JP7646303B2 - Lens units and camera modules - Google Patents

Description

The present invention particularly relates to a lens unit and a camera module that constitute an on-board camera mounted on a vehicle such as an automobile.

In recent years, automobiles have been equipped with on-board cameras to assist with parking and prevent collisions through image recognition, and there are also attempts to apply this to autonomous driving. Camera modules such as on-board cameras generally include a lens unit that has a lens group consisting of multiple lenses arranged along an optical axis, a barrel that houses and holds the lens group, and an aperture member that is placed between at least one of the lenses in the lens group (see, for example, Patent Document 1).

In a lens unit, the lenses that make up the lens group are generally assembled in the internal storage space of the lens barrel so that they are stacked in order from the image side to the object side. In this case, to prevent the lenses from shifting due to vibration or impact, causing degradation of resolution performance or misalignment of the optical axis, these lenses are generally pressed directly into the inner surface of the lens barrel, taking advantage of the inner surface shape of the lens barrel. After the lenses are assembled in this stacked state inside the lens barrel, a cap is attached to the object side end of the lens barrel, or the object side end of the lens barrel is crimped, so that the lens group made up of the laminated lenses is held in place in the optical axis direction inside the lens barrel.

JP 2013-231993 A

In this state where the lens group is held in the lens barrel while being restricted in the optical axis direction, if there is a difference in linear expansion coefficient (thermal expansion coefficient) between the lens barrel and the lens (especially if the linear expansion coefficient of the lens is larger than that of the lens barrel), the lens may receive compressive stress in the optical axis direction from the lens barrel due to thermal expansion of the lens in a high-temperature environment, and the surface shape of the lens may be deformed. For example, as shown in Fig. 7, a laminated lens 120 formed by bonding a lens 116 and a lens 117 is stacked on a lens 118, the lens 116 is pressed into the lens barrel 112, there is a gap between the outer peripheral surface of the lens 117 and the inner peripheral surface of the lens barrel 112, the outer diameter of the lens 117 is larger than the outer diameter of the lens 118 below it, and a portion 117a of the lens 117 extending radially outward beyond the lens 118 does not come into contact with the lens barrel 120 in the optical axis direction and does not come into contact with the lens 118 below it, when the lens group expands in the optical axis direction in a high-temperature environment, In this case, lens 117 is subjected to a downward compressive force F in the optical axis direction from the direction of lens 116 above, and therefore portion 117a of lens 117, which is not supported in the radial direction by lens barrel 112 and extends radially outward beyond lens 118 below, with space S1 downward (in the optical axis direction), may bend (into an aspheric shape) toward the optical axis direction, with corner R of lens 118 corresponding to the abutment edge between lens 117 and lens 118 (the radially outer edge of seating surface P of lens 117 against lens 118 in the figure) as a fulcrum, as shown by the dashed line in the figure, and lens 117 may become permanently deformed into a bow shape.
If large permanent deformation occurs in lens 117 in this way, it may not be possible to obtain the desired resolution performance, the focus may shift, etc., and the optical characteristics may be adversely affected (optical performance may deteriorate). Furthermore, if the lens unit is transferred from this high-temperature state to a low-temperature environment, the outer lens barrel 112 is quenched and compressed before the internal lens group, so that the downward compressive force F in the optical axis direction further increases, the amount of deformation of lens 117 further increases, and the amount of permanent deformation further increases.

In addition, such lens deformation generally occurs in parts of the lens that are not supported by the lens barrel or adjacent lenses, and is more pronounced the thinner the lens is, or between lenses with different hardness, particularly in the example of FIG. 7, where lens 117 is made of resin and lens 118 is made of glass. Even in cases where lenses 116 and 117 are not laminated lenses but are individual lenses and both lenses 116 and 117 are press-fitted into lens barrel 112, if there is a space S1 below radial extension portion 117a of lens 117, lens 117 may be permanently deformed downward, although the amount is smaller than in the case of FIG. 7. The deterioration of optical performance due to such deformation was not a big problem in conventional viewing cameras, but with the increasing number of pixels, it has become a major problem in sensing cameras that can lead to erroneous recognition.

The present invention was made in consideration of the above circumstances, and aims to provide a lens unit and a camera module that can suppress the amount of permanent deformation of one of a pair of lenses stacked vertically due to bending in the optical axis direction with the abutting edge of the pair of lenses as a fulcrum under the action of compressive stress, particularly in a high-temperature environment.

In order to solve the above problems, the present invention provides a lens unit including a cylindrical lens barrel that defines an internal storage space for storing and holding lenses, and a lens group that is incorporated in the internal storage space of the lens barrel and is arranged along an optical axis so that a plurality of lenses are stacked,
the lens group includes a first lens and a second lens that is stacked adjacent to the first lens on one side in the optical axis direction and has a larger diameter than the first lens;
the second lens has an extension portion extending radially outward beyond the first lens,
At least one of the surfaces of the first lens and the second lens, which face each other in the optical axis direction, is provided with a recess to prevent the second lens from contacting the radial outer edge of the first lens.

According to the present invention, a relief portion that prevents the second lens from contacting the radial outer edge (contact edge) of the first lens is provided on at least one of the surfaces of the first lens and the second lens that face each other in the optical axis direction. This prevents the extension portion of the second lens that extends radially outward from the first lens from deforming (into an aspheric shape) in the optical axis direction under the action of compressive stress in a high-temperature environment, with the radial outer edge of the first lens as a fulcrum, i.e., with the corner of the first lens corresponding to the contact edge between the first lens and the second lens as a fulcrum. As a result, the amount of permanent deformation of the second lens can be suppressed.

In the above configuration, the "radial outer edge" of the first lens means the edge (corner) located radially outward on the surface of the first lens facing the second lens in the optical axis direction. In the above configuration, the relief portion may be provided only on the first lens, only on the second lens, or on both the first and second lenses. The relief portion may be formed by a notch, groove, etc. provided on the surface of the first lens or the surface of the second lens facing each other in the optical axis direction, and the surface of the first lens and/or the second lens forming the relief portion may be curved or linear, or a combination of these.

In addition, in the above configuration, the escape portion can be applied to all lens pairs in a lens group having the above-mentioned configuration of the first and second lenses, i.e., a configuration in which one lens (second lens) of a pair of lenses stacked on top of each other has a larger outer diameter than the other lens (first lens) and the lens with the larger outer diameter has an extension portion that extends radially outward more than the other lens, but is particularly effective in the lens pair that constitutes the cemented lens described above in relation to Figure 7. In this case, deformation of the extension of the second lens along the optical axis direction with the radial outer edge of the first lens as a fulcrum is particularly likely to occur when the second lens receives a compressive force in the optical axis direction from another adjacent lens on the side opposite to the side facing the first lens under the action of compressive stress in a high-temperature environment, and when the extension of the second lens is not supported by the lens barrel. Furthermore, the thinner the lens is, and the more likely it is to occur between lenses with different hardness. Therefore, the escape portion can effectively prevent lens deformation along the optical axis direction when the extension of the second lens supports a third lens adjacent to the second lens, when the extension of the second lens is not in contact with the lens barrel in the radial direction, when the first and second lenses are located on the image side of the lens unit, or when the first lens is made of glass and the second lens is made of resin.

Furthermore, according to the above configuration, in a cross section along the optical axis direction of the lens unit, it is preferable that the sum of the radial dimensions of the recesses located on both radial sides is 5% to 10% of the sum of the radial dimensions of the contact portion between the first lens and the second lens. This is because, if the sum of the radial dimensions of the relief portion is less than 5% of the sum of the radial dimensions of the abutment portion of the first lens and the second lens, the surface of the second lens that faces the first lens in the optical axis direction cannot be sufficiently relieved from the radial outer edge of the first lens so that the extended portion of the second lens does not deform in the optical axis direction with the radial outer edge of the first lens as a fulcrum under the action of compressive stress in a high-temperature environment. On the other hand, if the sum of the radial dimensions of the relief portion exceeds 10% of the sum of the radial dimensions of the abutment portion of the first lens and the second lens, the area of the seating surface (abutment surface) of the second lens against the first lens becomes narrow, the support stability of the second lens against the first lens is lacking, and the extended portion of the second lens becomes easily deformed in the optical axis direction under the action of compressive stress in a high-temperature environment. Here, the sum of the radial dimensions of the relief portions is 2Y if the radial dimension of each relief portion located on both radial sides (on both sides of the optical axis) in a cross section of the lens unit along the optical axis direction is Y. On the other hand, the sum of the radial dimensions of the abutment portion of the first lens and the second lens is the radial dimension of the abutment portion when the abutment surfaces of the first lens and the second lens are circular, for example, and the first lens and the second lens are continuously abutting along the radial direction to form one abutment portion in a cross section of the lens unit along the optical axis direction. However, when the abutment surfaces of the first lens and the second lens are annular, for example, and there are a plurality of abutment portions of the first lens and the second lens are dispersed radially (on both sides of the optical axis) in a cross section of the lens unit along the optical axis direction, where the radial dimensions of each abutment portion are X1, X2...Xn, the sum of the radial dimensions of the abutment portion is X1+X2+...Xn. Therefore, in the present invention, (X1+X2+...Xn) x 5/100≦2Y≦(X1+X2+...Xn) x 10/100.

In addition, according to the above configuration, in the cross section along the optical axis direction of the lens unit, the maximum dimension in the optical axis direction of the escape space between the first lens and the second lens formed by the escape portion described above (maximum opening dimension) is preferably 0.5% to 5% of the maximum thickness dimension along the optical axis direction of the second lens. This is because if the maximum dimension in the optical axis direction of the escape space is less than 0.5% of the maximum thickness dimension along the optical axis direction of the second lens, the surface of the second lens facing the first lens in the optical axis direction cannot be sufficiently released from the radial outer edge of the first lens so that the extension portion of the second lens does not deform in the optical axis direction with the radial outer edge of the first lens as a fulcrum under the action of compressive stress in a high-temperature environment, and on the other hand, if the maximum dimension in the optical axis direction of the escape space exceeds 5% of the maximum thickness dimension along the optical axis direction of the second lens, the lens becomes thin and the extension portion of the second lens becomes more likely to deform in the optical axis direction under the action of compressive stress in a high-temperature environment.

In addition, in the above configuration, it is preferable that the ratio D/T of the outer diameter dimension D of the second lens to its maximum thickness dimension T along the optical axis direction is 5 to 7. In a second lens with such a ratio, the extension of the second lens is easily deformed in the optical axis direction under the action of compressive stress in a high-temperature environment, so the presence of the relief portion can effectively contribute to preventing lens deformation.

The present invention also provides a camera module equipped with a lens unit having the above-described configuration. Such a camera module can provide the effects of the lens unit described above.

According to the present invention, a relief portion that prevents the second lens from contacting the radially outer edge of the first lens is provided on at least one of the surfaces of the first lens and the second lens that face each other in the optical axis direction. This makes it possible to prevent the extension portion of the second lens that extends radially outward from the first lens from deforming (into an aspheric shape) in the optical axis direction with the radially outer edge of the first lens as a fulcrum under the action of compressive stress in a high-temperature environment, and as a result, the amount of permanent deformation of the second lens can be suppressed.

1 is a schematic cross-sectional view of a lens unit according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of part A in FIG. FIG. 3 is an enlarged view of part C in FIG. 2 . 2 is a schematic cross-sectional view of a camera module having the lens unit of FIG. 1. FIG. 2 is an enlarged cross-sectional view of part B in FIG. FIG. 6 is an enlarged view of part D in FIG. 5 . FIG. 1 is an enlarged cross-sectional view of a main portion of an example of a conventional lens unit having a lens group inside a lens barrel, the lens group being made up of a plurality of lenses arranged along an optical axis so as to be stacked.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The lens unit of the present embodiment described below is particularly intended for a camera module such as an in-vehicle camera, and is fixedly installed on the outer surface of a vehicle, with wiring drawn into the vehicle and connected to a display or other devices. In addition, hatching is omitted for the lenses in Figures 1 to 7.

1 shows a lens unit 11 according to an embodiment of the present invention. As shown in the figure, the lens unit 11 of this embodiment includes a cylindrical lens barrel 12 made of metal, a plurality of lenses arranged in the stepped inner storage space S of the lens barrel 12, for example, six lenses consisting of lens 13, lens 14, lens 15, lens 16, lens 17, and lens 18 from the object side, and an aperture member 22. In this embodiment, the aperture member 22 is interposed between the third lens 15 and the fourth lens 16 from the object side, and is an "aperture diaphragm" that limits the amount of transmitted light and determines the F-number, which is an index of brightness, or a "light blocking diaphragm" that blocks light rays that cause ghosts and light rays that cause aberrations. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a board having an image sensor (not shown), and an installation member (not shown) for installing the board on a vehicle such as an automobile.

The lenses 13, 14, 15, 16, 17, and 18 are stacked and arranged with their optical axes aligned in the inner storage space S of the lens barrel 12, and the lenses 13, 14, 15, 16, 17, and 18 are arranged along one optical axis O to form a group of lenses L used for imaging, all or part of which is directly pressed into the inner surface of the lens barrel 12 using the inner surface shape of the lens barrel 12. In this case, the lens 13 located closest to the object and the lens 18 located closest to the image are made of glass, and the other lenses 14, 15, 16, and 17 are made of resin, but this is not limited to this, and the number of lenses, the materials of the lenses and the lens barrel, etc. can be set arbitrarily depending on the application, etc. In this embodiment, the fourth and fifth lenses 16 and 17 from the object side located on the image side are cemented lenses (cemented lenses) 20 that are fitted together. In this case, the lenses 16 and 17 constituting the cemented lens 20 are positioned by fitting the convex portion 17a on the surface facing the object side of the lens 17 positioned on the image side into the concave portion 16a on the surface facing the image side of the lens 16 positioned on the object side, and are fixed by adhesive or the like. The object side lens 16 constituting the cemented lens 20 is press-fitted into the lens barrel 12, while the outer peripheral surface of the image side lens 17 does not contact the lens barrel 12 and has a gap between it and the lens barrel 12. The lenses 16 and 17 constituting the cemented lens 20 are smaller (thinner) in thickness along the optical axis direction than the other lenses 13, 14, and 15 positioned closer to the object side than these, and are also thinner than the lens 18 positioned closest to the image side. The surfaces of the lenses 13, 14, 15, 16, 17, and 18 constituting the lens group L are provided with anti-reflection films, hydrophilic films, water-repellent films, etc. as necessary.

In this embodiment, an O-ring 26 is inserted between the lens 13 located closest to the object side and the lens barrel 12 as a seal member to prevent water and dust from entering the lens group L inside the lens barrel 12. In this case, a stepped reduced diameter portion 13b with a smaller diameter at the image side portion of the lens 13 is provided on the outer circumferential surface 13a of the lens 13, and an O-ring 26 is attached to this reduced diameter portion 13b, and the O-ring 26 is compressed in the radial direction between the outer circumferential surface 13a of the first lens 13 and the inner circumferential surface 12a of the lens barrel 12, thereby sealing the object side end of the lens barrel 12. Note that the seal member inserted between the first lens 13 and the lens barrel 12 is not limited to an O-ring, and may be any shape as long as it is an annular body that can seal between the first lens 13 and the lens barrel 12.

In addition, when the lens group L is assembled and housed in the inner housing space S of the lens barrel 12, the crimping portion 23 at the object side end (the upper end in FIG. 1) is thermally crimped radially inward, thereby fixing the first lens 13, which is located closest to the object side of the lens group L, to the object side end of the lens barrel 12 in the optical axis direction by this crimping portion 23 (in FIG. 1, the crimping portion 23 has not yet been crimped).

In addition, an inner flange portion 24 is provided at the image side end (lower end in FIG. 1) of the lens barrel 12, with an opening having a smaller diameter than the lens 18 located closest to the image side. The inner flange portion 24 and the crimped portion 23 hold and fix the multiple lenses 13, 14, 15, 16, 17, and 18 that make up the lens group L within the lens barrel 12, and the aperture member 22 in the optical axis direction.

In addition, the lens unit 11 of the present embodiment having the above-mentioned configuration is provided with a relief portion that prevents one of the lens pairs stacked vertically to form the lens group L from deforming (into an aspheric shape) in the optical axis direction with the abutting edge (radial outer edge) of the lens pair as a fulcrum under the action of compressive stress, particularly in a high-temperature environment. In the present embodiment, such a relief portion is provided, as an example, between a pair of lenses 17, 18 that are likely to undergo the above-mentioned deformation along the optical axis direction. The first lens 18 constituting one of the lens pairs is a glass lens positioned closest to the image side in the lens unit 11 as described above, and the second lens 17 constituting the other of the lens pair is a resin lens constituting the image side lens of the cemented lens (cemented lens) 20, and is stacked adjacent to the first lens 18 on its object side and set to a diameter larger than that of the first lens 18. Therefore, this large-diameter second lens 17 has an extension portion 17d that extends radially outward from the small-diameter first lens 18. The extension 17d supports the object-side lens 16 (the third lens adjacent to the second lens 17 on the object side) that constitutes the composite lens 20. In this embodiment, the extension 17d is not supported by contact with the lens barrel 12 in the optical axis direction, nor is it supported by contact with the inner surface of the lens barrel 12 in the radial direction. However, in other modified examples, the extension 17d may be in contact with the lens barrel 12 in the radial direction.

The first lens 18 on the image side constituting the lens pair 17, 18 with the aforementioned clearance is a biconvex lens having convex surfaces on the object side and the image side, while the second lens 17 on the object side stacked on the first lens 18 has a concave surface on its image side, and the convex portion 18a forming the convex surface on the object side of the first lens 18 fits into the concave portion 17b forming the concave surface, forming a lens stacking form. The first and second lenses 18, 17 abut against each other at the flange portions on both radial sides of these concave and convex portions 17b, 18a to form an annular abutment surface (seating surface) P, and therefore, in the cross section along the optical axis direction of the lens unit 11 shown in FIG. 1, the abutment portions P1, P1 of the first and second lenses 18, 17 are present on both sides of the optical axis O so as to extend in the radial direction.

As can be seen from the above, the second lens 17 made of resin, which is located on the image side of the lens unit 11 (and therefore the lower side of the lens stack structure) and constitutes one of the lens pair, is made of a softer material than the first lens 18 made of glass which constitutes the other of the lens pair, is thinner than the other lenses 13, 14, 15, 18, and supports the object-side lenses 13, 14, 5, 16, including their extensions 17d. Therefore, in the case where this second lens 17 does not have the above-mentioned relief portion, when it receives a compressive force in the optical axis direction from another lens located on the object side under the action of compressive stress in a high-temperature environment, as in the conventional technology described above, its extension portion 17d, which is not supported by the lens barrel 12 in the optical axis direction and radial direction, becomes likely to deform (into an aspheric shape) in the optical axis direction, with the radial outer edge R of the first lens 18 (the edge (corner) located at the outermost radial position on the surface 18b of the first lens 18 that faces the second lens 17 in the optical axis direction, or the edge (corner) located on the object side of the outer peripheral side surface 18c of the first lens 18 facing in the radial direction) as a fulcrum. However, in this embodiment, as clearly shown in Figures 2 and 3, at least one of the surfaces 18b and 17c of the first lens 18 and the second lens 17, which face each other in the optical axis direction, has a clearance 50 provided on the surface 17c of the second lens 17 to prevent the second lens 17 from contacting the radial outer edge R of the first lens 18 (the image-side surface 17c of the second lens 17 facing the optical axis direction from contacting the radial outer edge R of the object side of the first lens 18). This can suppress the occurrence of the phenomenon of deformation of the second lens 17 in the optical axis direction with the radial outer edge R of the object side of the first lens 18 as a fulcrum, and can suppress the amount of permanent deformation. The clearance 50 will be described in detail below.

In this embodiment, the relief portion 50 is provided only on the image side surface 17c of the second lens 17 as described above, but it may be provided only on the object side surface 18b of the first lens 18, or on both the object side surface 18b of the first lens 18 and the image side surface 17c of the second lens 17. The relief portion 50 may be formed by forming the image side surface 17c of the second lens 17 in a shape that does not contact the radial outer edge R of the object side of the first lens 18, or by forming the surface 18b and the side surface 18c in a gentle shape so that the radial outer edge R is not formed on the object side surface 18b of the first lens 18. Alternatively, it may be formed by forming both the object side surface 18b of the first lens 18 and the image side surface 17c of the second lens 17 in the above-mentioned shape. In this case, the relief portion 50 may be formed by a notch, groove, or the like provided on the object-side surface 18b of the first lens 18 or the image-side surface 17c of the second lens 17 facing the optical axis direction, and such lens surfaces can be curved, linear, or a combination of these to define a relief space S2 separating the object-side surface 18b of the first lens 18 and the image-side surface 17c of the second lens 17. In particular, in the present embodiment shown in FIG. 3 in which the relief portion 50 is formed by a notch portion 17ca provided only on the image-side surface 17c of the second lens 17, the notch portion 17ca is curved, and a portion 18ba of the object-side surface 18b of the first lens 18 that defines the relief space S2 together with the relief portion 50 (notch portion 17ca) is linear. Therefore, on the radially outer side, the escape space S2 extends so that its opening widens toward the radially outer edge R on the object side of the first lens 18, and on the radially inner side, it tapers so that the cutout portion 17ca of the image side surface 17c of the second lens 17 and the portion 18ba of the object side surface 18b of the first lens 18 join together.

In addition, in this embodiment, in the cross section along the optical axis direction of the lens unit 11 shown in Figures 1 to 3, the sum 2Y of the radial dimensions Y (see Figure 3) of the relief portions 50 located on both radial sides is set to 5% to 10% of the sum 2X of the radial dimensions X (see Figure 2) of the abutment parts P1, P1 of the first lens 18 and the second lens 17. Here, if the sum 2Y of the radial dimensions Y of the relief portions 50 is less than 5% of the sum 2X of the radial dimensions X of the abutment parts P1, P1 of the first lens 18 and the second lens 17, the image side surface 17c of the second lens 17 facing the optical axis direction is sufficiently relieved from the radial outer edge R of the first lens 18 so that the extension part 17d of the second lens 17 does not deform in the optical axis direction with the radial outer edge R of the first lens 18 as a fulcrum under the action of compressive stress in a high-temperature environment. On the other hand, if the sum 2Y of the radial dimensions Y of the clearance portion 50 exceeds 10% of the sum 2X of the radial dimensions X of the contact portions P1, P1 of the first lens 18 and the second lens 17, the area of the seating surface (contact surface) P of the second lens 17 relative to the first lens 18 becomes narrow, the support stability of the second lens 12 relative to the first lens 18 is lacking, and the extension portion 17d of the second lens 17 becomes susceptible to deformation in the optical axis direction under the action of compressive stress in a high-temperature environment.

In addition, in this embodiment, in a cross section along the optical axis direction of the lens unit 11 shown in Figures 1 to 3, the maximum dimension H in the optical axis direction of the escape space S2 between the first lens 18 and the second lens 17 formed by the escape portion 50 (in this embodiment in which the space expands radially outward, the optical axis direction dimension of the radially outer opening end of the escape space S2; see Figure 3) is set to be 0.5% or more and 5% or less of the maximum thickness dimension T along the optical axis direction of the second lens 17 (see Figure 1). Here, if the maximum dimension H of the escape space S2 in the optical axis direction is less than 0.5% of the maximum thickness dimension T along the optical axis direction of the second lens 17, the image side surface 17c of the second lens 17 facing the optical axis direction cannot be sufficiently released from the radial outer edge R of the first lens 18 so that the extension portion 17d of the second lens 17 does not deform in the optical axis direction with the radial outer edge R of the first lens 18 as a fulcrum under the action of compressive stress in a high-temperature environment. On the other hand, if the maximum dimension H of the escape space S2 in the optical axis direction exceeds 5% of the maximum thickness dimension T of the second lens 17 along the optical axis direction, in this embodiment in which the escape portion 50 is provided on the second lens 17 side, the second lens 17 becomes thinner, and the extension portion 17d of the second lens 17 becomes more likely to deform in the optical axis direction under the action of compressive stress in a high-temperature environment.
In addition, the maximum thickness dimension T of the second lens 17 along the optical axis direction means the dimension in the optical axis direction at the radial location where the thickness is greatest when the thickness of the second lens 17 varies along the radial direction. In this embodiment, the second lens 17 has a ratio D/T of its outer diameter dimension D (see FIG. 1) to its maximum thickness dimension T along the optical axis direction of 5 to 7.

Figure 4 is a schematic cross-sectional view of a camera module 300 of this embodiment having a lens unit 11 configured as described above. As shown in the figure, this camera module 300 is configured to include the lens unit 11 of Figure 1 to which a filter 99 is attached. The filter 99 is fixed to the lens barrel 24 by adhesive or the like. For example, an acrylic adhesive or the like is used as the adhesive.

The camera module 300 includes an upper case (camera case) 301, which is an exterior component, and a mount (base) 302 that holds the lens unit 11. The camera module 300 also includes a sealing member 303 and a package sensor (imaging element) 304.

The upper case 301 is a member that engages with the flange portion 25 that is provided in a brim-like shape on the outer circumferential surface 12b of the lens barrel 12, and that exposes the object side end of the lens unit 11 and covers the other parts. The mount 302 is disposed inside the upper case 301, and has a female thread 302a that screws into the male thread 11a of the lens unit 11. The seal member 303 is a member that is interposed between the inner surface of the upper case 301 and the outer circumferential surface 12b of the lens barrel 12 of the lens unit 11, and is a member that maintains airtightness inside the upper case 301.

The package sensor 304 is disposed inside the mount 302, and is positioned to receive the image of the object formed by the lens unit 11. The package sensor 304 also includes a CCD, CMOS, or the like, and converts the light that is collected and reaches the package sensor 304 through the lens unit 11 into an electrical signal. The electrical signal is then converted into analog data or digital data, which is a component of the image data captured by the camera.

As described above, according to this embodiment, the surface 17c of the second lens 17 is provided with a clearance 50 that prevents the image-side surface 17c of the second lens 17 facing the optical axis direction from contacting the radially outer edge R of the object side of the first lens 18. Therefore, the extension 17d of the second lens 17, which extends radially outward from the first lens 18 without being supported by the lens barrel 12 in the optical axis direction, can be prevented from deforming (into an aspheric shape) in the optical axis direction with the radially outer edge R of the first lens 18 as a fulcrum under the action of compressive stress in a high-temperature environment. As a result, the amount of permanent deformation of the second lens 17 can be suppressed.

The present invention is not limited to the above-described embodiment, and can be modified in various ways without departing from the gist of the present invention. For example, the shapes of the lens, lens barrel, and escape portion are not limited to the above-described embodiment. In addition, the escape portion of the present invention can be applied to all lens pairs of the lens group having the above-described configuration of the first and second lenses, that is, a configuration in which one lens (second lens) of a pair of lenses stacked on top of each other has a larger outer diameter than the other lens (first lens) and the lens with the larger outer diameter has an extension portion that extends radially outward more than the other lens. Furthermore, even if the lenses that make up a lens pair have approximately the same outer diameter, if there is a gap between these lenses on the radial outside of the lens pair and one lens has an extension portion that extends radially while being separated from the other lens and not supported by the lens barrel, there is a risk that such an extension portion will deform in the optical axis direction with the radial outer edge, which is the abutting edge of the lens pair, as a fulcrum under the action of compressive stress in a high-temperature environment, therefore, a relief portion as described above can be provided for such lens pairs as well. An example of such a lens pair is the lenses 16 and 17 that constitute the cemented lens 20. As shown in FIG. 5, a gap S3 exists between the lenses 16 and 17 on the radial outside of the lens pair 16 and 17, and the object-side lens 16 has an extension portion 16b that extends radially without being supported by the lens barrel 12 while being separated from the image-side lens 17. In order to prevent this extension portion 16b from deforming in the optical axis direction with the radial outer edge R, which is the abutting edge of the lens pair 16 and 17, as shown in FIG. 6, a relief portion 50 as described above can be provided on the surface 16c of the lens 16 that faces the lens 17. In addition, part or all of the above-mentioned embodiments may be combined within the scope of the present invention, or part of the configuration may be omitted from one of the above-mentioned embodiments.

REFERENCE SIGNS LIST 11 lens unit 12 lens barrel 13, 14, 15, 16 lens 17 second lens 17c surface 17d extension 18 first lens 50 clearance 300 camera module O optical axis R radial outer edge S inner storage space

Claims (7)

A lens unit comprising: a cylindrical lens barrel that defines an inner storage space for storing and holding a lens; and a lens group that is incorporated in the inner storage space of the lens barrel and is arranged along an optical axis so that a plurality of lenses are stacked,
the lens group includes a first lens and a second lens that is stacked adjacent to the object side of the first lens and has a larger diameter than the first lens;
the second lens has an extension portion extending radially outward beyond the first lens,
a relief portion is provided on a surface of the second lens facing the first lens in the optical axis direction to prevent contact with a radially outer edge located at the outermost position in the radial direction on the surface of the first lens facing the second lens in the optical axis direction, and the relief portion is formed so as to move away from the radially outer edge in the optical axis direction from a state in which the relief portion is in contact with a portion of the surface of the first lens that forms the radially outer edge in the optical axis direction;
A lens unit characterized in that the extension portion of the second lens protrudes radially outward from the radial outer edge of the first lens without being supported by and in contact with the lens barrel in the optical axis direction and radial direction, when the lens barrel is not interposed between the image side end face of the second lens and an extension line of the surface of the first lens that forms the radial outer edge. The lens unit according to claim 1, characterized in that the extension of the second lens supports a third lens that constitutes the lens group and is adjacent to the second lens. 3. The lens unit according to claim 1, wherein the first lens is made of glass, and the second lens is made of resin. 4. The lens unit according to claim 1, wherein, in a cross section along the optical axis direction of the lens unit, a sum of radial dimensions of the recesses located on both radial sides is 5% to 10% of a sum of radial dimensions of a contact portion between the first lens and the second lens. 5. The lens unit according to claim 1, wherein in a cross section along the optical axis direction of the lens unit, a maximum dimension in the optical axis direction of the relief space between the first lens and the second lens formed by the relief portion is 0.5% or more and 5% or less of a maximum thickness dimension in the optical axis direction of the second lens. 6. The lens unit according to claim 1, wherein the second lens has a ratio D/T of an outer diameter dimension D to a maximum thickness dimension T along the optical axis direction of 5 to 7 . 7. A camera module comprising the lens unit according to claim 1 , and an image sensor disposed at a position where it receives an image formed by the lens unit.

Images