| 摘要 |
378,949. Television. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, DOWSETT, H. M., Drayton Gardens, Winchmore Hill, both in London, and PLAISTOWE, D. L., 21, Oakleigh Park Drive, Leigh-on-Sea. May 20, 1931, No. 14903. [Class 40 (iii).] In a television transmitter of the kind incorporating a Nipkow disc, Figs. 1 and 2, and coacting means for projecting light over an area of the disc for scanning purposes, and in which the disc is adapted for movement relative to the projection apparatus so that, by allowing the light to fall on different portions of the disc, the direction of the parallel scanning lines traced on the object may be changed, e.g. from the vertical to the horizontal or vice versa, the disc is provided with two spirals of apertures or equivalent scanning elements, one spiral being used for the normal transmission and the other spiral for monitoring purposes. In the arrangement shown, the disc 1 and driving motor 2 are mounted on a frame 3 that is adjustable by means of a screw-threaded rod 6 and hand-wheel 7 along a support 4 inclined at 45‹ to the horizontal. Fitted to the disc 1 are two lenses 8, 9 which respectively cooperate with the projection apparatus when the frame 3 is at its upper and lower extreme positions, the lens 8 serving for vertical line scanning and the lens 9 for horizontal line scanning. Instead of two movable lenses 8, 9 a single fixed lens may be employed, and the frame 3 moved relative thereto. The disc 1, which is mounted in a casing DC, is provided with an inner spiral of apertures IS serving for transmission purposes and, on an integral or attached annulus, with an outer spiral OS serving for monitoring purposes. When the lens 9 is operated as shown, contact is made between plugs 12P on the frame 3 and lower sockets 12S on the support 4, thereby bringing an horizontally disposed monitoring neon lamp 12 into operation ; while the lens 8 is associated through plugs 10P and sockets 10S with an horizontally disposed neon lamp 10. At the receiving station, the co-operating apparatus comprises a Nipkow disc with a single spiral of apertures and a switch SW for selecting alternatively an horizontal neon lamp NTH and viewing apparatus VLH, or a vertical neon lamp NTV and viewing apparatus VLV. |
