The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 03, 1992
Filed:
Dec. 20, 1990
Kanji Ishii, Yokohama, JP;
Atsushi Nagai, Yokohama, JP;
Hochiki Kabushiki Kaisha, Tokyo, JP;
Abstract
An ionization-type smoke sensor having a 2-chamber 1-radiation source structure including an inner electrode having a radiation source, an intermediate electrode having an opening through which radiation from the radiation source passes, an outer electrode through which smoke may flow inside from outside, and an insulator supporting and insulating the inner electrode, the intermediate electrode and the outer electrode. In the sensor, a fence portion made of an insulating material is formed on and projecting from a surface of the insulator which faces the outer electrode, the fence portion surrounding the periphery of the opening of the intermediate electrode. By virtue of this arrangement, even when the sensor is subjected to flow of air heading from outside toward the opening of the intermediate electrode, the fence serves to reduce the flow of air heading toward the opening, thereby enabling the characteristics of the sensor chambers to remain stable against flow of air. Since the fence portion made of an insulating material is formed to project from the surface of the insulator, the creepage distance between the intermediate electrode and the outer electrode is long, thereby enabling an improved level of insulation for the electrodes.