Emission testing circuit for color cathode ray tubes

Abstract

The emission of the various electron guns of a color cathode ray tube are measured and indicated preferably by a time sharing multiplexing technique where bright intensity producing emission generating voltages are fed between th cathode and control or accelerator electrodes of the various electron guns preferably in rapidly repeated sequence. The switching rate is preferably many times per second so the emission current values are displayed as steady indications on the faces of current meters with meter movements which respond to the average emission curent of the associated electron gun. A quick and convenient means for determining whether or not the ratio of the highest and lowest emission measurements fall within an acceptable range is provided by means which proportionately reduce the conduction periods of the electron guns, so the highest or lowest emission measurement falls along one margin of a band on the scale of the associated meter face whose opposite margin is at a value which indicates the limit of an acceptable highest to lowest emission ratio.