US 3015721 A
Description (OCR text may contain errors)
Jan. 2, 1962 E. F. GUTH, JR y I 3,015,721
FLuoREscENT LIGHTING FIXTURES Filed April 4, 1960 2 Sheets-Sheet 1 A? TURA/frs,
Jan. 2, 1962 E. F. GUTH, JR 3,015,721
FLUORESCENT LIGHTING FIXTURES Filed April 4, 1960 2 Sheets-Sheet 2 United States Patent Office 3,i5,72l Patented Jan. 2, 1962 Missouri Filed Aer. 4, 1960, Ser. No. 19,587 4 Claims. (Cl. Mtl-51.11)
This invention relates to lighting fixtures for fluorescent lamps, and more particularly to fixtures adapted for use with suspended ceilings built on a predetermined module.
A common method of creating a suspended ceiing involves suspending a frame work of narrow horizontally spaced rails of inverted T or similar cross section, thereby to support panels of acoustical tile or the like at their margins. The rails have laterally projecting flanges on which the margins of the ceiling panels rest, whereas the rail stems or vertical webs are connected to hangers. In the interests of economy, the industry has seen fit to establish certain standard dimensions for such panels and supporting rails, and it so happens the established module has created a serious problem for the manufacturers of lighting fixtures of the type adapted to be recessed within the frame work and lie flush with the panels.
The problem arises because the manufacturers of tubular fluorescent lamps have also established standard dimensions for their lamps. A popular lamp and its sockets require a space of at least four feet in length, hence a conventional enclosing troller must be sightly longer than four feet (by an amount corresponding t the thickness of its end walls). The space available between the stem parts of the rails of a standard suspended ceiling is exactly four feet (or slightly less), hence a conventional fixture cannot be fitted therein. In addition, there is a problem in removing and installing lamps. The opening between the flange parts of the rails is less than four feet, and prevents the lamps from being pushed straight up without tilting, as is customary with more conventional fixtures. Although the lamps can be tilted during insertion, this means making the trofler exceptiona'ly wide or deep.
Indeed, these difiiculties have led to considerable discussion in the industry about manufacturing and stocking a special lamp, whose length would be slightly less than that used for most four foot fixtures. Although the problem is serious, the expenses of retooling for and stocking specialjlamps and fixtures are considerable. Accordingly, it is the object of this disc`osure to show how a fixture can be made to fit with modular suspended ceilings and handle conventional lamps, without making the fixture excessively wide or deep.
Briefly, the fixture is made with a conventional elongate troffer of inverted U cross section an-d contains standard lamps, sockets, reflectors and the like, but the end walls of the troffer are modified, as will be explained. The customary diffusor is mounted in the bottom of the troller, although the diflusor must necessarily fit within the module or the opening defined by the T-rails of a modular ceiling.
The end walls of the troffer are formed to have an overall length (outside dimension) of forty-eight inches, except for certain areas opposite the lamp sockets, which are indented outwardly a distance corresponding to the wall thickness, thereby to accommodate the sockets and standard lamps which measure forty-eight inches. The indented portions of the end walls may also be formed as knock-out sections, which are removed when fixtures are mounted end-to-end in a continuous row, hence the fixture length fits with the ceiling module of four feet.
The lower portions of the Side and end walls are configurated to lit with T-rails of the framework, the lower flanges of which project horizontally a half inch from the vertical stems. The bottom of the fixture has a width greater than eleven inches but less than twelve inches and a length greater than forty-seven inches but less than forty-eight inches. In the case of the end walls, the lower portions thereof are bent inwardly about a half inch (to be coextensive with the edges of the T-rail flanges) and then bent outward to rest upon the rail flanges whi'e providing space for the center webs of the rails.
The resulting reduction in the length of the bottom opening to forty-seven inches presents a problem in lamp insertion, but this diiliculty is herein overcome by providing a small opening in at least one of the end walls between the sockets for temporarily accommodating an end part (the prongs) of the lampi. The prongs are about a quarter of an inch in length, hence when one end of the lamp is inserted first so that the prongs enter the opening between the sockets, the opposite end is brought inwardly a distance sufficient to clear the lower end of the troffer and adjacent lamp socket, as will be explained.
Other features of the invention will be in part apparent from and in part pointed out in the following detail description taken in connection with the accompanying drawings, in which:
FIG. 1 is a longitudinal vertical section of a lighting fixture mounted within a suspended ceiling;
FIG. 2 is a cross-section taken on the line 2-2 of FIG. l;
FIG. 3 is a cross-section taken on the line 3-3 of FIG. l showing the end of the fixture; and
FIG. 4- is a diagrammatic view similar to FIG. 1, but illustrating how the bulb is inserted within the fixture.
Referring to the drawings, there is shown part of a typical suspended cei'ing. A framework of panel-supporting rails 1 is hung by suitable hangers (not shown) from the rough ceiling or other structure of the building'. The rails usually have horizontal bottom flanges 3 on which the panels 5 rest and vertical webs 7, which are fastened to the hangers. The lighting fixtures 9 are recessed within the framework so as to be framed by the rail flanges 3, and may rest upon flanges or be supported independently.
The panels 5 typically are manufactured in standard dimensions (one, two or four feet), hence the rails must be placed to fit with the module of the panels. In order to achieve symmetry of appearance and convenience in installation, the lighting fixtures must also fit with the module. In the majority of instances, the lighting fixtures fit within a rectangle formed by rails spaced one foot transversely and four feet longitudinally center-to-center. For this reason, the fixture can be no wider than twelve inches or longer than forty-eight inches; in fact, lthe fixture must generally be slightly smaller at its lower margins if it is to fit between the vertical webs 7 flat against the flanges 3.
The flanges typically are each a half inch in width (the full width of the rail then being an inch), hence the opening defined by the edges of the rai's is only fortyseven by eleven inches. The T-rail type of trarne is illustrated, but it will be understood other rail forms can also be utilized.
The lighting fixture is largely of conventional construction, only certain details being changed to achieve the results desired, hence no great retooling expense is necessary. A trofler is formed by an elongate inverted trough 11 having a top wall 13 and side wals 15, the side walls being enlarged outwardly at their lower margins 17 and having inturned flanges 18, which seat upon theV rail flanges 3 while providing space for the web portions 7 of the rails (FIG. 2). Accordingly, the lower portion of the fixture is of a width greater than eleven inches but less than twelve inches.
The trofer is divided by a partition or reflector 19 into an upper space 2i containing a ballast or other equipment, and a lower space 23 containing lamps L. The lamps extend substantially the length of the trofier and are held at their ends within sockets 25, which are fastened to and depend from the wall 19. The lower portions of the socket measure three-eighths of an inch in thickness, and the lamps measure forty-seven and onefourth inches from the inner face of one socket to the inner face of its opposite socket, The lamps also have prongs P, which are received within the sockets in contact with electrical terminals, as will be understood by those skilled in the art.
The above lamp and socket dimensions are established as standards by the lamp and socket manufacturers, hence the manufacturer of the fixture must provide a space at least forty-eight inches in length for the lamps and sockets.
Referring to FIG. 1, the trofier li is closed at its ends by wall-forming plates 27, with marginal flanges 29 overlapping the end margins of the member 1l. It will be noted that the end walls are divided along a broken cut 31 into a peripheral portion 33 and a central section 3S, and the section 35 is set outwardly relative to the peripheral area 33, sections 35 being knock-out sections secured only by thin narrow nicks 37. The two sections 35 lie opposite the lamp sockets and are spaced apart exactly forty-eight inches measured from their inner surfaces, thereby to accommodate the standard lamps and sockets, whereas the outer portions 33 are inset inwardly a distance corresponding to the thickness o f the end walls, so that the length of the fixture is fortyeight inches measured at the outer surfaces of areas 33. The fixture length is slightly greater at the sections 35, but this is not important except where fixtures are mounted end-to-end, in which event no end closure is needed. Where the fixtures abut, the sections 3S may be removed.
The lower margins at the ends of the troffer are formed by specially shaped strips 39 which are secured at their ends to the parts 33 and 17. As viewed from the side the strips 3? converge inwardly at 4i to the bottom of the fixture, and are then bent outwardly to form flanges 43, which rest upon flanges 3 while providing space for the web portions 7 of the rails. Preferably, flanges 43 have inner corners 45 spaced apart about forty-seven inches so as to act as a frame for the diffusor D, which is removably held on hangers 47. The difiusor normally rests upon the side flanges 18, but slides out for access to the lamps.
In more conventional fixtures, the difiusor opening is forty-eight inches in length, hence the lamps could be pushed straight up into the sockets. When the fixture is recessed within a modular suspended ceiling, the rail fianges reduce the opening therebetween to forty-seven inches in length, and with the fixture described above, the diffuser opening is only forty-seven inches long. Since the lamp lacks only a quarter of an inch of being fortyeight inches in length, difficulties would arise in fitting it into the fixture, but the problem is herein overcome by forming a small opening in one of the end walls of the housing.
The opening is a narrow slot 51 extending horizontally at the level of the lamp sockets, and since the sockets are spaced apart, as indicated, the end prongs of a lamp can first be inserted in a slot therebetween before swinging the other end into the fixture. It has been found that the slot l need only accommodate the prongs P of a lamp. When the prongs are so inserted at one end, the other end of the lamp is moved inwardly relative to the adjacent end of the fixture a distance suflicient to clear the rail fiange 3 and socket of the fixture.
This will be apparent from the measurements of the lamp, sockets and fixtures. The bulb proper is fortyseven and one-fourth inches long, the prongs are each one-fourth of an inch in length, and the sockets are each three-eighths of an inch thick. Consequently, when the prongs at one end are inserted through slot 51 with the adjacent end of the bulb between two sockets, the other end is moved longitudinally a distance of five-eighths (three-eighths plus one-fourth) of an inch, and hence will clear the flange (one-half an inch) and the adjacent socket (three-eighths of an inch). This end of the lamp is then inserted in its socket, whereupon the other or first end is swung down and up into its socket, it being understocd the sockets have downwardly opening slots for admitting the lamp prongs.
From the foregoing, it will be apparent that I have provided a fixture for suspended ceilings, which fixture overcomes the difficulties heretofore experienced. Changes in and modifications of the construction described may be made, however, without departing from the spirit of my invention or sacrificing its advantages.
Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:
l. ln a substantially-enclosed fluorescent lampl fixture for use in a suspended ceiling having panel-supporting rails centered on a predetermined module, the fixture having an elongate housing formed with top, side and end walls and lamp sockets enclosed within the housing at opposite ends thereof, the fixture being adapted to utilize a tubular lamp having terminal prongs at its ends with the dimension between the ends of the prongs being greater than that defined by the opening of said panelsupporting rails; the improvement that comprises said end walls being spaced a distance substantially equal in distance to that of said predetermined module in order to permit the mounting of said fixtures end-to-end Within the pattern of the module, and at least one of the end walls being formed with an opening adjacent to but laterally spaced from a socket, said opening being of a size sufiicient to admit only the terminal prongs at one end of the lamp, thereby to facilitatethe insertion and removal of the lamp without an excessively large housing while maintaining a substantially enclosed condition.
2. A fixture as set forth in claim l wherein said tubular lamp has a predetermined maximum cross sectional dimension, the terminal prongs being of a cross sectional dimension less than said other cross sectional dimension, and said opening being in the form of a slot, the width of the slot being greater than the cross sectional dimension of said prongs but less than the maximum cross sectional dimension of lthe lamp.
3. In a fluorescent lighting fixture having a housing with side and end walls and sockets mounted within said housing at the opposite ends thereof to accommodate a tubular fluorescent lamp of predetermined length; the improvement that comprises said end Walls being located immediately adjacent the outer surfaces of said sockets, thereby to provide a fixture of minimum length, said end walls having lower bottom margin formations projecting inwardly a distance such that the opening defined therebetween is less than the length of said tubular lamp, thereby creating a problem in inserting the lamp, the lamp having terminal prongs at its ends, which terminal prongs are of a cross sectional dimension smaller than that of the intervening portion of the lamp, and a slot formed in at least one end wall in offset relationship to the socket, the slot being of a size greater than the prongs of the lamp and less than the intervening portion thereof, thereby to facilitate insertion of said lamp while permitting a relatively small housing in comparison with that required in the absence of said end opening.
4. A fluorescent lamp lighting fixture as set forth in claim 3 having a pair of lamp sockets at each end of the housing, said sockets being disposed along a line generally parallel to the lower edge of the end wall and being spaced a distance greater than the maximum cross sectional dimension of the tubular lamp, thereby to 'admit an end of a lamp therebetween, said slot being located in the end wall between the pair of sockets.
References Cited in the ile of this patent UNITED STATES PATENTS Zurawski Nov. 9, 1954 Spinetta July 19, 1955 Frzzel et al Aug. 5, 1958 Sorenson Feb. 23, 1960