LED-BASED EMERGENCY LIGHTING EQUIPMENT AND METHODOLOGY
First Claim
1. An emergency lighting system comprising:
- an AC-DC switch mode power converter;
a brown-out detection circuit for detecting a change in AC voltage and determining a brown-out state by reference to preset threshold values;
a rechargeable battery;
a charger circuit for charging said battery and operatively coupled to said AC-DC switch mode power converter;
at least one LED lighting source powered by said battery upon determination of said brown-out state; and
a microprocessor powered by said battery and executing a pulse charging algorithm to selectively change said battery power consumption levels and control said charger circuit for selectively charging said battery.
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Accused Products
Abstract
Systems and methods provide LED-based emergency lighting utilizing AC-DC switch mode power conversion technology, NiMH battery technology, and emergency lighting lamps that use high power white LEDs as the emergency lighting source. A low voltage microprocessor based circuit design reduces the battery input voltage for the unit to a nominal level of 2.4VDC. The microprocessor executes a pulse charging algorithm to lower battery maintenance mode power consumption levels and extend the useful life of the battery. Brownout detection technology does not require the determination of the AC input voltage level or transmission of the brownout detection signal to the secondary side of the circuit. A rechargeable battery is charged by a charge current selectively set to a bulk charge value, a trickle charge high value, or a trickle charge low value based on sampling of the voltage of the rechargeable battery and the charge current.
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Citations
50 Claims
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1. An emergency lighting system comprising:
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an AC-DC switch mode power converter; a brown-out detection circuit for detecting a change in AC voltage and determining a brown-out state by reference to preset threshold values; a rechargeable battery; a charger circuit for charging said battery and operatively coupled to said AC-DC switch mode power converter; at least one LED lighting source powered by said battery upon determination of said brown-out state; and a microprocessor powered by said battery and executing a pulse charging algorithm to selectively change said battery power consumption levels and control said charger circuit for selectively charging said battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A brown-out detection apparatus comprising:
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a voltage sensing circuit sensing an input AC voltage, said input AC voltage having a first nominal input voltage value or a second nominal input voltage value, said voltage sensing circuit including an output outputting a reference DC voltage proportional said input AC voltage; a first circuit responsive to said output of said voltage sensing circuit, said first circuit including a first output outputting a first voltage value when said input AC voltage is below a threshold voltage level and a second voltage value when said input AC voltage is above said threshold level; and a second circuit responsive to said first output of said first circuit, said second circuit including a second output outputting a second control signal indicative of a brown-out condition of said input AC voltage based on said first or second voltage value output of said first circuit and an internal brown-out threshold value. - View Dependent Claims (38, 39, 40, 41, 42, 43)
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44. A brown-out detection method comprising:
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sensing an input AC voltage having a first nominal input voltage value or a second nominal input voltage value; outputting a reference DC voltage proportional said input AC voltage; outputting in response to said reference DC voltage a first voltage value when said input AC voltage is below a threshold voltage level, or a second voltage value when said input AC voltage is above said threshold level; and outputting a second control signal indicative of a brown-out condition of said input AC voltage based on said first or second voltage value and an internal brown-out threshold value. - View Dependent Claims (45, 46, 47, 48, 49, 50)
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Specification