| 摘要 |
<p>In a cathode with an electron-emissive material layer formed on a base containing a reducing element, a relationship of 0.24 ≤ B/A ≤ 0.93 is satisfied, where A denotes a surface for layer formation of the base and B represents an area where the base and the electron-emissive material layer are in contact with each other. In addition, a relationship of 0.4 ≤ D/C ≤ 0.7 is satisfied, where C and D denote thicknesses of the base and the electron-emissive material layer, respectively. Thus, a cathode structure is provided in which sufficient electron emission can be obtained, a decrease in electron emission with the passage of time is not much during the operation, and variations in cut-off voltage are small. <IMAGE></p> |
