United States Patent
US Patent 4101823: Method and apparatus for measuring cathode…
US 4101823 · granted 1978-07-18
| Patent Number | 4101823 |
|---|---|
| Title | Method and apparatus for measuring cathode emission slump |
| Filed | 1977-03-28 |
| Granted | 1978-07-18 |
| Inventor(s) | Felta Carl Farmer, Jr. |
| Assignee | RCA Corp |
| CPC Classification | G01R31/25, G01R31/00, G01R31/24 |
| Number of Claims | 4 |
Abstract
A cathode ray tube having a cathode and first, second and third grid electrodes, is biased “on” to allow an electron current IK to flow from the cathode to the second and third grid electrodes. During a test period of predetermined length, the peak value of cathode current is stored as a reference measurement Ikp and the cathode current Ik is continuously monitored and compared with Ikp. A failure indication is provided if the magnitude of Ikp – Ik exceeds a predetermined value at any time during the test period.
Claims Summary
1. A method of measuring an electron emission slump of a cathode in a vacuum tube, wherein said vacuum tube is a cathode ray tube having at least one cathode, one control grid G1 and one screen grid G2 said method comprising the steps of:(a) heating said cathode;