JP7586664B2 - Lens barrel, lens unit and camera module - Google Patents

Description

The present invention particularly relates to a lens barrel, 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 includes a lens group consisting of multiple lenses arranged along an optical axis, a lens 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).

When the lens barrel that constitutes the lens unit is made of resin, the lens barrel is generally molded as a single unit by pouring molten resin material into a metal mold. As shown in FIG. 5, the integrated lens barrel 112 of such a lens unit 100 has a lens group L consisting of multiple lenses L1 to L5 (five lenses in FIG. 5 as an example) assembled and housed in its internal housing space S, and the crimping portion 123 at the object side end (upper end in FIG. 5) is thermally crimped radially inward to fix the lens L1, which is located closest to the object side of the lens group L, to the object side end of the lens barrel 112 by this crimping portion 123 (the hatching of the lenses is omitted in FIG. 5).

In this case, the lenses L1, L2, L3, L4, and L5 that make up the lens group L are assembled into the inner storage space S of the lens barrel 123 by utilizing their inner surface shape so that they are stacked in order from the image side (lower side in FIG. 5) to the object side (upper side in FIG. 5).

JP 2013-231993 A

As can be seen from Fig. 5 and Fig. 6, the crimped portion 123 tapers toward the object side and has a cylindrical shape before crimping, and its entire circumference is thermally crimped radially inward at once and crushed. However, after thermal crimping, if the lens barrel 112 including the crimped portion 123 expands and contracts radially due to changes in the environmental temperature, cracks may occur in the crimped portion due to its thin tapered shape. Such cracks reduce the crimping holding force of the crimped portion 123 for the lens L1, which may make it impossible for the crimped portion 123 to fix the lens L1 with the desired crimping strength, and may also cause stray light and other problems that may adversely affect optical performance.

The present invention was made in consideration of the above circumstances, and aims to provide a lens barrel, lens unit, and camera module that can prevent the occurrence of cracks in conventional crimped parts due to changes in environmental temperature.

In order to achieve the above object, the present invention provides a lens barrel which is molded into a substantially cylindrical shape by pouring molten resin into a mold through two or more gates spaced apart from each other in a circumferential direction, and has an internal storage space into which a lens group is incorporated, the lens barrel having a crimping portion at an object side end portion for fixing a lens located closest to the object side of the lens group incorporated in the internal storage space by being crimped radially inward,
The object-side end of the lens barrel is characterized in that a notch is provided at approximately the middle of the circumferential angular range between adjacent portions of the lens barrel that correspond to the position of the gate, and extends from the object-side end to the image side beyond the crimped portion.

In order to solve the above-mentioned problems, the present invention provides a lens unit including a lens group including a plurality of lenses arranged along an optical axis, and a lens barrel having an internal storage space for incorporating the lens group,
the lens barrel is molded into a substantially cylindrical shape by pouring molten resin into a mold through two or more gates that are spaced apart from each other in a circumferential direction, and has a crimping portion at an object-side end for fixing a lens located closest to the object side among the lens group that is incorporated into the inner accommodation space by being crimped radially inward,
The object-side end of the lens barrel is characterized in that a notch is provided at approximately the middle of the circumferential angular range between adjacent portions of the lens barrel that correspond to the position of the gate, and extends from the object-side end to the image side beyond the crimped portion.

The inventors have found that cracks tend to occur at specific positions in the thin tapered crimped portion, and after extensive research into the reasons why cracks tend to occur at those positions, have found that the welds where molten resin join in the mold are deeply involved in the cracks. That is, the inventors have noticed that when molten resin 200 is poured into a mold (not shown) from two or more (four in FIG. 6) gates G (FIG. 6 does not show the gates G themselves, but shows four parts of the lens barrel 112 corresponding to the positions of the gates G) that are spaced apart from each other in the circumferential direction to mold the lens barrel 112 into a roughly cylindrical shape, as shown in FIG. 6, a weld W, which is a weak part with a weld line due to poor adhesion, is formed at the part where the molten resin flowing out from between the adjacent gates G joins. The inventors concluded that these welds W cause a decrease in strength and toughness due to stress concentration, and that when the lens barrel 112 including the crimped portion 123 expands and contracts in the radial direction due to changes in environmental temperature, the thin crimped portion 123 receives stress f as shown by the arrow in Figure 6(a) at the position of the welds W, resulting in cracks. Based on this, the inventors arrived at the present invention of providing a notch in the object side end of the lens barrel at a position where a weld can occur, that is, approximately in the middle of the circumferential angular range between adjacent parts of the lens barrel that correspond to the gate positions.

In this way, if the weak weld portion can be eliminated by the cutout, the occurrence of cracks can be prevented, and problems associated with cracks, such as reducing the crimping force of the crimping portion, which makes it impossible to fix the lens with the desired crimping strength, and problems such as the occurrence of stray light and adverse effects on optical performance, can be avoided. In this case, the cutout is intended to prevent the occurrence of cracks when stress occurs by eliminating the weak part at the object side end of the lens barrel by negating the presence of the weld portion, so it is important that it extends long enough to cover the weld formation area from the object side end to the image side, at least beyond the thin crimping portion 123.

In the above configuration, the notches may be provided by machining after the lens barrel is molded, or may be formed simultaneously with the lens barrel being molded using pins (nested parts) that are inserted and removed within the mold. In the latter case, the pins act as walls to block the flow of resin, thereby suppressing the formation of welds in advance. In addition, the number of gates for the flow of molten resin into the mold is not limited, and can be any number, such as two-point gates, three-point gates, or four-point gates, as long as there are multiple gates, and the number of notches should correspond to the number of gates.

In the above configuration of the present invention, the notches are preferably provided in correspondence with the positions of the welds where the molten resin flowing in from each gate joins inside the mold. This allows the notches to reliably eliminate weak welds and reliably prevent the occurrence of cracks. When providing the notches in correspondence with the positions of the welds, it is preferable to identify the positions of the welds from the results of a simulation using, for example, resin flow simulation software.

In addition, in the above-mentioned configuration of the present invention, when the lens located closest to the object side in the lens group has a front surface facing the object side, a back surface facing the image side, and an outer peripheral side surface extending approximately parallel to the optical axis so as to connect the front surface and the back surface, it is preferable that the notch extends along the outer peripheral side surface of the lens beyond the crimped portion. This makes it possible to ensure a large area for forming the notch, and significantly reduces the possibility of cracks occurring.

In addition, in the above-mentioned configuration of the present invention, it is preferable that the notch is filled with adhesive. This makes it possible to compensate for the crimping force of the crimped portion that may be reduced by the formation of the notch, and to ensure the desired level of lens fixing force at the crimped portion.

In addition, in the above-mentioned configuration of the present invention, it is preferable that a light-shielding means is further provided for blocking the incidence of light on the exposed portion of the lens exposed to the outside through the cutout. In this way, the light-shielding means can cover the light-shielding defects caused by the cutout. In other words, the light-shielding means can block stray light that attempts to enter the lens from the side through the cutout, thereby preventing the occurrence of ghosts and the like. In this case, the light-shielding means may be formed of ink that is applied to the exposed portion of the lens, or may be formed of a light-shielding adhesive that is filled into the cutout. For example, a light-absorbing resin can be used as the light-shielding adhesive. The light-absorbing resin is a resin that has the property of being able to absorb light, and for example, an ultraviolet-curing resin, a thermosetting resin, and the like are suitable. In particular, an example of an ultraviolet-curing resin is Chemiseal U-2077 provided by Chemitech Co., Ltd.

The present invention also provides a camera module that includes the lens barrel and lens unit described above. A camera module configured in this way can also achieve the effects of the lens barrel and lens unit described above.

According to the present invention, a notch is provided at the object side end of the lens barrel, located approximately in the middle of the circumferential angular range between adjacent parts of the lens barrel that correspond to the gate positions, and extends from the object side end to the image side beyond the crimped portion. This makes it possible to eliminate the weld portion, which is a weak part, and to prevent the occurrence of cracks.

1 is a schematic cross-sectional view of a lens unit having a lens barrel according to an embodiment of the present invention. 2A is a plan view of the lens unit of FIG. 1 as viewed from the object side, and FIG. 2B is a perspective view of the lens unit of FIG. 1 . 2A is a schematic plan view of the lens unit of FIG. 1 as viewed from the object side, and FIG. 2B is a schematic side view of the lens unit of FIG. 1 with a partial cross-section (partial half cross-section along line X-X) as viewed from direction A in FIG. 2 is a schematic cross-sectional view of a camera module having the lens unit of FIG. 1 according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view of a conventional lens unit having an integrally molded lens barrel. FIG. 1A is a plan view of a lens unit having a conventional integrally molded lens barrel, as viewed from the object side, and FIG. 1B is a perspective view of the lens unit of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
It should be noted that the lens unit of this embodiment described below is intended particularly for a camera module such as an in-vehicle camera, and is fixedly installed, for example, on the outer surface of a vehicle, with wiring being pulled into the vehicle and connected to a display or other device.

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 resin and a plurality of lenses arranged in a stepped inner storage space S of the lens barrel 12, for example, four lenses consisting of a first lens 13, a second lens 14, a third lens 15, and a fourth lens 16 from the object side. These lenses 13 to 16 are incorporated in the lens barrel 12 so that they are stacked with spacers 22 between them. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a substrate having an image sensor (package sensor) not shown in FIG. 1, and an installation member not shown for installing the substrate on a vehicle such as an automobile. In this embodiment, the spacer 22 may also function as a "light blocking aperture" that blocks light rays that cause ghosts and light rays that cause aberrations, and an "aperture aperture" that limits the amount of transmitted light and determines the F-number, which is an index of brightness.

The lenses 13, 14, 15, and 16 are assembled and held in the inner storage space S of the lens barrel 12, and are stacked and arranged with their optical axes aligned, and the lenses 13, 14, 15, and 16 are arranged along a single optical axis O to form a group of lenses L used for imaging. In this case, the first lens 13, which is positioned closest to the object side of the lens group L, is a spherical glass lens whose surface 13d facing the object side is formed as a convex surface that is convex toward the object side, and whose back surface 13e facing the second lens 14 (facing the image side) is a concave surface that forms a cavity that is recessed toward the inside of the lens, and the other lenses 14, 15, and 16 are resin lenses, but are not limited to this (for example, the first lens 13 may be a resin lens).

The present invention, including this embodiment, is characterized by the shape of the object side end of the resin lens barrel 12, and the shape of the lens barrel and lenses, the number of lenses, and the material of the lenses can be set arbitrarily depending on the application. In addition, the surfaces of these lenses 13, 14, 15, and 16 are provided with an anti-reflection film, a hydrophilic film, a water-repellent film, etc., as necessary.

In this embodiment, an O-ring 26 is inserted between the first lens 13, which is located closest to the object, 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 reduced diameter at the image side portion of the lens 13 is provided on the outer peripheral side surface 13a of the first lens 13, and an O-ring 26 is attached to this reduced diameter portion 13b. The O-ring 26 is compressed in the radial direction between the outer peripheral side surface 13a of the first lens 13 and the inner peripheral surface 12a of the lens barrel 12, sealing the object side end of the lens barrel 12. 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.

When the lens group L is assembled and housed in the internal housing space S of the lens barrel 12, a crimping portion (extending around the entire circumference so as to taper toward the object side) 23 at the object side end (upper end in FIG. 1) of the lens barrel 12 is thermally crimped radially inward, thereby fixing the first lens 13 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 this case, to ensure stable crimping, the portion of the glass lens 13 where the crimping portion 23 is pressed against is formed as a flat portion 13c that is cut diagonally in a plane.

The end of the lens barrel 12 on the image side (the lower end in FIG. 1) is provided with an inner flange portion 24 having an opening with a smaller diameter than the fourth lens 16. The inner flange portion 24 and the crimped portion 23 hold and fix the multiple lenses 13, 14, 15, and 16 that make up the lens group L and the spacer 22 in the lens barrel 12 in the optical axis direction.

As can be seen from FIG. 2, the lens barrel 12 according to this embodiment is formed into a substantially cylindrical shape by pouring molten resin into a mold (not shown) through two or more gates G (four in this embodiment spaced at 90-degree intervals from each other in the circumferential direction) (FIG. 2 does not show the gates G themselves, but shows four parts 12ba, 12bb, 12bc, and 12bd of the lens barrel 12 corresponding to the positions of the gates G; the same is true for FIG. 3(a)). The object-side end of the lens barrel 12 is provided with a notch 30 extending from the object-side end to the image side beyond the crimped portion 23, located approximately in the middle of the circumferential angular range between the adjacent parts of the lens barrel 12 corresponding to the positions of the gates G. Specifically, in this embodiment of the four-point gate, as shown in FIG. 3A, a notch 30 is provided at the object side end of the barrel 12, located approximately in the middle of the circumferential angular range R1 between the adjacent parts 12ba and 12bb of the barrel 12 corresponding to the position of the gate G, a notch 30 is provided approximately in the middle of the circumferential angular range R2 between the adjacent parts 12bb and 12bc of the barrel 12 corresponding to the position of the gate G, a notch 30 is provided approximately in the middle of the circumferential angular range R3 between the adjacent parts 12bc and 12bd of the barrel 12 corresponding to the position of the gate G, and a notch 30 is provided approximately in the middle of the circumferential angular range R4 between the adjacent parts 12bd and 12ba of the barrel 12 corresponding to the position of the gate G.

In this embodiment, these four notches 30 are provided corresponding to the positions of the welds where the molten resin flowing from each gate G joins in the mold (not shown). In this case, it is preferable to specify the positions of the welds from the results of a simulation using, for example, resin flow simulation software. Furthermore, each notch 30 is not only notched to a depth that covers the entire length of the thermally crimped crimped portion 23 in the optical axis direction, but also extends beyond the crimped portion 23 to the image side, just before the O-ring 26 (for example, just before the stepped reduced diameter portion 13b). That is, not only is the notch 30 provided over the entire crimped area that applies a crimping holding force to the first lens 13, but it also extends deeper toward the image side than the crimped portion 23, and extends along the outer peripheral side surface 13a of the first lens 13 that extends approximately parallel to the optical axis O so as to connect the front surface 13d and back surface 13e of the first lens 13 beyond the base of the crimped portion 23.

In addition, in this embodiment, in order to compensate for the crimping force of the crimping portion 23 for the first lens 13, which may be reduced by the formation of the notches 30, each notch 30 is filled with an adhesive (not shown).

In addition, the lens unit 11 of this embodiment is further provided with a light-shielding means for blocking the incidence of light on the exposed portion of the first lens 13 exposed to the outside through the cutout 30. Such a light-shielding means may be formed by ink (not shown) applied to the exposed portion of the first lens 13, or may be achieved by imparting light-shielding properties to the aforementioned adhesive filled in the cutout 30. Examples of adhesives having light-shielding properties include adhesives made of ultraviolet-curing resin, thermosetting resin, etc.

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 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 (image sensor) 304 that is disposed at the imaging position of the lens group L.

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 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 notch 30 can eliminate the weld portion, which is a weak portion, and therefore the occurrence of cracks can be prevented. This avoids problems associated with cracks, such as a decrease in the crimping force of the crimping portion 23 for the lens 13, which makes it impossible to fix the lens with the desired crimping strength, and problems such as the occurrence of stray light and the like, which adversely affect the optical performance.

In addition, in this embodiment, the cutout 30 is filled with adhesive, so that the crimping force of the crimping portion 23 for the lens 13, which may be reduced by the formation of the cutout 30, can be compensated for by the adhesive, and the fixing force of the lens 13 at the crimping portion 23 can be secured at a desired level.

In addition, in this embodiment, a light-shielding means is provided to block the incidence of light on the exposed portion of the first lens 13 that is exposed to the outside through the cutout 30, so that the light-shielding failure caused by the cutout 30 can be covered by the light-shielding means.

The present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the scope of the present invention. For example, the shapes of the lenses, lens barrels, etc. are not limited to those of the above-described embodiments. In addition, in the above-described embodiments, the shape of the notches is rectangular when viewed from the optical axis direction, but the shape of the notches is not limited to this. The number of notches can be set arbitrarily according to the number of gates. Furthermore, the above-described embodiments may be combined in part or in whole, or part of the configuration may be omitted from one of the above-described embodiments, without departing from the scope of the present invention.

11 Lens unit 12 Lens barrel 13 First lens (the lens located closest to the object)
13a: Outer peripheral side surface 13d: Front surface 13e: Back surface 23: Crimping portion 30: Notch 300: Camera module O: Optical axis L: Lens group S: Inner storage space

Claims (9)

a lens barrel which is molded into a substantially cylindrical shape by pouring molten resin into a mold through two or more gates spaced apart from each other in a circumferential direction, and has an internal accommodation space into which a lens group is incorporated, and which has a crimping portion at an object side end portion for fixing a lens located closest to the object side of the lens group incorporated in the internal accommodation space by being crimped radially inward,
a notch is provided at the object-side end of the lens barrel, the notch being located approximately midway in the circumferential angular range between adjacent portions of the lens barrel that correspond to the position of the gate, and extending from the object-side end to the image side, beyond the base of the crimped portion, along the portion where the outer peripheral side of the lens closest to the object should be located . The lens barrel according to claim 1, characterized in that the notch is provided at a position corresponding to a weld portion where the molten resin flowing from each gate joins inside the mold. A lens unit comprising: a lens group including a plurality of lenses arranged along an optical axis; and a lens barrel having an inner storage space for incorporating the lens group,
the lens barrel is molded into a substantially cylindrical shape by pouring molten resin into a mold through two or more gates that are spaced apart from each other in a circumferential direction, and has a crimping portion at an object-side end for fixing a lens located closest to the object side among the lens group that is incorporated into the inner accommodation space by being crimped radially inward,
the lens located closest to the object side in the lens group has a front surface facing the object side, a back surface facing the image side, and an outer peripheral side surface extending substantially parallel to the optical axis so as to connect the front surface and the back surface,
a notch is provided at the object-side end of the lens barrel, the notch being located approximately midway in the circumferential angular range between adjacent portions of the lens barrel that correspond to the position of the gate, the notch extending from the object-side end to the image side, beyond a base of the crimped portion, along the outer peripheral side surface of the lens closest to the object . The lens unit according to claim 3, characterized in that the notch is provided at a position corresponding to a weld portion where the molten resin flowing from each gate joins inside the mold. 5. The lens unit according to claim 3, wherein the notch is filled with an adhesive. 6. The lens unit according to claim 3, further comprising a light blocking means for blocking light from entering an exposed portion of the lens that is exposed to the outside through the notch. 7. The lens unit according to claim 6 , wherein the light blocking means is formed by applying ink to the exposed portion of the lens. 7. The lens unit according to claim 6 , wherein the light blocking means is formed by a light blocking adhesive that is filled in the notch. 9. A camera module comprising the lens unit according to claim 3, and an image sensor disposed at an image forming position of the lens group.