Hygrometer with plural measuring bones and redundancy system circuit
First Claim
1. In a hygrometer of the electrical impedance type comprising a sensing element including an electrically conducting substrate, a porous moisture adsorbing layer the electrical properties of which vary with the quantity of water vapour adsorbed onto it formed on said electrically conducting substrate, and a porous conducting electrode formed on top of porous moisture adsorbing layer;
- the improvement wherein said porous conducting electrode is divided into a number of separate measuring zones and said hygrometer also includes a redundancy system circuit, said redundancy system circuit receiving separate outputs one from each of said respective measuring zones and only produces an output indicative of the humidity when said outputs from at least two of said separate zones are in agreement.
3 Assignments
0 Petitions
Accused Products
Abstract
A hygrometer of the electrical impedance type includes a sensing element (1) having a porous moisture adsorbing layer (3), the electrical properties of which vary with the quantity of water vapour adsorbed on it sandwich between a substrate (2) and a porous conducting electrode (4). The conducting electrode (4) is divided into a number of separate measuring zones (6A, 6 and 6C) by gaps (5). The hygrometer also includes a redundancy system circuit (7) which is connected to each of the separate measuring zones (6A, 6B and 6C) and which only provides a moisture indication when the output from at least two of the zones (6A, 6B and 6C) are in agreement. This arrangement enables failures of the sensing element (1) to be detected and distinguished from a false moisture indication.
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Citations
15 Claims
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1. In a hygrometer of the electrical impedance type comprising a sensing element including an electrically conducting substrate, a porous moisture adsorbing layer the electrical properties of which vary with the quantity of water vapour adsorbed onto it formed on said electrically conducting substrate, and a porous conducting electrode formed on top of porous moisture adsorbing layer;
- the improvement wherein said porous conducting electrode is divided into a number of separate measuring zones and said hygrometer also includes a redundancy system circuit, said redundancy system circuit receiving separate outputs one from each of said respective measuring zones and only produces an output indicative of the humidity when said outputs from at least two of said separate zones are in agreement.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In the hygrometer of the electrical impedance type comprising a sensing element including an electrically conducting substrate, a porous moisture adsorbing layer the electrical properties of which vary with the quantity of water vapour adsorbed onto it formed on said electrically conducting substrate, and a porous conducting electrode formed on top of said porous moisture adsorbing layer;
- the improvement wherein said porous conducting electrode is divided into three separate measuring zones and said hygrometer also includes a redundancy system circuit, said redundancy system circuit receiving separate outputs one from each of said respective measuring zones and producing an output corresponding to the signals from whichever two of said three capacity measuring zones are substantially equal.
- View Dependent Claims (11, 12, 13, 14, 15)
Specification