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US3671913A Expired / Lapsed US ⏱️ 0.0 years remaining

Aging-proof humidity sensing element and method for the production thereof

Assignee: Saginomiya Seisakusho Inc
•
Filing: 1970-03-18
•
Granted: 1972-06-20
•
Expires: 1990-03-18
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Abstract

Abstract A humidity sensing element comprises an insulating base plate provided with gold electrodes and a film or layer metal oxide particles or a mixture of metal oxide particles and carbon particles. The micro-gaps between said particles are filled up with a hydrophilic high polymer, thereby minimizing the deterioration by aging. The humidity sensing element can be produced by a method which comprises forming a film made of metal oxide particles or a mixture of metal oxide particles and carbon particles on an insulating base plate provided with gold electrodes, immediately whereupon said film is impregnated with a solution of a hydrophilic high polymer in a water-miscible volatile solvent and subsequently volatilizing off said solvent. The thus produced humidity sensing element shows a substantially constant electric resistance at a given humidity even with the passage of a long period of time, thereby enabling a hydrometer capable of exactly indicating humidity with high durability to be provided.

Inventors

  • 👤 Shigeo Mamiya
  • 👤 Ryoichiro Yajima

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-23 19:47
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 24 words
A humidity sensing element as claimed in claim 1 in which said layer has a thickness in the range of 5-10 X 10 3mm.
Claim 2
Dependent Claim 24 words
A humidity sensing element as claimed in claim 1, in which the weight ratio of said high polymer to said particles is about 1:2.
Claim 3
Dependent Claim 25 words
A humidity sensing element as claimed in claim 1, in which said hydrophilic high polymer is disposed substantially entirely in the micro-gaps between said particles.
Claim 4
Dependent Claim 26 words
A humidity sensing element as claimed in claim 1, wherein said hydrophilic high polymer is selected from the group consisting of polyvinyl acetate and cellulose acetate.
Claim 5
Dependent Claim 21 words
A humidity sensing element as claimed in claim 1, wherein said gold electrodes comprises a pair of comb-shaped symmetrical gold electrodes.
Claim 6
Independent Claim 167 words
A method for preparing a humidity sensing element, which comprises the steps of: applying a suspension of particles in water onto an insulating base plate having gold electrodes thereon to form a thin layer of particles thereon, said particles being selected from the group consisting of (1) gamma -ferric oxide particles and (2) a mixture of gamma -ferric oxide particles and up to 40 per cent by weight of carbon particles based on the weight of gamma -ferric oxide particles, said particles being of a size in the range of about 10 5 to 10 7cm, immediately thereafter and while said layer still contains said water, applying onto said layer a solution containing about 1 to 5 per cent by weight of a hydrophilic high polymer dissolved in a water-miscible volatile solvent so that the hydrophilic high polymer enters the micro-gaps between the particles, and then volatilizing the water and solvent to obtain a humidity sensing element in which said micro-gaps are filled with said high polymer.
Claim 7
Dependent Claim 38 words
A method as claimed in claim 7, in which said high polymer is selected from the group consisting of polyvinyl acetate and cellulose acetate and said solvent is selected from the group consisting of acetone and ethyl acetate.
Claim 8
Dependent Claim 18 words
A method as claimed in claim 8, in which said solution is applied to said layer by spraying.
Claim 9
Dependent Claim 25 words
A method as claimed in claim 8, in which said solution is applied by dipping said base plate having the layer thereon into said solution.
Claim 10
Dependent Claim 64 words
A method as claimed in claim 8, in which said suspension contains in the range of about 1 to 4 per cent by weight of said particles and in which said plate is at a temperature in the range of about 40* to 60* C., when the suspension is applied thereto and said plate is at room temperature when said solution is applied thereto.

References Cited (Backward Citations)

US2543384A Cited
GB795031A Cited
US3022667A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1975-06-20 1975-12-20 1976-06-20 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1979-06-20 1979-12-20 1980-06-20 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1983-06-20 1983-12-20 1984-06-20 $7700.00 Window Closed / Lapsed

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