EP3350926A1 - Auswerteschaltung für einen kapazitiven sensor, kapazitiver sensor und aktor in einem kraftfahrzeug - Google Patents
Auswerteschaltung für einen kapazitiven sensor, kapazitiver sensor und aktor in einem kraftfahrzeugInfo
- Publication number
- EP3350926A1 EP3350926A1 EP16766276.6A EP16766276A EP3350926A1 EP 3350926 A1 EP3350926 A1 EP 3350926A1 EP 16766276 A EP16766276 A EP 16766276A EP 3350926 A1 EP3350926 A1 EP 3350926A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- capacitive sensor
- measuring
- clock
- switching
- time
- 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.)
- Ceased
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
-
- 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
Definitions
- the invention relates to an evaluation circuit for a capacitive sensor according to the preamble of patent claim 1.
- Capacitive sensors are widely used not only in automation technology, but recently also in automotive technology, where they u. a. be used as trunk, door opener, or seat occupancy recognition application.
- AT 403 213 B discloses a capacitive humidity sensor with a rectangular generator whose signal is supplied to an AND gate via two different signal paths, one signal path being straight and the other having a measuring electrode whose capacitance influences the signal shape and thereby reaching a switching threshold delayed.
- WO 2007 025 785 A1 discloses a capacitive sensor with a square-wave generator whose signal is supplied via two different signal paths to an XOR gate, wherein one signal path contains a measuring electrode and the other a reference electrode.
- DE 10 2012 106 526 AI discloses a capacitive door handle sensor for a motor vehicle with at least two electrodes with different monitoring areas, wherein one electrode acts as a reference electrode.
- DE 10 2012 224 007 AI discloses an arrangement and a method for determining the capacitance of a measuring capacitor in a detectable with an analog-to-digital converter voltage with a charge transfer device for transferring the charge of an unknown capacitance C X on a measuring capacitor C L , however, only the Comparison of a single unknown capacity C X is provided with a reference capacity C re f.
- DE 10 2014 216 998 A1 shows an evaluation circuit for a capacitive sensor with a plurality of measuring capacitances and a reference capacitance, wherein the measuring capacitances are successively compared in a predetermined time regime with the same reference capacitance.
- the object of the invention is to provide a comparison with the circuit shown in DE 10 2014 216 998 AI again cost-optimized circuit, which also has additional opportunities to detect the capacitive environmental effects.
- the object of the invention is achieved with the characterizing features of claim 1.
- the subclaims relate to the advantageous embodiment of the invention.
- the essential idea of the invention is to compare the measuring capacitances successively in a predetermined time regime with the same reference capacitance and to controllably influence the respective capacitance measurement by means of an additional auxiliary electrode.
- the reference capacitance with the input of a first switching stage and the measuring capacitances connected to the inputs of other switching stages are formed for example as NAND gates and together form a logical combination unit which is designed so that the switching time of the first switching stage the switch-on of Output determines and the switching time of a further switching stage the
- the output signal determines or that the switching time of the first switching stage determines the switch-off of an output signal and the switching time of a further switching stage determines the switch-on of the output signal.
- the output signals of the logic operation unit are the input of a
- logic operation unit generated output pulses determines the voltage of the charging capacitor.
- Time influencing unit connected, the at least one capacitor and a
- Has voltage source or is connected to a controllable voltage source.
- the time-influencing unit serves to selectively influence the delay time generated by the reference capacitance.
- the advantage of the invention is that through an auxiliary electrode which is subjected to a voltage signal substantially simultaneously with one of the measuring electrodes, a specific capacitive influencing of the measuring electrode is possible, so that in this way further spatial regions in the vicinity of the measuring electrode are capacitively evaluated can, without a separate measuring channel with additional circuit complexity for capacitance measurement of an electrode is required.
- a capacitive sensor with two sensor electrodes can be constructed, which on the one hand leads to a saving of components and, on the other hand, additional possibilities for detecting capacitively
- FIG. 1 shows an evaluation circuit according to the invention with a passive auxiliary electrode.
- FIG. 2 shows an evaluation circuit according to the invention with an active auxiliary electrode.
- Fig. 3 shows a belonging to the circuits in Fig. L and 2 ⁇ C with switching stage.
- Fig. 4 shows the timing diagram for controlling the measurement in detail.
- Fig. 5 shows the embodiment of the circuit according to the invention in a vehicle door handle.
- Fig. 6 shows a circuit with two sensor electrodes and an active auxiliary electrode.
- Fig. 1 shows an embodiment with an integrated circuit of the type 74HC132 with four switching stages (NAND gate) 41, 42, 43, 44, which form a logic operation unit 4, wherein in the idle state, the controllable gate input designated 41
- Switching stage is at the logic state "high”, so that their output, and thus also the control signal 6 assumes the logic state "low.” This has the consequence that for the duration of this state, the switching stages 42, 43 at their non-externally controllable Input are also on 'low' and thus are technically blocked, so that their outputs for the duration of this signal state to "high”, the switching stage 44 at its output the state "low occupies and the integration stage 5 is also disabled, the here charged charging capacitor Ca, which was previously charged by the switch S, which in turn is controlled by the microcontroller shown in Fig. 3 ⁇ C.
- the control input of the switching stage 41 which is not connected to the operating voltage, is connected to a time influencing unit 9, which has, in addition to R re f and C re f, two capacitors C rl and C r2 to which the auxiliary voltage sources Ui and U 2 are connected.
- the clock input Clock Ref and one of the clock inputs Clock l, Clock_2 is set to "High.”
- the clock input Clock l is currently at “High”.
- the other clock input is at "low.
- the switching stage 42 whose clock input is at "high”, is prepared for pulse generation while the other clock input, in this example the switching stage 43, remains inhibited by the logic input signal "low”.
- both the clock input “Clock Ref and the clock input of the clock inputs Clock l, Clock_2 at the same time is set to "Low".
- the signal applied to "Clock Re” reaches the input of the switching stage 41 via the low-pass Rief, Cref and triggers a positive voltage jump at its output when the threshold voltage is reached, the delay time of this voltage jump being influenced by the time-influencing unit (9). by means of which the signal at C re f can be shifted in time.
- auxiliary voltages Ui and U 2 are created. These voltages and also the three clock signals shown in FIG. 4 (Clock Ref, Clock l, Clock_2) can be generated by the previously described control unit ( ⁇ ).
- ⁇ the previously described control unit
- Output signal is thus determined by the switching time of the first switching stage 41.
- the other gate 43 where the externally accessible input is on “Tie” from the outset, thus remains signal-technically blocked.
- the time influencing unit 9 includes for selectively influencing the by the
- the time duration with which the integration stage 5 is driven depends on the electrode capacitance to be measured, which is assigned to the respectively activated clock input (Clock 1, Clock_ 2).
- the respective assigned clock input is activated in the manner described above.
- the auxiliary electrode 8 labeled EL H is located on a further terminal IN I of the control unit .mu.C of FIG. 3, is powered by a resistor (Re3) of at least one of the clock inputs Clock l, Clock_2, and is capacitive with at least one the measuring electrodes 21, 22 (EL I, EL 2) coupled.
- the auxiliary electrode 8 is fed by the clock input Clock_2 and is capacitively coupled to the measuring electrode 22 (EL_2).
- the IN IN terminal can be operated during Pulse Generation of Clock_2 in at least 2 different modes, such as high impedance and low impedance.
- the clock signal applied to Clock_2 is likewise conducted to the auxiliary electrode 8 (EL H), while in the low-resistance mode, the clock signal applied to Clock_2 is short-circuited by IN I and thus does not appear on the auxiliary electrode 8 (EL H).
- the capacitance measurement at 22 (EL 2) is influenced differently via the capacitive coupling between the electrodes 8 (EL H) and 22 (EL 2), which in the signal evaluation provides information about the mutual capacitance between the electrodes 8 (EL H) and 22 (EL 2) allowed.
- Fig. 2 shows a circuit arrangement as in Fig. 1, which differs only by the control of the auxiliary electrode 8 (EL H).
- EL H auxiliary electrode 8
- the embodiment of Fig. 2 offers the additional possibility of the control signal to Clock_3 time both the measurement at 21 v (EL_l) and the measurement at 22 (EL 2) and thus to be able to evaluate both mutual capacities. If Clock_3 is generated simultaneously with Clock 1, then the capacitance between the electrodes 8 (EL H) and 21 (EL I) is affected. If, on the other hand, Clock_3 is generated simultaneously with Clock_2, then the capacitance between the electrodes 8 (EL H) and 22 (EL 2) is influenced. In addition, the control signal for Clock_3 can be generated both in-phase and out-of-phase, which allows the double Nutzsignalhub. This embodiment requires another
- Microcontroller ⁇ C J5 of Fig. 3
- the variant of Fig. 1 or the variant of Fig. 2 may be preferred.
- FIG. 3 shows a microcontroller for controlling and evaluating the circuits indicated in the two preceding figures.
- the port PI (Clock_3) is not needed, and can be left free.
- the terminal P8 (A) is connected to a switching stage (T2), which can transmit, for example, a switching signal or a bus signal, so as to transmit the desired measurement results or Ausensekriterien using the switching stage T2 to an external control unit.
- FIG. 4 shows an example, associated pulse diagram in detail.
- This signal voltage is in the illustrated signal pattern in
- the period of time designated by "tl” is used to produce a defined initial state and must be at least as large as the sum of all delay times, which may have an influence on the electrical potential of the relevant capacities, thus ensuring a reproducible flow of the measurement.
- 5 shows a constructive embodiment in the door handle of a motor vehicle, wherein the operation of the auxiliary electrode 8 and the influence of the mutual capacitive coupling (electric field 15) between the auxiliary electrode 8 and electrode 22 is shown, which is influenced by an approximated influencing object 16.
- the constructive sensor arrangement here includes the electronics 11 including electrode system 8, 13, 22, housing 10 and other design-related elements, which also affect the mutual capacitive coupling between the auxiliary electrode and another electrode. Sensory usable, so in the sense of a detection of certain operating cases or
- FIG. 6 describes a particularly simple battery-operated exemplary embodiment, in which the logical combination unit 4 consists of only two NAND gates 41, 43. At the input of the first switching stage 41, the reference capacitance is 1. The function of the other switching stages, at whose inputs the electrodes 21, 22 are connected, is here from the gate 43rd
- the circuit includes two sensor electrodes 21, 22 and an auxiliary electrode 8, which is actively acted upon by an auxiliary signal (Clock_3).
- This circuit operates in relation to the circuits of FIG. 1 or FIG. 2 in reverse sequence of events, so that in this arrangement the switch-on time of the output signal 7 of the logical combination unit 4 is not determined by the switching time of the first switching stage 41, but by the switching points of the further switching stages 43 , Of the
- Switch-off time of the output signal 7 of the logical combination unit 41, 43 is not determined by the switching point of another switching stage 43, but vice versa from the switching point of the first switching stage 41.
- the charging capacitor Ca at the output of the integration device 5 is not discharged, but charged.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electronic Switches (AREA)
- Lock And Its Accessories (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102015217575.8A DE102015217575B3 (de) | 2015-09-15 | 2015-09-15 | Auswerteschaltung für einen kapazitiven Sensor, kapazitiver Sensor und Aktor in einem Kraftfahrzeug |
PCT/EP2016/071609 WO2017046111A1 (de) | 2015-09-15 | 2016-09-14 | Auswerteschaltung für einen kapazitiven sensor, kapazitiver sensor und aktor in einem kraftfahrzeug |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3350926A1 true EP3350926A1 (de) | 2018-07-25 |
Family
ID=56889859
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16766276.6A Ceased EP3350926A1 (de) | 2015-09-15 | 2016-09-14 | Auswerteschaltung für einen kapazitiven sensor, kapazitiver sensor und aktor in einem kraftfahrzeug |
Country Status (4)
Country | Link |
---|---|
US (1) | US10168187B2 (de) |
EP (1) | EP3350926A1 (de) |
DE (1) | DE102015217575B3 (de) |
WO (1) | WO2017046111A1 (de) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11634937B2 (en) | 2009-08-21 | 2023-04-25 | Uusi, Llc | Vehicle assembly having a capacitive sensor |
US10954709B2 (en) * | 2009-08-21 | 2021-03-23 | Uusi, Llc | Vehicle assembly having a capacitive sensor |
DE102016215570A1 (de) * | 2016-08-19 | 2018-02-22 | Ifm Electronic Gmbh | Auswerteschaltung für einen kapazitiven Sensor, kapazitiver Sensor und Aktor in einem Kraftfahrzeug |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3740586A (en) * | 1971-12-13 | 1973-06-19 | Electro Dev Corp | Pulse width - dc converter compensating for pulse repetition rate changes |
AT403213B (de) * | 1996-03-15 | 1997-12-29 | Kaufmann Ruediger Dr | Bodenfeuchtesensor |
EP1777821B1 (de) * | 2005-08-31 | 2008-07-09 | Electrolux Home Products Corporation N.V. | Durch Berührung steuerbare kapazitive Schalteinrichtung |
EP1860776A3 (de) * | 2006-05-26 | 2010-08-11 | Fujikura Ltd. | Näherungssensor und Verfahren zur Näherungsdetektion |
DE102006035837A1 (de) * | 2006-08-01 | 2008-02-07 | Siemens Ag | Bedienelement |
DE102011053314A1 (de) | 2011-09-06 | 2013-03-07 | Huf Hülsbeck & Fürst Gmbh & Co. Kg | Kapazitive Sensoranordnung |
DE102012106526A1 (de) * | 2012-07-18 | 2014-01-23 | Huf Hülsbeck & Fürst Gmbh & Co. Kg | Handhabe mit zwei Elektroden |
DE102012224007B4 (de) * | 2012-12-20 | 2020-07-16 | Ifm Electronic Gmbh | Verfahren zur Bestimmung der Kapazität eines Messkondensators, Verfahren zum Betreiben eines kapazitiven Sensors sowie Vorrichtung zur Durchführung der beiden Verfahren |
DE102014216998B4 (de) * | 2014-08-26 | 2016-10-27 | Ifm Electronic Gmbh | Kapazitiver Sensor, die zugehörige Auswerteschaltung und Aktor in einem Kraftfahrzeug |
-
2015
- 2015-09-15 DE DE102015217575.8A patent/DE102015217575B3/de active Active
-
2016
- 2016-09-14 WO PCT/EP2016/071609 patent/WO2017046111A1/de active Application Filing
- 2016-09-14 EP EP16766276.6A patent/EP3350926A1/de not_active Ceased
- 2016-09-14 US US15/535,201 patent/US10168187B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
DE102015217575B3 (de) | 2016-09-29 |
US20180202838A1 (en) | 2018-07-19 |
WO2017046111A1 (de) | 2017-03-23 |
US10168187B2 (en) | 2019-01-01 |
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