JPH11249218A - Zoom position display device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom position display device for a lens device preventing zoom position display from being fluctuated by the movement of a zoom lens due to pumping correction by subtracting the displacement quantity based on pumping correction, from a zoom lens detection position to display a zoom position in the case of moving the zoom lens by pumping correction. SOLUTION: In a lens device feedback-controlling to nullify the difference between a position command signal for assigning the target position of a zoom lens 50 and a lens position signal indicating the present position of the zoom lens 50, pumping correction is made by subtracting a pumping correction signal from the lens position signal, and a signal obtained by subtracting the pumping correction signal from the lens position is inputted to a zoom position display device 70. The zoom position is displayed on the basis of this signal to prevent the fluctuation of zoom position display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom position display device for a camera, and more particularly to a camera for performing pumping correction for automatically displacing a variable-magnification lens group when a focus lens group moves to prevent a change in a photographing angle of view. Related to a zoom position display device.

[0002]

2. Description of the Related Art Conventionally, in a lens device for a television camera used for broadcasting or the like, if focus adjustment is performed by moving a focus lens group, a photographing angle of view also changes at the same time. In view of this, pumping correction is known in which when the focus lens group moves, the variable power lens group (zoom lens group) is automatically and minutely moved to prevent a change in the angle of view. The pumping correction is described in JP-A-6-250071.

In a lens device for a television camera, a zoom lens (focal length) is displayed on an indicator plate attached to the lens device by detecting the position of a variable power lens group. -1790
No. 06 publication.

[0004]

However, if the pumping correction is performed in the lens apparatus for displaying the zoom position on the indicator plate as described above, the variable power lens group can be used even though only the focus operation is performed. Has a drawback that the zoom position displayed on the indicator plate changes slightly. In other words, conventionally, the position of the zoom lens group is simply detected by a potentiometer, and the detected position is converted into a zoom position and displayed. When the zoom lens group moves by pumping correction, the display of the zoom position is also performed. There was a problem that it fluctuated.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a zoom position display device of a lens device for preventing a display of a zoom position from fluctuating due to movement of a variable power lens group due to pumping correction. With the goal.

[0006]

In order to achieve the above object, the present invention comprises a focus lens group and a variable power lens group. When the focus lens group moves, the variable power lens group is automatically displaced. A zoom position display device of a camera for performing pumping correction for preventing a change in a photographing angle of view, wherein a zoom position detecting means for detecting a position of the zoom lens group, and the zoom lens group detected by the zoom position detecting means. A zoom position subtracting means for subtracting the displacement amount of the variable power lens group displaced by the pumping correction from the position, and a focal length based on the position of the variable power lens group obtained by the subtraction of the zoom position subtracting means. And zoom position display means for displaying the indicated zoom position.

According to the present invention, when the variable power lens group is displaced by the pumping correction, the amount of displacement is subtracted from the detected position of the variable power lens group, and the position of the variable power lens group obtained by the subtraction is subtracted. Since the zoom position is displayed based on the zoom position, the display of the zoom position does not change even if the zoom lens group moves due to the pumping correction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a zoom position display device for a camera according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing an appearance of a television camera to which the present invention is applied. As shown in FIG. 1, the television camera 10 includes a lens device 12 and a camera body 14. The lens device 12 is detachably mounted on the camera body 14, and is electrically connected to the camera body 14 via an interface. Is to be connected to.

A head 18 for supporting the television camera 10
, Two pan / tilt bars 22 (only one pan / tilt bar is shown) are extended, and a grip portion 24 at the tip of the pan / tilt bar 22 has a focus for operating a focus. A demand (not shown) and a zoom controller 26 for operating a zoom are attached.

A position control signal is output from the focus demand, and the position control signal is input to the lens device 12 via a cable. Then, the lens device 12
The position of the focus lens (group) is controlled based on this position control signal. On the other hand, a speed control signal is output from the zoom controller 26 based on the rotation operation of the zoom ring 30, and the speed control signal is input to the lens device 12 via the cable 28. Then, the lens device 12
The zoom lens (group) is speed-controlled based on this speed control signal.

The cameraman can adjust the focus and zoom of the lens device 12 by operating the focus demand and the zoom controller 26 while watching the photographed image shown in the viewfinder 16. Also,
An indicator plate 32 is attached to a side surface of the lens device 12. As shown in FIG. 2, a zoom position (focal position) and an aperture value are written on the indicator plate 32, and L is displayed adjacent to each zoom position and the written position of each aperture value.
EDs 32A, 32A,... Are provided. As a result, the LEDs 32A, 32A,... Blink and the zoom position and the aperture value are displayed as levels. When the zoom lens is moved by the zoom controller 26, the position of the zoom lens is detected by the potentiometer, and the zoom position is displayed on the indicator plate 32 based on the detected value.

Next, a zoom position display device for displaying the zoom position on the indicator plate 32 will be described. As shown in FIG. 3, the zoom lens 50 of the lens device 12 is driven by a zoom motor 52,
Are driven by a motor control signal input from the subtractor 56 via the amplifier 54. A position command signal indicating a target position of the zoom lens 50 is input to one input side of the subtractor 56, and a lens position signal indicating a control position of the zoom lens 50 detected by the potentiometer 58 is input to the other input side. Is input via the subtractor 60.

A pumping correction signal, which will be described later, is input to the subtractor 60 so that the pumping correction signal is subtracted from the lens position signal. However, when the pumping correction signal is not input, Subtractor 5
At 6, the difference between the position command signal and the lens position signal is obtained, and this difference is output to the zoom motor 52 as the motor control signal.

Thus, when the pumping correction signal is not input, the lens position signal is fed back to the position command signal, and the zoom lens 50 determines that the difference between the position command signal and the lens position signal is zero. Thus, the target moves to the target position indicated by the position command signal. Note that the circuit shown in FIG. 3 shows a circuit configuration when the zoom controller 26 is not operated.
When the zoom controller 26 is operated, the speed of the zoom lens 50 is controlled by a speed control signal output from the zoom controller 26. However, when the zoom controller 26 is not operated, the speed of the zoom lens 50 is reduced. The control is switched to the position control as shown in FIG. That is, when the zoom controller 26 is in a non-operation state, the position of the zoom lens 50 immediately after the non-operation is detected by the potentiometer 58, the detected position is held, and the position is subtracted as a position command signal by the above subtraction. The signal is input to the device 56. Thus, while the zoom lens 50 is held at a fixed position, when a pumping correction signal is input as described later, the zoom lens 50 moves to a position displaced by a displacement amount indicated by the pumping correction signal and stops. Has become.

Next, the case where a pumping correction signal is input will be described. When the focus demand is operated while the zoom controller 26 is not operated and the focus lens is moved, the pumping correction is performed so that the angle of view does not change. Is performed. In this case, a pumping correction signal is input to the subtractor 60.

When the pumping correction signal is input to the subtractor 60, the lens position signal input to the subtractor 60 from the potentiometer 58 is subtracted by the pumping correction signal, and the subtracted lens position signal is input to the subtractor 56. Will be entered. Thereby, the subtractor 56
The zoom lens 50 is displaced such that the lens position signal input to the zoom lens 50 coincides with the position command signal. As a result, the zoom lens 50 is displaced by the amount subtracted by the pumping correction signal.

The zoom lens 50 constructed as described above
In the drive circuit of the above, the zoom position display device 70 for displaying the zoom position on the indicator plate 32 includes a subtractor 60
, Ie, between the subtractor 60 and the subtractor 56. As a result, a signal obtained by subtracting the pumping correction signal from the lens position signal is input to the zoom position display device 70. As described above, when the pumping correction is performed, the zoom lens 50 moves so that the value obtained by subtracting the pumping correction signal from the lens position signal matches the position command signal. Becomes a constant value even after executing the pumping correction. Accordingly, the zoom position display device 70 displays the zoom position based on the signal output from the subtractor 60, so that the display of the zoom position does not change even if the zoom lens 50 is displaced by the pumping correction.

As described above, in the above embodiment, the pumping correction of the zoom lens 50 is performed by feeding back a signal obtained by subtracting the pumping correction signal from the lens position signal to the position command signal, and the pumping correction signal is subtracted from the lens position signal. By displaying the zoom position based on the signal obtained, fluctuation of the display of the zoom position due to the pumping correction is prevented, but the present invention is not limited to this. For example,
As shown in FIG. 4, when the pumping correction signal is added to the position command signal by the adder 80, and the lens position signal is fed back to this signal to perform the pumping correction, the lens position signal is displayed on the zoom position display device 70. A change in the display of the zoom position may be prevented by inputting via the subtractor 82 and subtracting the pumping correction signal from the lens position signal by the subtractor 82.

[0019]

As described above, according to the zoom position display device for a camera according to the present invention, when the variable power lens group is displaced by the pumping correction, the displacement amount is subtracted from the detected position of the variable power lens group. Since the zoom position is displayed based on the position of the zoom lens group obtained by the subtraction, the display of the zoom position does not change even if the zoom lens group moves due to the pumping correction.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of a television camera to which the present invention is applied.

FIG. 2 is a diagram illustrating an indicator plate that displays a zoom position and the like;

FIG. 3 is a diagram illustrating a drive circuit of a zoom lens and an input signal capturing position of a zoom position display device.

FIG. 4 is a diagram illustrating another embodiment of a drive circuit of a zoom lens and an input signal capturing position of a zoom position display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... TV camera 12 ... Lens device 14 ... Camera main body 26 ... Zoom controller 32 ... Indicator plate 50 ... Zoom lens 52 ... Zoom motor 54 ... Amplifier 56, 60 ... Subtractor 58 ... Potentiometer 70 ... Zoom position display device

Claims (1)

[Claims] 1. A camera comprising a focus lens group and a variable power lens group, wherein when the focus lens group moves, the variable power lens group is automatically displaced to perform a pumping correction for preventing a change in a photographing angle of view. In the zoom position display device, a zoom position detecting means for detecting a position of the variable power lens group; and a zoom lens group displaced by the pumping correction from the position of the variable power lens group detected by the zoom position detecting means. Zoom position subtracting means for subtracting the displacement amount; and zoom position displaying means for displaying a zoom position indicating the focal length based on the position of the variable power lens group obtained by the subtraction of the zoom position subtracting means. A zoom position display device for a camera.