Camera tube residual image elimination apparatus

Claim 2

A video signal generating apparatus comprising an image pickup tube having a target adapted to receive a light image and electron beam generating means including a cathode and a grid for generating an electron beam directed towards said target to scan the surface thereof and in conjunction with said target convert the light received by said target into an electrical output which varies with the intensity of the light received by the areas of said target successively scanned by said beam so as to constitute a video signal; means connected to said tube for receiving a portion of said electrical output and for reversing the polarity of said output portion, and means for applying the polarityreversed output portion to both said cathode and grid simultaneously so as to modulate the voltage of said electron beam without changing the intensity of said beam, whereby to modify the voltage of said target for diminishing a residual image signal component of said video signal.

Claim 3

A video signal generating apparatus comprising an image pickup tube having a target adapted to receive a light image and electron beam generating means including a cathode and a grid for generating an electron beam directed towards said target to scan the surface thereof and in conjunction with said target convert the light received by said target into an electrical output which varies with the intensity of the light received by the areas of said target successively scanned by said beam so as to constitute a video signal; means connected to said tube for receiving a portion of said electrical output and for reversing the polarity of said output portion, and means for applying the polarity-reversed output portion to both said cathode and grid simultaneously so as to modulate the voltage of said electron beam without changing the intensity of said beam, whereby to modify the voltage of said target for diminishing a residual image signal component of said video signal.

Claim 4

A video signal generating apparatus comprising an image pickup tube having a target adapted to receive a light image and electron beam generating means including a cathode and a grid for generating an electron beam directed towards said target to scan the surface thereof and in conjunction with said target convert the light received by said target into an electrical output which varies with the intensity of the light received by the areas of said target successively scanned by said beam so as to constitute a video signal; means connected to said tube for receiving a portion of said electrical output and for reversing the polarity of said output portion, and means for applying the polarity-reversed output portion to both said cathode and grid simultaneously so as to modulate the voltage of said electron beam without changing the intensity of said beam, whereby to modify the voltage of said target for diminishing a residual image signal component of said video signal.

Claim 5

A video signal generating apparatus according to claim 1, including means for controlling the voltage level of said polarity-reversed output portion.

Claim 6

A video signal generating apparatus according to claims 1, which includes means for controlling the voltage level of said polarity reversed output portion, a plurality of color filters adapted to be sequentially disposed in front of said target and means for changing the level of said polarity-reversed output portion in accordance with which of said filters is disposed in front of said target whereby compensation is provided for different residual image components due to different colored lighT on the target.

Claim 7

A video signal generating apparatus according to claim 3, wherein said voltage line controlling means includes means establishing a reference level for each of said filters, said level changing means include a plurality of switches connected to respective reference levels of said voltage level controlling means and said switches are sequentially operated in synchronization with the sequential disposition of said color filters in front of said target to change the level of said polarity-reversed output portion in correspondence with the different filters.

Claim 8

A video signal generating apparatus according to claim 1, in which the voltage of the target is modified during the same frame of said video signal constituted by said electrical output.

Claim 9

A video signal generating apparatus according to claim 1, in which means are provided for effecting gamma correction of the polarity-reversed output portion applied to both said cathode and grid.

Claim 10

A video signal generating apparatus according to claim 1, in which means are provided for sensing the voltage of said target, and adding to said polarity-reversed output portion a signal proportional to said voltage, whereby variations of the residual image component due to variations of target voltage are removed.

Claim 11

A video signal generating apparatus according to claim 1, in which photoelectric conversion means are provided near said target for receiving light whose intensity is proportional to the light on said target and for adding an electric signal to said polarity-reversed signal output portion proportional to said received light, whereby variations of the residual image component due to variations in the amount of light incident on said target are removed.

Claim 12

A video signal generating apparatus comprising first and second image pickup tubes each having a target adapted to receive a light image and electron beam generating means including a cathode and a grid for generating an electron beam directed towards said target to scan the surface thereof and in conjunction with said target convert the light received by said target into an electrical output which varies with the intensity of the light received by the areas of the respective target successively scanned by the beam so as to constitute a video signal; means connected to said first one of said tubes for receiving a portion of said electrical output therefrom and for reversing the polarity of said output portion; and means for applying the polarity-reversed output portion to both said cathode and grid simultaneously of the electron beam generating means of the second of said tubes so as to modulate the voltage of said electron beam in said second tube without changing the intensity thereof, whereby to modify the voltage of the target of said second tube for diminishing a residual image signal component of the video signal from the second tube.

Claim 13

A video signal generating apparatus comprising first and second image pickup tubes each having a target adapted to receive a light image and electron beam generating means including a cathode and a grid for generating an electron beam directed towards said target to scan the surface thereof and in conjunction with said target convert the light received by said target into an electrical output which varies with the intensity of the light received by the areas of the respective target successively scanned by the beam so as to constitute a video signal; means connected to said first one of said tubes for receiving a portion of said electrical output therefrom and for reversing the polarity of said output portion; and means for applying the polarity-reversed output portion to both said cathode and grid simultaneously of the electron beam generating means of the second of said tubes so as to modulate the voltage of said electron beam in said second tube without changing the intensity thereof, whereby to modify the voltage of the target of said second tube for diminishing a residual image signal component of the video signal from the second tube.

Claim 14

A video signal generating apparatus according to claim 9, further including means for applying said polarity-reversed output portion of said first tube also to both said cathode and grid simultaneously of the electron beam generating means of said first tube.

Claim 15

A video signal generating apparatus according to claim 9, which further includes means for receiving a portion of the electrical output from said second tube and for producing a polarity-reversed second output portion therefrom, and means for applying said polarity-reversed second output portion of said second image pickup tube to both said cathode and grid simultaneously of the electron beam generating means of said first image pickup tube.