US3802268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitance humidity sensing element
Assignee: Johnson Service Co
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Filing: 1971-05-06
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Granted: 1974-04-09
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Expires: 1991-05-06
Abstract
Abstract A synthetic capacitance humidity sensing element comprising a moisture sensitive dielectric core and having electrode layers integrally bonded to opposite surfaces of the core. Each electrode layer consists of a matrix of a dielectric, moisturepermeable material, and a plurality of interconnected electrically conductive particles are dispersed within the matrix. At least one of the electrode layers has a length and width less than the corresponding dimensions of the core so that the ends and side edges of the core project beyond these of the electrode layer. A projecting mound or daub of electrically conductive material is applied to each electrode layer. In the preferred form, the humidity sensing element is bent in a generally U-shaped configuration and the ends of the element are connected to an insulating frame in a manner such that the projecting tabs of the electrically conductive material are compressed against electrical contacts on the frame which in turn are connected to terminals. Changes in relative humidity in the atmosphere provide a change in the capacitance of the element and this can be converted into a signal to indicate the relative humidity or to operate a humidity control system.
Inventors
- 👤 P Thoma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:16
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/223; G01N27/225
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
144 words
A capacitance humidity sensing element, comprising a filmlike core formed of a dielectric moisture sensitive material, an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix and having a plurality of interconnected electrically conductive particles distributed within said matrix, a first of said electrode layers having an area less than that of the core, whereby opposed portions of the periphery of the core project beyond the periphery of the first electrode layer, said element having a generally U-shape with the opposed portions of the core being located at the free ends of the U-shaped element and the free ends of the element lying in spaced generally parallel planes, and mounting means located at the opposed portions of the core for mounting the element in an insulated frame.
Claim 2
Dependent Claim
144 words
A capacitance humidity sensing element, comprising a filmlike core formed of a dielectric moisture sensitive material, an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix and having a plurality of interconnected electrically conductive particles distributed within said matrix, a first of said electrode layers having an area less than that of the core, whereby opposed portions of the periphery of the core project beyond the periphery of the first electrode layer, said element having a generally U-shape with the opposed portions of the core being located at the free ends of the U-shaped element and the free ends of the element lying in spaced generally parallel planes, and mounting means located at the opposed portions of the core for mounting the element in an insulated frame.
Claim 3
Dependent Claim
25 words
The element of claim 1, wherein the core has a generally rectangular shape and said opposed portions are located at the ends of the core.
Claim 4
Dependent Claim
24 words
The element of claim 2, wherein the side edges of the core project laTerally beyond the corresponding side edges of the first electrode layer.
Claim 5
Dependent Claim
20 words
The element of claim 3, wherein the second of said electrode layer is substantially coextensive in area with said core.
Claim 6
Dependent Claim
39 words
The element of claim 1, wherein the dielectric matrix of each electrode layer is formed of a hydrolyzable material and the outer surface of said matrix is hydrolyzed to increase its rate of response to changes in relative humidity.
Claim 7
Dependent Claim
22 words
The element of claim 1, wherein substantially the entire first electrode layer is exposed and free of attachment to said mounting means.
Claim 8
Dependent Claim
55 words
The element of claim 1, wherein the mounting means includes a pair of electrical conductors adapted to be connected in an electrical circuit, clamping means for clamping each electrode layer to one of said conductors, and projecting pressure means disposed between each electrode layer and the coresponding conductor to provide a positive electrical contact therebetween.
Claim 9
Dependent Claim
32 words
The element of claim 7, wherein the projecting pressure means comprises a mound of electrically conductive material connected to each electrode layer and extending outwardly beyond the surface of said electrode layer.
Claim 10
Dependent Claim
38 words
The element of claim 1, wherein the core is capable of absorbing at least 1 percent, based on its dry weight, of moisture when exposed to 95 percent relative humidity at 70*F for a period of 30 minutes.
Claim 11
Dependent Claim
33 words
The element of claim 1, wherein both the core and the matrix have a dielectric constant in the range of 1.1 to 10 and an electrical resistivity above 1 X 109 ohm inches.
Claim 12
Dependent Claim
16 words
The element of claim 1, wherein the core and the matrix are composed of cellulose esters.
Claim 13
Dependent Claim
133 words
A capacitance humidity sensing element assembly, comprising an element including a sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, a mounting frame connected to spaced portions of the element and including a pair of electrical conductors adapted to be connected in an electrical circuit, and clamping means for connecting each electrode layer to one of said conductors to provide a positive electrical contact therebetween, said element having a generally U-shape and the ends of the element lie in spaced generally parallel planes and are connected to said mounting frame.
Claim 14
Dependent Claim
133 words
A capacitance humidity sensing element assembly, comprising an element including a sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, a mounting frame connected to spaced portions of the element and including a pair of electrical conductors adapted to be connected in an electrical circuit, and clamping means for connecting each electrode layer to one of said conductors to provide a positive electrical contact therebetween, said element having a generally U-shape and the ends of the element lie in spaced generally parallel planes and are connected to said mounting frame.
Claim 15
Dependent Claim
75 words
The assembly of claim 12, wherein a first of said electrode layers has a length less than the length of the core, whereby the ends of the core project beyond the corresponding ends of the first electrode layer, said mounting frame being connected to the projecting ends of said core and substantially the entire surface area of said first electrode layer being exposed to the environment and being free of attachment to said mounting frame.
Claim 16
Dependent Claim
39 words
The assembly of claim 13, wherein said first electrode layer has a width less than the width of the core whereby the side edges of the core project laterally beyond the corresponding side edges of the first electrode layer.
Claim 17
Dependent Claim
26 words
The assembly of claim 14, including a strip of dielectric material bonded to each side edge of the second electrode layer, said strips being spaced apart.
Claim 18
Dependent Claim
56 words
The assembly of claim 12, wherein said mounting frame includes a central member and a pair of end members, one end of the element being clamped between said central member and one of said end members and the opposite end of the element being clamped between the other of said end members and said central member.
Claim 19
Dependent Claim
40 words
The assembly of claim 16, wherein each conductor is embedded within a frame member, one end of each conductor being exposed and clamped to the corresponding electrode layer and the opposite end of each conductor being connected to a terminal.
Claim 20
Dependent Claim
29 words
The assembly of claim 16, wherein said clamping means comprises a fastener disposed within aligned openings in said central member, said end members and the ends of said element.
Claim 21
Dependent Claim
49 words
The assembly of claim 18, wherein the fastener is hollow, said assembly also includes an outer perforated casing disposed around the element and secured to said end members of the frame, and connecting means extending through the hollow interior of said fastener for connecting the casing to the frame.
Claim 22
Dependent Claim
215 words
A capacitance synthetic humidity sensing element, comprising an elongated generally rectangular core formed of a dielectric material capable of absorbing at least 1 percent, based on its dry weight, of moisture when exposed to 95 percent relative humidity at 70*F for a period of 30 minutes, an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix and having a plurality of interconnected electrically conductive particles distributed within said matrix, a first of said electrode layers having a length less than that of the core whereby the ends of the core project beyond the corresponding ends of the first electrode layer and said first electrode layer having a width less than the width of the core whereby the side edges of the core project laterally beyond the corresponding side edges of the first electrode layer, the second layer being coextensive in width with said core, and a strip of dielectric material bonded to each side edge portion of the second electrode layer, each strip having a width greater than the space between the side edge of the core and the corresponding side edge of the first electrode layer, said strips acting to prevent side edge curling of the element.
Claim 23
Dependent Claim
215 words
A capacitance synthetic humidity sensing element, comprising an elongated generally rectangular core formed of a dielectric material capable of absorbing at least 1 percent, based on its dry weight, of moisture when exposed to 95 percent relative humidity at 70*F for a period of 30 minutes, an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix and having a plurality of interconnected electrically conductive particles distributed within said matrix, a first of said electrode layers having a length less than that of the core whereby the ends of the core project beyond the corresponding ends of the first electrode layer and said first electrode layer having a width less than the width of the core whereby the side edges of the core project laterally beyond the corresponding side edges of the first electrode layer, the second layer being coextensive in width with said core, and a strip of dielectric material bonded to each side edge portion of the second electrode layer, each strip having a width greater than the space between the side edge of the core and the corresponding side edge of the first electrode layer, said strips acting to prevent side edge curling of the element.
Claim 24
Dependent Claim
45 words
The element of claim 20, wherein the element has a generally U-shape with the ends of the element lying in substantially parallel planes, and said element includes mounting means disposed at the projecting ends of the core for mounting the element in an insulating frame.
Claim 25
Dependent Claim
29 words
The element of claim 20, and including a projection of electrically conductive material connected to each electrode layer and projecting outwardly beyond the surface of the respective electrode layer.
Claim 26
Dependent Claim
30 words
The element of claim 22, and including a coating of dielectric material disposed over said first electrode layer, the projection connected to said first electrode layer extending through said coating.
Claim 27
Dependent Claim
119 words
A capacitance synthetic humidity sensing element assembly, comprising an element including an elongated sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, said first electrode layer having a width less than the width of the core whereby the side edges of the core project laterally beyond the corresponding side edges of the first electrode layer, and a strip of dielectric material bonded to each side edge of the second electrode layer, said strips being spaced apart.
Claim 28
Dependent Claim
119 words
A capacitance synthetic humidity sensing element assembly, comprising an element including an elongated sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, said first electrode layer having a width less than the width of the core whereby the side edges of the core project laterally beyond the corresponding side edges of the first electrode layer, and a strip of dielectric material bonded to each side edge of the second electrode layer, said strips being spaced apart.
Claim 29
Dependent Claim
26 words
The assembly of claim 24, wherein each of said strips has a thickness and expansion coefficient corresponding to the thickness and expansion coefficient of the core.
Claim 30
Dependent Claim
135 words
A capacitance synthetic humidity sensing element assembly, comprising an element including a sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, a mounting frame connected to spaced portions of the element and includng a pair of eLectrical conductors adapted to be connected in an electrical circuit, clamping means for connecting each electrode layer to one of said conductors to provide a positive electrical contact therebetween, and an outer insulating casing disposed around the element and connected to the frame, said casing having openings therein whereby the element is exposed to the atmosphere.
Claim 31
Dependent Claim
135 words
A capacitance synthetic humidity sensing element assembly, comprising an element including a sheet-like core formed of a dielectric moisture sensitive material, said element also including an electrode layer bonded to each surface of the core and being porous to the diffusion of water vapor therethrough, each electrode layer comprising a dielectric matrix having a plurality of interconnected electrically conductive particles distributed within said matrix, a mounting frame connected to spaced portions of the element and includng a pair of eLectrical conductors adapted to be connected in an electrical circuit, clamping means for connecting each electrode layer to one of said conductors to provide a positive electrical contact therebetween, and an outer insulating casing disposed around the element and connected to the frame, said casing having openings therein whereby the element is exposed to the atmosphere.
Claim 32
Dependent Claim
21 words
The assembly of claim 26, and including a terminal connected to each conductor and projecting outwardly of the frame and casing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |