EP0618555A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Smoke type fire detector
Assignee: Nohmi Bosai Ltd
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Filing: 1994-03-19
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Granted: —
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Expires: 2014-03-19
Abstract
Abstract An object of the present invention is to provide a smoke type fire detector which detects a smoke density accurately, even when an internal temperature thereof changes. An internal temperature detecting unit (70) detects an ambient temperature of a light emitting element and a light receiving element. A correction coefficient K having a value associated with the ambient temperature detected by the temperature detecting unit is used to correct an output level of the light receiving element.
Inventors
- 👤 Toshikazu Morita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 08:08
CPC Classifications
G; G08; G08B; G08B29/00; G08B29/18; G08B29/20; G08B29/24; G08B29/185
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
112 words
A smoke type fire detector in which scattered light resulting from scattering of light emanating from a light emitting element due to smoke particles is received by a light receiving element, and a smoke density is detected using an output level of said light receiving element, comprising: a temperature detecting means for detecting an ambient temperature of said light emitting element and said light receiving element; a temperature compensating means for correcting an output level of said light receiving element according to said ambient temperature detected by said temperature detecting means; and a smoke density identifying means for identifying a smoke density using said output level corrected by said temperature compensating means.
Claim 2
Dependent Claim
112 words
A smoke type fire detector according to claim 1, wherein said temperature compensating means and said smoke identifying means are a microcomputer and a memory respectively; wherein said memory stores a temperature correction coefficient K having values associated with temperatures detectable by said temperature detecting means; wherein said smoke density identifying means identifies a smoke density by comparing an output level of said light receiving element with a given reference level; and wherein said temperature compensating means uses said temperature correction coefficient K having a value associated with a temperature detected by said temperature detecting means to correct either said output level of said light receiving element or said given reference level.
Claim 3
Dependent Claim
21 words
A smoke type fire detector according to claim 1, wherein said temperature detecting means utilizes the temperature characteristics of semiconductor elements.
Claim 4
Dependent Claim
33 words
A smoke type fire detector according to claim 3, wherein said temperature detecting means includes at least one diode and utilizes the temperature characteristic of said diode regarding the voltage across said diode.
Claim 5
Dependent Claim
32 words
A smoke type fire detector according to claim 3, wherein said temperature detecting means includes a transistor and utilizes the temperature characteristic of said transistor regarding the base-emitter voltage of said transistor.
Claim 6
Dependent Claim
76 words
A smoke type fire detector according to one of claims 2 to 6, wherein said microcomputer stores an initial output of said temperature detecting means and a reference temperature, which is a temperature detected when said initial output is stored, in said memory, and performs temperature compensation using an ambient temperature calculated by computing a deviation, which is calculated using an output of said temperature detecting means and said initial output, and said stored reference temperature.
Claim 7
Dependent Claim
48 words
A smoke type fire detector according to claim 1, wherein said temperature detecting means includes a control means for controlling power supply and is supplied power under the control of said control means, and said control means supplies power to said temperature detecting means only for temperature detection.
References Cited (Backward Citations)
No citation records indexed.
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