Automatic peak video control system

Claim 2

An automatic peak-video control system for a camera tube having light level controlling means and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said camera tube, said sensing means comprising a peak detector circuit for receiving said video signal output and sampling means coupled to said peak detector circuit for sampling the signal therein at least once during each field scan of said tube; means coupled to said sensing means for producing a voltage for controlling said light level controlling means in response to said sensed peak level; and means for decoupling said peak detector circuit from said video signal output during the blanking interval of said video signal.

Claim 3

The system of claim 1 further comprising logic means for causing said sampling means to sample and for resetting said peak detector circuit during the vertical blanking interval of said video signal.

Claim 4

The system Of claim 1 wherein said camera tube comprises a vidicon and said light level controlling means comprises the target of said vidicon.

Claim 5

The system of claim 3 further comprising means coupled between said vidicon and said peak detector circuit for restoring a DC level to said video signal.

Claim 6

The system of claim 1 wherein said controlling means comprises means for providing a reference signal, means for comparing said sensed peak level with said reference signal, and amplifier means for amplifying the difference therebetween, the output of said amplifier means comprising said control voltage.

Claim 7

The system of claim 5 wherein said camera tube comprises a vidicon, said light level controlling means comprises the target of said vidicon, and said control voltage comprises the target voltage of said vidicon.

Claim 8

The system of claim 6 further comprising clipping means coupled to said amplifier means for limiting the magnitude of said target voltage to a predetermined value.

Claim 9

An automatic peak-video control system for a camera tube having light level controlling means and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said camera tube; means coupled to said sensing means for producing a voltage for controlling said light level controlling means in response to said sensed peak level; means for producing a complementary voltage equal in magnitude but opposite in polarity to said control voltage; and means for applying said complementary voltage to said sensing means.

Claim 10

An automatic peak-video control system for a camera tube having light level controlling means and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said camera tube; means coupled to said sensing means for producing a voltage for controlling said light level controlling means in response to said sensed peak level; means for producing a complementary voltage equal in magnitude but opposite in polarity to said control voltage; and means for applying said complementary voltage to said sensing means.

Claim 11

The system of claim 6 wherein said amplifier means comprises a field effect transistor.

Claim 12

An automatic peak-video control system for a camera tube having light level controlling means and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said camera tube, said sensing means comprising a peak detector circuit for receiving said video signal output and sampling means coupled to said peak detector circuit for sampling the signal therein at least once during each field scan of said tube; means coupled to said sensing means for producing a voltage for controlling said light level controlling means in response to said sensed peak level; logic means for causing said sampling means to sample and for resetting said peak detector circuit during the vertical blanking interval of said video signal, said logic means being responsive to vertical drive pulses; and means responsive to said drive pulses for delaying vertical retrace of said tube.

Claim 13

An automatic peak-video control system for a camera tube having light level controlling means and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said camera tube, said sensing means comprising a peak detector circuit for receiving said video signal output and sampling means coupled to said peak detector circuit for sampling the signal therein at least once during each field scan of said tube; means coupled to said sensing means for producing a voltage for controlling said light level controlling means in response to said sensed peak level; logic means for causing said sampling means to sample and for resetting said peak detector circuit during the vertical blanking interval of said video signal, said logic means being responsive to vertical drive pulses; and means responsive to said drive pulses for delaying vertical retrace of said tube.

Claim 14

An automatic peak-video control system for a vidicon camera tube having a target the target voltage of which controls the light level of said vidicon and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said vidicon tube; means coupled to said sensing means for controlling the target voltage of said vidicon, said controlling means comprising means for providing a reference signal, means for comparing said sensed peak level with said reference signal, and amplifier means for amplifying the difference therebetween, the output of said amplifier means comprising said target voltage; and means coupled to said amplifier means for producing a complementary voltage equal in magnitude but opposite in polarity to said target voltage.

Claim 15

An automatic peak-video control system for a vidicon camera tube having a target the target voltage of which controls the light level of said vidicon and a video signal output comprising: means for sensing the peak level of said video signal output during each field scan of said vidicon tube; means coupled to said sensing means for controlling the target voltage of said vidicon, said controlling means comprising means for providing a reference signal, means for comparing said sensed peak level with said reference signal, and amplifier means for amplifying the difference therebetween, the output of said amplifier means comprising said target voltage; and means coupled to said amplifier means for producing a complementary voltage equal in magnitude but opposite in polarity to said target voltage.

Claim 16

The system of claim 11 further comprising a capacitor coupled to the output of said vidicon, and means coupling said complementary voltage to the side of said capacitor remote from said vidicon.

Claim 17

The system of claim 12 wherein said sensing means includes an amplifier for receiving said video signal output and wherein a capacitor is provided for coupling said amplifier to said tube, said complementary voltage being applied to said amplifier on the side of said capacitor remote from said tube. 14 The system of claim 13 wherein said tube is a vidicon and Said control voltage is the target voltage of said vidicon.