Abstract:
A method and apparatus for disinfecting water using ultraviolet light. An apparatus with an ultraviolet light source is floated in a water container such that the ultraviolet light source is suspended beneath the water surface and is capable of emitting ultraviolet light into the surrounding water.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates generally to devices and methods for disinfecting water and, more particularly, to a portable, low-cost system for disinfecting water using ultraviolet light. 
       BACKGROUND OF THE INVENTION 
       [0002]    Every day, thousands die worldwide due to infections from waterborne bacteria and viruses. Death typically results from acute dehydration, malnutrition, or other related complications. The majority of victims are young children or elderly people that live in economically impoverished countries. In these regions, contaminated surface water sources and poorly functioning municipal water distribution systems lead to the transmission of waterborne bacterial and viral diseases. Although the problem is particularly bad in impoverished countries, population groups in developed countries, such as residents in remote rural areas of the United States with poor water treatment and delivery systems, are also at risk. In addition, campers and hikers who do not have access to treated water also commonly fall victim to waterborne bacterial and viral infections. 
         [0003]    Conventional centralized water treatment and distribution systems can be very expensive and take years to construct. Furthermore, it is often impractical to provide centralized water treatment in sparsely populated areas. Therefore, providing at-risk groups with potable water requires innovative practical solutions such as, for example, point-of-use disinfection. In one disinfection method, ultraviolet (“UV”) radiation having wavelengths in the range of 200 to 300 nm are used to kill disease-carrying microorganisms in water. UV radiation has been found to deactivate a broad spectrum of pathogenic contaminates from amoebic-sized microorganisms to bacteria, algae and viruses. Water purification by ultraviolet radiation provides numerous advantages over other currently available water treatment methods. For example, UV water purification systems do not require chemicals nor do they require expensive filters. 
         [0004]    Existing UV water purification systems are often large installed flow-through systems serving a large number of people. However, in recent years, a number of smaller portable UV water purification systems have become available for use by individuals. Portable UV water purification systems use fluorescent tubes for emitting UV light into the water. A quartz cover is often provided around the fluorescent tube to protect the light source from mechanical shock and to electrically insulate the light source from the water being disinfected. Quartz covers are commonly used because it has been found that quartz is transparent at germicidal UV wavelengths, such as, around 254 nm. 
         [0005]    Existing portable UV water purification systems also include electronic circuitry for driving the fluorescent lamp. These devices and their circuits are often heavy and include multiple batteries in order to power the device and as such will sink if released into the liquid being treated. Furthermore, they must be affixed to the containers of liquid they are treating or otherwise held in place therein. As a result many containers are not viable candidates for treatment with such a device. Finally, point-of-use devices are generally small and cannot reach into the depths of a large container, limiting their usefulness to small storage and drinking containers. 
         [0006]    Due to the costs associated with existing UV water purification systems, a need exists for an improved water purification system that requires fewer components and is easily affordable to large segments of the population. It is desirable that such a system be rugged in construction and easily transportable for disinfecting drinking water in regions where water purification is not readily available. It is also desirable that such a device be lightweight, compact, and easy to use. The present invention addresses these needs. 
       SUMMARY OF THE INVENTION 
       [0007]    The disclosed methods and devices provide improved portable UV water purification. A preferred embodiment is small and light enough to be easily transported and floated in nearly any container of liquid. Other embodiments may include other features and advantages, such as one or more switches to control starting or stopping the treatment cycle, an internal power source, indicators of system status and operation, and a small, easily grasped handle on top of the device to facilitate removal of device from liquid. Another embodiment may also be able to detect whether it is immersed in a liquid, measure how long it has been active or inactive, and control the operation of the UV light source based on these parameters. Means for recharging an internal battery power source may also be provided. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The features and advantages of the present invention will be discussed in detail in the following description, and in conjunction with the accompanying drawings: 
           [0009]      FIG. 1  is a perspective view of an embodiment of the water purification device. 
           [0010]      FIG. 2  is a perspective view of an embodiment of the water purification device. 
           [0011]      FIG. 3  is an inside view of an embodiment of the water purification device. 
           [0012]      FIG. 4  is a perspective view of an embodiment of the water purification device. 
           [0013]      FIG. 5  is a perspective view of another embodiment of the water purification device. 
           [0014]      FIG. 6  is a perspective view of another embodiment of the water purification device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Preferred embodiments of the present invention described herein provide an improved floating portable water purification device which uses UV light for killing disease-carrying microorganisms in water. The water purification device may be used to remove contaminants from dangerous water supplies in locations wherein water purification is not readily available. In one application, the water purification system may be used by residents living in remote or impoverished regions to treat contaminated water. In another application, campers or hikers may use the water purification device to disinfect water from lakes or streams before drinking. Furthermore, the water purification device may be used to disinfect water around the house during emergencies, such as an earthquake or flood, wherein the tap water has become contaminated. 
         [0016]    With reference now to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes, generally, UV light source  12 , control circuit  28 , power supply  26 , enclosed within bulbous case  32  capable of floating in the liquid it is treating. In one preferred embodiment, the water purification system is constructed such that the UV light source does not require a quartz cover, thereby substantially reducing the cost of manufacture. 
         [0017]    With continued reference to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes a compartment shape which makes the device easy to grasp, and a handle  22 . 
         [0018]    With continued reference to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes a sensor  14  for detecting the presence or absence of liquid. The device may be designed such that it will not start if not immersed in the liquid to be treated, or can shut off automatically if removed from the liquid. Methods and circuits for performing this function are well known and are exemplified by the teachings of U.S. Patent Application 2005/0205480 filed on Dec. 3, 2004 by Kuhlmann et al., which is incorporated in its entirety herein by reference. 
         [0019]    With continued reference to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes one or more buttons  16 . The button(s)  16  can be configured to turn the UV lamp, tube, or other source  12  on and or off directly and or configured as input to a circuit such as a micro-controller that controls the lamp output. 
         [0020]    With continued reference to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes one or more light-emitting diodes (“LED”)  20  or other visible lamps. LED  20  may be colored for simple low level illumination or indication or it can be bright white type and be used for illumination secondary to the primary function of liquid treatment. LED  20  can also be used to indicate the various functions and conditions of the device including but not limited to start indication, normal cycle completion, aborted cycle completion, and low battery as well as other status conditions. More than one LED  20  can be used in combinations of colors and white to allow various combinations of indicators and illumination. 
         [0021]    With continued reference to the  FIG. 1 , for purposes of illustration, one preferred embodiment of a water purification device includes a compartment cover  18  that allows access to internal components including the battery  26 , circuit board, UV lamp  12  if not serviced from outside the compartment, and other internal components. 
         [0022]    With reference now to the  FIG. 2 , for purposes of illustration, one embodiment includes UV transparent cover  24 . One preferred embodiment of a water purification device includes a cover  24  to protect the UV lamp  12  and that can also be sealed to the case  32  to assist in protecting the internal components from leakage of the liquid into the compartment. In all other respects all of the heretofore discussed combinations are possible with the addition of UV transparent cover  24  including liquid sensor  14 , LEDs  20 , timer, handle  22 , etc. 
         [0023]    With reference now to the  FIG. 3 , for purposes of illustration, a number of internal features are shown. One preferred embodiment includes an auxiliary power jack  30  that allows the device to be powered from an external source or disconnected and run from an internal battery  26 . Although preferred embodiments are described herein as using batteries to provide a power supply, a variety of alternative power sources may be used. For example, a human powered generator may be incorporated into the device or may be provided as an option that may be attachable to the device. In another alternative embodiment, a solar powered generator (e.g., photo-voltaic cells) may be used to provide a power source. These alternative power sources may be used alone or in combination with batteries. The human powered generator and the solar powered generator each has the advantage of providing a renewable power source that can be used anywhere. Other power sources capable of providing the necessary electrical current and voltage will be apparent to those of skill and are intended to be within the scope of the claims. 
         [0024]    With further reference to the  FIG. 3 , an internal power source can include a battery  26 . The battery may be rechargeable and the control circuit  28  can be configured to manage charging of said battery. 
         [0025]    An external power source can be connected by way of leads with magnets fixed to their ends. The external power source so connected can be used to operate the device or to recharge an internal rechargeable battery  10  or power the device separately. 
         [0026]    With reference now to the  FIGS. 4 ,  5 , and  6 , for purposes of illustration, the operation of the device will now be described during use for disinfecting water. Before use, the circuit is initially in “off” condition such that the circuit to the UV lamp  12  is open and no current flows. After a container  34 , such as but not limited to those shown in  FIGS. 4 ,  5 , and  6 , is filled with water or another liquid, the user actuates the button or switch  16  to begin a sterilization cycle. In one preferred embodiment, button  16  is disposed at the top end of the device  10 . A single pole push button switch may preferably be used for reducing system cost. 
         [0027]    After the switch  16  is depressed, one preferred embodiment uses a micro-controller in the control circuit  28  which wakes from a low power mode and begins operating. During use, if the user desires to terminate the cycle for any reason, the button  16  may be pressed again during operation of the UV lamp  12 . This will cause the sterilization cycle to terminate. 
         [0028]    In one variation, the micro-controller is preferably configured to detect when the lamp has been struck (i.e., confirm the light source is emitting UV radiation) by monitoring the voltage pulses across the UV lamp  12 . Shutting down is desirable when pulses are not detected since no low impedance path exists for the power supply. The shut-down feature prevents waste of energy, harm to the control circuit, and provides an opportunity to attempt to strike the UV lamp  12  again or warn the user of a failure to operate correctly. 
         [0029]    In yet another variation, one or more LEDs  20  or other indicators may be included in the circuit to provide visual feedback to the user during operation. In one preferred embodiment, a visual indicator LED  20  is illuminated at the completion of the sterilization cycle to indicate whether the cycle was successful. For example, if the UV lamp  12  and circuit  28  are operating correctly, the cycle proceeds for a pre-selected period of time that is sufficient to be germicidal for clear liquids in the amount contained. If necessary or desired, the container  34  can be agitated or if equipped with a cover to retain the water such as in  FIG. 4  can be turned over such that all parts of the container  34  and liquid contained therein are treated by the UV light. 
         [0030]    In another embodiment, LED  20  may be white, a single color, or be capable of displaying in multiple different colors for the purpose of conveying different information. For example, a green LED  20  may be illuminated upon successful completion of the sterilization cycle. Conversely, if the sterilization cycle failed to complete for some reason, a red LED  20  may be illuminated to alert the user that the water is not safe to drink. In a one-color embodiment, for example, the light may blink if the cycle is not successfully completed and come on steady for a period of time if the cycle is successful. 
         [0031]    In yet another preferred variation, one or more electrically connected pins used as a liquid sensor  14  are provided for detecting the level of the water in the container  34 . In another preferred configuration, sensor  14  is in contact with the water being sterilized only when the water level is high enough to completely immerse the UV lamp. The primary purpose of the sensor  14  is to help prevent unnecessary exposure to UV radiation. Liquid sensor  14  can be used to prevent operation of the float device  10  until it senses that it is immersed in water for a significant period of time, for instance a few seconds. Thus it provides a safeguard that is also relatively impervious to false activation by a stray raindrop or some mist or splash. 
         [0032]    This provides an additional level of safety which helps prevent striking the tube when the UV lamp  12  is not completely immersed. More particularly, when the water level is insufficient, the container  34  does not provide contact with the pin(s). In another variation, one or more pins may provide a temperature sensor. In this embodiment, the micro-controller may adjust the period of the disinfection cycle according to water temperature. 
         [0033]    The UV water purification device  10  provides an efficient and easy to use device for treating water. The device  10  has a rugged construction and is small and lightweight such that the system may be easily carried to a remote location, such as during hiking or camping. The device  10  may be manufactured at a low cost, thereby making the system affordable to persons living in impoverished areas that lack access to adequate water treatment facilities. 
         [0034]    Preferred embodiments of the present invention provide an improved portable UV water purification  10  device. In one preferred embodiment, the device is small enough to be carried easily and floated in the container  34  of liquid being treated. 
         [0035]    A further preferred embodiment includes a small, easily grasped handle  22  on top of the device to facilitate removal of device  10  from liquid. Thus the user will readily be able to pluck the device  10  out of the liquid being treated. 
         [0036]    A further preferred embodiment includes one or more switches  16  to control starting or stopping the treatment cycle. This or these switches  16  could also enable or disable other optional features such as flashlight or length of treatment cycle. 
         [0037]    A further preferred embodiment has the device being sealed on all sides against penetration of liquid. If the container  34  is large enough that some of the liquid to be treated is out of the effective reach of the UV light, and the container  34  has a lid or other method of enclosing the liquid, the container  34  can be inverted and otherwise moved such that more of the container  34  and enclosed liquid can be treated. This and other embodiments also allow the user to fill the container  34 , such that it is not necessary to remove the device between treatments. 
         [0038]    The water purification device  10  is preferably provided with a power source  26 , such as batteries, and electronic circuitry for controlling the radiation of UV light. A case  32  may contain the power source  26  and electronic circuitry. 
         [0039]    In one variation, a timing function, preferably implemented in a micro-controller, is operatively connected to the control circuit  28 . The timing functionality may be implemented in software in the micro-controller. The micro-controller may then control the length of the treatment cycle by means of a timing function. 
         [0040]    In another variation, the method further includes an indicator lamp  20 , preferably a LED, to indicate to the user status of the device when in use. The LED  20  could indicate that the device  10  has been started; stopped; experienced an error, such as low batteries or premature termination of the treatment cycle; or other device or operation status. 
         [0041]    In another variation, the method further comprises sensing that the liquid is above a predetermined level before applying power to the UV lamp  12 , or removes power from the UV lamp  12  if liquid is not detected within a predetermined period of time. This feature prevents the system from operating when the container  34  is not sufficiently full of a liquid. Preferably a sensor  14  or metal contact extends into the interior volume such that the liquid can be detected by the control circuit or micro-controller if present. 
         [0042]    In another variation, the method further comprises a cover  24  which is transparent to UV to protect the lamp. The UV transparent cover is made of quartz or other special UV transparent glass or plastic. 
         [0043]    In another variation, the method further comprises a lantern or flashlight feature, where preferably a white LED is powered from the same source and provides a secondary function to the liquid treatment while being housed in the same case  32 . 
         [0044]    In another variation, the method further comprises a charging circuit or a circuit and otherwise necessary connections that allows an internal rechargeable battery to be recharged. Said connections could be fixed to the charge source with leads, and leads may be affixed to the charging source with magnets attached at the lead ends. 
         [0045]    While the foregoing detailed description has described several embodiments of the apparatus and methods of the present invention, it is to be understood that the above description is illustrative only and not limiting of the disclosed invention. It will be appreciated that the specific components can differ from those described above, and that the methods described can be used with a wide variety of systems, while remaining within the scope of the present invention.