Lighting Fixture Assembly with Track-Extending Rotation Arm

FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of designer lighting systems for theatrical, museum, retail, and other applications. The invention relates more particularly to a lighting fixture assembly using a parabolic aluminized reflector

(PAR) lamp.

BACKGROUND OF THE INVENTION

[0002] Ellipsoidal reflector (ER) light fixtures were introduced commercially in

1933 by Kliegl Brothers and Century Lighting and have been used ever since for theatrical spotlight applications. ER fixtures, which continue to be widely used today, include a tubular lamp positioned in a spun metal reflector that focuses the light through a lens or series of lenses to allow for "framed" or very precisely controlled illumination. Modern ER light fixtures come in fixed focal length and variable focal length (zoom) models for adjusting beam spread. ER light fixtures allow for patterns or images to be produced by inserting a stamped metal plate called a "gobo" into the light path. Drawbacks of ER fixtures include inefficiency, high heat generation, and large size. In order to use an ER light fixture outside or in a damp or wet location, the fixture must be enclosed in a metal and glass housing that keeps it completely dry. This housing, in combination with the large fixture size, makes the combined fixture about the size of a fire hydrant. This limits their use and makes maintenance and re- lamping very complicated.

[0003] About six years after ER fixtures were introduced, a parabolic aluminized reflector (PAR) lamp was disclosed in U.S. Patent No. 2,148,314 issued February 21, 1939, and was incorporated in 1940 model year automobiles. Since then, PAR lamps have been widely used for lighting throughout the entertainment and retail industries.

A PAR lamp is a type of sealed beam lamp having a reflector, a filament, and a front lens (usually of clear glass) permanently attached to form a unitary lamp assembly, wherein the reflector, filament, and lens are optically aligned and sealed at the factory.

PAR lamps are available in an assortment of diameters, wattages, and beam spreads (narrow spot, medium flood, wide flood, etc.). Each PAR lamp is received in a simple lighting fixture which typically has a cylindrically-shaped body referred to as a "can." The fixture body or can may be adapted to hold color media ("gels" or colored glass) in place to filter the white light from the PAR lamp to provide desired color effects. PAR lamps are often favored over other lamps because the fixtures are simple and the lamps maximize beam power for a given lamp wattage. PAR lamps also do away with maintenance problems that negatively affect the long term performance of a lighting fixture that may be associated with other lamps, such as dirty reflectors and misalignment of the lamp within the optical train resulting in decreased efficiency. In addition, PAR lamps are widely available and relatively inexpensive. However, in order to vary both the beam spread and the lumen output from a PAR lamp lighting fixture, it has heretofore been necessary to change the PAR lamp to a PAR lamp having a different beam spread or wattage rating. This is cumbersome and requires a supply of PAR lamps having different beam spreads and wattages.

[0004] ER lamp fixtures and PAR lamp fixtures have existed side-by-side in the entertainment industry for over sixty years, with designers choosing one or the other based on specific lighting requirements. Consequently, designers have had to accept the shortcomings of whichever type of fixture is chosen.

SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to provide a PAR lamp fixture assembly that enables beam spread and lumen output to be readily varied without changing the PAR lamp. [0006] Accordingly, a lighting fixture assembly formed in accordance with an embodiment of the present invention comprises a lighting fixture including a fixture body having a lamp socket and a framing attachment removably mounted on the fixture body, and a PAR lamp mounted in the lamp socket, wherein the framing attachment has an adjustable lens assembly arranged to refract light emitted by the PAR lamp, whereby beam spread may be varied by adjusting the lens assembly. The

adjustable lens assembly may include a removable lens barrel having at least one lens, whereby beam spread is varied by exchanging the lens barrel with a different lens barrel or by reconfiguring the lens or lenses in the lens barrel. The lens assembly may also be in the form of a variable focal length (zoom) lens assembly that is rotatably or slidably adjusted to change beam spread. The framing attachment may also be used to shape the beam or alter the lumen output of the fixture. The PAR lamp may be a high-intensity discharge (HID) lamp, an incandescent lamp, or other type of PAR lamp. [0007] In another embodiment, the lighting fixture assembly further comprises a housing for ceiling mount installation. The housing includes a top wall, a bottom wall having an aperture, and at least one side wall connecting the top wall and the bottom wall; a ballast box fixed to the housing and defining a wiring chamber opening into the housing; an electronic ballast (if required by the type of lamp) received in the ballast box; and a rotation arm including a proximal end portion, a distal end portion, and a track extending between the proximal and distal end portions. The proximal end portion of the rotation arm is mounted to the top wall of the housing to enable the rotation arm to be pivoted relative to the top wall in a rotational plane. The lighting fixture is connected to wires in the wiring chamber and further includes a yoke having a stem portion releasably engaging the track of the rotation arm to permit the lighting fixture to be selectively positioned at a desired location along the rotation arm, the fixture body being pivotably suspended in the yoke for tilting about a tilt axis extending parallel to the rotational plane of the rotation arm. The housing further includes a support panel spaced from the top wall, the support panel having a rotation opening allowing access to the track of the rotation arm, wherein the distal end portion of the rotation arm is supported by the support panel. Clamp knobs are associated with the distal end portion of the rotation arm, the yoke stem, and the yoke tilt axis for releasably locking the lighting fixture in a chosen orientation relative to the aperture in the bottom wall of the housing. In this way, the fixture body and lens assembly are fixably adjustable relative to the aperture in four degrees of freedom. The proximal end portion of rotation arm may be pivotally mounted to the top wall by a fastener having a sleeving loop such that wiring from the electronic ballast may

extend through the sleeving loop to keep it out of the way of the lighting fixture and light beam.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

Fig. l is a partially-sectioned side view of a lighting fixture assembly formed in accordance with an embodiment of the present invention;

Fig. 2 is a side cross-sectional view showing a lighting fixture assembly formed in accordance with another embodiment of the present invention;

Fig. 3 is a front cross-sectional view showing the lighting fixture assembly of Fig. 2;

Fig. 4 is a bottom plan view of a housing of the lighting fixture assembly shown in Figs. 2 and 3; and Fig. 5 is a perspective view showing how the lighting fixture is mounted within the fixture housing in the embodiment of Figs 2-4.

DETAILED DESCRIPTION OF THE INVENTION

[0009] Fig. 1 shows a lighting fixture assembly 10 formed in accordance with an embodiment of the present invention. Assembly 10 comprises a lighting fixture including a generally cylindrical hollow body 12 having a lamp socket 14 connected to wiring 16, a yoke 18 in which body 12 is pivotally suspended for tilting about a tilt axis defined by pivot pins 19 (only one of which is visible in Fig. 1), and a framing attachment 20 removably mounted on fixture body 12. Lighting fixture assembly 10 further comprises a PAR lamp 15 mounted in lamp socket 14. PAR lamp 17 includes a permanent integral lens 17.

[0010] Framing attachment 20 includes a shutter portion 22 adapted for mounting on body 12 and a lens assembly 21 in the form of a removable lens barrel 24 extending from the shutter portion and held in place by a retaining screw 30 extending through aligned holes in shutter portion 22 and lens barrel 24. Lens barrel 24 carries

at least one focusing lens 28 for refracting the beam emitted by PAR lamp 15. A suitable lens barrel and lenses are available from Litelab Corp. of Buffalo, New York under the designation LQ-250, which provides three configurations: a three-lens configuration for wide beam spread, a two-lens configuration for medium beam spread, and a single-lens configuration for narrow beam spread. To change beam spread without changing PAR lamp 15, users may simply choose among lens barrels having different beam spread configurations and install a selected lens barrel, or they may change the beam spread configuration of a single lens barrel by removing the lens barrel, inserting or removing lenses and spacers, and then reinstalling the lens barrel on the shutter portion. In the mentioned LQ-250 lens barrel and lens system, up to three identical lenses are used, however it is also contemplated to use lenses having different focal powers. As an alternative to lens barrel 24 of fixed focal length, lens assembly 21 may be in the form of a variable focal length (zoom) lens assembly as is known in the art. The term "lens assembly" is intended to encompass both fixed and variable focal length lens assemblies, and adjustment of the lens assembly is intended to encompass reconfiguration and replacement of a fixed focal length lens assembly, as well as zoom adjustment of a variable focal length lens assembly.

[0011] Fig. 1 also shows four shutters 26 slidably received through respective slots in the shutter body for positioning in the light beam path.

[0012] In the embodiment shown in Fig. 1, framing attachment 20 is removably mounted on fixture body 12 by a lid ring 32. An inner sleeve 36 is fixed to lid ring 32 by fasteners or welding. Shutter portion 22, which includes an annular flange 23, is inserted into sleeve 36 and may be held in place by a retaining spring or fasteners (not shown). Lid ring 32 is mounted on fixture body 12 by a radially adjustable thumbscrew 34; a stud (not shown) may also be provided to mate with a corresponding hole (also not shown) in body 12 to provide a second point of attachment. As may be understood, sleeve 36 acts as a baffle to minimize stray light leakage at the junction between fixture body 12 and framing attachment 20. [0013] PAR lamp 15 may be high-intensity discharge (HID) or incandescent lamp sized for receipt by fixture body 12. Lamp sizes PAR-20, PAR-30 and PAR-38 are

known to be suitable for a variety of applications, but the invention is not limited to these sizes.

[0014] Various mounting configurations are available for installing lighting fixture in an environment. For example, assembly 10 may be mounted on a track or busway, connected by a theatrical C-clamp to a pipe and powered through an electric line cord, or mounted using a universal bracket. Assembly 10 may also be mounted in a fixed-location ceiling canopy configuration. In these applications a remotely mounted ballast box or wiring chamber may be provided. It is contemplated to provide sealing technology, known in the art, to adapt lighting fixture assembly 10 for installation in damp or wet environments.

[0015] Reference is now made to Figs. 2-5, which illustrate an optional fixture housing 40 of lighting fixture assembly 10 useful for recessed installation in a ceiling or wall 8. Fixture housing 40 includes a bottom wall 42 and a top wall 52 connected by side walls 44, 46, 48, and 50. Housing 40 further includes a support panel 54 beneath and parallel to top wall 52 having a circular rotation opening 55. A light- transmitting aperture 56 is provided through bottom wall 42. Light transmitting cover glass may be optionally provided over this aperture. Fixture housing 40 also includes a ballast box 58 fixed to side wall 46 and communicating with the interior of housing 40 through an opening 60 in side wall 46. Ballast box 58 encloses an electronic ballast 62 and wiring associated therewith. As may be seen, wiring 16 is connected to electronic ballast 62. If the style of lamp does not require a ballast this area is used as the wiring compartment for the attachment to the building wiring system. Housing 40 may be installed in fully recessed arrangement with respect to ceiling 8 by fasteners 64 or other hardware appropriate for the material and orientation of ceiling or wall 8. As will be understood by those skilled in the art, housing 40 and/or the fastening hardware may be modified for partially recessed or surface mounting on ceiling or wall 8. Housing 40, fixture body 12, and framing attachment 20 are preferably provided with a black finish. [0016] In the illustrated embodiment, fixture body 12 and framing attachment 20 are fixably adjustable relative to aperture 56 in four degrees of freedom. A rotational degree-of-freedom is provided by mounting yoke 18 on a rotation arm 66 that is

pivotally mounted to top wall 52 at a central location by a fastener 68 such that rotation arm may rotate through 360° about an axis defined by fastener 68. In the present embodiment, rotation arm 66 includes an inverted U-shaped mounting piece 66A and an elongated U-shaped extension piece 66B having its proximal end portion mated with mounting piece 66A and its distal end portion supported by support panel

54. Access to rotation arm 66 is provided through rotation opening 55 in support panel 54. Fastener 68 is shown as including a sleeving loop 69 through which wiring 16 may be routed to keep it out of the way of the fixture body 12 and framing attachment 20. Nuts 70 and 72 are adjustable to clamp mounting piece 66A to top wall 52, and a clamp 74 is associated with the distal end portion of the rotation arm for releasably locking the distal end portion of extension piece 66B to support panel 54, whereby the rotation arm 66 may be releasably secured at a selected rotational position relative to the top wall. [0017] A radial degree of freedom is provided by releasably engaging a stem portion of yoke 18 in a linear track 76 extending between the proximal and distal end portions of extension piece 66B to permit the lighting fixture to be selectively positioned at a desired location along rotation arm 66. Track 76 may be a slot, rail, or channel configured to mate with the stem portion of yoke 18. A pivot degree of freedom is provided by the fact that yoke 18 may be pivoted about a pivot axis defined by its stem portion. A clamp knob 78 may be associated with the stem portion of yoke 18 to releasably lock the stem portion of the yoke to rotation arm 66 when the lighting fixture is at a desired position along the track and at a desired pivot position about the pivot axis defined by the yoke's stem portion. [0018] A tilt degree of freedom is provided about the tilt axis defined by pivot pins 19 joining fixture body 12 to yoke 18. A clamp knob (not shown) may be provided for releasably securing fixture body 12 and framing attachment 20 at a desired tilt angle.

[0019] As may be understood, the beam spread of PAR lamp 15 may be adjusted without the need to change lamps by exchanging or reconfiguring lens barrel 24 (accessible through aperture 56) on framing attachment 20 or by operating a zoom adjustment if lens assembly 21 is a variable focal length lens assembly, and the

direction along which the beam is directed may be adjusted in the four degrees of freedom described above. Thus, the invention dispenses with longstanding and unchallenged acceptance in the art that PAR lamp beam spread is solely determined by the chosen PAR lamp and its lens 17, and makes the benefits of PAR lamps available for a wider variety of lighting applications and environments.