Patent Abstract:
A lighting system for illuminating artwork includes a housing; a lamp mounted within said housing and including a halogen bulb and a reflector, said reflector having a dichroic coating; a linear spread lens positioned in front of said lamp and having an etched portion covering less than one hundred percent of a first surface of said lens; and a door associated with said housing and defining an opening therein, said opening having a flattened portion and a rounded portion, said linear spread lens positioned over said opening, and the light emitted by the lighting system being directed through said linear spread lens and said opening. The resulting lighting system produces safe light diffused evenly substantially over the entire surface of a piece of artwork.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the priority of application Ser. No. 10/613,360, filed Jul. 3, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to lighting systems and, more particularly, to a system for safely and effectively illuminating light-sensitive artwork.  
       BACKGROUND OF THE INVENTION  
       [0003]     The lighting of artwork in museums has traditionally been done by gallery style lighting in which a series of individual lights are mounted on a track and aimed at the artwork with overlapping beam patterns. These lights are located on the ceiling or placed high above the artwork to reduce radiant heat and are normally shielded with a UV reducing filter. These systems work well in commercial spaces but are highly undesirable and impractical in residential settings.  
         [0004]     The lighting of art from picture lights is traditionally done with exposed incandescent lamps located in a metal housing that can be rotated to direct the light onto the artwork and prevent direct glare into the viewers eyes. The exposed incandescent lamp generates light by heating the filament to “incandescence”, thereby exposing the artwork to excessive heat. Additionally, these lamps do not properly illuminate the artwork in an even manner.  
         [0005]     The prior art also includes fluorescent lamps. Fluorescent sources offer the benefit of producing less heat than incandescent lamps. However, these lamps also produce high levels of damaging UV rays. Furthermore, fluorescent lamps have difficulty evenly lighting an entire artwork due to poor reflector designs and socket shadows occurring between multiple lamps.  
         [0006]     Halogen based lamps are another alternative light source. Halogen light sources generate large amounts of heat and some UV rays. Halogen lights are available in various wattages. Some halogen lamps, referred to as MR style lamps, are provided with precise mirrored reflectors. These lamps can produce round, narrow beam distribution that can illuminate the entire height of a piece of art. However, MR lamps generally produce round beams of light down an artwork that are difficult to distribute evenly across the width of the work, particularly when the light sources are mounted close to the artwork.  
         [0007]     Recent advances in the prior art include the use of bare halogen lamps in combination with framing shutters or aperture plates. These systems include a single, small light source and limit the projection of light to the area of the canvas. These systems are limited by the fact that the lamp must be mounted at a significant distance out from the artwork in order to evenly illuminate a large piece of art. Examples of these systems are manufactured by DeBruyne Lighting LLC of Florida and Hogarth Fine Art Lighting of England. The system manufactured by DeBruyne includes a UV filter manufactured by Optivex. However, this filter only removes a portion of the harmful UV spectrum. The Hogarth system uses a lamp with a reduced UV ray output rather than a filter. Neither system offers any means of limiting the amount of radiant heat generated by the system. These systems are not generally suitable for lighting larger artworks.  
         [0008]     Light generated by most light sources, such as round halogen and incandescent exposed lamps, is not naturally collimated in the direction of propagation of the light on artwork. Collimation of multiple halogen light sources is often desirable to achieve high color rendering or artwork but is normally combined with excessive radiant heat or damaging UV light.  
         [0009]     Furthermore, MR style lamps have a circular cross-section. Thus, the generated light beam also has a circular cross-section. Where it is desired to generate a light beam having other than a circular cross-section (e.g., rectangular cross-section) the light beam cannot be efficiently transformed from a circular to non-circular shape.  
         [0010]     The present invention is directed to overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0011]     An aspect of the present invention is to provide a system for safely and effectively lighting artwork without exposing the artwork to excessive levels of radiant heat or ultraviolet light.  
         [0012]     Another aspect of the present invention is to provide a system for lighting artwork that results in a more even distribution of light covering the entire area of the artwork.  
         [0013]     In accordance with the above aspect of the invention, there is provided a lighting system for illuminating artwork that includes a housing; a lamp mounted within said housing and including a halogen bulb and a reflector, said reflector having a dichroic coating; a linear spread lens positioned in front of said lamp and having an etched portion covering less than one hundred percent of a first surface of said lens; and a door associated with said housing and defining an opening therein, said opening having a flattened portion and a rounded portion, said linear spread lens positioned over said opening, and the light emitted by the lighting system being directed through said linear spread lens and said opening. The resulting lighting system produces safe light diffused evenly substantially over the entire surface of a piece of artwork.  
         [0014]     In accordance with yet another aspect of the invention, there is provided an associated method of optically correcting a beam of light emitted by a halogen light source for illumination of artwork that includes the steps of emitting a beam of light from a halogen bulb; filtering radiant heat from the beam of light through a reflector surrounding the halogen bulb and having a dichroic coating; laterally diffusing the beam through a linear spread lens positioned in front of the lamp; vertically diffusing the beam through an etched first portion and lighter etched second portion of said lens; and adjusting the color of the beam through a tinted coating on the lens.  
         [0015]     These aspects are merely illustrative of the innumerable aspects associated with the present invention and should not be deemed as limiting in any manner. These and other aspects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the referenced drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the views.  
         [0017]      FIG. 1  is a perspective view of a lighting system for illuminating artwork according to one embodiment of the present invention.  
         [0018]      FIG. 2  is a schematic view of the underside of a lighting system for illuminating artwork according to another embodiment.  
         [0019]      FIG. 3A  is a cross-sectional view of the lighting system of  FIG. 2 , taken along line A-A.  
         [0020]      FIG. 3B  is a cross-sectional view of the lighting system of  FIG. 2 , taken along line A-A, showing the hinged door in a shifted position.  
         [0021]      FIG. 4A  is a top view of a linear spread lens suitable for use in a lighting system for illuminating artwork according to another embodiment.  
         [0022]      FIG. 4B  is a side view of the linear spread lens of  FIG. 4A .  
         [0023]      FIG. 4C  is a bottom view of the linear spread lens of  FIG. 4A .  
         [0024]      FIG. 5  is a schematic view of a lighting system for illuminating artwork installed above a painting.  
         [0025]      FIG. 6  is a perspective view of a lighting system for illuminating artwork according to another embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     In the following detailed description numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. For example, the invention is not limited in scope to the particular type of industry application depicted in the figures. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.  
         [0027]      FIGS. 1-4  illustrate a light for illuminating artwork  10 . The light  10  includes a housing  12  and a mounting arm  14 , by which the light  10  can be mounted to a piece of art, such as a frame surrounding a painting, or a wall adjacent the piece of art. The housing  12  may be arranged in a variety of cross-sectional shapes, including rounded or square, and colors, and has a open surface on one side. The housing  12  may be constructed of aluminum, steel, brass, plastic or any other suitable, rigid material. For most artworks, the mounting arm  14  advantageously positions the housing normally about 5 to 9 inches out from the artwork being illuminated, depending on the height of the work, and aims the lamps  24  (discussed in more detail below) ⅔ to ¾ of the way down the work. The light  10  may also be mounting at the bottom of an artwork, in which case, the lamps  24  would be aimed about ⅔ to ¾ of the way up the artwork.  
         [0028]     A socket holder  16  is supported within the interior of the housing  12 . The socket holder  16  is advantageously constructed of an extruded aluminum material, however, any rigid material is suitable. The socket holder  16  supports at least one light source  22 .  
         [0029]     The light  10  also includes a power source  18 . The power source  18  shown in  FIGS. 1-3  is a standard 110V AC power cord that may be plugged into any standard outlet. The power source may include a transformer  19 . The transformer  19  may be located within the housing  12  or integrated with a power cord. In an alternate embodiment, the power source  18  includes a battery of suitable voltage. The light  10  may also be hardwired into an existing electrical circuit.  
         [0030]     The light  10  may also include a light switch  20 . The light switch  20  may be a simple on/off contact switch to control the flow of electricity to the light source  22  or, alternatively, a dimmer switch to adjust the amount of light emitted by the light source  22 .  
         [0031]     The light source  22  itself may consist of any number of single point lamps  24 , depending on the width of the light required, which is generally dictated by the width of the artwork to be illuminated. If multiple lamps  24  are used, they are preferably spaced 7 to 12 inches from one another. Advantageously, the lamps  24  are halogen narrow beam lamps consisting of a halogen bulb  26  and a reflector  28 . In a particularly preferred embodiment, the halogen bulb  26  is a low wattage MR-11 halogen bulb. The reflector  28  is provided with a dichroic coating that allows all long wave radiation, including radiant heat, to pass through the reflector rather than being reflecting out of the lamp  24  and onto the artwork being illuminated. This significantly reduces the amount of radiant heat to which the artwork is subjected.  
         [0032]     A hinged door  30  is provided to substantially enclose the open side of the housing  12 . The hinged door  30  is provided with an opening  32  corresponding to each lamp  24 . According to a preferred embodiment, the opening is provided with a D-shape. The D-shaped opening  33 , illustrated in  FIG. 6 , is oriented such that the flattened edge  35  of the opening is positioned closer to the surface of the artwork than the rounded edge  37  of the opening. With such an opening, the light from the lamp is emitted with a relatively straight “top edge” that parallels the straight top border of the illuminated artwork, thereby utilizing the emitted light more efficiently and minimizing the potential for spill light (or “bright spots”) from each individual lamp on the frame and provides more even illumination across the top of the painting.  
         [0033]     The hinged door  30  is preferably constructed of a rigid material such as aluminum, steel, or plastic. The hinged door  30  is supported on a first side by the housing by means of a lip  34  on the cover that engages a second lip  36  located along one edge of the open side of the housing  12 . The second side of the hinged door  30  is supported on a ledge located on the opposite side of the housing  12 . The hinged door  30  is secured to the ledge by at least one screw  40  that is inserted through elongated openings  42  in the hinged door  30 . In a preferred embodiment, the housing lip  36  is slightly elongated in order to allow the cover lip  34  and housing lip  36  to mate slideable manner. This arrangement, in combination with the elongated openings  42  in the cover for screws  40 , allows the hinged door  30  to slide laterally relative to the housing  12 .  
         [0034]     The light  10  is provided with a light expanding system that converts the light emitted from the halogen lamps  24  into a “linear” or “planar” “light beam”. The light expanding system includes a linear spread lens  44  positioned over the cover openings  32  corresponding to the lamps  24 . Preferably, the linear spread lens covers the entire opening  32 . The lens  44  spreads the light beam emitted from each lamp  24  evenly across the width of the artwork being illuminated. In the event that multiple lamps  24  are used in the light  10 , the lenses  44  associated with each lamp  24  combine to spread and overlap the light beams emitted from each lamp  24 , thereby providing even illumination across the entire width of the artwork. The lens  44  includes a flat side  46  and a rippled side  48  that serves the purpose of diffusing emitted light laterally. The rippled side  48  is provided with a plurality of rounded ridges. Linear spread lenses of this nature are well known to those in the art. An example of a suitable lens is a Skytex pattern lens. The lens  44  is mounted over the opening  32  in the hinged door  30  with the rippled side  48  facing outward from the light  10 .  
         [0035]     Because lamps are generally located adjacent the top of the artwork, there is a tendency in prior art lamps for the emitted light to be more intense at the top of the work and less intense at the bottom. In embodiments of the present invention, the lens  44  is etched to even the light from top to bottom of an artwork. The etching also minimizes any striations in the emitted light that might be introduced by the lens  44 . The lens  44  is provided with heavier etching  50  on the side adjacent to the artwork and lighter or no etching  52  on the side farther away from the work. In alternate embodiments, there are more than two sections of etching on each lens  44 , each varying in the degree of etching, for example, from lighter to heavier etching. This alternate embodiment allows even finer vertical tuning of the light emitted from the lamps  24 .  
         [0036]     The ideal positioning of the line of demarcation  54  between heavier and lighter etching of the lens  44  relative to the lamp  24 , thereby determining the relative amounts of heavy and light etching, depends on the height of the artwork. For taller artworks, the lighter etching  52 , or no etching, should comprise a greater percentage of the lens  44 . For shorter works, it is preferable that the heavier etching  50  comprise more of the surface area of the lens  44 . In one embodiment, the following general rule of thumb is used to determine the appropriate amount of etching on the lens  44 : (1) for short paintings, i.e., those paintings less than twenty inches (20″) tall, heavier etching  50  is recommended on most of or over the entire surface of the lens  44 ; (2) for medium height paintings, i.e. those paintings between twenty inches (20″) and thirty-five (35″) tall, a balance of approximately half lighter etching  52  and half heavier etching  50  across the surface of the lens  44  is recommended, with the heavier etching being positioned on the side of the lens adjacent to the artwork; and (3) for taller paintings, i.e., those paintings more than thirty-five inches (35″) tall, a balance of approximately half lighter etching  52  and half no etching across the surface of the lens  44  is recommended, with the lighter etching being positioned on the side of the lens adjacent to the artwork.  
         [0037]     It is desirable that the lens  44  be adjustable relative to the lamp  24 . The sliding arrangement between the hinged door  30  and the housing  12  described above is a preferred means of providing this adjustability of the lens  44 . An alternative method is to mount the lens  44  in variable positions associated with the hinged door  30 . The lens  44  may be moved as desired relative to the hinged door opening  32 .  
         [0038]     In a preferred embodiment, the lens  44  is provided with an ultraviolet filter coating, for example, Optivex® by Bausch &amp; Lomb, to reduce the amount of ultraviolet emission from the lamp  24 . Preferably, the ultraviolet filter coating eliminates at least 95% of wavelengths below 400 nanometers. The lens  44  is also provided with a color-correcting tint. The tinting is required to counteract the removal of a portion of the red spectrum from the light emitted by the bulb due to the dichroic coating on the reflector. Without the tinting, light emitted from the light  10  would be slightly greenish in color.  
         [0039]     The hinged door  30  covers the open side of the housing  12 , thereby controlling the emission of light from the housing  12 . In addition, the lens  44  covers the entirety of the hinged door opening  32 . Therefore, most, if not all, of the light emitted by the light  10  passes through the lens  44 . This arrangement ensures that most of the light emitted has been processed through the heat filtering and light expanding systems of the light.  
         [0040]     While the above description has primarily described embodiments of the light  10  having a single lamp  24 , lens  44  and hinged door opening  32 , it should be understood that the same principles apply to lights incorporating multiple lamps  24  and corresponding lenses  44  and hinged door openings  32 .  
         [0041]     Other objects, features and advantages of the present invention will be apparent to those skilled in the art. While preferred embodiments of the present invention have been illustrated and described, this has been by way of illustration and the invention should not be limited.

Technology Classification (CPC): 5