Material monitoring device

• US 5,121,630 A
• Filed: 12/21/1990
• Issued: 06/16/1992
• Est. Priority Date: 12/21/1990
• Status: Expired due to Fees

• Current Assignee: Noel M. Calvin
• Original Assignee: Noel M. Calvin
• Inventors: Calvin, Noel M.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Bennett, G. Bradley
• Application Number:
  US07/633,031
• Time in Patent Office: 543 Days
• Field of Search: 73/73, 73/74, 73/304 C, 128/886, 340/573, 340/601, 340/602, 340/604
• US Class Current: 73/73
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825

Abstract

The present invention is directed to devices for detecting the moisture content of material such as a diaper using a change in bulk dielectric constant. More particularly, the invention relates to a moisture sensing device which provides an accurate indication of the moisture content of a material such as a diaper when merely placed in the vicinity of the diaper. In a preferred embodiment, the device is a hand-held device which can be readily transported and which can detect diaper moisture without piercing the diaper or attaching electrodes directly to the diaper.

Claims

1. A moisture sensing device for detecting moisture content of a material comprising:

a capacitance proximity sensor; and

,

an indicator responsive to an output of said capacitance proximity sensor, said capacitance proximity sensor further including;

a charge pump; and

,

an antenna formed as a single metal plate for detecting changes in the bulk dielectric constant of a material placed between said metal plate and a variable ground plane.

2. Device according to claim 1, wherein said device is a portable, hand-held device.

3. Device according to claim 1, wherein said capacitance proximity sensor further includes:

a square wave generator for providing an input to said charge pump;

an integrator and bias circuit for receiving an output from said charge pump and antenna; and

,

a peak-hold circuit for storing a maximum signal proportional to the bulk dielectric constant of a material.

4. Device according to claim 1, wherein said indicator is a liquid crystal display.

5. Device according to claim 1, wherein said indicator is a multi-colored LED display.

6. Device according to claim 1, wherein said indicator is a light generator which flashes at a rate proportional to the degree of moisture sensed.

7. Device according to claim 1, wherein said indicator is a tone generator having a tone which is adjusted in proportion to the degree of moisture detected b said sensing device.

10. Device according to claim 1, wherein said antenna is a first electrode of a capacitor for storing a voltage relative to an earth ground plane.

11. Device according to claim 3, wherein said square wave generator produces a square wave to measure change accumulated on said metal plate.

8. A portable, hand-held moisture sensing device for detecting moisture content of a material comprising:

a capacitance proximity sensor; and

,

a liquid crystal display indicator responsive to an output of said capacitance proximity sensor, said capacitance proximity sensor further including;

a charge pump;

an antenna formed as a single metal plate for detecting changes in the bulk dielectric constant between said metal plate and a variable ground plane;

a square wave generator for providing an input to said charge pump;

an integrator and bias circuit for receiving an output from said charge pump and antenna; and

,

a peak-hold circuit for storing a maximum signal proportional to the bulk dielectric constant of a material.

9. Device according to claim 8, wherein said antenna is a first electrode of a capacitor for storing a voltage relative to an earth ground plane.