JP5000327B2 - Visible light communication system - Google Patents

Description

  The present invention relates to a visible light communication system in which visible light communication is performed by blinking a light emitting diode by controlling a current supplied to the light emitting diode, and receiving and analyzing the light.

  Conventionally, as a lighting fixture constituting a visible light communication lighting system, an LED, a switching element that modulates and drives the LED, and an average current detection unit that detects an average current flowing through the LED are connected to a voltage source. It is known (see, for example, Patent Document 1). In this lighting apparatus, when the LED is modulated and driven by the switching element, the LED is controlled to blink or light, and emits modulated light on which a communication signal is superimposed. By this LED modulation driving, the average light amount emitted from the LED is reduced. The average current detector detects the average current flowing through the LED and controls the output voltage of the voltage source so that the average current flowing through the LED is substantially constant. For this reason, the average light quantity can be kept substantially constant regardless of the presence or absence of LED modulation.

  Further, as a visible light communication system, an LED emitting light in the visible light region is known to blink with an on time and an off time fixed at a predetermined ratio, and a receiver receives the light of the LED. (For example, refer to Patent Document 2). In this system, since the lighting time and turning-off time of the LED are fixed at a predetermined ratio, the brightness of the illumination light does not change even when the lighting frequency of the LED changes due to data communication.

However, in the techniques described in Patent Document 1 and Patent Document 2, communication by the light-emitting diode is possible by controlling the current supplied to the light-emitting diode according to the communication signal, but in order to dimm the light-emitting diode. It was difficult to dimming the light-emitting diode by controlling the current according to the dimming signal. For this reason, it has been difficult to achieve both dimming of the light emitting diode and visible light communication using the light emitting diode by controlling one current signal supplied to the light emitting diode.
JP 2006-120910 A JP 2004-120101 A

  The present invention has been made to solve the above-described conventional problems. By controlling one current signal supplied to the light emitting diode, both dimming of the light emitting diode and communication by the light emitting diode are achieved. An object of the present invention is to provide a visible light communication system that can be used.

In order to achieve the above object, the present invention provides a visible light communication system in which visible light communication is performed by blinking a light emitting diode by controlling a current supplied to the light emitting diode, and receiving and analyzing the light. A communication signal generating unit for generating a communication signal; a dimming signal generating unit for generating a dimming signal for dimming the light emitting diode; and a pulse width control for controlling a pulse width of a current supplied to the light emitting diode. And a pulse height control means for controlling a pulse height of a current supplied to the light emitting diode, and any one of the pulse width control means and the pulse height control means is used as the communication signal. performs the corresponding current control, the other, the ratio of the pulse width / pulse maximum height of the current is equal to the indicated is dimming by the light control signal Sea urchin, and controls the pulse width / pulse height, and performing current control corresponding to the dimming signal.

According to the present invention , one of the pulse width control means and the pulse height control means performs current control corresponding to the dimming signal for the light emitting diode, and the other performs current control corresponding to the communication signal. It is possible to independently perform dimming control and communication control of the light emitting diode using one current signal supplied to. Therefore, it is possible to achieve both dimming of the light emitting diode and communication by the light emitting diode.

  A visible light communication system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the visible light communication system 1. The visible light communication system 1 includes a lighting device 2 that blinks the LED 21 by controlling a current supplied to a light emitting diode (hereinafter referred to as an LED) 21, and a visible light communication by receiving and analyzing the light of the LED 21. And a receiver 3 for performing Hereinafter, the detailed structure of the lighting fixture 2 and the receiver 3 is shown.

  In addition to the LED 21, the lighting fixture 2 includes a communication signal generation unit 22 that generates a communication signal, a dimming signal generation unit 23 that generates a dimming signal for dimming the LED 21, and a pulse width of a current supplied to the LED 21. The pulse width control means 24 for controlling the power, the pulse height control means 25 for controlling the pulse height of the current supplied to the LED 21, and the direct current power for using the alternating current power from the commercial power source 60 inside the lighting fixture 2. And an AC / DC converter 26 for conversion into The AC / DC converter 26 supplies power to each part in the lighting fixture 2.

  The LED 21 serves as a light source for illumination, and is composed of, for example, a high-intensity white LED in which a blue light emitting diode and a yellow phosphor are combined. The LED 21 is driven by the supplied current and emits light. This current is supplied to the LED 21 in the form of a current signal in order to control the light emission intensity of the LED 21. This current signal is constituted by, for example, a pulse signal composed of a pulse train. By changing the pulse height of the current signal, the emission intensity of the LED 21 changes. In addition, when the frequency of the current signal is constant, the apparent light emission intensity, that is, the average light emission amount of the LED 21 can be changed by changing the current energization time per unit time, that is, the pulse width of the current signal. .

  The communication signal generation unit 22 is configured by a device such as a microcomputer that can generate a weak electric pulse signal having a relatively high frequency as a communication signal. The frequency of the weak electric pulse signal is, for example, several tens of kHz to several hundreds of MHz. This weak electric pulse signal is composed of a weak voltage signal having a binary voltage level of High level and Low level (hereinafter referred to as H level and L level, respectively). By changing the arrangement of the L level and the H level, a weak electric pulse signal, that is, a communication signal is formed. This arrangement can be arbitrarily changed via an external I / F (Interface) device (not shown). The above arrangement is fixed, and the information may be stored in advance in a storage unit (not shown). The communication signal generation unit 22 sends the generated communication signal to the pulse width control unit 24.

  The dimming signal generation unit 23 can generate a weak electric pulse signal or a weak electric analog signal as a dimming signal, and can change the pulse width of the weak electric pulse signal or the peak value of the weak electric analog signal. Consists of. The weak electric pulse signal and the weak electric analog signal are composed of weak voltage signals. In the dimming signal, when the element indicating the degree of dimming is a pulse width, that is, a duty ratio, the dimming signal generation unit 23 is configured by a device capable of changing the pulse width of the weak electric pulse signal, and when the element is a peak value, It is composed of devices that can change the peak value of weak electrical analog signals. The dimming degree is set based on a signal from an external dimmer, a remote controller or the like (not shown). The dimming signal generation unit 23 sends the generated dimming signal to the pulse height control means 25. When the communication signal generation unit 22 and the dimming signal generation unit 23 are configured by a microcomputer, the communication signal generation unit 22 and the dimming signal generation unit 23 may share the same microcomputer.

  The pulse width control means 24 is configured by a semiconductor switching element such as an FET or a transistor, for example. This semiconductor switching element is connected in series to the LED 21, receives a communication signal from the communication signal generation unit 22, and controls a current supplied to the LED 21 according to the communication signal. Specifically, the semiconductor switching element performs a switching operation in accordance with the switching timing of the H level and the L level in the communication signal, and controls the energization time to the LED 21, whereby the pulse width of the current signal supplied to the LED 21. That is, the duty ratio is controlled.

  The pulse height control means 25 is configured by a device that performs current control, such as a shunt regulator or an IPD (Intelligent Power Device). This device receives the dimming signal from the dimming signal generation unit 23, and controls the current supplied to the LED 21 according to the dimming signal. Specifically, the above device controls the pulse height of the current signal supplied to the LED 21 in accordance with the pulse width and peak value of the dimming signal.

  On the other hand, the receiver 3 includes a light receiving unit 31 configured by a photodiode or the like that receives light from the LED 2, and a control unit that obtains a communication signal superimposed on the light from the LED 21 by analyzing the output of the light receiving unit 31. 32. The control part 32 is comprised by the microcomputer, for example.

  FIG. 2 shows signal waveforms at various points in the visible light communication system 1. Hereinafter, the operation of the visible light communication system 1 will be described while explaining the signal waveforms at each location. Here, it is assumed that the external I / F device 4 is connected to the communication signal generation unit 22, and the dimmer 5 is connected to the dimming signal generation unit 23. In the operation of the visible light communication system 1, first, power is supplied to each part of the luminaire 2 from the AC / DC converter 26 (not shown in FIG. 2), and the receiver 3, the external I / F device 4, and the control device are controlled. The optical device 5 is turned on.

  Next, the dimming signal generation unit 23 generates a dimming signal based on the signal indicating the dimming degree input from the dimmer 5. The dimming signal generation unit 23 sends this dimming signal to the pulse height control means 25. The pulse height control means 25 is driven based on the dimming signal from the dimming signal generation unit 23 and supplies a current signal to the LED 21. The LED 21 emits light with a light emission intensity corresponding to the current signal.

  Here, an example of the operation of the dimming signal generator 23 and the pulse height control means 25 will be shown. For example, it is assumed that the dimmer 5 inputs a signal for instructing the LED 21 to light at 30% of the maximum light emission intensity to the dimming signal generation unit 23. This signal consists of a voltage signal having a peak value indicating 30% lighting of the LED 21 (shown in a broken line frame A). The dimming signal generator 23 that has received this signal sets the pulse width of the weak electric pulse signal, that is, the duty ratio, to 30%, and transmits this weak electric pulse signal to the pulse height control means 25 (shown in the broken line B). ). The pulse height control means 25 sends a signal to the LED 21 such that the pulse height of the current signal supplied to the LED 21 is 30% of the maximum pulse height. This signal is composed of, for example, a current signal having a peak value corresponding to 30% lighting of the LED 21 (shown in a broken line frame C). The LED 21 emits light at 30% of the maximum light emission intensity according to the current signal.

  On the other hand, when there is no signal input from the external I / F device 4, the communication signal generation unit 22 sends a weak electric pulse signal whose voltage level is always H level to the pulse width control unit 24. The pulse width control means 24 performs current control so that a current signal whose pulse height is always set by the pulse height control means 25 is supplied to the LED 21. In addition, when there is a signal input from the external I / F device 4, the communication signal generation unit 22 outputs a communication signal in which a pulse train is arranged according to the signal from the external I / F device 4 to a pulse width control unit. 24. This communication signal is switched according to the pulse train between a voltage level of H level and L level.

  The pulse width control unit 24 supplies current to the LED 21 according to the communication signal from the communication signal generation unit 22. That is, while the voltage level of the communication signal is at the H level, a current having a value set by the pulse height control means 25 is supplied to the LED 21. Further, the current supply to the LED 21 is interrupted while the voltage level is the L level. Thus, the energization time of the current supplied to the LED 21 is controlled according to the communication signal, and the pulse width of the current signal supplied to the LED 21 is changed.

  Here, an example of the operation of the communication signal generator 22 and the pulse width controller 24 will be shown. For example, it is assumed that a pulse signal having binary voltage values of H level and L level is input from the external I / F device 4 to the communication signal generation unit 22. The pulse width of this signal varies according to the information superimposed on the signal (shown in a broken line D). The communication signal generation unit 22 sends a communication signal whose voltage level fluctuates according to the signal from the external I / F device 4 to the pulse width control unit 24 (shown in a broken line frame E). When the pulse height of the current signal supplied to the LED 21 is set to 30% of the maximum value by the pulse height control means 25, the pulse width control means 24 determines the voltage level of the communication signal from the communication signal generator 22. While H is at the H level, current control is performed so that a current signal is supplied to the LED 21 with the pulse height set by the pulse height control means 25 as it is. The pulse width control means 24 cuts off the current supply to the LED 21 (shown in a broken line frame F) while the voltage level of the communication signal is L level.

  The LED 21 is driven based on a current signal whose pulse height is controlled according to the dimming signal by the pulse height control means 25 and whose pulse width is controlled according to the communication signal by the pulse width control means 24. Flicker. The frequency of the current signal is set high so that the flickering of the light from the LED 21 is not visible to humans. For this reason, communication using visible light is possible without causing discomfort to humans.

  The light receiving means 31 of the receiver 3 receives the light from the LED 2. The control unit 32 recognizes the change in the light emission intensity of the LED 2 in time series according to the output of the light receiving means 31, and obtains a communication signal. For example, the control unit 32 causes the output of the light receiving unit 31 when the light emission intensity of the LED 2 is 30% of the maximum value to correspond to the H level, and sets the output of the light receiving unit 31 when the LED 2 is turned off to the L level. A signal is generated in response. For this reason, it is possible to generate the same signal as the signal from the external I / F device 4, that is, the communication signal generated by the communication signal generator 22. In this way, in the visible light communication system 1, communication between the lighting fixture 2 and the receiver 3 becomes possible.

  In the above configuration, the pulse height control means 25 performs current control corresponding to the dimming signal for the LED 21, and the pulse width control means 24 performs current control corresponding to the communication signal. It becomes possible to perform dimming control and communication control of the LED 21 independently using two current signals. Therefore, the dimming of the LED 21 and the communication by the LED 21 can be made compatible.

  In addition, this invention is not restricted to the structure of said embodiment, A various deformation | transformation is possible according to a use purpose. For example, the pulse height control unit 25 controls the current supplied to the LED 21 according to the communication signal from the communication signal generation unit 22, and the pulse width control unit 24 controls the current from the dimming signal generation unit 23. The current may be controlled according to the optical signal.

1 is a configuration diagram of a visible light communication system according to an embodiment of the present invention. The figure which shows the signal waveform in each location of the said system.

Explanation of symbols

1 Visible Light Communication System 2 Lighting Equipment 21 LED
22 Communication signal generator 23 Dimming signal generator 24 Pulse width controller 25 Pulse height controller 3 Receiver

Claims (1)

In a visible light communication system that performs visible light communication by blinking the light emitting diode by controlling the current supplied to the light emitting diode, and receiving and analyzing the light,
A communication signal generator for generating a communication signal;
A dimming signal generation unit for generating a dimming signal for dimming the light emitting diode;
Pulse width control means for controlling the pulse width of the current supplied to the light emitting diode;
Pulse height control means for controlling the pulse height of the current supplied to the light emitting diode,
Wherein one of the pulse width control means and the pulse height control means, either one may perform a current control corresponding to the communication signal and the other, the ratio of the maximum value of the pulse width / pulse height of the electric current, the a visible light communication system to be equal and depicted by dimming degree, by controlling the pulse width / pulse height, and performing current control corresponding to the dimming signal by the dimming signal.

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