Ceiling lighting fixture with UV-C air sterilization

Abstract

An UV-C air sterilizer with an optional visible light provides effective air sterilization through the use of a relatively low intensity UV-C radiation field external of the fixture and the continuous circulation of a mixture of treated and untreated air. Methods are also disclosed.

1 . An in-room air sterilizer for a room having a ceiling not less than about eight feet from the floor, said sterilizer being adapted for connection through the ceiling to a source of electrical energy, said air sterilizer comprising:
 a housing;   an UV-C radiation baffle below said housing;   a source of UV-C radiation located between said housing and said baffle for creating a radiation field extending laterally into the room around said housing; and   an air mover including an impeller generally at the same vertical level as said source and an electric motor driving said impeller, said air mover drawing air upwardly into said impeller and discharging air generally horizontally from said impeller into the radiation field,   the location of said source and said housing defining the upper limit of the angle of direct radiation into the field and the maximum angle at which direct radiation is reflected into the field,   the location of said source and said baffle defining the lower limit of the angle of direct radiation into the field, and   the intensity of the radiation field inclusive of direct and reflected radiation being less than a predetermined threshold at a predetermined height above the floor.   
   
   
       2 . The sterilizer of  claim 1  where predetermined radiation threshold is about 0.3/γj/cm 2  within about five feet of the room floor. 
   
   
       3 . The sterilizer of  claim 1  including a control circuit within said housing. 
   
   
       4 . The sterilizer of  claim 3  wherein said control circuit includes a receiver by which the operation of the fixture may be remotely controlled. 
   
   
       5 . The sterilizer of  claim 3  wherein said control circuit includes a motion detector to increase the intensity of the UV-C radiation when there are no people in the lower part of the room. 
   
   
       6 . The sterilizer of  claim 1  where the maximum upper angle is about 35 degrees. 
   
   
       7 . The sterilizer of  claim 1  where the minimum lower angle is approximately 0 degrees. 
   
   
       8 . The sterilizer of  claim 1  wherein the vertical distance between housing and baffle is about 3 inches. 
   
   
       9 . The sterilizer of  claim 1  wherein the vertical distance between said housing and said baffle is adjustable. 
   
   
       10 . The sterilizer of  claim 9  wherein said air mover, UV-C sources and baffle form a single module. 
   
   
       11 . The sterilizer of  claim 1  where total fixture depth is less than about 15 inches. 
   
   
       12 . The sterilizer of  claim 11  where total fixture depth is less than about 12 inches. 
   
   
       13 . The sterilizer of  claim 1  including a source of visible light source below said baffle. 
   
   
       14 . The sterilizer of  claim 13  wherein said source of visible light is a circular fluorescent bulb. 
   
   
       15 . The sterilizer of  claim 14  including a glare reducing cover for said source of visible light. 
   
   
       16 . The sterilizer of  claim 15  wherein said UV-C and said visible light sources are substantially vertically aligned. 
   
   
       17 . The sterilizer of  claim 1  wherein said UV-C source is a pair of semi-circular bulbs. 
   
   
       18 . The sterilizer of  claim 1  wherein said UV-C sources are accessible without removing said baffle from the fixture. 
   
   
       19 . The sterilizer of  claim 1  wherein said impeller is reflective of at least 50% of the UV-C radiation incident thereon from said UV-C source. 
   
   
       20 . The sterilizer of  claim 1  wherein said source of visible light is above the lowest part of said air intake. 
   
   
       21 . The sterilizer of  claim 1  wherein said visible source is not in the air intake path of said impeller. 
   
   
       22 . The sterilizer of  claim 1  including a filter for said UV-C source to reduce visible light. 
   
   
       23 . The sterilizer of  claim 1  wherein the upper surface of said baffle is UV-C absorptive. 
   
   
       24 . The sterilizer of  claim 1  wherein the outer surface of said housing is UV-C absorptive. 
   
   
       25 . An in-room air sterilizer for a room having a ceiling not less than about eight feet from the floor, said sterilizer being adapted for connection through the ceiling to a source of electrical energy, said air sterilizer comprising:
 a housing;   an UV-C radiation baffle below said housing a distance not greater than about six inches;   a source of UV-C radiation located between said housing and said baffle for creating a radiation field extending laterally into the room around said housing; and   an air mover including an impeller generally at the same vertical level as said source and an electric motor driving said impeller, said air mover drawing air upwardly into said impeller and discharging air generally horizontally from said impeller into the radiation, the total depth of said sterilizer being less than about 15 inches.   
   
   
       26 . A ceiling fixture for sterilizing air within a room having a lower portion below about five feet, said fixture comprising:
 a source providing an UV-C radiation field in the room external of the fixture, with the field   (a) including essentially no direct radiation in the lower portion of the room;   (b) including essentially no ceiling reflected radiation in the lower portion of the room where the angle of reflection from the ceiling is greater than about 35 degrees, and   (c) the intensity of UV-C radiation in the lower portion of the room not exceeding about 0.3/γj/cm 2 ; and   an air mover for moving air through the UV-C field in a generally horizontal direction to effect mixing of room air and re-circulation of mixed room air through the fixture.   
   
   
       27 . A ceiling fixture for sterilizing air within a room comprising:
 a UV-C source;   a single opening baffle for said source for limiting direct radiation from said source into said room to an angle between the horizontal and about 35 degrees; and   an air mover for drawing air upwardly into said fixture and for discharging air generally horizontally from said fixture into the radiation field.   
   
   
       28 . A method of sterilizing the air in a room comprising the steps of:
 (a) positioning in a room above eye level a fixture containing an air mover and a source of UV-C radiation;   (b) using the source within the fixture to provide a field of UV-C radiation external of the fixture sufficient to kill germs in the air passing through the field without exceeding a predetermined radiation intensity below eye level; and   (c) using the air mover within the fixture to create air currents that move air through the field above eye level   to thereby reduce the germs in the room without endangering occupants in room.