Patent GB-1348403-A (GB)
Title: Information display system
IPC: G06F3/033
Filed: 1971-04-19
Abstract: 1348403 Cathode-ray tube displays; transistor oscillators NICOLET INSTRUMENT CORP 19 April 1971 [26 Feb 1970] 21982/71 Heading H4T [Also in Divisions G1 and G4] A selected co-ordinate point on an analogue curve displayed on a cathode-ray tube is marked under the control of means which allows the position of the point to be adjusted along the curve. In the embodiment described the marking is effected by brightening the point but other forms of marking such as "blinking" of the point position or producing a small circle instead of a dot may be employed. Additionally more than one selected point at a time may be marked. As shown in Fig. 1, information specifying ordinate values of the curve is fed via data and transfer input terminals 49, 79 and transfer gates 15 to memory data register 13 which feeds data to and receives data from a digital memory 1 and information specifying abscissa values is fed via address and transfer input terminals 47, 77 and transfer gates 5 to address counter 3 which controls memory 1 the circuit operating under the control of a readout circuit 17 to supply the outputs of register 13 and of address counter 3 to respective D/A converters 27, 35 to produce the curve on display tube 33. When it is required to mark a co-ordinate point on the curve marker position control means 37 is operated manually to produce an "up" or "down" count in a (reversible) selection counter 19, the count in which is compared in digital comparator 21 with the address count (abscissa reference) derived from address counter 3 and on coincidence of the two input counts comparator 21 supplies an output to the beam control grid 43 to brighten the trace at the particular abscissa co-ordinate position. Additionally, the output of comparator 21 opens transfer gates 7 and 23 which pass the abscissa address from counter 3 and the ordinate value from register 13, respectively, to respective display registers 9, 25 and Alpha-Numeric displays 11, 29. The marker position control 37 includes a manually operable member 38 which, as shown in Figs. 4, 4a and 4b, comprises a pivotally mounted opaque member provided with open slots 107, 109 and a slot 111 of variable optical density graded from a maximum in the centre to minima at each end, the member co-operating with light sources 101<SP>1</SP>, 103<SP>1</SP> and 105<SP>1</SP> and photoresistive devices 101, 102, 103 and 105 such that movement of the operating arm to the left or right-hand side results in a step change (reduction) in the resistance of devices 103 or 105, respectively, together with a change (reduction) in the resistances of devices 101 and 102 which is proportional to the angular extent of the movement. Devices 101 and 102 are included as frequency determining elements in a multivibrator circuit (Fig. 5) including transistors 114, 116 so that the repetition frequency of the pulse train output is proportional to the extent, in either direction, of the movement of the operating arms. This pulse train is supplied to an output terminal 55 via transistors 155 and 157 but the latter is held off by the conduction of a transistor 153 until a signal is produced by either transistor 129 or 139 in response to light falling on devices 103 or 105 (indicative of left or right hand movement respectively of the operating arm), such signals operating via respective transistors 151, 149 to turn transistor 153 off and transistor 157 on so that the pulse train is supplied to terminal 55. At the same time the signal produced by transistor 129 or 139 is fed via respective transistors 141 or 143 to output terminals 51, 53 which, together with terminal 55 are connected (as shown in Fig. 1) to selection counter 19, the output on terminal 51, produced by a left-hand movement of the operating arm, determining a count-down and that on terminal 53 (right-hand movement) a count-up and the rate of the count being determined by the output on terminal 55. Push-button controls 39, 41 are provided for producing a single up or down count respectively.