, the inventor press-fits a cemented lens (lens 4) in which the first lens 41 and the second lens 42 are cemented with the adhesive 8 into the holder 5, and In configuring the unit 100, the portion of the first lens 41 and the second lens 42 that is located on the bonding surface 40 side on the outer peripheral surface of one lens (for example, the first lens 41) is used as the press-fit portion 45 to the holder 5. We are considering the structure to use. The lens units shown in FIGS. 6A and 6B are reference examples for the present invention and do not have a conventional structure.

FIG. 1 of Japanese Patent Laid-Open No. 10-197772

  However, as shown in FIGS. 6A and 6B, when a portion located on the joint surface 40 side on the outer peripheral surface of the first lens 41 is used as the press-fit portion 45 with respect to the holder 5, as described below, There is a problem that peeling at the joint surface 40 between the first lens 41 and the second lens 42 is likely to occur due to a temperature change.

  That is, in the case of the structure shown in FIGS. 6A and 6B, the portion of the first lens 41 that overlaps the press-fit portion 45 into the holder 5 on the inner side in the radial direction is the first over the entire optical axis direction. The concave surface 41c of one lens 41 enters. Further, when the temperature rises, the press-fit portion 45 of the first lens 41 is restrained by the holder 5, and the first lens 41 and the holder 5 have different thermal expansion coefficients. For this reason, when the temperature rises, the first lens 41 expands in a state where it receives stress in a direction orthogonal to the optical axis L, whereas the second lens 42 expands in a state where the outer peripheral surface is free. To do. As a result, the second lens 42 isotropically expands, but the first lens 41 is distorted so that the central portion protrudes toward the object side L1, and as a result, the concave surface 41c is also distorted in the same direction. For this reason, a difference occurs between the shape change of the concave surface 41c of the first lens 41 and the shape change of the convex surface 42c of the second lens 42 on the joint surface 40 of the first lens 41 and the second lens 42, and FIG. As shown in c), the distance between the concave surface 41c of the first lens 41 and the convex surface 42c of the second lens 42 varies depending on the position (see the distances a1 and b1 in FIG. 7), and peeling easily occurs. Such peeling is not preferable because it causes problems such as clouding, whitening, and destruction of the lens 4.

  Here, the graph shown in FIG. 6C shows the central portion of the concave surface 41c of the first lens 41 and the convex surface of the second lens 42 after the temperature change, as schematically shown by a one-dot chain line in FIG. The difference G between the distance b2 between the central portion 42c and the distance a2 between the outer peripheral portion of the concave surface 41c of the first lens 41 and the outer peripheral portion of the convex surface 42c of the second lens 42 after temperature change is obtained by simulation. It is a graph which shows the result. In such a graph, when the absolute value of the difference G is 0.005 mm or more, the probability that peeling will occur becomes extremely high. Specifically, as shown by a solid line in FIG. 7, a temperature b1 between the central portion of the concave surface 41c of the first lens 41 and the central portion of the convex surface 42c of the second lens 42 before the temperature change occurs (25 ° C.), and the temperature The interval a1 between the outer peripheral portion of the concave surface 41c of the first lens 41 and the outer peripheral portion of the convex surface 42c of the second lens 42 before the change occurs (25 ° C.) is set to be equal. For this reason, the above difference G at 25 ° C. before the temperature change occurs is zero. Therefore, when the absolute value of the difference G increases due to a change in temperature, the interval becomes non-uniform due to a change in temperature. In particular, the adhesive easily peels off at a portion where the interval is widened. It shows that it becomes. As a result of examination, it has been found from experience that the limit value of the absolute value of the difference G is 0.005 mm.

  Although there is a method of simply inserting without adopting press-fitting, in this case, due to backlash caused by tolerance, decentering or the like occurs, and optical performance is impaired.

  In view of the above problems, an object of the present invention is to provide a lens unit in which separation of a cemented lens is difficult even if a temperature change occurs when a structure in which the cemented lens is press-fitted into a lens holder is employed. It is in.

  In order to solve the above-described problem, a lens unit according to the present invention includes a cemented lens in which a concave surface of a first lens and a convex surface of a second lens are cemented with an adhesive, and the first lens and the second lens. A cylindrical holder that holds the cemented lens inside by press-fitting only one lens inside, and the one lens is a plastic lens, and the one lens is connected to the holder. An imaginary plate in which 50% or more of the optical axis direction of the portion that overlaps radially inward with respect to the press-fitted portion is spaced apart from the cemented surface of the cemented lens in the optical axis direction in the entire direction orthogonal to the optical axis direction. It consists of a shape part.

  In the present invention, one lens of the cemented lens is a plastic lens, and only the one lens is press-fitted into the holder, whereby the cemented lens is held by the holder. Further, 50% or more of the optical axis direction of the portion that overlaps the press-fitted portion into the holder on the inner side in the radial direction is separated from the cemented lens joint surface in the optical axis direction over the entire direction orthogonal to the optical axis direction. Consists of virtual plate-like parts. For this reason, when the temperature changes, the outer peripheral surface of one lens is constrained by the holder, so the portion that overlaps the press-fitted portion into the holder on the inside in the radial direction is stress in the direction perpendicular to the optical axis. However, the cemented surface of the cemented lens is covered with less than 50%. For this reason, a joining surface does not deform | transform greatly by a temperature change. Therefore, since the difference in shape change when the concave surface of the first lens and the convex surface of the second lens are deformed is small, the distance between the concave surface of the first lens and the convex surface of the second lens is substantially the same at any position. . Therefore, peeling at the joint surface is unlikely to occur.

  In the present invention, in the one lens, it is preferable that the entire portion in the optical axis direction of the portion overlapping the press-fitted portion on the radially inner side is composed of the plate-shaped portion. According to such a configuration, the effect of preventing peeling at the joint surface is great.

  In the present invention, in the one lens, a portion of 50% or more of the optical axis direction of the portion that overlaps with the press-fitted portion on the radially inner side extends in the direction perpendicular to the optical axis direction. It is preferable that it is the solid part which occupies. According to such a configuration, when a temperature change occurs, even if one lens receives stress in a direction perpendicular to the optical axis from the press-fitted portion to the holder, the solid portion acts as a beam to apply stress. Therefore, the entire lens including the solid portion is unlikely to be greatly deformed such that the central portion is distorted to one side in the optical axis direction with respect to the peripheral portion. For this reason, distortion and deformation of the cemented surface of one lens can be suppressed. Therefore, since the difference in shape change when the concave surface of the first lens and the convex surface of the second lens are deformed is small, the distance between the concave surface of the first lens and the convex surface of the second lens is substantially the same at any position. . Therefore, peeling at the joint surface is unlikely to occur.

  In this case, in the one lens, it is preferable that the entire portion in the optical axis direction of the portion overlapping the press-fitted portion on the radially inner side is the solid portion. According to such a configuration, when a temperature change occurs, even when one lens receives stress in a direction perpendicular to the optical axis from the press-fitted portion to the holder, due to the effect of the beam of the solid portion, Since deformation of the cemented surface of one lens is further suppressed, peeling at the cemented surface is less likely to occur.

  The lens unit according to another aspect of the present invention includes a cemented lens in which the concave surface of the first lens and the convex surface of the second lens are cemented with an adhesive, and one of the first lens and the second lens. A cylindrical holder that holds the cemented lens on the inside by being press-fitted only inside, and the one lens is a plastic lens, and on one surface of the one lens, A groove extending along the press-fit portion is formed in a region sandwiched in the radial direction between the press-fit portion to the holder and the cemented surface of the cemented lens, and 50 in the optical axis direction of the press-fit portion. % Or more of the portion overlaps the groove on the outer side in the radial direction.

  In the present invention, one lens of the cemented lens is a plastic lens, and only the one lens is press-fitted into the holder, whereby the cemented lens is held by the holder. In addition, on one surface of one lens, a groove extending along the press-fitted portion is formed in a region sandwiched in the radial direction between the press-fitted portion to the holder and the cemented surface of the cemented lens in the radial direction. A portion of 50% or more of the press-fitted portion in the optical axis direction overlaps the groove radially outward. For this reason, when the temperature changes, the outer peripheral surface of one lens is constrained by the holder, so the portion that overlaps the press-fitted portion into the holder on the inside in the radial direction is stress in the direction perpendicular to the optical axis. However, the influence of such stress is absorbed by elastic deformation radially outward from the groove. For this reason, since the difference in shape change when the concave surface of the first lens and the convex surface of the second lens are deformed due to the temperature change is small, the distance between the concave surface of the first lens and the convex surface of the second lens is any position. But it is almost equivalent. Therefore, peeling at the joint surface is unlikely to occur.

  In this case, it is preferable that the entire press-fitted portion in the optical axis direction overlaps the groove on the outer side in the radial direction. According to such a configuration, the effect of preventing peeling at the joint surface is great.

  In this invention, it is preferable that the cross section of the bottom part of the said groove | channel has a concave curved surface shape. According to such a configuration, the portion on the outer side in the radial direction from the groove is easily deformed, so that the influence of stress is easily absorbed by the elasticity on the outer side in the radial direction from the groove. In addition, when a portion radially outward from the groove is deformed, in the cross section of the bottom of the groove, deformation stress concentrates on the corner portion formed by the bottom surface portion of the groove and the radially outer portion of the groove, causing elastic fracture. Can be avoided.

  In the present invention, it is possible to adopt a configuration in which the groove is formed on the joint surface side of both surfaces of the one lens.

  In the present invention, it is preferable that the groove is formed deeper in the optical axis direction than a position overlapping the press-fitted portion radially inward. According to such a configuration, the portion on the outer side in the radial direction from the groove is easily deformed, so that the influence of stress is easily absorbed by the elasticity on the outer side in the radial direction from the groove.

  The present invention is effective when applied to the case where both the first lens and the second lens are plastic lenses. In the case of a plastic lens, since the expansion and contraction accompanying the temperature change are large compared to the glass lens, the effect when the present invention is applied is large.

  The present invention is particularly effective when applied to the case where the one lens is the first lens. When the first lens having a concave surface on the cementing surface is used for press-fitting as one lens, the effect of applying the present invention is that the concave portion tends to have a structure that enters the inside in the radial direction with respect to the press-fitted portion. It ’s big.

  In the present invention, on the outer peripheral surface of the one lens, it is preferable that a portion other than the press-fitted portion is located radially inward from the press-fitted portion. According to such a configuration, even when a temperature change occurs, portions other than the press-fitted portion are not easily subjected to stress from the holder.

  In the present invention, the cemented lens may employ a configuration in which the one lens is disposed so as to face the object side.

  In the present invention, it is preferable that a step portion for supporting an outer peripheral end portion of the one lens on the image side is formed on the inner peripheral surface of the holder. According to this configuration, the position of the cemented lens in the optical axis direction and the posture of the cemented lens can be appropriately defined by the stepped portion.

  In the present invention, one lens of the cemented lens is a plastic lens, and only the one lens is press-fitted into the holder, whereby the cemented lens is held by the holder. Further, 50% or more of the optical axis direction of the portion that overlaps the press-fitted portion into the holder on the inner side in the radial direction is separated from the cemented lens joint surface in the optical axis direction over the entire direction orthogonal to the optical axis direction. Consists of virtual plate-like parts. For this reason, when the temperature changes, the outer peripheral surface of one lens is constrained by the holder, so the portion that overlaps the press-fitted portion into the holder on the inside in the radial direction is stress in the direction perpendicular to the optical axis. However, the cemented surface of the cemented lens is covered with less than 50%. For this reason, the joint surface is not greatly deformed by the temperature change. Therefore, since the difference in shape change when the concave surface of the first lens and the convex surface of the second lens are deformed is small, the distance between the concave surface of the first lens and the convex surface of the second lens is substantially the same at any position. . Therefore, peeling at the joint surface is unlikely to occur.

  In another embodiment of the present invention, on one surface of one lens, a region sandwiched in the radial direction between the press-fitted portion into the holder and the cemented surface of the cemented lens in the radial direction extends along the press-fitted portion. An existing groove is formed, and 50% or more of the press-fitted portion in the optical axis direction overlaps the groove on the outer side in the radial direction. For this reason, when the temperature changes, the outer peripheral surface of one lens is constrained by the holder, so the portion that overlaps the press-fitted portion into the holder on the inside in the radial direction is stress in the direction perpendicular to the optical axis. However, the influence of such stress is absorbed by elastic deformation radially outward from the groove. For this reason, since the difference in shape change when the concave surface of the first lens and the convex surface of the second lens are deformed due to the temperature change is small, the distance between the concave surface of the first lens and the convex surface of the second lens is any position. But it is almost equivalent. Therefore, peeling at the joint surface is unlikely to occur.

It is explanatory drawing of the lens unit which concerns on Embodiment 1 of this invention. It is a graph which shows the deformation | transformation of the lens surface accompanying the temperature change of the lens unit which concerns on Embodiment 1 of this invention. It is sectional drawing which expands and shows the structure of the cemented lens periphery of the lens unit which concerns on the structural example 3 of Embodiment 1 of this invention. It is explanatory drawing of the lens unit which concerns on Embodiment 2 of this invention. It is a graph which shows the deformation | transformation of the lens surface accompanying the temperature change of the lens unit which concerns on Embodiment 2 of this invention. It is explanatory drawing of the lens unit which concerns on the reference example of this invention. It is explanatory drawing which shows the deformation | transformation of the lens surface accompanying a temperature change.

  A lens unit to which the present invention is applied will be described with reference to the drawings. In the following description, the same reference numerals are given to the corresponding portions for easy understanding of the correspondence with the configuration described with reference to FIG.

[Embodiment 1]
FIG. 1 is an explanatory diagram of a lens unit according to Embodiment 1 of the present invention. FIGS. 1A, 1B, and 1C are cross-sectional views of the lens unit and an enlarged configuration around a cemented lens. FIG. 5 is a cross-sectional view showing an enlarged view of another configuration around the cemented lens. FIG. 2 is a graph showing the deformation of the lens surface accompanying the temperature change of the lens unit according to the first embodiment of the present invention. FIGS. 2 (a) and 2 (b) are diagrams in the configuration example 1 of the first embodiment. 5 is a graph showing lens surface deformation, and a graph showing lens surface deformation in Configuration Example 2 of Embodiment 1. FIG. The graph shown in FIG. 2 simulates the difference G depending on the position of the distance between the two lens surfaces on the cemented surface of the cemented lens with reference to the temperature of + 25 ° C. as described with reference to FIGS. It is a graph which shows the result calculated | required by.

(Entire configuration of lens unit)
As shown in FIG. 1, the lens unit 100 of this embodiment has a plurality of lenses 1, 2, 3, 4 arranged along the optical axis L. The lenses 1, 2, 3, 4 It is held by a cylindrical holder 5. In this embodiment, the plurality of lenses 1, 2, 3, 4 constitutes a wide-angle lens having an angle of view of 130 to 190 °.

  The holder 5 is made of a metal such as aluminum. Inside the holder 5, there are a small diameter portion 51, a medium diameter portion 52 whose inner diameter is larger than the small diameter portion 51, and a medium diameter from the image side L 2 to the object side L 1. A large-diameter portion 53 having an inner diameter larger than that of the portion 52 is formed in order. Therefore, a step portion 56 facing the object side L1 is formed between the small diameter portion 51 and the medium diameter portion 52, and a step facing the object side L1 is formed between the medium diameter portion 52 and the large diameter portion 53. A portion 57 is formed.

  The holder 5 has a flange portion 58 having a large diameter on the most object side L1, and an annular convex portion 59 is formed from a position from the outer peripheral end of the flange portion 58 toward the object side L1. The holder 5 has a bottom plate portion 54 on the image side L2, and the bottom plate portion 54 has an opening portion 54b for guiding light transmitted through the lenses 1, 2, 3, and 4 to an image sensor (not shown). Is formed.

  In this embodiment, the lens 1 (first group) is made of a glass lens having negative power. Specifically, in the lens 1, the lens surface 1a on the object side L1 is a convex spherical surface, and the lens surface 1b on the image side L2 is a concave spherical surface. The lens 1 is fitted inside the annular convex portion 59 of the holder 5.

  The lens 2 (second group) is made of a plastic lens having negative power. Specifically, in the lens 2, the lens surface 2a on the object side L1 is a convex surface or a concave surface having a small power, and the lens surface 2b on the image side L2 is a concave spherical surface or an aspherical surface. The lens 2 is fitted inside the large diameter portion 53 of the holder 5.

  The lens 3 (third group) is made of a glass lens having a positive power. Specifically, in the lens 3, the lens surface 3a on the object side L1 is a convex spherical surface, and the lens surface 3b on the image side L2 is also a convex spherical surface. In this embodiment, the lens 3 is held by a resin-made ring-shaped lens frame 6, and the lens frame 6 is disposed so as to straddle the medium diameter part 52 and the large diameter part 53 of the holder 5. More specifically, the lens frame 6 includes a small-diameter portion 61 and a large-diameter portion 62 having a larger outer diameter than the small-diameter portion 61 in this order from the image side L2 to the object-side L1. Is fitted inside the inner diameter portion 52 of the holder 5. A receiving portion 63 protruding inside the small diameter portion 61 is formed inside the lens frame 6, and the lens 3 is supported on the image side L <b> 2 by the receiving portion 63. Further, an engaging portion 66 is formed on the inner side of the large diameter portion 62 so as to cover the outer peripheral end portion of the lens surface 3a on the object side L1 of the lens 3 by heat caulking. It is supported on the object side L1.

  The lens 4 (fourth group) is a cemented lens in which the concave surface 41 c of the first lens 41 and the convex surface 42 c of the second lens 42 are bonded by the adhesive 8. The first lens 41 is a plastic lens having negative power, and the second lens 42 is a plastic lens having positive power.

  More specifically, in the first lens 41, the lens surface 41a on the object side L1 is a convex spherical surface, and the lens surface 41b on the image side L2 is a concave spherical surface (concave surface 41c). Here, on the surface on the image side L2 of the first lens 41, the outer peripheral portion of the lens surface 41b (concave surface 41c) is an annular flat surface 41e orthogonal to the optical axis L, and the flat surface 41e and the lens surface 41b. It is directly connected to the (concave surface 41c). On the other hand, on the object side L1 surface of the first lens 41, an annular flat surface 41f orthogonal to the optical axis L is formed on the outer peripheral portion of the lens surface 41a, and the central portion of the lens surface 41a is flat. It is located on the same plane as the surface 41f. For this reason, a concave portion 41g caused by the lens surface 41a is formed on the radially inner side of the flat surface 41f.

  In the second lens 42, the lens surface 42a on the object side L1 is a convex spherical surface (convex surface 42c), and the lens surface 42b on the image side L2 is a convex spherical surface. The lens 4 is held by the holder 5 by being press-fitted into the inner diameter portion 52 of the holder 5 with a configuration described later with reference to FIGS. 1B and 1C.

(Manufacturing method of the lens unit 100)
In manufacturing the lens unit 100 of this embodiment, as will be described below, after the lens 4, the lens 3, the lens 2, and the lens 1 are sequentially disposed inside the holder 5, the lens 1 is pressed by the outer frame 7. The lenses 1 to 4 are fixed inside the holder 5.

  More specifically, first, the lens 4 is press-fitted and fixed inside the intermediate diameter portion 52 of the holder 5. As a result, the lens 4 abuts on the stepped portion 56 and is positioned in the optical axis direction. Next, the lens frame 6 holding the lens 3 is inserted inside the holder 5, and the small-diameter portion 61 of the lens frame 6 is press-fitted and fixed to the medium-diameter portion 52 of the holder 5. As a result, the convex portion 69 formed on the outer peripheral side of the image side L2 surface of the lens frame 6 abuts on the outer peripheral side of the object side L1 surface of the lens 4 and is positioned in the optical axis direction. Next, the lens 2 is press-fitted and fixed inside the large-diameter portion 53 of the holder 5. As a result, the lens 2 comes into contact with the outer peripheral surface of the lens frame 6 on the L1 side and is positioned in the optical axis direction. Next, the lens 1 is inserted inside the holder 5. At that time, a seal member 9 made of an O-ring is disposed between the lens 1 and the flange portion 58 of the holder 5.

  After that, the outer frame 7 is put on the lens 1 from the object side L 1, and the outer frame 7 is fixed to the holder 5. At that time, a female screw is formed on the inner peripheral surface of the body portion 71 of the outer frame 7, while a male screw is formed on the outer peripheral surface of the flange portion 58 of the holder 5, and the outer frame 7 is screwed into the holder 5. Secure with. As a result, the lenses 1 to 4 are fixed inside the holder 5.

(Press-fit structure of lens 4 / Configuration example 1 of Embodiment 1)
As shown in FIG. 1B, when the lens 4 is disposed inside the holder 5, only one of the first lens 41 and the second lens 42 is press-fitted inside the holder 5, The lens 4 is held by the holder 5. In this embodiment, of the first lens 41 and the second lens 42, only the first lens 41 having a large outer diameter is press-fitted inside the middle diameter portion 52 of the holder 5, so that the lens 4 is held in the holder 5. Has been. In this state, the image side L2 surface of the first lens 41 is in contact with the step portion 56 and positioned. Further, there is a gap between the second lens 42 and the small diameter portion 51 of the holder 5. For this reason, since the lens 4 is in contact with the holder 5 only by the first lens 41, the positional accuracy of the lens 4 can be ensured. Further, in the configuration in which the second lens 42 is in contact with the holder 5, stress is applied to the bonding surface 40, and there is a concern about peeling or deformation at the bonding surface 40, but between the second lens 42 and the holder 5. Since there is a gap, stress that causes separation or deformation at the cemented surface 40 is not applied from the second lens 42 to the lens 4. In addition, there is a gap between the second lens 42 and the holder 5. For this reason, no stress in the optical axis direction is applied from the second lens 42 to the lens 4.

  In adopting such a press-fit structure, in the present embodiment, a portion of the outer peripheral surface of the first lens 41 located on the object side L1 (the side opposite to the joint surface 40) is used as the press-fit portion 45 with respect to the holder 5. . Here, on the outer peripheral surface of the first lens 41, a portion other than the press-fit portion 45 is located on the radially inner side from the press-fit portion 45, and a gap is formed between the holder 5 and the holder 5. For this reason, portions other than the press-fit portion 45 are not subjected to stress from the holder 5.

  Further, in this embodiment, the first lens 41 and the holder 5 are prevented from being peeled off at the joint surface 40 when a temperature change occurs due to a stress caused by a difference in thermal expansion coefficient. The following configuration is adopted for the purpose. First, in the first lens 41, 50% or more of the optical axis direction of the portion overlapping the press-fit portion 45 to the holder 5 on the inner side in the radial direction is the lens 4 (junction lens) over the entire direction orthogonal to the optical axis direction. It consists of the virtual plate-shaped part 46 (part shown with the dashed-dotted line L46) spaced apart from the joint surface 40 of the optical axis direction.

  More specifically, in this embodiment, in the first lens 41, the entire optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side extends over the entire direction in the direction perpendicular to the optical axis direction. It consists of a virtual plate-like portion 46 (a portion indicated by a one-dot chain line L46) spaced apart from the cemented surface 40 of the (joined lens) in the optical axis direction. The virtual plate-like portion 46 is a portion where the bonding surface 40 (concave surface 41c) does not enter regardless of whether or not the concave portion 41g caused by the lens surface 41a enters the inside. The portion 46 occupies the entire optical axis direction of the portion overlapping the press-fitting portion 45 into the holder 5 on the radially inner side.

  In this embodiment, in the first lens 41, 50% or more of the portion that overlaps the press-fit portion 45 on the radially inner side in the optical axis direction extends over the entire direction perpendicular to the optical axis direction. A solid portion 47 (a portion surrounded by a two-dot chain line L47) occupied by the meat portion.

  More specifically, in the present embodiment, in the first lens 41, about 60% of the optical axis direction of the portion overlapping the press-fit portion 45 on the inner side in the radial direction is the entire length of the first lens 41 in the direction orthogonal to the optical axis direction. A solid portion 47 (a portion surrounded by a two-dot chain line L47) occupied by the meat portion. The solid portion 47 is a portion into which neither the concave portion 41g caused by the lens surface 41a nor the bonding surface 40 (concave surface 41c) enters. In this embodiment, the solid portion 47 is press-fitted into the holder 5. It occupies 60% of the optical axis direction of the portion overlapping the portion 45 on the inner side in the radial direction.

  In the lens unit 100 configured in this way, as described with reference to FIGS. 6 and 7, the press-fit portion 45 of the first lens 41 is restrained by the holder 5 when the temperature rises. The second lens 42 expands in a state where the outer peripheral surface is free. Even in such a case, in this embodiment, the entire portion in the optical axis direction of the portion overlapping the press-fit portion 45 on the inner side in the radial direction is composed of the plate-like portion 46 separated from the joint surface 40 in the optical axis direction. The influence of expansion in the received state hardly reaches the joint surface 40 (concave surface 41c). In addition, since the solid portion 47 is present, the solid portion 47 becomes a beam even when stress is applied in a direction perpendicular to the optical axis from the press-fit portion 45, and therefore the solid portion 47 is included. There is no deformation in which the lens 41 is greatly distorted in the same direction on both the front and back sides, or a deformation in which the central portion is greatly distorted in one direction with respect to the peripheral portion. For this reason, in the joint surface 40 of the 1st lens 41 and the 2nd lens 42, a difference does not generate | occur | produce easily between the shape change of the concave surface 41c of the 1st lens 41, and the shape change of the convex surface 42c of the 2nd lens 42. Therefore, as shown in FIG. 2A, even if a temperature change occurs, the interval between the concave surface 41c of the first lens 41 and the convex surface 42c of the second lens 42 hardly changes depending on the position. That is, as shown in FIG. 2A, even when a temperature change from + 25 ° C. to −50 ° C. or a temperature change from + 25 ° C. to + 100 ° C. occurs, the central portion of the concave surface 41c of the first lens 41 The absolute value of the difference G between the distance b2 from the central portion of the convex surface 42c of the second lens 42 and the distance a2 between the outer peripheral portion of the concave surface 41c of the first lens 41 and the outer peripheral portion of the convex surface 42c of the second lens 42 is 0. Less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off.

(Press-fit structure of lens 4 / Configuration example 2 of Embodiment 1)
In the above configuration example, the plate-like portion 46 occupies the entire portion in the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side, and the solid portion 47 is the press-fit portion into the holder 5. It is the structure which occupies 60% of the optical axis direction of the part which overlaps with radial direction inner side with respect to 45. FIG. In contrast, in this example, as shown in FIG. 1C, the dimension in the optical axis direction of the press-fit portion 45 is larger than that in the configuration shown in FIG. For this reason, a part of the joint surface 40 enters a portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side. Accordingly, the plate-like portion 46 occupies 80% of the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side. In addition, the solid portion 47 occupies 50% of the optical axis direction of the portion overlapping the press-fitting portion 45 into the holder 5 on the radially inner side.

  In such a configuration, as shown in FIG. 2 (b), the absolute value of the difference G is larger than the result shown in FIG. 2 (a), but the temperature change from + 25 ° C. to −50 ° C. or + 25 ° C. Even when a temperature change occurs from + 100 ° C. to + 100 ° C., the distance b2 between the central portion of the concave surface 41c of the first lens 41 and the central portion of the convex surface 42c of the second lens 42, and the outer peripheral portion of the concave surface 41c of the first lens 41 And the absolute value of the difference G between the gap a2 and the outer peripheral portion of the convex surface 42c of the second lens 42 is less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off.

(Configuration Example 3 of Embodiment 1)
FIG. 3 is an enlarged cross-sectional view showing the configuration around the cemented lens of the lens unit according to Configuration Example 3 of Embodiment 1 of the present invention.

  In the configuration example 1 shown in FIG. 1B, the plate-like portion 46 occupies the entire portion in the optical axis direction of the portion that overlaps the press-fit portion 45 into the holder 5 in the radial direction, and the solid portion 47 In this configuration, 60% of the optical axis direction of the portion overlapping the press-fitting portion 45 into the holder 5 on the radially inner side is occupied. Further, in the configuration example 2 shown in FIG. 1C, the plate-like portion 46 occupies 80% of the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side, and is solid. The portion 47 occupies 50% of the optical axis direction of the portion overlapping the press-fitting portion 45 into the holder 5 on the radially inner side.

  On the other hand, in this example, as shown in FIG. 3, the first lens 41 is separated from the object side L1 surface to the image side L2 as compared with the configuration shown in FIGS. A press-fit portion 45 is provided at the position. For this reason, the concave portion 41g caused by the lens surface 41a does not enter the portion overlapping the press-fit portion 45 to the holder 5 on the radially inner side, and the joining surface 40 does not enter. Accordingly, the plate-like portion 46 occupies the entire portion in the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side. Further, the solid portion 47 occupies the entire portion in the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 on the radially inner side.

  According to this configuration, similarly to the configuration examples 1 and 2, even when a temperature change from + 25 ° C. to −50 ° C. or a temperature change from + 25 ° C. to + 100 ° C. occurs, the center of the concave surface 41c of the first lens 41 is obtained. The difference G between the distance b2 between the portion and the central portion of the convex surface 42c of the second lens 42 and the distance a2 between the outer peripheral portion of the concave surface 41c of the first lens 41 and the outer peripheral portion of the convex surface 42c of the second lens 42 is 0. It becomes less than 005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off. Further, since the solid portion 47 occupies the entire portion in the optical axis direction of the portion overlapping the press-fit portion 45 into the holder 5 in the radial direction, when the temperature change occurs, the joint surface of the first lens 41 It is possible to mitigate the deformation of the lens surface 41a opposite to 40 in a state where it receives stress.

(Another configuration example of the first embodiment)
According to the studies repeatedly conducted by the present inventors, if the plate-like portion 46 occupies 50% or more of the optical axis direction of the portion overlapping the press-fitting portion 45 into the holder 5 on the radially inner side, + 25 ° C. Even when a temperature change from −50 ° C. to −50 ° C. or a temperature change from + 25 ° C. to + 100 ° C. occurs, the distance b 2 between the central portion of the concave surface 41 c of the first lens 41 and the central portion of the convex surface 42 c of the second lens 42. The difference G between the outer peripheral portion of the concave surface 41c of the first lens 41 and the distance a2 between the outer peripheral portion of the convex surface 42c of the second lens 42 is less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off.

  Further, if the solid portion 47 occupies 50% or more of the optical axis direction of the portion overlapping the press-fit portion 45 to the holder 5 on the inner side in the radial direction, the press-fit portion 45 to the holder 5 is not affected. Even when the concave portion 41g caused by the lens surface 41a enters the portion that overlaps on the inside in the radial direction, the deformation of the lens surface 41a under stress can be mitigated.

[Embodiment 2]
FIG. 4 is an enlarged cross-sectional view showing the configuration around the cemented lens of the lens unit according to Embodiment 2 of the present invention. FIG. 5 is a graph showing the deformation of the lens surface accompanying the temperature change of the lens unit according to the second embodiment of the present invention. FIGS. 5 (a) and 5 (b) are diagrams in the configuration example 1 of the second embodiment. 6 is a graph showing lens surface deformation, and a graph showing lens surface deformation in Configuration Example 2 of Embodiment 2. FIG. Since the basic configuration of this embodiment is the same as that of Embodiment 1, common portions are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4A, the lens unit 100 of the present embodiment also has a plurality of lenses 1, 2, 3, 4 arranged along the optical axis L, as in the first embodiment. The lenses 1, 2, 3, and 4 are held by a cylindrical holder 5. In this embodiment, the plurality of lenses 1, 2, 3, 4 constitutes a wide-angle lens having an angle of view of 130 to 190 °. The holder 5 is made of metal such as aluminum.

  Also in the present embodiment, as in the first embodiment, the lens 4 is a cemented lens in which the concave surface 41c of the first lens 41 and the convex surface 42c of the second lens 42 are bonded by the adhesive 8, and the first lens 41 and Both of the second lenses 42 are plastic lenses. Also in this embodiment, as in the first embodiment, only one of the first lens 41 and the second lens 42 is press-fitted inside the holder 5, whereby the lens 4 is held by the holder 5. ing. In this embodiment, of the first lens 41 and the second lens 42, only the first lens 41 having a large outer diameter is press-fitted inside the middle diameter portion 52 of the holder 5, so that the lens 4 is held in the holder 5. Has been. In this state, the image side L2 surface of the first lens 41 is in contact with the stepped portion 56. Further, there is a gap between the second lens 42 and the small diameter portion 51 of the holder 5.

(Configuration example 1 of Embodiment 2)
In adopting such a press-fit structure, in this embodiment, as shown in FIG. 4B, the holder 5 in the radial direction on the image side L2 surface (the surface on the bonding surface 40 side) of the first lens 41. A groove 41p extending in the circumferential direction along the press-fit portion 45 is formed in an arc shape in a region sandwiched between the press-fit portion 45 and the joint surface 40 of the lens 4 in the radial direction. That is, on the image side L2 surface of the first lens 41, a flat surface 41e formed around the lens surface 41b (concave surface 41c) is formed with a groove 41p recessed in the optical axis direction. Here, the cross section of the bottom of the groove 41p has a concave curved surface shape. The groove 41p functions as a reservoir for excess adhesive 8 when the first lens 41 and the second lens 42 are joined with the adhesive 8, and also functions to absorb stress as described below. To do.

  More specifically, a portion of the outer peripheral surface of the first lens 41 that is located on the image side L2 (on the bonding surface 40 side) is a press-fit portion 45 to the holder 5, and portions other than the press-fit portion 45 are , Located radially inward from the press-fit portion 45. Further, on the outer peripheral surface of the first lens 41, a portion other than the press-fit portion 45 is located on the radially inner side with respect to the press-fit portion 45, and there is a gap between the holder 5 and the first lens 41. For this reason, portions other than the press-fit portion 45 are not subjected to stress from the holder 5.

  Here, 50% or more of the press-fit portion 45 in the optical axis direction overlaps the groove 41p on the radially outer side. In this embodiment, the dimension of the press-fit portion 45 in the optical axis direction is smaller than the depth dimension of the groove 41p, and the groove 41p is formed deeper in the optical axis direction than the position overlapping the press-fit portion 45 radially inward. Yes. For this reason, the whole of the press-fit portion 45 in the optical axis direction overlaps the groove 41p on the outer side in the radial direction.

  In the lens unit 100 configured as described above, as described with reference to FIGS. 6 and 7, when the temperature rises, the second lens 42 expands with the outer peripheral surface being free. On the other hand, since the press-fit portion 45 of the first lens 41 is restrained by the holder 5, it tries to expand in a state where it receives a stress in a direction orthogonal to the optical axis. It is absorbed by the elasticity outside in the radial direction from the groove 41p. For this reason, since the difference when the concave surface 41c of the 1st lens 41 and the convex surface 42c of the 2nd lens 42 deform | transform by temperature change is small, the concave surface 41c of the 1st lens 41 and the convex surface 42c of the 2nd lens 42 are small. The interval is substantially the same at any position. Therefore, as shown in FIG. 5A, even when a temperature change from + 25 ° C. to −50 ° C. or a temperature change from + 25 ° C. to + 100 ° C. occurs, the central portion of the concave surface 41c of the first lens 41 is obtained. The absolute value of the difference G between the distance b2 between the central portion of the convex surface 42c of the second lens 42 and the distance a2 between the outer peripheral portion of the concave surface 41c of the first lens 41 and the outer peripheral portion of the convex surface 42c of the second lens 42 is It is less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off. Moreover, the cross section of the bottom part of the groove | channel 41p has a concave curved surface shape. For this reason, since the portion outside the groove 41p in the radial direction is easily deformed, the influence of the stress is easily absorbed by the elasticity outside in the radial direction from the groove 41p. Further, when a portion radially outward from the groove 41p is deformed, deformation stress concentrates on a corner portion formed by a bottom surface portion of the groove 41p and a radially outer portion of the groove 41p in the cross section of the bottom portion of the groove 41p. Elastic breakage can be avoided.

(Press-fit structure of lens 4 / Configuration example 2 of Embodiment 2)
In the configuration example shown in FIG. 4A, the entire press-fit portion 45 in the optical axis direction overlaps the groove 41p on the radially outer side. On the other hand, in this embodiment, as shown in FIG. 4C, about 60% of the press-fit portion 45 in the optical axis direction overlaps the groove 41p on the outer side in the radial direction.

  In such a configuration, as shown in FIG. 5 (b), the absolute value of the difference G is larger than the result shown in FIG. 5 (a), but the temperature change from + 25 ° C. to −50 ° C. or + 25 ° C. Even when a temperature change occurs from + 100 ° C. to + 100 ° C., the distance b2 between the central portion of the concave surface 41c of the first lens 41 and the central portion of the convex surface 42c of the second lens 42, and the outer peripheral portion of the concave surface 41c of the first lens 41 And the absolute value of the difference G between the gap a2 and the outer peripheral portion of the convex surface 42c of the second lens 42 is less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off.

(Another configuration example of the second embodiment)
According to studies repeatedly conducted by the present inventors, if a portion of 50% or more of the press-fit portion 45 in the optical axis direction overlaps the groove 41p on the outer side in the radial direction, the temperature change from + 25 ° C. to −50 ° C. Even when a temperature change from + 25 ° C. to + 100 ° C. occurs, the distance b2 between the central portion of the concave surface 41c of the first lens 41 and the central portion of the convex surface 42c of the second lens 42, and the concave surface 41c of the first lens 41 The absolute value of the difference G between the outer peripheral portion of the second lens 42 and the interval a2 between the outer peripheral portion of the convex surface 42c of the second lens 42 is less than 0.005 mm. Therefore, in the lens unit 100 of this embodiment, even if the temperature changes, the lens 4 (bonded lens) is not easily peeled off.

[Other embodiments]
In the above embodiment, the first lens 41 located on the object side L1 is press-fitted into the holder 5 out of the first lens 41 and the second lens 42 constituting the cemented lens, but the second lens located on the image side L2. 42 may be press-fitted into the holder 5.

  In the above embodiment, the first lens 41 having the concave surface 41c on the cemented surface 40 side out of the first lens 41 and the second lens 42 constituting the cemented lens is press-fitted into the holder 5, but the convex surface on the cemented surface 40 side. The second lens 42 having 42 c may be press-fitted into the holder 5.

  In the above embodiment, the holder 5 is made of metal. However, the present invention may be applied to the case where the resin holder 5 reinforced with glass or carbon is used.

1, 2, 3 ... Lens 4 ... Lens (Bonded Lens)
5 ·· Holder 6 · · Lens frame 8 · · Adhesive 40 · · Joint surface 41 · · First lens 41p · · groove 42 · · second lens 45 · · press-fit portion 46 · · virtual plate-like portion 47 · -Solid part 100-Lens unit L-Optical axis L1-Object side L2-Image side

Claims (14)

A cemented lens in which the concave surface of the first lens and the convex surface of the second lens are cemented with an adhesive;
A cylindrical holder for holding the cemented lens on the inside by only one of the first lens and the second lens being press-fitted on the inside;
Have
The one lens is a plastic lens;
In the one lens, a portion of 50% or more of the optical axis direction of the portion that overlaps with the press-fitted portion into the holder on the radially inner side extends from the cemented surface of the cemented lens over the entire direction orthogonal to the optical axis direction. A lens unit comprising virtual plate-like portions spaced apart in the optical axis direction.   2. The lens unit according to claim 1, wherein in the one lens, the entire portion in the optical axis direction of the portion overlapping the press-fitted portion on the radially inner side is formed of the plate-shaped portion.   In the one lens, the solid part of the one lens occupies 50% or more of the optical axis direction of the part that overlaps the press-fitted part radially inward over the entire direction perpendicular to the optical axis direction. The lens unit according to claim 1, wherein the lens unit is a portion.   4. The lens unit according to claim 3, wherein, in the one lens, the entire portion in the optical axis direction of a portion overlapping with the press-fitted portion on the radially inner side is the solid portion. A cemented lens in which the concave surface of the first lens and the convex surface of the second lens are joined by an adhesive;
A cylindrical holder for holding the cemented lens on the inside by only one of the first lens and the second lens being press-fitted on the inside;
Have
The one lens is a plastic lens;
On one surface of the one lens, a groove extending along the press-fit portion is formed in a region sandwiched in the radial direction between the press-fit portion to the holder and the joint surface of the cemented lens in the radial direction. And
A lens unit, wherein a portion of 50% or more of the press-fitted portion in the optical axis direction overlaps the groove radially outward.   The lens unit according to claim 5, wherein the entire press-fitted portion in the optical axis direction overlaps the groove on the outer side in the radial direction.   The lens unit according to claim 5 or 6, wherein a cross section of a bottom portion of the groove has a concave curved surface shape.   The lens unit according to any one of claims 5 to 7, wherein the groove is formed on the joint surface side of both surfaces of the one lens.   The lens unit according to any one of claims 5 to 8, wherein the groove is formed deeper in the optical axis direction than a position overlapping the press-fitted portion on the radially inner side.   The lens unit according to any one of claims 1 to 9, wherein both the first lens and the second lens are plastic lenses.   The lens unit according to claim 1, wherein the one lens is the first lens.   The lens unit according to any one of claims 1 to 11, wherein a portion other than the press-fitted portion is located radially inward of the outer peripheral surface of the one lens.   The lens unit according to any one of claims 1 to 12, wherein the cemented lens is disposed so that the one lens faces the object side.   The lens according to any one of claims 1 to 13, wherein a step portion that supports an outer peripheral side end portion of the one lens on an image side is formed on an inner peripheral surface of the holder. unit.

Images