Abstract:
An ultraviolet radiation sanitation system which is portable and which operates on battery power to generate UVC radiation to decontaminate bathrooms on aircraft and other small rooms or enclosed areas. The system includes one or more low pressure high output mercury or amalgam UVC lamps mounted on a housing which contains a battery powered power supply, lamp ballasts and control circuitry. The housing also includes a control panel having controls and indicators for system operation. A motion detector is provided on the housing to shut off the system in the presence of detected motion which would occur by the presence of a person. The housing is mounted on a tripod or other stand to support the system on an aircraft bathroom floor or other location in which the system is to be deployed.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0001]    N/A 
       BACKGROUND OF THE INVENTION 
       [0002]    It is known that pathogens can be present on surfaces which are not regularly cleaned. This is especially true in bathrooms used by many people as in bathrooms on aircraft. It is also known that UVC radiation is effective in killing or deactivating pathogens in air, water and exposed surfaces. A system for providing UVC radiation to kill pathogens in the air and on radiated surfaces in a room is shown in U.S. Pat. No. 8,791,441 of the same inventor as the present invention. 
         [0003]    It would be useful to have an effective and convenient system for effective decontamination of pathogens in aircraft bathrooms and other small rooms or spaces. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The present invention provides an ultraviolet radiation sanitation system which is portable and which operates on battery power to generate UVC radiation to decontaminate bathrooms on aircraft and other small rooms or enclosed areas. The system includes one or more low pressure high output mercury or amalgam UVC lamps mounted on a housing which contains a battery powered power supply, lamp ballasts and control circuitry. The housing also includes a control panel having controls and indicators for system operation. One or more motion detectors are provided on the housing to shut off the system in the presence of detected motion which would occur by the presence of a person. The UVC lamps are of U shape having connectors on one end that can be plugged into electrical sockets on the housing and which are easily plugged in and out for replacement. Each lamp is covered by a protective sleeve to avoid shattering of the lamp glass in the event of breakage. FEP (Teflon) is preferred because it is UVC transmissive with little attenuation and can easily withstand the operating temperature of the lamps. UVC radiation is provided at a prime wavelength of 253.7 nm (referred to as 254 nm) and sufficient radiation can be provided by the system to decontaminate pathogens including  Clostridium difficile  in a typical aircraft bathroom in about 3 minutes. The on time of the lamps is so short that self-heating of the UVC lamps has no effect on performance of the system. The housing is mounted on a tripod or other stand to support the system on an aircraft bathroom floor or other location in which the system is to be deployed. The system may be operated by a remote control. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0005]    The invention will be more fully understood from the following detailed description in conjunction with the drawings in which: 
           [0006]      FIG. 1 a    is a pictorial view of one embodiment of a system in accordance with the invention; 
           [0007]      FIG. 1 b    is an elevation view of the embodiment of  FIG. 1   a;    
           [0008]      FIG. 2  is a block diagram of a system in accordance with the invention; and 
           [0009]      FIG. 3  is a schematic of circuitry of the system in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    A UVC sanitation system in accordance with the invention is shown in one embodiment in  FIGS. 1 a  and 1 b   . A housing  10  supports one or more UVC lamps  12  in vertical orientation. Two lamps are illustrated in the embodiment of  FIG. 1 . The lamps are in the form of U shaped tubes which are pluggable at one end into associated sockets  14  mounted to the top wall of housing  10 . The lamps are typically low pressure high output mercury or amalgam UVC generating lamps such as Light Sources, Model LTC55W/2G11/FEP. The lamps are typically about 20 inches in length. Preferably each lamp is covered by a protective sleeve to avoid shattering of the lamp quartz glass in the event of breakage. FEP (Teflon) is preferred because it is UV transmissive with little attenuation and can easily withstand the operating temperature of the lamps. The housing  10  can be made of any suitable material, typically aluminum. 
         [0011]    The housing contains one or more lamp ballasts, control circuitry and one or more batteries for powering the system. The ballasts are electronic ballasts and each lamp may be driven by one ballast or a single ballast may drive multiple lamps depending upon the particular lamps and ballasts employed. Battery power is typically 28 volts DC provided by the one or more batteries. The battery or batteries are typically rechargeable and may be mounted inside housing  10 , in which case the housing can include a door or panel  11  which can be opened for access to a battery compartment for removal and replacement of the battery. In another embodiment the one or more batteries can be mounted externally to one or more sides of housing  10 . 
         [0012]    The system is controlled by a microprocessor based controller typically contained on a control board disposed within housing  10 . A control panel  16  is provided on housing  10  and includes a display  18  such as a two digit alpha, numeric or alpha numeric digital display to indicate countdown of remaining time during a decontamination cycle and to indicate system messages such as error conditions. An audio annunciator  20  such as a Sonalert is provided to audibly indicate that an operating cycle has ended. The annunciator can also provide distinguishable sounds to denote one or more error conditions. A start or control switch  22  is provided to activate the system. The control switch can be of the illuminated type which illuminates when actuated to start a decontamination cycle. A USB port  32  is also coupled to the controller and enables the microprocessor to be programmed or reprogrammed via an external computer such as a PC. 
         [0013]    The system can be operated remotely via a remote control  34  which communicates with the controller. The remote control typically contains the same controls and indicators as on the control panel  16 . In an alternative embodiment the system may be operated only via a remote control, in which case no control panel would be provided on the housing. The remote communication between the remote control  34  and the controller can be wireless via radio, ultrasonic or optical signal as per se is known in the art. A wired remote control can alternatively be used. 
         [0014]    The system in the illustrated embodiment including batteries weighs about ten pounds. In the illustrated embodiment the two U shaped lamps are mounted parallel to each other. An enclosure in the form of a protective metal or plastic grid or cage  13  is disposed over the pair of lamps for mechanical protection of the lamps. The grid is sufficiently open to not significantly shield radiation from the lamps. The protective grid can be retained in place on the housing by any convenient means such as a support post or fasteners at the bottom of the grid. Alternatively to an open grid structure the enclosure can be a solid cover of UVC transmissive material. 
         [0015]    The housing is supported on a stand  30  such as a tripod stand. The stand may be collapsible for ease of transport and set up of the system in confined spaces such as an aircraft bathroom. The stand may also be adjustable in height to position the lamp for efficient radiation in the room. 
         [0016]    A motion detector  24  is provided on one or more sidewalls of housing  10  to provide a signal to the system controller in the event that motion is detected such as would occur by a person moving into proximity with the system. If the system is activated when a person is present, the system, in response to a signal from one or more of the motion detectors, will shut down to prevent the person being exposed to UVC radiation. The motion sensors can be associated with one or more LEDs  21  on the control panel to usually indicate when motion has been detected. An audio alarm can also be provided by annunciator  20 . Other embodiments can use a single motion sensor or multiple ones in selected positions on the housing. 
         [0017]    The system is shown in block diagram form in  FIG. 2 . Batteries  40  and  42  provide DC power to a control processor  44  which also receives a signal from a current sensor  46 . Motion detector  24  provides signals to controller  44 . The controller provides a control signal to DC to DC converter  50  which in turn drives lamp ballasts  52  which drive UVC lamps  54 . The controller  44  also provides output signals to one or more system displays  18  and an audio annunciator  20 . The system typically operates for a predetermined period of time as governed by a time period set in the controller. Upon activation of the system by pushing the start switch  22 , the lamps are turned on for the specified period of time and are turned off when the time ends. A countdown of the operating time is shown in the display  18  on the front panel. 
         [0018]    The controller  44  monitors the current to each of the electronic ballasts to insure that all of the lamps are operating properly. If the current as sensed by the current sensor  46  is less than the designated reference value, the controller will turn off the UVC lamps and display a message on front panel display  18 . Typically, the current monitor signal is converted to a digital signal by means of an analog to digital converter for comparison with a stored reference value. The converter can be part of the controller or a separate item. 
         [0019]    The batteries are typically lithium ion batteries rated at 28 volts and which can be recharged in approximately one hour. In the illustrated embodiment two UVC lamps are employed each having a 55 watt rating. The illustrated embodiment provides sufficient ultraviolet intensity to decontaminate a typical aircraft bathroom in three minutes and the battery supply is sufficient to decontaminate about ten bathrooms before the batteries need to be recharged. 
         [0020]    The controller monitors the voltage of the batteries and provides a signal to the visual display  18  to indicate a low battery condition and serve as a reminder that it is time to recharge the batteries. Other visual and/or audible indications can be provided by LED  21  and annunciator  20  to warn of a low battery condition. 
         [0021]    An electrical schematic of the system is shown in  FIG. 3 . Each battery has one terminal coupled to DC to DC converter  50  via an overcurrent protective device such as a thermally resettable circuit breaker  60 , and an isolation diode  62 . Each isolation diode is in series with the respective circuit breaker and prevents interaction between the batteries. The other battery terminals are coupled to electrical ground as shown. The batteries feed the converter  50  in parallel and the converter changes the battery voltage, typically 18-30 volts DC, to a fixed DC level of 120 volts. The electronic ballasts operate at 120 volts DC as well as 120 volts AC, and in the present embodiment the ballasts are driven by direct current from the batteries and converter. The current from the converter  50  into the ballasts is monitored typically in the ground lead to determine if one or more of the UVC lamps are operating properly. The monitored current is compared by the controller with a reference value and if below the reference value, the controller shuts down the system and causes indication of an error condition on display  18  and/or annunciator  20 . In the illustrated embodiment, the UVC lamps are driven in series by the ballasts so that both tubes are either fully on or off. Alternatively, two separate ballasts could be used to drive each lamp individually. 
         [0022]    The controller  44  governs the decontamination time of the system, monitors operating parameters of the system and provides visually and audio signals to indicate the operating conditions of the system. The microprocessor includes an analog to digital converter which monitors the current to the electronic ballasts, the voltage of each battery and the control signals from the start switch and motion detectors. 
         [0023]    The embodiment shown is operative to kill at least 99% of pathogens including  Clostridium difficile  in about 3 minutes in an aircraft bathroom in which the surfaces to be decontaminated are no more than three feet from the UVC lamps. 
         [0024]    The invention is not to be limited by the particular embodiments shown and modifications and alternative implementations are contemplated and within the intended scope of the invention. Accordingly, the invention is not to be limited by what has been particularly shown and described except as defined by the appended claims.