Smoke detector with regulated constant-current circuit for driving optical sources
First Claim
1. A method for powering first and second light emitting diodes (LEDs) in a smoke sensor of a hazard detection system, the system comprising a power source signal ranging between a first signal value and a second signal value, the method comprising:
- managing a first LED power signal for use by the first LED, wherein managing the first LED power signal comprises;
down converting the power source signal to the first LED power level, wherein the first LED power signal has a value less than the first and second signal values; and
managing a second LED power signal for use by the second LED, wherein managing the second LED power signal comprises;
up converting the power source signal to the second LED power signal, wherein the second LED power signal has a value greater than the first and second signal values.
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Accused Products
Abstract
Systems and methods for driving optical sources operating at different wavelengths within a smoke sensor are described herein. Multiple optical sources such as light emitting diodes may be used in a photoelectric smoke sensor to detect particles of different sizes. Photoelectric smoke sensors can operate by pulsing the LEDs and measuring a response in a light sensor. The signal measured at the light sensor changes based on the quantity of particles existing in a smoke chamber. Each optical source may have different operational characteristics and thus require different drive currents to operate. LED driving circuitry according to embodiments discussed herein provide a consistent and reliable drive current to each optical source, while maximizing efficiency of power consumption across a range of possible voltages provided by different power sources.
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Citations
22 Claims
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1. A method for powering first and second light emitting diodes (LEDs) in a smoke sensor of a hazard detection system, the system comprising a power source signal ranging between a first signal value and a second signal value, the method comprising:
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managing a first LED power signal for use by the first LED, wherein managing the first LED power signal comprises; down converting the power source signal to the first LED power level, wherein the first LED power signal has a value less than the first and second signal values; and managing a second LED power signal for use by the second LED, wherein managing the second LED power signal comprises; up converting the power source signal to the second LED power signal, wherein the second LED power signal has a value greater than the first and second signal values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A hazard detection system, comprising:
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a smoke chamber comprising first and second light emitting diodes (LEDs); a power input configured to receive a power signal ranging between first and second values; first LED driving circuitry coupled to receive the power signal from the power input and operative to provide a first LED power signal to the first LED, the first LED power signal characterized as having a value lower than the first and second values and a first substantially constant current value; and second LED driving circuitry coupled to receive the power signal from the power input and operative to provide a second LED power signal to the second LED, the second LED power signal characterized as having a value higher than the first and second values and a second substantially constant current. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A particle detector for use in a hazard detection system that is powered by one of a plurality of different power sources, wherein a power signal supplied by the plurality of power source ranges between first and second values, the particle detector comprising:
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a particle detection chamber comprising an infrared light emitting diode (IR LED), a blue light emitting diode (LED), and a photodetector; a power input for receiving the power signal; and LED driving circuitry coupled to the IR LED, the blue LED, and to receive the power signal, the LED driving circuitry operative to supply a first drive current to the IR LED and a second drive current to the blue LED, wherein the first and second drive currents are independently derived from the power signal using independently operating low dropout regulators. - View Dependent Claims (20, 21, 22)
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Specification