JPS6241291Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a servo-driven zoom lens, and more particularly to a zoom speed control device capable of high-speed zooming at a constant speed in addition to a variable normal zoom speed.

Servo-driven zoom lenses are widely used in television lenses, and when you turn a control knob that has the habit of returning to a stop position using a spring, etc., the output voltage of the potentiometer changes, and the output voltage changes depending on this voltage. A servo motor rotates at a certain speed to perform zooming, and the direction of rotation of the servo motor corresponds to the direction of rotation of the operating knob.

It is difficult to capture a new subject when the zoom lens is on the tele side, so when changing the subject, first return the zoom lens to the wide end (W), then point the TV camera at the new subject. After that, zooming and focusing are performed to obtain the desired screen configuration. In this way, when changing the cut, it is necessary to pull the zoom lens to a zoom position at or near the wide end, and in order to change the cut quickly during this zooming, it is desirable that the zoom speed be as fast as possible. On the other hand, when zooming within the same cut, it is desirable to avoid too fast a zoom speed, considering visibility and operational noise.

Based on the above background, it is an object of the present invention to provide a zoom speed control device capable of performing high-speed zooming necessary for changing cuts in addition to the normal zoom speed.

The present invention is provided with an output terminal of a potentiometer and a constant voltage terminal that outputs a voltage exceeding the output range of this potentiometer. This voltage is input to the servo drive system.

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

FIG. 1 shows a zooming operation section of a television camera. A camera body (not shown) is provided with a cylindrical portion 1, from which protrudes a grip 2 for changing the direction of the camera.
An operating knob 3 for zooming is provided on the outer periphery of the grip 2, and can be rotated by placing the thumb on the approximately V-shaped finger rest 3a. This rotation of the operating knob 3 is transmitted to a potentiometer 4 housed in the cylindrical portion 1 via, for example, a gear mechanism. Said operation knob 3
is stationary at the position shown in FIG. 1 by a spring or the like (not shown), and a push button 5 provided on the cylindrical portion 1 can be pressed with the thumb resting on the finger rest 3a.

FIG. 2 shows the zoom speed control circuit. The resistor 6 of the potentiometer 4 is grounded approximately at its center, and variable resistors 7 and 8 are connected to both ends thereof. A sliding terminal 9 of this potentiometer 4 is connected to a contact a of a switch 10. The switch 10 comes into contact with the contact b when the push button 5 is pressed against a spring or the like.
This contact b has a voltage higher than the maximum output voltage of the potentiometer 4. In this embodiment, the zoom lens is moved to the wide (W) side at high speed, but contact b may be connected to the variable resistor 8 to perform high-speed zooming to the tele (T) end. .

The voltage selected by switch 10 is input to servo amplifier 12 via resistor 11. The output of this servo amplifier 12 is applied to a motor 13 to drive it. As is well known, the rotation of the motor 13 is transmitted to the cam mechanism of the zoom lens, and the movable optical system is moved in the optical axis direction to perform zooming. A tachometer generator 14 is provided coaxially with the motor 13, and the voltage generated by the tachometer generator 14 is fed back to the servo amplifier 12.

Next, to explain its function, when the operation knob 3 is turned, the sliding terminal 9 of the potentiometer 4
moves, and a voltage corresponding to that position is output.
For example, when the operating knob 3 is turned to the wide side, the output voltage of the potentiometer 4 increases, and the motor 13 rotates at a speed corresponding to this voltage. Motor 1
The rotational speed of No. 3 is detected by the tachometer generator 14 and fed back to the servo amplifier 12, so the motor 13 performs zooming while maintaining the set speed. When the operating knob 3 is turned to the telephoto side, the motor 13 will rotate in the reverse direction.

When changing the cut, when the push button 5 is pressed, the switch 10 connects to contact b, so a high voltage is input to the servo amplifier 12, and the motor 13 rotates at high speed to return the zoom lens to the wide end. I can do it.

The present invention having the above configuration is capable of high-speed zooming in addition to the normal zoom speed controlled by a potentiometer, so the zoom lens can be quickly moved to the wide end or telephoto end when changing the cut, etc. Convenient when returning. Furthermore, since these two types of zooming can be switched using a switch provided near the operating knob, it is possible to perform the zooming operation quickly.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an operating section of the present invention, and FIG. 2 is a wiring diagram showing an electric circuit of the present invention. 2...grip, 3...operation knob, 4...potentiometer, 5...push button, 10...switch, 12...servo amplifier, 13...motor, 14...tachogenerator.

Claims (1)

[Scope of utility model registration request] In a zoom speed control device that is equipped with a speed-controlled servo drive system that drives a zoom lens and performs zooming at a speed that corresponds to the output of a potentiometer that is linked to an operation knob, the output terminal of the potentiometer is In addition, a constant voltage terminal was provided to output a voltage exceeding the output range of this potentiometer, and the voltage from the terminal selected by a switch provided near the operating knob was configured to be input to the servo drive system. A zoom speed control device characterized by: