| 摘要 |
1,230,023. Luminescent and photochromic materials and uses thereof. R.C.A. CORPORATION. 24 Jan., 1969 [24 Jan., 1968], No. 4245/69. Heading C4S. [Also in Division H1] In a cathode-ray tube provided with a photochromic screen, the image on the screen is written and erased by light from respective adjacent phosphors excited by electron beams of different energies. In one arrangement, Figs. 1 and 2 (not shown), the photochromic layer is covered by two phosphor layers adapted to produce light suitable respectively for exciting the photochromic layer and for erasing, and energized by electrons from a high-energy gun and from a low-energy gun respectively. As an alternative to the layered structures described above, particles of photochromic or of luminescent material may be coated with luminescent material to form the equivalent of a two-layered screen. Suitable photochromic materials are alkaline earth titanates or sodalite containing transition metal ions, and alkaline earth fluorides containing divalent rare earth elements. Specific materials are sodalite doped with iron, or strontium titanate doped with iron. Zinc cadmium sulphide activated with silver provides suitable light for erasing, and calcium magnesium silicate with cerium and lithium is a good write phosphor. |
