Lens unit and vehicle-mounted camera

Abstract

To provide a lens unit and an on-vehicle camera capable of preventing rattling between lenses due to temperature change, and suppressing the deterioration of optical performance.SOLUTION: A lens unit is equipped with a lens group 19, a lens barrel 10 integrally supports the lens group 19, an intermediate ring 13 disposed between lenses in at least one place of the lens group, and an elastic member 15 provided between a lens 4 and the intermediate ring 13 adjacent in an optical axis direction. The lens 4 adjacent to the elastic member 15 has an annular recessed portion 4a recessed in an optical axis direction on an outer peripheral portion, and the elastic member 15 is provided in the recessed portion 4a in a compressed state. The elastic member 15 presses a lens disposed on an article side against an end portion of an article side of the lens barrel by the elastic member, and presses the lens disposed on an image side against an end portion on the image side of the lens barrel through the intermediate ring 13 by the elastic member 15, thereby absorbing rattling.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lens unit suitable for an on-board camera mounted on a vehicle such as an automobile, and to an on-board camera. [Background technology]

[0002] 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 these cameras to autonomous driving. Such on-board cameras are exposed to similarly harsh temperature environments when the vehicle is exposed to cold or hot environments, and furthermore, on-board cameras located on the outside of the vehicle may be subject to the effects of cold winds and snow, or may be overheated by sunlight.

[0003] Therefore, it is desirable for vehicle-mounted cameras used in automobiles to be able to be used stably in a range of temperatures from low to high, and various temperature countermeasures have been proposed (for example, see Patent Document 1). In recent years, the incorporation of cameras into mobile phones (smartphones) and other devices has led to a high demand for high-performance, low-cost cameras, and relatively inexpensive plastic lenses have become widespread. Although components such as plastic lenses and plastic lens barrels can also be used in vehicle-mounted cameras, vehicle-mounted cameras that are placed outside the vehicle are subject to low and high temperatures, as mentioned above, and are exposed to rain, snow, hail, and the like, and may also be hit by flying stones or objects falling from the vehicle. Therefore, when durability is important, glass lenses and metal lens barrels are often used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-298968 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a camera with a certain level of performance, a lens group consisting of, for example, four or more lenses is used as the lens, and the lenses of this lens group are held in a state where they are aligned in a row with their optical axes aligned in the lens barrel. In addition, an intermediate ring may be provided to adjust the distance between the lenses in the optical axis direction. In addition, within the lens barrel, for example, the outer peripheral surface of the lens or the intermediate ring contacts the inner peripheral surface of the lens barrel to determine radial positioning, and the object (subject) side and the image sensor side of the lens group are positioned to determine the optical axis direction, and the lens group is appropriately held within the lens barrel. Therefore, the lenses of the lens group are stacked in the optical axis direction, and each lens is not fixed to the lens barrel.

[0006] When a lens barrel holds such a lens group or intermediate ring consisting of multiple lenses lined up in the optical axis direction, the length of the lens barrel along the optical axis direction becomes long, and if the lens barrel or intermediate ring is made of metal with a relatively large expansion coefficient, the amount of change in length along the optical axis direction due to temperature change becomes large. On the other hand, the linear expansion coefficient of a glass lens is generally smaller than that of metal, and for example, the amount of expansion in the optical axis direction due to a temperature rise of the lens barrel becomes larger than the amount of expansion in the optical axis direction of the entire lens group, resulting in gaps between the lenses of the lens group and rattle. When this happens, the lens spacing changes and the lenses tilt slightly, resulting in degradation of optical performance.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a lens unit and an on-board camera that can prevent rattling between lenses due to temperature changes and suppress deterioration of optical performance. [Means for solving the problem]

[0008] In order to achieve the above object, a lens unit according to the present invention includes a lens group in which a plurality of lenses are arranged along an optical axis of the lens, a lens barrel that supports the lens group as a unit, an intermediate ring that is disposed between at least one lens of the lens group, and an annular elastic member that is provided between the lenses and the intermediate ring that are adjacent to each other in the optical axis direction, the lens adjacent to the elastic member in the optical axis direction has an annular recess in an outer periphery thereof recessed in the optical axis direction, The elastic member is provided in the recess in a compressed state in the optical axis direction, The elastic member absorbs play that occurs due to relative movement between the lens barrel and the lens group in the optical axis direction caused by temperature changes by pressing the lens located on the object side of the elastic member against the object side end of the lens barrel, and by pressing the lens located on the image side of the elastic member against the image side end of the lens barrel via the intermediate ring.

[0009] With this configuration, in the event that a gap occurs between the lenses of the lens group along the optical axis direction due to a difference in the linear expansion coefficient between the lens barrel and the lenses caused by a rise in temperature, resulting in play, the elastic member presses the lens located on the object side of the elastic member against the object side end of the lens barrel, and presses the lens located on the image side of the elastic member against the image side end of the lens barrel via the intermediate ring, thereby absorbing the play. Therefore, it is possible to prevent the occurrence of rattle between the lenses due to temperature changes and suppress deterioration of the optical performance. The elastic member may be made of rubber or a leaf spring.

[0010] In the above-mentioned configuration of the present invention, another lens is provided between the lenses that sandwich the elastic member in the optical axis direction, The outer periphery of the other lens may be adhesively fixed to the intermediate ring.

[0011] With this configuration, the outer periphery of the other lens is adhesively fixed to the intermediate ring, so that the other lens can be moved toward the image side of the lens barrel by the intermediate ring, and no play occurs in the other lens.

[0012] A lens unit according to the present invention includes a lens group in which a plurality of lenses are arranged along an optical axis direction of the lenses, a lens barrel that integrally supports the lens group, and an annular elastic member that is disposed between at least one lens of the lens group; the lenses sandwiching the elastic member in the optical axis direction have abutment surfaces that abut against each other at parts of their opposing outer circumferential surfaces, one of the lenses sandwiching the elastic member in the optical axis direction has an annular recess that is recessed in the optical axis direction on an outer circumferential surface that is outer circumferential side of the abutment surface, The elastic member is provided in the recess in a compressed state in the optical axis direction, The elastic member absorbs play that occurs due to relative movement between the lens barrel and the lens group in the optical axis direction caused by temperature changes by pressing the lens located on the object side of the elastic member against the object side end of the lens barrel, and by pressing the lens located on the image side of the elastic member against the image side end of the lens barrel.

[0013] With this configuration, in the event that a gap occurs between the lenses of the lens group along the optical axis direction due to a difference in the linear expansion coefficient between the lens barrel and the lenses caused by a rise in temperature, resulting in rattle, the elastic member presses the lens located on the object side of the elastic member against the object side end of the lens barrel, and presses the lens located on the image side of the elastic member against the image side end of the lens barrel, thereby absorbing the rattle. Therefore, it is possible to prevent the occurrence of rattle between the lenses due to temperature changes and suppress deterioration of the optical performance. In addition, the lenses that sandwich the elastic member in the optical axis direction have abutment surfaces that abut against each other on part of their opposing outer circumferential surfaces, and as the abutment surfaces abut against each other, no play occurs between the lenses at room temperature.

[0014] In the above-described configuration of the present invention, the elastic member may be disposed at a position where inter-surface sensitivity, which is the sensitivity of image formation to a distance between lens surfaces, is lowest among the plurality of lenses constituting the lens group.

[0015] With this configuration, the elastic member presses the lens located on the object side of the elastic member against the object side end of the lens barrel, and presses the lens located on the image side of the elastic member against the image side end of the lens barrel.Even if a certain gap occurs between the lenses, the elastic member is positioned at a position where the inter-surface sensitivity is lowest, so degradation of optical performance can be suppressed.

[0016] The vehicle-mounted camera according to the present invention comprises the lens unit and a substrate having an imaging sensor; and a member for supporting the lens unit in a positioned state with respect to the substrate. Effect of the Invention

[0017] According to the present invention, it is possible to prevent the occurrence of rattle between lenses due to temperature changes and suppress deterioration of optical performance. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing a lens unit of an in-vehicle camera according to a first embodiment of the present invention. [Diagram 2] FIG. 27 is a cross-sectional view showing a lens unit of an in-vehicle camera according to a twentieth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The lens unit of this embodiment is for an in-vehicle camera, and is fixedly installed on the outer surface of a vehicle, for example, with wiring leading into the vehicle and connected to a display or other device.

[0020] (First embodiment) As shown in Fig. 1, the lens unit 20 of the vehicle-mounted camera of this embodiment includes a cylindrical lens barrel 10, multiple (six) lenses 1, 2, 3, 4, 5, and 6 arranged inside the lens barrel 10, an optical filter 9 arranged at the end of the lens barrel 10 on the side where the lenses 1, 2, 3, 4, 5, and 6 form an image (imaging) (the side where the image sensor 8 is arranged), a pressing member 18 that presses the lens 1 inside the lens barrel 10 at the end on the side of the object to be photographed, and three intermediate rings 11, 12, and 13 that function as spacers. Note that in Fig. 1 and Fig. 2 described later, the end on the object side is the upper end, and the end on the image side is the lower end.

[0021] The vehicle-mounted camera of this embodiment comprises the above-mentioned lens unit 20, a board 16 having an image sensor 8, a support member (mount) 17 that supports the lens barrel 10 in a positioned state relative to the board 16 equipped with the image sensor 8, and an installation member (not shown) that installs the board 16 in the vehicle. In addition, in FIG. 1 showing this embodiment and FIG. 2 showing a second embodiment described later, hatching of lenses 1, 2, 3, 4, 5, and 5 constituting lens unit 20 is omitted.

[0022] The multiple lenses 1, 2, 3, 4, 5, 6 fixed to and supported by the lens barrel 10 are arranged with their optical axes aligned, and the lenses 1, 2, 3, 4, 5, 6 are lined up along one optical axis to form a lens group 19 used for imaging. Therefore, when simply referring to the optical axis below, this refers to the optical axis of the lenses 1, 2, 3, 4, 5, 6 as well as the optical axis of the lens group 19.

[0023] Of the intermediate rings 11, 12, and 13, the first intermediate ring 11 from the object side is disposed between the first lens 1 and the second lens 2, with the lens 1 in contact with the upper end of the intermediate ring 11 and the lens 2 in contact with the lower end of the intermediate ring 11. The second intermediate ring 12 is disposed between the second lens 2 and the third lens 3, with the lens 2 in contact with the upper end of the intermediate ring 12 and the lens 3 in contact with the lower end of the intermediate ring 12. Moreover, the third intermediate ring 13 is disposed between the fourth lens 4 and the sixth lens 6. Furthermore, an elastic member 15 is disposed between the fourth lens 4 and the third intermediate ring 13. Therefore, the elastic member 15 is in contact with the upper end of the intermediate ring 13, and the lens 6 is in contact with the lower end of the intermediate ring 13.

[0024] The lens 4 adjacent to the elastic member 15 in the optical axis direction has an annular recess 4a recessed in the optical axis direction on the outer periphery. The elastic member 15 is provided in this recess 4a in a compressed state in the optical axis direction. Furthermore, the position where the inter-surface sensitivity, which is the sensitivity of imaging to the lens surface distance among the multiple lenses constituting lens group 19, is lowest is between lenses 4 and 5, and elastic member 15 is provided between these two lenses. However, lens 5 has a smaller diameter than lens 4, and its outer periphery is separated from the inner periphery of lens barrel 10, so as described above, a recess 4a is provided on the outer periphery of lens 4, and elastic member 15 is provided in this recess 4a.

[0025] In this embodiment, the elastic member 15 is configured of an annular metal wave spring (wave washer). The wave spring is, for example, disk-shaped with a hole in the center, and has a wavy shape along the circumferential direction because the position along the axial direction perpendicular to the disk changes depending on the position in the circumferential direction. Such elastic member 15 absorbs play that occurs with relative movement in the optical axis direction between the lens barrel 10 and the lens group 19 due to temperature changes (e.g., a temperature change from room temperature to a high temperature) by elastically pressing the lenses 1, 2, 3, and 4, which are located on the object side of the elastic member 15, against a pressure member 18 provided at the object side end of the lens barrel 10, and by pressing the lens 6, which is located on the image side of the elastic member 15, against an inner flange portion 21 provided at the image side end of the lens barrel 10 via the intermediate ring 13.

[0026] Further, the intermediate ring 13 has an inner flange portion 13a at its object side end, and the outer periphery of the lens (other lens) 5 is adhesively fixed to this inner flange portion 13a. Therefore, the lens 5 is supported by the intermediate ring 13, and when the intermediate ring 13 is pressed toward the image side by the elastic member 15 and moves, the lens 5 moves toward the image side together with the intermediate ring 13.

[0027] The lens barrel 10 has a male thread formed on the outer periphery of the object side end, and a female thread formed on the inner periphery of an annular pressing member 18 is screwed onto this male thread, so that the pressing member 18 is fixed to the object side end of the lens barrel 10. The above-mentioned six lenses 1, 2, 3, 4, 5, 6, three intermediate rings 11, 12, 13, and elastic member 15 are arranged in a state sandwiched between this pressing member 18 and an inner flange portion 21 provided at the image side end of the lens barrel 10. A predetermined number of disk-shaped diaphragm members may be provided at predetermined positions between the pressing member 18 and the inner flange portion 21.

[0028] Furthermore, the lens barrel 10 is joined to the inner peripheral surface of the support member 17 and is supported by the support member 17. The support member 17 is formed in a roughly cylindrical shape, the lens barrel 10 is disposed inside it, and the outer peripheral side of the lens barrel 10 is joined to the inner peripheral side of the support member 17. The end of the support member 17 on the imaging sensor 8 side is fixed to the substrate 16 on which the imaging sensor 8 is mounted. In this way, the support member 17 supports the lens unit 20 having the lens barrel 10 in a state where it is positioned relative to the imaging sensor 8.

[0029] In this embodiment, the lenses 1 to 6 are made of glass, for example, so-called optical glass, and the lens barrel 10 and the intermediate rings 11 to 13 are made of metal, for example, an aluminum alloy.

[0030] In such a lens unit 20 and vehicle-mounted camera, as described above, six lenses 1, 2, 3, 4, 5, 6, three intermediate rings 11, 12, 13, and an elastic member 15 are sandwiched between the pressure member 18 and the inner flange portion 21 at the image side end of the lens barrel 10. It is preferable that such a vehicle-mounted camera can be used in a wide temperature range. For example, it is preferable that it can be used in a range of -40°C to 105°C. In this case, for example, when the design is performed based on 25°C, which is the normal temperature range, when the temperature rises within the range of 105°C, a difference occurs between the amount of change due to thermal expansion of the total length of the lenses 1, 2, 3, 4, 5, and 6 and the three intermediate rings 11, 12, and 13 arranged in a stacked manner along the optical axis direction and the amount of change due to thermal expansion of the length of the lens barrel 10 along the optical axis direction (the length from the pressing member 18 to the inner flange portion 21), resulting in gaps between the lenses 1 to 6.

[0031] In this case, gaps may occur between the lenses 1, 2, 3, 4, 5, and 6 of the lens group 19, and gaps may occur along the optical axis direction between the lenses 1, 2, 3, 4, 5, and 6, causing backlash. In this case, the elastic member 15 presses the lenses 1, 2, 3, and 4 arranged on the object side of the elastic member 15 against the pressing member 18 at the object side end of the lens barrel 10, and presses the lens 6 arranged on the image side of the elastic member 15 against the inner flange portion 21 provided at the image side end of the lens barrel 10 via the intermediate ring 13, thereby absorbing the backlash. Therefore, it is possible to prevent the occurrence of rattle between the lenses due to temperature changes and suppress deterioration of the optical performance. Furthermore, since the outer periphery of the lens 5 is adhesively fixed to the inner flange portion 13a of the intermediate ring 13, the lens 5 can be moved toward the image side of the lens barrel by the intermediate ring 13, and no play occurs in the lens 5.

[0032] In this embodiment and in the second embodiment described later, lenses 1, 2, 3, 4, 5, and 6 are made of glass and lens barrel 10 is made of metal, but even if these are made of resin, the present invention can be applied in cases where a difference occurs between the amount of displacement due to thermal expansion of lens group 19 and the amount of displacement due to thermal expansion of lens barrel 10, as described above, due to differences in the thermal expansion coefficient caused by differences in materials, etc.

[0033] Second embodiment Next, a second embodiment of the present invention will be described with reference to FIG. The lens unit 20 of the second embodiment differs from the first embodiment in that the fifth lens 5 has a larger diameter than the lens 5 in the first embodiment. The following describes this point and the surrounding area, and the same components as in the first embodiment are given the same symbols and their description is omitted.

[0034] As shown in FIG. 2, in this embodiment, lens 5 has a larger diameter than lens 5 in the first embodiment, its outer peripheral surface is in contact with the inner peripheral surface of lens barrel 10, and the curvatures of the upper and lower surfaces of lens 5 are larger than the curvatures of the upper and lower surfaces of lens 5 in the first embodiment. The lenses 4, 5 sandwiching the elastic member 15 in the optical axis direction have contact surfaces 4b, 5b that come into contact with each other at parts of their opposing outer circumferential surfaces, and these contact surfaces 4b, 5b come into contact with each other. The contact surface 4b is provided radially inward from the recess 4a and is a flat surface perpendicular to the optical axis direction. The contact surface 5b is a flat surface perpendicular to the optical axis direction, faces the contact surface 4b, extends to the inner peripheral surface of the lens barrel 10, and is in contact with the elastic member 15.

[0035] The elastic member 15 is provided in the recess 4a in a compressed state in the optical axis direction. The position where the inter-surface sensitivity, which is the sensitivity of imaging to the lens inter-surface distance among the multiple lenses constituting the lens group 19, is lowest is between the lenses 4 and 5, and the elastic member 15 is provided between them. Furthermore, since the outer peripheral surface of lens 5 contacts the inner peripheral surface of the lens barrel 10, the intermediate ring 13 does not have an inner flange portion, unlike the intermediate ring 13 in the first embodiment, and lens 5 abuts against the upper end of the intermediate ring 13.

[0036] In such a lens unit 20 and vehicle-mounted camera, six lenses 1, 2, 3, 4, 5, 6, three intermediate rings 11, 12, 13, and an elastic member 15 are sandwiched between a pressure member 18 and an inner flange portion 21 at the image side end of the lens barrel 10. In such a vehicle-mounted camera, it is preferable that the usable temperature range is wide, as in the first embodiment. For example, it is preferable that the camera can be used in a range of -40°C to 105°C. In this case, for example, when the design is performed based on 25°C, which is the range of normal temperature, as the temperature rises, even within the range of 105°C, a difference occurs between the amount of change due to thermal expansion of the total length of the lenses 1, 2, 3, 4, 5, and 6 and the three intermediate rings 11, 12, and 13 arranged in a stacked manner along the optical axis direction and the amount of change due to thermal expansion of the length of the lens barrel 10 along the optical axis direction (the length from the pressing member 18 to the inner flange portion 21), resulting in a gap between the lenses 1 to 6.

[0037] In this case, gaps may occur between the lenses 1, 2, 3, 4, 5, and 6 of the lens group 19, and gaps may occur along the optical axis direction between the lenses 1, 2, 3, 4, 5, and 6, causing backlash. In this case, the elastic member 15 presses the lenses 1, 2, 3, and 4 arranged on the object side of the elastic member 15 against the pressing member 18 at the object side end of the lens barrel 10, and presses the lenses 5 and 6 arranged on the image side of the elastic member 15 against the inner flange portion 21 provided at the image side end of the lens barrel 10, thereby absorbing the backlash. Therefore, it is possible to prevent the occurrence of rattle between the lenses due to temperature changes and suppress deterioration of the optical performance. In addition, the lenses 4, 5 sandwiching the elastic member 15 in the optical axis direction have abutment surfaces 4b, 5b that abut against each other on parts of their opposing outer circumferential surfaces. Since the abutment surfaces 4b, 5b abut against each other, no rattling occurs between the lenses 4, 4 at room temperature. In addition, from the viewpoint of ensuring reliability, in the above embodiment, a metal annular wave spring (wave washer) is used as the elastic member 15, but if the requirement for reliability is low, a resin O-ring may be used instead, because a resin O-ring also has drawbacks such as expansion changes due to temperature and deterioration of elasticity over time. [Explanation of symbols]

[0038] 10. Telescope tube 1,2,3,4,5,6 Lenses 4a Recess 4b,5b Contact surface 8. Image Sensor 11,12,13 Middle ring 15 Elastic member 16 Substrate 17 Support member 19 Lens Group 20 Lens unit

Claims

1. a lens group in which a plurality of lenses are arranged along an optical axis direction of the lenses, a lens barrel that integrally supports the lens group, and an annular elastic member that is disposed between at least one lens of the lens group in a state of contact with both of the lenses, the lenses sandwiching the elastic member in the optical axis direction have abutment surfaces that abut against each other at parts of their opposing outer circumferential surfaces, one of the lenses sandwiching the elastic member in the optical axis direction has an annular recess that is recessed in the optical axis direction on an outer circumferential surface that is outer circumferential side of the abutment surface, The elastic member is provided in the recess in a compressed state in the optical axis direction, a lens unit comprising: a lens barrel having a first end and a second end, the lens barrel being arranged on a first side and a second side of the lens group; a lens unit having a second end and a second end, the lens unit being arranged on a second side and a second side of the lens group;

2. 2. The lens unit according to claim 1, wherein the elastic member is disposed at a position where inter-surface sensitivity, which is sensitivity of imaging to a distance between lens surfaces, is lowest among the plurality of lenses constituting the lens group.

3. The lens unit according to claim 1 or 2; a substrate having an imaging sensor; a support member that supports the lens unit in a positioned state with respect to the substrate; An in-vehicle camera comprising:

Images