Abstract:
An image projector that drops into the accessory slot of a luminaire and projects high quality images printed on plastic slides in full color and photographic detail for extended time periods without heat degradation. The projector comprises a cooling fan, infrared and ultraviolet light filter means, and an inexpensive and removable slide assembly comprising a plastic image slide, a protective film slide and at least one mounting plate. The cooling fan is combined with layered, reflective filters to create a protected environment for the plastic image slide to survive the extreme heat at the gate of today&#39;s efficient luminaires. The plastic image slide is created on a plastic sheet using conventional computer printing technologies.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/334,717 filed Oct. 31, 2001, which is incorporated herein by reference. 
    
    
     FIELD OF INVENTION 
     This invention generally relates to a device for projecting low cost, high-resolution images from existing lighting fixtures and, more particularly, to a combination image slide holder and cooling device for projecting images printed on plastic transparencies from commercially available theatrical and architectural luminaires for extended time periods. 
     BACKGROUND OF INVENTION 
     In typical theatrical and architectural applications, luminaires are used to direct bright or dimmed, sharp or soft-edged illumination toward a subject by focusing intense light from a high-energy lamp through its lenses. For example, luminaires may be used for spotlighting, projecting images such as logos or signs, or enhancing logos, signs, products or other goods. Four of the most common commercially available luminaires are the ETC Source Four, the Altman Shakespeare, Strand SL, and the Selecon Pacific Cool Light. 
     In addition to illuminating a subject, it is often desired in theatrical and architectural applications to provide a pattern or image in the light, or to change the light&#39;s color, brightness, beam diameter or focus. To achieve such effects, luminaires typically include an accessory slot in the body of the luminaire and/or an accessory holder on the front end of the luminaire. The accessory slot may be used as a holder of metal or glass patterns, a drop-in iris, a gobo rotator or a dual gobo rotator. The front accessory holder may be used for holding color frames, glass color frames, donuts, snoots or color changers and/or combinations of accessories as required. Although some of these devices may be used to project an image from a luminaire, many of the devices are expensive to fabricate because of the materials required to withstand the heat generated by the luminaire&#39;s lamp (for example, metal or glass), or they do not have a long use life, or they are time consuming to use. For example, many of the devices utilize metal or glass gobos etched with an image and inserted into the accessory slot. Such gobos are expensive and require specialized equipment and time to manufacture. On the other hand, when flexible film or plastic materials are used, they typically have a very short life span due to degradation from the heat of the lamp. 
     Some manufacturers have attempted to overcome the problems associated with projecting low-cost transparency images for extended periods of time by providing devices that utilize certain combinations of fans and filters to achieve the cooling required to prevent degradation of the image transparency. However, these devices are typically expensive stand-alone devices that were developed only for this one limited purpose and cannot be used with commercially available luminaires, for example, as a “drop-in” accessory. 
     It is therefore a broad object of this invention to overcome the above-mentioned shortcomings of known luminaire accessories and image projectors, and a more particular object of this invention to provide an improved image projector device that is easily used in combination with commercially available luminaires, and provides for easily fabricated, low cost, high-resolution images that can be used many times despite the heat generated in such luminaires that would otherwise prevent such use. 
     SUMMARY OF INVENTION 
     In the present invention, these objects, as well as others, are achieved by providing an image projector that drops into the accessory slot of a luminaire and comprises a cooling fan, infrared and ultraviolet light filter means, and an inexpensive and removable “slide assembly” comprising a plastic image slide, a protective film slide and at least one mounting plate. The cooling fan is combined with layered, reflective filters to create a protected environment for the plastic image slide to survive the extreme heat at the gate of today&#39;s efficient luminaires. The plastic image slide is created on a high temperature plastic base using conventional computer printing technologies, thereby allowing virtually any image to be printed on the slide. The image projector of this invention can thus project high quality images in full color and photographic detail previously available only through advanced projection systems or from expensive glass gobos. 
     Other objects, features and advantages of the present invention will be apparent when the detailed description of the preferred embodiments of the invention are considered in conjunction with the drawings which should be construed in an illustrative and not limiting sense as follows: 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of an image projector including a holder assembly and a slide assembly in accordance with a preferred embodiment of the invention. 
     FIG. 2 is an exploded view of the slide assembly shown in FIG.  1 . 
     FIG. 3 is a perspective view of the holder assembly shown in FIG. 1 (with its cover and slide assembly removed). 
     FIG. 4 is a cross-sectional view of the image projector shown in FIG. 1, taken along the line  4 — 4 . 
     FIG. 5 is a cross-sectional view of the image projector shown in FIG. 1, taken along the line  5 — 5 . 
     FIG. 6 is a cross-sectional view of the image projector shown in FIG. 1, taken along the line  6 — 6 . 
     FIG. 7 is a perspective view of an image projector including a holder assembly and a slide assembly in accordance with another preferred embodiment of the invention. 
     FIG. 8 is a cross-sectional view of the image projector shown in FIG. 7, taken along the line  8 — 8 . 
     FIG. 9 is an exploded view of the slide assembly shown in FIG.  7 . 
     FIG. 10 is a perspective view of the image projector shown in FIG. 7 with the slide assembly removed from the holder assembly. 
     FIG. 11 is a side view of a representative luminaire and placement of an image projector in accordance with this invention prior to installation. 
     FIG. 12 is a side view of an image projection in accordance with this invention installed in a representative luminaire. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An image projector  10  for projecting low cost, high-resolution images from a luminaire while simultaneously protecting the images from the heat of the luminaire&#39;s lamp is shown in FIGS. 1-10; FIGS. 1-6 showing a first embodiment and FIGS. 7-10 showing a second embodiment. FIGS. 11 and 12, respectively, show the image projector  10  before and after placement in the accessory slot of a typical commercially available luminaire  12 . 
     An image projector fabricated in accordance with this invention provides a compact and inexpensive means for projecting high-resolution images printed on plastic slides with commercially available luminaires by prolonging the life of image slides. The image slides may be made from any commercially available plastic transparency film (for example, made from polyester) having a computer-generated image printed thereon using any conventional printing technique, for example, ink-jet or laser printing may be used, but ink-jet printing provides longer lasting images. Preferably, the image slides are made from high temperature resistant plastic, but this is not required. The image slides can thus be easily produced and are readily interchangeable into the image projector. 
     In general, the image projector protects the image slides using the combination of a cooling fan and at least one ultraviolet (“UV”) and/or infrared (“IR”) filter. Referring to FIGS. 1 and 7, the image projector  10  comprises two main sections—a removable slide assembly  14 A (FIG.  1 ),  14 B (FIG. 7) for holding an image slide and a protective film slide; and a cooling assembly  16  for holding the slide assembly  14 A,  14 B and cooling the image slide therein. 
     The cooling assembly  16  comprises an enclosure  18  for a cooling fan  20  (see FIG. 3) and a base plate  22  arranged with a unique combination of alignment tabs that allow the base plate to fit into the accessory slot of many different commercially available luminaires without any modification to the luminaire; in particular, the pattern of tabs and ears  24  along the sides of the base plate, as well as the curved shape at the bottom  26  of the base plate. The length and width of the base plate  22 , as well as the dimensions and pattern of tabs and ears  24 , may be changed to accommodate other types of luminaires. 
     Any type of fan capable of blowing air through and out of the fan enclosure may be used in this invention. It has been found that a turbine fan, which blows air in line with the fan&#39;s blades is preferred. For example, a turbine fan marketed under the tradename “Cyclone Blower” by Antec, Inc. (Freemont, Calif.) may be used. 
     The base plate  22  and fan enclosure  18  are arranged substantially perpendicular to one another and may be fabricated from any type of strong metal or metal alloy capable of withstanding temperatures of at least 200° C., preferably steel. The fan enclosure comprises a removable cover  28  (as shown in FIG. 3) having a horizontal top section  30 , a vertical middle section  32  and a horizontal bottom section  34  that extends away from the middle section in a direction opposite that of the top section and extends toward the end of the base plate  26 . The removable cover may be secured to the fan enclosure by any known means. For example, screws  38  may be screwed through the middle section of the fan enclosure cover and into anchors  40  extending from an interior surface of the fan enclosure. The cover  28  may be made from any metal or metal alloy, but preferably comprises aluminum. 
     The top section  30  of the fan enclosure comprises a vent system comprising a series of slots  36  that allows cool, fresh air to flow into the fan enclosure when the fan  20  is turned ON. The vent system may be modified to include any type of aperture that permits air to flow through the top section and into the fan enclosure. The top section also comprises an aperture  40  for the fan&#39;s power cord to pass through. Alternatively, an aperture for the power cord may be placed in the sides or back of the fan enclosure. 
     To conserve energy, the fan&#39;s power cord may be plugged into the same electrical circuit (e.g., a dimmer circuit) as the luminaire to allow for simultaneous control of light output and flow of cooling air. This is advantageous because as the luminaire&#39;s light output is reduced, the heat created by the lamp is reduced and thus requires less cooling air. Therefore, as the luminaire is dimmed or brightened to adjust its light output, the fan in the image projector and subsequent airflow, will be similarly adjusted. 
     The bottom section  34  of the fan enclosure cover forms a plenum having a top and two sides, and when the cover is attached to the fan enclosure, the plenum forms an open space along the base plate  22  that directs the flow of air across the base plate. When the fan is turned ON, the fan draws fresh, cool air into the fan enclosure through the vent system  36 , and forces the cool air out of the bottom portion of the fan  20 , through the plenum, down along the base plate  22  (as indicated by the arrows in FIGS. 1,  5 ,  7  and  10 ) and through the slide assembly  14 A,  14 B, which is removably attached to the base plate. An air guard  41  is installed in the fan enclosure near the plenum to direct the flow of cool air out of the plenum and to prevent cool air from flowing back into the fan enclosure (see FIGS.  3  and  5 ). The air guard  41  is a generally U-shaped structure that extends substantially the entire width of the fan enclosure and substantially from the inner surface of the fan enclosure&#39;s middle section  32  to the outer surface of the fan  20 . The air guard  41  may be attached to the interior surface of the fan enclosure cover&#39;s middle section  32 , for example, by screws  42 , or it may be attached to the interior sides of the fan enclosure. 
     The base plate  22  extends substantially perpendicular to the fan enclosure and comprises a central aperture  44  that allows light from the luminaire&#39;s lamp to pass through and means for receiving the slide assembly. The slide assembly  12  may be removably attached to the base plate  16  with screws or other commercially available fastening devices, but preferably has key slots that fit over keyway buttons  46  that extend up from the base plate  22  for locking (as shown in FIG.  1 ). The keyway buttons  46  are arranged on the base plate in an asymetrical nature such that the slide assembly  12  may be installed in only one way. This prevents a user from incorrectly installing the slide assembly, which may cause damage to the image slide. 
     Referring to FIG. 3, a glass reflector or filter  50  is mounted to the base plate  22  over the aperture  44  with at least two brackets  52  (four are shown) either on the top surface of the bottom plate  22  or on the bottom surface (as shown). The glass filter  50  may also be mounted with a screw and washer combination (the washer acting as a bracket), heat-sensitive adhesives or other known means. Further, the glass filter may be mounted in a metal ring prior to installation to prevent breakage when the being installed onto the base plate. 
     The glass filter  50  blocks both IR and UV energy from the luminaire&#39;s lamp. A preferred filter of this type also blocks the portion of visible light from 400-420 nanometers, and reduces overall transmission of light by 20%. A preferred filter for this invention was derived from the 38,000 IR/UV Filter commercially available from Rosco Laboratories, Inc., Stamford, Conn., which was modified to block the portion of visible light from 400-422 nanometers and to reduce light transmission by 20%. The glass filter  50  thus substantially reduces the amount of heat that is transmitted through the filter to the slide assembly. 
     Further protection from the heat of the luminaire&#39;s lamp is provided by the construction of the slide assemblies  14 A (FIG.  2 ),  14 B (FIG.  14 B). Both slide assemblies generally comprise an IR reflecting protective film layer  54  and an image slide layer  56  surrounded on both sides by top  58  and bottom  60  mounting plates. In both embodiments, the top and bottom mounting plates have a central aperture  61  that allows light from the luminaire&#39;s lamp to pass through the slide assembly. The image  57  on the image slide  56  should be positioned approximately in the center of the central aperture  61 . 
     In the first embodiment (FIG.  2 ), the slide assembly  14 A comprises top  58  and bottom  60  mounting plates, preferably made of plastic, one (the bottom as shown) having a series of protruding snaps  62  on its interior surface and the other (the top as shown) having a corresponding series of holes  64  in its interior surface, such that the snaps  62  can be inserted into the holes  64  and snapped together to connect the top and bottom mounting plates together. The snaps  62  and holes  64  are placed in raised areas  68  along the two sides of top and bottom plates, leaving a recessed area  70  between the two raised areas. Thus, when the top and bottom plates are connected together, a slot or air gap  66  is formed between the plates to permit air from the cooling assembly&#39;s plenum to flow through and around both the image and protective film layers (see FIG.  1 ). The protective film layer  54  and the image slide layer  56  are inserted between the top and bottom mounting plates prior to connection and are secured in the slide assembly by either the force of the connection between the top and bottom plates or, preferably, the layers are adhered to the top and bottom plates respectively in the recessed areas  70  (as shown in FIG.  1 ). Alternatively, the layers may be adhered to each other using a heat resistant double-sided adhesive tape or the like. 
     In a second embodiment (FIG.  9 ), the image slide layer  56  and protective film layer  54  are sandwiched between top  58  and bottom  60  mounting plates of any material, for example, plastic or aluminum, each layer being separated by spacers  71  (for example, nylon washers) to allow air from the cooling assembly&#39;s plenum to flow through the slide assembly  14 B. The spacers  71  are used to separate each layer of slide assembly  14 B to allow cooling air from the fan  20  to flow across both surfaces of the protective film layer  54  and the image slide layer  56 . The spacers  71  may be metal, nylon or other type of material and are placed between the layers as follows: (1) between the bottom mounting plate  60  and the protective film layer  54 ; (2) between the protective film layer  54  and the image slide layer  56 ; and (3) between the image slide layer  56  and the top mounting plate  58 . Alternatively, the spacers between the bottom mounting plate  60  and the protective film layer  54 , and the image slide layer  56  and the top mounting plate  58 , may be removed if the film layer  54  is adhered to the bottom mounting plate and the image slide layer  56  is adhered to the top mounting plate  58 . Each layer may be adhered to each other with heat-resistant double-sided adhesive tape or the like, or the spacers could be made from an adhesive material, or the slide assembly may be held together by a pin system similar to the first embodiment. 
     In both embodiments, the bottom mounting plates  60  have three key apertures  72  shaped to be locked onto the three keyway buttons  46  on the base plate  22  (see FIGS. 1,  3  and  10 ). The top mounting plate  58  may also have three similarly shaped key apertures  48  for locking onto the keyway buttons  46 . The number of keyway buttons may be modified, provided the slide assembly is sufficiently secured to the base plate to prevent rotation. It is also preferred that the number and arrangement of keyway buttons be asymmetrical to prevent a user from improperly installing the slide assembly onto the base plate. 
     In the second embodiment, the bottom mounting plate  60  may also have a series of smaller mounting holes  74  along at least two sides thereof (aligned with the spacers  71 ) that permit mounting posts  76  to hold the film layer  54 , image slide layer  56  and spacers  71  in place. 
     The protective film layer  54  is a polyester film coated with a metalized IR reflective surface. This additional layer of IR reflector protects the image from any damaging IR energy that is not reflected by the glass filter  50  mounted on the base plate  22 . 
     Once the slide assembly  14 A,  14 B is assembled with an image slide layer  56 , it can be easily attached to and removed from the base plate  22  (as shown in FIGS. 3 and 10) The assembled unit or image projector  10  (shown in FIGS. 1 and 7) may then be inserted into a luminaire  12  as shown in FIGS. 11 and 12, with base plate  22  and slide assembly  14 A,  14 B sliding into the luminaire&#39;s accessory slot  78 , and the cooling assembly  16  sitting above the front portion  80  of the luminaire&#39;s body. The image projector  10  is installed such that the base plate  22  is closer than slide assembly  14  to the luminaire&#39;s lamp (situated at the rear  82  of the luminaire), and the cooling assembly  16  extends toward the front of the luminaire. Thus, the luminaire&#39;s lamp shines first through the glass filter  50  on the base plate  16  and then through protective film layer  54  and then through the image slide  56  to project the image in the slide assembly. 
     Together, the cooling assembly  16  and the slide assembly  14  protect the slide image  56  from heat and damaging light, allowing otherwise fragile plastic images to survive for substantially longer periods than they do under normal use (up to about fifty hours of use). More particularly, the flow of air from the fan provides cooling air circulation through and around the slide assembly  14 , which in combination with the layered IR and UV filtering in the glass filter  50  and the film layer  54  protects the slide image from high operating temperatures. Thus, images can be displayed and used on regular transparency film without serious heat damage even after extended time periods or multiple uses. 
     For example, when tested on luminaires of 600 watts or less, with light output at 100%, image slides in the image projector of this invention lasted for 30 to 50 continuous hours with no degradation of the image. When the luminaire was dimmed to approximately 50% light output, the life span is virtually infinite. Therefore, since a theatrical application typically uses an image slide for less than one hour per performance, a single image slide may be used for 30 performances or more, providing a substantial cost savings to the production. 
     Although the invention has been described with reference to a preferred embodiment, it will be appreciated by one of ordinary skill in the art that numerous modifications are possible in light of the above disclosure. For example, although it is preferred that the image projector use the same electrical circuit as the luminaire, it is not required. Further, the size of the aperture could vary and still be effective. The size of the slide assembly, so long as it covered the aperture could also vary. The unique shape of the base plate allows the single device to fit into multiple luminaires, however, one could modify the base plate to fit into a specific luminaire. Fans of various styles could be used, though a turbine fan proved most efficient. Further, the unit is equally effective if both filters are installed on the base plate, as opposed to one being in the slide assembly, as long as equivalent airflow between the filters and image is achieved. A further advantage of the invention is that the image projector can also protect color filter materials, such as gel. Using gel in place of the image layer achieves a significantly extended life span over color filter used in the traditional color frame location. All such variations and modifications are intended to be within the scope and spirit of the invention.