JP2007267040A - Illumination light transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination light transmission system by suppressing optical output variations in illumination light in a transmission state and a non-transmission state and preventing the variations from being conspicuously visually recognized even in the case that ordinary illumination is performed during no data transmission. <P>SOLUTION: A control circuit 2 outputs a frequency control signal to a drive circuit 5a to control an operating frequency of a lighting circuit 5 so that a frequency of a lamp current supplied from the lighting circuit 5 to a fluorescent lamp 3 when no data are superimposed (at non-transmission) is a third frequency f3 being an optical output nearly coincident with an average of optical outputs corresponding to first and second frequencies f1, f2. Since the frequency of the lamp current supplied to the fluorescent lamp 3 at non transmission is controlled to the third frequency f3 and the optical output being the third frequency f3 is nearly coincident with the average of the optical outputs corresponding to the first and second frequencies f1, f2, even when the ordinary illumination is carried out during no data transmission, optical output variations of the illumination light in the transmission state and the non transmission state are suppressed and conspicuous visual recognition of the variations can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination light transmission system including a plurality of lighting fixtures that transmit data superimposed on illumination light emitted from a light source, and one or more receivers that receive data superimposed on the illumination light. is there.

  Conventionally, various illumination light transmission systems having a plurality of lighting fixtures that transmit data superimposed on illumination light and a receiving device that receives data superimposed on illumination light have been proposed.

  Currently, the most widely used light source for general lighting is a fluorescent lamp, and various illumination light transmission systems using a lighting fixture using a fluorescent lamp as a light source (hereinafter referred to as a fluorescent lighting fixture) have been proposed. (For example, refer to Patent Document 1 and Patent Document 2). Such a fluorescent lamp illuminator includes a lighting device (so-called fluorescent lamp electronic ballast) that converts a commercial frequency into a high frequency by an LC resonance type inverter circuit to light the fluorescent lamp at a high frequency (so-called fluorescent lamp electronic ballast). Since the output characteristic of the circuit is a mountain-shaped waveform having a peak at the resonance frequency f0 of the resonance system including the LC resonance circuit and the fluorescent lamp (see FIG. 5), the operating frequency of the inverter circuit is the frequency f1 at rated lighting. By increasing from (> f0) to the modulation frequency f2 (> f1), the power supplied from the inverter circuit to the fluorescent lamp (lamp current) can be decreased, and the light output can be decreased. Therefore, as shown in FIG. 6, when the transmission data is at L level (0), the operating frequency of the inverter circuit is set to the frequency f1 at rated lighting, and when the transmission data is at H level (1), the operating frequency of the inverter circuit is set. By switching to the modulation frequency f2, the operating frequency of the inverter circuit is frequency-modulated with transmission data (FSK <frequency shift keying>), and the transmission data can be superimposed on the illumination light. Note that the operating frequency of the inverter circuit is generally set to 40 to 100 kHz depending on the light emission efficiency of the fluorescent lamp, the dimensions of circuit parts constituting the inverter circuit, heat generation, noise restrictions, and the like.

  When the illumination light is frequency-modulated with the transmission data as described above, the light output of the illumination light emitted from the fluorescent lamp is increased or decreased by the modulation, that is, the light output when the transmission data is at the L level in the above example. On the other hand, the optical output decreases when the transmission data is at the H level. Then, when the frequency of occurrence of 0 and 1 (L level and H level) in the transmission data is biased to either one, the fluctuation of the light output of the illumination light is perceived as flicker that is unacceptable to human eyes. There could be practical problems in use as a lighting fixture. In particular, if normal illumination is performed even when data is not being transmitted, the illumination light is irradiated even when data is not transmitted, so fluctuations in the light output of illumination light between data transmission and non-transmission May be noticeable.

On the other hand, conventionally, the transmission data is Manchester encoded so that the occurrence frequency of 0 and 1 (L level and H level) in the transmission data is made constant and the light output fluctuation of the illumination light is suppressed. (For example, see Patent Document 3).
JP-A-60-32443 Japanese Patent Laid-Open No. 6-20785 JP-T-2002-511727

  However, in the thing of patent document 3, although the average of the light output of the illumination light at the time of data transmission can be made substantially constant, when performing normal illumination even when data transmission is not performed as described above, Even if the transmission data is Manchester encoded, fluctuations in the light output of the illumination light during transmission and during non-transmission cannot be suppressed, and there is a possibility that the transmission data will be visually recognized.

  The present invention has been made in view of the above circumstances, and its purpose is to change the light output fluctuation of illumination light during transmission and during non-transmission even when performing normal illumination when data transmission is not performed. An object of the present invention is to provide an illumination light transmission system that is suppressed so as not to be visually recognized.

  In order to achieve the above object, the invention of claim 1 provides one or more luminaires for transmitting data superimposed on illumination light emitted from a light source, and one or more for receiving data superimposed on illumination light. In this illumination light transmission system, the lighting apparatus superimposes binary data on illumination light emitted from the light source by controlling the lighting means and the lighting means for lighting the light source. Data superimposing means, the data superimposing means switching the frequency of the current supplied from the lighting means to the light source to the first and second frequencies corresponding to the binary data, and not modulating the data. Sometimes, the lighting means is controlled so that the frequency of the current supplied to the light source becomes the third frequency at which the light output substantially matches the average value of the light outputs corresponding to the first and second frequencies. Features and That.

  According to a second aspect of the present invention, in the first aspect of the invention, the data superimposing means encodes the binary data so that the frequency of occurrence of the binary data is a constant ratio, and performs weighting according to the ratio, An average value of the optical output corresponding to the second frequency is obtained.

  According to the first aspect of the invention, the data superimposing means switches the frequency of the current supplied from the lighting means to the light source to the first and second frequencies corresponding to the binary data, and modulates the data. When not superposed, the lighting means is controlled so that the frequency of the current supplied to the light source becomes the third frequency at which the light output substantially matches the average value of the light outputs corresponding to the first and second frequencies. Therefore, when data is not superimposed (during non-transmission), the frequency of the current supplied to the light source is controlled to the third frequency, and the light substantially matches the average value of the light output corresponding to the first and second frequencies. Since it becomes an output, even when performing normal illumination when data transmission is not being performed, it is possible to prevent significant visual recognition by suppressing fluctuations in the light output of illumination light during transmission and during non-transmission. .

  According to the invention of claim 2, the data superimposing means encodes the binary data so that the frequency of occurrence of the binary data is a constant ratio, and performs weighting according to the ratio to the first and second frequencies. Since the average value of the corresponding light output is obtained, the light output fluctuation of the illumination light during transmission and during non-transmission can be appropriately suppressed in various encoding methods.

  The illumination light transmission system of the present embodiment includes one or more lighting fixtures T that irradiate illumination light and one or more receiving devices R.

  As shown in FIG. 1B, the receiving device R receives the illumination light from the lighting fixture T and converts it into an electrical signal, and amplifies the electrical signal (received signal) output from the photoelectric conversion circuit 20. An amplifying circuit 21, a demodulating circuit 22 for demodulating data from the received signal amplified by the amplifying circuit 21, and a receiving data processing circuit 23 for processing data demodulated by the demodulating circuit 22 (received data). .

  The photoelectric conversion circuit 20 includes an optical filter that transmits a frequency component on which illumination light data is superimposed, and a photoelectric conversion element such as a PIN photodiode that converts the frequency component transmitted through the optical filter into an electrical signal. The However, a photo IC in which a phototransistor and an amplifier are integrated may be used instead of the PIN photodiode. The amplifier circuit 21 is a differential amplifier circuit configured by a general-purpose operational amplifier IC or the like, but may be configured by a transistor instead of the operational amplifier IC. However, the amplifier circuit 21 may be omitted if the received signal output from the photoelectric conversion circuit 20 is at a level sufficient for the demodulation circuit 22 to perform demodulation processing.

  The demodulating circuit 22 includes, for example, a bandpass filter (not shown) and a comparison circuit (not shown) that compares the signal level of the received signal that has passed through the bandpass filter with a threshold value. The bandpass filter is a general-purpose filter having a frequency that is twice the modulation frequency f2 as the center frequency of the passband. However, a frequency that is twice the frequency f1 at the time of rated lighting may be used as the center frequency of the passband. In this case, since the logic of the received data to be demodulated is inverted, it is necessary to further invert it at the received data processing unit 23. is there. The comparison circuit is composed of a comparator, which outputs an H level signal when a frequency component twice the modulation frequency f2 passes through the bandpass filter and outputs an L level signal at other times from the lighting fixture T. The received data is demodulated from the received illumination light reception signal.

  The reception data processing circuit 23 includes a microcomputer as a main component. The reception data processing circuit 23 determines the validity of the reception data demodulated by the demodulation circuit 22, and converts the reception data determined to be valid to another electronic device (for example, a PDA). Or the like, the position information included in the received data is displayed on the screen of the display device based on the separately stored map information, or is notified by voice.

  The lighting fixture T is a fluorescent lamp lighting fixture, and as shown in FIG. 1A, a signal source 1 for outputting a data signal (square pulse signal taking binary values of H and L) indicating transmission data, and a signal source A control circuit 2 that encodes a data signal (baseband signal) output from 1 with a Manchester code or the like and superimposes the encoded data on illumination light, a fluorescent lamp 3 as a light source, and a commercial AC power supply AC are rectified and smoothed A DC power supply circuit 4 that converts the DC power into DC power, a lighting circuit 5 that converts the DC power into high-frequency AC power higher than the commercial frequency and lights the fluorescent lamp 3 at a high frequency, and a zero cross point of the commercial AC power supply AC is detected. A zero-cross point detection circuit 6 that performs the above-described operation, and a time-counting circuit 7 that measures a predetermined delay time from the time when the zero-cross point detection circuit 6 detects the zero-cross point.

  In the signal source 1, for example, position information indicating the installation location of the lighting fixture T is set by a dip switch or an EEPROM, and a data signal corresponding to the position information is repeatedly output. Here, the transmission data is an NRZ code, and is output from the signal source 1 as a square pulse having binary values of H and L (see FIG. 4A). The frequency of the data signal output from the signal source 1 is set to a frequency higher than the frequency (CFF: Critical Fusion Frequency) at which the human eye can recognize the light / dark switching of the plurality of light sources. In addition, although it is said that CFF changes with age (the elderly person has the tendency for the responsiveness with respect to the change of light relatively low) and an individual difference, if it is at least 120 kHz or more, there will be no problem in particular. This is because the frequency of the light output waveform of the incandescent lamp that lights at a commercial frequency of 50 Hz or 60 Hz or the fluorescent lamp that lights with a copper-iron ballast is 100 Hz or 120 Hz. Because it is. Therefore, it is only necessary to repeatedly output the data signal at a cycle of 8.3 μsec or less which is the reciprocal of 120 Hz.

  The DC power supply circuit 4 includes a diode bridge DB for full-wave rectifying the AC power supply voltage and a smoothing capacitor C0 for smoothing the full-wave rectified pulsating voltage. However, the configuration of the DC power supply circuit 4 is not limited to this, and a combination of a boost chopper circuit for power factor improvement and a smoothing capacitor may be used, or a battery may be used.

  The lighting circuit 5 is an LC resonance type inverter circuit described in the conventional example, and is connected to a series circuit of two switching elements Q1 and Q2 made of a field effect transistor or a bipolar transistor and at a connection point between the switching elements Q1 and Q2. Are connected to the non-power supply side of the filament of the fluorescent lamp 3 and the inductor C1 connected between the capacitor C1 and one end of the filament of the fluorescent lamp 3 C2 and the inductor L1, the preheating capacitor C2, and the fluorescent lamp 3 are formed of a so-called half-bridge type inverter circuit constituting a resonance circuit. That is, the switching elements Q1 and Q2 are alternately turned on / off at a high frequency by the drive signal output from the drive circuit 5a, thereby converting the DC power supplied from the DC power supply circuit 4 into the high frequency AC power, thereby causing the fluorescent lamp 3 to operate at high frequency. Lights up. As described in the prior art, the output characteristic of the lighting circuit 5 (inverter circuit) when the fluorescent lamp 3 is lit is a mountain-shaped waveform having a peak at the resonance frequency f0 of the resonance circuit (see FIG. 5). ), The drive circuit 5a is controlled by the frequency control signal output from the control circuit 2, and the operating frequency of the lighting circuit 5 (frequency at which the switching elements Q1 and Q2 are turned on / off) is the rated lighting frequency (first frequency). By increasing the frequency from f1 (> f0) to the modulation frequency (second frequency) f2 (> f1), the power supplied from the lighting circuit 5 to the fluorescent lamp 3 (lamp current) can be decreased to decrease the light output. For example, the operating frequency of the lighting circuit 5 is set to the first frequency f1 when the transmission data output from the signal source 1 is at the L level, and the operating frequency of the lighting circuit 5 is set to the first frequency when the transmission data is at the H level. Is superimposed the transmission data to the illumination light by frequency modulating (FSK) on the transmission data the operating frequency of the ballast circuit 5 is switched to the frequency f2 of the. That is, in the present embodiment, the control circuit 2 corresponds to data superimposing means. However, the configuration of the lighting circuit 5 is not limited to this, and may be a conventionally known full-bridge type or monolithic type inverter circuit, or a boost chopper circuit and a switching element constituting the DC power supply circuit 4. A configuration in which parts such as these are shared may be used.

  The control circuit 2 includes a microcomputer as a main component, and adjusts the frequency (the operating frequency of the lighting circuit 5) at which the drive circuit 5a drives the switching elements Q1 and Q2 by the frequency control signal, thereby preheating, starting, Lighting and superimposition of transmission data are performed. Further, the control circuit 2 performs encoding (for example, Manchester encoding) such that the frequency of occurrence of 0 and 1 (L level and H level) is constant in order to suppress fluctuations in the light output of illumination light during data transmission. Execute on transmission data. However, specific control contents regarding preheating, starting, and lighting of the fluorescent lamp 3 are well known in the art and will not be described. The timer circuit 7 is constituted by a microcomputer constituting the control circuit 2, but may be constituted by an independent timer IC.

  The zero-cross point detection circuit 6 uses a detection voltage Vx obtained by dividing the pulsating current output of the diode bridge DB by voltage dividing resistors R1 and R2, and a control voltage Vcc created by a constant voltage circuit (not shown) by voltage dividing resistors R3 and R4. The divided reference voltage Vth is compared with the comparator CP, and when the detection voltage Vx is lower than the reference voltage Vth, an H level zero cross point detection signal is output to the control circuit 2. A diode D is inserted between the voltage dividing resistor R1 and the smoothing capacitor C0 so that the charge of the smoothing capacitor C0 is not discharged through the voltage dividing resistors R1 and R2. Further, the harmonic component contained in the pulsating voltage is prevented from being input to the comparator CP by the capacitor C3 connected in parallel with the voltage dividing resistor R2.

  In the control circuit 2, the timing circuit 7 starts measuring the predetermined delay time ST from the time when the zero-cross point detection signal is input from the zero-crossing point detection circuit 6, and when the timing circuit 7 finishes measuring the delay time ST. The transmission data output from the signal source 1 is superimposed on the illumination light.

  For example, as shown in FIG. 2, when four lighting fixtures T1 to T4 repeatedly transmit 8-bit transmission data, the control circuits 2 of the respective lighting fixtures T1 to T4 have different delay times ST1 to ST4 ( It is assumed that ST1 <ST2 <ST3 <ST4) is set. The control circuit 2 of the lighting fixture T1 immediately superimposes the transmission data output from the signal source 1 on the illumination light when the zero cross point detection signal is input, and the control circuit 2 of the lighting fixture T2 receives the zero cross point detection signal. The transmission data output from the signal source 1 is superimposed on the illumination light at the time when the delay time ST2 has elapsed from the point in time, and the control circuit 2 of the lighting fixture T3 has the delay time ST3 ( = ST2 × 2), the transmission data output from the signal source 1 is superimposed on the illumination light, and the control circuit 2 of the luminaire T4 has a delay time ST4 (= ST2) from the time when the zero-cross point detection signal is input. The transmission data output from the signal source 1 at the time when × 3) has elapsed is superimposed on the illumination light and transmitted. In addition, although delay time ST1 of lighting fixture T1 is set to zero, it does not necessarily need to be zero. Further, although the delay times ST3 and ST4 are two times and three times ST2, it is not necessarily required to be a multiple, and may be a transmission period of transmission data and a period longer than the multiple.

  As described above, in the present embodiment, a plurality of lighting fixtures T transmit transmission data in a time-division multiplex manner while synchronizing at the zero cross point of the commercial AC power supply. Therefore, even in a period in which the transmission data is not superimposed on the illumination light. While performing normal illumination, it is possible to prevent data received by being superimposed on illumination light from a plurality of lighting fixtures T from colliding and being unable to be normally received by the receiving device R.

  Next, the light output control of illumination light by the control circuit 2 when data is not transmitted (during non-transmission), which is the gist of the present invention, will be described.

  As described in the prior art, if the transmission data is Manchester encoded, the average light output of the illumination light at the time of data transmission can be made almost constant, but when normal illumination is performed even when data transmission is not performed (for example, In a case where a plurality of lighting fixtures T performs time division multiplex transmission of data), even if transmission data is Manchester-encoded, fluctuations in the light output of illumination light during transmission and during non-transmission cannot be suppressed. Therefore, in the present embodiment, when the data is not superimposed (during non-transmission), the frequency of the lamp current supplied from the lighting circuit 5 to the fluorescent lamp 3 corresponds to the first frequency f1 and the second frequency f2. The control circuit 2 outputs a frequency control signal to the drive circuit 5a so that the third frequency f3 (f1 <f3 <f2) is obtained, which is a light output that substantially matches the average value of the lighting circuit. 5 is controlled (see FIG. 3). If the control circuit 2 controls the operating frequency of the lighting circuit 5 at the time of non-transmission in this way, the frequency of the lamp current supplied to the fluorescent lamp 3 is the third frequency when data is not superimposed (at the time of non-transmission). Since the light output is controlled to f3 and substantially matches the average value of the light outputs corresponding to the first and second frequencies f1 and f2, even when performing normal illumination when data transmission is not performed, The light output fluctuation of the illumination light at the time of transmission and at the time of non-transmission can be suppressed to prevent it from being visually recognized.

  Here, the encoding method executed by the control circuit 2 is not limited to Manchester encoding (see FIG. 4G), and various encoding methods described below can be employed.

  For example, as shown in FIG. 4B, the bit pattern (how 0 and 1 are arranged) may be encoded with the first half of the basic unit time as the data signal itself and the second half with the bit obtained by inverting the bit of the data signal. However, when the same data signal is repeatedly transmitted, the unit time is 8.3 μsec or less, and when it is not repeatedly transmitted, the unit time is 4.1 μsec or less. Further, as shown in FIG. 4C, both the 0 level and the 1 level in the data signal are always in the order of the rated lighting frequency (first frequency) f1 → second frequency f2 in the order of the data signal. The level 0 may be 2t, and the level 1 may be 4t (t is the basic time). However, the order of the second frequency f2 → the first frequency f1 may be used. Further, the cycle may be such that 0 level in the data signal is 4t and 1 level is 2t. Alternatively, as shown in FIG. 4D, the time per bit may be made equal. In this case, the transmission time is constant regardless of the transmission data, and time management in the control circuit 2 is facilitated. In these encoding methods, the generation ratios of the first frequency f1 and the second frequency f2 are equal in units of 1 bit as in Manchester encoding. Further, since the data signal includes a clock component, it is easy to synchronize the signals, and the reception device R can check not only the frequency but also the time width, and the reception reliability is improved. Furthermore, since the time from the falling to the falling (second frequency f2 → first frequency f1) is always 1 bit regardless of the data signal, as a characteristic of a fluorescent lamp luminaire, phosphorescence phenomenon of phosphors and A change from “dark” to “bright” (second frequency f2 → first frequency f1) and a change from “bright” to “dark” (first frequency f1) due to the control response of the lighting circuit 5 and the like. → When there is a difference in the time of the second frequency f2), the difference between the signal “10” (f1, f2, f2, f1) and “11” (f1, f2, f1, f2) is discriminated. In addition, it is possible to reduce erroneous reception due to time variation of the frequency control signal corresponding to the second frequency f2.

  Further, as shown in FIG. 4E, the bit pattern corresponding to the start of the data signal is “LHHHHHHL”, the bit pattern corresponding to the 1 level is “HLHH”, and the bit pattern corresponding to the 0 level is “HHLH”. May be used (where the H level is the first frequency f1, and the L level is the second frequency f2). Note that six "H" s continue only at the start of the data signal and can be distinguished from the data signal. Also in such an encoding method, the generation ratio of the first frequency f1 and the second frequency f2 is equal in units of 1 bit as in Manchester encoding. Further, since the data signal includes a clock component, it is easy to synchronize the signals, and the reception device R can check not only the frequency but also the time width, and the reception reliability is improved. Further, since the ratio between the first frequency f1 and the second frequency f2 is always 3: 1, the average light output of the illumination light becomes relatively high, which is advantageous in terms of the size and cost of the parts constituting the lighting circuit 5. become. On the contrary, since the frequency at the time of dimming can be made higher than other methods, the difference between the first frequency f1 and the second frequency f2 can be made large, so that the reception reliability is improved.

  Further, as shown in FIG. 4F, the bit pattern corresponding to the start of the data signal is “LHHHLHL”, the bit pattern corresponding to the 1 level is “HLH”, and the bit pattern corresponding to the 0 level is “HHL”. May be used (where the H level is the first frequency f1, and the L level is the second frequency f2). Note that four “H” s continue only at the start of the data signal and can be distinguished from the data signal. Also in such an encoding method, the generation ratio of the first frequency f1 and the second frequency f2 is equal in units of 1 bit as in Manchester encoding. Further, since the data signal includes a clock component, it is easy to synchronize the signals, and the reception device R can check not only the frequency but also the time width, and the reception reliability is improved. Furthermore, since the ratio between the first frequency f1 and the second frequency f2 is always 2: 1, the average light output of the illumination light becomes relatively high, which is advantageous in terms of the size and cost of the parts constituting the lighting circuit 5. become. On the contrary, since the frequency at the time of dimming can be made higher than other methods, the difference between the first frequency f1 and the second frequency f2 can be made large, so that the reception reliability is improved.

  In the Manchester encoding method shown in FIG. 4G and the encoding methods shown in FIGS. 4B to 4D, the ratio between the first frequency f1 and the second frequency f2 is always equal. The optical outputs corresponding to the first and second frequencies f1 and f2 may be obtained by simply arithmetically averaging, but in the encoding method shown in FIG. 4E, the first frequency f1 and the second frequency f2 are obtained. The ratio of the first frequency f1 and the second frequency f2 is 2: 1 in the encoding method shown in FIG. , F2 is preferably weighted when the average value of the optical output corresponding to f2 is obtained. That is, assuming that the operating frequency is proportional to the lamp current (light output), the third value corresponding to the average value of the light output when the ratio between the first frequency f1 and the second frequency f2 is 3: 1. The frequency f3 is obtained by f3 = f1 + (f1 + f2) / 4, and when the ratio between the first frequency f1 and the second frequency f2 is 2: 1, the third frequency f3 corresponding to the average value of the optical output is It is obtained by f3 = f1 + (f1 + f2) / 3. Then, the control circuit 2 sets the lighting circuit so that the third frequency f3, which is a light output substantially equal to the average value of the light outputs thus obtained, matches the operating frequency of the lighting circuit 5 during non-transmission. 5 is controlled. In this embodiment, a fluorescent lamp is exemplified as the light source. However, a discharge lamp other than the fluorescent lamp (for example, a high-intensity discharge lamp such as HID or an electrodeless discharge lamp), an incandescent lamp, a light emitting diode, an organic EL element, or the like. Any individual light emitting element may be used as long as it can superimpose data by frequency-modulating the supplied power and the light output changes with frequency modulation.

(A) is a block diagram of the lighting fixture in this embodiment, (b) is a block diagram of a receiver. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. (A)-(g) is explanatory drawing of the encoding method of the data signal in the same as the above. It is operation | movement explanatory drawing same as the above. It is explanatory drawing of a prior art example.

Explanation of symbols

T lighting fixture R receiver 1 signal source 2 control circuit 3 fluorescent lamp 4 DC power supply circuit 5 lighting circuit

Claims (2)

An illumination light transmission system comprising one or more lighting fixtures that transmit data superimposed on illumination light emitted from a light source, and one or more receivers that receive data superimposed on the illumination light,
The luminaire includes a light source, a lighting unit that turns on the light source, and a data superimposing unit that controls the lighting unit to superimpose binary data on the illumination light emitted from the light source,
The data superimposing means switches the frequency of the current supplied from the lighting means to the light source to the first and second frequencies corresponding to binary data and modulates the frequency, and when the data is not superimposed, is supplied to the light source. An illumination light transmission system, wherein the lighting means is controlled so that the current frequency becomes a third frequency at which the light output substantially matches the average value of the light outputs corresponding to the first and second frequencies. .   The data superimposing means encodes so that the occurrence frequency of binary data is a constant ratio, and performs weighting according to the ratio to obtain an average value of the optical outputs corresponding to the first and second frequencies. The illumination light transmission system according to claim 1.

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