JP5870305B2 - Illumination light communication apparatus and illumination light communication system - Google Patents

Description

  The present invention relates to an illumination light communication apparatus and an illumination light communication system.

  2. Description of the Related Art Conventionally, a lighting fixture that includes a light emitting diode (LED) as a light source has been proposed that transmits a signal by modulating the intensity of illumination light. In such an illumination light communication device, a signal is transmitted by modulating the illumination light itself, so that a special device such as an infrared communication device is not required. In addition, since a power saving can be realized by using a light emitting diode as a light source for illumination, use for a ubiquitous information system in an underground shopping mall is being studied.

  FIG. 44 is a circuit diagram of a conventional illumination light communication apparatus. A constant current circuit 52, three light emitting diodes 53, and a switch element Q1 are connected in series between both ends of a DC power source 51. When the switch element Q1 is turned on / off according to the high / low of the optical communication signal S1, the load current I1 flowing through the light emitting diode 53 is modulated while maintaining constant current (see FIG. 45).

  In this circuit, the circuit loss of the constant current circuit 52 provided for stably lighting the light-emitting diode 53 having a small operating resistance increases. For example, on the assumption that the load current I1 is 500 mA, the case where the constant current circuit 52 is configured with a constant current diode is calculated. The circuit loss is about 2.3 W, and the advantage of using a light-emitting diode with low power consumption Will be damaged.

  Therefore, as shown in FIG. 46A, it is conceivable to reduce the circuit loss by providing a DC-DC converter instead of the constant current circuit 52 and performing PWM control on the DC-DC converter. In this circuit, a current detection resistor R 3, three light emitting diodes 53, an inductor L 1, and a switch element Q 1 are connected in series between both ends of the DC power supply 51, and the switch element Q 1 is turned on / off by the control circuit 54. Is controlled. Further, a smoothing capacitor C3 and a rectifier diode D2 are connected between both ends of a series circuit of the three light emitting diodes 53 and the inductor L1, and a DC-DC converter is configured together with the inductor L1 and the switch element Q1. The control circuit 54 receives a feedback signal from the constant current feedback circuit 55 and controls the output current of the DC-DC converter to be substantially constant. Further, the optical communication signal S1 is input to the control circuit 54, and the load current I1 is modulated by turning on / off the switch element Q1 at a high frequency while the optical communication signal S1 is high (FIG. 47). (See (a) to (c)).

  FIG. 46B shows a specific circuit of the constant current feedback circuit 55. The error amplifier A1 compares the voltage drop of the resistor R3 through which the load current I1 flows with the reference voltage E1, and amplifies the deviation. And output to the control circuit 54. The series circuit of the resistor R4 and the capacitor C2 connected between the inverting input terminal and the output terminal of the error amplifier A1 constitutes a phase compensation circuit for ensuring the stability of the feedback system. In such a phase compensation circuit, a compensation circuit including an integration element is generally used to adjust a gain and a phase in a circuit transfer function, which is known as PI control or PID control in classical information theory. For example, FIG. 46C is a circuit diagram of an average current detection circuit disclosed in Patent Document 1, and an integration circuit 56 (consisting of a resistor R5 and a capacitor C3) connected between both ends of the current detection resistor R3 is as follows. It can be said that the above-described PI control is used as the output averaging means.

JP 2006-120910 A

  In the illumination optical communication apparatus of FIG. 46A described above, the load current I1 is modulated by intermittently operating the DC-DC converter according to the optical communication signal S1, but the optical communication signal S1 is faithfully reproduced. In order to obtain a current waveform reproduced in the following, the following two conditions are required. The two conditions are that the operating frequency of the DC-DC converter is higher than that of the optical communication signal (condition 1) and that the load current I1 is not smoothed (condition 2).

  In order to satisfy the above condition 1, for example, when the communication speed is 9.6 kbps, the operating frequency of the DC-DC converter is 100 kHz or more (about 10 times the communication speed), preferably 1 MHz or more (about 100 times or more). It is necessary to. However, if the operating frequency of the DC-DC converter is set to a high frequency, there is a problem that the loss of the switch element Q1 constituting the DC-DC converter increases and a countermeasure for noise reduction is required.

  The above condition 2 is that when a smoothing capacitor is connected in parallel with the light emitting diode 53, the load current I1 is not interrupted even when the switching element Q1 of the DC-DC converter is interrupted, and the load current corresponding to the optical communication signal This is because the modulation of I1 becomes difficult. On the other hand, if the load current I1 is not smoothed, a ripple current corresponding to the operating frequency component of the DC-DC converter is generated in the load current I1, so that it is necessary to take measures against noise from wiring and the like. In order to suppress the ripple of the operating frequency component with a smoothing capacitor having as small a capacity as possible so as not to smooth the load current I1, it is preferable to increase the operating frequency of the DC-DC converter. However, when the operating frequency is increased, there is a problem that the loss of the switching element Q1 increases.

  Conventionally, an illumination optical communication apparatus using a DC-DC converter to which a constant current feedback circuit is added has been proposed having a circuit configuration as shown in FIG. In this circuit, a DC-DC converter 62 operates with input from a DC power supply 61, and its output is converted into a DC voltage having a desired voltage value by a rectifier circuit 63 and a smoothing capacitor C4. Three light emitting diodes 64 and a current detection resistor R4 are connected in series between both ends of the smoothing capacitor C4. The voltage drop generated in the resistor R4 due to the flow of the load current I1 is compared with the reference voltage E1 by the error amplifier A2, amplified, and fed back to the output control unit 65 of the DC-DC converter 62, thereby determining the load current I1. The current is controlled. Incidentally, a series circuit of a resistor R5 and a capacitor C5 is connected between the inverting input terminal and the output terminal of the error amplifier A2 to constitute a phase compensation circuit, which increases the gain in the low frequency region and increases the frequency region. The phase of the feedback signal is adjusted while suppressing the gain at.

  FIG. 49A is a Bode diagram showing the output characteristics of this circuit, and the gain (L1 in FIG. 49A) decreases linearly with increasing frequency. Further, the phase angle (L2 in FIG. 49 (a)) is maintained around 90 degrees up to about 10 kHz and the phase margin is secured, so the stability of the feedback control system is good.

  In the circuit of FIG. 48, the reference voltage E1 or E2 is connected to the non-inverting input terminal of the error amplifier A2 via the switch SW1, and the load current I1 can be modulated by switching the switch SW1 according to the optical communication signal S1. It has become. That is, one reference voltage E1 is set to be the load current I1 when used as normal illumination, and the other reference voltage E2 is set to a value such that the load current I1 is smaller than the normal value. It is set to. The load current is modulated by switching the switch SW1 according to the optical communication signal S1. Here, the simulation result of the load current I1 when the load current at the reference voltage E1 is 500 mA, the load current at the reference voltage E2 is 100 mA, and the switch SW1 is switched according to the optical communication signal of 10 kHz is shown in FIG. Shown in In this simulation result, the load current I1 is averaged to an intermediate value (about 300 mA) between the current value (500 mA) at the reference voltage E1 and the current value (100 mA) at the reference voltage E2, and the optical communication signal The load current I1 is not modulated according to the above.

  As can be seen from the Bode diagram of FIG. 49A, when the frequency of the optical communication signal is around 10 kHz, the gain of the error amplifier A2 cannot be expected by PI control, and the output control cannot follow and the reference voltage E1 cannot be followed. , Only the load current obtained by averaging the load currents at E2 can be obtained. Here, if the phase compensation circuit is removed from the circuit of FIG. 48, the gain of the error amplifier A2 can be secured even in a high frequency region, and modulation of the load current according to the optical communication signal can be expected, but the feedback system is unstable. This could cause abnormal oscillation. Therefore, there is a problem that it is difficult to modulate the load current I1 by changing the circuit constant of the phase compensation circuit added to the error amplifier A2.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a simple circuit to be added for communication, and capable of faithfully modulating output light in accordance with a high-frequency optical communication signal. An object of the present invention is to provide an optical communication device and an illumination light communication system.

In order to solve the above-described problems, the illumination light communication apparatus of the present invention includes a switching power supply, a load circuit including a light emitting diode connected between outputs of the switching power supply, and the load circuit added to the load circuit. A load fluctuation element that changes a load current flowing through the circuit, a load fluctuation section that switches whether or not to add the load fluctuation element to the load circuit in accordance with a binary optical communication signal, and the load fluctuation element includes the load Regardless of whether or not it is added to the circuit, a feedback circuit that controls the average value of the load current to be constant, the feedback circuit is a state in which the load variation element is added to the load circuit And when the load variation element is not added to the load circuit, the load current is modulated to a predetermined current value, and the optical communication signal is transmitted. As the average current in the time of transmission stop it is constant, and controlling the switching power supply.

In this illumination optical communication device, the optical communication signal is a rectangular wave signal whose on-duty is adjusted, and in the state where the load variation element is connected to the load circuit, an average value and a bottom value of the load current are obtained. When the difference is d1, and the difference between the peak value and the average value of the load current is d2, if the on-duty of the optical communication signal is 50%, d1 = d2, and the on-duty of the optical communication signal is 50 It is also preferable that d1> d2 if it is larger than%, and d1 <d2 if the on-duty of the optical communication signal is smaller than 50% .

The illumination light communication apparatus of the present invention changes a load current flowing through the load circuit by adding the switching power supply, a load circuit including a light emitting diode connected between outputs of the switching power supply, and the load circuit. A load fluctuation unit that switches whether to add the load fluctuation element to the load circuit according to a binary optical communication signal, and the optical communication signal is a rectangle whose on-duty is adjusted. In the state where the load variation element is connected to the load circuit, the difference between the average value and the bottom value of the load current is d1, and the difference between the peak value and the average value of the load current is d2. In this case, d1 = d2 if the on-duty of the optical communication signal is 50%, and d1> d2 if the on-duty of the optical communication signal is greater than 50%, and the optical communication On-duty of the No. is characterized in that it is configured such that if d1 <d2 smaller than 50%.

  In this illumination light communication apparatus, it is also preferable that the load variation element is a thermistor.

  The illumination light communication system of the present invention includes any one of the illumination light communication devices described above and a receiver that receives light output from the illumination light communication device.

  According to the present invention, a circuit added for communication is simple, and output light can be modulated faithfully according to a high-frequency optical communication signal.

The illumination light communication apparatus of Embodiment 1 is shown, (a) is a circuit diagram, (b) is the circuit diagram modeled for simulation. (A) and (b) are waveform diagrams showing simulation results. The illumination light communication apparatus of Embodiment 2 is shown, (a) is a circuit diagram, (b) is the circuit diagram modeled for simulation. (A)-(e) is a circuit diagram which shows the principal part of the illumination optical communication apparatus of Embodiment 3. FIG. (A) is a circuit diagram of the illumination light communication apparatus of Embodiment 4, (b) (c) is a circuit diagram which shows the principal part. It is a circuit diagram of the illumination light communication apparatus of Embodiment 5. The illumination light communication apparatus of Embodiment 6 is shown, (a) is a circuit diagram, (b) is a circuit diagram modeled for simulation, (c) is a waveform diagram showing a simulation result. (A) (b) is a circuit diagram which shows another structure same as the above. It is a circuit diagram of the illumination light communication apparatus of Embodiment 7. It is a circuit diagram of the illumination light communication apparatus of Embodiment 8. The illumination light communication apparatus same as the above is shown, (a) is a circuit diagram modeled for simulation, and (b) is a waveform diagram showing a simulation result. (A) (b) is a circuit diagram which shows another structure same as the above. (A)-(c) is a wave form diagram of the load current which flows into the illumination optical communication apparatus of Embodiment 9. FIG. It is the circuit diagram which modeled the same as the above for simulation. (A)-(c) is a wave form diagram which shows a simulation result. (A)-(d) is a circuit diagram of the illumination optical communication apparatus of Embodiment 10. FIG. It is a circuit diagram which shows another structure same as the above. It is a circuit diagram of the illumination light communication apparatus of Embodiment 11. (A) is a circuit diagram which shows the other structure same as the above, (b) (c) is a circuit diagram which shows the specific structure of a communication unit. (A) and (b) are the circuit diagrams of the illumination light communication apparatus of Embodiment 12. FIG. It is a circuit diagram of the illumination light communication apparatus of Embodiment 13. (A)-(e) is a wave form diagram of each part same as the above. (A) is the circuit diagram of the illumination light communication apparatus of Embodiment 14, (b) is the circuit diagram modeled for simulation. (A) (b) is a wave form diagram which shows the simulation result of the load current same as the above. (A)-(c) is a wave form diagram which shows the simulation result of load current same as the above. (A)-(e) is a wave form diagram which shows the simulation result of load current same as the above. It is a circuit diagram of the illumination light communication apparatus of Embodiment 15. (A)-(c) is a wave form diagram which shows the simulation result of load current same as the above. It is a circuit diagram which shows the other circuit structure of an illumination light communication apparatus same as the above. (A)-(c) is a wave form diagram which shows the simulation result of load current same as the above. It is a circuit diagram of the illumination light communication apparatus of Embodiment 16. (A) (b) is a wave form diagram which shows the simulation result of the load current same as the above. (A) is a circuit diagram of the illumination light communication apparatus of Embodiment 17, (b)-(d) is explanatory drawing of the specific example of a current limiting element. (A)-(c) is a circuit example of the load circuit which comprises the same as the above. (A) and (b) are the circuit diagrams of the illumination light communication apparatus of Embodiment 18. FIG. (A) is the circuit diagram of the illumination light communication apparatus of Embodiment 19, (b) is the circuit diagram modeled for simulation. (A)-(c) is a wave form diagram which shows the simulation result of load current same as the above. It is a circuit diagram which shows the other circuit structure same as the above. (A)-(c) is a wave form diagram which shows the simulation result of load current same as the above. It is a circuit diagram of the comparative example same as the above. (A) (b) is a wave form diagram which shows the simulation result of the load current same as the above. It is a circuit diagram of the illumination light communication apparatus of Embodiment 20. (A)-(d) is a circuit diagram of the illumination optical communication apparatus of Embodiment 21. FIG. It is a circuit diagram of the conventional illumination light communication apparatus. (A) (b) is a wave form diagram explaining operation | movement same as the above. (A)-(c) is a circuit diagram which shows another prior art example. (A)-(c) is a wave form diagram explaining the operation | movement same as the above. It is a circuit diagram of another conventional illumination light communication apparatus. The illumination optical communication apparatus same as the above is shown, (a) is a Bode diagram, (b) is a waveform diagram of load current.

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

(Embodiment 1)
The illumination light communication apparatus of Embodiment 1 is demonstrated based on FIG. FIG. 1A is a circuit diagram of the illumination light communication apparatus 10. The illumination light communication apparatus 10 includes a constant current source 11, a smoothing capacitor C 11 (smoothing circuit), a load circuit 12, and a load variation element 13. The signal generation circuit 14 and the switch element Q2 are provided.

  The smoothing capacitor C11 is connected between the outputs of the constant current source 11, and smoothes the output of the constant current source 11.

  The load circuit 12 includes a plurality of light emitting diodes LD1 connected in series between the outputs of the constant current source 11, and is supplied with the output of the constant current source 11.

  The load variation element 13 is added to the load circuit 12 to partially change the load characteristics of the load circuit 12, and is composed of, for example, a resistor connected in parallel to some of the light emitting diodes LD1.

  The signal generation circuit 14 generates a binary optical communication signal. The signal generation circuit 14 may generate a binary optical communication signal in accordance with a transmission signal input from an external device.

  The switch element Q2 includes a switching element (for example, a MOSFET) connected in series with a resistor constituting the load variation element 13, for example. The switch element Q2 switches whether to add the load variation element 13 to the load circuit 12 by being switched on / off by a binary optical communication signal.

  FIG. 1B is a circuit diagram in which the circuit of FIG. 1A is modeled for simulation. Elements corresponding to the circuit components of FIG. 1A are denoted by the same reference numerals. The light emitting diode LD1 is equivalently replaced by a series circuit of a zener diode ZD11 having a constant on-voltage and an on-resistance R11. As the load variation element 13, a resistor R12 connected in parallel to the on-resistance R11 when the switch element Q2 is on is used. That is, a series circuit of a resistor R12 and a switch element Q2 is connected between both ends of the on-resistance R11. The signal generation circuit 14 is equivalently replaced by an oscillator 14a that generates a 10 kHz rectangular wave signal corresponding to the optical communication signal S1.

  FIGS. 2A and 2B show the results of simulating the load current I1 using the circuit of FIG. FIG. 2A shows the result of simulating the load current I1 with the optical communication signal S1 stopped, and the average current is about 500 mA. FIG. 2B shows a waveform diagram of the load current I1 flowing through the light emitting diode LD1. In this waveform diagram, a rectangular wave signal of 10 kHz is output from the oscillator 14a, and the state in which the resistor R12 is connected in parallel to the on-resistance R11 by the switch element Q2 and the state in which the resistor R12 is not connected to the on-resistance R11 are alternately performed. It is a wave form diagram at the time of switching and giving modulation to load current I1. Here, the load current I1 is about 600 mA when the switch element Q2 is turned on, and about 400 mA when the switch element Q2 is turned off. A modulation waveform faithful to the optical communication signal S1 is obtained, and the average current is the optical communication signal. About 500 mA in a state where S1 is stopped is maintained.

  An optical communication signal that is an optical output from the illumination optical communication device 10 is received by a receiver 20 having a photo IC, and the optical output is not superimposed on the optical communication signal and the optical communication signal is superimposed on the receiver 20. A method of receiving an optical communication signal by detecting a difference from the optical output is adopted. By adopting such a method, even a minute modulated light can be detected.

  As described above, the illumination light communication apparatus 10 of the present embodiment includes the constant current source 11, the smoothing circuit (comprising the smoothing capacitor C11), the load circuit 12, the load variation element 13, and the switch element Q2. Prepare. The smoothing circuit and the load circuit 12 including the light emitting diode LD1 are connected to the output of the constant current source 11, respectively. The load fluctuation element 13 is added to the load circuit 12 to partially change the load characteristic of the load circuit 12. The switch element Q2 switches whether to add the load variation element 13 to the load circuit 12 according to a binary optical communication signal.

  Thereby, since the load characteristic of the load circuit 12 changes according to the optical communication signal, the load current flowing through the light emitting diode LD1 is modulated faithfully to the waveform of the optical communication signal.

  By the way, in the simulation circuit of FIG. 2B, the variation due to the load variation element 13 is added to the on-resistance R11 constituting the equivalent circuit of the light emitting diode LD1, but the variation is added to the voltage value of the Zener diode ZD1. Even when it is added, the load current I1 can be modulated as described above.

(Embodiment 2)
Embodiment 2 of the illumination light communication apparatus will be described with reference to FIG. FIG. 3A is a circuit diagram of the illumination light communication apparatus 10, and the same components as those in the circuit of FIG. 1A described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. . In the present embodiment, a plurality of light emitting diodes LD1 and a resistor R12 are connected between both ends of the smoothing capacitor C11, and a switch element Q2 is connected between both ends of the resistor R12. Here, the load variation element 13 is configured by the resistor R12 connected in series with the plurality of light emitting diodes LD1, and the switch element Q2 is turned on / off according to the optical communication signal, whereby the load characteristic of the light emitting diode LD1 is increased. The same effect as the fluctuation can be obtained.

  FIG. 3B is a circuit diagram in which the circuit of FIG. 3A is modeled for simulation. Elements corresponding to the circuit components of FIG. 3A are denoted by the same reference numerals. Also in this simulation circuit, the light emitting diode LD1 is equivalently replaced by a series circuit of a Zener diode ZD11 having a constant ON voltage and an ON resistance R11. The signal generation circuit 14 is equivalently replaced by an oscillator 14a that generates a 10 kHz rectangular wave signal corresponding to the optical communication signal S1.

  The result of simulating the load current I1 using the circuit of FIG. 3B is the same as the simulation result of FIGS. 2A and 2B, and the load current I1 when the optical communication signal S1 is stopped is DC. It is about 500mA. Further, in a state where a 10 kHz rectangular wave signal is input to the switch element Q2 as the optical communication signal S1, the switch element Q2 is turned on / off, whereby both ends of the resistor R12 are short-circuited or opened to emit light. Modulation is applied to the current I1 flowing through the diode LD1. As a result, the load current I1 is about 600 mA when the switch element Q2 is turned on and about 400 mA when the switch element Q2 is turned off, and a modulation waveform faithful to the change of the optical communication signal S1 is obtained. This is substantially the same as about 500 mA in a state where S1 is stopped.

  As described above, according to the illumination light communication device 10 of the present embodiment, the light emitting diode LD1 and the resistor R12 that is the load variation element 13 are connected to the constant current source 11, and the resistor R12 is added to the load circuit 12. Whether or not to switch is switched by the switch element Q2. That is, the load variation element 13 includes a resistor R12 connected in series to the light emitting diode LD1, and the switch element Q2 is connected in parallel to the resistor R12.

  Thereby, the switch element Q2 switches whether or not the resistor R12 is added to the load circuit 12, whereby the load characteristic of the light emitting diode LD1 can be changed according to the optical communication signal, and the load current is changed to the optical communication signal. Can be faithfully modulated to the waveform.

(Embodiment 3)
Embodiment 3 of the illumination light communication apparatus will be described with reference to FIG. The illumination light communication apparatus 10 of the present embodiment is different from the illumination light communication apparatus 10 described in the first or second embodiment only in the configuration of the load variation element 13, and in FIG. 4, the load variation element 13 and the switch element Q2 are portions. Only the other parts are shown, and the other parts are not shown.

  In the circuit of FIG. 4A, a diode D21 is used as the load variation element 13, and this diode D21 is connected in series with the light emitting diode LD1. A switch element Q2 is connected in parallel with the diode D21. When the switch element Q2 is turned on, both ends of the diode D21 are short-circuited via the switch element Q2, and the diode D21 is not connected to the light emitting diode LD1. On the other hand, when the switch element Q2 is turned off, the diode D21 is connected to the light emitting diode LD1. Thus, when the switch element Q2 is turned on / off according to the optical communication signal S1, the same effect as that obtained by changing the load characteristic of the load circuit 12 including the light emitting diode LD1 can be obtained. Therefore, as described in the first and second embodiments, the load current flowing through the light emitting diode LD1 can be modulated faithfully to the waveform of the optical communication signal.

  In the circuit of FIG. 4B, a Zener diode ZD2 is used as the load fluctuation element 13, and this Zener diode ZD2 is connected in series with the light emitting diode LD1. A switch element Q2 is connected in parallel with the Zener diode ZD2. In this circuit, the same effect as that obtained by changing the load characteristic of the load circuit 12 including the light emitting diode LD1 can be obtained by turning on / off the switch element Q2 in accordance with the optical communication signal S1. Furthermore, in this circuit, the modulation width of the load current I1 flowing through the light emitting diode LD1 can be easily adjusted by selecting the Zener voltage of the Zener diode ZD2.

  In the circuit of FIG. 4C, the thermistor resistor Rh1 is used as the load fluctuation element 13, and this thermistor resistor Rh1 is connected in series with the light emitting diode LD1. A switch element Q2 is connected in parallel with the thermistor resistor Rh1. In this circuit, the same effect as that obtained by changing the load characteristic of the load circuit 12 including the light emitting diode LD1 can be obtained by turning on / off the switch element Q2 in accordance with the optical communication signal S1. Further, in this circuit, it is possible to give temperature characteristics to the degree of modulation of the load current I1 flowing through the light emitting diode LD1 and to add temperature correction.

  Further, in the circuit of FIG. 4D, a parallel circuit of a resistor R13 and a diode D22 is used as the load variation element 13, and this parallel circuit is connected in series with the light emitting diode LD1, and a switch is connected in parallel with the parallel circuit. Element Q2 is connected. In this circuit, the same effect as that obtained by changing the load characteristic of the load circuit 12 including the light emitting diode LD1 can be obtained by turning on / off the switch element Q2 in accordance with the optical communication signal S1. A parallel circuit of a resistor R13 and a diode D22 is connected in series with the light emitting diode LD1, and the modulation width of the load current I1 flowing through the light emitting diode LD1 is finely adjusted by adjusting the resistance value of the resistor R13, for example. Can do.

In the circuit of FIG. 4E, a series circuit of a resistor R13 and a diode D22 is used as the load fluctuation element 13, and this series circuit is connected in series with the light emitting diode LD1, and is connected between both ends of the series circuit. Switch element Q2 is connected. In this circuit, the same effect as that obtained by changing the load characteristic of the load circuit 12 including the light emitting diode LD1 can be obtained by turning on / off the switch element Q2 in accordance with the optical communication signal S1. Further, a series circuit of a resistor R13 and a diode D22 is connected in series with the light emitting diode LD1, and the modulation width of the load current I1 flowing through the light emitting diode LD1 is finely adjusted by adjusting the resistance value of the resistor R13, for example. Can do.

  As described above, in the present embodiment, the load variation element 13 is a constant voltage circuit including constant voltage elements (for example, diodes D21, D22, Zener diode ZD2, etc.) connected in series to the light emitting diode LD1, or the light emitting diode LD1. Are composed of impedance circuits including resistance elements (for example, a resistor R12, a thermistor resistance Rh1, etc.) connected in series. The switch element Q2 is connected in parallel to the constant voltage circuit unit.

  As a result, when the switch element Q2 is turned on / off according to the optical communication signal, the load characteristic of the load circuit 12 including the light emitting diode LD1 is partially changed. The communication signal can be modulated faithfully. In the present embodiment, the modulation characteristics of the load current I1 flowing through the light emitting diode LD1 can be adjusted by using various circuit elements and their combinational circuits as the load variation element 13.

(Embodiment 4)
Embodiment 4 of the illumination light communication apparatus will be described with reference to FIG. The illumination light communication apparatus 10 of this embodiment differs from the illumination light communication apparatus 10 described in Embodiments 1 to 3 in the configuration of the load circuit 12. As shown in FIG. 5A, the illumination light communication device 10 of this embodiment includes a series circuit 4a in which a plurality of light emitting diodes LD1 are connected in series, and a series circuit in which a plurality of light emitting diodes LD2 are connected in series. 4b. Here, the load circuit 12 is composed of two series circuits 4a and 4b connected to both ends of the smoothing capacitor C11 via the load variation element 13. In this circuit, the switch element Q2 is connected in parallel with the load fluctuation element 13, and the switch element Q2 is turned on / off according to the optical communication signal, so that the light emitting diodes LD1, LD2 are the same as in the first to third embodiments. Modulation is applied to the current flowing through

  In the circuit of FIG. 5A, two sets of circuits in which a plurality of light emitting diodes are connected in series are connected in parallel between both ends of the smoothing capacitor C11, but each circuit is composed of one light emitting diode. There may be any number. Two series circuits of light emitting diodes are connected in parallel. However, the number of series circuits of light emitting diodes is not limited to two, and the number can be arbitrarily set.

  Further, in the circuit of FIG. 5A, both the series circuit 4a of the light emitting diode LD1 and the series circuit 4b of the light emitting diode LD2 are connected to the load variation element 13, but the circuit configuration is not limited to this. For example, as shown in FIG. 5B, the load fluctuation element 13 is not interposed in the series circuit 4a of the light emitting diode LD1, and only the series circuit 4b of the light emitting diode LD2 is connected between both ends of the smoothing capacitor C11 via the load fluctuation element 13. It may be connected to. A switch element Q2 is connected in parallel to the load fluctuation element 13, and the switch element Q2 is turned on / off in accordance with the optical communication signal S1, thereby modulating the current flowing through the light emitting diode LD2. It should be noted that a suitable number of light emitting diodes interposing the load fluctuation element 13 and light emitting diodes not interposing the load fluctuation element 13 may be connected in accordance with conditions such as the modulation level applied to the load current.

  In the circuit of FIG. 5 (c), four circuit blocks in which a series circuit of two light emitting diodes LD1 and a series circuit of two light emitting diodes LD2 are connected in parallel between both ends of the smoothing capacitor C1 are connected in series. By connecting, a ladder-like circuit is configured. A load variation element 13 is connected in series with the light emitting diode LD2 constituting the low side circuit block, and a switch element Q2 is connected between both ends of the load variation element 13. Here, when the switch element Q2 is turned on / off according to the optical communication signal S1, whether or not the load variation element 13 (for example, formed of a resistor) is added to the load circuit 12 is switched. Modulation can be applied to the current flowing through LD1 and LD2.

  As described above, also in the illumination light communication device 10 of the present embodiment, whether or not the load variation element 13 is added to the load circuit 12 by the switch element Q2 being turned on / off according to the optical communication signal. Can be switched. Therefore, as in the first to third embodiments, the load characteristics of the load circuit 12 partially change according to the optical communication signal, so that the load current flowing through the light emitting diode can be modulated faithfully to the waveform of the optical communication signal. . In addition, since the modulation level applied to the load current can be adjusted by changing the configuration of the light emitting diode that is the load of the apparatus, the configuration of the light emitting diode may be selected according to the desired modulation level.

  5B and 5C, a plurality of light emitting diode series circuits (load circuits) are connected in parallel between the outputs of the constant current source 11, and a plurality of load variation elements 13 and switch elements Q2 are provided. Are provided in at least one of the load circuits.

  Thus, since the load variation element 13 and the switch element Q2 are provided in at least one of the plurality of load circuits, the load characteristics of the load circuit in which the load variation element 13 and the switch element Q2 are provided are changed. As a result, the load characteristics of the load circuit can be modulated as a whole.

(Embodiment 5)
Embodiment 5 of the illumination light communication apparatus will be described with reference to FIG. The illumination light communication apparatus 10 of this embodiment differs from the illumination light communication apparatus 10 described in Embodiments 1 to 4 in the configuration of the load circuit. In addition, the same code | symbol is attached | subjected to the component which is common in Embodiment 1-4, and the description is abbreviate | omitted.

  As shown in the circuit diagram of FIG. 6, the illumination light communication device 10 includes a constant current source 11 and a smoothing capacitor C <b> 11 connected between both ends of the constant current source 11. Between the both ends of the smoothing capacitor C11, a series circuit of a plurality of light emitting diodes LD1 and a load fluctuation element 13a, a series circuit of a plurality of light emitting diodes LD2 and a load fluctuation element 13b, and a plurality of light emitting diodes LD3 and a load fluctuation element 13c are provided. A series circuit is connected in parallel. Here, a load circuit is configured by the series circuit 4a of the plurality of light emitting diodes LD1, the series circuit 4b of the plurality of light emitting diodes LD2, and the series circuit 4c of the plurality of light emitting diodes LD3. And switch element Q2a, Q2b, Q2c is connected in parallel with each of the load fluctuation elements 13a, 13b, 13c. The switch elements Q2a, Q2b, and Q2c are switched on / off by optical communication signals S1, S2, and S3 input from the corresponding signal generation circuits 14A, 14B, and 14C, respectively.

  Here, when a red light emitting diode is used for the light emitting diode LD1, a green light emitting diode is used for the light emitting diode LD2, and a blue light emitting diode is used for the light emitting diode LD3, the corresponding switch elements Q2a, Q2b, Q2c are individually provided. The output of each color light emitting diode is modulated by being turned on and off by the optical communication signals S1, S2, and S3. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference. The amount of information that can be transmitted by communication can be tripled.

  As described above, in the illumination light communication apparatus 10 of the present embodiment, a plurality of load circuits (series circuits 4a, 4b, 4c) are connected in parallel between the outputs of the constant current source 11. The plurality of load circuits (series circuits 4a, 4b, 4c) are configured by light emitting diodes (light emitting diodes LD1, LD2, LD3) having different emission colors for each load circuit, and switch elements Q2a, Q2b and Q2c are provided.

  Accordingly, whether or not the corresponding load variation element 13 is added to the load circuit can be switched by the switch elements Q2a, Q2b, and Q2c. Therefore, the load characteristics can be modulated for each light emitting diode having different emission colors. The output of the light emitting diode can be modulated in accordance with the optical communication signal.

  Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference, and therefore, when the light emitting diode emits a single color. In comparison, the amount of information that can be transmitted by optical communication can be increased.

(Embodiment 6)
Embodiment 6 of the illumination light communication apparatus will be described with reference to FIGS. The illumination light communication apparatus 10 of this embodiment differs from the illumination light communication apparatus 10 described in Embodiments 1 to 5 in the configuration of the load circuit. In addition, the same code | symbol is attached | subjected to the component which is common in Embodiments 1-5, and the description is abbreviate | omitted.

  The illumination light communication device 10 includes a constant current source 11 and a smoothing capacitor C11 connected between both ends of the constant current source 11, as shown in the circuit diagram of FIG. Between both ends of the smoothing capacitor C11, a series circuit 4 of a plurality of (for example, eight in this embodiment) light emitting diodes LD1 to LD8 is connected, and a switch element Q2 is connected in parallel with the light emitting diode LD8. Here, a load circuit is constituted by a series circuit 4 of light emitting diodes LD1 to LD8 connected in parallel with the smoothing capacitor C11. In addition, the load variation element 13 is configured by the light emitting diode LD8 that forms part of the load circuit 4 with the switch element Q2 connected in parallel.

  FIG. 7B shows a circuit obtained by modeling the circuit of FIG. 7A for simulation, and elements corresponding to the circuit components of FIG. 7A are given the same reference numerals. In this simulation circuit, the light emitting diodes LD1 to LD8 are equivalently replaced with a simulation device in which the characteristics of the light emitting diode are modeled in advance.

  FIG. 7C shows the result of simulating the load current I1 using the circuit of FIG. 7B. The load current I1 when the optical communication signal S1 is stopped is set to about 500 mA of direct current.

  In a state where a 10 kHz rectangular wave signal is input to the switch element Q2 as the optical communication signal S1, whether or not the light emitting diode LD8 is removed from the load circuit 12 is switched by turning on / off the switch element Q2. Modulation is applied to the waveform of the load current I1. The load current I1 is about 700 mA when the switch element Q2 is turned on, and about 300 mA when the switch element Q2 is turned off. A modulation waveform faithful to the waveform of the optical communication signal S1 is obtained, and the average current is an average when no modulation is performed. It keeps approximately the same value as the current of about 500 mA.

  By the way, in this embodiment, the series circuit of the light emitting diodes LD1 to LD8 is connected between both ends of the smoothing capacitor C11. However, the present invention is not limited to the above circuit, and the circuit shown in FIG. Good. In this circuit, a series circuit 4a composed of a plurality of light emitting diodes LD1 and a series circuit 4b composed of a plurality of light emitting diodes LD2 are connected in parallel between both ends of the smoothing capacitor C11. The switch element Q2 is connected in parallel with a part (for example, one) of the light emitting diodes LD2 constituting the series circuit 4b. In this case, among the plurality of light emitting diodes LD2 constituting the series circuit 4b, the load variation element 13 is configured by the light emitting diode LD2 in which the switch element Q2 is connected in parallel. In the circuit of FIG. 8A, two series circuits of a plurality of light emitting diodes are connected in parallel between both ends of the smoothing capacitor C11. However, the number of series circuits of the light emitting diodes connected in parallel is limited to two. Any number of series circuits may be connected in parallel.

  Further, as shown in FIG. 8B, four circuit blocks in which a series circuit of two light emitting diodes LD1 and a series circuit of two light emitting diodes LD1 are connected in parallel between both ends of the smoothing capacitor C11 are connected in series. A ladder-like circuit may be configured by connecting to the circuit. In this circuit, a switch element Q2 is connected in parallel with a part of the light emitting diodes LD1 (for example, one light emitting diode LD1 belonging to the right column). When the switch element Q2 is turned on / off in response to the optical communication signal S1, the load characteristic of the load circuit is modulated, thereby modulating the load current.

  As described above, in the illumination light communication device 10 of this embodiment, the load circuit includes a plurality of light emitting diodes connected in series, and the switch element Q2 is connected in parallel to a part of the plurality of light emitting diodes. Yes.

  As a result, the light emitting diode itself connected in parallel with the switch element Q2 becomes the load fluctuation element 13, and the load current of the light emitting diode is faithfully modulated with the waveform of the optical communication signal without newly adding the load fluctuation element 13. Can do.

(Embodiment 7)
Embodiment 7 of the illumination light communication apparatus will be described with reference to FIG. In the circuit of FIG. 6 described in the fifth embodiment, a plurality of series circuits of light emitting diodes and load variation elements are connected in parallel between both ends of the smoothing capacitor C11, and a switch element is disposed in parallel with the load variation elements of each series circuit. It is connected. On the other hand, in this embodiment, as shown in the circuit diagram of FIG. 9, between the both ends of the smoothing capacitor C11, a series circuit 4a of a plurality of light emitting diodes LD1, a series circuit 4b of a plurality of light emitting diodes LD2, and a plurality of light emitting devices. A series circuit 4c of the diode LD3 is connected in parallel. That is, a plurality of load circuits (consisting of series circuits 4a, 4b, 4c) are connected in parallel between both ends of the smoothing capacitor C11. A red light emitting diode is used for the light emitting diode LD1, a green light emitting diode is used for the light emitting diode LD2, a blue light emitting diode is used for the light emitting diode LD3, and light emitting diodes having different emission colors are used for each load circuit. To do.

  A switch element Q2a that is turned on / off in response to the optical communication signal S1 is connected to a part (for example, one light emitting diode LD1) of the plurality of light emitting diodes LD1 constituting the series circuit 4a. When the switch element Q2a is turned on, both ends of the light emitting diode LD1 to which the switch element Q2a is connected in parallel are short-circuited, so that the load characteristic of the load circuit (series circuit 4a) is partially dependent on the on / off of the switch element Q2a. To change.

  Also, a switch element Q2b that is turned on / off in response to the optical communication signal S2 is connected to a part (for example, one light-emitting diode LD2) of the plurality of light-emitting diodes LD2 constituting the series circuit 4b. When the switch element Q2b is turned on, both ends of the light emitting diode LD2 to which the switch element Q2b is connected in parallel are short-circuited, so that the load characteristic of the load circuit (series circuit 4b) is partially dependent on the on / off of the switch element Q2b. To change.

  Also, a switch element Q2c that is turned on / off in response to the optical communication signal S3 is connected to a part (for example, one light-emitting diode LD3) of the plurality of light-emitting diodes LD3 constituting the series circuit 4c. When the switch element Q2c is turned on, both ends of the light emitting diode LD3 to which the switch element Q2c is connected in parallel are short-circuited, so that the load characteristic of the load circuit (series circuit 4c) is partially dependent on the on / off of the switch element Q2c. To change.

  As described above, in this embodiment, the load circuit includes a plurality of light emitting diodes connected in series, and a switch element is connected in parallel to a part of the plurality of light emitting diodes. That is, the load variation element is configured by a light emitting diode in which switch elements are connected in parallel.

  As a result, when the switch element is turned on / off according to the optical communication signal, the load characteristic of the load circuit is partially modulated. Therefore, the load current is modulated according to the optical communication signal. Optical communication is possible without adding a load fluctuation element.

  Further, in the present embodiment, a plurality of load circuits (comprising series circuits 4a, 4b, 4c) are connected in parallel between the outputs of the constant current source 11, and each of the load circuits includes a plurality of the light emitting diodes connected in series. I have. The light emission colors of the light emitting diodes are different for each load circuit, and a switch element is connected in parallel with a part of the plurality of light emitting diodes in each load circuit.

  As a result, when the switch element provided in each load circuit is turned on / off, the load characteristic of each load circuit is modulated, so that the output of each color light emitting diode can be modulated. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference. The amount of information that can be transmitted by communication can be tripled.

(Embodiment 8)
Embodiment 8 of the illumination light communication apparatus will be described with reference to FIGS. In the circuit of FIG. 8 described in the sixth embodiment, a series circuit 4a of a plurality of light emitting diodes LD1 and a series circuit 4b of a plurality of light emitting diodes LD2 are connected between both ends of the smoothing capacitor C11. A switch element Q2 is connected in parallel to a part of the light emitting diode LD2 (one light emitting diode LD2) constituting one series circuit 4b. On the other hand, in this embodiment, as shown in the circuit diagram of FIG. 10, a series circuit 4a of a plurality of light emitting diodes LD1 is connected between both ends of the smoothing capacitor C11. A series circuit 4b of a plurality of light emitting diodes LD2 is connected between both ends of the smoothing capacitor C11 via a switch element Q2 that is turned on / off in response to the optical communication signal S1. When the switch element Q2 is turned on according to the optical communication signal, the series circuit 4a of the light emitting diode LD1 and the series circuit 4b of the light emitting diode LD2 are connected in parallel between both ends of the smoothing capacitor C11. On the other hand, when the switch element Q2 is turned off according to the optical communication signal, only the series circuit 4a of the light emitting diode LD1 is connected between both ends of the smoothing capacitor C11. In order to suppress the occurrence of overvoltage, it is necessary to avoid a no-load state in which all loads (light emitting diodes LD1 and LD2) are disconnected from the constant current source 11 at the same time. For this purpose, it is necessary to leave a load (light emitting diode) that receives a current supply from the constant current source 11 even when the light emitting diode LD2 is disconnected from the constant current source 11 by the switch element Q2. In the present embodiment, since the plurality of light emitting diodes LD1 are connected to the constant current source 11 without passing through the switch element Q2, a load current is always supplied to the light emitting diode LD1, and a no-load state occurs. The generation of overvoltage can be suppressed.

  FIG. 11A shows a circuit obtained by modeling the circuit of FIG. 10 for simulation, and elements corresponding to the circuit components of FIG. 10 are denoted by the same reference numerals. In this simulation circuit, the light emitting diodes LD1 and LD2 are equivalently replaced with a simulation device that models the characteristics of the light emitting diodes in advance.

  FIG. 11B shows the result of simulating the load current I1 using the circuit of FIG. 11A, and the load current I1 (the current flowing in the series circuit 4a and the current flowing in the series circuit 4a) when the optical communication signal S1 is stopped. The combined current with the current flowing through the series circuit 4b is set to about 1A of direct current. When the optical communication signal S1 composed of a 10 kHz rectangular wave signal is input to the switch element Q2, and the circuit 4b of the light emitting diode LD2 is turned on / off by turning on / off the switch element Q2, the waveform of the load current I1 is When the element Q2 is turned on, a rectangular wave of about 1.3 A is obtained, and when the switch element Q2 is turned off, a rectangular wave of about 0.7 A is obtained, and a modulation waveform faithful to the optical communication signal S1 is obtained. Further, the average current of the load current I1 is maintained at substantially the same value as the current value (about 1 A) in a state where the optical communication signal S1 is stopped.

  As described above, in the present embodiment, a plurality of load circuits including light emitting diodes are connected in parallel between the outputs of the constant current source 11, and the switch element includes one to a plurality of load circuits excluding at least one of the plurality of load circuits. It is provided in the load circuit.

  As a result, since the load variation element is configured by the load circuit to which the switch element is connected, it is possible to faithfully modulate the load current of the light emitting diode with the waveform of the optical communication signal without adding a new load variation element. it can. In addition, since the switch element is not provided in at least one of the plurality of load circuits, even if all the switch elements are turned off at the same time, the load element is not in a no-load state.

  By the way, every other connection point of the light emitting diodes LD1 and LD2 in the series circuits 4a and 4b is connected to each other, whereby a ladder-like circuit as shown in FIG. . In this circuit, when the switch element Q2 is turned on / off in response to the optical communication signal S1, a part of the light emitting diode LD2 is intermittently connected, so that no load is caused.

  In the circuit of FIG. 12B, a series circuit of a plurality of light emitting diodes LD1 and a switch element Q2a, a series circuit of a plurality of light emitting diodes LD2 and a switch element Q2b, and a plurality of light emitting diodes are provided between both ends of the smoothing capacitor C11. A series circuit of the LD 3 and the switch element Q2c is connected in parallel. Separate optical communication signals S1, S2, and S3 are input to the switch elements Q2a, Q2b, and Q2c, respectively, and ON / OFF is switched according to the corresponding optical communication signals S1, S2, and S3. Here, a red light emitting diode is used for the light emitting diode LD1, a green light emitting diode is used for the light emitting diode LD2, a blue light emitting diode is used for the light emitting diode LD3, and the currents flowing through them are modulated by the optical communication signals S1, S2, and S3. Has been. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference, so that the light can be compared with a single color light emitting diode. The amount of information that can be transmitted by communication can be tripled. Since all the switch elements Q2a, Q2b, and Q2c are turned off at the same time, no load is applied. Therefore, the optical communication signals S1, S2, and S3 are set so that the switch elements Q2a, Q2b, and Q2c are not turned off at the same time.

(Embodiment 9)
Embodiment 9 of the illumination light communication apparatus will be described with reference to FIGS. 13 and 14. Note that the circuit configuration of the illumination light communication apparatus 10 is the same as the circuit of FIG. 1A described in the first embodiment, and thus illustration and description thereof are omitted.

  The signal generation circuit 14 according to the first embodiment generates an optical communication signal S1 having a constant on-duty. On the other hand, the signal generation circuit 14 of this embodiment includes a duty adjustment unit 14b. The duty adjustment unit 14b generates a signal S11 in which the on-duty is changed while maintaining the frequency based on the optical communication signal S1 that is a rectangular wave signal having a constant on-duty input from the outside. The switch element Q <b> 2 is switched on / off by a signal S <b> 11 input from the signal generation circuit 14 and switches whether to add the load variation element 13 to the load circuit 12. Therefore, the waveform of the load current I1 flowing through the load circuit 12 is modulated according to the signal S11 generated based on the optical communication signal S1.

  FIG. 13 is a waveform diagram of the signal S11 and the load current I1 output from the signal generation circuit 14. FIG. 13A shows an on-duty of the optical communication signal S1 of about 50%, and FIG. 13B shows an on-duty. FIG. 7C is a waveform diagram when the on-duty is about 25%. If the load current I1 when the on-duty is 50% has a waveform as shown in FIG. 13 (a), the waveform of the load current I1 is as shown in FIG. 13 (b) when the on-duty is increased to 75%. The waveform is such that the peak value is suppressed and the bottom value is lowered, and the modulation width is expanded. Further, when the on-duty is narrowed to 25%, the waveform of the load current I1 is increased in both the peak value and the bottom value as shown in FIG. 13C, and the modulation width is reduced.

  FIG. 14A is a simulation circuit modeled for simulating the circuit operation of the present embodiment. As the load circuit 12, the circuit of FIG. 7A described in the sixth embodiment is used. ing. That is, the load circuit 12 includes light emitting diodes LD1 to LD8 connected in series between both ends of the smoothing capacitor C11, and the switch element Q2 is connected in parallel with the light emitting diode LD8. The load variation element 13 is constituted by the light emitting diode LD8 to which the switch element Q2 is connected in parallel. In this simulation circuit, the light-emitting diodes LD1 to LD8 are replaced with a simulation device that models characteristics of the light-emitting diodes in advance.

  FIGS. 15A to 15C show results of simulation using the circuit of FIG.

  FIG. 15A is a waveform diagram of the current I1 flowing through the load circuit 4 when the frequency of the signal S11 output from the signal generation circuit 14 is 10 kHz and the on-duty is 50%. The peak value of the current I1 is about 700 mA, the bottom value is about 300 mA, the modulation width is about 400 mA, and the average value is about 500 mA.

  FIG. 15B is a waveform diagram of the current I1 when the frequency of the signal S11 output from the signal generation circuit 14 is 10 kHz and the on-duty is 75%. The peak value of the current I1 is about 630 mA, the bottom value is about 120 mA, the modulation width is about 510 mA, and the average value is about 500 mA.

  FIG. 15C is a waveform diagram of the current I1 when the frequency of the signal S11 output from the signal generation circuit 14 is 10 kHz and the on-duty is 25%. The peak value of the current I1 is about 710 mA, the bottom value is about 430 mA, the modulation width is about 280 mA, and the average value is about 500 mA.

  From these results, when the signal generation circuit 14 generates the signal S11 with the on-duty changed while maintaining the frequency of the optical communication signal S1, and the load current I1 is modulated in accordance with the signal S11, the on-duty It was found that the modulation width can be adjusted by the value.

  As described above, the illumination optical communication device 10 of the present embodiment includes the duty adjustment unit 14b that changes the on / off duty ratio of the optical communication signal.

  As a result, the switch element is turned on / off by the signal whose duty ratio is changed by the duty adjustment unit 14b, whereby the load characteristic of the load circuit can be modulated. Moreover. By changing the on-duty, the modulation width of the load current flowing in the load circuit can be adjusted to a desired value.

(Embodiment 10)
Embodiment 10 of the illumination light communication apparatus will be described with reference to FIG. Although the illumination light communication apparatus 10 according to the first to ninth embodiments described above uses the light source of the light emitting diode as the constant current source 11, a specific circuit of the constant current source 11 will be described in the present embodiment.

  FIG. 16A shows a circuit diagram of the illumination light communication apparatus 10. In the present embodiment, the constant current source 11 is configured by a DC-DC converter 2 (converter unit) that receives the DC power source 1, a current detection resistor 5 (current detection unit), an error amplifier A1 (differential abdominal unit), and the like. A feedback circuit 15 and an output control unit 7 (control unit) are provided.

  The current detection resistor 5 generates a voltage drop according to the load current flowing through the load circuit 4. The error amplifier A1 compares and amplifies the voltage drop generated in the current detection resistor 5 and the reference voltage E1. The output of the error amplifier A1 is sent to the output control unit 7. The output control unit 7 controls the output of the DC-DC converter 2 so that the voltage drop generated in the current detection resistor 5 matches the reference voltage E1 (that is, the output of the error amplifier A1 becomes small).

  In this circuit, a smoothing capacitor C11 is connected to the output of the DC-DC converter 2. A load circuit 4 composed of a series circuit of a plurality of light emitting diodes LD1 is connected between both ends of the smoothing capacitor C11. Here, whether or not the load variation element 13 is added to the load circuit 12 is switched by turning on / off the switch element Q2 in accordance with the optical communication signal S1, and thereby the load characteristic of the load circuit 4 is switched. Is partially changed.

  Various systems can be adopted for the DC-DC converter 2, and in the circuit shown in FIG. 16B, the DC-DC converter 2 is constituted by a flyback converter including a switching element Q1, an output transformer T1, and a diode D20. Has been.

  In the circuit shown in FIG. 16C, the DC-DC converter 2 is configured by a buck converter including a switching element Q1, a choke coil L21, and a diode D21.

  In the circuit shown in FIG. 16D, the DC-DC converter 2 is formed of an inverse buck converter circuit including a switching element Q1, a choke coil L21, and a diode D22. That is, the smoothing capacitor C11 is connected in parallel with the load circuit 4 formed of a series circuit of the light emitting diode LD1, and the current detection resistor 5 for detecting the load current flowing through the light emitting diode LD1 is provided on the source side of the switching element Q1. ing. The error amplifier A1 amplifies the difference between the voltage drop generated in the current detection resistor 5 by the source current of the switching element Q1 and the reference voltage E1, and the current flowing through the light emitting diode LD1 by the feedback circuit 15 and the output control unit 7 is amplified. Controlled to a constant current.

  In the circuits shown in FIGS. 16A to 16D, a constant current is output from the constant current source 11, and the switch element Q2 is turned on / off according to the optical communication signal S1, so that the load fluctuation element 13 is changed. Whether or not to be added to the load circuit 4 is switched. As a result, the load characteristic of the load circuit 4 is partially modulated, so that the load current is modulated according to the optical communication signal, and the waveform of the load current can be faithfully modulated to the optical communication signal S1. it can.

  Incidentally, in the specific circuit of the constant current source 11 described in the present embodiment (see FIGS. 16A to 16D), it is also preferable to add a phase compensation element to the constant current feedback system. The current source 11 can be realized. FIG. 17 shows a circuit in which a phase compensation element is added to the circuit of FIG. 16A, and an integrating element comprising a resistor R21 and a capacitor C21 connected between the output terminal and the inverting input terminal of the error amplifier A1. Including a phase compensation circuit 6b. The phase compensation circuit 6b increases the gain in the low frequency region, suppresses the gain in the high frequency region, and ensures the stability of the feedback transfer circuit.

  The method for performing modulation for optical communication by varying the load characteristics described in each of the above embodiments does not depend on the responsiveness of the constant current feedback system, and is configured with an error amplifier A1 or the like. The constant current feedback circuit has a function of controlling the average value of the load current substantially constant during modulation and non-modulation. Here, it is expected that the responsiveness for obtaining a modulation waveform that is modulated faithfully to the optical communication signal S1 is determined by the wiring inductance between the smoothing capacitor C11 connected in parallel to the light emitting diode LD1 and the light emitting diode LD1. Is done. Therefore, high-speed communication can be expected by performing wiring in consideration of wiring inductance. As a specific configuration of the DC-DC converter 2, various circuits as shown in FIGS. 16B to 16D can be applied.

  As described above, in the present embodiment, the constant current source 11 includes a converter unit (DC-DC converter 2) that generates a DC output, and a current detection unit that generates a voltage drop corresponding to the load current flowing in the load circuit ( A current detection resistor 5), a difference amplifying unit (error amplifier A1) for amplifying a difference between a voltage drop generated in the current detecting unit and a predetermined reference voltage, and an average value of the load current according to the output of the difference amplifying unit. A constant current feedback system including a control unit (output control unit 7) for controlling the output of the converter unit so as to be substantially constant is provided.

  As a result, the control unit feeds back the load current and controls the output of the converter unit, whereby the function of controlling the average value of the load current at the time of modulation and the time of non-modulation can be made substantially constant.

  Further, in the present embodiment, a phase compensation circuit 6b that includes an integration element and adjusts the phase of the output of the differential amplifier (error amplifier A1) is provided in the constant current feedback system.

  As described above, in the present embodiment, by providing the phase compensation circuit 6b, the gain in the low frequency region is increased, the gain in the high frequency region is suppressed, and the stability of the loop transfer function of the feedback system can be ensured. .

(Embodiment 11)
Embodiment 11 of the illumination light communication apparatus will be described with reference to FIG. In each of the above-described embodiments, the constant current source 11, the smoothing capacitor C11, and the load circuit 4 (consisting of the light emitting diode LD1) connected between both ends of the smoothing capacitor C11 is generally a lighting fixture having a light emitting diode as a load. It can be said that this is a basic circuit. Therefore, the load variation element 13 that partially changes the load characteristic of the load circuit by being added to the load circuit, and the load variation element 13 becomes the load circuit by being switched on / off according to the optical communication signal S1. If an illumination light communication block composed of the switch element Q2 for switching whether or not to be added can be added later to an existing lighting fixture, the optical communication function can be easily made to an existing general lighting fixture. It can be added and the spread of optical communication functions can be expected.

  FIG. 18 is a circuit diagram of the illumination light communication apparatus 10 according to the present embodiment. The illumination light communication apparatus 10 includes an existing illumination apparatus 100 and a communication unit 30 that can be connected to the illumination apparatus 100 later.

  The luminaire 100 includes a constant current source 11, a smoothing capacitor C11 connected to the output terminal of the constant current source 11, and a load circuit 4 connected between both ends of the smoothing capacitor C11. The light emitting diodes LD1 are connected in series.

  The communication unit 30 includes a signal generation circuit 14 that generates an optical communication signal S1, a load fluctuation element 13 that is added to the load circuit 4 of the lighting fixture 100 to partially change the load characteristics of the load circuit 4, and a light A switch element Q2 that switches whether to add the load variation element 13 to the load circuit 4 by being turned on / off according to the communication signal S1 is provided. The communication unit 30 includes a connector CN2 that is detachably connected to the connector CN1 included in the lighting fixture 100. When the connector CN2 is connected to the connector CN1, the load variation element 13 is electrically connected to the load circuit 4. It has become so.

  Thus, by connecting the connector CN2 of the communication unit 30 to the connector CN1 of the existing lighting fixture 100, an optical communication function can be easily added later to the existing lighting fixture 100 that does not have an optical communication function. can do.

  In addition, in the communication unit 30 of this embodiment, as shown to Fig.19 (a), the insulation part 16 which electrically isolates between the signal generation circuit 14 which generate | occur | produces optical communication signal S1, and switch element Q2 is provided. It is also preferable.

  19 (b) and 19 (c) show specific examples of the insulating portion 16. In the circuit of FIG. 19 (b), the insulating portion 16 is composed of the photocoupler PC11, and in the circuit of FIG. 19 (c), the insulating portion 16 is insulated. It is composed of a transformer T21. In the circuits of FIGS. 19B and 19C, the switch element Q2 is driven from the photocoupler PC11 or the insulating transformer T21 constituting the insulating portion 16 via the buffer IC4.

  As described above, the present embodiment includes the communication unit 30 in which the signal generation circuit 14, the load variation element 13, and the switch element Q2 necessary for realizing the illumination light communication function are housed in the same case 30a. Yes. The communication unit 30 is connected to the load circuit 4 via connection mechanical parts (connectors CN1, CN2).

  Thereby, the communication unit 30 can be connected to the existing lighting fixture 100 by retrofitting, and the function of illumination light communication can be easily added to the existing lighting fixture 100.

  The communication unit 30 is provided with an insulating portion 16 that electrically insulates between the signal generating circuit 14 and the switch element Q2.

  As a result, even when the communication unit 30 is connected to the lighting fixture 100 via the connectors CN1 and CN2, the signal generation circuit 14 is electrically insulated from the lighting fixture 100. Thus, an operation of converting a signal input from an external control system into an optical communication signal S1 is facilitated.

Embodiment 12
Embodiment 12 of the illumination light communication apparatus will be described with reference to FIG. The communication unit 30 described in the eleventh embodiment is connected to one lighting fixture 100 and provides the lighting fixture 100 with an optical communication function. In contrast, in the present embodiment, the communication unit can be connected to a plurality of lighting fixtures, and an optical communication function can be imparted to the plurality of lighting fixtures.

  FIG. 20A is a circuit diagram of the illumination light communication apparatus 10 according to the present embodiment. The illumination light communication apparatus 10 includes three existing illumination fixtures 100A, 100B, and 100C and illumination fixtures 100A, 100B, and 100C. It is comprised with the communication unit 30 connected.

  The lighting fixtures 100A, 100B, and 100C have the same configuration, and include a constant current source 11, a smoothing capacitor C11 connected between both ends of the constant current source 11, and a plurality of series connected between both ends of the smoothing capacitor C11. It is comprised with the load circuit 4 which consists of light emitting diode LD1.

  The communication unit 30 receives the optical communication signal S1 from the signal generation circuit 14 and modulates the load characteristics of a plurality of lighting fixtures to perform optical communication, and includes a plurality of load variation elements and switch elements. It is configured as a multi-channel communication unit with a system. The communication unit 30 includes, for example, three systems of load variation elements 13a, 13b, and 13c, switch elements Q2a, Q2b, and Q2c, insulating portions 16a, 16b, and 16c, connectors CN2a, CN2b, and CN2c, and the signal generation circuit 14 being the same. It is unitized by holding it in the case 30a. The load variation elements 13a, 13b, and 13c are respectively added to the load circuit 4 of the lighting fixture, thereby partially changing the characteristics of the load circuit 4. The connectors CN2a, CN2b, CN2c are detachably connected to the connector CN1 of the lighting fixture, respectively, and connect the corresponding load variation elements 13a, 13b, 13c to the load circuit 4 of the lighting fixture. The signal generation circuit 14 generates a binary optical communication signal S1. The switch elements Q2a, Q2b, and Q2c are turned on / off in response to the optical communication signal S1 from the signal generation circuit 14, respectively, to switch whether or not the corresponding load variation elements 13a, 13b, and 13c are added to the load circuit 4. . The insulating portions 16a, 16b, and 16c electrically insulate the signal generating circuit 14 and the corresponding switch elements Q2a, Q2b, and Q2c, respectively, as shown in FIGS. 19B and 19C, for example. It is comprised with such a circuit.

  As described above, the present embodiment includes the communication unit 30 in which the signal generation circuit, the load variation element, and the switch element necessary for realizing the illumination light communication function are housed in the same case 30a. This communication unit 30 is configured to be connected to the load circuit 4 of the lighting fixture via connection mechanism parts (connectors CN1, CN2a to CN2c).

  Thereby, the communication unit 30 can be connected to the existing lighting fixture 100 by retrofitting, and the function of illumination light communication can be easily added to the existing lighting fixture 100.

  In addition, in the present embodiment, a plurality of load variation elements and switch elements are provided so that the optical communication signal S1 from the signal generation circuit 14 can be output to a plurality of lighting fixtures. Modulation can be applied to the light output of the base luminaire.

  The switch elements Q2a, Q2b, Q2c of a plurality of systems are connected to the signal generation circuit 14 through corresponding insulating portions 16a, 16b, 16c, respectively. Therefore, a plurality of lighting fixtures connected to the communication unit 30 are electrically insulated, and mutual interference between the lighting fixtures can be suppressed.

  In the circuit of FIG. 20A, the optical communication signal S1 output from the signal generation circuit 14 is output to a plurality of lighting fixtures. However, as shown in FIG. A plurality of types (for example, three types) of optical communication signals S1, S2, and S3 may be generated, and the respective optical communication signals S1, S2, and S3 may be output to separate lighting fixtures. In the circuit of FIG. 20B, optical communication signals S1, S2, and S3 are input to the switch elements Q2a, Q2b, and Q2c via the corresponding insulating portions 16a, 16b, and 16c, respectively.

  As described above, the signal generation circuit 14 that generates the optical communication signal generates a plurality of different types of optical communication signals (three types of optical communication signals S1, S2, and S3 in the present embodiment). An individual switch element (switch element Q2a, Q2b, Q2c) is provided for each type of optical communication signal, and an insulating part (insulating parts 16a, 16b, 16c) for electrically insulating a plurality of switch elements is provided. Is provided.

  Thereby, a plurality of types of optical communication signals can be output to separate lighting fixtures, and multi-channel optical communication can be performed with one communication unit 30.

(Embodiment 13)
Embodiment 13 of the illumination light communication apparatus will be described with reference to FIGS. 21 and 22.

  FIG. 21 is a circuit diagram of the illumination light communication apparatus 10 of the present embodiment. In this embodiment, a carrier wave generation unit 32, a modulation unit 33, an insulation transformer T1, a control power supply unit 34, and a demodulation unit 35 are added to the communication unit 30 described in the eleventh embodiment.

  The carrier wave generator 32 forms an astable multivibrator with the timer IC 31, resistors R11 and R12, and the capacitor C10, and oscillates at a sufficiently high frequency (for example, 1 MHz) with respect to the frequency of the optical communication signal S1. For example, LMC555 manufactured by National Semiconductor Co., Ltd. is used as the timer IC 31.

  The output signal of the timer IC 31 is input to the modulation unit 33 and input to one input terminal of the AND gate IC1. The optical communication signal S1 is input to the other input terminal of the AND gate IC1, and the logical sum of the optical communication signal S1 and the output signal of the timer IC 31 is input to the buffer IC2 and insulated through the coupling capacitor C11. The primary winding of the transformer T1 is excited.

  A high frequency voltage obtained by modulating the optical communication signal S1 with a carrier of 1 MHz, for example, is induced in the secondary winding of the isolation transformer T1, and a control power supply configured by a voltage doubler rectifier circuit including diodes D11 and D12 and capacitors C12 and C13. Rectification and smoothing are performed by the unit 34. The power supply of the buffer IC3 that drives the gate of the switch element Q2 is generated by the output voltage of the voltage doubler rectifier circuit.

  The voltage induced in the secondary winding of the insulating transformer T1 is input to the demodulator 35. In the demodulator 35, the voltage induced in the secondary winding of the insulating transformer T1 is divided by the resistors R13 and R14, and the carrier component is removed by the capacitor C14, thereby reproducing the optical communication signal S1. The demodulator 35 drives the gate of the switch element Q2 made of a MOSFET by supplying the reproduced optical communication signal S1 to the input of the buffer IC3.

  22A to 22E are waveform diagrams of the respective parts for explaining the above-described circuit operation. FIG. 22A is a diagram illustrating the optical communication signal S1 (for example, 10 kHz) output from the signal generation circuit 14. It is a waveform diagram. FIG. 22B is a waveform diagram of a carrier wave signal (for example, 1 MHz), FIG. 22C is an output waveform of the AND gate IC1 (modulation unit 33), and the carrier wave signal is modulated by the optical communication signal S1. FIG. 22D shows the output waveform of the control power supply unit 34, and the DC power source rectified and smoothed by the voltage doubler rectifier circuit is supplied to the buffer IC3. FIG. 22 (e) shows the output waveform of the buffer IC3 (the signal waveform demodulated by the demodulator 35), which is input to the gate terminal of the switch element Q2 made of a MOSFET.

  In the illumination light communication apparatus 10 of the present embodiment, the communication unit 30 includes a carrier wave generation unit 32, a modulation unit 33, an insulating transformer T1, and a demodulation unit 35. The carrier wave generation unit 32 generates a carrier wave set to a frequency sufficiently higher than the frequency of the optical communication signal S1 so that it can be separated from the optical communication signal S1. The modulation unit 33 modulates the optical communication signal S1 with a carrier wave. The insulating transformer T1 is connected between the modulation unit 33 and the switch element Q2. The demodulator 35 outputs a signal obtained by removing the carrier wave from the output of the isolation transformer T1 to the switch element Q2.

  As described above, since the carrier wave generating unit 32, the transformer driving unit 33, the control power source unit 34, and the demodulating unit 35 are provided, the insulation constituting the insulating unit 16 provided between the signal generating circuit 14 and the switch element Q2 is provided. A small transformer can be used as the transformer T1. Moreover, since it is easy to ensure the drive power of the switch element Q2, it is not necessary to secure a control power supply from the lighting fixture, and the highly independent communication unit 30 can be realized. In addition, an optical communication function can be easily added later to the existing lighting fixture 100 by integrally configuring components such as the load variation element 13 and the switch element Q2 as the communication unit 30. Needless to say, the configuration of the communication unit of the present embodiment may be applied to the multi-channel communication unit described in the twelfth embodiment.

(Embodiment 14)
The illumination light communication apparatus of Embodiment 14 is demonstrated based on FIGS. FIG. 23A is a circuit diagram of the illuminating light communication apparatus 10. The illuminating light communication apparatus 10 includes a DC-DC converter 2 (converter unit), a rectifier circuit 3, and a smoothing capacitor C1 (inputting the DC power supply 1). Smoothing circuit). The DC-DC converter 2 switches the direct current voltage from the direct current power source 1 with the switch element Q1, and the output is rectified and smoothed by the rectifier circuit 3 including the diode and the smoothing capacitor C1, so that the direct current of a predetermined voltage value is obtained. Converted to voltage. Between the outputs of the DC-DC converter, that is, between both ends of the smoothing capacitor C1, a plurality of (for example, eight) light emitting diodes LD1 to LD8 and a current detection resistor 5 (current detection unit) are connected in series. The voltage drop of the current detection resistor 5 is input to the inverting input terminal of the error amplifier A1 (difference amplifier). The error amplifier A1 compares the voltage drop of the current detection resistor 5 with the reference voltage E1 input to the non-inverting input terminal, and outputs a signal obtained by amplifying the difference to the output control unit 7 (control unit). The output control unit 7 controls the load current I1 by controlling on / off of the switch element Q1 based on the feedback signal input from the error amplifier A1. Note that a phase compensation circuit 6a including a resistor R1 and a capacitor C2 as integration elements is connected between the output terminal and the inverting input terminal of the error amplifier A1, and is determined by the error amplifier A1, the resistor R1, the capacitor C2, and the like. A current feedback circuit 6 is configured.

  In this circuit, a switch element Q2 (switch element) is connected in parallel with a part of the light-emitting diodes LD1 to LD8 connected in series, that is, one light-emitting diode LD8, and this switch element Q2 is inputted from the outside. Is turned on / off by the optical communication signal S1.

  FIG. 23B shows a simulation circuit for verifying the circuit operation. In this circuit, a step-down chopper circuit is used as the DC-DC converter 2. The switch element Q2 connected to the light emitting diode LD8 is turned on / off by a signal source 8 that outputs an oscillation signal of 10 kHz corresponding to an optical communication signal.

  FIGS. 24A and 24B show the results of simulating the load current I1 using the above simulation circuit. FIG. 24A shows the load current I1 when the signal source 8 is stopped, and the load current I1 is set to about 500 mA of direct current. FIG. 24B shows a load current I1 when a rectangular wave signal of 10 kHz is output from the signal source 8 and the current flowing through the light emitting diode LD8 is interrupted. In this case, the load current I1 is about 700 mA when the switch element Q2 is on, about 300 mA when the switch element Q2 is off, and the average current is about 500 mA. The light emitting diode LD8 to which the switch element Q2 is connected in parallel flows a rectangular wave current of 0 when the switch element Q2 is on and about 300 mA when the switch element Q2 is off.

  As described above, the switch element Q2 is connected in parallel with a part of the light-emitting diodes LD1 to LD8 connected in series, and the switch element Q2 is turned on / off according to the optical communication signal, so that a part of the light-emitting diodes is formed. The flowing current is interrupted. Therefore, the load current flowing through the light emitting diodes LD1 to LD8 is modulated according to the optical communication signal, and the illumination light output from the light emitting diodes LD1 to LD8 is modulated according to the optical communication signal. An optical communication signal that is an optical output from the illumination optical communication device 10 is received by a receiver 20 having a photo IC. The receiver 20 employs a method of receiving an optical communication signal by detecting a difference between an optical output on which the optical communication signal is not superimposed and an optical output on which the optical communication signal is superimposed. By adopting this method, even minute modulated light can be detected. Moreover, since the DC-DC converter 2 is controlled so that the average value of the load current I1 becomes substantially constant, power loss can be reduced. Here, a load variation element is constituted by the light emitting diode LD8 to which the switch element Q2 is connected in parallel.

  In the above simulation circuit, the switch element Q2 is connected in parallel with one of the eight lamps. However, the switch element Q2 is connected in parallel with two of the eight lamps, and the switch element Q2 is connected to the signal source 8. FIG. 25A shows the load current I1 when the power is intermittently turned on / off. From the simulation result of FIG. 25A, when the number of light emitting diodes intermittently switched by the switching element Q2 is increased (1 lamp → 2 lamps), the peak value of the load current I1 becomes high and the bottom value becomes small, and the light output It has been found that can be modulated more greatly. Also in this case, it was found that the average current can be the same value (500 mA) as in the unmodulated state. Note that the output light of the light emitting diode is modulated by turning on / off the switching element Q2 at a high frequency of about 10 kHz, but the human eye cannot recognize the high-frequency light modulation of about 10 kHz, and thus feels strange. There is nothing.

  Further, in the above simulation circuit, the on-duty of the switch element Q2 is set to 50%, but the simulation results when the on-duty is set to 75% are shown in FIGS. FIG. 25B shows the load current I1 when one light emitting diode is intermittently connected with the switching element Q2, and FIG. 25C shows the load current I1 when two light emitting diodes are intermittently connected with the switching element Q2. From this simulation result, when the on-duty of the switch element Q2 is made larger than 50%, the extinguishing period of one or a plurality of light emitting diodes to which the switch element Q2 is connected in parallel can be lengthened. Thereby, while suppressing the peak value of the load current I1 which is a rectangular wave current, the average current can be made the same value as the unmodulated state, and the peak current rating of the light emitting diode can be changed by changing the on-duty of the switch element Q2. Can be adjusted and the reception sensitivity can be adjusted.

  In the above simulation circuit, the number of light-emitting diodes LD1 is eight, but when twelve light-emitting diodes are connected in series and the switch element Q2 is connected in parallel with one to four of the light-emitting diodes. The simulation results are shown in FIG. FIG. 26A shows the load current I1 in a state where the signal source 8 is stopped (that is, the switch element Q2 is off), and the load current I1 is set to about 500 mA of direct current. 26B shows the load current I1 when one light emitting diode is interrupted, FIG. 26C shows the load current I1 when two lights are interrupted, and FIG. 26D shows the case where three lights are interrupted. FIG. 26E shows the load current I1 when four lamps are intermittent. In any case, the on-duty of the switch element Q2 is set to 50%. From this simulation result, it was confirmed that the greater the number of light emitting diodes that are intermittently connected to the switching element Q2, the greater the degree of modulation of the load current I1, but the average current of the load current I1 is kept constant. .

  As described above, in the present embodiment, among a plurality of light-emitting diodes connected in series, a switch element Q2 is connected in parallel with some of the light-emitting diodes, and this switch element Q2 is turned on / off according to an optical communication signal. I am letting. When the switch element Q2 is turned on, a part of the light emitting diodes to which the switch element Q2 is connected in parallel is short-circuited between both ends. At this time, the ON voltage of the light emitting diodes connected in series is reduced by the number of short-circuits, and a difference ΔV is generated between the output voltage of the DC-DC converter 2 (that is, the voltage across the smoothing capacitor C1). Therefore, the load current I1 flowing through the remaining light emitting diodes increases by a value determined by the difference ΔV between the operating resistance and the voltage. This increase is not due to the feedback system (constant current feedback circuit 6) via the error amplifier A1, so the load current I1 increases instantaneously and good followability to the optical communication signal is obtained. Further, the larger the number of light-emitting diodes that are short-circuited, the greater the increase in load current. On the other hand, while the switch element Q2 is off, the load current I1 is lower than when it is not modulated by the optical communication signal, but this current value is controlled by the constant current feedback circuit 6 so that the average current is not modulated. The current value determined to be the same value is controlled.

  In this illuminating light communication device, a part of a plurality of light emitting diodes LD1 to LD8 connected in series, which are used for lighting, is short-circuited intermittently according to the optical communication signal, and faithful to the optical communication signal. Modulation of the load current I1 can be performed. In addition, there is no loss that impairs circuit efficiency, and even when modulation by an optical communication signal is applied, the average value of the load current I1 does not change, so there is no risk of impairing the quality of illumination.

  As described above, this embodiment provides an illumination optical communication apparatus that can modulate output light faithfully in accordance with a high-frequency optical communication signal and has low power loss, while a circuit added for communication is simple. can do.

(Embodiment 15)
The illumination light communication apparatus of Embodiment 15 is demonstrated based on FIGS. FIG. 27 is a simulation circuit for verifying the circuit operation of this embodiment. In this circuit, a series circuit 4a of eight light emitting diodes LD11 to LD18 and a series circuit 4b of eight light emitting diodes LD21 to LD28 are connected between the outputs of the DC-DC converter 2 via a current detection resistor 5. Connected in parallel. In addition, a switch element Q2 that is turned on / off in response to an optical communication signal is connected in parallel with a part of the light emitting diodes LD21 to LD28 (for example, the light emitting diode LD28) constituting one series circuit 4b. Here, in the simulation circuit of FIG. 27, the switch element Q2 is turned on / off by the signal source 8 that outputs an oscillation signal of 10 kHz corresponding to the optical communication signal. Since the circuit configuration other than the load circuit composed of the light emitting diodes LD11 to LD18 and LD21 to LD28 is the same as that of the fourteenth embodiment, common components are denoted by the same reference numerals and description thereof is omitted.

  28A to 28C show the results of simulating the load currents I1 and I2 flowing through the series circuits 4a and 4b and the combined current I3 (= I1 + I2) using the above simulation circuit. FIG. 28A shows the currents I1 to I3 in a state where the signal source 8 is stopped, the load currents I1 and I2 are set to about 500 mA of direct current, and the combined current I3 is set to about 1 A of direct current. Yes.

  FIG. 28B shows a 10 kHz rectangular wave signal (on-duty is 50%) output from the signal source 8, and shows load currents I1, I2 and combined current I3 when one light emitting diode LD28 is intermittently connected. Show. Here, the load current I1 flowing through the series circuit 4a in which the light emitting diode is not intermittently connected by the switch element Q2 is not modulated by substantially direct current. On the other hand, the load current I2 flowing through the series circuit 4b in which the light emitting diode LD28 is intermittently connected by the switch element Q2 is modulated on the basis of the average current (about 500 mA). Thus, the combined current I3 that is the sum of the load currents I1 and I2 is modulated with reference to the average value (1A).

  In the above simulation circuit, one light-emitting diode LD28 is turned on / off by the switching element Q2, but the results of simulating currents I1 to I3 when two light-emitting diodes are intermittently connected by the switching element Q2 are shown in FIG. It is shown in 28 (c). From this result, it was confirmed that the modulation width can be increased by increasing the number of light emitting diodes intermittently connected by the switching element Q2. This is because when the switch element Q2 is turned on, both ends of a part of the light emitting diodes connected in parallel to the switch element Q2 are short-circuited. At this time, the ON voltage of the light emitting diodes connected in series is reduced by the number of short-circuits, and a difference ΔV is generated between the output voltage of the DC-DC converter 2 (that is, the voltage across the smoothing capacitor C1). Accordingly, the load current I1 flowing through the remaining light emitting diodes increases by a value determined by the difference ΔV between the operating resistance and the voltage described above. Since this increase is not due to the feedback system via the error amplifier A1, the load current I1 increases instantaneously, and good followability to the optical communication signal can be obtained. As the number of light-emitting diodes that are short-circuited increases, the increase in load current increases. On the other hand, while the switch element Q2 is off, the load current I1 is lower than when it is not modulated by the optical communication signal, but this current value is controlled by the constant current feedback circuit 6 so that the average current is not modulated. The current value determined to be the same value is controlled.

  By the way, the number of parallel connection of a series circuit of a plurality of light emitting diodes is not limited to two, but three or more may be connected in parallel. In the circuit shown in FIG. 29, a series circuit 4a in which eight light-emitting diodes LD11 to LD18, LD21 to LD28, and LD31 to LD38 are connected in series between outputs of the DC-DC converter 2 via a current detection resistor 5. , 4b, 4c are connected in parallel. A switch element Q2 that is turned on / off in response to an optical communication signal is connected in parallel with a part of the light emitting diodes LD31 to LD38 (for example, the light emitting diode LD38) constituting one series circuit 4c.

  FIGS. 30A to 30C show results of simulating the load currents I1, I2, and I3 flowing through the series circuits 4a, 4b, and 4c and the combined current I4 (= I1 + I2 + I3) using the above simulation circuit. Show. FIG. 30A shows currents I1 to I4 with the signal source 8 stopped, the load currents I1 to I3 are set to about 500 mA of direct current, and the combined current I4 is about 1.5A of direct current. Is set.

  FIG. 30B shows a 10 kHz rectangular wave signal (on-duty is 50%) output from the signal source 8 and shows the load currents I1 to I3 and the combined current I4 when one light emitting diode LD38 is intermittently connected. Show. Here, the load currents I1 and I2 flowing through the series circuits 4a and 4b in which the light emitting diodes are not interrupted by the switch element Q2 are not modulated by substantially direct current. On the other hand, the load current I3 flowing through the series circuit 4c in which the light emitting diode LD38 is intermittently connected by the switch element Q2 is modulated with reference to the average current (about 500 mA). Thus, the combined current I4, which is the sum of the load currents I1 to I3, is modulated with reference to the average value (1.5A).

  In the above simulation circuit, one light-emitting diode LD38 is turned on / off by the switching element Q2, but the currents I1 to I4 when the two light-emitting diodes LD37 and LD38 are intermittently connected by the switching element Q2 are simulated. A result is shown in FIG.30 (c). From this result, it was confirmed that the modulation width can be increased by increasing the number of light emitting diodes intermittently connected by the switching element Q2, as in the first embodiment.

(Embodiment 16)
The illumination light communication apparatus of Embodiment 16 is demonstrated based on FIG.31 and FIG.32. FIG. 31 is a simulation circuit for verifying the circuit operation of this embodiment. In this circuit, circuit blocks B1 to B4 in which a plurality of (for example, four sets) series circuits 4 of two light emitting diodes LD1 and LD2 are connected in parallel between the outputs of the DC-DC converter 2 via a current detection resistor 5. Four are connected in series. In this circuit, among the four series circuits 4 constituting the circuit block B4, the switch element Q2 is connected in parallel with a part of the light emitting diodes LD1 and LD2 of the series circuit 4, that is, the light emitting diode LD2. Yes. The switch element Q2 is turned on / off according to the optical communication signal. In the simulation circuit of FIG. 31, the switch element Q2 is turned on / off by the signal source 8 that outputs an oscillation signal of 10 kHz corresponding to the optical communication signal. doing. In addition, since circuit structures other than the load circuit comprised by circuit block B1-B4 are the same as that of Embodiment 15, the same code | symbol is attached | subjected to a common component and the description is abbreviate | omitted.

  FIGS. 32A and 32B show the results of simulating the currents I1 to I4 flowing through the load circuit using the above simulation circuit. Here, the current I2 is a current flowing through the light emitting diode LD2 to which the switch element Q2 is connected in parallel. The current I1 is a current that flows through the light emitting diode LD1 connected in series with the light emitting diode LD2 to which the switch element Q2 is connected in parallel. The current I3 is a current that flows through the series circuit 4 including the light emitting diode LD2 to which the switch element Q2 is connected and the other series circuit 4 belonging to the same circuit block B4. The current I4 is a combined current that flows through the load circuit.

  FIG. 32A shows currents I1 to I4 in a state where the signal source 8 is stopped, that is, in a state where the switch element Q2 is turned off, and the load currents I1 to I3 are set to about 500 mA of direct current. Since the load current flowing in the four series circuits 4 constituting each of the circuit blocks B1 to B4 is set to 500 mA of direct current, the combined current I4 is about 2 A of direct current.

  FIG. 32B shows a load when the light emitting diode LD2 is intermittently turned by outputting a 10 kHz rectangular wave signal (on duty is 50%) from the signal source 8 and turning on / off the switch element Q2. Currents I1 to I3 and combined current I4 are shown. Here, the current I2 flowing through the intermittent light emitting diode LD2 is 500 mA when the switch element Q2 is off, and 0 A when the switch element Q2 is on. On the other hand, the current I1 flowing through the light emitting diode LD1 connected in series with the light emitting diode LD2 is 500 mA when the switch element Q2 is turned off, and increases by a change determined by the amount of decrease in the on voltage when turned on. The current flowing in the other series circuit 4 belonging to the same circuit block B4 slightly decreases as the current I1 increases when the switch element Q2 is turned on, but the combined current I4 is based on the current value (about 2A) when not modulated. Will be modulated.

  Also in this circuit, as in each of the above-described embodiments, when the switch element Q2 is turned on, the on-voltage of the load circuit is lowered, and thereby the load current is instantaneously increased. Since this increase is not due to the feedback system via the error amplifier A1, the load current I1 increases instantaneously, and good followability to the optical communication signal can be obtained. On the other hand, while the switch element Q2 is off, the load current I1 is lower than when it is not modulated by the optical communication signal, but this current value is controlled by the constant current feedback circuit 6 so that the average current is not modulated. The current value determined to be the same value is controlled. Therefore, it is possible to provide an illumination optical communication device that can modulate output light faithfully in accordance with a high-frequency optical communication signal and has low power loss while a circuit added for communication is simple.

  In this circuit, only one of the 32 light emitting diodes is interrupted in response to the optical communication signal, so the degree of modulation of the combined current I4 is small, but the number of light emitting diodes that are intermittently short-circuited can be increased. If so, strong modulation can be obtained. How much modulation is required depends on the sensitivity on the receiving side. If the receiving side detects a difference in the intensity of illumination light, even if it is a minute modulation, It is possible to receive a modulated signal.

(Embodiment 17)
The illumination light communication apparatus of Embodiment 17 is demonstrated based on FIG.33 and FIG.34. FIG. 33A is a circuit diagram of this embodiment. In this illumination optical communication device 10, a plurality of (for example, four) light emitting diodes LD1 to LD4 are connected in series between the outputs of the DC-DC converter 2 (that is, between both ends of the smoothing capacitor C1) via the current detection resistor 5. The circuit 4 and the current limiting element 9 (load fluctuation element) are connected in series. Between both ends of the current limiting element 9, a switching element Q2 that is turned on / off in accordance with an optical communication signal is connected. The circuit configuration other than the load circuit including the light emitting diodes LD1 to LD4 and the current limiting element 9 is the same as that of the circuit of FIG. 23A described in the fourteenth embodiment. The description is omitted.

  Also in this illumination optical communication device 10, since the switch element Q2 is turned on / off according to the optical communication signal, both ends of the current limiting element 9 are short-circuited or opened. Modulation can be performed according to the communication signal.

  33 (b) to 33 (d) show a specific configuration of the current limiting element 9, and the current limiting element 9 may be configured with a diode D1 as shown in FIG. 33 (b). The diode D1 is a general diode, and the number and type thereof may be selected according to the required degree of modulation. In the above-described embodiment 14, the diode D1 is a light-emitting diode that emits visible light. However, the diode D1 may be a light-emitting diode other than visible light. If an infrared light-emitting diode is used, it receives infrared light. It becomes possible to receive with the instrument.

  FIG. 33 (c) shows that the current limiting element 9 is constituted by a resistor R2, and the resistance value may be set according to the required degree of modulation.

  FIG. 33 (d) shows that the current limiting element 9 is constituted by a parallel circuit of a diode D1 and a resistor R2, and may be constituted by a series circuit of a diode D1 and a resistor R2, depending on circumstances.

  34A and 34B show circuit examples in which a plurality (for example, two sets) of series circuits 4a and 4b of a plurality of (for example, four) light emitting diodes are connected in parallel. In the circuit example of FIG. 34A, a current limiting element 9 is connected to a location where two series circuits 4a and 4b merge, and a switching element Q2 is connected in parallel with the current limiting element 9. In the circuit example of FIG. 34B, the current limiting element 9 is connected in series only to one series circuit 4b, and the switch element Q2 is connected in parallel to the current limiting element 9. In the circuit example of FIG. 34C, a plurality (for example, two) of circuit blocks B1 to B4 in which a plurality (for example, two sets) of series circuits of a plurality of (for example, two) light emitting diodes are connected in parallel are connected in series. ing. In this circuit example, a current limiting element 9 is connected in series with one of the series circuits constituting the circuit block B4, and a switch element Q2 is connected in parallel with the current limiting element 9.

  In this manner, the current limiting element 9 is connected in series with the light emitting diode, and the current limiting element 9 is connected to the current limiting element 9 while the switch element Q2 connected in parallel with the current limiting element 9 is turned off according to the optical communication signal. As a result of generating a voltage drop or a shared voltage, the voltage applied to the light emitting diode is lowered by that amount and the load current is lowered. When the switch element Q2 is turned on in response to the optical communication signal, the voltage drop or shared voltage of the current limiting element 9 disappears, the voltage applied to the light emitting diode increases, and the load current increases. The increase / decrease in the voltage applied to the light emitting diode is due to turning on / off of the current limiting element 9 and not due to the feedback system (constant current feedback circuit 6) via the error amplifier A1, so the load current can be increased / decreased instantaneously. Good followability to communication signals can be obtained. Note that the average value of the load current is controlled to the same value as when there is no modulation by the averaging control by the constant current feedback circuit 6.

  Moreover, the communication function by illumination light can be easily added to the existing LED lighting fixture by adding the current limiting element 9 and the switch element Q2. Further, by selecting the current limiting element 9 having desired characteristics, it is possible to realize fine adjustment of the modulated light according to the required dimming degree, in other words, the sensitivity of the receiver 20, so that optimum optical communication is possible. Can be realized.

  In each of the circuits of the fourteenth to sixteenth embodiments described above, instead of connecting the switch element Q2 in parallel with a part of the light emitting diode, a current limiting element 9 is connected in series with the light emitting diode, and the current limiting element 9 is connected. The switch elements Q2 connected in parallel may be turned on / off according to the optical communication signal. Also in this case, the load current can be modulated in accordance with the optical communication signal as in the circuits of the above-described embodiments.

  In the present embodiment, the number of light emitting diodes is not necessarily plural, and as an extreme example, the current limiting element 9 is connected in series with one light emitting diode, and the switch element Q2 is connected in parallel to the current limiting element 9 to switch The element Q2 may turn on / off between both ends of the current limiting element 9.

(Embodiment 18)
An illumination light communication apparatus according to the eighteenth embodiment will be described with reference to FIG. FIG. 35A is a circuit diagram of the present embodiment. In this illumination optical communication device 10, a plurality of types of light emitting diodes LD 1, LD 2, LD 3 are provided between the outputs of the DC-DC converter 2 (that is, between both ends of the smoothing capacitor C 1) via the current detection resistor 5 ( For example, 4 pieces are connected in series. The three types of light emitting diodes LD1, LD2, and LD3 have different emission colors (for example, three types of R, G, and B) and are connected in series for each emission color. Each type of light emitting diode LD1, LD2, LD3 is turned on / off by individual optical communication signals S1, S2, S3 in parallel with a part (for example, one) of light emitting diodes LD1, LD2, LD3. Switch elements Q21, Q22, Q23 are connected. Since the circuit configuration other than the load circuit composed of the light emitting diodes LD1 to LD3 is the same as the circuit of FIG. 23A described in the fourteenth embodiment, common constituent elements are denoted by the same reference numerals, The description is omitted.

  Here, when the switch elements Q21, Q22, Q23 are turned on / off according to the optical communication signals S1, S2, S3, a part of the light emitting diodes LD1, LD2, LD3 of each emission color is short-circuited. As in the first mode, the optical output is modulated. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference. The amount of information that can be transmitted by communication can be tripled.

  In the above circuit, a plurality of types of light emitting diodes having different emission colors are connected in series. However, as shown in FIG. 35B, a plurality of types of light emitting diodes are connected in series between the outputs of the DC-DC converter 2. A plurality of light emitting diode series circuits may be connected in parallel. In this circuit, a plurality of light emitting diodes LD1, LD2, and LD3 of different types (for example, three types of R, G, and B) having different emission colors are connected in series between the outputs of the DC-DC converter 2 via a current detection resistor 5. A plurality of series circuits 4a, 4b, and 4c connected to each other are connected in parallel. For each type of series circuit 4a, 4b, 4c, switching elements Q21, Q22, Q23 are connected in parallel with some (for example, one) light emitting diodes LD1, LD2, LD3. Also in this circuit, when the switching elements Q21, Q22, and Q23 are turned on / off according to the optical communication signals S1, S2, and S3, a part of the light emitting diodes LD1, LD2, and LD3 of the respective emission colors is short-circuited. As in the first embodiment, the light output is modulated. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference. The amount of information that can be transmitted by communication can be tripled. Further, in this circuit, as described in the seventeenth embodiment, the current limiting element 9 is connected in series with the light emitting diode, and the load current is turned on / off by the switch element connected in parallel with the current limiting element 9. May be modulated.

(Embodiment 19)
An illumination light communication apparatus according to the nineteenth embodiment will be described with reference to FIGS.

  FIG. 36A is a circuit diagram of the present embodiment. In this illumination optical communication device 10, a plurality of (for example, two sets) series circuits 4 a and 4 b each having a plurality of light emitting diodes LD 1 and LD 2 connected in series between the outputs of the DC-DC converter 2 via the current detection resistor 5. Connected in parallel. A switch element Q2 that is turned on / off in response to an optical communication signal is connected in series with the light emitting diode LD2 that constitutes one of the series circuits 4b. Since the circuit configuration other than the load circuit composed of the light emitting diodes LD1 and LD2 is the same as the circuit of FIG. 23A described in the fourteenth embodiment, common components are denoted by the same reference numerals, The description is omitted.

  FIG. 36B shows a simulation circuit for verifying the operation of the circuit shown in FIG. In this circuit, a step-down chopper circuit is used as the DC-DC converter 2. Further, between the outputs of the DC-DC converter 2, series circuits 4 a and 4 b in which eight light emitting diodes LD 1 and LD 2 are connected in series are connected in parallel via a current detection resistor 5. The switch element Q2 connected in series with the light emitting diode LD2 is turned on / off by a signal source 8 that outputs an oscillation signal of 10 kHz corresponding to an optical communication signal.

  FIGS. 37A and 37B show the results of simulating the load currents I1 to I3 using the above simulation circuit. The load current I1 is a current flowing through the series circuit 4a of the light emitting diode LD1, the load current I2 is a current flowing through the series circuit 4b of the light emitting diode LD2, and the load current I3 is a combined current of the currents I1 and I2.

  FIG. 37 (a) shows the currents I1 to I3 when the signal source 8 is stopped (switch element Q2 is on), the load currents I1 and I2 are set to about 500 mA DC, and the combined current I3 is DC. Is set to about 1A.

  FIG. 37B shows currents I1 to I3 in a state where a 10 kHz rectangular wave signal (on duty is 50%) is output from the signal source 8 and the series circuit 4b of the light emitting diode LD2 is intermittent. . Here, the current waveform of the current I1 flowing through the series circuit 4a to which the switch element Q2 is not connected is a direct current of about 700 mA. On the other hand, the current waveform of the current I2 flowing through the series circuit 4b to which the switch element Q2 is connected is a rectangular wave current having a peak value of about 700 mA and a bottom value of 0A. Therefore, the combined current I3 has a current waveform that vibrates positively and negatively with an amplitude of about 300 mA with reference to the average value (1A). FIG. 37C shows currents I1 to I3 when the on-duty of the rectangular wave signal output from the signal source 8 is 75%. When the on-duty is larger than 50%, the peak current of the combined current I3 can be reduced while the average current is constant as compared with the case where the on-duty is 50%.

  Incidentally, in the circuit of FIG. 36, two sets of series circuits 4a and 4b of light emitting diodes are connected in parallel between the outputs of the DC-DC converter 2, but the series circuit of light emitting diodes connected in parallel is limited to two sets. It is not intended. For example, as shown in FIG. 38, three sets of series circuits 4a, 4b, and 4c in which eight light emitting diodes LD1, LD2, and LD3 are connected in series are connected in parallel between the outputs of the DC-DC converter 2. Good. In this circuit, a switch element Q2 that is turned on / off in response to an optical communication signal is connected in series with a series circuit 4c formed of a light emitting diode LD3.

  Here, FIG. 39 shows the result of simulating the load currents I1, I2, and I3 flowing through the series circuits 4a, 4b, and 4c and the combined current I4.

  FIG. 39A shows currents I1 to I4 in a state where the signal source 8 is stopped (switch element Q2 is on), and load currents I1, I2, and I3 are set to about 500 mA of direct current, and the combined current I4 Is set to about 1.5 A of direct current.

  FIG. 39 (b) outputs a 10 kHz rectangular wave signal (on-duty 50%) from the signal source 8, and the currents I1 to I4 in a state where the series circuit 4c of the light emitting diode LD3 is intermittently connected by the switch element Q2. Show. Here, the current waveforms of the currents I1 and I2 flowing through the series circuits 4a and 4b to which the switch element Q2 is not connected become a direct current of about 600 mA. On the other hand, the current waveform of the current I3 flowing through the series circuit 4c to which the switch element Q2 is connected is a rectangular wave current having a peak value of about 600 mA and a bottom value of 0A. Therefore, the composite current I4 has a current waveform that vibrates positively and negatively with an amplitude of about 300 mA with reference to the average value (1.5 A). FIG. 39C shows currents I1 to I4 when the on-duty of the rectangular wave signal output from the signal source 8 is 75%. In this case, the current waveform of the current I3 flowing through the series circuit 4c to which the switch element Q2 is connected is a rectangular wave current having a peak value of about 550 mA and a bottom value of 0A. The combined current I4 is a modulation signal based on the average value (about 1.5A), but the peak value of the combined current I4 is also suppressed to about 1.65A by suppressing the peak value of the current I3. . As described above, when the on-duty is larger than 50%, the peak current of the combined current I4 can be reduced while the average current is constant as compared with the case where the on-duty is 50%.

  When the number of light emitting diode circuits connected in parallel between the outputs of the DC-DC converter 2 is three or more, the switch element Q2 is connected to a place where a plurality of circuits are integrated except for one circuit. Also good. Even in this case, when the switch element Q2 is turned on / off according to the optical communication signal, a plurality of circuits to which the switch element Q2 is connected can be intermittently turned on / off, and the load current can be modulated. .

  As described above, in the present embodiment, a plurality of light emitting diodes are connected in parallel to the output terminal of the DC-DC converter 2, and the switch element Q2 is connected in series with some of the light emitting diodes. The reason for the premise of the connected circuit is discussed below.

  As shown in FIG. 40, a simulation result of the load current is shown for a circuit in which a plurality of light emitting diodes LD1 are connected in series to the output end of the DC-DC converter 2, and a switch element Q2 is connected in series with the light emitting diode LD1. 41. FIG. 41A shows the load current I1 and the output voltage V1 of the DC-DC converter 2 when the signal source 8 is stopped (the switch element Q2 is on). The current I1 is about 500 mA DC and the output voltage V1. Is about 26V of direct current.

  On the other hand, FIG. 41B shows a load current I1 in a state in which a 10 kHz rectangular wave signal (on duty is 50%) is output from the signal source 8 and the series circuit 4 of the light emitting diode LD3 is intermittently connected by the switch element Q2. The output voltage V1 is shown. In this simulation result, the load current I1 has a peak value of about 6.5A and an output voltage V1 of about 140V, which is not practical. This phenomenon is controlled by the constant current averaging control, and the output voltage V1 is controlled according to the average value of the load current I1. Therefore, when the load current I1 is cut off, unless the feedback function or protection function of the output voltage V1 is added, This is because the DC-DC converter 2 outputs the maximum voltage. Therefore, it is necessary to avoid a no-load state in which the load circuit is completely cut off.

  From this point of view, when only some of the light emitting diodes connected in parallel are intermittently turned on / off at high speed, the reason why the load current I1 can be appropriately modulated is as follows. I can explain. That is, a state in which some of the circuits are turned off is a state in which the load of the DC-DC converter 2 is lightened. However, if constant current control by the DC-DC converter 2 is functioning normally, the current flows to the light emitting diode. Feedback control should be performed in the direction of increasing the load current. However, when intermittent ON / OFF is performed at a high speed of 10 kHz, the gain of the error amplifier A1 cannot be obtained by the PI control of the constant current feedback circuit 6, and as a result, the load current I1 decreases and the output voltage V1 becomes To rise. Next, when the switch element Q2 is turned on, the load current increases by an amount corresponding to the increase of the output voltage V1 during the off period. However, when the time axis is expanded, the constant current averaging control functions, and the load current is increased. The average value is controlled to be a predetermined current value (target value).

  In this way, when a part of the circuits is turned off by turning on / off the switching element Q2 at a high frequency of about 10 kHz, since the feedback control of the constant current feedback circuit 6 does not function, only the increase / decrease of the LED load is achieved. The load current is determined according to the condition determined by (1), and the load current can be modulated extremely quickly. Therefore, it is possible to provide an illumination optical communication device that can modulate output light faithfully in accordance with a high-frequency optical communication signal and has low power loss while a circuit added for communication is simple.

  In the present embodiment, a plurality of light emitting diodes do not necessarily have to be connected in series. A plurality of circuits composed of one light emitting diode are connected in parallel, and a switch element Q2 is connected in series with any of the light emitting diodes. May be.

(Embodiment 20)
The illumination light communication apparatus according to the twentieth embodiment will be described with reference to FIG.

  FIG. 42 is a circuit diagram of the illumination light communication apparatus 10 of the present embodiment. In this apparatus, a plurality of types (for example, three types) of light emitting diodes LD1, LD2, and LD3 having different emission colors are connected in series between the outputs of the DC-DC converter 2 via the current detection resistor 5. A plurality of series circuits 4a, 4b, 4c are connected in parallel. In addition, switch elements Q21, Q22, and Q23 that are turned on / off in response to individual optical communication signals S1, S2, and S3 are connected in series with each type of series circuit 4a, 4b, and 4c. The elements Q21, Q22, Q23 are controlled so as not to be turned off simultaneously. Since the circuit configuration other than the load circuit composed of the light emitting diodes LD1, LD2, and LD3 is the same as that of the circuit of FIG. 23A described in the fourteenth embodiment, common constituent elements are denoted by the same reference numerals. The description is omitted.

  Also in this embodiment, when the switching elements Q21, Q22, Q23 are turned on / off according to the optical communication signals S1, S2, S3, the light emitting diodes LD1, LD2, LD3 of the respective emission colors are intermittently turned on / off. Thus, similarly to the first embodiment, the optical output is modulated. Thus, if the color temperature of the light output from the illumination light communication device 10 can be identified on the receiver 20 side, three types of signals can be received without causing interference. The amount of information that can be transmitted by communication can be tripled. In this case, it is necessary to control the switching elements Q21, Q22, and Q23 not to be turned off at the same time so that the series circuits 4a to 4c of all the light emitting diodes LD1 to LD3 are turned off at the same time and no load is caused. There is.

  In the present embodiment, a plurality of types of light-emitting diodes LD1, LD2, and LD3 are not necessarily connected in series. As an extreme example, each type of light-emitting diode may be configured by one. .

(Embodiment 21)
The illumination light communication apparatus of Embodiment 21 will be described with reference to FIG. In the illumination optical communication device of each embodiment described above, the switch element Q2 connected in parallel or in series with the light emitting diode is turned on / off in accordance with the optical communication signal, thereby modulating the load current and the light output. Modulated. Therefore, it is considered that the optical communication function can be easily added to the existing LED lighting fixture by adding the switch element Q2, but the safety between the optical communication signal system that generates the optical communication signal and the lighting circuit is safe. It is desirable to be electrically insulated.

  FIG. 43A is a circuit diagram of an illumination light communication apparatus realized by adding a communication unit 30 to an existing lighting fixture 10A. In addition, the same code | symbol is attached | subjected to the component which is common in the illumination light communication apparatus 10 shown to Fig.23 (a), and the description is abbreviate | omitted.

  This lighting fixture 10 </ b> A includes a connector CN <b> 1 to which the communication unit 30 is connected between the outputs of the DC-DC converter 2. A plurality of (for example, four) light emitting diodes LD1 are connected in series between the output on the high voltage side of the DC-DC converter 2 (that is, the high voltage side end of the smoothing capacitor C1) and the connector CN1. . A current detection resistor 5 is connected in series between the output on the low voltage side of the DC-DC converter 2 (that is, the low voltage side end of the smoothing capacitor C1) and the connector CN1.

  FIG. 43B is a specific circuit diagram of the communication unit 30. This communication unit 30 has a connector CN2 that is detachably connected to the connector CN1, and the limit described in the seventeenth embodiment between the terminals of the connector CN2. The flow element 9 and the switch element Q2 are connected in parallel. In this communication unit 30, the switch element Q2 is turned on / off based on the optical communication signal S1 input from the external communication device 40 to the input terminal t1, and the communication circuit 40 and the lighting fixture are turned on by the built-in transformer T1. 10A is electrically insulated. In this circuit, an astable multivibrator is constituted by the timer IC 31 (for example, LMC555 of National Semiconductor), resistors R11 and R12, and a capacitor C10, and oscillates at a sufficiently high frequency (for example, 1 MHz) with respect to the frequency of the optical communication signal S1. Let The output signal of the timer IC 31 is input to one input terminal of the AND gate IC1. The optical communication signal S1 is input to the other input terminal of the AND gate IC1, and the logical sum of the optical communication signal S1 and the output signal of the timer IC 31 is input to the buffer element IC2 and is coupled via the coupling capacitor C11. The primary winding of the insulating transformer T1 is excited. A high-frequency voltage that is induced by the secondary winding of the isolation transformer T1 and modulated by the optical communication signal S1 having a carrier frequency of 1 MHz is 9.6 kHz is generated by a voltage doubler rectifier circuit including diodes D11 and D12 and capacitors C12 and C13. Rectified and smoothed. The power supply of the buffer IC3 that drives the gate of the switch element Q2 is formed by the output voltage of the voltage doubler rectifier circuit. The voltage induced in the secondary winding of the isolation transformer T1 is divided and shaped by the resistors R13 and R14 and the capacitor C14, and then input to the buffer element IC3. By this waveform shaping, the frequency component of 1 MHz is removed, the optical communication signal S1 is reproduced, and the gate of the switch element Q2 made of a power MOSFET is driven. Of course, a method of driving the isolation transformer T1 only with the optical communication signal S1 and directly driving the switch element Q2 with its output is also conceivable. In this case, consideration must be given to an increase in the size of the insulating transformer T1 and a device for obtaining a drive waveform faithful to the optical communication signal S1.

  By the way, in the above-described circuit, the communication unit 30 is applied to the circuit of FIG. 23A. However, the above-described communication unit 30 may be applied to the illumination light communication devices of Embodiments 1 to 5 described above. In that case, the current limiting element 9 having the configuration as shown in FIGS. 33B to 33D may be built in the communication unit 39, and the current limiting element 9 may be connected in parallel with the switch element Q2. Further, the communication unit 30 of the present embodiment may be applied to the illumination light communication devices of the sixth and seventh embodiments. In that case, it is not necessary to connect the current limiting element 9 in parallel with the switch element Q2.

  As described above, the communication unit 30 incorporates the current limiting element 9 together with the switch element Q2, and is connected to the load circuit 4 via the connectors CN1 and CN2 which are mechanical components for connection.

  Thereby, when adding an optical communication function to the existing lighting fixture 10A which does not have an optical communication function, it is not necessary to carry out a special process other than providing the connector CN1 with respect to the existing lighting fixture 10A.

  Further, since the communication circuit 40 that generates the optical communication signal S1 and the switch element Q2 are electrically insulated by the insulation transformer T1, insulation between the communication circuit 40 and the lighting fixture 10A can be ensured. Moreover, since the power for driving the switching element Q2 is supplied from the communication circuit 40 via the insulating transformer T1 as an insulating portion, a special driving power for the switching element Q2 is provided on the existing lighting fixture 10A side. No processing is required.

  FIG. 43 (c) shows another circuit example of the communication unit 30. An optical communication signal S1 input from the outside is transmitted to the input terminal of the gate element IC3 by the photocoupler PC1, and the switch element Q2 is transmitted by the gate element IC3. Is to drive. In this circuit, it is necessary to secure driving power for the gate element IC3 and the photocoupler PC1 from the DC-DC converter 2 on the lighting fixture side, but the circuit configuration of the communication unit 30 is simpler than that of the circuit of FIG. Can be FIG. 43 (d) shows still another circuit example of the communication unit 30. In this case, the optical communication signal S1 is transmitted to the input terminal of the gate element IC3 by the pulse transformer T2, and the switch element Q2 is driven. In addition, the circuit configuration of the communication unit 30 can be simplified.

  In each of the above embodiments, a light emitting diode is used as a light source, but organic electroluminescence (organic light emitting diode) may be used instead of the light emitting diode.

  The illumination light communication apparatus described above includes a constant current source, a smoothing circuit and a load circuit, a load variation element, and a switch element. A smoothing circuit and a load circuit including a light emitting diode are connected to the output of the constant current source. The load variation element is added to the load circuit to partially change the load characteristic of the load circuit. The switch element switches whether to add the load variation element to the load circuit according to a binary optical communication signal.

  In this illumination optical communication device, it is preferable that the load variation element is a resistor connected in series to the light emitting diode, and the switch element is connected in parallel to the resistor.

  In this illumination optical communication device, the load variation element is configured by a constant voltage circuit unit including at least a constant voltage element connected in series to the light emitting diode, and the switch element is connected in parallel to the constant voltage circuit unit. Is also preferable.

  In the illumination light communication apparatus, a plurality of the load circuits are connected in parallel between outputs of the constant current source, and the load variation element and the switch element are provided in at least one of the plurality of load circuits. Is also preferable.

  In the illumination light communication apparatus, it is also preferable that the plurality of load circuits are configured by the light emitting diodes having different emission colors for each load circuit, and the switch element is provided for each of the load circuits having different emission colors.

  In this illumination optical communication device, the load circuit preferably includes a plurality of light emitting diodes connected in series, and the switch element is preferably connected in parallel to a part of the plurality of light emitting diodes.

  In the illumination light communication apparatus, a plurality of the load circuits are connected in parallel between the outputs of the constant current source. Each of the load circuits includes a plurality of the light emitting diodes connected in series, and the light emission color of the light emitting diode is different for each load circuit, and each of the load circuits is parallel to a part of the plurality of light emitting diodes. It is also preferable that the switch element is connected to the switch.

  In the illumination light communication apparatus, a plurality of the load circuits are connected in parallel between the outputs of the constant current source. Preferably, the switch element is connected in series with at least one of the plurality of load circuits, and the load variation element is the load circuit connected in series to the switch element.

  In this illumination light communication device, it is also preferable to include a duty adjustment unit that changes the on / off duty ratio of the optical communication signal.

  In this illumination optical communication device, it is also preferable that the constant current source includes a constant current feedback system including a converter unit, a current detection unit, a differential amplification unit, and a control unit. The converter unit generates a direct current output. The current detector generates a voltage drop corresponding to the load current flowing through the load circuit. The difference amplifying unit amplifies a difference between a voltage drop generated in the current detection unit and a predetermined reference voltage. The control unit controls the output of the converter unit so that the average value of the load current becomes substantially constant according to the output of the difference amplifying unit.

  In this illumination light communication apparatus, it is also preferable that a phase compensation circuit that includes an integration element and adjusts the phase of the output of the differential amplifier is provided in the constant current feedback system.

  The illumination optical communication apparatus includes a communication unit that houses the signal generation circuit that generates the optical communication signal, the load variation element, and the switch element in the same case, and the communication unit includes a mechanical part for connection. It is also preferable to be connected to the load circuit via

  In this illumination optical communication device, it is also preferable that an insulating portion for electrically insulating the signal generation circuit for generating the optical communication signal and the switch element is provided.

  In this illumination optical communication device, a signal generation circuit that generates the optical communication signal generates a plurality of different types of optical communication signals. It is also preferable that the individual switch elements are provided for each type of the optical communication signal, and that an insulating portion that electrically insulates the plurality of switch elements is provided.

  The illumination light communication apparatus preferably includes a carrier wave generation unit, a modulation unit, an insulating transformer, and a demodulation unit. The carrier wave generation unit generates a carrier wave set to a frequency higher than the frequency of the optical communication signal so as to be separated from the optical communication signal. The modulation unit modulates the optical communication signal with the carrier wave. The insulating transformer is connected between the modulation unit and the switch element. The demodulator outputs a signal obtained by removing the carrier from the output of the isolation transformer to the switch element.

  In this illumination optical communication device, it is also preferable that the light emitting diode is an organic light emitting diode.

DESCRIPTION OF SYMBOLS 10 Illumination light communication apparatus 11 Constant current source 12 Load circuit 13 Load fluctuation element C11 Smoothing capacitor LD1 Light emitting diode Q2 Switch element

Claims (5)

A switching power supply;
A load circuit including a light emitting diode connected between the outputs of the switching power supply;
A load variation element that changes the load current flowing in the load circuit by being added to the load circuit;
A load changing unit that switches whether to add the load changing element to the load circuit according to a binary optical communication signal ;
Regardless of whether or not the load variation element is added to the load circuit, a feedback circuit that controls the average value of the load current to be constant, and
In the feedback circuit, the load current is modulated to a predetermined current value in a state where the load variation element is added to the load circuit and in a state where the load variation element is not added to the load circuit, and The illumination light communication apparatus , wherein the switching power supply is controlled so that an average current is constant between transmission of the optical communication signal and stop of transmission . The optical communication signal is a rectangular wave signal whose on-duty is adjusted, and in a state where the load variation element is connected to the load circuit, a difference between an average value and a bottom value of the load current is d1, and the load current When the difference between the peak value and the average value is d2,
  If the on-duty of the optical communication signal is 50%, d1 = d2, and if the on-duty of the optical communication signal is larger than 50%, d1> d2, and the on-duty of the optical communication signal is smaller than 50%. The illumination light communication apparatus according to claim 1, wherein d1 <d2 is satisfied. A switching power supply;
A load circuit including a light emitting diode connected between the outputs of the switching power supply;
A load variation element that changes the load current flowing in the load circuit by being added to the load circuit;
A load changing unit that switches whether or not to add the load changing element to the load circuit according to a binary optical communication signal;
The optical communication signal is a rectangular wave signal whose on-duty is adjusted, and in a state where the load variation element is connected to the load circuit, a difference between an average value and a bottom value of the load current is d1, and the load current When the difference between the peak value and the average value is d2,
If the on-duty of the optical communication signal is 50%, d1 = d2, and if the on-duty of the optical communication signal is larger than 50%, d1> d2, and the on-duty of the optical communication signal is smaller than 50%. if d1 <characterized in that it is configured such that d2 irradiation Meiko communication device.   The illumination light communication apparatus according to claim 1, wherein the load variation element is a thermistor.   An illumination light communication system comprising: the illumination light communication apparatus according to claim 1; and a receiver that receives a light output from the illumination light communication apparatus.

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