Patent GB-496227-A (GB)
Title: Improvements in or relating to printing telegraph systems
Filed: 1937-05-26
Abstract: 496,227. Type - printing telegraphs with photo - electric transmitters. BRITISH TABULATING MACHINE CO., Ltd. (International Business Machines Corporation) May 26, 1937, No. 14659. [Class 40 (iii)] A system for transmitting statistical data in the form of perforations or other code indications differentially located in columns on record cards comprises means for optically scanning each column on a card H in turn to transmit a signal impulse at a time determined by the position of the code indication in the column, and receiving means operated in synchronism with the scanning means for selecting printing surfaces and forming therefrom a printed record corresponding to the signal impulses. Figs. 2 and 3 show an arrangement for scanning a card 1 having code perforations in columns extending down the card, each perforation denoting by its position in a column either a numeral or, if a " shift " perforation appears at the head of that column, a symbol such as is shown in the margin of Fig. 1. The perforated part of the card is placed over a uniformly moving belt 2 having a series of scanning holes 2a, one for each column, arranged in echelon. Light from a lamp 11 is placed on one side of the card 1 and a photoelectric cell 12 is so located at the other side that a signal is transmitted each time a scanning hole 2a coincides with a perforation in the card. A sprocket wheel 15, driving the belt, is associated with a cam 18 which closes contacts 19 for emitting synchronizing signals, one every time a scanning hole passes over the blank margin of the card. Fig. 4 shows the circuit arrangements at the transmitter. The cathode 12c of the cell 12 is connected through a switch 22 to the grid 40b of a glow-discharge tube 40, the grid being also connected through a resistor 45 to the synchronizing-impulse switch 19. Thus, each closure of the switch 19 trips the discharge tube 40, and sends an impulse through the line transformer 43, while a code-signal impulse is sent each time the cell 12 is illuminated, the switch 22 having been previously closed. The duration of each impulse is determined by a cut-out relay 41. The switch 22 is mounted on a lever carrying a star wheel which is connected to a cam acting on the switch, and which coacts with a roller associated with the sprocket-wheel 15 in such a manner that the switch 22 is closed only once in each revolution of 15, when the first scanning hole is just beginning to traverse the card. A card switch 21, Fig. 4, controls a magnet 24 which is normally energized, and which by lifting the lever carrying the switch 22 prevents closure of that switch until the entry of a card for scanning breaks the circuit of the magnet 24 at 21. At the end of the scanning, the switch 21 closes, switch 22 is opened, and the card is automatically ejected by means not shown. A modification is described (Fig. 11, not shown), in which the record cards are provided with marks or dots instead of punched holes, and light passed through the scanning holes in the moving belt is reflected from a card on to the photoelectric cell. Figs. 6 and 7 show the printing receiver. A shaft 52 is driven by a motor 50 at the same speed as the sprocket 15 of the transmitter. A sleeve 54 on the shaft 52, connected thereto through phase-correcting mechanism 55 and a friction coupling, carries a type-wheel 53, five cams 57a .... 57e co-operating with contacts 67a ... 67e, a worm 58, and a tape-feeding cam 59. The sleeve 54 also has a stop arm 54a, which is adapted to be held by the armature of a magnet 56 when, in the absence of synchronizing signals, this magnet is de-energized. Under these conditions, the cam 57b keeps contacts 67b closed. The contacts 67a ... 67e, each pair of which is connected to a magnet as shown, are all connected in parallel to the anode of a valve 70, to the grid of which the signals from the transmitter are applied. At the start, a synchronizing signal trips the valve 70, allowing current to flow through the magnet 56 via 67b. This releases the stop arm 54a, and the sleeve 54 rotates with the shaft 52. A capacitor 56c provides holding current for the magnet 56 during the normal interval between synchronizing impulses. The cams 57a, 57c cooperate with contacts 67a, 67c so that normally they connect magnets M<1>, M<2> momentarily in the plate circuit of the valve 70, 67a being closed just before and 67c just after a synchronizing signal is due. If the shaft 52 is running slow or fast, one or other of the magnets M<1>, M<2> is in circuit with the valve 70 when a synchronizing impulse arrives, and actuates the phase corrector mechanism 55 (which may be similar to that described in Specification 452,031) so as to restore synchronism.. The type-wheel 53 is slidable along the shaft 52 so as to bring either a numeral or a letter or like symbol, as required, to the printing position, i.e. in alignment with a hammer (not shown), the tape passing between the hammer and the type. Shifting of the wheel 53 along the shaft is effected when a magnet 87 is energized and brings a roller 87b into engagement with a side cam 53a on the type wheel. When the wheel has thus been shifted axially, it remains in this position until near the end of a revolution, when it is moved back by a second side cam 53b coacting with a fixed roller 88. The energizing of the magnet 87 occurs if a shift signal is received during the momentary closure of contacts 67d near the beginning of a cycle. After contacts 67d have opened, contacts 67e are closed by the cam 57e, and remain closed during the remainder of a revolution. If during this period a printing signal is received, a magnet 80 is energized, and actuates the printing hammer. A cut-off relay 71 controls the duration of the operating impulses. The feed of the tape is effected after each revolution of the shaft 52 by ratchet-mechanism actuated by the cam 59. If, however, during several revolutions of the shaft no printing signals occur, a lever 96 is moved by the worm 58 sufficiently to close contacts 94 which enable magnet 93 to be energized and to hold the tape-feeding lever against further movement until another printing signal is received. Each movement of the printing-magnet armature causes the lever 96 to be raised out of engagement with the worm 58, and to be returned by a spring 98 to its initial position.