Television camera system having improved temperature control

Claim 1

A TELEVISION CAMERA SYSTEM COMPRISING IN COMBINATION A CAMERA TUBE AND A CASING SURROUNDING THE TUBE, AND TEMPERATURE-CONTROL MEANS COMPRISING AN INLET CONDUIT AND AN OUTLET CONDUIT CONNECTED WITH RESPECTIVE END PARTS OF SAID CASING; FLUID CIRCULATING MEANS ASSOCIATED WITH SAID INLET CONDUIT AND OPERABLE TO CIRCULATE FLUID THERETHROUGH INTO SAID CASING; HEATING MEANS ASSOCIATED WITH SAID OUTLET CONDUIT AND OPERABLE TO HEAT FLUID ISSUING THERETHROUGH OUT OF SAID CASING; VALVE MEANS HAVING A PORTED VALVE HOUSING WITH A FIRST PORT CONNECTED TO SAID OUTLET CONDUIT BEYOND AN OUTLET END OF SAID HEATING MEANS, A SECOND PORT CONNECTED TO SAID INLET CONDUIT AHEAD OF AN INLET OF SAID FLUID CIRCULATING MEANS, AND A THIRD AND A FOURTH PORTS CONNECTED TO ATMOSPHERE; AND A VALVE MEMBER DISPLACEABLE IN THE VALVE HOUSING BETWEEN A FIRST POSITION IN WHICH SAID FIRST AND SECOND PORTS ARE INTERCONNECTED AND SEALED FROM SAID THIRD AND FOURTH PORTS AND A SECOND POSITION IN WHICH SAID FIRST AND FOURTH PORTS ARE INTERCONNECTED AND SAID SECOND AND THIRD PORTS ARE INTERCONNECTED AND SEALED FROM SAID FIRST AND FOURTH PORTS, AND THROUGH A RANGE OF INTERMEDIATE POSITIONS IN WHICH SAID FIRST PORT IS CONNECTED PARTLY TO SAID SECOND AND PARTLY TO SAID FOURTH WHILE SAID THIRD PORT IS CONNECTED TO SAID SECOND PORT, WHEREBY TO CIRCULATE AIR PAST THE TUBE AT A VARIABLE TEMPERATURE DETERMINED BY THE POSITION OF THE VALVE MEMBER.