Patent ID: 7129628

Claim:
A velocity modulation coil apparatus to be provided on an outer circumferential surface of a funnel of a cathode-ray tube, comprising: a pair of velocity modulation coils for modulating a horizontal deflection velocity of an electron beam emitted from an electron gun, and a pair of magnetic substances, wherein the pair of velocity modulation coils are placed with a horizontal plane, including a tube axis of the cathode-ray tube, interposed therebetween, the pair of magnetic substances are placed with a vertical plane, including the tube axis of the cathode-ray tube, interposed therebetween, the pair of velocity modulation coils includes a straight line portion extending substantially in parallel to the tube axis of the cathode-ray tube, the straight line portion is placed between the pair of magnetic substances and the tube axis of the cathode-ray tube, an interval D between the magnetic substance and the straight line portion is 1 to 3 mm, and assuming that the tube axis of the cathode-ray tube is a Z-axis, a position of an end of the velocity modulation coil on a side opposite to a phosphor screen in a tube axis direction is Z=0, and a position of an end of the velocity modulation coil on a phosphor screen side in the tube axis direction is Z=L, a coordinate Z M at a center point of the magnetic substance in the tube axis direction satisfies a relationship: 0.2 ×L≦Z M ≦0.9 ×L.