| 摘要 |
PURPOSE:To prevent the noise and increase the visualization of an image tube by roughing the inner surface of the glass bulb which is a part of the airtight case constituting an image tube which is assembled by installing a photoelectric cathode and a fluorescent screen anode in the airtight case. CONSTITUTION:An image tube consists of an airtight case consisting of a light incidence window 1 constituting a photoelectric cathode 7, a light discharge window 2 having a fluorescent screen 8, metallic electrodes 3, 4 and 5 and a cylindrical glass bulb 6. The inner surface 9 of the glass bulb 6 is made rough by blasting performed by spraying an aluminum oxide powder from a nozzle at high speed. After the airtight case is evacuated to a given vacuum degree, an evaporation source such as silver or cesium is heated to form a photoelectric cathode 7 by vapordeposition. Accordingly, the rough inner surface 9 of the bulb 6 prevents minute electric discharge which might be caused by the adhesion of the material of the photoelectric cathode, thereby improving the equivalent noise and increasing the visualization of the image tube. |
