Ceiling fixture having self-activating mounting means

A lighting fixture adapted to be mounted between parallel ceiling support grids includes a series of latches at the corners. The latches are retracted responsive to movement of the fixture to a position above the support grids and are released automatically after the fixture is disposed above the grids to define grid engaging supports for the fixture.

THE PRIOR ART 
It is known to utilized the gridwork employed for supporting ceiling tiles 
as the means or mechanism for supporting rectangular lighting fixtures 
disposed between the tiles. 
In the typical fixture of the type described the fixture is supported by a 
series of laterally extending mounting lugs fixed to the corners of the 
reflector housing. Mounting of the fixture is effected by adjusting the 
fixture to a height above the height of the grid structure, shifting the 
lugs laterally and thereafter tightening the lugs. The difficulties 
inhering in mounting a fixture of the type described are detailed in the 
above referenced copending application. 
Briefly, the device of the above referenced copending application 
simplifies installation and reduces the waste space encountered in the use 
of conventionally mounted rectangular fixtures by providing a lighting 
assembly having a series of spring projected latches at the corners. The 
installer has merely to elevate the fixture to a height above the ceiling 
support grids and normally activate detents at the corners, whereupon 
latches spring outwardly to a position whereat the undersurface of the 
latches rests against the upper surface of the support grids. 
While the device of the aforesaid application constitutes a substantial 
improvement in the art, installation of such lighting fixture still 
presented an awkward procedure. Moreover, the device did not provide means 
for heightwise adjustment of the fixture to accommodate minor 
irregularities in ceiling configuration or misadjustment in a heightwise 
direction of the ceiling supporting gridwork. 
SUMMARY OF THE INVENTION 
The present invention may be summarized as directed to a lighting fixture 
adapted to be installed in a recessed condition between the grids of a 
ceiling tile support structure. The device includes a housing having at 
the corners thereof spring projected latch members which are restrained 
from shifting outwardly by detent means interposed between the latch 
members and elements of the housing. 
A characterizing feature of the invention resides in the provision of a 
latching assembly whereby the latch members automatically are retracted 
responsive to movement of the fixture to a position above the grid 
structure, and automatically spring outwardly into fixture supporting 
position responsive to movement of the fixture to its mounted position. 
More particularly, the latch members are provided with cam means 
positioned to interact with the grid members upon upward movement of the 
fixture, which interaction functions to further retract the latch members 
and also to engage further cam mechanism which release the detent 
mechanisms retaining the latch members in a partially retracted position 
so that the latch members are free to spring outwardly after the fixture 
is lifted to a level above the ceiling grid structure. 
A further characterizing feature of the invention resides in the provision 
of fulcrum means which support the latch members for slideable as well as 
tilting movements. A degree of heightwise adjustment of the fixture is 
afforded by adjustably shifting the fulcrum members relative to the 
housing of the lighting fixture. 
It is accordingly an object of the invention to provide an improved 
recessed lighting fixture adapted to be mounted to the gridwork supporting 
a ceiling tile installation. 
A further object of the invention is the provision of a fixture of the type 
described wherein the fixture may be fixedly mounted between the grids 
defining a ceiling tile support assembly by the simple action of lifting 
the lighting fixture to a height above the support grids. 
Still a further object of the invention is the provision of a fixture of 
the type described wherein a degree of heightwise adjustability is 
afforded enabling the fixture to be accommodated to ceiling 
irregularities. 
A still further object of the invention is to provide a fixture of the type 
described in the above referenced copending application, but providing 
improvements in ease of mounting and in degree of adjustability as 
contrasted with the fixture of said application.

Turning now to the drawings, there is shown in FIG. 1 a cross sectional 
view through a conventional ceiling tile support assembly which includes a 
plurality of inverted T-bars 10 having depending web portions 11 at the 
bottom ends of which are disposed tile support branches 12 arrayed in a 
generally horizontal plane. 
As is conventional the ceiling tile members C include horizontally directed 
mounting slots 13 adjacent their side marginal edges, the tiles being 
mounted by the insertion of the slots 13 onto the opposite branches 12 of 
the supports 10. 
Support members 10 include hanger ledges 14 extending from the uppermost 
portion of the webs 11, the hanger portions being suspended from 
structural components of the building by depending support wires (not 
shown). 
The specific configuration of the support members 10 is not critical to the 
present invention, it being understood that the fixture of the present 
invention may be used with a wide variety of tile support assembly grid 
systems such as Z-bar systems and the like. 
As best seen in FIGS. 1, 2 and 3 the lighting fixture of the present 
invention includes a housing 15 within which is supported any conventional 
lighting means such as fluorescent lamps 16. The housing 15 is generally 
rectangular in horizontal section including end walls 16,17 and spaced 
parallel side walls 18,18 extending between the end walls 16,17. The end 
walls 16,17 and side walls 18,18 together define at their lower edges a 
downwardly open mouth portion 19 which optionally but preferably may be 
covered by a removeable laterally, outwardly extending frame or flange 20. 
The flange 20 may form an extension of a diffuser support assembly, as is 
conventional, wherein a translucent or prismatic light transmitting member 
is mounted to conceal direct visual access to the fluorescent bulbs or 
like lighting members. 
The housing 15 is mounted to the support members 10 by four latch 
assemblies 21 which are moveably mounted adjacent the inside of the side 
walls 18 of the housing at the corners. Since the latch assemblies 21 are 
identical to each other a description of one will suffice. 
The latch assemblies include elongate metallic members 22 which are 
slideable along the inside of walls 18. The members 22 include elongate 
slot portions 23 extending generally axially of the latch members, the 
slot 23 in the embodiment of FIGS. 1 through 5 encompassing the body 
portion 26 of rivet member 27. The rivet members 27 are headed as at 28 
and 29 inwardly and outwardly of the housing and thus it will be seen that 
the latch members 21 are constrained by the headed rivets 27 to slideable 
movement in a plane paralleling the plane of the side walls 18. The side 
walls 18 adjacent their corner portions are provided with slots or 
cut-outs 30 within which are moveably mounted, inwardly directed detent 
portions 31 projecting from the latch members 22. The detent portions 31 
include latching shoulders 32 which face outwardly toward the periphery of 
the housing. The shoulders 32 are adapted to cooperate with a retainer 
ledge of sear 33 formed by a downward projection of the slot 30. 
The slot 30 includes an upwardly inclined cam shoulder 34 which lies behind 
the rear shoulder 35 of the tab 31 when the forward shoulder 32 of said 
tab is engaged against the sear 33. The slot 30 includes a clearance area 
36 which permits an inward travel of the latch members 22 from the 
detented position shown in dot and dash lines in FIG. 3. The latch members 
22 are yieldably, outwardly urged by spring members 37 biased between 
anchor points 38 and 39 on the housing and latch member 22 respectively. 
As will be best appreciated from an inspection of FIG. 3, it will be seen 
that the spring 37 functions to engage the retainer shoulder 32 of tab 31 
against the sear 33, whereby the latch member 22 is prevented from 
springing outwardly under the influence of spring 37. The latch members 22 
include a distal or nose portion 40 projecting outwardly beyond the end 
walls of the housing the uppermost surface 41 of the nose defining a cam 
configuration. 
The device is supplied with the latch members 22 in the partially retracted 
position illustrated in FIG. 1. In such condition the spacing between the 
caming portions 41 of the nose 40 is calculated to coordinate with the 
standardized spacing of the tile support hangers 10. The device is 
installed by merely passing the housing upwardly between an adjacent pair 
of hanger members 10 until the cam surfaces 41--41 of the latch members 22 
engage against the undersurface 12 of the hanger members 10. Further 
upward movements of the housing function to deflect the latch members 22 
progressively inwardly, i.e. toward each other, so as to permit the nose 
portions 40 to spring past the support portions 12 of the adjacent hanger 
members 10. 
In the course of such inward movement as best perceived from FIG. 3 the 
rearmost edge portion 42 of the latch members will eventually engage 
against the cam portion 34 in slot extension 30. The net result of such 
engagement will be to tilt the nose portions 40 in a downward direction 
about the fulcrum defined by the rivet member 26. Such tilting movement 
lifts the detent 31 to a level above the sear 33, whereby the latch 
members 22 are free to spring outwardly without interference between the 
detent and sear. 
In FIG. 2 the lighting fixture is illustrated as having been lifted to an 
intermediate position whereat the nose portions 40 engage against the 
vertical webs 11 of the grids or hanger members. A comparison of FIGS. 1 
and 2 discloses the tilting movement of the latch members 22 resulting 
from the engagement of latch members against cam surface 34 as described 
hereinabove. 
With continued upward movement of the housing the latch members will pass 
to a heightwise position above the portions 14 of the grids or hanger 
members 10. When the housing reaches this upwardmost position, the latch 
members 22 will spring outwardly to the dashed line position of FIG. 2 
from the solid line position depicted in such figure. With the parts thus 
disposed, the detent 31 will lie in the narrow slot portion 42 whereupon 
it will be perceived that the latches are supported at two spaced points, 
i.e. by the engagement of the fulcrum member 27 in slot 23 and the detent 
31 in narrow portion 42 of slot 30. It is thus clear that significant 
movement of the latched members 22 is prevented. The housing may now be 
released and will be supported in position between the grids 10 in a 
proper heightwise orientation with respect to the ceiling tiles C 
surrounding the lighting fixture. 
In FIGS. 6 through 8 there is disclosed an embodiment of the invention 
wherein a degree of heightwise adjustment is permitted. In such figures 
like parts have been given like reference numerals to the prior described 
embodiment. In the (FIG. 6) embodiment, a vertically directed slot 50 is 
formed in side walls 18 of the housing. A lock nut member 51 is disposed 
adjacent the housing wall 18 and the machine screw 52 extends through slot 
23 of the latch member 22 through the vertical slot 50 and into the lock 
nut assembly 51. The lock nut assembly 51 preferably includes a fiber or 
polymeric insert 53 having a threaded aperture 54 complemental to the 
threading of machine screw 52. The insert 53 thus provides frictional 
retention against unthreading of the machine screw 52. 
The device is installed as before, but after installation it will be 
appreciated that a degree of vertical orientation of each of the corners 
of the housing may be effected by releasing the machine screw 52 a few 
turns, setting the housing at a desired heightwise relation by upward or 
downward movement of the machine screw and retainer nut, and thereafter 
retightening the machine screw 52. 
Optionally, but preferably, the latch members 22 are rigidified by having 
their body portions bent to an arcuate or concave configuration as best 
seen in FIGS. 4, 6 and 8. Desireably, a dome or protuberance 55 projects 
inwardly from the side wall portions 18 into the arcuate channel 56 of the 
latch members 22. 
As best seen from FIG. 6 the end walls 16-17 of both described embodiments 
are provided with slots 57 enabling outward movement of the latch members 
22 from a partially retracted position wherein the detent and sear 
components are engaged, to a fully retracted position resulting from 
inward caming of the latch members by interaction with the support grids, 
and finally to a projected position whereat the undersurface of the latch 
members overlie the support grids to afford mounting support for the 
fixture. 
From the foregoing description it will be appreciated that there is 
provided in accordance with the present invention a lighting fixture which 
may be readily mounted between spaced grids of a ceiling support structure 
with a minimum amount of manipulative movements by the installer. In 
accordance with the embodiment of the FIGS. 6 through 8 a degree of 
heightwise adjustment is permitted to allow for irregularities in the 
installation of the ceiling grid supports and/or the ceiling tiles. As is 
conventional, the diffuser member carried by the frame assembly 20 may be 
removed with the frame for relamping, removal of the frame assembly 
likewise permitting access to the latches from the interior of the 
housing. 
As will be apparent to those skilled in the art numerous variations in 
details of construction from the specifics of the illustrated embodiments 
may be made without departing from the spirit of the invention. 
Accordingly the same is to be broadly construed with the scope of the 
appended claims.