Abstract:
A position dependent information retrieval system is disclosed including a light source having a driver and an encoder. The driver and the encoder are coupled to the light source so that the light source produces a modulated light signal in accordance with a predetermined signature. The system also includes a receiver having a photosensitive detector capable of detecting the modulated light signal and a decoder capable of decoding the predetermined signature. A controller is communicatively coupled to the receiver, a memory and output device. The controller is arranged to receive the decoded predetermined signature, based upon the decoded predetermined signature, obtain at least one localized message in the memory, and output the localized message using the output device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 10/029,805, filed Dec. 27, 2001, now U.S. Pat. No. 6,807,478. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains generally to the field of information retrieval systems, and in particular, the invention relates to an information system used to provide localized messages dependent upon the position inside a building, structure or location using, in part, existing artificial light sources. 
     BACKGROUND OF THE INVENTION 
     There are numerous instances where it is necessary to transmit a message of a localized nature to someone, and which needs to be updated on a regular but not instantaneous basis. Examples of such instances include promotions offered by a nearby store or mall, commentaries on pieces of art in a museum, or the nature, cost and location of sale items in a supermarket. Currently, information of a localized nature can be communicated in a number of ways. Foremost are signs with pictograms or reading material. However, signs require visual attention, which may distract the person the message is directed to. Signs may also be difficult to find in a visually cluttered environment. Another method is a sound broadcast. However, sound broadcasts by their nature are directed at everyone within a particular space. A sound broadcast also must be repeated over and over again, consequently requiring such broadcasts be kept relatively short. Sound broadcasts are typically used only for warnings or guided visits. 
     Another method is a device receiving the message in a wireless fashion, such as via infrared or radio frequency. The devices reconstruct the message in text or auditory format. This method requires an intelligent network of localized transmitters and can be costly to install and maintain. Infrared and radio frequency communications face other limitations as well. Infrared is strongly directional and positioning within the room is very important. Radio frequency (RF) is sensitive to interference from emitters in other locations or other RF devices. Compliance with the many RF regulations around the world creates additional costs for RF systems.
 
Another method is a portable device carried by a user which stores a number of messages in memory. For example, systems based on messages prerecorded on a tape player have been in use in museums for some years. They are advantageous because they provide a personalized experience for the user and are relatively simple and inexpensive to install and maintain since no networks are involved. However, they face a number of drawbacks. The user must specify his location to receive the relevant message, and he must visit the exhibits in a predetermined sequence since the messages are not randomly accessible. The action required from the user reduces the effectiveness of this method. Also the messages can not be readily altered. This system could be improved if the message corresponding to the user&#39;s location were automatically determined. Various approaches have been proposed to achieve this objective, such as ultrasonic or radio transmitters which function as location beacons. However, they suffer from interference and cost problems.
 
     Accordingly, there is a need for a position dependent information retrieval system that solves the shortcomings of the above described systems. 
     BRIEF SUMMARY OF THE INVENTION 
     One aspect of the present invention uses the existing lighting infrastructure (e.g., fluorescent lamps and fluorescent lamp drivers) in a building or structure to form a position dependent information retrieval system. Light intensity can be modulated to carry a message. The modulation can be performed at a high frequency such that its effect on the light intensity as perceived by humans is null. Light sources are ideal since by their nature they are localized to a room and less susceptible to interference. This arrangement typically does not require any additional infrastructure cost. The lighting infrastructure may be any type of light source (e.g., fluorescent, halogen or incandescent light sources). The building or structure can be any type of house, office, arena, complex or location that include some sort of artificial lighting. 
     Thus the artificial light in a room can be used to transmit a coded message that is unique at each position within the building and that can be detected by a portable device. The unique code for each light source can be fixed at the factory and can remain fixed for the life of the product. The existing lighting infrastructure within the building, in addition to providing illumination as its primary function, can be used to create a constellation of such light beacons. Each light beacon would not need to receive input data and consequently would not need to be tied to a network. This would keep the cost of implementation and operation very low. 
     A small portable device could be used to deliver localized messages which are automatically retrieved from internal memory, and which would correlate to various locations. The devices could either display the message on a small screen, such as those on a personal digital assistant (PDA), or be synthesized to speech and delivered to the user through headsets. This frees the user from the distraction of manually having to enter her location. In addition, the messages can be retrieved in any order so the user is free to choose any random route to follow through the building. The messages would also be easily updated on a regular basis by passing the receiver near a transmitter located at a central location, such as the entrance to a building. An input for user preferences and interests can also be provided (e.g. a keypad), so that a user specific profile can be stored in memory to further filter messages associated with particular locations. 
     Various embodiments of the invention can be used to add a position dependent information retrieval system within a building. Application examples of this invention include:
         Receiving commentaries while walking though a museum;   Receiving promotions offered in supermarkets;       

     One embodiment of the present invention is directed to a position dependent information retrieval system used inside a building, structure, arena or location. Light sources are used as beacons to transmit unique codes by modulating their light output. The transmitted codes are decoded by an optical receiver and are used in combination with a table of associations stored in the receiver to provide position dependent information to the user within a building (e.g., mall, museum or airport). 
     In one embodiment, an information system includes a light source having a driver and an encoder. The driver and the encoder are coupled to the light source so that the light source produces a modulated light signal in accordance with a predetermined signature. A receiver is provided having a photosensitive detector capable of detecting the modulated light signal and a decoder capable of decoding the predetermined signature. A controller is communicatively coupled to the receiver, a memory and an output device. The controller is arranged to receive the decoded predetermined signature. Based upon the decoded predetermined signature, the controller obtains at least some information stored in the memory and outputs the information using the output device. 
     In another embodiment, an optical receiver is provided for operation with the information retrieval system. 
     Yet another embodiment is directed to an information retrieval system including means for producing a light signal having a signature, means for decoding the signature from the light signal and means for providing a localized message in accordance with the signature. 
     These and other embodiments and aspects of the present invention are exemplified in the following detailed disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The features and advantages of the present invention can be understood by reference to the detailed description of the preferred embodiments set forth below taken with the drawings, in which: 
         FIG. 1  is a conventional lighting system with data transmission capability. 
         FIG. 2  is a light encoding system in accordance with one aspect of the invention. 
         FIG. 3  is a block diagram of an optical receiver in accordance with one embodiment of the invention. 
         FIG. 4 . is a block diagram illustrating an exemplary application of a position dependent information retrieval system in accordance with another embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Referring now to  FIG. 2 , a information system  10  is shown, which includes a driver  11 , a light source  12  and a power source  13 . The driver  11  includes an encoder  14  for encoding a unique code  15  which is transmitted by modulating light emitted from the light source  12 . In this way, the light is modulated to have a signature in accordance with the unique code  15 . The light source  12  and the driver  11  may be supplied (from a manufacturer) with the unique code  15 . The unique code  15  may also be programmable via an interface  16 . The interface may be a data input port or a wireless data interface (e.g., infrared or radio-frequency (RF)). 
     A plurality of light encoding systems  10  each would have a different unique code  15  associated therewith. The unique code  15  may consist of a plurality of bits. The number of bits is chosen to be high enough to ensure at least that in practice no two installed light encoding systems  10  in a building share the same unique code  15 . Various alternative formats may be used for the unique code  15 . The following are examples of possible unique codes  15  and are not intended to be limiting: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 00h through 0fh: 
                 provides 16 unique (hexadecimal) codes 
               
               
                 XYh: 
                 where X (0 through f) is a region designation 
               
               
                   
                 and Y (0 through f) is a light source designation 
               
               
                   
                 within each region 
               
               
                 aabbcccc (binary) 
                 where aa represents a location classification 
               
               
                   
                 (e.g., mall, office), bb represents a floor number 
               
               
                   
                 and cccc represents a light source designation within 
               
               
                   
                 a particular location and on a particular floor. 
               
               
                   
               
             
          
         
       
     
     The unique code  15  may be transmitted/modulated at regular intervals, e.g., once per second, or only at specific times as needed. In the case of the regular intervals of once per second, the transmission bit-rate of the unique code  15  can be very low, for instance 200 bits/second (which is not visible to the human eye). This bit rate simplifies the design of a receiver  20  and reduces its power consumption. The transmission of data in the previous art typically requires a much higher bit-rate. Also it is generally easier to modulate the light output at a lower frequency. Alternatively, the unique code  15  may only be transmitted/modulated when prompted by an external trigger. The trigger may be an input received via the interface  16 . The input may be from the receiver  20  (discussed below). 
     It is also noted that the light encoding system  10  does not need to receive any input data to transmit. As discussed above, the unique code  15  is predetermined/programmed for the light source  12 . Therefore there is no need to tie all light sources into a network as prior art systems require. It is also noted that no regulations are imposed on light emissions or the modulation of light emissions from lighting sources. 
     A block diagram of the receiver  20  in accordance with one embodiment is shown in  FIG. 3 . The receiver  20  includes a photosensitive detector  21  to detect the modulated light signal  22  and a decoder  23  to extract the unique code  15  from the modulated light signal  22 . The unique code  15  is associated with a location of the light source  12  in a table of associations  24  of the building stored in a memory  25 . Using the unique code  15  from one or more light sources  12  and the table of associations  24 , the appropriate pre-stored message can be selected. Based upon the selection, the message can be played back or displayed via the output device  27 . 
     One difference between the present invention from the conventional systems using light output modulation to transmit data is the use of the memory  25  to store messages instead of having to transmit a large amount of information related to a particular location. The modulated light only needs to include the unique code  15 . The unique code  15  is used to retrieve the relevant information from the memory  25 . The overall processing of unique code  15  and localized message is performed by a CPU  26  or controller. 
     The CPU  26  may also include a communication interface, a memory interface, a CD-ROM drive interface and a video interface (not shown). The CPU  26  comprises a microprocessor or the like for executing computer readable code, i.e., applications, such as those noted above, out of the memory  25 . Such applications may be stored in memory  25  or, alternatively, on a floppy disk in disk drive or a CD-ROM in a CD-ROM drive. The CPU  26  accesses the applications (or other data) stored on a floppy disk via the memory interface and accesses the applications (or other data) stored on a CD-ROM via CD-ROM drive interface. 
     As noted above, the functions of the system  10  are implemented by computer readable code executed by a data processing apparatus. The code may be stored in a memory within the data processing apparatus or read/downloaded from a memory medium such as a CD-ROM or floppy disk. In other embodiments, however, hardware circuitry may be used in place of, or in combination with, software instructions to implement the invention. These functions/software/hardware may be formed as part of the receiver  20  or be an adjunct unit. The invention, for example, can also be implemented on a Personal Digital Assistant, laptop computer, a cellular telephone or the like. 
     The receiver  20  also includes an output device  27 . The output device  27  may include a variety of audio and visual units. The output device may also be a separate unit coupled to the CPU  26 . For example, the output device  27  may be a personal computer or a cellular phone. 
     The receiver  20  may also include an input unit  28 . The input unit  28  may comprise a variety of conventional data input devices. For example, the input unit  28  may be a keyboard, push buttons, a touch pad, a mouse, a voice recognition unit or the like. Using the input unit  28 , a user of the information retrieval system  10  can enter data such as a user preference. Using the input information, the CPU  26  will use the user preference to further filter/modify the specific messages to the user on the output device  27 . 
     The receiver  20  may also be able to communicate to one or more of remote devices  29  over a network  30 . The network  30  may be a global computer communications network such as the Internet, a wide area network, a metropolitan area network, a local area network, a cable network, a satellite network or a telephone network, as well as portions or combinations of these and other types of networks. The network  30  may be accessed by the receiver  20  through wired connections, wireless connections or combinations thereof, using well-known conventional communication protocols such as the Internet Protocol (IP). 
     As shown in  FIG. 3 , the table of associations  24  and associated localized messages may be located at the remote site  29 , e.g., a web server. The remote site  29  may include a data storage device that stores any type of multimedia information related to the table of associations  24  and associated localized messages. The data storage may be any suitable storage medium such as audio/video cassettes, digital audio tapes (DAT), laser discs, DVDs, and the like. 
       FIG. 4  a block diagram illustrating an exemplary application of the information retrieval system  10 . In this example, a first piece of artwork  40  and a second piece of artwork  50  are located in a museum  60 . A plurality of light sources  61 – 68  is located throughout the museum  60 . A person  70  located near light source  64  using the receiver  20  would receive a message concerning the piece of artwork  40 . A person  70  located near the light source  67  would receive a message concerning the second piece of artwork  50 . 
     While the present invention has been described above in terms of specific embodiments, it is to be understood that the invention is not intended to be confined or limited to the embodiments disclosed herein. On the contrary, the present invention is intended to cover various structures and modifications thereof included within the spirit and scope of the appended claims.