EP3552003A1 - Capteur capacitif de gouttelettes d'eau et compteur de réseau public contenant celui-ci - Google Patents

Capteur capacitif de gouttelettes d'eau et compteur de réseau public contenant celui-ci

Info

Publication number
EP3552003A1
EP3552003A1 EP16819471.0A EP16819471A EP3552003A1 EP 3552003 A1 EP3552003 A1 EP 3552003A1 EP 16819471 A EP16819471 A EP 16819471A EP 3552003 A1 EP3552003 A1 EP 3552003A1
Authority
EP
European Patent Office
Prior art keywords
electrode
sensor
water droplet
printed circuit
circuit board
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Withdrawn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
EP16819471.0A
Other languages
German (de)
English (en)
Inventor
Lars Jespersen
Henrik Bork STEFFENSEN
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.)
Danfoss AS
Original Assignee
Danfoss AS
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 Danfoss AS filed Critical Danfoss AS
Publication of EP3552003A1 publication Critical patent/EP3552003A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity

Definitions

  • the invention relates to a capacitive water droplet sensor comprising a printed circuit board, wherein the sensor comprises a first electrode and a second electrode both arranged in a sensor layer of the printed circuit board, wherein the first electrode and the second electrode form a
  • the invention furthermore relates to a
  • the water absorbing layer is a nonstandard component which complicates the construction and increases the cost of the PCB.
  • Task of the invention is therefore to provide a less complicated alternative for the known capacitive relative humidity sensors.
  • the above task is solved in that the first electrode and the second electrode are fully covered to an outside of the printed circuit board by an electrically insulating, water-non-absorbent material.
  • the solution therefore dispenses with a water absorbing layer arranged adjacent to the capacitor.
  • This has the disadvantage that the sensor is less sensitive than the known relative humidity sensors that are able to detect elevated levels of humidity in the air surrounding the PCB.
  • the present invention however will only detect a significant change in capacity if water droplets condense on the surface of the water-non-absorbent material covering the first electrode and the second electrode. At the same time, it becomes much easier and less expensive to incorporate the capacitive sensor into the PCB.
  • the capacitive sensor may comprise further circuit elements. In the sensor the capacitor comprising the first electrode and the second electrode may be combined with further circuit components such as one or more resistors and/or transistors.
  • the capacitive sensor may comprise an oscillator circuit.
  • a change in capacity of the capacitor relative to a reference value of the capacity may be detected. This is because the capacity of the capacitor will change if water is adsorbed on the surface of the water-non-absorbent material.
  • the water-non-absorbent material is a resin laminate, a plastic or a solder stop mask.
  • a resin laminate, certain plastics and a solder stop mask are standard materials of a PCB and can be chosen to be electrically insulating and water-non-absorbent.
  • the resin laminate may be a fibre or fabric reinforced laminate.
  • the resin laminate may, for example, be a glass-fibre reinforced laminate, e.g. FR-4.
  • the plastic may be a suitable electrically insulating, water-non-absorbent plastic, e.g. Teflon.
  • the electrically insulating water-non-absorbent material may, however, also be any other suitable base material of a PCB-layer like aluminum oxide ceramics or co-fired ceramics.
  • the water-non-absorbent material is a resin laminate or a plastic that is part of a layer of the printed circuit board adjacent to the sensor layer.
  • the first electrode and the second electrode are covered by a resin laminate or a plastic that is part of an adjacent layer of the PCB.
  • the capacitor may then be formed in the sensor layer by etching the first and second electrode out of a metal layer (e.g. a copper layer), forming the sensor layer, e.g. with a thermoset resin, and then forming a further layer of the PCB on top of the sensor layer.
  • the area of the layer that is covering the capacitor should only comprise the electrically insulating, water-non-absorbent material, i.e.
  • the printed circuit board comprises at least three layers, wherein the sensor layer is arranged adjacent to at least one of the two surface layers. This embodiment ensures that the capacitor formed by the first electrode and the second electrode is arranged sufficiently close to a surface of the printed circuit board such that the adsorption of water droplets on the surface of the printed circuit board will have a sufficiently large effect on the capacity of the capacitor.
  • the sensor layer is one of the outermost layers of the printed circuit board and the water-non-absorbent material is a solder stop mask covering the sensor layer.
  • a solder stop mask is not part of a layer of the printed circuit board.
  • the first electrode and the second electrode are etched out of a metal layer (e.g. a copper layer).
  • the capacitor can be formed along the remaining circuitry arranged in the sensor layer.
  • sensor layer denotes the layer in which at least the first electrode and the second electrode are arranged. This sensor layer may of course comprise numerous other circuitry elements of the printed circuit board.
  • the first electrode merges into the remainder of the metal layer.
  • This embodiment simplifies the construction of the printed circuit board since the capacitor may be placed in any "unused" area of the sensor layer by etching out the space between the first electrode and the second electrode. The remainder of the unused area may then be left in the sensor layer such that the first electrode merges into the remainder of the metal layer.
  • the metal layer may be a copper layer.
  • the water-non-absorbent material has a rough surface to increase the adsorption of water droplets.
  • a rough surface increases the adsorption of water droplets due to a larger number of microscopic troughs and notches. These microdefects locally lower the energy necessary for adsorption.
  • the distance between the first electrode and the second electrode is substantially constant.
  • the first electrode and the second electrode form a bifilar spiral pattern.
  • a bifilar spiral pattern allows to use the area provided for the capacitor effectively.
  • the first electrode and the second electrode may form a comb pattern.
  • the comb pattern may be single-sided or dual-sided.
  • the first electrode and the second electrode form a circular bifilar spiral pattern, an oval bifilar spiral pattern or a rectangular bifilar spiral pattern.
  • the sensor comprises an oscillator circuit, wherein the oscillator circuit comprises the capacitor of the first electrode and the second electrode, a resistor as well as a NAND-Gate.
  • the sensor does not necessarily comprise these components since it suffices to be able to detect a change in capacity of the capacitor.
  • the utility meter is a flow meter.
  • the utility meter is a heat meter.
  • Fig. 1 shows a schematic circuit diagram of an oscillator circuit of the capacitive water droplet sensor according to the invention
  • Fig. 2a-2c show several examples of patterns of the capacitor according to the invention
  • Fig. 3a-3c show the embodiments according to Fig. 2a-2c with the area covered by the water-non-absorbent material shown in addition,
  • Fig. 4a-4c show embodiments of the capacitor covered with a solder stop mask
  • Fig. 5 shows an embodiment of the capacitor, wherein the first
  • Fig. 1 shows a schematic layout of an oscillator circuit of a capacitive water droplet sensor 1 according to the invention.
  • the capacitive water droplet sensor 1 is simply denoted as the sensor 1 .
  • the sensor 1 comprises a capacitor 2 arranged in a sensor layer of a printed circuit board.
  • the sensor 1 furthermore comprises a resistor 3 as well as a NAND-Gate 4.
  • the oscillator circuit is an RC oscillator circuit adopting a Schmitt-trigger as shown, whose oscillator is enabled by a high signal on the ENABLE input terminal 5.
  • the oscillation frequency is determined by the resistance R of the resistor 3, the capacitance of the capacitor 2 as well as the voltage thresholds of the Schmitt-trigger input NAND-gate 4.
  • the oscillation frequency of the oscillatory circuit depends on the stray electric field originating from the capacitor which is influenced by condensed water droplets in the vicinity of the capacitor, for example, droplets that have been adsorbed on the printed circuit board. These water droplets increase the capacitance of the capacitor whereby the oscillation frequency of the oscillator circuit is altered.
  • Fig. 2a to 2c show three embodiments of a capacitor 2 of the sensor 1 .
  • the capacitor 2 comprises a first electrode 6 and a second electrode 7.
  • Fig. 2a, 2b and 2c show embodiments in which the first electrode 6 and the second electrode 7 form bifilar spiral patterns.
  • the first electrode 6 and the second electrode 7 form a rectangular bifilar spiral pattern.
  • the first electrode 6 and the second electrode 7 form an oval bifilar spiral pattern.
  • Fig. 2c the first electrode 6 and the second electrode 7 form a circular bifilar spiral pattern.
  • Fig. 3a to 3c correspond to the electrode shapes of Fig. 2a to 2c.
  • Fig. 3a to 3c show schematically an area where an electrically insulating, water-non-absorbent material 8 is arranged which fully covers the first electrode 6 and the second electrode 7 to an outside of the printed circuit board.
  • the area covered by the water-non-absorbent material 8 may be larger than the area occupied by the first electrode 6 and the second electrode 7.
  • the water-non-absorbent material 8 may, for example, be epoxy, in particular glass epoxy, or a solder stop mask.
  • Fig. 4a to 4c show the same electrode patterns of Fig. 2a to 3c but in this case the water-non-absorbent material 8 is a solder stop mask.
  • the sensor layer in which the capacitor 2 is arranged is preferably one of the outermost layers of the printed circuit board. If the water-non- absorbent material 8 is an epoxy (for example part of a layer of the printed circuit board adjacent to the sensor layer) then the sensor layer is preferably a layer adjacent to one of the outermost layers of the printed circuit board.
  • Fig. 5 shows an alternative pattern of the first electrode 6 and the second electrode 7.
  • the first electrode 6 merges into the remainder of a metal layer 9.
  • This embodiment is slightly less complicated to manufacture than the previous embodiments since an "unused" area of the sensor layer may be provided with the first electrode 6 and the second electrode 7 by simply etching the space between the two electrodes 6, 7 away and leaving the rest of the metal layer 9 in the unused area.
  • the first electrode 6 could also merge into a remainder of a metal layer 9 with the shapes of the first electrode 6 and the second electrode 7 shown, for example, in Fig. 2b and 2c or any other shape of the electrodes 6, 7.
  • the first electrode 6 and the second electrode 7 may also form alternative shapes from the ones shown in the figures, for example, a single-sided comb pattern or dual-sided comb pattern. In this case, the first electrode 6 may substantially encompass the second electrode 7.
  • the capacitive water droplet sensor 1 may be part of a utility meter used in an application with an increased risk of high humidity entering the utility meter.
  • the utility meter may be a flow meter or a heat meter both of which may be arranged adjacent to a fluid line or a fluid tank.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un capteur capacitif de gouttelettes d'eau (1) comprenant une carte à circuit imprimé. Le capteur (1) comprend une première électrode (6) et une deuxième électrode (7), toutes deux disposées dans une couche de capteur de la carte à circuit imprimé. La première électrode (6) et la deuxième électrode (7) forment un condensateur (2) du capteur (1). L'invention a pour objet de produire un capteur capacitif qui est plus facile à intégrer dans une carte à circuit imprimé existante. À cet effet, la première électrode (6) et la deuxième électrode (7) sont entièrement recouvertes d'un matériau électriquement isolant, n'absorbant pas l'eau (8), par rapport à l'extérieur de la carte à circuit imprimé.
EP16819471.0A 2016-12-12 2016-12-12 Capteur capacitif de gouttelettes d'eau et compteur de réseau public contenant celui-ci Withdrawn EP3552003A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2016/080672 WO2018108242A1 (fr) 2016-12-12 2016-12-12 Capteur capacitif de gouttelettes d'eau et compteur de réseau public contenant celui-ci

Publications (1)

Publication Number Publication Date
EP3552003A1 true EP3552003A1 (fr) 2019-10-16

Family

ID=57680224

Family Applications (1)

Application Number Title Priority Date Filing Date
EP16819471.0A Withdrawn EP3552003A1 (fr) 2016-12-12 2016-12-12 Capteur capacitif de gouttelettes d'eau et compteur de réseau public contenant celui-ci

Country Status (4)

Country Link
EP (1) EP3552003A1 (fr)
CN (1) CN110036287A (fr)
EA (1) EA201991364A1 (fr)
WO (1) WO2018108242A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11581206B2 (en) * 2020-03-06 2023-02-14 Applied Materials, Inc. Capacitive sensor for chamber condition monitoring
CN111458753A (zh) * 2020-04-07 2020-07-28 安徽大学 一种全柔性同面螺旋电极接近觉传感器及其制备方法
CN112946025B (zh) * 2021-01-11 2023-04-25 中国石油天然气股份有限公司 一种基于阻容振荡的井下套管内涂层检测仪及其检测方法
KR20230132469A (ko) * 2021-01-20 2023-09-15 헨켈 아게 운트 코. 카게아아 수분 검출을 위한 가요성 센서 장치

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6842018B2 (en) * 2002-05-08 2005-01-11 Mcintosh Robert B. Planar capacitive transducer
US7461560B2 (en) * 2005-03-28 2008-12-09 Microstrain, Inc. Strain gauge with moisture barrier and self-testing circuit
DE102006030208B4 (de) * 2005-07-19 2008-05-29 Preh Gmbh Sensoranordnung zur Erfassung der Feuchte auf einer Scheibe
US8089287B2 (en) * 2007-01-10 2012-01-03 Alain Izadnegahdar Soil humidity evaluation with contact free coupling
US20090009193A1 (en) * 2007-07-06 2009-01-08 Chung Yuan Christian University Moisture-Sensitive Element with an Interdigital Capacitor and Fabrication thereof
US20100277185A1 (en) * 2009-05-01 2010-11-04 Spectrum Technologies, Inc. Soil moisture sensor
US20100307238A1 (en) * 2009-06-05 2010-12-09 The Governors Of The University Of Alberta Humidity sensor and method of manufacturing the same
US9063067B1 (en) * 2010-11-17 2015-06-23 Alvin P. Schmitt Moisture sensing devices
US9068816B2 (en) * 2011-11-22 2015-06-30 Flextronics Automotive Inc. Capacitor sensors and system and methods for non-contact object detection

Also Published As

Publication number Publication date
WO2018108242A1 (fr) 2018-06-21
EA201991364A1 (ru) 2019-11-29
CN110036287A (zh) 2019-07-19

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