JP2007324671A - Illumination light communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an appropriate and efficient optical system between a mobile unit and lighting fixtures. <P>SOLUTION: An illumination light side light receiving unit 13 comprises a light receiving sensor 14, and three pilot light sources 16A, 16B, 16C. The pilot light sources 16A, 16B, 16C configure a pilot light emitting group 16. Central points of the pilot light source 16A, the light receiving sensor 14, and the pilot light source 16B are respectively located on a virtual straight line L1, and a central point of the pilot light source 16C is located on a virtual straight line L2 orthogonal to the virtual straight line L1. Through the configuration above, the mobile unit side can easily determine the position and the direction of the light receiving sensor at the illumination side, and it is possible to form the proper and efficient optical system (optical axis, luminance setting or the like) between the mobile unit and the lighting fixtures. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination light communication apparatus.

  With recent improvements in LED emission brightness, discussions about lighting fixtures using LEDs (Light Emitting Diodes), information distribution by information display fixtures, and two-way communication have become active. Since LEDs have excellent response speed and are easy to control electrically, lighting fixtures using LEDs can be used as communication equipment in addition to functions as lighting equipment by blinking at a speed that is not perceived by human eyes. Functions can be provided at the same time.

  Communication using visible light is a problem that may interfere with important life-related equipment such as medical equipment and aircraft navigation control equipment in wireless communication systems, and irradiation of human eyes with infrared communication. It has an excellent aspect as a system that does not cause problems that cause obstacles.

  In a visible light communication system, it is necessary to align an optical axis between a light emitting unit and a light receiver to form an appropriate and efficient optical system, and conventionally, a user of a mobile device has performed this optical axis alignment visually. As a conventional technique for improving this optical axis alignment, the light emitting state such as the light emission signal intensity, the color, the blinking cycle, and the blinking width is changed according to the reception state in the opposite optical receiving device in order to perform the optical axis adjustment alone. A technique for improving the accuracy of optical axis alignment and shortening the adjustment time by adding a device (see Patent Document 1) has been proposed.

  In addition, as a further conventional technique for aligning the optical axis, the laser pointer, which is an indicator that emits visible light, can be detachably attached to the terminal unit, so that the optical axis of the terminal unit and the optical axis of the satellite unit can be attached only when necessary. Has been proposed (see Patent Document 2).

  Further, as a further conventional technique, the illumination light modulated by the data emitted by the illumination communication device is received, the light receiving means for acquiring the data, and the illumination light is reflected by the corner cube reflector and modulated according to the data to be transmitted. There has been proposed an apparatus (see Patent Document 3) that has reflection modulation means for transmitting the reflected light and transmits the reflected light toward the illumination light source.

Further, as a further conventional technique, an apparatus (see Patent Document 4) that performs communication without reducing the illuminance of illumination and without reducing the luminance level of the display has been proposed. Conventionally, in data transmission from the terminal to the lighting device side, it has been considered to transmit data using a white light source such as an auxiliary light of a mobile phone or a flash light source as in the case of downlink communication.
Japanese Patent Laid-Open No. 4-117636 (Optical space communication system, etc.) JP-A-5-153063 (Optical axis adjustment structure) JP 2004-072365 A (Illumination light communication) Japanese Unexamined Patent Application Publication No. 2004-072365 (Optical Communication Device, etc.)

  However, in the conventional optical communication system using illumination light, control of “downstream light” is emphasized, and control of “upstream light” from the mobile station side to the illuminator side has been hardly considered. That is, in order to form an appropriate and efficient optical system between the mobile device (terminal device) and the illumination light communication device, use and control of “upstream light” (upstream communication light) is also important. Very little technology has been developed for this. Also, in order to realize an appropriate and efficient optical system, it is considered that the optical axis is aligned with the other party (illumination optical communication device side) that the mobile device wants to emit light, but the light emission brightness on the mobile device side is controlled. I wasn't even thinking about doing it. In addition, in the conventional systems of Patent Documents 1 and 2, the optical axis alignment needs to be performed by the user, which reduces user convenience and optimizes the light emission power only by aligning the optical axes. As a result, there was a problem of consuming unnecessary power.

  Further, in the system of Patent Document 3, since the light source from the mobile device communication device is the light source of the illumination light communication device, there is a problem that transmission data of the mobile device communication device cannot be transmitted when the illumination brightness is dark.

  In an illuminating light communication system, it is conceivable that bidirectional communication is performed in a time division multiplexing manner and communication is performed while changing the timing with uplink communication. However, there arises a problem that the data transmission efficiency of the system is lowered. Especially in downlink communication, it is considered that the frequency of moving image information distribution and user information collection is high, so it is preferable to have a high transmission rate, but the data transmission rate is reduced by sharing time with uplink communication. It is a problem. In order to maximize the uplink / downlink data transmission rate, it is necessary to have each communication path separately. For this reason, the upstream and downstream communication frames are asymmetrical, and it is considered to be important to use a frame that places importance on the downstream communication transmission rate.

  At this time, in the environment where light is obtained from the white LED, if the white LED is used for data transmission from the terminal to the illumination device side light receiver, a problem that the S / N ratio deteriorates occurs. In particular, an illumination device used in an office needs to secure the illuminance at hand of an operator in the office and unfavorable illumination unevenness, so that directivity is weak like a fluorescent tube and it is necessary to emit strong light. The same tendency is strong for station premises and hospital meeting rooms. In this environment, a sensor that receives light emitted from the terminal is likely to be exposed to strong illumination light. For this reason, when the light emitted from the terminal is white, the illumination light becomes a strong interference source, resulting in a deterioration in the S / N ratio of the light receiving sensor on the illumination device side.

  The present invention has been made in view of these problems, and a plurality of lighting fixtures that transmit data superimposed on illumination light and a bidirectional that transmits data superimposed on visible light to a mobile device. In the optical transmission system, the light emission brightness of the mobile device (terminal device) and the optical communication device is kept to the minimum necessary to form an appropriate and efficient optical system between the mobile device and the lighting fixture, and other movements The purpose is to provide an optical communication technique that can prevent simultaneous access from the machine.

In order to solve the above-described problems, the illumination optical communication apparatus according to the first invention is
An illumination unit (such as an LED) that illuminates by assigning illumination light with superimposed information to each of the time-divided time slots;
A pilot light emitter (such as an LED) that emits pilot light (test light) indicating the timing of each of the time slots;
A light receiving unit (phototransistor, CCD, etc.) that receives light emitted from a terminal device that is arranged around the pilot light emitting unit and receives information of the illumination light to obtain information;
It is characterized by providing.

An illumination light communication apparatus according to the second invention is
There are at least two pilot light emitting units,
The at least two pilot light emitting units are disposed with the light receiving unit interposed therebetween (preferably, the pilot light emitting unit, the light receiving unit, and the pilot light emitting unit are arranged substantially in a straight line in this order). Features.

  As described above, the solution of the present invention has been described as an apparatus (system). However, the present invention can be realized as a method substantially equivalent to these, and these are also included in the scope of the present invention. Should be understood.

  According to the present invention, the optical axis can be easily obtained by using the positional relationship between the light receiving unit provided in the illumination light communication device and the pilot lamp, or various control instructions can be generated by the upstream light from the terminal side using the light receiving unit. Therefore, an appropriate and efficient optical system (optical axis, brightness setting) is formed between the terminal device (mobile device) and the illumination light communication device, and the terminal device and the optical communication device It is possible to minimize the light emission luminance. For example, easily depending on the disturbance (temperature, humidity, dust floating in the atmosphere, shielding by people, incident light from outside the room, etc.) between the two devices and the distance / positional relationship between the two devices It is possible to adjust the luminance of light emitted from the terminal device side to an optimum one in response to the fluctuation of the optical system that is easily affected.

  The configuration of the illumination light communication apparatus according to the present invention will be described. In the optical communication system according to the present invention, the light receiving and emitting devices are synchronized with each other, and perform communication using visible light that performs data communication at a predetermined timing. Further, at least two light sources (pilot lights) are provided around the illumination light side light receiver. Moreover, it arrange | positions on the circumference of the circle | round | yen centering on the center part of the said light source receiver. The plurality of pilot light sources are composed of red, green, and blue LEDs, and can emit a plurality of colors. The plurality of pilot light sources emit light at different timings. The emission brightness of the mobile device is controlled by controlling the brightness, color and timing of the pilot light. When mobile device light emission luminance control (communication negotiation) is started, the light emission timing of the pilot light is emitted at the luminance control timing. After the emission brightness of the mobile device is determined, the emission brightness of the pilot light is adjusted and optimized. While the communication is continued, the mobile device light emission luminance control and the pilot light luminance control are performed at regular intervals.

  With the above-described configuration, it is possible to perform communication in which S / N does not deteriorate by using light having a wavelength different from the wavelength of illumination light for upstream communication. For this reason, high-quality data communication can be performed with less power. In other words, the data transmission rate can be increased with the same power. In the past, humans performed optical axis alignment, but in the present invention, optical axis alignment can be performed automatically and optimal light emission brightness control of the mobile device is performed, so that the user does not have to be aware of the position of the light receiver. Rich in nature. In addition, since the user does not need to worry about optical axis adjustment, data can be transmitted without stopping applications such as e-mail and Web browsing.

Since the mobile device starts light emission after specifying the position of the photoreceiver, it is possible to prevent the surroundings of the photoreceiver (ceiling or wall) from being brightly illuminated by the highly directional light emitted by the mobile device.
By searching for pilot light at a constant period, it is possible to keep the optical axis aligned, so that optical communication can be performed even while the mobile device is moving. Since the mobile device emits light with the minimum amount of light required by the light receiver, the power consumed during data communication can be kept to a minimum.

  The luminance characteristics of LEDs, which are light emitting elements, vary depending on the colors used. For example, red and blue LEDs have different luminous efficiencies due to differences in materials used. Different product series have different light emission characteristics. This is the difference between Company A's B series and Company C's D series. Even in the same product, individual characteristics do not completely match and vary. Since this characteristic variation can be eliminated by calibration performed for each mobile device, the luminance variation of the element can be allowed. Because brightness control is performed, fluctuations due to changes in the light receiving environment (scintillation) can be absorbed.

By adjusting the brightness of the pilot light after adjusting the light emission brightness of the mobile device, the current consumption for driving the pilot light source can be minimized.
It is possible to almost avoid the collision of communication that can occur when a plurality of mobile devices try to start communication.

When the data size transmitted by the mobile device is large and there is an empty slot, it is possible to easily increase the transmission throughput by using the empty slot for data transmission.
Since the one-to-one communication is performed after the pilot light search, it is only necessary to monitor the signal level for upstream and downstream communications, and there is no need to perform modulation. Therefore, the system is simple and there is no need to perform complicated processing for demodulation. In particular, for mobile devices, the processing speed can be increased and power consumption can be reduced by not performing arithmetic processing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system configuration diagram showing a basic configuration of an illumination light communication system according to the present invention. As shown in the figure, the illumination light communication system according to the present invention includes an illumination light communication device 100 and at least one terminal device (mobile device) 200. Illumination light communication device 100 includes illumination unit 110, pilot light emitting unit 120, light receiving unit 130, photodetector PD1, pilot light source PL, LED for illumination (LED-DWN), and control for controlling each of these units and the entire device Part 140 is provided. The illumination unit 110 uses an illumination LED (LED-DWN) provided with a plurality of LEDs (LED1, LED2, LED3, etc.) to time-divide the illumination light for optical communication (downlight) on which information is superimposed. Allocate and irradiate each time slot. This light functions as illumination light and a communication medium. Further, the pilot light emitting unit 120 uses a pilot light source PL including three color light emitting elements (PL1, PL2, PL3) so that full color can be reproduced, and pilot light (test light) indicating the timing of each time slot. Is emitted. In addition, the light receiving unit 130 receives light (uplink light for optical communication or instruction light) emitted from the terminal device 200 by using the photodetector PD1 with a function of detecting light (visible light). Based on the light reception level of the light emitted from the terminal device 200 received by the light receiving unit 130, the control unit 140 emits light emitted from the pilot light emitting unit 120 (for example, luminance, color, light emission timing and light emission pattern in the slot). The control is performed so as to adjust the “change of the light emission timing, light up multiple times, light up with different brightness or color between the light emission of multiple times”, and the like.

  The terminal device 200 includes a light receiving unit 210, a light emitting unit 220, a control unit 230, a storage unit 240, a photodetector PD2, and an upstream light LED (LED-UP). The light receiving means 210 receives the pilot light emitted from the illumination light communication apparatus 100 using the photodetector PD2. The light emitting means 220 emits light using an upward light LED (LED-UP). Based on the adjusted pilot light emitted from the illuminating light communication apparatus 100 received by the light receiving means 210, the control means 230 is a luminance of light emitted from the light emitting means 220 using the LED for upward light (LED-UP). Control to adjust.

  FIG. 2 is a conceptual diagram showing the entire system. On the ceiling, an illumination light communication device 10 that is normal illumination and a spot illumination light communication device 10A are installed. In the space under the ceiling, there is a mobile device (terminal device) 20 that is carried by the user or placed on a table. The illumination light communication devices 10 and 10A include illumination LEDs 12 using LEDs as light emitting elements, and can perform communication using visible light. The illumination light communication devices 10 and 10A include an illumination light side light receiver 13, and the light receiver includes a light reception sensor 14 and a plurality of pilot light sources 15 provided around the light reception sensor.

  Here, the mobile device (terminal device) 20 refers to a terminal that a user carries for the purpose of data communication, and includes a notebook personal computer, a laptop personal computer, a PDA, a mobile phone terminal, etc., but it is necessary to include a wireless communication means. There is no. As places where users perform data communication using illumination light for a certain period, coffee shops, airplanes, trains, hospital waiting rooms, wards, offices, etc. are most applicable. Mobile devices communicate not only with narrowly defined lighting devices, but also with devices that use or replace LED arrays as light sources, such as light emitting devices and display devices that use light such as neon lights, signboards, and electric bulletin boards. It becomes. In general, downlink data transmission includes Web site browsing, video and music download, distribution of various store information, etc., and is often used more frequently than uplink and requires a data transmission speed. In the figure, the illumination light device is provided with three LEDs, and each LED is prepared for transmitting data exclusively to the mobile device. On the other hand, the mobile device transmits data to a light receiving sensor provided in the light receiver on the illumination side. Since it is not necessary to equalize the frequency of uplink data transmission compared to downlink data transmission, here, a mechanism is adopted in which three mobile devices emit light to one light receiver.

  The light receiving sensor (not shown) of the mobile device 20 is provided integrally with a light emitting element (not shown) with the same optical axis, and can be freely changed in the direction of the zenith. Furthermore, a motor (not shown) is also provided, and the direction (of the optical axis) can be automatically changed in the zenith direction. The light receiving sensor specifically refers to a CMOS or CCD sensor, and the mobile device 20 is equipped with a camera. It is desirable that the light emitting element of the mobile device 20 emits light only toward the illumination light side light receiver to which a signal is to be sent. The light emitting element of the mobile device 20 is not suitable for the illumination light side light receiver 13 because it becomes interference light, lowers the S / N ratio, causes unnecessary processing, or lowers power efficiency. It is necessary to emit light with strong directivity. For this reason, it is necessary for the light emitting element to further collect a highly directional LED using an optical lens or to use a semiconductor laser.

  FIG. 3 is a layout view of the illumination-side light receiver that is a component of the illumination light communication apparatus. The illumination light side light receiver 13 includes a light receiving sensor 14 and three pilot light sources 16A, 16B, and 16C. These three pilot light sources 16A, 16B and 16C constitute a pilot light emitting element group 16. The center points of the pilot light source 16A, the light receiving sensor 14, and the pilot light source 16B are located on the virtual straight line L1. Further, the center point of pilot light source 16C is located on virtual straight line L2 orthogonal to virtual straight line L1. The virtual straight lines L1 and L2 are located in the ceiling SL. The center points of the pilot light sources 16A, 16B, and 16C are arranged on the circumference of the same circle with the orthogonal point of the virtual straight lines L1 and L2 as the center. Note that FIG. 3 is a perspective view, and for the convenience of drawing, distances and positional relationships between the elements are not accurate.

  By measuring the position (direction) of each light source arranged in this way from a mobile device (terminal device) located in an arbitrary space in the lower space of the ceiling SL, the light receiving sensor is geometrically easy and reliable. It is possible to determine the three-dimensional coordinates of the center point (ie, the optical axis connecting the two). Since the mobile unit moves and the position seen from the pilot light source is not constant, the position of the light receiving sensor is specified when at least two light sources are not located on the straight line passing through the light receiving sensor. It is difficult to do. When a plurality of pilot light sources are provided, the respective positions are arranged as close as possible to the center of the light receiving sensor. Moreover, it becomes easy to calculate the position of the light receiving sensor by arranging each light source at an equal angle. For example, when there are six pilot light sources, each angle is arranged at 60 °.

  FIG. 4 is a control block diagram of components of the illumination light communication apparatus. As shown in the figure, the control unit 340 executes a command such as a program read from the storage unit ST or the like, and controls the overall luminance of the apparatus (CPU) that controls the entire apparatus, and the luminance that controls the emission luminance of the pilot light source group PL A control unit BLC, a modulation unit MOD for controlling the light emission timing, and the like are included. The pilot light source group PL is composed of red, green, and blue LEDs (PL1, PL2, PL3). The LEDs of each color (PL1, PL2, PL3) are connected to the brightness control units BLC1, BLC2, BLC3 for red, blue, and green, and the modulation units MOD1, MOD2, and MOD3 for each color that control timing. The modulation unit MOD that receives the signal performs control according to the input signal. The luminance of the signal is controlled by the CPU. The clock generator CLK oscillates at an optimum frequency to make a system time, and supplies a clock to a block that requires data transmission / reception. For this reason, various data can be transmitted and received at the required timing. Although not shown, the control unit 340 also includes a luminance control unit and a modulation unit for LEDs for illumination light communication, and performs substantially the same operation except for superimposing information transmission data on the illumination light.

  After the level detector LM detects the light reception level (brightness) of light from the mobile device (terminal device) received by the light receiving sensor LS and converts the detected value into a digital signal by an A / D converter (not shown). The optical signal acquired by the CPU and received by the light receiving sensor LS is demodulated by the demodulator DM and transferred to the CPU. The CPU is connected to a data transmission path, and performs various processes such as distribution of data to LEDs for illumination light communication (not shown), data processing, luminance control, and adjustment of light receiving / emitting timing. The data transmission path is connected to a power line when a communication line such as a LAN cable or an optical fiber or power line communication is performed.

  FIG. 5 is a timing chart showing data transmission / reception timing of the illumination light side light receiver and data transmission timing of the illumination light communication apparatus. The entire system operates with time synchronization. The mobile device, the illumination device, the light receiver, and the pilot light source are time-synchronized.

  FIG. 5A is a conceptual diagram of light emission / light reception timings of the pilot light source and the light receiver. The light emission / light reception timing is divided into a pilot light emission section, a luminance adjustment section (downlink light), and a data reception section (uplink light). In the pilot light emission section, a pilot light source provided around the light receiving sensor on the illuminator side as shown in FIG. 3 emits light in a designated color. A mobile device (terminal device) is used for searching the position of the light receiving sensor and aligning the optical axis. When the mobile unit finishes the optical axis alignment, it enters light emission luminance adjustment. The brightness adjustment section is used at this time. The data transmission section is a section used for data transmission when the light emission luminance adjustment is completed. The reception data of the mobile device is transmitted from the illumination device, and the data is superimposed on the illumination light, and the emission luminance is controlled to be kept constant. In the present invention, a detailed description of data reception by the mobile device is omitted. The slot length (time interval of one slot) is determined by the data rate required for the system and the response characteristics of light emitting elements such as illumination light, pilot light source, and mobile unit LED. When a high data rate is required, it is necessary to shorten the slot.

  FIG. 5B shows the data transmission timing of the lighting device. Downlink communication does not require brightness adjustment or pilot brightness control performed by the light receiver. Also, the formats of uplink and downlink data transmission are different. For this reason, the rise of the signal is at the same timing as the light receiver side, but the illumination device transmits data even in the section where the illumination light side light receiver performs pilot brightness control or mobile device brightness control. It becomes.

  FIG. 6 is a timing chart showing the timing when emphasizing data reception. In FIG. 5, for the sake of simplification, the data receiving section is a diagram in which data is transmitted in one slot of each color. In this figure, three colors of red (lattice), green (shaded), and blue (horizontal line) are used. It is a figure at the time of assembling a system by making 5 slots into 1 unit of light-receiving area. A large number of slots corresponding to the number of data bits such as 10 slots and 128 slots are allocated according to the importance of data.

  FIG. 6 is a timing chart showing an example of the operation timing of the system when light is received in five slots. Here, for simplicity, the illumination light device is composed of three LEDs, and the pilot light source is controlled by three colors of red (lattice), green (shaded), and blue (horizontal line), of which In this example, communication negotiation is performed using two colors. It is a well-known fact that pilot light sources can produce various colors by adjusting and mixing the brightness of each of the three colors of red, green, and blue. For pilot light, the same number of colors are prepared according to the number of terminals that the lighting device can communicate with. For example, when the lighting device is composed of 10 LEDs and can communicate with 10 terminals, 10 colors are prepared as pilot light emission sources, and light is emitted sequentially at the timing of 10 slots.

  FIG. 7 is a timing chart showing the timing at which the illumination light communication apparatus controls the light emission luminance of each mobile device. In this example, three slots (that is, channels) are prepared in three colors of red, green, and blue. As shown in FIG. 7A, the pilot light sources 1 and 2 periodically emit pilot light of colors corresponding to the empty slots (in this example, all three colors are empty slots). On the mobile station side, since pilot light needs to be recognized first, pilot light search is performed. Since the length of one frame is not known at this time, light is received in the longest time normally used on the system. The received data is processed to recognize the strongest pilot light color. Next, check if the color is received at least three times. Receiving light three times is equivalent to searching for at least one period (one frame). Since the section with two received light sources is the pilot light receiving section and the section with three light sources is the mobile unit brightness adjustment section, the pilot light emitting section can be recognized by the difference in the number of light emitting light sources. Simultaneously with the above recognition, the time of one frame is recognized.

  Next, a peripheral search (light source search operation) is performed to search for the strongest pilot light. After completing the search, point the camera at the strongest light and align the optical axis. The mobile device that has finished optical axis alignment emits light toward the light receiving sensor of the illumination optical communication device. In the example shown in the figure, upon receiving the pilot red light emission R1 at the reference luminance B1, as shown in FIG. 7C, the mobile device 1 performs the response red light emission Re1 at the luminance BT1. The illumination side light receiving sensor receives the light from the mobile device 1 and simultaneously checks its intensity. A signal for controlling the light emission luminance of the mobile device according to the intensity is emitted from the pilot light source 3 in the next slot. Since the pilot light sources 1 and 2 serve as a reference for the light emission level of the pilot light source 3, they always emit light with a constant intensity (reference luminance B1). When the light from the mobile device has a sufficient level with respect to the sensitivity point of the illumination side light receiving sensor, the pilot light source 3 emits light at a low level with respect to the pilot light sources 1 and 2. That is, as shown in FIG. 7B, the pilot light source 3 emits the red light emission R3 at a luminance B3 (becomes an instruction light for instructing luminance reduction) lower than the same reference luminance B2 as the reference luminance B1. The mobile device 1 that has received the red light emission R3 that is the instruction light for lowering the luminance emits a response red light emission Re2 with a luminance BT2 lower than the previous luminance BT1. When the sensitivity point is reached, the pilot light sources 1, 2, and 3 are caused to emit light with the same intensity (reference luminance B1, B2). When there is no margin with respect to the sensitivity point (insufficient brightness), the pilot light source 3 is caused to emit light strongly and the light emission brightness of the mobile device is increased, which will be described later.

  The next section is a pilot light emission section, but light emission in the pilot light emission section stops immediately after the start of luminance adjustment. As a result, the collision of access is only one slot for making an access request, so that the collision is hardly performed. In addition, since the mobile station performing the pilot search does not recognize the slot having the color in use, the other mobile stations that have started the pilot search do not detect unnecessary pilot light, which is useless. Thus, efficient processing can be performed without generating any processing.

  Since the pilot light source emits light at high speed (higher than the threshold perceived by humans), human eyes cannot be detected. Therefore, the color temperature of the illumination device is not changed by the emission of pilot light. The luminance control level step preferably takes into account the required data rate. This is because adjustment takes too much time when the communication speed is slow and the brightness control step is fine. Further, the next section is a data transmission section. When the luminance adjustment is completed, data is transmitted using this section. Even during data transmission, the luminance is always adjusted in the luminance adjustment section, and data transmission is performed at the adjusted level.

  FIG. 8 is a flowchart showing processing from pilot light search to mobile device light emission luminance adjustment. As shown in the figure, when the user enters the visible light communicable area, the operation is started by the user's operation. The mobile device receives light for a certain time without zooming the lens in order to investigate the timing of the area. By performing image processing with the CPU in the mobile device, it is possible to recognize how many colors the area is using during this period. Further, the rising timing of the pilot light with the strongest reception level is detected. The clock of the mobile device is synchronized with this timing (S1, S2).

  Next, a peripheral search is started in step S3. The camera is moved in all zenith directions according to the angle of view of the camera mounted on the mobile device (S4), and the light intensity and position of the pilot light that can be received are sequentially stored (S5, S6). Since two or more pilot lights are emitted per light receiver, it is easy to specify the position. After confirming that all searches have been completed (S7), select the light with the strongest intensity from the accumulated data, set the camera position to the communication partner in the direction of this light (S8), and end the peripheral search operation. (S9). After the search is completed, the mobile device moves to the light emission luminance control operation (S10). After confirming the searched pilot light again, if the camera has a zoom function, the zoom is performed (S11). Since the mobile device has a high possibility of moving, and it is expected that the camera image will be blurred in accordance with the movement, zoom is not performed to the full image of the camera in order to make the zoom in consideration of blurring. By performing zooming, the optical axis of the mobile device light emitting means and the central axis of the illumination light side light receiving sensor are accurately aligned.

  Next, in step S12, the mobile device emits light for the first time with respect to the illumination light side receiver. The light emission intensity follows a table associated with a light emission level (predetermined luminance) corresponding to the light reception level stored in the storage unit in advance. If light is emitted before adjusting the optical axis, the illumination light side light receiver cannot emit light, and the ceiling or wall on which the light receiver is installed is illuminated, which consumes unnecessary power. When light from the mobile device is received on the illumination light side (S13), the level is inspected (S14).

  The illumination light communication device stores in advance the sensitivity level of the light receiving sensor and the light receiving level reference from the mobile device. When the received light level is outside this reference, it is determined whether it is within the reference level (S15, S20), and a series of operations for adjusting the mobile device light emission level is performed until it falls within the reference level (S16-S19, S22-S24). ). This reference is obtained from the sensitivity of the light receiving sensor and the allowable value of the level fluctuation of the mobile device that moves over time, and a numerical value obtained by adding this allowable value from the sensitivity point is stored.

  When the light receiving level is lower than this reference, the pilot light is emitted so as to emit a level one step stronger (S16). For example, in the example of FIG. 7, the mobile device 2 that has received blue light emission BL1 emits response blue light emission with luminance BT3 as shown in FIG. 7 is lower than the reference, and as shown in FIG. 7B, the blue light emission BL3, which is the instruction light for instructing the higher luminance by the pilot light source 3, is changed to the luminance B4 higher than the reference luminance B2 (that is, , At a level stronger than the reference brightness B1 of the pilots 1 and 2. As shown in FIG. 7, the timing of light emission is changed so that light is emitted in the luminance adjustment section. At this time, since the pilot light becomes invisible for the mobile station performing the peripheral search, it is excluded from the search target and access collision is avoided. The mobile device emits response blue light emission BLe2 at a level (luminance BT4) stronger by one step in accordance with blue light emission BL3 which is a luminance control instruction by pilot light.

  The brightness adjustment is continued until it falls within the reference level (within the upper limit level and the lower limit level). On the other hand, the mobile device may have moved far away from the illumination side light receiving device. At this time, the light emission level of the mobile device is maximized and the brightness cannot be increased. In this case, since the light emission from the mobile device does not reach, the pilot light search is started, and the nearby illumination light side light receiver is searched. The brightness of the mobile device is controlled by controlling the brightness of the mobile device in the same way as when it is higher or lower than the reference level.

  Here, a process when it is detected that the communication path is blocked during each process will be described. When the pilot search is being performed, the pilot search is performed a plurality of times at the camera angle at which the shielding occurs, and when the shielding is continued, the search is performed at the next angle. If shielding occurs during the mobile device light emission brightness adjustment, and there is no response of pilot light even if light is emitted a plurality of times, the optical axis adjustment is performed with the light receiver having the next highest light emission intensity as a result of the search. Here, if there is no response of the pilot light, the optical axes are aligned in order of increasing intensity as a result of the pilot search. When shielding occurs during pilot emission luminance adjustment, optical axis adjustment is performed in descending order from the result of the pilot search in the same way as during mobile device emission luminance adjustment, and alignment with the lower candidate is continued until communication is established. If communication is still not established, the pilot search is performed.

  FIG. 9 is a flowchart showing a brightness control process for adjusting the brightness of the pilot light source to emit light in the pilot light emission section. The processing steps are continuous with the flowchart of FIG. 8, and the luminance control of the pilot light is started after the emission luminance control of the mobile device is completed (S25). The pilot light is originally set to have a higher brightness than the illumination light, and the pilot light is first emitted at this high brightness (S26). This is a device for making it easier for the mobile device to search for pilot light. In step S27, the mobile device checks the brightness of the received pilot light. In the mobile device, the sensitivity point of the light receiving sensor mounted on the mobile device in advance is stored in the storage unit (memory) as a reference level with a value obtained by adding a margin of several dB from this sensitivity point. In addition, data in a table in which the light reception level and the light emission level are associated with each other is stored. The mobile device emits light according to the stored table according to the light reception level. The illumination light side light receiver inspects and stores the light emission level from the mobile device.

  The pilot light sources 1, 2, and 3 emit light with the same intensity next time, but when the mobile device determines that the received light level is lower than the stored lower reference level (S 28), the mobile device Since the pilot light may not be recognized, the mobile device emits light with a luminance higher than the previous light emission level, and emits an instruction light instructing to increase the luminance intensity of the pilot light source by one step (S37). In response to this instruction light, the pilot emits light at a brightness level one step higher (S38), the mobile device side checks the received light level (S39), and returns to step S28 to determine again whether it is lower than the reference level. Similarly, the operation of decreasing the brightness of the pilot light is performed in a series of steps S29, S34, S35, and S36. In this way, the mobile unit adjusts the brightness of the pilot light to an optimum level by emitting light that is stronger than the previous light emission brightness when it is desired to increase the brightness of the pilot light with reference to the previous light emission brightness and weaker when it is desired to decrease it.

  After the adjustment is completed (S30), transmission data is emitted from the mobile device and the data is transmitted (S31). After the pilot light brightness adjustment, the process shifts to data mobile device light emission brightness control. This cycle indicates whether data transmission has been completed (S32), whether the user has operated the mobile device to perform communication termination processing (S33), or if a light source could not be found even after multiple pilot searches. Exit when the mobile device is powered off. Advantages of optimizing the brightness of the pilot light include reduction of current consumption and prevention of interference with a pilot light source of another channel at a remote location.

  FIG. 10 is a timing chart showing the adjustment timing of the light emission luminance control on the illumination light side. The mobile device adjusts the luminance of the light source and adjusts the luminance of the pilot light source by instructing the illumination light side light receiving unit to control the luminance of the pilot light. As shown in FIG. 10A, the pilot light sources 1 and 2 emit red light emission R1 at the reference luminance B1. As shown in FIG. 10C, in response to the red light emission R1, the mobile device 1 performs response red light emission Re1 with a luminance BT2 lower than the original luminance BT1. On the side of the illumination light receiving this, the red light emission R2, R3 is emitted from the pilot light sources 1, 2, 3 with the luminances B3, B4 which are lowered by one step from the reference luminances B1, B2. When the mobile device 1 that has received the red light emission R2 and R3 is satisfied with this luminance, it emits response red light emission Re2 and Re3 with the initial luminance BT1, and the illumination light side indicates that the luminance control has been successfully completed. Notify

  Next, an example in which the luminance of the blue pilot light source is lowered by two levels will be described. As shown in FIG. 10A, the pilot light sources 1 and 2 emit the blue light emission BL1 at the reference luminance B1. As shown in FIG. 10 (d), upon receiving this blue light emission BL1, the mobile device 2 performs response blue light emission BLe1 with a luminance BT4 lower than the original luminance BT3. On the side of the illumination light that has received this, the blue light sources BL2, BL3 are emitted from the pilot light sources 1, 2, 3 with the luminances B3, B4 that are one step lower than the reference luminances B1, B2. If the mobile device 2 that has received the blue light emission BL2 and BL3 is not satisfied with the luminance, the mobile device 2 emits the response blue light emission BLe2 again with the luminance BT4 lower than the initial luminance BT3. In response to this, the pilot light sources 1, 2 and 3 emit blue light emission BL4 and BL5 at luminances B5 and B6 which are two steps lower than the reference luminances B1 and B2.

  FIG. 11 is a timing chart showing an example of control when the light emission period is changed. Here, a technique for performing brightness control by means different from the brightness control instruction of FIG. 8 will be described. As shown in FIG. 11A, the pilot light sources 1 and 2 emit green light emission G1 indicating that the green slot is an empty slot at the reference luminance B1. As shown in FIG. 11D, the mobile device 2 that has received the green light emission G1 emits a response green light emission Ge1 with luminance BT1 toward the illumination light receiver for connection request. By transitioning to this state, the mobile device can recognize that the connection request has passed and the brightness adjustment mode has been entered. A luminance control signal is included in the light emission pattern of the pilot light source 3. The illumination-side light receiver that has received the connection request from the mobile device 2 checks the reception level and starts brightness adjustment. The figure shows a case where the brightness of the mobile device 2 is low. When the brightness control mode is entered, the pilot light source 3 emits light at a strong level with respect to the pilot light sources 1 and 2. In this way, the brightness can be adjusted by giving the next light emission level strength with reference to the levels of the pilot light sources 1 and 2.

  In the example of the figure, the illumination light side light receiver that recognizes the light emission from the mobile device 2 blinks the next pilot light in the slot. That is, green light emission G2 and G3 that emit light twice in one slot are emitted. The green light emission G3 of the pilot light source 3 is performed at a brightness B3 higher than the reference brightness B2, and instructs the mobile device to increase the brightness. The mobile device 2 that has received the green light emission G3, which is an instruction light for instructing this luminance, emits a response green light emission Ge2 with a luminance BT2 that is one step higher than the initial luminance BT1. On the illumination light side, since the luminance condition is satisfied by this response, green responses G4 and G5 are subsequently emitted with the reference luminances B1 and B2, and the mobile device 2 is notified of the end of the luminance control.

  In the case of red light emission, this is an example of a luminance reduction instruction. As shown in FIG. 11C, the mobile device 1 that has received the red light emission R1 emits a response red light emission Re1 indicating a connection request with the initial luminance BT3. The illumination light side light receiver that has recognized the light emission from the mobile device 1 causes the next pilot light to blink in the slot, that is, to emit red light emission R2 and R3 that emit light twice. The red light emission R33 of the pilot light source 3 is performed at a brightness B4 lower than the reference brightness B2, and instructs the mobile device 1 to reduce the brightness. The mobile device 1 that has received the red light emission R3, which is an instruction light for instructing the decrease in luminance, emits a response red light emission Re2 with a luminance BT4 that is one step lower than the original luminance BT3.

  At this time, it is necessary to increase the processing speed for inspecting the pilot light luminance at the time of the pilot search as compared with FIG. 8, but it is not necessary to provide the luminance adjustment section independently and can be shared with the pilot light emission section. There is an advantage that does not decrease. The procedures of pilot light search, mobile device light emission luminance adjustment, and pilot light luminance control are the same as those in FIGS. Reduction of pilot brightness at this time has an effect of reducing current consumption.

  FIG. 12 is a timing chart showing an example of control by color change. In this example, the luminance of the pilot light source is constant, and the increase / decrease of the luminance is instructed by changing the color of the light source 3. As shown in FIG. 12A, the pilot light sources 1 and 2 emit green light emission G1 indicating that the green slot is an empty slot at the reference luminance B1. As shown in FIG. 12D, the mobile device 2 that has received the green light emission G1 emits a response green light emission Ge1 with luminance BT1 toward the illumination light receiver for connection request. In response to this request, the illumination light side receiver detects the light emission of the mobile device, checks the level, and compares it with the reference level. The figure shows a case where the level is low, with yellow light emission Y1 instructing to increase the light emission luminance of mobile device 2 by emitting pilot light source 3 in yellow (vertical line) and green light emission G2 of pilot light sources 1 and 2 as a reference. Perform with luminance B1 and B2. The mobile device 2 that has received the yellow light emission Y1 indicating this luminance increase instruction emits a response green light emission Ge2 with a luminance BT2 higher than the initial luminance BT1. Since it is not necessary to adjust the luminance in the next section, green light emission G3 and G4 are emitted in the color requested for connection.

  On the other hand, the mobile device 1 makes a connection request at a red timing. In this example, as shown in FIG. 12C, the mobile device 1 that has received the red light emission R1 indicating an empty slot sends a response red light emission Re1 with luminance BT3 toward the illumination light receiver for connection request. Exit. The figure shows a case where the level is high. Light emission W1 that gives an instruction to increase the light emission luminance of the mobile device 2 by emitting light of the pilot light source 3 in light blue and the red light emission R2 of the pilot light sources 1 and 2 are used as reference luminances B1 and B2. To do. The mobile device 1 that has received the light blue emission W1 indicating the luminance reduction instruction emits a response red light emission Re2 with a luminance BT4 lower than the original luminance BT3.

  In this way, the color for controlling the light emission luminance of the mobile device is determined in advance and ruled, and the light emission luminance of the mobile device is adjusted by the pilot light source 3. The connection procedure is the same as in the previous example. In this method, there is no need to provide a section for brightness adjustment as in the case of FIG. 7, and there is no need to blink the light source as in FIG. However, there are disadvantages that the two colors designated in advance for brightness adjustment cannot be used for the pilot light sources 1 and 2.

  FIG. 13 is a timing chart showing a control example in which the luminance is changed in a plurality of stages in one slot. Up to the above example, the increase / decrease of the brightness of the mobile device could be controlled only at each step preset in the mobile device. However, in reality, it is conceivable that the moving speed of a user having a mobile device is fast and the amount of space loss rapidly increases and decreases. In order to cope with this, it is necessary to increase the control width in one slot. The figure shows an example in which the pilot light source 3 is used to perform brightness control on the mobile device in two stages. The pilot light source 3 performs lighting three times in one slot. The first lighting is performed by combining the pilot light sources 1 and 2 with the luminance, and is used as a reference value for luminance control. The light emission brightness of the mobile device is adjusted by the second and third lighting. Increasing the brightness of the pilot light increases the brightness of the mobile device, and decreasing the brightness of the pilot light decreases the brightness of the mobile device.

  FIG. 13C shows an example in which the light intensity is increased by one level because the mobile device 1 has a slightly weak luminance. The mobile device 1 that has received the red light emission R1 of the pilot light sources 1 and 2 emits the response red light emission Re1 indicating the connection request with the initial luminance BT1. In response to this, the pilot light source 3 emits red light emission R3 that emits three times, but the first emission of three blinks is performed at the reference luminance B2, and 2, 3 to indicate an increase in luminance by one step. The second emission is one higher brightness B3. The mobile device 1 that has received the red light emission R3 of this one-step luminance increase instruction emits a response red light emission Re2 with a luminance BT4 that is one step higher than the initial luminance BT1. The light sources 1, 2, and 3 satisfying the luminance condition with the response red light emission Re2 emit red light emission R4 and R5 with the reference luminances B1 and B2.

  On the other hand, since the mobile device 2 has a very strong brightness, the instruction to lower the level in two steps in the first slot is the green light emission G3 brightness B5 (brightness one step lower than the reference brightness), B6 (brightness two steps lower than the reference brightness) ). Receiving this, the mobile device 2 emits light with the response green light emission Ge2 having the brightness BT2 which is two steps lower than the initial brightness BT3, and further emits light with the brightness BT5 which is two steps lower in the next response green light emission Ge2. As described above, the second-stage intensity is lowered in the second slot, and the four-stage luminance is lowered in two slots. Similarly, by increasing the number of light emission in the slot, there is an effect that brightness control can be performed in three or more steps. This effect makes it possible to follow the luminance of the mobile device against a sudden level fluctuation.

  There is a case where it is expected that the data size transmitted from the mobile device is large and that transmission takes time. At this time, if there is an empty communication path in the light receiver currently performing communication, this may be used. For example, in the case of FIG. 7, the green (shaded) timing is an empty slot. The mobile device can transmit data by optimizing the brightness after requesting connection by response green light emission. At this time, pilot search and optical axis alignment in the flowchart of FIG. Data transmission time from the mobile device can be halved. Thus, there is an effect that the data transmission speed can be improved by using a plurality of idle channels for data transmission according to the situation.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible. In the embodiment, a variation of luminance control from the illumination light side (pilot light source) to the terminal device (instruction light format instructing to change the luminance value by color change, instruction light format to change the light emission pattern such as blinking light emission in one slot, etc. Or, a lot of explanations have been made on the indication light format for instructing a luminance change in two or more steps in which light is emitted a plurality of times in one slot and the luminance value is further changed, and the control principle of such indication light is It should be noted that the present invention can also be applied to the luminance control of the illumination light communication device (pilot light source) from the terminal device side.

1 is a system configuration diagram showing a basic configuration of an illumination light communication system according to the present invention. It is a conceptual diagram which shows the whole of this system. It is an arrangement view of a mounted illumination side light receiver which is a component of the illumination light communication device. It is a control block diagram of the component of an illumination light communication apparatus. It is a timing chart which shows the data transmission / reception timing of an illumination light side light receiver, and the data transmission timing of an illumination light communication apparatus. It is a timing chart which shows the timing when placing weight on data reception. It is a timing chart which shows the timing which an illumination light communication apparatus controls the light emission luminance of each mobile device. It is a flowchart which shows the process from a pilot light search to mobile station light emission brightness adjustment. It is a flowchart which shows the brightness | luminance control processing which adjusts the brightness | luminance which a pilot light source light-emits in a pilot light emission area. It is a timing chart which shows the adjustment timing of the light emission luminance control by the side of illumination light. It is a timing chart which shows the example of control when changing the light emission period. It is a timing chart which shows the example of control by a color change. It is a timing chart which shows the example of control which changes a brightness | luminance in multiple steps by 1 slot.

Explanation of symbols

10,10A Illumination light communication device
12 LED for lighting
13 Illumination light side receiver
14 Light sensor
15 Pilot light source
16 Pilot light emitting elements
16A, 16B, 16C Pilot light source
L1, L2 Virtual straight line
SL ceiling
20 Mobile
100 Illumination light communication device
110 Lighting section
120 Pilot light emitter
130 Receiver
140 Control unit
PL pilot light source
LED-DWN LED for lighting
LED-UP LED for upstream light
200 terminal equipment
210 Light receiving means
220 Light emitting means
230 Control means
240 storage means
PD1, PD2 Photo detector
340 control unit
BLC brightness controller
CLK clock generator
ST storage
CPU processing unit
DM demodulator
LM level detector
LS light receiving sensor
MOD Modulator
R1, R2, R3, R4, R5 Red light emission
BL1, BL2, BL3, BL4, BL5 Blue light emission
G1, G2, G3, G4, G5 Green light emission
Re1, Re2, Re3, Re4 Response red light emission
BLe1, BLe2 Response blue light emission
Ge1, Ge2, Ge3 Response green light emission
W1 Light blue
Y1 yellow light emission

Claims (2)

An illuminating unit that assigns and illuminates illumination light on which information is superimposed to each of the time-divided time slots;
A pilot light emitting unit that emits pilot light indicating the timing of each of the time slots;
A light receiving unit that receives light emitted from a terminal device that is disposed around the pilot light emitting unit and receives information of the illumination light to obtain information;
An illumination light communication device comprising: In the illumination light communication apparatus according to claim 1,
There are at least two pilot light emitting units,
The at least two pilot light emitters are disposed with the light receiver interposed therebetween,
An illumination optical communication device characterized by the above.

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