WO2019213812A1

WO2019213812A1 - Image capture device

Info

Publication number: WO2019213812A1
Application number: PCT/CN2018/085868
Authority: WO
Inventors: 霍昊扬
Original assignee: 深圳市伯森光电科技有限公司
Priority date: 2018-05-07
Filing date: 2018-05-07
Publication date: 2019-11-14
Also published as: CN111566534A; CN117608049A

Abstract

Provided by the present invention is an image capture device. The image capture device is capable of stably maintaining the focal position of a lens even when external pressure changes. The image capture device comprises: a lens unit, which is provided with multiple lenses and a frame for accommodating the multiple lenses; a retainer, which retains the lens unit; an image capture element, which receives light beams that pass through the lenses, wherein, in the image capture device, the retainer comprises: a thread part, wherein the thread part may be used to cause the lens unit to move along the optical axis direction; at least one fitting part, the lens unit fitting into the at least one fitting part, and the central point of a meshing part of the thread part being provided at a side closer to a captured object than a middle part of the optical full length of the image capture device.

Description

Camera

Technical field

The present invention relates to an image pickup apparatus in which a lens unit having a plurality of lenses is mounted, and provides an image pickup apparatus capable of stably maintaining a focus position of a lens even if an external environment such as external pressure or temperature changes.

Background technique

As an imaging device used for an in-vehicle camera, a surveillance camera, or the like, an imaging device in which a small and low-cost lens unit called a pan focus type fixed focus is mounted is often used.

For example, in the imaging device described in Patent Document 1, Patent Document 2, and Patent Document 3, the external thread formed on the outer circumference of the lens unit and the internal thread formed on the inner circumference of the holder are screwed to each other. The unit is moved relative to the holder to move the lens unit in the optical axis direction, thereby adjusting the focus position of the lens with respect to the imaging surface.

In the imaging device described in Patent Document 2, after the focus adjustment, the lens unit is fixed to the holder by an adhesive.

In the imaging device described in Patent Document 3, in order to improve water repellency and airtightness inside the device, a sealing member having elasticity is interposed between the lens unit and the casing.

Further, in the imaging device described in Patent Document 4, the focus position of the lens at the time of temperature change is suppressed by providing a collet between the holder and the frame and maintaining a constant thermal expansion coefficient of each material. Offset.

Prior art literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-191423

Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-186756

Patent Document 3: Japanese Laid-Open Patent Publication No. 2010-78772

Patent Document 4: US 9594228 Patent Specification

Summary of the invention

Problems to be solved by the invention

In the image pickup apparatuses described in Patent Document 1, Patent Document 2, and Patent Document 3, the lens unit is positioned only by the screw with respect to the holder, and therefore, in order to suppress the looseness between the external thread and the internal thread, the lens unit is not generated. In the case of a positional shift in the optical axis direction, an inclination of the optical axis, or the like, the focus position is stably maintained, and a high-precision screw is required, which may cause an increase in cost.

In the imaging device described in Patent Document 2, after the focus adjustment, the lens unit is fixed to the holder by the adhesive, but there is a concern that the external environment changes due to external pressure and temperature with respect to the lens unit. When the adhesive itself is deformed and stretched, the positional deviation and tilt of the lens unit occur, and the focus position cannot be stably maintained.

In the imaging device described in Patent Document 3, when the lens unit and the outer casing are displaced due to a component error, the side pressure is applied to the lens unit by the elastic force of the sealing member. The optical axis is tilted, so that the focus position cannot be stably maintained.

In the imaging device described in Patent Document 4, a collet (cylinder jig) is required between the holder and the lens frame, and there is a concern that the number of components increases and the cost increases.

The present invention has been made in view of such circumstances, and an object thereof is to provide an image pickup apparatus capable of stably maintaining a focus position of a lens even if an external pressure changes.

An object of the present invention is to provide an image pickup apparatus capable of stably maintaining a focus position of a lens even if temperature changes.

One of the objects of the present invention is to provide an image pickup apparatus which is low in cost and high in precision.

Solution to solve the problem

In order to solve the above problems, the present invention provides an image pickup apparatus including: a lens unit having a plurality of lenses and a lens frame accommodating the plurality of lenses; a holder that holds the lens unit; and an image pickup element that receives the lens after passing through the lens The light beam, the image pickup device is characterized in that the holder includes: a threaded portion through which the lens unit can be moved in the optical axis direction; and at least one fitting portion, the lens unit is fitted to the at least one fitting portion, The center point of the meshing portion of the screw portion is provided on the side closer to the subject than the intermediate portion of the optical full length of the imaging device.

Effect of the invention

According to the image pickup apparatus of the present invention, the focus position of the lens can be stably maintained even if the external pressure changes.

DRAWINGS

FIG. 1 is a cross-sectional view showing a configuration of an imaging device according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a configuration of an imaging device according to Embodiment 1 of the present invention.

3 is a front view of the elastic member according to Embodiment 1 of the present invention.

Fig. 4 is a side view of the elastic member according to Embodiment 1 of the present invention.

FIG. 5 is an explanatory view of a bonding structure according to Embodiment 1 of the present invention.

FIG. 6 is a cross-sectional view showing a configuration of an imaging device according to Embodiment 2 of the present invention.

FIG. 7 is a cross-sectional view showing a configuration of an imaging device according to Embodiment 3 of the present invention.

FIG. 8 is a cross-sectional view showing a configuration of an imaging device according to Embodiment 4 of the present invention.

Description of the reference numerals

10, holding member; 11, circuit board mounting portion; 12, threaded portion; 13a, front side fitting portion; 13b, rear side fitting portion; 13c, centering point of the engaging portion; 14, bonding portion; 14a, front end surface 14b, rear end face; 15, front end portion; LU, lens unit; 20, frame; 21, lens housing portion; 21a, L1, fitting portion; 22, diaphragm portion; 23, 23a, 23b, front thread portion; 24, a rear threaded portion; 25a, a front side fitting portion; 25b, a rear side fitting portion; 26, a bonding portion; 27, an abutting portion; 30, a front side pressure ring; 31, a lens holding portion; Threaded portion 40; first spacer ring; 50, second spacer ring; 60, rear side pressure ring; 61, lens pressing portion; 62, thread portion; 63, fitting portion; 64, lens bonding portion (fixing member) 70; force spring (fixed part); 80, sealing member; 90, sealing member; 100, outer casing; L1 ~ L8, first lens - eighth lens; L1a, side reduced diameter portion; L8a, lens bonding Part (fixed part); A, optical axis; F, optical filter; S, solid-state imaging element; S1, protective glass; S2, imaging surface; S3, circuit board connection part; Lh, length of holder ( The distance between the center point of the joint and the imaging surface); Lb, the length of the frame (the distance between the center point of the meshing portion and the eighth lens); bf, the back focus (the distance between the eighth lens and the imaging surface); TL, optical full length.

detailed description

Hereinafter, an image pickup apparatus embodying the present invention will be specifically described based on the drawings.

FIG. 1 is an explanatory view showing a configuration of an imaging device according to Embodiment 1 of the present invention. As shown in the figure, the imaging device includes a lens unit LU, a holder 10 that holds the lens unit LU, and a solid-state imaging element S such as a CMOS or a CCD that receives a light beam that has passed through the lens.

The lens unit LU includes a lens L1 to a lens L8, an optical filter F, a lens frame 20 having a lens housing portion 21 that houses and holds the lens, and a front side pressure ring 30 that presses and fixes the lens L1 to the lens L3 to the lens frame 20. a rear side pressure ring 60 that presses and fixes the lens L4 to the lens L8 to the lens frame 20, and has a fitting portion 63 that is fitted with the optical filter F to hold the optical filter F; and a biasing spring 70 having The elasticity is applied to the lens L4 to the lens L8 toward the image side.

The threaded portion 32 of the front side pressure ring 30 is threadedly engaged with the front side threaded portion 23a of the frame 20, and the threaded portion 62 of the rear side pressure ring 60 is threadedly engaged with the rear side threaded portion 24 of the frame 20. The rear side pressure ring 60 is provided with a lens pressing portion 61 that presses the lens 8.

As shown in FIGS. 3 and 4, the biasing spring 70 is a wave washer-shaped leaf spring which is compressed in the thickness direction between the abutting portion 27 of the lens frame 20 and the abutting portion L51 of the lens L5. The spring 70 biases the lens L4 to the lens L8 toward the image side.

Further, as shown in FIG. 1, a first spacer ring 40 is provided between the lens L6 and the lens L7, and a second spacer ring 50 is provided between the lens L7 and the lens L8.

With the holder 10, the screw unit 12 is screwed into the front side screw portion 23b of the lens frame 20, thereby keeping the lens unit LU movable in the optical axis direction, and the circuit board mounting portion 11 of the holder 10 is screwed. A fixing method such as bonding or the like is fixed to a circuit board (not shown) on which the solid-state image sensor S is mounted.

The solid-state imaging device S has a cover glass S1 and an imaging surface S2, and the circuit board connection portion S3 of the solid-state image sensor S is electrically connected to a circuit board (not shown).

The holder 10 further includes two fitting portions, that is, a front fitting portion 13a and a rear fitting portion 13b, which are fitted to the lens unit LU so that the lens unit LU can be moved in the optical axis direction, and the lens unit LU is held. The front side fitting portion 13a is fitted to the front side fitting portion 25a of the mirror frame 20, and the rear side fitting portion 13b is fitted to the rear side fitting portion 25b of the frame 20. Thereby, the lens unit LU can be stably held such that the optical axis A of the lens unit LU is perpendicular to the imaging surface S2.

Further, the screw portion 12 is provided on the side closer to the subject than the intermediate portion between the front side fitting portion 13a and the rear side fitting portion 13b, and the front side screw portion 23b is provided on the front side fitting portion 25a and rear. The intermediate portion between the side fitting portions 25b is located on the side of the subject, and the distance between the two fitting portions of the front side fitting portion 13a and the rear side fitting portion 13b and the front side fitting portion 25a The distance between the two fitting portions of the rear side fitting portion 25b is 1/2 or more of the total length of the lens unit, that is, the center point 13c of the meshing portion of the screw portion 12 and the front thread portion 23b is set to be larger than that of the imaging device. Since the intermediate portion of the optical full length TL is on the side of the subject, even when a lateral pressure or the like from the outside is applied to the lens unit, it is possible to prevent the tilt of the optical axis such that the focal position of the lens is shifted. Here, as shown in FIG. 1, the optical total length TL of the imaging device is the distance from the tip end of the lens optical system, that is, the lens tip end to the imaging surface S2.

Further, the holder 10 is provided with an adhesive portion 14 that penetrates the side surface of the holder 10 so that the lens frame 20 is exposed to the outside, and the adhesive portion B is applied to the bonding portion 14, so that the bonding portion 14 can be applied to the bonding portion 14. The lens unit LU is bonded and fixed to the holder 10 between the front end surface 14a and the bonding portion 26 on the side surface of the mirror frame 20, and between the rear end surface 14b of the bonding portion 14 and the bonding portion 26 on the side surface of the lens frame 20. Moreover, as shown in FIG. 2, the adhesion part 14 is provided in three places every 120 degrees in the circumferential direction of the holder 10. Further, the lens unit LU may be directly bonded by the bonding portion 14, or the other member may be bonded by the bonding portion 14, and the lens unit LU may be fixed via the other member.

The advantages of this bonding method are explained. Conventionally, in an image pickup apparatus with a fixed focus, there is a problem that the focus position of the lens shifts due to a temperature change, and the movement of the lens unit due to expansion or contraction of the adhesive is one of the causes.

For example, in Patent Document 2, the lens unit and the holder are screwed by threads, and there is a possibility that the thread is loose, and the expansion and contraction of the adhesive due to the temperature change may cause the lens unit to move in the optical axis direction and the thread is loose. A corresponding amount, resulting in a shift in focus position.

According to the bonding method of the present invention, even if the temperature changes to cause the adhesive B to expand and contract, the lens unit LU does not follow the optical axis due to the restriction of the front end face 14a and the rear end face 14b of the bonding portion 14 of the holder 10. The direction moves, and the focus position can be stably maintained. Further, the bonding has the characteristics of low cost, simpleness, and the like. However, it is needless to say that the fixing can be performed by screwing from the side surface by using a screw or the like as in the related art.

Further, Patent Document 4 proposes a method of setting a relationship between a lens holder (holder) and a focal length of a lens barrel (frame), a collet, and a lens as follows, that is,

Lc·CTEc=Lm·CTEm+Lb·CTEb–Lf·CTEf

Among them, Lc: length of collet, Lm: length of lens holder, Lb: length of lens barrel, Lf: focal length of lens, CTEc: thermal expansion rate of collet material, CTEm: thermal expansion rate of lens holder material, CTEb : thermal expansion rate of lens barrel material, CTEf: temperature change rate of lens,

Thereby, the focus position can be maintained even when the temperature changes. In other words, it is a method of canceling the movement of the holder and the frame which expand and contract in the same direction from the imaging surface by the expansion and contraction in the opposite direction of the collet when the temperature changes.

On the other hand, according to the present invention, the holder 10 and the frame 20 are fixed to each other by the screw portion 12 and the front screw portion 23b and the

bonding portions

14 and 26 on the side closer to the subject than the intermediate portion of the lens unit LU. Therefore, when the temperature changes, the holder 10 and the frame 20 expand and contract in the opposite direction with the imaging surface S2 as a starting point. Therefore, in the present invention, the relationship between the holder 10 and the frame 20 and the back focus of the lens is set as follows.

Lh·CTEh=Lb·CTEb–bf·CTEf

Among them, Lh: length of the holder, Lb: length of the frame, bf: back focal length, CTEh: thermal expansion rate of the material of the holder, CTEb: thermal expansion rate of the frame material, CTFf: temperature change rate of the lens,

The CTFf is determined by the overall characteristics of the optical system including the optical full length TL.

Thereby, since the focus position can be maintained even when the temperature changes, the collet is not required, and the cost can be suppressed.

Here, as shown in FIG. 1 and FIG. 6, the length Lh of the holder is from the center point 13c of the meshing portion between the screw portion 12 of the holder 10 and the front thread portion 23b of the lens frame 20 to the imaging surface S2. The distance Lb of the frame is the distance from the center point 13c of the meshing portion between the screw portion 12 of the holder 10 and the front thread portion 23b of the lens frame 20 to the rear surface of the eighth lens L8. Further, the back focal length bf is a distance from the rear surface of the eighth lens L8 to the imaging surface S2.

In addition, FIG. 6 is an explanatory view showing a configuration of an imaging device according to Embodiment 2 of the present invention, in which a screw portion 12 is provided between the front side fitting portion 13a and the rear side fitting portion 13b, and the front side fitting portion is provided. A modification of the imaging device according to Embodiment 1 of the present invention in which the screw portion 23 is provided between the 25a and the rear side fitting portion 25b.

In addition, FIG. 7 is an explanatory view showing a configuration of an imaging device according to Embodiment 3 of the present invention, and is a modification of the imaging device according to Embodiment 1 of the present invention, which does not include the front side fitting portion 13a and the front side fitting portion 25a. example.

In the second embodiment, as in the first embodiment, the meshing portion center point 13c of the screw portion 12 and the front screw portion 23b is provided on the side closer to the subject than the intermediate portion of the optical full length TL of the imaging device. In the same manner as in the first embodiment, even when a side pressure or the like from the outside is applied to the lens unit, light can be prevented from shifting the focus position of the lens. The tilt of the shaft.

Further, in the present invention, since the biasing spring 70 having elasticity and biasing the lens L4 to the lens L8 toward the image side is provided, even when the temperature changes, even the thermal expansion between the lens frame 20 and the lens L4 to the lens L8 is caused. It is also possible to prevent the gap from being loosened between the lenses due to the difference in the rate, and it is possible to ensure that the eighth lens L8 is located closer to the sensor, and the back focus bf can be stably maintained.

Further, the elastic member is provided between the sixth lens L6 and the seventh lens L7 or between the seventh lens L7 and the eighth lens L8, and similarly, it is possible to prevent looseness between the lenses due to a gap caused by a difference in thermal expansion coefficient. The back focus bf is stably maintained.

Further, as shown in FIG. 5, the rear side pressure ring 60 and the eighth lens L8 are bonded and fixed by the lens bonding portions L8a and 64, and thus the lens looseness due to thermal expansion cannot be prevented, but the eighth lens can be secured. L8 is always in a position closer to the sensor, whereby the back focus bf can also be stably maintained. Further, the bonding and fixing may be performed between the frame 20 and the eighth lens L8.

Next, another advantage of the bonding method will be described using FIG. FIG. 8 is an explanatory view showing a configuration of an imaging device according to Embodiment 4 of the present invention, and is an example of an imaging device having a waterproof structure according to a modification of the imaging device according to Embodiment 1 of the present invention. The description of the portions common to the imaging device according to the first embodiment of the present invention will be omitted.

The lens unit LU includes an elastic sealing member 80 that is compressed in the radial direction (in a direction perpendicular to the optical axis) between the side reduced diameter portion L1a of the first lens L1 and the L1 fitting portion 21a of the lens frame 20, Thereby, the waterproofness in the lens housing portion 21 of the lens frame 20 is ensured.

The image pickup apparatus further includes an elastic sealing member 90 that is compressed only in the optical axis direction between the front end portion 15 of the holder 10 and the outer casing 100, thereby ensuring waterproofness of the peripheral portion of the image pickup device.

Here, in the conventional example, the position of the lens unit adhesion fixing portion located at the tip end portion of the holder is the bonding portion 14 which is a through hole that faces the lens unit LU from the side surface of the holder 10 in the present invention, and therefore, the sealing member 90 It does not interfere with the adhesive B and ensures water repellency.

Further, according to the waterproof structure, even when a misalignment occurs between the lens unit LU and the outer casing 100 due to a component error, the side pressure is not applied to the lens unit LU by the elastic force of the sealing member 90. Therefore, the focus position of the lens can be stably maintained.

Claims

An image pickup apparatus comprising: a lens unit having a plurality of lenses and a lens frame accommodating the plurality of lenses; a holder that holds the lens unit; and an image pickup element that receives a light beam that passes through the lens,

The camera device is characterized in that

The holder includes:

a threaded portion by which the lens unit can be moved in the optical axis direction;

At least one fitting portion, the lens unit is fitted to the at least one fitting portion,

The center point of the meshing portion of the screw portion is provided on the side closer to the subject than the intermediate portion of the optical full length of the imaging device.
The image pickup apparatus according to claim 1, wherein

The holder includes two fitting portions, and the lens unit is fitted to the two fitting portions.
The image pickup apparatus according to claim 2, wherein

The threaded portion is provided at a distal end portion of the holder that is closest to the object side.
The image pickup apparatus according to claim 1, wherein

The holder includes an adhesive portion, and the lens unit is fixed by the bonding portion,

Providing, in the holder, a hole penetrating from a side surface of the holder toward a side of the lens unit through the holder;

The bonding portion is configured to be bonded and fixed between the hole and a side surface of the lens unit.
The image pickup apparatus according to claim 2, wherein

The two fitting portions are provided to be spaced apart from each other by an interval of 1/2 or more of the entire length of the lens unit.
The image pickup apparatus according to claim 1, wherein

The material of the holder is a material having a coefficient of thermal expansion that is smaller than a thermal expansion coefficient of the material of the frame.
The image pickup apparatus according to claim 6, wherein

The following relationship is satisfied between the holder and the back frame of the lens frame and the lens,

Lh·CTEh=Lb·CTEb–bf·CTEf

Wherein, Lh: length of the holder, Lb: length of the frame, bf: back focal length, CTEh: thermal expansion rate of the material of the holder, CTEb: thermal expansion coefficient of the material of the frame, CTFf: temperature change rate of the lens.
The image pickup apparatus according to claim 1, wherein

The lens unit has a fixing member that fixes a position of a lens closest to the imaging surface with respect to the frame toward the direction of the imaging element.
The image pickup apparatus according to claim 8, wherein

The fixing member bonds the lens closest to the imaging surface to the frame, or bonds the lens closest to the imaging surface to the pressure ring.
The image pickup apparatus according to claim 8, wherein

The fixing member is an elastic member that presses a lens closest to the imaging surface in a direction toward the imaging surface.