JP4661771B2 - Lighting device for visible light communication and visible light communication lighting system - Google Patents

Description

  The present invention relates to a visible light communication lighting apparatus and a visible light communication lighting system that perform communication using visible light for illumination.

As a conventional visible light communication lighting device and a visible light communication lighting system that performs communication using visible light for illumination, Patent Literature 1 drives an LED (Light Emitting Diode) as an illumination light source and the LED. A lighting fixture and a lighting system including a switching control circuit are disclosed. The lighting fixture and the lighting system of Patent Document 1 perform visible light communication by controlling the lighting and extinguishing of the LED, and by fixing the lighting time and the extinguishing time of the LED at a predetermined ratio, the visible light communication is performed. Changes in the lighting environment due to turning on and off at the time can be reduced.
JP 2004-120101 A (paragraphs 0009 to 0013 and FIGS. 1 to 3)

  However, in the conventional visible light communication lighting apparatus and visible light communication lighting system, the light beam emitted from the light source gradually decreases due to deterioration of the resin or the like forming the light source (LED) (light beam decrease). Will occur. Since the luminous flux of the light source greatly depends on the communication distance of visible light communication, the conventional visible light communication lighting fixture and visible light communication lighting system have a place where the communication distance is shortened by the decrease of the light flux of the light source. There is a problem that there is a high possibility that the communication range becomes narrow.

  The present invention has been made in view of the above points, and an object of the present invention is to maintain the communication distance and communication range of visible light communication within a certain range with respect to the initial state over a long period of time. An object of the present invention is to provide a lighting device for visible light communication and a visible light communication lighting system.

The invention relating to the lighting device for visible light communication according to claim 1 includes: a light source that emits visible light; a transmission unit that switches on and off of the light source based on transmission information and transmits the transmission information; and A lighting control means for controlling the light source so that the light emission illuminance falls within a predetermined range, a timer for measuring the total light emission time of the light source, and the total so that the light emission illuminance falls within the predetermined range. Storage means for storing a data table indicating the current value of the current supplied to the light source for each light emission time, and the lighting control means is stored in the total light emission time counted by the timer and the storage means. The current value of the supply current to the light source is controlled based on the data table .

The visible light communication lighting system according to claim 2 is a visible light communication lighting device according to claim 1 , and a receiver that receives visible light from the visible light communication lighting device and receives transmission information. It is characterized by providing.

  According to the first aspect of the present invention, the luminous flux decrease of the light source can be corrected and the light emission intensity of the light source can be maintained within a certain range with respect to the initial state. It can be kept for a long time within a certain range with respect to the state.

Further, according to the first aspect of the present invention, it is possible to predict the light flux decrease of the light source for each total light emission time of the light source, and supply a current having a current value set to the light source based on this prediction.

According to the second aspect of the present invention, in the lighting device for visible light communication, the luminous flux reduction of the light source can be corrected so that the light emission illuminance of the light source can be within a certain range with respect to the initial state. The communication distance and communication range can be kept within a certain range with respect to the initial state over a long period of time.

(Embodiment 1)
First, the structure of the visible light communication illumination system according to the first embodiment of the present invention will be described with reference to FIGS. This visible light communication illumination system performs communication using visible light for illumination, and as shown in FIG. 1, a visible light communication lighting device 1 that emits visible light and transmits transmission information, And a receiver 2 that receives visible light from the luminaire 1 for visible light communication and receives transmission information.

  The visible light communication lighting device 1 includes a light source 10 that emits visible light, a power supply unit 11 that generates a current for causing the light source 10 to emit light, and a constant current circuit unit 12 that uses a current from the power supply unit 11 as a constant current. A signal oscillation unit 13 that superimposes transmission information on a constant current from the constant current circuit unit 12, a brightness sensor 14 that detects the light emission illuminance of the light source 10, and a target value of the sensor voltage of the brightness sensor 14 is stored. A first storage unit 15, a second storage unit 16 that stores transmission information, and a control unit 17 that transmits and receives transmission information by switching on and off the light source 10 are housed in the instrument body 18 (see FIG. 2). It is prepared.

  2 is embedded and installed in the ceiling surface 3 so that the lower surface 180 and the light emitting surface 181 are exposed.

  The light source 10 shown in FIG. 1 is an LED, and emits visible light when supplied with current. Since this LED is a semiconductor light emitting element, it has no filament and has a relatively long life compared to a discharge lamp or an incandescent lamp, but the LED chip and the resin sealing the LED chip are deteriorated. As a result, as shown in FIG. 3, the light transmittance is reduced and the luminous flux is reduced. The degree of light flux reduction of the light source 10 cannot be determined unconditionally depending on the overall heat dissipation, resin composition, etc., but as an example, it is said that the total lighting time is about 40,000 hours, which is reduced to 50% of the initial state. When it decreases to 50% of the initial state, the communication distance and communication range of visible light communication are assumed to be less than half of the initial state.

  The power supply unit 11 shown in FIG. 1 is configured by a diode bridge, for example, and is connected to an AC power supply AC. The AC power source AC is, for example, a commercial power source. The power supply unit 11 rectifies an AC current from the AC power supply AC, smoothes it, and outputs it to the constant current circuit unit 12.

The constant current circuit unit 12 is composed of, for example, a shunt regulator or a current mirror circuit, and makes the current value of the current from the power supply unit 11 constant, and a constant current I ₁ that is a direct current of a predetermined current value a (see FIG. )) Is output to the signal oscillator 13. The luminous flux of the light source 10 changes according to the current value a of the constant current I ₁ output from the constant current circuit unit 12.

The signal oscillating unit 13 includes, for example, a semiconductor switch element such as a bipolar transistor or FET (Field Effect Transistor) or an oscillator such as a crystal. When a later-described information signal including transmission information is input to the signal oscillating unit 13 from the control unit 17, the signal oscillating unit 13 receives the input information signal from the constant current I ₁ (see FIG. 4 (a)), and the superimposed pulse current I ₂ (see FIG. 4 (b)) is output to the light source 10. The amplitude of the pulse current I ₂ is the same as the current value a constant current I _1. By the operation as described above, the signal oscillating unit 13 can switch the light source 10 on and off according to the pulse current I ₂ based on the transmission information, and transmit the transmission information from the light source 10 (FIG. 4 ( c)).

  The brightness sensor 14 is, for example, a light-receiving semiconductor element such as a photodiode or a phototransistor, and detects the light emission illuminance of the light source 10 and controls the sensor voltage V (see FIG. 4D) based on the detected light emission illuminance. 17 to output. Therefore, as shown in FIG. 2, the brightness sensor 14 is fixed to the instrument body 18 with the light receiving surface 140 facing the light emitting surface 181 on which the light source 10 is installed. Note that the voltage value of the sensor voltage V and the luminous flux of the light source 10 are in a substantially proportional relationship.

  The first storage unit 15 illustrated in FIG. 1 is a non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory, for example, and a target centering on a target value b of the sensor voltage V of the brightness sensor 14. The range B (see FIG. 5B) is stored. The target range B is a predetermined range centered on the target value b or the target value b itself. In the first embodiment, the target range B is set in advance within a range of up to 10% around the target value b. Means for writing the target range B into the first storage unit 15 includes writing at the manufacturing stage and writing or rewriting from an external device (for example, a remote controller or an external communication interface).

  The second storage unit 16 is a non-volatile memory such as an EEPROM or a flash memory, for example, and stores transmission information for transmission by visible light communication. Means for writing the transmission information to the second storage unit 16 include writing at the manufacturing stage and writing or rewriting from an external device (for example, a remote controller or an external communication interface).

  The control unit 17 is configured by, for example, a microcomputer, and transmits the transmission information by switching on and off the light source 10 based on the transmission information. Specifically, first, the control unit 17 reads transmission information from the second storage unit 16 at the same time as the power is turned on. Thereafter, the control unit 17 creates an information signal by patterning the read transmission information by a predetermined method (for example, the Manchester method or the bipolar method), and the signal information is generated at a predetermined time interval. 13 is output. As described above, since the control unit 17 can cause the light source 10 to emit light based on the pattern of the information signal, the transmission information stored in the second storage unit 16 can be transmitted by visible light communication.

Moreover, the control part 17 controls the light source 10 so that the light emission illuminance of the light source 10 at least during non-communication is within a certain range. Specifically, first, the control unit 17 reads the target range B (see FIG. 5B) of the sensor voltage V of the brightness sensor 14 from the first storage unit 15 at the same time when the power is turned on. The target range B is compared with the voltage value of the sensor voltage V sequentially input from the brightness sensor 14 at least while the control unit 17 is not outputting an information signal to the signal oscillation unit 13 (during non-communication). Thereafter, the control unit 17 controls the constant current circuit unit 12 to increase or decrease the current value a of the constant current I ₁ based on the result of comparison performed at the time of non-communication, whereby the voltage value of the sensor voltage V is set to the target value. The light source 10 is controlled so as to be within the range B.

  Then, the structure of the receiver 2 which concerns on Embodiment 1 is demonstrated. The receiver 2 includes a light receiving unit 20 that receives visible light from the light source 10 and a demodulation unit 21 that demodulates transmission information from the visible light received by the light receiving unit 20.

  The light receiving unit 20 is configured by, for example, a photodiode or a resistor, and receives visible light from the light source 10. After receiving light, the light receiving unit 20 creates an electrical signal based on the received visible light, and outputs the electrical signal to the demodulating unit 21.

  The demodulating unit 21 amplifies the electrical signal from the light receiving unit 20, demodulates transmission information from the amplified electrical signal, and displays the demodulated transmission information.

Next, the operation of the visible light communication illumination system according to the first embodiment will be described with reference to FIGS. First, the light source 10 of the luminaire 1 for visible light communication shown in FIG. 1 emits visible light by a pulse current I ₂ (see FIG. 4B) from the signal oscillator 13 (see FIG. 5A). On the other hand, in the receiver 2, the light receiving unit 20 receives visible light from the light source 10, and the demodulation unit 21 detects transmission information included in the visible light. At this time, in the visible light communication lighting device 1, the brightness sensor 14 detects the light emission illuminance of the light source 10, and outputs the sensor voltage V to the control unit 17 (see FIG. 5B). The control unit 17 compares whether or not the voltage value of the sensor voltage V at the time of non-communication is within the target range B (see FIG. 5B), and when it is out of the target range B (t _{11 in} FIG. 5). , T ₁₂ , t ₁₃ , t ₁₄ , t ₁₅ ), and the constant current circuit unit 12 is controlled to change the current value a of the constant current I ₁ so that the sensor voltage V is within the target range B (FIG. 5). (See (c)). Specifically, increasing the current value a of the constant current I ₁ and the voltage value of the sensor voltage V is below the target range B.

As described above, according to the first embodiment, in the lighting device for visible light communication 1 shown in FIG. 1, the control unit 17 controls the constant current circuit unit 12 to increase the current value a of the constant current I ₁ (FIG. 5 (c)), the reduction of the luminous flux of the light source 10 is corrected (see FIG. 5 (a)), and the light emission illuminance of the light source 10 can be maintained within a certain range with respect to the initial state (FIG. 5 ( b)), the communication distance and communication range of visible light communication can be kept within a certain range for a long time with respect to the initial state while the receiver 2 is kept as it is.

  Further, since the light emission illuminance of the light source 10 can be detected by the brightness sensor 14, the light emission illuminance of the light source 10 can be easily maintained within a certain range using the detected light emission illuminance.

  Furthermore, since the light emission illuminance detected by the brightness sensor 14 at the time of non-communication is used to correct the light beam decrease of the light source 10, the average light emission light flux per unit time of the light source 10 varies depending on transmission information, compared with visible light communication. Thus, the light emission illuminance of the light source 10 can be detected more accurately, and highly accurate feedback can be performed.

(Embodiment 2)
First, the structure of the visible light communication illumination system according to Embodiment 2 of the present invention will be described with reference to FIGS. This visible light communication lighting system includes a receiver 2 (see FIG. 1) in the same manner as the visible light communication lighting system (see FIG. 1) of the first embodiment, and the visible light communication lighting device 1 of the first embodiment (FIG. 1). In place of (refer to FIG. 6), a lighting device 1a for visible light communication as shown in FIG. 6 is provided. As illustrated in FIG. 6, the visible light communication lighting device 1 a according to the second embodiment includes a light source 10, a power supply unit 11, a constant current circuit unit 12, a signal oscillation unit 13, and a second storage unit 16. Although provided similarly to the lighting fixture 1 for visible light communication of Embodiment 1, it has the following characteristic parts which are not in the lighting fixture 1 for visible light communication of Embodiment 1.

The visible light communication lighting device 1a includes a timer 19 that performs timer counting instead of the brightness sensor 14, the first storage unit 15, and the control unit 17 (see FIG. 1) of the first embodiment, and a timer count by the timer 19 a first storage unit 15a for storing a timer table (see FIG. 7) showing the relationship between the count value c and the constant current I ₁ of the current value a, the constant current circuit 12 on the basis of the timer count and the timer table And a control unit 17a to be controlled.

  The timer 19 is, for example, a multivibrator integrated into an IC or mounted as a hardware resource in a microcomputer. When the power source is turned on for the first time and the light source 10 emits light, the timer 19 starts counting. The timer count is continued while the light source 10 is emitting light. The count value c (see FIG. 7) of the timer count of the timer 19 is output to the control unit 17a. Since this timer count is performed at regular time intervals, the timer 19 counts the total light emission time of the light source 10 by performing the timer count, and outputs the count value c to the control unit 17a to thereby output the count of the light source 10. The total light emission time is output to the control unit 17a.

The first storage unit 15a stores a timer table shown in FIG. 7 instead of the target range B (see FIG. 5B) of the sensor voltage V of the first embodiment. This timer table has a constant current I ₁ corresponding to one-to-one for each count value c of the timer count by the timer 19 so that the light emission illuminance of the light source 10 (see FIG. 6) is within a certain range (FIG. ))). That is, this timer table sets the current value of the pulse current I ₂ (see FIG. 4B) to be supplied to the light source 10 every total light emission time of the light source 10 so that the light emission illuminance of the light source 10 is within a certain range. It is a data table shown. In addition, the 1st memory | storage part 15a is the same as that of the 1st memory | storage part 15 (refer FIG. 1) of Embodiment 1 in points other than the above.

Control unit 17a shown in FIG. 6, the power supply reads the timer table initial current value a ₁ (see FIG. 7) a constant current I ₁ of the first storage unit 15a simultaneously turned on, the read current value a ₁ is output to the constant current circuit unit 12 to change the current value a of the constant current I ₁ to a ₁ . Thereafter, the control unit 17a reads a current value a of the constant current I ₁ from the timer table according to the count value c of the timer count by the timer 19, and outputs the read current value a constant current circuit unit 12. Specifically, the count value c reaches c ₁ a current value a of the constant current I ₁ and a _2, the count value c reaches c ₂ a current value a of the constant current I ₁ and a _3, count value c changes to reach _{c 3} a current value a constant current _{I 1} to _{a 4.} Since the constant current I ₁ becomes a pulse current I ₂ (see FIG. 4B) having the same amplitude value as the current value a by the signal oscillation unit 13, the control unit 17 a is based on the total light emission time of the light source 10 and the data table. Thus, the current value of the supply current (pulse current I ₂ ) to the light source 10 is controlled. With the above operation, the control unit 17a controls the light source 10 so that the light emission illuminance of the light source 10 at least during non-communication is within a certain range. The control unit 17a is the same as the control unit 17 of the first embodiment except for the points described above.

  Here, the count value c of the timer count is stored in the first storage unit 15a at a fixed timing by the control unit 17a, and even when the power is turned on again after the power is turned off and the light source 10 stops emitting light. The timer count can be restarted from the count value c before the power is turned off.

Next, the operation of the visible light communication illumination system according to the second embodiment will be described with reference to FIGS. First, when the lighting device 1a for visible light communication shown in FIG. 6 is turned on, the control unit 17a outputs an initial current value a ₁ (see FIG. 7) of the constant current I ₁ to the constant current circuit unit 12, and the constant current When the circuit unit 12 outputs the constant current I ₁ having the current value a ₁ , the light source 10 emits visible light (see FIG. 8A). Further, the timer 19 starts timer counting when the power is turned on. The control unit 17a monitors the count value c of the timer count, and when this count value c reaches each of the count values c _{1 to} c ₅ of the timer table (t ₂₁ , t ₂₂ , t ₂₃ , t ₂₄ , t ₂₅ ), the current value a of the constant current I ₁ is changed to a _{2 to} a ₅ by controlling the constant current circuit unit 12. For example, although the count value c is up to _{c 1} below are powered by an initial current value _{a 1,} the time and the _{t 21} the count value c reaches _{c 1} (see FIG. 8 (b)), the timer table (FIG. follow the 7 reference), to change the current value a constant current _{I 1} to _{a 2} reference (FIG. 8 (c)). Thereby, the luminous flux of the light source 10 is corrected (see FIG. 8A).

Above, according to the second embodiment, a current value a of the control section 17a controls the constant current circuit 12 a constant current I ₁ shown in FIG. 6, the timer count and the first storage unit 15a by the timer 19 stores By making a change based on the timer table that has been set, the light flux decline of the light source 10 is predicted in advance for every total light emission time of the light source 10, and a current with a current value set is supplied to the light source 10 based on this prediction. Can do. Thereby, the luminous flux of the light source 10 can be kept almost constant, and the communication distance and communication range of visible light communication can be kept within a certain range for a long time with respect to the initial state while the receiver 2 is kept as it is. Can do.

It is a block diagram which shows the structure of the visible light communication illumination system which concerns on Embodiment 1 of this invention. It is an external view of the lighting fixture for visible light communication which concerns on the same as the above. It is a figure which shows the emitted light beam of the light source which concerns on the same as the above. The structure of the lighting fixture for visible light communication which concerns on the same as the above is demonstrated, Comprising: (a) is a time chart of a constant current, (b) is a time chart of a pulse current, (c) is a time chart of the emitted light beam of a light source. , (D) is a sensor voltage time chart. The operation of the illuminating device for visible light communication according to the above will be described, wherein (a) is a time chart of luminous flux of the light source, (b) is a time chart of sensor voltage, and (c) is a time chart of constant current. It is. It is a block diagram which shows the structure of the lighting fixture for visible light communication which concerns on Embodiment 2 of this invention. It is a figure which shows the timer table memorize | stored in the 1st memory | storage which concerns on the same as the above. The operation of the luminaire for visible light communication according to the above will be described, wherein (a) is a time chart of the luminous flux of the light source, (b) is a time chart of the count value of the timer count, and (c) is a constant current. It is a time chart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Lighting fixture 10 for visible light communication Light source 12 Constant current circuit part 13 Signal oscillation part 14 Brightness sensor 15, 15a First memory | storage part 17, 17a Control part 19 Timer 2 Receiver I ₁ Constant current I ₂ Pulse current V Sensor voltage

Claims (2)

A light source that emits visible light;
Transmission means for switching on and off the light source based on transmission information and transmitting the transmission information;
Lighting control means for controlling the light source so that the light emission illuminance of the light source falls within a predetermined range ,
A timer for measuring the total light emission time of the light source;
Storage means for storing a data table indicating a current value of a current supplied to the light source for each of the total light emission times so that the light emission illuminance falls within the predetermined range ;
Visible light characterized in that the lighting control means controls the current value of the current supplied to the light source based on the total light emission time counted by the timer and the data table stored in the storage means. Communication lighting equipment. A lighting fixture for visible light communication according to claim 1,
A receiver that receives visible light from the lighting device for visible light communication and receives transmission information;
Visible light communication illumination system comprising: a.

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