EP0357733A1 - Capteur capacitif de proximite - Google Patents

Capteur capacitif de proximite

Info

Publication number
EP0357733A1
EP0357733A1 EP89903028A EP89903028A EP0357733A1 EP 0357733 A1 EP0357733 A1 EP 0357733A1 EP 89903028 A EP89903028 A EP 89903028A EP 89903028 A EP89903028 A EP 89903028A EP 0357733 A1 EP0357733 A1 EP 0357733A1
Authority
EP
European Patent Office
Prior art keywords
electrode
electrodes
generator
proximity sensor
intermediate electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89903028A
Other languages
German (de)
English (en)
Inventor
Jiri Marek
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SETEC MESSGERATE GmbH
Original Assignee
SETEC MESSGERATE GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SETEC MESSGERATE GmbH filed Critical SETEC MESSGERATE GmbH
Publication of EP0357733A1 publication Critical patent/EP0357733A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945—Proximity switches
    • H03K17/955—Proximity switches using a capacitive detector
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/96—Touch switches
    • H03K2217/9607—Capacitive touch switches
    • H03K2217/960735—Capacitive touch switches characterised by circuit details
    • H03K2217/960745—Capacitive differential; e.g. comparison with reference capacitance
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/96—Touch switches
    • H03K2217/9607—Capacitive touch switches
    • H03K2217/960755—Constructional details of capacitive touch and proximity switches
    • H03K2217/960765—Details of shielding arrangements

Definitions

  • the invention relates to a capacitive proximity sensor in which two electrodes, which are kept isolated from one another, are electrically connected to a signal generator, at least one of which is flat, the input of an amplifier being connected to one of these electrodes.
  • Such a proximity sensor has been used e.g. B. known from DE-OS 35 09 507.
  • two capacitors having a common electrode are provided, one of which is switched on in the feedback circuit of a differential amplifier, but the third electrode is kept potential-free.
  • this solution there are considerable problems in the evaluation of the signals obtained, which are also highly dependent on external conditions.
  • Such a solution would hardly be suitable as a distance sensor for a parking aid for motor vehicles.
  • proximity sensors are known in which a capacitive sensor plate forms one half of a capacitor and the second half of this capacitor is connected directly or indirectly to ground.
  • Such an arrangement which is characterized by a high degree of simplicity, has a number of disadvantages.
  • DE-OS 20 44 790 has also already proposed to connect the shielding of a supply cable from a capacitive sensor plate to a low-frequency generator, in order to partially reduce the parasitic capacitance of the cable compensate.
  • this measure only affects the supply cable and has no influence whatsoever on the basic capacitance of the sensor plates and the fastening, so that not much can be gained from this measure.
  • the aim of the invention is to reduce the basic capacitance in a proximity sensor of the type mentioned in the introduction in order to achieve a higher stability of the sensor and a greater insensitivity to it from environmental influences.
  • the output of the amplifier is connected to an intermediate electrode which is arranged between the electrodes which are constantly connected to the generator and which is arranged insulated from the other two electrodes.
  • the intermediate electrode has a surface whose size lies between that of the two other electrodes, the smallest electrode being arranged essentially centrally to the intermediate electrode and the latter projecting substantially beyond the smaller electrode , the three electrodes preferably being arranged parallel and essentially concentrically to one another.
  • a further intermediate electrode is arranged, in the area of which there is provided a reference electrode which is insulated from the latter Area is significantly smaller than that of the further intermediate electrode, the reference electrode being connected to a further output of the generator and the further intermediate electrode being connected to the output of a further amplifier connected to the reference electrode on the input side.
  • the reference capacitance can be dimensioned such that its value essentially corresponds to the value of the measuring capacitance.
  • the generator can be formed by two resonant circuits which can be influenced by the measuring or reference capacitance. Since the reference capacitance remains essentially constant or changes only as a result of changed environmental influences, the ratio of the frequencies with which the two oscillating circuits of the generator oscillate can be used to infer the value of the measuring capacitance, which, for. B. depends on the distance of the corresponding electrode from a part connected to ground.
  • a particularly simple construction of such a proximity sensor is obtained if the reference electrode is arranged in the plane of the further intermediate electrode and is preferably enclosed on all sides by the latter.
  • Such a structure can easily be produced in such a way that a conductive layer applied on an insulating substrate along the boundary of the reference electrode provided, for. B. is removed by etching.
  • FIG. 1 schematically shows an inventive proximity sensor with evaluation circuit
  • FIG. 3 schematically shows a section through the proximity sensor according to FIG. 2,
  • 5 a 'to f show various application possibilities for a proximity sensor according to the invention.
  • the output of the generator 5, the z. B. can be formed by a resonant circuit, is connected to an electrode 1 of the proximity sensor.
  • the input of an amplifier 4 is also connected to this output of the generator.
  • the generator 5 is connected to ground and thus coupled to the electrode 3, which is also connected to ground.
  • a connection via a corresponding line could also be provided. It is only essential that the generator and the electrode 3 are at the same potential.
  • Such a connection could e.g. B: also be made over the body of a vehicle.
  • this sinusoidal shape or any other signal shape eg. B. may have a triangular shape, in the embodiment according to FIG. 1, an intermediate electrode 2 is arranged, which is connected to the low-impedance output of the amplifier 4. This is also applied to this electrode 2 with a similar signal as the electrode 1, i. H. that the signals applied to the electrodes 1 and 2 have the same shape and preferably also the same amplitude.
  • the output impedance of the amplifier 4 is preferably of the order of 0.1 to 10 ohms.
  • the capacitance of the electrode 1 changes to ground, which also changes the operating point of the generator 5 and thus its output signal, e.g. B. changes in its frequency or duty cycle.
  • Fig. 4 shows the influence of the proximity sensor 1, 2, 3, which e.g. housed in a wall, or can be immersed in a liquid, approaching object 13 to the electrical field 9 forming around the proximity sensor.
  • Field 9 of intermediate electrode 2 partially shields the influence of an otherwise between electrodes 1 and 3 ⁇ forming electric field.
  • the electrical field 10 of the electrode 1 is therefore formed. This closes over a relatively large path to the electrode 3, this path being shortened more and more by the approaching object 13 and moreover causing distortions. This leads to a change in the capacitance of the electrode 1 with respect to ground.
  • a further intermediate electrode 20 is provided, in the plane of which a reference electrode 21 is arranged, which is separated from the latter by a circumferential gap 22 of the electrically conductive coating of the intermediate electrode 20.
  • the further intermediate electrode 20 encloses the reference electrode 21.
  • the reference electrode 21 is connected to a further output of the generator 5 ', to which a further amplifier 4' is also connected, the low-impedance output of which is connected to the further intermediate electrode 20.
  • the generator 5 'can essentially be formed by two resonant circuits which are connected to the electrodes 1 and 21 and the amplifiers 4, 4' via separate outputs.
  • the reference electrode 21 forms with the intermediate electrode 2 a reference capacitance C * -., which is preferably dimensioned such that it is in the order of magnitude of the measuring capacitance C x determined by the electrode 1 and ground.
  • the values of the two capacitances Cr... And Cx can be recorded in such a way that the ratio of the frequencies of the resonant circuits contained in the generator is recorded, which frequencies are influenced by the capacitances mentioned.
  • the embodiment according to FIG. 2 can also be modified in such a way that between the two intermediate electrodes 2 and 20 there is another electrode connected to ground and therefore connected to the generator 5 ', so that the reference capacitance Ci ⁇ * forms between the reference electrode 21 and the electrode connected to ground, which is arranged between the intermediate electrodes 2, 20 and which is not shown in FIG. 2.
  • the arrangement of this further electrode, which is connected to ground, is particularly advantageous in the case of generators 5 'whose outputs deliver signals with different frequencies, so that interference phenomena do not have an effect on the measurement result.
  • 5a shows an application as a distance sensor in a vehicle, the electrode 3 being formed by the body and the intermediate electrode 2 and the electrode 1 being connected to the body by means of electrically insulating holders.
  • the changes Capacitance of the electrode 1 against earth which change can be evaluated accordingly, e.g. B. to activate an optical or acoustic warning signal.
  • FIG. 5b shows an example of an application of the proximity sensor according to FIG. 1 to an elevator door.
  • the electrode 3 is formed by the metallic door frame, on the end face of which the door faces the intermediate electrode 2 and the electrode 1, each separated from one another by means of electrically insulating intermediate layers, these electrodes being connected according to FIG. 1 are.
  • a floor sensor according to FIG. 1 is constructed, the electrode 3 being formed by the earth in which the other two electrodes 1 and 2 are embedded.
  • the connection of the electrodes to the generator and the amplifier is the same as in FIG. 1. If a person approaches the floor sensor, its capacity changes, which change can be evaluated accordingly.
  • FIG. 5d shows a solution for a proximity sensor as a fuse, e.g. B. for pictures or the like.
  • the wall forms the electrode 3 and the object to be protected forms the electrode 1.
  • the intermediate electrode 2 is insulated from both. When a person or an object approaches, the capacitance of the electrode 1 changes with respect to ground, which change can be evaluated accordingly.
  • Fig. 5e shows the use of a proximity sensor according to Fig. 1 as a contactless button.
  • This consists of an electrically conductive film connected to ground, an intermediate electrode 2 arranged insulated thereon, in the plane of which an electrode 1 insulated from it is arranged, the electrodes according to FIG. 1 being connected to the generator (not shown) and an amplifier are.

Landscapes

  • Electronic Switches (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

Un capteur capacitif de proximité comprend deux électrodes mutuellement isolées électriquement connectées à un générateur de signaux et dont au moins une est plate. L'entrée d'un amplificateur est connectée à une de ces électrodes. Afin de réduire la capacité de base du capteur, la sortie de l'amplificateur (4) est connectée à une électrode intermédiaire (2) agencée entre les électrodes (1, 3) connectées de manière permanente au générateur (5) et isolée par rapport à ces deux autres électrodes (1, 3).
EP89903028A 1988-03-03 1989-03-02 Capteur capacitif de proximite Withdrawn EP0357733A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT553/88A AT393040B (de) 1988-03-03 1988-03-03 Kapazitiver naeherungsgeber
AT553/88 1988-03-03

Publications (1)

Publication Number Publication Date
EP0357733A1 true EP0357733A1 (fr) 1990-03-14

Family

ID=3493657

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89903028A Withdrawn EP0357733A1 (fr) 1988-03-03 1989-03-02 Capteur capacitif de proximite

Country Status (3)

Country Link
EP (1) EP0357733A1 (fr)
AT (1) AT393040B (fr)
WO (1) WO1989008352A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2404443A (en) * 2003-07-28 2005-02-02 Automotive Electronics Ltd Ab Capacitive proximity sensor

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GB8911274D0 (en) * 1989-05-17 1989-07-05 Moonstone Computers Ltd Proximity sensor
DE4006119A1 (de) * 1990-02-27 1991-08-29 Ines Gmbh Kapazitives wegaufnehmersystem
US5166679A (en) * 1991-06-06 1992-11-24 The United States Of America As Represented By The Administrator Of The National Aeronautics & Space Administration Driven shielding capacitive proximity sensor
US5801340A (en) * 1995-06-29 1998-09-01 Invotronics Manufacturing Proximity sensor
DE19812626A1 (de) * 1998-03-23 1999-09-30 Bayerische Motoren Werke Ag Verfahren zur kapazitiven Objekterkennung bei Fahrzeugen
FR2779889B1 (fr) * 1998-06-15 2000-08-04 Patrick Rondeau Detecteur de contact par effet capacitif
DE19836054A1 (de) 1998-08-10 2000-02-17 Bosch Gmbh Robert Meßschaltung
US6441623B1 (en) 1999-07-29 2002-08-27 Ab Automotive Electronics Ltd. Capacitive proximity sensor for automotive use
JP2002062105A (ja) * 2000-08-23 2002-02-28 Sunx Ltd ヘッド分離型センサ、静電容量式センサ及びウエハ検出装置
DE10100972A1 (de) * 2001-01-11 2002-03-07 Winkler Hans Georg Einrichtung zur Sicherung eines Objektes gegen unbefugten Zugriff
FR2823163B1 (fr) * 2001-04-04 2003-07-04 Plastic Omnium Cie Element exterieur de vehicule automobile, integrant un capteur capacitif et piece de carrosserie comportant un tel element exterieur
WO2002084875A2 (fr) * 2001-04-12 2002-10-24 Ab Automotive Electronics Ltd. Capteur capacitif
GB0109269D0 (en) * 2001-04-12 2001-05-30 Ab Automotive Electronics Ltd Capacitive sensor
JP4356570B2 (ja) * 2004-09-16 2009-11-04 沖電気工業株式会社 静電容量型距離センサ
DE102006001666A1 (de) * 2006-01-12 2007-08-16 Ident Technology Ag Verfahren und Kontrollsystem für Schliessklappen
DE102007012111B4 (de) * 2006-03-13 2015-08-06 Ident Technology Ag Anordnung zur Generierung eines elektrischen Feldes, sowie unter Einschluss derselben realisierte Sensoreinrichtung
DE202006009188U1 (de) 2006-06-12 2007-10-18 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Coburg Einklemmsensor
DE202006009189U1 (de) * 2006-06-12 2007-10-18 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Coburg Taktiler Sensor
US7521665B2 (en) 2006-07-07 2009-04-21 Leoni Ag Sensor system, sensor element, and method with a light sensor and an electrical sensor for monitoring a closing mechanism
DE202006010813U1 (de) * 2006-07-13 2007-11-22 Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Coburg Einklemmsensor sowie Auswerteschaltung
WO2008064864A2 (fr) * 2006-11-27 2008-06-05 Ident Technology Ag Système de détection de parties d'un corps par absorption d'un champ électrique proche
US7999562B2 (en) 2007-07-31 2011-08-16 Vermeer Manufacturing Company Apparatus and method of capacitively sensing operator presence for a stump cutter
US10039239B2 (en) 2007-07-31 2018-08-07 Vermeer Manufacturing Company Method and apparatus for controlling the operation of a stump cutter
US8257227B2 (en) 2007-07-31 2012-09-04 Vermeer Manufacturing Company Method and apparatus for decelerating a material reduction tool
DE102008032850B4 (de) * 2008-07-14 2010-06-24 Preh Gmbh Bedienelement mit kapazitiver Näherungssensorik
DE102008036240A1 (de) * 2008-08-02 2010-02-04 Dr.Ing.H.C.F.Porsche Aktiengesellschaft Anordnung und Verfahren zur Erfassung eines kapazitiven Objekts in einem Observationsbereich
DE102009002566A1 (de) * 2009-04-22 2010-10-28 Huf Hülsbeck & Fürst Gmbh & Co. Kg Sensorelektronik in einem Kraftfahrzeugtürgriff
DE102009059202A1 (de) * 2009-07-20 2011-02-03 Huf Hülsbeck & Fürst Gmbh & Co. Kg Sensormodul
US8638109B2 (en) * 2009-12-31 2014-01-28 Mapper Lithography Ip B.V. Capacitive sensing system with differential pairs
CZ201195A3 (cs) * 2011-02-23 2012-07-04 Befra Electronic, S. R. O. Rukojet se senzorem uchopení
DE102011078077A1 (de) 2011-06-24 2012-12-27 Ident Technology Ag Leiterplatte mit Elektrodenkonfiguration eines kapazitiven Sensors
DE102012205122B4 (de) 2012-03-29 2024-06-20 Robert Bosch Gmbh Kapazitives Ortungsgerät
DE102016106860B4 (de) * 2015-04-17 2026-04-23 Ford Global Technologies, Llc Gruppenbasierte Gleichtaktunterdrückunq von Näherunqsschalteranordnunqen
US20180136271A1 (en) * 2016-11-14 2018-05-17 Touchsensor Technologies, Llc Capacitive sensor with self-test feature

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DE2744785B2 (de) * 1977-10-05 1981-05-21 Robert 7995 Neukirch Buck Elektronischer Annäherungsschalter
DE3509507A1 (de) * 1984-03-17 1985-09-19 Sartorius GmbH, 3400 Göttingen Schaltungsanordnung fuer einen differentialkondensator-messaufnehmer

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
GB2404443A (en) * 2003-07-28 2005-02-02 Automotive Electronics Ltd Ab Capacitive proximity sensor
GB2404443B (en) * 2003-07-28 2007-08-01 Automotive Electronics Ltd Ab Capacitive sensor

Also Published As

Publication number Publication date
AT393040B (de) 1991-07-25
ATA55388A (de) 1990-12-15
WO1989008352A1 (fr) 1989-09-08

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