Indirectly heated cathode for cathode ray tube - has heated section length defined to achieve reduction in current overshoot characteristic

摘要

The cathode has a cap (2) with carbonate (1) and a sleeve (4) of Ni-Cr alloy that encloses the heating element (13). When the supply voltage is applied the temp. rises to 780 to 820 degrees Celcius over the end section (13a) and a thermionic emission is produced. The length of the heated section is some 25 to 30 percent of the total length (L) of the sleeve. The reduction in the heated length section results in a reduction in the overshoot rate of the cathode current. ADVANTAGE - Improved operating characteristic.