GB811267A - Analog to digital translators - Google Patents

Abstract

811,267. Electric selective signalling systems. STANDARD TELEPHONES & CABLES Ltd. Nov. 8, 1957 [Nov. 9, 1956], No. 34887/57. Class 40 (1). In a shaft digitizer (that is a device for producing digital electric signals representative of a shaft position) using a plurality of monophylically coded binary discs appropriately geared together, there being one for each decimal denomination, and in which each disc, except the units order disc, has two sets of sensing brushes-a lead set and a lag set-(the lead set being positioned slightly ahead of the theoretical sensing position and the lag set slightly behind), the actual set of brushes used for reading any one disc is determined by whether the adjacent lower order disc is registering 0 to 4 or 5 to 9. As described, three discs 10, 11, 12, Fig. 1, are read serially by bit and serially by disc starting with the bits of the units disc 10, and each disc is so coded (see Fig. 2, not shown), that the last bit to be read is 0 for the range 0 to 4 and 1 for the range 5 to 9. A complete read operation is as follows: initially a read matrix is controlled so as to pass only pulses coming from disc 10; a scan generator then pulses four lines 24 to 27 in succession, thereby reading out the units disc 10 to an output; the last bit read from disc 10 is examined by an and gate 28 and if it is a 1 it causes a lead line 35 of a selector 34 to become positive-it it is an 0 it causes a lag line 36 to become positive; the read matrix is then controlled to pass pulses from disc 11 and the next four pulses from the scan generator, applied successively to leads 24 to 27, are routed via a scan matrix to either the lead brushes or the lag brushes as determined by the selector 34; this causes the read out of the tens disc and the hundreds disc 12 is read out in a similar manner.