Apparatus for increasing signal to noise ratio in television low light level scenes

Claim 5

A method as defined in claim 1 comprising the further step of causing the beam to scan, during each trace interval of the beam, a band of the target electrode which includes the target strip associated with said trace interval and at least part of one adjacent target strip.

Claim 6

In combination with a television camera tube having a target electrode for providing an electrically detectable image of the scene being televised, means for producing an electron beam substantially focused on the target electrode, and means for repetitively deflecting the beam linearly across the target electrode at a predetermined line scanning rate so as to cause the beam to scan successive parallel strips of the target electrode during successive trace intervals of said beam, the improvement comprising blanking means selectively connected to said beam producing means for blanking the beam during the trace interval at least one line scanning period at regular intervals between intervening individual line scanning periods when the beam is active during the trace interval.

Claim 7

In combination with a television camera tube having a target electrode for providing an electrically detectable image of the scene being televised, means for producing an electron beam substantially focused on the target electrode, and means for repetitively deflecting the beam linearly across the target electrode at a predetermined line scanning rate so as to cause the beam to scan successive parallel strips of the target electrode during successive trace intervals of said beam, the improvement comprising blanking means selectively connected to said beam producing means for blanking the beam during the trace interval at least one line scanning period at regular intervals between intervening individual line scanning periods when the beam is active during the trace interval.

Claim 8

An arrangement as defined in claim 3 further comprising means associated with said tube to defocus the beam for causing the diameter of the beam at the target electrode to be greater than the distance between the center lines of adjacent target strips.

Claim 9

An arrangement as defined in claim 3 wherein said blanking means comprise a bistable multivibrator connected to receive the horizontal driving pulses normally applied to said camera tube so as to cause its output state to change in response to each successive horizontal driving pulse, said multivibrator having its output connected to said electron beam producing means for blanking the electron beam whenever the output of the said multivibrator is in one of its states.

Claim 10

An arrangement as defined in claim 5 wherein said camera tube further includes a blanking amplifier connected to control the production of the electron beam, and an OR gate having its output connected to said blanking amplifier and having one input selectively connectable to the output of said multivibrator.

Claim 11

An arrangement as defined In claim 5 further comprising: an ANDNOT gate having an output connected to the input of said multivibrator, a direct input connected to receive the horizontal driving pulses normally applied to said tube, and a negated input; an AND gate having an output connected to said negated input of said ANDNOT gate and having two inputs; a three stage binary counter having its third stage output connected to one input of said AND gate and having its input connected to receive the vertical driving pulses normally applied to said tube; and a monostable multivibrator having an output connected to the other input of said AND gate and an input connected to receive the vertical driving pulses normally applied to said tube, said monostable multivibrator being arranged to produce an output pulse having a duration substantially equal to one trace interval of said beam in response to the appearance of each vertical driving pulse.

Claim 12

An arrangement as defined in claim 5 further comprising means connected to said bistable multivibrator for blocking the delivery of one horizontal driving pulse to said multivibrator at the start of each field scanning period of every other group of four field scanning periods of said tube.