FR2495332A1 - Electronic valve for detection of magnetic field - has modulating grid signal neutralising space charge for wide temp. range operation and giving signal related to electron beam deviation - Google Patents

Abstract

The detector tube comprises a filament with direct heating via a dropping resistor. A control grid is coupled through a decoupling capacitor to a modulating or chopping signal while a resistor provides a bias for the grid. A screen grid is connected to the positive power rail while a suppressor grid is connected internally to the filament. An anode connected to a load resistor provides an output signal when a magnetic field is detected. The field affects the electron flow from filament to anode and the modulating signal neutralises the space charge. Two detectors may be connected into a multivibrator circuit such that an incident magnetic field causes changes to the output amplitude and frequency. The device produces a direct read-out of the magnetic field by the deviation of the electron beam path.

Description

 The proportional detection of variable magnetic fields, capable of measuring the DC component thereof, while ensuring faithful detection at wide frequency band, is only partially carried out by certain semiconductor processes.

 However, these processes, either because they are based on certain properties of certain semiconductors, themselves, or because they require semiconductors, for their operation, are very thermally limited, by definition.

 These thermal limitations are not only limits at high or low levels of temperature, but also and above all, in the useful range of these sensors in the fact of non-negligible drifts which distort the measurement values. Temperature ranges such as - 600 C to + 2500 C are prohibited, both by the extreme operating limits and by the drifts of the useful signals in the range considered.

 The present invention remedies these drawbacks, but it also provides numerous possibilities, most of them unprecedented, with notable sensitivities, increased precision and incomparable stabilities.

 In particular, the function translating the value of the incident magnetic field into electrical measurement is obtained directly in the form of voltage, without it being necessary to call upon auxiliary electronic elements for demodulation.

 On the other hand, the possible introduction of modulation or chopping signals makes it possible to obtain useful signals referenced to an electrical level, an increase in performance by neutralizing space charges, and a possible transmission at a distance over a carrier frequency perfectly determined.

 The present invention makes use, in particular forms and under certain well-defined conditions, of the phenomena of electron deflection in a vacuum tube under the influence of an incident magnetic field.

 The physical and mathematical operating conditions of the present invention are explained below.

 Any magnetic field exerts a force on moving electrons, which is the case in an electronic vacuum tube with thermionic emission, because it exerts a force on an electric current which is none other than a set of electrons in movement.

Laplace's law stipulates that a field H exerts on a current element i of length dl a force perpendicular to
H and at i with f = H i dl sin.
If this current corresponds to the passage of n electrons, at the speed v, the charge which passes per second, ie the current, is i = ne, these electrons occupy a length of current
dl which is equal to v
The force exerted on these n electrons y oet therefore
f = H i dl sin. i = H nev sin. .

 So the force exerted by a field H on an electron moving at speed v is a force perpendicular to H and at v it is equal to f = H e v sin. i.

sucking the angle of H and v (degree of perpendicularity),
If the field is parallel to the speed v of the electron 0 (= O and there is no action of the magnetic field.

 If compared to a filament-cathode disposed vertically in the center of a right cylinder formed by an anode, an assembly in which the emitted electrons radially move around the filament, and if an electromagnet is disposed longitudinally around the anode in thus creating a magnetic field perpendicular to the trajectories of the electrons, these will be more or less curved in one direction or another, with a curvature which will depend on the value of the field H and a direction which will depend on the orientation given to the batteries magnetic.

In the example given above, the field H is perpendicular to the speed v of the electrons, that is to say that = 1 and that
f = Hev.

 This force f is at all times perpendicular to the trajectory considered and this results in an acceleration y which equals Hmev. This acceleration is constant and is perpendicular to the trajectory. Electrons therefore tend to revolve around the filament.

d'où

d'où lton peut tirer le rayon r de la trajectoire circulaire

par laquelle on con6gate que la courbure de la trajectoire considérée est proportionnelle au et à e o , (rapport de la charge à la masse de
m l'électron), mais aussi, ce qui est très important pour la détection du champ magnétique, que la courbure de cette traJectoire est inversement proportionnelle à la vitesse électronique v
La présente invention est basée, à des fin de détection et de mesure du champ magnétique, sur la valeur et les variations de l'indice de courbure de trajectoires électroniques, sous lein- fluence d'un champ magnétique.When the field H is perpendicular to the speed v of the electrons, ie quend o (and f = H ev
y corresponds, if H is uniform, to a uniform circular motion on a circle of radius r such that the acceleration Y is the centripetal acceleration

from where

where lton can draw the radius r from the circular path

by which we con6gate that the curvature of the trajectory considered is proportional to and to eo, (ratio of the load to the mass of
m the electron), but also, which is very important for the detection of the magnetic field, that the curvature of this trajectory is inversely proportional to the electronic speed v
The present invention is based, for the purpose of detecting and measuring the magnetic field, on the value and the variations of the index of curvature of electronic trajectories, under the influence of a magnetic field.

 As is clear from the above, it is advantageous to operate with low electronic speeds, that is to say with slow electrons. This will be achieved in the present invention by the use of low acceleration voltages on the electrodes of the electronic tubes used as magnetic field sensors. This is a great technological advantage, because the various magnetic field sensors from the present invention are made, therefore, fully compatible with the circuits and components of modern electronics which operate, for the most part, with low supply voltages.

If these sensors use electronic vacuum tubes, which may seem obsolete at present, they no longer have the great disadvantages of this technique, but they retain them, quite the contrary, indisputable advantages, more particularly on the thermal plane. The interesting characteristic of these sensors, in addition to their high efficiency as magnetic field detectors, is therefore to only require a reduced supply voltage, only a few volts, which does not prevent them from conserving, apart from their sensor function, a certain amplification coefficient which will judiciously be used in certain construction and operating variants of the present invention.
This invention therefore relates to proportional magnetic field sensors produced using electronic vacuum tubes under certain production and operating conditions, which are influenced by incident external magnetic fields which are translated into directly usable electrical measurement. among other things, the particularity of the draw supplied at low voltages in order to obtain electron beams at low electron speed, ives required acceleration voltages which may reach, possibly legality of voltage with the heating of the tube in question. This low electronic speed allows a considerable action in the influence of the magnetic vector on the trajectory of slow electrons, which are, therefore, easily deflected, and even repelled by the incident H field. This results in a significant modulation of the cathode-anode current of the sensor electronic tube, a current which is easy to collect in the form of proportional voltage, or inversely proportional as the case may be, on the anode load.

 The present invention also relates to similar magnetic-chaFps sensors produced with electronic tubes more specially designed geometrically and physically in order to augment the claimed methods. For example, the fact of using very low acceleration voltage allows a considerable approximation of the electrodes, this quiet unthinkable with the usual operation of conventional vacuum tubes, such a modification would fall within the scope of the present invention, the various variants of which are given for information only and not limiting. Similarly, the optimization of the process by various geometrical adaptations of the electrodes would also fall within the scope of this patent.

 For example, if we act simultaneously, as we have already said, a magnetic field and an electric field perpendicular to the electron beam, the deviations given to this beam are both proportional to e / m, charge ratio and the mass of the electron, and depend in a different way on the speed v of the beam. The measurement of the two deviations, which can be carried out, for example, by the measurement of the point of impact of the electronic bombardment of a non-accelerating target makes it possible to overcome, to a certain extent, speed.

 This is why, the use of one or more accelerating electrodes and an anode, single or multiple, weakly ac accelerating, will allow an increase of the phenomenon. In addition, if the control gate, which is close to the electronic emission source, is made positive when at its polarization, much lower voltages will still be made possible.

 But under the new very specific conditions of use of certain electronic tubes as magnetic field detectors, the geometric structures of the tubes in question and their electrodes should not be arbitrary and will be taken into account because they will intervene in the functioning of the sensor.

 Certain miniature and sub-miniature tubes on the market can be directly used as magnetic field sensors and will demonstrate in a first approach the technical validity of the present invention, but certain mounting conditions will have to be achieved both in the electronic structure of the diagram of use, in the value of the power supply and associated elements as in the orientation and the magnetic polarization of the tube, without forgetting the need for a fully closed electro-static shielding to overcome any other influence than that of the magnetic field.

 However, it will be more judicious to produce, by construction, clearly specialized magnetic field detector tubes, taking into account the new technical criteria of the present invention, that is to say, taking into account the values and the direction of the lines of electric force. and magnetic contacts and interactions at the level of the electron beam, which will be suitably directed, concentrated, and whose proportional deviation will, at best, be exploited. To this end, concentrators of external magnetic fluxes, or internal magnetic fluxes, or both, will be carefully constructed, and sometimes made common with certain electrodes of the tube in question, to increase the performance of these new devices, magnetic field detectors.

 We give below, by way of nonlimiting example, a certain number of descriptions and various internal constitutions of magnetic field detector tubes according to the invention.

 If a narrow beam of electrons crosses an electric field, then a magnetic field, both perpendicular to the direction of the electron beam, and If we make sure that the ratio H j E is suitably chpisi, almost all electrons, whatever their speed, will gather at the same point on a final target and we will obtain an impact of the beam at a determined location of the target. If the H field is modified, the impact will move, proportional to the modification of the H field, and all the more strongly as the electric field E will be weak. It is therefore necessary to use low accelerating voltages if one wants to be able to detect weak fields, but in this case the electronic density will also be low. For example, if a cathode ray tube in operation is subjected to a transverse magnetic field, it will show a deviation of the "spot", and this, all the more so as its acceleration (high voltage) will be weak, but also said spot will be less and less concentrated and of lower luminosity.

 It is therefore an acceptable compromise which will be sought between the acceleration voltages and the values of the magnetic field which one wishes to exploit.

 For example, a sensitive magnetic field sensor will be produced with a miniature pentode tube with direct heating, with a common power supply for heating and acceleration of only 3 Volts. The filament is directly supplied by the power source to which it is connected in parallel, the control grid is directly connected to the negative pole of the 3 Volt source, the screen grid is joined to the positive pole, the anode is joined it too in the positive, but through a load resistance of a few tens of thousands of ohms. As soon as the electronic emission appears, a continuous voltage will appear on the load resistance, this voltage, greater than one volt for a correct tube, will be strongly modified by the approach of a small magnet outside the tube, and in certain orientations of the magnetic field at certain positions, the action of the magnetic field will be rnaxbm81é.

In this assembly, it will be possible to bring the grid
control at the negative pole through a bias resistor
and attack it, through a capacitor, for example, by
modulation or chopping signals.

 In this case, the magnetic detection phenomenon will be accentuated, by the fact of the neutralization of certain space charges inside the tube thanks to the applied alternating signals which modulate and even cut the electron beam.

The modulation signals applied to the grid will be collected on the anode charge, with a certain amplification, moreover, the amplitude of which will be inversely proportional to the value of the magnetic field applied to the outside.

 An interesting variant of the present invention will be achieved by replacing an anode in an electron tube with a set of independent multiple anodes which will allow the detection of the position of the impact of the electron beam by the differential currents collected between the various target anodes.

 Another variant of the invention will be realized, in the constitution of a magnetic field detector starting from the usual structures of cathode ray tubes, but in which, the usual fluorescent screen is replaced by a set of multiple anodes with independent outputs.

 The magnetic field detectors produced according to the present invention can therefore be directly used for obtaining the following function t Proportional or inversely proportional output voltage, (f) Value, or direction, of the incident magnetic field. However, as has already been pointed out, the best sensitivity with the best stability of these new sensors will be obtained by the introduction of modulation or chopping signals. Any frequency signal, amplitude of only a few volts, rectangular sinusoidal shape, or other, will greatly improve the operation of the sensor, these signals will preferably be injected on the control grills, but they could be applied on the either of the other electrodes.

 These signals will be collected at the output with a slight voltage gain and their amplitude will be a function of the value of the applied magnetic field. These modulation or chopping signals will depolarize the control gate and neutralize space charges. These signals may come from external circuits or be produced directly at the sensor. We give in fig. 5 Plate 2 the diagram of a proportional sensor whose modulation signals of the electron beam are obtained by a uni-junction transistor directly supplied by the same voltage source. But in this case, as in similar cases where we introduce semiconductors at the level of the sensor, the thermal performance of said sensor is reduced, but this to a lesser extent than in other systems, because the dignoeix in question have no auxiliary action on the sensor.

 We have seen that the output signals have a slight gain compared to the input signals. This makes it possible to consider the sensor as a voltage amplifier in addition to its normal function for detecting magnetic fields, optionally allowing certain variants of use.

 For example, the association of two interconnected sensors, electronically with each other, in a multivibrator, the frequency and amplitude of the relaxation signal thus obtained are a function of the incident magnetic field. In this case, where the basic elements of the multivibrator are sensor tubes, the high thermal performance will be preserved. It would be the same if the sensor itself was associated in multivibrator with an electronic tube having for only function the amplification of tension necessary for the stable relaxation, but in this case it would be necessary to increase the supply voltages of the tube not sensor.

 Interesting variants will be produced by the association of a sensor tube with 1 or more transistors, always with a view to obtaining relaxation for the production of modulation or chopping signals.

 Combinations with integrated circuits are perfectly compatible and usable whenever the required temperature ranges will be acceptable with the operation of the semiconductors used, if these are necessarily intimately linked to the sensor.

 It will no longer be the same if the auxiliary electronic elements are clearly separated from the sensors and not held to the same thermal rigors as these. In this case, the possibility of operating the sensors in very large temperature loops with very small drifts will be retained.

 In a first alternative embodiment according to the invention, the magnetic field sensor is produced using a vacuum tube with direct or indirect heating and, depending on the use or the sensitivity envisaged, of the diode, triode, pentode type. , or muti-grids. This sensor tube is undernourished, preferably with a single voltage used both for heating and for polarization of the various electrodes, with the addition of passive elements such as load resistors, voltage drop resistors, and decoupling capacitors or link. It is subjected to an incident magnetic field of which it translates the value by interaction on the electronic density of the electron beam at low speed. This first variant corresponds to FIG. 3 P1 2 and to the corresponding description.

 It would be within the scope of the present invention to use vacuum tubes more particularly designed for the exploitation of the present process in which the shapes and arrangements of the inner electrodes are more particularly adapted to the phenomenon of magnetic detection and more particularly the constitution of laminar electron beams with directed emission, in sub-miniature tubes.

In a second variant embodiment according to the invention, the detector tube is directly supplied with alternating current.
Of course in this case, only the positive alternation of the signal is modified by the incidence of the magnetic field.

 In a third variant embodiment according to the invention, the tube used is advantageously a pentode tube by which the phenomena of field / voltage translation are increased.

In a fourth variant embodiment according to the invention, a magnet or an electromagnet external to the tube is associated with it so as to obtain an initial magnetic polarization of the sensor. This allows the latter to detect magnetic fields with ambiguity regarding the quality of the incident magnetic pole, but also to be able to detect any modification of the surrounding magnetic field, detection of non-magnetized magnetic targets for example.

 In a fifth variant of embodiment according to the invention, the cliutricede filament resistance is advantageously confused with the ohmic resistance of the magnetic polarization electromagnet, whether this is directly wound on the detector tube, or not.

 In a sixth variant embodiment according to the invention, the magnetic field detector electronic tube used poses an electro-luminous visible function, which allows a brightness proportional to the value of the applied magnetic field.

 In a seventh variant embodiment according to the invention an auxiliary electrical signal is injected onto one or more electrodes of the detector tube so as to cut or modulate the electron beam. This signal, by its action, makes it possible to overcome the space charge effect of certain electrodes, it thereby increases the detection sensitivity and it also makes it possible to obtain a useful signal with component alternative at perfectly determinable frequency, but the amplitude of which will depend on the value of the incident magnetic field.

 In an eighth variant embodiment according to the invention, the electronic tube used as a magnetic field detector comprises an electroluminescent display by virtue of a deposit of fluorescent or phosphorescent material on certain grids or anodes constituted by metallic grids with pitches well defined in a manner to allow direct visualization of the magnetic lines of force of the incident magnetic field. This gives the visualization of the electronic trajectories of the detector tube.

 DESCRIPTION OF THE COFIMENTAIRI2S OF THE FIGURES.

- Figure 1 plate 1 represents, sectional view, an electronic magnetic field detector tube according to the invention.

The magnetic field H H 'is considered to be variable.

If this field H is zero, the electron beams 9 and 92 emitted simultaneously on either side of the filament 1, are concentrated by 2 and 2 'and directed towards the anodes 12 and 12'. These electron beams strike their anode 12 with their flow of electrons and inking an output proportional anode current, these
have previously passed through the control grids 3 and 3 and of acceleration 4 and 4 as well as the supressor grids 5 and 5 'which are brought to the electrical potential of 2 and 2'. The electron beams 9 and 92 are not deflected - if the H field is zero. They will, on the other hand, be deflected, with a more or less accentuated curvature, accentuation depending on the value of the magnetic field H, if this field does not is not zero. These beams will then describe a trajectory such as, for example, 10 and 10. shown, or else 11 and 11 ′, depending on the polarity of the incident magnetic field. In this case, the beams will strike the targets 13 or 13v always along the direction of the magnetic field and the resulting anode current corresponding to the beams will be proportionally deflected from 12 and 12 to 13, or from 12 and 12 'to 13' .

14 is the envelope of the tube considered
3 and 32 are control grids by which it will be possible, if necessary, to modulate or cut the electronic beams,
4 and 42 are accelerating screen grids,
5 and 5 are suppressor grids, usual in pentodes.

 It goes without saying that the electrodes 12 and 12 ′, 3 and 3 as well as 4 and 4 can be electrically merged, which is already the case for the electrodes 2 and 2r1 and, 5 and 5t.

 Figure 2 Plate 1 represents another magnetic field detector tube according to the invention into which magnetic flux concentrators 5 and 5t are introduced. These internal magnetic hubs are both electronic hubs.

 The operating process of this second detector tube is similar to that corresponding to Figure 1 Plate 1.

 The magnetic action on electronic flows is accentuated by the action of flux concentrators. The magnetic field H, H deviates more or less, depending on its value, the beams 9 and 92 emitted, on both sides by the filament 1 and strike the normal anode targets 6 and 6r or the auxiliary anode targets 7 and t or even, depending on the direction of the magnetic field, the auxiliary anodes 8 and 8 '. In this figure, we find in 2 and 2' the control grids, in 3 and 3 the screen grids, and in 4 and 41 the supressor grids always brought to the potential of the magnetic and electronic flux concentrator 5 and 5x. electrically merged with these, 10 is a tube of sensor collector.

 It is in general, for conditions of mechanical ease of construction that the electronic tubes are made symmetrical, but it is possible to produce an asymmetric sensor tube as shown in Figure 3 Plate 1.

- Figure 3 Plate 1 represents an asymmetric magnetic field sensor tube, subjected to a magnetic field H, H '.

1 is the electron-emitting filament,
2 the control grid of the tube, which will be used, optionally and preferably, for modulating or cutting the electron beam 8,
3 is the accelerating grid,
4 is the supresous grid,
5 is the electronic beam concentrator which is at the same time the magnetic H field concentrator,
6 is the anode of the tube
7 and 7 are independent auxiliary anodes which will make it possible to know both the value of the incident magnetic field and the direction thereof depending on whether the beam is deflected in direction 9 or in direction 10,
11 is the envelope of the tube.

- Figure 1 Plate 2 represents a magnetic field detector tube with indirect heating and directed lamellar beam, with associated magnetic flux concentrator.

l is the heating filament of the tube,
2 and 2 'the control grids
3 and 3 the screen grids
4 and 4 the supersizing grids which are electrically connected to the magnetic and electronic flux concentrator 5 and 5
6 and 6 'normal target anodes
7 and 7 'and 8 and 8 are auxiliary anodes allowing the measurement of the deflection of the beam by differential distribution between the anodes 6 and 6 and 7 and 7 or 6 and 6 and 8 and 8t.

9 is the envelope of the tube,
10 the cathode.

- Figure 2 Plate 2 shows the mounting of an electronic magnetic field detector tube with the supply of its electrodes and an associated magnetic polarization.

 The magnetic polarization is carried out by the electromagnet 6, directly wound on the tube 11. This electromagnet 11 also performs the function of voltage jumper necessary for heating the filament which in the case considered is fixed at 1.5 Volt.

 I1 is therefore arranged in series with the filament 1 and it is directly supplied to a pole by the voltage - xV which will be, for example 6 Volts.

 the combination of the polarizing field created by the electromagnet and by one or the other of the incident fields H or H 'will influence the direction of the beam and consequently its density at the level of the anode, the current of this one will decrease according to the value of the magnetic field for a given polarity, for the reverse polarity, the current will increase. This by algebraic addition of the magnetic fluxes considered. This tube which does not have an auxiliary anode could include one, which would allow an increase in these characteristics.

1 is the filament
2 the control grid
3 the screen grid
4 the supressor grid
5 the anode
6 the electromagnet directly wound on the tube
7 a protective resistor of the control gate 2 for possible attack of the control gate by modulation or chopping signals
8 the polarization resistance of the grid. Note that this grid is positively polarized with respect to the filament, because the mass is positive in this arrangement. It is therefore with negative signals applied at E (Lntrée) that the electron beam will be modulated.

 9 is the load resistance of the anode 5 from which the detection or measurement signals will be taken.

 10 is the electrical supply pole of the assembly, relative to the ground. In this case, this pole is negative, (- xV), it is fixed for the considered tube at - 6.3 Volts DC.

 11 is the casing and the shielding of the detector tube.

- Figure 3 Plate 2 shows the mounting diagram of a magnetic field detector tube H, non-polarized, the power supply can be made at will, positive with respect to mass, (+ xV), (in this case - xV is joined to the mass), or negative, (- xV), (in which case + xV is gathered to massage it.

1 is the direct heating filament,
2 the control grid,
3 the screen grid
4 the supresous grid joined internally to the cathode
5 the anode
6 the falling resistance of the filament
7 the capacitor for decoupling the input signals even
modulation or cutting tuels of the electronic flow.

8 the bias resistance of the control grid,
which is positively biased
9 the anode load resistance
10 tube casing and shielding
+ xV or -xV, power supply of the fixture fixed to
+ 6.3 Volt or - 6.3 volt, depending on the polarity chosen
E is the possible X input of siplAdx-modulation
S the output of the measurement signal
H the incident magnetic field - Figure 4 Plate 2 represents a field detector tube as in Figure 2 Plate 2 with in addition representation of the input signals E for cutting the electron beam into l0, and representation of the signals obtained at output S whose the amplitude is a function of the magnetic field H, Vs (f) of H. Recall that the output signals, for zero magnetic field are significantly higher in amplitude than the input signals.

- Figure 5 Plate 2 represents the complete diagram of a detector tube associated with a uni junction transistor which directly generates the modulation signals of the electron beam. LtenRemble requires only one low voltage power source - G volts direct current.

1 is the tube heating filament
2 the control grid
3 the screen grid
4 the grid
3 the anode
6 the filament tension drop resistance
7 the connecting capacitor through which the
control signals
8 the polarization resistance of the control grid
which is positively biased
9 the anode load resistance
10 the uni junction transistor
11 and 12 of the load resistors of the uni-junction transistor
13 and 14 the RC circuit which determines the frequency of the signals
modulation
S the output of the detection or measurement signal
H the incident magnetic field
- xV the supply voltage of the fixed assembly, in the
case considered at - 6.3 volts in direct current.

 -Figure 1 Plate 3 represents the electric diagram of a magnetic field detector tube in which the polarization resistance of the control grid is joined to the filament, at the level of the falling resistance of the latter, which provides the control grill a slight positive polarization with respect to the poin - xY.

1 is the filament
2 the control grid
3 the screen grid joined to ground, (positive pole)
4 the supreuse grid joined internally to the filament
5 the anode
6 filament drop resistance
7 connection capacitor allowing possible application
modulation or chopping signals
8 the polarization resistance of the control grid
9 the anode load resistance
10 tube casing and shielding
E input of modulation signals
S the output of the detection or measurement signal
H the incident magnetic field
- xV the supply voltage fixed at - 6 volts in the case
considered - Figure 2 Plate 3 represents an assembly formed by a magnetic field detector tube 10 and a transistor 15 constituting by electronic association a fairly special astable multivibrator. The output signals will be taken from the outputs S and Se in the form relaxation signals whose frequency and amplitude will depend on the value of the incident magnetic field.

1 is the filament of the detector tube
2 the control electrode, grid 2
3 the screen grid
4 the supresous grid joined internally to the cathode
5 11 anode
6 filament drop resistance
7 the tube input connection capacitor
8 the polarization resistance of the control grid 2
9 the anode load resistance
10 the magnetic field detector tube
11 the cathode
12 the transistor input link capacitor
13 the load resistance of the transistor collector
14 the bias resistance of the base of the transistor
15 an NPN transistor
H the incident magnetic field
S and Sw the complementary outputs of the detection signals
tion or measurement
- xV the supply voltage fixed at 12 Volts in the case
considered - Figure 3 Plate 3 represents the forms and the values of the signals input and output for two modulation frequencies of a magnetic field detector subjected to this one
1 is a rectangular signal applied to the input E of a detector, amplitude of this signal is 2 volts, the frequency is fixed at 50 Hertz, the duration of this signal is delO milli-seconds
1 is the corresponding signal obtained at the output of the sensor, relative to the mass, with different values of the incident magnetic field, action illustrated by the successive levels noted 5, 69 7 8, 9, and 10. Note that the output signal is of an amplitude twice the input signal, in the absence of field.

2 is a rectangular input signal of frequency 200 Hz
amplitude 2 volts and duration 2.5 milliseconds
2 is the corresponding detector output signal with
various amplitudes from the action of the magnetic field
incident tick - Figure 4 Plate 3 represents, as in Figure 3 Plate 4,
the forms and values of the input and output signals
a magnetic field detector, according to the invention, subjected
to an incident magnetic field
3 is a 20 kilo frequency rectangular input signal
hertz, amplitude 2 volts and duration 25 microseconds
3 'is the corresponding detector output signal with
various amplitudes from the action of the magnetic field
incident tick
4 is a rectangular input signal of frequency 100 kilo
hertz, amplitude 2 volts and duration 5 microseconds
4t is the corresponding detector output signal with
various amplitudes from the action of the magnetic field
incident tick - Figure 1 Plate 4, still given by way of nonlimiting example, represents a magnetic field detector produced with a pentode electronic tube EF184 of the 'Noval' series. This tube has a notable sensitivity to magnetic fields. This particular sensitivity to certain electronic tubes basically comes from the significant distance that electrons must travel between cathode and anode. In addition, these tubes have, under the operating conditions according to the invention , a respectable amplification gain in voltage, generally greater than 25 Db, despite the low supply voltage of only a few volts. The use of tubes such as EF80, ECF80 and the like of the 'Noval' series or other series, in the production of magnetic field detectors, according to the present invention, obviously falls within the scope of this patent, would not be - as under new applications of known elements, and moreover, in unusual and unforeseen operating conditions.

 This figure 1 Plate 4 represents the electrical assembly of an EF184 tube used as a magnetic field detector. The robber of the anode charge resistor 6 is set at 12 kilhoms, that of the bias resistor 7 is set at 50 kilhoms.

 These resistors are directly connected to the positive supply line + xV brought to + 6.3 Volt in direct voltage.

 The tube heating filament is directly supplied by this voltage.

 In the absence of a magnetic field, the detector tube has a voltage amplification of more than 25 Db (Decibels) between input E and output S for the signals applied at E. A modulation signal, for example, of 0 , 2 Volt input will be amplified and found at output under amplitude 4 Volts. The action of the magnetic field on this detector will vary the output signal, whether in continuous form (absence of modulation), or in alternative form (presence of modulation or breakout signals), by 4 Volts around O Volt. In this assembly, the screen and the suppressor grid are brought to positive potential, the control grid is also positively polarized.

 If a magnetic polarization is applied Jet adjusted, on this assembly, in such a way that one obtains an output signal at mid-level, that is 2 Volts in the case considered, this will allow the detector to detect and measure , remotely, in an extremely faithful manner, of alternating or direct currents, flowing in conductors, the presence of transients or of direct component superimposed on alternating currents and the polarity or the direction of propagation of direct currents. This with a very wide frequency band of use and an almost insensitivity to thermal phenomena.

 The detection of direct or alternating electric currents or of any shape by the sensors produced according to the invention would obviously fall within the scope of the patent, since this detection or possible measurement is carried out by measuring the magnetic field created around these currents.

In Figure 1 Plate 4,
1 is the filament of pentode 11
2 the control grid
3 the screen grid
4 the grid
5 the anode
6 the input link capacitor E of any signals
modulation or splitting
7 the polarization resistance of the control grid
which is positively biased
8 possible screen load resistance
91a anode load resistance
10 cathode
11 the tube casing and shielding
H the incident magnetic field
+ xV the supply voltage fixed at 6.3 Volts of voltage
keep on going
S1 and S2 signal outputs
E input possibly used for mo signals
dulation or cutting
The curve represented in FIG. 5 Plate 4 gives the value of sensitivity in distance of such a detector subjected to an alternating current of constant amplitude flowing in a conductor.

It gives the AC volts collected at the detector output as a function of the distance existing between the current to be measured and the detector.

- Figure 2 Plate 4 represents an electronic assembly made with a single magnetic field detector tube which, thanks to an electronic self-relaxation provides in outputs S1 and recurrent signals whose frequency and amplitude are function of the field value magnetic incident. The total absence of semiconductors allows the detector to operate in wide temperature ranges.

This assembly is a very particular variant, with low supply voltage and with magnetic parameter, of the wTransitron electronic assembly with Miller integrator ". The not insignificant gain in voltage, under low supply voltage of the EF184 tube already mentioned, or of equivalent tubes, allows a very good operation of the magnetic field detector in this electronic variant. If, for example, we take <the following values t
- 60 kilhoms for anode load resistance 8
- 220 kilhoms for polarization resistance 7
- 30 kilhoms for screen load resistance 9
- 220 kilhoms for the polarization resistance 12
- 0.47 microfarads for coupling capacitors 6 and 10 we will obtain at output 2, S2 signals of almost rectangular shape, of amplitude of several volts and whose recovery frequency will go from 13 to 200 Hertz approximately, depending of the applied magnetic field.

 If, on the other hand, the value of the capacitor (6) is reduced to 2700 pF for example the recurrence frequency will be approximately 1.7 KHZ and will pass to approximately 7 KHZ depending on the value of the magnetic field. In this use at variable frequency> function of the magnetic field, it is advantageous to pick up the signals on the screen load resistance which is less subject to the drop in amplitude by the action of the magnetic field than the anode because the electronic flux is more strongly diverted from 11 anode than from the screen, at the level of which the curvature of flux is less accentcent than at the level of 11 anode.

1 is the filament
2 the control grid
3 the screen grid
4 the supressor grid
5 anode
6 the anode-grid coupling capacitor
7 the polarization resistance of the control grid
positively polarized
8 screen load resistance
10 the screen-grid suppressor coupling capacitor
11 the cathode
12 the polarization resistance of the suppressor grid
13 casing and tube shielding
H the incident magnetic field
S1 and 52 are the outputs of the relaxation signals
+ xV the supply voltage fixed at + 6.3 V
FIG. 3 plate 4 represents a magnetic field detector tube according to the invention with particular properties.

 The detector tube consists of a triode-pentode tube of the ECF 80 type which is mounted as an astable multivibrator with double coupling, an inter-grid and anode coupling by capacitances and a cathode coupling obtained by the 2 cathodes joined to the same resistance of pairing tel2).

 In the absence of a magnetic field, a stable continuous level is obtained at output 1 or 2 (S1) or (S2).

 The presence of even a weak magnetic field will trigger off. of a certain threshold (a certain distance for a small magnet), a brutal input in relaxation of the whole and deliver as output rectangular signals of high amplitude whose frequency will be 10 Hertz, for example, if the capacitors 14 and 15 are fixed at the value of approximately 0.5 UF. There is thus a particularly advantageous magnetic field presence detector which provides a comfortable signal as soon as a certain level of the magnetic field value is reached, a detector in which the temperature practically does not intervene because no semi- conductor is used.

 It is possible to obtain a different operation from this arrangement, by reducing the biasing resistor 13 of the control grid (6) of the triode to the + xV supply. In this case, the detector 7 which loses the benefit of unlocking at the threshold of the pulses) delivers rectangular signals whose frequency as a function of the magnetic field easily reaches ratios greater than 100. These signals will preferably be taken at output 3 (S3), because on the other outputs, the amplitude attenuation is much more accentuated as a function of the value of the magnetic field.

Example if we obtain for the following values,
resistance 11 of pentode grid = 220 kilohms
13 of triode grid = 60 "
n 9 of pentode anode = 220 n
8 8 triode anode = 12 2
12 common to cathodes = 0247 microfarad of rectangular pulses with a recurrence frequency varying from 10 Hertz to 1000 Hertz, approximately, depending on the magnetic field, and whose amplitude at the screen grid, output S3, will evolve between 1 and 2 Volts .The relaxation signals can be taken from output 1 and output 2 but these, although of identical initial value> in the absence of magnetic field, are much more subject to a drop in amplitude depending on the value of the magnetic field .

1 and 1 heating filament of the triode and the pentode
of the same magnetic field detector tube
2 pentode control grid
3 pentode screen grid
4 pentetic suppressor grid, assembled internally
at cathode 10
5 pentode anode
6 triode control grid
7 triode anode
8 load resistance of the triode anode
9 load resistance of the pentode anode
10 and 10 'cathodes of the triode and the penthode, combined
outwardly
11 control grid bias resistor
of positively polarized penthode
12 cathodic coupling resistance
13 control grid bias resistor
of the triode
14 condens :: coupling probe between anode / pentode and
grid / triode
15 coupling capacitor between anode / triode and grid /
penthode
16 tube casing and shielding
Figure 4 plate 4 illustrates the operation of a magnetic field detector tube according to the invention produced with a long electron path diode tube.

 The introduction of the filament drop resistor (3) allows the assembly to operate under a supply voltage of 12 volts (+ xV) for an EY96 tube. for example.

 A direct variation in output voltage as a function of the applied magnetic field of a value significantly greater than 1 volt is obtained directly at the output (S) at the anode load resistance (4).

1 is the electron emitting filament
2 the anode
3 the filament drop resistance (approximately 68A)
4 the anode load resistance (around 47 koL)
5 the tube casing and shielding
+ xV is the supply voltage fixed at 12 volts
S is the output of the wanted signal
H is the incident magnetic field
FIG. 5 plate 4 represents the value of alternating voltage obtained at the output of a magnetic clamp detector, polarized, which detects, and measures, an alternating electric current flowing in an electric conductor, at a distance.

 At 20 cm, the signal obtained, of the order of 50 mV, is perfectly usable.

 It informs both of the value of the alternating current, of a possible continuous component superimposed, and of the presence of any transients.

 It is obvious that the drawings appended to this patent and the description which results therefrom are given for information only to better understand the present invention, the scope of which they cannot in any way limit.

 Likewise, any modification made to the various examples described, and all variants of assemblies falling within the claimed methods and devices would also fall within the scope of the present invention.

Claims (32)

- 1 proportional magnetic field detector, characterized in that it consists of an electron emission vacuum tube with several suitably supplied electrodes, of the diode, triode, pentode or multi-electrode type, in which the variation of the the index of curvature of the electronic trajectories of its electron beam, which is subjected to the influence of the magnetic field before another detected, is transformed into a proportional electric signal which translates the value of said magnetic field. - 2 proportional magnetic field detector, according to claim 1, characterized in that the variation of the index of curvature of the electronic trajectories of the electron beam, which is subjected to the influence of the magnetic field, is greatly increased by -a strong decrease in the speed of said electrons, which is obtained by a strong under-supply of the acceleration electrodes of the tube considered. - 3 proportional magnetic field detector, according to claim-2, characterized in that one or more electrodes for controlling the magnetic field detector tube is, or are, positively biased with respect to the filament or the cathode. - 4 proportional magnetic field detector, according to either of claims 1 to 3, characterized in that the magnetic field detector tube is entirely covered with an electro-static shielding eliminating any parasitic disturbances of electrical origin outside.  - 5 proportional magnetic field detector, according to either of claims 1 to 4, characterized in that the vacuum tube with thermionic emission constituting the magnetic field detector sensor is a miniature or subminiature tube, commercial, or specially constituted, the function of which is the translation into a proportional electric signal, of the value and of the shape of an electric current, at a distance, or the position of a magnet or of an electromagnet, or the position of a magnetic element in a magnetic field, or the value of a magnetic field, or any fluctuation of this or any associated element. - 6 proportional magnetic field detector, according to either of claims 1 to 5, characterized in that it is constituted by a vacuum tube with directed electronic emission. - 7 proportional magnetic field detector, according to either of claims 1 to 6, carcatized in that it is constituted by an electronic vacuum tube, the target of which comes the electron beam subjected to the field incident magnetic is split into several independent targets so that the proportional deflection of the beam allows it to explore the multiple anodes thus formed. - 8 proportional magnetic field detector, according to either of claims 1 to 7, characterized in that magnetic flux concentrators are associated with the detector tube, either outside or inside that here, either on either side of the envelope of the tube. - 9 proportional magnetic field detector according to claim 8, characterized in that the flux concentrators internal to the tube are, at the same time, the, or, electrical concentrators of the electronic flux of the detector tube. - 10 proportional magnetic field detector, according to either of claims 1 to 9, characterized in that a suitably oriented magnetic polarization is effected at the level of the detector, using a magnet, or using an electromagnet, or using both. - 11 proportional magnetic field detector, according to claim 10, characterized in that the magnetic polarization is made aJustable, either mechanically, or electrically, or both. - 12 Proportional magnetic field detector, according to either of claims 10 to 11, characterized in that the magnetic polarization is carried out by an electromagnet directly wound on the magnetic field detector electronic tube. - 13 proportional magnetic field detector, according to claim 12, characterized in that the polarization electromagnet performs two functions, on the one hand, magnetic polarization, on the other hand, the voltage drop necessary for the filament, which is obtained by putting the electromagnet and the filament in series, and the judicious choice of the ohmic resistance of the electromagnet. - 14 proportional magnetic field detector, according to either of claims 10 to 12, characterized in that the magnetic polarization is controlled by any parameter. - 15 proportional magnetic field detector, according to either of claims 1 to 14, characterized in that the detector tube is made as flat as possible, in order to obtain a stronger action of the magnetic field. - 16 proportional magnetic field detector according to either of claims 1 to 15, characterized in that the path of the anode cathode electronic flux is made as long as possible, in order to obtain greater variations in the index of curvature of the electron beam subjected to the magnetic field, and thereby obtain a greater sensitivity of the detector. - 17 Proportional magnetic field detector, according to either of claims 1 to 16, characterized in that the detector tube is a multiple tube in which two or more tubes are united under the same bulb. - 18 proportional magnetic field detector, according to either of claims 1 to 17, characterized in that certain electrodes of the detector tube are coated with electroluminescent substance, so as to make the electron beam and its deflection visible depending on the value of the applied magnetic field. - 19 Proportional magnetic field detector according to claim 18, characterized in that the display electrodes of the electron beam consist of grids with a pitch and orientation determined so that the lines of force of the incident magnetic field can be observed. - 20 proportional magnetic field detector, according to either of claims 1 to 19, characterized in that the various supply voltages of the electrodes of the detector tube, are with direct current. - 21 Proportional magnetic field detector according to claim 209 characterized in that the direct current supply to certain electrodes of the detector tube is interrupted sequentially over time. - 22 Proportional magnetic field detector, according to any one of claims 1 to 19, characterized in that one or the other, or more, or all the electrodes of the detector tube are supplied with sinusordinal alternating current or any shape. - 23 peoportional magnetic field detector according to claim 22, characterized in that the alternating current supply of certain electrodes is at a well-determined frequency. - 24 Proportional magnetic field detector according to any of claims 1 to 20, characterized in that auxiliary signals for modulating or cutting the electron beam are applied to one or more electrodes. - 25 proportional magnetic field detector, according to claim 24, characterized in that the modulation or cutting signals of the electron beam are obtained by the association with the detector tube of another electronic tube, detector or non-detector magnetic field, transistors, unijunction tran sistors, tunnel diodes, integrated circuits, or any other amplifier element, using or not in this association, the own amplification coefficient of the sensor tube itself. - 26 Proportional magnetic field detector, according to claim 25, characterized in that the association with auxiliary electronic elements constitutes an astable multivibrator, or a monostablo multivibrator, or a bistabl multivibrator or any other type of assembly providing signals relaxation assemblies in which the complementary half-element is constituted by the magnetic field sensor tube and the modification of characteristics of the assembly thus formed is a function of the incident magnetic field. - 27 proportional magnetic field detector, according to either of claims 1 to 26, characterized in that the incident magnetic field acting on the electronic flux comes from an alternating current flowing at a certain distance from the detector including that -This gives measure. - 28 proportional magnetic field detector, according to either of claims 1 to 26, characterized in that the magnetic field acting on the electronic flux comes from a direct current flowing at a certain distance from the detector which gives it measured. - 29 proportional magnetic field detector, according to claim 27, characterized in that the magnetic field acting on the flow of electrons from the detector tube, comes from an alternating current with continuous component, and of which the detector simultaneously informs, by visualizing the value and the shape of the corresponding electric current, the value of the amplitude of the alternating current and the value of the amplitude of the continuous component. - 30 Proportional magnetic field detector, according to either of claims 1 to 29, characterized in that the action of the incident magnetic field is only considered as an additional parameter of the operation of the detector electron tubes in their new characteristics thus obtained naked. - 31 proportional magnetic field detector, according to either of claims 1 to 30, characterized in that the magnetic detection is carried out using specially designed electronic tubes, according to the criteria of the present invention, described in the foregoing claims. - 32 Magnetic field detectors, according to either of claims 1 to 31, characterized in that the proportional detection obtained is used, using appropriate circuits for all or nothing detection, or at threshold.