CN111566534A

CN111566534A - Image pickup apparatus

Info

Publication number: CN111566534A
Application number: CN201880085816.5A
Authority: CN
Inventors: 霍昊扬
Original assignee: Shenzhen Bosen Photoelectric Technology Co ltd
Current assignee: Shenzhen Bosen Photoelectric Technology Co ltd
Priority date: 2018-05-07
Filing date: 2018-05-07
Publication date: 2020-08-21
Also published as: WO2019213812A1; CN117608049A

Abstract

The invention provides an imaging device. The image pickup device can stably maintain the focus position of the lens even if the external pressure changes. The imaging device includes: a lens unit having a plurality of lenses and a lens frame for housing the plurality of lenses; a holder that holds the lens unit; and an imaging element that receives the light flux having passed through the lens, wherein the holder includes: a screw portion by which the lens unit can be moved in the optical axis direction; and at least one fitting portion to which the lens unit is fitted, wherein a central point of an engagement portion of the screw portion is provided on a side closer to the object than an intermediate portion of an optical overall length of the imaging apparatus.

Description

Image pickup apparatus

Technical Field

The invention relates to an imaging device equipped with a lens unit having a plurality of lenses, and provides an imaging device capable of stably maintaining the focal position of the lenses even if the external environment such as external pressure and temperature changes.

Background

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

For example, in the imaging devices described in

patent documents

1, 2, and 3, a male screw formed on the outer periphery of the lens unit and a female screw formed on the inner periphery of the holder are screwed together, and the lens unit is moved in the optical axis direction by rotating the lens unit with respect to the holder, thereby adjusting the focal position of the lens with respect to the imaging surface.

In the imaging device described in patent document 2, the lens unit is fixed to the holder with an adhesive after focus adjustment.

In the imaging device described in patent document 3, a sealing member having elasticity is interposed between the lens unit and the housing in order to improve the water-tightness and airtightness of the inside of the device.

In the imaging device described in patent document 4, a collet is provided between the holder and the lens frame, and the thermal expansion coefficients of the materials are set to have a constant relationship, thereby suppressing the shift of the focal position of the lens during a temperature change.

Documents of the prior art

Patent document 1: japanese patent laid-open 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

Disclosure of Invention

Problems to be solved by the invention

In the imaging devices described in

patent documents

1, 2, and 3, since the lens unit is positioned with respect to the holder only by the screw, a high-precision screw is required to stably maintain the focal position without causing positional deviation in the optical axis direction, inclination of the optical axis, and the like of the lens unit by suppressing looseness between the male screw and the female screw, and there is a concern that a cost increase is caused.

In the imaging device described in patent document 2, after focus adjustment, the lens unit is fixed to the holder by an adhesive, but there is a concern that: when the adhesive itself is deformed or expanded or contracted by a change in external environment such as external pressure or temperature with respect to the lens unit, a positional shift or inclination of the lens unit occurs, and the focal position cannot be stably maintained.

In the imaging device described in patent document 3, there is a concern that: when the lens unit and the housing are misaligned due to a component error, a lateral pressure is applied to the lens unit by an elastic force of the sealing member to tilt the optical axis, and the focal position cannot be stably maintained.

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

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

An object of the present invention is to provide an imaging device capable of stably maintaining a focal position of a lens even when a temperature changes.

An object of the present invention is to provide an imaging device with low cost and high accuracy.

Means for solving the problems

In order to solve the above problem, the present invention provides an imaging apparatus including: a lens unit having a plurality of lenses and a lens frame for housing the plurality of lenses; a holder that holds the lens unit; and an image pickup element that receives the light flux having passed through the lens, the image pickup apparatus being characterized in that the holder includes: a screw portion by which the lens unit can be moved in the optical axis direction; and at least one fitting portion in which the lens unit is fitted, the central point of the engagement portion of the screw portion being provided on the side closer to the object than the intermediate portion of the entire optical length of the image pickup apparatus.

ADVANTAGEOUS EFFECTS OF INVENTION

The image pickup device of the present invention can stably maintain the focal position of the lens even when the external pressure changes.

Drawings

Fig. 1 is a sectional view showing the configuration of an imaging device according to embodiment 1 of the present invention.

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

Fig. 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 the bonding structure according to embodiment 1 of the present invention.

Fig. 6 is a sectional view showing the configuration of an imaging device according to embodiment 2 of the present invention.

Fig. 7 is a sectional view showing the configuration of an imaging device according to embodiment 3 of the present invention.

Fig. 8 is a sectional view showing the configuration of an imaging device according to embodiment 4 of the present invention.

Description of the reference numerals

10. A holder; 11. a circuit board mounting portion; 12. a threaded portion; 13a, a front side fitting part; 13b, a rear-side fitting part; 13c, a central point of the engaging portion; 14. an adhesive portion; 14a, a front end face; 14b, a rear end face; 15. a front end portion; LU, lens unit; 20. a mirror frame; 21. a lens housing section; 21a, L1, and a fitting portion; 22. a light ring section; 23. 23a, 23b, a front side thread portion; 24. a rear side screw thread portion; 25a, a front-side fitting part; 25b, a rear-side fitting part; 26. an adhesive portion; 27. an abutting portion; 30. a front side compression ring; 31. a lens holding section; 32. a threaded portion; 40. 1 st spacer ring; 50. a 2 nd spacer ring; 60. pressing the ring at the back side; 61. a lens pressing section; 62. a threaded portion; 63. a fitting portion; 64. a lens bonding section (fixing member); 70. an urging spring (fixed member); 80. a sealing member; 90. a sealing member; 100. a housing; L1-L8, and 1 st to 8 th lenses; l1a, a side reduced diameter portion; l8a, lens bonding part (fixing member); A. an optical axis; F. an optical filter; s, a solid-state imaging element; s1, protective glass; s2, a camera shooting surface; s3, a circuit board connection part; lh, the length of the holder (the distance between the central point of the engagement portion and the imaging surface); lb, length of frame (distance between center point of engagement portion and 8 th lens); bf. Back focal length (distance between the 8 th lens and the image pickup surface); TL, total optical length.

Detailed Description

Hereinafter, an imaging apparatus embodying the present invention will be described specifically with reference to the drawings.

Fig. 1 is an explanatory diagram showing a configuration of an imaging device according to embodiment 1 of the present invention. As shown in the drawing, the imaging apparatus 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, a CCD, or the like, which receives the light beam having passed through the lens.

The lens unit LU includes: lens L1 to lens L8; an optical filter F; a lens frame 20 having a lens housing section 21 for housing and holding a lens; a front pressure ring 30 for pressing and fixing the lenses L1 to L3 to the frame 20; a rear pressure ring 60 that presses and fixes the lenses L4 to L8 to the frame 20 and has a fitting portion 63 for fitting the optical filter F and holding the optical filter F; and an urging spring 70 having elasticity and urging the lens L4 to the lens L8 toward the image side.

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

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

As shown in fig. 1, a 1 st spacer 40 is provided between the lens L6 and the lens L7, and a 2 nd spacer 50 is provided between the lens L7 and the lens L8.

The holder 10 is held so as to be movable in the optical axis direction by screwing the screw portion 12 to the front screw portion 23b of the lens frame 20, and the circuit board mounting portion 11 of the holder 10 is fixed to a circuit board, not shown, on which the solid-state imaging element S is mounted by a fixing method such as screwing or bonding.

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

The holder 10 further includes a front fitting portion 13a and a rear fitting portion 13b, which are two fitting portions for fitting the lens unit LU so that the lens unit LU can move in the optical axis direction and holding the lens unit LU, the front fitting portion 13a being fitted to the front fitting portion 25a of the frame 20, and the rear fitting portion 13b being fitted to the rear fitting portion 25b of the frame 20. This enables the lens unit LU to be stably held so that the optical axis a of the lens unit LU is perpendicular to the image pickup surface S2.

Further, the screw portion 12 is provided on the object side with respect to the intermediate portion between the front side fitting portion 13a and the rear side fitting portion 13b, the front side screw portion 23b is provided on the object side with respect to the intermediate portion between the front side fitting portion 25a and the rear side fitting portion 25b, and the distance between the two fitting portions of the front side fitting portion 13a and the rear side fitting portion 13b and the distance between the two fitting portions of the front side fitting portion 25a and the rear side fitting portion 25b are equal to or greater than 1/2 of the total length of the lens unit, that is, the engaging portion center point 13c of the screw portion 12 and the front side screw portion 23b is provided on the object side with respect to the intermediate portion of the optical total length TL of the imaging device, and therefore, even when lateral pressure from the outside or the like is applied to the lens unit, inclination of the optical axis such that the focal position of the lens is shifted can be prevented. Here, as shown in fig. 1, the total optical length TL of the imaging device is the distance from the lens end, which is the end of the lens optical system, to the imaging surface S2.

Further, the holder 10 is provided with the adhesive portion 14 that penetrates the side surface of the holder 10 so that the lens frame 20 is exposed to the outside, and by applying the adhesive B to the adhesive portion 14, the lens unit LU can be adhesively fixed to the holder 10 between the front end surface 14a of the adhesive portion 14 and the adhesive portion 26 on the side surface of the lens frame 20, and between the rear end surface 14B of the adhesive portion 14 and the adhesive portion 26 on the side surface of the lens frame 20. As shown in fig. 2, the adhesive portion 14 is provided at 3 points every 120 ° in the circumferential direction of the holder 10. The lens unit LU may be directly bonded by the adhesive portion 14, or another member may be bonded by the adhesive portion 14 and fixed via the other member.

Illustrating the advantages of the bonding method. Conventionally, in an imaging device with a fixed focus, there is a problem that a focus position of a lens is shifted due to a temperature change, and one of the causes is that a lens unit moves due to expansion and contraction of an adhesive.

For example, in patent document 2, the lens unit and the holder are screwed together by a screw, and there is a possibility that the screw is loosened, and the lens unit is moved in the optical axis direction by an amount corresponding to the screw loosening by expansion and contraction of the adhesive due to temperature change, and the focal position is shifted.

According to the bonding method of the present invention, even if the adhesive B expands or contracts due to a temperature change, the lens unit LU is not moved in the optical axis direction and the focal position can be stably maintained because the lens unit LU is restricted by the front end surface 14a and the rear end surface 14B of the bonding portion 14 of the holder 10. Further, although the bonding is characterized by low cost, simplicity, and the like, it is needless to say that the bonding may be performed by screwing by providing a screw from the side surface as in the conventional case.

Further, patent document 4 proposes the following method: the relationship between the lens holder (holder) and the focal distances of the lens barrel (barrel frame), collet, and lens is set as follows,

Lc·CTEc＝Lm·CTEm+Lb·CTEb–Lf·CTEf

wherein, Lc: length of collet, Lm: length of lens holder, Lb: length of lens barrel, Lf: focal length of lens, ctce: thermal expansion coefficient of collet material, CTEm: thermal expansion coefficient of lens holder material, CTEb: thermal expansion coefficient of lens barrel material, CTEf: the rate of change of the temperature of the lens,

this enables the focal position to be maintained even when the temperature changes. That is, the movement of the holder and the frame which expand and contract in the same direction from the imaging surface as a starting point is canceled out by the expansion and contraction of the collet in the opposite direction when the temperature changes.

In contrast, according to the present invention, since the holder 10 and the lens frame 20 are fixed to each other by the screw portion 12, the front screw portion 23b, and the

adhesive portions

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

Lh·CTEh＝Lb·CTEb–bf·CTEf

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

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

This makes it possible to maintain the focal position even when the temperature changes, and therefore, a collet is not required, and the cost can be reduced.

Here, as shown in fig. 1 and 6, the holder length Lh is a distance from the center point 13c of the engagement portion between the screw portion 12 of the holder 10 and the front screw portion 23b of the lens frame 20 to the imaging surface S2, and the lens frame length Lb is a distance from the center point 13c of the engagement portion between the screw portion 12 of the holder 10 and the front screw portion 23b of the lens frame 20 to the rear surface of the 8 th lens L8. The back focal length bf is a distance from the back surface of the 8 th lens L8 to the image pickup surface S2.

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

Fig. 7 is an explanatory diagram 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 fitting portion 13a and the front fitting portion 25 a.

In embodiment 2, as in embodiment 1, since the engagement portion center point 13c between the screw portion 12 and the front screw portion 23b is provided on the object side of the intermediate portion of the total optical length TL of the imaging apparatus, as in embodiment 1, the accuracy of the optical axis is slightly inferior to that in embodiment 1, but even when lateral pressure or the like from the outside is applied to the lens unit, as in embodiment 1, it is possible to prevent the optical axis from being inclined such that the focal position of the lens is shifted.

Further, in the present invention, since the urging spring 70 having elasticity and urging the lenses L4 to L8 toward the image side is provided, even if a gap is generated due to a difference in thermal expansion coefficient between the frame 20 and the lenses L4 to L8 at the time of a temperature change, the backlash between the lenses due to the gap can be prevented, and the 8 th lens L8 can be secured at a position close to the sensor, so that the back focal length bf can be stably maintained.

Also, the elastic member is provided between the 6 th lens L6 and the 7 th lens L7 or between the 7 th lens L7 and the 8 th lens L8, and similarly, it is possible to prevent the occurrence of backlash between the lenses due to a gap generated by a difference in thermal expansion coefficient, and to stably maintain the back focal length bf.

As shown in fig. 5, the rear pressure ring 60 and the 8 th lens L8 are fixed by bonding with the lens bonding portions L8a and 64, and thus lens looseness due to thermal expansion cannot be prevented, but the 8 th lens L8 can be always kept close to the sensor, and the back focal length bf can be stably maintained. The frame 20 and the 8 th lens L8 may be bonded and fixed to each other.

Next, another advantage of the bonding method will be described with reference to fig. 8. Fig. 8 is an explanatory view showing a configuration of an imaging device according to embodiment 4 of the present invention, which is a modification of the imaging device according to embodiment 1 of the present invention described above, and is an example of an imaging device having a waterproof structure. The portions common to the imaging apparatus according to embodiment 1 of the present invention are not described.

The lens unit LU includes a sealing member 80 having elasticity and compressed in the radial direction (in the direction perpendicular to the optical axis) between the side surface reduced diameter portion L1a of the 1 st lens L1 and the L1 fitting portion 21a of the frame 20, thereby ensuring waterproofness in the lens housing portion 21 of the frame 20.

The imaging device further includes a sealing member 90 having elasticity that is compressed only in the optical axis direction between the front end portion 15 of the holder 10 and the housing 100, thereby ensuring the waterproofness of the peripheral portion of the imaging device.

Here, in the conventional example, the position of the lens unit adhesion fixing portion located at the holder distal end portion is located at the adhesion portion 14 which is a through hole facing the lens unit LU from the side surface of the holder 10, and therefore, the sealing member 90 does not interfere with the adhesive B, and waterproofness can be ensured.

In addition, according to this waterproof structure, even when the lens unit LU and the housing 100 are misaligned 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, and therefore the focal position of the lens can be stably maintained.

Claims

An imaging device includes: a lens unit having a plurality of lenses and a lens frame for housing the plurality of lenses; a holder that holds the lens unit; and an image pickup element that receives the light beam having passed through the lens,

the image pickup apparatus is characterized in that,

the holder includes:

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

at least one fitting portion in which the lens unit is fitted,

the center point of the engagement portion of the screw portion is provided on the object side of the intermediate portion of the entire optical length of the imaging device.
The image pickup apparatus according to claim 1,

the holder includes two fitting portions to which the lens units are fitted.
The image pickup apparatus according to claim 2,

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

the holder includes an adhesive portion by which the lens unit is fixed,

the holder is provided with a hole penetrating through the side surface of the holder from the side surface of the holder toward the lens unit,

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

the two fitting portions are provided at intervals of 1/2 or more of the total length of the lens unit.
The image pickup apparatus according to claim 1,

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

the holding piece, the lens frame and the back focal length of the lens satisfy the following relation,

Lh·CTEh＝Lb·CTEb–bf·CTEf

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

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

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

the fixing member is an elastic member that presses the lens closest to the image pickup surface in the direction toward the image pickup surface.