Patent Publication Number: US-2021185783-A1

Title: Emergency lighting system

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. patent application Ser. No. 16/423,462, filed May 28, 2019, which claims priority to U.S. patent application Ser. No. 15/487,600, filed Apr. 14, 2017, which claims priority to U.S. Provisional Application No. 62/324,575, filed Apr. 19, 2016, the entire contents both of which are hereby incorporated. 
    
    
     FIELD 
     Embodiments relate to emergency lighting equipment. 
     SUMMARY 
     Emergency lighting equipment, units, and systems provide essential illumination coverage for individual buildings or building complexes in the event of failure of the mains power supply, for example, so evacuation can be performed safely. Emergency lighting units are typically used to light the path of egress such as corridors, walkways, stairways, and exits from the premises. In response to power outage or reduction, emergency lighting units automatically transfer to emergency mode, providing necessary illumination in assisting building evacuation. 
     Emergency lighting units detect the existence of an emergency condition by detecting a brown-out event. A brown-out event is a type of an emergency condition during which the mains voltage provided to a building is reduced. Brown-out events occur when the demand for electricity is fairly high so that the mains voltage is dropped from its nominal level due to heavy loads. The mains voltage level may be reduced to a point at which some of the normally-on lighting fixtures are not able to operate. 
     Traditionally, during a brown-out event, an emergency lighting unit provides power to all of the lights of the emergency lighting unit. In order to apply power to all the lights during brown-out event, the emergency lighting unit requires a large, expensive, high-capacity battery. Additionally, when applying power to all the lights during a brown-out event, wasted light is used outside a typical emergency lighting distribution area. 
     Therefore, in one embodiment, the application provides an emergency lighting system including an auxiliary power supply, a plurality of lights including a first group of lights and a second group of lights, a driver configured to provide power, a switching circuit, a relay, and a controller. The switching circuit includes a driver input configured to receive power from the driver, an auxiliary power input configured to receive power from the auxiliary power supply, an emergency control input. The has a first position, in which power from the driver is provided to the first group of lights and the second group of lights; and a second position, in which power from the auxiliary power supply is provided to the second group of lights. The controller is configured to output a signal to the emergency control input when an input voltage is below a threshold. Wherein, the switching circuit places the relay in the second position upon receiving the signal at the emergency control input. 
     Other aspects of the application will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  illustrate an emergency lighting system according to one embodiment of the present application. 
         FIG. 2  illustrates a block diagram of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 3  illustrates a block diagram of a control system of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 4  illustrates a circuit diagram of an input power stage module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 5  illustrates a controller of the control system of  FIG. 3  according to some embodiments of the present application. 
         FIGS. 6A-6D  illustrate a circuit diagram of a mains power supply and a brown-out circuit module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 7  illustrates a circuit diagram of a battery charger power stage module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 8  illustrates a circuit diagram of a battery charger battery voltage detection module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 9  illustrates a circuit diagram of a battery charger charge current sensing module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 10  illustrates a circuit diagram of a battery charger battery temperature sensing module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 11  illustrates a circuit diagram of a battery charger voltage qualification module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 12  illustrates a circuit diagram of a battery charger battery presence module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 13  illustrates a circuit diagram of a light source of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIGS. 14A and 14B  illustrate a circuit diagram of a light switching module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 15  illustrates a circuit diagram of a driver power switch of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 16  illustrates an LED IC module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 17  illustrates a circuit diagram of an LED string voltage detection module of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
         FIG. 18  illustrates a flow chart of an operation of the emergency lighting system of  FIGS. 1A and 1B  according to some embodiments of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The application is capable of other embodiments and of being practiced or of being carried out in various ways. 
       FIGS. 1A and 1B  illustrate an emergency lighting unit, or system,  100  according to one embodiment of the application. The system  100  includes a housing  105  made from, for example, flame-rated UV stable thermoplastic material. The system  100  further includes a plurality of lights  110 . In some embodiments, the plurality of lights  110  include one or more light-emitting diodes (LEDs). In other embodiments, the plurality of lights  110  include one or more incandescent or fluorescent light sources. In some embodiments, the plurality of lights include a first light group  115  and a second light group  120 . In such an embodiment, the first light group  115  may be positioned to direct light in a first direction and the second light group  120  may be positioned to direct light in a second direction. In some embodiments, the first direction and the second direction may be the same. 
       FIG. 2  illustrates a block diagram of the emergency lighting system  100 . The system  100  includes a mains power supply module  200 , a charging circuit module  205 , a brown-out circuit module  210 , a battery module  215 , a driver (e.g., LED driver) module  220 , a light source module (e.g., LEDs, lamps, etc.)  225 , an NFC module  230 , an antenna  235 , and a controller  240 . The modular schematic illustrated in  FIG. 3  has been simplified for illustrative purposes and additional connections among or between various modules within the emergency lighting unit  100  can be present beyond those illustrated in  FIG. 3 . For example, the mains power supply module  200  can provide power directly to each of the modules within the emergency lighting unit  100 , rather than through one or more modules of the emergency lighting unit  100 . 
     The mains power supply module  200  receives power from a line voltage (e.g., an AC mains power supply) that provides, for example, an AC voltage of between approximately 100 VAC and 305 VAC (e.g., between 120 VAC and 277 VAC). The mains power supply module  200  is operable to rectify the AC input voltage and generate a DC output voltage that can be used to power the emergency lighting unit  100 . In some embodiments, the mains power supply module  200  is implemented using a flyback topology that incorporates a flyback transformer, as described below. The charging circuit module  205  receives power from the mains power supply module  200  and provides charging current to the battery module  215 . The brown-out circuit module  210  is connected to mains power supply module  200  through the charging circuit module  205  and extracts input voltage information related to the voltage level of the mains power supply. The battery module  215  includes one or more batteries and provides auxiliary power to the light source module  225  when mains power is unavailable (e.g., the unit is in an emergency or brown-out condition). In some embodiments, the batteries or battery cells have a lithium-based chemistry (e.g., lithium iron phosphate [“LiFePO4”]). The voltage of the batteries in the battery module  215  can also be monitored by the controller  240  to determine when the batteries need to be charged by the charging circuit module  205 . The driver module  220  generates drive signals for the light source module  225 . For example, the driver module  220  generates drive signals for the plurality of lights  110  of the light source module  225  based on specified or determined levels for the output currents provided to the plurality of lights  110 , a dimming level, fade-in times, fade-out times, etc. The NFC module  230  includes a connection to the antenna  235 , a connection to the controller  240 , and a memory for storing operational and control parameters for the emergency lighting unit  100 . In some embodiments, the NFC module  230  can include an NFC transceiver. The antenna  235  is, for example, etched onto a PCB and is operable to receive NFC signals within the 13.56 MHz ISM frequency band. In some embodiments, an inductor can be used in place of the antenna  235 . 
       FIG. 3  illustrates the controller  240  of the emergency lighting system  100  in more detail. The controller  240  is electrically and/or communicatively connected to a variety of modules or components of the emergency lighting unit  100 . For example, the illustrated controller  240  is connected to the charging circuit module  205 , the brown-out circuit module  210 , the battery module  215 , the driver module  220 , and the NFC module  230 . The controller  240  includes combinations of hardware and software that are operable to, among other things, control the charging state of the charging circuit module  205 , identify a brown-out or brown-in condition, monitor the voltage of the battery module  215 , control a drive level of driver module  220 , receive operational and control system parameters from the NFC module, etc. 
     In some embodiments, the controller  240  includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller  240  and/or the emergency lighting unit  100 . For example, the controller  240  includes, among other things, a processing unit  245  (e.g., a microprocessor or another suitable programmable device), a memory  250 , input units  255 , and output units  260 . The processing unit  245  includes, among other things, a control unit  265 , an arithmetic logic unit (“ALU”)  270 , and a plurality of registers  275  (shown as a group of registers in  FIG. 4 ), and is implemented using a known computer architecture, such as a modified Harvard architecture, a von Neumann architecture, etc. The processing unit  245 , the memory  250 , the input units  255 , and the output units  260 , as well as the various modules connected to the controller  240  are connected by one or more control and/or data buses (e.g., common bus  280 ). The control and/or data buses  280  are shown generally in  FIG. 4  for illustrative purposes. The use of one or more control and/or data buses for the interconnection between and communication among the various modules and components would be known to a person skilled in the art in view of the invention described herein. In some embodiments, the controller  240  is a microcontroller, is implemented partially or entirely on a semiconductor chip, is a field-programmable gate array (“FPGA”), is an application specific integrated circuit (“ASIC”), etc. 
     The memory  250  includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as read-only memory (“ROM”), random access memory (“RAM”) (e.g., dynamic RAM [“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasable programmable read-only memory (“EEPROM”), flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices or structures. The processing unit  245  is connected to the memory  250  and executes software instructions that are capable of being stored in a RAM of the memory  250  (e.g., during execution), a ROM of the memory  250  (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or a disc. Software included in the implementation of the emergency lighting unit  100  can be stored in the memory  250  of the controller  240 . The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller  240  is configured to retrieve from memory  250  and execute, among other things, instructions related to the control processes, methods, and communication protocols described herein. In other constructions, the controller  240  includes additional, fewer, or different components. 
       FIG. 4  illustrates an input power stage circuit module  300  for a controller  240  of the emergency lighting system  100  according to one embodiment of the application. The input power stage circuit module  300  regulates an input DC voltage to provide a stable DC output voltage (e.g., approximately 3V to approximately 5V) to the controller  240 . The output voltage VDD, of the input power stage circuit module  300 , is provided as an input voltage to the controller  240  as illustrated in  FIG. 5 . In some embodiments, the controller  240  is substantially similar to the controller  240  described with respect to  FIG. 2 . In some embodiments, the controller  240  and the input power stage circuit module  300  are located on a primary or main printed-circuit board (PCB). 
       FIG. 6  illustrates a mains power supply circuit  400  and a brown-out circuit module  405 . The mains power supply circuit module  400  utilizes a simplified offline flyback circuit topology. The mains voltage ranges from approximately 102 VAC to 305 VAC and is applied to inputs  410 . The AC input voltage is rectified and filtered before being provided to a transformer, or flyback transformer,  415 . The transformer  415  includes a primary coil, a secondary coil, and a switch  420 . In some embodiments, the switch  420  is a transistor (e.g., a FET, a MOSFET, a JFET, a BJT, or similar transistor). 
     In a typical flyback topology converter, the transformer  415  is not used as a traditional transformer to transmit energy from the primary side to the secondary side in real time. Instead, the transformer  415  is used to store energy. The mains power supply output  425 , MAIN_OUTPUT, is used to power various portions of the emergency lighting unit  100 . 
     The brown-out module  405  is operable to determine if the mains voltage drops below a threshold value, or recovers to exceed the threshold value. In some embodiments, the threshold value is approximately 80% to approximately 90% the mains voltage. For example, when the mains voltage is approximately 110 VAC, the threshold may be within a range of approximately 88 VAC to approximately 99 VAC. In another example, when the mains voltage is approximately 220 VAC, the threshold may be within a range of approximately 176 VAC to approximately 198 VAC. In some embodiments, the brown-out module  405  takes advantage of the flyback topology of the power supply and extracts input voltage information using the existing flyback power stage components. The brown-out module  405  scales the voltage down to a DC voltage that is proportional to the mains voltage level. The DC voltage can then be sampled by the controller  240  to monitor the real-time mains voltage and detect brown-out events. The brown-out module  405  is connected across the secondary coil of the transformer  415 . The brown-out module  405  includes a level shifter  430  that is followed is followed by a peak detector  435 . The peak detector output  440 , VLINE_PEAK_SAMPLE, is provided to the controller  240  to monitor for the occurrence of a brown-out or brown-in condition. 
       FIG. 7  illustrates a battery charger power stage circuit module  500 . The circuit module  500  receives power from the main output of the mains power supply circuit module  400  and provides charging current to the positive terminal, VBATT+, of the battery. The circuit module  500  receives a charger PWM signal from the controller  240  The charger PWM signal is operable to control the conductive state of a charging switch  505  to produce a desired charging current. 
       FIG. 8  illustrates a battery charger battery voltage detection circuit module  510 . The voltage detection circuit module  510  monitors the voltage of the positive terminal, VBATT+, of the battery. The voltage of the battery, VBATT+, is provided through a switch  515  to a voltage divider circuit  520  and a non-inverting amplifier  525 . The output of the amplifier  525  is filtered by a low-pass RC filter  530  and a sampled battery voltage, VBATT_SAMPLE, is provided to the controller  240 . 
       FIG. 9  illustrates a battery charger charge current sensing circuit module  535 . The charge current sensing circuit module  535  measures a charge current that is provided to the battery. The charge current is measured across a resistor, R 50  (see  FIG. 7 ), by measuring the voltage across the resistor, R 50 . The voltage is provided to a current sensing integrated circuit  540 , which provides a sampled current value to the controller  240 . 
       FIG. 10  illustrates a battery charger battery temperature sensing circuit module  545 . The temperature sensing circuit module  545  measures the temperature of the battery to determine whether the battery is at an appropriate temperature for charging (e.g., not too cold or too hot). The temperature of the battery can be determined using a negative temperature coefficient (“NTC”) resistor. The voltage of the temperature sensor is provided to a unity buffer amplifier  550 , and a voltage indicative of the temperature of the battery, NTC_SAMPLE, is provided to the controller  240 . 
       FIG. 11  illustrates a battery charger voltage qualification circuit module  555 . The circuit module  555  receives power from the main output of the mains power supply circuit module  400 . Two voltage divider circuits  560  and  565  are implemented so the controller  240  can determine whether an under-voltage condition exists (monitored by the controller as MO_UVLO) or an over-voltage condition exists (monitored by the controller as MO_OVP). 
       FIG. 12  illustrates a battery charge battery presence circuit module  570 . The circuit module  570  is operable as a constant current sink that can be used to detect the presence of a battery in the emergency lighting unit  100 . The controller  240  provides a battery discharge signal, BATTERY_DISCHARGE, to the gate of a transistor  575  to create a conductive path from the battery, VBATT+, to ground. 
       FIG. 13  illustrates a circuit diagram of the light source  225 . As discussed above, in some embodiments, the light source  225  includes the plurality of lights  110 . In such an embodiment, the plurality of lights  110  include a first light group  115  and a second, or emergency, light group  120 . The first light group  115  is electrically connected to a first light group input  615  and a first light group output  620 . The second light group  120  is electrically connected to a second light group input  625  and a second light group output  630 . In some embodiments, the second light group  120  is an emergency light group. 
     In some embodiments, the second light group  120  includes lights  121   a,    121   b,    121   c , and  121   d.  In such an embodiment, lights  121   a - 121   d  may be LEDs. Additionally, in some embodiments, each light  121   a - 121   d  is electrically connected to a shunt control circuit  635   a ,  635   b,    635   c,  and  635   d,  respectively. As illustrated, the shunt control circuits  635   a - 635   d  are electrically connected to an input and an output of each light  121   a - 121   d  respectively. The shunt control circuits  635   a - 635   d  are configured to provide an alternate current path in case any of the lights  121   a - 121   d  fail. Thus, during a failure of an individual light, the remaining lights of the second light group  120  may continue to operate. 
       FIG. 14  illustrates a light switching circuit module  700 . The light switching circuit module  700  is configured to selectively provide power to the plurality of lights  110 . In some embodiments, the light switching circuit module  700  selectively provides power to either, both the first light group  115  ( FIG. 13 ) and the second light group  120  ( FIG. 13 ), or only the second light group  120  ( FIG. 13 ). In another embodiments, the light switching circuit module  700  may selectively provide power to one of the first light group  115  ( FIG. 13 ) or the second light group  120  ( FIG. 13 ). The light switching circuit module  700  includes a battery input  705  (VBATT+), an LED driver input  710  (AC LED DRV OUTPUT+), an emergency LED output  715  (EM_LED+), an LED output  720  (LED_ARRAY+), an LED input (LED_ARRAY−)  722 , a relay  725 , a switch  730 , and an emergency control input  735 . 
     The battery input  705  is configured to receive power from the battery  215 . In some embodiments, the battery input  705  receives power from the VBATT+ output illustrated in  FIG. 7 . The LED driver input  710  is configured to receive power from an output of the driver  220 . An activation/deactivation signal is received at the emergency control input  735 . In some embodiments, the activation/deactivation signal is output from controller  240 . During normal operation, an activation signal is received at the emergency control input  735 . The activation signal turns the switch  730  on, thus activating relay  725 . When relay  725  is activated, power received from the output of the driver  220  is used to power the first light group  115  ( FIG. 13 ) and the second light group  120  ( FIG. 13 ). In some embodiments, during normal operation, power is output from LED output  720  (LED_ARRAY+) to the first light group input  615  ( FIG. 13 ), through the first light group  115  ( FIG. 13 ), then output from first light group output  620  ( FIG. 13 ) to the LED input (LED_ARRAY−)  722 . Power is then output from emergency LED output  715  (EM_LED+) of the light switching circuit module  700  to the second light group input  625  ( FIG. 13 ), and through the second light group  120  ( FIG. 13 ). 
     During emergency mode, a deactivation signal is received at the emergency control input  735 . The deactivation signal turns switch  730  off, thus deactivating relay  725 . When relay  725  is deactivated power received at the battery input  705  is used to only power the second light group  120  ( FIG. 13 ). In some embodiments, during emergency mode, power is output from the emergency LED output  715  (EM_LED+) of the light switching circuit module  700  to the second light group input  625  ( FIG. 13 ), and through the second light group  120  ( FIG. 13 ). 
       FIG. 15  illustrates a driver power switch  800 . The driver power switch  800  is configured to selectively control power supplied to the driver  220 . In some embodiments, the driver power switch  800  is configured to provide a relay time between the AC power (supplied by the LED driver) and the emergency power (supplied by the battery  215 ) being applied to the lights  110 . Such a relay time may be used to ensure that the LED driver input  710  and the emergency LED output  715  are not electrically connected during transfer. Additionally, the driver power switch  800  may be configured to prevent an open circuit condition at the connection between the LED driver and the lights  110 . 
     The driver power switch  800  includes a driver control signal input  805 , a driver control switch  810 , a driver control relay  815 , a switched AC line input  820 , and an AC LED driver output  825 . During normal operation, a driver deactivation signal is received at the driver control signal input  805 . When the driver deactivation signal is received, the driver control switch  810  is turned off, thus deactivating the driver control relay  815 . When the driver control relay  815  is deactivated, power is provided from the switched AC line input  820 , through the AC LED driver output  825 , to the driver  220 . During emergency mode, a driver activation signal is received at the driver control signal input  805 . When the driver activation signal is received, the driver control switch  810  is turned on, thus activating the driver control relay  815 . When the driver control relay  815  is deactivated, power to the driver  220  is prohibited by opening the contacts of the driver control relay  815 . 
       FIG. 16  illustrates an LED driver IC module  900 . The IC module  900  is configured to control the driver  220 . The IC module  900  includes LED driver IC  905  having analog dimming interface, NDIM, that enables setting output constant current by providing a reference voltage that is proportional to the desired output current. The output current is then controlled by the GATE_DRIVE signal, output from a GATE_DRIVE output  915  of the IC  905 , as described above with respect to  FIG. 14 . The LED driver IC  905  may also include LED_DRIVER_EN inputs  910 . In some embodiments the LED driver IC  905  is configured to receive one or more signals from the controller  240  at the LED_DRIVER_EN inputs  910 . In such an embodiment the one or more signals may enable and/or disable the LED driver IC  905 . 
       FIG. 17  illustrates an LED string voltage detection circuit module  950  for monitoring the voltage of the LEDs. The LED_DRIVER_OUTPUT voltage is provided from the light switching circuit module  700  to the LED string voltage detection module  950 . The voltage of the LEDS, LED_DRIVER_OUTPUT, is provided to a voltage divider circuit  955  and a non-inverting amplifier  960 . The output of the amplifier  960  is filtered by a low-pass RC filter  965  and a sampled battery voltage, VLED_SAMPLE, is provided to the controller  240 . 
       FIG. 18  is a flowchart illustrating a process  1000  of the system  100  according to some embodiments of the application. In normal operation, both the first light group  115  and the second light group  120  are activated (step  1005 ). The brown-out module  405  continually monitors the line voltage (step  1010 ). The brown-out module  405  determines if a brown-out has occurred (e.g., has the line voltage dropped below a threshold) (step  1015 ). When a brown-out has not occurred (e.g., when the line voltage is above the threshold), process  1000  cycles back to step  1010  and continues to monitor the line voltage. When a brown-out has occurred, emergency mode signals (e.g., activation/deactivation signal and driver activation/deactivation signal) are output to the light switching circuit module  700  and at the driver power switch  800  (step  1020 ). Once the driver activation/deactivation signal is received at the driver power switch  800 , AC line voltage is disconnected from the driver  220  (via the driver power switch  800 ) (step  1025 ). Additionally, once the activation/deactivation signal is received at the light switching circuit module  700 , emergency mode is entered and power is supplied only to the second light group  120  (step  1030 ). Process  1000  then cycles back to step  1010  and continues to monitor the line voltage. 
     Thus, the invention provides, among other things, an emergency lighting system. The emergency lighting system requires less power consumption during brown-out events. By requiring less power consumption during brown-out events, the emergency lighting system may include a relatively small, inexpensive battery. Various features and advantages of the invention are set forth in the following claims.