Image-converter tube with output fluorescent screen assembly resiliently mounted

Claim 1

IN AN IMAGE CONVERTER TUBE HAVING A SEALED ENVELOPE, A PHOTOCATHODE IN THE ENVELOPE NEAR AN INPUT END THEREOF, AN IMAGE-FORMING OUTPUT SCREEN ASSEMBLY IN THE ENVELOPE NEAR AND SPACED FROM AN OUTPUT END THEREOF, AND ELECTRONOPTICAL MEANS IN THE ENVELOPE FOR DIRECTING PHOTO-ELECTRONS FROM THE PHOTOCATHODE ON TO AN INNER SURFACE OF SAID OUTPUT SCREEN TO FORM AN IMAGE PATTERN THEREON, THE IMPROVEMENT COMPRISING MEANS SUPPORTING SAID OUTPUT SCREEN ASSEMBLY AT A PRESCRIBED SPACING FROM SAID OUTPUT END OF THE TUBE INCLUDING SPRING MEANS RESILIENTLY PRESSING THE OUTPUT SCREEN ASSEMBLY AGAINST ITS SUPPORTING MEANS AN ANNULAR DUST-SHIELD MEMBER POSITIONED IN THE SPACE BETWEEN THE OUTPUT SCREEN ASSEMBLY AND THE OUTPUT END OF THE ENVELOPE AND HAVING ONE MARGINAL PORTION SEALINGLY ENGAGING THE PERIPHERY OF THE SCREEN ASSEMBLY AND ANOTHER MARGINAL PORTION SEALINGLY ENGAGING THE INNER SURFACE OF SAID ENVELOPE SO AS TO SEAL OFF SAID SPACE FROM THE GENERAL CAVITY OF THE TUBE ENVELOPE AGAINST INGRESS OF FOREIGN PARTICLES THEREINTO.