JP2602733B2 - How to adjust the optical axis of a video camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting an optical axis of a video camera for matching an optical axis of a zoom lens with a sensor of a solid-state imaging device such as a CCD.

<Prior Art> In general, a manufacturer performs an optical axis adjustment operation for matching the optical axis of a zoom lens of a video camera with the center of an effective pixel of a CCD as follows.

That is, as shown in FIG. 4, a cap 8 having a hole 7 at the center is put on the tip of the lens unit 9 of the video camera, and the zoom lens is set in a macro state.
While observing the image based on the output from 0 on the underscan monitor, the CCD 10
The CCD 10 is moved in the Y direction, and when the hole 7 of the cap 8 coincides with the center of the underscan monitor as shown in the monitor screen of FIG. 5, the CCD 10 is fixed at that position.

Alternatively, a predetermined pattern is imaged without using the cap 8, and the zoom lens is set at the wide-angle end (telephoto end).
The image of the center of the underscan monitor based on the output of the CCD10 even when the CCD10 is moved from the telephoto end to the telephoto end (wide-angle end) is found.
Is fixed.

<Problems to be Solved by the Invention> However, in the former optical axis adjustment, since the zoom lens is adjusted in a macro state, when the zoom lens is actually moved, the center image moves. In the latter case, the optical axis adjustment tries a CCD position where the center image does not move even if the zoom lens is moved from the wide-angle end (telephoto end) to the telephoto end (wide-angle end). The search must be made in an erroneous manner. Therefore, in order to perform the adjustment with high accuracy, the movement of the zoom lens must be repeatedly performed, and there is a disadvantage that the adjustment work takes time.

The present invention has been made in view of the above points,
An object of the present invention is to shorten the time required for the adjustment work and to enable highly accurate optical axis adjustment.

<Means for Solving the Problems> In order to achieve the above object, the present invention is configured as follows.

That is, the present invention relates to a method of adjusting the optical axis of a video camera that matches the optical axis of a zoom lens with the center of a solid-state imaging device, wherein a large number of shaped portions having a predetermined size corresponding to pixels of the solid-state imaging device are provided. And the reflectance of each of the adjacent shape portions is different from each other. A subject having a required pattern is arranged at a fixed position, and while moving the zoom lens, the subject is imaged at a predetermined imaging position, and the zoom lens is moved. Based on the output change of each pixel of the solid-state imaging device according to, to detect a pixel that matches the optical axis of the zoom lens,
The solid-state imaging device is moved so that the center of the solid-state imaging device is located at the position of the detected pixel.

<Operation> The present invention provides an image pickup method for a subject having a required pattern, in which a zoom lens is moved from a telephoto end (wide-angle end) to a wide-angle end (telephoto end). The output of a pixel coinciding with the optical axis of the zoom lens is substantially constant irrespective of the movement of the zoom lens, whereas the output of a pixel not coincident with the optical axis is undesirably affected by the movement of the zoom lens. Focusing on the change, the pixel that matches the optical axis is detected, and the optical axis is adjusted by moving the solid-state image sensor so that the center of the solid-state image sensor is located at the position of the detected pixel. Therefore, by moving the zoom lens once from the telephoto end (wide-angle end) to the wide-angle end (telephoto end), highly accurate optical axis adjustment can be performed.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram for explaining an optical axis adjusting method according to one embodiment of the present invention.

In the optical axis adjustment method of this embodiment, a subject 1 having a required black and white lattice pattern is arranged at a fixed position, a lens unit 2 of a video camera is arranged at a predetermined imaging position, and a zoom lens is set at a telephoto end (wide-angle end). From the object to the wide-angle end (telephoto end), and detects a CCD3 pixel coincident with the optical axis 4 of the zoom lens based on the output change of each pixel of the CCD3 accompanying the movement of the zoom lens. The CCD3 is moved so that the center of the CCD3 is located at the position of the detected pixel.

Therefore, based on the output change of each pixel of the CCD3, the optical axis shift detecting means 5 for detecting the shift of the optical axis, and based on the detected shift amount, the CCD3 is moved in the X and Y directions to zoom lens. CCD position adjusting means 6 for aligning the optical axis 4 with the center of the CCD 3 is provided.

In the grid pattern of the subject 1 of this embodiment, white and black grids having different reflectances are arranged so as to be adjacent to each other, and the size of each grid is determined by the CCD3 when the zoom lens is at the wide-angle end. Is larger than the size corresponding to one pixel. The size of the grid is selected as described above because, when the zoom lens is moved from the telephoto end (wide-angle end) to the wide-angle end (telephoto end) and an image is picked up, the output of pixels that match the optical axis of the zoom lens This is to minimize the change.

In the method of the present invention, light that coincides with the optical axis 4 of the zoom lens travels straight without being refracted by the zoom lens even when the zoom lens is moved from the telephoto end (wide-angle end) to the wide-angle end (telephoto end). By using the property described above, among the pixels of the CCD3, it is attempted to detect a pixel that coincides with the optical axis 4 of the zoom lens. Is detected as follows.

That is, FIG. 2A is a diagram showing a monitor image when the subject 1 is imaged when the zoom lens is at the telephoto end, and FIG. 2B is a diagram when the zoom lens is at the wide-angle end. FIG. 3 is a diagram showing monitor images when a subject 1 is imaged, and each monitor image is shown in correspondence with pixels of CCD3.

Now, the pixel P1 of the CCD3 whose position in the X and Y directions is indicated by (i, j)
Is coincident with the optical axis 4 of the zoom lens, and assuming that light from a white grating is received at the telephoto end as shown in FIG. 2A, the pixel P1 Is moved to the wide-angle end, light from the same white grating is received as shown in FIG. 2 (B).

On the other hand, a pixel that does not coincide with the optical axis 4 of the zoom lens, for example, a pixel P2 whose position in the X and Y directions is indicated by (i−1, j) is at the telephoto end at the time of FIG. As shown in FIG. 2B), light from the white grating is received, but at the wide angle end, light from the black grating is received as shown in FIG. 2B.

Therefore, the output of the pixel P1 coinciding with the optical axis 4 of the zoom lens is substantially constant irrespective of the movement of the zoom lens, as shown by the solid line in FIG.
The output of pixel P2 will change significantly, as indicated by the dashed line in FIG.

Therefore, in the optical axis adjustment method of this embodiment, an image of the subject 1 consisting of a black and white grid pattern is taken while moving the zoom lens from the telephoto end (wide-angle end) to the wide-angle end (telephoto end), and each pixel of the CCD 3 Based on the output change of the zoom lens, the optical axis shift detecting means 5 detects a pixel having little or no output change as a pixel matching the optical axis 4 of the zoom lens. Pixels and
The shift from the pixel at the center of CCD3, that is, the optical axis shift, is calculated.
The optical axis is adjusted by moving the CD3 in the X and Y directions in FIG. 1 so that the pixel at the center of the CCD3 is moved and fixed so that the pixel located at the center of the CCD3 is located.

As described above, since the optical axis is adjusted based on the change in the output of each pixel of the CCD3, the optical axis can be adjusted with higher accuracy than the conventional example in which the zoom lens is visually moved by a monitor. In this case, the time required for the optical axis adjustment operation can be reduced as compared with the conventional example in which the optical axis is adjusted by repeatedly moving the zoom lens.

In the above embodiment, the subject is a rectangular lattice pattern, but the present invention is not limited to this.
Other patterns, for example, a triangular or circular pattern, may be used. If the reflectance is different and a change in the pixel output of the CCD can be detected, the pattern is not limited to a black and white grid.

<Effects of the Invention> As described above, according to the present invention, a subject having a required pattern is imaged by moving the zoom lens, and is aligned with the optical axis of the zoom lens based on a change in the output of each pixel of the solid-state image sensor. Since the optical axis is adjusted by detecting the matching pixel and moving the solid-state image sensor so that the center of the solid-state image sensor is located at the position of the detected pixel, the conventional example in which the monitor is visually performed is used. The optical axis adjustment with higher accuracy can be performed, and the movement of the zoom lens can be basically performed only once, so that the time required for the optical axis adjustment can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining an optical axis adjustment method according to an embodiment of the present invention, FIG. 2 is a diagram showing a monitor screen for explaining the adjustment principle of the present invention, and FIG. FIG. 4 is a diagram showing a change in pixel output, FIG. 4 is a diagram showing a conventional example, and FIG. 5 is a diagram showing a monitor screen of a conventional example. 1 ... subject, 3 ... CCD, 4 ... optical axis of zoom lens.

Claims (1)

(57) [Claims] 1. A method of adjusting an optical axis of a video camera, wherein an optical axis of a zoom lens and a center of a solid-state image sensor are matched, wherein a plurality of shape portions having a predetermined size corresponding to pixels of the solid-state image sensor are used. And the reflectance of each adjacent shape portion is different from each other in a required pattern. The subjects are arranged at fixed positions, and the subject is imaged at a predetermined imaging position while moving the zoom lens. A pixel matching the optical axis of the zoom lens is detected based on the output change of each pixel of the solid-state imaging device, and the solid-state imaging device is positioned such that the center of the solid-state imaging device is located at the position of the detected pixel. Moving the optical axis of the video camera.