Patent GB-1145712-A (GB)
Title: Apparatus for separately integrating successive values of each of a plurality of cyclically appearing signals
IPC: G01D1/04
Filed: 1966-04-27
Abstract: 1,145,712. Selective signalling. SOC. NATIONALE DES PETROLES D'AQUITAINE. 27 April, 1966 [30 April, 1965], No. 18544/66. Addition to 1,132,891. Heading G4H. Construction.-A mass spectrometer delivers at a scanning frequency the periodic unequal voltage signals a, b to an input terminal connected to a potentiometer 2 and contacts a, b, of a relay 1; whereby the larger signal is attenuated to equality by the potentiometer and the smaller is selected directly, and are alternately fed to differential amplifier 5 by energization of the relay from bi-stable multivibrator 18. The amplifier output energizes a trigger 7 having a fixed threshold value, a control gate 8, a shaping circuit 9, a binary counter 10, and a digital/ analogue converter 11 energizing a second input of the differential amplifier. A fixed frequency generator 13 also energizes gate 8, and counter 10 is connected over two lines to a multivibrator 16 energizing a differentiating circuit 17 retroactively connected to multivibrator 18. Shaping circuit 9 is also connected over gate 19 to adder 20, and over gate 22 to adder 23; the adders having associated therewith a zeroizer 37. The output of differential amplifier 5 is also connected to a trigger circuit 26 having a fixed threshold value, followed by integrator 27, inverter 28, monostable time delay multivibrator 29 and gate 30. whose output is connected through capacitor 31 and inverter 32 to counter 70 and multivibrator 16; and directly to bistable multivibrator 18 and gate 33, whose output excites monostable time delay multivibrator 34 whose output is connected to gates 30 and 8. Gates 22, 33 are also excited from output 35 of multivibrator 18 while gate 19 is excited from the output 36 thereof. Operation.-On occurrence of signal a, the input of amplifier 5 increases to a predetermined unit level at which trigger 7 operates to open gate 8, permitting generator 13 to pulse binary counter 10, operating a digital/analogue converter 11 developing a reference voltage fed back at 12 to the differential amplifier which increases by multiples of the predetermined level, and so long as the difference between the input voltages exceeds the unit level gate 8 remains open and the counter is pulsed in dependence on the signal amplitude, while at equality the gate closes and the count ceases. Counter 10 records the transmitted pulses from generator 13, and adder 20 also records this pulse number, since gate 19 is held open and gate 22 is held closed by multivibrator 18. When the amplitude of signal a diminishes by a unit level value, the output 25 of differential amplifier 5 operates trigger 26 to deliver a signal which is integrated at 27, amplified, converted, and applied through time delay multivibrator 29 to gate 30, which is initially open due to a signal from monostable time-delay multivibrator 34, to be differentiated at 31, amplified and inverted to zeroize counter 10. The signal is also applied over gate 30 to gate 33 normally closed by multivibrator 18, and also to the latter multi-vibrator, which is thus changed over. Coil 1 is thus energized to position the relay to accept signal b, and a similar sequence ensues to count the pulses of generator 13 in adder 23 alternately to the operation of counter 10, since gate 22 is opened and gate 19 closed due to the changeover of multivibrator 18. The control signal from trigger 26 operates through gate 33 (opened by the change of state of multivibrator 18) to trigger the multivibrator 34 to close gates 8, 30 during the return strokes of the scanning cycles of the mass spectrometer to prevent recording of spurious return signals. Overflow of counter 10 due to faulty operation of relay or potentiometer 2 triggers multivibrator 16, which through differentiator 10 returns multivibrator 18 to change over relay 3 and reverse the gates 8, 30 to prepare the apparatus for the next voltage peak. The signals a and b are thus alternately coded and added in 20, 23 which accumulate corresponding integrated numbers A, B which are converted to analogue signals at the outputs of 21, 24. At the end of a desired time interval an external pulse from zeroizer 37 is transmitted with delay to zeroize adders 20, 23. Any number of signals consistent with the mass spectrometer measuring cycle may be processed, with an equivalent number of adders and associated logic; the cessation of counting during scanning return being controlled by the last signal of each cycle.