JPH0629921B2 - Video camera - Google Patents

Description

The present invention relates to a video camera having a diaphragm unit with variable light transmittance.

FIG. 1 is a configuration diagram of an electric circuit system of a diaphragm means of a conventional video camera, in which an image of an object is formed on an image sensor 1 via a lens 2 and a diaphragm 3. The video signal output from the image pickup device 1 is amplified by the preamplifier 4 and output as a signal according to the subject by the brightness detection circuit 5, and the level is adjusted according to the level set by the level adjustment circuit 6, and the coil drive circuit 7 to control the electric current to flow through the aperture opening / closing device 8,
The opening / closing of the diaphragm 3 is automatically controlled. Further, in order to prevent hunting of the diaphragm 3, the diaphragm opening / closing device 8 is provided with a coil (not shown) for detecting the opening / closing speed of the diaphragm, and the detection signal is fed back to the coil drive circuit 7 via the braking circuit 9. Then, the diaphragm 3 is braked.

In this conventional diaphragm 3, the diaphragm for the amount of light is performed by opening and closing a plurality of blade members. However, if such a diaphragm 3 is provided in a video camera in which an interchangeable lens of a single-lens reflex camera can be mounted, an optical image that has passed through the lens 2 will not be adjusted in light amount by the diaphragm 3 and the image will be hidden. , The black part will be captured in the image as much as the aperture is narrowed down. Although it is possible to use the diaphragm of the interchangeable lens itself, it is mechanically impossible to automatically operate the diaphragm, and it is impossible to shoot with the interchangeable lens with the video camera as it is.

An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional apparatus, and to provide a video camera capable of using, for example, an interchangeable lens for a single-lens reflex camera, and its gist is a video camera having a built-in diaphragm. And a second interchangeable lens for a single-lens reflex camera equipped with a filter having an electro-optical effect in which the light transmittance is variable according to an electric signal are selectively attached and detached in front of the image sensor. A flexible video camera, which comprises a discriminating means for discriminating which of the first interchangeable lens and the second interchangeable lens is mounted, and the discriminating means for determining the first interchangeable lens.
If it is determined that the second interchangeable lens is attached, the aperture amount of the aperture is controlled based on the electric signal from the image pickup device, and the determining unit determines that the second interchangeable lens is attached. If the determination is made, the control means is provided for controlling the light transmittance of the filter based on the electric signal from the image pickup device.

The present invention will be described in detail based on the embodiment shown in FIG.

FIG. 2 shows an embodiment of the present invention, and the same reference numerals as those in FIG. 1 denote the same circuits.

The lens 2, the diaphragm 3, and the diaphragm opening / closing device 8 in front of the image sensor 1
The lens unit 10 having a lens can be exchanged with an interchangeable lens 14 for a single-lens reflex lens including a lens 11, an aperture 12, and a lens 13. The interchangeable lens 14 is attached to a video camera using a mount adapter 16 having a liquid crystal filter 15.

The video signal output from the image sensor 1 is the preamplifier 4,
The output from the brightness detection circuit 5 and the level adjustment circuit 6 is the same as in the conventional example shown in FIG. 1, but the output of the level adjustment circuit 6 is the coil drive circuit 17 and the liquid crystal drive circuit 18.
Is output to both. The output of the coil drive circuit 17 is output to the diaphragm opening / closing device 8 of the conventional lens unit 10 via the first switch 19, and the output of the liquid crystal drive circuit 18 is output to the second.
It is output to the liquid crystal filter 15 via the switch 20. Also, the switches 19 and 20 are the mount adapter 16
The presence or absence of the switch is switched via the detection circuit 21, and when the mount adapter 16 is not attached, the first switch 19 is turned on and the second switch 20 is turned off. In the opposite case, the first switch 19 is turned on. The switch 19 is turned off and the second switch 20 is turned on.

When the lens unit 10 attached to the video camera is attached, the first switch 19 is turned on and the switch 20 is turned off to control the diaphragm 3. This state is the conventional one shown in FIG. Since the function is the same as the example, the description is omitted.

Next, when the interchangeable lens for single-lens reflex lens 14 is attached using the mount adapter 16, the detection circuit 21 operates due to the attachment of the mount adapter 16, the first switch 19 is turned off, and the second switch 20 is turned on. When turned on, the light transmittance of the liquid crystal filter 15 provided on the mount adapter 16 is controlled.

Also in this case, as in the case of FIG. 1, the video signal from the image sensor 1 is sent to the liquid crystal drive circuit 18 via the preamplifier 4, the brightness detection circuit 5, and the level adjustment circuit 6, and the liquid crystal filter 1
A diaphragm means is implemented by changing the light transmittance of No. 5.

By doing so, it becomes possible to shoot with the interchangeable lens 14 for a single-lens reflex camera, which was impossible because the screen is blurred when the diaphragm is used to stop. When taking a picture with the interchangeable lens 14, it is desirable that the diaphragm 12 is fixed to about F8, which can bring out the maximum output of the lens.

In this embodiment, the liquid crystal filter is used as the diaphragm means for changing the light transmittance. However, if a substance having an electro-optical effect such as electrochromy or PLZT is used, the light transmittance is the same as that of the liquid crystal filter. A diaphragm means for changing Further, these members for changing the light transmittance may be always provided in front of the image pickup device 1 and the light transmittance may be changed as necessary.

As described above, the video camera according to the present invention makes it possible to use an interchangeable lens for, for example, a single-lens reflex camera by using a substance having an electro-optical effect capable of changing the light transmittance, which is not possible with a conventional video camera. It enables super telephoto and super wide-angle shooting.

[Brief description of drawings]

FIG. 1 is a block diagram of a diaphragm means of a conventional video camera, and FIG.
FIG. 1 is a block diagram showing an embodiment of a video camera according to the present invention. Reference numeral 1 is an image sensor, 2, 11, 13 are lenses, 3 is a diaphragm, 4 is a preamplifier, 5 is a brightness detection circuit, 6 is a level adjusting circuit, 10 is a lens unit, 14 is an interchangeable lens, 15 is a liquid crystal filter, 16 Is a mount adapter, 17 is a coil drive circuit, 18 is a liquid crystal drive circuit, 19 and 20 are switches,
Reference numeral 21 is a detection circuit.

Claims (1)

[Claims] 1. A first interchangeable lens for a video camera, which has a built-in diaphragm, and a second interchangeable lens for a single-lens reflex camera, to which a filter having an electro-optical effect of which light transmittance is variable by an electric signal is attached. A video camera that is selectively removable in front of the image pickup device, and a determination means for determining which of the first interchangeable lens and the second interchangeable lens is attached, When the discriminating means determines that the first interchangeable lens is attached, the diaphragm amount of the diaphragm is controlled based on an electric signal from the image pickup device, and the discriminating means controls the second interchangeable lens. And a control means for controlling the light transmittance of the filter based on an electric signal from the image pickup device when it is determined that the video camera is attached.