Patent GB-602621-A (GB)
Title: Improvements in receiving telegraph or like signalling systems
IPC: H04L17/30
Filed: 1945-09-05
Abstract: 602,621. Type-printing telegraphy. HYDE, G. A. M. Sept. 5, 1945, No. 22814. [Class 40 (iii)] A receiving telegraph or like signalling system comprises a hunting mechanism controlled by a marking bank of electrical contacts and a braking system so arranged that the effective number of stopping positions of the hunting mechanism is multiplied by the number of pre-set positions in which the marking bank and braking system together may be set relative to a fixed reference point. Incoming five-unit code signals are received by a line relay LR, Fig. 8, whose contacts lr1 apply marking or spacing potential to the brush Br of a distributer, according to the nature of the signal element being received. The distributer brush Br normally rests on the start segment STS and a received start signal operates a one revolution clutch via this segment to drive the distributer. The code signal-element potentials are then fed in turn via distributer segments FM1 ... FM5 to five drive magnets (not shown) of two-position contact discs FD1 ... FD5 each bearing 32 contacts, Figs. 7 and 7a. If a marking potential is applied to a drive magnet it moves its corresponding contact disc by <1>/64th of a revolution. Interleaved between the discs are four brush discs BD2 ... BD5 each having 32 pairs of brushes, the contacts and brushes being so arranged that for each of the 32 possible code combinations the positioning of the contact discs sets up a unique electrical path between discs FD1 and FD5. The outside brush discs BD1 and BD6 are of different construction, BD1 serving to common all the contacts on the first contact disc FD1, and BD6 serving to connect 26 individual contacts on the last contact disc FD5 to corresponding contacts on a marking bank MS, Fig. 2. The remaining six contacts are connected to six function magnets which serve to provide carriage return, line-feed, spacing, letter-shift, figure-shift or capital-shift. During the receipt of the stop element relay ST, Fig. 4, operates to the marking contact M of the line relay LR via the distributer stop segment SS and locks. Earth is extended by contacts st3 (not shown) to brush disc BD1 and hence to the selected contact on the marking bank MS or to a selected function magnet, which performs the required function. A slow-tooperate relay STR is energized over st2 to start a motor M which drives the test wiper TW, Fig. 2, of the marking bank MS until, if a character combination has been received, it reaches the contact marked with earth potential. The test relay TR then operates and at tr1 stops the motor and operates a braking magnet BM. Rotating with the test wiper TW are a braking disc K, Fig. 6, and an associated type-head, and the operation of the braking magnet BM inserts a braking wedge BW into the selected one of twenty-six notches F. At bm1 a hammer magnet HM is operated and causes a hammer H to strike the selected lower-case type (as indicated by the small arrow in Fig. 6). At hm1 a carriage stepping magnet CM is operated to step the type carriage one space, and release relay ST. The system thus returns to normal. The operation of any function magnet breaks the motor drive circuit, and releases relay ST, the " spacing " magnet doing so by operating the carriage stepping magnet CM at sm1. The figures and capitals shift magnets rotate the marking bank MS and braking wedge BW through 360/78 degrees and 360/39 degrees respectively. Character signals received after these shift signals cause the braking wedge to stop the braking disc K and type-head in a position in which the typehammer H strikes a second or third case character respectively. The letters shift signal rotates the marking bank MS and braking wedge BW back to their original position. With the marking bank MS is associated a twelve-armed direction-selecting wiper SW, Fig. 2, which rotates with the test wiper TW and ensures that it rotates in the shortest direction to the marked contact. If the marked contact is one on which the direction wiper SW is resting, relay SR operates and applies positive battery to the motor M which on subsequent operation of the slow-to-operate relay STR drives the test-wiper TW in a counter-clockwise direction. If the marked contact is not touching the direction wiper SW, relay SR does not operate and the motor M rotates the test-wiper TW clockwise. The type-head may be replaced by a wiper or set of wipers which may apply a potential to a desired contact or group of contacts or establish a unique combination of electrical connections. The Provisional Specification states that the receiver may be arranged to print one character while the next is being received, that " whoare-you " facilities may be incorporated, and that if a stop element is not received an errorsymbol, or no symbol, may be printed. It also states that the keyboard comprises five contact bars across its width, the depression of a key placing a potential on selected ones of these and also starting the distributer.