KR20120067780A - Visible light communication system using r,g,b led - Google Patents

Abstract

PURPOSE: A visible light communication system using RGB(red, green, blue) LEDs is provided to obtain effectively modulated optical signals by inputting transmit data and color data to a controller for performing the visible light communication and color lighting at the same time. CONSTITUTION: A visible light communication system using RGB(red, green, blue) LEDs comprises the following: a transmitting device(100) coding inputted transmit data, producing a PWM signal corresponding to inputted color data, and operating plural LEDs having different colors for modulating the coded transmit data into optical signals in different colors using the PWM signal; and a receiving device(200) demodulating the optical signals, and decoding the demodulated optical signals.

Description

Visible light communication system using R, G, B LED {VISIBLE LIGHT COMMUNICATION SYSTEM USING R, G, B LED}

The present invention relates to a visible light communication system. In particular, the present invention relates to a visible light communication system that can be utilized in color illumination.

 The visible light communication system is generally implemented using only one color such as white and red. This is because the transmission / reception scheme is simplified when using one color, and thus it is easy to implement.

 However, in the case of LED lighting used as the main communication medium of the visible light communication system, it is increasingly being implemented in various colors according to the needs of consumers. In this situation, the conventional visible light communication system also needs to use various colors of illumination instead of a single color.

LED lighting can use light sources of basic colors such as R (Red), G (Green), and B (Blue) LEDs to achieve various colors, and in general, PWM (PWM) Pulse Width Modulation) method is used.

However, the conventional visible light communication system has difficulty in transmitting data using R (Red), G (Green), and B (Blue) LEDs driven by the PWM method as described above. That is, in the conventional visible light communication system, there is a difference in operation intervals for each color, and if the data is modulated accordingly, there is a big limitation in the length of the transmission data packet, which causes a communication error. It may have a problem that is difficult to obtain the color of the desired light.

An object of the present invention is to provide a visible light communication system that can be used for visible light communication without affecting the color light using the LED.

A first aspect of the visible light communication system according to the present invention for solving the above problems is a transmission device for coding the input transmission data and modulates the coded transmission data into a plurality of color optical signals; A receiver for demodulating the received optical signals of a plurality of colors and decoding the demodulated optical signals; And a controller for controlling each operation of the transmitter and the receiver.

The transmitting device generates a PWM signal corresponding to the color data input by the control device, and uses the generated PWM signal so that the coded transmission data is modulated into the multi-color light signal. Can drive them.

The coded transmission data may be coded by a Manchester coding scheme in which the high and low ratios of signals are kept the same. Here, the coded transmission data may be block coded and byte interleaved before being coded by the Manchester coding scheme, and the block coding may be performed by a Hamming code.

A second feature of the visible light communication system according to the present invention for solving the above problems is to code the input transmission data, generate a PWM signal corresponding to the input color data, the coded by using the generated PWM signal A transmitter for driving the LED lamps having a plurality of colors so that the transmission data is modulated into a plurality of color optical signals; A receiver for demodulating the received optical signals of a plurality of colors and decoding the demodulated optical signals; And a controller for controlling each operation of the transmitter and the receiver.

The PWM signal repeatedly drives the entire LED lamps by a predetermined period, and the period may be shorter than the time for which the afterimage of the naked eye remains.

The PWM signal may repeatedly drive the entire LED lamps by a predetermined period, and the PWM signal may be disposed in front of each period.

The transmitting device includes an LED driver including driving elements for driving each of the LED lamps, a PWM module for generating a PWM signal corresponding to the color data, and the driving signal for the PWM signal corresponding to the color data, respectively. It may include a PWM generating unit having a distribution module for selecting and distributing. The LED driver may further include an AND gate device that receives and outputs each of the PWM signals distributed by the distribution module and the coded transmission data, and outputs an AND logic operation to each of the driving devices.

The visible light communication system according to the present invention can simultaneously perform visible light communication and color illumination by receiving transmission data and color data by a control device and generating an optical signal which is efficiently modulated based on them.

Specifically, in the visible light communication system according to the present invention, since the PWM signal provided to the LED driver is disposed in front of every cycle, and the PWM signal for driving each driving element is provided in an undivided form, color illumination is minimized while minimizing a communication error. The color distortion of the can be minimized.

1 is a block diagram of a visible light communication system according to an embodiment of the present invention.
2 is a block diagram of a transmitter according to an embodiment of the present invention.
3 is a waveform diagram illustrating an operation of a transmitter according to an embodiment of the present invention.
4 is a block diagram of a receiving apparatus according to an embodiment of the present invention.

Hereinafter, a visible light communication system according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a visible light communication system according to an embodiment of the present invention. As shown in FIG. 1, the visible light communication system 1 according to the present exemplary embodiment may be composed of a transmitter 100, a receiver 200, and a control device 300 for controlling them.

The transmitting device 100 generates a PWM signal in response to the coding unit 110 for coding the transmission data TD input by the control device 300 and the color data CD input by the control device 300. The PWM generator 130, and the LED light emitting unit 150 for modulating the transmission data coded using the PWM signal to a plurality of color light signal. The receiver 200 includes a photoelectric converter 210 for demodulating an optical signal received from the outside and a decoder 230 for decoding the demodulated electric signal.

2 is a block diagram of a transmitter according to an embodiment of the present invention. As shown in FIG. 2, the transmitting device 100 includes a coding unit 110, a PWM generation unit 130, and an LED light emitting unit 150. The transmitting device 100 receives the transmission data to be transmitted and the color data related to the color under the control of the control device 300 and generates an optical signal based on these, and emits light that is a communication signal and serves as color lighting. do.

As shown in FIG. 2, the coding unit 110 includes a block coder 112, a byte interleaver 114, and a Manchester encoder 116. The coding unit 110 functions to code the transmission data input by the control of the control device 300 and output the coded data to the LED driver 152.

The block coder 112 and the byte interleaver 114 perform a function for minimizing a transmission error that occurs during transmission. The block coder 112 cuts the transmission data and codes the data in block units, and the byte interleaver 114 performs a function of minimizing an error occurring when the data is mixed in the time domain.

The visible light communication system 1 of the present embodiment may use R (Red), G (Green), and B (Blue) LEDs as the LED module 154 for implementing optical signals of various colors. In this case, since the communication medium is light emitted sequentially from the R, G, and B LEDs, it may include turn-on and turn-off delay times. This can cause errors.

The block coder 112 shown in FIG. 2 may use a Hamming code. For example, the 7-4 Hamming code of the Hamming code consists of 4 bits of data and the remaining 3 bits are redundant bits.

The byte interleaver 114 fills the block coded data by the column of the matrix, and reads the data by row when the data is filled, so that the transmission of each bit within a byte occurs at a predetermined interval from each other.

By using the block coder 112 and the byte interleaver 114 as described above, when different colors, for example, R, G, and B LEDs are used, the boundary points of Red (R), Green (G), and Blue (B) are used. The possibility of errors that can occur can be greatly reduced.

The Manchester encoder 116 codes block coded and byte-interleaved transmission data using the Manchester method, as shown in FIG. Data coded by this coding scheme always has a change in signal value at the center of one bit, and by detecting this, the clock can be easily recovered. In addition, the data coded by the Manchester coding scheme can usually be maintained at the same high and low ratio 50%.

As such, when the LED module 154 is driven based on the data coded by the Manchester method, the operation ratio of the LED module 154 may be kept constant regardless of the transmission data input by the control device 300. For example, when the transmission data is {0,0,0 ..}, the LED module 154 may be prevented from operating.

As shown in FIG. 2, the PWM generation unit 130 may include a PWM module 132 and a distribution module 134. The PWM module 132 generates a pulse width modulation (PWM) signal corresponding to the color data input by the control device 300 and outputs it to the distribution module 134. The distribution module 134 selects and distributes the PWM signal to the driving elements Dr, Dg, and Db in response to the color data.

As illustrated in FIG. 3A, the PWM signal output from the PWM module 132 is generated to repeatedly drive the entire LED module 154 by a predetermined period T. The PWM signal generated in each of these periods T appears in front of each period T, as shown in FIG.

In addition, as shown in (a) of FIG. 3, the PWM signal is disposed so that the signals provided to the LED driver 152 to drive the respective driving elements Dr, Dg, and Db are not separated. As a result, each LED module 154 may maintain a state in which the operation section is not separated. That is, the signal coded from the coding unit 110 may be transmitted to the LED module 154 without interruption through the LED driver 152. In addition, it is possible to reduce overhead such as a preamble sent before a packet of transmission data each time.

In addition, since the driving period T of the PWM signal output from the PWM module 132 is determined to be shorter than the time for which the afterimage of the naked eye remains, the respective driving elements Dr, Dg, and Db driven in one period T are displayed. Several colors can be mixed together to create colorful colors. In addition, since the PWM generation unit 130 according to the present embodiment uses the PWM method, digital implementation may be easier than other driving methods.

The distribution module 134 outputs the PWM signal output from the PWM module 132 as shown in FIG. 3 (a), and outputs the signals 'S1', 'S2' and 'S3' as shown in FIG. It is selectively distributed to each AND gate element Gr, Gg, and Gb.

As shown in FIG. 2, the LED light emitting unit 150 includes an LED driver 152 and an LED module 154.

As shown in FIG. 2, the LED driver 152 includes AND gate elements Gr, Gg, and Gb and AND gate elements Gr, which receive signals output from the PWM generator 130 and the coding unit 110, respectively. It consists of driving elements Dr, Dg, and Db that receive signals output from Gg and Gb, respectively, and generate driving signals. The AND gate elements Gr, Gg, and Gb may be provided as digital elements that perform AND logic operations.

Each driving signal output from the driving elements Dr, Dg, and Db of the LED driver 152 drives the LED lamps Lr, Lg, and Lb of the LED module 154, and each of the LED lamps Lr, Lg, and Lb. ) Emits light in response to this drive signal. As such, the light emitted from the LED lamps Lr, Lg, and Lb serves as an optical signal corresponding to the transmission data TD and an illumination corresponding to the color data CD.

Among the waveforms shown in FIG. 3C, the waveform corresponding to the first {1,1,0} bit is input as 'Dr', and the waveform corresponding to the bit of {0,1} is 'Dg'. ', And the waveform corresponding to the bit of {1,0,1,1} is input as' Db'.

Hereinafter, the receiver 200 of the visible light communication system 1 according to the present embodiment will be described in detail with reference to FIG. 4.

The reception device 200 operates under the control of the control device 300 and includes a photoelectric conversion unit 210 and a decoding unit 230. The photoelectric conversion unit 210 includes a photoelectric sensor 212 for detecting and converting an optical signal emitted from the outside into an electrical signal, and an amplifier 214 for amplifying the electrical signal converted by the photoelectric sensor 212. The photoelectric sensor 212 may be mainly provided as a photodiode. The signal output from the photoelectric converter 210 is input to the Manchester decoder 232.

The Manchester decoder 232 decodes the input signal and processes the received signal into data in the form of NRZ pulses and recovers the original data through the byte deinterleaver 234 and the block decoder 236. The byte deinterleaver 234 and the block decoder 236 perform operations opposite to the above-described byte interleaver 114 and the block coder 112.

As such, the visible light communication system 1 according to the exemplary embodiment of the present invention may implement the color illumination as desired by the user and maintain the same communication performance as the visible light communication for the conventional monochromatic light.

Although not disclosed through the present embodiment, the visible light communication system according to the present invention may be implemented by various known hardware and software techniques.

1: visible light communication system 100: transmission device
110: coding unit 112: block coder
114: byteinterleaver 116: Manchester encoder
130: PWM generator 132: PWM module
134: distribution module 150: LED light emitting unit
152: LED driver 154: LED module
200: receiver 210: photoelectric conversion unit
212: photoelectric sensor 214; amplifier
230: decoding unit 232: Manchester decoder
234: byte deinterleaver 236: block decoder
300: controller

Claims (10)

A transmitter for coding input transmission data and modulating the coded transmission data into an optical signal having a plurality of colors;
A receiver for demodulating the received optical signals of a plurality of colors and decoding the demodulated optical signals; And
And a control device that controls each operation of the transmitting device and the receiving device. The method of claim 1,
The transmitting device generates a PWM signal corresponding to the color data input by the control device, and uses the generated PWM signal so that the coded transmission data is modulated into the multi-color light signal. Visible light communication system, characterized in that for driving. The method of claim 1,
The coded transmission data is a visible light communication system, characterized in that the coded by the Manchester coding scheme in which the high and low ratio of the signal is maintained the same. The method of claim 3,
And the coded transmission data is block coded and byte interleaved before being coded by the Manchester coding scheme. The method of claim 4, wherein
And said block coding is performed by a hamming code. Coding the input transmission data, and generates a PWM signal corresponding to the input color data, LED lamps having a plurality of colors so that the coded transmission data is modulated into a plurality of color light signal by using the generated PWM signal A transmission device for driving;
A receiver for demodulating the received optical signals of a plurality of colors and decoding the demodulated optical signals; And
And a control device that controls each operation of the transmitting device and the receiving device. The method of claim 6,
And the PWM signal repeatedly drives the entire LED lamps by a predetermined period, and the period is determined to be shorter than a time for which an after-image of the naked eye remains. The method of claim 6,
And the PWM signal repeatedly drives the entire LED lamps by a predetermined period, and the PWM signal is disposed in front of each period. The method of claim 6,
The transmitting device includes an LED driver including driving elements for driving each of the LED lamps, a PWM module for generating a PWM signal corresponding to the color data, and the driving signal for the PWM signal corresponding to the color data, respectively. And a PWM generation unit having a distribution module for selecting and distributing the visible light communication system. 10. The method of claim 9,
The LED driver further includes an AND gate device that receives and outputs each of the PWM signals and the coded transmission data distributed by the distribution module, and outputs them to the driving elements. system.

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