Abstract:
A manually operable test switch useful for testing of inverter units installed in fluorescent lighting fixtures, the inverter units providing an emergency lighting capability to the lighting fixtures on interruption of usual mains AC power and the test switch providing an ability to test the condition of the inverter units during normal maintenance activity. Operation of the test switch shorts an LED carried by a housing of the switch, the housing also being formed integrally with an adjustable toothed connector for mounting the test switch to a portion of the lighting fixture. The switch housing mounts an electrical contact element under spring loading from a resilient bushing, the contact being displaceable against the spring loading by manual manipulation of an electrical circuit which includes the inverter unit so that the LED is shorted and lamping driven under normal conditions is illuminated at reduced levels to prove functional use of the lamping and associated circuitry of the inverter unit for worthiness to function on loss of usual AC mains power.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to test switch and pilot light structures generally and particularly to a test switch/pilot light having a light emitting diode which is shorted by a switch, lamping of an emergency fluorescent lighting fixture or the like providing illumination at reduced levels, thereby to test visually the operational worthiness of an inverter unit. 
     2. Description of the Prior Art 
     Fluorescent lighting fixtures of various description including such fixtures generally known as linear fixtures and downlighting fixtures can be provided with battery packs and associated circuitry which operate fluorescent lamping of the fixtures for a minimum period of time on interruption of normal power. Such devices are generally referred to as inverter units, battery/inverter units, or battery/charger board units and will be referred to herein as an inverter unit. Units with which the present test switch can be employed also include ballast load transfer devices and the like which do not include batteries. The present test switch can be used as a remote test switch with any number of emergency lighting fixtures. Present day inverter units often carry maintenance-free, high-temperature nickel-cadmium batteries within sealed housings formed of high impact polycarbonate polymers or steel. Such inverter units are described, for,.example, in U.S. Pat. Nos. 5,202,608 and 5,814,971. Lithonia Lighting, a division of National Service Industries, Inc., of Atlanta, Ga., manufactures and markets inverter units of this type under the POWER SENTRY trademark for particular use with linear fluorescent fixtures and downlighting fluorescent fixtures and particularly such fixtures used in office and industrial environments. Linear fluorescent fixtures such as are manufactured by Lithonia Lighting are known under the designations OPTIMAX; 2PM3N, and GT/SP which identify respectively parabolic troffer fixtures and lensed troffer fixtures which are particularly configured to drive linear fluorescent lamping of the T12 or T8 type, for example. In downlighting fluorescent fixtures, inverter units typically operate compact fluorescent lamps of varying description via the agency of nickel-cadmium batteries permanently sealed within steel enclosures. 
     Test switches have long been used in lighting systems including emergency lighting function such that the condition and operational worthiness of inverter units can be quickly and conveniently determined. In normal operation, a visual signal is usually provided by a light emitting diode which gives off light once the unit is connected to power. Operation of a prior test switch in this environment causes the LED to be extinguished for as long as the test is underway. Prior test switches have included manually operable switch elements which allow inverter units to be tested by reference to a visual signal, such prior test switches having taken other structural configurations than those of the test switches of the present invention and have particularly been more costly to manufacture. In particular, prior test switches of this type have included LED&#39;s and switches in completely separate housings. Other prior test switches have included separate toggle switches and panel-mounted light emitting diodes with further inclusion of structure such as PCB-mounted dome switches with PCB-mounted light emitting diodes. Essentially all such prior devices use a dedicated switch such as a PCB-mounted dome switch to complete a circuit. A particular feature of the present test switches which yield substantial utility in manufacture and assembly is the provision of a switch housing which can essentially be unitarily formed from a polymeric material and which houses an LED and a contact which can be brought into engagement with leads of the LED to provide a visual signal evidenced by continuing lamp operation at reduced output to indicate proper inverter operation. The LED is actually shorted and goes out. The structure so envisioned can be rapidly assembled from a minimum of parts, the resulting structure being capable of remote disposition, for example, a few feet or so, from the inverter unit and lighting fixture so that testing is facilitated. The present invention therefore provides improved test switch assemblies which also include connector structure tied to the switch housing for mounting of the test switch to a portion of the lighting fixture. The assemblies of the present invention also provide structure capable of mounting into a variety of materials such as castings, sheet metal, plastic, etc., over a range of thicknesses with ease and rapidity. The invention thus contemplates improvement over the prior art by way of providing an inexpensive and compact structure having a minimum of parts and which is readily manufactured and assembled at minimum cost. 
     SUMMARY OF THE INVENTION 
     The invention provides embodiments of a test switch and mounting assembly which is particularly useful as a manual switch to determine the condition of an inverter unit used to, provide an emergency lighting capability in fluorescent lighting fixtures. In both linear and downlighting fluorescent lighting fixtures, an emergency capability is provided by means of a sealed inverter housing containing batteries capable of driving fluorescent lamping at a fractional output of full lumen rating to yield optimum, glare-free emergency illumination for a minimum period of time on interruption of normal AC mains power. Inverter units useful in such applications are manufactured and marketed by Lithonia Lighting, a division of National Service Industries, Inc., of Atlanta, Ga., certain examples of the inverter units manufactured by Lithonia being proprietary and being the subjects of U.S. Pat. Nos. 5,202,608 and 5,814,971, the disclosures of which patents are incorporated hereinto by reference. Inverter units useful for providing an emergency lighting capability to both linear and downlighting fluorescent fixtures are marketed by Lithonia Lighting under the trademark designation of POWER SENTRY. 
     The batteries contained within inverter units must be capable of being tested periodically in order to ascertain the condition of the batteries, that is, to determine whether the batteries are sufficiently charged to possess the capability of driving lamping during an emergency occasioned by a power failure. Testing of associated inverter circuitry is also necessary. Embodiments of manually operable test switches configured according to the invention replace conventional test switches used in a similar manner to determine the operational worthiness of inverter units as has been described herein. The present test switches can be inexpensively manufactured relative to the cost of prior switches while retaining all capabilities of prior switches. In manufacture of the present switches, fewer parts are required and those parts can be individually manufactured at reduced cost. Assembly of the several component parts of the present test switches can be more rapidly accomplished in a typical manufacturing environment than those switches of the prior art which are replaced by the present test switches. 
     The present test switches are provided with polymeric housings, typically clear, “plastic” housings having opposing housing portions joined together along one edge for movement relative to each other in the manner of a “living hinge” such that the housing portions can be snapped together once internal switch components have been placed inside the housing. The housings of the present switches are further provided with a connector held to the housing by means of a connecting tie integrally formed of plastic material and molded with the housing and the connector simultaneously. Lengths of cable connect a light emitting diode disposed internally of any one of the several housings, exterior ends of the cable being electrically connected to a molded connector formed of plastic material, the molded connector having internally disposed electrical contacts which mate with contacts located within an inverter unit. The inverter unit is provided with an opening through which a conventional electrical harness extends, the harness having a mating connector which joins to the test switch of the invention in order to form an electrical circuit with internal circuit elements of one of the inverter units. 
     According to the several embodiments of the invention, a substantially box-like housing has a cylindrical housing element formed at one end thereof, the cylindrical housing element receiving a plastic plunger element which can be biased downwardly by finger pressure exerted against portions of the plunger which extend from the cylindrical housing element. Displacement of this plunger causes an electrical contact to complete a circuit with leads emanating from the light emitting diode and joined to the electrical cables which connect with elements to be tested disposed internally of one of the inverter units through the connector mentioned above. The light emitting diode is thus de-energized and the fluorescent tamping is caused to operate at a reduced output, thereby providing an indication of the operational worthiness of the inverter unit. In the event that the condition of the inverter unit is inadequate to provide the necessary emergency lighting function, the fluorescent tamping will not illuminate on operation of the test switch. The test switch can be mounted at a distance from the inverter unit by means of the connector which is integrally forimed with the housing of the test switch, the test switch thus being mountable to portions of the lighting fixture per se or to other structure convenient for access to the test switch for testing purposes. 
     Accordingly, it is a primary object of the invention to provide a manually operable test switch useful in the testing of an inverter unit installed on a fluorescent lighting fixture to provide emergency lighting capabilities to the fixtures on interruption of normal AC power. 
     It is another object of the invention to provide a test switch capable of providing a visual test of the operational worthiness of an inverter unit or the like, which switch structures are formed of a minimum of inexpensive parts which can be assembled with relative ease in order to reduce manufacturing expense. 
     It is a further object of the invention to provide a test switch which causes lamping to be illuminated at reduced levels to indicate the condition of an inverter unit, the test switch structures employing an electrically conductive element displaceable into contact with leads extending from the lamping and which are electrically connected to cables electrically joined to circuitry elements to be tested, a spring-loaded electrical contact being displaced into contact with leads joined to the lamping on manual manipulation of the plunger element against spring loading. 
     Other objects and advantages of the invention will become more readily apparent in light of the following detailed description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the preferred embodiment of the test switch; 
     FIG. 2 is an exploded view of the preferred test switch and further showing a toothed wedge which provides a mounting function; 
     FIG. 3 is a side elevational view in section of the test switch of FIG. 2 illustrating the switch in a non-testing condition; 
     FIG. 4 is a side elevational view in section of the test switch of FIG. 2 illustrating the switch in a non-testing condition; 
     FIG. 5 is a perspective view of the test switch taken from an opposite end thereof; and, 
     FIG. 6 is an exploded view of a second embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and particularly to FIGS. 1 and 2, a test switch configured according to a preferred embodiment of the invention is seen generally at  10  to be fitted with insulated, electrically conductive wires  12  and  14  which are preferably formed of 18 or 20 gauge material and which are UL 1015 or 1007 rated. The wires  12 ,  14  perform conventional functions and are of a length, such as approximately 36 inches, which allow remote location of the test switch  10  relative to an inverter unit (not shown) with which the test switch  10  is used. The inverter unit can take the form of one of the POWER SENTRY products of Lithonia Lighting, a division of National Service Industries, Inc., of Atlanta, Ga., and contains circuit elements (not shown) sealed within the interior of the inverter unit. Batteries (not shown) which are often used in such inverter units preferably take the form of sealed, maintenance-free, high-temperature nickelcadmium batteries which are permanently sealed within housings (not shown) formed either of high-impact polycarbonate material or a conventional steel material. The inverter unit also contains a circuit board (not shown) including a charger circuit (not shown) necessary for converting 120 VAC or 277 VAC from building power to a current and voltage the batteries or other emergency power source require when building power is present, and an inverter circuit (not shown) for transforming battery voltage and current into the type of power fluorescent lamps (not shown) want to see when building power is not present. The inverter unit is conventionally mounted to a portion of a lighting fixture (not shown), the function of the inverter unit, fixture and lamp being conventional in the art in that the lamp mounted by the fixture is driven under normal conditions by AC mains power. An interruption in the primary AC power supply causes a switching of power by circuitry components (not shown) within the inverter unit to cause the lamp (and other lamping associated with the fixture) to be driven by battery power from the inverter unit. The lamp typically takes the form of a linear fluorescent lamp such as a T12 or T8 lamp when the fixture is a linear fluorescent fixture. When the fixture is a downlighting fluorescent fixture, the lamp would normally take the form of a compact fluorescent lamp or lamps of varying description. 
     The free ends of the wires  12 ,  14  are received by a connector  22  of conventional design, the connector  22  typically being of a type such as is provided by Molex under product designation 39-43025-0400. Female terminals (not shown) connect the ends of the wires  12 ,  14  to the connector  22  internally thereof The connector  22  plugs into the inverter unit in a conventional manner although it is important to note that the connector  22  electrically communicates with battery power within the inverter unit such that a circuit can be formed through the wires  12 ,  14  to the test switch  10  when the test switch is activated as will be described hereinafter. A jumper wire  24  is mounted to the connector  22  in a conventional manner and functions in a known manner which does not need to be described herein. 
     The ends of the wires  12 ,  14  opposite connection to the connector  22  are electrically spliced to crimped connectors  26  with one of the connectors  26  being connected to each end of each of the wires  12 ,  14 . The connectors  26  connect also to respective leads  28  which form a part of a light emitting diode  30 , the light emitting diode  30  being a conventional LED such as is manufactured by SUNLED Co. with product designation LMDS3D/K-14V. Other diodes produced by other companies are also useful. 
     The light emitting diode  30  along with the leads  28 , connectors  26  and ends of the wires  12 ,  14  are received within a housing  32  which is molded from a clear polypropylene material or other suitable polymeric material having suitable and conventional requirements for an application of this type. The housing  32  is formed of an upper portion  34  and a lower portion  36  which are hinged together at  38  effectively by means of a “living hinge” formed along edges of the portions  34 ,  36 . The upper and lower portions  34 ,  36  of the housing  32  can be pivoted relative to each other in order to form an enclosure which is the housing  32 , the portions  34 ,  36  snapping together in a manner which will be described hereinafter. 
     The lower portion  36  of the housing  32  comprises a planar base  40  having a lateral planar side plate  42  which extends along an elongated edge of the planar base  40  through the full length thereof, the plane of the plate  42  being essentially perpendicular to the plane of the base  40 . Two spaced rectangular openings  44  are formed in the plate  42  near each end respectively of the plate  42 , the openings  44  extending through the juncture between the base  40  and the plate  42  and slightly into the base  40 . The openings  44  function in concert with snap elements  46  formed integrally on the upper portion  34  of the housing  32  to lock the portions  34  and  36  together. 
     The planar base  40  of the lower portion  36  is provided with a divider  48  located immediately inwardly of two spaced cradling tabs  50  mounted on one edge of the base  40 , the structure of the tabs  50  and of the divider  48  acting to separate the leads  28  of the test switch  10  from each other when the LED  30  and the leads  28  inter alia are placed into the interior of the housing  32 , the LED  30  being placed inside of the housing  32  when the portions  34 ,  36  are unassembled, that is, not snapped together. The LED  30  is received within a substantially cylindrical and hollow receptacle  52  which is open on the side thereof facing the divider  48  such that the portions of the leads  28  immediately adjacent the light emitting diode  30  can be accommodated. The leads  28  are respectively received within notches  54  formed in a cylindrical wall  56  disposed between the divider  48  and the receptacle  52 . Upper edges of the receptacle  52  can preferably be formed with an upward slope toward an outermost side of the receptacle  52  in order to provide increased protection to the LED  30 . 
     The upper portion  34  of the housing  32  is substantially formed as a rectangular solid with a planar base  58  having elongated side walls  60  and  62  disposed along the longest side edges of the base  58  and side walls  64  and  66  disposed along the two shorter edges of the base  58 . The side walls  60 ,  62 ,  64  and  66  are substantially planar with the planes thereof being substantially perpendicular to the plane of the base  58 . A living hinge  68  is formed along the elongated side wall  60 , the hinge  68  hinging the upper portion  34  and the lower portion  36  of the housing  32  together at  38  as aforesaid. The elongated side wall  60  increases in thickness to form a shoulder  70  which effectively extends above the plane of the base  58  and terminates in a slanted, toothed wedge  72  which is essentially formed integrally with a cylindrical housing  74  which extends from the base  58  at right angles thereto, the housing  72  terminating in collar portions  76  which are interrupted at opposite ends by means of rectangular notches  78  which extend from the distal end of the cylindrical housing  74  to locations just above upper surfaces of the toothed wedge  72  and a toothed wedge  80  formed on the opposite side of the housing  74  from the wedge  72 , the toothed wedge  80  extending essentially directly from the base  58  and being thickened to form a shoulder  82  at the juncture of the wedge  80  and the base  58 . The toothed wedges  72  and  80  provide a mounting function in concert with additional structure which will be described hereinafter. 
     The elongated side wall  62  is provided with the snap elements  46  as alluded to above, the elements  46  being substantially triangular in cross-section by virtue of being thicker at terminations of the elements  46  inwardly of the side wall  62  as opposed to loci of minimum thickness at the juncture of the elements  46  and the free edge  84  of the side wall  62 . The snap elements  46  snap into the openings  44  in a conventional manner to hold the upper portion  34  and lower portion  36  together to form the housing  32 . 
     A mounting yoke  86  formed of a planar base  88  having triangular legs  90 , is integrally molded with the housing  32  and attached together by means of a tie  92  which is also integrally molded with the yoke  86  and the housing  32 . Sloped side walls  94  are provided with teeth  96  which cooperate with the toothed wedges  72  and  80  to mount the test switch  10  to structure which can fit between side walls of the cylindrical housing  74  and a preferably arcuate wall  98  formed between the legs  90  at the juncture thereof with the base  88  of the yoke  86 . The end of the housing  32  having the cylindrical housing  74  extending therefrom is preferably placed against structure to which the test switch  10  is to be mounted and the yoke  86  is brought into engagement with the housing  32  such that the teeth  96  of the legs  90  of the yoke  86  engage respectively the toothed wedges  72 ,  80  to wedge the test switch  10  in place relative to structure of the fixture in a conventional manner. The mounting structure thus described is adjustable by virtue of movement of the toothed sloped side walls  96  of the legs  90  of the yoke  86  relative to the toothed wedges  72 ,  80  so that mounting to structure of differing physical dimension can be accommodated. 
     A planar wall  100  is formed interiorly of the upper portion  34  of the housing  32 , the wall  100  extending downwardly toward the planar base  40  of the lower portion  36  at the inward side of the divider  48  to facilitate maintenance of the leads  28  in a desired location within the interior of the housing  32 . An arcuate wall  102  is formed inwardly of the wall  100  and, like the wall  100 , extends from interior surfaces of the planar base  58  to a location immediately opposing outermost peripheral surfaces of the wall  56 , thereby to facilitate maintenance of the leads  28  within the notches  54  formed in the wall  56 . Immediately inwardly of aperture  104  which is the juncture of the housing  74  with the base  58 , an arcuate tab  106  extends from inner surfaces of the base  58  and is received between the wall  56  and the receptacle  52  which extend from the base  40  of the lower portion  36  of the housing  32 . The arc of the tab  106  opposes the arc of the arcuate wall  102  to incompletely defme an arcuate receptacle  108  which receives an elastomeric grommet  110  which has a substantially conical portion  112  surrounded by an apron  114  on exterior surfaces of the grommet  110 . Interiorly of the grommet  110 , the grommet  110  is essentially hollow except for a central, substantially cylindrical wall  116  which mounts an electrically conductive disc  118 . The conical portion  112  of the grommet  110  is placed into the arcuate receptacle  108  whereby the apron  114  contacts along major portions thereof the outer peripheral edges of the arcuate wall  102  and the arcuate tab  106 . A plunger  120  formed of an elongated, arcuate body portion  122  terminates in a cylinder  124  at one end of the body portion  122 , the cylinder  124  being rounded to form a push button  126  which extends slightly out of the cylindrical housing  74  at the free end of said housing  74  such that the push butt  12  can be manipulated by finger pressure. The opposite end of the arcuate body portion  122  terminates in a shaped base plate  128  having a rectangular portion  130  immediately adjacent the body portion  122  and a triangular portion  132  extending from an outer lateral edge of the rectangular portion  130 . An opening  134  of substantially rectangular shape is formed in the rectangular portion  130 , the opening  134  being rectangular except for the side of the opening nearmost the arcuate body portion  122 , this side of the opening  134  being arcuate to accommodate the shape of the body portion  122 . 
     Assembly of the plunger  120  into the cylindrical housing  174  causes the arcuate tab  106  to be received within the opening  134  of the base plate  128  of the plunger  120 , the base plate  128  then lying between interior surfaces of the planar base  58  of the upper portion  34  and the elastomeric grommet  110  although the grommet  110  is positioned to rest on the arcuate wall  102  and the arcuate tab  106  as aforesaid. Finger pressure on the push button  126  causes the plunger  120  to move inwardly of the cylindrical housing  74  and to cause the base plate  128  of the plunger  120  to displace the grommet  110  against resilient loading provided by the material from which the grommet  110  is formed. Displacement of the grommet  110  coupled with distortion of the apron  114  of the grommet  110  in particular causes the electrically conductive disc  118  to come into contact with the leads  28  of the LED  30  when the LED  30  has been mounted within the housing  32  as aforesaid. The LED  30 , which has essentially been illuminated since correct wire hook-up during installation, is thus shorted out and is no longer illuminated. Indication of the operational worthiness of the unit  16  is provided by illumination of the lamping, such as the lamp  20  at reduced levels. 
     FIGS. 3 and 4 respectively illustrate the configuration of a non-testing and testing condition respectively of the test switch  10 . FIG. 4 particularly illustrates the configuration of the structural elements of the switch  10  when the push button  126  is depressed. FIG. 5 more clearly illustrates the structure of the test switch  10  by providing a perspective view which shows the test switch from the opposite side thereof relative to the orientation of the switch as seen in FIG.  11 . 
     Referring now to FIG. 6, a second embodiment of the invention is seen in an exploded view to include structure similar to that described hereinabove relative to the first embodiment of the invention. Essentially, only housing  140  and an electrical contact spring  142  differs substantially from corresponding structure described relative to the first embodiment of the invention. The housing  140  is seen to be similar in external features to the housing  32  described above particularly in that the housing  140  is formed of upper and lower portions  144  and  146 . The upper and lower portions  144  and  146  snap together to form the housing  140  in a manner which is substantially identical to that described hereinabove relative to the housing  32 . The lower portion  146  of the housing  140  is provided interiorly thereof with a divider  148  which finctions substantially as does the divider  48  of FIGS. 1 through 4. Further, the lower portion  146  is provided with a cradle  150  having notches  152 , the cradle allowing LED  154  to lie thereon while leads  156  fit into the notches  152  formed in the cradle  150 . A wall  158  at the end of the lower portion  146  opposite the divider  148  extends upwardly from a base of the lower portion  146  to provide an edge against which an actuator portion  160  of plunger  162  can bias in order to limit travel of the portion  160 . The plunger is provided with a push button  164  which is essentially identical to that described hereinabove relative to the embodiment of FIGS. 1 through 4, the plunger  162  fitting within a cylindrical housing  166  which is hollow and which extends from one end of the upper portion  144  of the housing  140 . The cylindrical housing  166  is formed in a manner essentially identical to that described hereinabove relative to the embodiment of FIGS. 1 through 4. However, the housing  166  is provided with toothed wedges (not shown) on either side of the housing  166  along the longitudinal axis of the housing  140 . A yoke  172  held to the housing  140  by means of an integral tie  174  is essentially identical in structure to the yoke  86  shown and described hereinabove, teeth  176  formed on sloped side walls  178  of legs  180  of the yoke  86  cooperating with the toothed wedges mentioned above to provide an identical function to that described hereinabove relative to essentially identical structure of the test switch  10 . 
     The plunger  162  is provided at its free end with an elongated pressure plate  182  which has an elongated opening  184  formed therein, the opening  184  receiving therethrough positioning stem walls  186  which extend downwardly into the interior of the housing  140  from inner surfaces of the upper portion  144 . The electrical contact spring  142  is formed of an electrically conductive material and is placed within the interior of the housing  140  between the pressure plate  182  and the lower portion  146  of the housing  140 . The spring  142  is formed of a base  188  having ani opening  190  formed therein, the base  188  being elongated and terminating in recurved distal tips  189 . The opposite end of the base  188  is formed of a substantially U-shaped downward protrusion  194  having a recurved end portion  196 . A tab element  198  extends from an innermost leg portion of the protrusion. Pressure on the push button  164  of the plunger  162  causes the pressure plate  182  to bias downwardly against spring loading provided by the geometry and material of the electrical contact spring  142  and causes a portion of the spring  142  to electrically contact the leads  156  to short the LED  154  and provide the visual indication from lamping as noted above. Accordingly, testing is readily and easily accomplished. 
     It is to be understood that the invention can be practiced other than as expressly shown and described herein, the scope of the invention being defined by the recitations of the appended claims.