JP4777030B2 - Transmitting apparatus, receiving apparatus, communication method, and optical communication system - Google Patents

Description

  The present invention relates to a transmission device, a reception device, a communication method, and an optical communication system, and more particularly to a technique for performing communication using visible light.

  In the so-called ubiquitous society where users can access necessary information without being seized by time and place, it is assumed that users always carry communication devices, such as exchanging information between users and receiving information from other devices. Wireless communication technology between devices is indispensable. At present, wireless communication using radio waves is the most common, but radio waves are concerned about the impact on the human body, and since they affect precision equipment, their use in hospitals, trains, etc. is restricted. Yes.

  Another wireless communication method is infrared communication. Infrared communication is a technology that implements wireless communication using infrared light that is between the frequency band of visible light and the frequency band of millimeter waves. The infrared communication module has no antenna, has a compact hardware, and is low in cost. Therefore, the infrared communication module is used in various digital devices such as a television, a notebook computer, a digital camera, and a PDA. In particular, mounting infrared communication modules on mobile phone terminals is being standardized worldwide.

  The infrared communication method described above can be used for devices such as changing the TV channel using the remote control, adjusting the temperature of the air conditioner, and communicating data such as phone books and photos between mobile terminals. limited.

  In recent years, terrestrial digital broadcasting has been started nationwide and is spreading to ordinary households. FIG. 11 is a basic configuration diagram of a liquid crystal display used for a digital broadcast receiver on the ground. A liquid crystal display 900 illustrated in FIG. 11 includes a display control unit 910, an image information storage unit 911, a light emission control unit 912, a light emission unit 913, a first polarization unit 914, a liquid crystal unit 915, and a second polarization unit 916. The user's eye 300 can capture the image light signal 912 from the liquid crystal display 900.

  With the spread of terrestrial digital broadcasting, it is conceivable that information transmitted together with television broadcast information is received by a portable terminal or the like. Also, in the medical field, due to the widespread use of electronic medical records, there may be situations where information is transmitted from a display such as a television or a personal computer to a portable terminal or the like, such as transmitting necessary information to a patient's portable terminal. Also, in public transportation such as trains, where the use of wireless communication devices such as mobile phone terminals is currently restricted, liquid crystal displays for in-car guidance and liquid crystals for terminals held by users (mobile phone terminals, PDAs, etc.) Realizing wireless communication using a display can be considered. Specifically, for example, a service that broadcasts connection information, news, weather forecasts, and the like from a display on the train can be considered.

  However, in such information transmission, on the receiving side, it is assumed that the user holds the receiving terminal. For this reason, when communicating using infrared rays, it is considered that infrared rays may enter the user's eyes, and when infrared rays enter the eyes, they may affect the protein of the lens and cause cataracts. ing. In order to avoid such a possibility, the transmission power must be reduced, and as a result, the communication speed cannot be increased, and the communicable range is limited.

Therefore, at present, information communication using visible light or the like is being studied (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 11-215062

  However, in the information transmission described above, a transmission device for transmitting information is required in addition to the display for image display, resulting in an increase in the size of the device.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a transmission device, a reception device, a communication method, and an optical communication system in which the size of the device is reduced. It is in.

The present invention provides a liquid crystal unit composed of communication pixels and image pixels, a communication light emitting unit that emits communication light toward the communication pixels, and the image pixels. The image light emitting unit for irradiating the image light, and only one polarization of the communication light from the communication light emitting unit is transmitted toward the communication pixel, and the image light emitting unit A first polarization unit that passes only one polarization of the image light to the image pixel, and polarizes the communication light incident on the communication pixel based on the communication information. A polarization control means for polarizing image light incident on the image pixel based on the information; and a second control means for transmitting only one polarization of at least the image light polarized in the image pixel. has a polarization unit, wherein the first polarization section and the Of the two polarizing portions, at least one polarization conversion with the same polarization transformation applied to the light for the image, a transmitting apparatus characterized by not apply to light for communication.

  With this configuration, since some pixels of the liquid crystal unit are used for communication and communication information is transmitted, wireless communication can be realized without providing a transmission device in addition to the conventional liquid crystal display. Therefore, it is possible to reduce the size of the apparatus.

  The present invention further includes communication light emission control means for controlling light emission by the communication light emitting unit based on the communication information.

Further, the present invention, the second polarizing portion, a light for communication polarized in the communication pixels, Ru pass without being polarized.

Further, in the invention, the first polarizing unit polarizes the communication light from the communication light emitting unit and the image light from the image light emitting unit so that the polarization angles are orthogonal to each other. The second polarization unit polarizes the communication light polarized in the communication pixel and the image light polarized in the image pixel so that the polarization angles are orthogonal to each other.

  In the present invention, the communication pixel is disposed at an outer edge portion of the liquid crystal portion.

  Further, according to the present invention, the communication light emission control unit emits the same number of light sources among the plurality of light sources constituting the communication light emitting unit corresponding to each communication information, and the light sources to be emitted are periodically Switch.

  In the present invention, the communication light is light in a visible light region.

The present invention also provides a light receiving means for receiving other light together with light polarized based on communication information, and communication information specifying for specifying the communication information based on a polarization angle of light received by the light receiving means. And a communication time determining means for determining whether the light received by the light receiving means corresponds to when the communication information is communicated or corresponds to a non-communication time, the communication information specifying means Receiving the communication information based on a difference between a polarization vector of light received by the light receiving unit during communication and a polarization vector of light received by the light receiving unit during non-communication Device.

  With this configuration, it is possible to receive the polarized light based on the communication information output from the transmission device described above and acquire the communication information.

  Further, according to the present invention, the light receiving unit receives a first light receiving unit that receives one polarized light of the reaching light, and the polarization angle received by the first light receiving unit among the reaching light is orthogonal to the polarization angle. And a second light receiving portion that receives the polarized light.

Further, the present invention provides a communication light emitting step for irradiating communication light toward a communication pixel constituting the liquid crystal unit, and an image light toward the image pixel constituting the liquid crystal unit. The image emission step for irradiating the image and the communication light emitted by the communication light emission step pass only one polarized light toward the communication pixel, and the image emission step is emitted. Based on the first polarization step for passing only one polarization of the image light to the image pixel and the communication information , the communication light incident on the communication pixel is polarized, and the image information based on the polarization control step of polarizing the light for image incident on the pixel for the image, in the polarization controlling step, one of the light for image polarized in at least said image pixel And a second polarization step of passing only polarized light, wherein the first polarization step and of said second polarization step, at least one, same polarization as polarization transformation applied to the light for the image The communication method is characterized in that the conversion is not applied to the communication light .

  The present invention also includes a communication light emission control step for controlling light emission in the communication light emission step based on the communication information.

  Further, according to the present invention, the communication light emission control step emits the same number of light sources among the plurality of light sources emitted by the communication light emission step corresponding to each communication information, and the light sources to emit the light Switch periodically.

  In the present invention, the communication light is light in a visible light region.

Further, the present invention provides a light receiving step for receiving other light together with light polarized based on communication information, and communication information specifying for specifying the communication information based on a polarization angle of light received by the light receiving step. And a communication time determination step for determining whether the light received by the light receiving step corresponds to the time of communication of the communication information or to correspond to the time of non-communication. Specifies the communication information based on a difference between a polarization vector of light received by the light receiving step during communication and a polarization vector of light received by the light receiving step during non-communication .

  According to the present invention, since some pixels of the liquid crystal unit are used for communication and communication information is transmitted, the device can be miniaturized.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a basic configuration diagram of a visible light communication system according to a first embodiment of the present invention. In FIG. 1, a liquid crystal display 101 as a transmission device includes an image light emitting unit 107 that emits light for image drawing and a communication light emitting unit 108 that emits light for communication information. The light emitting unit 103, the first polarizing unit 104 through which only one polarized light passes, the liquid crystal unit 105 that changes the polarization angle for each pixel, and the polarizing unit through which only predetermined polarized light passes, The second polarization unit 106 provided with a gap 109, the communication information storage unit 113 holding communication information, the image information storage unit 114 holding image information, and image information and communication information as one drawing information The display communication control unit 110 controls the polarization angle for each pixel with respect to the liquid crystal unit 105, and the communication light emission control unit 112 controls the communication light emission unit 108 based on the drawing information.

  The image light emitting unit 107 emits light based on the control of the image light emission control unit 111. The light emitted from the image light emitting unit 107 is converted into one polarized light by the first polarizing unit 104 and then incident on the liquid crystal unit 105. The display communication control unit 110 combines image information and communication information into one piece of drawing information, and controls the liquid crystal constituting the liquid crystal unit 105 for each pixel based on the image information included in the combined drawing information. Determine the angle. As a result, only one polarized light out of the light passing through the liquid crystal unit 105 passes through the second polarizing unit 106 and an image is drawn on the screen, and the image light signal 191 is visually recognized by the user's eyes 300.

  On the other hand, the communication light emitting unit 108 emits light based on the control of the communication light emission control unit 112. The light emitted from the communication light emitting unit 108 is converted into one polarized light by the first polarizing unit 104 and then incident on the liquid crystal unit 105. The display communication control unit 110 controls the liquid crystal constituting the liquid crystal unit 105 for each pixel based on the communication information included in the combined drawing information, and determines the polarization angle. Thereby, the incident light to the liquid crystal unit 105 is polarized at an arbitrary angle by the liquid crystal unit 105 and then passes through the gap 109 provided in the second polarizing unit 106.

  Therefore, the liquid crystal display 101 transmits the image light signal 191 that is the polarization for drawing an image on the screen that has passed through the second polarization unit 106 and the communication information that has passed through the gap 109 of the second polarization unit 106. Therefore, a signal (visible light signal) 190 in the visible light region, which is polarized light at an arbitrary angle, is synthesized and output.

  Further, in the liquid crystal display 101, the communication light emission control unit 112 is configured so that the communication light emission unit 108 alternately communicates during communication in which light is emitted and non-communication in which light is not emitted. 108 is controlled.

  The receiving apparatus 102 includes a first light receiving unit 115 that receives only one polarization signal, a second light receiving unit 116 that receives only a polarization signal orthogonal to the polarization signal received by the first light receiving unit 115, and a first The communication information acquisition unit 117 extracts the communication information 180 based on the polarization signal received by the light receiving unit 115 and the second light receiving unit 116.

  The first light receiving unit 115 and the second light receiving unit 116 receive only polarized signals orthogonal to each other. The communication information acquisition unit 117 can extract communication information by taking a difference between communication time and non-communication time with respect to the polarization signal received by the first light receiving unit 115 and the second light receiving unit 116.

  FIG. 2 is a configuration diagram of the communication information acquisition unit 117 of the reception device 102. In FIG. 2, the communication information acquisition unit 117 includes a first communication information presence / absence determination unit 201 that determines presence / absence of communication information of a first reception signal 204 that is a polarization signal received by the first light reception unit 115, and a second light reception. A second communication information presence / absence determination unit 202 that determines the presence / absence of communication information of the second reception signal 205, which is a polarization signal received by the unit 116, a reference signal 206 having no communication information, and a communication signal 208 having communication information. And a comparison unit 203 that obtains the difference between the reference signal 207 having no communication information and the communication signal 209 having communication information.

  The first communication information presence / absence determination unit 201 selects a polarization signal corresponding to each of communication time and non-communication time alternately from the first reception signal 204, and uses the polarization signal at the time of non-communication as the first reference signal 206. While outputting to the comparison part 203, the polarization signal at the time of communication immediately after the 1st reference signal 206 is output to the comparison part 203 as the 1st communication signal 208. FIG. Similarly, the second communication information presence / absence determination unit 202 selects a polarization signal corresponding to each of communication time and non-communication time alternately from the second reception signal 205, and sets the polarization signal at the time of non-communication as the second reference. The signal 207 is output to the comparison unit 203, and the polarization signal during communication immediately after the second reference signal 207 is output to the comparison unit 203 as the second communication signal 209. The comparison unit 203 obtains a difference between the first reference signal 206 and the second reference signal 207 at the time of non-communication and the first communication signal 208 and the second communication signal 209, and specifies the communication information 180 based on these differences. To do.

  FIG. 3 is a diagram illustrating a transmission output signal of the liquid crystal display 101. In FIG. 3, the horizontal axis indicates time. The upper part of FIG. 3 is an image signal output from the image drawing portion, and the arrow indicates the polarization vector. On the other hand, the lower part of FIG. 3 is a communication signal that has passed through the gap 109 provided in the second polarization unit 106, and the arrow indicates the polarization vector. 3 indicates that the output signal is a signal corresponding to non-communication when the output signal does not have communication information.

  At time t1 (during non-communication), the liquid crystal display 101 outputs only an image signal that is one polarization signal. At the next time t2 (during communication), the liquid crystal display 101 outputs both an image signal that is one polarization signal and a communication signal that is a polarization signal at an arbitrary angle. Further, since the communication is not performed again at time t3, the liquid crystal display 101 outputs only an image signal that is one polarization signal, similarly to the time t1. As described above, the liquid crystal display 101 alternately and continuously outputs a signal output at the time of non-communication having no communication signal at times t1 and t3 and a signal output at the time of communication having a communication signal at times t2 and t4. It is done.

  FIG. 4 is a diagram for explaining difference processing in the receiving apparatus 102. In FIG. 4, the horizontal axis indicates time. 4 shows one polarization signal received by the first light receiving unit 115 of the receiving apparatus 102, and an arrow indicates the polarization vector (first light receiving unit polarization vector). The middle part of FIG. 4 is one polarization signal received by the second light receiving unit 116 of the receiving apparatus 102, and the arrow indicates the polarization vector (second light receiving unit polarization vector). The lower part of FIG. 4 shows a difference signal between the first light receiving unit polarization vector and the second light receiving unit polarization vector during non-communication and communication. 4 indicates that the received light signal is not in communication and has no communication information.

  In the receiving device 102, the first light receiving unit 115 and the second light receiving unit 116 that receive the orthogonal polarization signals respectively receive the polarization signal corresponding to the non-communication and the polarization signal corresponding to the communication alternately and continuously. The first communication information presence / absence determination unit 201 and the second communication information presence / absence determination unit 202 determine the presence / absence of communication information for the received polarization signal, send the polarization signal during non-communication to the comparison unit 203, and The polarization signal at the time of communication immediately after the one reference signal 206 is sent to the comparison unit 203. The comparison unit 203 includes the polarization vector (first light receiving unit polarization vector) of the polarization signal from the first communication information presence / absence determination unit 201 corresponding to the time of non-communication and the first communication information presence / absence determination unit 201 corresponding to the immediately following communication. And the difference between the polarization vector of the polarization signal from the second communication information presence determination unit 202 and the polarization vector of the polarization signal from the second communication information presence / absence determination unit 202 (second light reception unit polarization vector) The communication information is specified by taking the difference from the polarization vector (second light receiving unit polarization vector) of the polarization signal from the second communication information presence / absence determination unit 202 corresponding to the communication, and combining these difference vectors.

  As described above, the liquid crystal display 101 alternately outputs a polarization signal corresponding to a non-communication time without a communication signal and a polarization signal at the time of communication having communication information, and the receiving device 102 takes these differences. Communication information can be extracted. Note that the receiving device 102 is assumed to be held by the user, but if the light receiving surface of the receiving device 102 faces the screen of the liquid crystal display 101 by using the communication method described above, the user It is possible to reliably receive communication information without depending on how it is held. For example, when communication information related to an image displayed on the liquid crystal display 101 is transmitted and received, the user can recognize the content of the communication information in the image.

  FIG. 5 shows an example of 2-bit information assigned to a polarization signal vector (polarization vector) that is a communication signal. In FIG. 5, 2-bit communication information is assigned to each of the four polarization angles of the communication signal, and 2-bit communication information can be transmitted and received at a time. If the communication condition of the transmission path is good, it is possible to transmit / receive 3-bit or 4-bit communication information at a time by changing the polarization angle of the communication signal to 8 or 16.

  As described above, in the liquid crystal display 101 according to the first embodiment, some pixels are used as communication ports, and communication information is transmitted to the receiving device 102. Therefore, in addition to the conventional liquid crystal display 101, communication is performed. Wireless communication can be realized without providing a service port, and the apparatus can be reduced in size. In addition, since light in the visible light region is used for transmission of communication information from the liquid crystal display 101 to the receiving device 102, there is no need to reduce transmission power as in the case of performing communication using infrared rays, and communication speed can be increased. It is possible to improve the communication range and improve the communication range.

(Second embodiment)
FIG. 6 is a basic configuration diagram of a visible light communication system according to the second embodiment of the present invention. In FIG. 6, the liquid crystal display 101 as a transmission device includes a light emitting unit 215 including an image light emitting unit 250 and a communication light emitting unit 251, a first image polarizing unit 260, and a first communication polarized light. A first polarization unit 216 configured by a unit 261, a liquid crystal unit 217, a second polarization unit 218 configured by a second image polarization unit 280, and a second communication polarization unit 281; A housing 219, a protective film 220, a communication information storage unit 113 holding communication information, an image information storage unit 114 holding image information, and a liquid crystal unit 217 based on the image information and communication information. The display communication control unit 110 controls the communication light emission control unit 112 and the communication light emission control unit 112 controls the communication light emission unit 251.

  The display communication control unit 110 reads the image information stored in the image information storage unit 114, and forms the read image in the image drawing area of the liquid crystal unit 217. The image light emission unit 250 emits light based on the control of the image light emission control unit 111. The light emitted from the image light emitting unit 250 is converted into one polarized light by the first image polarizing unit 260 and then incident on the liquid crystal unit 217. The display communication control unit 110 determines the polarization angle by controlling the liquid crystal constituting the liquid crystal unit 217 for each pixel based on the image information. As a result, only one polarization of the light that has passed through the liquid crystal unit 217 passes through the second image polarization unit 280 and an image is drawn on the screen, and the image light signal 191 is visually recognized by the user's 300 eyes. .

  Furthermore, the display communication control 110 reads communication information stored in the communication information storage unit 113 and controls the polarization angle of the liquid crystal region for communication of the liquid crystal unit 217 based on the communication information. The communication light emission control unit 112 performs light emission control of the communication light emission unit 251 in accordance with the control of the communication area of the liquid crystal unit 217 from the display communication control unit 110. The communication light emitting unit 251 emits light when there is a light emission request from the communication light emission control unit 112. The light emitted from the communication light emitting unit 251 is converted into one polarized light by the first communication polarizing unit 261 and then incident on the liquid crystal unit 217. The display communication control unit 110 determines the polarization angle by controlling the liquid crystal forming the liquid crystal unit 217 for each pixel based on the communication information. As a result, only one polarization of the light that has passed through the liquid crystal unit 217 passes through the second communication polarization unit 281 and is output as a signal in the visible light region (visible light signal 190) for transmitting communication information. The

  The polarization angle of the first image polarization unit 260 of the first polarization unit 216 and the polarization angle of the first communication polarization unit 261 are orthogonal to each other. Further, the polarization angle of the second image polarization unit 280 of the second polarization unit 218 and the polarization angle of the second communication polarization unit 282 are orthogonal to each other. Furthermore, the polarization angles of the first image polarization unit 260 and the second image polarization unit 280 are orthogonal to each other. Therefore, the polarization angles of the light (image light signal 191) that has passed through the second image polarization unit 280 and the light (visible light signal 190) that has passed through the second communication polarization unit 281 are orthogonal to each other.

  On the other hand, the receiving apparatus 102 includes a first light receiving unit 230 and a second light receiving unit 233 that receive an optical signal from the outside, and a first buffer 231 and a second buffer 234 that delay the two received optical signals. The communication information 180 is obtained from the first difference processing unit 232 and the second difference processing unit 235 that calculate the difference between the two optical signals, and the two differences obtained by the first difference processing unit 232 and the second difference processing unit 235. It comprises a received light signal analysis unit 236 for analysis and output.

  As described above, the polarization angles of the image light signal 191 and the visible light signal 190 are orthogonal. That is, the light output from the liquid crystal display 101 is a combination of the image light signal 191 and the visible light signal 190 having a polarization component orthogonal to the image light signal 191. On the other hand, the first light receiving unit 230 and the second light receiving unit 233 receive polarized signals orthogonal to each other, and each arriving light is separated into polarized components. The first light receiving unit 230 outputs the polarization signal to the first buffer 231 and the first difference processing unit 232, and the second light receiving unit 233 outputs the polarization signal to the second buffer 234 and the second difference processing unit 235. . The first difference processing unit 232 calculates a difference between the polarization signal from the first light receiving unit 230 and the delayed polarization signal from the first buffer 231. Similarly, the second difference processing unit 235 calculates the difference between the polarization signal from the second light receiving unit 233 and the delayed polarization signal from the second buffer 234. The received light signal analysis unit 236 obtains communication information 180 corresponding to these differences.

  FIG. 7 is a diagram for explaining the transmission process of the liquid crystal display 101. In FIG. 7, the horizontal axis indicates time, and the communication vector read from the communication information storage unit 113 and transmitted, the lighting of the communication light emitting unit 251, and the polarization vector of the visible light signal 190 corresponding to the communication information in order from the top. The polarization vector of the image optical signal 191 and the polarization vector of the optical signal output from the liquid crystal display 101 are shown.

  The image light signal 191 is a normal NTSC signal (30 [frame / sec]). On the other hand, the blinking speed of the communication light emitting unit 251 is 20 [MHz]. When communication information = 0, the communication light emitting unit 251 is turned off (Tk + 4 to Tk + 6). When communication information = 1, the communication light emitting unit 251 is turned off and turned on (Tk to Tk + 2). . The update of the image light signal 191 is very slow compared to the blinking speed of the communication light emitting unit 251, in other words, the communication speed of the visible light signal 190 corresponding to the communication information. For this reason, at a time (Tk + 4 to Tk + 13) other than the update timing of the image light signal 191, the image light signal 191 becomes a constant value, and only the visible light signal 190 fluctuates. Therefore, when the time difference of the change signal received by the receiving apparatus 102 is calculated, the component of the image light signal is 0 as the time difference, and only the fluctuation of the visible light signal 190 is calculated as the time difference. Become. In addition, at the update timing of the image light signal 191, by including specific information indicating the information in the communication information, the receiving device 102 can calculate the fluctuation of the visible light signal 190 at the update timing of the image light signal 191. It becomes possible to eliminate errors.

  FIG. 8 is a diagram for explaining a reception process of the reception device 102. In FIG. 8, the horizontal axis indicates time, and in order from the top, the light reception signal at the first light receiving unit 230, the light reception signal at the second light receiving unit 233, the output signal of the first difference processing unit 232, and the second difference processing unit. 235 shows an output signal and communication information. The light reception signal at the first light receiving unit 230 and the light reception signal at the second light receiving unit 233 are orthogonal to each other. The first difference processing unit 232 calculates a difference (first difference value) between the polarization signal from the first light receiving unit 230 and the delayed polarization signal from the first buffer 231, and the second difference processing unit 235 The difference (second difference value) between the polarization signal from the second light receiving unit 233 and the delayed polarization signal from the second buffer 234 is calculated. The received light signal analysis unit 236 sets the communication information to 0 (Tj + 5 to Tj + 7) when the difference value is continuously less than the predetermined value, and sets the communication information to 1 when the difference value is continuously the predetermined value or more. (Tj + 1 to Tj + 3).

  9 and 10 are diagrams for explaining the operation of the communication light emission control unit 112 of the liquid crystal display 101, FIG. 9 is a front view of the screen of the liquid crystal display 101, and FIG. 10 is a control example of the communication light emission control unit 112. FIG. The screen of the liquid crystal display 101 shown in FIG. 9 is used for an area (image area 272) for displaying an image arranged at the center, and for communication arranged between the image area 272 and the casing 270. Area (communication area 271). A part of the communication area 271 includes communication light emitting pixels 10 to 15.

  In FIG. 10, the horizontal axis represents time, and in order from the top, communication information, lighting of the communication light emitting pixels 10 to 15, and visible light signal 190 corresponding to communication information output from the liquid crystal display 101.

  The communication light-emission control unit 112 blinks the communication light-emitting pixels 10 and 13 during the time Tk to Tk + 2 when the communication information is 1, and then for communication during the time Tk + 2 to Tk + 4 when the communication information 1 is next. The light-emitting pixels 11 and 14 are blinked, and the communication light-emitting pixels 12 and 15 are blinked at the time Tk + 6 to Tk + 8 when the communication information becomes 1 next. As a result, the number of pixels blinking when the communication information is 1 is constant, and the blinking pixels are periodically switched. Therefore, the lifetime of the liquid crystal unit 217 is maintained while the amount of the visible light signal 190 to be irradiated is constant. Can be lengthened. Further, when the number of times of light emission per time of each pixel is small, the pixel is visually recognized as black, and when it is large, it is visually recognized as white. For this reason, by reducing the number of times of light emission per time of each pixel in the communication area 271, the communication area 271 is visually recognized as a black belt, and the image drawn in the image area 272 is visually recognized. Does not affect. For example, during the period from time Tk to Tk + 13, the communication light emitting pixel 10 blinks only during the period from time Tk + 1 to Tk + 2. As a result, the brightness of the communication light emitting pixel 10 is simply 1/13 of that of the case where the light emitting pixel 10 always emits light.

  As described above, in the liquid crystal display 101 in the second embodiment, as in the first embodiment, some pixels are used as communication ports, and communication information is transmitted to the receiving device 102. Wireless communication can be realized without providing a communication port in addition to the liquid crystal display 101, and the apparatus can be downsized. In addition, since light in the visible light region is used for transmission of communication information from the liquid crystal display 101 to the receiving device 102, there is no need to reduce transmission power as in the case of performing communication using infrared rays, and communication speed can be increased. It is possible to improve the communication range and improve the communication range.

  As described above, the transmission device, the reception device, and the communication method according to the present invention can reduce the size of the device and are useful as a transmission device or the like.

1 is a basic configuration diagram of a visible light communication system in a first embodiment. It is a block diagram of the communication information acquisition part of a receiver. It is a figure which shows the transmission output signal of a liquid crystal display. It is a figure explaining the difference process in a receiver. The example of the 2-bit information allocated to the vector of a polarization signal is shown. It is a basic block diagram of the visible light communication system in 2nd Example. It is a figure explaining the transmission process of a liquid crystal display. It is a figure explaining the reception process of a receiver. It is a front view of the screen of a liquid crystal display. It is a figure which shows the example of control of the light emission control part for communication. It is a basic block diagram of the conventional liquid crystal display.

Explanation of symbols

  10, 11, 12, 13, 14, 15 Communication light emitting pixel, 101 Liquid crystal display, 102 Receiver, 103, 215 Light emitting unit, 104, 216 First polarization unit, 105, 217 Liquid crystal unit, 106, 218 Second polarization 107, 250 Image light emitting unit, 108, 251 Communication light emitting unit, 109 gap, 110 Display communication control unit, 111 Image light emission control unit, 112 Communication light emission control unit, 113 Communication information storage unit, 114 Image information Storage unit 115, 230 First light receiving unit 116, 233 Second light receiving unit 117 Communication information acquisition unit 201 First communication information presence / absence determination unit 202 Second communication information presence / absence determination unit 203 Comparison unit 219 220, protective film, 231 first buffer, 232 first differential processing unit, 234 second buffer, 235 second differential processing unit, 23 Received light signal analysis unit, 260 First image polarization unit, 261 First communication polarization unit, 270 Case unit, 271 Communication region, 272 Image region, 280 Second image polarization unit, 281 Second communication polarization Department.

Claims (15)

A liquid crystal unit composed of communication pixels and image pixels;
A communication light emitting unit that emits communication light toward the communication pixel;
An image light emitting unit that emits image light toward the image pixels;
Only one polarized light of the communication light from the communication light emitting unit is allowed to pass toward the communication pixel, and only one polarized light of the image light from the image light emitting unit is passed to the image pixel. A first polarizing section that passes through
Polarization control means for polarizing communication light incident on the communication pixel based on communication information, and polarizing image light incident on the image pixel based on image information ;
A second polarizing section that allows only one polarization of image light polarized in at least the image pixel to pass through;
Have
In at least one of the first polarization unit and the second polarization unit, the same polarization conversion as that applied to the image light is not applied to the communication light. Transmitter device.   The transmission device according to claim 1, further comprising: a communication light emission control unit that controls light emission by the communication light emitting unit based on the communication information. Said second polarization unit, the transmission device according to light for communication polarized in the communication pixels to claim 1 or 2, characterized in the Turkey pass without being polarized. The first polarization unit polarizes the communication light from the communication light emitting unit and the image light from the image light emitting unit so that the polarization angles thereof are orthogonal to each other , and Henhikaribu, said the light for communication polarized in communication pixels, and light for polarized image in pixels for the image, is polarized such that the polarization angle orthogonal to each other, it is characterized in claim Item 3. The transmitter according to Item 1 or 2.   The transmission device according to claim 1, wherein the communication pixel is disposed on an outer edge portion of the liquid crystal unit.   The communication light emission control unit emits the same number of light sources among a plurality of light sources constituting the communication light emitting unit and periodically switches the light sources to emit light corresponding to each communication information. The transmission device according to claim 2.   The transmission apparatus according to claim 1, wherein the communication light is light in a visible light region. A light receiving means for receiving other light together with the polarized light based on the communication information;
Communication information specifying means for specifying the communication information based on a polarization angle of light received by the light receiving means ;
Communication time determining means for determining whether the light received by the light receiving means corresponds to the communication information communication time or non-communication time,
The communication information specifying unit specifies the communication information based on a difference between a polarization vector of light received by the light receiving unit during communication and a polarization vector of light received by the light receiving unit during non-communication. A receiving device. The light receiving means is
A first light-receiving unit that receives one polarized light of the reaching light;
The receiving device according to claim 8, further comprising: a second light receiving unit that receives polarized light whose polarization angle is orthogonal to the polarized light received by the first light receiving unit out of the reaching light . A light emission step for communication that irradiates light for communication toward the pixel for communication constituting the liquid crystal unit;
An image emission step of irradiating image light toward the image pixels constituting the liquid crystal unit;
Only one polarization of the communication light emitted in the communication light emission step is transmitted toward the communication pixel, and one polarization of the image light emitted in the image light emission step. A first polarization step to pass only the image pixels to the image pixel;
A polarization control step of polarizing communication light incident on the communication pixel based on communication information, and polarizing image light incident on the image pixel based on image information;
In the polarization control step, a second polarization step for passing only one polarization of at least the image light polarized in the image pixel;
Have
In at least one of the first polarization step and the second polarization step, the same polarization conversion as that applied to the image light is not applied to the communication light. Communication method . The communication method according to claim 10, further comprising: a communication light emission control step for controlling light emission in the communication light emission step based on the communication information . The communication light emission control step emits the same number of light sources among the plurality of light sources emitted by the communication light emission step and periodically switches the light sources to emit light corresponding to each communication information. The communication method according to claim 11, wherein: The communication method according to claim 10, wherein the communication light is light in a visible light region . A light receiving step for receiving other light together with the polarized light based on the communication information;
A communication information specifying step for specifying the communication information based on a polarization angle of the light received by the light receiving step;
A communication time determination step for determining whether the light received by the light receiving step corresponds to a time of communication of the communication information or a non-communication time;
The communication information specifying step specifies the communication information based on a difference between a polarization vector of light received by the light receiving step during communication and a light polarization vector received by the light receiving step during non-communication. A communication method characterized by the above . Including a transmitting device and a receiving device,
The transmitter is
A liquid crystal unit composed of communication pixels and image pixels;
A communication light emitting unit that emits communication light toward the communication pixel;
An image light emitting unit that emits image light toward the image pixels;
Only one polarized light of the communication light from the communication light emitting unit is allowed to pass toward the communication pixel, and only one polarized light of the image light from the image light emitting unit is passed to the image pixel. A first polarizing section that passes through
Polarization control means for polarizing communication light incident on the communication pixel based on communication information, and polarizing image light incident on the image pixel based on image information;
A second polarizing section that allows only one polarization of image light polarized in at least the image pixel to pass through;
In at least one of the first polarization unit and the second polarization unit, the same polarization conversion as that applied to the image light is not applied to the communication light.
The receiving device is:
A light receiving means for receiving light polarized based on the communication information;
Communication information specifying means for specifying the communication information based on a polarization angle of light received by the light receiving means.
An optical communication system .

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