US4449188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for controlling humidity
Assignee: Panasonic Holdings Corp
•
Filing: 1981-11-05
•
Granted: 1984-05-15
•
Expires: 2001-11-05
Abstract
Abstract Apparatus for controlling humidity comprises a humidity sensing circuit including a humidity sensing element the electrostatic capacitance of which varies in accordance with the ambient relative humidity, and an air-conditioning system responsive to the sensed humidity. The humidity sensing element is charged and discharged repeatedly in accordance with a pulse train signal, and a period required for the voltage across the sensing element is measured during charging by a comparison between the voltage and a reference voltage. The pulse width or the reference voltage may be changed to select a desired reference humidity. A hysteresis characteristic may be given to render the operation of the circuit stable. When an SCR is controlled by the output signal of the humidity sensing circuit, the frequency of the pulse train signal is selected to be greater than four times the frequency of the voltage applied to the SCR.
Inventors
- 👤 Takehiko Unoguchi
- 👤 Seiro Hasegawa
- 👤 Katsuyuki Fujito
- 👤 Atsushi Nishino
- 👤 Akihiko Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:47
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/223
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
268 words
Apparatus for controlling humidity, including a humidity sensing circuit for producing an output signal indicative of the ambient humidity; and means for controlling the humidity in accordance with said output signal, said humidity sensing circuit comprising: (a) a humidity sensing element, the electrostatic capacitance of which varies in accordance with the ambient relative humidity; (b) a resistor connected in series with said humidity sensing element, said series circuit of said resistor and said humidity sensing element being connected to a D. C. power source so that said humidity sensing element is charged through said resistor; (c) a pulse generator for producing an output pulse train signal; (d) a switching circuit responsive to said pulse train signal for periodically discharging charge prestored in said humidity sensing element, ON/OFF operation of said switching circuit being controlled in accordance with the width of each pulse of said pulse train signal so that said switching circuit is periodically opened for a predetermined interval to exponentially charge said humidity sensing element in such a manner that a varying voltage derived from said D. C. source is developed across said humidity sensing element, the width and the duty cycle of said each pulse being selected such that said varying voltage across said humidity sensing element rises to a predetermined voltage when said electrostatic capacitance of said humidity sensing element assumes a given value; and (e) a voltage comparator responsive to the varying voltage across said humidity sensing element and to a reference voltage for producing an output signal which indicates that the humidity sensed has a predetermined relationship with respect to a reference humidity.
Claim 2
Dependent Claim
268 words
Apparatus for controlling humidity, including a humidity sensing circuit for producing an output signal indicative of the ambient humidity; and means for controlling the humidity in accordance with said output signal, said humidity sensing circuit comprising: (a) a humidity sensing element, the electrostatic capacitance of which varies in accordance with the ambient relative humidity; (b) a resistor connected in series with said humidity sensing element, said series circuit of said resistor and said humidity sensing element being connected to a D. C. power source so that said humidity sensing element is charged through said resistor; (c) a pulse generator for producing an output pulse train signal; (d) a switching circuit responsive to said pulse train signal for periodically discharging charge prestored in said humidity sensing element, ON/OFF operation of said switching circuit being controlled in accordance with the width of each pulse of said pulse train signal so that said switching circuit is periodically opened for a predetermined interval to exponentially charge said humidity sensing element in such a manner that a varying voltage derived from said D. C. source is developed across said humidity sensing element, the width and the duty cycle of said each pulse being selected such that said varying voltage across said humidity sensing element rises to a predetermined voltage when said electrostatic capacitance of said humidity sensing element assumes a given value; and (e) a voltage comparator responsive to the varying voltage across said humidity sensing element and to a reference voltage for producing an output signal which indicates that the humidity sensed has a predetermined relationship with respect to a reference humidity.
Claim 3
Dependent Claim
28 words
Apparatus for controlling humidity as claimed in claim 1, wherein said reference voltage is produced by a voltage divider interposed between said D. C. power source and ground.
Claim 4
Dependent Claim
28 words
Apparatus for controlling humidity as claimed in claim 1, wherein said switching circuit comprises a transistor the emitter-collector path of which is connected across said humidity sensing element.
Claim 5
Dependent Claim
26 words
Apparatus for controlling humidity as claimed in claim 1, wherein said pulse generator comprises means for adjusting the pulse width of said output pulse train signal.
Claim 6
Dependent Claim
21 words
Apparatus for controlling humidity as claimed in claim 4, wherein said means for adjusting the pulse width is a variable resistor.
Claim 7
Dependent Claim
40 words
Apparatus for controlling humidity as claimed in claim 1, wherein said means for controlling humidity comprises an SCR and a relay connected in series, the gate electrode of said SCR being responsive to the output signal of said voltage comparator.
Claim 8
Dependent Claim
45 words
Apparatus for controlling humidity as claimed in claim 6, further comprising a resistor interposed between said output terminal of said voltage comparator and said gate electrode, another resistor interposed between said gate electrode and ground, and a capacitor connected across the winding of said relay.
Claim 9
Dependent Claim
30 words
Apparatus for controlling humidity as claimed in claim 6 or 7, wherein said series circuit of said relay and said SCR is supplied with a half-wave or full-wave rectified voltage.
Claim 10
Dependent Claim
23 words
Apparatus for controlling humidity as claimed in claim 1, further comprising a voltage-hold circuit responsive to the output signal of said voltage comparator.
Claim 11
Dependent Claim
35 words
Apparatus for controlling humidity as claimed in claim 9, further comprising an inverter responsive to the output signal of said voltage-hold circuit, and a resistor interposed between the input terminal of said inverter and ground.
Claim 12
Dependent Claim
32 words
Apparatus for controlling humidity as claimed in claim 10, further comprising a feedback resistor interposed between the output terminal of said inverter and one of the input terminals of said voltage comparator.
Claim 13
Dependent Claim
48 words
Apparatus for controlling humidity as claimed in claim 10, further comprising a feedback circuit which includes a series circuit of a second inverter, a resistor and a diode, said feedback circuit being interposed between the output terminal of said first mentioned inverter and to said humidity sensing element.
Claim 14
Dependent Claim
51 words
Apparatus for controlling humidity as claimed in claim 10, wherein said pulse generator comprises a series circuit of a variable resistor and a fixed resistor for adjusting the pulse width, and a switching circuit connected across said fixed resistor, said switching circuit being responsive to the output signal of said inverter.
Claim 15
Dependent Claim
82 words
Apparatus for controlling humidity as claimed in claim 1, wherein said pulse generator comprises first, second and third inverters connected in series, a series circuit of a resistor and a capacitor connected between an input terminal of said first inverter and an output terminal of said second inverter, and a series circuit of a variable resistor and a fixed resistor connected between an output terminal of said first inverter and a junction connecting said resistor and capacitor which are connected in series.
Claim 16
Dependent Claim
32 words
Apparatus for controlling humidity as claimed in claim 2, wherein said voltage divider comprises a multi-contact switch and a plurality of fixed resistors respectively connected to the contacts of said multi-contact switch.
Claim 17
Dependent Claim
39 words
Apparatus for controlling humidity as claimed in claim 6, wherein said pulse generator is so constructed as to generate a pulse train signal having a frequency greater than four times the frequency of the voltage applied to said SCR.
Claim 18
Independent Claim
168 words
A method of controlling humidity, comprising the steps of sensing ambient relative humidity by exposing to an environment to be humidity controlled a humidity sensing element, an electrostatic capacitance of which varies in accordance with ambient relative humidity, charging by a DC voltage the electrostatic capacitance of the humidity sensing element in accordance with a pulse train signal, the width and duty cycle of said pulse train signal being selected such that a varying voltage across the humidity sensing element derived from the DC source rises to a predetermined voltage when the electrostatic capacitance of the humidity sensing element assumes a given value, comparing the voltage across the humidity sensing element with a reference voltage to detect an interval required for charging the humidity sensing element so that the voltage across the humidity sensing element equals the reference voltage, changing the pulse width of the pulse train signal for setting a reference humidity and applying the signal developed by the humidity sensing circuit to a humidity control means.
Claim 19
Independent Claim
168 words
A method of controlling humidity, comprising the steps of sensing ambient relative humidity by exposing to an environment to be humidity controlled a humidity sensing element, an electrostatic capacitance of which varies in accordance with ambient relative humidity, charging by a DC voltage the electrostatic capacitance of the humidity sensing element in accordance with a pulse train signal, the width and duty cycle of said pulse train signal being selected such that a varying voltage across the humidity sensing element derived from the DC source rises to a predetermined voltage when the electrostatic capacitance of the humidity sensing element assumes a given value, comparing the voltage across the humidity sensing element with a reference voltage to detect an interval required for charging the humidity sensing element so that the voltage across the humidity sensing element equals the reference voltage, changing the pulse width of the pulse train signal for setting a reference humidity and applying the signal developed by the humidity sensing circuit to a humidity control means.
Claim 20
Independent Claim
160 words
A method of controlling humidity, comprising the steps of exposing to a region to be humidity controlled a humidity sensing element having an electrostatic capacitance that varies in accordance with ambient relative humidity, charging by a DC voltage the humidity sensing element and repeatedly discharging the element in accordance with a pulse train signal, the width and duty cycle of said pulse train signal being selected such that a varying voltage across the humidity sensing element derived from the DC source rises to a predetermined voltage when the electrostatic capacitance of the element assumes a given value, comparing the voltage across the humidity sensing element with a reference voltage to detect an interval required for charging the humidity sensing element so that the voltage across the humidity sensing element equals the reference voltage, changing the reference voltage for setting a reference humidity and applying a humidity sensing element electrostatic capacitance dependent output signal to a means for controlling ambient humidity.
Claim 21
Independent Claim
160 words
A method of controlling humidity, comprising the steps of exposing to a region to be humidity controlled a humidity sensing element having an electrostatic capacitance that varies in accordance with ambient relative humidity, charging by a DC voltage the humidity sensing element and repeatedly discharging the element in accordance with a pulse train signal, the width and duty cycle of said pulse train signal being selected such that a varying voltage across the humidity sensing element derived from the DC source rises to a predetermined voltage when the electrostatic capacitance of the element assumes a given value, comparing the voltage across the humidity sensing element with a reference voltage to detect an interval required for charging the humidity sensing element so that the voltage across the humidity sensing element equals the reference voltage, changing the reference voltage for setting a reference humidity and applying a humidity sensing element electrostatic capacitance dependent output signal to a means for controlling ambient humidity.
References Cited (Backward Citations)
US3547348A
Cited
US3689907A
Cited
US3710244A
Cited
US3957200A
Cited
US4092635A
Cited
GB1575167A
Cited
US4156268A
Cited
US4161660A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |