| 摘要 |
872,607. Cathode-ray tubes. PHILCO CORPORATION. Dec. 3, 1957 [Dec. 3, 1956], No. 37640/57. Class 39(1). A cathode-ray tube has a luminescent screen provided with portions emitting radiations of two different ranges of wavelengths and with a covering layer deposited on these portions for reflecting radiation of one range of wavelengths while transmitting radiation of the other range of wavelengths. In a colour television tube the green strips 44 are also indexing strips emitting ultra-violet or infra-red radiation. This radiation is transmitted through the layer 50 to a photocell 65 controlling the indexing system. A window 70 is provided in the wall of the tube for the emergence of the radiation. Anode layer 34 may be constituted to reflect the radiation as described in Specification 822,017. The glass face plate 60 of the tube may also be constructed to reflect the radiation. For emitting ultra-violet radiation the green strips, e.g. of magnesium activated zinc orthosilicate; may include unactivated zinc orthosilicate which also serves to balance the light output of the green strips relative to that of the blue and red strips as described in Specification 753,452. Alternatively there may be used activated zinc oxide which has two peaks of emission, one in the green region of the spectrum and the other near the ultra-violet region. Layer 50 may be of silver. For emitting infra-red radiation, the green strips may include manganese activated magnesium silicate. Layer 50 then consists of silicon, or germanium. Indexing material may be placed in the spaces between the colour phosphors instead of in one of the phosphor strips. The invention may also be applied to a monochrome tube in which indexing signals are used to stabilise the linearity of sweep. |
