Emergency power supply unit

Claim 1

AN EMERGENCY LIGHTING APPARATUS FOR AN ELEVATOR CAB WHICH COMPRISES: A VENTILATOR ARRANGED TO BE MOUNTED IN THE CEILING OF SAID CAB; AN EMERGENCY LIGHTINT UNIT POSITIONED WITHIN SAID VENTILATOR, SAID UNIT COMPRISING TRANSFORMER MEANS HAVING A PRIMARY WINDING CONNECTABLE TO AN ALTERNATING POWER SOURCE AND A SECONDARY WINDING INCLUDING FIRST AND SECOND TERMINALS, RECHARGEABLE BATTERY MEANS AND FIRST DIODE MEANS CONNECTED IN ELECTRICAL SERIES RELATIONSHIP, SAID BATTERY MEANS BEING CONNECTED TO SAID FIRST TERMINAL AND SAID FIRST DIODE MEANS BEING CONNECTED TO SAID SECOND TERMINAL TO MAINTAIN SAID BATTERY IN A CHARGED CONDITION FROM SAID TRANSFORMER MEANS, SOLID STATE SWITCHING MEANS INCLUDING AN ANODE, A CATHODE, AND A GATE, EMERGENCY LAMP MEANS POSITIONED TO DIRECT EMERGENCY LIGHT DOWNWARD FROM SAID APPARATUS AND CONNECTED IN SERIES WITH SAID ANODE AND CATHODE, THE SERIES CIRCUIT BEING CONNECTED IN PARALLEL WITH SAID BATTERY, AND A SERIES CIRCUIT COMPRISING SECOND DIODE MEANS AND RELATIVELY HIGH IMPEDANCE CAPACITOR MEANS CONNECTED BETWEEN SAID SECOND TERMINAL AND THE GATE OF SAID SOLID STATE SWITCHING MEANS.