JP2000266985A - Automatic focal adjustment device for monitor camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct effective unmanned monitoring. SOLUTION: This device comprises a controller 8 for controlling a focal distance of a camera 5 supported by a biaxial turn device 1 to be turned biaxially, and a detector for detecting two angles θ, ϕ around two axes of the biaxial turn device 1. A known function L (θ, ϕ) having the two angles θ, ϕ as variables is a focal distance. The function L (θ, ϕ) is found by the two angles θ, ϕ, and the two angles θ, ϕ are detected in a real time to provide a substantial automatic focusing function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device for a surveillance camera, and more particularly to an automatic focusing device for a surveillance camera that is effective when a geometric position with respect to the camera is determined.

[0002]

2. Description of the Related Art In banks and supermarkets, surveillance cameras for monitoring intruders and their actions are installed. Such a surveillance camera uses a high-magnification and high-precision lens and does not have an automatic focusing function. As shown in FIG. 4, the operator of the monitoring system monitors the intruder by watching the image on the television monitor 5. The operator follows the movement of the intruder to be photographed, controls the turning device 3 that turns two axes so that the optical axis of the lens 1 faces the intruder, and further moves the lens 1 while watching the image. The focus adjustment is performed by performing an operation of moving.

According to such a conventional operation method, there are the following problems. When manned / manual monitoring is performed, each time the camera 2 is turned, the distance between the camera and the object to be photographed changes, so manual focus adjustment is required, and the operability is poor. In particular, in nighttime shooting, since the image contrast reflected on the television monitor 5 is low, focus adjustment is difficult and operability is poor.

When an unmanned / automatic system for automatically tracking an object to be photographed is used in combination with an image processing apparatus, the distance between the camera and the object to be photographed changes with the movement of the object to be photographed. A clear surveillance image cannot be obtained. As a result, effective monitoring cannot be performed.
It is desirable to perform unmanned and effective monitoring.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic focus adjusting device for a surveillance camera capable of performing unmanned and effective monitoring.

[0006]

Means for solving the problem are described as follows. The technical matters corresponding to the claims in the expression are appended with numbers, symbols, etc. in parentheses (). The number, the symbol, etc. are at least one of the technical matters corresponding to the claims and the plurality of embodiments.
Although the agreement / correspondence with the technical matters of the two forms is clarified, it is not intended to show that the technical matters corresponding to the claims are limited to the technical matters of the embodiment.

An automatic focus adjusting device for a surveillance camera according to the present invention comprises a two-axis turning device (1), a camera (5) supported by the two-axis turning device (1) for turning two axes, and a camera (5). A control device (8) for controlling the focal length of
A detection device for detecting two angles θ and φ around two axes of the two-axis turning device (1), and a known function L (θ, φ) having two angles θ and φ as variables is represented by a focal length. Yes, or corresponding to the focal length. A known function L by two angles θ and φ
(Θ, φ) is known, the two angles θ, φ can be detected in real time, and can have a substantially automatic focusing function. The focal length can be obtained by optical calculation based on the lens configuration. Known function L (θ, φ)
Corresponds to the focal length, but need not correspond to the focal length.

The control device (8) has a table (FIG. 2) for associating the known function L with the two angles (θ, φ).
Preferably, it is expressed as L (θj, φk). The known function L (θ, φ) is given by h /
cos (θ). Where θ is the angle between one of the two axes and the optical axis of the camera (5), h
Is the height between the height position of the camera (5) and the height position of the shooting target (H). When the positional relationship between the camera (5) and the photographing target is determined only by detecting two angles, the automatic focus function is effective. The present invention is effective where there is a defined geometry.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the drawings, an embodiment of an automatic focusing apparatus for a surveillance camera according to the present invention is provided with a television camera and a turning device. The turning device 1 is fixedly provided near the ceiling at a position higher than the floor surface 2. The turning device 1 has a two-axis turning function. The two-axis turning function includes a turning function around the vertical axis 3 and a turning function around the horizontal axis 4. The television camera 5 is attached to such a turning device 1.

The television camera 5 has a focus adjusting lens device 6 at the head, and can move the lens in the direction of the optical axis 7 linearly and rotationally. Focus adjustment lens device 6
Has a lens (not shown) and a driver for moving the lens as described above. The turning device 3 is 2
A shaft drive servomotor (not shown) is provided. The rotational positions of these servo motors are controlled by the computer 8. The driver of the focus adjustment lens device 6 includes another servomotor (not shown), and the rotational position of the servomotor is controlled by the computer 8.

A television monitor 9 is connected to the television camera 5. An operation panel 11 is connected to the computer 8. By operating the operation panel 11, the television camera 5 can be manually rotated in two axes. Operation panel 11
Has an input board, and can supply a calculation formula described later. The operation panel 11 further includes a database 12, and the database 12 includes a table described later.

The database 12 has a table 13 shown in FIG. The angle around the vertical axis 3 is divided into meshes, and the angle coordinates are represented by φj. The angle around the horizontal axis 4 is divided into meshes, and the angle coordinates are represented by θk. The domain of both angle coordinates is determined according to the surrounding environment in which the present apparatus is arranged.

The matrix element Ljk shown in FIG.
Is represented by the following equation. Ljk = L (φj, θk). (1) This function L is not represented by a general formula. As shown in FIG. 2, Ljk is a distance already calculated or obtained by actual measurement. The distance Ljk is a distance variable set between the focus adjustment lens device 6 and the area near the head of the imaging target.

The focus adjustment lens device 6 is provided by the tracking device.
Is directed toward the head H of the imaging target. The angle coordinates (φj, θk) at that time are output from the turning device 1 and input to the computer 8. If such a distance Ljk is set from the television camera 5, when the optical axis 7 is directed to the head H by the tracking device, the computer 8 uses the table 13 to calculate the distance Ljk corresponding to the angular coordinates (φj, θk). Can be determined. Based on the distance Ljk, the focus adjustment lens device 6 automatically moves the lens to an appropriate position.

Such automatic focus adjustment is exactly the same as the automatic focus adjustment in the case of unmanned / automatic operation in the case of manned / manual operation. In the case of manned / manual, the operator can take an image of the head H or an arbitrary imaging target with the operation panel 11. In both automatic and manual modes, the distance Lj set by the table 13 in the direction in which the optical axis 7 of the camera faces.
k objects are clearly projected, and a clear image can be recorded. Automatic focusing can be performed on a low-contrast image at night or a frame accumulation image generated at night with a high-sensitivity camera.

The height of the terrain floor is a function L (φ, θ)
In this case, the table 13 is not required, and the computer 8 can calculate an L (φ, θ) in real time to obtain an appropriate focal length L in real time.

FIG. 2 shows another embodiment of the automatic focus adjusting device for a surveillance camera according to the present invention. The device configuration of this embodiment differs from the device configuration of FIG. 1 only in that the database 12 is omitted. In this embodiment, the floor 2 is a plane, in particular, a horizontal plane. When the vertical axis 3 is orthogonal to the floor 2, the focal length L is
It is expressed by the following equation. L (φ, θ) = h · cos (θ). (2) Here, h is a head which is a vertical component of a distance between the head H of the imaging target and the focus adjustment lens device 6. In this case, the focal length L depends on the angle θ but does not depend on the angle φ.

[0018]

The automatic focus adjusting device for a surveillance camera according to the present invention can exhibit the automatic focus function where the terrain is determined.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an automatic focus adjusting device for a surveillance camera according to the present invention.

FIG. 2 is a table expression expressing a distance.

FIG. 3 is a cross-sectional view showing another embodiment of the automatic focus adjusting device of the surveillance camera according to the present invention.

FIG. 4 is a cross-sectional view showing a known device.

[Explanation of symbols]

 5 camera 8 control device 12 axis rotation device L (θ, φ) known function H subject

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Claims (3)

[Claims] 1. A two-axis turning device, a camera supported by the two-axis turning device for turning two axes, a control device for controlling a focal length of the camera, and a two-axis turning device. A detection device for detecting two angles θ and φ around an axis; and an automatic focus adjustment device for a monitoring camera in which a known function L (θ, φ) having the two angles θ and φ as a variable is the focal length. 2. The control device according to claim 1, wherein the control device includes the known function L and the two angles (θ,
φ), wherein the table is such that the known function is discontinuously Ljk = L
An automatic focus adjustment device for a surveillance camera, which is represented as (θj, φk). 3. The method according to claim 1, wherein the known function L (θ, φ) is h / independent of an angle φ.
where θ is the angle between one of the two axes and the optical axis of the camera, and h is the height position of the camera and the height of the subject. An automatic focus adjusting device for a surveillance camera, wherein the automatic focus adjusting device is located at a height between the camera position and the camera position.