| 摘要 |
PURPOSE:To secure a cathode-ray tube for radar use capable of ample cognition for a radar image even at a speedier scanning rate than the conventional PPI scanning, by having a long persistent phosphor and a short persistent one mixed together, while combining both afterglow characteristics multiplicationally. CONSTITUTION:A P38 phosphor having a composition of (Zn F2)(Mn F2):Mn as long persistent phosphor is mixed just before a phosphor screen is formed, with a P14 phosphor having a composition of (Zn, Cd)S:Cu as a short persistent phosphor. In proportion to the increase of a composition weight ratio in the P14 phosphor, afterglow time decreases. In case of a radar beacon for fluvial navigation, when the time required fro a turn of a PPI scanning is about one second, it is required to take more than 0.5sec. for a 10% afterglow time to secure the sightability of a radar image. Furthermore, in order to quicken the extinguishment of afterglow following variations in the radar image, it requires such a time that relative residual brigtness becomes below 1% is three seconds or less and, what is more, it is also necessary a weight ratio of the short persistent phosphor is 5-50%. |
