Video camera, printer apparatus and method of controlling same, and apparatus and method for detecting print inhibit signal

A video camera comprising:

• shutter implementing device periodically performing exposure one time at a relatively high shutter speed for every n successive frames and for performing exposure n-1 times at an ordinary shutter speed, relatively longer than the relatively high shutter speed, wherein n is an integer;
• photographic device outputting a first video signal when exposure is performed at the ordinary shutter speed and a second video signal when exposure is performed at the relatively high shutter speed;
• an amplifier circuit amplifying the first and second video signals, outputted by said photographic device, at mutually different amplification factors such that an average level of the second video signal becomes approximately equal to an average level of the first video signal;
• flicker discriminator discriminating whether or not a difference between average levels of video signals representing two successive frames among the video signals amplified by said amplifier circuit is greater than a predetermined threshold value and for detecting when the difference is greater than the predetermined threshold value, thereby determining that flicker is caused in the video signal by an illuminating light;
• and
• controller, responsive to said flicker discriminator determining that flicker is caused in the video signal by the illuminating light, for controlling said shutter implementing device such that the relatively high shutter speed in said shutter implementing device is lowered to equal to the ordinary shutter speed.

A method of controlling a video camera, comprising the steps of;

• periodically performing exposure one time at a relatively high shutter speed for every n successive frames and performing exposure n-1 times at an ordinary shutter speed, relatively longer than the relatively high shutter speed, wherein n is an integer;
• obtaining a first video signal when exposure is performed at the ordinary shutter speed and a second video signal when exposure is performed at the relatively high shutter speed;
• amplifying the first and second video signals at mutually different amplification factors such that an average level of the second video signal becomes approximately equal to an average level of the first video signal;
• discriminating whether or not a difference between average levels of video signals representing two successive frames in the amplified video signals is greater than a predetermined threshold value, thereby determining that flicker is caused in the video signal by an illuminating light;
• and
• changing the relatively high shutter speed and the ordinary shutter speed to be identical shutter speeds that corresponds to a reciprocal of a positive whole-number multiplied by a period of an AC power supply of a light source generating the illuminating light, and making the amplification factors of the first and second video signals identical, in response to the determining that flicker is caused in the video signal by the illuminating light.