Abstract:
An ignitor monitoring device is provided which is enclosed within a housing to allow for portability while testing high intensity discharge (HID) luminaires. The device is placed in the lamp socket with the lamp removed, and measures the open circuit voltage across the ignitor, as well as the ignitor&#39;s ignition pulse. If the ignitor monitoring device detects adequate voltage to enable ignition of the lamp, the LED illuminates; otherwise, the LED fails to illuminate, and the operator can begin troubleshooting by replacing the ignitor and re-testing the luminaire, or testing the source, among other troubleshooting methods known in the art. A first housing employs a plunging mechanism that allows the operator to insert the monitoring device into the lamp socket with ample pressure to ensure electrical conduction between the device and the luminaire. A second housing employs a screw-in delivery system, similar to a conventional light bulb, to facilitate coupling and electrical conduction between the device and the luminaire.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to an ignitor monitoring device disposed within a housing that is independent of the luminaire. More specifically, the invention provides for a device that tests for the presence of a hot re-strike ignitor pulse having a minimum threshold voltage.  
         BACKGROUND OF THE INVENTION  
         [0002]    High intensity discharge luminaires, hereinafter referred to as HID luminaires, are commonly installed at high locations at commercial or industrial facilities such as on the ceiling of a warehouse or plant, or on light poles in a parking lot or stadium. HID luminaires can include, but are not limited to, metal halide (MH) lamps, and high pressure sodium (HPS) lamps. Some MH luminaires and all HPS luminaires use pulses from a high voltage source such as an ignitor circuit to ignite the lamp.  
           [0003]    In many applications, the HID luminaires can be elevated on the order of thirty feet or more above the ground or floor of a commercial or industrial facility. The elevation of the luminaires makes repairs of malfunctioning luminaires inconvenient and time consuming since service personnel must ascend to considerable heights in order to gain access to the luminaires, assess the problem and then repair or replace the defective components of the luminaire. The malfunctioning of the HID can be attributable, for example, to a defective lamp starting circuit, also referred to as an ignitor. Specifically, if the ignitor does not produce a minimum threshold voltage, the lamp does not illuminate, thereby failing to establish initiation of the arc.  
           [0004]    A number of devices exist to facilitate the assessment of a malfunctioning luminaire. For example, U.S. Pat. No. 4,496,905, to Forte et al., discloses an ignitor testing device with indicator lights to inform the user of various possibilities for luminaire failure. The device replaces the lamp in the luminaire housing, thus measuring the voltage provided across the lamp. In addition, the ignitor testing device employs a circuit with multiple elements in order to assess the positive and negative waveforms of the open circuit voltage signal. These multiple elements require a larger surface area on the circuit board and therefore a larger housing, which makes the device less portable. Thus, a need exists for an ignitor monitoring device that employs fewer elements in order to facilitate a smaller housing.  
           [0005]    Further, the ignitor producing the open circuit voltage disclosed in U.S. Pat. No. 4,496,905 is not a hot re-strike ignitor, but rather a standard ignitor that is only able to re-strike after 45 seconds to 1.5 minutes, that is, only after sufficient time has elapsed for the lamp portion of the luminaire to cool down. Therefore, a need exists for an ignitor monitoring device that is able to test a hot re-strike ignitor yet maintain the portability function, as mentioned above. Such a hot re-strike ignitor is disclosed for example, in U.S. Pat. No. 5,047,694 to Nuckolls et al., and U.S. Pat. No. 5,321,338 to Nuckolls et al., the contents of both being incorporated herein by reference.  
           [0006]    U.S. Pat. No. 6,127,782, to Flory, IV et al., also discloses an ignitor monitoring device that provides an indication of sufficient open circuit voltage to operate the ignitor. In contrast with the ignitor monitoring device disclosed in U.S. Pat. No. 4,496,905, the ignitor monitoring device disclosed in U.S. Pat. No. 6,127,782 is externally mountable to the luminaire housing. Thus, rather than replacing the lamp via a removable test housing, a receptacle that is distinct from the lamp socket, is provided to enable the ignitor monitoring device to be attached to the luminaire housing. Thus, each lamp has an attached and dedicated ignitor monitoring device. Accordingly, a need exists for a portable ignitor monitoring device with various delivery systems that can be readily coupled and uncoupled to different luminaires for troubleshooting purposes.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention overcomes the deficiencies of existing ignitor monitoring devices and realizes a number of advantages over these devices. An ignitor monitoring device is provided in accordance with the present invention that is portable to enable testing of different luminaires for the presence of an ignitor pulse via a pulse voltage associated with the lamp, therein. The ignitor monitoring device of the present invention is disposed on a circuit board within a housing that has two embodiments, for example, comprising a screw-in delivery housing and a plunger delivery housing.  
           [0008]    The ignitor monitoring device of the present invention, for example, comprises a voltage threshold circuit, a gating circuit, an indicator device, a signal conditioning circuit, and a current discharge circuit. The voltage threshold circuit is operable to determine whether the pulse voltage is a minimum threshold voltage, thereby indicating if the ignitor is striking at a sufficiently high voltage level to operate the lamp. The gating circuit is operable to conduct current when the open circuit voltage reaches the minimum threshold voltage, thereby allowing the indicator device to illuminate and indicate a sufficient ignitor pulse for lamp operation, as well as hot re-strike capability. The current discharge circuit is also operable to discharge residual current within the ignitor monitoring device. This discharge circuit is a safety feature to dissipate the residual charge on the circuit board within the housing thereby reducing the risk of exposing the user of the ignitor monitoring device to electrocution.  
           [0009]    The present invention also provides a method for testing one of a plurality of luminaires for the presence of an ignitor pulse via a pulse voltage associated with the luminaires. The method comprises, first, determining whether the pulse voltage is a minimum threshold voltage and secondly, conducting current through a gating circuit such as an SCR when the pulse voltage is at the minimum threshold voltage. The method also comprises illuminating an LED in response to current flow indicating the ignitor is maintaining a minimum voltage pulse.  
           [0010]    In accordance with an aspect of the present invention, the ignitor monitoring device is disposed on a circuit board within a housing that is external to the luminaire. In addition, the housing couples and decouples via a plunger device or a screw-in device, allowing for ease of use when testing.  
           [0011]    In accordance with another aspect of the present invention, the ignitor monitoring device monitors the ignitor pulse on every positive one-half cycle of the waveform, thus allowing use of fewer components.  
           [0012]    In accordance with another aspect of the present invention, the ignitor monitoring device is provided for use with a hot re-strike ignitor, as opposed to a conventional HID lamp ignitor requiring a cool down period before re-striking can occur. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    These and other aspects, advantages and novel features of the invention will be more readily appreciated from the following detailed description when read in conjunction with the accompanying drawings, in which:  
         [0014]    [0014]FIG. 1 is a schematic diagram depicting an ignitor monitoring device coupled to the luminaire constructed in accordance with an embodiment of the present invention;  
         [0015]    [0015]FIG. 2 is a schematic diagram of an ignitor monitoring device constructed in accordance with an embodiment of the present invention;  
         [0016]    [0016]FIG. 3 is a timing diagram illustrating the voltage threshold of the ignitor of FIG. 2 within an HID luminaire;  
         [0017]    [0017]FIG. 4 is an exploded perspective view of an ignitor monitoring device and its housing constructed in accordance with an embodiment of the present invention;  
         [0018]    [0018]FIG. 5 is a cross-sectional side view of a plug-in ignitor monitoring device disposed on a circuit board within a housing constructed in accordance with an embodiment of the present invention;  
         [0019]    [0019]FIG. 6 depicts the front end of the housing enclosing the ignitor monitoring device taken along lines  6 - 6  of FIG. 5 and constructed in accordance with an embodiment of the present invention;  
         [0020]    [0020]FIG. 7 illustrates the back end of the housing depicting the ignitor monitoring device taken along lines  7 - 7  of FIG. 5 and constructed in accordance with an embodiment of the present invention;  
         [0021]    [0021]FIG. 8 illustrates a threaded housing for an ignitor monitoring device constructed in accordance with a first embodiment of the housing of the present invention; and  
         [0022]    [0022]FIG. 9 depicts a top view of the threaded housing taken along lines  9 - 9  of FIG. 8 and constructed in accordance with a second embodiment of the housing of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    [0023]FIG. 1 depicts an assembly  5  comprising a High Intensity Discharge (HID) luminaire  10  coupled to an ignitor monitoring device  45  constructed in accordance with a preferred embodiment of the present invention. The lamp  30  that is typically associated with the luminaire  30  is shown in phantom to illustrate use of the ignitor monitoring device  45  of the present invention. An AC source  15  is connected across the primary winding  18  of the lamp ballast  20  and the HID lamp  30  in a conventional manner. The ignitor monitoring device  45  is connected across the secondary winding  19 , thereby allowing the device  45  to measure an open circuit voltage across a lamp  30  as provided by ballast  20 . This operation is discussed in further detail below.  
         [0024]    The ballast  20  of FIG. 1 provides the step-up transformation of voltage for the ignitor  40 . The ballast  20  and the HID lamp  30  are in a series circuit relationship with one another across the AC power source  15 . The primary winding  18  and the secondary winding  19  are inductively coupled via the steel core  17 . As is readily apparent to one skilled in the art, the primary winding  18  has a greater number of turns than secondary winding  19 . A tap  25  is provided at a point in the winding  18  and the secondary winding  19 , which is preferably on the order of about 5 % of the total number of turns of the primary winding  18 .  
         [0025]    The ignitor  40  is connected to the lamp  30 , the ballast  20  and common  35  in a conventional manner. In addition, the ignitor  40  is preferably a hot re-strike ignitor, thus allowing the ignitor  40  to re-strike a hot de-ionized lamp  30  on the order of about three seconds. This is in contrast to a conventional ignitor which can require as many as 1.5 seconds to elapse between ignition pulses in order to allow the circuitry to dissipate excess heat.  
         [0026]    As is discussed in further detail below, the ignitor monitoring device  45  can be disposed in various housings to provide for a compact and portable test device. This compact size and portability are important features of the present invention since the HID luminaires  10  are typically elevated on the order of about thirty feet or more above ground level. In addition, the ignitor monitoring device  45  comprises an LED that illuminates when the ignitor pulse, as depicted in FIG. 3 and described herein, is adequate to ignite the lamp  30 . This allows for rapid assessment of the ignitor status.  
         [0027]    Referring now to FIG. 2, which depicts a detailed schematic of the ignitor monitoring device  45  of FIG. 1, the device  45  is enclosed within a portable housing, described below, and is preferably coupled to the lamp terminals  50  and  55  with the lamp removed from the energized ballast  20 . The negative terminal  50  of the device  45  is coupled to the line connection for the lamp  30 , and the positive terminal  55  of the device  45  is coupled to the common  35  or neutral connection of the lamp  30 , thus creating an overall reverse polarity characteristic to the device  45 . Capacitor  60  is charged via the ignitor pulse shown in FIG. 3 with this reverse polarity to ensure sufficient voltage to overcome the voltage threshold of zener diode  65 , whose operation is further discussed below. Capacitor  56  is also charged via the 60 HZ AC source  15  to act as an energy source for the illumination of LED  70 . Diode  75  is a half-wave bridge to ensure consistent polarity as required by the LED  70 . The reverse polarity ensures activation of LED  70 , which requires conduction in only one direction. As is known to those skilled in the art, an LED provides for current flow from anode to cathode in a unidirectional fashion. Thus, when a forward voltage is applied, the LED conducts, and when a reverse voltage is applied, conduction ceases or reverse breakdown occurs. Thus, the reverse polarity assists in achieving the adequate required breakdown voltage of zener diode  65 , as well as ensuring sufficient current loop energy for illumination of the LED  70 .  
         [0028]    Capacitor  60  and capacitor  82  function as a voltage divider to distinguish between ignitor pulses of sufficient voltage and ignitor pulses lacking sufficient voltage. Accordingly, capacitor  60  facilitates throughput of sufficient voltage ignitor pulses, as shown in FIG. 3. The SCR  80  operates in a conventional manner. For example, the SCR  80  is controlled from an off state to an on state via a third terminal or gate. Thus, once the SCR is turned on, it conducts even after removal of the gate signal, as long as a minimum holding current is maintained in the rectified circuit. Therefore, the current flows through SCR  80  and LED  70 , since the anodes and cathodes of these two components are in similar directions, to ensure the correct polarity.  
         [0029]    In a preferred embodiment of the present invention, a signal conditioning circuit is preferably provided comprising diode  75 , resistor  85 , and capacitor  56 , wherein capacitor  56  is charged every other half-cycle through diode  75  and resistor  85 . The current path continues through resistor  90  which preferably employs capacitor  56  to limit the stored energy, as well as to provide a discharge path when the testing device  45  is removed from the lamp socket.  
         [0030]    During operation of the ignitor monitoring device  45 , which is placed in the lamp socket in place of the lamp  30 , the device  45  measures a voltage resulting from the ignitor pulse of the ignitor  40 . As shown in FIG. 3, if the ignitor is functioning properly, it outputs a voltage level on the order of about 7000 Volts to provide adequate ignition energy for the lamp  30 . An embodiment of the present invention employs a hot re-strike ignitor, thereby allowing the ignitor to operate every three to five seconds until the lamp is turned on. Accordingly, zener diode  65  conducts upon application of sufficient voltage, as preferably provided by the energy stored in capacitor  60 . Current conducts through resistor  95 , providing sufficient current to gate SCR  80 . Upon conduction of SCR  80 , capacitor  56  discharges via LED  70  and resistor  100 . This current flow allows LED  70  to illuminate if the ignitor pulse voltage is on the order of about 7000 V, thus indicating an adequate ignitor pulse for ignition of the lamp  30 . Therefore, when the operator places the ignitor device  45  within the luminaire  10  and the LED  70  illuminates, the operator knows the ignitor is functioning properly. However, if the LED  70  fails to illuminate, the operator can begin troubleshooting by replacing the ignitor  40 , or checking condition of the supply  15 .  
         [0031]    To prevent the risk of shock when the user is removing the ignitor monitoring device  45  from the lamp socket, various components are employed to discharge any residual stored energy. Specifically, resistor  110  is preferably employed to provide an adequate discharge path for capacitor  60 . In addition, capacitor  82  discharges through resistors  85 ,  90 ,  110 , and  120 .  
         [0032]    Illustrative values for the resistors  85  and  90 , along with all the components of the ignitor monitoring device are detailed in Table 1 below.  
                                                       capacitor 56   5.6 mf           capacitor 60   0.1 mf           capacitor 82   250 pf           resistor 85   270 Kohms           resistor 90   6.8 Mohms           resistor 95   360 ohms           resistor 100   2.2 Kohms           resistor 110   2.7 Mohms           resistor 120   10 Mohms           Diode 75   GPO2-40 (4 kV)           Zener Diode 65   100 V           SCR 80   S6025 (600 V, 25 A           LED 70   HPWAMH                      
 
         [0033]    The ignitor monitoring device  45  is preferably located on a circuit board which is further disposed within an assembly  138 . FIG. 4 depicts an exploded view of the circuit board  130  within an assembly  138  constructed in accordance with a preferred embodiment of the present invention. The assembly  138  comprises the removable circuit board  130  which embodies the schematic of FIG. 2, a substantially cylindrical threaded end cap  140 , located at a first end coupled to a metal ring  145 , a plunger device  150 , a flexible metal spring  160 , a substantially cylindrical plastic ring  170 , an arcuate metal conductive ring  180 , a plastic substantially cylindrical housing  190 , and a plastic first end cap  210  located proximate to the circuit board and distal to the substantially cylindrical second end cap  140 .  
         [0034]    The substantially cylindrical housing  190  is composed of a hard plastic with, for example, three levels of grading at the end distal to the substantially cylindrical end cap  140 . The first grading level  194  is substantially cylindrical and has an outer surface  194   a . Surface  194   a  comprises two arcuate holes  193  and  195 , and are adapted to receive two small springs  194   b  and  194   c , respectively, spring  194   b  is adapted to provide the circuit board  130  with adequate electrical connection to test the luminaire  10 , via conductive ring  180 . The next grading level  196  is substantially cylindrical and has a diameter larger than grading  194 . Furthermore, level  196  has an outer surface  196   a  and an end surface  196   b . However, grading  196  has only one hole  197  in end surface  196   b  to facilitate an electrical connection for the circuit board  130 . Hole  196  is adjacent hole  193  and allows an electrical wire to extend from circuit board  130  in the interior of assembly  138  through interior channel  130   a  (FIG. 5) and couple to spring  194   b . The last grading level  198 , proximate to the second end cap  210 , contains a hole  192  that can allow access to the circuit board  130  for testing equipment (not shown) if desired, when not in use a screw can be inserted into hole  192  to ensure circuit board  130  stability. The end cap  210  is also provided to ensure the circuit board  130  stability, but also to maintain an enclosed environment for the circuit board  130  to prevent wear and tear. The end cap  210  has three screws  202  to secure the end cap  210  on the housing  190 .  
         [0035]    Referring now to FIG. 5, which depicts a cross-sectional view of the assembly  138 . For clarity, the cross-section does not reflect all of the detail of FIG. 4. Assembly  138  has a substantially cylindrical interior channel  131  defined by surface  131   b  that is adapted to hold circuit board  130 . Channel  131  opens to first end  220  for insertion of board  130  thereto. Channel  131  has a frustoconical surface  133  that is adjacent interior surface  135 . Interior surface  135  is then adjacent substantially cylindrical surface  137 . Surface  137  has a diameter that is larger then surface  135  and the difference in diameter forms surface  135   a . Surface  137  is adjacent threaded opening  139 , which opens to second end  215 . Channel  130   a  extends from frustoconical surface  133  to surface  196   b  as described above.  
         [0036]    Circuit board  130  fits into open end  131   a  and is preferably frictionally held by surface  131   b . However, board  130  can be held in channel  131  by any means desired, such as slots or adhesive. Two wires  130   b  and  130   c  extend from board  130  through channel  130   a  and through channel  131  to second end  215 . A substantially cylindrical metal block  131   c  having a passage way therethrough and an end surface  131   d  fits into passageway  131  and abuts surface  135   a . Spring  160  can be inserted into channel  131  and abuts end  131   d  of block  131   c . The wire  130  couples to spring  160 . Plunger  150  is then inserted into channel  131  and spring  160  is inserted into open end  151  of plunger  150 . End cap  140  is then inserted into second open end  215  and screwed thereinto. Contact portion  153  extends through hole  141  in end cap  140 . The plunger  150  is preferably metal, which allows electrical connection from circuit board  130  through wire  131   c  to plunger  150 .  
         [0037]    Ring  180  is large enough to fit around level  194  and is biased off center from main longitudinal axis  181  by springs  194   b  and  194   c . Ring  180  is held onto level  194  by ring  170  which is sized to frictionally engage surface  194   c.    
         [0038]    In operation, second end  215  of assembly  138  is inserted into the lamp socket of the luminaire  10 , with the lamp  30  removed, contact portion  153  of plunger  151  provides an electrical connection with spring  160  provided to facilitate and maintain connection. In addition, ring  180  provides an electrical connection between the side of assembly  138  and the lamp socket. Springs  194   b  and  194   a  biases ring  180  off center from the main longitudinal axis  181  to facilitate electrical conduction.  
         [0039]    [0039]FIG. 6 depicts a plastic front end  215  wherein, the plunger  150  makes electrical connection with the luminaire  10  at terminal  50 . The springs  217  and  216  are provided to offset the metal ring  180  from the main axis  181  of the housing  190 , thus facilitating an electrical connection between the circuit board  130  and the luminaire  10  at terminal  55 . The shape of the front end  215  is substantially cylindrical and is composed of an impermeable, hard plastic.  
         [0040]    [0040]FIG. 7 depicts the second end  220  located distal to the front end  215  as shown in FIG. 6. The second end is illustrated upon removal of the end cap  210 . For illustrative purposes, the circuit board  130  is shown in position as if a luminaire  10  is being tested. Additionally, the circuit board  130  is seated by frictional means between sides  220   a  and  220   b . This allows for simple insertion and removal of the circuit board in case of repair or storage, among other reasons. However, the circuit board  130  may be mounted within the housing by any means known in the art.  
         [0041]    [0041]FIGS. 8 and 9 disclose a second embodiment  250  of the housing employed to enclose circuit board  130 , for ignitor testing purposes. An electrical connection is provided at terminal  260  to facilitate a connection between circuit  130  and the luminaire  10 . Threaded surface  255  assists in providing an additional electrical connection, via the metal threads  255   a - c . The threaded surface  255  is attached in a conventional manner similar to a light bulb, to luminaire  10  within the lamp socket, with the lamp  30  removed.  
         [0042]    [0042]FIG. 9 depicts a top end  270  of FIG. 8 distal to the threaded surface  255 . The circuit board  130  is shown, for illustrative purposes, fixed by means of slots  272   a  and  272   b , however slots  272   a  and  272   b  are not the only means for attachment of circuit board  130  to housing  250 . For example, the circuit board  130  can be secured by frictional forces, adhesive or any other method known in the art.  
         [0043]    Although only several exemplary embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.