Occupancy sensor with active sensitivity adjustment based on ambient temperature
First Claim
1. An occupancy sensor, comprising:
- a passive infrared (PIR) sensing element to sense a background infrared level of a monitored space, and a heat signature of an occupant or a moving object in the monitored space;
a temperature sensing element to sense an ambient temperature of the monitored space;
memory for storing the background infrared level; and
a processor communicatively coupled to the memory, the PIR sensing element and the temperature sensing element;
the processor being programmed to;
determine a difference in temperature between the heat signature of the occupant or the moving object, and the background infrared level so that when the processor determines that the difference in temperature exceeds a sensing threshold, an occupied signal is generated; and
adjust the sensing threshold based on information representative of the ambient temperature in the monitored space;
wherein, when the processor determines that the ambient temperature of the monitored space has changed as compared to a stored value, the processor adjusts the sensing threshold so that a greater or lesser difference in temperature between the heat signature of the occupant or the moving object, and the background infrared level results in the occupied signal being generated.
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Abstract
A system and method provide fail-safe operation of a lighting system. A lighting level detector is used to obtain a baseline lighting level for a low-intensity light. If the detector measures less than the baseline level when an occupancy sensor determines the space is unoccupied, a high-intensity light is energized and an indication is provided to a user that the low-intensity light has failed. A method provides daylighting operation of a lighting system. An occupancy sensor can have Wi-Fi functionality to enable remote configuration of the sensor. A line voltage occupancy sensor can include an interface with low voltage devices. An occupancy sensor can include an integral interface to enable an external control system to override the sensor'"'"'s normal logic under emergency conditions. An occupancy sensor can include an active temperature compensation feature. An occupancy sensor can also incorporate an automatically adjustable coverage area.
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Citations
11 Claims
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1. An occupancy sensor, comprising:
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a passive infrared (PIR) sensing element to sense a background infrared level of a monitored space, and a heat signature of an occupant or a moving object in the monitored space; a temperature sensing element to sense an ambient temperature of the monitored space; memory for storing the background infrared level; and a processor communicatively coupled to the memory, the PIR sensing element and the temperature sensing element;
the processor being programmed to;determine a difference in temperature between the heat signature of the occupant or the moving object, and the background infrared level so that when the processor determines that the difference in temperature exceeds a sensing threshold, an occupied signal is generated; and adjust the sensing threshold based on information representative of the ambient temperature in the monitored space; wherein, when the processor determines that the ambient temperature of the monitored space has changed as compared to a stored value, the processor adjusts the sensing threshold so that a greater or lesser difference in temperature between the heat signature of the occupant or the moving object, and the background infrared level results in the occupied signal being generated. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An occupancy sensor, comprising:
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a digital passive infrared (PIR) sensing element to sense an occupant or a moving object in a monitored space and to sense an ambient temperature of the monitored space; and a processor communicatively coupled to the PIR sensing element, the processor being programmed to actively adjust a sensing threshold to account for changes in ambient temperatures in the monitored space; wherein; the PIR sensing element senses a background infrared level of the monitored space, the background infrared level being stored in memory associated with the processor; the PIR sensing element senses a heat signature of the occupant or the moving object when in the monitored space; when the difference in temperature between the heat signature of the occupant or the moving object, and the background infrared level exceeds the sensing threshold, an occupied signal is generated; and the processor is programmed to actively adjust the sensing threshold by periodically determining the ambient temperature, and, based on the determined ambient temperature, adjust the sensing threshold. - View Dependent Claims (9, 10)
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11. A method for energizing a load;
- the method comprising the steps of;
sensing a background infrared level of a monitored space; sensing an ambient temperature of the monitored space; periodically sensing a heat signature of the monitored space; determining whether the heat signature exceeds the background infrared level by a sensing threshold; transmitting, when the sensing threshold has been met or exceeded, an occupied signal to a load control device, the occupied signal instructing the load control device to energize the load; and actively adjusting the sensing threshold based on changes in the sensed ambient temperature of the monitored space via periodically determining the ambient temperature in the monitored space has increased or decreased; and
, if a determination that the ambient temperature in the monitored space has increased, then decreasing the sensing threshold; and
, if a determination that the ambient temperature in the monitored space has decreased, then increasing the sensing threshold.
- the method comprising the steps of;
Specification