JP3247151B2 - Aperture device for video camera lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera provided with a motor-driven aperture mechanism which can be exchangeably mounted on a video camera which outputs only a galvanometer type aperture drive signal as an automatic aperture signal from the video camera body. The present invention relates to a diaphragm device for a lens.

[0002]

2. Description of the Related Art Conventionally, as an automatic aperture device for a video camera lens, an auto iris mechanism for adjusting the aperture of a lens by driving the aperture mechanism with a motor or an actuator by a galvanometer has been generally employed. Different drive signals are output from the video camera body to the lens aperture drive circuit in the case and the galvanometer.

For example, in the above-described motor-driven diaphragm mechanism, a signal corresponding to a luminance signal is output from a video signal of an image photographed by a video camera body to a lens side, and the signal is output by a circuit in the lens. After processing into the DC signal, a drive signal corresponding to the opening / closing direction and the amount of operation of the diaphragm is supplied to the motor drive circuit in comparison with a reference signal corresponding to the reference luminance, and the diaphragm mechanism is moved to a predetermined amount based on the signal. A predetermined drive voltage is output to the motor for driving, whereby the motor rotates by a predetermined amount, moves the aperture mechanism to a predetermined aperture position, and stops.

On the other hand, in a galvanometer-driven diaphragm mechanism, a driving voltage based on a luminance signal obtained from a video signal in a video camera body is directly output to a galvanometer on the lens side. With a driving coil for driving and a braking coil for detecting a signal corresponding to the rotation speed thereof,
A braking voltage (braking coil feedback signal) proportional to the rotation speed is input to the video camera main body, and feedback control is performed between the braking voltage and a driving voltage to operate the galvanometer in a predetermined state. I have.

[0005]

However, for example, an industrial video camera or the like is provided with a structure in which a lens can be exchanged. At the time of this lens exchange, the main body of the video camera is driven by a galvanometer-driven diaphragm mechanism. When a lens having a motor-driven aperture mechanism is attached to a lens that outputs a drive signal to the lens, there is a problem that aperture control cannot be performed by a galvanometer-type aperture drive signal from the video camera side.

In some cases, aperture control of a video camera lens is switched between automatic aperture control based on a signal from a camera and aperture control by remote control.
A motor drive system or other drive system capable of remote operation must be configured.However, an aperture mechanism with a built-in galvanometer operated by a galvanometer system automatic aperture signal cannot perform aperture control by this remote operation, and as described above. The aperture drive signal of the galvanometer method cannot control the aperture of a lens having a built-in aperture mechanism operated by a motor drive signal that can be remotely controlled.

In view of the above circumstances, the present invention is directed to a video camera having a motor-driven aperture mechanism capable of controlling the aperture by the drive signal even if the video camera body outputs a galvanometer type aperture drive signal. It is an object of the present invention to provide a lens aperture device.

[0008]

In order to achieve the above object, a video camera lens aperture device according to the present invention comprises: an aperture mechanism for adjusting the aperture of the lens; an actuator using a motor for driving the aperture mechanism; A drive circuit for outputting an actuator drive signal to the actuator based on a drive voltage of a galvanometer diaphragm drive signal from the video camera body, and detecting a voltage corresponding to the rotation speed of the actuator and outputting a braking voltage to the video camera body. And a braking circuit.

[0009]

In the aperture device for a video camera lens as described above, the drive voltage for the drive coil of the galvanometer type aperture drive signal output from the video camera body is converted into an actuator drive signal in the opening and closing direction of the aperture mechanism by the drive circuit. A voltage signal proportional to the speed of movement of the diaphragm mechanism due to the operation of the actuator by the motor is taken out by the braking circuit, and is input to the video camera body as a braking voltage corresponding to a braking coil feedback signal. This makes it possible to control the aperture of a lens incorporating a motor-driven aperture mechanism, thereby increasing the versatility of the interchangeable lens and enabling remote control.

[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 a video camera body 10. The video camera body 10 includes an aperture control circuit 13 that outputs an aperture drive signal (drive coil drive signal) for driving an aperture mechanism operated by an actuator using a galvanometer. When a lens (not shown) having a galvanometer-type aperture mechanism is mounted on the camera, a predetermined aperture drive can be performed.

The aperture control circuit 13 includes a comparator 14 to which a driving voltage corresponding to a luminance signal obtained from a video signal is input to a positive side, and a negative side of the comparator 14
The driving voltage for the driving coil is output to the lens 11 by 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 17 that changes the aperture of the motor
Is installed. A final actuator drive signal is output from the drive circuit 18 to the actuator 17, and a drive voltage from the aperture control circuit 13 of the video camera body 10 is supplied to the drive circuit 18 by a comparison amplifier circuit. Entered via 19. A terminating resistor 20 is connected to a stage preceding the comparison amplifier circuit 19, and the terminating resistor 20 corresponds to a coil resistance of a driving coil of the galvanometer.

The comparison amplifying circuit 19 compares the input voltage with a reference voltage to determine the direction in which the motor 17 is driven and amplifies the driving direction. Is converted into a signal for driving.

Further, a braking circuit 21 is connected to the driving circuit 18. The braking circuit 21 uses a back electromotive force of the motor 17 from a part of the driving circuit 18 to extract a signal proportional to the speed at which the diaphragm moves, that is, the operating speed of the actuator 17, and corresponds to a braking coil feedback signal of the galvanometer. The signal is converted into a braking voltage signal and input to an aperture control circuit 13 in the video camera body 10.

As a specific example of the braking circuit 21, a bridge circuit as shown in FIG. 2 is used. Is configured.

The operation of the above embodiment will be described. A signal corresponding to the measured luminance is output from the video camera body 10 to an aperture control circuit.
When the drive voltage for the drive coil of the galvanometer is output to the lens 11 side, the signal is compared with a reference voltage by a comparison amplifier circuit 19 which receives the signal and operates the aperture mechanism 16 in the opening direction or in the closing direction. An 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 and closing operation of the aperture mechanism 16 is performed by driving the motor 17. Is performed.

In response to the driving 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 a braking voltage from a braking coil of the galvanometer, and the braking voltage is converted to an aperture control circuit 13 of the video camera body 10. The comparator 14 performs feedback control of the drive voltage by comparing the drive voltage 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.

As a result, the aperture of the motor-driven aperture mechanism 16 can be controlled 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, when an aperture command signal from a remote control panel or the like is input to the aperture control circuit 13, the aperture drive based on the command signal is performed. Is possible.

FIG. 3 shows a modification of the aperture device for the lens 11. The braking circuit 25 of this embodiment includes a generator 26 (tach generator) that rotates in conjunction with the rotation of a motor 17, A voltage corresponding to the drive speed of the actuator 17 is obtained from the signal of the generator 26, and the voltage is converted into a braking voltage signal corresponding to a signal output from the braking coil of the galvanometer, and the diaphragm control circuit of the video camera body 10 This is configured to obtain a braking voltage to be input to 13, and the other configuration is the same as in the previous example, and the same aperture control is performed.

The braking circuit can be appropriately designed and changed to a known configuration for extracting a voltage proportional to the driving speed of the actuator 17 in addition to the one using the bridge circuit as in the above embodiment, the one using a generator, and the like. .

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a specific example of the braking circuit of FIG. 1;

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)

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