Cathode ray tubes

Claim 1

A CATHODE RAY TUBE EMBODYING A TRANSPARENT FACE PORTION HAVING A FLUORESCENT SCREENADJACENT ITS INNER SURFACE, ELECTRON DISCHARGE MEANS FOR DIRECTING A BEAM OF ELECTRONS ONTO SAID FLUORESCENT SCREEN TO PRODUCE A LUMINOUS SPOT THEREON, AND A TRANSPARENT COVER ELEMENT DISPOSED OVER SAID FACE PORTION AND HAVING AN OUTER SURFACE WHICH WOULD NORMALLY REFLECT LIGHT RAYS FROM SAID LUMINOUS SPOT BACK TO THE SCREEN SO AS TO RE-ILLUMNINATE PORTIONS THEREOF, AND A TRANSPARENT REFLECTION-REDUCTION AND LIGHT-TRANSMISSION INCREASING COATING ON SAID SURFACE FOR REDUCING SURFACE REFLECTIONS FROM AN EXTERNAL SOURCE OF ILLUMINNATION AND FOR SIMULTANEOUSLY INCREASING TRANSMISSION OF SAID LIGHT RAYS EMITTING FROM SAID LUMINOUS SPOT THROUGH THE OUTER SURFACE OF SAID ELEMENT WHEREBY UNDESIRABLE ILLUMINATION OF SAID FLUORESCENT SCREEN BY SAID LIGHT RAYS WHICH WOULD OTHERWISE BE REFLECTED BACK BY SAID SURFACE TO THE SCREEN IS SUBSTANTIALLY REDUCED AND THE CONTRACT DISCRIMINATION OF AN IMAGE PRODUCED ON SAID TUBE SURFACE BY SAID LUMINOUS SPOT IS GREATLY IMPROVED, SAID TRANSPARENT COATING COMPRISING A THIN LAYER OF SUB-MICROSCOPIC, DISCRETE, MICRO-GRANULAR, TRANSPARENT SOLID PARTICLES FORMING MINUTE IRREGULARITIES ON SAID OUTER SURFACE, THE CONCENTRATION OF SAID PARTICLES IN THE IRREGULARITIES DECREASING FROM SAID OUTER SURFACE OUTWARDLY AND THE MATERIAL OF SAID PARTICLES BEING SUCH THAT THE EFFECTIVE INDEX OF REFRACTION OF SAID COATING VARIES SUBSTANTIALLY FROM UNITY AT THE COATING-AIR INTERFACE TO AN INDEX VALUE WHICH PROGRESSIVELY INCREASES IN A DIRECTION INWARDLY OF SAID COATING AND APPROACHES THE INDEX OF REFRACTION OF THE MATERIAL OF THE COVER ELEMENT.