Patent Publication Number: US-7218241-B2

Title: Device for identifying a person or an object

Description:
RELATED APPLICATIONS 
   This application is a 35 U.S.C. 371 national stage filing of International Application No. PCT/IB02/02903, filed 25 Jul. 2002, which claims priority to South Africa Patent Application No. 2001-7139 filed on 29 Aug. 2001 in South Africa. The contents of the aforementioned applications are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   This invention relates to a device for identifying a person or an object, and more specifically to a device which utilises light to identify a person or an object in dark or dim conditions. 
   Chemical light sticks for identifying a person in certain circumstances, for example under water, are known. Conventional chemical light sticks generally include a first chemical in an outer, flexible tube and a second chemical sealed within an inner glass tube inside the outer, flexible tube. To activate the light stick the outer tube is bent until the inner tube breaks and releases the first chemical into the second chemical to produce a fluorescent glow. The known types of chemical light sticks are available in different sizes and are marketed under different names, for example GLO-STICK, CYLUME, LIGHT-STICK, CHEM-STICK and CHEM-LIGHT. 
   A problem associated with known light sticks of the type described above is that the chemicals sustain the fluorescent glow for a limited time only, generally in the region of six hours, and consequently, under normal circumstances, these sticks cannot be re-used. Also, the activation of these light sticks is dependent upon the proper contacting of two chemicals, and consequently these sticks have to be used before an expiry date and often are defective upon purchase. 
   It is an object of the present invention to provide an alternative light-emitting device for identifying a person or an object which is relatively long-lasting, re-usable and robust. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a device for identifying a person or an object comprising:
         a transparent or translucent body, and   embedded within the transparent or translucent body,
           a printed circuit board (PCB),   a plurality of light emitting diodes (LEDs) electrically connected to the PCB, and   a diffuser for diffusing light emitted from the LEDs thereby to illuminate the transparent or translucent body to form a light source for identifying a person or an object attached to the device.   
               

   In a preferred embodiment of the invention, the diffuser includes a tapered portion defining a surface which is inclined relative to a longitudinal axis of the device at an angle of between 25° and 45°, preferably at an angle of approximately 30°. 
   In a particularly preferred arrangement, the device includes a housing defining a chamber for at least one battery. In this embodiment, the diffuser may form at least part of the battery housing. 
   Typically, the PCB is connected to the battery housing and is arranged to hold between three and six LEDs within the transparent or translucent body. 
   The LEDs and the diffuser preferably are arranged so that, when the transparent or translucent body is illuminated, the light source is visible from all sides of the device. 
   The device may include attachment means for attaching it to a person or an object. 
   The device may also include a switch for controlling the flow of current through the LEDs. 
   The switch may comprise a rotatable member which is threadably engaged with an end cap so as to be displaceable relative to the end cap between an operative position in which it contacts a terminal on a battery within the battery chamber and an inoperative position in which it is spaced from the terminal of the battery. 
   Alternatively, the switch may be arranged to operate under pneumatic or hydraulic pressure. 
   Typically, elastomeric O-rings form watertight seals on the end cap and on the rotatable switch member. 
   The device may also include a second PCB within the battery chamber for connecting a battery contact spring to a wire extending from the first PCB. 
   Conveniently, the transparent or translucent body is moulded from an epoxy resin, possibly with colour tints, and the PCB defines a plurality of openings for allowing the resin through the PCB during the moulding of the body. 
   In one arrangement, the battery housing is formed from aluminium, typically a marine grade aluminium, and includes a detachable, aluminium end cap. 
   In a configuration which produces a preferred strength and quality of light, the transparent or translucent body includes a 19 mm diameter cylindrical section, and six LEDs of 6 mm diameter are embedded within the cylindrical section, adjacent the diffuser, in a circular configuration. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: 
       FIG. 1  shows a perspective view of an identifier according to the present invention; 
       FIG. 2  shows a cross-sectional view of the identifier illustrated in  FIG. 1 ; and 
       FIG. 3  shows a side view of the identifier according to the invention. 
   

   DESCRIPTION OF AN EMBODIMENT 
     FIG. 1  of the drawings illustrates an identifier  10  according to the present invention. As can be seen, the identifier includes a battery housing  12  which has a cylindrical portion  14 , a tapered portion  16  and a connecting stem  18 . In this embodiment of the invention, the battery housing is formed from aluminium, typically a marine grade aluminium, and is seen in  FIG. 2  to define a chamber  20  for a battery  22  in the form of a single 12V super alkaline cell. 
   A knurled end cap  24  carrying a thread  26  is engageable with a corresponding thread  28  on the cylindrical portion  14  of the battery housing so as to be detachable for battery replacement. The end cap  24  carries an elastomeric O-ring  30  in an annular groove  32  which forms a watertight seal with the cylindrical portion  14  of the housing  12 , in use. A partly threaded bore  34  in the end cap  24  is sized to receive a partly threaded, rotatable switch member  36  which holds an elastomeric O-ring  38  for forming a watertight seal between the rotatable switch member and the end cap. Both O-rings  30  and  38  are silicone-based, high pressure rated O-rings. 
   In the illustrated embodiment, rotation of the switch member  36  relative to the end cap  24  displaces the member between an inoperative position (as illustrated in  FIG. 2 ) in which it is withdrawn from the battery  22  and an operative position (not illustrated) in which it contacts the negative terminal of the battery. The end cap  24  also includes an aperture  40  for receiving a ring or the like (not shown) for attaching the identifier to a person or an object. 
   The battery housing  12  is embedded in a transparent body  42  which is formed in a cold moulding process from an epoxy resin, typically NH64FR which is available from Elite Chemical Industries (Pty) Ltd. In this embodiment of the invention, the resin includes a colour tint for facilitating a red glow within the body  42 . 
   A rivet  44  connects a printed circuit board (PCB)  46  to the stem  18  of the battery housing so as to position six high-intensity or ultra high-intensity, red light emitting diodes (LEDs)  48  around the stem, as illustrated. The PCB  46  holds the LEDs  48  in desirable locations within the transparent body  42  and controls the flow of current to these LEDs. An important feature of the PCB  46  is that it includes six openings (not illustrated) along the periphery thereof for allowing the epoxy resin to flow through the PCB in one direction and for air to escape past the PCB in the opposite direction during moulding. 
   The PCB  46  is electrically connected to a second PCB  50  inside the battery chamber  20  via a wire  52 , and a plastics insulator  54  above the PCB  50  allows for charge separation. The PCB  50  provides a link between the wire  52  and a battery contact spring  56  and insulates the positive terminal of the battery  22  from the negatively charged battery housing  12 . 
   In the illustrated embodiment, the tapered portion  16  of the battery housing  12  acts as a diffuser for diffusing light emitted from the LEDs, thereby to illuminate the transparent body  42  to form a light source for identifying a person or object attached to the device. 
   In one application, the identifier  10  may be used to identify a scuba-diver under water. In this application, once the battery  22  has been loaded into the battery chamber  20  and the end cap  24  has been securely connected to the battery chamber, the switch member  36  is rotated into contact with the battery so as to close a circuit between the positive and negative terminals of the battery. With the circuit closed, current flows through the end cap  24 , the battery housing  12 , the rivet  44 , the PCB  46  and the LEDs  48 , and then back to the battery  22  via the wire  52 , the PCB  50  and the contact spring  56 . As light is emitted from the LEDs into the transparent body  42 , the light is diffused by the diffuser  16 , and is deflected, reflected and refracted in the manner illustrated in  FIG. 3  to produce a red glow within the body  42 . It should be appreciated that the glow in the body  42  is visible from all sides of the identifier  10 . The identifier is then connected to the diver&#39;s clothing or equipment by means of a connecting ring extending through the aperture  40  in the switch member  36  to identify the diver under water. 
   It will be appreciated that although the identifier has been described above with reference to a rotatable switch, the switch could be arranged to operate under pneumatic or hydraulic pressure. For example, the identifier may be connectable to a high/low pressure stage in a scuba system so that the switch activates upon the opening of the cylinder valve and is deactivated when the cylinder valve is sealed and depressurised. 
   It will also be appreciated that although the invention has been described above with reference to red LEDs, various other coloured LEDs, for example amber, blue or green, could be used. Furthermore, the LEDs could be arranged to emit white light or, for military applications, infra-red light, if desired. In other, non-illustrated embodiments of the invention, the LEDs are arranged to emit dual tones and/or to flash on and off. 
   Furthermore, it will be appreciated that apart from scuba-diving applications, the identifier  10  could be used in many other applications, for example as an identifier for people or objects in mining applications, military applications, emergency services applications, or recreational applications including fishing, cycling or mountain climbing after sunset or before sunrise. 
   In another, non-illustrated embodiment of the invention, the identifier  10  includes a rechargeable battery unit instead of the battery  22 . 
   A major advantage of the identifier according to the embodiment of the invention described above is that it is long-lasting and hence can be re-used a number of times. It is anticipated that the battery life will be at least 48 hours, and the detachable end cap  24  allows for the replacement of batteries, as required. Also, with the PCB  46  and the LEDs  48  embedded within the transparent body  42 , the identifier  10  is fairly robust. A further advantage of the identifier  10  is that it is relatively small and light, and consequently is easy to use.