JP4610511B2 - Visible light receiving apparatus and visible light receiving method - Google Patents

Description

  The present invention relates to a visible light receiving apparatus and a visible light receiving method capable of receiving data by selecting from a plurality of visible light communication light sources.

  In recent years, research and development of visible light communication that communicates in the visible light region using a visible light source such as illumination light or LED and a light receiving element such as a photodetector has been promoted, traffic lights, car brake lamps, office lighting, Various application uses such as an electric bulletin board at a station are considered. The communication speed depends on the response speed of an LED used as an illumination light source or a photodetector as a light receiving element, S / N, etc., but a throughput of several Mbps (bits / second) or more is also obtained. Infrared light communication using infrared light is a similar technology. However, visible light communication is a communication that uses a visible light so that the light source is visible to the human eye, so that the transmitting device can be immediately identified. There are advantages such as easy-to-understand areas that can be used, and wide application range because it can replace lighting in the world as it is.

  In addition, there is a technique that uses an imaging device such as a mobile phone as a light receiving device other than the photodetector (Patent Document 1). According to this, when the light emission source in the area where the image is captured by the imaging unit blinks in a specific pattern, pattern matching of the light emission pattern of the light source is performed from a plurality of image signals arranged in the time axis direction, There has been proposed an image processing apparatus having a step of specifying a light emitting area and a step of pasting an arbitrary image at the specified position. Thus, for example, by continuously photographing the light source with a camera of a mobile phone or the like, the light source on the screen can be specified and data can be extracted.

Patent Document 2 uses infrared communication technology and a camera to capture the position of an infrared communication light source that cannot be confirmed by the human eye with a camera that covers the infrared wavelength region, confirms the location, and directs the user to the light source. It guides you through infrared communication.
JP 2002-262180 A JP 2004-011226 A

  When an imaging device such as a cellular phone is used as the light receiving device as in Patent Document 1, the data rate depends on the frame rate of the imaging unit of the camera, and a frame is not obtained with a CMOS camera or the like mounted on the cellular phone. The rate is about 30 fps (frames / second). In this case, since the data rate can be obtained only at a maximum of 30 bps or less, it is difficult to handle large data. When a CMOS camera or a CCD camera is usually incorporated in a portable device, a camera of about 30 fps is used. A high-speed CMOS camera of several hundred fps has also been realized, but it is expensive, and about 30 fps is sufficient for recording a moving image on a portable device. This is because, since the (aperture value) is large, it is necessary to increase the amount of light by extending the exposure.

  In the case of Patent Document 2, when a camera is used only for specifying the position of an infrared communication source and a plurality of light sources are within an area photographed by the camera, an arbitrary one is selected on the screen. Communication is not possible, and the user must approach the area of infrared communication.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a camera with an inexpensive combination of an imaging unit of a camera with a low frame rate and a light receiving unit used for visible light communication. An object of the present invention is to provide a visible light receiving apparatus and a visible light receiving method capable of receiving data from any one light source in an imaged area.

  In order to achieve the above object, a visible light receiving apparatus according to the present invention includes a photographing means for photographing a subject, a light receiving means for receiving light emitted from a light source and obtaining a coded signal, and the light receiving means. An acquisition unit that acquires a code for decoding the encoded signal from the light source by the photographing unit, and a coded signal acquired by the light receiving unit using the code acquired by the acquisition unit And a decoding means.

  Further, the display device further includes a display unit that displays the subject photographed by the photographing unit in real time, and a selection unit that selects a light source from the subject displayed by the display unit, and the decoding unit includes the light source selected by the selection unit. It is preferable to decode the encoded signal obtained by the light receiving means using a code.

  Further, the display device further comprises storage means for storing the decoded signal, and when the light source is selected by the selection means, the decoded signal stored in the storage means corresponding to the light source selected by the selection means is displayed. It is preferable to display on the means.

  In addition, the visible light receiving device of the present invention includes a photographing unit that photographs a subject, a light receiving unit that receives light emitted from a light source and obtains a signal, and a light receiving timing for obtaining a signal by the light receiving unit. The image processing apparatus includes an acquisition unit that acquires from the light source by an imaging unit, and a setting unit that sets a timing at which the light receiving unit acquires a signal using the light reception timing acquired by the acquisition unit.

  The display unit further includes a display unit that displays a subject photographed by the photographing unit in real time, and a selection unit that selects a light source from the subject displayed by the display unit. The setting unit includes a light source selected by the selection unit. It is preferable to set a timing at which the light receiving unit acquires a signal using a light receiving timing.

  In addition, the visible light receiving method of the present invention is a method for receiving a light emitted from a light source by a light receiving means and obtaining an encoded signal, and for decoding the encoded signal obtained by the light receiving means. Including a process of acquiring a code from the light source by an imaging unit that images a subject, and a process of decoding the encoded signal acquired by the light receiving unit using the code acquired by the imaging unit. To do.

  Further, the visible light receiving method of the present invention includes a process for obtaining a signal by receiving light emitted from a light source by a light receiving means, and a light receiving timing for obtaining a signal by the light receiving means, and a photographing means for photographing a subject. And a process of setting a timing at which the light receiving unit acquires a signal using a light receiving timing acquired by the photographing unit.

  The present invention receives data from an arbitrary light source in an area photographed by a camera by an inexpensive combination of an imaging unit of a low-frame-rate camera used for a mobile phone and a light-receiving unit used for visible light communication. be able to.

  Embodiments of the present invention will be described with reference to the drawings. The visible light communication system includes a visible light receiving device that receives data and a transmitter that transmits data. FIG. 1 is a block diagram of a visible light receiving apparatus according to the present invention. The visible light receiving apparatus 1 includes an imaging unit 2, a light source detection unit 3, a low speed data demodulation unit 4, an operation unit 5, a light receiving unit 6, a high speed data demodulation / decoding unit 7, a synchronization acquisition unit 8, The storage unit 9, the control unit 10, and the display unit 11 are configured.

  The imaging unit 2 is an imaging unit that captures a subject. The imaging unit 2 uses a CMOS or a CCD as an imaging element to capture at a low frame rate (here, 30 fps (frame / second)), and detects the captured image as a light source. To the unit 3 and the control unit 10. The light source detection unit 3 detects the visible light communication light source from the temporal change of the image captured by the imaging unit 2 and notifies the low-speed data demodulation unit 4, and if the light source is not detected, the frame of the imaging unit 2 The detection of the light source is continued while shifting the timing by a predetermined time. When the low-speed data demodulator 4 receives a notification from the light source detector 3 that there is a visible light communication light source, the low-speed data demodulator 4 demodulates the data from the blinking pattern of the light source, and outputs the demodulated data to the controller 10 for control. The unit 10 stores in the storage unit 9. The demodulated data is a code necessary for decoding by the high-speed data demodulating / decoding unit 7. The display unit 11 displays image data output from the control unit 10 and data acquired from icons, buttons, and light sources operated by the operation unit 5. The light receiving unit 6 includes a photodiode and a photodetector, receives light from the visible light communication light source, and outputs the light to the high-speed data demodulation / decoding unit 7. The high-speed data demodulation / decoding unit 7 decodes data based on the data received by the low-speed data demodulation unit 4 with respect to the received light received by the light receiving unit 6. The synchronization acquisition unit 8 performs synchronization acquisition and synchronization maintenance so that the timing is appropriate when the high-speed data demodulation / decoding unit 7 multiplies the codes.

  FIG. 2 is a block diagram of the transmitter. The transmitter 20 includes a storage unit 21, a control unit 22, a low-speed data input unit 23, a high-speed data input unit 24, an encoding / modulation unit 25, and an LED (visible light communication light source) 26.

  The storage unit 21 stores data to be transmitted and data used by the receiving device for decoding. The control unit 22 outputs data to be transmitted to the receiving device to the high-speed data input unit 24, and outputs data used by the receiving device to decode the high-speed data to the low-speed data input unit 23. The low-speed data input unit 23 and the high-speed data input unit 24 output data input at predetermined timings to the encoding / modulation unit 25, respectively. The encoding / modulating unit 25 encodes the data input from the high-speed data input unit 24 and modulates the input data so that the LED 26 blinks at a predetermined timing (described later). Output to LED26. The LED 26 blinks the LED as modulated by the encoding / modulating unit 25 and transmits data.

  Here, the first method for receiving data from one light source when there are two light sources will be described. FIG. 3 is a diagram for explaining a first method for selecting one of two light sources (light source A and light source B). Both the light source A and the light source B are low-speed data (binary PPM (pulse position modulation) of 15 bps), and high-speed data (PPM in which 1 Mbps data is spread with a code of 16 symbols) shown in FIG. The case where it is superimposed is shown. The high-speed data is transmitted while the LED is lit in the low-speed data PPM. High-speed data is binary PPM at a speed of 16 Msps (symbol / second) because data of 1 Mbps is spread with a code of 16 symbols, and the LED is turned on and off at 32 MHz, so high-speed data is being transmitted. In the meantime, it is determined that the light source is turned on in the imaging unit of about 30 fps.

3 (1) shows a transmission pattern of low-speed data of the light source A, and FIG. 3 (2) shows a transmission pattern of low-speed data of the light source B. Binary PPM is used, and is “0” when the first half is lit and “1” when the second half is lit. Further, “0101” is set as a flag indicating the head and tail of the data. The low-speed data demodulating unit 4 detects the flag from the light sources A and B photographed by the imaging unit 2 and acquires the data between them as a decoding code. A code W ₃ ¹⁶ = “0011110000111100” is acquired from the light source A, and a code W ₆ ¹⁶ = “0110011001100110” is acquired from the light source B. Here, a Walsh code having a symbol length of 16 is used as the spreading code.

The light receiving unit 6 receives light from both the light sources A and B at the same time, and receives light as a result of superposition. On the other hand, the high-speed data demodulating / decoding unit 7 despreads W ₃ ¹⁶ at a predetermined timing (takes an exclusive OR) to decode the data from the light source A and only the data from the light source A. Can be acquired. Here, the predetermined timing is the timing captured by the synchronization capturing unit 8, and the synchronization capturing unit 8 captures the timing at which data can be appropriately acquired while shifting the timing of despreading, and then maintains the timing by holding it. It will be. Similarly, data from the light source B can be acquired by performing despreading at the timing at which the synchronization capturing unit 8 captures and holds the signal with W ₆ ¹⁶ .

  Although the symbol length is 16 here, the data rate is slowed by increasing the symbol length. However, more light sources can be separated. For example, when the symbol length is 64, the theoretical number is 64. Even if there are about 50 light sources in the photographing area, it can be dealt with.

  Even when the light receiving unit moves during reception due to camera shake or the like, data can be received from the target light source without any problem as long as the light receiving unit is within a range capable of receiving the light source as shown in FIG. FIG. 4 is a diagram illustrating the positional relationship between the light sources A and B and the light receiving unit.

  It can be seen that data can be received from a specific single light source at high speed even when a plurality of light sources are within the range photographed by the camera by the above processing.

  FIG. 5 is a flowchart for explaining the operation of the control unit of the visible light receiving device, FIG. 6 is a diagram showing a bus stop for explaining an example of use, and FIG. 7 is a timetable display of the bus stop. It is a figure which shows the case where one specific timetable (here Akasaka) is downloaded from several timetables on a board.

  When the user turns on the camera by turning the camera to a part of the bus stop (FIG. 6), which is a visible light communication source (step 31), the light source detection unit 3 is visible in the area captured by the imaging unit 2. It is determined whether there is an optical communication light source (step 32). If there is a light source, the display unit 11 displays that there is a visible light communication light source (step 33). FIG. 7A shows a screen in which a bus timetable is displayed by a camera, and shows that there are four visible light communication light sources in the photographing area by highlighting the light source portion. Next, it is determined whether or not there are two or more visible light communication light sources (step 34), and when there are two or more light sources, it waits for the user to select one of the light sources by key operation (step 35). When the user selects one of a plurality of light sources by key operation (when Akasaka is selected in FIG. 7 (2)), or when there is only one visible light communication light source in step 34, the low-speed data demodulator 4 Acquires the data necessary for decoding (the diffusion code of the Akasaka light source) from the selected visible light communication light source (step 37), and stores it in the storage unit 9. Subsequently, it is determined whether or not the download button has been pressed by the user (step 38). When the download button is pressed (when the DL button in FIG. 7 (2) is pressed), the light receiving unit 6 is activated. Light reception starts, and the high-speed data demodulation / decoding unit 7 decodes the data from the selected light source using the decoded data stored in the storage unit 9, downloads it, and obtains Akasaka timetable data (FIG. 7). (3)) is stored in the storage unit 9 and displayed on the display unit 11 (step 39).

  As described above, the user can receive only Akasaka timetable data from the four light sources.

  Here, the download starts after the user presses the download button. However, a temporary buffer is provided, and when the light source is detected by the imaging unit and the codes can be acquired, the high speed encoded from all the light sources is obtained. If the data is decoded, the data obtained by decoding is temporarily stored in a temporary buffer, and the corresponding data is displayed immediately when the user selects the light source, the time is shortened for the user. Become.

  FIG. 8 is a diagram showing a transmission pattern when the title of the light source is included in a part of the low-speed data of the light source. By including the title of the light source in a part of the low-speed data, as shown in FIG. 9, the title can be displayed so as to be easily understood by the user by overlapping the title with the light source. FIG. 9 (1) is a diagram when the title “Bus Stop Kasuga” is displayed by selecting the light source on the stop name display plate at the top of the time table display plate, and FIG. 9 (2) is the time table display plate. Fig. 9 (3) shows the title of "Destination Akasaka" by selecting the Akasaka light source from the timetable display board. FIG.

  Next, a second method for receiving data from one light source when there are two light sources will be described. In the processing described above, the light source is separated by the code and the signal is received from the light source. However, the light source can be separated by time division and the signal can be received from the light source. FIG. 10 is a diagram for explaining a second method of selecting one from two light sources (light source A and light source B). The light source A and the light source B have different data transmission timings. When the imaging unit 2 receives the low speed data “0000” from the light source A in the time slots 0 to 3, the light receiving unit 6 next receives the high speed data in the time slots 4 to 7. When the imaging unit 2 receives the low speed data “0000” from the light source B in the time slots 4 to 7, the light receiving unit 6 next receives the high speed data in the time slots 8 to 11.

  As described above, when the imaging unit 2 receives the low speed data “0000”, the light receiving unit 6 receives the high speed data for the same time and then receives the low speed data. Even when the light source is within the range photographed by the camera, data can be received at a high speed from one specific light source.

  As described above, the present invention provides a light receiving unit for visible light communication in addition to a CMOS camera of about 30 fps mounted on a normal mobile phone without mounting expensive equipment such as a high-speed CMOS camera. With a simple configuration, even when there are a plurality of visible light communication light sources, data can be received from one specific light source selected by the user.

It is a block diagram of the visible light receiver of this invention. It is a block diagram of a transmitter. It is a figure explaining the 1st method of selecting one from two light sources (light source A and light source B). It is a figure explaining the positional relationship of the light sources A and B and a light-receiving part. It is a flowchart explaining operation | movement of the control part of a visible light receiver. It is a figure explaining an example of use. It is a figure explaining an example of use. It is a figure which shows the transmission pattern when the title of a light source is included in a part of low-speed data of a light source. It is a figure explaining an example of use. It is a figure explaining the 2nd method of selecting one from two light sources (light source A, light source B).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Visible light receiver 2 Imaging part 3 Light source detection part 4 Low-speed data demodulation part 5 Operation part 6 Light-receiving part 7 High-speed data demodulation / decoding part 8 Synchronization acquisition part 9 Storage part 10,22 Control part 11 Display part 20 Transmitter 21 Storage Unit 23 Low-speed data input unit 24 High-speed data input unit 25 Encoding / modulation unit 26 LED (visible light communication light source)

Claims (7)

Photographing means for photographing the subject;
A light receiving means for receiving the light emitted by the light source and obtaining an encoded signal;
An acquisition means for acquiring from the light source the code for decoding the encoded signal acquired by the light receiving means;
Decoding means for decoding the encoded signal obtained by the light receiving means using the code obtained by the obtaining means;
A visible light receiving device comprising: Display means for displaying the subject photographed by the photographing means in real time;
Selecting means for selecting a light source from the subject displayed by the display means,
The visible light receiving apparatus according to claim 1, wherein the decoding unit decodes the encoded signal acquired by the light receiving unit using the code of the light source selected by the selection unit. A storage means for storing the decoded signal;
3. The decoded signal stored in the storage unit corresponding to the light source selected by the selection unit is displayed on the display unit when a light source is selected by the selection unit. Visible light receiver. Photographing means for photographing the subject;
A light receiving means for receiving light emitted by the light source and acquiring a signal;
An acquisition means for acquiring from the light source the light receiving timing for acquiring a signal by the light receiving means;
Setting means for setting a timing at which the light receiving means acquires a signal using the light receiving timing acquired by the acquiring means;
A visible light receiving device comprising: Display means for displaying the subject photographed by the photographing means in real time;
Selecting means for selecting a light source from the subject displayed by the display means,
The visible light receiving apparatus according to claim 4, wherein the setting unit sets a timing at which the light receiving unit acquires a signal using a light reception timing of the light source selected by the selection unit. A process of receiving the light emitted from the light source by the light receiving means and obtaining the encoded signal;
A process of acquiring a code for decoding the encoded signal acquired by the light receiving means from the light source by an imaging means for imaging a subject;
A process of decoding the encoded signal acquired by the light receiving means using the code acquired by the imaging means;
The visible light receiving method characterized by including. A process of obtaining a signal by receiving light emitted from a light source by a light receiving means;
A process of acquiring a light reception timing for acquiring a signal by the light receiving unit from the light source by an imaging unit that captures a subject;
A process of setting a timing at which the light receiving means acquires a signal using the light receiving timing acquired by the photographing means;
The visible light receiving method characterized by including.

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