Adjustable x-ray field defining cone and field size indicating means

Claim 1

AN X-RAY CONE ASSEMBLY COMPRISING A HOUSING HAVING OPENINGS AT OPPOSITE ENDS FOR PASSING AN X-RAY BEAM THERETHROUGH, MECHANISM SUPPORT MEANS WITHIN THE HOUSING, PAIRS OF SHUTTER BLADES WHOSE EACH BLADE IN A PAIR IS MOUNTED ON THE SUPPORT MEANS FOR MOVEMENT THROUGH AN ANGLE OPPOSED TO THE OTHER SHUTTER BLADE FOR DEFINING CROSSSECTIONAL DIMENSIONS OF THE X-RAY BEAM, FIRST AND SECOND PULLEY MEANS ATTACHED REPECTIVELY TO EACH BLADE IN EACH PAIR FOR ROTATION THEREWITH, CABLE MEANS COUPLING SAID FIRST AND SECOND PULLEY MEANS TO EACH OTHER FOR JOINT ROTATIONAL MOVEMENT OF EACH BLADE IN EACH PAIR, MEANS FOR DRIVING SAID BLADES IN A PAIR THROUGH AN ANGLE, A FIELD DIMENSION INDICATING DEVICE INCLUDING A FIELD DIMENSION SCALE MEANS, SAID SCALE MEANS FOR EACH DIMENSION OF THE FIELD COMPRISING A SINGLE ROTATABLY MOUNTED DRUM MEANS HAVING ITS AXIS PARALLEL WITH A SIGHT OPENING IN THE HOUSING FOR PERMITTING VISUALIZATION OF THE DRUM FROM THE OUTSIDE OF THE HOUSING, SAID DRUM MEANS HAVING FIELD DIMENSION SCALES SPACED APART AND IN PARALLELISM WITH EACH OTHER ON THE PERIPHERY OF THE DRUM, EACH OF SAID SCALES HAVING ADJACENT TO IT A FOCAL SPOT DISTANCE INDICIA DIRECTLY ON THE DRUM, AN INDICATOR POINTER MEANS FOR EACH PAIR OF COACTING BLADES THAT IS TRANSLATABLE ALONG THE SCALE IN ACCORDANCE WITH SHUTTER BLADE MOVEMENT, MEANS COUPLING AN INDICATOR POINTER MEANS FOR ONE FIELD DIMENSION WITH CORRESPONDING SHUTTER BLADES, SAID LAST NAMED COUPLING MEANS COMPRISING PULLEYS CARRIED BY THE SHUTTER BLADES, STATIONARY PULLEYS, A CORD THAT IS ATTACHED AT ITS ENDS AND RUNS AROUND SAID PULLEYS, SAID INDICATOR POINTER MEANS BEING ATTACHED TO THE CORD IN A REGION BETWEEN PULLEYS THAT IS AT LEAST COEXTENTIVE WITH THE LENGTH OF THE DIMENSION SCALES.