Environmental abnormality alarm apparatus

• US 4,831,361 A
• Filed: 06/08/1988
• Issued: 05/16/1989
• Est. Priority Date: 06/30/1987
• Status: Expired due to Term

• Current Assignee: National Company Limited
• Original Assignee: Nittan Co. Ltd. (Old) (Secom Company Limited)
• Inventors: Kimura, Tetsuo
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/203,928
• Time in Patent Office: 342 Days
• Field of Search: 340/506, 340/500, 340/501, 340/510, 340/511, 340/521, 340/522, 340/537, 340/661-663
• US Class Current: 340/506
• CPC Class Codes: G08B 23/00 Alarms responsive to unspecified undesired or abnormal conditions
• CPC Class Codes: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components

Abstract

An environmental abnormality alarm apparatus includes a sensor for detecting a fire, gas leakage, a burglar, or the like in a monitoring area, and a signal processor for receiving an output from the sensor and evaluating the output for an alarm determination reference and generating an alarm. A detecting unit is provided in the monitoring area of the sensor to detect a change in environmental condition resulting from objects or conditions other than those to be detected by the sensor, and an alarm determination reference is changed in accordance with an output state of the detecting unit during signal processing.

Claims

1. An environmental abnormality alarm apparatus comprising:

sensor means for detecting a dangerous abnormality in a monitoring area;

signal processor means for receiving an output from said sensor and evaluating said output against an alarm determination reference and generating an alarm based on the evaluation;

detecting means in said monitoring area of said sensor means for detecting an object or condition in said monitoring area other than said dangerous abnormality to be detected by said sensor means; and

means for changing said alarm determination reference in accordance with an output of said means for detecting during processing of said output of said sensor means.

2. A method for operating an environmental abnormality alarm apparatus comprising the steps of:

detecting a dangerous abnormality in a monitoring area using at least one sensor, said sensor having an output;

evaluating said sensor output against an alarm determination reference;

generating an alarm signal based on the result of the evaluation;

detecting an object or condition in said monitoring area other than said dangerous abnormality to be detected by said sensor, and generating a signal corresponding to said object or condition; and

changing said alarm determination reference in accordance with said signal corresponding to said object or condition during processing of said output of said sensor.