Abstract:
A heat controlled ultraviolet light apparatus includes a source of ultraviolet light, a cover, and a heating or cooling element that heats/cools the space or gap between the ultraviolet light source and the cover. Accordingly, the ultraviolet light source may be maintained at an optimal temperature thereby maximizing the efficiency of the ultraviolet light source in producing ultraviolet radiation. The apparatus may further include a temperature sensor and a control circuit to automatically control production of heat/cooling by the element based upon the ambient temperatures experienced by the ultraviolet light source during use. Methods are also provided for sanitizing heating and cooling coils of various devices such as an HVAC system, and cooling systems such as a refrigeration unit and an evaporative cooler.

Description:
TECHNICAL FIELD 
   The present invention relates generally to methods and apparatuses for disinfecting objects utilizing an ultraviolet light source, and more particularly, to an ultraviolet light source that is maintained at a desired temperature range by heating or cooling, as necessary, thereby maximizing the efficiency of the ultraviolet light source in producing ultraviolet rays. 
   BACKGROUND OF THE INVENTION 
   An ultraviolet light source is a well known means for sanitizing and disinfecting many targeted objects to include fluids. When administered at the desired frequencies, durations, and intensities, ultraviolet (UV) light is able to kill a wide array of micro-organisms that include, but not limited to, bacteria, viruses, spores, algae and protozoa, without having to chemically treat the object to be disinfected. One type of common UV bulb includes a quartz or glass casing that holds a vaporizable material, such as mercury, and also holds a stabilizing gas. The stabilizing gas may be one of the noble gases such as argon, neon, or xenon. An electrode positioned within the area sealed by the casing excites the stabilizing gas and vaporizable material. Ultraviolet light is emitted from a plasma field which is generated with the excited vaporizable material. 
   The ability of a UV light source to disinfect an object is primarily a function of exposure time and intensity of the exposure. For purposes of disinfecting or sanitizing a targeted object, it is therefore advantageous to use a source of UV light that consumes a minimum amount of power, yet produces an intense UV light output. 
   One of the more common types of UV light sources that are used as sanitizing/disinfecting agents are low pressure mercury lamps. Low pressure mercury lamps are generally cost effective in that their power requirements are low as compared to other types of UV light sources, yet low pressure mercury lamps also have a comparatively high UV output. One disadvantage with mercury lamps is that they are unable to adequately function in temperatures that fall outside optimal operating temperatures of the mercury lamps. UV light sources have been proven to be effective in sanitizing and disinfecting freezers/coolers used in the food handling industry; however, degradation in the performance of the UV light sources is experienced due to the colder temperatures that fall well below the optimal operating temperatures of the UV light sources. Low pressure mercury lamps are most efficient in producing ultraviolet light when the lamps are maintained at a temperature between about 80° to 90° F. 
   Therefore, it is apparent that a cost effective means is needed for providing UV disinfection/sanitization, particularly in those industries where ambient temperatures of objects to be sanitized are well below the optimal operating temperature ranges of a UV light source. 
   Also, there are circumstances when a UV light source may be subjected to temperatures that exceed optimal operating temperatures; thus, there is also a need to provide UV disinfection/sterilization in these conditions. 
   U.S. Patent Application Publication No. U.S. 2003/0001112 discloses a hermetically sealed ultraviolet light source in the form of an ultraviolet light bulb/lamp and a protective sleeve that surrounds the ultraviolet bulb. The sleeve helps to insulate the ultraviolet bulb which therefore helps to keep the bulb&#39;s plasma thermally stable. 
   U.S. Patent Application Publication No. 2003/00038247 discloses a watertight irradiation apparatus utilizing a microwave excited ultraviolet radiation generator that includes an electrodeless lamp. The UV radiation generator is enclosed within a watertight housing having an irradiation window allowing the UV rays to pass from the lamp to a target area. 
   While the prior art may suggest use of a covering to protect an otherwise exposed ultraviolet light source, a need still exists for providing an ultraviolet light source that may be selectively and controllably heated or cooled to optimize the output of the ultraviolet light source, regardless of the temperature at which the source is exposed to during use. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, a heat controlled ultraviolet light apparatus is provided. The basic components of the apparatus include an ultraviolet light source, an ultraviolet transmissive cover placed over the light source, and a heating or cooling element placed within the cover to heat or cool the light source. The apparatus is placed at a desired distance from the object(s) to be disinfected/sanitized, and the ultraviolet light source is energized to deliver a desired amount of radiation in the form of ultraviolet light. The terms “disinfect” and “sanitize” as used herein are interchangeable terms, and collectively mean to free a targeted object from contaminants particularly in the form of living organisms such as the microorganisms mentioned above. 
   More specifically, the apparatus of the present invention includes a heating or cooling element that may be selectively controlled to provide the necessary amount of heating/cooling to maintain the ultraviolet light source at a desired temperature range thereby maximizing the efficiency of the UV light source in producing ultraviolet light. Preferably, the ultraviolet light source of the present invention can be categorized as a “hot UV” lamp, and more particularly, a low pressure mercury lamp that is most efficient in producing ultraviolet light when the lamp is maintained at a temperature between about 80-90° F. A heat sensor, such as a thermocouple or any other type of sensor, may be placed adjacent the ultraviolet light source to measure the temperature at which the light source operates. The heat sensor communicates with a control circuit which energizes the heating element at necessary intervals to maintain the light source within the optimal temperature range when the light source requires heating. For example, as temperature conditions may change, the heat sensor provides periodic inputs to the control circuit. The control circuit reacts accordingly to provide power to the heating element thereby maintaining the UV light source at the desired temperature range. 
   Alternatively, the heat sensor can be in the form of a temperature switch thereby eliminating the need for a separate control circuit, or at least reducing control circuit requirements. 
   If it is necessary to cool the UV light source, a cooling element can be used, such as a Peltier element, or a small cooling coil that may circulate a cooling medium therethrough. As necessary, a control circuit could be used to control the cooling element as well. 
   The cover not only helps to regulate temperature of the UV light source, but also helps to protect the UV light source from damage. The size and shape of the cover can be adapted for the specific use of the apparatus, as well as the type of ultraviolet light source used. The cover is larger than the bulb of the ultraviolet lamp thereby creating an airspace or gap between the cover and the bulb. Preferably, the heating/cooling element is placed in the gap/airspace between the cover and the lamp. A heating/cooling element having a higher output may allow the cover to be larger as the airspace between the cover and bulb would be more easily controlled, while a heating/cooling element with a lower output may require a smaller cover to allow the element to adequately control temperature in the airspace. One important aspect of the present invention is that the cover used be UV transmissive. Known materials which could be used that are UV transmissive include soft glass and quartz. 
   The UV light apparatus of the present invention can be used in even the most harsh environments, such as within an HVAC system, or a refrigeration unit wherein both environments would subject the apparatus to wide variances in temperature to include temperatures well below freezing. 
   With the apparatus of the present invention, disinfection of a targeted object can be accomplished in an energy efficient manner, thus reducing power requirements for the apparatus, as well as avoiding use of multiple apparatuses to achieve desired disinfectionss. Disinfection of the coils in systems such as an HVAC or refrigeration system also provides remedial and preventative maintenance benefits because the coils lose their ability to transfer heat if covered with microorganisms such as mold and algae. Motors and compressors must then work harder to compensate for the diminished coil performance. Thus, disinfection also helps to maintain proper operation of these systems to include saving power used by the systems. 
   Other features and advantages of the invention will become apparent from a review of the detailed description, taken in conjunction with the drawings, wherein like reference numbers refer to similar items throughout the figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the ultraviolet light apparatus of the present invention, to include a schematic of circuitry supporting the apparatus; 
       FIG. 2  is an enlarged vertical section of the apparatus illustrating interior details; 
       FIG. 3  is another perspective view illustrating another embodiment; 
       FIG. 4  is a schematic drawing of the apparatus of the present invention used within an HVAC system; 
       FIG. 5  is another schematic drawing of the apparatus of the present invention used within an evaporative cooler; and 
       FIG. 6  is yet another schematic drawing illustrating the apparatus of the present invention used within a walk-in cooler/freezer. 
   

   DETAILED DESCRIPTION 
   Referring first to  FIG. 1 , the heat controlled ultraviolet light apparatus  10  of the present invention is shown. The apparatus includes a UV transmissive cover  12 , an ultraviolet lamp or bulb  14 , and a heating/cooling element  18  that is placed in the gap or space between the bulb  14  and the cover  12 . The particular type of ultraviolet bulb or lamp  14  shown includes one with a filament  16  which is used to excite a metal such as mercury housed in the lamp. One or more rare gases additionally fill the interior of the bulb so that a plasma field can be created, thus generating both visible and ultraviolet light. Although a particular type of ultraviolet lamp is shown, it shall be understood that the present invention can utilize any type of ultraviolet lamp. The bulb  14  may include an integral bulb base  20 , which is most common in ultraviolet lamp constructions. As required, the bulb base may further include an internal ballast incorporated with base  20 , or an external ballast  30  as shown. 
   Referring to  FIG. 2 , the apparatus of the present invention may further include a foundation or mount  21  which is used to secure the various elements of the apparatus. The mount  21  may be made from plastic, metal, or resin having a central opening therein sized to receive the bulb base  20 . Preferably, the mount  21  is made of potting resin such that the mount  21  can be formed in a molding process to secure the elements of the apparatus. A slot or annular groove  22  can be formed on an upper surface of the mount  21  in order to receive a circumferential flange  24  formed on the cover  12 . The slot  22  can be sized so that the flange  24  of the cover  12  frictionally engage the slot  22  thereby securing the cover  12  to the mount  21 . Alternatively, the open end of the cover  12  may eliminate the flange  24 , and the slot  22  can simply be sized with a width to frictionally engage the end of the cover  12 . By this manner of attachment, the cover  12  can be sealed with respect to the bulb  14 . Those skilled in the art can envision any number of additional ways in which the cover  12  may be secured to the mount  21 . The heating/cooling element  18  has a lower end which is also received in the mount  21 . 
     FIG. 2  further illustrates a temperature sensor  26  which may be mounted directly to the bulb  14 , or may be secured to the mount  21  and positioned in the gap between the element  18  and the bulb  14 . The sensor  26  includes a transmission line  27  which communicates with a control circuit  28 . Sensor  26  acts as a temperature input to the control circuit. The element  18  also electrically connects with the control circuit  28  as by electrical line  29 . The control circuit  28  would periodically energize/control the element  18  depending upon temperature inputs from sensor  26  to maintain the bulb  14  at a desired temperature range. A common power supply  32  can be used to power the ultraviolet lamp  14 , as well as the control circuit  28  and heating element  18 . 
   A preferred heating element is one made of a quartz material with a nichrome heating element etched on the quartz medium. The shape of the heating element is shown as being rectangular; however, any shape can be used, but preferably one which is of simple shape thereby minimizing manufacturing requirements. The heating element is also preferably sized to extend along the length of the lamp  14  thereby assuring a more uniform heating of the lamp. 
   A preferred cooling element may include a Peltier element, a small cooling coil that circulates a cooling medium therethrough, or any other acceptable cooling element that can fit in the gap between the lamp and the cover. 
   Referring now to  FIG. 3 , an alternate embodiment is shown. While  FIG. 2  represents a cover  12  that may be sealed with respect to the lamp  14 ,  FIG. 3  shows an arrangement wherein one portion of the lamp  14  is covered by the cover  12 , yet other portions of the lamp  14  remain exposed. With the embodiment of  FIG. 3  as used in some applications, it may be unnecessary to completely seal the cover with respect to the ultraviolet lamp. Thus, adequate heating/cooling of the lamp can take place if only a portion of the lamp remains covered during operation. For example, the apparatus of  FIG. 3  could be used within a cooling unit that did not experience continued freezing temperatures, or the apparatus of  FIG. 3  could be used to disinfect an object which might only occasionally be subject to cool temperatures. Structurally, the only modifications to the apparatus of  FIG. 3  in comparison to the apparatus shown in  FIG. 2  is that the cover does not completely cover the bulb and a plurality of supports  34  are used to attach the open end of the cover  12  to the mount  21 . 
   In addition to providing clear open spaces around the lamp  14  as shown in  FIG. 3 , another method in which to provide a non-sealed cover would be to simply form a plurality of openings within the cover  12 . Thus, a friction type engagement could still be used to attach the cover  12  to the mount  21 , but the cover would not completely seal the lamp  14  because of the plurality of openings. 
   One acceptable material for the cover is a number  210  clear polished quartz of approximately 1/16th of an inch thickness. The cover is intended to be removable to facilitate periodic cleaning and replacement of not only the cover itself, but also of the heating element and/or UV lamp. Thus, in lieu of permanently affixing the base  20  of the lamp within the mount  21 , a threaded attachment cold be used between the base  20  and the mount  21  thereby easing removal and replacement of the lamp  14 . 
     FIG. 4  is a schematic diagram illustrating the apparatus  10  of the present invention used within a standard HVAC system  40 . As shown, the HVAC system  40  may include a central duct  42 , a fan  44 , a return air duct  46 , and an outlet duct  52 . One or more filter elements  48  may be placed within the duct group as desired. Additionally, heating and/or cooling coils may traverse the central duct  42  thereby allowing heating or cooling of the air that passes through the HVAC system. The apparatus  10  is placed in close proximity to the cooling coils  50  to thereby sanitize/disinfect the cooling coils. As shown, the apparatus  10  can simply be mounted to the central duct  42  with the apparatus  10  extending a desired length into the duct space. Depending upon the size of the coils, the type and size of the ultraviolet lamp used, one or more apparatuses  10  can be used to disinfect sides of the cooling coils  50 . Of course, the apparatus  10  can be placed at other locations with the HVAC system to provide sanitization benefits. As understood in the art, use of an ultraviolet light source also is effective in sanitizing the airstream itself. 
     FIG. 5  illustrates use of the apparatus  10  within an evaporative cooling device  60 . The evaporative cooling device  60  is generally characterized as including a housing  61 , cooler batting  62  mounted at an inlet of the cooler, a liquid line  64  that provides a controlled drip of liquid over the batting, and a pump  65  to deliver the liquid. One or more fans  66  can be used to pull air through the cooler. Alternately, one or more fans  66  could be positioned upstream of the batting to push air through the device. The apparatus  10  is mounted in close proximity to the cooler batting  62  thereby providing disinfection of the same. One or more apparatuses  10  can be used and spaced from one another along the length of the batting  62  in order to achieve desired treatment. 
     FIG. 6  illustrates yet another example of use of the apparatus  10 .  FIG. 6  illustrates a common walk-in cooler or freezer. Accordingly, the cooler/freezer  70  may include an access door  72 , which provides access to the temperature controlled space that may hold food or other perishables for storage. A common or generic refrigeration unit would include an inlet fan  76  for delivering cooled air, an exhaust fan  74  for removing air from the temperature controlled space, and a housing  78  to contain other elements of the refrigeration unit such as a compressor, expansion valve, etc. In order to optimize efficiency of the refrigeration unit, it is most common for the refrigeration unit to have its condenser coils  80  positioned within the temperature controlled space. Because heat transfer takes place from the condenser coils, the condenser coils themselves may be a source of microbial growth because they would normally be at a temperature higher than the surrounding air. Additionally, condensation may develop on the condenser coils  80 , thereby necessitating the use of a drip pan  82  to catch the dripping liquid. The liquid within the drip pan  82  may also serve as a source for undesirable microbial growth. The apparatus  10  of the present invention would be mounted in close proximity to the coils  80 . As necessary, more than one apparatus  10  may be used to optimally disinfect the coils  80  as well as to disinfect the drip pan  82  and the liquid that may be collected within the drip pan. 
   In all of the uses described in  FIGS. 4 ,  5  and  6 , the apparatus  10  of the present invention may be subject to temperatures well below the optimal temperature range of the ultraviolet lamp. Accordingly, the integral heating element allows selective and controllable heating of the UV lamp to thereby maximize the delivery of ultraviolet radiation to the targeted objects to be disinfected. Although low pressure mercury lamps may have an optimal operating temperature range between about 80-90 degrees F, the apparatus of the present invention is well suited to provide necessary heat for lamps that may operate at many other temperature ranges. 
   In addition to the apparatus of the present invention, the present invention also includes methods of sanitizing various objects to include coils of a refrigeration unit, and coils of an HVAC system/evaporative cooling device. Although these three specific methods have been described and claimed herein, the apparatus of the present invention can be used in many other applications as well. 
   The apparatus and methods of the present invention have been described with respect to preferred embodiments; however, it shall be understood that various other changes and modifications can be made within the spirit and scope of the present invention as claimed.