JP3862556B2 - Camera lens holding mechanism using solid-state image sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens holding mechanism of a camera using a solid-state image sensor.
[0002]
[Prior art]
A camera using a solid-state image sensor is used for in-vehicle use or industrial use under a greatly changing ambient environment temperature or vibration environment.
This type of camera has a structure in which a lens is attached to a lens holder and the focus is adjusted. The lens is generally fixed to the lens holder with a set screw having a pointed tip from the direction perpendicular to the lens optical axis.
In such a case, all members configured to fix the lens such as the lens barrel, lens holder, and set screw must have the same coefficient of thermal expansion, and the lens can be fixed by thermal expansion of the member against changes in the surrounding environment. When the regulation force is weakened and the screw is loosened due to vibration or creep, the focus will be shifted in the worst case. Further, when a set screw is used for fixing the lens, a mark of pressing the screw at the time of initial adjustment remains on the lens frame, and it becomes difficult to make fine adjustment again.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a lens holding mechanism for a camera using a solid-state imaging device that does not cause a focus shift due to environmental changes such as temperature fluctuations and vibrations.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the lens holding mechanism of the camera using the solid-state imaging device according to the present invention has a focus position in the optical axis direction by screwing and fixing the lens frame to the lens coupling cylindrical portion of the lens holding member. In the camera having a structure in which the lens barrel is fixed to the lens holding member by adjusting the lens barrel, a vertical knurled portion is formed in the optical axis direction on the outer circumferential surface of the lens barrel and rotated on the outer circumferential surface of the lens coupling cylindrical portion A blocking portion is provided, and includes a lens fixing member having a knurling engagement groove having a shape complementary to the knurling portion, and a rotation blocking engagement portion having a shape complementary to the rotation blocking portion, and rotates to the rotation blocking portion. The lens locking member is fitted to the lens coupling cylindrical portion while the rotation blocking portion prevents the rotation of the lens fixing member by engaging the blocking engagement portion, and the lens is focused. After location adjustment, the tip of the lens fixing member is moved in the optical axis direction to fix the lens by Rukoto engaged the knurled engagement grooves in the knurled portion further screwed to the lens fixing member bis and it is configured to secure the fixing of the lens by fixing the lens fixing member is pressed against the outer circumferential surface of the lens coupling cylinder portion in the optical axis direction.
Moreover, the said rotation prevention engagement part in this invention is a long groove provided in the optical axis direction, and the said rotation prevention part is comprised by the long plate shape fitted to the said long groove.
Furthermore, the knurled portion in the present invention is configured to be provided at substantially the center in the optical axis direction of the lens barrel.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1A and 1B are views showing the appearance of a camera to which a lens holding mechanism according to the present invention is applied. FIG. 1A is a front view, FIG. 1B is a side view, and FIG. FIG. 2 is an external perspective view of a camera to which the lens holding mechanism according to the present invention is applied.
This figure shows a state before the lens position is fixed by a lens retainer which is an intermediate member for fixing the lens. A screw thread (not shown) provided on the outer periphery of the lens barrel 10 is inserted in mesh with a screw portion of the lens coupling cylindrical portion 8 (see FIG. 3) of the lens holder 4, and set to a predetermined focus position. The A vertical knurled portion 3 is provided in the optical axis direction substantially at the center of the lens barrel 10.
The lens retainer 2 is fitted to the lens coupling cylindrical portion 8. The fixing screw hole 4a is for attaching to a housing (for example, a vehicle body) (not shown), and the positioning pin 4b is for determining a position when the housing is attached.
[0006]
3A and 3B are exploded views of the camera using the image pickup device according to the present invention, in which FIG. 3A is a perspective view from an oblique front, and FIG. 3B is a perspective view from an oblique rear.
The lens holder 4 is a rectangular plate and has a structure in which an upright portion 4c is continuously provided around the lens holder 4. Fixing screw holes 4a and positioning pins 4b are arranged at the four corners of the lens holder 4, and a lens coupling cylindrical portion 8 having an internal thread on the inner wall of the cylindrical portion is provided at the center thereof. On the outer periphery of the lens coupling cylindrical portion 8, rotation preventing portions 8 a are provided at two locations, upper and lower.
On the other hand, the lens barrel 10 incorporating the lens 1 is provided with a male screw (not shown) at the rear end circumferential portion, and the knurled portion 3 is provided at the center portion as described above.
[0007]
The cylindrical lens retainer 2 for fixing between the lens barrel 10 and the lens coupling cylindrical portion 8 is provided with knurling engagement grooves 2a at three positions on the inner wall at intervals of 120 °. The inner wall is provided with two rotation prevention grooves 2c.
A printed circuit board 5 having an image pickup device 6 mounted on one surface and a DSP 7 mounted on the other surface is attached to the rear surface side of the lens holder 4 by screws.
[0008]
4A and 4B are diagrams for explaining a camera focus adjustment method using an image sensor according to the present invention, in which FIG. 4A shows a state before focus adjustment, and FIG. 4B shows a state after focus adjustment. .
In FIG. 3, the lens retainer 2 is fitted to the lens coupling cylindrical portion 8 while engaging the rotation prevention groove 2c with the rotation prevention portion 8a.
By inserting and rotating the lens barrel 10 into the lens coupling cylindrical portion 8, the outer peripheral portion of the lens barrel 10 and the inner wall portion of the lens coupling cylindrical portion 8 are screwed together. By adjusting the amount of rotation, the lens barrel 10 can be moved back and forth in the optical axis direction to adjust the focus position. (A) shows this state.
[0009]
When the focus adjustment is completed, the lens retainer 2 is slid in the direction of the arrow 10 from the state (a) to engage the knurling engagement groove 2 a with the knurling portion 3. FIG. 5 shows a state of engagement between the knurling portion of the lens barrel and the knurling engagement groove of the lens retainer. Thereafter, the screw 9 is passed through the screw hole 2b of the lens retainer 2, and screwed into the screw portion 8b of the rotation preventing portion 8a to be fixed. As a result, the lens barrel 10 is fixed to the lens holder 4. (B) shows this state.
When fixing the lens, it is desirable that the crest of the lens and the trough of the lens retainer mesh with each other as they are. The valley may not fit.
In the present invention, the knurl pitch of the lens is set so that the amount of focus movement due to the fine adjustment amount of rotation of the lens is sufficiently smaller than the depth of focus of the lens optical system and does not affect the resolution obtained. In other words, the knurled mountain has a sufficiently small focal shift amount for one pitch rotation with respect to the focal depth of the lens. Therefore, although the maximum rotation fine adjustment amount moves 1/2 mountain, even if the lens barrel is finely adjusted and fixed to the position where the lens retainer mountain meshes, the resolution is hardly affected and can be ignored.
[0011]
According to the present invention, even if the screw for fixing the lens retainer to the lens holder is loosened, no defocusing occurs unless the screw is completely removed from the lens retainer. Further, readjustment after fixing the lens once in the adjustment step is easy. Further, the lens is fixed by restricting the rotation of the lens retainer in the circumferential direction with respect to the lens holder.
[0012]
【The invention's effect】
As described above, the present invention provides a camera having a structure in which a lens barrel is screwed and fixed to a lens coupling cylindrical portion of a lens holding member to adjust a focus position in the optical axis direction and attach a lens. It is not fixed directly to the lens holder that is the holding member, but is fixed to the lens holder via the lens retainer that is an intermediate member for fixing the lens. A highly reliable camera can be provided.
That is, since a screw is not directly used for fixing the lens, a focus shift caused by thermal expansion of the lens fixing member does not occur even when the environmental temperature changes. Similarly, there is no occurrence of focus shift caused by loosening of the set screw due to the vibration environment. Since the fixing screw does not hold the position with the set screw, there is an effect that it is easy to readjust the focus without leaving any trace of pressing of the screw.
[Brief description of the drawings]
FIGS. 1A and 1B are views showing the appearance of a camera to which a lens holding mechanism according to the present invention is applied, wherein FIG. 1A is a front view, FIG. 1B is a side view, and FIG.
FIG. 2 is an external perspective view of a camera to which a lens holding mechanism according to the present invention is applied.
FIGS. 3A and 3B are exploded views of a camera using an image sensor according to the present invention, in which FIG. 3A is a perspective view from an oblique front, and FIG. 3B is a perspective view from an oblique rear;
4A and 4B are diagrams for explaining a camera focus adjustment method using an image sensor according to the present invention, in which FIG. 4A shows a state before focus adjustment, and FIG. 4B shows a state after focus adjustment; .
FIG. 5 is a view for explaining engagement between a knurled portion of a lens and a lens retainer.
[Explanation of symbols]
1 Lens 2 Lens retainer (Lens fixing member)
3 Knurled part 4 Lens holder (Lens holding member)
5 Printed Circuit Board 6 Image Sensor 7 Digital Signal Processor (DSP)
8 Lens coupling cylindrical part 9 Screw (screw)
10 Lens frame

Claims (3)

In the camera having a structure in which the lens barrel is fixed to the lens holding member by adjusting the focus position in the optical axis direction by screwing and fixing the lens barrel to the lens coupling cylindrical portion of the lens holding member .
Forming a vertical knurled portion in the optical axis direction on the outer peripheral surface of the lens barrel and providing a rotation blocking portion on the outer peripheral surface of the lens coupling cylindrical portion;
A knurled groove having a shape complementary to the knurled portion, and a lens fixing member having a rotation blocking engaging portion complementary to the rotation blocking portion,
The lens fixing member is fitted to the lens coupling cylindrical portion while preventing the rotation of the lens fixing member by engaging the rotation prevention engaging portion with the rotation prevention portion.
After focus position adjustment of the lens, the lens fixing member is moved in the optical axis direction to fix the lens by Rukoto engaged the knurled engagement grooves in the knurled portion,
Further , the solid-state imaging is characterized in that the fixing of the lens is secured by pressing the tip of the screw screwed to the lens fixing member against the outer peripheral surface of the lens coupling cylindrical portion to fix the lens fixing member in the optical axis direction. Lens holding mechanism of camera using element.   The solid-state image pickup device according to claim 1, wherein the rotation prevention engagement portion is a long groove provided in an optical axis direction, and the rotation prevention portion has a long plate shape that fits into the long groove. The lens holding mechanism of the camera. The lens holding mechanism of the camera using the solid-state imaging device according to claim 1, wherein the knurled portion is provided at a substantially center of the lens barrel in the optical axis direction.

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