Patent ID: 6141234
Filing Date: 2000-10-31
Classification: H02J

Abstract:
A power supply for an emergency sign connected to AC line power, comprising:a first capacitor having a first terminal connected to AC line power and a second terminal; a bridge rectifier having a first input terminal connected to a said second terminal of said first capacitor, said bridge rectifier having a second terminal connected to AC line power, said bridge rectifier having first and second outputs;a second capacitor connected across first and second outputs of said bridge rectifier;branches connected in parallel with each other, each of said branches including a plurality of light emitting diodes connected in series, said branches being connected to said second output of said bridge rectifier;a first resistor connected between said first output of said bridge rectifier and said branches;a battery having first and second battery terminals, said first battery terminal being connected to said second output of said bridge rectifier;a first diode-resistor branch connected between said first output of said bridge rectifier and first battery terminal, said first diode-resistor branch including a second resistor and a first diode in series, said first diode being connected at a first polarity to permit forward current flow from said first output of said bridge rectifier to first battery terminal; anda second diode-resistor branch connected between said branches and said first battery terminal,said second diode-resistor branch including a third resistor and a second diode in series, said second diode being connected at a second polarity to permit forward current flow from said first battery terminal to said branches.