Patent GB-826267-A (GB)
Title: Apparatus for handling mathematical, physical, technical and similar values
IPC: H03M1/00
Filed: 1956-12-06
Abstract: 826,267. Analogue to digital converters. KIENZLE APPARATE G.m.b.H. Dec. 6, 1956 [Dec. 10, 1955], No. 37324/56. Class 40 (1). In an analogue to digital converter an input analogue value represented by the duration of a pulse is transformed into digital output signals the value of which bears a non-linear relation to the value of input analogue. The invention is applied to a calculating apparatus for performing multiplication or division in which the digits of the input number are entered in a keyboards register 10, Fig. 3, one keyboard for each decimal denomination. The key depressed makes contact with a potentiometer which is weighted so as to produce a voltage increasing at a greater rate than the digit value it represents as shown in Fig. 1. This allows an approximately constant high tolerance of error in the response of the detecting apparatus in the range of the higher digits. This tolerance is 16% in the form shown. The scale of conversion shown is linear in the first part, i.e. up to digit 3, and thereafter increases approximately as does an exponential function. When these analogue values are read out in turn by step switch 20 on to line 21 they are applied to a pulse forming device 30 which forms pulses whose duration correspond linearly to the magnitude of the applied voltage. These pulses are applied to the beam control grid of a cathode-ray tube 40, the beam being switched on when the pulse is applied. The cathode-ray tube is used as a switch or distributer to change the variable duration pulse back into a digital representation. The beam is deflected by deflector plates 42 to which a voltage is applied which as shown increases rapidly at first and then at a progressively lesser rate. This causes the beam to scan rapidly at first and then more slowly, the applied voltage curve being the inverse of the curve shown in Fig. 1. The beam traverses a series of anodes 44 which are all connected to an output line 41. The output signal consists of a series of pulses having a number equal to the digit represented by the series, the non-linear scanning speed compensating for the non-linear conversion to a voltage analogue and a pulse duration analogue. In the apparatus described each of these pulses is used to initiate the read-out from a keyboard register 50 containing another number which is converted digit by digit into pulse trains in the same way so that the numbers in the two registers are effectively multiplied. Instead of varying the rate of increase beam deflection voltage this may be left linear and the anodes 44 placed increasing distances apart so that the effect is the same. In another form the cathoderay switching device is replaced by a delay line switching device having interconnected tappings at increasing intervals following the same weighting as is shown in Fig. 1. The variable duration pulses are applied to one end of a line connected at intervals through diodes to the delay line tappings. A pulse simultaneously applied to the end of the delay line traverses a certain number of tappings while the pulse is present on the other line, whereby a train of pulses is obtained corresponding to the value of the digit represented. Specification 812,829, [Group XIX], is referred to.