Achievement of High Picture Quality in Color CRTs with the Beam-Scan Velocity Modulation Method

The aperture compensation method is visually very effective, because it emphasizes the contours of the picture image by preshooting or overshooting the electron beam current. The picture image is, however, influenced adversely by the large beam spot resulting from the increase of the beam current at the contours. Consequently, this increase in beam spot size results in suppression of sudden brightness changes. The effect may be very clearly seen as the increased band width of a window pattern video signal, for example.