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
56 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, 39, 40, 42)
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34. A method for charging a rechargeable battery by a charge current comprising the steps of
(a) sampling a voltage of said rechargeable battery and said charge current; -
(b) if said voltage of said rechargeable battery is less than or equal to a voltage threshold value and said charge current is less than or equal to a current threshold value, setting said charge current to a bulk charge value and applying said charge current to said rechargeable battery for a bulk charge time period; (c) if said voltage of said rechargeable battery is greater than or equal to a low voltage threshold value and less than or equal to said voltage threshold value and said charge current is within a certain range of said bulk charge value, and a duration of said bulk charge time period is greater than or equal to a bulk charge time expiration period, setting said charge current to a trickle charge low value and applying said charge current to said rechargeable battery for a trickle charge low time period; (d) if said charge current is less than or equal to a current threshold value, and a duration of said trickle charge low time period is greater than or equal to a trickle charge low time expiration period, setting said charge current to a trickle charge high value and applying said charge current to said rechargeable battery for a trickle charge high time period; (e) if said voltage of said rechargeable battery is greater than or equal to said low voltage threshold value and less than or equal to said voltage threshold value and said charge current is within a certain range of said trickle charge high value, and a duration of said trickle charge high time period is greater than or equal to a trickle charge high time expiration period, setting said charge current to a trickle charge low value and applying said charge current to said rechargeable battery; and (f) repeating said steps (a) through (e) at least once. - View Dependent Claims (35, 36, 37, 41)
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38. A method for charging a rechargeable battery by a charge current comprising the steps of
(a) sampling a voltage of said rechargeable battery and said charge current; -
(b) if said voltage of said rechargeable battery is less than or equal to a voltage threshold value and said charge current is less than or equal to a current threshold value, setting said charge current to a bulk charge value and applying said charge current to said rechargeable battery for a bulk charge time period; (c) calculating a delta V/delta t value of said voltage, wherein V is said voltage of said rechargeable battery, and t is time. (d) if said delta V/delta t value is less than or equal to about zero for a first conditional time period, or if during a second conditional time period said delta V/delta t value is not less than or equal to about zero for said first conditional time period, setting said charge current to a trickle charge low value and applying said charge current to said rechargeable battery for a trickle charge low time period; (e) if said current of said charger circuit is less than or equal to said current threshold value, checking at trickle charge low check time intervals a duration of said trickle charge low state, and if said duration of said trickle charge low state is greater than or equal to a trickle charge low time expiration period, setting said charge current to a trickle charge high value and applying said charge current to said rechargeable battery for a trickle charge high time period; and (f) repeating said steps (a) through (e) at least once.
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43. 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 (44, 45, 46, 47, 48, 49)
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50. 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 (51, 52, 53, 54, 55, 56)
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Specification