Abstract:
Introducing ultraviolet (UV) light ( 102, 202 ) to alter the environment inside a shoe destroys microorganisms or inhibits their growth. Visible light can also be used to prevent further growth. A preferred embodiment comprises an adjustable shoe tree ( 200 ) equipped with a UV germicidal light source ( 202 ) and electronic safeguards ( 284, 370 ) that prevent appreciable leakage of UV radiation outside the shoe.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. Provisional Patent Application Nos. 60/781,276 and 60/881,552, filed Mar. 13, 2006 and Jan. 22, 2007, respectively. 
     
    
     COPYRIGHT NOTICE 
       [0002]    © 2007 Shoe Care Innovations, Inc. A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR § 1.71(d). 
       TECHNICAL FIELD 
       [0003]    The present disclosure pertains to the use of light as a sanitizing agent in human footwear. 
       BACKGROUND INFORMATION 
       [0004]    Warm, damp, dark environments provide favorable conditions for growth of infectious biological microorganisms, allowing bacteria, viruses, fungi, and their associated odors to proliferate. For example, foot perspiration within shoes promotes warmth and dampness, while closed shoes stored in dark closets may fail to admit enough broad spectrum ambient light, which includes a component of UV light, to control pathogen levels. Excessive levels of harmful microorganisms sustained in enclosed shoes may cause or promote various foot maladies. 
         [0005]    It is well-known that exposure to ultraviolet (UV) light of certain wavelengths, intensities, and durations can destroy or inhibit growth of surface pathogens. For instance, germicidal lamps that emit UVC radiation are used to treat waste water for the purpose of reducing organic content. U.S. Pat. Nos. 4,981,651 and 5,978,996 describe the use of UV light for sterilization; however, not all UV light wavelengths are germicidal. The UV spectrum spans wavelengths from 10 nm to 400 nm. The band from 320 nm to 400 nm is designated as UVA; 280 nm to 320 nm is UVB; and 185 nm to 280 nm is UVC. Germicidal UV light, the type that destroys microorganisms, is limited to a wavelength range from 240 nm to 280 nm, in which maximum germicidal efficiency coincides with a wavelength of 254 nm. UVA and visible light, which includes a near-UV component, have been shown to inhibit growth but not to destroy pathogens. 
         [0006]    One concern with harnessing UV light, which is a form of short wavelength, high energy radiation, is that UV light can cause damage to human tissue. Eyes are especially vulnerable when exposed to direct incidence of UV light. Thus, any application of high energy radiation, including UV light, should protect against unwanted exposure. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    The present disclosure relates to introducing light to alter the environment inside a shoe to destroy microorganisms or to inhibit their growth. In one embodiment, delivery of germicidal UV light is accomplished by mounting a set of light emitting diodes (LEDs), tuned to an appropriate UV wavelength, inside a hollow shoe tree that is inserted into the toe of the shoe. UV LEDs that emit light within the germicidal range can be used to destroy microorganisms residing in the shoe. In a second embodiment, an alternative light source, a UV germicidal bulb, is used in place of UV LEDs. In a third embodiment, visible light LEDs or a visible light bulb, both of which are less expensive and easier to acquire than germicidal UV light sources, are used because light within the visible spectrum inhibits or prevents further growth of microorganisms, as opposed to actually killing them. A fourth embodiment, suitable for commercial use, relies on an enclosure to contain UV light emanating from a bulb inserted inside a shoe, without the support of a shoe tree. 
         [0008]    Embodiments of or accessories associated with a shoe tree are implemented with safeguards to contain UV radiation exposure within a region of interest. One method of containing UV radiation inside a shoe entails placing an opaque or a translucent barrier between the propagation path of the UV radiation and openings in the shoe. A preferred embodiment of such a barrier is a seal set around the spine or heel of a shoe tree. Alternatively, the forepart of a shoe tree may incorporate a light restrictor, or caps may be placed over openings in the shoe. 
         [0009]    Another method of preventing unwanted UV exposure entails activating the UV light source only if a threshold level of ambient light is not detected. Ambient light detected inside a shoe indicates a light leak, which could allow UV radiation to escape. A light leak could be the result of improper insertion of the UV light source into the shoe. Disabling the UV power source when a threshold level of ambient light is detected by a light sensor, such as a photodiode or a phototransistor, prevents unwanted UV exposure. 
         [0010]    A variation on this method of preventing unwanted UV exposure entails implementing an electrical safety switch that prevents operation of the UV light source unless the UV light source is properly inserted in the shoe. When positioned correctly, the UV light source closes an electrical circuit, causing actuation of the safety switch to an operating condition that allows a user to activate the light source. 
         [0011]    A further method of safeguarding the user from unwanted exposure to UV light entails placing the shoe inside a container. The container is made of translucent, opaque, or transparent material that absorbs at least some of the UV light emanating from the interior of the shoe. Use of a container may be combined with the aforementioned light sensor to reduce the intensity of ambient light inside the shoe, provided that the container is translucent or opaque. This is a preferred method of treating sandals or open-toed shoes with germicidal UV light while reducing risk of unwanted UV exposure. 
         [0012]    Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an isometric view of a first preferred embodiment of a shoe tree, as seen from underneath a hollow forepart of the shoe tree to show placement of light emitting diodes (“LEDs”). 
           [0014]      FIGS. 2A and 2B  are top and bottom isometric views, respectively, of a second preferred embodiment of a shoe tree, in which an ultraviolet germicidal bulb is installed. 
           [0015]      FIGS. 3A ,  3 B,  3 C,  3 D, and  3 E are, respectively, top plan, right-hand side, left-hand side, rear, and front elevation views of the shoe tree shown in  FIGS. 2A and 2B . 
           [0016]      FIG. 3F  is a front perspective view of the shoe tree shown in  FIGS. 2A and 2B . 
           [0017]      FIG. 3G  is a sectional view taken along lines  3 G- 3 G of  FIG. 3A . 
           [0018]      FIG. 4  is an exploded view of the shoe tree shown in  FIGS. 2A and 2B . 
           [0019]      FIG. 5  is an enlarged, fragmentary sectional side elevation view of the heel section of the shoe tree shown in  FIGS. 2A and 2B . 
           [0020]      FIG. 6  is an enlarged, fragmentary isometric view of the safety interlock switch in the heel section of the shoe tree shown in  FIGS. 2A and 2B . 
           [0021]      FIG. 7  is an enlarged, fragmentary sectional side elevation view of the hollow forepart of the shoe tree shown in  FIGS. 2A and 2B . 
           [0022]      FIG. 8  is an enlarged, fragmentary pictorial view of a width adjustment mechanism in the forepart of the shoe tree shown in  FIGS. 2A and 2B . 
           [0023]      FIGS. 9A ,  9 B, and  9 C are diagrams of safety enclosures that prevent light leakage from a shoe sterilizer installed in a shoe. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0024]      FIG. 1  shows, as a first embodiment, a shoe tree  100  configured to accommodate a semi-circular linear array of LEDs  102  that, in a preferred embodiment, radiate germicidal UV light, or white light including a UV component, into the toe of a shoe in which shoe tree  100  is inserted. A UV LED that emits light within the germicidal range and is suitable for use in LED array  102  is a Model No. UVTOP255-BL-TO39, available from Roithner LaserTechnik, Vienna, Austria. Visible light (blue or white) LEDs, which are readily available, can be used to inhibit or prevent further growth of microorganisms in the shoe. Shoe tree  100  includes a hollow forepart  104  connected by an extensible one-piece cylindrical spine  106  to a heel section  108 . 
         [0025]    Forepart  104  is a curved half-shell structure having an inner surface  110  that supports multiple inwardly directed, spaced-apart structural tabs  112  and having multiple generally rectangular, elongated slots  114  that are spaced apart in a transverse direction to the length of forepart  104 . Light emitted by LED array  102  propagates through elongated slots  114  and impinges directly on the interior lining of the upper of a shoe (not shown) in which shoe tree  100  is placed. Because forepart  104  of shoe tree  100  is hollow, the interior footbed of the shoe is illuminated by LED array  102 . A wall  120  defines a back end of forepart  104  and has an interior surface  122  on which LED array  102  is mounted. Light emitted by LED array  102  propagates primarily in a forward direction toward the toebox of the shoe. A half-oval cutout  122  in wall  120  allows cylindrical spine  106 , which extends out of and retracts into the interior of heel section  108 , to extend into the toebox of the shoe, or retract to the middle of the shoe, as needed to adjust the overall length of shoe tree  100  to fit a particular shoe. Heel section  108  of shoe tree  100  is of a design found in a conventional shoe tree. Heel section  108  is in the shape of a modified solid rectangular block, with a rounded lower surface  126 , in which the depth  128  of the solid block becomes gradually thicker from front to rear, to better conform to the heel of a shoe. The bottom of heel section  108  may be scored twice, dividing its surface lengthwise into three sections. 
         [0026]      FIGS. 2A ,  2 B;  3 A- 3 G, and  4 - 7  show, as a second embodiment, a sterilizing shoe tree  200  in which a UV germicidal bulb  202  is installed, instead of LED array  102  used in shoe tree  100 . Shoe tree  200  includes a hollow forepart  204  connected by a spring-loaded extensible spine  206  to a heel section  208 . Electronic components enabling UV safety features are concealed throughout heel section  208 , spine  206 , and hollow forepart  204  and are, therefore, not apparent from the exterior of shoe tree  200 . Heel section  208  terminates in a closed loop-shaped handle  210  to facilitate length adjustment; spring-loaded extensible spine  206  allows linear motion into and out of heel section  208 ; and hollow forepart  204  features large openings, or windows, of non-uniform size and shape through which light can propagate into the interior of a shoe. A power supply cord  212  extends from the rear of heel section  208  and provides electrical power for delivery to UV germicidal bulb  202  as described below. The top of handle  210  includes a power-on button  214 , which activates the UV bulb along with its safety checks. The manufacture of shoe tree  200  may incorporate a scent into the material by impregnating it with a liquid, a solid, or a gel. For example, shoe tree  200  could be constructed from a scented polymer such as that used in the manufacture of AURACELL products by Rotuba, Linden, N.J. 
         [0027]    With particular reference to  FIG. 3A , forepart  204  is formed by two skeletal sections, including a left-hand side skeletal section  218  and a right-hand side skeletal section  220 . Skeletal section  218  has from front to back an approximately triangular-shaped window  222  and a generally parallelogram-shaped window  224 . Skeletal section  220  has from front to back generally parallelogram-shaped windows  230 ,  232 , and  234 . 
         [0028]      FIG. 3A  shows the asymmetric design of hollow forepart  204  of shoe tree  200 . Windows  224  and  234  are symmetric about a central longitudinal axis  238 , which runs along the seam of skeletal sections  218  and  220  when they are assembled together. Central longitudinal axis  238  extends straight through the instep of shoe tree  200 , angling sideways at approximately 60° in the toe area, causing the foremost window openings  222  and  230 , to be irregularly shaped. A pair of shoe sterilizers includes left-hand and right-hand shoe trees, the left-hand shoe tree configured in a mirror image of right-hand shoe tree  200  shown in  FIG. 3A . 
         [0029]    With particular reference to  FIG. 4 , skeletal section  218  has a floor portion  244  from which a tab member  246  extends and contacts a tab member  248  that extends from a floor portion  250  of skeletal section  220  (see also  FIG. 3   g ). Tab members  246  and  248  form a smooth surface region when skeletal sections  218  and  220  are assembled together at the bottom of hollow forepart  204 . Skeletal sections  218  and  220  support on their respective floor portions  244  and  250 , mounting blocks  252  that are sized to receive and support a split bulb carrier  254 . Split bulb carrier  254  is an assembly of matable half sections  256 , from which T-shaped projections  258  extend. Base portions  260  of T-shaped projections  258  mate with slots  262  of complementary shape formed in corresponding mounting blocks  252  to hold split bulb carrier  254  in place when skeletal sections  218  and  220  are assembled together. Tabs  264  extending upwardly from base portions  260  of half sections  256  of bulb carrier  254  accommodate a width adjustment of hollow forepart  204 , by constraining sideways motion of moveable skeletal sections  218  and  220  within their associated slots  266 , one of which is shown in  FIGS. 2B and 4 . 
         [0030]    Split bulb carrier  254  forms a threaded socket that receives a threaded base  280  of germicidal bulb  202  and a carrier for a small electrical circuit board  282  on which is mounted an electronic ambient light sensor  284 . A suitable UV germicidal bulb  202  is a Model No. GTL3, available from Ushio, Inc., Cypress, Calif. An ambient light sensor  284  suitable for use in shoe tree  200  is a Model No. LX1972IBC-TR, available from Microsemi, Irvine, Calif. A pair of leaf springs  286  attached to the front of circuit board  282  ensures contact to the positive and negative terminals of UV germicidal bulb  202 . The output signal of ambient light sensor  284  controls initial activation of a sterilizing operation of shoe tree  200  and is, therefore, active for a momentary portion of the sterilizing operation. The output signal is delivered through a cable  288  to heel section  208 . 
         [0031]    With particular reference to  FIGS. 4 and 5 , heel section  208  is an assembly of matable half-shell sections  300 , which are held together by screws  302 . Each half-shell section  300  has interior mounting tabs  304  that support an electrical circuit board  306  in position below and along the length of the bottom part of handle  210 . Circuit board  306  provides a connection point  308  in the form of a power supply for power supply cord  212  and a connection point  310  for cable  288 . Circuit board  306  carries a microcontroller  312  that controls the operation and safety functions implemented in shoe tree  200 . Microcontroller  312  controls through cable  288  delivery of electrical power to UV germicidal bulb  202  and processing of the output signal of ambient light sensor  284 . Spring-loaded adjustable spine  206  includes at its forward end a skeletal section spread plate  320  terminating in hollow forepart  204  and at its rear end a long coil spring  322  terminating in heel section  208 . 
         [0032]      FIG. 4  shows a clevis  326  at an end of spread plate  320  and a spring carrier  328 . Spread plate  320  has a support surface  330  on which half sections  256  of split bulb carrier  254  rest. Upright end tabs  332  of spread plate  320  hold split bulb carrier  254  in place by restricting its forward movement as spine  206  undergoes changes in length. Two guide slots  334  in spread plate  320  converge in a forward direction toward the toe end of forepart  204 . Stepped guide pins  336  pass through guide slots  334  in spread plate  320  and holes  338  in mounting blocks  252  of skeletal sections  218  and  220  to secure spread plate  320  to skeletal sections  218  and  220  and spread them apart in response to a shortening of spine  206 . Spread plate  320  is positioned in forepart  204  so that UV germicidal bulb  202  is set at a fixed distance of 5 cm from the end of a shoe in which shoe tree  200  is installed. The reason for such bulb placement is that the intensity and therefore the effectiveness of UV energy as a sterilizing agent decreases with distance away from the light source. Spring carrier  328 , which is formed of two matable U-shaped rails  344 , contains and secures in its interior an end  346  of coil spring  322 . Spring carrier  328  is fixed by a pin  350  to clevis  326  of spread plate  320 . 
         [0033]      FIG. 5  shows coil spring  322  passing through a tubular housing portion  352  in the forward end of heel section  208  and an end  354  of coil spring  322  resting against a stop  356  in the rear end of heel section  208 . Coil spring  322  is held in a nominal partly compressed state in spine  206 . A strain relief clamp  358  holds cable  288  in position on housing portion  352  of heel section  208  as spine  206  undergoes changes in length. An articulated rubber sleeve  360  positioned between forepart  204  and heel section  208  fits over spring carrier  328  and conceals it from view. 
         [0034]      FIGS. 5 and 6  show a photo-interrupter  370 , which includes a spaced-apart infrared (IR) transmitter/detector pair. A fin  372  attached to the back end of U-shaped rail  344  obstructs IR light emitted by the transmitter from reaching the receiver when coil spring  322  is in its nominal partly compressed state. Compression of spring  322  as shoe tree  200  is placed in a shoe causes fin  372  to move rearward, thereby allowing IR light to reach the detector. The output signal from photo-interrupter  370  is sent to microcontroller  312  on circuit board  306  to enable application of power to UV germicidal bulb  202  through cable  288 . A suitable photo-interrupter  370  is Part No. GP1S092HCPIF, available from Sharp Electronics Corporation, Romeoville, Ill. 
         [0035]      FIGS. 7 and 8  show the front end of cable  288  where it plugs into split bulb carrier  254  securing UV germicidal bulb  202 . Three parallel ribs  374  acting as structural supports for hollow forepart  204  extend downward from the top interior surface of skeletal section  220 .  FIG. 7  shows ribs  374  positioned above the exterior surface of split bulb carrier  254 , together with two vertical bulkheads  376  ( FIG. 3G ) positioned on either side of rubber sleeve  360  covering spine  206 , to block light from escaping the toe of the shoe. With reference to  FIG. 8 , for each of skeletal sections  218  and  220 , a coil spring  348  is positioned between a spring tensioner post  364  and guide pin  336  to hold skeletal sections  218  and  220  together when shoe tree  200  is not placed in a shoe. (In  FIG. 8 , only one coil spring  348  appears, and it is shown disconnected from spring tension post  364 .) Spring tensioner post  364  and guide pin  336  are positioned outside of threaded base  280  of UV germicidal bulb  202 . Guide pin  336  restricts lateral displacement of skeletal section  220 . The end of a circular rivet  378  joining half sections  256  of split bulb carrier  254  is visible in  FIG. 7 , along with pin  350  located in clevis  326  at the rear of spread plate  320 . Pin  350  forms a pivot point allowing spine  206  to articulate upward relative to forepart  204 . 
         [0036]    Adjustment of the length of spine  206  to place shoe tree  200  in a shoe is accomplished by a user grasping handle  210  and positioning forepart  204  in the toe box of the shoe. The user then exerts pressure on heel section  208  to compress coil spring  322 , while lowering heel section  308  into the heel of the shoe. Compressing coil spring  322  shortens spine  206  and thrusts spread plate  320  forward, thereby separating skeletal sections  218  and  220 , and producing a snug fit of shoe tree  200  in the shoe so that UV light will not escape from it. 
         [0037]    After shoe tree  200  is positioned inside a shoe, application of electrical power through power supply cord  212  by actuation of power-on button  214  triggers the following sequence of events to protect user safety: A preliminary ambient light check is initiated using light sensor  284  to ensure UV source  202  is contained within the shoe with no detected light leaks. If the ambient light check is negative (i.e., no appreciable light leakage detected), a heel compression check using photo-interrupter  370  acting as an electrical safety switch is initiated to ensure that shoe tree  200  is properly positioned within a shoe. If the heel compression check is positive (i.e., improper shoe tree installation not detected), microcontroller  312  engages UV light source  202  to sterilize the shoe for approximately 30 minutes. If during a 30-minute shoe sterilization operating window shoe tree  200  is removed or dislodged from the shoe, safety switch  370  deactivates the UV light source  202 . The forepart ambient light check using sensor  284  is not active during the 30-minute operating window. 
         [0038]    An alternative embodiment without use of a shoe tree lends itself to commercial use and prohibits, by blocking the escape of UV radiation during a shoe sterilization operating window, the UV light from reaching an individual who is proximally located to the shoe. This alternative embodiment entails inserting a UV lightbulb into a shoe and either surrounding the shoe with a protective “shower cap,” enclosing the shoe in a protective bag, or sealing the opening of the shoe. 
         [0039]    More specifically,  FIG. 9A  shows a series of images that illustrate enclosing a shoe  380  (image A 1 ) in a shower cap style enclosure  382  (images A 2  and A 3 ) and inserting a UV lightbulb  384  attached to a long, cylindrical handle  386  (image A 4 ) through an opening  388  in enclosure  382  into the inside of shoe  380  (image A 5 ). Enclosure  382  is secured around shoe  380  by tightening a drawstring  390 .  FIG. 9B  shows a series of images that illustrate enclosing shoe  380  in a closed bag  392  (image B 1 ). UV lightbulb  384  attached to handle  386  is inserted in an opening  394  in bag  392  (image B 2 ) and into the inside of shoe  380  (images B 3  and B 4 ). Bag  392  is secured around shoe  380  by tightening a drawstring  396  that closes the open side of bag  392 . 
         [0040]    Both enclosure  382  and bag  392  are made of a UV light-blocking material. UV lightbulb  384  may be enclosed in a protective metal mesh cage  398 . 
         [0041]      FIG. 9C  shows a series of images that illustrate an alternative to full enclosure of shoe  380  by sealing the open top of shoe  80  with a cap  400  (image C 1 ). Cap  400  has an opening  402  through which UV light bulb  384  attached to handle  386  is inserted (image C 2 ). Disassembly of UV light bulb  384  and cage  398  from handle  386  is carried out to enable its passage through opening  402  and cap  400  (image C 3 ). 
         [0042]    It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.