Hewlett-packard Company

Robin R Schmuckal

Ronald G Reed

Robert K McCullough

The magnitude of a DC high voltage supplied to an internal element of a CRT is varied by a thermionic valve that is located within the envelope of the CRT and that forms a voltage divider with an external load resistor. Only a small scale signal referenced near ground is needed to produce a several thousand volt change in the high voltage supplied to the internal CRT element. The variable high voltage may control a variable deflection factor, variable spot size, or in the case of a beam penetration CRT, either variable persistence or variable trace color. In a particular beam penetration color CRT having a split anode the thermionic valve comprises a tetrode flood gun coupled by an electron mirror to a plate region in the neck of the CRT.

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Colorado Springs, CO, United States of America

Robin R Schmuckal