Scattered light fire detector
First Claim
Patent Images
1. Method for evaluating scattering signals of a fire detector, comprising:
- measuring the scattering signals at two scattering angles;
determining an alarm threshold; and
comparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals, the ratio of the scattering signals defining a factor F, F′
with
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Abstract
A scattered light fire detector and a method for evaluating scattering signals of a fire detector are disclosed. The microprocessor-based scattered light fire detector measures the scattering signals at two scattering angles and determines an alarm threshold. An alarm value is determined as a function of the ratio of the scattering signals and compared with the determined alarm threshold. The fire detector can be used with mixed fires without prior calibration. Fraudulent measurement values arising, for example, from water vapor can be stored in a memory.
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Citations
35 Claims
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1. Method for evaluating scattering signals of a fire detector, comprising:
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measuring the scattering signals at two scattering angles;
determining an alarm threshold; and
comparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals, the ratio of the scattering signals defining a factor F, F′
with - View Dependent Claims (2, 3, 4, 27, 28, 29)
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5. A method for evaluating scattering signals of a fire detector, comprising:
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measuring the scattering signals at two scattering angles;
determining an alarm threshold; and
comparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals and is a weighted sum of values corresponding to the scattering signals. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A method for evaluating scattering signals of a fire detector, comprising:
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measuring the scattering signals at two scattering angles;
determining an alarm threshold; and
comparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals and the scattering signals are multiplied with at least one value corresponding to an additional input value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method for evaluating scattering signals of a fire detector, comprising:
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measuring the scattering signals at two scattering angles;
determining an alarm threshold; and
comparing an alarm value with the alarm threshold, wherein the alarm value is determined as a function of the ratio of the scattering signals, and wherein for each scattering angle a quiescent value is determined and the quiescent value is subtracted from the corresponding scattering signal. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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30. A scattered light fire detector, comprising:
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a scattered light system for determining scattering signals having at least a forward scattering angle and a backscatter angle;
a processor which determines an alarm value from a ratio of the scattering signals and compares the alarm value with a predetermined alarm threshold; and
a temperature sensor which measures an ambient temperature, wherein the scattering signals are multiplied with at least one value corresponding to the ambient temperature. - View Dependent Claims (31, 32, 33, 34, 35)
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Specification