Humidifier

• US 4,546,916 A
• Filed: 03/01/1984
• Issued: 10/15/1985
• Est. Priority Date: 03/15/1983
• Status: Expired due to Term

• Current Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Original Assignee: Tokyo Shibaura Denki Kabushiki Kaisha
• Inventors: Tsuaki, Hajime
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US06/585,163
• Time in Patent Office: 593 Days
• Field of Search: 73/29, 73/73, 73/336.5, 324/65 R, 340/602, 338/35, 236/44 R, 236/44 E, 236/44 A, 236/44 C
• US Class Current: 236/44.00A
• CPC Class Codes: G01N 27/121 for determining moisture content, e.g. humidity, of the fluid moisture content of the tested material G01N27/048
• CPC Class Codes: G01N 27/122 Circuits particularly adapted therefor, e.g. linearising circuits
• CPC Class Codes: G05D 22/02 characterised by the use of electric means
• CPC Class Codes: Y10S 261/48 Sonic vibrators

Abstract

A humidifier for controlling ambient moisture includes a moisture sensor having a capacitor component and a resistor component which may vary in response to the ambient moisture, a pseudo AC square-wave generator for supplying a square-wave source voltage to the sensor which is the sum of two separate square-wave voltages, and a moisture detector section to which a sensor output voltage and a reference voltage electrically representing an objective moisture value are supplied. When the sensor output voltage reaches the stable potential after the transient phenomenon to be caused by the sensor capacitor component, the moisture detector section compares the stable voltage with the above reference voltage, thereby performing the moisture detection which faithfully corresponds to the sensor resistor component.

Claims

1. An apparatus for detecting ambient moisture, comprising:

moisture sensor means for outputting a sensor output signal in response to a source voltage, said output signal having a capacitor component and a resistor component which vary with changes in ambient moisture;

square-wave generator means for supplying to said sensor a square-wave source voltage which alternately varies between first and second potentials at a predetermined period thereby constituting a pseudo AC source voltage, said generator means comprising

first voltage generator means for generating a first square-wave voltage having a first amplitude, and

second voltage generator means for generating a second square-wave voltage having a second amplitude, said second square-wave voltage being added to said first square-wave voltage with one of said first and second square-wave voltages used as a reference potential so as to define said pseudo AC source voltage; and

detector means for receiving said sensor output signal and a reference voltage representative of an objective moisture value, said detector means including

timer means for indicating a stable component included in said sensor output which occurs after a transient component thereof which varies due to said sensor capacitor component, said stable component accurately corresponding to said sensor resistor component, and including

means for generating a moisture detection signal by comparing said stable component with said reference voltage.

4. The apparatus according to claim 1, wherein said detector means comprises:

first circuit means for generating said reference voltage defined as a pulsate voltage signal which is generated after said transient component of said sensor output has passed, said pulsate voltage signal being synchronized with the period of said pseudo AC source voltage and having a smaller pulse width than that of said stable component.

5. The apparatus according to claim 4, wherein said pulsate voltage signal has a pulse height which can vary in accordance with the setting of the objective moisture.

6. The apparatus according to claim 5, wherein said detector means further comprises:

second circuit means, connected to said sensor means and said first circuit means, for comparing said sensor output voltage with the pulse height of said pulsate voltage signal to output a comparison signal in response to the relative magnitude relationship between them as said detection signal.

7. The apparatus according to claim 6, wherein said first and second circuit means include a delay circuit and a comparator circuit, respectively.

8. The apparatus according to claim 1, wherein said detector means comprises:

first circuit means for generating said reference voltage defined as a pulsate voltage signal which is generated after said transient component of said sensor output, said pulsate voltage signal being synchronized with the period of said pseudo AC source voltage and having a smaller pulse width than that of said stable component.

9. The apparatus according to claim 8, wherein said pulsate voltage signal has a pulse height which can vary in accordance with the setting of the objective moisture.

10. The apparatus according to claim 9, wherein said detector means further comprises:

second circuit means, connected to said sensor means and said first circuit means, for comparing said sensor output voltage with the pulse height of said pulsate voltage signal to output a comparison signal responsive to the relative magnitude relationship between them as said detection signal.

11. The apparatus according to claim 10, wherein said first and second circuit means include a delay circuit and a comparator circuit, respectively.

2. An apparatus for controlling ambient moisture, comprising:

moisture sensor means for outputting a sensor output signal in response to a source vo1tage, said output signal having a capacitor component and a resistor component which vary with changes in the ambient moisture;

source voltage generator means for supplying to said sensor a square-wave source voltage which alternately varies between first and second potentials at a predetermined period thereby constituting a pseudo AC source voltage, said generator means comprising,

first voltage generator means for generating a first square-wave voltage having a first amplitude, and

second voltage generator means for generating a second square-wave voltage of a second amplitude, said first and seeond amplitudes being added together and with one of them used as a reference potential to produce said pseudo AC source voltage;

objective moisture value setting means for generating a reference voltage representative of an objective value of ambient moisture;

moisture detection means, connected to said sensor means and said objective moisture value setting means, for indicating a first stable voltage component included in said sensor means and which corresponds to said sensor means resistor component, said first voltage component being generated after a second transient voltage component which varies due to said sensor means capacitor component, and for comparing said first voltage component with said reference voltage to generate a comparison signal in accordance with their respective voltage magnitudes; and

moisture control means, connected to said moisture detection means, for controlling ambient moisture in response to said comparison signal.

12. The apparatus according to claim 2, wherein said moisture control means comprises:

moisture increasing means for generating foggy water in response to said comparison signal, thereby increasing the ambient moisture.

13. The apparatus according to claim 12, wherein said moisture increasing means includes:

ultrasonic transducer means for producing ultrasonic waves, thereby generating fog.

14. The apparatus according to claim 2, wherein said detection means comprises:

first circuit means for generating said reference voltage as a pulsate voltage signal which is generated after said second voltage component, said pulsate voltage signal being synchronized with the period of said pseudo AC source voltage and having a smaller pulse width than that of said first voltage component.

15. The apparatus according to claim 14, wherein said detector means further comprises:

second circuit means, connected to said sensor means and said first circuit means, for comparing said sensor output voltage with the pulse height of said pulsate voltage signal to output a detection signal in response to the relative magnitude relationship between them as said comparison signal.

3. A method for detecting ambient moisture, comprising the steps of:

generating a first square-wave voltage having a first amplitude and a second square-wave voltage having a second amplitude which is added to the first square-wave voltage so as to produce a pseudo AC square-wave source voltage having as its amplitude the sum of the first and second amplitudes, said square-wave source voltage alternately varying between first and second potentials at a predetermined period;

supplying the square-wave source voltage to a moisture sensor having an output voltage based thereon with a capacitor component and a resistor component which vary in response to the ambient moisture;

producing a reference voltage electrically representing an objective value of the ambient moisture;

specifying a first stable voltage component included in the output voltage from said sensor which is generated after a second voltage component that transiently varies due to the sensor capacitor component, the first stable voltage accurately corresponding to the sensor resistor component; and

comparing the first stable voltage component with the reference voltage to thereby accurately detect the ambient moisture.

16. The method according to claim 3, wherein said reference voltage includes:

a pulsate voltage signal which is generated after the second voltage component and which is synchronized with the period of the pseudo AC source voltage and which has a smaller pulse width than the generating time of the first voltage component.

17. The method according to claim 16, wherein said pulsate voltage signal has a pulse height which can vary in accordance with the setting of the objective moisture.

18. The method according to claim 17, further comprising the step of:

controlling the ambient moisture in accordance with the comparison of the first voltage component and the reference voltage.

19. The method according to claim 18, wherein said ambient moisture varying step comprises the step of:

generating foggy water and adding it to the ambient moisture when the first voltage component is lower than the reference voltage.