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Àug- 28, 1952 J. U. l-:YNoN 3,051,898 MEASURING AND INTEGRATING SYSTEM Filed sept. 28, 1959 k26 United States Patent tice 3,051,898 Patented Aug. 28, 1962 2 1 in conjunction with the accompanying drawing in which 3 051,898 MEASURING AND’INTEGRATING SYSTEM James U. Eynon, Willow Grove, Pa., assignor to Leeds and Northrop Company, Philadelphia, Pa., a corpora tion of Pennsylvania Filed Sept. 28, 1959, Ser. No. 842,879 17 Claims. (Cl. 324--100) there has been diagrammatically illustrated a system em bodying the invention. Referring to the drawing, there is applied to input termi nais 1€) and 11 a voltage EX representative of, that is proportional to, the magnitude of a condition to be measured and integrated Values of which are desired. Though as indicated above, 'there are many condi This invention relates to measuring and integrating tions Where there may be desired measurements of the systems and has for an object the provision of such a 10 magnitudes as well as the determination of quantities system which is reliable in operation and which per representative of integrals of such conditions, reference forms the required multiple functions of measuring and may be had to gas chromatography as one field where integrating with a minimum of components. such measurements are particularly useful. For eX In many industrial processes it is frequently desirable ample, it has been found that with gas chromatograms a to integrate with respect to time the magnitude of a 15 better correlation with concentration is achieved if area condition or a measured variable and to produce an in measurements beneath peak values are utilized instead dication and/ or a record of the integrated magitude of of measurements alone of the peak heights of the out such a condition. In order to integrate the magnitude of a condition, there must be provided a measuring sys put of the chromatograph detector. Thus it may be as sumed that the voltage EX is that produced by the detector tem arranged to produce a measured output of magnitude 20 in a gas chromatograph. at all times proportional to that of the condition. This The magnitude of the voltage Ex is determined by a measured output is then applied to an integrating means measuring system which includes a detector 12 and a for producing a second output proportional to the integral potentiometer comprising a slidewire resistor 13 energized with respect to time of the measured output. from a suitable source of supply, such as a battery 14 ‘ In accordance with the present invention, the measuring 25 by Way of a rheostat 1S. The detector 12 is preferably system which is utilized to produce the measured output of the electronic type and such as shown in Williams proportional to the magnitude of the condition is like Patent 2,113,164. This detector operates to adjust the wise utilized for measuring the second output proportional movable contact 13a of slidewire 13 to maintain in bal to the integral of the first output. This is accomplished ance the measuring circuit. Thus as the magnitude of by providing a means of disconnecting the integrating 30 the voltage EX changes, so does the position of contact means from the measuring system and for then applying 13a on slidewire 13. Besides the mechanical connec the second output as the input to that measuring system tion to the contact 13a as indicated by the broken line, for producing therefrom an indication of the magnitude of there is also a mechanical connection, as indicated by the integral with respect to time of the magnitude of the the broken line 16, to a pen-index 17 of an exhibiting 35 condition. Thus the system as a whole operates periodi~ means which includes a scale 18 and a chart 19 arranged cally to measure and to integrate the magnitude of a to be periodically driven by a chart-driving motor 20. condition and periodically to provide indications and/or As the magnitude of the voltage Ex changes'in one direc records of the integral with respect to time of the mag tion or the other, the pen-index 17 -Will be driven in one nitude of the condition. direction or the other to- indicate on the scale 18 its in 40 In a preferred form of the invention there is utilized stantaneous magnitude and to record that magnitude on a measuring circuit for producing a voltage output pro the chart 19. portional to the magnitude of the condition. This voltage The detector 12, through a mechanical connection 22, output is applied to an integrating system including an relatively adjusts a slidewire 23 and its associated con ampliñer, an integrating capacitor, and an integrating re tact 23a energized from a constant voltage source 24 sistor. The arrangement is such that the magnitude of 45 to produce, for an integrating system now to be described, the charge on the capacitor is proportional to the integral an input voltage EI, proportional to the voltage Ex. Thus with respect to time of the voltage representative of the the measuring system produces a first Voltage output which magnitude of the condition. Periodically the integrating is the input to the integrating system. system, having a voltage output representative of the The integrating means may be of the type disclosed in charge on the integrating capacitor, is disconnected from Davis et al. Patent 2,830,245. As shown, the integrating the measuring circuit. This output is then applied to the system comprises an integrating resistor 25 (which cor input of the measuring circuit, 'which input is then disresponds With the reset resistor of said patent) and an connected from the condition under measurement, for ,amplifier 26 having a modulating means shown in the measurement of the output, and thus the integral with form of a vibrator 27 included in its input circuit. The 55 respect to tim-e of the magnitude of the condition over movable contacts of the vibrator 27 is driven by an the preceding time interval. Preferably, the measuring operating coil 28 alternately to engage iirst one stationary system includesv an exhibiting means for indicating not contact and then to engage the other stationary Contact only instantaneous variations in the- magnitude of the of the vibrator. The amplifier 26 includes in its output condition, but also for indicating and recording the afore 60 circuit a converter 29, such for example, as illustrated said integral with respect to timev of that condition. , in FIG. 4 of said -Davis et al.> patent, in order to produce For further objects and advantages of the invention across output conductors 30 and 31 a direct current out and for a discussion of a typical embodiment thereof, put which increases when the alternating current input reference is to be had to the following description taken l(produced by vibrator 27) is of one phase and decreases 3,051,898 3 A. when that input is of opposite phase. The conductors seen that the potential difference at balance across the re 30 and 31 correspond with the connection in FIG. 4 of sistor 36 will be equal and opposite to the potential dif said Davis et al. patent leading to the cathode of the , ference across the capacitor 32. The resistance means tube 91 and to the conductor 50 of that patent. Phase including the resistor 37 and the slidewire 38 is provided sensitive converters which produce direct current outputs 5 in order that there may be derived therefrom a fractional may take various forms, and a further example of a part of a voltage equal to that across capacitor 32 for ap suitable system may be found in FIG. 1 of McAdam et plication to the input of the measuring system. This al. Patent 2,901,563. fractional voltage El is proportional lto the integral with With slidewire contact 23a in its illustrated position, it respect to time of the applied input signal EX. The man will be understood there is an output from amplifier 26 ner in which the magnitude of the integrated output signal and its converter 29. The polarity is such that current is measured and recorded will now be described. flows from one side of converter 29 by way of conductor During the operations which have just been described, 30, an integrating capacitor 32, an integrating resistor 25, contacts 33, the lower fractional part of the slidewire 23, and by way of conductors 34 and 31 to the other side of the converter 29. The potential difference developed by the current fiowing through integrating resistor 25 op poses the potential difference Ep. If these two voltages or potential differences be of unequal value, there will be an input signal to the amplifier 2.6 which will produce a 20 change in the output in a direction to reduce the difference, approaching zero as a limit. 'Ihat the described opera tion takes place will be evident by considering that the movable Contact of vibrator 27 first engages its left-hand a timing motor 41 energized from a suitable source of sup ply has been effective in rotating a series of control cams 42-45 inclusive in a counterclockwise direction. After a predetermined time interval and corresponding with the time over which the magnitude of the condition EX is to be integrated, a trough of cam 42 arrives in registry with a cam follower 46 for operation of switch contacts 47 and 45 from their uppermost to their lowermost positions to interrupt the circuit from the input terminals 10 and 11 and to complete a circuit from output conductors 49 and Si) from the integrator to the input conductors 51 and 52 of the measuring system. stationary contact. There will then be applied to the in 25 Concurrently with, and preferably just in advance of, put of amplifier 26 an input signal of polarity and mag the operation of the switch contacts 47 and 48, »the trough nitude depending upon the direction and magnitude of the of cam 44 arrives in registry with a cam follower 53 for difference between the voltage Ep and the potential dif the opening of switch contacts 33 an instant ahead of the ference developed across the integrating resistor 25. Thus, operation of the contacts 47 and 48. The effect of open this input signal will be of one polarity or of an opposite ing the switch contacts 33 is to disconnect the output of polarity. When the movable contact 27 engages its right the measuring means from the input circuit of the integrat hand stationary contact, it will be seen the input to the amplifier is shorted, meaning that there is zero signal ap plied thereto. 'Ihus, zero or ground potential is utilized as a reference signal with which the aforesaid difference signal is at all times compared. The periodic operation of the movable contact of vibra tor 27 in opening and closing the aforesaid circuits pro duces an input to the amplifier 26 having an alternating ing means. With the contacts 33 open, the point 40 is still maintained at or very close to ground potential by the action of the amplifier 26. This action will maintain the voltage across resistor 36 equal and opposite to the voltage across the capacitor 32 during the time that the contacts 33 are open. Thus the integrator can store an integrated value for a period of time so that the value can be read out at the operator’s convenience. There current component of a frequency dependent upon that 40 after, or concurrently therewith, the contacts 47 and 48 of the alternating source used for energizing the driving connect the output of the integrating means to the input coil of the vibrator 27. As shown, that source has a fre of the measuring system. Since the voltage El is propor quency of sixty cycles per second. The phase of the al tional to the charge on the integrating capacitor 32, the ternating current will depend on the polarity of the poten measuring system will now be effective to measure the tial difference applied to the input circuit of amplifier 216. time integral of the voltage Ex over the period of time If it now be assumed that the voltage Ep is greater than during which integration took place. Thus, the detector that developed across the integrating resistor 25, then 12 responds to the voltage E1 andthe contact 13a is moved there will be an increased output from amplifier 26 to in to a circuit-balancing position, and through the driving crease the unidirectional current flow through integrating connection 16 the pen-index 17 is lmoved to a position resistor 25 to restore the voltage balance in the input cir 50 corresponding with the integrated value, Ei, of the condi cuit to the amplifier 26. tion as represented by the voltage Ex. This integrated The integrating action takes place by reason of the fol value is exhibited on the scale 18. lowing considerations. Inasmuch as the current path for To provide a distinctive indication on the chart 19, a the integrating resistor 2S is by way of the integrating crest is provided on the cam 43 which is arranged to close capacitor 32, it will be seen that the current flow to the 55 the motor control switch 21 shortly after the operation of capacitor 32 must be maintained constant if there is to the switches by cams 42 and 44, as above described. be produced a constant potential difference across the in tegrating resistor ‘25. Inasmuch as the capacitor 32 ac quires a charge and potential difference of magnitude pro portional to the integral with respect to time of the cur rent flowing through it (and hence proportional to the integral with respect to time of the magnitude of the in put condition EX), to overcome the increasing charge on capacitor 32, there is developed from the amplifier 26 and the converter 29 an increasing output, an output which increases as long as the voltage Ep has a finite value greater than zero and at a rate depending upon the magnitude of ythe voltage Ep. Included in the output circuit of the converter 29 are branch circuits, one including a resistor 36 and the other including a resistor 37 in series with a slidewire 38 hav ing a manually adjustable contact 38a. It will be recalled that at balance, the point 40 is With motor 20 energized, the chart is rotated in a down ward direction to produce, by the chart-marker or the pen portion of the pen-index 17, a line in the direction of 60 travel of the chart. Such a line is shown at 19a. Anoth er such line is shown at 19h. It will be noted that the line 1% appears to the left of the end of the horizontal line just beneath it and for the following reasons. In the integration of the magnitude of a condition hav ing the `characteristic of a high amplitude which lasts for a short interval of time, the peak value of the voltage EX will exceed the integrated value represented by the voltage E1. Thus on the chart 19 there will be recorded all peak values which exceed in magnitude the time in tegral of the condition over the period of time during which the integration takes place. In this connection, it is to be understood that by increasing the magnitude of Ei, as by suitable adjustment of the contact 38a, all brought to the same potential (to a very close approx integrated values may be made to exceed the peak values imation) as the conductor 34. Accordingly, it will be 75 as appearing on the chart 19, but without the respective apetece Y 5 . 6 , measurements departing from true proportionality in re spect to the magnitudes of ‘the condition under meas urement and with respect to the time integrals of such conditions. The timing cams 42 and 44 maintain the contacts 47 and 48 in their lowermost position and the switch con tacts 33 open until the motor 20 has been energized for a length of time adequate to produce the distinctive in tor and a potentiometer adjustable by'said detector for maintaining said measuring system in balance with change in the magnitude of said condition, and means operable by ‘said detector for indicating instantaneous magnitudes of said condition. 3. The measuring and integrating apparatus of claim 2 in which there is provided a voltage-developing means, means operable by said detector for adjusting said volt age-developing means for producing as la voltage said a switch 54 to short-circuit the capacitor 32 wholly to 10 ñrst output of magnitude proportional to the magnitude of said condition, said integrating means including an discharge it, a cam follower 55 being associated with integrating resistor and an integrating capacitor for pro cam 45 for the operation of switch 54. Thereafter, the ducing as a voltage said second output proportional to cams 42-45 operate to restore the parts to their illus« the integral with respect to time of said first output volt trated positions. The applied voltage EX is immediately age. detected by the detector l2 which functions through con 4. The measuring and integrating apparatus of claim 3 tact 13a to rebalance' the measuring circuit and to set dications on the chart 19. Thereafter the cam 45 closes in which said integrating means includes amplifying the-contact 23a to develop the input voltage Ep for the means having a direct current output for supplying cur integrating means. The integrating means then operates rent to said integrating capacitor through a circuit in in the manner described above to initiate the charging of the capacitor 32 and for the development of the out 20 cluding said integrating resistor for producing in the in put to said amplifying means a voltage balance. put signal Ei from the integrating means preparatory to 5. The measuring and integrating apparatus of claim 4 the next operation of the circuit controlling switches 21, in which said amplifying means has an input circuit and 33, 47, 48 and 54. in which said switching means for disconnecting said inte lf it be desired to integrate the quantity EX over more grating means includes a switch for interrupting the cir than one cycle of operation as determined by the motor cuit between said voltage-developing means and said 41 and its associated cams, a switch 56 in series with capacitor without interrupting connections of said capaci the switch 54 may be opened so that the capacitor 32 tor to said input circuit of said amplifying means, where will not be discharged at the end of the first cycle. If by said second output will be proportional to the magni after the crest of cam 45 has passed the cam follower 55, the switch 56 be closed, the output E1 of the integrating 30 tude of the potential difference across said integrating capacitor. means will then be representative of the integrated quan 6. The measuring and integrating apparatus of claim l tity EX over two time cycles. Obviously, the integration may take place over any -selected number of consecutive time cycles. By timed opening and closing of switch 6l integrations over selected time cycles may be omitted. For convenience, the integration interval has been de scribed as taken in respect to time, the timing motor 41 providing the time-parameter. If the integration interval be desired in respect -to a different quantity, the cams in which there is provided means for modifying the opera tion of said switching means for varying the time interval over which integration of said first output takes place. 7. The measuring and integrating apparatus of claim l in which there is provided means for resetting to zero said integrating means after operation of said switching means to apply said second output -as the input to said measur ¿i2-45 will be operated by a driving means energized under the control of that quantity. For example, a switch 57 in series with the motor 41 will be opened and closed by a control means 58 responsive to the quantity in respect’to which the integration interval is to take ing system. place. ing system for relatively moving said marker and said With the above understanding of the invention, it is to be understood that modifications may be made in various parts of >the system and that some features may 8. The measuring and integrating apparatus of claim 1 in which there is associated with said measuring system an exhibiting instrument having a chart, a marker for said chart, means operable under the control of said measur chart for producing a record on said chart of the magni tude of said condition, and means operable in timed re lation with said switching means for relatively moving said chart and said marker in a different direction for to cover such modifications and reasonable equivalents 50 producing a distinctive mark on said chart in position be utilized without other features, it being the intent by the appended claims. What is claimed is: l. A measuring and integrating apparatus comprising a measuring system having an output circuit and an in put circuit, switching means for applying an input signal to said input circuit proportional to the magnitude of a condition for producing at said output circuit a ñrst out put of magnitude proportional to the magnitude of said indicative of the magnitude of said second output. 9. A measuring and integrating apparatus comprising a measuring system having an output circuit and an input circuit, switching means for applying an input signal to said input circuit proportional to the magnitude of a condition, said measuring system including a detector and potentiometer means foi- producing at said output circuit a first voltage output of magnitude proportional to the magnitude of said condition, integrating means having condition, integrating means having an output circuit and an input circuit connected to said output circuit of said 60 an output circuit and an input circuit connected to said output circuit of said measuring system for integrating measuring system for integrating with respect to» time with respect to time said first output and for producing said iirst output and for producing at said -output circuit at said output circuit of said integrating means a second of said integrating means a second output proportional output proportional to the integral with respect to time to the integral with respect to time of said ñrst output, and means for operating said switching means for discon 65 of said íirst output, said integrating means including an integrating resistor, an integrating capacitor, voltage-di necting said integrating means from said output circuit viding resistance means and an amplifier of the chopper of said measuring system and for connecting said output type responsive to the difference between said iirst volt circuit of said integrating means to said input circuit age output and the potential difference developed across of said measuring system in place of the input responsive said integrating resistor, a phase-sensitive converter hav to the magnitude of said condition for establishing a mag ing an output circuit and an input circuit connected to the nitude of the output from said measuring `system pro output of said amplifier for producing a direct current portional to the integral with respect to time of said output, said integrating resistor and said integrating ca magnitude of said condition. pacitor being connected in series circuit relation with said 2. The measuring and integrating apparatus of claim l output circuit of said converter and with said output in which said measuring system includes a voltage detec 3,051,898 8 opposite polarity, an integrating capacitor connected circuit of said measuring system, said resistance means being connected across said output circuit of said integrat in series-circuit relation in said output circuit of said amplifier and in series-circuit relation with said integrat ing means, and means for operating said switching means for disconnecting lsaid integrating means from said out ing resistor, the amplifier output current iiowing through put circuit of said measuring system and for connecting 5 said integrating resistor having a magnitude which de velops said potential difference balancing said measuring the output circuit of said integrating means to said input circuit of said measuring system in place of the input system output voltage, voltage-dividing resistance means responsive 'to the magnitude of said condition for apply connected across said amplifier output circuit for develop ing at least a fractional part of the voltage developed ing a potential difference, switching means for connect across said resistance means to the input of said detector 10 ing the input of said amplifier to be responsive solely to for establishing a voltage output from said measuring the difîerence in the potential acquired by said integrating system proportional to the magnitude of the voltage de capacitor and that developed by said voltage-dividing re rived from said resistance means thereby to provide a measurement of the integral with respect to time of said sistance means, said amplifier regulating the current ñow through said resistance means to produce a potential dif ference equal and opposite to that across said integrating capacitor whereby measurement of a potential difference developed by said resistance means will `be proportional magnitude of said condition. 10. A measuring and integrating apparatus comprising a measuring circuit having input terminals for applica tion thereto of a voltage which varies in accordance with the magnitude of a condition, said measuring system in cluding a detector and potentiometer means for produc to the potential diiierence across said integrating capaci tor, and means for applying at least a fraction of said last-named potential difference as the sole input to said ing a voltage balancing that of the applied voltage and measuring system for the measurement of the magnitude for producing a first output voltage of magnitude propor of the integral with respect to time of said magnitude of said condition. tional to the magnitude `of said condition, integrating means including an amplifier having an input circuit, 13. The combination of claim l2l in which said meas modulating means included in said input circuit, a phase 25 uring system includes a Voltage detector and a potentiom eter adjustable by said detector for maintaining said sensitive converter connected to the output of said ampli fier for producing a direct current output, an integrating measuring system in balance with change in the magni resistor and an integrating capacitor in series-circuit re lation with said output of said converter, means including said modulating means for applying to said amplifier the difference between said first output voltage and the poten tial diti’erence developed across said integrating resistor for applying a signal having an alternating current com tude of said condition. 14. The combination of claim l2 in which there is provided means for modifying the operation of said` switching means for varying the time interval over which the amplifier output current iiows through said integrating ponent of phase and of amplitude dependent upon the direction and magnitude of said difference, resistance capacitor. l5. The combination of claim l2 in which there is associated with said measuring system a recorder having means connected across said output of said converter for a chart, a marker and driving means for said chart, means operable under the control of said measuring system for developing a potential difference, an output circuit from moving said marker for producing a record on said chart said integrating means derived from said resistance means, of the magnitude of said condition and of the magnitude switching means for disconnecting said integrating means from said measuring system, whereby said direct cur 40 of the integral with respect to time of said magnitude of rent output produces a potential difference across said said condition, and timing means for controlling the operation of said switching means. resistance means equal and opposite to that across said integrating capacitor, and 4means for interrupting the 16. The combination of claim l5 in which means are provided to control said driving means for said chart for circuit from said input terminals to said detector and movement of said chart only during the said production for establishing connections from the output circuit of said integrating means to said detector as the input to said measuring system thereby to produce a magnitude of said first output voltage proportional to the integral with respect to time of the magnitude of said condition. l‘l. The measuring and integrating apparatus of claim l0 ^ in which there is »associated with said detector an exhibit ing means having a chart, driving means for the chart, of one of said records on said chart. 17. A measuring and integrating yapparatus comprising a measuring system responsive to the magnitude of a condition for producing a first output of magnitude pro portional to the magnitude of said condition, integrating tion of the instantaneous magnitudes of said condition means having an input circuit, means operable under the control of said measuring system for developing across said input circuit an input voltage proportional to the magnitude of said condition, said integrating means com during the period of integration thereof, and timing means prising means including Áan `amplifier for producing in for establishing the time over which said magnitude of its output circuit a direct current of magnitude which increases when the input to said amplifier is of one polar a marker for producing a record on said chart for indica said condition is integrated for controlling the operation of said switching means and for controlling the operation ity and decreases when the input to said amplifier is of of said driving means for said chart to move said chart opposite polarity, an integrating capacitor and an in 60 tegrating resistor in series-circuit relation with said out relative to said marker. 12. The combination with a measuring system for put circuit of rsaid amplifier and in said input circuit, a measuring the magnitude of a condition and for produc connection from one side of said input of said amplifier ing an output voltage of magnitude proportional to the Xtending to the junction between said integrating resis magnitude of Aa condition, of integrating means having tor and said integrating capacitor, and a second connec an input circuit to wi‘hch said output voltage is applied, tion for the other side of said input extending to the side an integrating resistor in series-circuit relation in said of the output circuit of said amplifier remote from said input circuit, an amplifier having an output circuit and integrating capacitor for application to said amplifier ot an input including said input circuit for application there the difference-potential between said input voltage and to of the difference between said output voltage and the 70 the potential difference developed across said integrating potential difference developed across said integrating re resistor by reason of current iiow therethrough from said sistor, said amplifier including output means for produc amplifier by Way of said integrating capacitor whereby ing flow of a direct current through said output circuit said output current from said amplifier will charge said which increases or decreases when said difference volt integrating capacitor to a potential proportional to the age applied to its input is of one polarity or of an integral with respect to time of said magnitude of said a î @51,898 Q l@ condition, Voltage-dividing resistance means connected References Cited in the file of this patent UNITED STATES PATENTS across the output of said ampliñer, switching means for disconnecting from said input circuit said input Voltage for development yin said input of said »amplifier of ya poten 2,359,767 Keinath _____________ __ Oct. 10, 1944 2,366,913 Le Clair ____ _1_ ________ __ Jan. 9, 1945 tial difference representing the difference between that 2,575,711 Hippie _____________ __ Nov. 20, 1951 across said integrating capacitor and that developed by 2,577,735 Broomell ___________ __ Dec. 11, 19‘51 said resistance means, and means including said switching 2,663,855 Beggs _______________ __ Dec. 22, 1953 means for applying as the sole input to said measuring OTHER REFERENCES system -a potential difference derived from said resistance means for operation of said measuring system to produce 10 Publication: “A Combined Current Indicator and In tegrator,” on pages 688490 of “The Review of Scientific an output proportional to the magnitude of the integral Instruments,” vol. 22, No. 9, Sept. 1951. with respect to time of said magnitude of said condition.