US2466207A

US2466207A - Device comprising a cathode-ray oscillograph adapted to make at least two measuring voltages simultaneously perceptible

Info

Publication number: US2466207A
Application number: US663809A
Authority: US
Inventors: Carpentier Edmond Egbertus
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1942-02-09
Filing date: 1946-04-22
Publication date: 1949-04-05
Anticipated expiration: 1966-04-05

Description

April 5, 1949. E. E. CARPENTIER DEVICE COMPRISING A CATHODE-RAY OSCILLOGRAPH ADAPTED TO MAKE AT LEAST TWO MEASURING VOLTAGES SIMULTANEOUSLY PEHCEPTIBLE Filed April 22, 1946 FIG. I

FIG. 2

iNvENToR EDMOND EGBERTUE CARPENT ER ATTQRNEY Patented Apr. 5, 1949 UNITED sTATss DEVICE COMPRISING A CATHODE-BJAY OSCILLOGRA'PH ADAPTED TO MAKE AT LEAST TWO MEASURING VOLTAGES SIMULTANEOUSLY PERCEPTELE.

Edmond Egbertus Carpenti er, Eindhoven, Netherlands, assignor, by me s'nelassignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application April 22, 1946, Serial No. 663,809 In the Netherlands February 9, 1942 Section 1, Public Law 690, August-8, 1946 Patent expires February 9, 1962 5 Claims. (Cl. v31!5-26) This invention relates to a device adapted to make 'tWO or more non-recurring or recurring phenomena simultaneously perceptible, measuring voltages corresponding to these phenomena alternately controlling in rapid sequence the devflection in one and the same direction of the cathode-ray beam of a cathode-ray oscillograph. The measuring voltages may then alternately be supplied, for example with the aid of a rotary mechanic switch (cfqfor example British patent 1.-

specification No. 403,060), to a deflection system of the cathode-ray oscillograph, whereas the other deflection system has supplied to it, for example, a time-base voltage which in the case of recurring phenomena varies preferably in synchronism with one of these phenomena or a harmonic thereof.

For the purpose of alternately supplying the phenomena to the oscillograph, discharge paths serving as inertialessswitches are preferably used instead of mechanic switches. Diodes or block 'ing-layer rectifiers may" be used, for example,

which are blocked perio'dically'with-the aid of an auxiliary alternating voltage of preferably sinusoidal or" rectangular form (of. British patent specification 476,224). It is also possible'toutilise gaseous discharge tubes as substantially inertialess switches (of. for example the article by R. Sewig-in Zeitschrift fiir technische Physik1933-, vol. 14, pages 152; 153). grid-controlled high-vacuum tubes may be used as switching tubes (of. for example the last-mentioned article and also French patent specifica- -tion 654,354 and British patent specification The auxiliary voltage required: when discharge pathsare used as switches, which voltage'prefer- :ably varies rectangularly with time, may be generated, for example, with the aid of a cathoderay tube in which a certain number of collecting electrodes are arranged beside each other and successively -struck by the cathode-ray beam (of. for example the above-mentioned French patent specification No. 654,354), or it may be derivedfrom a multivibratorcircuit.

The frequency of.switching, he. the frequency of the auxiliary voltage, for non-recurring phenomena is chosen in such manner that it is considerably higher :than the fundamental fre- ;quency of the phenomenato @beobserved; in the- Further, the ordinary case of recurring phenomena the frequency of switching, in addition to being considerably higher than the fundamental frequency, may be chosen such that it corresponds td the fundamental frequency or a subharmonic thereof (cf. for example the above-stated British patent specification No. 403,060). In the former case the screen of the cathode-ray tube has formed on. it curves produced in points, in the latter case not interrupted curves.

The known devices of the indicated type, independently of the switching device or the frequency of switching utilized, have the drawback oscillogram may be avoided as much as possible.

According to the invention, the said drawback in devices of this kind is obviated by that the times-during which at least two of the measuring voltages control the deflection of the cathode-ray beam are made difierent from each other.

For example, when taking a twofold oscillo- =gram, one thus obtains that the measuring voltage having the larger amplitude is longer active than the other measuring voltage. Since the mean quickness of writing of the cathode-ray beam (i. e. the quickness with which the cathode- .ray beam is moved across the screen) increases with the amplitude of the measuring voltage to be recorded, as a result of which the light intensity of the image obtained is smaller according as the amplitude is larger, the effect of the greater quickness of writing'upon the light intensity is neutralised by causing the measuring voltage having the larger amplitude to be longer active. It is thus possible with measuring voltages having'different amplitudes to obtain curves of at least substantially equal light intensity and consequently equal sharpness.

For the purpose of obtaining an optimum adaptation of the times during which the'diiferfigure.

.4. uring voltage A will act'npon the oscillograph during a longer time than the measuring voltage 1 B, so that with a larger amplitude of the mess-- Fig. 2 showsas a function of time the auxiliary voltageused in the device of Fig. 1 for switching. In Fig. 1, I and 2 are amplifying tubes serving:

respectively to amplify the measuring voltages,

A and B supplied to the control grids concerned,

the amplified measuring voltages set up at the anode resistance which is common to both tubes being suppliedvia a condenser lto'the vertical deflecting electrodes of a cathode-ray o'scillograph 6. A sawtooth time-base voltage- 9 is supplied to the horizontal deflecting electrodes, for example via terminals 8.

The amplifyingtubes l and 2 are alternately released and blocked in rapid sequence by means of a rectangular auxiliary alternating voltage which is set upat aresistance Ill interposed-be tween the screen grids of the amplifying tubes I and 2 and is derived from a multivibrator cir- V cult of a construction :known per se;

For the mutual displacement in thevertical uringvoltage A curves of equal intensity and sharpness are nevertheless obtained.

As mentioned above, it isadvantageous to regulate the ratio of the times t1 and t2. In the device Shown this y be effected by varyin the resistance H1 in the multivibrator circuit, as 18 schematically indicated by an arrow in the It. is evident that the invention may be applied similarly to-devices for oscillographin'g more than two measuring voltages. 'In recording, for ex-" ample, non-recurring electrical phenomena of ,which the variation of voltage and'current-in a circuit as a function of time, as well as a sinusoidal reference voltage must be recorded simul- 'taneously, it is frequentlyadvantageous that the voltage and the current to be measured are active during approximately equally great times, but that the'reference voltage is active only during a considerably shorter time. age required therefor may be generated, for ex-- ample, with the aid of a. rotary mechanic switch,

"the extremity of a switching arm moved with direction of the curves A, B produced on the screen of the cathode ray tube, the cathodes of the amplifying tubes are connected to an ad-' justable tapping point of the resistance Hi.

The multivibrator circuit comprises tWopush- 7 null connected and crosswisefeedback-coupled' screen-grid tubes l2, 13, the feed-back being effected 'Withthe aid of. condensers l4, l5 connested between the screen grid of the one tube and the control grid of the other tube.

The control grids of the tubes are connected to the earthed cathodes through resistances l6 and [1 respectively, while screen-grid resistances I8, [9 are connected to the positive terminal 22 of a source of direct voltage (not shown) through a resistance 2! shunted by a condenser 20.

The output voltage of the multivibrator circuit is derived from the anode resistances 23, 2d and supplied to the resistance ill via. separating condensers 26. The point of connection of the

anode resistances

23, 23 is also connected to the terminal. 22 of the source of direct voltage.

In the known devices of the indicated type for producing twofold oscillograms, the multivibrator circuit is constructed entirely symmetrically, so that the times during which the amplifying tubes 1 and 2 were alternately active and hence also the times during which the different measuring voltages controlled the oscillograph were always equally great.

According to the invention, in the device shown the symmetry of the multi-vibrator circuit is intentionally avoided, for example by giving equal values to the condensers M, I5 but different values to the resistances l6, IT.

The output voltage on of the asymmetric multivibrator circuit thus obtained exhibits, for example, the variation shown in Fig. 2 as a function of the time t, the time t1 during which the tube i2 is traversed by current and consequently the am lifyin Lulu: l 1:: blocked, bclug considcrably smaller than the time 252 during which the tube I3 is traversed by current and the amplif ing tube- 2 is blocked. Consequently, the mensuniform quickness touching successively three different contact surfaces, two of which are of equal width, whereas the third contact surface has a considerably smaller width.

.In addition .to' the stated advantage of equal intensity of all the curves produced, with'the' use I of the inventionone also obtains, for example, in the last-mentioned case, a more detailed reproduction of the Dhen'omen'a to be'meas'ured,

It has been found that in particular when the I multiple oscillograms obtained, are photographed an appreciable improvement is achieved'by'the use of the invention. I WhatI claim is:

ll An oscillographic system adaptedtoexhibit simultaneously along a common time base the waveforms of a plurality of voltages having different amplitudes, said system comprising a cathode-ray tube having a fluorescent screen and first and second deflection means for displacing the ray in mutually perpendicular directions, means to apply a sawtooth time base wave of a prescribed frequency and amplitude onto one of said deflection means, and means independent of said base wave to apply sequentially onto the other of said deflection means each of said voltages for a period whose duration depends on the amplitude thereof whereby the waveforms displayed on said screen are of substantially like intensity.

2. An oscillographic system adapted to exhibit simultaneously along a common time base the waveforms of first and second voltages having diiferent amplitudes, said system comprising a cathode-ray tube having a fluorescent screen and first and second deflection means for displacing the ray in mutually perpendicular directions, means to apply a sawtooth time base wave of a prescribed frequency and amplitude onto one of said deflection means, means to apply alternately said first and second voltages onto the other of said deflection means, and means independent of said base wave to control the time ratio of the periods during which the respective voltages are applied onto said other deflection means in accordance with the ratio of the amplitude of said voltages.

3. An oscillographic system adapted to exhibit simultaneously along a, common time base the waveforms 01' first and second voltages having The auxiliary voltdifferent amplitudes, said system comprising a cathode-ray tube having a fluorescent screen and first and second deflection means for displacing the ray in mutually perpendicular directions, means to apply a sawtooth time base wave of a prescribed frequency and amplitude onto one of said deflection means, a pair of amplifiers each arranged to impress a respective one of said first and second voltages onto the other of said de flection means, and means independent of said base wave for alternately rendering said amplifiers operative for a period whose duration is proportional to the amplitude of the voltage applied as an input thereto.

4. An oscillographic system adapted to exhibit simultaneously along a common time base the waveforms of first and second voltages having different amplitudes, said system comprising a cathode-ray tube having a fluorescent screen and first and second deflection means for displacing the ray in mutually perpendicular directions, means to apply a sawtooth time base wave of a prescribed frequency and amplitude onto one of said deflection means, a pair of amplifiers each arranged to impress a respective one of said first and second voltages onto the other of said deflection means, means independent of said base wave for alternately rendering said amplifiers operative for a period whose duration is proportional to the amplitude of the voltage applied as an input thereto, said last named means including an asymmetrical multivibrator producing alternating rectangular pulses, each of said pulses being applied to said first and second amplifiers to disable one and simultaneously render the other operative.

5. An oscillographic system adapted to exhibit simultaneously along a common time base the waveforms of first and. second voltages having different amplitudes, said system comprising a cathode-ray tube having a fluorescent screen and first and second deflection means for displacing the ray in mutually perpendicular directions, means to apply a sawtooth time base wave of a prescribed frequency and amplitude onto one of said deflection means, a pair of amplifiers each including an electron discharge device having a control grid, a screen grid a d an anode, the anodes of the amplifier devices both being coupled to the other of said deflection means, means to apply said first and second voltages to the respective control grids of said amplifier devices, and an asymmetrical multivibrator independent of said base wave for alternately rendering said amplifiers operative, said multivibrator including a pair of electron discharge devices each having a control grid, a screen grid and an anode, said pair of devices being arranged in push-pull relation, the screen grid in each of said pair of devices being feedback coupled to the control grid in the other, the anodes of said pair of devices being coupled respectively to the screen grids of said amplifier devices.

EDMOND EGBERTUS CARPENTIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,945 Bedell Dec. 13, 1938 2,221,115 Shepard, Jr Nov. 12, 1940 2,300,999 Williams Nov. 3, 1942 2,375,709 Thompson May 8, 1945