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WO2018141395A1 - Printed circuit board with an improved condensation sensor circuit application - Google Patents

Printed circuit board with an improved condensation sensor circuit application Download PDF

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Publication number
WO2018141395A1
WO2018141395A1 PCT/EP2017/052315 EP2017052315W WO2018141395A1 WO 2018141395 A1 WO2018141395 A1 WO 2018141395A1 EP 2017052315 W EP2017052315 W EP 2017052315W WO 2018141395 A1 WO2018141395 A1 WO 2018141395A1
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WO
WIPO (PCT)
Prior art keywords
circuit board
printed circuit
square wave
microcontroller
low pass
Prior art date
Application number
PCT/EP2017/052315
Other languages
French (fr)
Inventor
Mehmet Cahit OZDEMIR
Emrah SALMAN
Reyhan Turk
Original Assignee
Arcelik Anonim Sirketi
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 Arcelik Anonim Sirketi filed Critical Arcelik Anonim Sirketi
Priority to PCT/EP2017/052315 priority Critical patent/WO2018141395A1/en
Priority to TR2018/01001A priority patent/TR201801001A2/en
Publication of WO2018141395A1 publication Critical patent/WO2018141395A1/en

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    • 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
    • G01N27/228—Circuits therefor
    • 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
    • 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
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/045—Circuits
    • 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
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material

Definitions

  • the present invention relates to a condensation sensing circuit disposed on a printed circuit board (PCB).
  • PCB printed circuit board
  • condensation i.e. the change of the physical state of matter from gas phase into liquid phase, occurs in cases where electrical household appliances are needed to be stored in storage sites where temperature is relatively low with relatively higher humidity and from where they are taken to be installed in consumers’ homes with normal temperature and humidity ranges.
  • electrical household appliances such as laundry machines (washing and/or drying machines), dishwashers, refrigerators or other small domestic appliances.
  • amount of condensation on the printed circuit board surfaces varies in dependence with the humidity of the installation environment where temperature change is in question. It is to be noted that more condensation is generated in the vicinity of components with more thermal capacitance, such as heat sinks, large capacitors etc.). Condensed water can typically cause many problems such as DC bus short circuits, inverter short circuits or microcontroller pin short circuits.
  • US20100277185 discloses a soil moisture probe including a capacitance-type probe and a detection circuit.
  • the probe includes two spaced electrodes on the same side of a printed circuit board.
  • the electrodes are placed on an inner layer of a multi-layer PCB and the detection circuit may be placed on an outer layer.
  • the PCB also includes a ground plane.
  • the detection circuit generates a saw-tooth or triangular wave which is converted to a DC voltage representative of the moisture content of a soil sample into which the probe is inserted.
  • the unique circuit uses the capacitance of the probe as part of a low-pass filter that distorts an oscillator-generated square wave into a saw-tooth or triangular wave.
  • a resistance component of the low-pass filter is adjustable, allowing tuning of the probe and the circuit.
  • WO0025120 disclosing a capacitive moisture sensor in which the insulator arranged between two electrodes is comprised of polyarylimide, said material having dielectric properties which are dependent on moisture content.
  • the present invention provides a condensation sensing circuit by which problems caused by condensed water, such as DC bus short circuit, inverter short circuits or microcontroller pin short circuits can be more practically detected and prevented.
  • Primary object of the present invention is to detect circuit malfunctions originating from humidity by means of a condensation sensing circuit as defined in Claim 1 and subsequent Claims.
  • the present invention proposes a printed circuit board with a condensation sensing element having conductors in the form of microstrip lines.
  • a square wave voltage signal is fed into a phase shifting circuit stage having said condensation sensing element.
  • a low pass filter consisting of said phase-shifting circuit provides that the frequency of the output signal of the low pass filter is changed with respect to the signal inputted thereto by said condensation sensing element whose time constant is variable in dependence with ambient moisture.
  • phase shifting stage consists of an RC low pass filter also having said condensation sensing element and the output of the RC low pass filter is monitored by the microcontroller to determine whether it remains as a constant voltage or changes to square wave form signal, as indicative of the ambient moisture.
  • Fig. 1 demonstrates a general block diagram of the condensation sensing circuit with components according to a first embodiment of the present invention.
  • Fig. 2 demonstrates a general block diagram of the condensation sensing circuit with components according to a second embodiment of the present invention.
  • the present invention proposes a condensation sensing circuit (8) with an interdigital (or interdigitated) capacitor element conventionally with microstrip lines.
  • the interdigital capacitor has an interdigital electrode pattern formed on a semiconductor substrate.
  • the interdigital capacitor typically comprises a pair of electrodes horizontally arrangeable on the semiconductor substrate.
  • a conventional configuration is for instance known from the publication US4522060A.
  • Condensation may occur in cases where electrical household appliances are stored in storage sites where temperature is relatively low with relatively higher humidity and taken to consumers’ homes with normal temperature and humidity ranges. Condensation on the surfaces of printed circuit boards (PCB) in electrical household appliances such as laundry machines (washing and/or drying machines), dishwashers, refrigerators or other small domestic appliances cause problems such as DC bus short circuits, inverter short circuits or microcontroller pin short circuits.
  • PCB printed circuit boards
  • a pair of electrodes of a condensation sensing element (9) is arranged on at least one surface portion of a printed circuit board, wherein impedance between the pair of electrodes of the condensation sensing element (9) varies in response to moisture.
  • the two electrode parts can be conventionally configured in a comb structure so as to interleave each other.
  • a condensation sensing circuit (8) is provided, said circuit having a microcontroller (1) that generates a square wave signal by SPWM (Sinusoidal Pulse Width Modulation) technique.
  • the square wave signal is fed into a low pass filter (first level filter (2)) to be converted into sinusoidal form.
  • the sinusoidal signal passes through a further low-pass filter (second level filter (4)).
  • the second level filter (4) acts as a phase-shifting circuit (3) to create a phase difference as will be delineated below.
  • the frequency of the output signal (5) of the second level filter (4) and the frequency of the signal inputted to said second level filter (4) are different due to a capacitive condensation sensing element (9), whose time constant is variable in dependence with ambient moisture. Due to the variable time constant of the capacitive condensation sensing element (9), frequency components passed by the second level filter (4) will change and the frequencies of the sinusoidal voltage waves after each filter (namely, the first and second level filters (2, 4)) will be different. To this end, a comparator (9) is connected to said second level filter (4) in the manner that a comparison is performed to determine deviation between frequencies of the output signal (5) of the second level filter (4) and the signal inputted to said second level filter (4).
  • the above described condensation sensing circuit (8) can be realized in the manner that the microcontroller (1) generates a predetermined-frequency square wave (PWM), which is then fed into a phase shifting stage (3) in the form of an RC low pass filter (10) with a condensation sensing element (9). If the output of the RC low pass filter (10) is a constant voltage signal, the microcontroller (1) detects that the predetermined critical moisture threshold is exceeded. If the output is instead still in square wave form, it is detected that the moisture level is within pre-specified limits.
  • PWM predetermined-frequency square wave
  • the microcontroller (1) detects that the predetermined critical moisture threshold is exceeded. If the output is instead still in square wave form, it is detected that the moisture level is within pre-specified limits.
  • output of the RC low pass filter (10) can be connected to the interrupt pin of the microcontroller (1) to monitor change in square wave form and generate an error signal if no square wave form is detected.
  • the output of the RC low pass filter (10) can be applied to the ADC input pins of the microcontroller (1).
  • the control scheme of the condensation sensing circuit (8) performs in a dual operation (detection/non-detection) mode, i.e. it only generates a corresponding indication when the condensation level reaches a predetermined level.
  • the present invention proposes a printed circuit board having a substrate and a condensation sensing circuit (8) comprising an interdigital capacitor with an electrode pattern with at least a pair of electrodes of a condensation sensing element (9) in the form of microstrip lines on said substrate.
  • said condensation sensing circuit (8) comprises a microcontroller (1) that generates a square wave which is fed into a phase shifting stage (3) having said condensation sensing element (9).
  • said condensation sensing circuit (8) comprises a low pass filter in the form of a first level filter (2) converting said square wave signal into sinusoidal form.
  • said condensation sensing circuit (8) comprises a further low pass filter in the form of a second level filter (4) consisting of said phase-shifting circuit (3) such that frequency of output signal (5) of the second level filter (4) and frequency of the signal inputted to said second level filter (4) are different from each other.
  • the frequency of the output signal (5) of the second level filter (4) is changed with respect to the signal inputted to said second level filter (4) by said condensation sensing element (9), which is a capacitor element with variable time constant in dependence with ambient moisture,
  • a comparator (9) is connected to said second level filter (4) in the manner that a comparison is performed to determine deviation between frequencies of the output signal (5) of the second level filter (4) and the signal inputted to said second level filter (4).
  • said microcontroller (1) generates a square wave by sinusoidal pulse width modulation and the square wave signal is fed into said first level filter (2).
  • said microcontroller (1) generates a predetermined frequency square wave, which is fed into said phase shifting stage (3) consisting of an RC low pass filter (10) having said condensation sensing element (9).
  • the microcontroller (1) detects that a predetermined moisture threshold is exceeded.
  • the microcontroller (1) detects that moisture level is within pre-specified limits.
  • the output of the RC low pass filter (10) is connected to any interrupt pin of the microcontroller (1) to monitor change in square wave form and generate an error signal if no square wave form is detected.
  • the output of the RC low pass filter (10) is applied to any ADC input pin of the microcontroller (1).
  • the electrodes are configured in a comb structure so as to interleave each other.
  • the electrodes are placed in the vicinity of a heat sink or a capacitor element.
  • an electrical household appliance comprising a printed circuit board is proposed.
  • said electrical household appliance is a refrigerator, a washing machine, a dishwasher, a drying machine or a combo drying and washing machine.
  • the present invention provides a condensation sensing circuit (8) by which problems caused by condensed water, such as DC bus short circuit, inverter short circuits or microcontroller pin short circuits are detected and prevented.

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  • 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)
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  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

The present invention relates to a printed circuit board having a substrate and a condensation sensing circuit (8) comprising an interdigital capacitor with an electrode pattern with at least a pair of electrodes of a condensation sensing element (9) in the form of microstrip lines on said substrate. Said condensation sensing circuit (8) comprises a microcontroller (1 ) that generates a square wave which is fed into a phase shifting stage (3) having said condensation sensing element (9).

Description

PRINTED CIRCUIT BOARD WITH AN IMPROVED CONDENSATION SENSOR CIRCUIT APPLICATION
The present invention relates to a condensation sensing circuit disposed on a printed circuit board (PCB).
It is well-known that condensation, i.e. the change of the physical state of matter from gas phase into liquid phase, occurs in cases where electrical household appliances are needed to be stored in storage sites where temperature is relatively low with relatively higher humidity and from where they are taken to be installed in consumers’ homes with normal temperature and humidity ranges. To this end, condensation on the surfaces of printed circuit boards in electrical household appliances (such as laundry machines (washing and/or drying machines), dishwashers, refrigerators or other small domestic appliances).
Typically, amount of condensation on the printed circuit board surfaces varies in dependence with the humidity of the installation environment where temperature change is in question. It is to be noted that more condensation is generated in the vicinity of components with more thermal capacitance, such as heat sinks, large capacitors etc.). Condensed water can typically cause many problems such as DC bus short circuits, inverter short circuits or microcontroller pin short circuits.
Among others, one of the prior art disclosures in the technical field of the present invention can be referred to as US20100277185, which discloses a soil moisture probe including a capacitance-type probe and a detection circuit. The probe includes two spaced electrodes on the same side of a printed circuit board. The electrodes are placed on an inner layer of a multi-layer PCB and the detection circuit may be placed on an outer layer. The PCB also includes a ground plane. The detection circuit generates a saw-tooth or triangular wave which is converted to a DC voltage representative of the moisture content of a soil sample into which the probe is inserted. The unique circuit uses the capacitance of the probe as part of a low-pass filter that distorts an oscillator-generated square wave into a saw-tooth or triangular wave. A resistance component of the low-pass filter is adjustable, allowing tuning of the probe and the circuit.
Another prior art disclosure is referred to as WO0025120 disclosing a capacitive moisture sensor in which the insulator arranged between two electrodes is comprised of polyarylimide, said material having dielectric properties which are dependent on moisture content.
The present invention, on the other hand, provides a condensation sensing circuit by which problems caused by condensed water, such as DC bus short circuit, inverter short circuits or microcontroller pin short circuits can be more practically detected and prevented.
Primary object of the present invention is to detect circuit malfunctions originating from humidity by means of a condensation sensing circuit as defined in Claim 1 and subsequent Claims.
The present invention proposes a printed circuit board with a condensation sensing element having conductors in the form of microstrip lines. A square wave voltage signal is fed into a phase shifting circuit stage having said condensation sensing element. A low pass filter consisting of said phase-shifting circuit provides that the frequency of the output signal of the low pass filter is changed with respect to the signal inputted thereto by said condensation sensing element whose time constant is variable in dependence with ambient moisture.
Change between frequencies of the output signal of the low pass filter and the signal inputted thereto is determined by a comparator. Alternatively, said phase shifting stage consists of an RC low pass filter also having said condensation sensing element and the output of the RC low pass filter is monitored by the microcontroller to determine whether it remains as a constant voltage or changes to square wave form signal, as indicative of the ambient moisture.
Accompanying drawings are given solely for the purpose of exemplifying a printed circuit board with an improved condensation sensor circuit, whose advantages over prior art were outlined above and will be explained in brief hereinafter.
The drawings are not meant to delimit the scope of protection as identified in the claims nor should they be referred to alone in an effort to interpret the scope identified in said claims without recourse to the technical disclosure in the description of the present invention.
Fig. 1 demonstrates a general block diagram of the condensation sensing circuit with components according to a first embodiment of the present invention.
Fig. 2 demonstrates a general block diagram of the condensation sensing circuit with components according to a second embodiment of the present invention.
The following numerals being referred to are used in the detailed description of the invention:
  1. Microcontroller
  2. First level filter
  3. Phase shifting stage
  4. Second level filter
  5. Output signal
  6. Comparator
  7. Comparator output signal
  8. Condensation sensing circuit
  9. Condensation sensing element
  10. RC low pass filter
The present invention proposes a condensation sensing circuit (8) with an interdigital (or interdigitated) capacitor element conventionally with microstrip lines. The interdigital capacitor has an interdigital electrode pattern formed on a semiconductor substrate. The interdigital capacitor typically comprises a pair of electrodes horizontally arrangeable on the semiconductor substrate. A conventional configuration is for instance known from the publication US4522060A.
Condensation may occur in cases where electrical household appliances are stored in storage sites where temperature is relatively low with relatively higher humidity and taken to consumers’ homes with normal temperature and humidity ranges. Condensation on the surfaces of printed circuit boards (PCB) in electrical household appliances such as laundry machines (washing and/or drying machines), dishwashers, refrigerators or other small domestic appliances cause problems such as DC bus short circuits, inverter short circuits or microcontroller pin short circuits.
According to the present invention, a pair of electrodes of a condensation sensing element (9) is arranged on at least one surface portion of a printed circuit board, wherein impedance between the pair of electrodes of the condensation sensing element (9) varies in response to moisture. The two electrode parts can be conventionally configured in a comb structure so as to interleave each other.
In accordance with a first embodiment of the present invention, a condensation sensing circuit (8) is provided, said circuit having a microcontroller (1) that generates a square wave signal by SPWM (Sinusoidal Pulse Width Modulation) technique. The square wave signal is fed into a low pass filter (first level filter (2)) to be converted into sinusoidal form. The sinusoidal signal passes through a further low-pass filter (second level filter (4)). The second level filter (4) acts as a phase-shifting circuit (3) to create a phase difference as will be delineated below.
According to the present invention, the frequency of the output signal (5) of the second level filter (4) and the frequency of the signal inputted to said second level filter (4) are different due to a capacitive condensation sensing element (9), whose time constant is variable in dependence with ambient moisture. Due to the variable time constant of the capacitive condensation sensing element (9), frequency components passed by the second level filter (4) will change and the frequencies of the sinusoidal voltage waves after each filter (namely, the first and second level filters (2, 4)) will be different. To this end, a comparator (9) is connected to said second level filter (4) in the manner that a comparison is performed to determine deviation between frequencies of the output signal (5) of the second level filter (4) and the signal inputted to said second level filter (4).
In an alternative second embodiment of the present invention, the above described condensation sensing circuit (8) can be realized in the manner that the microcontroller (1) generates a predetermined-frequency square wave (PWM), which is then fed into a phase shifting stage (3) in the form of an RC low pass filter (10) with a condensation sensing element (9). If the output of the RC low pass filter (10) is a constant voltage signal, the microcontroller (1) detects that the predetermined critical moisture threshold is exceeded. If the output is instead still in square wave form, it is detected that the moisture level is within pre-specified limits.
Conventionally, output of the RC low pass filter (10) can be connected to the interrupt pin of the microcontroller (1) to monitor change in square wave form and generate an error signal if no square wave form is detected. Alternatively, the output of the RC low pass filter (10) can be applied to the ADC input pins of the microcontroller (1).
In accordance with the second embodiment of the present invention, the control scheme of the condensation sensing circuit (8) performs in a dual operation (detection/non-detection) mode, i.e. it only generates a corresponding indication when the condensation level reaches a predetermined level.
In a nutshell, the present invention proposes a printed circuit board having a substrate and a condensation sensing circuit (8) comprising an interdigital capacitor with an electrode pattern with at least a pair of electrodes of a condensation sensing element (9) in the form of microstrip lines on said substrate.
In one embodiment of the present invention, said condensation sensing circuit (8) comprises a microcontroller (1) that generates a square wave which is fed into a phase shifting stage (3) having said condensation sensing element (9).
In a further embodiment of the present invention, said condensation sensing circuit (8) comprises a low pass filter in the form of a first level filter (2) converting said square wave signal into sinusoidal form.
In a further embodiment of the present invention, said condensation sensing circuit (8) comprises a further low pass filter in the form of a second level filter (4) consisting of said phase-shifting circuit (3) such that frequency of output signal (5) of the second level filter (4) and frequency of the signal inputted to said second level filter (4) are different from each other.
In a further embodiment of the present invention, the frequency of the output signal (5) of the second level filter (4) is changed with respect to the signal inputted to said second level filter (4) by said condensation sensing element (9), which is a capacitor element with variable time constant in dependence with ambient moisture,
In a further embodiment of the present invention, a comparator (9) is connected to said second level filter (4) in the manner that a comparison is performed to determine deviation between frequencies of the output signal (5) of the second level filter (4) and the signal inputted to said second level filter (4).
In a further embodiment of the present invention, said microcontroller (1) generates a square wave by sinusoidal pulse width modulation and the square wave signal is fed into said first level filter (2).
In a further embodiment of the present invention, said microcontroller (1) generates a predetermined frequency square wave, which is fed into said phase shifting stage (3) consisting of an RC low pass filter (10) having said condensation sensing element (9).
In a further embodiment of the present invention, if the output of the RC low pass filter (10) is a constant voltage, the microcontroller (1) detects that a predetermined moisture threshold is exceeded.
In a further embodiment of the present invention, if the output of the RC low pass filter (10) remains in square wave form, the microcontroller (1) detects that moisture level is within pre-specified limits.
In a further embodiment of the present invention, the output of the RC low pass filter (10) is connected to any interrupt pin of the microcontroller (1) to monitor change in square wave form and generate an error signal if no square wave form is detected.
In a further embodiment of the present invention, the output of the RC low pass filter (10) is applied to any ADC input pin of the microcontroller (1).
In a further embodiment of the present invention, the electrodes are configured in a comb structure so as to interleave each other.
In a further embodiment of the present invention, the electrodes are placed in the vicinity of a heat sink or a capacitor element.
In a further embodiment of the present invention, an electrical household appliance comprising a printed circuit board is proposed.
In a further embodiment of the present invention, said electrical household appliance is a refrigerator, a washing machine, a dishwasher, a drying machine or a combo drying and washing machine.
Accordingly, the present invention provides a condensation sensing circuit (8) by which problems caused by condensed water, such as DC bus short circuit, inverter short circuits or microcontroller pin short circuits are detected and prevented.

Claims (15)

  1. A printed circuit board having a substrate and a condensation sensing circuit (8) comprising an interdigital capacitor with an electrode pattern with at least a pair of electrodes of a condensation sensing element (9) in the form of microstrip lines on said substrate, characterized in that;
    said condensation sensing circuit (8) comprises a microcontroller (1) that generates a square wave which is fed into a phase shifting stage (3) having said condensation sensing element (9).
  2. A printed circuit board as in Claim 1, characterized in that said condensation sensing circuit (8) comprises a low pass filter in the form of a first level filter (2) converting said square wave signal into sinusoidal form.
  3. A printed circuit board as in Claim 2, characterized in that said condensation sensing circuit (8) comprises a further low pass filter in the form of a second level filter (4) consisting of said phase-shifting circuit (3) such that frequency of output signal (5) of the second level filter (4) and frequency of the signal inputted to said second level filter (4) are different from each other.
  4. A printed circuit board as in Claim 3, characterized in that the frequency of the output signal (5) of the second level filter (4) is changed with respect to the signal inputted to said second level filter (4) by said condensation sensing element (9), which is a capacitor element with variable time constant in dependence with ambient moisture,
  5. A printed circuit board as in Claim 4, characterized in that a comparator (9) is connected to said second level filter (4) in the manner that a comparison is performed to determine deviation between frequencies of the output signal (5) of the second level filter (4) and the signal inputted to said second level filter (4).
  6. A printed circuit board as in Claim 2, characterized in that said microcontroller (1) generates a square wave by sinusoidal pulse width modulation and the square wave signal is fed into said first level filter (2).
  7. A printed circuit board as in Claim 1, characterized in that said microcontroller (1) generates a predetermined frequency square wave, which is fed into said phase shifting stage (3) consisting of an RC low pass filter (10) having said condensation sensing element (9).
  8. A printed circuit board as in Claim 7, characterized in that if the output of the RC low pass filter (10) is a constant voltage, the microcontroller (1) detects that a predetermined moisture threshold is exceeded.
  9. A printed circuit board as in Claim 7 or 8, characterized in that if the output of the RC low pass filter (10) remains in square wave form, the microcontroller (1) detects that moisture level is within pre-specified limits.
  10. A printed circuit board as in Claim 7, 8 or 9, characterized in that the output of the RC low pass filter (10) is connected to any interrupt pin of the microcontroller (1) to monitor change in square wave form and generate an error signal if no square wave form is detected.
  11. A printed circuit board as in Claim 7, 8 or 9, characterized in that the output of the RC low pass filter (10) is applied to any ADC input pin of the microcontroller (1).
  12. A printed circuit board as in Claim 1, characterized in that the electrodes are configured in a comb structure so as to interleave each other.
  13. A printed circuit board as in Claim 1 or 12, characterized in that the electrodes are placed in the vicinity of a heat sink or a capacitor element.
  14. An electrical household appliance comprising a printed circuit board as in any preceding Claims.
  15. An electrical household appliance as in Claim 14, characterized in that said electrical household appliance is a refrigerator, a washing machine, a dishwasher, a drying machine or a combo drying and washing machine.
PCT/EP2017/052315 2017-02-03 2017-02-03 Printed circuit board with an improved condensation sensor circuit application WO2018141395A1 (en)

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PCT/EP2017/052315 WO2018141395A1 (en) 2017-02-03 2017-02-03 Printed circuit board with an improved condensation sensor circuit application
TR2018/01001A TR201801001A2 (en) 2017-02-03 2018-01-24 Printed Circuit Board with Improved Condensate Sensor Circuit Application

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Application Number Priority Date Filing Date Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020174197A1 (en) * 2019-02-28 2020-09-03 Valeo Systemes Thermiques Humidity detection intended for a front-end motor-fan of a motor vehicle

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4522060A (en) 1982-03-24 1985-06-11 Murata Manufacturing Co., Ltd. Dry/dew/frost sensor
WO2000025120A1 (en) 1998-10-22 2000-05-04 Marco Koch Capacitive moisture sensor and a method for the production thereof
US20060192568A1 (en) * 2004-09-17 2006-08-31 Fondazione Torino Wireless Multi-frequency capacitive measurement device and a method of operating the same
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
US20110291845A1 (en) * 2010-05-27 2011-12-01 David Rice Fluid leak detection and alarm

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4522060A (en) 1982-03-24 1985-06-11 Murata Manufacturing Co., Ltd. Dry/dew/frost sensor
WO2000025120A1 (en) 1998-10-22 2000-05-04 Marco Koch Capacitive moisture sensor and a method for the production thereof
US20060192568A1 (en) * 2004-09-17 2006-08-31 Fondazione Torino Wireless Multi-frequency capacitive measurement device and a method of operating the same
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
US20110291845A1 (en) * 2010-05-27 2011-12-01 David Rice Fluid leak detection and alarm

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WO2020174197A1 (en) * 2019-02-28 2020-09-03 Valeo Systemes Thermiques Humidity detection intended for a front-end motor-fan of a motor vehicle
FR3093394A1 (en) * 2019-02-28 2020-09-04 Valeo Systemes Thermiques HUMIDITY DETECTION INTENDED FOR A MOTOR VEHICLE FRONT PANEL FAN OF A MOTOR VEHICLE

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