Patent GB-693250-A (GB)
Title: Improvements in or relating to devices for facilitating the detection of errors in symbol groups
IPC: G06Q20/00
Filed: 1951-03-09
Abstract: 693,250. Type-bar making machines. REUMERMAN, T., and HELMIG, W. H. T. March 9, 1951 [March 10, 1950], No. 5791/51. Class 100(iii) [Also in Groups XIX and XL(b)] A device for determining for a symbol group (e.g. a number, word or sentence) composed from a given series of n symbols numbered in a predetermined order, a corresponding check symbol, comprises a key-board for inserting the symbols, each key when depressed actuating a switch to close an electric circuit including means for displacing a check symbol indicator over a number' of steps which depend on the number of the symbol and its position in the group. The check symbol associated with the group can be used for detecting errors in the operation of a keyboard machine in which the device is incorporated. It defines the remainder Rn(G) obtained by dividing by a given number N a number G = #ai ki where ai is the number of the symbol in position i, the coefficients or "factors" ki are different for adjacent positions, and N#n and has no factors in common with ki or (ki+ 1-ki). The device may be incorporated in a typewriter and an associated composing machine, the check symbol being printed at the end of each sentence (i.e. on selection of a full stop) on a separate paper ribbon and the indicator being then zeroized automatically. In addition, the check symbol may be printed after a fixed number, e.g. 100, of symbols have been set up. The two paper ribbons may be subsequently compared. In the device shown in Figs. 1-3, the series of symbols are the digits 0-9, numbered accordingly, N=1 1  and ki=RN(10<SP>i</SP>-<SP>1</SP>). Thus k,=k,=...=1 and k 2 =k 4 = ...=10 (or-1). The digits are set up one by one, the highest or leftmost digit first, on the left-hand key-board. Fig. 1. Each key closes contacts to energize a magnet Ma which, when released, steps a shaft A 1  and commutator C, through ¢ a revolution, and each of the 1-9 keys supplies a positive potential to a commutator brush B 1 . The commutator is divided into segments connected to slip rings SR 1 , as indicated by the numerals (1-10) in Fig. 2, each of which is connected to a corresponding magnet M 1  ... M 10  which magnets when energized displace toothed racks ts which engage wheels tr coupled to indicator shaft A2 to rotate the shaft through 1-10 steps respectively. The shaft A2 carries an indicator drum ST with two scales 1, 2 each lit by a lamp GL, Fig. 3, and as the two halves of the commutator (corresponding to the two values for ki) are alternately brought into contact with brushes B1, the brush of a slip ring SR4 on shaft A, engages a corresponding part of a current distributer SV to light one of the lamps so that the correct check symbol (0-9 or +) is always indicated. If, subsequently, the key of the right-hand key-board corresponding to the check symbol accompanying the number set up is depressed, contacts will be closed to one of the brushes B, and if this symbol corresponds to that indicated the indicator shaft A2 will be returned to zero. An alarm relay AR energized through further contacts of the check symbol key will then be short-circuited through slip ring SR3, brush B6 and fixed contact blade CV. If, however, an error has been made and the check symbols do not agree, an alarm signal is given or a machine in which the device is incorporated may be stopped. Instead of the contacts being operated directly through the keys, they may be operated through members of the machine, e.g. those controlling item-printing, so that errors due to the machine may be checked in addition to those involved in receipt and setting up the number. Another form of the device, Figs. 4-6 (not shown), is based on N=13 which gives six different values for ki. The commutator Cl therefore has six parts connected to twelve slip rings, and there are six scales each lit by a different lamp through a six-part distributor SV. The shaft A2 is driven by a single stepping magnet the number of whose energizations is determined by a second commutator and associated slip rings. Other shaftdriving means may be used, e.g. each of the step magnets such as M 1 -M 10 , Figs. 1 and 2, may move the shaft through one step by pawl-and-ratchet mechanism, each of the magnets M 2 -M 10  closing contacts to energize the next lower magnet M 1 -M 0 . As shown in Fig. 8, each magnet drives the shaft A2 through a freely rotatable ratchet pr 1  and a connected gear wheel tr 1 , a pawl carrying wheel tr 2  and a ratchet pr 2 . The gear ratio of the pairs of wheels tr 1 , tr 2 , is such that the shaft is displaced one step for M 1 , two for M 2  and so on. Other forms of the device are also described (see Group XIX).