Abstract:
In one embodiment, color sensors allow multiple data transfer channels to occur between a light source and a light detector. Light of differing wavelengths can be detected simultaneously and the modulated data on each wavelength can be independently and simultaneously processed. If desired, data from a selected wavelength can be delivered to an end-user. In another embodiment, different colors can be used for different directions of communication thereby allowing for simultaneous bi-directional communication.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to visual light communication systems and more particularly to systems and methods for increasing data communication bandwidth.  
       BACKGROUND OF THE INVENTION  
       [0002]     The use of infrared (IR) signals has become commonplace for transmitting line of sight information from one place to another. Such IR signaling is employed, for example, in hand-held controls used for turning television sets and other electronic devices on-off and for changing channels, volume control, etc. These devices are specially designed for communications there between and such communications, since they are in the IR band, are not meant for general purpose communications.  
         [0003]     Light in the visual range is now being investigated for communication purposes. Such systems, known as visual light communication (VLC) systems, use commonly available light sources, such as LED and LCD displays for communication purposes. Thus, a device that serves the purpose of displaying information (or even simply providing illumination) can also be simultaneously used to transmit information to one or more light receptacles. In a VLC system data is modulated onto the visible light coming from the light source and any detector (demodulator) that is in the path of the visible light can receive that data.  
         [0004]     As with most communication systems, the bandwidth soon fills thus limiting the data transfer rate between the light source and the light detector. If VLC systems are to become a source for data transfer to and from mobile devices, such as PDA&#39;s, computers, and the like, it is important that the data transfer bandwidth be as high as possible.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     In one embodiment, color sensors allow multiple data transfer channels to occur between a light source and a light detector. Light of differing wavelengths can be detected simultaneously and the modulated data on each wavelength delivered can be independently and simultaneously processed, and, if desired, selectively to an end-user.  
         [0006]     In another embodiment, different colors can be used for different directions of communication thereby allowing for simultaneous bi-directional communication.  
         [0007]     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:  
         [0009]      FIGS. 1A, 1B , and IC show various embodiments of one aspect of the inventive concept;  
         [0010]      FIG. 2  shows one embodiment of the system for one-way multi-channel communication; and  
         [0011]      FIG. 3  shows one embodiment of the system for bi-directional multi-channel operation. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]      FIG. 1A  shows system  10  in which electronic sign  11  displays information  110  to the viewing public. In this context, I will call such displayed information communally broadcast information. The light source(s) for electronic sign  11 , as will be discussed, can be modulated over various channels so that a specific message can be delivered over one channel to car  12 - 1  and a different message delivered to car  12 - 2 . A message in car  12 - 1  can be displayed, via display  13 - 1  with a first message while display  13 - 2  in car  12 - 2  could have a separate message. With each message being delivered using a different light color from light source  11  which forms a visual light communication system (VLC). It should be noted that the data, while displayed as slogan or information on a screen, in the example, could also be, for example, information for controlling the car or any other data desired to be transmitted. Also note that the display in a particular car could be “tuned” to receive different channels.  
         [0013]      FIG. 1B  shows one example of system  100  using the red ( 15 R), yellow ( 15 Y), and green ( 15 G) lights of traffic signal  14 , in which lights  15  are used in the conventional matter to control the flow of traffic. These lights, for example, could be comprised of a plurality of individual LEDs such that red light  15 R, yellow light  15 Y, and green light  15 G would each have perhaps 100 light emitting diodes (LEDs) similarly for yellow light  15 Y and for green light  15 G. If it is desired to communicate multi-channel information, one or more of the cluster of LEDs that comprise light  15 R can be modulated with data. This modulated light is demodulated by mobile device  12 - 1 , and the data displayed within the module device. Note that in  FIG. 1B  all three light sources ( 15 R,  15 Y, and  15 G) can be utilized to provide a three-channel system.  
         [0014]      FIG. 1C  shows still another embodiment using a television set (TV)  16  as a light source. TV  16  has displayed thereon image  160  which is the communal picture available to any viewer TV  16 . Each pixel of TV  16  is made up from these different color light sources red, green, and blue. The liquid crystal displays (LCDs) or other light sources within TV  16  can be individually modulated so that a remote display, such as display  17 , can receive information modulated on the visible light from TV  16 . For example, TV  16  could send three or more different channels of information, each channel serving a different purpose, with each channel using a separate color (frequency). This modulated data could be used for controlling other devices, or for displaying information, etc., all under control of TV  16 . Note that the modulation can be locally controlled or could be controlled via the signals provided to TV  16  from a remote source. Thus, a remote source can, in addition to providing the visual entertainment on TV  16 , provide control for various different electronic equipment, or various messages, in proximity to TV  16 .  
         [0015]      FIG. 2  shows one implementation  20  in which three data channels are utilized. Data on channel DATA  1  goes to modulator  21 R, while data on channel DATA  2  goes to modulator  21 G, and data on channel DATA  3  goes to modulator  21 B. These three modulators are associated with red, green, and blue light sources respectively, which are the three light sources available in this implementation. Note that while three modulators are shown, a single modulator could be utilized, for example, in a time multiplexed manner, if desired. Also note that the modulators are preferably digital modulators.  
         [0016]     The outputs of the modulators modulate the light of each driver independently such that red driver  22 R is modulated by data on input DATA  1 , green driver  22 G is modulated by data on input DATA  2 , while blue driver  22 B is modulated by data on input DATA  3 . The outputs of the drivers then drive the three light sources  23 B,  23 G and  23 R of light source  23 . Note that in the embodiment shown each light source  23 B,  23 G,  23 R is shown as a single source, but in reality each source can be a plurality of individual light sources, such as LEDs, LCDs, etc.  
         [0017]     Broken lines  24 B represent the modulated light from light source  23 B while broken lines  24 G represent the modulated light from source  23 G and likewise broken lines  24 R represent the modulated light from light source  23 R. This light is in the visual range and is detected, in one embodiment, by color sensor  26  which is a sensor utilizing filters.  
         [0018]     The output of color sensor  26 , which sensor could be on a color-by-color basis, or integrated for several colors, is separated with respect to the various light frequencies. Accordingly, blue modulated light is provided to demodulator  27 B, green modulated light is provided to demodulator  27 G, while red modulated light is provided to demodulator  27 R. The outputs of these three demodulators then recover the data from input DATA  1 , input DATA  2 , input DATA  3 . Note that device  13  can be a mobile device coming into proximity of light source  11  from time to time, or it can be stationary with respect to light source  11 .  
         [0019]      FIG. 3  shows system  30  which is one embodiment of a multi-directional system such that data coming in from high speed network  302  is provided to one or more of the blue, green, or red drivers  22 B,  22 G, or  22 R, respectively. Note that in this embodiment, modulator  201  can be a single modulator or could be three modulators as shown in  FIG. 2  and that any number of colors can be utilized. As discussed with respect to  FIG. 2 , color sensor  26  receives the modulated light in remote unit  17  and provides the individual outputs to demodulator  207 . Note that if only one color was utilized then only one color would be provided to demodulator  207 . However, in situations where there are multiple colors being utilized, all the modulated colors (or channels) can be provided to demodulator  207 . If desired, a selector, such as selector  302 , can be used to select or tune color sensor  26  to select which of the color(s) are provided to demodulator  207  (or to demodulators  27 B,  27 G,  27 R in  FIG. 2 ).  
         [0020]     Assuming one channel is selected in demodulator, that channel is provided to display input/output  18  for communal (or private) display to a user. The user could then input information via input/output  18  which data then is provided to modulator  31  and LED driver  32 . LED driver  32  then drives light source  33  having a specific color  34  which color is different from the colors currently being used for the direction from device  16  to device  17 . These selected colors can be on a permanent bases, such that, for example, yellow is always used from device  17  to device  16 , while red is always used from device  16  to device  17 .  
         [0021]     The system could also be set so that selector  302  determines which color is coming in the direction towards device  17  and then controls light source  33  so that a different color is used in the reverse direction. In any event, the color going from device  17  to device  16  is a different color than is used from device  16  to device  17  thereby allowing simultaneously transmitted bi-directional modulation. Color sensor  36  provides the proper color modulated light to modulator  37  which in turn provides the data from input/output  18  to high speed data network  302 . Note that high speed data network  301  is only necessary if, in fact, the information is to go beyond device  16 . In some situations, the information goes back and forth between device  16  and device  17  without need for delivery to any further destination.  
         [0022]     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.