JPS58156274A - Video camera - Google Patents

Abstract

PURPOSE:To facilitate a still image pickup, by providing an auxiliary sensor which is always irradiated by the pickup light to an optical system, and using the detection output fed from the auxiliary sensor as a control signal to set automatically the exposure quantity. CONSTITUTION:Iris mechanisms 2 and 3, a half mirror 5, a shutter mechanism 6, a zoom lens 1 and a main lens 4 are provided to an optical path of an image pickup light which irradiates a solid state image sensor 7. When a mode command signal indicating a still image pickup is supplied to a system controller 10, the mechanisms 2 and 3 are kept open with the mechanism 6 closed respectively. The mechanism 2 interlocks the mechanism 6 with interlocking to the operation of a shutter button, and the still image pickup is performed by an image sensor 7. The mechanism 2 is controlled so as to apply a proper exposure quantity corresponding to the shutter speed and on the basis of the detection output given from an auxiliary sensor 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video camera having both a still imaging function and a movie imaging function, and more particularly to a video camera capable of automatically setting the exposure amount of an image sensor in a still imaging special program.

- Second, the video camera has a 5il image sensor on its image sensor.
1 light is constantly irradiated, and 1 field period or 1
By reading out the fist image output from the above-mentioned image sensor every frame period, continuous imaging, that is, movie imaging is performed, and a video signal conforming to a predetermined standard television system is output. That is,
For example, in an NTSC video camera, the imaging output is read out from the image sensor every 1 second or every τ second, so a fixed value corresponding to the repetition period of the readout operation (1 second or τ seconds) of the upper 18m5 output is Movie H is being played at shutter speed.

By the way, when capturing still images with a video camera that captures images at a shutter speed fixed to 0 at 2 seconds or 90 seconds as described above, especially when trying to capture still images of a moving subject, There is a risk that the image may become blurry due to the scratches. Therefore,
In a video camera that captures still images, it is necessary to be able to set the shutter speed arbitrarily and variably. Furthermore, when the shutter speed is varied, the exposure amount of the image sensor changes, so it is necessary to control the aperture of the optical system according to the shutter speed.

Therefore, the present invention provides an iris mechanism that adjusts the amount of imaging light, an optical shutter that opens and closes an optical path through which the imaging light passes, an image sensor that is exposed to light when the shutter is opened, and at least one of the imaging lights. The optical system includes an auxiliary sensor, a part of which is always illuminated, and the exposure amount is automatically set using the detection output from the auxiliary sensor as a control signal, and still images are captured by the image sensor, and the shutter is in the open state. The object of the present invention is to provide a video camera having a novel configuration, which is a video camera equipped with an imaging operation means for performing movie imaging using the image sensor while holding the video camera.

Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment.

The embodiment shown in FIG. 1 is a charge-coupled device (CCD: Ch
The present invention is applied to an NTSC color video camera using a solid-state image sensor 7 formed in a large CoupledDevice, so that it can perform normal movie imaging operations and still imaging operations using a so-called shutter speed priority automatic control system. This is what I did.

In this embodiment, the optical path of the imaging light irradiated to the solid-state image sensor 7 includes first and second iris mechanisms 2°3 that adjust the amount of the imaging light, and a part of the imaging light that is transmitted to the auxiliary sensor. 8, a shutter mechanism 6 for opening and closing this optical passage, and a zoom lens 1 and a main lens 4 for forming a subject image by imaging light on the light receiving surface of the solid-state image sensor 7. It is being

The solid-state image sensor 7 is driven by a drive clock from the sensor drive section 11, performs, for example, a frame transfer type imaging operation, and samples and samples the imaging output.
The signal is supplied to the AGC circuit 22 via the hold circuit 21.

The solid-state image sensor 7 performs color imaging, and is provided with, for example, a striped color coding filter on its imaging surface, although not shown. The sensor driving section 11 forms a driving clock synchronized with a synchronizing signal in an NTSC television signal based on a system clock supplied from the system controller 10, and drives the solid-state image sensor 7 using this driving clock. Note that the sample hold circuit 21 provided at the output of the solid-state image sensor 7 is connected to the sensor drive circuit 11.
A sampling pulse is supplied from the solid-state image sensor 7, and a sample hold operation is performed in synchronization with the imaging operation of the solid-state image sensor 7.

Further, the AGC circuit 22 to which the imaging output signal is supplied via the sample and hold circuit 21 is composed of, for example, a voltage-controlled variable gain amplifier, and the AGC circuit 22 is configured to adjust the gain according to the control voltage supplied via the switch 30. The imaging output signal is amplified and its output is supplied to the process processing circuit 23 and also to the first and second detection circuits 31 and 32.

The first and second detection circuits 31 and 32 are for obtaining control signals for automatically controlling the AGC circuit w622 and the second iris mechanism 3 in the movie imaging operation. The detection output of the second detection circuit 32 is supplied to the AGC circuit 22 via the switch 30, and the detection output of the second detection circuit 32 is supplied to the second drive control circuit 12 via the second drive control circuit 12.
The iris drive 05] is supplied to the iris drive path 13. The AGC circuit 22 is supplied with a predetermined control voltage from a gain setting power source 35 via a switch 30 during still imaging operation, and is configured to amplify the imaging output signal with a predetermined gain.

Further, the process processing circuit 23 includes the AGC circuit 22
The imaging output signal supplied via the NT8
The signal is output via the C encoder 24 as an NTSC color television signal. Although not shown, the process processing circuit 23 is equipped with a white balance adjustment function using, for example, a voltage-controlled variable gain amplifier.
The signal levels of the three primary color signal components in the image pickup output signal are compared and detected. White balance adjustment is performed based on the detection output of the white balance detection circuit 37. When a white balance command signal is supplied to the system controller 10 by operating a white balance switch (not shown) while imaging a standard white subject in the movie imaging mode, the white balance detection circuit 37 detects a white balance command signal in the imaging output signal. The signal levels of the three primary color signal components are compared and detected, and the detected output controls the gain of the variable gain amplifier in the process processing circuit 23 so that the signal levels are equal to each other, and automatically adjusts the white balance. It works like this. The detection output of the white balance detection circuit 37 in a state where the white balance is maintained normally is stored in the memory 38, and the white balance tonality function of the process processing circuit 23 is activated by the stored contents of the memory 38. ing.

Further, the auxiliary sensor 8, which is constantly irradiated with imaging light, supplies a detection output signal corresponding to the amount of imaging light to the third detection circuit 42 via the amplifier 41. The detection output of the third detection circuit 42 is supplied to the first iris drive unit 15 via the first drive control circuit 14, and is used to control the first iris mechanism 2 during still imaging operation. .

Furthermore, the shutter mechanism 6 provided in the optical path that guides the imaging light to the solid-state image sensor 7 is driven by a shutter drive unit 16 that is activated by a shutter control signal from the system control 10. Here, the shutter mechanism 6 is held in an open state in the movie imaging mode, and in a closed state in the still imaging mode, and is opened only for a set exposure period that is completed by operation of a shutter button (not shown). . The operation of the shutter mechanism 6 in the still imaging mode is performed by supplying a shutter command signal to the system controller 1o by operating the shutter button.
This is performed at a timing synchronized with the imaging operation of the solid-state image sensor 7 and at an arbitrary shutter speed that is set.

Here, the first iris mechanism 2 operates by capturing a still image. The second iris mechanism 3 controls the amount of imaging light in the movie imaging mode, and maintains an open state in the still imaging mode, and responds to the detection output from the second detection circuit 32 in the movie imaging mode. The drive is controlled continuously.

In the embodiment configured as described above, by supplying a mode command signal instructing a movie imaging operation to the system controller 10, the second iris mechanism is activated while the first iris mechanism 2 and the shutter mechanism 6 are open. 3, movie imaging is performed while maintaining the appropriate amount of imaging light irradiated to the solid-state image sensor 7, and the AGC circuit 2
2, it is possible to obtain an imaging output signal with an appropriate signal level.

Furthermore, when a mode command signal for commanding a still imaging operation is supplied to the system controller 1o, the first and second iris mechanisms 2 and 3 are held open, the shutter mechanism 6 is closed, and the shutter button is not operated. The first iris mechanism 2 and the shutter mechanism 6 are operated in conjunction with each other to allow the solid-state image sensor 7 to take a still image. In this still imaging mode, the first iris mechanism 2 is automatically controlled based on the detection output from the auxiliary sensor 8 to provide an appropriate amount of exposure according to the shutter speed, resulting in so-called automatic shutter speed priority control. It is possible to perform still imaging. During this still imaging, by reading the imaging output from the solid-state image sensor 7 with the shutter mechanism 6 closed, it is possible to prevent the so-called smear phenomenon and blooming phenomenon. Further, it is also possible to perform frame still imaging by reading out the imaging output for one frame from the solid-state image sensor 7.

The still imaging output signal obtained by the solid-state image sensor 7 is output as an NTSC color television signal via the NTSC encoder 24, and is supplied to a magnetic recording reproduction device using, for example, a rotating magnetic disk.
Still images can be played back on the screen of the monitor television receiver as the playback video signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a video camera according to the present invention. 2.3...Iris mechanism 5...Half mirror 6...
・・・・・・Shirt Mechanism 7・・・・・・・・・・・・
Solid-state image sensor 8...Auxiliary sensor 10...System controller 11
......Sensor drive unit 12.14...Drive control unit 13.15...Iris drive unit 16...
...Shutter drive unit 22...AGC
Circuit 23...Process processing circuit 24...
...Encoder

Claims (1)

[Claims] an iris mechanism that adjusts the amount of imaging light; an optical shutter that opens and closes an optical path through which the imaging light passes; an image sensor that is exposed to light when the shutter is opened; and at least a portion of the imaging light that is always irradiated. The optical system includes an auxiliary sensor that uses the detection output from the auxiliary sensor as a control signal to automatically set the exposure amount, captures a still image using the image sensor, and maintains the shutter in an open state to capture the image. A video camera equipped with an imaging operation control means that performs movie imaging using a sensor.