CAPACITIVE DETECTION DEVICE COMPRISING A MODULE FOR POLARIZATION BY INDUCTION

Abstract

A device for capacitive detection of an object (O), including at least one biasing module configured to bias at least one measurement electrode at an alternating electric potential (Vg), referred to as work potential, different from a ground potential (M); and measurement electronics; at least one biasing module including at least one toroidal element, referred to as excitation element, with a central opening designed to induce, in at least one electrical conductor which passes therethrough and which is in electrical connection with at least one measurement electrode, an alternating potential difference equal to the alternating electrical work potential (Vg), between an input and an output of the at least one toroidal element. An apparatus using such a capacitive detection device is also included.

Claims

1. A device for capacitive detection of an object (o), comprising: at least one polarization module configured to polarize at least one measurement electrode at an alternating electrical potential (V.sub.g), called working potential, different from a ground potential (M); and measurement electronics configured to measure a signal relating to a capacitance (C.sub.oe), called object-electrode capacitance, seen by said at least one measurement electrode, at a working frequency; at least one polarization module comprises at least one toroidal element, called excitation toroidal element, with a central opening: provided to be placed around at least one electrical conductor electrically connected to said at least one measurement electrode, through the central opening; and comprising at least one electrical winding, supplied by an alternating electrical signal (V), arranged to generate a circular magnetic field (B) in the excitation toroidal element and an axial magnetic field vector potential (E) in said central opening; so as to induce, in said electrical conductor, an alternating potential difference equal to said working alternating electrical potential (V.sub.g), between an input and an output of said at least one toroidal element.

2. The device according to claim 1, characterized in that the polarization module comprises several toroidal elements, each comprising at least one electrical winding supplied by an alternating voltage (V), so as to induce an alternating potential difference equal to the working alternating electrical potential (V.sub.g) in any conductor passing through all of said toroidal elements.

3. The device according to claim 1, characterized in that at least one excitation toroidal element comprises a ferromagnetic core around which is wound the at least one electrical winding of said excitation toroidal element.

4. The device according to claim 1, characterized in that at least one excitation toroidal element comprises several distinct electrical windings.

5. The device according to claim 1, characterized in that the polarization module comprises, for at least one electrical winding of an excitation toroidal element, an electric power supply circuit for said winding forming, with said electrical winding, a resonant circuit tuned to the working frequency.

6. The device according to claim 1, characterized in that it comprises an induction sensor, connected to the measurement electronics, and configured to provide said measurement electronics with an electrical signal as a function of the electrode-object capacitance seen by at least one measurement electrode, said induction sensor comprising at least one toroidal element, called receiving toroidal element, comprising a central opening: provided to be placed around an electrical conductor electrically connected to said at least one measurement electrode; and comprising at least one electrical winding, called receiving electrical winding, in which said electrical signal is induced.

7. The device according to claim 6, characterized in that the measurement electronics comprise a voltage amplifier, respectively a transimpedance amplifier, connected to said induction sensor and outputting a voltage (V.sub.s) relative to the voltage, respectively to the current, provided by said induction sensor, and in particular by the electrical winding of said induction sensor.

8. The device according to claim 1, characterized in that the measurement electronics comprise an amplifier of the transimpedance type configured to measure a current or a charge originating from at least one measurement electrode and output a voltage (V.sub.s) as a function of said current, respectively of said charge.

9. An appliance including: a capacitive detection device according to claim 1; and at least one measurement electrode electrically connected to an electrical conductor passing through the central opening of the at least one excitation toroidal element of the polarization module of said capacitive detection device.

10. The appliance according to claim 9, characterized in that it comprises at least one measurement electrode comprising, or consisting of: an additional capacitive electrode mounted on a portion of the appliance, an electrically conductive part of said appliance, such as a casing or a trim element of said appliance, a constituent portion of said appliance, such as a segment, a functional head, in particular interchangeable, equipping said appliance, or all of said appliance.

11. The appliance according to claim 9, characterized in that it comprises a polarization module positioned: around a base element of said appliance serving to fix said appliance to an external support, or between said base element and said external support, for example in the form of an intermediate part or a base, or around one or a plurality of electrical cables connected to the appliance.

12. The appliance according to claim 9, characterized in that it comprises a first polarization module and a second polarization module positioned on either side of the at least one measurement electrode.

13. The appliance according to claim 12, characterized in that the second polarization module is arranged so as to induce, in at least one electrical conductor passing through it, an alternating potential difference (−V.sub.g) of the same value and opposite sign to the working alternating electrical potential (V.sub.g), between an input of said second polarization module located on the side of the output of the first polarization module, and the output of said second polarization module.

14. The appliance according to claim 12, characterized in that the second polarization module is arranged so as to induce, in at least one electrical conductor passing through it, an alternating potential difference different from said working alternating electrical potential (V.sub.g), between an input of said second polarization module located on the side of the output of the first polarization module, and the output of said second polarization module.

15. The appliance according to claim 9, characterized in that the capacitive detection device comprises at least one induction sensor placed: around one or a plurality of electrical conductors electrically connected to at least one measurement electrode, around a base element of said appliance serving to fix said appliance to an external support, between said base element and said external support, for example in the form of an intermediate part or a base, or around one or a plurality of electrical cables connected to said appliance.

16. The appliance according to claim 9, characterized in that the appliance is a robot or a portion of a robot, mobile or fixed.

17. The appliance according to claim 9, characterized in that the appliance is a display device comprising an electrical display screen.

Description

DESCRIPTION OF THE FIGURES AND EMBODIMENTS

[0145] Other advantages and characteristics will become apparent on examination of the detailed description of an embodiment which is in no way limitative, and the attached drawings, in which:

[0146] FIG. 1 is a diagrammatic representation of the operating principle of a polarization module of a capacitive detection device according to the invention;

[0147] FIGS. 2a-2e are diagrammatic representations of different non-limitative embodiment examples of a polarization module of a capacitive detection device according to the invention;

[0148] FIGS. 3a-5 are diagrammatic representations of different non-limitative embodiment examples of a capacitive detection device according to the invention;

[0149] FIG. 6a is a diagrammatic representation of a non-limitative embodiment example of an induction sensor that can be implemented in a capacitive detection device according to the invention;

[0150] FIG. 6b is a diagrammatic representation of a non-limitative embodiment example of measurement electronics that can be implemented in a capacitive detection device according to the invention; and

[0151] FIGS. 7-13 are diagrammatic representations of different non-limitative embodiment examples of an appliance according to the invention.

[0152] It is of course understood that the embodiments that will be described hereinafter are in no way limitative. In particular, variants of the invention can be imagined comprising only a selection of the characteristics described hereinafter, in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art. This selection comprises at least one, preferably functional, characteristic without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art.

[0153] In the figures, elements common to several figures keep the same reference.

[0154] FIG. 1 is a diagrammatic representation of the operating principle of a polarization module of a capacitive detection device according to the invention.

[0155] FIG. 1 represents an excitation toroidal element 102 according to an isometric view and according to a cross-sectional view.

[0156] The excitation toroidal element 102 includes a central opening 104.

[0157] The excitation toroidal element 102 can have different architectures, non-limitative examples of which will be described hereinafter. In FIG. 1, the excitation toroidal element 102 is formed by a ferromagnetic core 106 having a circular cross section and a circular shape, for example made of ferrite, around which is wound a winding 108 including a single turn.

[0158] An electrical conductor 110 passes through the central opening 104 of the excitation toroidal element 102. The electrical conductor 110 enters the central opening 104 through an input 112 and leaves the central opening 104 through an output 114. This electrical conductor 110 can be, for example, an electrical cable, or an electrical track, for connecting a measurement electrode, or a conductive part of the structure of an appliance.

[0159] The flow of an alternating electrical current “i” in the electrical winding 108 generates a magnetic field B in the excitation toroidal element 102. This magnetic field B flows around the central opening 104, the space in which the electrical conductor 110 is located. The magnetic field B is associated with a magnetic field vector potential, A, defined by B=Rot(A) in the space surrounded by this magnetic field B. A temporal variation of this magnetic field vector potential A generates an electric field, E, following the same direction and according to the relationship E=∂A/∂t. This electric field E will establish a potential difference ΔV, along the field lines defined by the vector potential A.

[0160] As a result, the conductive element 110, passing through the central opening 104 containing the field lines, will see an electrical potential difference ΔV appear between the sections thereof respectively upstream and downstream of this space, i.e. between the section thereof located before the input 112 of the central opening 104 and the section thereof located after the output 114 of the central opening 104. Put another way, with respect to any reference whatever such as a general ground, if the conductor 110 is at the potential V1 at the level of the input 112 of the central opening 104, this same conductor 110 will be at the potential V2=V1+ΔV, at the level of the output 114 of the toroidal element 102.

[0161] It should be noted that this potential difference ΔV is superposed on all the potentials present in the conductor 110 which passes through the toroidal element 102. Thus, for example, if the potential V1 is a reference potential or general ground potential of the electronics upstream of the excitation toroidal element 102, the alternating potential V2=V1+ΔV becomes the reference potential downstream of the toroidal element 102.

[0162] Thus, it is possible to polarize any conductor passing through the toroidal element 102 at a working alternating potential, denoted V.sub.g, by choosing ΔV=V.sub.g.

[0163] The architecture of the excitation toroidal element 102, represented in FIG. 1, is in no way limitative and is given by way of example.

[0164] FIG. 2a is a diagrammatic representation, seen from above, of a non-limitative embodiment example of a polarization module of a capacitive detection device according to the invention.

[0165] The polarization module 200, represented in FIG. 2a, comprises an excitation toroidal element 202.

[0166] The excitation toroidal element 202 is formed by an electrical winding 204 in the shape of a toroid. More particularly, the electrical winding 204 has a shape having rotational symmetry, in particular circular.

[0167] The electrical winding 204 has a shape having a circular cross section. Alternatively, the electrical winding 204 can have a cross-section which is triangular, square, rectangular, etc.

[0168] In the example represented in FIG. 2a, the excitation toroidal element 202 does not include a core around which is wound the electrical winding 204. In other words, the electrical winding 204 is wound around air.

[0169] According to an alternative, the excitation toroidal element 202 can include a core around which is wound the electrical winding 204. In this case, the core can be made from a ferromagnetic material, or from a material which is not ferromagnetic.

[0170] The polarization module 200 also comprises an electrical source 206 supplying the electrical winding 204 with an alternating voltage V. Assuming that the electrical winding 204 comprises “m” turns, in order to induce an alternating potential difference equal to V.sub.g in any electrical conductor 110 which passes through said excitation toroidal element 202, it is necessary to supply the electrical winding 204 with a voltage V=m.Math.V.sub.g, disregarding the coupling losses.

[0171] FIG. 2b is a diagrammatic representation of a non-limitative embodiment example of a polarization module of a capacitive detection device according to the invention.

[0172] The polarization module 200 comprises an excitation toroidal element 212.

[0173] The excitation toroidal element 212 of FIG. 2b comprises an electrical winding 214 wound around a ferromagnetic core 216.

[0174] In the example represented, the electrical winding 214 comprises a single turn. Of course, the electrical winding 214 can comprise more than one turn.

[0175] The polarization module 210 also comprises an electrical source 218 for supplying the electrical winding 214 with an alternating voltage V.

[0176] In the example represented in FIG. 2b, disregarding the losses, an excitation alternating potential difference V=V.sub.g is applied at the terminals of the electrical winding 214 comprising a single turn. Thus, the polarization module 200 generates, in any electrical conductor 110 which passes through the excitation toroidal element 212, a potential difference ΔV=V.sub.g between the input of the excitation toroidal element 212 and the output of the excitation toroidal element 212.

[0177] In general, as indicated above, if a voltage V is applied at the terminals of an electrical winding having “m” turns wound around the core 216, the potential difference induced on the electrical conductor 108 passing through the excitation toroidal element 212 would be ΔV=V/m. As a result, if a potential difference V.sub.g is desired across the conductor 110 with an electrical winding comprising “m” turns wound around the core 216, then said electrical winding must be supplied with a voltage V=m.Math.V.sub.g.

[0178] In addition, according to a general definition, the voltage source 206 providing the voltage V “sees” an impedance which depends on the inductance of the electrical winding, which increases with the number of turns and the surface area encompassed by the turn or turns. The inductance L.sub.m of an electrical winding having “m” turns is thus L.sub.m=m.sup.2 L, with L the inductance of a turn having the same surface area.

[0179] FIG. 2c is a diagrammatic representation of another non-limitative embodiment example of a polarization module of a capacitive detection device according to the invention.

[0180] The polarization module 220 of FIG. 2c comprises an excitation toroidal element 222.

[0181] The excitation toroidal element 222 of FIG. 2c comprises several, and in particular three, distinct electrical windings 224.sub.1-224.sub.3 wound around a ferromagnetic core 216.

[0182] In the example represented, each electrical winding 224.sub.1-224.sub.3 comprises a single turn. Of course, at least one of the electrical windings 224.sub.1-224.sub.3 can comprise more than one turn.

[0183] The electrical windings 224.sub.1-224.sub.3 represented in FIG. 2c are identical. Alternatively, at least two of the windings 224.sub.1-224.sub.3 can be different. In this case, the electrical windings including different numbers of turns are supplied with different alternating voltages.

[0184] In FIG. 2c, the electrical windings 224.sub.1-224.sub.3 are placed at a constant angular pitch of 120° in order to ensure a better distribution of the magnetic field. Of course, according to alternatives, the angular pitch between the windings may not be constant.

[0185] Moreover, the excitation toroidal element 222 can comprise a number of electrical windings different to three.

[0186] In the example represented in FIG. 2c, each electrical winding 224.sub.1-224.sub.3 is supplied with a voltage V=V.sub.g such that an alternating potential difference equal to V.sub.g is generated in any electrical conductor 110 which passes through the excitation toroidal element 222, since each electrical winding 224.sub.1-224.sub.3 includes a single turn. According to a general definition, in the example of FIG. 2c, if at least one of the electrical windings comprises “m” turns, then it would be necessary to supply said electrical winding with an alternating voltage V=V.sub.g.Math.m, in order to generate an alternating potential difference equal to V.sub.g in any electrical conductor 110 which passes through the excitation toroidal element 222.

[0187] The polarization module 220 comprises, for each electrical winding 224.sub.1-224.sub.3, an electrical source, respectively 218.sub.1-218.sub.3, dedicated to supplying said electrical winding. Alternatively, at least two, in particular all the, electrical windings 224.sub.1-224.sub.3 can be supplied by a single electrical source common to all of said electrical windings.

[0188] It should be noted that, for “p” distinct electrical windings around one and the same ferromagnetic core, due to the couplings by mutual inductance, the inductance L.sub.p of each electrical winding is given by L.sub.p=p L, with L the inductance of an electrical winding which would alone be around said core. Thus, the inductance of p electrical windings in parallel, supplied by one and the same electrical source, corresponds to: p.Math.L/p=L, namely the same inductance as that of a single winding. The power consumed by “p” electrical windings is therefore the same as the power consumed by a single electrical winding.

[0189] FIG. 2d is a diagrammatic representation of another non-limitative embodiment example of a polarization module of a capacitive detection device according to the invention.

[0190] The polarization module 230 of FIG. 2d comprises an excitation toroidal element 232.

[0191] The excitation toroidal element 232 of FIG. 2d comprises all the components of the excitation toroidal element 212 of FIG. 2b.

[0192] The excitation toroidal element 232 also comprises a capacitor 234 in parallel with the electrical winding 214, such that the electrical winding 214 forms, with said capacitor 234, a resonant circuit. The capacitance of the capacitor 234 and the inductance value of the electrical winding 214 are chosen such that the resonant frequency of the resonant circuit is equal to the working frequency, denoted f.sub.g, i.e. to the working potential frequency V.sub.g.

[0193] The setting in resonance, via the addition of a capacitor 234, makes it possible to increase the impedance and therefore reduce the supply current of the winding 214. In this case, the electrical source 206 must be tuned to the frequency f.sub.g given by the following relationship

[00001]$f_g=\frac{1}{2\pi \sqrt{C.\mathrm{Leq}}},$

with C the capacitance of the capacitor 234 and Leq the resulting inductance.

[0194] This configuration, illustrated in FIG. 2d with a single electrical winding can of course be used in each of the examples given in FIGS. 2a-2c, with each of the excitation toroidal elements 202, 212 and 222.

[0195] As explained previously with reference to FIG. 2c, the inductance of each of the windings, with “p” windings, is L.sub.p=p L, with L the inductance of an electrical winding which would alone be around a toroidal core. If C is the capacitance in order to obtain a resonance at the excitation frequency f.sub.g with a single inductance winding L, the capacitance C.sub.p to be placed in parallel with each of the p coupled windings in order to obtain the same resonant frequency is C.sub.p=C/p, which gives

[00002]$f_g=\frac{1}{2\pi \sqrt{\frac{C}{p}.p.L}}.$

[0196] Each of the polarization modules 200, 210, 220 and 230 which have just been described comprises a single excitation toroidal element.

[0197] Alternatively, a polarization module can comprise several identical or different excitation toroidal elements placed in a cascade.

[0198] FIG. 2e is a diagrammatic representation of another non-limitative embodiment example of a polarization module of a capacitive detection device according to the invention.

[0199] The polarization module 240, represented in FIG. 2e, comprises “n” excitation toroidal elements 212.sub.1-212.sub.n, placed in a cascade in series along an electrical conductor 110 which passes through each of said excitation toroidal elements 212.sub.1-212.sub.n.

[0200] In the polarization module 240, the n excitation toroidal elements are identical. Alternatively, the polarization module 240 can comprise at least two different excitation toroidal elements.

[0201] Each of the n excitation toroidal elements 212.sub.1-212.sub.n of the polarization module 240 is identical to the excitation toroidal element 212 of FIG. 2b. Alternatively, at least one of the excitation toroidal elements can be any one of the excitation toroidal elements 202, 222 or 232.

[0202] The electrical winding of each excitation toroidal element 212, is supplied by an independent electrical source. Alternatively, the electrical windings of at least two of the, in particular of all the, excitation toroidal elements 212.sub.1-212.sub.n can be supplied by a single electrical source.

[0203] In general, when a polarization module comprises several excitation toroidal elements in a cascade, each excitation toroidal element will contribute to a portion ΔV.sub.i of the increase of the targeted potential ΔV=V.sub.g, with ΔV=Σ.sub.nΔV.sub.i. Moreover, each excitation toroidal element with one or more windings with “m” turns contributes to a potential difference ΔV.sub.i=V/m, disregarding the losses. The total potential difference obtained is n times the potential difference of each excitation toroidal element (V/m).

[0204] Thus, in the example represented in FIG. 2e, each excitation toroidal element 212.sub.i contributes to a portion ΔV.sub.i of the increase of the targeted potential ΔV=V.sub.g. In addition, as each excitation toroidal element 212.sub.i comprises a single electrical winding with a single turn, then each electrical winding is supplied with an alternating voltage V=ΔV.sub.i=V.sub.g/n.

[0205] When all the “n” electrical windings are supplied by a single electrical source, considering that all the “n” electrical windings have the same geometry or at least the same surface area and include “m” turns, the inductance L.sub.T of all the electrical windings “seen” in parallel by one and the same voltage source is: L.sub.T=m.sup.2L/n, or L.sub.T=nL for m=n. It follows that the power consumed in this configuration is less than for an excitation toroidal element including a single electrical winding.

[0206] The configuration shown in FIG. 2e can be implemented with a plurality of electrical windings in parallel for each toroidal element, for a better homogeneity of the potential differences induced without change with regard to the potential difference ΔV generated and the power consumed.

[0207] FIG. 3a is a diagrammatic representation of a non-limitative embodiment example of a capacitive detection device according to the invention.

[0208] The capacitive detection device 300, represented in FIG. 3a, comprises at least one electrode 302, called measurement electrode, and optionally at least one electrode 304, called guard electrode, to electrically guard the measurement electrode 302. This guard electrode 304 can for example be placed under the measurement electrode 302 on the opposite side to the detection zone/surface.

[0209] The detection device 300 comprises at least one polarization module 306 for polarizing the measurement electrode 302, and the guard electrode 304 where appropriate, at a working alternating potential V.sub.g, different from a ground potential, denoted M, at a working frequency, denoted f.sub.g. The polarization module 306 can be any one of the polarization modules 200, 210, 220, 230 or 240 of FIGS. 2a-2e.

[0210] The polarization module 306 carries out a polarization of the measurement electrode 302 by induction of an alternating potential difference, equal to the working alternating potential V.sub.g, in an electrical conductor 308 electrically connected to said measurement electrode 302, and passing through the polarization module 306. Similarly, the polarization module 306 polarizes the guard electrode 304 by induction of an alternating potential difference, equal to the alternating working potential V.sub.g, in an electrical conductor 310 electrically connected to said guard electrode 304, and passing through the polarization module 306.

[0211] In general, the polarization module 306 polarizes all of the conductors which pass through it at the working alternating potential V.sub.g. Thus, the guard electrode 304 can represent any portion of the appliance polarized at the working potential V.sub.g and not used as measurement electrode 302.

[0212] The detection device 300 also comprises measurement electronics 312, connected to the measurement electrode 302 and configured to output a signal proportional to an object-electrode coupling capacitance, denoted C.sub.oe, between the measurement electrode 302 and an object O, such as a hand approaching or in contact with a detection surface.

[0213] In the capacitive detection device 300 as illustrated, the measurement electronics 312 are placed downstream of the polarization module 306, between the polarization module and the measurement electrode. The measurement electrode 302 is polarized at the working potential V.sub.g via these measurement electronics 312, which are themselves preferably referenced to the working potential V.sub.g. The measurement electrode 302 and the guard electrode 304 are polarized at the working potential V.sub.g by the same electrical connection 308 passing through the polarization module 306. The output of the measurement electronics 312 is effected by an electrical connection 314 which also passes through the polarization module 306 but in the opposite direction, which makes it possible to transform a measurement signal at the output of the measurement electronics 312 referenced to the working potential into a measurement signal referenced to the ground M after passing into the polarization module 306.

[0214] FIG. 3b is a diagrammatic representation of another non-limitative embodiment example of a capacitive detection device according to the invention.

[0215] The capacitive detection device 350, represented in FIG. 3b, differs from the device 300 in that the measurement electronics 312 are placed upstream of the polarization module 306 such that the polarization module 306 is located between the measurement electrode 302 and the measurement electronics 312. In this case, the measurement electrode 302 is polarized at the working potential V.sub.g, and connected to the measurement electronics 312, by a conductor 308 which passes through the polarization module. The measurement electronics 312 are preferably referenced to the ground potential M and directly output, across the electrical connection 314, a measurement signal referenced to the ground M.

[0216] In the examples illustrated in FIGS. 3a and 3b, and more generally in all the examples that will be described, at least one electrical conductor 308, respectively 310, passing through the polarization module 306, and electrically connected to at least one measurement electrode 312, respectively to a guard electrode 304, can be: [0217] a track or an electric wire of said electrode, or [0218] a part or a portion of an appliance equipped with the detection device 300, in electrical contact with said electrode, such as a trim element, a framework element, a segment in the case of a robot or a robotized arm, etc., or [0219] a portion or all of the body of an appliance equipped with the detection device 300.

[0220] In the examples illustrated in FIGS. 3a and 3b, and more generally in all the examples that will be described, at least one measurement electrode 302, respectively one guard electrode 304, can comprise, or consist of: [0221] an additional capacitive electrode mounted on a portion of an appliance equipped with the detection device 300; [0222] an electrically conductive part of said appliance, such as a casing or a trim element, [0223] a constituent portion of said appliance, such as a segment, [0224] a functional head, in particular interchangeable, with which said appliance is equipped, or [0225] all of said appliance.

[0226] FIG. 4 is a diagrammatic representation of another non-limitative embodiment example of a capacitive detection device according to the invention.

[0227] The capacitive detection device 400, represented in FIG. 4, comprises all the components of the detection device 350 of FIG. 3b.

[0228] The capacitive detection device 400 also comprises an induction sensor 402 placed between the measurement electronics 312 and an electrical conductor 308 electrically connected to the measurement electrode 302. In this capacitive detection device 400, the induction sensor 402 is also positioned between the measurement electrode 302 and the polarization device 306.

[0229] In particular, the induction sensor 402 comprises at least one toroidal element, called receiving toroidal element, including one central opening passed through by the at least one electrical conductor 308.

[0230] The current flowing in the electrical conductor 308, passing through the central opening of the induction sensor 402, induces an alternating signal in an electrical winding of the receiving toroidal element of the induction sensor 402, as illustrated below. This signal is a function of the capacitance C.sub.oe seen by the measurement electrode. This signal can then be measured by the measurement electronics 312 connected to the induction sensor 402.

[0231] A non-limitative example of an induction sensor 402 is given below, with reference to FIG. 6a.

[0232] FIG. 5 is a diagrammatic representation of another non-limitative embodiment example of a capacitive detection device according to the invention.

[0233] The capacitive detection device 500, represented in FIG. 5, comprises all the components of the detection device 400 of FIG. 4.

[0234] The capacitive detection device 500 differs from the detection device 400 in that the induction sensor 402 and the measurement electronics 312 are placed upstream of the polarization module 306 such that the polarization module 306 is located between the measurement electrode 302 and the induction sensor 402 and the measurement electronics 312.

[0235] FIG. 6a is a diagrammatic representation of a non-limitative embodiment example of an induction sensor that can be implemented in a capacitive detection device according to the invention.

[0236] The induction sensor 600 of FIG. 6 can be the induction sensor 402 of FIGS. 4 and 5.

[0237] In the example represented, and in a manner that is in no way limitative, the induction sensor 600 comprises a receiving toroidal element 602, including a central opening passed through, in the example illustrated, at least by the electrical conductor 308 connected to the at least one measurement electrode 302.

[0238] The receiving toroidal element 602 is identical to, or can be produced in the same manner as, the excitation toroidal element 212 of FIG. 2b. It comprises an electrical winding 604 wound around a ferromagnetic core 606. The electrical winding 604 is connected to the measurement electronics 312, which can be the measurement electronics 312 of FIGS. 3a-5.

[0239] In the example represented, the electrical winding 604 comprises a single turn. Of course, the electrical winding 604 can comprise more than one turn.

[0240] In general, the induction sensor 600 can comprise a receiving toroidal element, or a combination of several receiving toroidal elements placed in a cascade, including a central opening passed through at least by an electrical conductor connected to at least one measurement electrode 302.

[0241] In a manner that is in no way limitative, at least one receiving toroidal element can be formed by: [0242] at least one electrical winding toroid in shape, and in particular with rotational symmetry, and the cross section of which can be circular, square, rectangular, etc. in shape, such as for example the toroidal element 202 of FIG. 2a, [0243] at least one core, in particular ferromagnetic, each including one or more electrical windings wound around said core, and each including at least one turn, such as for example any one of the toroidal elements 212, 222 or 232 of FIGS. 2b-2d.

[0244] FIG. 6b is a diagrammatic representation of a non-limitative embodiment example of measurement electronics that can be implemented in a capacitive detection device according to the invention.

[0245] The measurement electronics 610, represented in FIG. 6b, can be, or be comprised in, the measurement electronics 312 of FIGS. 3-5.

[0246] In the example represented, and in a manner that is in no way limitative, the measurement electronics 610 comprise a current, or charge, detector 612, for example of the transimpedance amplifier type, which measures the current generated at the working frequency of the potential V.sub.g by the capacitive coupling between the measurement electrode 302 and the object O. This transimpedance amplifier can comprise an operational amplifier (OA) 614 with:

[0247] the inverting input (“−”) connected to the measurement electrode 302, or to the induction sensor 402, and receiving the current i to be measured;

[0248] the non-inverting input (“+”) connected to a reference potential V.sub.ref corresponding, according to the configurations, to the working potential V.sub.g or to the ground potential M; and

[0249] the output fed back to its inverting input, with a feedback capacitor 616, and optionally a resistor (not represented).

[0250] Under these conditions, the output of the OA 614 provides a voltage V.sub.s as a function of the current i and therefore of the capacitance C.sub.oe. The output of the OA 614 can be connected to a step of synchronous detection, which makes it possible to obtain, by synchronous demodulation with a carrier corresponding to the working potential V.sub.g, the capacitive signal at the working frequency.

[0251] In the capacitive detection device 300, the measurement electronics 312 utilize measurement electronics 610 with the inverting input (“−”) connected to the measurement electrode 302 and the non-inverting input (“+”) connected to the working potential V.sub.g. Preferably, this measurement electronics 312 is also referenced by its electric power supplies to the working potential V.sub.g, to avoid internal leakage capacitances. The output of these measurement electronics is effected as explained previously by the electrical connection 314 which also passes through the polarization module 306 but in the opposite direction, which makes it possible to transform a measurement signal V.sub.s at the output of the measurement electronics 312 referenced to the working potential Vg into a measurement signal V.sub.s referenced to the ground M after passing into the polarization module 306. It should be noted that passing through the polarization module does not modify the measurement signal V.sub.s with respect to the reference under consideration (Vg or M).

[0252] In the capacitive detection device 350, the measurement electronics 312 utilize measurement electronics 610 with the inverting input (“−”) connected to the measurement electrode 302 through the polarization module, and the non-inverting input (“+”) connected to the ground potential M. The output of these measurement electronics directly produces a measurement signal V.sub.s referenced to the ground M. Preferably, these measurement electronics 312 are also referenced by its electric power supplies to the ground potential M.

[0253] In the capacitive detection devices 400 and 500, the measurement electronics 312 utilize measurement electronics 610 with the inverting input (“−”) and the non-inverting input (“+”) connected respectively to the two ends of a winding of the induction sensor 402, so as to measure the current which is flowing in this winding by induction. The inverting input (“−”) can also be connected at a potential which determines the reference potential of these electronics, or for example at the working potential Vg in the capacitive detection device 400, and the ground potential M in the capacitive detection device 500, so as to limit the parasitic coupling capacitances.

[0254] Alternatively, and when the capacitive detection device comprises an induction sensor, the measurement electronics can be, or comprise, a voltage amplifier connected to said induction sensor and outputting a voltage relative to the voltage provided by said induction sensor.

[0255] FIG. 7 is a partial diagrammatic representation of a non-limitative embodiment example of an appliance according to the invention.

[0256] The appliance 700, represented in FIG. 7, is very simplified and can be any type of appliance, such as a robot, a robotized arm, any type of machine, etc.

[0257] The appliance 700 comprises one or more electrical members. In the example represented, the appliance 700 comprises a motorized gripping member 702, such as a motorized gripper, supplied by electrical lines 704-706 connected to an electrical plug 708. The electrical plug 708 is intended to be connected to an electrical interface external to the appliance 700 providing the electrical energy supplying the gripping member 702.

[0258] The appliance 700 is equipped with a capacitive detection device according to the invention, such as for example the device 400 of FIG. 4. As described above, the device 400 comprises a measurement electrode 302, an optional guard electrode 304, a polarization module 306, an induction sensor 402 and measurement electronics 312. The polarization module 306 polarizes the measurement 302 and guard 304 electrodes, at the working potential V.sub.g, by inducing an alternating potential difference equal to the working potential V.sub.g in the electrical conductors 308 and 310 which pass through it and which are connected to these electrodes 302 and 304.

[0259] In the appliance 700, the presence of electrical members polarized at a potential other than the guard potential V.sub.g, in proximity to the measurement electrode 302, or to any electrical conductor which is connected to it, can disrupt the capacitive detection, by creating parasitic capacitances. Yet the electrical plug 708, the conductors 704 and 706 and the gripping member 702 are at the reference potential M which is the input potential of the appliance 700 or the potential of the external source, and generally a general ground potential. As a result, these electrical members 702-708 risk disrupting the capacitive detection.

[0260] In order to avoid this disruption, the polarization module 306 is placed, not only around the electrical conductors 308 and 310 which are connected to the electrodes 302 and 304, but also around the electrical conductors 704 and 706 which are connected to the gripping member 702. Thus, the polarization module 306 induces an alternating potential difference equal to the guard potential V.sub.g both in the conductors 308 and 310, but also in the conductors 704 and 706. In other words, the polarization module 306 superposes the working potential V.sub.g on the other potentials, or signals, already present in the conductors 704 and 706, over all the portion of these conductors 704 and 706 located downstream of the polarization module 306, i.e. between the polarization module 306 and the motorized gripping member 702.

[0261] Thus, the conductors 704 and 706 and the gripping member 702 are at the guard potential V.sub.g. As a result, at the working frequency f.sub.g of the working potential V.sub.g, the conductors 704 and 706, and the gripping member 702, are at the same potential as the measurement electrode 302 and therefore do not disrupt the capacitive detection.

[0262] It should be noted that the working potential V.sub.g is superposed on all the other potentials present in the conductors 704 and 706, and on all the signals circulating in the conductors 704 and 706, including at the reference potential of these signals. Thus, these signals are not affected by the superposition of the working potential V.sub.g in the conductors 704 and 706 such that the operation of the gripping member 702 is not impacted.

[0263] The simplified example which has just been described with a single electrical member can potentially be applied to all the electrical members, and to all the electrically conductive parts, of an electrical or electronic appliance. The polarization module of the capacitive detection device according to the invention can be used to polarize one or more electrical members of an appliance, one or more electrically conductive parts, but also a portion or all of an appliance at the working potential.

[0264] Thus, according to a general definition, any conductive element capable of establishing a parasitic capacitance able to disrupt the capacitive detection can be polarized at the working potential V.sub.g, such as for the gripping member 702 and the electrical conductors 704 and 706. In this manner, all these elements which are polarized but not used to carry out the capacitive measurement operate as guard electrodes 304.

[0265] The appliance 700 comprises the detection device 400 of FIG. 4 which allows a measurement of the coupling capacitance specifically between a measurement electrode 302 and the surroundings.

[0266] Of course, the appliance 700 can be equipped with another capacitive detection device according to the invention, such as for example any one of the devices 300, 350 or 500, or any one of their alternatives.

[0267] FIG. 8a is a partial diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0268] The appliance 800, represented in FIG. 8a, comprises all the elements of the appliance 700 of FIG. 7, except the guard electrode 304 and the conductor 310.

[0269] In addition, unlike the appliance 700, in the appliance 800, the induction sensor 402 is placed around, not only the electrical conductor 308 connected to the measurement electrode 302, but also around the electrical conductors 704 and 706 connected to the gripping member.

[0270] According to a general definition, according to the invention, any conductive element capable of establishing a capacitance with another element or the surroundings can be passed through the induction sensor 402.

[0271] This embodiment makes it possible to monitor the general state of the elements polarized at the working potential V.sub.g, in order to detect coupling capacitances between the surroundings and the conductive elements, for example the conductive wires 704 and 706 or the measurement electrode 302. In fact, in the absence of any coupling capacitances, the currents flowing in the conductors 704 and 706 cancel one another out in the induction sensor 402. Similarly, when no object is detected by the measurement electrode 302, no current flows in the conductor 308. As a result, in the absence of coupling capacitances with the surroundings, the sum of the currents passing through the central opening of the sensor is zero, and the induction sensor 402 should not detect anything. However, in the case of capacitive coupling between an object and the measurement electrode 302, or elements connected to the conductors 704 and 706, all of the currents flowing in the conductors passing into the induction sensor 402 do not cancel one another out, which induces a non-zero signal in this induction sensor 402.

[0272] Thus, this embodiment makes it possible to carry out an overall capacitive detection with all of the elements polarized at the potential V.sub.g and passing through the induction sensor 402, which can relate to a portion or even the whole appliance. In this case, all of the elements polarized at the potential V.sub.g and passing through the induction sensor 402 behave like a measurement electrode 302.

[0273] Alternatively, detection circuits associated with each element can also be used to measure, individually, the currents generated by the coupling capacitances, as illustrated with the capacitive detection device 400.

[0274] In the appliance 800, the induction sensor 402 is positioned between the measurement electrode 302 and the polarization device 306, like in the capacitive detection device 400.

[0275] FIG. 8b is a partial diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0276] The appliance 850, represented in FIG. 8b, comprises all the elements of the appliance 800 of FIG. 8a.

[0277] The appliance 850 differs from the appliance 800 in that the induction sensor 402 and the measurement electronics 312 are placed upstream of the polarization module 306 such that the polarization module 306 is located between the measurement electrode 302 and the induction sensor 402 and the measurement electronics 312. The induction sensor 402 is placed around, not only the electrical conductor 308 connected to the measurement electrode 302, but also around the electrical conductors 704 and 706 connected to the gripping member. This configuration also allows an overall measurement of capacitive coupling with all of the elements polarized at the potential V.sub.g and passing through the induction sensor 402. Its operation is the same as that of the capacitive detection device 500.

[0278] FIG. 9a is a partial diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0279] The appliance 900, represented in FIG. 9a, comprises all the elements of the appliance 800 of FIG. 8a.

[0280] In the appliance 900, the capacitive detection device comprises, in addition to the polarization module 306, a second polarization module 902. The second polarization module 902 can have an architecture identical to, or different from, that of the polarization module 306. The second polarization module 902 can be any one of the polarization modules 200, 210, 220, 230 or 240 of FIGS. 2a-2e.

[0281] The second polarization module 902 is placed around the conductors 704 and 706, just before the motorized gripping member 702.

[0282] In the example represented in FIG. 9a, the second polarization module 902 is arranged to induce an alternating potential difference equal to the working potential V.sub.g but having the opposite sign, i.e. an alternating potential difference equal to −V.sub.g, between its input located on the side of the polarization module 306 and of the measurement electrode 302 and its output located on the side of the gripping member 702. Thus, the portion of each conductor 704 and 706 located between the polarization modules 306 and 902 is polarized at the working potential V.sub.g, while the portions of these conductors 704, 706 and the gripping member 702 located on the side opposite the second polarization module 902 are brought to the initial potential, for example ground potential, from before the first polarization module 306.

[0283] Thus, the gripping member 702 can come into contact with an object or a surface at the ground potential M, or at any other potential, without however disrupting the polarization of the electrical conductors 704 and 706 at the potential V.sub.g in the portion located between the polarization modules 306 and 902. The induction sensor 402, operating at the working frequency V.sub.g, thus makes it possible to measure the coupling capacitance with all the conductors which pass through it, and which operate as measurement electrode, in the section thereof between the polarization modules 306 and 902, without being affected by a possible contact with the ground beyond the second polarization module.

[0284] FIG. 9b is a partial diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0285] The appliance 950, represented in FIG. 9b, comprises all the elements of the appliance 900 of FIG. 9a.

[0286] In this embodiment, the second polarization module 902 can be arranged to induce an alternating potential difference equal to a second working potential, denoted V.sub.g2, having a frequency f.sub.g2 different from the frequency f.sub.9 of the working potential V.sub.g, between its input located on the side of the polarization module 306 and of the electrodes 302 and 304 and its output located on the side of the gripping member 702.

[0287] Thus, the gripping member 702 and the portions of the conductors 704 and 706 located between the second polarization module 902 and the gripping member 702, are polarized at the second working potential V.sub.g2, different from the ground potential M and different from the first working potential V.sub.g, at the second working frequency f.sub.g2. This makes it possible to use the gripping member 702 as measurement electrode to carry out a capacitive detection at the second working frequency f.sub.g2. Moreover, to avoid the gripping member 702 also operating as measurement electrode at the first working frequency f.sub.9, it is also possible to superpose on the potential V.sub.g2 a potential −V.sub.g in the second polarization module 902, as previously.

[0288] In the example illustrated in FIG. 9b, the appliance 950 comprises two induction sensors 402.sub.1 and 402.sub.2 respectively coupled to detection electronics 312.sub.1 and 312.sub.2, and arranged respectively to carry out a capacitive detection at the first working frequency f.sub.g and at the second working frequency f.sub.g2. The induction sensors 402.sub.1 and 402.sub.2 can be positioned around the same conductors, for example in the portion referenced to the ground, as illustrated. As a function of the working frequencies of the measurement electronics, they will be sensitive to the capacitive couplings with the conductors between the two polarization modules 306, 902, and/or beyond the second polarization module 902.

[0289] According to other modes of implementation, one and the same induction sensor 402 and one and the same measurement electronics 312 can be used simultaneously or sequentially for the capacitive detection at the working frequency f.sub.g, and at the second working frequency f.sub.g2. Alternatively, it is possible to use an induction sensor and/or measurement electronics with or without an induction sensor, dedicated to the capacitive detection at the second working frequency f.sub.g2.

[0290] In addition, the embodiments described in FIGS. 9a and 9b can be combined with the embodiment of FIG. 7 by placing an induction sensor 402 only around a conductor 308 connected to the measurement electrode 302.

[0291] As indicated above, the guard electrode 304 is optional in all the examples described. Or more accurately, all of the elements polarized at the working potential and not used as measurement electrode act as guard electrode.

[0292] Moreover, the use of the induction sensor 402 is also optional in all the examples described. It is in fact possible to connect the measurement electronics directly to the conductor 308, without using an induction sensor.

[0293] FIG. 10 is a diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0294] The appliance 1000, represented in FIG. 10, is a robotized arm including a base segment 1002 and a distal segment 1004 equipped with a functional head, which can for example be the motorized gripping member 702 of FIGS. 7, 8a, 8b, 9a and 9b. The robotized arm includes two other intermediate segments 1006 and 1008 placed between the base segment 1002 and the distal segment 1004.

[0295] In particular, the robotized arm 1000 can be any one of the appliances 700, 800, 850, 900 or 950 of FIGS. 7, 8a, 8b, 9a and 9b.

[0296] The robotized arm 1000 is placed on a surface 1010, which is at the ground potential M.

[0297] The robotized arm 1000 is equipped with a capacitive detection device according to the invention, which can be any one of the detection devices of FIG. 3a, 3b, 4, 5, 7, 8a, 8b, 9a or 9b.

[0298] In FIG. 10, the capacitive detection device is partially represented. Thus, only the polarization module 306, the measurement electrode 302 and the conductor 308 can be seen in FIG. 10.

[0299] The polarization module 306 is placed around the base segment 1002 of the robotized arm 1000. Thus, all of the electrical conductors which pass through the polarization module 306, as well as all the electrical conductors which are in contact with them, are polarized at the guard potential Vg, downstream of the polarization module 306.

[0300] In particular, all the portion of the robotized arm 1000, which is located downstream of the polarization module 306 is polarized at the guard potential V.sub.g.

[0301] FIG. 11 is a diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0302] The appliance 1100, represented in FIG. 11, is a robotized arm including all the elements of the robotized arm 1000 of FIG. 10.

[0303] In the example of FIG. 11, unlike the robotized arm 1000 of FIG. 10, the polarization module 306 is placed between the surface 1010 and the base segment 1002.

[0304] In this example, the polarization module 306 forms a base for the robotized arm 1100.

[0305] Thus, all of the robotized arm 1100 is polarized at the guard potential V.sub.g.

[0306] In another implementation example, the robotized arm is insulated from the ground, for example by virtue of an insulating baseplate, and the polarization module 306 is positioned around the whole electric power supply and data cables connected to the robot.

[0307] Thus, in the same way as before, all of the robotized arm is polarized at the guard potential V.sub.g.

[0308] FIG. 12 is a diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0309] The appliance 1200, represented in FIG. 12, is a robotized arm including all the elements of the robotized arm 1100 of FIG. 11.

[0310] The robotized arm 1200 comprises, in addition to the polarization module 306, a second polarization module, for example the polarization module 902 of FIGS. 9a and 9b.

[0311] In the example represented, the second polarization module 902 is placed between the distal segment 1004 of the appliance 1200, and the functional head 702.

[0312] Thus, all of the robotized arm 1200 is polarized at the guard potential V.sub.g, except the functional head 702. The functional head 702 can be used as detection electrode at a second detection frequency f.sub.g2, as described with reference to FIG. 9b, or brought to a ground potential M as described with reference to FIG. 9a.

[0313] Alternatively, to that which is represented in FIG. 12, the second polarization module 902 can be placed around another segment of the robotized arm 1200, such as for example around the distal segment 1004, and not between the distal segment 1004 and the functional head 702.

[0314] Of course, according to alternatives that are not represented, it is possible to use a second polarization module 902, in the robotized arm 1000 of FIG. 10 or in the robotized arm 1100 of FIG. 11, either between the distal segment 1004 and the functional head 702, or around a segment of the robotized arm such as the distal segment 1004.

[0315] The appliance according to the invention is not limited to a robotized arm and can be any electrical or electronic appliance.

[0316] FIG. 13 is a diagrammatic representation of another non-limitative embodiment example of an appliance according to the invention.

[0317] The appliance 1300, represented in FIG. 13, is an electronic display appliance comprising a display screen 1302 supplied by an electric power supply cable 1304, communication or data cables 1305 and a support strut 1306 of said display screen 1302.

[0318] The display appliance 1300 comprises a capacitive detection device according to the invention, which can be any one of the detection devices of FIG. 3, 4, 5, 7, 8a, 8b, 9a or 9b.

[0319] In FIG. 13, the capacitive detection device is partially represented. Thus, only the polarization module 306, measurement electrodes 302 and the conductor 308 can be seen in FIG. 13.

[0320] The measurement electrodes 302 are placed on the frame of the display screen 1302, for example at the rate of one measurement electrode 302 per side.

[0321] The polarization module 306 is placed around the support strut 1306, and around the electric power supply 1304 and data 1305 cables. Thus, all of the electrical conductors which pass through the polarization module 306, as well as all the electrical conductors which are in contact with them, are polarized at the guard potential V.sub.g, downstream of the polarization module 306.

[0322] In particular, all the portion of the display device which is located downstream of the polarization module 306 is polarized at the guard potential V.sub.g, without any particular modification.

[0323] Of course, the polarization module can, according to an alternative, constitute a base on which the display device 1300 is placed, similarly to that which is described with reference to the robotized arm of FIG. 11 or 12.

[0324] In all the examples described, the or each measurement electrode is formed by an additional electrode mounted on the appliance.

[0325] According to alternatives that are not represented, at least one measurement electrode can be formed by a constituent portion of the appliance, or the whole appliance. For example in the case of a robotized arm, at least one measurement electrode can be formed by a trim element of the robotized arm, a segment of the robotized arm, all of the robotized arm, etc. In the context of a display device, at least one measurement electrode can be formed, for example, by an electrically conductive frame of the display screen, or the whole display screen.

[0326] Of course, the invention is not limited to the examples detailed above.