WO2007119611A1

WO2007119611A1 - Visible light communication system

Info

Publication number: WO2007119611A1
Application number: PCT/JP2007/057083
Authority: WO
Inventors: Takemi Arita; Shinichiro Haruyama; Masao Nakagawa; Takehiko Yamaguchi; Toshihiko Komine
Original assignee: Nakagawa Laboratories, Inc.
Priority date: 2006-03-31
Filing date: 2007-03-30
Publication date: 2007-10-25
Also published as: JP2007274580A; TW200807913A

Abstract

[PROBLEMS] A visible light communication system is provided to stably and surely carry out an up-link communication. [MEANS FOR SOLVING THE PROBLEMS] A visible light communication system is comprised of a transmitting and receiving unit (1) for transmitting data by illumination light to terminal device (3) and for receiving data from the terminal device (3), and a receiving unit (2) for receiving data sent by light from the terminal device (3), wherein the receiving unit (2) is connected with an electric power line (4) in the same way as the transmitting and receiving unit (1) but provided at a position which is different from the transmitting and receiving device (1). With this, even if the transmitting and receiving unit (1) fails to receive the light from the terminal device but if the receiving unit (2) receives it, communication can be carried out. When, for example, light to the transmitting and receiving unit (1) is interrupted or light from the terminal device (3) is changed, communication can be made if the receiving unit (2) can receive it, so that stable and sure communication can be carried out.

Description

Specification

Visible light communication system

Technical field

[0001] The present invention relates to a bidirectional communication system using a power line and illumination light (visible light).

Background art

In recent years, semiconductor light emitting elements such as LEDs have been used as light sources for illumination. The semiconductor light-emitting element can blink at high speed or control the amount of light. A technology has been developed to transmit data using illumination light by using this characteristic to blink a semiconductor light emitting element for illumination or to control the amount of light according to the data. If the blinking of the semiconductor light emitting element or the change in the amount of light is fast, the blinking or change in the amount of light is not visible to the human eye. Therefore, it is possible to transmit data without hindering human use as illumination light. In addition, lighting devices are widely used, and there is an advantage that these lighting devices can be used for communication.

[0003] For example, Patent Document 1 describes a broadcasting system using illumination light. In this case, communication is only in one direction to the lighting device power terminal device (downlink). Infrared communication is normally used for communication from the terminal device to the lighting device (uplink). However, as described in Patent Document 2, for example, the uplink also uses visible light. ing.

[0004] When illumination light is used for the downlink, a communication circuit is incorporated in a light emitting part such as a light bulb as an illumination light source that is attached to the illumination apparatus or the illumination apparatus. Or it is provided in the periphery. Therefore, the position of the light receiving unit is fixed. For example, when light from the terminal device is blocked by an obstacle or a human body, there is a problem that communication cannot be performed. In addition, when the terminal device is a portable type, there is a possibility that communication cannot be performed only by the operator moving the terminal device. Furthermore, since the light emitting part and the light receiving part are close to each other, there is a problem that strong illumination light enters the light receiving part and interferes with the uplink light. Patent Document 1: Japanese Patent Application Laid-Open No. 2004-147063

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-221747

Disclosure of the invention

Problems to be solved by the invention

[0006] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a visible light communication system capable of performing uplink communication stably and reliably. Means for solving the problem

[0007] The present invention provides a visible light communication system in which illumination light connected to a power line is modulated by data received by the power line force and transmitted, and the data is received by the light receiving element. Transmission / reception means for sending data to the power line; and a plurality of reception means for sending data received by a light receiving element connected to the power line to the power line, wherein the plurality of reception means are different from the transmission / reception means. It is characterized by being placed in place.

The invention's effect

[0008] According to the present invention, a plurality of reception means connected to the same power line as the transmission / reception means are arranged at a location different from the transmission / reception means, so even one reception means or transmission / reception means is improved. Even if the light on the link is blocked, it can be received by other receiving means or transmitting / receiving means. Further, even if the operator moves the terminal device and changes the direction of the uplink light, communication can be performed as long as it can be received by any one of a plurality of receiving means or transmitting / receiving means. Therefore, there is an effect that uplink communication can be performed stably and reliably.

[0009] Further, for example, even if it is difficult to receive uplink light because the light receiving unit of the transmission / reception unit is prevented from receiving interference of illumination light, it can be covered by another reception unit. Therefore, uplink communication can be performed stably and reliably in this case as well.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a schematic diagram showing one embodiment of the present invention. In the figure, 1 is the transmitter / receiver, 2 is the receiver 3 is a terminal device, 4 is a power line, and 5 is an external device. In the present invention, a power line 4 that supplies power is generally used, and the power line 4 is connected to a transmission / reception unit 1, a plurality of reception units 2, and an external device 5. Each of these units receives power from the power line 4 and communicates using the same power line 4. Here, the data transmitted from the external device 5 is transmitted to the terminal device 3 using the illumination light by the transmission / reception unit 1, and the data transmitted from the terminal device 3 by light is transmitted to the transmission / reception unit 1 or the reception unit 2. An example of receiving and transmitting to the external device 5 through the power line 4 is shown.

[0011] Note that the terminal device 3 has a function of receiving illumination light and receiving data (downlink) transmitted by the illumination light, and a function of driving light emitting elements and transmitting data by light. ing.

The transmission / reception unit 1 includes semiconductor light emitting elements such as LEDs, LDs, and ELs, and emits light from the semiconductor light emitting elements and performs illumination with the emitted light. In addition, it receives data sent through the power line 4, and controls the blinking of the semiconductor light emitting element or controls the amount of light according to the received data, thereby modulating the illumination light. Is sent (downlink). Further, the transceiver 1 has a light receiving element. The light receiving element receives light (uplink) from the terminal device 3, receives data transmitted from the terminal device 3 by light, and sends the data to the external device 5 through the power line 4.

[0013] The receiving unit 2 has a light receiving element. The light receiving element receives light (uplink) from the terminal device 3 and receives data transmitted from the terminal device 3 by light. To send data to the external device 5. A plurality of receiving units 2 can be provided.

The receiving unit 2 is arranged at a different location from the transmitting / receiving unit 1. For example, in the example shown in FIG. 1, the transmitter / receiver 1 functions as a light and is usually provided on the ceiling of a room. The receiving unit 2 may be provided at a position away from the transmitting / receiving unit 1 such as, for example, on the wall of a room or in the corner of the ceiling.

[0015] The configurations of the transmission / reception unit 1 and the reception unit 2 will be further described. FIG. 2 is a block diagram showing an example of the transmission / reception unit 1. In the figure, 11 is a modulation / demodulation unit, 12 is a light modulation unit, 13 is a semiconductor light emitting device, 14 is a light receiving device, and 15 is an amplification unit.

Modulator / demodulator 11 demodulates and captures data sent through power line 4 and modulates light. The data received from the amplifying unit 15 is modulated and sent to the power line 4.

[0017] The light modulation unit 12 controls the blinking or light amount of the semiconductor light emitting element 13 according to the data passed from the modem unit 11, modulates the light (illumination light) emitted from the semiconductor light emitting element 13, and transmits the data. To do.

[0018] As described above, the semiconductor light emitting element 13 is a light emitting element having high-speed response characteristics such as LED, LD, EL, etc., and light emitted from the semiconductor light emitting element 13 is used as illumination light. The semiconductor light emitting element 13 is blinked or the amount of light is controlled by the light modulator 12. If blinking and fluctuations in the amount of light are high-speed, the human eye will not be affected by blinking or fluctuations in the amount of light, and even light modulated by data can be used as illumination.

The light receiving element 14 receives light transmitted from the outside and converts it into an electrical signal. In this case, the light emitted from the terminal device 3 is received, and the transmitted data is converted into an electric signal and sent to the amplifying unit 15. As the light receiving element 14, for example, various light receiving elements such as a photodiode, a phototransistor, a CCD, and a CMOS sensor can be used.

The amplification unit 15 amplifies the electric signal received and converted by the light receiving element 14 and passes the amplified signal to the modulation / demodulation unit 11. As a result, the data sent from the terminal device 3 is sent from the modem 11 to the power line 4.

FIG. 3 is a block diagram illustrating an example of the receiving unit 2. In the figure, 21 is a light receiving element, 22 is an amplifying unit, and 23 is a modulating unit. The receiving unit 2 is only a part of the transmitting / receiving unit 1. The light receiving element 21 is the same as the light receiving element 14 of the transmission / reception unit 1. For example, the light reception element 21 receives light emitted from the terminal device 3, converts the transmitted data into an electrical signal, and sends it to the amplification unit 15.

The amplification unit 22 is the same as the amplification unit 15 of the transmission / reception unit 1, amplifies the electric signal received and converted by the light receiving element 21, and passes it to the modulation unit 23.

The modulation unit 23 has the modulation function of the modulation / demodulation unit 11 of the transmission / reception unit 1, modulates the received data passed to the amplification unit 22, and sends it to the power line 4. As a result, the data sent from the terminal device 3 is sent to the power line 4.

[0024] The outline of the operation in the embodiment of the present invention will be briefly described below. First, the downlink for data transmission from the external device 5 to the terminal device 3 is the same as the conventional communication using power lines and illumination light as described in Patent Document 1, for example. That is, data transmitted from the external device 5 through the power line 4 is demodulated by the modem unit 11 of the transmission / reception unit 1 and passed to the optical modulation unit 12. The light modulation unit 12 controls the blinking or light amount of the semiconductor light emitting element 13 according to the data passed from the conversion modulation unit 11, thereby modulating the light (illumination light) emitted from the semiconductor light emitting element 13. Send data.

[0025] The terminal device 3 can acquire transmitted data by receiving and demodulating light (illumination light) emitted from the transmission / reception unit 1. In general, illumination light can be communicated without any problem as long as the direction of the light receiving element of the terminal device 3 where the light intensity is strong changes or a shadow is formed.

[0026] On the other hand, for the uplink that performs data transmission from the terminal device 3 to the external device 5, light (visible light) is controlled by blinking or controlling the light amount of the light emitting element provided in the terminal device 3 according to the data. Alternatively, data can be transmitted by infrared light). This light is received by the light receiving element 14 of the transmission / reception unit 1, amplified by the amplification unit 15, modulated by the modulation / demodulation unit 11, and sent to the power line 4, whereby data is transmitted to the external device 5. Alternatively, the light emitted from the terminal device 3 is received by the light receiving element 21 of the receiving unit 2, amplified by the amplifying unit 22, modulated by the modulating unit 23, and sent to the power line 4. Is transmitted

[0027] In this uplink, the intensity of the emitted light on the terminal device 3 side is much weaker than the illumination light used for the downlink. For this reason, if the light emitted from the terminal device 3 side is blocked or the direction of the light changes, the amount of light received at the fixed point changes greatly, and data cannot be received. For example, it is assumed that light emitted from the terminal device 3 in a normal state is mainly received by the transmission / reception unit 1. In this state, if the light emitted from the terminal device 3 is blocked by a person or the direction of the emitted light changes due to movement of the terminal device 3, etc., the amount of light received by the transmission / reception unit 1 changes significantly, causing data to change. May not be received.

[0028] In such a case, if any of the receiving units 2 can receive the light emitted from the terminal device 3, the receiving unit 2 receives the light emitted from the terminal device 3 and receives the data. Then outside Can be transferred to device 5. For this purpose, the receiving unit 2 is arranged at a different location from the transmitting / receiving unit 1 as described above. For example, in the example shown in FIG. 1, the transmission / reception unit 1 is provided on the ceiling of the room, and the reception unit 2 is provided on the wall of the room. By providing the receiving unit 2 at a position away from the transmitting / receiving unit 1 in this manner, for example, even when light from the terminal device 3 to the transmitting / receiving unit 1 is blocked, the receiving unit 2 radiates from the terminal device 3. Power S can be received. Further, even when the operator changes the attitude of the terminal device 3 and the direction of the emitted light changes accordingly, for example, when the terminal device 3 is portable, the transmission / reception unit 1 or If light can be received by any of the plurality of receiving units 2, communication can be performed. Further, even if the light from the terminal device 3 and the illumination light interfere with each other in the transmission / reception unit 1, if the other reception unit 2 can receive light and receive data, the communication with the printer can be performed without any problem.

Of course, it does not matter if the light emitted from the terminal device 3 is received by the receiving unit 2 and the data is received normally. In the past, only the transceiver 1 was used, so it was necessary to always return the uplink light in the direction of the illumination light. However, in the present invention, by providing one or more receiving units 2 in addition to the transmitting / receiving unit 1, it is not necessary to direct the uplink light in the direction of the illumination light, and the degree of freedom can be further increased.

[0030] In addition, the receiving unit 2 can be installed anywhere as long as it can be connected to the power line, and has a very high degree of freedom. Needless to say, the receiving unit 2 is not limited to the arrangement shown in FIG.

[0031] In this way, even if the light emitted from the terminal device 3 is blocked or the direction of the light is changed, the data is received and received by either the transmission / reception unit 1 or the reception unit 2, and stable. And uplink communication can be performed reliably.

Note that light emitted from the terminal device 3 may be received by the transmission / reception unit 1 and one or a plurality of reception units 2 or a plurality of reception units 2. In order to cope with such a case, it is preferable to attach an ID or a time stamp to the data transmitted from the terminal device 3. Thus, even when data is received by a plurality of transmission / reception units 1 and reception units 2, the transmission / reception unit 1 and reception unit 2 may transfer the data to the external device 5 as they are. In the external device 5, when data with the same ID or the same time stamp is sent, one is excluded. And discard it. In this way, accurate data transmission can be realized even when a plurality of signals are received.

In the configuration shown in FIG. 1, in the modem 11 and the modulator 23, when the light waveform received by the light receiving element 14 or the light receiving element 21 is converted into an electric signal, it is converted into a signal of a different format. By adopting a method that directly modulates the power line, the device configuration can be simplified and the price can be reduced. Of course, the present invention is not limited to this configuration, and details at the time of communication are arbitrary, such as using different modulation schemes for communication by light and communication through a power line.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

2 is a block diagram showing an example of a transmission / reception unit 1. FIG.

FIG. 3 is a block diagram illustrating an example of a receiving unit 2;

Explanation of symbols

[0035] 1 ... Transmission / reception unit, 2 ... Reception unit, 3 ... Terminal device, 4 ... Power line, 5 ... External device, 11 ... Conversion modulation unit, 12 ... Light modulation unit, 13 ... Semiconductor light emission Elements 14 ··· Light receiving element 15 ··· Amplifying unit 21 ··· Light receiving device 22 ··· Amplifying unit 23 ··· Modulating unit

Claims

The scope of the claims

Transmitting / receiving means for modulating illumination light generated by light emitted from the illumination element connected to the power line with data received from the power line and transmitting the data, and transmitting data received by the light receiving element to the power line; and the power line A visible light communication system, comprising: a plurality of receiving means for sending data received by a light receiving element to the power line; and the plurality of receiving means are arranged at locations different from the transmitting / receiving means. .