Patent GB-1428200-A (GB)
Title: System for the sequential measurement fo several variable para meters
IPC: G01D5/12
Filed: 1973-04-16
Abstract: 1428200 Recording apparatus COMPTEURS SCHLUMBERGER 16 April 1973 [14 April 1972] 18147/73 Heading G1J In a multi-channel recorder in which the values of several analogue input signals 2 are marked successively and repetitively on a moving chart, each signal as it is sampled by a selector switch 4 is passed to an analogue-digital converter 6 connected to a first register 8, a second register 14 receives from a digital comparator circuit 16 signals representing the position relative to a reference position of a writing head 10 movable transversely across the chart, and the digital comparator circuit 16 compares the values in the registers 8, 14 and produces control signals to a stepping motor 12 to position the writing head 10, and to a print actuator 20 associated with the writing head to mark the chart when the head is correctly positioned. A coincidence circuit 34 compares the value in the register 8 with a pre-set maximum value 30 appropriate to the selected input channel 2, and actuates an alarm 36 if the input signal 2 equals or exceeds the pre-set maximum. Writing head. Fig. 2. A type wheel 10 is slidable along a shaft 40 in a direction transverse to the movement direction of the chart (not shown) by a stepping motor 12 acting via gearing 48, an endless drive cable 42 passing round pulleys 44, 46, and a yoke 50. A rotary electromagnet 22 acts via gears 56, 54 to rotate the shaft 40 and the type wheel 10 stepwise to bring a selected one of type characters 38 into the printing position, and via gearing 56, 58 to rotate two inking pads 24 (only one shown), one at each limit of travel of the type wheel, to bring a selected colour zone into the inking position. Electromagnet 22 also rotates the input channel selector switch 4 and the reference channel selector switch 32 (Fig. 1). An electromagnet 20, when energized, rocks a lever 52 to strike the type wheel 10 on the chart, or on an inking pad 24. Control system. Fig. 3. Flip-flops 68, 72 respectively determine the stopping and running of the stepping motor 12 and its direction of operation. Photo-electric sensors 62, 64 near the sides of the chart roll 60 form two reference positions for the writing head 10 and produce signals CG, CD respectively when the head 10 passes them. These signals and signals AR, AV representing the writing head's direction of travel are fed to AND gates 84, 86, 88, 90. AND gates 84, 88 trigger a sequence switch 96 controlling the inking and reversal of the writing head 10 at either end of its travel. AND gates 86, 90 trigger the analogue-digital converter 6 to take in a signal 2 and to activate a sequence switch 122 controlling the positioning of the writing head 10, marking the chart, and stepping on the selector switch 4, print wheel, etc. A high frequency (e.g. 50KHz) clock pulse generator 108 feeds the analogue-digital converter 6. A clock pulse generator 132 supplies pulses (e.g. 300Hz) to energize the stepping motor 12. Operation. Assuming the writing head 10 reaches detector 62 moving in direction AR, AND gate 84 signals the first sequence switch 96 to allow clock pulses H to activate it to deliver a series of output signals thus:- (1) n pulses to cause the head 10 to continue movement to the inking pad 24; (2) 70 to flip-flop 68 to stop the head 10; (3) 78 to a monostable circuit 76 of electromagnet 20 to strike a character 38 of the head 10 on the inking pad; (4) 74 to flip-flop 72 to reverse the head 10 drive motor 12; (5) 104 to analogue-digital converter 6 to enter a converted input signal 2 into register 8; (6) 70 to flip-flop 68 to start head 10 movement in direction AV; and RAZ to reset scaler 100 of switch 96 to zero. As the head 10 passes sensor 62, AND gate 86 passes a signal 136 to cause transfer of the contents of register 8 to register 14, a signal 114 to flip-flop 112 to set the register 14, which is an UP-DOWN counter, to subtract, and a signal 134 to connect the clock pulse generator 132 to register 14 so that its pulses reduce the contents of register 14 in accordance with the movement of head 10 from the reference point 62. When the register 14 is empty, the head 10 position corresponds to the value of input signal 2. A zero detector 116 for the register 14 then activates sequence switch 122 to deliver a series of output signals thus:- (1) 70 to flip-flop 68 to stop the head 10; (2) 78 to circuit 76 to strike the inked character 38 of the head 10 on the chart; (3) 136 to register 14 to re-enter the value from register 8; (4) 82 to a monostable circuit 80 of rotary electromagnet 22 to advance the selector switches 4, 32, type wheel 10, and inking pads 24 one step; (5) 104 to analoguedigital converter 6 to enter the new input signal 2 into the cleared register 8; (6) 134 to switch to fast clock pulse generator 108. Pulses are simultaneously added to register 8 and subtracted from register 14 to determine if the sum of the two stored inputs 2 is greater than the maximum measurement range of the recorder, which corresponds to the capacity of register 8. If the sum exceeds the maximum, a logic signal 110 emitted by a saturation detection circuit 106 for the register 8 is charged. The zero detector 116 stops the transfer by closing a gate 118 to the pulses when the register 14 is empty, and restarts the sequence switch 122. The switch 122 passes a signal 111, dependent on the level of signal 110 of circuit 106, to the flip-flop 72 to set the direction of the motor 12. Final signal 70 restarts the head 10, and RAZ resets the scaler 126 of switch 122 to zero. If signal 110 has changed, head 10 moves in direction AV; if not it moves in direction AR, the shortest travel for inking and positioning for the next marking action having been selected. Inking and resetting now proceed as above.