Abstract:
An infrared beacon assembly includes a light source removeably attachable to lighting fixtures that supply electrical power. A voltage converter is connected to the light source to provide a reduced supplied voltage. The infrared beacon broadcasts a data signal.

Description:
FIELD OF THE INVENTION 
     The present invention relates to use of infrared beacons for locale identification. More particularly, the present invention relates to infrared beacons embedded in light fixtures to enable navigation and coordination of portable computing equipment. This application relates to U.S. application Ser. No. 09/477,876, filed Nov. 23, 1999 concurrently herewith. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Low cost portable computing devices such as handheld or palm-sized computers are widely available. Such devices can support local communication between nearby computers, or more generally can support wireless network or internetwork communications. Users equipped with suitable portable computers can, for example, exchange e-mail, browse the web, utilize mapping software, control nearby computer peripherals (e.g. printers), or receive information from local devices (e.g. job status of a printer). As will be appreciated, flexibility and utility of various applications can be enhanced if the precise spatial location of the portable computing device is known. Knowing the location of the portable computing device (with a precision of several meters or so) permits construction of user specific maps, transfer of location information to others, and receipt of location information for nearby computational or real world resources (e.g. answering such questions as “where is the nearest printer” or “where is the nearest coffeeshop”). For this reason, having easily determinable and reliable position information is a useful feature. 
     However, spatial localization with low cost devices can be difficult. Devices incorporating Global Positioning System (GPS) receivers often do not work indoors because of poor radio reception and can require a substantial amount of time to determine position with a required accuracy. In many areas, there may not be any differential GPS availability to gain the necessary meter level precision for greatest utility. Other wireless schemes for localizing spatial position are generally not sufficiently precise (e.g. digital cellular telephone service areas with 1000 meter errors), or too expensive (inertial navigation systems). 
     SUMMARY OF THE INVENTION 
     According to the present invention, one solution for determining spatial location is based on low cost infrared equipped devices and infrared beacons. Outdoor situated infrared beacons that broadcast a unique identification number can be precisely located outdoors using differential GPS in a one-time procedure. Indoor situated infrared beacons that broadcast a unique identification number can be precisely located indoors using architectural plans in combination with accurate survey maps or external GPS of the building. Relative location of infrared beacons is even simpler. For example, each room in an office building can be equipped with a unique identification number, and geographic references are made with respect to room numbers rather than x,y,z absolute position. In any case, whether absolute or relative positioning is used, the location information is linked to the unique identification number available over the Internet or through local database spatial localization services. In operation, a portable computing devices equipped with an infrared receiver can receive the data signal from the infrared beacon, enabling high precision determination of physical location both indoors and outdoors. In certain embodiments, a GPS receiver integrated with a portable computer can be used to roughly determine location, with more precise positioning being handled by reference to infrared beacons. 
     In preferred embodiments, an infrared beacon is integrated into convention incandescent, fluorescent, or high intensity discharge lamps (e.g. metal halide, high or low pressure sodium lamps) suitable for indoor or outdoor usage. The infrared beacon includes a light source removably attachable to lighting fixtures that supply electrical power at a determined voltage and a voltage converter electrically and physically connected to the light source to provide a reduced supplied voltage. For indoor usage, electrical power is typically supplied at 110 Volts AC, and is converted to less than 5 or 6 volts DC by the voltage converter. Outdoor power supplies are often higher (220 Volts AC or greater), and power supplied by the voltage converter may also be slightly higher. 
     In operation, the infrared beacon, powered by the voltage converter, continuously, intermittently, or in response to an interrogatory signal, broadcasts a data signal. This data signal can be predetermined, and is typically a series of infrared pulses adhering to Infrared Data Association (IrDA standards. In certain embodiments, a microcontroller and oscillator are attached to trigger the microcontroller to initiate the electrical pulse train resulting in broadcast of the data signal. Alternatively, a special trigger circuit responsive to infrared, optical, physical (e.g. pushbutton or switch), or radiofrequency input can be used, alone or in combination with a microcontroller or oscillator circuit, to initiate broadcast of the data signal. 
     Additional functions, objects, advantages, and features of the present invention will become apparent from consideration of the following description and drawings of preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically illustrates usage of embedded infrared beacons in outdoor and indoor environments with the aid of a portable computer equipped with both infrared and radio transceivers; 
     FIG. 2 shows an infrared beacon embedded in an incandescent light bulb; 
     FIG. 3 shows an infrared beacon embedded in a fluorescent light bulb; 
     FIG. 4 is a schematic illustrating construction of an infrared beacon; and 
     FIG. 5 is a schematic illustrating construction of an infrared beacon capable of providing alternative data streams. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As seen in FIG. 1, a high precision positioning system  10  for determining spatial location can utilize a low cost infrared equipped portable computing device  20 , lightpole  14  mounted outdoor infrared beacons  16 , or ceiling  13  mounted indoor infrared beacons  18  to provide location specific information to a user. In operation, infrared beacons that broadcast a unique identification number are precisely located using, for example, differential GPS in a one-time procedure. The location information linked to the unique identification number is available over the Internet or through local database spatial localization services. A cellular or radio system  12  including broadcast tower  32  and connection to internet or computing services (box  30 ) can support such wireless transmission to wireless receiver  24  on portable computing device  20 . A user with the portable computing device  20  equipped with an infrared receiver  26  can receive the data signal from the infrared beacons  16  or  18 , enabling high precision determination of physical location both indoors or outdoors. Mapping software displayable on a screen  22  can be optionally used to assist in spatial locating or tracking. As will be appreciated, in certain embodiments, a GPS receiver integrated with the portable computer  20  can be used to roughly determine location from differential GPS transmitters, with more precise positioning being handled by reference to infrared beacons. 
     In preferred embodiments, an infrared beacon is integrated into convention incandescent, fluorescent, or high intensity discharge lamps (e.g. metal halide, high or low pressure sodium lamps) suitable for indoor or outdoor usage. The infrared beacon includes a light source removably attachable to lighting fixtures that supply electrical power at a determined voltage. Advantageously, integration of an infrared beacon for use in ceiling mounted conventional lighting fixtures generally assures that the beacon signal information is readily available indoors, since such lights are optimally located to direct light to all parts of a room. In operation, the infrared beacon continuously, intermittently, or in response to an interrogatory signal, broadcasts the data signal. This data signal can be predetermined, and is typically a series of infrared pulses adhering to IrDA standards. In certain embodiments, a microcontroller or and oscillator are attached to trigger the microcontroller to initiate the electrical pulse train resulting in broadcast of the data signal. Alternatively, a special trigger circuit responsive to infrared, optical, physical (e.g. pushbutton or switch), or radiofrequency input from portable computing device  20  can be used, alone or in combination with a microcontroller or oscillator circuit, to initiate broadcast of the data signal. 
     As will be appreciated, conventional lighting fixtures will readily support infrared beacons in accordance with the present invention. For example, as seen in FIG. 2 shows an infrared beacon assembly  18  having an infrared beacon  44  embedded in an incandescent light bulb  40 . A lighting element  42  provides incandescent lighting, while the infrared beacon  44  can provides data signals. Similarly, FIG. 3 shows an infrared beacon  54  for providing data signals embedded in a fluorescent light bulb  50 . 
     As seen in FIG. 4, an infrared beacon assembly  60  is powered by an alternating current power supply  62  (typically household current) that also powers a conventional lamp  64  for producing incandescent or fluorescent light  65 . The beacon assembly  60  has a voltage transformer  66  that can convert input electrical power to the low direct current and low voltages required by a conventional infrared LED  74  for emitting an infrared data signal  75  as directed by a combination of controller  68 , oscillator  70  and buffer  72 . 
     The voltage transformer  66  generally converts a 110 volt alternating current to less than 10 volts direct current, with 3-6 volts DC being typically required for most applications. Conventional transformers or switch mode devices can be used. Since power consumption of the infrared beacon assembly  60  is on average on the order of 50 mW (although peak power may be substantially greater), heating effects in the transformer are negligible. In certain alternative embodiments, the lamp  64  can be used as a dropper resistor, with a small resistor being placed in series with the lamp  64 . Voltage across this series resistor can be fed into a voltage regulator circuit to provide a stable current supply when the lamp  64  is turned on. 
     The controller  68  can be implemented with analog circuitry, with a general purpose microcontroller, or with an ASIC FSM. Typically, a four bit processor or dedicated ASIC is used to send a repeating stream of unique identifying pulses to the buffer  72 , with the pulse sequence representing a globally or locally unique identification number. Alternatively, the pulse sequence can provide information in addition to identification, including sensor data (e.g. temperature) or informational details about an area (e.g. street number, enhanced location information). In preferred embodiments, the pulses comply with IrDA connectionless packet layout, to simplify recognition and interpretation by IrDA computing devices. 
     The repetition rate of controller  68  is optionally directed by oscillator  70 . For example, an oscillator with a period of 10 seconds can be used to trigger the controller  68  to wake-up and initiate a pulse train fed to buffer  72  (which can be a simple FET or other suitable device). Each pulse is used to drive current to the IR LED  74  to emit data signal  75 . 
     An alternative embodiment capable of providing various infrared data streams  97  or  98  in response to specific triggers is schematically illustrated in FIG.  5 . Similar to the embodiment of FIG. 4, an infrared beacon trigger assembly  80  is powered by an alternating current power supply  82  (typically household current) that also powers a conventional lamp (not shown) for producing incandescent or fluorescent light. The power supply  82  of the beacon trigger assembly  80  has a voltage transformer that can convert input electrical power to the low direct current and low voltages required by a conventional infrared LED  96  for emitting an infrared data signals  97  or  98  as directed by a combination of controller  84 , oscillator  85  and buffer  94 . 
     Unlike the embodiment of FIG. 4, the infrared beacon trigger assembly  80  further includes a trigger circuit  86 . The trigger circuit can be optionally activated by a radio signal  87 , sensor input  88  (e.g. physical user triggered switch, pressure or motion sensor, light sensor), or user directed light beam  89  (e.g. infrared or optical laser). Depending on trigger conditions, data stream A (box  90 ) or data stream B (box  92 ) can be converted by controller  84  into a pulse train for broadcast respectively as data signals  97  or  98 . As will be appreciated, the data signals can be identification numbers, location information, information specific to a geographic locale, time dependent information (e.g. weather/temperature conditions for site) or any other desired data broadcast. 
     As those skilled in the art will appreciate, other various modifications, extensions, and changes to the foregoing disclosed embodiments of the present invention are contemplated to be within the scope and spirit of the invention as defined in the following claims.