JP2010103851A - Visible light communication system and transmission-side apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visible light communication system which reduce noise generation even when they are loaded on a vehicle, and to provide a transmission-side apparatus. <P>SOLUTION: A transmission-side apparatus 100 includes a left headlight 120 and a right headlight 130 which emit visible light B1 and B2, respectively, an operating part 140 which sets brightness of the visible light B1 and B2, and a controller 110 which generates a first PWM signal and a second PWM signal for driving the left headlight 120 and the right headlight 130, respectively, so that the brightness becomes the set brightness. When communication data are at a logic H level, the controller 110 generates and outputs the same signal as a first PWM signal as a second PWM signal; and when communication data are at a logic L level, the controller generates and outputs, as a second PWM signal, a signal in which a first PWM signal has been delayed by a predetermined delay time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a visible light communication system that transmits and receives communication data using visible light between a transmission side device and a reception side device, and a transmission side device that constitutes the visible light communication system.

Conventionally, a technique described in Patent Document 1 is known as this type of visible light communication system and transmission side device. In the technique described in this document, the transmission side device converts a communication data into a PPM signal and modulates a subcarrier (carrier signal) using the PPM signal, and generates a modulation signal, A drive signal generation unit that generates a drive signal by embedding this modulation signal in a dimming signal (PWM signal) that changes the luminance of visible light emitted from the light emitting element, and controls the light emission of the light emitting element using this drive signal And a drive unit for Thereby, the transmission side apparatus can transmit the said communication data using visible light, adjusting the brightness | luminance of visible light.
JP 2007-97071 A

  However, when the wireless communication system (transmission side device) using the visible light is mounted on a vehicle, there is a concern that the following problems may occur.

  Specifically, in order not to affect the luminance of visible light, the frequency of the modulation signal needs to be sufficiently higher than the frequency of the dimming signal. Therefore, the drive signal generated by embedding the modulation signal in the dimming signal is a high-frequency signal. Normally, the drive signal, which is a high-frequency signal, is transmitted to the in-vehicle light via the wire harness, so that the radio wave is emitted when the wire harness operates as an antenna. The radio wave thus generated acts as noise on other in-vehicle devices, and there is a concern that noise may enter the in-vehicle radio or cause malfunction of other in-vehicle devices.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a visible light communication system and a transmission-side device capable of reducing noise generation even when mounted on a vehicle. There is to do.

  In order to achieve such an object, according to the first aspect of the present invention, the visible light that transmits and receives communication data between the transmission side device and the reception side device using the visible light having the luminance set based on the manual operation of the user. In the communication system, the transmission-side device includes a first light-emitting unit and a second light-emitting unit that emit the visible light, and a first for driving the first light-emitting unit to have the set luminance. A first drive signal generation unit that generates a drive signal, and a second drive signal for driving the second light emitting unit to have the set luminance, the same signal as the first drive signal and the first drive signal A second drive signal generation unit configured to generate one of the signals obtained by delaying one drive signal for a predetermined time according to the logic level of the communication data, and the reception-side device includes: The visible light emitted is the first light reception signal A first light-receiving unit that receives light as a second light-receiving signal, and a delay between the first light-receiving signal and the second light-receiving signal. And a data extraction unit that extracts a logical level of the communication data based on the presence or absence of the communication data.

  In the above-described configuration as the visible light communication system, the predetermined time is longer than the lower limit value at which the delay can be detected by the data extraction unit and shorter than the upper limit value that does not affect the luminance of visible light. It is possible. When such a predetermined time is employed, the second drive signal generation unit generates a signal that is the same as the first drive signal and a signal obtained by delaying the first drive signal for a predetermined time as the second drive signal, at the logic level of the communication data. Accordingly, the data extraction unit extracts the logic level of the communication data based on the presence or absence of a delay between the first light receiving signal and the second light receiving signal. This makes it possible to transmit communication data without using the first drive signal and the second drive signal as high-frequency signals, unlike the above-described prior art in which the drive signal must be a high-frequency signal. . Therefore, even when the transmission-side device of the visible light communication system is mounted on a vehicle, radio waves are less likely to be emitted from the wire harness, and as a result, generation of noise can be reduced.

  As a wireless communication system, a wireless communication system using radio waves such as a mobile phone and a wireless communication system using infrared light (IrDA (Infrared Data Association)) are known. According to the above-described configuration as a visible light communication system, unlike a wireless communication system using radio waves, authentication by a public institution is not required, so that it can be used all over the world. Further, according to the above configuration as a visible light communication system, unlike a wireless communication system using infrared light, not only wireless communication at a short distance (for example, “1 m” in IrDA) but also a long distance (for example, Wireless communication with “several tens of meters”) is also possible.

  By the way, the 2nd drive signal should just be produced | generated according to the logic level of communication data. Therefore, for example, “when the communication data is at the logic H level, the second drive signal generation unit generates the same signal as the first drive signal as the second drive signal, while the communication data is at the logic L level. , A signal obtained by delaying the first drive signal for a predetermined time may be generated as the second drive signal, or “the second drive signal generation unit is configured to perform the first drive when the communication data is at the logic L level. While the same signal as the signal is generated as the second drive signal, when the communication data is at the logic H level, a signal obtained by delaying the first drive signal for a predetermined time may be generated as the second drive signal.

  In the configuration according to the first aspect, the first light receiving unit and the second light receiving unit may be provided adjacent to each other. However, in this case, visible light emitted by the first light emitting unit is received not only by the first light receiving unit but also by the second light receiving unit, or visible light emitted by the second light emitting unit is not received. It is conceivable that not only the second light receiving unit but also the first light receiving unit receives light, and as a result, the data extraction unit cannot extract the logical level of the communication data.

  Therefore, as in the second aspect of the present invention, visible light emitted from the first light emitting unit is received by the second light receiving unit between the first light emitting unit and the second light receiving unit. And a second optical filter that suppresses the visible light, and visible light emitted from the second light emitting unit is interposed between the second light emitting unit and the first light receiving unit. It is desirable that a first optical filter that suppresses light received by the unit is provided. Thereby, the accuracy of extracting the logical level of the communication data can be improved.

  In many cases, various lights such as a tail lamp and DRL (Daytime Running Light) are mounted on the vehicle. Moreover, as long as the 1st light emission part and the 2nd light emission part can light-emit visible light of the set brightness | luminance, the light emission principle and structure are arbitrary.

  Therefore, in the configuration according to claim 1 or 2, as in the invention according to claim 3, the transmission side device is mounted on a vehicle, and the first light emitting unit and the second light emitting unit are mounted on a vehicle. It is desirable to be a light. Thereby, since the vehicle-mounted light already equipped in the vehicle is used, wireless communication with the outside using visible light can be performed with only a slight change in the configuration. Moreover, since the change of a structure is slight, it becomes advantageous in terms of cost.

  In order to achieve the above object, the invention according to claim 4 is a transmission side device that transmits communication data to a reception side device using visible light having a luminance set based on a user's manual operation. And a first driving signal generating unit configured to generate a first driving signal for driving the first light emitting unit so as to achieve the set luminance. And a signal obtained by delaying the same signal as the first drive signal and the first drive signal by a predetermined time as a second drive signal for driving the second light emitting unit so as to achieve the set luminance Any one of the above is provided with a second drive signal generation unit that generates the one according to the logic level of the communication data. Thus, similarly to the first aspect of the invention, communication data can be transmitted without using the first drive signal and the second drive signal as high-frequency signals. Even when is mounted on a vehicle, radio waves are less likely to be emitted from the wire harness, and as a result, noise generation can be reduced.

  Hereinafter, an embodiment of a visible light communication system according to the present invention will be described with reference to FIGS.

  First, with reference to FIG.1 and FIG.2, the transmission side apparatus 100 which comprises the visible light communication system concerning this invention is demonstrated. 1 is a schematic diagram illustrating an example of a schematic configuration of the transmission-side apparatus 100, and FIG. 2 is a block diagram illustrating an example of a detailed configuration of the transmission-side apparatus 100.

  As shown in FIG. 1, the transmission side device 100 is mounted on the vehicle C, and as shown in FIG. 2, the control device 110, the left headlight 120, the right headlight 130, the operation unit 140, etc. It is prepared for.

  Among these, the left headlight 120 and the right headlight 130 are known in-vehicle lights provided on the traveling direction side of the vehicle C, and irradiate visible light B1 and B2 toward the traveling direction of the vehicle C (light emission). ) A control device 110 (a first output driver 114 and a second output driver 115 described later) is connected to the left headlight 120 and the right headlight 130, and light is emitted from the left headlight 120 and the right headlight 130. The luminance of visible light is PWM (Pulse Width Modulation) controlled by the control device 110. The left headlight 120 corresponds to the first light emitting unit described in the claims, and the right headlight 130 corresponds to the second light emitting unit described in the claims. Further, since the headlight capable of PWM control is known, a detailed description thereof is omitted here.

  The operation unit 140 is for setting the luminance of visible light emitted from the left headlight 120 and the right headlight 130 based on a manual operation by the user.

  Specifically, the operation unit 140 is a rotary potentiometer that can rotate within a predetermined rotation angle range about a rotation shaft (not shown), and is provided in the passenger compartment and connected to the control device 110. Here, when the luminance of the visible light emitted from the left headlight 120 and the right headlight 130 is increased (brighter), the user shall rotate the rotation shaft so that the rotation angle from the initial angle position increases. It is assumed that the resistance value inside the operation unit 140 increases as the rotation angle increases. In this embodiment, a rotary potentiometer is employed as the operation unit 140. However, the operation unit 140 is not limited to a rotary potentiometer, and other known slider-type potentiometers may be employed. Good. Furthermore, it is not limited to a potentiometer, and for example, a known momentary switch or the like may be employed.

  The control device 110 is actually configured as a normal computer having a well-known CPU, for example, a memory such as a ROM or a RAM, an I / O, and a bus line for connecting them (only the I / O is included). (Illustrated). In the following description, the control device 110 includes a duty ratio calculation unit 111, a control waveform generation unit 112, and a rise delay unit 113 as functions realized by a CPU executing a program stored in a memory. The control device 110 will be described as having a first output driver 114 and a second output driver 115 which are actual I / Os.

  The duty ratio calculation unit 111 is connected to the operation unit 140 and detects a resistance value inside the operation unit 140. The duty ratio calculation unit 111 calculates the duty ratio as a larger value as the resistance value inside the operation unit 140 is larger, and calculates the duty ratio as a smaller value as the resistance value inside the operation unit 140 is smaller.

  The control waveform generation unit 112 generates a pulse signal from which the duty ratio calculated by the duty ratio calculation unit 111 is obtained. Specifically, when the duty ratio is “100%”, the control waveform generation unit 112 generates a rectangular pulse signal that is continuously at a logic H level (for example, “5 V”) during a predetermined period. In addition, when the duty ratio is “0%”, the control waveform generation unit 112 generates a rectangular pulse signal that is continuously at a logic L level (for example, “0 V”) during a predetermined period. In addition, when the duty ratio is “50%”, the control waveform generation unit 112 continuously becomes the logic H level in the first half “50%” of the predetermined period and continues in the second half “50%” of the predetermined period. A rectangular pulse signal having a logic L level is generated. As described above, the control waveform generation unit 112 generates a rectangular pulse signal in which the higher the duty ratio, the higher the ratio of the logic H level continuously being increased.

  However, the left headlight 120 and the right headlight 130 are turned on and off according to the pulse signal at the rising portion from the logic L level to the logic H level and the falling portion from the logic H level to the logic L level included in the pulse signal. It is difficult to control. For this reason, the control waveform generation unit 112 generates and outputs a first PWM signal in which the rising and falling portions of the rectangular pulse signal are gently shaped. The control waveform generator 112 corresponds to the first drive signal generator described in the claims, and the first PWM signal corresponds to the first drive signal described in the claims.

  The rising delay unit 113 generates a second PWM signal based on communication data that is data to be transmitted from the transmission-side device 100 and the first PWM signal. Specifically, when the communication data is at the logic L level, the rising delay unit 113 generates a signal obtained by delaying the first PWM signal by a predetermined delay time as the second PWM signal, while the communication data is at the logic H level. In some cases, the same signal as the first PWM signal is generated as the second PWM signal. As described above, the rising delay unit 113 generates the second PWM signal according to the logic level of the communication data. The rising delay unit 113 corresponds to the second drive signal generation unit described in the claims, and the second PWM signal corresponds to the second drive signal described in the claims.

  The first output driver 114 is configured by a transistor, for example, and receives the first PWM signal from the control waveform generation unit 112 and is connected to the left headlight 120. Here, when the voltage level of the first PWM signal is a logic H level, the first output driver 114 is turned on, and the left headlight 120 is driven to emit visible light. On the other hand, when the voltage level of the first PWM signal is the logic L level, the first output driver 114 is turned off, the left headlight 120 is not driven, and no visible light is emitted.

  Similarly, the second output driver 115 is composed of, for example, a transistor, and receives the second PWM signal from the rising delay unit 113 and is connected to the right headlight 130. Here, when the voltage level of the second PWM signal is the logic H level, the second output driver 115 is turned on, and the right headlight 130 is driven to emit visible light. On the other hand, when the voltage level of the second PWM signal is a logic L level, the second output driver 115 is turned off, the right headlight 130 is not driven, and no visible light is emitted.

  Of the operations of the transmission-side apparatus 100 configured as described above, operations related to luminance adjustment will be described. In the description of the operation relating to the luminance adjustment, it is assumed that the communication data is at the logic L level for convenience.

  In order to maximize the luminance of the visible light emitted from the left headlight 120 and the right headlight 130, the user manually rotates the rotation axis of the operation unit 140 to a predetermined rotation angle range limit. When the rotation shaft of the operation unit 140 is rotated to the limit of the predetermined rotation angle range, the resistance value inside the operation unit 140 becomes maximum, and the duty ratio calculation unit 111 calculates the duty ratio as “100%”. When the duty ratio is calculated as “100%”, the control waveform generation unit 112 generates a rectangular pulse signal that is continuously at a logic H level for a predetermined period, and further generates a first PWM signal, and the first output driver To 114. The rising delay unit 113 generates the same signal as the first PWM signal as the second PWM signal, and outputs the second PWM signal to the second output driver 115. Then, the left headlight 120 and the right headlight 130 are turned on during the period in which the first PWM signal and the second PWM signal are input to the first output driver 114 and the second output driver 115, respectively. Visible light is emitted with luminance.

  When trying to minimize the luminance of the visible light emitted from the left headlight 120 and the right headlight 130, the user manually sets the rotation axis of the operation unit 140 to the initial angular position. When the rotation axis of the operation unit 140 is set to the initial angular position, the resistance value inside the operation unit 140 is minimized, and thus the duty ratio calculation unit 111 calculates the duty ratio as “0%”. When the duty ratio is calculated as “0%”, the control waveform generation unit 112 generates a rectangular pulse signal that is continuously at a logic L level during a predetermined period, and further generates a first PWM signal, and the first output driver To 114. The rising delay unit 113 generates the same signal as the first PWM signal as the second PWM signal, and outputs the second PWM signal to the second output driver 115. Then, the left headlight 120 and the right headlight 130 are turned off during the period in which the first PWM signal and the second PWM signal are input to the first output driver 114 and the second output driver 115, respectively. Visible light is emitted.

  Further, when the brightness of visible light emitted from the left headlight 120 and the right headlight 130 is to be moderate, the user manually sets the rotation axis of the operation unit 140 to approximately the center of a predetermined rotation angle range. Set. When the rotation axis of the operation unit 140 is set to approximately the center of the predetermined rotation angle range, the resistance value inside the operation unit 140 becomes medium, and the duty ratio calculation unit 111 calculates the duty ratio as “50%”. . When the duty ratio is calculated to be “50%”, the control waveform generation unit 112 causes the first half “50%” of the predetermined cycle to be continuously at the logic H level, and the second half “50%” of the predetermined cycle is continued. Then, a rectangular pulse signal having a logic L level and a first PWM signal are generated and output to the first output driver 114. The rising delay unit 113 generates the same signal as the first PWM signal as the second PWM signal, and outputs the second PWM signal to the second output driver 115. Then, in the left headlight 120 and the right headlight 130, the first half “50%” of the period in which the first PWM signal and the second PWM signal are input to the first output driver 114 and the second output driver 115, respectively, is turned on, and Since the latter half “50%” is turned off, visible light is emitted with a medium luminance.

  Hereinafter, based on the description of the operation related to the brightness adjustment, the operation related to transmission of the communication data of the transmission side device 100 will be described with reference to FIG. FIG. 3 is a flowchart showing a processing procedure of communication data transmission processing S1 executed by the transmission-side apparatus 100.

  When the communication data transmission process S1 is started, the control device 110 (duty ratio calculation unit 111) calculates a duty ratio as the process of step S11. When the duty ratio is calculated, the control device 110 (control waveform generation unit 112) generates a pulse signal, and thus the first PWM signal, as the subsequent process of step S12.

  When the first PWM signal is generated, control device 110 (rising delay unit 113) determines whether or not the communication data is at the logic L level as a determination process in subsequent step S13. Here, when it is determined that the communication data is at the logic L level (“Yes” in the determination process of step S13), the rising delay unit 113 delays the signal obtained by delaying the first PWM signal by a predetermined delay time to the second PWM. Generate as a signal. On the other hand, when it is determined in the determination process of the previous step S13 that the communication data is at the logic H level (“No” in the determination process of step S13), the rising delay unit 113 outputs the same signal as the first PWM signal. Generated as the second PWM signal.

  When the first PWM signal and the second PWM signal are generated in this way, the control waveform generation unit 112 outputs the first PWM signal to the first output driver 114 and the rising delay unit 113 is processed in the subsequent step S16. The second PWM signal is output to the second output driver 115.

  FIG. 4 is a timing chart showing an example of waveforms of the first PWM signal generated by the control waveform generation unit 112 and the second PWM signal generated by the rising delay unit 113 when the duty ratio is calculated as “50%”. It is a chart.

  As shown in FIG. 4, the control waveform generation unit 112 continuously sets the first half “50%” of the predetermined period T to the logic H level regardless of whether the communication data is at the logic H level or the logic L level. In addition, a rectangular pulse signal in which the second half “50%” of the predetermined period T is continuously at the logic L level is generated and output as the first PWM signal.

  As shown in FIG. 4, when the communication data is at the logic H level, the rising delay unit 113 generates the same signal as the first PWM signal as the second PWM signal, while the communication data is at the logic L level. In this case, a signal obtained by delaying the first PWM signal by a predetermined delay time Δt is generated and output as the second PWM signal.

  Next, with reference to FIG. 5, the receiving side apparatus 200 which comprises the visible light communication system concerning this invention is demonstrated. FIG. 5 is a block diagram illustrating an example of the configuration of the reception-side device 200.

  As shown in FIG. 5, the receiving-side apparatus 200 includes a first light receiving unit 210, a second light receiving unit 220, a rise time comparison unit 230, and the like.

  The first light receiving unit 210 includes a light receiving element such as a photodiode or a phototransistor, for example. When visible light emitted from the left headlight 120 is applied to the first light receiving unit 210, the first light receiving unit 210 converts the received light signal into an electric signal (first light receiving signal) and compares the rise time. Output to the unit 230.

  Similar to the first light receiving unit 210, the second light receiving unit 220 includes a light receiving element such as a photodiode or a phototransistor. When visible light emitted from the right headlight 130 is irradiated on the second light receiving unit 220, the second light receiving unit 220 converts the received optical signal into an electrical signal (second received light signal) and compares the rise time. Output to the unit 230.

  The rise time comparison unit 230 is configured as an ordinary computer having a well-known CPU, for example, a memory such as a ROM or a RAM, an I / O, and a bus line connecting them (all not shown), Based on the presence or absence of a delay between the signal and the second light receiving signal, the logic level of the communication data transmitted from the transmitting apparatus 100 is extracted.

  Specifically, the rise time comparison unit 230 detects a rising portion from the logic L level included in the first light reception signal to the logic H level, and rises from the logic L level included in the second light reception signal to the logic H level. Detect part. Then, the rise time comparison unit 230 determines whether the rise of the second light reception signal is delayed by a predetermined delay time from the rise of the first light reception signal. When it is determined that the rising time comparison unit 230 is delayed by a predetermined delay time, the rising time comparison unit 230 determines that the communication data transmitted from the transmission side device 100 is at the logic L level. On the other hand, when it is determined that the delay time comparison unit 230 is not delayed by a predetermined delay time, the communication time transmitted from the transmission-side device 100 is determined to be at the logic H level. In this manner, the rise time comparison unit 230 extracts the logical level of the communication data from the visible light emitted from the left headlight 120 and the right headlight 130. The rise time comparison unit 230 corresponds to the data extraction unit described in the claims.

  Hereinafter, an operation related to reception of communication data of the reception-side apparatus 200 will be described with reference to FIG. FIG. 6 is a flowchart showing a processing procedure of communication data reception processing S2 executed by the reception-side apparatus 200.

  When the communication data reception process S2 is started, the rise time comparison unit 230 detects the rising part from the logic L level to the logic H level included in the first light reception signal as the process of step S21, and the subsequent step S22. As the processing, a rising portion from the logic L level to the logic H level included in the second received light signal is detected.

  When a rising portion is detected for each of the first light receiving signal and the second light receiving signal, the rising time comparison unit 230 compares the rising time of the first light receiving signal with the rising time of the second light receiving signal as the processing of the subsequent step S23. At the same time, as the determination processing in step S24, it is determined whether or not the rising edge of the second light receiving signal is delayed by a predetermined delay time from the rising edge of the first light receiving signal.

  Here, when it is determined that the signal is delayed by a predetermined delay time (“Yes” in the determination process of step S24), the rise time comparison unit 230 is transmitted from the transmission-side apparatus 100 as the subsequent process of step S25. The communication data is determined to be at the logic L level. On the other hand, when it is determined that the delay is not delayed by the predetermined delay time (“No” in the determination process of step S24), the rising time comparison unit 230 is transmitted from the transmission-side apparatus 100 as the subsequent process of step S26. It is determined that the communication data is at logic H level.

  In the above-described embodiment, the transmission side device 100 generates the same signal as the first PWM signal as the second PWM signal and outputs it to the right headlight 130 when the communication data is at the logic H level, When the visible light B2 is emitted and the communication data is at the logic L level, a signal obtained by delaying the first PWM signal by a predetermined delay time is generated as the second PWM signal and output to the right headlight 130 to be visible. A control device 110 that emits light B2 is provided. In addition, the receiving-side apparatus 200 receives the visible light B1 emitted from the left headlight 120 when the rising edge of the second received light signal received and converted from the visible light B2 emitted from the right headlight 130 is received. It is determined whether or not it is delayed by a predetermined delay time with respect to the rising edge of the first received light signal converted in this way. The communication data is determined to be at the logic H level, and when it is determined that the communication data has not been delayed by a predetermined delay time, the communication data transmitted from the transmission side device 100 is determined to be at the logic L level. It was decided.

  Thus, communication data can be transmitted without using the first PWM signal and the second PWM signal as high-frequency signals. Therefore, even when the visible light communication system (transmission side device 100) is mounted on the vehicle C, radio waves are less likely to be emitted from the wire harness, and as a result, noise generation can be reduced. . In addition, unlike a wireless communication system using radio waves, authentication by a public institution is unnecessary, so that it can be used all over the world. Furthermore, unlike a wireless communication system using infrared light, not only wireless communication over a short distance (for example, “1 m” in IrDA) but also wireless communication over a long distance (for example, “several tens of meters”) is possible. It becomes like this.

  The visible light communication system according to the present invention is not limited to the configuration illustrated in the above embodiment, and can be implemented with various modifications without departing from the spirit of the present invention. is there. In other words, for example, the following embodiment can be implemented by appropriately changing the above embodiment.

  As shown in FIG. 7 as a diagram corresponding to FIGS. 1 and 5, the transmission-side apparatus 100a places the first optical filter F11 and the second optical filter F21 immediately before the left headlight 120 and the right headlight 130, respectively. In addition, the receiving-side device 200a preferably includes the first optical filter F12 and the second optical filter F22 immediately before the first light receiving unit 210 and the second light receiving unit 220, respectively.

  Specifically, a vertical polarization filter and a horizontal polarization filter are employed as the first optical filters F11 and F12 and the second optical filters F21 and F22, respectively. In this case, visible light B1 emitted from the left headlight 120 and transmitted through the first optical filter F11 passes through the first optical filter F12 and is received by the first light receiving unit 210, but passes through the second optical filter F22. The light is not transmitted and is not received by the second light receiving unit 220. The visible light B2 emitted from the right headlight 130 and transmitted through the second optical filter F21 is transmitted through the second optical filter F22 and received by the second light receiving unit 220, but is transmitted through the first optical filter F12. The first light receiving unit 210 does not receive the light. Thereby, the accuracy of extracting the logical level of the communication data can be improved.

  Moreover, it is not restricted to the said vertical polarizing filter and a horizontal polarizing filter. FIG. 8 shows combinations of optical filters that can be employed as the first optical filter F11, the second optical filter F21, and the first optical filter F12 and the second optical filter F22.

  As shown as another example in FIG. 8, an infrared light reflection filter and an infrared light transmission filter can be employed as the first optical filters F11 and F12 and the second optical filters F21 and F22, respectively. When such an optical filter is employed, visible light B1 emitted from the left headlight 120 and transmitted through the first optical filter F11 does not include infrared light but includes light other than infrared light. Therefore, the visible light B1 passes through the first optical filter F12 and is received by the first light receiving unit 210, but does not pass through the second optical filter F22 and is not received by the second light receiving unit 220. Further, the visible light B2 emitted from the right headlight 130 and transmitted through the second optical filter F21 does not include light other than infrared light, and includes only infrared light. Therefore, the visible light B2 passes through the second optical filter F22 and is received by the second light receiving unit 220, but does not pass through the first optical filter F12 and is not received by the first light receiving unit 210. Thereby, the accuracy of extracting the logical level of the communication data can be improved.

  Further, as shown as another example 2 in FIG. 8, a first wavelength selection filter and a second wavelength selection filter can be employed as the first optical filters F11 and F12 and the second optical filters F21 and F22, respectively. Here, the first wavelength and the second wavelength are different from each other. When such an optical filter is employed, the visible light B1 emitted from the left headlight 120 and transmitted through the first optical filter F11 includes only light of the first wavelength. Therefore, the visible light B1 passes through the first optical filter F12 and is received by the first light receiving unit 210, but does not pass through the second optical filter F22 and is not received by the second light receiving unit 220. Further, the visible light B2 emitted from the right headlight 130 and transmitted through the second optical filter F21 includes only light of the second wavelength. Therefore, the visible light B2 passes through the second optical filter F22 and is received by the second light receiving unit 220, but does not pass through the first optical filter F12 and is not received by the first light receiving unit 210. Thereby, the accuracy of extracting the logical level of the communication data can be improved.

  An application example of the above embodiment is shown in FIG. As shown in FIG. 9, the receiving side device 200 or 200a constituting the visible light communication system is provided at an appropriate location in the garage G1 capable of receiving visible light B1 and B2, and stores the unique ID of the vehicle C. It has a memory holding unit (not shown) for holding. In addition, the transmission-side device 100 or 100a transmits the unique ID of the vehicle C as communication data using visible light B1 and B2. When the unique ID transmitted from the transmitting device 100 or 100a with the visible lights B1 and B2 is authenticated by the receiving device 200 or 200a, the garage opens the garage door. Thus, the above-described embodiment can be applied to such a garage.

  FIG. 10 shows another application example of the above embodiment. As shown in FIG. 10, the parking system P includes a receiving-side device 200 or 200a at an appropriate place where visible light B1 and B2 can be received, and further stores a unique ID of the vehicle C. A holding unit (not shown), a display unit 240 that displays a designated parking area, and an illumination 250 that disappears in the parking area are provided. When the unique ID transmitted from the transmitting apparatus 100 or 100a with visible light B1 and B2 is authenticated by the receiving apparatus 200 or 200a, the garage system G2 opens the gate and displays it on the display unit 240. By doing so, the parking section is designated, and the illumination 250 provided in the corresponding parking section is turned on and off. Thus, the above embodiment can be applied to such a parking system P.

In the above embodiment, the left headlight 120 and the right headlight 130 are employed as the first light emitting unit and the second light emitting unit, respectively. Conversely, the right headlight 130 is employed as the first light emitting unit and the second light emitting unit. Alternatively, the left headlight 120 may be employed. In addition to the headlight, various lights such as a tail lamp and DRL may be employed. However,
There is no need to mount the visible light communication system.

It is a schematic diagram which shows an example of the schematic structure about the transmission side apparatus which comprises one Embodiment of the visible light communication system which concerns on this invention. It is a block diagram which shows the example about the detailed structure of a transmission side apparatus. It is a flowchart which shows an example of the process sequence about the communication data transmission process performed by the transmission side apparatus. It is a timing chart which shows an example of the waveform about the 1st PWM signal and the 2nd PWM signal which are generated by the transmitting side device. It is a block diagram which shows an example of the whole structure about the receiving side apparatus which comprises the said one Embodiment. It is a flowchart which shows an example of the process sequence about the communication data reception process performed by the receiving side apparatus. It is a schematic diagram which shows another structural example about the visible light communication system which concerns on this invention. It is a figure which shows the combination of a 1st optical filter and a 2nd optical filter by a list. It is a schematic diagram which shows the example of application of the visible light communication system which concerns on this invention. It is a schematic diagram which shows another example of application of the visible light communication system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 100a ... Transmission side apparatus, 110 ... Control apparatus, 111 ... Duty ratio calculation part, 112 ... Control waveform generation part, 113 ... Rise delay part, 114 ... 1st output driver, 115 ... 2nd output driver, 120 ... Left Headlight, 130 ... right headlight, 140 ... operation unit, 200, 200a ... receiving side device, 210 ... first light receiving unit, 220 ... second light receiving unit, 230 ... rise time comparison unit, 240 ... display unit, C ... Vehicle, F1 ... first optical filter, F2 ... second optical filter, G ... garage system, P ... parking system

Claims (4)

A visible light communication system that transmits and receives communication data between a transmission-side device and a reception-side device using visible light having a luminance set based on a user's manual operation,
The transmitting device is:
A first light emitting part and a second light emitting part for emitting visible light;
A first drive signal generation unit that generates a first drive signal for driving the first light emitting unit to have the set luminance;
Either the same signal as the first drive signal or a signal obtained by delaying the first drive signal for a predetermined time as the second drive signal for driving the second light emitting unit so as to achieve the set luminance. A second drive signal generation unit that generates one according to the logic level of the communication data;
The receiving side device
A first light-receiving unit that receives visible light emitted from the first light-emitting unit as a first light-receiving signal;
A second light receiving unit that receives visible light emitted from the second light emitting unit as a second light receiving signal;
A visible light communication system comprising: a data extraction unit that extracts a logic level of the communication data based on presence or absence of a delay between the first light reception signal and the second light reception signal. The visible light communication system according to claim 1,
A second optical filter is provided between the first light emitting unit and the second light receiving unit to suppress visible light emitted from the first light emitting unit from being received by the second light receiving unit. And
A first optical filter is provided between the second light emitting unit and the first light receiving unit to suppress visible light emitted from the second light emitting unit from being received by the first light receiving unit. A visible light communication system. The visible light communication system according to claim 1 or 2,
The transmission side device is mounted on a vehicle, and the first light emitting unit and the second light emitting unit are in-vehicle lights. A transmission-side device that transmits communication data to a reception-side device using visible light having a luminance set based on a user's manual operation;
A first light emitting part and a second light emitting part for emitting visible light;
A first drive signal generation unit that generates a first drive signal for driving the first light emitting unit to have the set luminance;
Either the same signal as the first drive signal or a signal obtained by delaying the first drive signal for a predetermined time as the second drive signal for driving the second light emitting unit so as to achieve the set luminance. A transmission-side apparatus comprising: a second drive signal generation unit that generates one according to a logical level of the communication data.

Images