JP2013051585A - Visible light communication reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a visible light communication reception device capable of performing visible light communications without being affected by solar light.SOLUTION: A visible light communication reception device comprises: a visible light reception section which receives visible light; a filter which extracts Fraunhofer lines from the visible light received by the visible light reception section; and a reception circuit which performs a demodulation process on the basis of the Fraunhofer lines extracted by the filter.

Description

  Embodiments described herein relate generally to a visible light communication receiver for performing visible light communication.

  In recent years, for example, communication using visible light emitted from illumination or the like (hereinafter referred to as visible light communication) is known.

  In such visible light communication, a device that transmits a visible light signal on which information is superimposed (visible light communication transmitter) and a device that receives a visible light signal transmitted from the visible light communication transmitter (visible light communication). Receiving device). The visible light communication receiver includes a sensor (for example, a pin photodiode or an image sensor) for receiving visible light.

  In general, when such visible light communication is performed outdoors, in addition to the visible light signal transmitted from the visible light communication transmitter, sunlight rays often directly enter the sensor of the visible light communication receiver.

JP 2009-206840 A

  By the way, as described above, when the amount of light exceeding the limit of the sensor is incident on the sensor of the visible light communication receiving device due to the sunlight, the sensor (the reception sensitivity) is saturated. When the sensor of the visible light communication receiver is saturated in this way, the visible light signal transmitted from the visible light communication transmitter cannot be input (received) by the visible light communication receiver. I can't.

  Here, in the visible light communication receiver, for example, it is conceivable to block sunlight using a filter that blocks the visible light frequency band. However, in this case, since the visible light signal transmitted from the visible light communication transmitter is also blocked, visible light communication cannot be performed as a result.

  Therefore, the problem to be solved by the present invention is to provide a visible light communication receiver capable of performing visible light communication without being affected by sunlight.

  The visible light communication receiver according to the embodiment is extracted by a visible light receiving unit that receives visible light, a filter that extracts a Fraunhofer line from visible light received by the visible light receiving unit, and the filter. And a receiving circuit that performs demodulation processing based on the Fraunhofer line.

The block diagram which shows the structure of the visible light communication transmission apparatus and visible light communication receiver which concern on 1st Embodiment. The figure which shows the main symbols and wavelengths of a Fraunhofer line. The flowchart which shows the process sequence of the visible light communication transmission apparatus 10 and the visible light communication receiving apparatus 20 which concern on this embodiment. The figure for demonstrating the visible light communication transmission apparatus and visible light communication receiver which concern on 2nd Embodiment.

  Hereinafter, each embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of a visible light communication transmitter and a visible light communication receiver according to the first embodiment. The visible light communication transmitter 10 and the visible light communication receiver 20 shown in FIG. 1 are used for performing visible light communication.

  The visible light communication transmission device 10 includes a specific LED (Light Emitting Diode) light source 11 and a visible light communication transmission control circuit 12.

  The specific LED light source 11 is configured to emit visible light in a frequency band centered on a frequency not included in sunlight. The frequency not included in the sunlight includes one of the frequencies of the Fraunhofer line. The Fraunhofer line is a dark line that exists in the sunlight spectrum, and is generated when a specific frequency (wavelength) of the sunlight spectrum is absorbed by atoms and molecules in the atmosphere of the sun and the earth. Is.

  The visible light communication transmission control circuit 12 controls the specific LED light source 11 to perform visible light communication. The visible light communication transmission control circuit 12 modulates information transmitted to the visible light communication receiver 20 in visible light communication (hereinafter referred to as transmission information) by light emission of the specific LED light source 11.

  The visible light communication receiver 20 includes a filter 21, a condenser lens 22, a sensor device 23, and a visible light communication receiver circuit 24. Note that the visible light communication receiver 20 is provided with a visible light receiving unit (not shown) that receives visible light.

  The filter 21 extracts only one frequency (visible light) of the frequencies not included in the sunlight, that is, the frequency of the Fraunhofer line, from the received visible light. Note that the frequency extracted by the filter 21 and the frequency centered in the visible light emitted by the specific LED light source 11 included in the visible light communication transmitter 10 described above are the same.

  The condensing lens 22 condenses the visible light (visible light emitted by the specific LED light source 11 included in the visible light communication transmitter 11) extracted by the filter 21.

  The sensor device 23 converts the visible light collected by the condenser lens 22 into an electrical signal. The sensor device 23 includes, for example, a pin photodiode and an image sensor. The image sensor includes a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor.

  The visible light communication receiving circuit 24 performs a demodulation process based on the Fraunhofer line extracted by the filter 21. Specifically, the visible light communication receiving circuit 24 demodulates transmission information based on the electrical signal converted by the sensor device 23.

  Here, FIG. 2 shows the main symbols and wavelengths of the Fraunhofer lines described above. As shown in FIG. 2, there are a plurality of Fraunhofer lines.

  As described above, the specific LED light source 11 included in the visible light communication transmitter 10 is configured to emit visible light centered on one frequency of such a plurality of Fraunhofer lines. Further, the filter 21 included in the visible light communication receiver 20 extracts only the frequency (that is, one of a plurality of Fraunhofer lines) centered in the visible light emitted by the specific LED light source 11. It is configured as follows.

  Of the plurality of Fraunhofer lines shown in FIG. 2, the C-, F-, G'-, and h- lines are hydrogen ballmer series.

  Next, with reference to the flowchart of FIG. 3, the processing procedure of the visible light communication transmitter 10 and the visible light communication receiver 20 according to the present embodiment will be described. Note that the visible light communication transmitter 10 and the visible light communication receiver 20 according to the present embodiment are assumed to be used outdoors, for example.

  First, the visible light communication transmission control circuit 12 included in the visible light communication transmitter 10 converts transmission information (information transmitted in visible light communication) into an electric signal for driving the specific LED light source 11 (step S1). .

  The specific LED light source 11 included in the visible light communication transmission device 10 emits light based on the driving electrical signal converted by the visible light communication transmission control circuit 12 (step S2). In other words, the visible light communication transmission control circuit 12 modulates the transmission signal by the light emission of the specific LED light source 11.

  The specific LED light source 11 is configured to emit visible light in a frequency band centered on one of the frequencies of the Fraunhofer line (hereinafter referred to as a specific frequency) as described above.

  As described above, since the visible light communication transmitter 10 and the visible light communication receiver 20 are assumed to be used outdoors, in the visible light communication receiver 20, the visible light emitted from the specific LED light source 11 is changed. In addition, it is assumed that sunlight is incident (that is, received light).

  Here, the filter 21 included in the visible light communication receiver 20 is configured to extract (that is, pass) only a specific frequency (visible light) from the received visible light. Accordingly, the filter 21 blocks visible light (that is, visible light having a frequency included in sunlight) other than the visible light signal emitted by the specific LED light source 11 (step S3).

  Next, the condensing lens 22 condenses the visible light (visible light emitted by the specific LED light source 11) that has passed through the filter 21 (step S4).

  The sensor device 23 converts the visible light collected by the condenser lens 22 into an electrical signal (step S5). As described above, the sensor device 23 includes, for example, a pin photodiode, a CCD image sensor, and a CMOS image sensor.

  The visible light communication receiving circuit 24 demodulates the transmission information based on the electrical signal converted by the sensor device 23 (step S6).

  Visible light communication is performed between the visible light communication transmitter 10 and the visible light communication receiver 20 according to the present embodiment as described above.

  As described above, in the visible light communication transmitter 10 according to this embodiment, transmission is performed by light emission of the specific LED light source 11 that emits visible light in a frequency band centered on one of the frequencies of the Fraunhofer line. Information is modulated. Further, in the visible light communication receiver 20 according to the present embodiment, only the Fraunhofer line is extracted by the filter 21, and demodulation processing is performed based on the extracted Fraunhofer line.

  That is, in the present embodiment, communication is performed using a spectrum that is not included in the sunlight in order to exchange transmission information after eliminating strong disturbances such as sunlight. For this reason, the specific LED light source 11 provided on the visible light communication transmitter 10 side emits visible light in a frequency band centered on the frequency indicated by the spectrum not included in the sunlight, and on the visible light communication receiver 20 side. The provided filter 21 is configured to extract only the frequency (that is, the Fraunhofer line) indicated by the spectrum not included in sunlight.

  Thereby, in this embodiment, the visible light communication transmitter 10 and the visible light communication receiver 20 are used outdoors, for example, and the visible light emitted by the specific LED light source 11 included in the sunlight and the visible light communication transmitter 10 is used. Even in a situation in which light is incident on the visible light communication receiver 20 (sensor device 23 included), visible light having a frequency included in sunlight is blocked, so that the sensor device 23 ( Receiver sensitivity) is not saturated with sunlight. Therefore, in this embodiment, visible light communication can be performed stably without being affected by sunlight.

  In the present embodiment, the visible light communication receiver 20 is described as including the condensing lens 22, but the condensing lens 22 may be omitted. Thus, when the condensing lens 22 is abbreviate | omitted, the process of step S4 shown in FIG. 3 mentioned above is not performed. In addition, the constituent elements described in the present embodiment may be appropriately omitted or added according to design elements such as a communication distance or a light amount. The same applies to the following embodiments.

(Second Embodiment)
Next, a visible light communication transmission device and a visible light communication reception device according to the second embodiment will be described with reference to FIG.

  In the visible light communication transmitter 100 according to the present embodiment, a plurality of the visible light communication transmitters 10 according to the first embodiment described above are arranged as shown in FIG.

  Further, in the visible light communication receiver 200 according to the present embodiment, a plurality of visible light communication receivers 20 according to the first embodiment described above are arranged as shown in FIG.

  In the present embodiment, the visible light communication transmitter 100 is provided with a plurality of visible light communication transmitters 10, and the visible light communication receiver 200 is provided with a plurality of visible light communication receivers 20, whereby the Fraunhofer line It is assumed that transmission information is multiplexed at each frequency (that is, frequency division multiplexing).

  Each configuration of the visible light communication transmitter 10 shown in FIG. 4 is the same as that of the visible light communication transmitter 10 according to the first embodiment described above, and each configuration of the visible light communication receiver 20 described above. Since it is the same as that of the visible light communication receiver 20 according to the first embodiment, detailed description of the same parts as those of the first embodiment described above will be omitted. Further, the configurations of the visible light communication transmitter 10 and the visible light communication receiver 20 will be described with reference to FIG. 1 as appropriate.

  The specific LED light source 11 included in each of the plurality of visible light communication transmitters 10 provided in the visible light communication transmitter 100 according to the present embodiment has a frequency not included in sunlight (of the frequency of the Fraunhofer line). Of the frequency band centered on a frequency different from the visible light emitted by the specific LED light source 11 included in the other visible light communication transmitter 10. Emits visible light.

  That is, the specific LED light source 11 included in each of the plurality of visible light communication transmitters 10 is configured to emit visible light in a frequency band centered on different frequencies.

  In addition, each of the plurality of visible light communication transmitters 10 performs visible light communication with one corresponding visible light communication receiver 20. That is, in the present embodiment, the number of visible light communication transmitters 10 and the number of visible light communication receivers 20 are the same.

  The filter 21 included in each of the plurality of visible light communication receivers 20 provided in the visible light communication receiver 200 according to the present embodiment has a frequency not included in sunlight (one of the frequencies of the Fraunhofer line). Specific LED light source 11 included in the corresponding visible light communication transmitter 10 (that is, any one of the plurality of visible light communication transmitters 10). The visible light having the frequency centered in the visible light emitted by the above is extracted.

  That is, the filter 21 included in each of the plurality of visible light communication receivers 20 extracts Fraunhofer lines having different frequencies. In other words, the visible light communication receiver 200 according to the present embodiment is provided with a plurality of filters that respectively extract Fraunhofer lines having different frequencies from the received visible light.

  As shown in FIG. 4, each of the plurality of visible light communication transmitters 10 is connected to the information communication multiplexer 30 via a communication channel. The information communication multiplexing device 30 has a function of outputting (distributing) different information (transmission information multiplexed at each frequency of the Fraunhofer line) to each of the visible light communication transmission devices 10 for each communication channel.

  Each of the plurality of visible light communication transmitters 10 transmits (transmits) the transmission information output by the information communication multiplexer 30 by visible light communication. Since the operation of the visible light communication transmitter 10 in this case is the same as that of the first embodiment described above, detailed description thereof is omitted.

  Each of the plurality of visible light communication receivers 20 demodulates transmission information from visible light emitted by the specific LED light source 11 included in the corresponding visible light communication transmitter 10. That is, each of the plurality of visible light communication receivers 20 extracts a Fraunhofer line having a different frequency from the received visible light, and performs demodulation processing based on the Fraunhofer line. Since the operation of the visible light communication receiver 20 in this case is the same as that of the first embodiment described above, detailed description thereof is omitted.

  Here, as shown in FIG. 4, each of the plurality of visible light communication receivers 20 is connected to the information communication multiplexer 40 via a communication channel. The transmission information demodulated in each visible light communication receiver 20 is output to the information communication multiplexer 40 via the communication channel of the visible light communication receiver 20.

  As described above, between one set of corresponding visible light communication transmitting apparatus 10 and visible light communication receiving apparatus 20, one transmission information among a plurality of transmission information multiplexed at each frequency of the Fraunhofer line. Are transmitted and received by visible light communication.

  As described above, in the visible light communication transmission device 100 according to the present embodiment, visible light in a frequency band centered on one of the frequencies of the Fraunhofer gland is emitted from each of the visible light communication transmission devices 10. Is done. In the visible light communication receiver 200 according to the present embodiment, the Fraunhofer lines having different frequencies are extracted from the visible light by the filters 21 included in each of the visible light communication receivers 20. Thereby, in this embodiment, multiplexed visible light communication can be realized.

  That is, in the present embodiment, by using a plurality of frequencies of the Fraunhofer line, frequency division multiplex communication can be performed using each frequency as a communication channel.

  According to at least one embodiment described above, a visible light communication transmitter and a visible light communication receiver capable of performing visible light communication without being affected by sunlight can be provided.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in each embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 10 ... Visible light communication transmitter, 11 ... Specific LED light source, 12 ... Visible light communication transmission control circuit, 20 ... Visible light communication receiver, 21 ... Filter, 22 ... Condensing lens, 23 ... Sensor device, 24 ... Visible light Communication receiving circuit, 30... Information communication multiplexer, 40.

Claims (2)

A visible light receiving part for receiving visible light;
A filter that extracts a Fraunhofer line from visible light received by the visible light receiver;
A visible light communication receiving apparatus comprising: a receiving circuit that performs demodulation processing based on the Fraunhofer line extracted by the filter. A visible light receiving part for receiving visible light;
A plurality of filters for extracting Fraunhofer lines each having a different frequency from visible light received by the visible light receiving unit;
A visible light communication receiving apparatus comprising: a receiving circuit that performs demodulation processing based on a Fraunhofer line extracted by each of the plurality of filters.

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