The decline of impregnated cathodes in CRTs

In the 1990s various CRT-companies introduced impregnated cathodes (I-cathodes) in color picture tubes (CPTs) in order to meet the requirements of good life performance at high beam currents. The initially successful introduction of I-cathodes in mass production did not result in a complete change over; on the contrary, I-cathodes are gradually phased out from CRTs. The reasons are the recent improvements of oxide cathodes, rather high cost of I-cathodes, sensitivity of I-cathodes for ion bombardment and electron optic considerations.