JP2018157390A - Illumination communication system and illumination communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new illumination communication system capable of emitting light satisfying conditions such as brightness required for illumination light at the same time as performing data communication. An illumination communication system of the present invention includes a light source that emits light in the visible light region and a control means that controls the emission of light emitted from the light source, and the light source is an organic EL light source or an LED light source. The control means is a generation means that generates waveform information of modulated light corresponding to communication data, calculates optical information of the modulated light from the waveform information of the modulated light, and optical information of illumination light as an evaluation reference. Including a calculation means for obtaining a difference between It is characterized by. [Selection diagram] Fig. 1

Description

  The present invention relates to an illumination communication system and an illumination communication method.

  A technique for performing communication by using a light source capable of emitting light of a pulse wave and emitting modulated light whose emission intensity is modulated according to data to be transmitted is disclosed (Patent Document 1).

JP 2008-271317 A

  However, when the light source is emitted as modulated light corresponding to communication data, for example, the luminance and color temperature conditions necessary for illumination light may be insufficient.

  Therefore, an object of the present invention is to provide a new illumination communication system capable of emitting light satisfying a necessary condition as illumination light at the same time as performing data communication.

In order to achieve the above object, the lighting communication system of the present invention comprises:
A light source that emits light in the visible light range, and
Including control means for controlling emission of emitted light from the light source,
The light source is an organic EL light source or an LED light source;
The control means includes
Generating means for generating waveform information of modulated light corresponding to communication data;
Calculation means for calculating the optical information of the modulated light from the waveform information of the modulated light, and calculating a difference from the optical information of the illumination light as an evaluation reference; and
Including correction means for generating waveform information of corrected modulated light in which the difference is corrected,
The corrected modulated light is emitted from a light source based on waveform information of the corrected modulated light.

The lighting communication method of the present invention includes:
Including a control step of controlling emission of emitted light from a light source that emits light in the visible light range,
The light source is an organic EL light source or an LED light source;
The control step includes
A generation process for generating waveform information of modulated light corresponding to communication data;
A calculation step of calculating the optical information of the modulated light from the waveform information of the modulated light and obtaining a difference from the optical information of the illumination light serving as an evaluation reference,
A correction step of generating waveform information of corrected modulated light in which the difference is corrected; and
An emission step of emitting the corrected modulated light from a light source is included.

  ADVANTAGE OF THE INVENTION According to this invention, the new illumination communication system which can radiate | emit the light which satisfy | filled conditions, such as the brightness required as illumination light, for example, can be provided simultaneously with performing data communication, for example.

FIG. 1 is a block diagram illustrating an example of a lighting communication system according to the first embodiment. FIG. 2 is a block diagram illustrating a flow of communication data according to the first embodiment. FIG. 3 is a flowchart of the illumination communication method according to the first embodiment. FIG. 4 is a graph illustrating an example of correction by the correction unit according to the first embodiment. FIG. 5 is a graph illustrating an example of correction by the correction unit according to the first embodiment. FIG. 6 is a graph illustrating an example of correction by the correction unit according to the first embodiment. FIG. 7 is a circuit diagram showing an example of an organic EL light source. FIG. 8 is a graph showing an example of variation correction of an organic EL element.

  In the illumination communication system of the present invention, for example, the modulated light is modulated light obtained by modulating light of a plurality of wavelengths.

  In the illumination communication system of the present invention, for example, the illumination light is white light.

  In the illumination communication system of the present invention, for example, the light information is at least one selected from the group consisting of color temperature, luminance, light intensity of a plurality of wavelengths, and color tristimulus values.

  In the illumination communication system according to the present invention, for example, the modulation method in the modulated light is one of a pulse width modulation method and a pulse position modulation method, and the correction unit converts the pulse signal with respect to the waveform information of the modulated light. The difference is corrected by changing the amplitude.

  In the illumination communication system according to the aspect of the invention, for example, the calculation unit obtains a difference between the light information of the modulated light and the light information of the illumination light serving as an evaluation reference in a predetermined period, and the correction unit performs the correction for each predetermined period. Waveform information of the corrected modulated light is generated, and the predetermined period is a period shorter than an interval at which the human eye can time-resolve.

  In the illumination communication system according to the present invention, for example, the calculation unit obtains a difference between the optical information of the modulated light and the optical information of the illumination light serving as an evaluation reference in each pulse signal, and the correction unit Waveform information of the corrected modulated light is generated.

  In the illumination communication system of the present invention, for example, the correction unit applies correction light to the waveform information of the modulated light in at least one period before and after the period in which the modulated light corresponding to the communication data is emitted. The difference is corrected by emission.

  The illumination communication system of the present invention further includes, for example, receiving means for receiving the communication data, and the receiving means receives light emitted from the light source, which is the corrected modulated light, and the corrected modulation. Demodulating means for demodulating the communication data from optical waveform information.

  Next, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited or restricted by the following embodiments.

(Lighting communication system)
In FIG. 1, the block diagram of the illumination communication system 1 in this embodiment is shown. As shown in FIG. 1, the illumination communication system 1 of the present embodiment includes an organic EL light source 10 that emits light in the visible light region, and a control unit 20 that controls emission of the emitted light from the organic EL light source 10. The control unit 20 generates the modulated light waveform information corresponding to the communication data, calculates the modulated light optical information from the modulated light waveform information, and calculates the illumination light optical information as an evaluation reference. And a correction means 203 for generating waveform information of the corrected modulated light in which the difference is corrected. In the illumination communication system 1 of the present embodiment, the organic EL light source 10 is electrically connected to the control means 20.

  In the present invention, as the light source, for example, either an organic EL light source or an LED light source can be used, but an organic EL light source is preferable. Conventionally, in visible light communication using blinking LEDs for data transmission, white light LEDs are often used, and since it is difficult to produce extremely small elements, for example, RGB 3 In the communication apparatus using the LED of the wavelength, there is a problem that the size is increased. On the other hand, when an organic EL light source is used for the communication device, the light emitting element and the wiring can be directly formed on the transparent substrate and used as they are as the communication device, so that the device can be easily downsized. Moreover, since the organic EL light source can form a plurality of organic EL element portions on the same substrate, the degree of freedom in design is high. Therefore, by using a combination of organic EL light sources having a plurality of light wavelengths, it is possible to provide a communication device that is economical and capable of communicating a large amount of information.

  The organic EL light source 10 may be any organic EL light source that emits light in the visible light range, and a known organic EL light source can be used. The organic EL light source 10 includes, for example, a substrate and an organic EL element unit disposed on the substrate.

  In the organic EL light source 10, it is preferable that the substrate has a high transmittance that transmits light emitted from the organic EL layer in the organic EL element portion. Examples of the material for forming the substrate include non-alkali glass, soda glass, soda lime glass, borosilicate glass, aluminosilicate glass, and quartz glass; polyester such as polyethylene naphthalate and polyethylene terephthalate; polyimide; polymethacrylic acid Examples thereof include acrylic resins such as methyl, polyethyl methacrylate, polymethyl acrylate, and polyethyl acrylate; polyethersulfone; polycarbonate. The size (length and width) of the substrate 110 is not particularly limited, and may be set as appropriate according to the size of the desired organic EL light source 10, for example. The thickness of the substrate is not particularly limited, and can be appropriately set according to the forming material, use environment, and the like, and is, for example, 1 mm or less.

  The organic EL element section includes, for example, a pair of electrodes and an organic EL layer, and one electrode of the pair of electrodes, the organic EL layer, and the other electrode of the pair of electrodes. Is a laminated body laminated in this order. The pair of electrodes is, for example, a combination of an anode and a cathode, the anode is a transparent electrode such as indium tin oxide (ITO), and the cathode is, for example, a metal (such as aluminum). Counter electrode. The organic EL layer has, for example, a stacked structure in which a hole injection layer, a hole transport layer, a light emitting layer including an organic EL, an electron transport layer, and an electron injection layer are sequentially stacked. One or more (two or more) organic EL element units may be arranged on one surface of the substrate.

The light emitting layer is a layer that recombines electrons and holes injected from the electrode to emit fluorescence, phosphorescence, and the like. The light emitting layer includes a light emitting material. Examples of the light-emitting material include tris (8-quinolinol) aluminum complex (Alq ₃ ), bisdiphenylvinylbiphenyl (BDPVBi), 1,3-bis (pt-butylphenyl-1,3,4-oxadiazole) Yl) phenyl (OXD-7), N, N′-bis (2,5-di-t-butylphenyl) perylenetetracarboxylic acid diimide (BPPC), 1,4 bis (Np-tolyl-N-4) Examples thereof include low molecular compounds such as-(4-methylstyryl) phenylamino) naphthalene, and high molecular compounds such as polyphenylene vinylene-based polymers.

In addition, the light emitting material may be, for example, a material composed of a two-component system of a host and a dopant, in which excited state energy generated by the host molecule moves to the dopant molecule and the dopant molecule emits light. Specifically, such a light-emitting material is prepared by, for example, adding a quinolinol metal complex such as a host Alq ₃ to a dopant 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran ( DCM), quinacridone derivatives such as 2,3-quinacridone, or those doped with a coumarin derivative such as 3- (2′-benzothiazole) -7-diethylaminocoumarin, bis (2- Methyl-8-hydroxyquinoline) -4-phenylphenol-aluminum complex doped with a condensed polycyclic aromatic compound such as perylene as a dopant, or 4,4′-bis ( m-Tolylphenylamino) biphenyl (TPD) doped with dopant rubrene, etc., host 4,4 ′ A carbazole compound such as biscarbazolylbiphenyl (CBP), 4,4′-bis (9-carbazolyl) -2,2′-dimethylbiphenyl (CDBP), a dopant platinum complex, tris- (2 ferrinylpyridine) ) Iridium complex (Ir (ppy) ₃ ), (bis (4,6-di-fluorophenyl) -pyridinate-N, C2 ′) picolinate iridium complex (FIr (pic)), (bis (2- (2 ′ -Iridium complexes such as benzo (4,5-α) thienyl) pyridinate-N, C2 ′) (acetylacetonate) iridium complex (Btp ₂ Ir (acac)), Ir (pic) ₃ , Bt ₂ Ir (acac) And the like doped with.

The above-mentioned luminescent material can be appropriately selected according to, for example, the target luminescent color of the illumination communication system 1. Specifically, for example, in the case of green light emission, Alq ₃ , quinacdrine, coumarin, Ir (ppy) ₃ etc. as the dopant, in the case of blue light emission, DPVBi, the dopant as perylene, distyrylarylene derivative, FIr (pic) etc. In the case of green to blue-green light emission, OXD-7 or the like, in the case of red to orange light emission, DCM, DCJTB, Ir (pic) ₃ or the like as a dopant, in the case of yellow light emission, rubrene, Bt ₂ Ir (acac) or the like Can be selected. In order to obtain white light emission, for example, a combination of Alq ₃ as a host and DCM (orange) as a guest can be selected as the light emitting material.

  For example, the organic EL light source 10 may be a combination of a plurality of the organic EL element units that emit light of different colors. Specifically, for example, white light can be obtained by arranging the organic EL element portions that emit red, green, and blue (RGB) in a tile shape on the surface of the substrate and combining the light of each color. it can. In addition, white light can be obtained by combining light emitting complementary colors such as blue and yellow.

  In addition, for example, a layer having a three-layer structure that contains light-emitting materials that emit red, green, and blue, a layer that has a two-layer structure that emits blue, yellow, and the like, and these light-emitting materials by multiple co-evaporation The organic EL element part which emits white can be obtained by forming, as the light emitting layer, a layer having a single layer structure in which is mixed. Further, the light emitting material constituting each color layer in the above-described three-layer laminated layer or two-layer laminated layer is formed, for example, by sequentially arranging fine pixels such as red, blue, and green in a planar manner. The layer may be the light emitting layer that emits white light.

  As described above, the control unit 20 includes the generation unit 201, the calculation unit 202, and the correction unit 203. The control unit 20 is, for example, a device (terminal) that integrally includes the generation unit 201, the calculation unit 202, and the correction unit 203, and may be a system. The generation unit 201, the calculation unit 202, and the correction unit 203 may be incorporated in, for example, data processing unit (data processing apparatus) that is hardware, or may be software or hardware in which the software is incorporated. The data processing means may include a central processing unit (CPU), a microprocessor, a microcontroller, and the like. In the illumination communication system 1 of the present embodiment, the generation unit 201 is electrically connected to the calculation unit 202, and the calculation unit 202 is electrically connected to the correction unit 203. In the illumination communication system 1 of the present embodiment, for the control unit 20, for example, any one or more units may be separated.

  The generation unit 201 generates waveform information of modulated light corresponding to communication data. The waveform information is, for example, information on the waveform of the modulated light and information on a current value for outputting the corrected modulated light so as to have the waveform. Examples of a method for modulating the communication data in the generation unit 201 include a pulse width modulation (PWM) method and a pulse position modulation (PPM) method. A specific method for modulating the communication data will be described later.

  For example, the generation unit 201 may generate waveform information of modulated light corresponding to communication data for light of one color, or generate waveform information of modulated light corresponding to communication data for light of a plurality of types of colors. May be. In the latter case, the generation unit 201 may assign a plurality of different communication data to the light of each color, or may separate one communication data and assign it to the light of each color.

  When the generation unit 201 separates one communication data, assigns it to the light of each color, and generates the waveform information of the modulated light corresponding to the communication data for the light of each color, the illumination communication system 1 of the present embodiment For example, a separation unit may be included, and the separation unit may allocate one piece of communication data to the light of each color. The separating means and the multiplexing means described later are, for example, a central processing unit (CPU), a microprocessor, a microcontroller, and the like. Then, the generation unit 201 generates the waveform information of the modulated light corresponding to the communication data assigned by the separation unit for the light of each color.

  FIG. 2 is a block diagram showing the flow of communication data when the light corresponding to the communication data is three types of RGB light. As shown in FIG. 2, in the separation means (separation circuit), communication data (transmission data) is divided into three, and each communication data is converted into three types of RGB light emitted from the organic EL light source 10. Assigned. Then, the control means 20 (drive circuit) generates waveform information of corrected modulated light corresponding to the assigned communication data. Then, the corrected modulated light is emitted from the organic EL light source 10, respectively. As will be described later, the receiving means 30 (light receiving circuit) receives the corrected modulated light corresponding to the communication data by a photo detector (PD) having a color filter (CF), and performs the three types of correction of RGB. The communication data is demodulated from the modulated light. The communication data divided into three is returned to one communication data (received data) in a multiplexing means (multiplexing circuit).

  The calculating means 202 calculates the light information of the modulated light from the waveform information of the modulated light generated by the generating means 201, and further, the light information of the modulated light and the light information of the illumination light serving as an evaluation reference Find the difference between

  The optical information is, for example, color temperature (K), luminance, light intensity of multiple wavelengths, and color tristimulus values. The color temperature can be rephrased as, for example, chromaticity, and the luminance can be rephrased as, for example, a luminous flux, brightness, and light intensity.

The illumination light is, for example, white light, specifically, daylight color (about 6500K), daylight white color (about 5000K), light bulb color (about 3000K), white color (about 4200K), and warm white color (about 3500K). Can be given. Moreover, when the illumination communication system 1 is used for design illumination or automobile illumination, the illumination light may be light other than white light, for example. The brightness of the illumination light is, for example, 100 to 10000 cd / m ² .

  For example, when the modulated light is a combination of a plurality of types of light, the calculation unit 202 includes light information of the light obtained by adding the plurality of types of light and illumination light serving as the evaluation criterion. The difference between the light information of each of the plurality of types of light and the difference between the light information when the illumination light serving as the evaluation reference is divided into a plurality of lights may be obtained. You may ask for.

  The correction unit 203 generates waveform information of the corrected modulated light in which the difference is corrected based on the difference between the light information of the modulated light and the light information of the illumination light serving as an evaluation reference, which is obtained by the calculation unit 202. To do.

  By the correction, for example, the corrected modulated light can be light having no difference or small difference in optical information in comparison with illumination light serving as an evaluation reference. That is, the corrected modulated light is light that satisfies the conditions necessary for illumination light.

Generally, since the time resolution of the human eye is about 50 ms to 100 ms, when light blinks at an interval shorter than the resolvable time interval, a person recognizes that the light is continuously lit. In addition, when lights having different wavelengths are lit at intervals shorter than the resolvable time interval, a person recognizes the light as one type of light synthesized from the different wavelengths. Accordingly, it is preferable that the correcting unit 203 sets a period shorter than the interval in which the human eye can be time-resolved as a predetermined period, and corrects the difference in that period in the predetermined period. Thereby, the person can recognize the said correction | amendment modulated light as an illumination light without a sense of incongruity. In addition, for example, even when light combining a plurality of colors of light is used, it is possible to suppress variations in the color of the corrected modulated light by correcting the difference in the light information of each color during the predetermined period. The predetermined period (one correction period) is, for example, 5 × 10 ^{−9 to} 100 ms, 1 × 10 ^{−8 to} 50 ms, or 2 × 10 ^{−8 to} 16.7 ms.

  For example, when the modulated light is a combination of a plurality of types of light, the correction unit 203 preferably corrects the light of each color. When the correction unit 203 corrects the light of the plurality of types of colors, for example, by changing the luminance of the modulated light of each color, for example, the difference in color temperature of the light obtained by adding the light of the plurality of types of color Can be corrected. Further, for example, by uniformly changing the luminance of the modulated light of each color, it is possible to correct the difference in luminance of the light obtained by adding the light of the plurality of colors.

  For example, the correction unit 203 may refer to information stored in a storage unit described later. A specific correction method will be described later.

  The illumination communication system 1 of the present embodiment may further include, for example, a storage unit that stores the light information of the illumination light serving as the evaluation criterion. The storage means is, for example, a database, a server, a random access memory (RAM), a read only memory (ROM), or the like.

  For example, the storage unit may store the optical information corresponding to the current value as a reference table. In this case, the control means 20 can control the emission of emitted light from the light source based on the reference table stored in the storage means.

  The illumination communication system 1 of the present embodiment may further include, for example, a receiving unit 30 that receives communication data. The receiving unit 30 includes, for example, a light receiving unit 301 that receives outgoing light from the light source that is the corrected modulated light, and a demodulating unit 302 that demodulates the communication data from waveform information of the corrected modulated light.

  The receiving unit 30 is, for example, a device (terminal) that integrally includes the light receiving unit 301 and the demodulating unit 302, and may be a system. In the illumination communication system 1 of the present embodiment, the light receiving unit 301 is electrically connected to the demodulating unit 302. In the illumination communication system 1 of the present embodiment, for example, the receiving unit 30 may be separated from each other.

  The light receiving means 301 only needs to be able to receive the corrected modulated light emitted from the organic EL light source 10, and for example, a color having a color filter in front of PIN-photodiodes, PIN-photodiodes and avalanche photodiodes having different light-receiving wavelengths. Examples include sensors, image sensors such as CMOS monolithic photo ICs and CCDs, and photo detectors such as photo registers. When the light emitted from the organic EL light source 10 is a combination of a plurality of types of light, the light receiving unit 301 may be, for example, a photodetector having a color filter for dispersing each light, or a color sensor. May be used. For example, the light receiving unit 301 receives the corrected modulated light as light in a wavelength range (color) determined by a color filter, and converts the light into an electrical signal for each color.

  The demodulating means 302 demodulates the communication data from the waveform information of the corrected modulated light corresponding to the communication data received by the light receiving means 301. Specifically, the demodulation unit 302 demodulates the original communication data from the electrical signal for each color converted by the light receiving unit 301. The method of demodulating the communication data in the demodulating unit 302 is a method corresponding to the method of modulating the communication data in the generating unit 201, for example. The demodulating means 302 is, for example, a central processing unit (CPU), a microprocessor, a microcontroller, or the like.

  The illumination communication system 1 of the present embodiment can receive communication data from the corrected modulated light emitted from the organic EL light source 10 by including the receiving unit 30 that receives communication data. In the lighting communication system 1 of the present embodiment, the receiving unit 30 is not an essential component, and the receiving unit 30 may or may not be included in the lighting communication system 1.

  In the illumination communication system 1 of the present embodiment, for example, the organic EL light source 10 can be used only as an illumination device in a period in which data communication is not performed. For example, when the lighting communication system 1 transmits data, the communication data to be transmitted is supplied to the control unit 20, so that the control unit 20 emits light from the organic EL light source 10 based on the communication data. To control the emission of. Thereby, the corrected modulated light corresponding to the communication data is emitted from the organic EL light source 10.

(Lighting communication method)
In FIG. 3, the flowchart of the illumination communication method in this embodiment is shown. The illumination communication method of this embodiment is implemented as follows, for example. As shown in FIG. 3, the control process in the illumination communication method of the present embodiment includes an S1 step (generation process), an S2 step (calculation process), an S3 step (correction process), and an S4 step (exit process). The illumination communication method of this embodiment can be implemented using the illumination communication system 1 of this embodiment, for example. The description of the illumination communication system 1 of this embodiment can be used for the illumination communication method of this embodiment, for example.

  In the generation step S1, communication data is modulated, and waveform information of modulated light corresponding to the communication data is generated. As described above, examples of a method for modulating the communication data include a pulse width modulation (PWM) method and a pulse position modulation (PPM) method. The pulse width modulation method is a modulation method in which the communication data signal is modulated into the waveform information of the modulated light by making the period for generating the pulse signal constant and making the pulse width correspond to the communication data signal. Also, the pulse position modulation method modulates the communication data signal into the waveform information of the modulated light by making the pulse width constant and associating the temporal position of the pulse signal in a constant period with the communication data signal. It is a method.

  Examples of the pulse position modulation method include a quaternary pulse position modulation (4PPM) method and an inversion pulse position modulation (I-4PPM) method. In the 4PPM system, a certain time is defined as one symbol time, which is divided equally into four slots, and a pulse signal is generated in one slot per symbol time. Then, the communication data information is converted into information indicating in which slot a pulse signal exists in one symbol. The pulse signal may be one pulse signal having one slot width, or a plurality of pulses may be generated in one slot. In the latter case, for example, allocated 2-bit information can be transmitted per slot. In the 4PPM modulation method, the communication data is modulated, so that only one slot is lit and a signal is transmitted only at the pulse position, so the error rate is small. In addition, since the amplitude of the pulse signal is constant and the light is turned on once during a certain period, even in the case of modulated light combining multiple wavelengths of light, the brightness in each color is constant, so correction of the color temperature Can be done easily. On the other hand, in the I-4PPM system, the position where there is a pulse and the position where there is no pulse in the 4PPM system are interchanged to increase the lighting time. In the 4PPM system, the luminance is about ¼ compared to that in the case of no modulation, whereas in the I-4PPM system, the luminance can be set to about ¾ compared with that in the case of no modulation. For this reason, the I-4PPM system can perform communication with brighter brightness when the amplitudes of the pulse signals are equal.

  In the calculation step S2, the optical information of the modulated light is calculated from the waveform information of the modulated light. Further, a difference between the optical information of the modulated light and the optical information of the illumination light that is an evaluation reference is obtained. The calculation of the light information of the modulated light is performed by, for example, calculating light information obtained at a predetermined current value in advance from the emission spectrum of each light source with respect to the current value, and storing the correspondence relationship. Based on the correspondence relationship, the optical information of the modulated light can be obtained from the waveform information of the modulated light.

  In the correction step S3, waveform information of corrected modulated light in which the difference is corrected is generated based on the difference. An example of correction in the correction step S3 will be described below with reference to the drawings. In the following description, an example in which correction is performed for light of one color is shown. However, the present invention is not limited to this, and correction can be similarly performed for light of a plurality of types of colors.

  An example of the correction of the difference in the correction step S3 is shown in FIG. 4 when the modulated light is modulated light by a pulse width modulation method. In FIG. 4, (A) shows the waveform of the modulated light by the pulse width modulation method, and (B) and (C) show the waveform of the corrected modulated light in which the luminance of the modulated light is corrected. 4A to 4C, the horizontal axis indicates time, and the vertical axis indicates the amplitude of the pulse signal. In FIG. 4, the integrated value of the pulse signal at a predetermined time corresponds to the luminance of the modulated light at the predetermined time. As shown in FIG. 4A, in the modulated light modulated by the pulse width modulation method, the communication data signal corresponds to the pulse width in each pulse signal. In the modulated light, the period and amplitude of the pulse signal are constant. In the correction step S3, for example, the luminance of the modulated light can be changed by changing the amplitude of the pulse signal. Specifically, as shown in FIG. 4B, in the correction step S3, for example, the luminance of the modulated light in a predetermined period (one correction period) is compared with the luminance of illumination light serving as an evaluation reference. If it is insufficient, the luminance of the modulated light can be increased by increasing the amplitude of the pulse signal in a predetermined period by a predetermined value. Further, in the correction step S3, for example, when the luminance of the modulated light in a predetermined period is excessive as compared with the luminance of the illumination light serving as an evaluation reference, the amplitude of the pulse signal in the predetermined period is decreased by a predetermined value. As a result, the brightness of the modulated light can be reduced. In FIG. 4B, the amplitude of each pulse signal is changed by the same value, but the amplitude of each pulse signal may be changed by a different value. In this case, for example, the amplitude of each pulse signal can be changed so that the luminance obtained from each pulse signal is constant. On the other hand, as shown in FIG. 4C, in the correction step S3, for example, for each pulse signal, the brightness of the modulated light is compared with the brightness of the illumination light serving as the evaluation reference, and the brightness of the modulated light is insufficient. In the case where the amplitude of each pulse signal is increased by a predetermined value, the brightness of the modulated light is increased. When the brightness of the modulated light is excessive, the amplitude of each pulse signal is set to a predetermined value. By reducing the value, the brightness of the modulated light can be reduced.

  As described above, when correcting the modulated light by the pulse width modulation method, it is only necessary to change the amplitude of the pulse signal in the modulated light based on the difference. For example, correction calculation can be simplified. Further, for example, since the ratio of the light emission period (pulse width) in each cycle is relatively large as compared with the 4PPM method, when the luminance of the modulated light is increased, the luminance of the modulated light is controlled by the amplitude of the pulse signal. The load on the organic EL light source can be suppressed and the life of the organic EL light source can be extended.

  Next, another example of the correction of the difference in the correction step S3 is shown in FIG. 5 in the case where the modulated light is modulated light by a pulse position modulation method. In FIG. 5, (A) shows the waveform of the modulated light by the pulse position modulation (4PPM) system, and (B) shows the waveform of the corrected modulated light in which the luminance of the modulated light is corrected. 5A and 5B, the horizontal axis indicates time, and the vertical axis indicates the amplitude of the pulse signal. In FIG. 5, the integrated value of the pulse signal at a predetermined time corresponds to the luminance of the modulated light at the predetermined time. As shown in FIG. 5A, in the modulated light modulated by the pulse position modulation method, the communication data signal corresponds to the temporal position of the pulse signal in a fixed period. In the modulated light, the pulse width and amplitude of the pulse signal are constant. In the correction step S3, for example, the luminance of the modulated light can be changed by changing the amplitude of the pulse signal. Specifically, as shown in FIG. 5B, in the correction step S3, for example, when the luminance of the modulated light is insufficient compared to the luminance of the illumination light serving as the evaluation reference, By increasing the amplitude by a predetermined value, the luminance of the modulated light can be increased. Further, in the correction step S3, for example, when the luminance of the modulated light is excessive as compared with the luminance of the illumination light serving as the evaluation reference, the amplitude of the pulse signal is reduced by a predetermined value, thereby reducing the modulated light. The luminance can be reduced.

  As described above, when correcting the modulated light by the pulse position modulation method, the amplitude and pulse width of the pulse signal are constant, and the number of pulses in a certain period (one symbol period) is also constant. And the amount of correction data can be reduced.

  FIG. 6 shows still another example of the difference correction in the correction step S3 in the case where the modulated light is modulated light by a pulse width modulation method and a pulse position modulation method. 6A shows a waveform of corrected modulated light in which the luminance of the modulated light is corrected for the modulated light by the pulse width modulation method. (B) shows the waveform of the corrected modulated light in which the luminance of the modulated light is corrected for the modulated light by the pulse position modulation (4PPM) method. In FIG. 6, the horizontal axis represents time, and the vertical axis represents the amplitude of the pulse signal. In FIG. 6, the integrated value of the pulse signal at a predetermined time corresponds to the luminance of the modulated light at the predetermined time. As shown in FIG. 6, in the correction step S3, for example, the correction light is supplied in at least one period (correction period) before and after the period (signal transmission period) in which the modulated light corresponding to the communication data is emitted. The difference can be corrected by emitting light. Specifically, in the correction step S3, for example, the difference between the luminance of the modulated light calculated in the calculation step S2 and the luminance of the illumination light serving as an evaluation reference is assigned to the correction period, thereby correcting the modulated light. Is corrected so that the integrated value of the pulse signal at a predetermined time becomes the value of the illumination light serving as the evaluation reference. Here, the amplitude of the signal used for correction is, for example, the same as the amplitude of the communication data signal. In this case, for example, the correction can be performed by making the difference correspond to the pulse width of the pulse signal in the correction period. The signal used for the correction may be a plurality of pulse signals or a single signal during the correction period.

  In the correction step S3, when the correction light is emitted in at least one of the correction periods before and after the signal transmission period, the ratio between the signal transmission period and the correction period is not particularly limited. The ratio of the signal transmission period is 0 (when communication is not performed) to 99%, 0 to 80%, and 0 to 50%.

  Thus, when the modulated light is corrected by including a correction period before and after the period for transmitting the communication data signal, the amplitude of the signal used for correction and the communication data signal can be made constant. The light emission luminance of the EL light source can be made constant. As a result, the organic EL light source can be prevented from instantaneously having a significantly high brightness, so that the life of the organic EL light source can be extended. Further, since the signal used for correction and the amplitude of the communication data signal can be made constant, it is not necessary to adjust the slice level and sensitivity of the photodiode on the signal receiving side. Further, since the communication data signal is assigned to the signal transmission period and the correction signal is assigned to the correction period, it is not necessary to distribute the correction information to each communication data signal, so that the correction data amount can be reduced. The correction calculation can be simplified.

  The correction of the difference in the correction step S3 has been described above with an example. However, in the correction step S3, for example, two or more methods among the correction methods may be combined.

  Next, an example of the illumination communication method of the present embodiment will be specifically described in the case where the organic EL light source is a light source that combines light of a plurality of colors, and the optical information is a tristimulus value of light. .

First, from the emission spectrum for the current value of each light emitted from the organic EL light source, the light tristimulus value (XYZ) at a predetermined current value and the light tristimulus value of each light are added. The tristimulus value of light obtained during additive color mixing is obtained. Then, correspondence information regarding these current values, tristimulus values of each light, and tristimulus values of light at the time of additive color mixture is assigned to a reference table (LUT). For example, when referring to an 8-bit reference table for each color of RGB, it is possible to perform about 16.77 million types of control with 256 gradations for each color. The number of color data (number of bits) may be reduced using FRC (frame rate control). The tristimulus value (XYZ) of light can be obtained by the following formula (1). In Expression (1), P (λ) is a spectral spectrum, Q (λ) is an emission spectrum, and x (λ), y (λ), and z (λ) are color matching functions.

  Moreover, the value of the optical information used as an evaluation reference when using the organic EL light source as illumination light is acquired in advance. For example, the tristimulus value of light and the current value corresponding to this when the organic EL light source emits light that satisfies the daylight white color of 5000K and the rated luminous flux are obtained.

  Then, in the generation step S1, modulated light corresponding to the communication data is generated, and in the calculation step S2, a tristimulus value of light is obtained for the modulated light, and this value is used as an evaluation criterion acquired in advance. The difference from the tristimulus value of light is obtained.

  In the correction step S3, based on the difference, the reference table is referenced to calculate the corrected light tristimulus values for each light. Based on the tristimulus values of the corrected light, the waveform information of the corrected modulated light is calculated for each light, and the current value is output.

  Here, in the correction, as described above, when the amplitude (emission intensity) of the pulse signal in the modulated light is changed, the correction is performed by changing the amplitude of the pulse signal, and the pulse signal in the modulated light is changed. When the amplitude is constant, correction is performed by changing the light emission time. The correction may be performed by changing both the emission intensity and the emission time of the modulated light.

The light tristimulus values XYZ are normalized and converted,
x = X / (X + Y + Z) y = Y / (X + Y + Z) z = 1−xy
The same correction can be performed by using the value of xyY together with Y of the luminance (light flux) information. In this case, by using the xy chromaticity diagram, it becomes easy to confirm the relationship between the xy chromaticity coordinates of the illumination light (for example, daylight white (0.3457, 0.3585) and daylight color (0.3127, 0.3290)).

  By calculating and storing the tristimulus values XYZ of colors and the tristimulus values at the time of additive color mixture obtained by adding them from each emission spectrum with respect to the current value, it is possible to perform complex arithmetic processing by simple array reference processing. It is possible to improve the processing efficiency. In this way, the control means 20 can reduce the calculation burden and perform processing efficiently by extracting the target data from the array instead of performing the calculation each time.

  Further, as a method of calculating the waveform information of the corrected modulated light, the pulse signal of each light source that directly corresponds to the difference based on the difference in luminance and chromaticity coordinates of each light source in the modulated light and illumination light The amplitude (light emission intensity) and the light emission time may be calculated.

  The calculation is performed as follows. First, a relational expression between the current value of each light source and chromaticity coordinates is acquired. Next, the chromaticity coordinates and luminance of the modulated light are obtained, and the difference between the chromaticity coordinates and luminance of the modulated light and the chromaticity coordinates and luminance of illumination light is obtained. From the difference, the amplitude and / or light emission time of the pulse signal of each light source corresponding to the difference is calculated. This is added to the amplitude and / or emission time of the pulse signal of the modulated light. Then, a current value is calculated based on the relational expression. In this way, the waveform information of the corrected modulated light can be generated.

  In the emission step S4, the corrected modulated light is emitted from the light source based on the waveform information of the corrected modulated light whose difference has been corrected in the correction step S3. The light source is, for example, an organic EL light source.

  Thus, according to the illumination communication method of the present embodiment, the control process includes an S1 step (generation process), an S2 step (calculation process), an S3 step (correction process), and an S4 step (exit process). As a result, the corrected modulated light that satisfies the conditions of light information necessary as illumination light can be emitted.

  The illumination communication method of the present embodiment may include, for example, an S5 step (receiving step) for receiving communication data, and the receiving step S5 receives, for example, emitted light from the light source that is the corrected modulated light. A light receiving step and a demodulating step of demodulating the communication data from the waveform information of the corrected modulated light may be included. Thereby, the communication data included in the corrected modulated light emitted from the light source can be acquired. In the illumination communication method of the present embodiment, the reception step S5 is not an essential component, and the reception step S5 may or may not be included in the illumination communication method of the present embodiment.

(Organic EL light source)
FIG. 7 shows a circuit diagram per basic light emitting unit as an example of the organic EL light source. One light emitting unit is provided with two TFTs (thin film transistors) and one storage capacitor (storage capacitor, capacitor). One of the two TFTs is a selection TFT for selecting the light emitting unit, and the other is a driving TFT for flowing a current necessary for light emission of the organic EL.

  In FIG. 7, when a selection voltage is applied to the address line (selection line), the selection TFT is turned on, and a voltage corresponding to the data of the lighting signal is applied to the gate electrode of the driving TFT through the data line (signal line). The At the same time, the storage capacitor is applied and charged, that is, data is written. Thereby, even when the selection signal is turned OFF, the gate voltage of the driving TFT is maintained by the voltage written in the storage capacitor. When the set current of the organic EL corresponding to the voltage of the storage capacitor is supplied from the power supply line to the organic EL element, the organic EL element emits light. Since this state can be maintained until the next writing is performed, the organic EL element can maintain a constant luminance during that time.

  As described above, when the light emission intensity of the organic EL is controlled by the driving TFT, variations in characteristics such as the threshold voltage and mobility of the TFT cause variations in the light emission luminance, and thus compensation (correction) is required. . The compensation can be performed by a known method such as adding a correction TFT or capacitor, forming a current mirror circuit, or programming a current or voltage.

  FIG. 8 shows an example in which an organic EL element is driven by a configuration including two TFTs and one storage capacitor as a circuit configuration for compensating for the above-described variation. Since this method compensates by pulsing the power supply voltage and applying a signal voltage and a reference voltage to the data line, it is suitable for, for example, visible light communication in which data is transmitted by a light emission pulse signal of an organic EL light source. Is the method. 7 and 8, Vadress is an address line potential and indicates a gate line potential (pixel selection signal) of a selection TFT. Vcc is a power supply line potential (power supply voltage) for causing the organic EL to emit light, and the threshold voltage of the driving TFT is also corrected by changing the voltage. Vcath represents the cathode voltage of the organic EL, Vref represents the reference voltage used for threshold correction, Vsig represents the data voltage of the signal to be displayed, and Vth represents the threshold voltage of the driving TFT. In the previous stage of correcting the threshold value, by setting Vcc to the low potential, the source potential of the driving TFT and the anode of the organic EL become the same potential as Vcc, and at the same time, the potential of the gate and the storage capacitor of the driving TFT And the light emission stops. In a state where Vref is applied to the data line (signal line), the selection signal Vadress (address line) is turned ON, and Vref is written in the gate of the driving TFT and the potential of the storage capacitor. At this time, the gate-source voltage Vgs of the driving TFT is Vgs = Vref−Vcc> Vth. In the threshold correction process, by raising the power supply line from the low potential to Vcc, a current flows between the drain and source of the driving TFT, and the source potential of the driving TFT increases. The source potential of the driving TFT and the anode of the organic EL rise to the voltage (Vref−Vcc = Vth) at which the gate-source voltage (Vgs) of the driving TFT becomes the threshold (Vth), and the threshold is corrected. Is done.

  Next, data signal writing and mobility correction are performed. In this step, the potential of the gate and the storage capacitor of the driving TFT becomes a desired data voltage, and at the same time, the mobility is corrected according to the capability of the driving TFT. Specifically, during the period when the voltage of the data line (signal line) is Vsig, the gate voltage of the selection TFT is raised from Voff to Von by the selection signal Vadress (address line), and the gate of the driving TFT is used as the data line. Connecting. The gate voltage of the driving TFT becomes Vsig. At this time, the voltage of the anode of the organic EL element is lower than the threshold voltage Vthel of the organic EL element, and the organic EL element is in a non-lighting state. Therefore, the current between the drain and source of the driving TFT flows into the capacitance component (parallel plate capacitor) of the organic EL element, and the element capacitance is charged, so that the source voltage Vs of the driving TFT increases by ΔV, and thereafter The gate-source voltage Vgs of the driving TFT becomes Vsig + Vth−ΔV. In this way, mobility is corrected simultaneously with writing. Here, since ΔV increases as the mobility of the driving TFT increases, the variation in mobility of the driving TFT arranged for each organic EL element is corrected by reducing the potential difference Vgs by ΔV before light emission. can do.

  Next, the gate voltage of the selection signal Vadress (address line) is lowered from Von to Voff. As a result, the gate of the driving TFT floats, current flows between the drain and source of the driving TFT, the source voltage Vs rises, and the organic EL element emits light with the threshold value and mobility compensated. can do. Thereby, in the emission process, the organic EL emits light with the threshold value and mobility compensated.

  The present invention has been described above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the new illumination communication system which can radiate | emit the light which satisfy | filled conditions, such as brightness required as illumination light, can be provided simultaneously with performing data communication.

  A part or all of the above embodiment can be described as in the following supplementary notes, but is not limited to the following.

(Appendix 1)
A light source that emits light in the visible light range, and
Including control means for controlling emission of emitted light from the light source,
The light source is an organic EL light source or an LED light source;
The control means includes
Generating means for generating waveform information of modulated light corresponding to communication data;
Calculation means for calculating the optical information of the modulated light from the waveform information of the modulated light, and calculating a difference from the optical information of the illumination light as an evaluation reference; and
Including correction means for generating waveform information of corrected modulated light in which the difference is corrected,
An illumination communication system, wherein the corrected modulated light is emitted from a light source based on waveform information of the corrected modulated light.

(Appendix 2)
The calculation means obtains a difference between the light information of the modulated light and the light information of the illumination light serving as an evaluation reference in a predetermined period,
The correction means generates waveform information of corrected modulated light every predetermined period,
The lighting communication system according to appendix 1, wherein the predetermined period is a period shorter than an interval in which human eyes can perform time resolution.

(Appendix 3)
The illumination communication system according to appendix 2, wherein the correction means changes the amplitude of the pulse signal so that the luminance obtained from each pulse signal corresponding to the communication data is constant.

(Appendix 4)
Including a control step of controlling emission of emitted light from a light source that emits light in the visible light range,
The light source is an organic EL light source or an LED light source;
The control step includes
A generation process for generating waveform information of modulated light corresponding to communication data;
A calculation step of calculating the optical information of the modulated light from the waveform information of the modulated light and obtaining a difference from the optical information of the illumination light serving as an evaluation reference,
A correction step of generating waveform information of corrected modulated light in which the difference is corrected; and
An illumination communication method comprising an emission step of emitting the corrected modulated light from a light source.

(Appendix 5)
The illumination communication method according to appendix 4, wherein the modulated light is modulated light obtained by modulating light of a plurality of wavelengths.

(Appendix 6)
The illumination communication method according to appendix 4 or 5, wherein the illumination light is white light.

(Appendix 7)
The illumination communication method according to any one of appendices 4 to 6, wherein the optical information is at least one selected from the group consisting of color temperature, luminance, light intensity of a plurality of wavelengths, and color tristimulus values.

(Appendix 8)
The modulation method in the modulated light is a pulse width modulation method or a pulse position modulation method,
8. The illumination communication method according to any one of appendices 4 to 7, wherein the correction step corrects the difference by changing an amplitude of a pulse width signal with respect to the waveform information of the modulated light.

(Appendix 9)
In the calculation step, the difference between the light information of the modulated light and the light information of the illumination light as an evaluation reference in a predetermined period is obtained,
In the correction step, waveform information of the corrected modulated light is generated every predetermined period,
The lighting communication method according to any one of appendices 4 to 8, wherein the predetermined period is a period shorter than an interval in which human eyes can perform time resolution.

(Appendix 10)
The illumination communication method according to appendix 9, wherein in the correction step, the amplitude of the pulse signal is changed so that the luminance obtained from each pulse signal corresponding to the communication data is constant.

(Appendix 11)
In the calculation step, the difference between the light information of the modulated light in each pulse signal and the light information of the illumination light as an evaluation reference is obtained,
The illumination communication method according to any one of appendices 4 to 8, wherein in the correction step, waveform information of the corrected modulated light is generated for each pulse signal.

(Appendix 12)
In the correction step, with respect to the waveform information of the modulated light, the difference is corrected by emitting correction light in at least one period before and after the period of emitting modulated light corresponding to the communication data. The lighting communication method according to any one of appendices 4 to 11.

(Appendix 13)
And further including a receiving step of receiving the communication data,
The receiving step includes
The illumination communication according to any one of appendixes 4 to 12, further comprising: a light receiving step for receiving light emitted from the light source that is the corrected modulated light; and a demodulating unit that demodulates the communication data from waveform information of the corrected modulated light. Method.

DESCRIPTION OF SYMBOLS 1 Illumination communication system 10 Organic EL light source 20 Control means 201 Generation means 202 Calculation means 203 Correction means 30 Reception means 301 Light reception means 301 Demodulation means

Claims (10)

A light source that emits light in the visible light range, and
Including control means for controlling emission of emitted light from the light source,
The light source is an organic EL light source or an LED light source;
The control means includes
Generating means for generating waveform information of modulated light corresponding to communication data;
Calculation means for calculating the optical information of the modulated light from the waveform information of the modulated light, and calculating a difference from the optical information of the illumination light as an evaluation reference; and
Including correction means for generating waveform information of corrected modulated light in which the difference is corrected,
An illumination communication system, wherein the corrected modulated light is emitted from a light source based on waveform information of the corrected modulated light. The illumination communication system according to claim 1, wherein the modulated light is modulated light obtained by modulating light of a plurality of wavelengths. The illumination communication system according to claim 1, wherein the illumination light is white light. The illumination communication according to any one of claims 1 to 3, wherein the optical information is at least one selected from the group consisting of color temperature, luminance, light intensity of a plurality of wavelengths, and color tristimulus values. system. The modulation method in the modulated light is one of a pulse width modulation method and a pulse position modulation method,
The illumination communication system according to any one of claims 1 to 4, wherein the correction unit corrects the difference by changing an amplitude of a pulse signal with respect to the waveform information of the modulated light. The calculation means obtains a difference between the light information of the modulated light and the light information of the illumination light serving as an evaluation reference in a predetermined period,
The correction means generates waveform information of corrected modulated light every predetermined period,
The lighting communication system according to any one of claims 1 to 5, wherein the predetermined period is a period shorter than an interval in which human eyes can perform time resolution. The calculation means obtains a difference between the light information of the modulated light in each pulse signal and the light information of the illumination light serving as an evaluation reference,
The illumination communication system according to any one of claims 1 to 5, wherein the correction unit generates waveform information of corrected modulated light for each pulse signal. The correction means corrects the difference in the waveform information of the modulated light by emitting correction light in at least one period before and after the period of emitting modulated light corresponding to the communication data. The lighting communication system according to any one of claims 1 to 7. And further comprising receiving means for receiving the communication data,
The receiving means includes
9. The light receiving device according to claim 1, further comprising: a light receiving unit configured to receive light emitted from the light source that is the corrected modulated light; and a demodulating unit configured to demodulate the communication data from waveform information of the corrected modulated light. Lighting communication system. Including a control step of controlling emission of emitted light from a light source that emits light in the visible light range,
The light source is an organic EL light source or an LED light source;
The control step includes
A generation process for generating waveform information of modulated light corresponding to communication data;
A calculation step of calculating the optical information of the modulated light from the waveform information of the modulated light and obtaining a difference from the optical information of the illumination light serving as an evaluation reference,
A correction step of generating waveform information of corrected modulated light in which the difference is corrected; and
An illumination communication method comprising an emission step of emitting the corrected modulated light from a light source.

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