Patent GB-404715-A (GB)
Title: Improvements in or relating to picture transmission systems
IPC: H04N7/24
Filed: 1932-07-22
Abstract: 404,715. Copying telegraphy. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Bollman, J. H. ; 553, 34th Street, Woodcliff, New Jersey, U.S.A.) July 22, 1932, No. 20743. Convention date, July 25, 1931. Addition to 311,810, [Class 40 (iii), Telographs, Electric]. [Class 40 (iii).] To actuate punch selecting apparatus so as to produce code signals in accordance with the light and shade of the picture, light from the picture is interrupted at high frequency and falls on a photo-electric cell, the resulting modulated high-frequency current being impressed on a plurality of electric discharge devices, each of which is responsive to a different predetermined range of current or voltage strength, the outputs of which are connected to a further plurality of electric discharge devices, similarly responsive to different predetermined values of the voltage or current supplied. Transmitter. Light from a source 12, Fig. 1, is interrupted by an apertured disc 18 and passes through the picture 10, mounted on the drum 11, to the light-sensitive cell 15. A motor 16 rotates and traverses axially the drum 11 through gears 17, and rotates the disc 18 through gears 19, 20. The resulting current in the cell 15 is amplified by valves 21, 24, 25 and an adjustable attenuator 28 allows the output of valve 25 to be adjusted. The output circuit of valve 25 includes a transformer 29 connected in the input circuits of valves 30 ... 33 which are biassed by batteries 34 .... 37 so that for a small input only the valve 30 becomes conductive, a larger input making the valves 30, 31 conductive, while the strongest input renders all the valves 30 ... 33 conductive. The output circuits of valves 30 ... 33 include transformers 42 ... 45, each feeding the grids of groups of valves 46 ... 49, 50 ... 53, 54 ... 57, 58.... 61, Fig. 2. Each of these groups of valves is biassed in the same The disc 18 may have equal apertures disposed equally round its circumference, or the apertures may extend only part way round and the first few apertures may progressively way as valves 30 ... 33, and their output circuits include relays 62 .... 77, so that the number of relays actuated corresponds to the lightness or darkness of the picture 10. The relays 62 ... 77 are connected to the electro-magnets of a tape perforator 99 in such a way that according to the number of relays actuated the tape is perforated by the corresponding combination of electro-magnets. For example when relays 62 ... 72 are actuated, electro-magnets 1, 2, 5 are operated. The perforated tape 117 passes through the transmitter 120 and code signals are sent over the line 121 to the receiver and tape perforator 122. increase in diameter so that the false actuation of the relays is avoided. Receiver. The perforated tape 123, Fig. 3, passes through a tape transmitter 124 for distributing the code signals to the relays 101 ... 105. The actuation of the relays 101 .... 105 causes the short circuiting of one or more resistance elements 162 ... 177 included in the circuit of the light valve 178, so that the size of the aperture in the light valve is governed by the light and shade of the original picture. Light from a source 185 is controlled by the light valve 178 to record on the drum 180.