Patent Publication Number: US-8974079-B2

Title: Lighting system with integrated EL panel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 13/299,588, filed 18 Nov. 2011, and this application claims the benefit of U.S. Provisional App. No. 61/489,527, filed 24 May 2011, both of which are incorporated herein by reference and to which priority is claimed. 
    
    
     BACKGROUND 
     Commercial and residential buildings use lighting throughout rooms, hallways, corridors, and other areas to illuminate these locations. During power failures or emergencies, certain lighting can be maintained in the building although the majority of fixtures are not illuminated. This emergency lighting helps illuminate exits and escape routes. Typically, power to illuminate the emergency lighting is provided by a backup power source, such as a generator, battery, or other power line. Unfortunately, not all areas of a building can be illuminated by the emergency lighting system because this would require extensive implementation of the needed components. 
     When commercial and residential buildings are only partially occupied or empty, such as at night, the need for illuminating certain areas greatly diminishes. For this reason, sometimes only portions of the building&#39;s lighting is illuminated to conserve power, while still maintaining at least some illumination for safety and security reasons. Being able to partially illuminate areas of a building to conserve power and to prolong the life of fluorescent or other lights by alleviating nighttime workload can be a great benefit. 
     What is needed is a way to inexpensively provide emergency or ancillary lighting for commercial and residential applications that can be incorporated into the existing fixtures of such buildings. 
     SUMMARY 
     To that end, a lighting system as disclosed herein is intended to provide emergency or ancillary lighting for commercial and residential applications. The lighting system can be incorporated into existing fixtures or features of such buildings. The lighting system has a receptacle for a light source disposed on a light fixture. Various types of light sources and light fixtures can be used. The receptacle couples to a first power source, such as standard alternating current available in a building. An electroluminescent (EL) panel is disposed adjacent the light fixture and couples either to the same first power source, to a second power source, such as a direct current emergency power source of a battery or a building, or to both the first and second power sources. This EL panel can be disposed on a shade or a reflector disposed on the light fixture, or the EL panel can be disposed on a ceiling tile or some other location in the building. Moreover, the EL panel can be used in an exit sign of an emergency monitoring system. 
     For the EL panel coupled to the first power source, circuitry illuminates the electroluminescent panel with power from the first power source when the receptacle for the light source is disconnected from the first power source. For the EL panel connected to the second power source, the circuitry illuminates the EL panel with power from the second power source during a failure of the first power source. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a fluorescent light fixture having electroluminescent (EL) panels according to the present disclosure. 
         FIG. 2  shows components of electroluminescent panel in an exploded view. 
         FIGS. 3A-3B  shows another fluorescent light fixture having an EL panel according to the present disclosure. 
         FIGS. 4A-4B  shows an incandescent light fixture having an EL panel according to the present disclosure. 
         FIG. 5  shows another incandescent light fixture having an EL panel according to the present disclosure. 
         FIG. 6  shows an acoustic ceiling tile having an EL panel according to the present disclosure. 
         FIG. 7  schematically illustrates a lighting system according to the present disclosure. 
         FIGS. 8-14  show control circuitry for the disclosed EL panel. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a fluorescent light fixture  30  having one or more electroluminescent (EL) panels  10   a - b  according to the present disclosure. This fluorescent light fixture  30  can be similar to those used in commercial settings. Accordingly, the fixture  30  has fluorescent light tubes  34  installed in receptacles or sockets  35  for the tubes  34 , and the receptacle  35  couple to conventional circuitry  36  and a power supply  40  for illuminating the tubes  34 . Although fluorescent tubes  34  are shown, any of a number of light sources can be used, such as incandescent lights, compact fluorescents (CFL), light emitting diodes (LED), halogen light, etc. As is typical, the power supply  40  can be standard NC power provided in a building or the like, and the power circuitry  36  can use a ballast to regulate current, such as an inductor for A/C power. 
     Here, an EL panel  10   a  can be attached to the inner surface of the fixture&#39;s reflective surface  32 . The EL panel  10   a  can be attached to the entire reflector  32  or just a portion thereof, and adhesive, fasteners, or the like can be used to attach the panel  10   a  to the reflector  32 . Any adhesive used is preferably heat activated. The other EL panel  10   b  can be attached to an outer surface of the fixture  30  if present. In general, the fixture  30  can have one or both of the panels  10   a - b  in these positions. 
     The EL panels  10  couple to EL power circuitry  20 , which provides the necessary supply of alternating current to illuminate the EL panels  10  as discussed herein. The circuitry  20  can be powered and controlled from the fluorescent circuitry  36 . Alternatively, the circuitry  20  can be directly connected to the building&#39;s power supply  40 . Still further, the circuitry  20  can be connected to an auxiliary power supply  42 , such as an emergency power supply for the building. 
     When the fixture  30  is on, the fluorescent circuitry  36  draws power from the power supply  40  and illuminates the fluorescent tubes  34 . While these tubes  34  are “on,” the EL panels  10   a - b  may or may not be illuminated, although they are preferably not illuminated. Instead, when the tubes  34  are “off,” the EL panels  10   a - b  are preferably illuminated to provide ancillary or backup lighting, either at night, during an emergency, or for some other reason. Thus, turning “on” and “off” the EL panels  10   a - b  can coincide with the reverse turning “off” and “on” of the light fixture  30  or can coincide with a switch to change from the convention power supply  40  to the emergency power supply  42 . 
     Details of an electroluminescent (EL) panel  10  are shown in  FIG. 2 , which presents the components of an EL panel  10  in an exploded view. As is known, electroluminescence directly converts electric energy to light using a solid phosphor subjected to an alternating electric field. The EL panel  10  functions when phosphor particles are excited by an electrical field generated by applying an alternating current to front and back electrodes that sandwich a phosphor layer. The front and rear electrodes simply pass the electrical current and do not convert this into any other form of energy, such as heat or ultraviolet radiation. 
     The panel  10  has a front electrode layer  12 , a rear electrode layer  14 , a dielectric insulating layer  16 , and a microencapsulated solid phosphor layer  18 . The EL panel  10  illuminates when the microencapsulated solid phosphors in the phosphor layer  18  are excited by an alternating electrical current (AC). In particular, alternating current is applied to the front and rear electrode layers  12 / 14  by leads  13 / 15 , and an electromagnetic (EM) field is created that excites the phosphor layer  18  to produce luminous energy. 
     The EL panel  10  operate with relatively little current, which makes it well suited for light sources that operate continuously or for extended periods of time. The EL panel  10  essentially operates as a capacitor with its dielectric layer  16  and phosphor layer  18  disposed between the two conductive electrodes  12  and  14 . The front layer  12  is typically transparent. 
     Details related to electroluminescent elements are provided in U.S. Pat. Nos. 5,662,408; 5,816,682; and 7,191,510, which are incorporated herein by reference in their entireties. For example, the transparent front electrode  12  can be made out of indium tin oxide. The phosphor layer  18  has encapsulated phosphor screen-printed over the front electrode  12 . The dielectric layer  16  can contain a solvent, a binder, and barium titanate particles that are screen-printed over the phosphor layer  18 . The rear electrode  14  typically has a solvent, a binder, and conductive particles such as silver or carbon that are screen-printed over the dielectric layer  16 . 
       FIGS. 3A-3B  show another fluorescent light fixture  60  having an EL panel  10 . Here, the fixture  60  is a compact fluorescent lighting fixture having a reflector  62  with a reflecting surface  64  and having a compact fluorescent light  66  installed in a receptacle or socket  65 . The EL panel  10  affixes to the surface  64  of the reflector  62  and connects to the EL power circuitry  20  as discussed herein. 
     As shown in  FIG. 3B , the fluorescent lamp  66  may normally couple to the building&#39;s power supply  40  when “on.” A controller or switch  44  that turns “off” the power to the lamp  66  instead connects the EL circuitry  20  to the power supply  40  so the EL panel  10  can be illuminated. Other arrangements to supply power to the lamp  66  and circuitry  20  can be used, as discussed herein. 
       FIGS. 4A-4B  shows an incandescent light fixture  70  having an EL panel  10  attached outside a lampshade  72  of the fixture  70 , which can be a desk, table, or floor lamp. As shown in  FIG. 4B , the incandescent light  74  installs in a receptacle or socket  75  and may normally couple to the building&#39;s power supply  40  when turned “on.” A controller or switch  44  that turns “off” the power to the light  74  instead connects the EL circuitry  20  to the power supply  40  so the EL panel  10  can be illuminated. Other arrangements to supply power to the lamp and circuitry  20  can be used, as discussed herein. 
     As shown in  FIG. 4A , the panel  10  can affix outside the lampshade  72 , either partially or entirely thereon. Alternatively, it can be affixed inside the lampshade  72 . For example,  FIG. 5  shows another incandescent light fixture  80  having an EL panel  10  attached inside the lampshade or reflector  82  of a desk, table, or floor lamp having an incandescent light  84  installed in a receptacle or socket  85 . 
       FIG. 6  shows a suspended or dropped ceiling system  50  having acoustic ceiling tiles  52 , cross-members or runners  54 , and EL panels  10  according to the present disclosure. The ceiling tiles  52  can be those typically used in commercial buildings for a dropped ceiling. These tiles  52  are typically made of fire resistant and noise dampening material, and they fit into place in the supporting frame of runners  54  hung from the building&#39;s ceiling. 
     One or more EL panels  10  attach to the surface of one or more of these ceiling tiles  52  and connect to a power supply (not shown) as noted herein. These EL panels  10  on the tiles  52  can be illuminated when conventional lighting in a building is turned off, during an emergency, or for some other purpose. For example, a group of the panels  10  may be attached to ceiling tiles  52  near an exit. Lined sets of the EL panels  10  on tiles  52  can be used to illuminate and indicate an escape route along the ceiling. These and other possibilities can be used. 
       FIG. 7  schematically illustrates a commercial or residential lighting system  100  according to the present disclosure. Several conventional lighting fixtures  102 , such as discussed previously, couple to the standard power supply  40  for the building. In addition, several emergency lighting fixtures  104  can couple to an emergency power supply  42  for the building. The emergency power supply  42  can be provided by battery, generator, or the like. The emergency light fixtures  104  can be remotely installed fixtures coupled to the power supply  42  by building wiring. In other cases, the emergency light fixtures  104  can have its own local power supply  42  provided by a battery backup. 
     Either associated with or separate from these light fixtures  102 / 104 , the system  100  also has several EL panels  10  with controllers  120  for providing supplemental light during an emergency or other purpose disclosed herein. The number and placement of the various EL panels  10  in a building depend on how large the rooms are, how many light fixtures are present, where illumination is desired, and other considerations. 
     The controllers  120  can generally include the power circuitry discussed previously for providing the necessary power to illuminate the EL panels  10 . Preferably and as discussed in more detail below, these controllers  120  may include some additional circuitry to control the illumination of the EL panels  10 . As shown in  FIG. 7 , the controllers  120  can be coupled to the conventional power supply  40 , to the emergency power supply  42 , or to both. 
     The system  100  also has a central monitoring workstation  110  that couples to the building&#39;s existing wiring and power supplies. This central workstation  110  can include one or more computers and can have its own backup power supply (not shown). The workstation  110  can include conventional features for monitoring the security and safety of a building. For example, the workstation  110  can monitor fire alarms and security alarms of the building. 
     To communicate with the various controllers  120  of the EL panels  10 , the workstation  104  can couple to the controllers  110  via the existing building wiring  102 , dedicated wiring, or wireless communication system. For wireless communication, the controllers  120  of the EL panels  10  have wireless communication devices, such as wireless transceivers known and used in the art. 
     In some instances when an associated fixture  102  is turned “off,” then the EL panel  10  can be illuminated using the main power supply  40 . In other instances, regular power may go out due to an emergency or power failure. In this case, the EL panel  10  can use emergency power  42  to switch “on” either from the buildings emergency wiring or a backup battery. The controller  120  can also increase the brightness of the EL panel  10  when using the backup power from the emergency wiring or battery. For example, the regular power supply  40  can be 120 Volts, 60 Hz. The brightness of the EL panel  10  during regular AC power operation can be from about 3.5 to 5 fL (foot lamberts). When switched to backup power supply  42 , the brightness of the panel  10  can be increased to 7 fL (foot lamberts) during emergency DC power operation. 
     The controllers  120  control the brilliance of the EL panels  10  as discussed below. In one technique, the controller  120  can control the voltage applied to the EL panel  10 . By increasing the voltage, the controller  120  can increase the element&#39;s brilliance, although this is not a preferred way to increase the brilliance. 
     In another technique, the controller  120  modifies the waveform used to operate the EL panel  10 . In general, a sharper rise time of the waveform increase the brightness of the EL panel  10 . The controller  120  can modify the sine wave with faster rising edges to change the RMS voltage used for the EL panel  10 . This increases the brilliance of the EL panel  10  with all other parameters held constant. Yet, this technique may shorten the life of the EL panel  10  so that it may not be preferred in some implementations. 
     In yet another technique, the controller  120  can control the brilliance of the EL panel  10  by increasing the frequency of the sine wave used. To do this, the controller  120  is programmed with power control algorithms so the controller  110  can control the waveform and frequency of the sine wave used to operate the EL panel  10 . Using PWM (pulse width modulation) signaling and a low pass filter, the controller  110  creates a waveform at a desired frequency. In general, the higher the frequency produced by the controller  120 , the brighter the EL panel  10  will illuminate. Preferably, the desired frequency for operating the EL panel  10  is in the range of 50 to 80-Hz. 
     Similar to the monitoring system disclosed in incorporated U.S. application Ser. No. 13/299,588, the monitoring system  100  of the present disclosure can have integrated exit signs (not shown). In preferred implementations, the exit signs have electroluminescent elements, such as the disclosed electroluminescent panels  10  or light emitting capacitors. The exit signs connect to the internal wiring of a building. Local power sources for the each of the exit signs can provide emergency power if the building power is lost, or the signs can uses ancillary back up power lines  42  of the building. 
     Controllers on the exit signs, such as controllers  120  for the EL panels  10 , communicate with the central monitoring workstation  110  using the existing wiring and/or wireless communication. The controllers  120  have one or more automated features for monitoring operation of the exit signs and the surrounding environment. These automated components include one or more of intensity sensor, ambient light sensor, temperature sensor, memory unit, smoke detector, camera, speaker, microphone, motion detector, RFID detector, and the like. Because the exit signs are widely distributed throughout the building, operators, firemen, and the like can get detailed information of the building environment, security, fire, smoke, temperature, etc. The exit signs can store this information locally in memory and can communicate useful information using WI-FI, WLAN, WWAN, LAN, or other form of communication to the central workstation  110 .  FIGS. 8-14  show some of the control circuitry for the controller  120  of the disclosed EL panel  10 , and details of these portions of the control circuitry are discussed below. The control circuitry can also be found in incorporated U.S. application Ser. No. 13/299,588, filed 18 Nov. 2011, claiming the benefit of U.S. Prov. Appl. Ser. No. 61/415,143 filed 18 Nov. 2010 and entitled “Integrated Exits Signs and Monitoring System,” which are incorporated herein by reference in their entireties. 
       FIG. 8  shows a power selection circuit  230 . The circuit  230  uses an O-ring diode  232 , such as the LTC4413-3 available from Linear Technology. This circuit  230  is used to select a backup power  234  from a battery or to select a source power  236  from a main AC input ( FIG. 10 ). Power status  238  is provided by the circuit  230  to a microcontroller discussed below in  FIG. 12 . Additionally, output power  235  is provided by the circuit  230  for the control circuitry. 
       FIG. 9  shows a 5V backup power circuit  240  having a dual channel, synchronized, fixed frequency step-up DC/DC converter  242 . The circuit  240  can use a step-up DC/DC converter  242 , such as the LTC3535 available from Linear Technology. Battery power  246  is received and backup power  244  is provided for the power selection source circuit  230  of  FIG. 8 . 
       FIG. 10  shows an AC power detection circuit  250  coupling to an AC hot line as input. The circuit  250  provides an indication  252  that the AC power is “good” to the microcontroller discussed below in  FIG. 12 .  FIG. 10  also shows the main AC input  254  and 5V power circuit  256  for the control circuitry. 
       FIG. 11  shows a battery charger circuit  260  having a battery charger  262  that couples by a connection to a backup battery  264 . The battery charger circuit  260  can use a linear NiMH/NiCd fast battery charger  262 , such as the LTC4060 available from Linear Technology. 
       FIG. 12  shows a microcontroller  270  for the control circuitry. This microcontroller  270  can be a flash-based microcontroller with onboard EEPROM data memory. One suitable microcontroller  270  is the PIC16F684 available from Linear Technology. The microcontroller  270  couples to signal inputs and outputs for the control circuitry and is programmed in accordance with the functions described in the present disclosure. 
     As noted previously, the brightness of the EL panel ( 10 ) can be increased when the frequency is increased. To that end, the microcontroller  270  can be programmed to create the waveform for operating the EL panel ( 10 ) using pulse width modulation (PWM) signals. The microcontroller  270  reduces the time interval between each pulse. For a sine wave, the time that the PWM pulse is “ON” is the sine of the position of the PWM pulse divided by the period of the waveform. The time it is “OFF” is the difference of the period of the PWM pulse less the time it is “ON.” The microcontroller  270  modifies the intervals of the pulses to control the brightness of the EL panel ( 10 ) with a preferred waveform and frequency as discussed previously. 
       FIG. 13  shows a relay circuit  280  having a relay  282  for switching between AC power and switcher current. The relay  282  is controlled by a coil command from the microcontroller  270  of  FIG. 12 . 
       FIG. 14  shows power circuitry  290  having a PWM DC/DC converter  292 , a transformer  294 , and a switching diode  296  for the control circuitry. The PWM DC/DC converter  292  can use an LT3580 available from Linear Technology. The switching diode  296  can be a Dual In-Series Small-Signal High-Voltage Switching Diode series GSD2004S available from VISHAY Semiconductors. 
     Poles ( 7 - 8 ) of the transformer  294  connect to the Overvoltage Protection Sense Input (OVI) and Overvoltage Protection Output (OVP) pins on the O-ring diode ( 232 ) of  FIG. 8 . Poles ( 1 - 5 ) of the transformer  294  and switching diode  296  connect to pins for the second channel on the step-up DC/DC converter ( 242 ) of the backup power circuit ( 240 ) of  FIG. 9 . The pins include the second channel&#39;s battery input voltage (VIN 2 ), the logic controlled shutdown input (SHDN 2 ), the output voltage sense and drain of the internal synchronous rectifier (VOUT 2 ), the feedback input to the g m  Error Amplifier (FB 2 ), and the switch pin (SW 2 ). 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.