US3069621A

US3069621A - Apparatus for controlling uniformity of a flow of textile and the like fibres

Info

Publication number: US3069621A
Application number: US851417A
Authority: US
Inventors: Butticaz Andre; Dembowski Heinz
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-12-20
Filing date: 1959-11-06
Publication date: 1962-12-18
Anticipated expiration: 1979-12-18

Description

Dec. 18, 1962 A. BUTTICAZ ET AL 3,0

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW 0F TEXTILE AND THE LIKE FIBRES 8 Sheets-Sheet 1 Filed Nov. 6, 1959 ANME 5077/6/12 A/E/NZ fiiMsolw/v/ Bu 'ym i Dec. 18, 1962 A. BUTTICAZ ET AL 3,0

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW OF TEXTILE AND THE LIKE FIBRES Filed Nov. 6, 1959 8 Sheets-Sheet 2 A ry Dec. 18, 1962 A. BUTTICAZ ETAL 3,069,621

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW OF TEXTILE AND THE LIKE FIBRES 8 Sheets-Sheet 3 Filed Nov. 6, 1959 m w w N ANOF Burr/642' HE/A/Z fiE/HaOWSIU.

1 9M Arry 1952 A. BUTTICAZ ETAL 3,069,621

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW 0F TEXTILE AND THE LIKE FIBRES Filed Nov. 6, 1959 a Sheets-Sheet 4 14/8 0165 61/77/642 HE/A/Z DA-MEOWSK/ 1952 A. BUTTICAZ ETAL 3,069,621

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW 0F TEXTILE AND THE LIKE FIBRES Flled Nov. 6, 1959 8 Sheets-Sheet 5 1952 A. BUTTICAZ ETAL 3,069,621

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW 0F TEXTILE AND THE LIKE FIBRES Filed Nov. 6, 1959 8 Sheets-Sheet 6 Dec. 18, 1962 A. BUTTICAZ ETAL 3,069,621 APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW 0F TEXTILE AND THE LIKE FIBRES Filed Nov. 6, 1959 8 Sheets-Sheet 7 FIG/l1 Dec. 18, 1962 A. BUTTICAZ ETAL 3,069,621

APPARATUS FOR CONTROLLING UNIFORMITY OF A FLOW OF TEXTILE AND THE LIKE FIBRES Filed Nov. 6, 1959 8 Sheets-Sheet 8 VA VM 0 0 p 2 Iu-Lnjn +100,

/A VA/7v,$

AWAKE 6077/6/12 7754 2 fif/vafl AyJM JW United States Patent 3,06%,621 APPARATUS FGR CONTRBLLING UNIFORMITY OF A FLUW 8F TEXTELE AND THE LIKE FBREl Andre Butticaz, 45 Rue de La Belle, Saint-Die, France, and Heinz Dernhowslri, fiaint Die, France. (4? Rue Fenelon, Mulhouse-Dornach, Hauhllhin, France} Filed Nov. 6, 1959, Ser. No. 851,417 Claims priority, application France Dec. 20, 1958 32 Claims. (Cl. 3224-61) Our invention has for its object improvements in apparatus for controlling the uniformity of a continuous flow of textile or the like fibres and, in particular, of ribbons, slivers or yarns, of the type wherein the stream or flow of material progresses at a constant adjustable speed through a measuring condenser, so as to produce an electric signal corresponding to a lack of balance in the comparison of the capacity of said condenser with that of a reference condenser.

Our invention covers more particularly but not exclusively such apparatus of the type including a measuring head, wherein the measuring and reference condensers are combined so as to form a unitary differential condenser including two outer armatures or electrodes arranged symrnetrically to either side of a central armature or electrode. Such a measuring head may be incorporated in a measuring circuit including a symmetrical oscillator adapted to feed current into an impedance connected betwen the central armature or electrode and the grounding mass of the arrangement, said current having a voltage corresponding to the lack of balance between the elementary condensers and adapted to be amplified and compared after rectification with a DC. reference voltage, with a view to applying the final resultant voltage defining the extent of irregularity to a device for the interpretation of said irregularity. This interpreting device may include an indicator instrument, integrating means and means for searching periodical components of irregularity.

Apparatus for controlling irregularity or regularity meters are already known which operate in accordance with such principles or with similar principles; said apparatus have appeared of considerable interest and are more and more in favor, chiefly in textile concerns. Their weight and their bulk are however such that it is a difficult matter to transport them and their use is confined to laboratory tests.

Now, there is a general tendency, chiefly in spinning concerns, which consists in inserting the control means far as possiole directly on the actual production machine. Such a manner or" proceeding shows the obvious advantages of saving time and cutting out a considerable amount of waste, since it is possible in numerous cases to do away with the necessity of taking samples and to control directly the adjustment of the machine while furthering the search of the actual causes of irregularity and providing in practice particularly efficient means for increasing productivity.

(Bur invention has for its object the execution of a portable regularity meter providing such advantages. It covers in particular various features which lead not only to a considerable reduction in the weight of the various elements forming part of the regularity meter, but which also improve the conditions of operation and of use or" such elements.

A further object of the invention is the incorporation with a portable regularity meter of its supply of energy, whereby it is made independent of the mains and no current feeding lead is any longer required, while all spark-generating switches are also cut out, the presence of which is not only troublesome, but also danger- 3,069,621 Patented Dec. 18, 1962 ous in a workshop including machines rotating at a high speed in an atmosphere laden with combustible and even explosive material.

A still further object of our invention consists in the execution of a portable regularity meter incorporating in a compact and simplified manner the means required for the interpretation of investigations speedily executed in the workshop, said meter being also intended for association in the laboratory with other interpreting means, which allow obtaining more detailed results with samples of material removed for this purpose from recent or prior production of the same or another concern.

A more particular object of our invention consists in an arrangement for searching periodical components of irregularity, whereby it is possible, through very simple means and within a very short time, to scan a large range of possible frequencies of irregularity at the actual place of production.

Yet a further object of our invention covers the portable section of the apparatus and consists in the execution of an integrator of irregularity which is lighter and simpler than those proposed hitherto.

Our invention covers more particularly control means, whether stationary or for laboratory purposes, which include an automatic integrator cutting out the necessity of any reading and calculation which may lead to errors, through the indication or even the reading of the mean value of the irregularity as integrated over a predetermined period.

A regularity meter according to our invention comprises an interchangeable measuring head connected through a yielding connecting cord with the actual body of the apparatus, wherein the measuring head carries a differential condenser provided with two lateral armatures or electrodes arranged symmetrically to either side of a central armature or electrode inside a frame including means for guiding the yarn or the like fibres through the measuring slot between the central armature or electrode and one lateral armature or electrode of the condenser, an output connector provided with a medial terminal connected with the central armature or electrode and with a pair of symmetrical terminals connected with the corresponding lateral condenser armatures or electrodes, and means for restoring equilibrium between the capacities of the dual differential condenser thus connected, while the apparatus body contains an oscillator with two output terminals arranged symmetrically to either side of a grounded point, an input connector provided with a medial terminal and with a pair of symmetrical terminals for connection with the corresponding oscillator terminals and an amplifier controlled by the signals fed to the medial terminal on the input connector and the yielding cord encloses a double wire cable interconnecting the corresponding symmetrical terminals on the two connectors and a coaxial cable interconnecting the medial terminals on said two connectors.

Our invention covers also simple and convenient means for searching the periodical components of the irregularity detected, an advantageous embodiment of which means may also serve for selective amplifiers and sinusoidal 0scillators operating at a very low frequency.

The accompanying drawings illustrate, by way of examples, various embodiments of our invention, so that the features and advantages of our invention will appear more clearly. In said drawings:

FIG. 1 is a diagrammatic view of a portable apparatus according to our invention.

FIG. 2 is an elevational view of the measuring head of said apparatus.

FIG. 3 is a sectional view on a larger scale of the diiferential condenser along line III-III of FIG. 2.

FIG. 4 is a sectional view through the same line a IiL-III showing the structure of the connector fed by the measuring head.

FIG. is a detail view of the female section of the connector as shown cross-sectionally through line V-V of FIG. 4.

FIG. 6 is a view from the rear of the measuring head after removal of the cover.

FIG. 7 is a view of the inner surface of the cover of the casing of the measuring head.

H6. 8 is a view of the outer surface of the cover of the casing of the measuring head.

FIG. 9 is a simplified wiring diagram of the apparatus.

FIG. illustrates diagrammatically an integrating de vice to be incorporated with the apparatus.

P16. 11 is a wiring diagram of the independent feeding means.

FIG. 12 is a wiring diagram of a preferred embodiment of the means for finding the periodical components of the detected irregularities.

Turning first to the measuring head as illustrated in FIG. 1, said measuring head 1 is removably and interchangeably secured to the end of a cord 2, the other end of which is connected with the casing 3 containing all the other elements of the apparatus including the supply of current. Said casing is of a portable type and may be carried by means of braces for instance.

The measuring head 1 is equipped with a differential measuring condenser formed by three identical

parallelopipedic blocks

4, 5 and 6 (FIGS. 1, 2 and 3) defining between them two slots of

equal breadths

7 and 8. The capacity formed between the

blocks

4 and 5 serves as a reference capacity while the capacity formed between the

blocks

5 and 6 is adapted to be engaged by the yarn 9 to be examined.

As already apparent from examination of FIG. 3, each of the

blocks

4, 5 and 6 is secured to a carrier plate 10 through the agency of a single screw 11, of a covering washer 12 and of two

plates

13 and 14 of a low-loss insulating material extending respectively in contact with the upper and with the lower surface of each block. The

blocks

4, 5 and 6 are connected with the deformable leads 15, 16 and 17 respectively each through the agency of a rigid rod 18 welded at one end 19 to the associated deformable lead and at the other end inside an opening 20 formed eccentrically in the corresponding block, each rod 13 passing through a passage provided for this purpose inside the plate 10 and being protected inside said passage by an insulating sleeve 21 of plastic material. We provide thus a proper mechanical and electrical mounting of the

blocks

4, 5 and 6 forming the armatures or electrodes of the differential condenser.

The deformable leads i5, 16 and 17 extend, (see also FIG. 6), starting from their welded ends connected with the rods 18, into a sheet of three wires parallel with the supporting plate 10, so as to end at the

pins

22, 23 and 2 respectively forming the male section 25 of the connector on the measuring head, said male section being secured to said plate 19 by the usual screws 27 (FIG. 2). The insulating disc 28 (FIG. 4) capping said section of the connector carrying the pins 22 to 24 is slotted along a cord lying between the pin 23 and the

pins

22 and 24, so as to form two parts between which is held fast a metal blade 29 acting as an electrical screen, as disclosed hereinafter. Two notches 30 are cut in the upper edge of the connector 25 in alignment with the plate 2% and to either side of the latter.

The cord 2 connecting the measuring head with the body 3 of the apparatus enters the conventional connecting casing 31 for the movable female section of the connector; said casing includes two parts which are screwed together and which hold fast between them, as shown in PEG. 4, a base or cap 32 inside which is fitted an insulating plug 33.- constituted by

sockets

34, 35 and 36 adapted to cooperate with the

pins

22, 23 and 24 respectively. The plug 33 is slotted so as to form two parts between which is fitted a metal blade 37 forming a screen between the socket 35, on the one hand, and the

sockets

34 and 36, on the other hand, said blade extending at 38 inside the connecting casing 31.

From inspection of PEG. 5, it is apparent that the blade 37 includes two projections 39 and it), the upper ends 41 and of which engage respectively cuts formed for this purpose inside the cap 32, so as to be welded to the latter. The lower ends of the projections 39 and are adapted, on the other hand, to engage the notches in the stationary male section 25 of the connector upon engagement of the plug 33 inside the latter. A sleeve 43 provided with an inner thread caps in the conventional manner a shoulder 44 on the cap 32;, said sleeve being screwed over the male section 2% of the connector and ensuring the clamping and locking together of the male and female sections of the latter. During this clamping, the engagement of the

projections

39 and 40 inside the notches 3%) guides the sockets 3d and 36 over the

pins

22 and 2 which cuts out any torsional straining and the deformation which may result therefrom.

The cord 2 includes a two-wire cable 45 protected by a screen and a yielding coaxial cable 46, the leads 47 of the two-wire cable 45 being welded to the

sockets

36 and 34 respectively, while the lead 48 in the cable 46 is welded to the socket 35. The screens of the two cables are welded to the corresponding surfaces of the blade 37-38. It is apparent that a continuous electrical screen is thus arranged between the connecting wire of the central block 5 of the differential condenser, on the one hand, and the connecting wires 47 of the

outer blocks

4 and 6, on the other hand, starting from the

pins

22 and 24 on the connector and including same, up to the input of the connecting cables in the body 3 of the apparatus.

It should be remarked furthermore, reference being made to FlGS. l and 2, that the male section 25 of the connector is carried by the plate it) on the front surface of the latter, adjacent the differential condenser 46, while a casing 5d of a generally rectan ular shape surrounds said condenser and is provided with two guiding notches 51 in registry with the measuring slot 8.

The carrier plate it; forms, on the other hand, the front cover for a flat casing 52 closed at the rear by a cover 53.

The details of this casing inside which the connections are made and the measuring condenser is balanced appear clearly in H68. 6 to 8.

Said casing houses in fact the sheet of connecting

wires

15, 16 and 17 already referred to. The wire defining the axis of this sheet starts from its output terminal 183 lying in the medial plane of the measuring head and, consequently, of the casing 52. The output terminals 18A and 18C of the

wires

15 and 17 are located to either side of this medial plane at equal distances from the latter. Now, whereas the wire 17 extends between the output 13 and the pin 24, the wire 15 extends beyond the point of its welded connection with the output 18A, the total length of said wire being substantially equal to that of the wire 17, so that it shows at the right-hand side of FIG. 5, beyond its connection at 13A, a freely deformable section 57. The cover is provided with an opening 54 which is normally closed by a threaded plug 55 which may be operated through its head 56 (FIGS. 7 and 8). Upon operation of the plug it is possible to deform and adjust the location of the extension 5'7 of the connecting wire said deformation provides thus a rough adjustment means for the balance between the capacities of the dirlerential condenser. The cover 53 carries furthermore an arrangement for the accurate adjustment of said balance. To this end, there is provided a member rotatably carried by the cover 53 round the axis extending in the embodiment illustrated in substantial registry with the pin 23 connected with the central wire 16, said rotary member including two discs, to wit: at its inner end in registry with the pin ends of the wires l5, l6 and 17, a disc carrying in its turn an eccentric projecting blade or bar 58 (FIG. 7) and, at its outer end, a knurled disc 59 (FIG. 8) serving as a control knob, lying within the out of the cover and which may be readily actuated by r on of the presence of two recesses in the cover 55, It is readily apparent that it is possible to perfect the balance between the two capacities of the differential condenser through rotation of the eccentric blade 53, to either side of a medial position for which it is perpendicular to the sheet wires while any shifting away from said position has for its result a movement of the blade 58 towards one of the

outer wires

15 and 17 and away from the other. Er:- perienee shows that this balance or return to zero may be executed once and for all for each of the measuring heads which it may be desired to secure to the end or" the cable 2.

Turning now to the apparatus body, the wiring diagram illustrated in FIG. 9 shows the arrangement of the electric circuits of the apparatus except for the feeding means which are constituted in the case of the present embodiment considered by a storage battery of the silver-andzinc type, with the interposition of a transistor converter. The portable casing of the apparatus which is not shown in full detail is designed so as to carry said feeding means adapted to produce through any means well-known per se the various voltages required, as described hereinafter.

The wiring diagram includes an oscillator 61, a tuned amplifier 71, an indicator 81, an automatic gain-controlling circuit 91, a periodicity-searching circuit 97 and an integrating modulator 98.

There is shown firstly in the upper left-hand side of the diagram the dilferential condenser described hereinabove and of which the armatures or electrodes 4 and d are connected through the two-wire cable 47 with the output end of the hi h frequency oscillator of any suitable type well-known per se and including for instance a tube 62 loaded by an oscillating circuit of which the winding 63 is coupled with the coil dd connected with the grid, on the one hand, and with the output winding 65, on the other hand. Said winding 65 is of the symmetrical type including two halves 66 and 6'7 formed by ,two Wires Wound together over the same core. The outer terminals of the half windings 6-6 and 67 are connected with the wires 4'7, while their inner terminals are connected with the terminals of a potentiometer 68, the Slider of which, 69, is grounded through the lead 78. Said potentiometer 68 may advantageously be constituted by a mere loop of a resistant wire having a resistance of about 1 ohm. its object is to allow once and for all an accurate equilibrium of the phases of the voltages applied to the cable 4 7, which voltages should he in accurate phase opposition.

The lead 43 connects the central armature or electrode 5 of the differential condenser with the input of the amplifier 71, which input includes a tuned circuit 72-73 and a condenser 74- connected with the grid of the tube '75 equipping the first amplifying stage, said grid being connected furthermore through a large resistance 6 with an automatic gain-controlling or reaction circuit 91, to be described hereinafter. The tube '75 and the following tubes of the amplifier which are not described in full detail are advantageously or". the directly heated small consumption type.

We will now describe with more detail the indicator system. The amplified high frequency signal voltage is tapped at the output of the last stage 77 of the amplifier off the output winding 78 and it is rectified by two diodes of the silicon type inserted in series, so as to cut out the voltage in the reverse direction, which may be cornparatively high. The rectified current thus obtained is applied to the input of the so-called indicator system $1,

" the output signal equal to 40 volts.

so as to load a condenser 3d, of which the terminal A is positive and the terminal B negative. The voltages of the terminals of said condenser 3d are then applied to the condenser fill, through the agency of a resistance 82 and of a varistance 83 inserted in parallel. Experience shows that this arrangement allows obtaining across the terminals A, C or" the condenser 8d, a DC. voltage which varies linearly within a large range of amplitudes as a function of the high frequency signals applied to the input of the amplifier. Said range extends for instance up to a value of 50 volts for the rectified voltage. Across the terminals A, C of the condenser 8% is inserted a chain of resistances including a microammeter 56, an unvarying resistance 83 and an adjustable resistance 37, the reference letter D designating the point common to these two latter elements. The value of the adjustable resistance 87 is of a magnitude lower than that of the resistance 88.

A potentiometric chain starting from the anodic voltage supply 84 (say at 100 volts) and including an adjustable resistance 85 and a stationary resistance 99 allows bringing the terminal A common to the condensers fill and 86 to a positive potential which is adjustable through adjustment of the resistance 85. A second potentiometric chain including an adjustable resistance 89 is adapted to bring the point D to another positive potential which is adjustable through adjustment of the said resistance 89.

The potential at the point A is adjusted to a reference value of say 20 volts while the point D is transiently grounded and the resistance 88 is adjusted in a manner such that the instrument 86, a microamrneter in the case considered, has its hand registering then with the middle point of its scale which is the reference 0%. The potential at the point D is then adjusted by opening the output circuit feeding the condenser 15%, so as to cut out the deflection given to the instrument 86, the zero deflection position thus obtained being referenced as Under such conditions, the deflection 0 is again obtained for a rectified voltage of 20 volts or thereabouts across the terminals A, C of the condenser 8d. The complete deflection marked +100% is obtained for a rectified voltage of substantially 40 volts across the terminals A, C of the condenser 80'.

It is apparent from the preceding disclosure that the point D is at a potential which is substantially equal to 20 volts in the absence of any signal While it is zero for an output signal of 2'.) volts, i.e. at a voltage equal to the reference voltage and of 20 volts for a value of It is therefore apparent that the voltage applied across the input of the modulating and integrating circuit 98 will correspond to the modifications in potential of said point D to either side of the reference potential which is 20 volts in the case considered.

On the other hand, the potential at the point C has corresponding modifications while remaining always underneath the potential at D by an amount equal to the drop in voltage produced across the terminals of the resistance 87 by the discharge current from the condenser 89. The variable voltage thus produced at the point C is applied, on the one hand, to the circuit 91 controlling the gain and, on the other hand, to the circuit 97 provid ing for a search of periodical components.

Turning to the automatic gain control system, it includes a circuit 91 constituted by a low-pass filter including in series a cell with a series of resistances 92. and a condenser in parallel 95, said cell being damped by a resistance 94, and a second cell with a resistance in series 93 and a condenser in parallel 96. The resistance 76 fed by the grid of the first amplifier stage is connected with the output 8 of said circuit.

A three-way switch which is not illustrated allows executing three different connections for this gain-controlling circuit. For one of said connections, the control aceaear circuit is inoperative and the point S is subjected to an unvarying negative voltage which corresponds to a m dium amplification. Said conditions are those which serve for the return to zero of the measuring head and, possibly, for the checking of the linearity of amplification.

For a second position of the switch ensuring a further connection, the gain-controlling circuit 91 is operative, the

condensers

95 and 96 being however disconnected. The reaction is then immediate and not subjected to any delay. The action of the modifications in cross-section of a yarn pa sing through the measuring condenser is cut out and the output voltage of the amplifier is adjusted to a constant value. This is the position which allows adjusting the position corresponding to the medial. point of the scale by acting on the adjustable resistance 8 For the third position of the switch, the complete gaincontrolling circuit is connected in the manner illustrated and the gain of the amplifier is automatically adjusted so that the average value of the output signal which forms the integral over a period of time defined by the characteristic properties of the control circuit 91 may be held at the reference level of say 20 volts, while the instantaneous variations of the signal with reference to said average value appear cross the outputs D and C of the indicating system.

Turning now to the circuit 97 providing for the search of periodical components, which is fed starting from the point C through the agency of a resistance 99 of a high value, said circuit includes a selective phase-shifting network including resistances and a capacity so as to form a conventional double T cell including firstly two condensers 1% and Hill in series and a resistance H32 in parallel, on the one hand, and, secondly, two resistances in series 103 and EM associated with a condenser in parallel 105, on the other hand. The three resistances N2, 103 and 104 are constituted by potentiometers aligned along a common axis and which are adjustable simultaneously through rotation around said common axis. It is thus possible to adjust within comparatively broad limits the resonating frequency of the network.

Said circuit 97 is connected, on the one hand, through the connecting condenser Me with the control grid of an amplifyin tube 1&7, which grid is biased by a supply of negative voltage 108 in series with a high resistance 109 and, on the other hand, with the slider of a potenticmeter 11!) inserted in the anode circuit of the tube fid'i. A cathodic indicator of the magic eye type 111 is connected in parallel with the tube 167.

In order to properly understand the part played by the circuit adapted to search for periodicity, it should be remembered that the characteristics of yarns and, in particular their cross-sections are subjected to modifications of many kinds which are generally aperiodic. However, it may occur that the rotary parts of machines such as the driving or drawing rollers or the like do not run smoothly as a consequence of wear for instance and, in this case the resultant modifications are periodical. Now, our improved arrangement allows scanning a broad range of frequencies through a modification of the resistances M2, lltlfi and 104, so that it is possible to detect any predominant frequency of the phenomenon, while cutting out the others by reason of the large selectivity of the phase-shifting network.

The presence of a marked periodicity is revealed by a periodical luminous signal in the cathodic indicator 111. A direct optic comparison with the different rollers of the textile machine allows finding out readily the defective part.

It is not necessary to gauge accurately the treble potentiometer or resistance system because the accurate speeds of rotation are not generally known. The finding of a synchronism through optic comparison is conclusive without any further data being required.

However, there exist two limits for the utilisation of the arrangement described. in the case of high frequencies, the inertia of the human eye does not allow observing frequencies above 10 cycles. As to very low requencies, it should be remembered that the gain-- controllin circuit $7 cuts out all the waves having a comparatively long period, say above 1 minute. At any rate, this last limitation has only a very reduced importance, since the searching of such periodicities would lead to a duration of investi ation which cannot practically beallowed. in fact, if it is desired to make sure that a true periodicity has been found and that the phenomenon is not an isolated phenomenon appearing fortuitously, it would be necessary to wait about five minutes, which is: not possible in practice.

The circuit for searching periodicity may advantageously be provided with a rotary contact-maker which is not illustrated so as to operate on several ranges of frequencies according to the requirements of various types of spinning machines.

An improved periodicity-searching circuit will be described hereinafter.

We will now describe the modulating and integrating means 98, the input of which is connected between the point D and the ground. The variable voltage at the point D is applied through the agency of the resistance 11?. to the slider of a potentiometer 113, which forms part of a modulating bridge including in a manner known per se a silicon diode M4, 115 in each of its arms, each diode being inserted in series with a resistance 1 6, 117 and being fed by one of the terminals of a transformer secondary 118, the middle point of which, 119, forms an apex of the bridge, while the primary of the transformer 123i) is shown at 121 as fed directly by an A.C. voltage of a frequency defined in the case considered as equal to 1,000 cycles, said frequency of rectangular waves being tapped off the transistor converter in the feeding circuit already referred to and forming part of a feed system advantageously designed for operating at such a frequency.

The output of the modulator feeds through the agency of the connecting condenser 122 an amplificationadjusting potentiometer 123, the other terminal of which is connected with a biased terminal 124 and the slider of which is connected with the grid controlling an amplitying tube 125. The latter is loaded in its anode circuit by an oscillating circuit including an inductance 126, a condenser 127 and a damping resistance 1.23 and tuned to the modulating frequency, say 1,000 cycles in the case considered. The damping resistance 128 and the coupling elements are connected in a manner such as to provide a substantially uniform response of the amplifier throughout a band of frequencies extending over about 200 cycles to either side of said carrier frequency of 1,000 cycles.

The output voltage of ti e tube is applied through the agency of a connecting condenser 129 to the control grid of a cathodic tube 136, the cathode of which is loaded by an inductance 331. The signal collected through a low impedance across the terminals of the latter is rectified by a silicon diode 132 loaded by a resistance 133 shunted by a condenser 434 adapted to cut out the carrier frequency of 1,066 cycles. The output signal thus filtered is applied to the actual integrator constituted by a double cell of the resistance capaci y type l3-5137, r3-ft39. The slowiy varying voltage collected at the output of said integrator is transferred under low impedance conditions at F across the terminals of the loading resistance 14-11 of a tube Me of the cathode follower type, so that said voltage may be compared to an adjustable reference DC. voltage tapped at G off the slider of the potentiometer 143 forming part of a potentiometric chain 14d1 i5. The value of the irre ularity thus obtained is read by connecting across the points F and G the micro-ammeter as already mentioned and inserted in series with a resistance 143.

As disclosed precedingly, the unvarying reference voltage at the point A being selected as equal to 20 volts, that at the point D is capable of varying between and 40 volts, i.e. by volts tor irregularities ranging between :100%. Experience shows furthermore that it is of advantage to provide a range of measures adapted to measure an average irregularity up to 210%. This implies, in the present case, obtaining a total deflection of the indicating instrument 36 inserted across the output F-G of the integrator for a voltage of 2 volts applied at D at the input of the modulating and integrating means 98. It is well known that such a low voltage cannot serve for direct action on a rectifier. To obtain a rectification with a suitable rectilinearity, taking into account the curvature of the characteristic curves of conventional rectifiers, it is necessary to resort to a voltage of at least about 10 volts. The modulating and integrating means described allow obtaining such a result under particularly favorable conditions.

The diode modulator 114-115 being fed through the agency of the transformer 120 by a control voltage with substantially rectangular waves, the modulated signal collected at the output at l22l23 remains practically linear with reference to the input signal for modifications of the latter which may be high enough to reach the peak value of the control voltage. It is suiiicient to define said value as equal to 8 volts for instance so as to cover the entire range of modifications of the input signal for the conditions defined hereinabove.

The voltage appearing at the potentiometer 123 is in the shape of short pulses. The oscillation circuit 326- 127 tuned to the frequency of 1,000 cycles of the control voltage restores a substantially sinusoidal voltage at the output point feeding the tube 138.

The equilibrium of the modulator is obtained once and for all after grounding the point D by adjusting the position of the slider on the potentiometer 113 in a manner such as to obtain a minimum deflection in the indicating instrument as inserted between F and G. Said deflection is then cancelled through action on the slider of the potentiometer M3.

The indicating instrument 556 is provided with a scale extending from zero to 10% and the deflection 10% is then adjusted by applying to the input D of the modulating and integrating circuit a voltage of 2 volts tapped at tee off the potcntiometric chain Jill-355.

A second scale ranging between zero and 30% may advantageously be provided and may become operative upon shifting of a lever-controlled reversing switch which is not illustrated.

A totalizing integrator will noW be described since the simple integrator which has just been described has only a limited memory or storing capacity. In practice, the indications given by the hand vary slowly to either side of an average value. In order to find this average value, it is therefore necessary to execute a suificient number of readings and to calculate their average; said manner of proceeding is satisfactory when the portable apparatus is used in a workshop. However, the calculation of the averare value requires time and the result sufiers by the unavoidable errors in reading. Our invention provides now, with a view to more accurate measurements, an auxiliary totalizing integrator adapted to be associated, in principle in the laboratory, with the portable apparatus incorporating the circuits which have just been described with reference to FIG. 9. FIG. 10 illustrates diagrammatically such a totalizing integrator adapted to be connected across the output terminal F-G of the integrating and modulating circuit d8.

Said totalizing integrator includes as a main part a small DC. motor hi6 adapted to be connected by a contact-maker M7 controlled by a time-switch 148 during a predetermined period of say three minutes across the terminals P-G. The speed of rotation of such a motor M6 is proportional to the voltage applied, provided the load produced chiefly by friction is negligible.

10 There are sold nowadays micromotors which satisfy completely these conditions.

The shaft 149 of the motor 146 drives, in the present case and as illustrated, a semi-circular disc 150 which cuts out periodically the luminous beam 151 projected by a source of light 152 in the direction of a photosensitive diode or cell 153. The impulses produced in the latter feed a relay 154 of a suitable transistor of thyratron type, which in its turn actuates a printing meter 155' of any suitable conventional type provided with a return to Zero knob which is not illustrated.

The number of turns executed by the motor and, consequently, the number of pulses recorded by the meter is an integrated measure of the irregularity-defining voltages applied across F and G during the measuring period controlled by the time-switch 148. Said period, equal to say three minutes, corresponds to the requirements of laboratory measurements for which it is possible to readily resort to speeds of yarn progression of a magnitude of 100 meters per minute.

Tne relay 15 iand the meter 155 are designed in a manner such that, for a voltage of 2 volts for instance applied to the input of the modulator, the meter shows an indication of 10% at the end of the three-minute period.

Turning now to the feeding means, FIG. 11 shows a preferred embodiment of an autonomous feeding circuit carried inside the casing of the portable apparatus.

A storage battery lot) of the silver-and-zinc type producing a normal voltage of 6 volts and protected by a fuse MEA is associated with a push-pull converter with two transistors 161' and 162 in accordance with a wellknown connection of the grounded collector type. The emitters are connected with the outer terminals of the two halves and 164 of a first winding, the middle point of which is connected with the slider 165 of a rheostat tee and, through the agency of the latter, with the positive terminal of the battery rec. The emitters are coupled in parallel with the first winding through a resistance in? in series with a condenser 163. The bases of the arisistors are connected with the outer terminals of the two halves 169 and 17d of a second winding inserted in series with and to either side of a potentiometer hill, the slider of which is connected through a common biasing resistance with the middle point of the first winding. This forms a multi-vibrator wherein the two transistors ids. and 162 when energized are alternatingly locked and released at a predetermined rhythm, as defined chiefly by the value oi the inductance and which is assumed in the present case to be equal to about 1,000 cycles. The slider on the potentiometer 171 is also connected through the agency of a resistance 172A with the movable contact-piece i673 of a switch which is normally open and the stationary contact-piece of which is connected with the negative terminal of the battery Mt). The closing of said switch starts the production of oscillations by applying a low negative biasing voltage to the bases across the terminals of the resistance M2. The two above-mentioned windings and all those described hereinafter are wound over a common magnetic circuit which is not illustrated.

A third high voltage winding 175 serves for applying the anodic voltage +HT for the amplifier and the like associated circuits through the agency of a rectifier including two

diodes

176, 177 mounted as a voltagedoubling device with two condensers in

series

178 and 17% and a condenser 18d in parallel with said diodes. A second, normally open switch 132 is inserted across the terminals of the high voltage winding and is coupled with the above-mentioned switch 173 through a lever illustrated diagrammatically at 183.

Said system of switches may be advantageously con stituted by a conventional compound switch of the telephone key type having a central stable position and two non-stable positions. Upon rocking of the lever 183 towards the right-hand side of 11, it is possible to start the oscillations; this corresponds to the operative position M. When rocked towards the left-hand side of FIG. 11, the lever 183 cuts out suddenly the oscillations and the feed stops.

This arrangement has for its advantage the cutting out of a switch in the battery circuit which remains constantly energized. When the oscillations stop and the two transistors are locked, the output of the battery is entirely negligible. A further advantage consists in the fact that if a short-circuit arises in any section of the apparatus (windings, cables, diodes, condensers), this results in an immediate stoppage of the converter, so that a protection is obtained which is more reliable than that of a circuitbreaker. This protection is furthermore gratuitous since it requires no further instrumentality.

A fourth winding 13 i is adapted to supply the heating current to the lead CH through the agency of a rectifier 385 operating on both alternations of a filter 136. One or more windings 187 load, through the agency of diodes 1558, condensers 13% across the terminals of which are tapped voltages V for the biasing of the grids; a last winding 1% supplies at VC the alternating voltage required for controlling the integrating and modulating means 98 (PEG. 9).

It is apparent that each of the different voltages required for operation of the apparatus is supplied through the agency of a suitable winding while all the windings are coupled through the agency of a common transformer with those forming part of the actual converter, which latter alone are electrically connected with the battery loll itself. Said connection is performed through the agency of the rhcostat 366 which compensates for all the modifications in voltage of the battery during its discharge with reference for instance to a periodical control of the high voltage, say 100 volts, on the line +HT. The rheostat 166 is designed in a manner such that at the end of the discharge, its slider 165 engages an insulated contact-piece 191 independent of the actual resistance. When the operator wishes to make up for a lowering of the voltage by bringing the slider 165 on said contact piece, the circuit is switched off and the oscillations of the converter are stopped and the battery is thus automatically no lon ger under discharge. The potentiometer 171 allows obtaining symmetry in the mounting by compensating for the comparatively large differences which may appear between the properties of diilerent transistors sold in trade.

We will now describe a modification, illustrated in HS. 12, of the arrangement for detecting periodical components of the modifications in voltage.

In said FlG. 12, the variable voltage, in which any possible periodicities are to be searched for, is applied to the terminal C and is transmitted through the agency of a condenser Zill and of a potentiometer 292 to the control grid of a tube 2%; the signal amplified by said tube is applied to a Wien bridge including a resistance 2% and a rheostat 2 associated with a condenser Ell-5, on the one hand, and a pair of corresponding resistances 2-MAZ5A associated with a condenser 2596A, on the other hand, the corresponding elements having identical values in each arm of the bridge while the potentiometers 26:5 and 295A are controlled in unison. The anode of the tube 2133 is connected through the resistance and a portion of the potentiometer with a terminal VA providing anodic DC. voltage about 160 volts. Consequently, the anodic charge of the tube 2% forms part of the input resistance of the Wien bridge and the signals are thus accurately injected into said input of the bridge; the output signals of the bridge are applied to the first grid of the tetrode 2%7, the anode of which is connected with the terminal VA providing the anode voltage through the primary Winding of a transformer Zll, while its second grid is connected with a terminal Vivi feeding voltage pulses of an amplitude also equal to 200 12 volts for instance. Referring to the feeding device described hereinabove with reference to H8. ll, it will be remarked that the voltage VA forms the general voltage feeding the different amplifying stages of the associated apparatus. while the voltage pulses VM may be tapped for instance 05f the stationary contact-piece of the switch 182 of the feeding means illustrated in PEG. 11.

The primary winding of the transrorrner Zll is provided with an intermediate tapping which allows connecting across the terminals of a portion of said winding a condenser 213 through the agency of a diode 217;, the potentiometer Zlll already referred to being connected across the terminals of the condenser 21 The latter is also connected with the control grid of a tube 23.6 forming a ma ic eye, through the agency of a connecting condenser and of the grid leak resistance An ear-piece 2:29 is lastly fed by a secondary winding of the transformer Zll with the insertion in series therewith of a diode 2 22.

The second grid of the tube 2&7 being fed by DC. pulses, the amplitude of which is equal to the value of auodic voltage, the anodic current is modulated in a corresponding manner. The amplitude of the pulses of the anodic current is proportional to the voltage applied to the control grid through the agency of the Wien bridge, whereby there appears in the primary of the transformer Ell an A.C. voltage which is also proportional to the applied voltage. Said primary voltage is rectified by the

diode

2,12 and there appears thus across the terminals of the potentiometer Zltl a D.C. reaction voltage which is again proportional to the voltage injected into the input of the bridge. The polarity of the diode 212 is selected so as to provide phase concordance, i.e. a positive reaction. It is apparent that, as a matter of fact, the voltage across the input of the W'en bridge becomes more positive when the voltage across the output becomes more positive. The phase conditions required are consequently satisfied for the execution of an amplifier and, possibly, of an oscillator.

The operative conditions provide a great purity for very low frequencies. There is practically no lower limit from this standpoint except for the bulk to be given to the condensers file-206A of the Wien bridge.

The upper operative limit depends on the carrier frequency. In the case considered, said frequency is of a magnitude of 1,000 cycles and the upper limit is located at about 5i) cycles.

The luminous signals produced by the tubes 216 are associated with an acoustic signal produced in the earpiece This is of considerable interest, chiefly for the upper range of frequencies of a magnitude of 10 cycles which cannot be appreciated by the human eye. The diode 2 2 which should be inserted in the circuit of the ear-piece forms a highly non-linear resistance which marks more strongly the modifications in the acoustic energy and compensates to a certain extent the lack of sensitivity of the human ear for modifications in acoustic energy. If the average voltage of the secondary is of the order of the threshold of linear response of the diode, say 0.5 volt for instance for a silicon junction diode, it is found that the signals have a proper rhythm and are fully intelligible. The ear-piece should have a low impedance so as to benefit by such advantages.

The Wien bridge described introduces a weakening by about 3 and the gain in the reaction loop which may be adjusted by shifting the slider of the potentiometer Zlll should also be equal to about 3. If the gain is equal to or above 3, the circuit produces undamped oscillations. If the gain is lower than 3 by a more or less considerable amount, the circuit is correspondingly damped; in other words, the resonance curve is more or less sharp, It said resonance is too sharp, the searching of the periodical components is very tedious and if it is too indefinite, it is difiicult to distinguish the periodical phenomena from the aperiodical phenomena. A correct adjustment corresponds obviously to a compromise. It will thus be remarked that the actual part played by the condenser 210 consists in the adjustment of the selectivity and that played by the input potentiometer 202 consists in the adjustment of sensitivity as quite different from selectivity. Said adjustments .are to be executed in fact once and for all.

The connection of the demodulating or detecting diode 212 with the medial tapping on the transformer 211 allows reducing the internal impedance of the demodulating circuit.

The arrangement described shows interesting advantages over the corresponding arrangement of FIG. 9. The selective circuit forming a Wien bridge is simpler than the arrangement 97, since it includes only two resistances and two condensers. Furthermore, it allows cutting out the condenser 106 and the resistance 109 in the diagram of FIG. 9, which were required for uncoupling the high D.C. voltage of the anode with reference to the grid of the amplifier tube. Said eements are incorporated in the diagram of FIG. 12 without any further expenditure.

Now, whereas it was impossible hitherto to connect such a circuit between the anode and the grid of a single tube, by reason of the phase concordance required, it is apparent that our invention allows cutting out the insertion in series of a further tube to reverse the phase condition. In the case illustrated, said phase reversal is obtained through the contrivance of a modulation followed by a demodulation through a diode with the desired polarity.

Our invention, of course, is not limited to the details of the embodiment described given by Way of a mere exempification and which may form the object of many modifications, as will appear clearly to any one skilled in the art as concerns for instance the amplifying and modulating means which are enclosed inside a common tube 2.07 in the case of FIG. 12.

We should also mention the particular application which may be provided for the arrangement illustrated in FIG. 12 in the field of sinusoidal oscillators operating at a very low frequency and of selective amplifiers also at a very low frequency. As a matter of fact, selective oscillators and amplifiers are known since a long time, which incorporate in a different manner a Wien bridge and operate for low frequencies ranging between 1 and 100,000 cycles, but the use of such amplifiers has not been contemplated hitherto for very low frequencies underneath 1 cycle. This is ascribable, on the one hand,

to the limitation on the low frequency side correspond- Y ing to a further objectionable phase shifting which it was difficult to avoid in the known arrangements and, on the other hand, to the absence of any application in this field at the present time. The checking of the irregular size in a flow of textile or the like fibres forms an example of application of this scanning of a frequency range and further applications are possible in the field of geophysical searches for instance.

To give an idea of the possibilities provided by the arrangement described in the fied of very low frequencies, it is possible to consider, for instance when using resistances of 20 megohms and condensers of 2 microfarads in the Wien bridge, a resonance frequency of 1/250 cycles, i.e. a period of about 4 minutes. It is even possible to contemplate periods of the magnitude of 1 hour by resorting to highly insulated condensers without even requiring the use of special tubes of the electrometer type.

The apparatus described as a whole hereinabove may serve as well for measurement in the workshop and in the laboratory. In the Workshop, the measuring head described which is particularly illustrated in FIG. 1 is of a very convenient use, since its reduced bulk allows positioning it without any difficulty on a yarn between two other yarns or at the output of any machine. Independence with reference to the mains cuts out the necessity of using a cable for connection with the mains which would be not only objectionable, but even dangerous in the presence of machines revolving at a high speed inside an atmosphere laden with inflammable particles. The setting of the measuring head at the end of the cable connecting it with the body of the apparatus allows the operator, who may carry the .apparatus on his back or chest, to permanently check the correct unwinding of the yarn through the measuring head. In a practical embodiment according to the above description, the weight of the portable apparatus has been reduced to 6 kgs. and its consumption of energy to 6 watts altogether.

In the case of laboratory work, the same apparatus may be carried on a support which is not illustrated and which is equipped with a driving motor running at a variable speed, with graphic recording means and, lastly, with a totalizing integrator incorporating a recording and, possibly, a printing meter. In this case, the measurement of irregularities in size is performed automatically while cutting out entirely all errors due to reading and calculation.

With the structure described and by reason chiefly of the relative screening of the wires feeding the outer armatures, on the one hand, and of the wire providing for connection of the central armature or electrode of the differential condenser, on the other hand, throughout the connectors and up to the input into the apparatus, there is no difficulty in changing the measuring heads corresponding to different gauges. The extension of the electrostatic screening inside the actual body of the connector cuts out in particular any phase shifting or possible lack of equilibrium which might result from an even slight modification of the relative positions of the connecting pins and sockets depending on the conditions of interfitting of the male and female sections of the connector.

What we claim is:

1. An apparatus for controlling uniformity of flow of textile and the like fibres, comprising an interchangeable portable measuring head including a differential condenser constituted by a central electrode and two lateral electrodes arranged symmetrically to either side of the central electrode, means guiding the fibres to be examined through the gap between the central electrode and one lateral electrode, an output connector carried by the measuring head and including a first part provided with a medial terminal and two lateral terminals arranged symmetrically of the medial terminal and a second part removably fitted in the first part, means connecting said medial terminal with the central electrode and the lateral terminals with the corresponding lateral electrode; an apparatus body including an oscillator having two output terminals and a grounded point, an input connector including a first part provided with a medial terminal and two lateral terminals arranged symmetrically of the medial terminal, circuit connecting said last-mentioned terminals with the corresponding oscillator terminals, and a second part removably fitted on last mentioned first part, a cord electrically interconnecting the second parts of the two connectors and including a double wire cable interconnecting the corresponding lateral terminals on said two connectors and a coaxial cable interconnecting the medial terminals on said two connectors and amplifying means carried by the body and controlled by the signals appearing on the medial terminal of the input connector in accordance with the disturbances in the equilibrium of the differential condenser upon passage of an irregular flow through the condenser gap, and detecting and interpreting means for the output signals fed by the amplifying means upon appearance of irregularities in the flow of fibres.

2. An apparatus for controlling uniformity of flow of textile and the like fibers, comprising an interchangeable measuring head including a differential condenser constituted by a central electrode and two lateral electrodes arranged symmetrically to either side of the central electrode, means guiding the fibres to be examined through the gap between the central electrode and one lateral electrode, an output connector carried by the measuring head and including a first part provided with a medial terminal and two lateral terminals arranged symmetrically of the medial terminal and a second part removably fitted in the first part, means connecting said medial terminal with the central electrode and the lateral terminal with the corresponding lateral electrode, an apparatus body including an oscillator having two output terminals and a grounded point, an input connector including a first part provided with a medial terminal and two lateral terminals arranged symmetrically of the medial terminal, a circuit connecting said last-mentioned terminals with the corresponding oscillator terminals and a second part removably fitted on last-mentioned first part, a cord electrically interconnecting the second parts of the two connectors and including a double-wire cable interconnecting the corresponding lateral terminals on said two connectors and a coaxial cable interconnecting the medial terminals on said two connectors, an electrostatic screen on the coaxial cable extending into transverse registry with the medial terminal of at least one of the connectors to screen the latter terminal with reference to the corresponding lateral terminals, and amplifying means carried by the body and controlled by the signals appearing on the medial terminal of the input connector in accordance with the disturbances in the equilibrium of the differential condenser upon passage of an irregular flow through the condenser gap.

3. In an apparatus as claimed in claim 1, the combination of a carrier plate carrying the differential condenser electrodes and the output connector on one of its surfaces, a casing closed by the opposite surface of the plate and enclosing the means connecting the condenser electrodes with the output connector terminals, and means for adjusting the equilibrium of the condenser carried inside said casing.

4. In an apparatus as claimed in claim 1, the combination of a carrier plate carrying the output connector on one of its surfaces, an insulated screw extending through each electrode and screwed into last-mentioned surface of the plate to hold said electrode fast on said one surface of the plate, an outer compression washer and an outer insulating plate fitted between each screw head and the corresponding electrode, an inner insulating plate held between each electrode and the carrier plate, a casing closed by the opposite surface of the plate and enclosing the means connecting the condenser electrodes with the i output connector terminals and means carried inside said casing for adjusting the equilibrium of the differential condenser.

5. In an apparatus as claimed in claim 1, the combination of a carrier plate carrying the differential condenser electrodes and the output connector on one of its surface, a casing closed by the opposite surface of the plate, a rigid output lead fitted eccentrically through one end in each electrode and projecting beyond same through the carrier plate, an insulating sleeve surrounding each rigid lead in its passage through the carrier plate, a connecting wire welded to the other end of each rigid lead and forming the connection With the corresponding terminal of the output connector, and means for adjusting the equilibrium of the differential condenser, said last-mentioned means being carried inside said casing.

6. in an apparatus as claimed in claim 1, the combination of a carrier plate carrying the differential condenser electrodes and the output connector on one of its surfaces, a casing closed by the opposite surface of the plate, a ri id output lead fitted eccentrically through one end in each electrode and projecting beyond same through the carrier plate, an insulating seeve surrcunding each rigid lead in its passage through the carrfer plate, a con- .necting wire Welded to the other end of each rigid lead and forming the connection with the corresponding terminal of the output connector, the rigidlead for the central electrode and the medial terminal of the output connector lying in the plane of symmetry of the differential condenser, the rigid lead for each outer electrode lying with the corresponding lateral terminal on a corresponding side of said plane and the connecting wires forming a sheet parallel With the carrier plate, a deformable overhanging extension for the wire connected with the lateral electrode nearest the cutput connector and the end of which registers transversey with the rigid lead of the lateral electrode furthest from the output connector, the deformation of said extension acting on the equiIibrium of the differential condenser.

7. In an apparatus as claimed in c aim 1, the combination of a carrier plate carrying the differential condenser electrodes and the output connector on one of its surfaces, a casing closed by the opposite surface of the plate, a rigid output lead fitted eccentrically through one end in each eectrode and p ojecting beyond same through the crrier plate, an insulating sleeve surrounding each rigid lead in its passage through the carrier plate, a connecting Wire welded to the outer end of each rigid lead and forming the connection with the corresponding terminal of the output connector, the rigid lead for the central clectrcde and the medial terminal of the output connector lying in the plane of symmetry of the condenser, the rigid lead for each outer electrode lying with the corresptnding lateral terminal on a corresponding side of said plane and the connecting wires forming a sheet parallel with the carrier plate, a deformable overhanging extension for the wire connected with the lateral electrode nearest the output connector and the end of which registers transversely with the rigid lead of the lateral electrode furthest from the output connector, a cover provided with a shutter-controlled opening for the casing and registering with said overhanging extension to allow adjustment of the position of the latter to provide rough equilibrium between the capacities separating the central e'ectrod-e from the lateral electrodes.

8. In an apparatus as claimed in claim 1, the combination of a carrier plate carrying the differential condenser electrodes and the output connector on one of its surfaces, a casing closed by the opposite surface of the pate, a'rigid output lead fitted eceentricaly through one end in each electrode and projecting beyond same through the carrier plate, an insulating sleeve surrounding each rigid lead in its passage through the carrier plate, a conne ting w're welded to the other end of each rigid lead and fo'ming the ccnnection with the corresponding terminal of the output connector, the rigid lead for the central electrode and the medial terminal of the output connector lying in the plane of symmetry of the condenser. the rigid lead of each outer electrode lying with the corresponding lateral terminal on a corresponding side of said plane and the connecting wires forming a sheet parallel with the carrier plate, a deformable overhanging extension for the wire connected with the lateral electrode nearest the output connector and the end of which registers transversely with the rigid lead of the lateral electrode furthest from the output connector, the deformation of said extension acting on the equilibrium of the differential condenser, an eccentric rotary eement projecting inwardly of the casing into registry with the wires, a knob cn the outside of the casing controlling the a gular prsiion of said rotary element and thereby producing the fine adiustment required for the equilibrium between the capacities separating the central electrode from the lateral electrodes.

9. in an apparatus as claimed in claim 1, the combination of a screen for the coaxial cable and a metal blade forming an extension of the cable screen and extending through at least one connector to separate electrostatically the medial terminal of the latter from its lateral terminals.

10. In an apparatus as claimed in claim 1, the combi- 17 nation of a screen for the coaxial cable, a metal blade forming an extension of the cable screen and extending through at least one connector to separate eiectrostatically the medial terminal of the latter from its later terminals and abutments carried by said extension and preventing relative rotation of the two parts of the connector.

11. In an apparatus as claimed in claim 1, the combination of two windings coupled with the output of the oscillator, a balancing potentiometer inserted in series between s:id two windings, a slider for the potentiometer and means for grounding said slider.

12. In an apparatus as claimedin claim 1, the provision of a grounded impedance inserted between the medial terminal of the output connector fed by the central electrode of the condenser and forming a resonating circuit tuned to the frequency of the oscillator.

13. In an apparatus as claimed in claim 1, the combination of a detector fed by the amplifying means, a detecting condenser fed by said detector, a chain of resistances in which the detecting condenser is inserted, an indicating instrument controlled by the detecting condenser through said chain of resistances and means for bringing one of the terminals of the detecting condenser to a DC. reference potential and including a supp y of DC. potential, a grounded potentiometric chain connected with said terminal and with said supply and means connecting an intermediate point of said chain of resistances with said supply.

14. In an apparatus as claimed in claim 1, the combination of a detector fed by the amplifying means, a detecting condenser fed by said detector, a chain of resistances in which the detecting condenser is inserted, an indicating instrument controlled by the detecting condenser through said chain of resistances, an intermediate condenser across the terminals of which the detecting condenser and the system including the indicating instrument and the chain of resistances are connected in parallel, a non-linearresistance inserted between the detecting condenser and last-mentioned intermediate condenser, and means for bringing one of the terminals of the detecting condenser to a DC. reference potential and including a supply of DC. potential, a grounded potentiometric chain connected with said terminal and with said supply and means connecting an intermediate point of said chain of resistances with said supply.

15. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a selective circuit fed with signals by the amplifying means and adapted'to' be adjustably tuned, an amplifier staged fed by the selective circuit and a cathodic indicator fed by the amplifier stage.

16. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a phaseshifting selective circuit of the double T shape fed by the amplifying means and including condensers and three aligned adjustable potentiometric resistances, a common rotary spindle coaxial with said aligned potentiometers to control the latter, an amplifier stage fed by the selective circuit and a cathodic indicator fed by the amplifier stage.

17. In an apparatus as claimed in claim 1, the provision of an integrator for the irregularities in the flow of fibres comprising an indicator circuit fed by the amplifying means and adapted to produce signals corresponding to the irregularities of flow, a closed circuit modulator fed by said signals and adapted to modulate same at the rhythm of a control signal at an unvarying frequency, means for amplifying the modulated signal, a detector fed by last-mentioned amplifying means and a circuit for integrating the signals produced by said detector.

18. In an apparatus as claimed in claim 1, the provision of an integrator for the irregularities in the flow of fibres comprising an indicator circuit fed by the amplifying means and adapted to produce signals correspondng to the irregularities of flow, a closed circuit modulator fed by said signals and adapted to modulate same at the rhythm of an AC. control signal of substantially rectangular shape at an unvarying frequency, means for amplifying the modulated signal, a detector fed by last-mentioned amplifying means and a circuit for integrating the signals produced by said detector.

19. In an apparatus as claimed in claim 1, the provision of an integrator for the irregularities in the flow of fibres, comprising an indicator circuit fed by the amplifying means and adapted to produce signals corresponding to the irregularities of flow, a closed circuit modulator fed by said signals and adapted to modulate same at the rhythm of an AC. control signal of substantially rectangular shape at an unvarying frequency, means for amplifying the modulated signal, a detector fed by last-mentioned amplifying means, said last-mentioned means including at least one circuit tuned to the frequency of the control signal, and a circuit for integrating the signals produced by said detector.

20. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the push-pull type including two transistors, windings fed by said battery and energizing the transistors, and rectifying and filtering means controlled by said transistors and feeding the tubes of the oscillator and of the amplifying means of the apparatus.

21. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the push-pull type includ ing two transistors, windings fed by said battery and energizing the transistors, rectifying and filtering means controlled by said transistors and feeding the tubes of the oscillator and of the amplifying means of the apparatus and including means for producing a rectangular A.C.

signal, a modulator modulating the output signals from the amplifying means with said rectangular A.C. signal, and means for detecting and integrating the modulated signals.

22. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the push-pull type including two transistors, windings fed by said battery and energizing the transistors, rectifying and controlling means controlled by said transistors and feeding the tubes of the oscillator and amplifying means of the apparatus, and including means for producing a rectangular A.C. signal having a frequency equal to the operative frequency. of the relaxation converter, of about 1,000 cycles, a modulator modulating the output signals from the amplifying means with said rectangular A.C. signal, and means for detecting and integrating the modulated signal.

23. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the pushpull type including two transistors, windings feeding the latter across the terminals of the storage battery, means for energizing and deenergizing said converter through a starting and damping of the relaxation oscillations therein, and rectifying and filtering means controlled by said transistors and feeding the tubes of the oscillator and amplifying means of the apparatus.

24. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the push-pull type including two transistors, windings feeding the latter across the terminals of the storage battery, a switch adapted to provide in a first position an operative biasing voltage for the transistors, in a second position a short-circuit1ng of the transistor windings and, in a third position, energization of the converter, means urging said switch into said third position, and rectifying and filtering means controlled by said transistors and feeding the tubes of the oscillator and amplifying means of the-apparatus.

25. In an apparatus as claimed in claim 1, the provision of a supply of current comprising a portable storage battery, a relaxation converter of the push-pull type including two transistors, windings feeding the latter across the terminals of the storage battery, a transformer, the primary of Which is formed by the transistor windings and secondary windings on said converter feeding the tubes 'ofthe' oscillator and amplifying means of the apparatus.

26. In an apparatus as claimed in claim 1, the provision of an automatic integrator comprising a DC. motor, means feeding said motor with the signals from the amplifying means, a time-switch limiting the operation of said motor to integrating periods of a predetermined duration, means controlled by the rotation of the motor for producing a number of impulses proportional to the number of revolutions executed by said motor during each integrating period and a meter controlled by last-mentioned means and counting the number of impulses produced during each integrating period and showing its value expressed in percentages of irregularity.

27. In an apparatus as claimed in claim '1, the provision of an automatic integrator comprising a DC. motor, means feeding said motor with the signals from the multiplying means, a time-switch limiting the operation of said motor to integrating periods of a predetermined duration, a photo-cell, a source of light facing said cell, a

notched disc keyed to the motor and adapted to conceal the cell with reference to the light from said source at least once for each revolution of the DC. motor, and a meter controlled by the impulses produced by the impact of light onto said cell and counting the number of impulses produced during each integrating neriod and showing its value expressed in percentages of irregularity.

28. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a selective circuit, means feeding said selective circuit with output signals from the amplifying means, tuning means for the selector circuit, an amplifier stage fed by the selective circuit, means for modulating the signal produced by the amplifier stage at an acoustic frequency, and si nalling means controlled by the modulated signal from the output of said amplifier stage.

29. In an ap aratus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a selective circuit, means feeding said selective circuit With output signals from the amplifying means, tuning means for the selector circuit, said selective control circuit shifting the phase of the signals received by it between its input and output to obtain a substantially zero phase shifting for resonant conditions, an amplifier stage fed by the selective circuit, means for modulating the signal produced by the amplifier stage at an acoustic fre- 2t? quency, a reaction circuit connecting the output of the amplifier stage with the input of said selective circuit, a control circuit including a diode and an ear-piece in series and controlled by the modulated signal from the amplifier stage through thereaction and selective circuits.

30. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a selective circuit, means feeding said selective circuit with output signals from the amplifying means, tuning means for the selector circuit, an amplifier stage fed by the selective circuit, said amplifier stage including a tube containing two control grids, modulating means connected with one of said control grids for modulating the signal produced by the amplifier stage at an acoustic frequency, a control circuit including a diode and an ear-piece inserted in series and controlled by the modulated signal from the amplifier stage.

31. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and includinga selective circuit, means feeding said selective circuit with output signals from the amplifying means, tuning means for the'selector circuit, said selective control circuit'shifting the phase of the signals received by it between its input and output to obtain a substantially zero phase shifting for resonant conditions, an amplifier stage fed by the selective circuit, means for modulating the signal produced by the amplifier stage at an acoustic frequency a reaction circuit connecting the output of the amplifier stage with the input of said selective circuit, a demodulator inserted in the reaction circuit and including a diode, a condenser and a potentiometer shunting said condenser and adapted to adjust the intensity of the signal from the reaction circuit, a control circuit including a diode and an ear-piece in series and controlled by the modulating signal from the amplifier stage through the reaction and selective circuits.

32. In an apparatus as claimed in claim 1, the provision of means for finding periodical components in the irregularities of the flow of fibres and including a selective circuit constituted by a Wien bridge of the resistance and capacity type, means feeding said selective circuit With output signals from the amplifying means, tuning means for the selector circuit, an amplifier stage fed by the selective circuit, means for modulating the signal produced by the amplifier stage at an acoustic frequency, and signalling means controlled by the modulated signal from the output of said amplifier stage.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,368 Grob et a1. May '22, 1951 FOREIGN PATENTS 479,152 Italy Mar. 18, 1953 337,341 Switzerland May 15, 1959