US2605332A - Electronic analyzer - Google Patents

Description

July 29, 1952 J. H. PARSONS ELECTRONIC ANALYZER 4 Sheets-Sheet 2 Filed March 17. 1949 INVENTOR. Ho ward Parsons 4 Sheets-Sheet 3 Filed March 17. 1949 E? 6 3 r W C w an e e u @w W W 0, d 6/5 Wm m a c 9 W A Z X V h r em i ,w h mm m u wm a w/ P1P. d 3 .W 3 h s w 4 W Y. M 0 w TNT ENTOTQ.

J. Howard Parsons y 1952 J. H. PARSONS 2,605,332

ELECTRONIC ANALYZER Filed March 17. 1949 4 Sheets-Sheet 4 6' 7 1 115 Ill ,EZEIB- IN V EN TOR. J Ho war-d Parsons BY flw/a fi flTTOE/VEY Patented July 29, 1952 to the United States of Americaas represented I a 41 by the United States Atomic Energy'comm'isa sion Application 'Maich ll, 1949, Serial Nantes l My invention relates to electronic" analyzers and more particularly to ajsy'stem for electronically classifying, cataloging and accounting of the magnitude distribution of a series of events, and is related to the invention disclosed in my co-pending application Serial No. 53,794.

In the physical sciences it is often necessary to determine the magnitude distribution of a series of events. Each event in a series of physical events will occur with a magnitude that is controlled by the operating physical laws. A physical event can be defined as the occurrence of any phenomenon, and the magnitude of the event as a quantitative measure of a variable such as size, brightness, or duration. A series of events is characterized in part by the number of events in each increment of magnitude throughout the spectrum of magnitudes and thisdistribution is the magnitude distribution. The physical laws that control a series of events can be-studi'ed under certain conditions if the magnitude distribution is known. For example, the laws governing grain size in a photographic film may be studied if .the distribution of grain size produced under :varying conditions can be obtained: The magnitude distribution ofa series 'ofzevents may-be obtained by classifying each event asto size, and

cataloging and (counting the number of events in each increment of magnitude. mination, if performed manually. will be slow and willhave a low probability of beinga'truerepresentation of the magnitude distribution oft-he series of events, be cau se determinations are statistical in nature and involve large numbers of events, each of which must be operated upon by the observer. The observer canonly classify an event within a finite incrementof magnitude; therefore, the determination is only approximate.

since; manual determinaticnfis slow and inaccube a common one. In addition tothis translator,

the systems involve a discriminator that will distinguish between true observationsfand interferifig" efi'ect's, a classifier that will measure the rep:

3 Glaims; (CL-177 3 11) Such azdeterresentative pulse'voltage, and a cataloger and counter that will record the data in tabular or graphical form.

7 Systems for providing information of the above character have particular usefulness in the field of measurement of energy releases during nuclear changes, such as the distribution of kinetic energies of alpha particles released by the nuclei of certain radioactive isotopes. In one specific application, the energies of the alpha particles were translated into proportional voltage pulses in an ion chamber; Heretofore, the sample was placed in an ionization chamber and alpha particles emitted therefrom served to ionize the gas within the chamber. A voltage change proportional to the energy of the alpha particle was produced oh a collecting electrode as a result of the ionizanon of the gas and the collection of the ions or electrons. This voltage change was amplified and measuredand served as an indication of the magnitude distribution of the alpha particles, and for the purpose, variousforms of systems having different degreesof response and accuracy were employed. However, if electronic systems of classifying, cataloging and counting areto realizev their full usefulness, they must .operate on events at a high'ra'te, and the results ofthese operations must reveal fine detail of magnitude distribution. If fine detail is to be retained, eitherthe increment of classification mustbe 'very small, or the increment of classification must continuously vary its observational point. .While the system of my copending applicatioii, supra, generally meets these requirements, it will be apparent that such system does not classify, catalog and-count each and every event a series, but operates on a representative group. That system is, therefore, not useful for all types of magnitude distribution studies, 7 especially ivhereanumber of selected events are not representative of the series, where the events dor'iot repeatin some fashion, or where the total number-of eveiitsissmall, necessitatmg the 'classisflcation; cataloging-and counting of each and eve y event.

Applicant with knowledge of the problems of the prior art has for an object of his invention the provision-of a system which will act upon'each ana-evry vem of a series to determine the mag jnitude-di stribution-of evelits. v Applicant'has as another-object of his invention the'prevision of a system for classifying the events of a series to determine magnitude distribution by converting the events into propora photographic film or plate to reproduce the displacement distribution which is an exact representation of the original magnitude distribution with all fine details preserved.

Applicant has as a still further object of his invention the provision of a system for classifying the events of a series by converting the events into voltage pulses and translating pulse voltage into a proportional time interval.

wave form I are observed by translator 2 and are converted to representative voltage pulses. They are passed through the classifier 3 to the horizontal deflecting plates of a cathode ray tube 4 Where they are utilized to position the beam of the cathode ray tube, and form traces on the screen 5, whose displacement from the reference position is'determined' by the magnitude of the event as a function of pulse or signal magnitude. Each pulse size acts to cause a bright line to be drawn on the screen with displacement corresponding to signal magnitude Cataloging is accomplished by photographing the series of result- Applicant has as a still further object of his,

invention the provision of a system for classifying the events of a series wherein linear drivin amplifiers for the cathode ray tube indicator are eliminated. n

Other objects and advantages of my invention will appear from the following specification and accompanying drawings, and the novel features thereof will be" particularly pointed out in the annexed claims. j In the drawings, Fig. 1 is a schematic of an arrangement for classifying, cataloging and recording events. Fig. 2 is a graph of a microdensitometer recording of magnitude distribution. Fig. 3 is a schematic of a displacement analyzer form of system for determining magnitude distribution. Fig. 4 is a schematic of one form of integrating circuit and 'restorer suitable for incorporation into my improved system. Fig. 5 is a series of graphs of voltages plotted against time at a plurality of points in the displacement analyzer form of my improved system. Fig. 6,

is a schematic of the synchronous analyzer form of system for determining magnitude distribution. Fig. 7 is a graph showing a plurality of curves of voltages plotted against timeat'a seriesof points in the synchronous analyzer form of my improved system. Fig. 8 is a photographicrecord of a plan view of. a cathode ray tube screen showing a series of lines which representmagnitude distribution of events as recorded by the second form of my improved system. Fig. 9 is a detail of a suitable form of voltage comparator and a fragmental showing of a portion of a restorercircuit which may be incorporated'in the synchronous form of my improved system. Fig. 10 is a schematic of a form of L, C circuit suitable for incorporation into the synchronous form or type of my improved system. r Referring to the drawings in detail, and particularly to Fig. 1, a'suitable translator, forob- 7 serving an event I and translating the observation into an electronic pulse, such as a photoelectric tube, an ion chamber, orthe like, is diagrarnmatically indicated at 2. It feeds into aclassifier 3 and then to the cathode ray tube 4. Linesproduced on the screen 5 of the cathode ray; tube" 4 are projected through the 'lens 6 ofasuitable camera upon a film 1. While the details ofthe circuits of the different forms of the preferred system will 'be described atlength hereinafter, this diagrammatic illustration will serve to clarify the general procedure. employed, and provide a reasonable understanding of the arrangement of elements in a system necessary to accomplish the desired results. v 5 u Events as indicated diagrammatically by the ing positions of the beam on the screen 5. This is carried out by the camera 6 and a photographic plate or film 1 on which is produced a catalog of beam positions having a displacement distribution that is an exact representation of the original magnitude distribution with all fine detail preserved. Counting is accomplished by means of a recording microdensitometerinot shown).

This instrumentwill plot distribution of beam 7 positions and hence the magnitude distribution. A graph or densitometer tracing of such magnitude distribution will be found in Fig. 2.

In the displacement analyzer form of system disclosed in Fig. 3,'input derived from any event observation pick up, such as an ion chamber and/or conventional amplifier generally designated as translator 2', is fed into a pulse integrator 8, to be described more in detail hereinafter. The integrator 8 feeds into the horizontal deflecting plates of cathode ray tube 4 and is controlled by the restorer 9, described more in detail hereinafter. The input also feeds through delay line or circuit ID, of known or conventional form. Thedelay network functions to withhold the trace from the cathode ray tubescreen until the output of pulse integrator 8 has reached its peak value- The delayed output signal is impressed upon a univibrator I I of any suitable type tube 4, for a period depending upon the time constants of .the circuits thereof, before returning to its stable condition. The univibrator out- .put is also coupled to a network which includes condenserv l2, and resistors l3, l4. This latter network is connected at the juncture of condenser I2 and resistors l3, M to one of the vertical-defleeting plates of the cathode ray tube 4. -In this way the condenser I2, which is connected to one vertical deflecting plate of the cathode ray tube 4, is charged up through resistance [4, while resistance 13 serves toleak off the charge from condenser l2 to ground.

Consider the operation of the system for a single pulse andfollow, the results thereof at the various elements of the system as indicated in the graph of Fig. 5 drawn to correspond to positions on the cathode ray tube screen. The pulse is appliedthrough the input at A to the pulse integrator 8. The shape of the applied pulse is generally indicated by curve A in the graph of Fig. 5'. The output voltage of the pulse integrator 8 will follow the rise of the input pulse until such pulse has reached its maximum voltage, as is indicated by curve B of Fig. 5. "This output voltage, which, aswill be shown, determines the horizontal position or. displacement of the trace on the'screen of tube 4, will then remain constant until some restoring action takes place; The intensity rid of the cathode ray tube 4 is negaconventional delaycircuittz and the delayed pulse is then simultaneously applied at. point Y to a saw-tooth generator 33 and a univibrator. The saw-tooth generator may be ofconventional vtypesuch as disclosed 'in Hoag on Basic Radio,

published in 1942 by D. Van Nostrand Co Inc., New York, N. Y. pages 165, 168 and 234, or used generally in radar systems, or may be of any known type which is suitable for the purpose. Also the univibrator may be of any suitable known type, but is preferably of the type disclosed in my copending application, supra. This delayed pulse serves toactu ate univibrator 34 and sawtooth generator 33 .after the output of the pulse integrator 30 has reached its maximumvalue. The saw-tooth generator 33 is coupled to the biasing circuit of the comparator 3|, and serves to 'render it operative. A univibrator in the comparator 3| will trip when the voltage of the sawtooth from the generator 33 is equal to or overcomes the biasing voltage of the integrator 30 at point Z. The time required for the saw-tooth voltage-to go from zero to the voltage produced by the integrator will be proportional to the magnitudeof the voltage on the integrator which corresponds to the peak voltage of the pulse.

Therefore, a measure of this time will be a meas-' ure of peak voltage of the original pulse.

The univibrator 34 commenced operation in response to the same pulse at point Y that rendered the saw-tooth generator 33 operative. The generated square wave of univibrator 33 is impressed upon an L. C. circuit 35, to be described more in detail hereinafter, and the resulting out of phase voltages cause the beam of a cathode ray tube 36 to sweep in a circular fashion. When the univibrator in the comparator 3| is actuated by the saw-tooth wave, the intensity grid of the cathode ray tube 36 acts to intensity the beam. The comparator also feeds into restorer circuit v31, described hereinafter in connection with Figs.

9 and 10, for closing circuits about components of the L. Cjcircuit 35 and reducing their potentials substantially to zero for de energizing them. This has the efiect of producing a bright radial line 38 on the screen of the tube 36. The angular position of this line is a measure of the proportional time; In addition, the restorer 31 acts "upon the collapse of the square'wavesignal from comparator3| to remove the peak output voltage from the output of the integrator 30 and restore it to normal inoperative condition. The other circuits are also restored to normal condition and the cycle repeats with each subsequent pulse.

Thus the angle and/or position of'the radial line on the scope' or screen is a measure of peak voltage of the pulse. A photograph of a series of these radial lines as indicated in Fig. 8, will be however, would result in a linearcatalog which could not effectively utilize tube size. Another modification might employ a spiral catalog which would tend tov improve tube screen utility, and

could be realized by replacing the L. ;C. circuit 35 with an R. L. C. circuit. v

Referring now to Fig. 9 which discloses a detailed circuit of a-preferred form of the voltage comparator 3| and a fragmental, portion of the restorer, 31, an electric discharge device, such as triode 39, is fed throughits control grid from the output ofthe pulseintegrator 3. In this arrangement a coupling condenser 40 is employed to couple the control grid to the integrator 30. This grid isnormally maintained at ground potential by thegrid resistor-4|, while the drop across cathode resistor 42 normally biases the cathode sufficiently positive to maintain the tube in substantially cutoff condition. The anode of tube 39 is fed throughloadresistor Ill from voltage source H and is coupled through .a resistor 43 and-blocking condenserv 80 to one end of a plurality of diodes, M, 44, 44 which are themselves connected in series between locking condensers 45, 45.. A ground return for the system is completed through the resistors 41, 3|. In addition this diode circuit is coupled through condenser 45 to saw-tooth generator 33. The diode circuit feeds into a univibrator which includes a normally inoperative triode 48 coupled through resistor 50 and condenser 5| to normally operative triode 49. The control grid of triode 48 is maintainedat substantially ground potential by input resistor 52, and the cathodes of triodes 48, 49 are joined together and coupled to ground through a common cathode resistor 53. This univibrator circuit is similar to that disclosed and used in the system of my prior copending application, supra, where'its operation is fully described. Y

The output of the univibrator of comparator 3| is connected to the intensity grid of cathode ray tube 36 and controls the beam intensity of such tube since it is normally biased to cut off by. any suitable source (not shown). It also feeds the restorer 31, passing through a differentiating and clipping network, including condenser 54 and resistors 55, '|||,v to the control grid'of -triode 56. Theoutput of tube 53 feeds through line51 totube l4 an'dtoltubes 58, 59, 59. .ofthe restorer shown in detail in Fig. 10'. It will be apparent that the restorer circuit is similar in most connection with Fig. 4. .1 In its operation, a pulse at point A, indicated by curve A of Fig. 7, is fed to integrator 30 causing it to impress a wavesuch asis indicated by curve Z-of Fig.7 through condenser 40 upon the controlgrid of tube 39. In response thereto tube 39 fires or commences to conduct. This causes a negative pulse to appear at H of similar configuration to that denoted by the curve positioned adjacent that point: This action places a bias on 'the diodes 44, 44,44,- and such bias is maintained until overcome by the rising potential of the saw-tooth wave delivered byge'nerator 33 at point X and indicated by curve X of Fig. 7. Thereafter a positive potential is placed upon the control grid'of tube 48 so' that the univibrator portion, including,tubes48,i49, of the comparator 3| delivers a square or rectangularwave, as indicated by curveW of Fig. '7, to raise the potential of the intensity grid of the tube 36 so that the beam may appear upon the screen of the cathode ray tube? It also impresses a square or rectangular wave on, the restorer circuit 31 including condenser. andlresistor 10, which differentiates it in theimanne'r heretoforede'sc'ribed in connection with Fig. .4, creating a clipped positive and' a sharp negative'pulse, and rendering tube 56 op- .erative. :Qpe'ration "of tube 56 produces, in its output circuit, a small negative pulse at the formation of the rectangular pulse and a very much larger positive pulse ,of substantially rectangular configuration as aresult of the collapse of the rectangular pulse. The configuration of the pulse is controlled bythe clipping action causedby the resistor 55'inthe grid circuitof the tube. This positive pulse at the anode is then led by line'51 to tubes 58,;59','a'nd 59 of Figi-lfl to overcome their negative bias and renderthem 'oprative'ifor the purpose indicated hereinafter. It is also fed through condenser H to the input circuit of tube '14 which is normally biased to cutofi by source 13 acting through resistor 12. By overcoming the bias the tube 74 is rendered conductive and provides a discharge path to ground through lead I for the control condenser of pulse integrator 39, rendering the tube therein inoperative, as heretofore described in connection with the circuits of Fig. 4. This restores pulse integrator for the next pulse.

Referring now to the L. C. circuit of Fig. 10, it will be noted that line 51 from the first tube of the restorer circuit 31, referred to above, feeds the triodes 58, 56, and 59' also of the restorer circuit, through blocking condensers 60, 6 I, and 6!. Triodes 58, 59, and 59' are preferably negatively biased to a point at or near cutofi by E. M. F.

sources 62, 63, and 63, respectively, coupled through resistors 64, 65, and 65'. The L. C. circuit consists essentially of a condenser 66 and and an inductance 61 connected by leads 68, 69 and a ground connection across the horizontal and vertical plates, respectively, of the cathode ray tube 36. The anode circuits of triodes 5B, 59 and the cathode circuit of tube 59' are then connected to the leads from the condenser 66 and inductance 61 of the L. C. circuit to control their 59 and the cathode of tube 59' are tied to the inductance 61, it will be noted that tube 59 can operate only over the time interval represented by the positive portion of the voltagecharacterl istic curve L of the Fig. '7, and that tube 59' will operate over the time interval represented by the negative portion of that curve.

When a pulse, delayed by line or network 32 of Fig. 6 reaches the input of univibrator 34, it

produces a rectangular or square pulse in the output thereof, and its relation to other pulses and waves of the system is indicated by curve V of Fig. 7. This wave is impressed upon the L. C. circuit 35. As a result the entire voltage of the impressed wave appears across the inductance 61 at the moment of rise of the impressed wave. The voltage on inductance 61 will become lessaccording to the well-established cosine law and the voltage on condenser 66 will build up according to the well-established sine law. The relationships of these voltages are indicated at L and C of Fig. 7. These are also the voltages appearing on the vertical and horizontal deflecting plates of the cathode ray tube 36 and give a comparison with the other Waves or voltages at various points in the system. At the point where voltage comparator 3! acts to remove the voltage on the intensity grid of cathode ray tube 36, it also acts on the restorer circuit 31 to cutoff tube 56, which permits tubes 58, and 59 or 59 to return to the operative condition. This is accomplished by the collapse of the substantially rectangular positive waveappearing at the output of tube 56 as a result oithe cessation of 10 signal from the comparator 3|. The collapse of the square wave from comparator 3| was differentiated by condenser 54 to provide a negative pulse on the control grid of tube 56 of Fig.

"9. and cause it to become less conducting. This produced a substantially rectangular positive wave on the output of tube 56 which overcame the bias on'tub'es 58,and 59-or 59', depending upon the timing thereof, and rendered them operative. The operation of tubes 58, 59 or 59 provided low impedance paths around condenser 66 and inductance 61 to ground and abruptly interrupted the voltage relation curves, as indicated at L and C of Fig. 7. However, lack of further signal from comparator 3| leaves tube 56 in a substantially nonconducting state and with the collapse of the positive wave in the output circuit of tube 56, the negative bias on tube 58 and tube 59 or 59' returns them to the nonconducting state. With the charge removed from the plates of cathode ray tube 36 and tubes 58, 59, or 59 rendered nonconducting, the system is readied for the next pulse. In this connection it will be understood that if the positive wave arrives through lead 51 at the time when the voltage across the inductance 61 is positive, as indicated by the characteristic curve L of Fig. '7, the tube 59 will conduct. However, if the positive wave arrives on lead 51 at a time when the voltage across inductance 6! is negative, as indicated by the characteristic curve, then tube 59 alone will operate.

In connection with the system of Fig. 3 it may be noted that the conventional driving amplifiers for the cathode ray tube have been omitted. This was done for the sake of simplicity.

While the heater elements for the various tubes and the power supply has not been included herein, it will be understood that they are of conventional form and were only omitted for the purpose of clarity in disclosing the more important details of the invention' In addition, applicant has indicated the restoring circuit for the pulse integrator 30 as a part of the general restorer circuit31, but it will be understood that an entirely separate restorer, such as disclosed at 9 of Fig. 4, may be employed, and that it may be fed from point W of Fig. 6.

Having thus described my invention, I claim:

1. A system for determining the magnitude distribution of a series of events comprising a translator for converting the events into electronic pulses, a pulse integrator fed by the translator for producing and sustaining a signal corresponding to the magnitude of each of said pulses, an indicator for reproducing the signals from the integrator, and means responsive to said pulses for controlling the operation of the indicator and for restoring the integrator.

2. A system for determining the magnitude distribution of a series of events comprising a translator for converting the events into electronic pulses, a pulse integrator fed by the translator for producing and sustaining signals corresponding to the peaks of said pulses, a cathode ray discharge device having a screen, said discharge device being fed by said integrator to reproduce the signals on its screen and 11 12 t-ronic pulses, a, pulseintegratorfed by'the translater for producing and sustaining signals, cor- REFERENCES CITED responding to t e m gni ud Of -Sa d:D 1 The following references are of record in the cathode ray discharge device having a screen for file of thi patent; reproducing said signa1s;,; anda control circuit inoluding a delay circuit responsive to, said pulses a ;j ES: PATENT-s for activating said discharge-device to ,display Number Name 1 Date thesignals and for-restoring saidfdntegratpr to 2,094,733 Byrnes Oct. 5, 1 937 inqperatilve position, a M 2,398,988 ZGibOlZ April 23, 51946 V 2,422,766 Alexander -June 2 l, 1947 J wARb R N 2,477,395 Sunstein July 26,1949

Images