JPS581007Y2 - Video camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video camera with an improved automatic aperture device.

Video cameras generally have a viewfinder,
It contains a cathode ray tube for monitoring.

This cathode ray tube can be used as a monitor when taking an image, and can also be used as a display device when reproducing images recorded on a VTR.

When a video system is used outdoors, a receiver for reproduction is not usually provided, so the reproduced images of the VTR are often viewed on the monitor cathode ray tube of the video camera.

In such a video system, while the reproduced image is being viewed on the cathode ray tube of the video camera, the power of the video camera is turned on and the electron beam is scanned in the image pickup tube.

At this time, if you can cover the camera lens with a cap to prevent external light from hitting the image pickup tube, there will be no problem, but in general, it is troublesome to cover the cap, so don't forget it. There are many.

Because the cap cannot be overturned, strong light enters, and because the video camera is observing the reproduced image, the electron beam is scanned in the image pickup tube, and because imaging is stopped, the subject is stationary. If the lens is kept pointed, part or all of the photoelectric conversion surface of the image pickup tube will continue to be exposed to strong light, causing deterioration of the photoelectric conversion surface.
Sometimes it was burnt out.

In particular, in the final state of image capture, if a dark subject is being imaged, the automatic diaphragm device is in a substantially fully opened state, and the above-mentioned problem occurs conspicuously.

Further, especially when the video system is used outdoors, there is a high possibility that the incident light will be strong, and the above-mentioned problems are likely to occur.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a video camera that has a simple configuration and can easily protect its image pickup tube.

To achieve the above object, the present invention includes an image pickup tube, an automatic aperture device that adjusts the amount of light entering the image pickup tube, and a viewfinder section having a monitor display device that is driven simultaneously with the image pickup tube. a video signal supply circuit that selectively supplies an internal video signal based on the output of the image pickup tube and an external video signal based on the output of an external device to the monitor display device; and the diaphragm device based on the output of the image pickup tube. In order to automatically adjust the amount of aperture in the image pickup tube, the aperture device is provided between the image pickup tube and the aperture device, and includes, for example, a detection circuit 6, a reference circuit 7, a comparator circuit 8, an amplifier 9, etc. an automatic aperture control signal forming circuit, an aperture full-close drive circuit that generates an aperture full-close drive signal for fully closing the aperture in the aperture device, and an external video signal in the video signal supply circuit. The present invention relates to a video camera comprising a switch for connecting the fully closed diaphragm drive circuit to the diaphragm device in response to the selection of the diaphragm device.

According to the present invention, a fully closed diaphragm drive circuit and a switch for selectively connecting the diaphragm to the diaphragm device are provided, and this switch responds to the selection of the external video signal in the video signal supply circuit. Even if the image pickup tube and the viewfinder section are in a driving state, the aperture 75
It becomes full-throttle musically.

Therefore, it is possible to reliably and easily protect the image pickup tube in the driving state.

Next, one embodiment of the present invention will be described.

The drawing schematically shows a video camera with an automatic aperture device and a viewfinder.

In the video camera section, an image pickup tube 2 receives light that enters through a lens 1, and an iris or aperture device 3 is provided between the lens 1 and the image pickup tube 2 to adjust the amount of light. It is being

The output signal obtained from the image pickup tube 2 is sent to a video signal supply circuit 5 through a video amplifier 4.

The video signal supply circuit 5 includes a circuit for forming a video signal based on the output of the image pickup tube 2 and a VTR as an external device, and includes a video signal based on the image pickup tube, that is, an internal video signal, and a video signal based on the VTR, that is, an external video signal. and a switch for selectively supplying the same to the cathode ray tube display device 15.

Since this video camera is of an automatic aperture type, an aperture control circuit is provided to control the automatic aperture device consisting of an aperture device 3 and a motor 10.

The aperture control circuit includes a detection circuit 6, a reference circuit 7, a comparator circuit 8, and an amplifier 9, which are provided in a typical automatic aperture system.
In addition, it includes a fully closed diaphragm drive circuit 11 and a changeover switch 12.

During automatic aperture control, a signal from the output stage of the image pickup tube 2 is detected by a detection circuit 6, and this detection output and a reference signal provided from a reference circuit 7 are compared by a comparison circuit 8.

After that, the comparison output obtained from the comparison circuit 8 is sent to the amplifier 9.
The signal is amplified and supplied to the motor 10.

The motor 10 rotates in accordance with the magnitude of the signal given from the amplifier 9, and automatically adjusts the amount of aperture in the aperture device 3.

That is, when the subject is too bright, the aperture is tightened to reduce the amount of light, and when the subject is dark, the aperture is opened to increase the amount of light.

The diaphragm fully closing drive circuit 11 sends a motor drive signal to the motor 1 that allows the diaphragm device 3 to be fully closed by the motor 10.
This is a circuit that supplies 0.

The changeover switch 12 has a contact a that connects the automatic diaphragm control circuit to the motor 10 and a contact d that connects the diaphragm fully closed drive circuit 11 to the motor 10.

This selector switch 12 is connected to the video signal supply circuit 5.
The switching operation is performed in conjunction with the playback monitor setting switch 13 in .

That is, when an external video signal obtained from a VTR as an external device is selected in the video signal supply circuit 5 and this external video signal is supplied to the cathode ray tube display device 15 in the viewfinder section 16, the changeover switch 12 The contact 5 is turned on, while the display signal supply device 5 is turned on.
At this point, the camera output signal based on the output of the image pickup tube 2, that is, the internal video signal, is selected, and when this internal video signal is being supplied to the cathode ray tube display device 15, the contact a of the changeover switch 12 is turned on.

Note that the switch 1 shown in the video signal supply circuit 5
The switch 4 operates in the opposite direction to the switch 13 and is turned on when supplying the internal video signal to the display device 15.

In addition, the cathode ray tube display device 15 of the viewfinder section 16
is driven simultaneously with the image pickup tube 2, and the cathode ray tube display device 15
The image pickup tube 2 is also configured to operate during the operation.

In the apparatus configured as described above, when an object is imaged by the video camera and recorded by the VTR, the switch 13 is opened, the contact a of the changeover switch 12 is closed, and the switch 14 is closed. has been admonished.

Therefore, the viewfinder section 16 is in a video camera monitor state.

Further, an automatic diaphragm device consisting of a diaphragm device 3 and a motor 10 is controlled by the output of an amplifier 9 so as to achieve an optimum diaphragm state.

When a predetermined image capturing is completed and it is desired to play back what was recorded on the VTR, the switch 13 is closed.

As a result, the changeover switch 12 is operated, and the contact point a is opened and the contact point is closed.

Also, switch 14 is opened.

As a result, the playback output of the VTR, ie, the external video signal, is sent to the viewfinder section 16 and to the Kerfraun tube display device 15.

The reproduced image is then displayed on the viewfinder section 16.

At the same time, contact a of the changeover switch 12 is opened,
The contacts are closed.

As a result, the automatic diaphragm loop is interrupted, the diaphragm fully closing drive circuit 11 is connected to the motor 10, and the motor 10 is driven to fully close the diaphragm of the diaphragm device 3.

Therefore, no external light enters the image pickup tube 2.

Therefore, since the external video signal monitor (VTR monitor) is displayed in the viewfinder unit 16, the electron beam is scanned in the image pickup tube 2 while the power of the video camera is on, and a strong light is emitted. Even if you receive it,
The image pickup tube 2 is not exposed to light, and problems such as deterioration and burnout of the photoelectric conversion surface of the image pickup tube do not occur.

Since the automatic diaphragm device is used to block the incident light, the configuration of the camera is simplified.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and can be further modified.

For example, it is applicable to devices other than the motor 10 that perform automatic aperture control.

Further, the amplifier 9 is always connected to the motor 10, and a switch is provided between the fully closed drive circuit 11 and the motor shaft 10, and the V
This may be closed at the same time as the TR monitor.

[Brief explanation of the drawing]

The drawing is a circuit diagram of a video system showing one embodiment of the present invention. Also, in the symbols used in the drawings, 1 is a lens,
2 is an image pickup tube, 3 is an aperture device (iris), 4 is a video amplifier, 5 is a video signal supply circuit, 6 is a detection circuit, 7 is a reference circuit, 8 is a comparison circuit, 9 is an amplifier, 10 is a motor, 1
1 is a fully closed drive circuit, 12 is a changeover switch, 13 is a switch, 14 is a switch, 15 is a cathode ray tube display device, 16
is the viewfinder section.

Claims (1)

[Claims for Utility Model Registration] An image pickup tube, an automatic aperture device that adjusts the amount of light entering the image pickup tube, a viewfinder section having a monitor display device that is driven simultaneously with the image pickup tube, and the image pickup tube. a video signal supply circuit that selectively supplies an internal video signal based on the output of the camera and an external video signal based on the output of the external device to the monitor display device; an automatic aperture control signal forming circuit provided between the image pickup tube and the aperture device to automatically adjust the aperture amount; and an aperture fully closing drive for fully closing the aperture in the aperture device. A video camera comprising: a fully closed diaphragm drive circuit that generates a signal; and a switch that connects the fully closed diaphragm drive circuit to the diaphragm device in response to selection of the external video signal in the video signal supply circuit.