JPH0638095A - Diaphragm device for lens for video camera - Google Patents

Abstract

PURPOSE:To enable diaphragm control by outputting a braking voltage corresponding to the drive of a motor to a diaphragm mechanism when a lens provided with a motor type diaphragm device is mounted on a video camera to output a galvano meter system diaphragm driving signal. CONSTITUTION:An attachable, detachable and exchangable motor type diaphragm mechanism 11 is mounted on a main body 10 of the video camera to output the galvano meter system diaphragm driving signal. A braking circuit 21 is connected to a driving circuit 18 of the diaphragm mechanism 11. The circuit 21 extracts a signal proportional to the moving speed of a diaphragm, namely, the operating speed of an actuator 17 from one part of the driving circuit 18 by using the counter electromotive force of the motor 17, converts the signal to a braking voltage signal corresponding to the braking coil field back signal of a galvano meter and inputs it to a diaphragm control circuit 13 at the main body 10 of the video camera.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera equipped with a motor-driven diaphragm mechanism which enables replacement mounting on a video camera which outputs only a galvanometer system diaphragm drive signal as an automatic diaphragm signal from the video camera body. The present invention relates to a diaphragm device for use lenses.

[0002]

2. Description of the Related Art Conventionally, as an automatic diaphragm device for a video camera lens, an auto iris mechanism has been generally employed in which the diaphragm mechanism is driven by an actuator such as a motor or a galvanometer to adjust the diaphragm amount of the lens. Different drive signals are output from the video camera body to the lens aperture drive circuit between the case and the galvanometer.

For example, in the above-mentioned motor-driven diaphragm mechanism, a signal corresponding to a luminance signal is output from the video signal of a video image captured by the video camera body to the lens side, and the signal is output by the circuit in the lens. After processing into a DC signal, a drive signal corresponding to the opening / closing direction and operation amount of the diaphragm is supplied to the motor drive circuit as compared with the reference signal corresponding to the reference brightness, and the diaphragm mechanism is driven by a predetermined amount based on the signal. A predetermined driving voltage is output to the motor for driving, and the motor is rotated by a predetermined amount to move the diaphragm mechanism to a predetermined diaphragm position and stop.

On the other hand, in the galvanometer-driving type diaphragm mechanism, the driving voltage based on the luminance signal obtained from the video signal in the video camera body is also directly output to the galvanometer on the lens side. A drive coil for driving and a braking coil for detecting a signal corresponding to the rotation speed thereof are provided,
A braking voltage (braking coil feedback signal) proportional to the rotational speed is input to the video camera body side, feedback control is performed between the voltage and the driving voltage, and the galvanometer is operated in a predetermined state. There is.

[0005]

However, for example, in an industrial video camera or the like, the structure is such that the lens can be exchanged, and the video camera body is a galvanometer-driven diaphragm mechanism when the lens is exchanged. When a lens having a motor-driven diaphragm mechanism is attached to a device that outputs a drive signal for the, the diaphragm control cannot be performed depending on the galvanometer system diaphragm drive signal from the video camera side.

Further, the aperture control of the video camera lens may be switched between automatic aperture control by a signal from the camera and aperture control by remote control. At that time,
Although it must be configured as a motor drive system or other drive system capable of remote control, the aperture control with a galvanometer built-in that operates by galvanometer system automatic aperture signal cannot control the aperture by this remote control, and as described above. The galvanometer type aperture drive signal cannot control the aperture of a lens having a built-in aperture mechanism that operates by a motor drive signal that can be remotely controlled.

In view of the above circumstances, the present invention is for a video camera equipped with a motor-driven diaphragm mechanism capable of controlling the diaphragm by this driving signal even if the video camera body outputs a galvanometer type diaphragm driving signal. An object of the present invention is to provide a diaphragm device for a lens.

[0008]

In order to achieve the above object, a diaphragm apparatus for a video camera lens according to the present invention comprises a diaphragm mechanism for adjusting the diaphragm amount of the lens, an actuator by a motor for driving the diaphragm mechanism, A drive circuit that outputs an actuator drive signal to the actuator based on the drive voltage of the galvanometer diaphragm aperture drive signal from the video camera body, and a voltage corresponding to the rotational speed of the actuator is detected and a braking voltage is output to the video camera body. And a braking circuit.

[0009]

In the diaphragm device for a video camera lens as described above, the drive coil drive voltage of the galvanometer diaphragm drive signal output from the video camera body is used as the actuator drive signal in the opening / closing direction of the diaphragm mechanism by the drive circuit. The galvanometer diaphragm drive signal is converted by extracting the voltage signal proportional to the moving speed of the diaphragm mechanism by the operation of the actuator by the motor by the braking circuit and inputting it to the video camera body as the braking voltage equivalent to the feedback signal of the braking coil. With this, it is possible to control the aperture of a lens having a motor-driven aperture mechanism, which increases the versatility of the interchangeable lens and enables remote operation.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of a diaphragm device for a video camera lens according to an embodiment.

A lens 11 is detachably attached to the video camera body 10. The video camera body 10 is provided with an aperture control circuit 13 for outputting an aperture drive signal (drive coil drive signal) for driving an aperture mechanism operated by a galvanometer actuator. When a lens (not shown) having a galvanometer type diaphragm mechanism is attached to the lens, predetermined diaphragm driving can be performed.

The diaphragm control circuit 13 includes a comparator 14 to which a driving voltage corresponding to a luminance signal obtained from a video signal is input on the + side, and a lens 11 to be described later is provided on the-side of the comparator 14.
The braking voltage is input from the side, and the driving voltage for the driving coil is output to the lens 11 side by the feedback control of the driving voltage and the braking voltage.

On the other hand, the lens 11 is provided with a diaphragm mechanism 16 such as an iris diaphragm for adjusting the diaphragm amount.
Actuator with a motor that changes the aperture amount of 17
Is installed. The final actuator drive signal is output from the drive circuit 18 to the actuator 17, and the drive voltage from the aperture control circuit 13 of the video camera body 10 is supplied to the drive circuit 18 as a comparison and amplification circuit. Entered via 19. Further, a terminating resistor 20 is connected to the preceding stage of the comparison / amplifying circuit 19, and the terminating resistor 20 corresponds to the coil resistance of the drive coil of the galvanometer.

The comparison and amplification circuit 19 compares the input voltage with a reference voltage to determine the direction in which the motor 17 is driven and amplifies it, and the drive circuit 18 uses the signal from the comparison and amplification circuit 19 to drive the motor 17. Is converted into a signal for driving.

A braking circuit 21 is connected to the drive circuit 18. The braking circuit 21 utilizes a counter electromotive force of the motor 17 from a part of the driving circuit 18 to take out a signal proportional to the moving speed of the diaphragm, that is, the operating speed of the actuator 17, and corresponds to a galvanometer braking coil feedback signal. It is converted into a braking voltage signal and input to the aperture control circuit 13 in the video camera body 10.

A concrete example of the braking circuit 21 is constituted by a bridge circuit as shown in FIG. 2, and the motor 17 is connected to the bridge circuit so as to extract a voltage proportional to the speed of the rotation of the motor 17. Is configured.

The operation of the above embodiment will be described. A signal corresponding to the measured brightness from the video camera main body 10 is a diaphragm control circuit.
When the drive voltage for the drive coil of the galvanometer is output to the lens 11 side when input to 13, the comparison amplification circuit 19 receiving this signal compares the reference voltage with the reference voltage to operate the diaphragm mechanism 16 in the opening direction or in the closing direction. The actuator drive signal for driving the motor 17 in the opening direction or the closing direction is output from the drive circuit 18 to the motor 17 based on this signal, and the opening / closing operation of the aperture mechanism 16 is driven by the driving of the motor 17. Is done.

Then, corresponding to the drive of the motor 17,
A signal proportional to the driving speed is detected by the braking circuit 21, and the detected voltage is converted into a voltage corresponding to the braking voltage from the braking coil of the galvanometer, and the braking voltage is controlled by the diaphragm control circuit 13 of the video camera body 10. Is input to the motor, and the comparator 14 performs feedback control of the drive voltage by comparing it with the drive voltage corresponding to the luminance signal,
Aperture control is performed so that 17 stops at a predetermined aperture position corresponding to the luminance signal.

Thus, the aperture control of the motor-driven aperture mechanism 16 can be performed by the control signal for driving the galvanometer from the video camera body 10. Further, instead of the aperture control corresponding to the luminance signal based on the video signal, even when the aperture command signal from the remote control panel or the like is input to the aperture control circuit 13, the aperture drive based on the instruction signal is performed. Is possible.

FIG. 3 shows a modified example of the diaphragm device for the lens 11. The braking circuit 25 of this example is provided with a power generator 26 (tacho-generator) which rotates in synchronization with the rotation of the motor 17. A voltage corresponding to the drive speed of the actuator 17 is obtained from the signal of the generator 26, and this is converted into a braking voltage signal corresponding to the signal output from the braking coil of the galvanometer, and the diaphragm control circuit of the video camera body 10 is obtained. It is configured to obtain the braking voltage to be input to 13, and is otherwise configured in the same manner as in the previous example, and similar throttle control is performed.

The braking circuit is not limited to the one using the bridge circuit as in the above-described embodiment, the one using the generator, and the known structure for extracting the voltage proportional to the driving speed of the actuator 17 can be appropriately changed. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a main part of a video camera lens and a video camera body having a diaphragm device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of the braking circuit of FIG.

FIG. 3 is a schematic block diagram showing a diaphragm device for a video camera lens according to another embodiment of the present invention.

[Explanation of symbols]

 10 Video camera body 11 Lens 13 Aperture control circuit 16 Aperture mechanism 17 Actuator (motor) 18 Drive circuit 21,25 Braking circuit

Claims (1)

[Claims] 1. A diaphragm device for a video camera lens, which is replaceably mounted on a video camera body for outputting a galvanometer diaphragm drive signal, comprising: a diaphragm mechanism for adjusting a diaphragm amount of the lens; An actuator driven by a motor, a drive circuit for outputting an actuator drive signal to the actuator based on a drive voltage of a galvanometer type aperture drive signal from the video camera body, and a voltage corresponding to the drive speed of the actuator is detected to detect the video. A diaphragm device for a video camera lens, comprising: a camera body; and a braking circuit that outputs a braking voltage.