JP2008051580A - Optical axis adjustment method for stereo camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical axis adjustment method of a stereo camera capable of allowing the optical axis position of a lens to coincide readily with the center position of an imaging element. <P>SOLUTION: A reference lens-barrel 13 having a lens 13A, used as a reference, is inserted into either of two holes 12a, 12b used as a reference formed on a stereo camera body 12. Then, a spot light is emitted from a spot light source 11, arranged on the optical axis of the lens 13A used as the reference, and the locus of the spot light source 11 is fixed at a single point. Thereafter, the first lens-barrel having a lens is inserted into the hole 12a, in place of the lens-barrel 13, and the position of the first lens-barrel is adjusted so that the optical axis of the lens coincides with the position of the optical axis of the lens 13A. Then, the position of the second lens-barrel is adjusted so that the optical axis of a lens of the second lens-barrel, inserted into the hole 12b, coincides with the position of the optical axis of the lens 13A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical axis adjustment method for a stereo camera.

Conventionally, a stereo camera device having a pair of lenses and a pair of imaging elements (CCD, CMOS sensor, etc.) corresponding to the pair of lenses is known. An image shift amount is detected based on image signals of the left and right imaging elements, and the shape of the object to be measured and the distance to the object to be measured are measured.
JP-A-5-157557

  By the way, in a stereo camera device, lenses such as a wide-angle lens and a fish-eye lens are usually used in order to take a wide field of view.

  However, it is very difficult to match the optical axis position of the lens with the center position of an image sensor such as a CCD or CMOS. The deviation between the optical axis position of the lens and the center position of the image sensor becomes a measurement error when measuring the shape of the object to be measured and the distance to the object to be measured.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a method of adjusting the optical axis of a stereo camera that can easily match the optical axis position of a lens with the center position of an image sensor. .

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a first step of inserting a lens barrel having a reference lens into one of two holes formed in the stereo camera body, and after the first step, Spot light is emitted from a spot light source arranged on the optical axis of the reference lens, the position of the lens barrel is determined so that the image of the spot light source becomes a point, and the spot light source image in the state of the point is obtained. After the second step of recording and after the second step, a first lens barrel having a first lens is inserted into one of the two holes instead of the lens barrel, and an image of the spot light source is displayed on the display means. A third step of adjusting the position of the first barrel so that the spot light source image matches the position of the spot light source image recorded in the second step, and after the third step, A second lens is provided instead of the first lens barrel. Two lens barrels are arranged on the optical axis, and the spot light source image is displayed on the display means so that the spot light source image coincides with the position of the spot light source image recorded in the second step. And a fourth step of adjusting the position of the second lens barrel.

  According to the present invention, the optical axis position of the lens and the center position of the image sensor can be easily matched.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a block diagram of a stereo camera device according to an embodiment of the present invention, and FIG. 1B is a diagram showing an example of a test chart pattern.

  This stereo camera device includes a stereo camera 6, image capture memories 7 and 8, an image overlay processing unit 9, and an image monitor 10.

  The stereo camera 6 has a pair of lenses 2A, 3A and a pair of CCDs (Charge Coupled Devices) 4, 5 corresponding to the pair of lenses (first lens, second lens) 2A, 3A. The pair of lenses 2 </ b> A and 3 </ b> A are respectively held by lens barrels (first and second lens barrels) 2 and 3, and the lens barrels 2 and 3 are accommodated in the stereo camera body 12.

  The CCD 4 is disposed on the optical axis of the lens 2A, and the CCD 5 is disposed on the optical axis of the lens 3A. For example, an image obtained by imaging a test chart (see FIG. 1B) drawn on the screen 1 is output as an image signal (image data) according to the intensity of light by the CCDs 4 and 5.

  The image capture memory 7 captures an image signal for one frame corresponding to the test chart of the screen 1 output from the CCD 4.

  The image capture memory 8 captures an image signal for one frame corresponding to the test chart of the screen 1 output from the CCD 5.

  For example, the image superposition processing unit 9 performs various signal processings on the image signal output from the image capture memory 7 to calculate the distance from the stereo camera 6 to the test chart, and is imaged by the CCD 4 or the CCD 5. The image is displayed on the image monitor 10.

  Next, a method for adjusting the optical axis of the stereo camera device will be described.

  2A is a block diagram of the optical axis adjusting device, and FIG. 2B is a diagram showing an example of a spot light source. The same reference numerals are given to portions common to FIG. 1, and the description thereof is omitted.

  First, a reference lens barrel that holds the lens 13A in the hole 12a of the reference holes 12a and 12b formed in the stereo camera body 12 (a lens barrel in which the center position of the lens 13A and the center position of the CCD 4 are aligned with each other). ) 13 is inserted (first step).

  A small camera (camera) 14 is disposed at a position where the CCD 4 of the stereo camera 6 is disposed. The small camera 14 is fixed to the stereo camera body 12. An image acquired by the small camera 14 is displayed on the image monitor 15.

  A spot light source 11 is disposed on the optical axis of the lens 13A. The light receiving surface of the small camera 14 is disposed at the focal position of the lens 13A.

  When the reference barrel 13 is rotated by hand, for example, the image of the light emitting part of the spot light source 11 arranged on the optical axis is fixed on the image monitor 15 and displayed. The position of the image (reference position) is recorded on the screen of the image monitor 15 with a pen or the like (second step).

  Next, the reference barrel 13 is removed from the hole 12a.

  FIG. 3A is a block diagram of the optical axis adjusting device, and FIG. 3B is a diagram showing an example of a spot light source. To do.

  The adjustment of the lens optical axis of one barrel 2 will be described with reference to FIG.

  The lens barrels 2 and 3 holding the lenses 2A and 3A are inserted into the holes 12a and 12b of the stereo camera body 12, respectively.

  A spot light source 11 is disposed on the optical axis of the lens 2A.

  An image of the spot light source 11 is displayed on the image monitor 15, and an optical axis adjustment described later corresponding to the first lens barrel 2 is made so that the spot light source image coincides with the position of the spot light source image created in the second step. The position of the first lens barrel 2 is adjusted using the mechanism 16 (third step).

  Next, the central axis of the other lens barrel 3 is moved onto the optical axis of the small camera 14.

  4A is a block diagram of the optical axis adjusting device, and FIG. 4B is a diagram showing an example of a spot light source. The same reference numerals are given to portions common to FIGS. To do.

  Adjustment of the lens optical axis of the other lens barrel 3 will be described with reference to FIG.

  An optical axis adjustment mechanism, which will be described later, corresponding to the second lens barrel 3 so that an image of the spot light source is displayed on the image monitor 15 and the spot light source image matches the position of the spot light source image created in the second step. 16 is used to adjust the position of the second lens barrel 3 (fourth step).

  As a result, the optical axes of both lenses 2A and 3A are parallel to each other.

  Next, the optical axis adjustment mechanism will be described.

  FIG. 5A is a conceptual diagram showing a cross section of the stereo camera, and FIG. 5B is a conceptual diagram showing a cross section taken along the line AA of FIG. 5A.

  In FIG. 5, the small camera 14 is removed from the stereo camera body 12, and the CCDs 4 and 5 are fixed at the position where the small camera 14 was located. The CCDs 4 and 5 are mounted on substrates 26 and 27, respectively, and the substrates 26 and 27 are fixed to the stereo camera body 12 with screws 18. The top surface of the stereo camera body 12 is covered with a cover 25.

  The stereo camera body 12 is provided with two optical axis adjustment mechanisms 16 corresponding to the lens barrels 2 and 3. The optical axis adjusting mechanism 16 includes three adjusting screws 16a. The adjustment screw 16a moves back and forth with respect to the central axis of the lens barrels 2 and 3 to move the lens barrels 2 and 3.

  The adjusting screws 16a are respectively screwed into the screw holes 22a formed in the stereo camera body 12 at regular intervals (120 degree intervals) in the circumferential direction. By tightening or loosening the adjustment screw 16a, the positions of the optical axes of the lenses 2A and 3A can be adjusted, and the locus of the image of the light emitting part of the spot light source 11 can be matched with the reference position on the image monitor 15.

  Further, for example, the lens barrel 2 is held by a holding frame (not shown) that is screwed to the stereo camera body 12, and the holding frame is moved in the optical axis direction to adjust the focal position of the lens 2A.

  Similarly, the lens barrel 3 is held by a holding frame (not shown) that is screwed to the stereo camera body 12, and the holding frame is moved in the optical axis direction to adjust the focal position of the lens 3A.

  As a result, the adjustment of the optical axis position and the focal position of the stereo camera 6 is completed.

  According to this embodiment, the optical axis positions of the lenses 2A and 3A and the center positions of the CCDs 4 and 5 can be easily matched.

  In the above-described embodiment, a CCD is used as the imaging device. However, a CMOS (Complementary Metal Oxide Semiconductor) sensor or the like may be used instead of the CCD.

FIG. 1A is a block diagram of a stereo camera device according to an embodiment of the present invention, and FIG. 1B is a diagram showing an example of a test chart pattern. FIG. 2A is a block diagram of the optical axis adjusting device, and FIG. 2B is a diagram showing an example of a spot light source. FIG. 3A is a block diagram of the optical axis adjusting device, and FIG. 3B is a diagram showing an example of a spot light source. FIG. 4A is a block diagram of the optical axis adjusting device, and FIG. 4B is a diagram showing an example of a spot light source. FIG. 5A is a conceptual diagram showing a cross section of the stereo camera, and FIG. 5B is a conceptual diagram showing a cross section taken along the line AA of FIG. 5A.

Explanation of symbols

  2: lens barrel (first lens barrel), 3: lens barrel (second lens barrel), 2A: lens (first lens), 3A: lens (second lens), 6: stereo camera, 11: spot light source ( Light source), 12: stereo camera body, 12a, 12b: hole, 13: reference barrel, 13A: lens, 14: small camera (camera).

Claims (1)

A first step of inserting a lens barrel having a reference lens into one of two holes formed in the stereo camera body;
After this first step, spot light is emitted from a spot light source arranged on the optical axis of the reference lens, and the position of the lens barrel is determined so that the spot light source image becomes a point. A second step of recording the spot light source image of the state;
After the second step, a first lens barrel having a first lens is inserted into one of the two holes in place of the lens barrel, and an image of the spot light source is displayed on the display means. A third step of adjusting the position of the first lens barrel so that the image matches the position of the spot light source image recorded in the second step;
After the third step, a second lens barrel having a second lens is arranged on the optical axis instead of the first lens barrel, and an image of the spot light source is displayed on the display means, and the spot And a fourth step of adjusting the position of the second lens barrel so that the light source image coincides with the position of the spot light source image recorded in the second step. .

Images