Patent ID: 6870575

Claim:
A screen-noise eliminating apparatus comprising: a beam-spot-length control element for controlling the vertical length of a beam spot on a display screen generated by an electron beam of a cathode-ray tube for displaying a TV signal, said beam-spot-length control element operating to create a beam spot in a first state when a number of scanning lines in the TV signal exceeds a certain number, and operating to create a beam spot in a second state when a number of scanning lines in the TV signal is less than a certain number, wherein the beam spot has a greater vertical beam length in said second state than in said first state; a vertical enhancement element for enhancing a given vertical-direction spatial frequency characteristic of said TV signal; and a noise elimination control element for controlling said beam-spot-length control element and said vertical enhancement element so as to compensate said vertical-direction spatial frequency characteristic according to the beam spot length resulting from operation of said beam-spot-length control element.