Abstract:
A bulb grasping unit for an elongated cylindrical fluorescent bulb is rigidly mounted on an elongated handle to facilitate replacement of fluorescent bulbs supported by two prongs on the bulb ends en resiliently mounted tubular contacts in out of reach fixtures. The bulb grasping unit is integrally formed from plastic and defines a generally semi-cylindrical recess which is resiliently radially expandable to snap into engagement with the fluorescent bulb. When one bulb prong is inserted in one tubular contact, upward movement of the other end of the bulb by the bulb grasping unit engages a cam on the end of the bulb grasping unit with a cam surface on the fixture to axially shift the other prong into alignment with the other tubular contact.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to apparatus for installing and removing elongated, cylindrical fluorescent bulbs into or out of their customary supporting fixtures. The invention has particular application in fluorescent lighting systems involving axially directed, spring type retaining sockets for mounting tubular fluorescent bulbs. 
     2. Summary of the Prior Art 
     As is well known, the installation and removal of fluorescent bulbs is usually accomplished with much inconvenience. In the normal situation, fluorescent bulbs are supported in fixtures at an overhead location out of reach of the normal size person. Hence, an elevated platform or ladder is needed to place the maintenance person within reach of the particular fixture needing a bulb change. Since many fluorescent bulbs range in length from six to eight feet, it is difficult for the maintenance person to climb up a ladder holding the bulb, then align one end of the bulb with the spring type retaining socket, apply an axial force to the bulb to compress the socket, and then swing the other end of the bulb into engagement with the other socket. 
     It has been previously proposed that grasping units for holding a fluorescent bulb be secured to the end of an elongated handle to permit the replacement of the bulb without resort to a ladder. Bulb grasping units of this type are shown in the following U.S. Pat. Nos.: 
     
         ______________________________________#2,393,880           Beard#2,589,642           Stueland#2,855,238           Ford#3,101,212           Cater#3,929,365           Hunt et al______________________________________ 
    
     In all of the aforementioned prior art patents, except the Hunt et al patent, elaborate mechanisms are provided generally incorporating two semi-cylindrical grasping elements which are moved relative to each other in surrounding, clamping relationship relative to a fluorescent bulb by the operation of a complex linkage. Obviously, these constructions are expensive to manufacture and require frequent repair due to the number of moving parts involved in such prior art apparatuses. 
     The Hunt et al U.S. Pat. No. 3,929,365 discloses a simpler arrangement for grasping a fluorescent bulb, having either one or two connector prongs, comprising a semi-cylindrical gripper. A complex coupling is provided between the gripper and the operating handle to permit rotation of the bulb for insertion of a two prong type. The Hunt et al construction is obviously expensive to manufacture. 
     It is readily apparent, therefore, that a fluorescent bulb handling mechanism involving a minimum of movable parts, yet assuring the firm securement of the bulb during an installation or removal operation, would be a highly welcomed mechanism for installing or removing elongated fluorescent bulbs. 
     SUMMARY OF THE INVENTION 
     This invention provides a fluorescent bulb grasping element having a generally semi-cylindrical configuration. The grasping element is mounted on the end of an elongated handle, which may incorporate a conventional mechanism for adjusting the effective length of such handle. When so mounted, the axis of the semi-cylindrical grasping member is perpendicular to the axis of the elongated handle. 
     The grasping element is formed from a semi-rigid, yet resiliently flexible material which could be either metal or a suitable plastic such as polypropylene. While the bulb grasping unit is of generally semi-cylindrical configuration, along its axial length, portions of the longitudinal edges of the bulb grasping unit are arcuately extended to encompass slightly more than half of the diameter of the fluorescent bulb to be grasped. Thus, to apply the grasping unit to the bulb, it is only necessary to radially push the grasping unit against the bulb whereby the arcuate extensions on the grasping unit will be resiliently flexed outwardly to permit entry of the bulb into the recess defined by the grasping unit and to be secured therein. 
     In a preferred embodiment of the invention, the grasping unit comprises an outer body element formed of a solid, yet flexible material which defines a semi-cylindrical recess having a radius greater than that of the bulb to be grasped. A layer of foam is then inserted in the recess of the bulb grasping unit to provide a cushioned support for such bulb and increased frictional engagement. Again, however, arcuate extensions are provided along the axial edges of the bulb grasping unit, which encompass the bulb by more than 180° and hence effect a securement of the bulb within the foam covered recess. 
     With either of the two aforedescribed embodiments of the invention, the grasped bulb may be readily raised so that the single contact prong on one end of the bulb is engagable with a spring pressed female contact in the brackets that support the fluorescent bulb. The grasped bulb is pivoted upwardly while maintaining an axial force thereon to compress the spring biased female contact and bring the second prong on the bulb in alignment with the second female contact. The axial force on the bulb is then released, permitting the bulb to be moved axially to engage the other female contact and to be inserted therein. 
     A further embodiment of this invention is particularly useful in inserting or removing fluorescent bulbs from fixtures having brackets which define a vertically inclined camming surface leading upwardly from the bottom of the bracket to the vicinity of the female contact. For this type of fluorescent mounting apparatus, the bulb grasping element embodying this invention additionally incorporates a rotatable cam mounted on the end of a plunger which projects axially out of a lower portion of the tube grasping element in generally parallel relationship to the bulb. Such plunger is normally held in a projecting position compressing a spring within a spring mounting recess, by the operation of a latch which is vertically shiftable. In such position, the cam rolls up the vertically inclined camming surface after insertion of the first contact prong in the spring pressed female contact. As the bulb is pivoted upwardly the spring pressed female contact is compressed by the cam and plunger acting on the bulb grasping unit. 
     In the locking position of the latch, the top of the latch is adjacent the bottom surface of the fluorescent bulb held in the tube grasping unit. When the bulb is pivoted upwardly, the bottom wall of the supporting fixture is contacted by the bulb, thus preventing further upward movement and shifting the latch downwardly. Preferably, a patch of material having an adhesive backing is applied to the bulb and engages the aforesaid bottom fixture wall to position the bulb so that the second contact prong of the bulb is in vertical alignment with the female prong provided in the second bracket of the mounting fixture. Thus, when further upward movement of the bulb is prevented by engagement of the patch of material with the bottom wall of the fixture, the upward force exerted by the bulb grasping unit will cause the latch to be moved downwardly, thereby contracting the plunger by the force of the compressed plunger spring to permit axial movement of the bulb grasping unit to engage the second contact prong of the bulb in the second female contact, thus securing the bulb in the female contacts. 
     A burnt out fluorescent bulb may be readily removed from the fixture by any of the embodiments of this invention. With any embodiment, the bulb is grasped in its medial portion by applying the grasping unit to the bulb and exerting sufficient upward force on the grasping unit, through the elongated handle, to spread the retention prongs of the grasping unit and permit it to snap into snug engagement with the bulb. An axial force in the direction of the spring pressed female contact element is then applied to the bulb, which effects the release of the contact prong on the opposite end of the bulb. The bulb is then pivoted downwardly and removed from the spring pressed female contact. 
     The invention, in all of its embodiments, is much simpler than any of the prior art structures, hence more economical to manufacture and to maintain. 
     Further advantages of the invention will be readily apparent to those skilled in the art from the following detailed description, taken in conjunction with the annexed sheets of drawings, on which is shown several preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view illustrating the insertion of an elongated fluorescent bulb into a supporting fixture by a bulb grasping unit embodying this invention. 
     FIG. 2 is a perspective view of one embodiment of bulb grasping unit embodying this invention. 
     FIG. 3 is an enlarged scale vertical sectional view of a modification of the bulb grasping unit of FIG. 2. 
     FIG. 4 is an enlarged scale exploded perspective view of another modified grasping unit embodying this invention. 
     FIG. 5 is an enlarged scale vertical sectional view of the modified form of bulb grasping unit shown in FIG. 4, shown in assembled relationship to a fluorescent bulb and illustrating the position of the elements of the grasping unit as the bulb is moved to an inserting position in its supporting fixture. 
     FIG. 6 is a view similar to FIG. 5 but illustrating the position of the elements of the bulb grasping unit when the bulb is completely inserted in its supporting fixture. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, there is disclosed the simplest form of a replacement apparatus for elongated cylindrical fluorescent bulbs embodying this invention. The apparatus comprises a generally semi-cylindrical bulb grasping unit 1 having opposed longitudinal edge walls 1a. The unit 1 is suitably rigidly mounted in transverse relation onthe end of a elongated pole 2. Pole 2 may be of the type utilizing a plurality of telescopic members to permit selective elongation of the poleto a desired length. Such adjustable elongated poles are well known in the art and hence, will not described in detail. 
     The bulb grasping unit 1 is provided with an integral hub 1c which may be internally threaded for receiving a cooperating threaded end of the elongated handle 2. Alternatively, spring pressed balls or a bayonet type attachment may be employed. 
     The bulb grasping unit 1 is formed from a semi-rigid, yet resiliently flexible material such as aluminum, steel or an injection moldable plastic, such as polypropylene. The shell 1d of grasping unit 1 defines a semi-cylindrical recess lb having a radius substantially equal to, but notless than the radius of the fluorescent bulb 10 to be grasped. Along the longitudinal edges 1b, a plurality of opposed arcuate projections le are formed which extend the semi-cylindrical recess 1b to slightly more than 180°. Thus, when the shell 1d of the bulb grasping unit 1 is forcedradially against a wall of a fluorescent bulb 10, the shell 1d is expanded by resilient deflection of the arcuate extending portions 1e to snap into surrounding engagement with the fluorescent bulb 10 as shown in FIG. 1. Preferably, the arcuate projections 1e comprise a plurality of scallops disposed along each edge 1a to prevent tilting when initially engaged withthe bulb. 
     The utilization of the bulb grasping unit 1 is illustrated in FIG. 1. The grasping unit 1 is snapped into engagement with a medial portion of the bulb 10, preferably adjacent one end, and the other end of the bulb 10 having a single projecting contact prong 10a is moved into engagement withan axially shiftable spring pressed female contact 12a formed in a supporting bracket 12b of a fluorescent light fixture 12. See enlarged views of FIGS. 4 and 5 for clarity. A second bracket 12c is axially spacedfrom the first mentioned bracket 12b a distance corresponding to the lengthof the fluorescent bulb 10 and this bracket incorporates a female contact element 12d which may or may not be axially spring pressed. Brackets 12b and 12c are supported by a receptacle housing 12d having a bottom wall 12e. 
     With one prong 10a of the fluorescent bulb 10 inserted in the axially shiftable spring pressed female contact 12a, an axial force is applied to the fluorescent bulb 10 by manipulation of the handle 2, thus depressing the spring pressed female contact element 12a. The bulb is then pivoted upwardly to bring the second single prong contact 10b of the bulb 10 into alignment with the second female contact element 12c. The axial force exerted on the bulb is then released and the bulb 10 shifts in an axial direction to engage the second prong 10b in the female contact 12d of the second supporting bracket 12d. Thus, the bulb 10 is securely anchored in the fixture 12. 
     To remove the bulb 10, the sequence of steps is merely reversed. The grasping unit 1 is raised by the handle 2 to radially engage a medial portion of the fluorescent bulb 10. An axial force is then applied to the bulb 10 to effect the axial shifting of the spring pressed female contact 12a, thus permitting the second contact prong 10b of the bulb 10 to be removed from its cooperating female contact element 12d. The bulb then canbe pivoted downwardly to remove the first prong 10a from the spring pressedfemale contact 12a and the bulb 10 then can be lowered to a point where it can be manually grasped by the maintenance person. 
     To protect the fluorescent bulb 10 from damage from the application of the grasping unit 1 thereto, the embodiment of this invention illustrated in FIG. 3 may be employed. In this embodiment, the grasping unit 1&#39; defines asemi-spherical recess 1&#39;a which is larger than the radius of the fluorescent bulb 10. This increase in clearance is provided to accomodate a layer 11 of a cushioning material, such as a polyurethane foam plastic. Again, the internal radius of the resulting semi-cylindrical recess defined by the inserted foam plastic is substantially less than the external radius of the fluorescent bulb 10, thereby permitting the arcuateprongs or projections 1&#39;e, to secure the bulb grasping unit 1&#39; in firm engagement with the external surface of the fluorescent bulb 10. The cushioning material 11 employed also increases the frictional engagement between a fluorescent bulb 10 and the internal surface of the grasping unit 1&#39;, thereby preventing the grasping unit 1&#39; from sliding relative to the bulb 10 when the required axial force is applied to the bulb 10 to compress the female contact element 12a. 
     A third embodiment of the invention is illustrated in FIGS. 4-6. In this embodiment, the fluorescent tube grasping unit 20 defines an internal semi-cylindrical recess 20a having a radius substantially greater than theexternal radius of the fluorescent bulb 10 to be engaged. As in the modification of FIG. 3, a layer of cushioning and friction increasing material, such as a polyurethane foam 21, is inserted in the semi-cylindrical recess 20a. Arcuate prongs 20c are provided along each edge 20b of the semi-cylindrical recess 20a to extend the recess to slightly more than 180°, thereby insuring the securement of the fluorescent bulb 10 within the foam plastic lined recess 20a. 
     Additionally, the hub portion 20c of the tube grasping unit 20 is axially elongated as indicated at 22. An axially extending square bore 22a is provided in such hub portion 22 and opens in one end of the hub 22. 
     A plunger 24 is slidably mounted in the bore 22 and the outer end of the plunger 24 mounts a U-shaped bracket 26 having spaced arms 26a and 26b between which a cam roller 28 is rotatably journalled. Cam roller 28 is normally engaged with an upwardly inclined camming surface 12f (FIG. 5) conventionally provided on the bulb mounting brackets 12 which terminates in a planar surface 12g which is disposed in juxtaposition to an end face of the bulb 10 when the bulb 10 is installed in the female contact units 12a and 12b. 
     The cam mounting plunger 24 is normally secured in its outwardly projectingposition shown in FIG. 5 by a vertically shiftable latch element 30 which is best shown in the exploded view of FIG. 4. Latch element 30 is of rectangular configuration and has a rectangular recess 30a surrounding plunger 24. Latch 30 is vertically shiftable in a correspondingly shaped slot 22d formed in the axially extended hub portion 22 and traversing the bore 22a within which the cam plunger 24 is mounted. 
     Cam plunger 24 is provided with a notch 24d which engages one edge of the rectangular slot 30a formed in the latch element 30. A recess 22e is formed in the hub portion 22 traversing the plunger mounting bore 22a. A spring 32 is mounted in surrounding relationship to the cam plunger 22 andis compressed between a vertical wall 22g (FIG. 5) of the recess 22c and a pin 24f transversely secured to the cam mounting plunger 24. Thus, in the position of latch element 30 shown in FIG. 5, the cam mounting plunger 24 is essentially rigidly mounted to the tube grasping unit 20 which, in thisembodiment of the invention, is engaged with the fluorescent bulb 10 at a location adjacent one end of such fluorescent bulb. At least one spring pressed female contact 12a is provided in the mounting fixture 12 and whenthe prong 10a of the other end of bulb 10 is inserted in female contact 12aand the first bulb end pivoted upwardly, the cam 28 engages the vertically inclined camming surface 12f formed on the bracket opposed to the spring pressed female contact. 
     Thus, to insert a bulb between the opposed brackets 12b and 12c, the end ofthe bulb 10 opposite to the end grasped by the grasping unit 20 is first manipulated to insert the prong 10a into the spring pressed contact element 12a. The fluorescent tube 10 is then pivoted upwardly by manipulation of the handle 2 and the cam roller 28 rolls upwardly against the vertically inclined camming surface 22f provided on the opposed bracket 22c to axially shift the spring pressed contact element 12a and permit the second prong 10b of the fluorescent bulb to clear the inner face 12g of the bracket 12c. 
     To assist in alignment of the second prong 10b with the second female contact element 12e, this invention contemplates the utilization of a small pad 40 of foam or cloth having a thickness sufficient to position the prong 10b in substantially exact vertical alignment with the female contact 12e in the second bracket 12c by engagement of such pad with the bottom wall surface 12e of the supporting housing 12d. 
     When the bulb 10 is thus positioned, the latch 30 is pushed downwardly through the application of the upward force to the bulb grasping unit 20, thereby depressing the latch 30 to free the latch 30 from the notch 24d formed in the cam mounting plunger 24, as shown in FIG. 6. The cam mounting plunger 24 is then pushed inwardly by spring 32 to disengage fromthe camming surface 12f of the adjacent bracket 12c. The grasping unit 20 is then free to be moved axially toward the second bracket 12c to engage the second prong 10b in the second female socket 12e, thus securing the bulb in the female sockets. 
     To replace a burned out bulb, the plunger 24 is placed in its spring retracted position, and the same removal procedure is employed as previously described in connection with the modifications of FIGS. 1-3.