Fire detector drift compensation
First Claim
1. A fire detector system comprising:
- a fire detector unit;
a sensor disposed in the fire detector unit and arranged to detect characteristics of a fire and to generate an output signal indicative of the characteristics detected by the sensor; and
a processor arranged to receive the output signal from the sensor and to generate a fire alarm signal when the output signal exceeds an alarm point threshold;
wherein the system is arranged to change the alarm point threshold over time to compensate for drift in the response of the detector unit to the characteristics of a fire;
wherein the fire detector unit includes a first sensitivity mode with a first drift compensation limit and a second sensitivity mode with a second drift compensation limit, the second sensitivity mode being more sensitive than the first sensitivity mode; and
wherein, as the alarm point threshold in the first sensitivity mode approaches or reaches the first drift compensation limit, the system is changed from the first sensitivity mode to the second sensitivity mode.
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Accused Products
Abstract
A fire detector system comprises a fire detector unit; a sensor disposed in the fire detector unit and arranged to detect the characteristics of a fire and to generate an output signal indicative of the characteristics detected by the sensor; and a processor arranged to receive the output signal from the sensor and to generate afire alarm signal when the output signal exceeds an alarm point threshold; wherein the system is arranged to change the alarm point threshold over time to compensate for drift in the response of the detector unit; wherein the fire detector unit includes a first sensitivity mode with a first drift compensation limit and a second sensitivity mode with a second drift compensation limit, the second sensitivity mode being more sensitive than the first; and wherein, as the first alarm point threshold in the first sensitivity mode is approached or reached, the mode of the system is changed to the second sensitivity mode.
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Citations
29 Claims
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1. A fire detector system comprising:
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a fire detector unit; a sensor disposed in the fire detector unit and arranged to detect characteristics of a fire and to generate an output signal indicative of the characteristics detected by the sensor; and a processor arranged to receive the output signal from the sensor and to generate a fire alarm signal when the output signal exceeds an alarm point threshold; wherein the system is arranged to change the alarm point threshold over time to compensate for drift in the response of the detector unit to the characteristics of a fire; wherein the fire detector unit includes a first sensitivity mode with a first drift compensation limit and a second sensitivity mode with a second drift compensation limit, the second sensitivity mode being more sensitive than the first sensitivity mode; and wherein, as the alarm point threshold in the first sensitivity mode approaches or reaches the first drift compensation limit, the system is changed from the first sensitivity mode to the second sensitivity mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 29)
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16. A method of compensating for drift in a fire detector unit having a sensor arranged to detect characteristics of a fire and to generate an output signal indicative of the characteristics detected by the sensor, the method involving a processor arranged to receive the output signal from the sensor and to control the response by indicating a fire when the output signal exceeds an alarm point threshold, the method comprising:
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(1) placing the fire detector unit in a first sensitivity mode with a first drift compensation limit; (2) changing the alarm point threshold over time to compensate for drift in the response of the detector unit to the characteristics of a fire; (3) changing the mode of the unit from the first sensitivity mode to a second sensitivity mode with a second drift compensation limit and which is a more sensitive mode than the first sensitivity mode as the alarm point threshold in the first sensitivity mode approaches or reaches the first drift compensation limit; (4) changing the alarm point threshold over time to compensate for drift in the response of the detector unit to the characteristics of a fire. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A fire detector unit comprising;
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a sensor disposed in the fire detector unit and arranged to detect characteristics of a fire and to generate an output signal indicative of the characteristics detected by the sensor; and a processor arranged to receive the output signal from the sensor and to control the response by indicating a fire when the output signal exceeds an alarm point threshold; wherein the fire detector unit is arranged to change the alarm point threshold over time to compensate for drift in the response of the detector unit; wherein the fire detector unit includes a first sensitivity mode with a first drift compensation limit and a second sensitivity mode with a second drift compensation limit, the second sensitivity mode being more sensitive than the first; and wherein, as the first alarm point threshold in the first sensitivity mode is approached or reached, the fire detector unit is changed from the first sensitivity mode to the second sensitivity mode.
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Specification