Magnetic Deflection of Kinescopes

This paper investigates some basic principles in the operation of systems for magnetic deflection of television tubes. In the first part, the energy of the deflecting field is calculated for various deflection angles and beam voltages. It is found that sweep amplifiers are preferably operated with a positive rate of change of plate current. This causes a considerable plate-voltage drop, for which expressions are given. The efficiency of sweep generators is discussed and a method is indicated to determine the power dissipation in the sweep output amplifier. The second part deals with the transients during the retrace and their elimination. A theory is given for resistance damping. Practical results are presented for a special method of damping by secondary emission within the sweep amplifier. In part three, some basic forms of sweep distortion are discussed and means for their correction are indicated. Two characteristic distortions are found to be due to the resistive components of either the tube or the load. These distortions are of opposite sign. Nonlinearity of the tube characteristic is found equivalent to an emphasis of low-frequency components in the spectrum of a sawtooth wave. The fourth part describes a sweep circuit of improved efficiency. This circuit operates with power feedback and uses a diode as switching element. Flyback energy is rectified and the resulting direct-current power added to the plate power supply.