Abstract:
A method to provide emergency lighting, the method comprising: detecting absence of current in the emergency lighting system; determining state of a main power switch connecting the emergency lighting system with a main power supply; and switching to backup power to provide emergency lighting based on the determination of the state of the main power switch. A system, the system comprising: a signal generator to generate a control signal; a switching unit to connect and disconnect a light emitting element; a control signal sensor to detect the control signal in the emergency lighting system; and a switching controller linked to the switching unit to: detect absence of current in the emergency lighting system; determine state of a main power switch not tied to the emergency lighting system; and switch to backup-up power to provide the emergency lighting based on the determination of the state of the main power switch.

Description:
PRIORITY CLAIM 
     This U.S. patent application claims priority under 35 U.S.C. §119 to Indian Application No. 3754/CHE/2015, filed Jul. 21, 2015. The aforementioned applications are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     This disclosure relates generally to emergency lighting systems, and more particularly to an emergency lightening system with smart switching. 
     BACKGROUND 
     Typically, an emergency lighting system may comprise of an internal backup power. The emergency lighting system may switch to the internal backup power on failure of a main power supply. A user may switch the main power supply off to shut down the emergency lighting system. The emergency lighting system may switch to the internal backup power, if the user switches the main power supply off. Typically, the emergency lighting system may not be able to distinguish between failure of the main power supply and user switching off the main power supply. 
     SUMMARY 
     A method to provide emergency lighting, the method comprising: detecting absence of current in the emergency lighting system; determining state of a main power switch connecting the emergency lighting system with a main power supply; and switching to backup power to provide emergency lighting based on the determination of the state of the main power switch. 
     An emergency lighting system, the system comprising: a signal generator to generate a control signal; a switching unit to connect and disconnect a light emitting element; a control signal sensor to detect the control signal in the emergency lighting system; and a switching controller linked to the switching unit to: detect absence of current in the emergency lighting system; determine state of a main power switch not tied to the emergency lighting system; and switch to backup-up power to provide the emergency lighting based on the determination of the state of the main power switch. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. 
         FIG. 1  illustrates an exemplary diagram for an environment with emergency lighting system to provide emergency lighting. 
         FIG. 2  illustrates the switching controller which may include a control signal detector, a current detector and a switching element. 
         FIG. 3  illustrates an exemplary flow diagram of a method to provide emergency lighting. 
         FIG. 4  illustrates an exemplary circuit diagram  400  with an emergency lighting system to provide emergency lighting. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the spirit and scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope and spirit being indicated by the following claims. 
       FIG. 1  illustrates an exemplary diagram for an environment  100  with an emergency lighting system  102  to provide emergency lighting. The exemplary environment  100  may include an emergency lighting system  102 , a main power switch  104 , a main power supply  106  and a bypassing element  108 . The emergency lighting system  102  may further contain a switching controller  110 , an emergency lighting element  112 , a backup power  114  and a signal generator  116 . The main power supply  106  may supply power to the emergency lighting system  102 . The main power supply  106  may either be direct AC main or some other form of power, such as DC, etc. The main power switch  104  may control the input of the main power supply  106  to the emergency lighting system  102 . The main power switch  104  may be controlled by a user. The bypassing element may be connected in parallel to the main power supply  106  between the main power switch  104  and the main power supply  106 . The bypassing element may have high resistance or reactance for the main power supply  106 , but allows the control signal to pass through. The emergency lighting element  112  may emit light by consuming electric current such as one or more incandescent bulbs or one or more clusters of high-intensity light-emitting diodes (LED). The backup power  114  may provide power to the emergency lighting system  102  on the failure of the main power supply  106  such as deep cycle batteries and other technologies such as flywheel energy storage or fuel cells. The signal generator  116  may be generate a control signal with a frequency that doesn&#39;t cause interference with the frequency of the main power supply. The switching controller  110  may alternate power supplied to the emergency lighting element  112  between the main power supply and the backup power  114 . While not shown, the exemplary environment  100  may include additional components, which are well known to those of ordinary skill in the art and thus will not be described here. 
       FIG. 2  illustrates the switching controller  110  which may include a control signal detector  202 , a current detector  204  and a switching element  206 . The switching controller  110  may detect an absence of electric current in the emergency lighting system. During course of operation, the emergency lighting system  102  may draw electric current from a main power supply. The input of main power supply  106  may be controlled the main power supply switch  104 . The main power supply switch  104  may be controlled by a user. During the course of operation of the emergency lighting system  102  the switching controller  110  may detect an absence of electric current in the emergency lighting system  102 . The absence of the electric current may be due to the user switching the main power switch  104  off or the main power supply failure. The absence of the electric current of electric current may be detected by the current detector  204 . The current detector  204  may be one or more current sensors such as hall-effect sensors, current shunt sensors, current transformer sensors. The one or more current sensors may be well known to those of ordinary skill in the art and thus will not be described here. 
     Then the switching controller  110  of the emergency lighting system  102  may determine state of the main power switch  104  connecting input of the main power supply  106  to the emergency power system  102 . The determination of the state of the main power switch  104  comprises detecting by the switching controller  110 , a control signal in the emergency lighting system  102 . The control signal may be generated by the signal generator  116  of the emergency lighting system  102 . The control signal may pass through the bypassing element  108  connect parallel to the main power supply  106  between the main power switch  104  and the main power supply  106 . The bypassing element  108  may have high resistance or reactance for the main power supply  106 , but allows the control signal to pass through. Once the control signal passed through the bypassing element  108 , the control signal may be detected by the control signal detector  202 . If the control signal is detected by control signal detector  202 , the state of the main power supply switch  104  may be determined as ON. If the control signal is not detected by the control signal detector  202 , the state of the main power supply switch  104  may be determined as OFF. The control signal detector  202  may not detect the control signal, if the control signal doesn&#39;t pass through the bypassing element  108 . Hence, the state of the main power supply switch  104  may be determined as OFF. 
     Once the state of the main power supply switch  104  is determined, the switching controller  110  may switch to a backup power  114  to provide emergency lighting. If the state of the main power supply switch  104  is determined as ON, then the switching element  206  may switch to the backup power  114  to provide the emergency lighting. If the state of the main power supply switch  104  is determined as OFF, the switching controller  110  may not switch to the backup power  114 . The switching element  206  may be logic gates or multiplexers (MUX) made by using power transistor(s) or made by using relay(s). 
       FIG. 3  illustrates an exemplary flow diagram of a method to provide emergency lighting. The method may involve detecting, by the switching controller  110  of an emergency lighting system  102 , an absence of electric current in the emergency lighting system  102  at step  302 . During course of operation, the emergency lighting system  102  may draw electric current from a main power supply. The input of main power supply  106  may be controlled the main power supply switch  104 . The main power supply switch  104  may be controlled by a user. During the course of operation of the emergency lighting system  102  the switching controller  110  may detect an absence of electric current in the emergency lighting system  102 . The absence of the electric current may be due to the user switching the main power switch  104  off or the main power supply failure. The absence of the electric current of electric current may be detected by the current detector  204 . The current detector  204  may be one or more current sensors such as hall effect sensors, current shunt sensors, current transformer sensors. The one or more current sensors may be well known to those of ordinary skill in the art and thus will not be described here. 
     At step  304 , the switching controller  110  of the emergency lighting system  102  may determine state of the main power switch  104  connecting the main power supply  106  to the emergency power system  102 . The determination of the state of the main power switch  104  comprises detecting by the switching controller  110 , a control signal in the emergency lighting system  102 . The control signal may be generated by the signal generator  116  of the emergency lighting system  102 . The control signal may pass through the bypassing element  108  connect parallel to the main power supply  106  between the main power switch  104  and the main power supply  106 . The bypassing element  108  may have high resistance or reactance for the main power supply  106 , but allows the control signal to pass through. Once the control signal passed through the bypassing element  108 , the control signal may be detected by the control signal detector  202 . If the control signal is detected by control signal detector  202 , the state of the main power supply switch  104  may be determined as ON. If the control signal is not detected by the control signal detector  202 , the state of the main power supply switch  104  may be determined as OFF. The control signal detector  202  may not detect the control signal, if the control signal doesn&#39;t pass through the bypassing element  108 . Hence, the state of the main power supply switch  104  may be determined as OFF. 
     Once the state of the main power supply switch  104  is determined, the switching controller  110  may switch to a backup power  114  to provide emergency lighting at step  304 . If the state of the main power supply switch  104  is determined as ON, then the switching element  206  may switch to the backup power  114  to provide the emergency lighting. If the state of the main power supply switch  104  is determined as OFF, the switching controller  110  may not switch to the backup power  114 . The switching element  206  may be logic gates or multiplexers (MUX) made by using power transistor(s) or made by using relay(s). 
       FIG. 4  illustrates an exemplary circuit diagram  400  with an emergency lighting system to provide emergency lighting. The exemplary circuit diagram  400  may include an emergency lighting system  402 , a switch  404  (as the main power switch  104 ), a main power source  406  (as the main power supply  106 ) and a High Pass Filter  408  (as the bypassing element  108 ). The emergency lighting system  402  may further contain a switching controller  410 , a light emitting element  412  (as the emergency lighting element  112 ), a battery management unit and a battery  414  (as the backup power  114 ) and a high frequency signal generator  416  (as the signal generator  116 ). The switching controller  410  may include a main power and high frequency signal detector  418  (as the control signal detector  202  and current detector  204 ), and a switching unit  420 . The switching controller  410  may detect an absence of electric current in the emergency lighting system. During course of operation, the emergency lighting system  402  may draw electric current from the main power source  406 . The input of main power source  406  may be controlled the switch  404 . The switch  404  may be controlled by a user. During the course of operation of the emergency lighting system  402  the switching controller  410  may detect an absence of electric current in the emergency lighting system  402 . The absence of the electric current may be due to the user switching the switch  404  off or the main power source  406  failure. The absence of the electric current of electric current may be detected by the main power and high frequency signal detector  418 . The main power and high frequency signal detector  418  may be one or more current sensors such as hall-effect sensors, current shunt sensors, current transformer sensors. The one or more current sensors may be well known to those of ordinary skill in the art and thus will not be described here. 
     Then the switching controller  410  of the emergency lighting system  102  may determine state of the switch  404  connecting input of the main power source  406  to the emergency power system  402 . The determination of the state of the switch  404  comprises detecting by the switching controller  410 , a high frequency control signal in the emergency lighting system  402 . The control signal may be generated by the signal generator  416  of the emergency lighting system  402 . The control signal may pass through the high pass filter  408  connect parallel to the main power source  406  between the switch  404  and the main power source  406 . The high pass filter  408  may have high resistance or reactance for the supply from the main power source  406  resistance as compared to the emergency lighting system  102 , but allows the high frequency control signal to pass through. Once the high frequency control signal passed through the high pass filter  408 , the high frequency control signal may be detected by the main power and high frequency signal detector  418 . If the high frequency control signal is detected by the main power and high frequency signal detector  418 , the state of the switch  404  may be determined as ON. If the high control signal is not detected by the main power and high frequency signal detector  418 , the state of the switch  404  may be determined as OFF. The main power and high frequency signal detector  418  may not detect the high frequency control signal, if the control signal doesn&#39;t pass through the high pass filter  408 . Hence, the state of the switch  404  may be determined as OFF. 
     Once the state of the switch  404  is determined, the switching controller  110  may switch to a backup power  414  to provide emergency lighting. If the state of the switch  404  is determined as ON, then the switching unit  420  may switch to the backup power  414  to provide the emergency lighting. If the state of the switch  404  is determined as OFF, the switching unit  420  may not switch to the backup power  414 . The switching unit  420  may be logic gates or multiplexers (MUX) made by using power transistor(s) or made by using relay(s). 
     It is intended that the disclosure and examples be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.