High writing speed dark-trace tube with flood beam enhancement

Claim 1

A DARK-TRACE CATHODE RAY TUBE COMPRISING AN EVACUATED ENVELOPE WITH A TRANSPARENT FACEPLATE, SCREEN MEANS MOUNTED WITHIN SAID ENVELOPE AND ADJACENT SAID FACEPLATE COMPRISING A LAYER OF A PHOTOCHROMIC MATERIAL ON A TRANSPARENT ELECTRICALLY CONDUCTIVE SUPPORT AND A UV PHOSPHOR LAYER COATED ON SAID PHOTOCHROMIC MATERIAL LAYER ON THE SIDE OPPOSITE SAID FACEPLATE, A WRITING MEANS FOR SCANNING SELECTED AREAS OF SAID PHOTOCHROMIC SCREEN MEANS WITH ELECTRONS AND THUS CHANGING THE ELECTRIC POTENTIAL OF SELECTED AREAS IN SAID PHOTOCHROMIC SCREEN MEANS, A FLOODING MEANS FOR FLOODING SAID PHOTOCHROMIC SCREEN MEANS, WITH LOW ENERGY ELECTRONS TO MAINTAIN A BISTABLE POTENTIAL PATTERN AND PRODUCING DARKENING OF THE MORE POSITIVE AREAS, WHEREBY THE ELECTRONS FROM SAID WRITING MEANS FORM A CHARGE PATTERN ON SAID PHOSPHOR LAYER AND THE ELECTRONS FROM SAID FLOODING MEANS MAINTAIN A BISTABLE POTENTIAL PATTERN AND CAUSES SAID PHOSPHOR LAYER TO FLUORESCE IN ACCORDANCE WITH SAID CHARGE PATTERN WHEREIN SAID PHOTOCHROMIC MATERIAL DARKENS IN ACCORDANCE WITH THE FLUORESCENCE, A COLLECTOR MEANS POSITIONED ADJACENT TO SAID PHOTOCHROMIC SCREEN MEANS AND IN THE PATH OF ELECTRONS FROM SAID WRITING MEANS AND SAID FLOODING MEANS, THE SECONDARY EMISSION RATIO OF SAID PHOTOCHROMIC SCREEN MEANS BEING GREATER THAN UNITY AND SAID COLLECTOR MEANS SERVING TO COLLECT THE SECONDARY EMISSION ELECTRONS EMITTED FROM SAID PHOTOCHROMIC SCREEN MEANS WHEN SELECTED AREAS ARE SCANNED BY SAID WRITING MEANS TO ESTABLISH SAID BISTABLE POTENTIAL PATTERN AND FURTHER SERVING TO COLLECT THE SECONDARY EMISSION ELECTRONS FROM SAID PHOTOCHROMIC SCREEN MEANS WHEN SAID SELECTED AREAS ARE BOMBARDED BY ELECTRONS FROM SAID FLOODING MEANS THEREBY SHIFTING SAID SELECTED AREAS TO THE POTENTIAL OF SAID COLLECTOR MEANS, SAID PHOTCHROMIC SCREEN MEANS BEING INITIALLY UNIFORMLY CHARGED TO THE SAME POTENTIAL AS SAID FLOODING MEANS, SAID POTENTIAL BEING NEGATIVE WITH RESPECT TO SAID COLLECTOR MEANS BUT SUBSTANTIALLY POSITIVE WITH RESPECT TO SAID WRITING MEANS, AND ERASE MEANS FOR ERASING THE DARK-TRACE PATTERN ON SAID PHOTOCHROMIC SCREENS MEANS COMPRISING TERMINAL MEANS CONNECTED TO SAID TRANSPARENT ELECTRICALLY CONDUCTIVE SUPPORT AND ADAPTED TO RECEIVE AN ERASE PULSE TO DEVELOP A UNIFORM NEGATIVE CHARGE PATTERN OVER SAID SCREEN MEANS.