Patent Publication Number: US-6705747-B2

Title: Circular lighting louver

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     None. 
     TECHNICAL FIELD 
     The present invention relates to lighting louvers and more particularly to curvilinear louvers. 
     BACKGROUND OF THE INVENTION 
     Most of those acquainted with lighting louvers are familiar with rectangular arrays of reflectors used in ceiling mount or suspended installations. Such mounts are very common, especially for use with flourescent lights. It is known to use parabolic reflectors in such louver construction for desired illumination characteristics. Calculation of the parabolic configurations is a relatively straightforward procedure due to the rectilinear configuration of the louver grid. 
     High efficiency circular flourescent tubes have recently been developed. However, the light source produced by a circular or other curvilinear light source is not compatible with rectilinear louvers. The origin of the light (light source) is a factor taken into consideration when the parabolic reflector surfaces are considered. A curvilinear light source thus suggests if not, demands, a similarly curved reflective louver. 
     Curvilinear louvers have been produced in the past for use in conjunction with similarly shaped or curved light sources. However, such louvers have been produced with inner and outer parabolic reflector surfaces and with flat baffles extending between the two curved reflector surfaces. Flat baffles are not efficient reflectors when compared with specifically designed parabolic configurations. What was once a rectangular opening or cell in a louver becomes somewhat of a trapezoidal configuration in curvilinear louvers. A long reflector surface is located on one side, a short reflector surface on the other, and baffles that are substantially radially oriented with respect to a center of curvature are spaced apart along the curved reflector. Such spacing results in unfavorable physical shielding angles. 
     The advent of high efficiency circular lamps has thus created the need for a similarly circular louver with at least an approximation of the physical and optical shielding angle characteristics as the linear luminaire light control systems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
     FIG. 1 is a schematic view of a curvilinear lamp and power source of a nature capable of use with the present invention; 
     FIG. 2 is a diagrammatic view illustrating a generalized configuration for a circular louver, it being understood that the actual curvature for the surface as illustrated would be parabolic; 
     FIG. 3 is an enlarged sectional plane illustrating a preferred configuration for first and second reflectors, and baffle with a section of a lamp included; 
     FIG. 4 is a perspective view of a preferred louver looking upwards toward leading edges of the reflectors; 
     FIG. 5 is a perspective view looking downwardly at trailing edges of the louver and a lamp mounted therein; 
     FIG. 6 is a cross-sectional view taken substantially along line  6 — 6  in FIG. 5; 
     FIG. 7 is an enlarged fragmented view taken substantially as indicated at  7 — 7  in FIG. 5; and 
     FIG. 8 is a cross-sectional view taken substantially along line  8 — 8  in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     Before describing elements in detail, brief general descriptions will be given of aspects of the invention. 
     In a first aspect, a curvilinear lighting louver  10  is provided in which a first reflector  12  is formed in a curvilinear ring configuration about an axis X. The first reflector  12  includes a first parabolic reflector surface  14  that faces toward the axis X. A second reflector  16  is formed in a curvilinear configuration that is substantially concentric with the first reflector  12 . The second reflector  12  includes a second parabolic reflector surface  18  facing away from the axis. Baffles  20  connect the first and second reflectors  12 ,  16  between the first and second parabolic reflector surfaces  14 ,  18 . The baffles  20  includes third parabolic reflector surfaces  24  extending substantially radially with respect to the axis X. 
     Another aspect of the invention includes a lighting louver  10  in which first and second reflectors  12 ,  16  are formed in an approximate truncated toroid configuration about an axis X with a first parabolic reflector surface  14  on the first reflector  12  facing toward the axis, and with the second reflector  16  having a second parabolic reflector surface  18  facing away from the axis X. The first and second reflectors include leading edges  28 ,  32  that are radially spaced from one another to form a circular light discharge opening  35 . Baffles  20  are radially oriented with respect to the axis X and include third parabolic reflector surfaces  24  joining the first and second parabolic surfaces  14 ,  18 . 
     In a further aspect, a circular lighting louver  10  is provided with a first reflector  12  formed in a circular configuration on a first radius about an axis X. A first parabolic reflector surface  14  is provided on the reflector  12 , facing toward the axis X and including a leading edge  28 . A trailing edge  29  is spaced axially from the leading edge. A second reflector  16  is formed in a circular configuration on a second radius that is less than the first radius and that is substantially concentric with the first reflector  14 . The second reflector  16  includes a second parabolic reflector surface  18  facing away from the axis X. Substantially radial baffles  20  join the first and second reflectors  14 ,  16  and include third parabolic surfaces  24  joining the first and second parabolic surfaces  14 ,  18 . The baffles  20  further include recesses  42  that are axially spaced from the third parabolic surfaces  24  and are disposed axially between the leading and trailing edges  28 ,  29  for receiving a circular lamp L. 
     Referring now in greater detail to various preferred elements of the present invention, attention is first drawn to FIG.  1 . FIG. 1 is a simplified illustration to basically identify an exemplary curvilinear configuration of the louver  10 . The illustrated configuration is that of a truncated, or, more specifically, a frusto-torroidal form. It should be understood, however, that the illustration is simplified to illustrate a very basic configuration and that the curved surfaces  14  and  18  are preferably parabolic configurations that are generated about the central axis X, at least in the particular embodiment illustrated. 
     It should also be noted that other curvilinear configurations for the louver may be provided that may not be perfectly circular. It is, however, most desirable that the configuration be curvilinear as opposed to rectilinear. 
     Thus, the louver  10  may be formed about a single axis X as shown, or about multiple axes. In either instance, the opposed reflector members  12 ,  16  will remain substantially equally spaced with respect to the axis or axes about which the reflectors bend. 
     Variations may also be found within the illustrated circular structures. For example, note the relative diameter of the louver  10  shown in FIG. 1, particularly that of the second reflector  16  with respect to the center axis X. This may be compared to the diameter illustrated in FIG. 6 for a similar reflector  16  in an embodiment in which the diameter is significantly larger. 
     It should also be noted that the present louver  10  may be produced using various materials and construction techniques. For example, the baffle may preferably be formed of injection molded plastic. Alternatively, the baffle may also be formed of specular aluminum. Other materials and construction techniques may also be used. 
     Looking once again at FIGS. 2 and 6, it may be seen that the preferred examples illustrated include leading and trailing edges  28 ,  32 ;  29 ,  33  are arranged in substantially parallel planes that are substantially perpendicular to the axis X. While this configuration is preferred, it may be that the edges may be angularly, axially, or angularly and axially offset from one another depending upon directional and/or aesthetic requirements. It is preferred, however, that the edges be substantially aligned and parallel as generally indicated. 
     The leading and trailing edges define top and bottom openings in the illustrated examples. The bottom opening as illustrated, is defined by the light discharge opening  35  which, in the illustrated configuration, is substantially circular. The opposed top opening is provided primarily for physical access to facilitate reception and removal of the lamp L. However, it is entirely conceivable that a cover or other form of top surface (not shown) could be provided over the trailing edges for decorative or light control purposes. 
     The radial distance between the trailing edges  29 ,  33  may vary as exemplified once again by a comparison of FIGS. 2 and 6. This radial dimension is considered the radial pitch of the louver. Radial pitch may be considered as a constant in parametric calculations for determining the parabolic curvatures and axial dimension of the respective surfaces  14 ,  18 . A desired pitch or spacing, coupled with the desired physical cutoff or shielding angle P (FIG. 3) may be used to determine the axial height between the leading and trailing edges. This angle is identified by a line in FIG. 3 extending between the trailing edge  33  of the second reflector  16  and the leading edge  28  of the first reflector  12 . The physical shielding P angle is preferably the same for the trailing edge  29  and leading edge  32 . 
     It is desirable to locate the lamp L with its outward diameter tangential to the above lines which identify the physical cutoff angles. To this end, the baffles  20  are provided with lamp receiving recesses  42  that facilitate axial positioning of the lamp in the desired tangential relationship. Most preferably, the recesses  42  are substantially centered in the radial direction between the reflectors  12  and  16 . 
     The preferred number and spacing of the baffles  20  about the louver  10  may be a function of the desired physical cutoff angle between adjacent baffles  20 . Most preferably, the physical cutoff angle P between the first and second reflectors  12 ,  16 , is substantially equal to the physical cutoff angle P 1  (FIG. 8) which is measured diagonally across the respective openings defined by successive baffles  20  in the louver. The diagonal line for each pair of baffles extends from a radial inward corner at one baffle trailing edge  41  to an outward corner at the intersection of the adjacent baffle leading edge  40  and parabolic surface  14 . 
     By spacing the baffles  20  to achieve the desired physical shielding angle P 1  and the radial cutoff angle P, an efficient and desirable distribution of light may be obtained. This is true because the angle P 1  measured in the diagonal as indicated, represents the “worst case” observation angle from any position below or to the leading edge side of the louver. 
     It is noted that the preferred forms of baffles  20  each include opposed parabolic surfaces  24 . These surfaces extend from the leading edges  40  toward the trailing edges  41 . However, the parabolic surfaces  24  are interrupted by substantially parallel and flat axial surfaces  43 . The surfaces  43  are situated axially between the trailing edges  41  and leading edges  40  and more particularly between the respective leading and trailing edges of the first and second reflectors. 
     The surfaces  43  are provided to minimize passage of light that would otherwise cause flash or reflection in an undesirable manner, and to permit use of the parabolic surfaces  24  to maximum advantage. It may be understood that should the correct parabolic surfaces  24  be axially extended to the top or trailing edges of the first and second reflectors, a significant amount of space would be occupied by the top surfaces of the baffles, thereby creating an undesirable and inefficient environment adjacent to the light source. 
     By producing the light louver with the above described characteristics, a light control system may be obtained wherein the physical shielding or cutoff angle is substantially the same about the axis or axes from which the louver is formed. Thus, the present curvilinear louver may function with properties similar to those enjoyed by common rectilinear louver systems. 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.