Focussing circuit for electron beam - has limited parabolic signals applied to horizontal deflection coil and to vertical deflection electrodes of tubes

摘要

The focussing circuit, for an electron beam, produces parabolic signals from the horizontal and vertical sync. pulses and passes them to the two focussing elements. The first focussing element consists of one focussing coil (FD) and it is supplied with parabolic signals derived from the horizontal sync. pulses whilst the second focussing element consists of the electron tube focussing electrode and is supplied with parabolic signals which are derived from the vertical sync. pulses. The parabolic signals are derived by doubly integrating the vertical and horizontal pulses and are applied via clamping circuits (KH, KV) to the focussing elements.