Abstract:
An adjustable track lighting fixture of a type having rotary locking lever for securing the fixture to a bus bar, where the locking lever is economically formed with an internal confinement facility of removably housing an Allen key to be retained with the fixture and used for locking the adjustments of the fixture when desired. A spring, also housed internally of the locking lever, resiliently but releasably retains the Allen key until purposefully withdrawn by a workman. The key is returned to its confinement after the workman has finished using it for the purposes intended. The key is retained in an inconspicuous manner but nevertheless visible to the workman and readily extracted for use when desired.

Description:
FIELD OF THE INVENTION 
     The invention relates to specialized forms of adjustably positioned lighting fixtures, as frequently used in commercial and theatrical lighting, and particularly to features thereof to accommodate and facilitate periodic adjustment. 
     BACKGROUND OF THE INVENTION 
     Specialized lighting fixtures, such as theatrical lighting, and various forms of commercial lighting fixtures are constructed to provide for accurate aiming of a light beam. In many cases, after a lighting fixture is initially installed, it may be adjusted one or more times until a desired effect is achieved. At that juncture, it may be desired to tightly lock the adjustments, so that vibrations and other external influences will not, over time, result in undesired movements in the adjusted position of the fixture. For effectively tight locking of the adjustments, a tool frequently is required. However, if the workman does not have the correct tool at the proper time, the final locking of the adjustments may not be carried out. 
     SUMMARY OF THE INVENTION 
     The invention is directed to an improvement in adjustable lighting fixtures of the type described, particularly for track lighting systems, which include novel and effective facilities for housing a locking tool in the fixture itself in a reliable and secure manner, easily accessible to a workman. Typically a suitable locking tool is an Allen key, of a size to be engageable with one or more Allen screws provided on the fixture, for securely tightening the fixture in an adjusted position when appropriate and desired. The Allen key is mounted in a convenient manner and location, easily accessible to the workman, yet is securely retained against accidental dislodgment and loss, and is easily replaced by the workman when finished with the locking operations. 
     An advantageous form of track lighting fixture of existing design includes a mounting body arranged to be received within a downwardly opening recess of a bus bar containing conductive elements for operating lighting fixtures positioned anywhere along the bar. The mounting body includes a rotatable element carrying electrical contacts and a clamping element, all operated by a rotatable locking lever accessible at the bottom of the mounting body. After the mounting body is positioned in the bus bar, the locking lever is rotated such that the electrical and the clamping elements are rotated into engagement with the bus bar, securing the fixture in position and engaging its electrical contacts with the conductors of the bus bar. The new fixture incorporates a novel and specialized design of locking lever, which enables it to conveniently house an Allen key in a secure manner which is at the same time easily accessible to a workman for locking an adjusted lighting fixture in a desired orientation and also conveniently restored to its position within the locking lever so as to be available for a future occasion. The proper tool thus always accompanies the fixture and is always available to a workman installing, re-installing and/or adjusting the fixture. 
     For a more complete understanding of the invention reference should be made to the following detailed description of a preferred embodiment thereof and to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an advantageous form of track lighting fixture incorporating the features of the invention. 
         FIG. 2  is an exploded view of a rotatable locking lever, utilized in the fixture of  FIG. 1 , incorporating features of the invention. 
         FIGS. 3 and 4  are top plan views of the locking lever of  FIG. 2 , showing features according to the invention for receiving and securely retaining an Allen key for use in setting the lighting fixture in a semi-permanent manner after its initial adjustments have been completed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, the reference numeral  10  designates generally a track lighting fixture which, except for features to be described hereinafter, is of a known type with known features which do not form part of this invention. The illustrated fixture includes a lamp body  11  which is mounted on a transformer housing  12  for rotation with respect to the housing  12  about a horizontal axis. Suitable calibration indices  13  may be provided to assist in properly orienting the housing  11  with respect to its rotational axis. The transformer housing  12  is attached to a mounting body  14  and is arranged for rotation with respect to the mounting body  14 , about a vertical axis. Calibration indices  15  also can be provided to facilitate proper rotational adjustment about the vertical axis. 
     The mounting body  14  is of an inverted T-shaped cross sectional configuration, suitable to be received within the downwardly opening recess of a typical bus bar (not shown). A flange  16  at the bottom of the mounting body seats against bottom surfaces of the bus bar. 
     For mounting the fixture  10  in the bus bar, the mounting body  14  houses an internal rotary element (not shown) carrying electrical contacts  17 ,  18  and a clamping element  19 . The rotary element is fixed to a rotary locking lever  20  located underneath the flange  16 . For the initial mounting of the fixture, the lever  20  is rotated at right angles to the mounting body  14 , to retract the contacts  17 ,  18  and the clamping element  19  into the mounting body. After the mounting body is positioned in the bus bar, the lever  20  is rotated to a position parallel with the mounting body, as shown in  FIG. 1 , simultaneously to cause the clamping element  19  to lockingly engage the bus bar and to cause the contacts  17 ,  18  to engage linear conductors within the bus bar. 
     After mounting the fixture on the bus bar, the lamp housing  11  is normally adjusted about its respective horizontal and vertical axes to cause light from the fixture to be properly focused on a desired subject area. Typically, there is sufficient friction in the horizontal and vertical rotational connections to enable the housing  11  to remain in an adjusted position. However, over time, various influences such as vibrations, temperature variations, accidental bumping etc., can cause an initial adjusted position to change. Accordingly, manufacturers frequently provide locking devices, such as Allen screws, for tightly locking the elements in their adjusted positions to largely prevent such undesired movements. One such Allen screw is indicated at  21  in  FIG. 1  for the vertical axis adjustment, and a similar such screw (not visible) is provided on the housing  11  for locking the horizontal axis adjustment. 
     Pursuant to the invention, a locking lever  20  of novel design is provided to enable each lighting fixture to be provided with an Allen key suitable for its components, with the Allen key being inserted and retained in the locking lever so as to be available at all times for securing of the fixture in its adjusted position. With reference to  FIGS. 2-4 , the locking lever  20  comprises a molded plastic body  22  formed with a generally flat bottom wall  23 , a surrounding wall  24  and a rounded end  25  to accommodate rotation. At the center of the rounded end, the lever is formed with socket walls  26  forming a hexagonal socket engageable with a correspondingly shaped element (not shown) forming the bottom of the previously mentioned rotary element in the mounting body  14 . A screw fastener  28  is engageable through opening  27  at the center of the socket defined by walls  26 , for fixing the lever  20  to the rotary element. 
     Locking levers  20  generally are well known devices for use in the mounting of track lighting fixtures and frequently are formed with a bottom opening  29  providing access to an on-off switch (not shown). An associated side recess  30  allows the lever to be rotated to engage or disengage the fixture when the switch is in its “off” position. The locking lever of the invention, however, includes an additional and unique feature for receiving and reliably retaining an Allen key  31 . As shown in  FIGS. 2 and 4 , a standard Allen key  31  is of L-shaped configuration comprised of a long leg  32  and a short leg  33 . The locking lever of the invention is formed with an opening  34  in an end portion  35  of the surrounding wall, with one side of the opening being defined by a side wall portion  36 . The side wall portion  36  forms a guide for receiving the long leg of the Allen key  31  and forms one side of a cavity for retaining the key. In this respect, the length of the locking lever  22  is such that the entire long leg of the Allen key can be received within the lever  22 , with the short leg positioned tightly against the end wall portion  35  (see  FIG. 4 ). 
     Spaced inward from the guide wall  36  is an inner confinement wall  37 , which is spaced from the guide wall and defines therewith a confinement space considerably greater than the thickness of the Allen key. In the illustrated and preferred embodiment of the invention, the confinement wall  37  is formed, adjacent to the end wall opening  34  with a short re-entrant wall  38  defining an inwardly facing, open ended recess  39 . The recess  39  is arranged to receive one end  40  of a generally J-shaped strip spring  41 . The spring  41  includes an elongated stem portion  42 , which is received in the confinement space between walls  36 ,  37 , and an arcuate portion  43  configured to pass part way around the socket wall  36 . The arcuate portion  43  joins at an apex  44  with a straight portion  45  passing in contact with a facet  46  of the socket wall  26  that lies parallel with the opposite side portions  36 ,  47  of the wall  24 . The straight portion  45  of the spring terminates in an outwardly and rearwardly directed end element  48 , which is received in a recess slot  49  on the inside of the wall portion  47 . 
     The spring  41  is assembled with the molded lever body by inserting the spring downwardly into the open top of the lever body, inserting the opposite ends of the spring into their respective confining slots  39 ,  49 . The geometry of the spring  41  is such that, when initially assembled, a portion  50  of the spring, between the straight and arcuate portions  42 ,  43  lies close to, and preferably bears resiliently against the inner surface of the side wall  36 , as shown in  FIG. 3 . To advantage the arcuate portion  43  of the spring may be pressed outward by corner  51  of the socket wall  46  to help press the spring portion  50  against the wall  36 . 
     As shown in  FIGS. 3 and 4 , the straight portion  42  of the strip spring  41  extends diagonally across the confinement space between the walls  36 ,  37  at a small angle thereto. Accordingly, when the long leg  32  of the Allen key is inserted into the end opening  34 , the end of the key is confined between the spring and the wall  36 . As the key is forced inward, it displaces the spring inwardly in the region of the portion  50 . When the Allen key is fully inserted, as shown in  FIG. 4 , the long leg  32  of the key is tightly gripped between the spring portion  50  and the wall  36  and is removable only by an intentional withdrawal by a service man or other person. 
     As shown in  FIG. 4 , the Allen key  31  is formed with a generous rounding in the area  53  between the short and long legs  33 ,  32 . To accommodate this rounding, the end wall opening  34  is substantially wider than the maximum thickness of the key stock. This allows the key to be inserted into the lever  22  sufficiently that the short leg  33  of the key comes into contact with the end wall  35 . It also stabilizes the key by providing a support surface  54  to position and hold the short leg  33  parallel with the bottom surface  23  of the locking lever. Only the short leg of the key is visible externally, and that is positioned tightly against the end wall of the lever  22  so as to be inconspicuous while being readily available for use. 
     The key-holding feature of the invention can be incorporated with track lighting fixtures of existing design with minimal cost, consisting of the cost of the spring  41  and its assembly, and minor, one-time mold revisions to accommodate the presence of the spring and to define a recess and an opening for the Allen key. 
     The new feature has substantial commercial significance in that it makes the overall product substantially more attractive to potential customers. Maintaining the adjustable lighting fixtures in accurate adjustment is a concern of all users thereof, and the improvement of the present invention greatly simplifies such maintenance and, more importantly, makes it more likely that the necessary or desired locking of the fixture adjustment will in fact take place. When “final” adjustments of a fixture have been completed, it is largely assured that the fixture adjustment can and will be properly locked because the required tool is always available to the service person. 
     It should be understood, of course, that the specific form of the invention herein illustrated and described is intended to be representative only as various changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following claims in determining the full scope of the invention.