KR20110031082A - Visible light wireless communication method minimizing the brightness reduction of light source and enabling the dimming control of light source, and apparatus therefor - Google Patents

Abstract

PURPOSE: A visual light wireless communication method and a device for the same are provided to minimize the brightness reduction of a visual light source or a light device which is generated by a code for a communication and a demodulation function. CONSTITUTION: A coding and modulating unit(120) code and modulates each bit of a code which will transmits the code by at least one between a first modulating signal and a second modulating signal. The first modulating signal is for enabling light during a unit time in continuous on state. A second modulating signal is for generating the off/on of light within the unit time or generating on/off modification. A visible light source driving unit(130) drives the light by using a first modulating signal or a second modulating signal. The visible light source driving unit performs visible light wireless communication through the light.

Description

Visible light wireless communication method minimizing the brightness reduction of light source and enabling the dimming control of light source, and apparatus therefor}

The present invention relates to a visible light wireless communication method, and an apparatus therefor. More particularly, the present invention relates to a visible light wireless communication coding and modulation method capable of minimizing brightness reduction of a light source and adjusting the brightness of the light source, and an apparatus therefor.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task management number: 2008-F-009-02, Project name: IT lighting communication convergence 380 ~ 780 nano] Meter Visible RGB Screening Wireless Communication Research].

In accordance with the recent changes in the energy environment and the reduction of global greenhouse gases, lighting fixtures and display devices using LED (Light Emitting Diode) have been applied to automobiles, traffic lights, billboards, TVs, monitors, mobile devices, special lighting and general lighting. It is rapidly spreading in daily life. In addition, wireless communication technologies have been actively researched to add a communication function to LED lighting devices and display devices to simultaneously achieve the purpose of the LED light source and the purpose as a communication means.

This is because an LED light source has a long life, excellent power efficiency, various colors, and digital control. In addition, the realistic situation of mandatory energy reduction and greenhouse gas reduction in accordance with the entry into force of the United Nations Climate Change Convention's Kyoto Protocol is one of the reasons why countries around the world are rapidly replacing existing light sources with LED light sources. .

Visible light wireless communication technology is a wireless communication technology that transmits information wirelessly using light in the visible light wavelength band (380n ~ 780nm region) that can be recognized by the human eye. This technology is distinguished from the conventional wired optical communication technology in that it uses light in the visible wavelength band.

In addition, unlike the RF (Radio Frequency) wireless communication which is currently widely used, visible light wireless communication technology is excellent in convenience and physical security that can be freely used without any regulation or permission in terms of frequency use, and users can easily view the communication link. It has the distinction of being able to confirm, and above all, it is characterized as a convergence technology that can attain the unique purpose and communication function of the light source at the same time.

The transmission and reception structure of the visible light wireless communication system may be designed in various ways according to analog and digital communication methods. In addition, various electrical modulation and demodulation methods for analog and digital communication methods can be designed in various ways, and studies on this are being actively conducted.

On the other hand, in the digital visible light wireless communication system using the LED light source, since it is difficult for the receiver to detect information on the phase of the transmitted optical signal, the electrical data signals "0" and "1" are changed to the intensity of the visible light signal as shown in FIG. Modulation strength modulation method or OOK (On-Off Keying) modulation method is generally applied, which has the advantage of relatively simple configuration.

2 is a transfer function graph illustrating the intensity of an output visible light signal according to a change in applied current or voltage of a general LED light source, and an intensity modulation method or OOK for modulating electrical data signals "0" and "1" into a change in intensity of a visible light signal; (On-Off Keying) This is a graph showing the principle of the modulation method, and as shown in Fig. 1, the transmission unit of a general digital communication system defines the digital signals " 0 " and " 1 " It has a coding block that maps to a signal waveform of "1". Depending on the characteristics of a system, coding techniques such as non-return-to-zero (NRZ), return-to-zero (RZ), and Manchester are mainly used.

3 is a diagram illustrating waveforms of visible light signals output from a transmitter when the NRZ coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1, and FIG. 4 is a digital visible light radio of FIG. When the RZ coding method and the OOK modulation method are applied to the transmitter of the communication system, the waveform of the visible light signal output from the transmitter is shown. 5 illustrates waveforms of a visible light signal output from a transmitter when the Manchester coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1.

On the other hand, when the coding method as shown in Figs. 3 to 5 is applied, the average output of the optical signal output from the visible light source of the transmitter is stochastic when the number of data "1" and "0" is equally equal. The OOK and Manchester-OOK coding and modulation methods are equivalent to the optical output when a signal equal to half the size of the data "1" signal is constantly applied. In the RZ-OOK coding and modulation methods, the NRZ-OOK and Manchester- The optical signal is smaller than that of the OOK coding and modulation method. For example, FIG. 6 shows an average light output of a visible light signal output by the Manchester-OOK coding and modulation method.

Therefore, if the coding and modulation method as shown in Figs. 3 to 5 is applied to the transmitter of the visible light wireless communication system, only half or less of the light output power that the actual LED light source can output is radiated. The disadvantage is that it does not provide enough brightness.

Of course, in the coding and modulation method as shown in Figs. 3 to 5, the average light output of the light source can be increased by greatly increasing the amplitude of the electrical data signal or adding the DC component (see Figs. 7 and 8). In addition, exceeding the driving allowance of the LED light source (or illumination) greatly shortens the life of the light source, which is not an efficient method.

In addition, if the size of the modulation signal is adjusted to increase the average light output of the light source, the brightness may be controlled to some extent, but in this case, the color of the light source may not be kept constant.

In addition, the digital visible light wireless communication system of FIG. 1 to which the coding and modulation methods of FIGS. 3 to 5 are applied does not have an input port of a control signal for adjusting the change of the brightness of the light source, making it difficult to adjust the brightness of the light source. Even if it has an input port of a control signal for adjusting the brightness can be adjusted only within a very limited range as described above.

The present invention has been proposed to solve the above problems,

When the visible light wireless communication transmission function is added to a lighting device or a visible light source that emits visible light, the brightness reduction of the lighting device or the visible light source generated by the communication coding and modulation function is minimized, and the brightness of the lighting device or the visible light source is simultaneously reduced. An object of the present invention is to provide an adjustable visible light wireless communication method and an apparatus therefor.

In addition, another object of the present invention is to control the brightness of the visible light source and at the same time the color of the light source can be kept constant, visible light wireless communication method that does not exceed the driving allowance of the visible light source does not cause a shortening of the visible light source and the same It is to provide a device for.

In addition, another object of the present invention is to use the additional line coding function that can prevent the flicker of the visible light in combination with the coding and modulation method according to the present invention, the brightness of the light source can be adjusted and flickering does not appear A visible light wireless communication method and apparatus therefor are provided.

The visible light wireless transmitter according to the embodiment of the present invention, each bit of the code to be transmitted, the first modulated signal to keep the lighting on for a unit of time and the lighting is turned off / on or on / within the unit time A coding and modulation unit for coding and modulating one of the second modulated signals to cause an off transition to occur; And a visible light source driver for driving the illumination using the first modulated signal or the second modulated signal to process visible light wireless communication through the illumination.

In particular, the second modulated signal is characterized in that one off / on or on / off transition occurs within the unit time.

The controller may further include a controller configured to adjust the brightness of the illumination by controlling a time point at which the off / on or on / off transition of the second modulated signal occurs according to the brightness control signal input from the outside. .

The control unit may further include setting a first modulation signal and a unit for each bit of the code to keep the lighting off for a unit time when the brightness adjustment value of the illumination included in the brightness adjustment signal is equal to or less than a set value. And control the coding and modulator to be coded and modulated with any one of the second modulated signals to cause an off / on or on / off transition of illumination within time.

In addition, the signal level of the first modulated signal for keeping the illumination in the on state and the signal level of the second modulated signal for the illumination in the on state is the same.

In addition, the signal level of the first modulated signal for keeping the illumination in the on state and the signal level of the second modulated signal for the illumination in the on state is characterized in that less than the driving allowance of the illumination.

The coding and modulation unit may recognize source codes as source codes in units of a first number of bits, and encode each of the source codes in an encoding code of units of a second number of bits larger than the first number. The apparatus may further include a line coding unit to transmit to the encoding code, wherein the encoding code is equal to the number of bits corresponding to 1 and the number of bits corresponding to 0.

The first number is four, and the second number is six.

The line coding unit may include the source codes “0000”, “0001”, “0010”, “0011”, “0100”, “0101”, “0110”, “0111”, “1000”, “1001”, "1010", "1011", "1100", "1101", "1110", and "1111" are the encoding codes "001110", "001101", "010011", "010110", "010101", and "100011" respectively. "," 100110 "," 100101 "," 011001 "," 011010 "," 011100 "," 110001 "," 110010 "," 101001 "," 101010 "," 101100 "characterized by encoding .

On the other hand, the visible light wireless communication method according to an embodiment of the present invention, the optical signal receiving unit for receiving the visible light signal from the visible light source to convert the visible light signal into an electrical signal; And demodulating a section in which the visible light source is continuously turned on in the unit time using the electrical signal to the first bit, and demodulating a section in which the off / on or on / off transition of the visible light source occurs in the unit time to the second bit. And a decoding unit.

In particular, the data pattern output from the demodulation and decoding unit recognizes the received codes in the unit of the first number of bits, and each of the received codes is a decoding code in the unit of the second number of bits smaller than the first number. The apparatus may further include a line decoding unit configured to decode the PDU, wherein each of the received codes has the same number of bits as 1 and the number of bits corresponding to 0.

In the visible light wireless communication method according to an embodiment of the present invention, the visible light wireless communication transmitter, each bit of the code to be transmitted, the first modulation signal and the illumination within the unit time to keep the lighting on for a unit time Coding and modulating with any of the second modulated signals to cause off / on or on / off transitions; And driving the illumination using the first modulated signal or the second modulated signal to process visible light wireless communication through the illumination.

According to the present invention, the following effects can be expected.

In addition to the transmission of visible light wireless communication to a lighting device or a visible light source that emits visible light, a reduction in the brightness of the lighting device or visible light source generated by the communication coding and modulation function can be minimized, and at the same time, the brightness of the lighting device or visible light source can be reduced. I can regulate it.

In addition, even if the brightness of the visible light wireless communication lighting device or the visible light source is adjusted by the communication coding and modulation function, the lighting state level of the light corresponding to the digital "0" signal and the lighting state level corresponding to the digital "1" signal are the same. The color of the light source can be kept constant.

In addition, when the communication coding and modulation function provides the maximum brightness of the visible light wireless communication lighting device or the visible light source, the ON state level of the light corresponding to the digital "0" signal and the ON state level corresponding to the digital "1" signal are displayed. The light source can be protected because it does not exceed the driving allowance of.

In addition, by adding a line coding function for preventing flicker of the visible light source, flickering of the light source detected by the human eye does not occur in the visible light output signal.

In addition, by selectively using the reverse return-to-zero (RRZ) coding method and the existing return-to-zero (RZ) coding method according to the present invention, it is possible to further increase the brightness control range of the light source.

In addition, there is no need for a separate driving circuit for controlling the brightness of the visible light source such as LED and a separate circuit for receiving the communication signal of the visible light wireless communication, and transmitting the visible light wireless communication function to the lighting device or the visible light source. The addition of the transmitter does not complicate the configuration of the transmitter.

In addition, even if the visible light wireless communication function is added to the lighting device or the visible light source, the lighting function or the unique function of the visible light source is not impaired. There is an effect that can reduce the power consumption of the transmitter than when there are separate circuits to accommodate each other.

FIG. 1 is a diagram schematically illustrating a function of a transmitter of a general digital visible light wireless communication system.
2 is a transfer function graph illustrating the intensity of an output visible light signal according to a change in applied current or voltage of a general LED light source.
FIG. 3 illustrates waveforms of a visible light signal output from the transmitter when the NRZ coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1.
4 illustrates waveforms of a visible light signal output from the transmitter when the RZ coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1.
FIG. 5 illustrates waveforms of a visible light signal output from the transmitter when the Manchester coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1.
FIG. 6 illustrates an average light output of a visible light signal output from the transmitter when the Manchester coding method and the OOK modulation method are applied to a transmitter of a digital visible light wireless communication system as shown in FIG. 1.
7 illustrates a principle of exceeding a driving allowance range of a light source as the amplitude of a driving signal is greatly increased to increase an average light output of a visible light signal output from a transmitter of a digital visible light wireless communication system as shown in FIG. 1. It shows the OOK coding and modulation method.
FIG. 8 illustrates a principle of exceeding a driving allowance of a light source by applying a DC-offset level to a drive signal to increase an average light output of a visible light signal output from a transmitter of a digital visible light wireless communication system as shown in FIG. It shows the OOK coding and modulation method.
9 is a view for explaining the configuration of a visible light wireless communication transmitter according to an embodiment of the present invention.
FIG. 10 is a diagram illustrating a 4B6B line code as an example of a line code applicable to prevent flicker of a visible light signal output from a visible light wireless communication transmitter of the present invention.
11 is a digital "0" signal in the coding and modulation method according to the present invention is defined as an electrical signal in which the on state of illumination is maintained unchanged in one cycle of communication, the digital "1" signal is turned on when the illumination is off When defined as an electrical signal that transitions to a state, the waveform of the modulation signal corresponding to each electrical signal is shown.
12 is a digital "0" signal in the coding and modulation method according to the present invention is defined as an electrical signal that transitions from the off state to the on state, the digital "1" signal is a state in which the illumination state in one cycle of communication When defined as an electrical signal that remains unchanged, the waveform of the modulation signal corresponding to each electrical signal is shown.
13 is a digital "0" signal in the coding and modulation method according to the present invention is defined as an electrical signal in which the on state of the lighting remains unchanged in one cycle of communication, the digital "1" signal is turned on when the illumination is off When defined as an electrical signal that transitions to a state, when the duty ratio of the digital "1" signal is 50%, the waveform of the modulation signal corresponding to the "01100101" data pattern is shown.
14 is a digital "0" signal in the coding and modulation method according to the present invention is defined as an electrical signal in which the on state of the light remains unchanged in one cycle of communication, the digital "1" signal is turned on when the light is off When defined as an electrical signal that transitions to a state, the principle that the brightness of the visible light transmitting light source is controlled by changing the duty ratio of the digital "1" signal in the range of 25% to 87.5% is represented by the waveform of the modulated signal.
15 is a digital "0" signal in the duty-adjustable RZ coding method is an electrical signal in which the off state of the light remains unchanged in one cycle of communication, and the digital "1" signal transitions from the off state to the on state. When defined as an electrical signal, the waveform of the modulation signal corresponding to each electrical signal is shown.
16 is a digital "0" signal in the duty-adjustable RZ coding method is an electrical signal that transitions from the off state to the on state, the digital "1" signal is maintained in the off state of the light in one cycle of communication unchanged When defined as an electrical signal, the waveform of the modulation signal corresponding to each electrical signal is shown.
17 is a digital "0" signal in the duty-adjustable RZ coding method is an electrical signal in which the off state of the light remains unchanged in one cycle of communication, and the digital "1" signal transitions from the off state to the on state. When defined as an electrical signal, the principle that the brightness of the visible light transmitting light source is adjusted by changing the duty ratio of the digital "1" signal in the range of 25% to 87.5% is represented by the waveform of the modulation signal.
FIG. 18 is a view to show that the brightness control range of the light source can be doubled by using the RZ coding method capable of adjusting the duty, the coding method according to the present invention, and the OOK modulation method in parallel.
19 is a view for explaining the configuration of a visible light wireless communication receiver according to an embodiment of the present invention.
20 is a flowchart illustrating a visible light wireless communication method according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Here, the repeated description, well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention, and detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more completely describe the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity.

9 is a view for explaining the configuration of a visible light wireless communication transmitter according to an embodiment of the present invention.

9, the visible light wireless communication transmitter 100 according to the present invention includes a line coding unit 110, a coding and modulation unit 120, a visible light source driving unit 130, an optical signal output unit 140, and The control unit 150 is provided.

The line coding unit 110 receives a source code to be transmitted through visible light, recognizes the received source code as a source code in units of a first number of bits, and recognizes each of the source codes larger than the first number. Coding is performed using an encoding code of two bits and transmitted to the coding and modulation unit 120. In this case, the illumination may correspond to the optical signal output unit 140.

In this case, the first number may be four, and the second number may be six. That is, the line coding of the present invention may be 4B6B line coding (see FIG. 10).

In this case, the encoding code is the same as the number of bits corresponding to 1 and the number of bits corresponding to 0.

Referring to FIG. 10, sixteen four-bit data corresponds to one of sixteen six-bit patterns, two six-bit patterns “110100” and “001011” are set to a preamble pattern, and two It can be seen that the 6 bit patterns "111000" and "000111" are set to an idle pattern.

The criterion for selecting a pattern in the line code is whether the number of consecutive 1s or 0s is possible when the selected pattern is used. The number of consecutive ones or zeros is commonly referred to as run length.

In the conventional 4B5B, when 7 (0111) is followed by 0 (0000), the encoding code "01111" comes after the encoding code "11110", so the run length is 8. This long run length was a serious obstacle for the existing 4B5B to be used for data and clock recovery.

However, the 4B6B line coding according to the present invention can reduce run length to four.

To this end, “111000” and “000111” among six 6-bit patterns having the same number of twenty ones and zeros may be used as idle patterns. That is, if "111000" and "000111" are not used for data transmission / reception, the occurrence of run length 6 can be eliminated.

If "111000" and "000111" are not used as the data pattern and 16 are selected from the remaining 18 6-bit patterns and used for data transmission / reception, the run length is reduced to 4.

In visible light communication, OOK (On-Off Keying) modulation is mainly used in which the LED is turned on when data is 1 and the LED is turned off when 0. In this case, the data 1 and the data 0 correspond to different voltage or current levels, respectively, and the voltage / current level corresponding to the data 1 may be higher or lower than the voltage / current level corresponding to the data 0.

When 4B6B line coding according to the present invention is used, no matter what source code is transmitted, the brightness remains constant at 50%, so there is no change in the brightness of the light according to data transmission / reception and no flickering of the light occurs.

The coding and modulation unit 120 causes each bit of the source code (encoding code) encoded by the line coding unit 110 to keep the lighting on for a unit of time (ie, one period of communication). Coded and modulated with any one of the first modulated signal and a second modulated signal that causes an off / on or on / off transition of illumination to occur within a unit time. Hereinafter, a coding scheme used in the present invention, that is, a coding scheme in the coding and modulation unit 120 will be defined as reverse return-to-zero (RRZ) coding.

Referring to FIGS. 11 to 13, when (a) of FIG. 11 defines a digital "0" signal as an electrical signal in which an on state of lighting is maintained without change in one cycle of communication in the RRZ coding method according to the present invention. The waveform of the first modulated signal corresponding thereto is shown. 11B illustrates a waveform of the second modulated signal corresponding to the digital “1” signal when the digital “1” signal is defined as an electrical signal that is changed from an off state to an on state in the RRZ coding method according to the present invention. It is shown. Of course, it is also possible to define a digital "1" signal as an electrical signal that transitions from an on state to an off state. FIG. 13 illustrates a waveform of a modulation signal corresponding to the data pattern "01100101" when the duty ratio of the digital "1" signal is 50% when defining the modulation signal corresponding to each electrical signal as shown in FIG.

12A illustrates a waveform of a second modulated signal corresponding to a digital “0” signal as an electrical signal that transitions from an off state to an on state in the RRZ coding method according to the present invention. It is shown. Here too, it is also possible to define a digital "0" signal as an electrical signal that transitions from an on state to an off state. 12 (b) shows a first modulation corresponding to the digital “1” signal when the digital “1” signal is defined as an electrical signal in which an on state of lighting is maintained without change in one cycle of communication in the RRZ coding method according to the present invention. The waveform of the signal is shown.

In this case, the second modulated signal causes one off / on or on / off transition to occur in one cycle of communication, and a time point at which the off / on or on / off transition occurs in the second modulated signal (duty ratio). Is changeable.

Referring to FIG. 14, FIG. 14 defines a digital "0" signal as an electrical signal in which an ON state of lighting is maintained without change in one cycle of communication in the RRZ coding method according to the present invention, and the digital "1" signal is an illumination. When defined as an electrical signal that transitions from the off state to the on state, the duty ratio of the digital "1" signal is changed from 25% to 87.5%, for example, to control the brightness of the visible light source. As shown by the waveforms, FIGS. 14A, 14B, 14C, and 14D show waveforms of the modulated signal when the duty ratios are 25%, 50%, 75%, and 87.5%, respectively. That is, by adjusting the duty ratio of the second modulated signal, it is possible to adjust the brightness of the visible light source output through the illumination.

In addition, in order to maintain a constant color of the visible light output through the illumination, it is preferable to make the signal level of the first modulated signal in which the illumination is continuously turned on equal to the signal level of the turned on state of the second modulated signal. .

In addition, it is preferable that the signal level of the first modulated signal and the signal level of the turned on state of the second modulated signal in which the illumination is continuously turned on do not exceed the driving allowance of the illumination to prevent the life of the illumination from being shortened.

In addition, the coding and modulating unit 120 controls each bit of the source code (encoding code) encoded by the line coding unit 110 to generate the first modulated signal and the unit time so that the illumination is continuously turned off for a unit time. It can be modulated with either of the second modulated signals to cause an off / on or on / off transition of illumination within. That is, the coding and modulator 120 may use Return-to-Zero (RZ) coding.

15 to 17, FIG. 15A defines a digital "0" signal as an electrical signal in which an off state of an illumination is maintained without change in one cycle of communication in an RZ coding method capable of adjusting a duty ratio. In this case, the waveform of the first modulated signal corresponding thereto is shown. 15B illustrates a waveform of the second modulated signal corresponding to the digital “1” signal when the digital “1” signal is defined as an electrical signal that is changed from an off state to an on state in an RZ coding method capable of adjusting a duty ratio. It is shown. Of course, it is also possible to define a digital "1" signal as an electrical signal that transitions from an on state to an off state.

Meanwhile, (a) of FIG. 16 illustrates a waveform of a second modulated signal corresponding to a digital “0” signal when the digital “0” signal is defined as an electrical signal that transitions from an off state to an on state in an RZ coding method in which the duty is adjustable. It is shown. Here too, it is also possible to define a digital "0" signal as an electrical signal that transitions from an on state to an off state. 16B illustrates a first digital signal corresponding to a digital “1” signal as an electrical signal in which an off state of lighting is maintained without change in one cycle of communication in an RZ coding method capable of adjusting a duty ratio. The waveform of the modulation signal is shown.

In this case, the second modulated signal causes one off / on or on / off transition to occur in one cycle of communication, and a time point at which the off / on or on / off transition occurs in the second modulated signal may be changed. .

Referring to FIG. 17, FIG. 17 defines a digital "0" signal as an electrical signal in which an on state of lighting is maintained without change in one cycle of communication in an RZ coding method capable of adjusting a duty ratio. When the lighting is defined as an electrical signal that transitions from off to on, the waveform of the modulated signal is controlled by changing the duty ratio of the digital "1" signal in the range of 25% to 87.5%. As shown in FIG. 17, (a), (b), (c), and (d) show waveforms of a modulated signal when the duty ratios are 25%, 50%, 75%, and 87.5%, respectively. That is, by adjusting the duty ratio of the second modulated signal, it is possible to adjust the brightness of the visible light source output through the illumination.

Meanwhile, reverse return-to-zero (RRZ) coding or return-to-zero (RZ) coding performed by the coding and modulator 120 may be selectively performed under the control of the controller 150. This will be described in more detail in the description of the controller 150 to be described later.

The visible light driver 130 drives the illumination by receiving the first modulated signal or the second modulated signal to process visible light wireless communication through the light.

The optical signal output unit 140 transmits the visible light signal to the visible light wireless communication receiver under the control of the visible light source driver 130. For example, the optical signal output unit 140 may be a lighting device composed of one or more light emitting diode (LED) light sources.

The controller 150 controls the time (that is, duty ratio) when the off / on or on / off transition of the second modulation signal occurs according to the brightness control signal input from the outside (eg, the user) to adjust the brightness of the lighting. Adjust

At this time, the controller 150 compares the brightness adjustment value of the illumination included in the brightness adjustment signal with a set value (eg, 50%). As a result of the comparison, if the brightness adjustment value of the illumination is less than or equal to the set value, each bit of the encoding code is turned off / on or on / within the first modulated signal and the unit time to keep the illumination off for unit time. The coding and modulator 120 is controlled to be modulated with any one of the second modulated signals to cause an off transition.

According to the above (that is, the RZ coding method and the OOK modulation method capable of adjusting the duty ratio in the coding and modulation unit or the RRZ coding method and the OOK modulation method according to the present invention can be selectively used), the brightness control range of the light source Can be doubled. Referring to FIG. 18, it can be seen that the brightness control range of the light source is doubled by using the RZ coding method capable of adjusting the duty, the coding method according to the present invention (RRZ coding method), and the OOK modulation method in parallel. In FIG. 18, (a) illustrates a case in which an RZ coding method and a OOK modulation method in which the duty ratio is adjustable, and (b) illustrates a case in which the RRZ coding method and the OOK modulation method according to the present invention are used.

19 is a view for explaining the configuration of a visible light wireless communication receiver according to an embodiment of the present invention.

Referring to FIG. 19, the visible light wireless communication receiver 100 includes an optical signal receiver 210, a demodulation and decoding unit 220, and a line decoding unit 230.

The optical signal receiver 210 receives the visible light signal output from the visible light wireless communication transmitter according to the present invention, and converts the received visible light signal into an electrical signal.

The demodulation and decoding unit 220 uses the electrical signal converted by the optical signal receiving unit 210 to determine a period in which the visible light source is continuously turned on within a unit time (that is, one cycle of communication). Demodulate to ") and demodulate the section in which the visible light source is turned off / on or the on / off transition occurs within a unit time to a second bit (eg, '1').

The line decoding unit 230 recognizes the data pattern output from the demodulation and decoding unit 220 as reception codes of a first number of bits, and each of the recognized reception codes is a second number smaller than the first number. Line-decode the decoding code in units of bits. In this case, each of the reception codes has the same number of bits corresponding to 1 and number of bits corresponding to 0.

In this case, the first number may be six and the second number may be four.

Also, the line decoding unit 230 receives the reception codes "001110", "001101", "010011", "010110", "010101", "100011", "100110", "100101", "011001", "011010" , "011100", "110001", "110010", "101001", "101010", and "101100" respectively represent the decoding codes "0000", "0001", "0010", "0011", "0100" and " 0101 "," 0110 "," 0111 "," 1000 "," 1001 "," 1010 "," 1011 "," 1100 "," 1101 "," 1110 "," 1111 "can be decoded.

20 is a flowchart illustrating a visible light wireless communication method in a visible light wireless communication transmitter according to an embodiment of the present invention.

Referring to FIG. 20, the visible light wireless communication transmitter according to the present invention receives a source code for visible light wireless communication (S100). In this case, the reception is not only received through a communication channel or the like but also encompasses a signal transmission in the device.

In addition, the visible light wireless transmitter performs 4B6B line coding on the received source code in order to remove flickering of lights that may occur when transmitting data using visible light (S110). More specifically, the visible light wireless transmitter recognizes the received source code as source codes in units of 4 bits. The visible light wireless transmitter encodes each of the source codes into a 6-bit encoding code in which the number of bits corresponding to 1 and the number of bits corresponding to 0 are the same.

Next, the visible light wireless communication transmitter receives a brightness control signal input from the outside (S120), and determines the coding scheme (RRZ coding or RZ coding) of the encoding code according to the received brightness control signal (S130).

When the coding scheme is determined through the step S130, the visible light wireless transmitter modulates each bit of the encoding code into a first modulated signal or a second modulated signal using the determined coding scheme (S140). Assuming the RRZ scheme is determined as the encoding scheme, the visible light radio transmitter transmits each bit of the encoding code to the first modulated signal and the illumination is turned on / off or on within the unit time to keep the lighting on for a unit time. Modulate with either of the second modulated signals to cause the on / off transition to occur. For example, a digital "0" signal modulates with a first modulated signal that keeps the light on in one cycle of communication unchanged, while the digital "1" signal is off / on or on / on in one cycle of communication. Modulate with a second modulated signal to cause an off transition to occur.

Next, the visible light wireless communication transmitter drives the lighting using the first modulated signal or the second modulated signal generated through step S140 to process visible light wireless communication through the lighting (S150).

According to the above, the addition of the transmission function for the visible light wireless communication to the lighting device or the visible light source that emits visible light can minimize the decrease in brightness of the lighting device or the visible light source generated by the communication coding and modulation function, and at the same time You can adjust the brightness of the visible light source.

In addition, even if the brightness of the visible light wireless communication lighting device or the visible light source is adjusted by the communication coding and modulation function, the lighting state level of the light corresponding to the digital "0" signal and the lighting state level corresponding to the digital "1" signal are the same. The color of the light source can be kept constant.

In addition, when the communication coding and modulation function provides the maximum brightness of the visible light wireless communication lighting device or the visible light source, the ON state level of the light corresponding to the digital "0" signal and the ON state level corresponding to the digital "1" signal are displayed. The light source can be protected because it does not exceed the driving allowance of.

In addition, by adding a line coding function for preventing flicker of the visible light source, flickering of the light source detected by the human eye does not occur in the visible light output signal.

In addition, by selectively using the RRZ coding method according to the present invention and the existing RZ coding method in parallel, it is possible to further increase the brightness control range of the light source.

In addition, there is no need for a separate driving circuit for controlling the brightness of the visible light source such as LED and a separate circuit for receiving the communication signal of the visible light wireless communication, and transmitting the visible light wireless communication function to the lighting device or the visible light source. The addition of the transmitter does not complicate the configuration of the transmitter.

In addition, even if the visible light wireless communication function is added to the lighting device or the visible light source, the lighting function or the unique function of the visible light source is not impaired, and a dedicated driving circuit for controlling the brightness of the light source and the communication signal of the visible light wireless communication are applied. There is an effect that can reduce the power consumption of the transmitter than when there are separate circuits to accommodate each other.

As described above, the best embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

100: visible light wireless communication transmitter 110: line coding unit
120: coding and modulator 130: visible light source driver
140: light signal output unit 150: control unit
200: visible light wireless communication receiver 210: optical signal receiver
220: demodulation and decoding unit 230: line decoding unit

Claims (20)

Each bit of the code to be transmitted is either a first modulated signal that keeps the light on for a unit time and a second modulated signal that causes the light to turn off / on or on / off transition within the unit time. A coding and modulation unit for coding and modulating; And
And a visible light source driver for driving the illumination using the first modulated signal or the second modulated signal to process visible light wireless communication through the light. The method according to claim 1,
The second modulated signal is,
And wherein said one off / on or on / off transition occurs within said unit time. The method according to claim 1,
And controlling the brightness of the illumination by controlling a time point at which the off / on or on / off transition of the second modulated signal occurs according to a brightness control signal input from the outside. Wireless transmitter. The method according to claim 3,
The control unit,
When the brightness control value of the illumination included in the brightness control signal is less than or equal to a set value, each bit of the code is turned off / on within the first modulation signal and the unit time to keep the illumination off for unit time. And controlling the coding and modulating unit to be coded and modulated with any one of the second modulated signals to cause on or on off transitions. The method according to claim 1,
And the signal level of the first modulated signal for keeping the illumination on and the signal level of the second modulated signal for bringing the illumination on are the same. The method according to claim 5,
And the signal level of the first modulated signal for keeping the illumination on and the signal level of the second modulated signal for causing the illumination to be on are less than or equal to the driving tolerance of the illumination. The method according to claim 1,
Recognizes source code as source codes in units of a first number of bits, encodes each of the source codes into an encoding code of units of a second number of bits larger than the first number, and transmits the encoded code to the coding and modulation unit. Further provided with a line coding unit,
The encoding code is a visible light wireless transmitter, characterized in that the number of bits corresponding to 1 and the number of bits corresponding to 0. The method according to claim 7,
And said first number is four, and said second number is six. The method according to claim 8,
The line coding unit,
The source code "0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011" , "1100", "1101", "1110", and "1111" respectively represent the encoding codes "001110", "001101", "010011", "010110", "010101", "100011", "100110", " 100101 "," 011001 "," 011010 "," 011100 "," 110001 "," 110010 "," 101001 "," 101010 "," 101100 ", characterized in that the visible light wireless transmitter. An optical signal receiver configured to receive a visible light signal from a visible light source and convert the visible light signal into an electrical signal; And
Demodulation for demodulating the section in which the visible light source is continuously turned on by the first bit using the electrical signal and demodulating the section where the off / on or on / off transition of the visible light source occurs within the unit time to the second bit. And a decoding unit. The method according to claim 10,
Recognize the data pattern output from the demodulation and decoding unit as received codes of a first number of bits, and decode each of the received codes into a decoding code of a second number of bits smaller than the first number. Further provided with a line decoding unit,
And each of the reception codes is the same as the number of bits corresponding to one and the number of bits corresponding to zero. The method of claim 11,
And wherein the first number is six, and the second number is four. The method of claim 11,
The line decoding unit,
The reception code "001110", "001101", "010011", "010110", "010101", "100011", "100110", "100101", "011001", "011010", "011100", "110001" , &Quot; 110010 "," 101001 "," 101010 ","101100", respectively, the decoding codes" 0000 "," 0001 "," 0010 "," 0011 "," 0100 "," 0101 "," 0110 "and" 0111 "," 1000 "," 1001 "," 1010 "," 1011 "," 1100 "," 1101 "," 1110 "," 1111 ", characterized in that the decoding of any visible light wireless communication receiver. Visible light wireless transmitter,
Each bit of the code to be transmitted is either a first modulated signal that keeps the light on for a unit time and a second modulated signal that causes the light to turn off / on or on / off transition within the unit time. Coding and modulating; And
And driving the illumination using the first modulated signal or the second modulated signal to process visible light wireless communication through the light. The method according to claim 14,
The second modulated signal is,
And wherein said one off / on or on / off transition occurs within said unit time. The method according to claim 14,
The off-on or on-off transition of the second modulated signal is changed according to the brightness control signal input from the outside, visible light wireless communication method. The method according to claim 14,
And the signal level of the first modulated signal for keeping the illumination on and the signal level of the second modulated signal for bringing the illumination on are the same. 18. The method of claim 17,
And the signal level of the first modulated signal for keeping the illumination in the on state and the signal level of the second modulated signal for the illumination in the on state are less than or equal to the driving allowance of the illumination. The method according to claim 14,
Recognizing the source code as source codes in units of a first number of bits, encoding each of the source codes into an encoding code in units of a second number of bits greater than the first number,
The encoding code is a visible light wireless communication method, characterized in that the number of bits corresponding to 1 and the number of bits corresponding to 0. The method of claim 19,
Wherein the first number is four and the second number is six.

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