JP6883785B2 - Lighting devices, lighting fixtures and signboards - Google Patents

Description

The present invention relates to a lighting device for applying an electric current to a light emitting element such as an LED, a lighting device including a lighting device, and a signboard including the lighting device, and more particularly to a lighting device including a modulation circuit for visible light communication.

In recent years, a lighting device that applies a current to a light emitting element such as an LED has been proposed to include a modulation circuit for visible light communication (see, for example, Patent Document 1). With such a lighting device, the lighting device also becomes a data communication device, and a convenient wireless environment is constructed.

According to the lighting device of Patent Document 1, a series circuit of the resistor and the switch element is added so as to be connected in parallel to the resistor connected in series with the LED. As a result, a circuit for visible light communication can be easily added to the lighting device.

Japanese Unexamined Patent Publication No. 2014-14119

However, in the lighting device of Patent Document 1, if an abnormal state occurs due to a poor connection between the lighting device and the LED, the LED may be destroyed. When the output path of the constant current source is disconnected due to a poor connection between the lighting device and the LED, the output voltage of the constant current source rises to the maximum. In this state, if the lighting device and the LED are reconnected (that is, detached) due to a poor connection between the lighting device and the LED, etc., due to discharge from the smoothing capacitor connected to the output terminal of the constant current source. , Excessive current may be applied to the LED and the LED may be destroyed.

Therefore, the present invention has been made in view of the above problems, and is a lighting device having a function of visible light communication, and even when an abnormality such as a connection failure of the light emitting element occurs, the light emitting element can be used. An object of the present invention is to provide a lighting device or the like that is suppressed from being destroyed.

In order to achieve the above object, the lighting device according to one embodiment of the present invention is a lighting device that applies a current to a light emitting element, and includes a constant current source and a capacitor connected to an output terminal of the constant current source. , The switch element connected in parallel with the capacitor and connected in series with the light emitting element, the modulation circuit that turns the switch element on and off based on the signal for visible light communication, and the current flowing through the switch element. It is provided with a constant current control circuit that controls a constant current to make the current flowing through the switch element constant when the value is equal to or higher than the first predetermined value. The switch element is a first transistor, and the constant current control circuit controls the constant current by controlling the voltage of the control terminal of the first transistor.

In order to achieve the above object, the luminaire according to one embodiment of the present invention includes a light emitting element and the lighting device for applying an electric current to the light emitting element.

In order to achieve the above object, the signboard according to one embodiment of the present invention is illuminated by a light emitting element, the lighting device for applying an electric current to the light emitting element, and at least one of characters and figures. It is provided with a display board for showing.

INDUSTRIAL APPLICABILITY The present invention provides a lighting device having a visible light communication function, in which the light emitting element is suppressed from being destroyed even when an abnormality such as a connection failure of the light emitting element occurs. Will be done.

Circuit diagram of the lighting device according to the first embodiment Timing chart showing the operation of the lighting device according to the first embodiment Timing chart with time around time t1 in FIG. 2A Circuit diagram of the lighting device according to the second embodiment Timing chart showing the operation of the lighting device according to the second embodiment External view of the lighting equipment according to the application example of the third embodiment External view of the signboard according to the application example of the third embodiment

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that all of the embodiments described below show a specific example of the present invention. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, operation timings, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components. Moreover, each figure is not necessarily exactly illustrated. In each figure, substantially the same configurations are designated by the same reference numerals, and duplicate description will be omitted or simplified.

(Embodiment 1)
First, the lighting device according to the first embodiment will be described.

FIG. 1 is a circuit diagram of the lighting device 10 according to the first embodiment. The lighting device 10 is a device having a function of applying (that is, lighting) a current to the LED unit 14 and a function of visible light communication, and includes a constant current source 11 and a modulation unit 13.

The LED unit 14 is an example of a light emitting element that serves as a load for the lighting device 10. Here, the LED unit 14 is composed of a plurality of LEDs 1 to 5 connected to the lighting device 10 by a load wiring 15 and connected in series. The light emitting element is not limited to the LED, and may be another light emitting element such as an organic EL or an inorganic EL. Further, the LED unit 14 is not limited to a plurality of LEDs connected in series, and may be composed of one LED, a plurality of LEDs connected in parallel, or connected in series. A plurality of LED sets may be connected in parallel to each other.

The constant current source 11 is a power source that applies a constant current to the LED unit 14 that is a load, and raises the output voltage to the maximum voltage when the load is disconnected.

The modulation unit 13 has a function of a modulation circuit that turns on and off the transistor Q1 which is a switch element based on a signal for visible light communication, and a constant current mode of the transistor Q1 when the current flowing through the transistor Q1 is equal to or more than a first predetermined value. It also has the function of a constant current control circuit. Specifically, the modulation unit 13 is composed of a constant voltage regulator REG1, a microcomputer (microcomputer) MCU1, capacitors C1 and C2, transistors Q1 to Q4, resistors R1, and R3 to R6.

The transistor Q1 is a switch element for visible light communication, is connected in parallel with the capacitor C1, and is connected in series with the LED unit 14. The transistor Q1 is, for example, a MOSFET.

The capacitor C1 is a smoothing capacitor connected to the output terminals of the constant current source 11 (that is, between the two output terminals). In the modulation unit 13, the transistor Q1 is periodically turned on and off as a switch element for visible light communication. During the off period of the transistor Q1, the output voltage of the constant current source 11 rises because the current path is cut off. A capacitor C1 is provided in order to suppress the amount of increase. The capacitance of the capacitor C1 is preferably a value such that the amount of increase ΔVF of the output voltage during the off period of the transistor Q1 is 30% or less of the forward voltage VF of the LED unit 14. Specifically, when the off period Toff is 208 μsec, the output current Iout = 0.7A, and the forward voltage VF = 15V, the amount of increase ΔVF is 4.5V from ΔVF = 15V × 0.3 = 4.5V. It becomes. Therefore, the minimum capacitance C1min of the capacitor C1 is 32.4 μF from C1min = Toff × Iout / ΔVF = 208 μsec × 0.7 A / 4.5 V≈32.4 μF. Therefore, the capacitance of the capacitor C1 is set to, for example, 33 μF or more.

The constant voltage regulator REG1 is a circuit module that generates a constant voltage power supply voltage for operating the circuit inside the modulation unit 13 from the output voltage of the constant current source 11. The constant voltage regulator REG1 is, for example, a small switching regulator or a series regulator that outputs a power supply voltage of 5 V.

The microcomputer MCU1 is a microcomputer that operates with the power supply voltage generated by the constant voltage regulator REG1. The microcomputer MCU1 is composed of, for example, a ROM for holding a program, a RAM as a temporary storage area, a processor for executing the program, input / output circuits such as an A / D converter and a D / A converter, a counter / timer, and the like. It is an LSI. The microcomputer MCU1 functions as a part of the modulation circuit. Specifically, the microcomputer MCU1 outputs a drive signal for turning on / off the transistor Q1 based on the signal for visible light communication from the output terminal SIG according to the built-in program. The signal for visible light communication is a fixed character string determined by a built-in program, a character string that can change dynamically, or the like.

The resistor R6, the transistor Q5, the resistor R5, the transistors Q3 and Q4 are drive circuits for driving the gate of the transistor Q1 and form a part of the modulation circuit. This drive circuit charges and discharges the gate-source capacitance of the transistor Q1 so that the transistor Q1 is turned on and off according to the drive signal from the microcomputer MCU1. Specifically, when the drive signal from the microcomputer MCU1 is HIGH, the transistor Q5 is turned on, so that the transistor Q3 is turned off and the transistor Q4 is turned on. As a result, the gate of the transistor Q1 is discharged via the transistor Q4 and the resistor R4, so that the gate potential of the transistor Q1 becomes 0V and the transistor Q1 is turned off. On the other hand, when the drive signal from the microcomputer MCU1 is LOW, the transistor Q5 is turned off, so that the transistor Q3 is turned on and the transistor Q4 is turned off. As a result, the gate of the transistor Q1 is charged via the transistor Q3 and the resistor R4, so that the gate potential of the transistor Q1 becomes HIGH and the transistor Q1 is turned on. When the transistor Q1 is turned on and off by the drive signal from the microcomputer MCU1, the digital optical code for visible light communication is superimposed on the light emitted from the LED unit 14. The resistor R4 is a resistor that limits the charging / discharging of the gate of the transistor Q1. By adjusting the on / off speed of the transistor Q1 by the resistor R4, noise at the time of switching of the transistor Q1 can be suppressed.

The capacitor C2, the transistor Q2, the resistors R3 and R1 perform constant current control for making the current flowing through the transistor Q1 constant when the current flowing through the transistor Q1 (that is, the drain current) is equal to or higher than the first predetermined value. The constant current control circuit 12 is configured. The first predetermined value is the maximum value that can be tolerated as the current flowing through the LED unit 14, and is, for example, 2A. Since the current flowing through the transistor Q1 flows through the resistor R1 connected in series with the transistor Q1, a voltage corresponding to the current flowing through the transistor Q1 is generated across the resistor R1. Since the voltage is applied between the base and the emitter of the transistor Q2, when the threshold voltage Vbe of the transistor Q2 is exceeded, the transistor Q2 is turned on and the gate potential of the transistor Q1 is lowered. The transistor Q2 is an example of a second transistor that controls the voltage of the control terminal of the transistor Q1 depending on the voltage generated in the resistor R1. The capacitor C2 is provided for control phase compensation. Normally, the value of the resistor R1 is set so that the voltage across the resistor R1 does not exceed the threshold voltage Vbe of the transistor Q2. When an overcurrent flows through the LED unit 14, the voltage generated across the resistor R1 becomes large, so that the current flowing through the transistor Q2 becomes large, and the transistor Q1 is controlled in the direction of being forcibly turned off.

Next, the operation of the lighting device 10 according to the first embodiment configured as described above will be described.

FIG. 2A is a timing chart showing the operation of the lighting device 10 according to the first embodiment. In this figure, the output voltage Vdc of the constant current source 11, the current Iout flowing through the LED unit 14, and the gate-source voltage Vgs (Q1) of the transistor Q1 are shown from the top.

Until time t0, the lighting device 10 is operating normally. The microcomputer MCU1 controls to periodically turn on / off the transistor Q1 based on the signal for visible light communication (see the gate-source voltage Vgs (Q1)), and as a result, the current Iout flowing through the LED unit 14 is The current is intermittent. The output voltage Vdc is stabilized by the capacitor C1.

It is assumed that at time t0, the LED unit 14 is disconnected from the lighting device 10 due to poor contact between the load wiring 15 and the LED unit 14, and the current path is disconnected. Then, the current Iout flowing through the LED unit 14 becomes zero, the constant current source 11 raises the output voltage Vdc, and the capacitor C1 is charged. The microcomputer MCU1 continues the control to turn on / off the transistor Q1 (see the gate-source voltage Vgs (Q1)).

It is assumed that at time t1, the LED unit 14 is reconnected to the lighting device 10 and the current path is conducted due to the elimination of poor contact between the load wiring 15 and the LED unit 14. In this state, the output voltage Vdc is large and the capacitor C1 is charged. Therefore, when the current path is conducted, a large current flows through the LED unit 14 when the transistor Q1 is turned on. At this time, the constant current control circuit 12 composed of the resistor R1 and the like detects that the current flowing through the transistor Q1 is equal to or higher than the first predetermined value, and the current flowing through the transistor Q1 becomes a constant current (current Ipk). Is controlled. That is, the gate-source voltage Vgs (Q1) of the transistor Q1 is lowered, and the increase in the current flowing through the LED unit 14 is suppressed. The output voltage Vdc rapidly decreases due to the occurrence of the load current.

At time t2, the output voltage Vdc drops to the normal level, the current flowing through the LED unit 14 also reaches the normal level, and the constant current control by the constant current control circuit 12 is canceled.

FIG. 2B is a timing chart in which the time t1 in FIG. 2A is enlarged in time. More specifically, a timing chart is shown before and after the period (time t10 to t13 in FIG. 2B) in which the transistor Q5 is first turned off after the LED unit 14 is reconnected to the lighting device 10 at time t1 in FIG. 2A. .. In this figure, from the top, the collector voltage Vce (Q5) of the transistor Q5, the gate-source voltage Vgs (Q1) of the transistor Q1, and the current Iout flowing through the LED unit 14 are shown.

At time t10, the transistor Q5 is turned off by the drive signal from the output terminal SIG of the microcomputer MCU1, so that the collector voltage Vce (Q5) of the transistor Q5 becomes HIGH. As a result, the transistor Q3 is turned on, and the gate-source voltage Vgs (Q1) of the transistor Q1 rises.

At time t11, the gate-source voltage Vgs (Q1) of the transistor Q1 reaches the threshold voltage of the transistor Q1, and the current Iout flowing through the LED unit 14 rises.

At time t12, in the constant current control circuit 12, the voltage across the resistor R1 becomes equal to or higher than the threshold voltage Vbe of the transistor Q2 due to the current Iout flowing through the resistor R1, and the transistor Q2 starts to turn on. When the transistor Q2 is turned on, the gate-source voltage Vgs (Q1) of the transistor Q1 decreases with the voltage Vgs1 as a peak. The gate-source voltage Vgs (Q1) of the transistor Q1 is feedback-controlled by the transistor Q2 so that the voltage generated in the resistor R1 becomes the threshold voltage Vbe of the transistor Q2, and is stabilized at the voltage Vgs2. As a result, from time t12 to time t13, the transistor Q2 operates in the constant current mode, and the current Ipk flows.

At time t13, the transistor Q5 is turned on by the drive signal from the output terminal SIG of the microcomputer MCU1, so that the collector voltage Vce (Q5) of the transistor Q5 becomes LOW. As a result, the transistor Q4 is turned on, the gate-source voltage Vgs (Q1) of the transistor Q1 becomes approximately 0V, and the current Iout flowing through the LED unit 14 becomes zero.

As described above, the lighting device 10 according to the present embodiment is a device that applies a current to the LED unit 14, and is a constant current source 11, a capacitor C1 connected to an output terminal of the constant current source 11, and a capacitor. A transistor Q1 connected in parallel with C1 and connected in series with the LED unit 14, a modulation circuit (microcomputer MCU1 of the modulation unit 13, etc.) that turns the transistor Q1 on and off based on a signal for visible light communication, and a transistor. A constant current control circuit 12 that controls a constant current to make the current flowing through the transistor Q1 a constant current when the current flowing through the Q1 is equal to or higher than the first predetermined value is provided.

As a result, even if an abnormality (that is, attachment / detachment) occurs in which the LED unit 14 and the lighting device 10 are disconnected and reconnected during lighting due to a poor connection or the like, the current flowing through the transistor Q1 is the first. After the value exceeds a predetermined value, the current becomes constant. Therefore, it is possible to prevent the LED unit 14 from being destroyed by applying an excessive current to the LED unit 14.

Further, the switch element used for visible light communication is the first transistor (that is, transistor Q1), and the constant current control circuit 12 controls the constant current by controlling the voltage of the control terminal of the transistor Q1.

As a result, the switch element for visible light communication is also used for constant current control, and the circuit of the lighting device 10 is made compact.

Further, the constant current control circuit 12 is a second transistor (that is, transistor Q2) that controls the voltage of the control terminal of the transistor Q1 depending on the resistor R1 connected in series with the transistor Q1 and the voltage generated in the resistor R1. including.

As a result, the constant current control circuit 12 is realized with a simple configuration using the resistor R1 and the transistor Q2.

(Embodiment 2)
Next, the lighting device according to the second embodiment will be described.

FIG. 3 is a circuit diagram of the lighting device 10a according to the second embodiment. The lighting device 10a is a device having a function of applying a current (that is, lighting) to the LED unit 14 and a function of visible light communication, as in the first embodiment, and is a constant current source 11 and a modulation device. A unit 13a is provided. The lighting device 10a basically has the function of the lighting device 10 of the first embodiment, but the configuration of the modulation unit 13a is different from that of the first embodiment. That is, the modulation unit 13a newly has a bypass circuit 16 with respect to the modulation unit 13 of the first embodiment, and further, the constant current control having a different circuit configuration instead of the constant current control circuit 12 of the first embodiment. It differs from the first embodiment in that it has a circuit 12a. Hereinafter, the points different from those of the first embodiment will be mainly described.

The bypass circuit 16 is a circuit connected to the output terminal of the constant current source 11 to bypass the current flowing through the LED unit 14 and the transistor Q1, and includes resistors R10 to R14, transistors Q10 to Q12, and a constant voltage diode ZD10. Will be done. The bypass circuit 16 is a circuit connected in parallel to the LED unit 14 and the transistor Q1 as a whole, and bypasses the current when the current flowing through the LED unit 14 and the transistor Q1 is equal to or more than a second predetermined value. The second predetermined value is the maximum value that can be tolerated as the current flowing through the LED unit 14, and is, for example, 2A.

More specifically, the bypass circuit 16 is configured as follows. The transistor Q12 is a transistor for passing a bypass current, for example, a power MOSFET, and a transistor having a higher rated current than the transistor Q1 is generally used. The resistor R14 is provided for alleviating the power stress of the transistor Q12. The zener diode ZD10 is provided to limit the bias voltage when the gate of the transistor Q12 is biased via the resistor R13 when the transistor Q11 is off. The constant voltage diode ZD10 limits the gate potential of the transistor Q12 to, for example, 10V. The transistor Q11 is provided for signal inversion. The resistor R12 is a resistor for biasing the base of the transistor Q11.

The transistor Q10 is a current control transistor, and controls the base potential of the transistor Q12 so that the detection voltage generated by the load current flowing through the resistor R10 becomes the threshold voltage Vbe of the transistor Q10. The resistor R11 limits the base current of the transistor Q10. The capacitor C10 is provided for control phase compensation.

The constant current control circuit 12a basically has the same function as that of the first embodiment, that is, when the current flowing through the transistor Q1 is equal to or higher than the first predetermined value, the constant current that makes the current flowing through the transistor Q1 constant. Although it has a function of controlling, it is composed of a circuit different from that of the first embodiment. That is, the constant current control circuit 12a is composed of a resistor R1 connected in series with the transistor Q1 and a constant voltage diode ZD1 connected between one end of the resistor R1 and the control terminal (gate) of the transistor Q1. .. When the voltage generated in the resistor R1 by the current flowing through the resistor R1 becomes equal to or greater than the sum of the breakdown voltage of the constant voltage diode ZD1 and the threshold voltage of the transistor Q1 (that is, the first predetermined value), the gate potential of the transistor Q1 drops and the transistor The current flowing through Q1 is limited. That is, the transistor Q1 operates in the constant current mode.

Next, the operation of the lighting device 10a according to the second embodiment configured as described above will be described.

FIG. 4 is a timing chart showing the operation of the lighting device 10a according to the second embodiment. In this figure, from the top, the output voltage Vdc of the constant current source 11, the current Iout flowing through the LED unit 14, the gate-source voltage Vgs (Q1) of the transistor Q1, and the current (that is, drain current) Id (that is, the drain current) flowing through the transistor Q12. Q12) is shown.

Until time t0, the lighting device 10a is operating normally. The microcomputer MCU1 controls to periodically turn on / off the transistor Q1 based on the signal for visible light communication (see the gate-source voltage Vgs (Q1)), and as a result, the current Iout flowing through the LED unit 14 is The current is intermittent. The output voltage Vdc is stabilized by the capacitor C1. The voltage generated in the resistor R10 is equal to or less than the threshold voltage Vbe of the transistor Q10, and as a result, the transistor Q10 is turned off, the transistor Q11 is turned on, and the transistor Q12 is turned off (see drain current Id (Q12)).

It is assumed that at time t0, the LED unit 14 is disconnected from the lighting device 10a due to poor contact between the load wiring 15 and the LED unit 14, and the current path is disconnected. Then, the current Iout flowing through the LED unit 14 becomes zero, the constant current source 11 raises the output voltage Vdc, and the capacitor C1 is charged. The microcomputer MCU1 continues the control to turn on / off the transistor Q1 (see the gate-source voltage Vgs (Q1)).

It is assumed that at time t1, the LED unit 14 is reconnected to the lighting device 10a and the current path is conducted due to the elimination of poor contact between the load wiring 15 and the LED unit 14. In this state, the output voltage Vdc is large and the capacitor C1 is charged. Therefore, when the current path is conducted, a large current flows through the LED unit 14 when the transistor Q1 is turned on. At this time, in the constant current control circuit 12a, the voltage generated in the resistor R1 becomes equal to or greater than the sum of the breakdown voltage of the constant voltage diode ZD1 and the threshold voltage of the transistor Q1 (that is, the first predetermined value), and the gate potential of the transistor Q1 drops. The current flowing through the transistor Q1 is limited. That is, the transistor Q1 operates in the constant current mode.

Further, in the bypass circuit 16, the voltage generated in the resistor R10 rises, the transistor Q10 turns on, the transistor Q11 turns off, the transistor Q12 turns on, and as a result, a bypass current flows through the resistor R14 through the transistor Q12. That is, the current flowing through the LED unit 14 and the transistor Q1 becomes equal to or higher than the second predetermined value, and the bypass current flows through the bypass circuit 16. Due to the flow of the bypass current, the electric charge of the capacitor C1 is discharged, and the output voltage Vdc drops rapidly.

At time t2, the output voltage Vdc drops to the normal level, the current flowing through the LED unit 14 also reaches the normal level, and the constant current control by the constant current control circuit 12a is canceled. Further, the transistor Q10 is turned off, the transistor Q11 is turned on, and the transistor Q12 is turned off, so that the bypass current due to the transistor Q12 disappears.

As described above, the lighting device 10a according to the present embodiment is a device that applies a current to the LED unit 14 as in the first embodiment, and is applied to the constant current source 11 and the output terminals of the constant current source 11. The connected capacitor C1, the transistor Q1 connected in parallel with the capacitor C1 and connected in series with the LED unit 14, and the modulation circuit (modulator 13) that turns the transistor Q1 on and off based on the signal for visible light communication. The microcomputer MCU1 and the like) and a constant current control circuit 12a that controls a constant current to make the current flowing through the transistor Q1 constant when the current flowing through the transistor Q1 is equal to or higher than the first predetermined value.

As a result, even if an abnormality (that is, attachment / detachment) occurs in which the LED unit 14 and the lighting device 10a are disconnected and reconnected during lighting due to a poor connection or the like, the current flowing through the transistor Q1 is the first. After the value exceeds a predetermined value, the current becomes constant. Therefore, it is possible to prevent the LED unit 14 from being destroyed by applying an excessive current to the LED unit 14.

Further, in the lighting device 10a according to the present embodiment, the constant current control circuit 12a is connected between the resistor R1 connected in series with the transistor Q1 and one end of the resistor R1 and the control terminal (gate) of the transistor Q1. Includes the Zener diode ZD1.

As a result, the switch element for visible light communication is also used for constant current control, and the circuit of the lighting device 10 is made compact. Further, the constant current control circuit 12a is realized by a simple configuration using the resistor R1 and the constant voltage diode ZD1.

Further, the lighting device 10a according to the present embodiment further includes a bypass circuit 16 that is connected to the output terminal of the constant current source 11 and bypasses the current flowing through the LED unit 14 and the transistor Q1. The bypass circuit 16 bypasses the current flowing through the LED unit 14 and the transistor Q1 when the current flowing through the LED unit 14 and the transistor Q1 is equal to or higher than the second predetermined value.

As a result, even if an abnormality occurs in which the LED unit 14 and the lighting device 10 are disconnected and reconnected during lighting due to a poor connection or the like, the current is bypassed from the constant current source 11 and the LED unit 14 is used. And the flow of overcurrent to the transistor Q1 is suppressed. Therefore, it is possible to prevent the LED unit 14 from being destroyed by applying an excessive current to the LED unit 14.

Further, in the first embodiment, when the capacitance of the capacitor C1 is large, the power stress on the transistor Q1 tends to be large, but the bypass circuit 16 of the present embodiment reduces the power stress.

Further, by absorbing the surge power by the resistor R14, the lighting device 10a can be designed without increasing the size of the transistor Q12.

(Embodiment 3)
Next, as the third embodiment, application examples of the lighting devices 10 and 10a according to the above embodiment will be described.

FIG. 5 is an external view of the luminaire 20 according to the application example of the third embodiment. The luminaire 20 is a spotlight installed on the ceiling, wall, pillar, or the like of a room, and includes a circuit box 21, a lamp body 22, and wiring 23. The circuit box 21 is a box that houses the lighting device 10 or 10a according to the above embodiment. The lamp body 22 houses an LED bulb as a light emitting element. The wiring 23 is an example of load wiring that electrically connects the circuit box 21 and the LED bulb housed in the lamp body 22.

Since such a lighting fixture 20 includes the lighting device 10 or 10a according to the above embodiment, lighting and visible light communication are performed at the same time. Further, even if an abnormal state such as attachment / detachment of the LED bulb to / from the lamp body 22 occurs during lighting due to poor connection or the like, it is possible to prevent the circuit elements constituting the lighting devices 10 and 10a from being destroyed. ..

In this figure, the spotlight is shown as the luminaire 20, but the luminaire according to the application example of the lighting device 10 or 10a is not limited to the spotlight. It may be a chandelier, a ceiling light, a stand, Japanese-style lighting, a bracket, a foot light, a pendant, a base light, a downlight, a kitchen light, a bathroom light, an exterior light, or the like.

FIG. 6 is an external view of the signboard 30 according to the application example of the third embodiment. The signboard 30 includes a housing 31 that houses an LED bulb (not shown) as a light emitting element and a lighting device 10 or 10a (not shown) according to the above embodiment in which a current is applied to the LED bulb. , The display board 32 is provided. The display board 32 is a display board that is illuminated from the back surface by an LED light bulb and shows at least one of characters and figures, and is, for example, a translucent resin substrate on which characters are engraved.

Since such a signboard 30 includes the lighting device 10 or 10a according to the above embodiment, the display of characters and the like on the display board 32 and visible light communication are performed at the same time. In visible light communication, for example, data indicating characters displayed on the display board 32 and / or data indicating the location where the signboard 30 is installed are superimposed on the illumination light and transmitted. Further, according to such a signboard 30, even if an abnormal state occurs in which the LED bulb and the lighting device 10 or 10a are disconnected and reconnected during lighting due to a poor connection or the like, the lighting device 10 is used. And the circuit elements constituting 10a are suppressed from being destroyed.

In the signboard 30 of FIG. 6, the LED as a light emitting element and the display board 32 are separate bodies, but they may be integrated. By arranging a plurality of LEDs side by side in the housing 31 and controlling the emission colors of the plurality of LEDs, the plurality of LEDs may be used as a display board to display at least one of characters and figures.

The lighting device, the luminaire, and the signboard according to the present invention have been described above based on the first to third embodiments, but the present invention is not limited to these embodiments. As long as the gist of the present invention is not deviated, various modifications that can be conceived by those skilled in the art are applied to the first to third embodiments, and other embodiments constructed by combining some components of the first to third embodiments are also available. , Included within the scope of the present invention.

For example, in the above embodiment, the capacitor C1 is provided in the modulation units 13 and 13a, but the position is not limited to this. If it is connected between the output terminals of the constant current source 11, it may be built in the constant current source 11 or may be connected at a position between the constant current source 11 and the modulation units 13 and 13a.

Further, in the second embodiment, the bypass circuit 16 is configured by a discrete circuit using transistors, but may be configured by using an operational amplifier.

Further, in the second embodiment, the bypass circuit 16 is provided in the modulation unit 13a, but the bypass circuit 16 is not limited to this position, and if it is connected between the output terminals of the constant current source 11, it can be connected to the constant current source 11. It may be built in, or may be connected at a position between the constant current source 11 and the modulation unit 13a.

10, 10a Lighting device 11 Constant current source 12, 12a Constant current control circuit 13, 13a Modulator (circuit including modulation circuit)
14 LED unit (light emitting element)
16 Bypass circuit C1 capacitor Q1 transistor (switch element)
20 Lighting equipment 30 Signboard 32 Display board

Claims (6)

A lighting device that applies an electric current to a light emitting element.
With a constant current source
A capacitor connected to the output terminal of the constant current source and
A switch element connected in parallel with the capacitor and connected in series with the light emitting element,
A modulation circuit that turns the switch element on and off based on a signal for visible light communication,
A constant current control circuit that controls a constant current to make the current flowing through the switch element constant when the current flowing through the switch element is equal to or higher than a first predetermined value is provided .
The switch element is a first transistor and
The constant current control circuit is a lighting device that controls the constant current by controlling the voltage of the control terminal of the first transistor. The constant current control circuit
A resistor connected in series with the switch element,
Lighting apparatus of claim 1 further comprising a second transistor for controlling the voltage of the control terminal of the first transistor depends on the voltage generated in the resistor. The constant current control circuit
A resistor connected in series with the switch element,
Lighting apparatus of claim 1 further comprising connected a constant voltage diode between a control terminal of the first transistor and one end of the resistor. Further, a bypass circuit connected to the output terminal of the constant current source and bypassing the current flowing through the light emitting element and the switch element is provided.
The bypass circuit according to any one of claims 1 to 3 for bypassing the current flowing through the light emitting element and the switch element when the current flowing through the light emitting element and the switch element is equal to or higher than a second predetermined value. The lighting device described. Light emitting element and
A lighting fixture comprising the lighting device according to any one of claims 1 to 4 , wherein a current is applied to the light emitting element. Light emitting element and
The lighting device according to any one of claims 1 to 4 , wherein a current is applied to the light emitting element.
A signboard illuminated by the light emitting element and comprising a display board showing at least one of characters and figures.

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