Humidity-sensitive sensor

• US 3,983,527 A
• Filed: 08/12/1974
• Issued: 09/28/1976
• Est. Priority Date: 08/14/1973
• Status: Expired due to Term

• Current Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Inventors: Sono, Kenzo, Tanaka, Keihachiro, Ohsato, Nobuyoshi
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/496,856
• Time in Patent Office: 778 Days
• Field of Search: 338/35, 338/34, 338/308, 200/61.04, 73/336.5, 23/254 E, 23/255 E, 340/235, 219/203, 219/522, 427/123, 427/125, 427/126, 428/328, 428/329, 428/402, 428/403
• US Class Current: 338/35
• CPC Class Codes: B60S 1/00 Cleaning of vehicles by apparatus not integral with vehicle B60S3/00; cleaning in general B08B; de-icing of aircraft B64D; heating arrangements specially adapted for transparent or reflecting areas H05B3/84
• 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: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide

Abstract

A humidity-sensitive sensor, especially useful on the window of an automobile with the sensor on the inside surface of the glass. The sensor has a pair of spaced electrodes and a humidity-sensitive coating composed of a hydroscopic resin extending over the pair of electrodes. The resin can be an acrylate resin or a methacrylate resin, and preferably is a resin which has a volume change of at least 10% in response to a 50% change in humidity. Dispersed in the resin are electrically conductive particles, preferably in an amount of from 20 to 60% by volume of the amount of resin. The sensor, prior to its use in an operating device, is preferably exposed to a high humidity condition and a low humidity condition at least thirty times in order to stabilize it.

Claims

1. A humidity-sensitive sensor comprising:

an electrically non-conductive base plate;

a pair of spaced electrodes fixed on said base plate;

a humidity-sensitive coating composed of a hygroscopic resin having dispersed therein electrically conductive particles and extending over said pair of electrodes; and

an adhesive layer bonding said humidity-sensitive coating to said base plate, said adhesive layer being composed of an adhesive having dispersed therein electrically conductive particles and electrically connecting each of said electrodes to said humidity-sensitive coating while electrically insulating said electrodes from each other.

2. The sensor of claim 1 wherein said adhesive is non-hygroscopic.

3. The sensor of claim 2 wherein the volume of the electrically conductive particles dispersed in the hygroscopic resin is 20 to 60% of that of the hygroscopic resin.

4. The sensor of claim 3 wherein said hygroscopic resin is a resin taken from the group consisting of acrylate resins and methacrylate resins.

5. The sensor of claim 4 wherein said resin is a polymer of a hydroxy lower alkyl acrylate.

6. The sensor of claim 4 wherein said resin is a hydroxy lower alkyl methacrylate.

7. The sensor of claim 4 wherein said resin is a homopolymer of 2-hydroxyethyl methacrylate.

8. The sensor of claim 4 wherein said resin is a copolymer of 2-hydroxyethyl methacrylate.

9. The sensor of claim 3 wherein said hygroscopic resin is cross-linked with a cross-linking agent.

10. The sensor of claim 3 wherein at least one of said pair of electrodes has a lead of a metal selected from the group consisting of gold, platinum, palladium, rhodium and alloys thereof.

11. The sensor of claim 3 wherein said base plate is a window glass of an automobile, and the humidity-sensitive sensor is on the inside surface of said window glass.