JP2020098359A - Lens unit and on-vehicle camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens unit and a vehicle-mounted camera capable of preventing a lens supported by a lens barrel from moving due to temperature change. A lens unit 20 includes a lens group 19 in which a plurality of lenses 2, 3, 4, 5, 6, 7 are arranged along an optical axis of the lenses 2, 3, 4, 5, 6, 7. , A lens barrel 1 that integrally supports the lens group 19, and a member that presses the most object-side first lens 2 of the lens group 19 toward the image side by being screwed and fastened to the object-side end of the casing 1. And a pressing member 18 having a stopper 18a. The first lens 2 has an annular recess that is recessed in the optical axis direction on the outer periphery of the object side surface. The concave portion is provided with an annular elastic body 13b interposed between the first lens 2 and the locking portion 18a of the pressing member 18. [Selection diagram] Figure 2

Description

The present invention relates to a lens unit suitable for an on-vehicle camera mounted on a vehicle such as an automobile and an on-vehicle camera.

In recent years, an on-vehicle camera has been mounted on an automobile to support parking and prevent collision by image recognition, and further application to automatic driving has been attempted.
Such an on-vehicle camera is also exposed to the same severe temperature environment as the vehicle is exposed to cold and hot environments, and furthermore, the on-vehicle camera arranged outside the vehicle is affected by cold wind and snow. Or it may be overheated by sunlight.

Therefore, it is desired that the vehicle-mounted camera used during automobile use can be used stably from low temperature to high temperature, and various temperature countermeasures have been proposed (for example, refer to Patent Document 1).
In recent years, there is a great demand for high-performance and low-cost cameras due to the incorporation of cameras into mobile phones (smartphones) and the like, and relatively inexpensive resin lenses have become widespread.
Members such as resin lenses and resin lens barrels can also be used in in-vehicle cameras, but in in-vehicle cameras that are placed outside the vehicle, they can be exposed to low temperatures and high temperatures as described above, and are exposed to rain, snow, hail, etc. Since there is a possibility of being hit or hit by a bounced stone or a fallen object from an automobile, a glass lens and a metal lens barrel are often adopted when durability is important.

No. 2008-299868

By the way, in the case of a somewhat high-performance camera, a lens group including, for example, four or more lenses is used as a lens, and a plurality of lenses of this lens group are arranged in a line in the optical axis direction of the lens barrel. Will be held in. Further, in the lens barrel, the outer peripheral surface of the lens is in contact with and follows the inner peripheral surface of the lens barrel, and the object (subject) side and the image sensor side of the lens group do not appear outside the lens barrel. It is held in the lens barrel in such a state that it is sandwiched. Therefore, the lenses of the lens group are stacked in the optical axis direction, and the individual lenses are not fixed to the lens barrel.

When the lens barrel holds such a lens group composed of a plurality of lenses in the optical axis direction, the length of the lens barrel along the optical axis direction becomes long, and the lens barrel has a relatively large expansion coefficient. When a large metal is used, 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 the glass lens is generally smaller than that of metal, and, for example, the amount of expansion in the optical axis direction due to the temperature rise of the lens barrel is larger than the amount of expansion of the entire lens group in the optical axis direction.

In this case, there may be a gap between the lenses in the lens group, which causes the lenses to tilt slightly so that they are slightly tilted, and the optical axis direction of the lenses may be slightly displaced from the axial direction of the lens barrel. There is a nature. When the lens in the lens barrel moves in this way, for example, when an image taken by an in-vehicle camera is displayed on a monitor, the lens moves a little and the image on the monitor moves a little. That is, the lens moves due to the gap between the lenses, which causes a shift in the image pickup range, which causes a shift in the position of the captured image.

If you just shoot while viewing the video and display the captured video, you can determine the imaging range by moving the camera at the time of shooting, so such a slight movement of the video is not a big problem, This may be a problem when an in-vehicle camera is used for collision prevention by assisting or image recognition. For example, in parking assistance, a guideline (display of a thick line) is often displayed on the monitor along with the image captured by the vehicle-mounted camera. If the image of “1” moves, the positional relationship between the guideline and the image may shift, and it may be difficult to park the vehicle at an appropriate position along the guideline. Further, in the collision prevention, since the positional relationship between the vehicle and the external object is obtained based on the image, a problem may occur if the image is displaced. Even if the lens barrel and the lens are made of resin, the above-mentioned problem due to the temperature change may occur due to the difference in material between the lens barrel and the lens.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens unit and a vehicle-mounted camera that can prevent the lens supported by the lens barrel from moving due to temperature changes.

In order to solve the above problems, the lens unit of the present invention,
A lens group in which a plurality of lenses are arranged along the optical axis of the lens, a lens barrel integrally supporting the lens group, between at least one lens of the lens group, or the object side of the lens group Or, with an annular spacer arranged at the image-side end,
The spacer is extendable in the optical axis direction of the lens.

According to such a configuration, when the gap along the optical axis is generated between the lenses of the lens group due to the difference in linear expansion coefficient between the lens barrel and the lens due to the temperature rise, the spacer is arranged in the optical axis direction. It is possible to prevent the expansion and the formation of a gap between the lenses. As a result, when a gap is formed between the lenses, for example, it is possible to prevent a part of the lenses from being inclined and the imaging range from changing. This makes it possible to improve reliability at high temperatures in parking assistance, collision prevention, automatic driving, etc. using an on-vehicle camera. It is preferable that the spacer extendable in the optical axis direction is made of, for example, an elastic member such as rubber or spring, and is arranged in a compressed state in the optical axis direction. Further, the spacer may be a member that can expand and contract in the optical axis direction, such as a polymer actuator.

In the above structure of the present invention, it is preferable that the spacer is an elastic body.
According to such a configuration, for example, various rubbers, rubber-like resins, and various springs (metal disc springs, wave springs, etc.) can be used, and they are relatively low in cost and can be used between the lenses when the temperature rises. A gap can be prevented from occurring. Since the spacers are basically arranged between the lenses in a compressed state, an elastic force acts on the lenses and the like, but a gap is generated between the lenses at a high temperature due to an elastic force at a level where no particular problem occurs. Can be suppressed.

In the above structure of the present invention, it is preferable that the spacer is a spring.
With such a configuration, it is easy to make the expandable and contractable spacer made of metal, and it is possible to provide a structure in which durability is easily obtained. That is, in the case of springs, many products are made of metal, and by making the extendable spacers made of metal, it becomes easy to improve durability.

In the above structure of the present invention, it is preferable that the spacer is a wave spring.
According to such a configuration, by using the wave spring as the extending spacer, the length along the optical axis at the time of compression is short, and the length is sufficient to fill the gap between the lenses due to thermal expansion. It is possible to extend and it is not necessary to design the distance between the lenses to be long in order to arrange the extending spacer.

An in-vehicle camera of the present invention includes the lens unit having the above-mentioned configuration.
With such a configuration, the operational effects of the lens unit described above can be obtained with the vehicle-mounted camera.

According to the present invention, in a lens unit that may be used at high temperature or low temperature like an in-vehicle camera mounted on a vehicle such as an automobile, it can be sufficiently used at low temperature and suppresses deviation of the imaging range at high temperature. it can.

It is sectional drawing which shows the lens unit of the vehicle-mounted camera of the 1st Embodiment of this invention. It is sectional drawing which shows the lens unit of the vehicle-mounted camera of the 2nd Embodiment of this invention.

The first embodiment of the present invention will be described below.
The lens unit according to the present embodiment is for a vehicle-mounted camera, for example, is fixedly installed on the outer surface side of an automobile, and wiring is drawn into the automobile and connected to a display and other devices.

As shown in FIG. 1, the lens unit 20 of the vehicle-mounted camera according to this embodiment includes a cylindrical lens barrel 1 and a plurality of (six) lenses 2, 3, 4, 5 arranged in the lens barrel 1. , 6, 7 and the lenses 2, 3, 4, 5, 6, 7 of the lens barrel 1 are arranged at one end on the (imaging) side where the images are formed (the side on which the image sensor 8 is arranged). An optical filter 9, a pressing member 18 that presses the lens 2 in the lens barrel 1 at the other end on the object side to be photographed, three diaphragm members 10, 11, 12, and three spacers (intermediate rings) 13, 14 and 15. The vehicle-mounted camera according to the present embodiment includes the above-mentioned lens unit 20, the substrate 16 having the image sensor 8, and a support member (mount) for supporting the lens barrel 1 in a positioned state with respect to the substrate 16 having the image sensor 8. 17 and an installation member (not shown) for installing the substrate 16 in an automobile.

The plurality of lenses 2.3.4.5.6.7 fixed and supported by the lens barrel 1 are arranged so that their optical axes coincide with each other, and each lens 2.3.4.5.6.7 is arranged along one optical axis. The lenses 2, 3, 4, 5, 6, 7 are arranged side by side to form one lens group 19 used for imaging. Therefore, in the following description, when simply described as an optical axis, the optical axis of each lens 2, 3, 4, 5, 6, 7 is shown and the optical axis of the lens group 19 is shown.

The first diaphragm member 10 from the object side (the other end of the lens barrel 1) of the three diaphragm members 10, 11 and 12 is located between the first lens 2 and the second lens 3 from the object side. It is located in. The second diaphragm member 11 from the object side is a spacer that is arranged between the second lens 3 and the third lens 4 from the object side and between the lenses 3 and 4 along the optical axis direction. It is arranged between 13 and the spacer 14. The third diaphragm member 12 from the object side is arranged between the spacer 15 arranged between the fourth lens 5 and the sixth lens 7 from the object side and the sixth lens 7.

The first spacer 13 and the second spacer 14 from the object side among the annular spacers 13, 14, 15 which are the intermediate rings are between the second lens 3 and the third lens 4 as described above. It is arranged. One of the two spacers 13.14 on the object side is made of an elastic member and is arranged between the lens 3 and the lens 4 in a compressed state. Specifically, the spacer 13 is arranged between the lens 3 and the lens 4 via the spacer 14.

The spacer 13 is made of a spring as an elastic member. The spacer 13 is composed of an annular wave spring (wave washer). The wave spring has, for example, an annular shape with a disc shape and a hole in the center, and the position along the axial direction orthogonal to the disc changes along the circumferential direction by changing depending on the circumferential position. It has a wavy shape.

The wave spring is a kind of leaf spring and can be expanded in the axial direction when compressed in the axial direction described above. Therefore, due to the difference in linear expansion coefficient between the lens barrel 1 and the lenses 2 to 7 when the temperature rises, When a gap is generated between the lenses 2 to 7, it is prevented from being compressed in the optical axis direction and the spacer 13 arranged between the lenses 2 to 7 expands so that a gap is generated between the lenses 2 to 7. It is like this.

In the lens barrel 1, a male screw portion is formed on the outer circumference of the other end portion on the object side, and a female screw portion formed on the inner circumference of the annular holding member 18 is screwed onto the male screw portion, so that the holding member 18 is a mirror. It is fixed to the other end of the cylinder 1. Between the retaining portion 18a having a smaller inner diameter of the pressing member 18 and the retaining portion 1a formed on the inner peripheral side of one end of the lens barrel 1 so as to protrude inward so that the inner diameter becomes smaller. In the sandwiched state, the above-described six lenses 2, 3, 4, 5, 6, 7 and three diaphragm members 10.11.12 and three spacers 13, 14, 15 are arranged.

The lens barrel 1 is joined to the inner peripheral surface of the support member 17 and supported by the support member 17. Further, the support member 17 is formed in a substantially cylindrical shape, the lens barrel 1 is arranged inside thereof, and the outer peripheral side of the lens barrel 1 and the inner peripheral side of the support member 17 are joined. The end of the support member 17 on the image sensor 8 side is fixed to the substrate 16 on which the image sensor 8 is mounted. Accordingly, the support member 17 supports the lens unit 20 having the lens barrel 1 in the state of being positioned with respect to the image sensor 8.

Further, in the present embodiment, each of the lenses 2 to 7 is made of glass, for example, so-called optical glass, and the lens barrel 1 and the spacers 14 and 15 are made of metal, for example, an aluminum alloy. It consists of

As described above, in the lens unit 20 and the in-vehicle camera as described above. Between the locking portion 18a of the pressing member 18 and the locking portion 1a at one end of the lens barrel 1, six lenses 2, 3, 4, 5, 6, 7 and three diaphragm members 10.11. 12 and three spacers 13, 14 and 15 are arranged in a sandwiched state. In such a vehicle-mounted camera, it is preferable that the usable temperature range is wide. For example, it is preferable that it can be used in the range of -40°C to 105°C. In this case, for example, when the design is carried out based on the room temperature range of 25° C., the lenses 2, 3 arranged so as to be stacked even if the temperature rises up to 105° C. , 4, 5, 6, 7 and the three diaphragm members 10.11.12 and the three spacers 13, 14, 15 along the optical axis, the amount of change due to thermal expansion, and the lens barrel. There is a difference in the amount of change in the length of the No. 1 along the optical axis direction (the length from the locking portion 18a to the locking portion 1a) due to thermal expansion, and a gap is generated between the lenses 2 to 7.

In this case, a gap is generated between the lenses 2, 3, 4, 5, 6, 7 of the lens group 19, and each lens 2, 3, 4, 5, 6, 7 or a part of the lenses 2, 3, 4, There is a risk that 5, 6, and 7 will move so that the optical axis direction is inclined. In this case, the imaging range changes. When the photographer confirms the shooting range by moving the camera instead of the vehicle-mounted camera and shoots, the shooting range is changed by moving the lenses 2, 3, 4, 5, 6, 7 as described above. However, there is no problem because the photographer moves the camera to determine the shooting range. However, the in-vehicle camera is positioned and fixed to the vehicle. For example, when guiding the parking using the image of the in-vehicle camera, the position of the guide line displayed on the monitor and the position of the displayed image are deviated. This may make parking operation difficult.

Further, in the case of preventing collision between an external object and the vehicle body by image recognition as in the case of collision prevention or automatic driving, there is a possibility that the accuracy is lowered due to the deviation of the shooting direction. In the lens unit 20 and the vehicle-mounted camera according to the present embodiment, when a gap is created between the lenses 2, 3, 4, 5, 6, and 7, the wave spring is arranged so as to be compressed in the optical axis direction. The spacer 13 extends in the optical axis direction and prevents a gap from being formed between the lenses 2, 3, 4, 5, 6, 7. As a result, the lenses 2, 3, 4, 5, 6, 7 do not move even if the temperature rises, and as described above, in the parking guidance using the in-vehicle camera, collision prevention, automatic driving, etc., It is possible to prevent the occurrence of problems caused by the movement of the lenses 2, 3, 4, 5, 6, 7.

As the spacer 13, a polymer actuator or the like that can be expanded in the optical axis direction can be used, but an elastic body is preferably used in consideration of cost. As the elastic pair, for example, rubber or rubber-like resin can be used.

When the spacer 13 is a spring, a disc spring or other leaf spring can be effectively used in addition to the wave spring, and a coil spring may be used as the spring.

Further, in this embodiment, the lenses 2, 3, 4, 5, 6, 7 are made of glass and the lens barrel 1 is made of metal. The present invention can be applied when a difference occurs between the displacement amount due to the thermal expansion of the lens group 19 and the displacement amount due to the thermal expansion of the lens barrel 1 as described above due to the difference.

The arrangement position of the spacer 13 that can be extended in the optical axis direction may basically be such that the extended field finely presses the lenses 2, 3, 4, 5, 6, 7 in the optical axis direction. It is preferable to arrange the lenses 2, 3, 4, 5, 6, 7 at a position where the inter-surface sensitivity is lowest.

Next, a second embodiment of the present invention will be described.
As shown in FIG. 2, the lens unit 20 of the second embodiment has, for example, a spacer 13a made of the same material as the spacers 14 and 15 in place of the spacer 13 made of the wave spring of the first embodiment. Equipped with. In addition, between the lens 2 arranged at the object side end of the lens group 19 and the locking portion 18a of the pressing member 18 joined to the object side end of the lens barrel 1, a wave spring as an elastic body is provided. The annular spacer 13b is formed. That is, the lens unit 20 in the second embodiment is provided with a spacer 13b made of a wave spring in place of the spacer 13 made of the wave spring of the first embodiment. In the following description, the same components as those in the first embodiment will be assigned the same reference numerals as those in FIG. 1 in FIG. 2, and the description thereof will be omitted.

The spacer 13b is arranged in a compressed state between the lens group 19 and the pressing member 18, and is in a state of being extendable in the optical axis direction. Therefore, the lens group 19 is constantly pushed from the object side to the image formation side (sensor side) in the lens barrel 1. That is, the lens group 19 is in a state in which the whole of the lens group 19 is pressed against the locking portion 1a of the lens barrel 1 by the spacer 13b.

According to such a lens unit, when the lens barrel 1 thermally expands when the temperature rises and extends from the lens group 19 in the optical axis direction, the lens group 19 is pressed against the locking portion 1a on the image forming side, It is possible to prevent a gap from being generated between the lenses 2, 3, 4, 5, 6, 7 of the lens group 19, and it is possible to achieve the same excellent effect as that of the first embodiment.

Further, in the first embodiment, the spacer 13 made of a wave spring having elasticity and expandability is arranged between the lenses 3 and 4, that is, between the lenses of the lens group 19. In the second embodiment, the spacer 13b formed of a wave spring has the object side of the lens group 19, and the locking portion 18a for holding the lens group 19 in the lens barrel 1 by pressing the object side of the lens group 19. It is located between.

Accordingly, in the first embodiment, when the lens barrel 1 extends from the lens group 19 along the optical axis direction when the temperature rises, the spacer 13 extends in the optical axis direction, so that the lens 3 and the lens 4 are separated from each other. The distance between them changes more than the amount of change due to the expansion of the lens group 19 due to thermal expansion, which affects the image formation of the lens group 19.

On the other hand, in the second embodiment, for example, when the lens barrel 1 extends from the lens group 19 along the optical axis direction when the temperature rises, the spacer 13b extends in the optical axis direction, so that the lens group 19 extends. Since the whole is pressed against the locking portion 1a on the image forming side of the lens barrel 1, the distance between the lenses in the lens group 19 does not greatly extend only by the spacer 13, and the spacer 13b to the lens group 19 does not extend. The effect of stretching is reduced.

Further, since the lens group 19 is pressed against the image forming side by the spacer 13b, a spacer is arranged between the lens group 19 and the locking portion 1a of the lens barrel 1 and the comparison is made when this spacer is extended. Then, the change in the distance between the lens group 19 and the image sensor 8 is small, and the influence of the extension of the spacer 13b can be suppressed.

Although the distance between the lens group 19 and the image sensor 8 may increase as described above, a spacer made of an elastic body such as a wave spring may be arranged at the end of the lens group 19 on the image capturing side. It is possible to obtain substantially the same effect as that of the first embodiment.

1 Lens barrel 2, 3, 4, 5, 6, 7 Lens 13 Spacer (extendable spacer)
19 lens group 20 lens unit

Claims (4)

A lens group in which a plurality of glass lenses are arranged along the optical axis of the lens,
A lens barrel made of a metal having a reduced diameter portion at which an image-side lens of the lens group comes into contact with the image-side end portion and integrally supporting the lens group,
A pressing member having a locking portion that presses the first lens closest to the object side of the lens group to the image side by being screwed and fastened to the object side end portion of the casing;
A lens unit comprising:
The first lens has an annular recess that is recessed in the optical axis direction on the outer periphery of the object side surface,
An annular elastic body interposed between the first lens and the locking portion of the pressing member is provided in the recess,
The elastic body is provided so as to be compressed in the optical axis direction of the lens, and a gap is not formed between the lenses due to relative movement of the lens barrel and the lens group in the optical axis direction due to temperature change. A lens unit, wherein the lens unit is extendable in the optical axis direction of the lens. The lens unit according to claim 1, wherein the elastic body is a spring. The lens unit according to claim 2, wherein the spring is a wave spring. The lens unit according to any one of claims 1 to 3,
A substrate having an image sensor,
A member for supporting the lens unit in a state of being positioned with respect to the substrate,
An in-vehicle camera comprising:

Images