Patent GB-263005-A (GB)
Title: Television
IPC: H04N3/02
Filed: 1926-03-23
Abstract: 263,005. Baxter, C. March 23. 1926. Television.-The apparatus is designed for ready conversion from an arrangement in which the original scene is illuminated by flood light to one in which successive elemental portions are illuminated by spot light, thus eliminating any inconvenience to the artists of flood light illumination. For this purpose the usual rotary disc, travelling perforated band, or like devices employed for directing light from the successively elemental portions of the scene on to one more light-sensitive cells are adapted for ready detachment from the housing for the cell or cells and for attachment to the housing of a lamp for effecting the spot light illumination. Fig. 1 shows the light-sensitive coil 7 with associated optical devices carried by a cylindrical housing 1 formed with a support 3 for the detachable exploring device comprising a motor 4 driving discs 5 and 6 in opposite directions. The disc 6, provided with peripheral radial slots, is secured, preferably with provision for rotary adjustment as by a nut 24, to the shaft 17, Fig. 4, of the motor. The disc 5, provided with a spiral series of holes passing in front of the slcts in the disc 6, is mounted by bearings 22 on the shaft 17 and is driven through gears 18 - - 20, Fig. 4. The holes in the disc 5 may be fitted with lenses or formed with blackened bevelled edges. The optical system includes an iris diaphragm 53, lens 64, condenser lenses 65, and adjustable objective lenses. Fig. 2 shows the lamp, the light 11 with associated optical devices being mounted in a housing carrying a support 10 for the motor 4 and associated mechanism. Fig. 3 shows the apparatus for reconstituting the scene at the receiving station, comprising a light 16, of which the intensity is varied by the received currents either directly or by use of a polarizing tube, with associated optical devices mounted in a housing 13 carrying a support 14 for a motor 4 and associated mechanism similar to those at the transmitting station. Synchronous movements.-To maintain synchronism of corresponding shafts at the two stations, each shaft may be provided with a disc 27, Fig. 5, formed with a hole 29 fitted or not with lenses, mirrors, prisms or like optical devices. At the transmitting station this hole passes once per revolution between a lamp 30 and a light-sensitive cell 31, and the resulting current in the circuit of the cell is caused to illuminate momentarily a lamp 32, Fig. 6, at the receiving station in similar relation to the hole in the disc at that station. The light passing through this hole is incident on a light-sensitive cell 34 or 35 according as the speed of rotation of the disc is greater or less than that of the disc 27, Fig. 5. The resulting correction currents are arranged to control a governor or a brake or the field strength of the electric motor if such is used. Alternatively, the synchronizing disc may be of insulating material with the holes therein co-operating with spark discharge points instead of with lamps and light-sensitive cells, and in this case pointed conductors may he used in place of the holes. As a further modification, metal contacts co-operating with brushes may be used.