Patent Application
20220117056
The present invention relates to a lighting system including a dimmer apparatus and lighting equipment.
A conventional lighting system using various dimming control methods such as a phase dimmer control method, a PWM (Pulse Width Modulation) dimmer control method, a wireless dimmer control method, and a PLC (Power Line Communication) dimmer control method for adjusting brightness of an LED (Light Emitting Diode) lighting equipment has been known.
For example, Patent Document 1 discloses a lighting system that controls light while suppressing sudden voltage fluctuations generated by a phase control method by changing the conduction of a sinusoidal AC (Alternating Current) waveform for half a cycle for the purpose of reducing noise.
In addition, Patent Document 2 discloses a lighting system that controls light of lighting equipment by converting a sinusoidal wave AC voltage into a DC (Direct Current) voltage in advance by an AC-DC converter, superimposing transmitting data on the DC voltage, and decoding the transmitting data by the lighting equipment.
Further, Patent Document 3 discloses a lighting system including: a controller configured to perform power line communication; and a lighting control unit including a master unit configured to perform power line communication and lighting equipment capable of communicating with the master unit, for the purpose of enabling control using power line communication while suppressing an increase in equipment cost. In this case, the master unit and the lighting equipment communicate with each other by communication means different from the power line communication.
[Patent Document 1] Japanese Patent No. JP6170995B
[Patent Document 2] Japanese Patent Laid-open Publication No. JP2018-018764A
[Patent Document 3] Japanese Patent Laid-open Publication No. JP2019-169432A
However, in Patent Document 1, the lighting equipment requires a microcomputer and a memory as a control circuit, and this results in increase in the cost. In addition, since the sinusoidal AC waveform is applied to the light source, an AC-DC converter is required, and this results in being not suitable for miniaturization. Further, although it is not disclosed, since it is necessary to turn on the light source in a state where zero level is applied, it is expected that a bulk capacitor that is about twice as large as that in a normal AC-DC converter to which a sinusoidal AC waveform is applied is required. The bulk capacitor is one of the largest components of an AC-DC converter, and if the size of the bulk capacitor is about twice the original size, the size of lighting equipment further increases.
In addition, in Patent Document 2, the lighting equipment requires a microcomputer and a memory as a control circuit, which increases the cost. In addition, since the lighting equipment includes a DC-DC converter (step-down chopper), although the size of the DC-DC converter is smaller than that of an AC-DC converter, the DC-DC converter hinders miniaturization and increases costs. Further, although a bulk capacitor is required for the DC-DC converter, since the transmitting signal is a rectangular wave, it is assumed that a large inrush current occurs and causes noise. Therefore, in actual use, a large-sized noise filter is required, and this results in further increase in the costs and causes an increase in size.
Further, in Patent Document 3, a light adjuster requires a microcontroller circuit for converting input information from an input interface into a PLC signal. On the other hand, each LED lighting equipment requires a switching power supply circuit, which increases the size and costs, and also requires a microcontroller circuit to decode the PLC signal, which is costly. Further, the PLC signal includes a high-frequency component, which generates high-frequency noise and causes a malfunction of other devices.
An object of the present invention is to solve the above problems and to provide a lighting system having a simple structure, capable of being miniaturized, having less noise, and being easy to install as compared with the prior art.
According to one aspect of the present invention, there is provided a lighting system comprising a dimmer apparatus and lighting equipment that are connected to each other via a two-wire power supply line. The dimmer apparatus generates a DC voltage including a dimming PWM signal having a PWM amplitude corresponding to a dimming control signal, and outputs the DC voltage to the lighting equipment. The lighting equipment includes at least one light emitting element that emits light by a DC current based on the DC voltage; and a current control circuit. The second control circuit modulates the dimming PWM signal included in the DC voltage, and controls brightness of the light emitting element, so that a DC current corresponding to a duty ratio of a modulated dimming PWM signal flows through the light emitting element based on the duty ratio of the dimming PWM signal.
Therefore, the lighting system according to the present invention has a simple structure, can be miniaturized, has less noise, and is easy to install as compared with the prior art.
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. It is noted that the same or similar components are designated by the same reference numerals.
Embodiments according to the present invention have the following features in a lighting system capable of dimming or adjusting light.
(1) A dimming PWM signal is superimposed on a DC voltage generated in advance by an AC-DC converter, the DC voltage including the PWM signal is transmitted to lighting equipment via a two-wire power supply line, and the DC voltage is used as a power supply voltage of the lighting equipment.
(2) The lighting equipment is equipped with a light emitting element, which is, for example, a light emitting diode (LED), the PWM signal is rectified and demodulated by a low-pass filter, and the brightness of the light emitting element is controlled according to the duty ratio of the demodulated PWM signal.
The dimmer apparatus 1 generates a DC voltage including a PWM signal having a plurality of PWM amplitudes (hereinafter, referred to as amplitudes) corresponding to a predetermined dimming control signal Sc, based on an AC voltage Vac from an AC power supply 3, and outputs the DC voltage to the lighting equipment 2 via the two-wire power supply line 5. The lighting equipment 2 includes at least one light emitting element, for example, a series circuit of a plurality of LEDs, that has a forward voltage VF (meaning a voltage required to make the light emitting element emit light) lower than the DC voltage inputted from the dimmer apparatus 1, and emits light by a DC current based on the DC voltage. In this case, the lighting equipment 2 includes a current control circuit that demodulates the PWM signal included in the DC voltage, and controls the brightness of the light emitting element, so that the DC current corresponding to the duty ratio of the PWM signal flows through the light emitting element.
Referring to
Referring to
The control circuit 10 is, for example, a microcontroller, receives a dimming control signal having a predetermined dimming signal level from an input interface circuit installed on a wall surface, for example, turns on or off the MOS transistors Q1 and Q2 correspondingly to the dimming signal level of the dimming control signal to generate a PWM signal of 0 V to 1 V, and apply the PWM signal to the negative terminal of the AC-DC converter 11 as a reference voltage of the AC-DC converter 11. In this case, when the MOS transistor Q1 is turned on and the MOS transistor Q2 is turned off, the reference voltage of the AC-DC converter 11 is 0 V. In addition, when the MOS transistor Q1 is turned off and the MOS transistor Q2 is turned on, the reference voltage of the AC-DC converter 11 is 1 V.
The dimming power supply voltage V1 from the dimmer apparatus 1 configured as described above is a power supply voltage including a superimposed PWM signal that changes between 46 V and 47 V.
Referring to
Referring to
In this case, the reference voltage V2 at a connection between the resistance R1 and the capacitor C2 is applied to a positive power supply terminal of the comparator 21 in the subsequent stage, and is grounded to the negative terminal of the power supply voltage of the comparator 21.
In the voltage shift circuit 31 configured as described above, the resistance R1 allows a bias current to flow through the zener diode ZD1 based on the dimming power supply voltage V1 from the dimmer apparatus 1, so that the zener diode ZD1 generates a reference voltage V2 of 1.25 V. It is noted that the capacitor C2 connected in parallel with the zener diode ZD1 has a smoothing capacitance. In addition, the diodes D1 and D2 have a forward voltage VF of, for example, 0.5 V. The capacitor C1 shifts the level of the PWM amplitude of the dimming power supply voltage V1 to the voltage V3, and outputs the resulting voltage to a non-inverting input terminal of the comparator 21. Further, the resistance R2 is provided to limit an inrush current from the capacitor C1 to the diodes D1 and D2.
The signal voltage inputted to the non-inverting input terminal of the comparator 21 is clamped by the forward voltage VF of the diodes D1 and D2, so that signal voltage is the voltage V3 of the PWM signal that changes between 0.75 V and 1.75 V. Therefore, the voltage shift circuit 31 is configured to shift the voltage of the PWM signal included in the dimming power supply voltage V1 that changes between 46 V and 47 V to the voltage V3 of the PWM signal that changes between 0.75 V and 1.75 V.
The voltage V2 across the zener diode ZD1 is inputted to the inverting input terminal of the comparator 21. Therefore, the output voltage V4 of the comparator 21 is the voltage of the PWM signal that changes between 0 V and 1.25 V. Therefore, the voltage shift circuit 31 and the comparator 21 shift the voltage of the PWM signal included in the dimming power supply voltage V1 that changes between 46 V and 47 V to the voltage V4 of the PWM signal that changes between 0 V and 1.25 V.
The low-pass filter 32 is configured by connecting the resistance R3 and the capacitor C3 in an L shape, and smooths the output voltage V4 of the comparator 21 to generate a voltage V5.
The current control circuit 33 is a circuit that drives and controls the current of the light emitting element 23, and includes an operational amplifier 22, an N-channel MOS transistor Q11, and a resistance Rsns1. One end of the light emitting element 23 is connected to the positive electrode of the two-wire power supply line 5, and another end of the light emitting element 23 is connected to the negative electrode of the two-wire power supply line 5 grounded via the drain and source of the MOS transistor Q11 and the resistance Rsns1. In this case, the resistance Rsns1 is provided to detect a current IL1 flowing through the light emitting element 23, and the voltage across the resistance Rsns1 is proportional to the current ILL
The operational amplifier 22 applies the voltage obtained by subtracting the voltage across the resistance Rsns1 from the voltage V5 to the gate of the MOS transistor Q11, controls the gate voltage to be applied to the MOS transistor Q11, so that the voltage V5 and the voltage across the resistance Rsns1 substantially match each other. Therefore, assuming that the current flowing through the resistance Rsns1 is ILL the current IL1 is feedback-controlled to be as follows.
IL1=PWM signal duty ratio×1.25/Rsns1
Therefore, the operational amplifier 22, the MOS transistor Q1, and the resistance Rsns1 form a feedback control circuit that controls the current IL1 flowing through the light emitting element 23. It is noted that since the current IL1 flowing through the light emitting element 23 is sufficiently larger than the current flowing through the voltage shift circuit 31, a current IV1 flowing through the lighting equipment 2 is substantially equal to the current IL1.
The operation of the lighting equipment 2 configured as described above will be described below with reference to the timing chart of
As is clear from
IL1=20%×1.25 V/1.25Ω=200 mA.
In addition, the current IV1 is the input current to the lighting equipment 2, but the current IV1 almost matches the current ILL and it can be seen that there is almost no noise.
According to the lighting system according to the first embodiment configured as described above, the dimmer apparatus 1 generates the DC voltage V1 including the dimming PWM signal having a plurality of amplitudes corresponding to the dimming control signal, and outputs the DC voltage V1 to lighting equipment 2. In addition, the lighting equipment 2 includes:
the light emitting element 23 that has the forward voltage VF lower than the DC voltage V1 inputted from the dimmer apparatus 1 and emits light by the DC current IL1 based on the DC voltage V1; and a current control circuit that demodulates the dimming PWM signal included in the DC voltage V1 and controls the brightness of the light emitting element 23, so that the DC current IL corresponding to the duty ratio of the demodulated dimming PWM signal flows through the light emitting element 23.
Therefore, the lighting system according to the first embodiment has the following unique effects.
(1) Since the lighting equipment 2 does not require a control circuit such as a microcomputer and a memory and a bulk capacitor, the configuration is simple, the size can be reduced, and the noise is small as compared with the prior art.
(2) Since the dimmer apparatus 1 and the lighting equipment 2 are connected to each other via the two-wire power supply line 5, the construction is extremely easy.
Referring to
(1) The dimmer apparatus 1A is provided instead of the dimmer apparatus 1, and the specifics are as follows:
(1a) a control circuit 10A is provided instead of the control circuit 10; and
(1b) a MOS transistor Q3 and a DC-DC converter 13 are further provided.
(2) The lighting equipment 2A is provided instead of the lighting equipment 2, and the specifics are as follows:
(2a) a voltage shift circuit 31A is provided instead of the voltage shift circuit 31; and
(2b) a light emitting element 23A, a comparator 21A, a low-pass filter 32A, and a current control circuit 33A are further provided.
In particular, the lighting system according to the second embodiment has the following feature, as compared to the lighting system according to the first embodiment:
changing the dimming power supply voltage V1 including a PWM signal having two amplitudes to a dimming power supply voltage V8 including a PWM signal having three amplitudes, thereby driving and controlling two light emitting elements 23 and 23A. The differences will be described below.
In the dimmer apparatus 1A of
The control circuit 10A receives the dimming control signal, turns on one of the MOS transistors Q1 and Q2, and Q3 so as to correspond to the dimming signal level of the dimming control signal, turns off the other to generate a PWM signal of 0 V, 1 V or 2 V, and applies the PWM signal to the negative terminal of the AC-DC converter 11 as a reference voltage of the AC-DC converter 11. In this case,
(1) when the MOS transistor Q1 is turned on and the MOS transistors Q2, Q3 are turned off, the reference voltage of the AC-DC converter 11 is 0 V;
(2) in addition, when the MOS transistor Q2 is turned on and the MOS transistors Q1 and Q3 are turned off, the reference voltage of the AC-DC converter 11 is 1 V; and
(3) further, when the MOS transistor Q3 is turned on and the MOS transistors Q1 and Q2 are turned off, the reference voltage of the AC-DC converter 11 is 2 V.
The dimming power supply voltage V8 from the dimmer apparatus 1A configured as described above is a power supply voltage including a superimposed PWM signal that changes between 46 V, 47 V, and 48 V.
The lighting equipment 2A of
Referring to
In this case, the reference voltage V2 at a connection between the resistance R1 and the capacitor C2 is applied to a positive power supply terminal of the comparator 21 and 21A in the subsequent stage, and is grounded to the negative terminal of the power supply voltage of the comparator 21 and 21A.
In the voltage shift circuit 31A configured as described above, the resistance R1 allows a bias current to flow through the zener diode ZD1 based on the dimming power supply voltage V8 from the dimmer apparatus 1A, so that the zener diode ZD1 generates a reference voltage V2 of 1.25 V. It is noted that the capacitor C2 connected in parallel with the zener diode ZD1 has a smoothing capacitance. In addition, the diodes D2 and D3 have a forward voltage VF of, for example, 0.5 V. The capacitor C1 level-shifts the PWM amplitude of the dimming power supply voltage V8 to the voltage V3, and outputs the voltage V3 to a non-inverting input terminal of the comparator 21 and an inverting input terminal of the comparator 21A. In this case, the non-inverting input terminal of the comparator 21A is grounded. Further, the resistance R2 is provided to limit an inrush current from the capacitor C1 to the diodes D3 and D2.
The signal voltage inputted to the non-inverting input terminal of the comparator 21 is clamped by the forward voltage VF of the diodes D2 and D3, so that signal voltage is the voltage V3 of the PWM signal that changes between −0.5 V and 1.75 V. Therefore, the voltage shift circuit 31A shifts the voltage of the PWM signal included in the dimming power supply voltage V1 that changes between 46 V and 47 V to the voltage V3 of the PWM signal that changes between −0.5 V and 1.75 V.
The voltage V2 across the zener diode ZD1 is inputted to the inverting input terminal of the comparator 21. Therefore, the output voltage V4 of the comparator 21 is the voltage of the PWM signal that changes between 0 V and 1.25 V. In addition, the voltage V3 is inputted to the non-inverting input terminal of the comparator 21A. Therefore, the comparator 21A outputs an output voltage of 1.25 V when the voltage V3 becomes equal to or lower than the reference voltage (0 V). Therefore, the voltage shift circuit 31A and the comparators 21 and 21A shift the voltage of the PWM signal that is included in the dimming power supply voltage V1 and changes between 47 V and 48 V to the voltage V4 of the PWM signal that changes between 0 V and 1.25 V, while shifting the voltage of the PWM signal that changes between 46 V and 47 V to the voltage V6 of the PWM signal that changes between 0 V and 1.25 V.
In a manner similar to that of the low-pass filter 32, the low-pass filter 32A is configured by connecting the resistance R4 and the capacitor C4 in an L shape, and smooths the output voltage V6 of the comparator 21A to generate a voltage V7. In this case, the voltage V7 is the duty ratio of the PWM signal x 1.25 V.
The current control circuit 33A is a circuit that drives and controls the current of the light emitting element 23A, and includes an operational amplifier 22A, an N-channel MOS transistor Q12, and a resistance Rsns2, in a manner similar to that of the current control circuit 33. One end of the light emitting element 23A is connected to the positive electrode of a two-wire power supply line 5, and another end of the light emitting element 23A is connected to the negative electrode of the two-wire power supply line 5 grounded via the drain and source of the MOS transistor Q12 and the resistance Rsns2. In this case, the resistance Rsns2 is provided to detect a current IL2 flowing through the light emitting element 23A, and the voltage across the resistance Rsns2 is proportional to the current IL2.
The operational amplifier 22A applies the voltage obtained by subtracting the voltage across the resistance Rsns2 from the voltage V7 to the gate of the MOS transistor Q12, controls the gate voltage to be applied to the MOS transistor Q12, so that the voltage V7 and the voltage across the resistance Rsns2 substantially match. Therefore, assuming that the current flowing through the resistance Rsns2 is IL2, the current IL2 is feedback-controlled to be as follows:
IL2=PWM signal duty ratio×1.25/Rsns2.
Therefore, the operational amplifier 22A, the MOS transistor Q2, and the resistance Rsns2 form a feedback control circuit that controls the current IL2 flowing through the light emitting element 23A. It is noted that since the current IL2 flowing through the light emitting element 23A is sufficiently larger than the current flowing through the voltage shift circuit 31A, the current IV8 flowing through the lighting equipment 2A is substantially equal to the sum of the current IL1 and the current IL2.
In the lighting equipment 2A of
In this case, when the voltage V3 is clamped at the maximum of 1.75 V,
(A) when the voltage V8 is 48 V, the voltage V3 is 1.75 V,
(B) when the voltage V8 is 47 V, the voltage V3 is 0.75 V, and
(C) when the voltage V8 is 46 V, the voltage V3 is −0.25 V.
Therefore,
(A) when the voltage V8 is 48 V, the output voltage of the comparator 21 is 1.25 V, and
(C) when the voltage V8 is 46 V, the output voltage of the comparator 21A is 1.25 V.
In addition, when the voltage V3 is clamped at the minimum of −0.5 V,
(A) when the voltage V8 is 46 V, the voltage V3 is −0.5 V,
(B) when the voltage V8 is 47 V, the voltage V3 is 0.5 V, and
(C) when the voltage V8 is 48 V, the voltage V3 is 1.5 V.
Therefore,
(C) when the voltage V8 is 48 V, the output voltage of the comparator 21 is 1.25 V, and
(A) when the voltage V8 is 46 V, the output voltage of the comparator 21A is 1.25 V.
In the lighting equipment 2A of
The operation of the lighting equipment 2A configured as described above will be described below with reference to the timing chart of
As is clear from
IL1=20%×1.25 V/0.625Ω=400 mA; and
IL2=10%×1.25 V/0.625Ω=200 mA.
In the second embodiment, since the control voltages of the two light emitting elements 23 and 23A are included in one PWM signal, the duty ratio cannot be set to 100% as in the first embodiment. However, by setting the resistance values of the resistances Rsns1 and Rsns2 to half of those of the first embodiment, it is possible to cause the same current as in the case where the duty ratio in the first embodiment is 100% to flow even when each of resistance values of the resistances Rsns1 and Rsns2 is 50%. Further, it can be seen that there is almost no noise at the current IV8.
According to the lighting system according to the second embodiment configured as described above, the dimmer apparatus 1A generates the DC voltage V8 including the dimming PWM signal having three amplitudes corresponding to the dimming control signal, and outputs the DC voltage V8 to the lighting equipment 2A. In addition, the lighting equipment 2A includes:
the light emitting elements 23 and 23A, that have the forward voltage VF lower than the DC voltage V8 inputted from the dimmer apparatus 1A and emit light by the DC currents IL1 and 112 based on the DC voltage V8; and
a current control circuit, that demodulates the dimming PWM signal included in the DC voltage V8, and controls the brightness of the light emitting elements 23 and 23A, so that the DC currents IL1 and IL2 further corresponding to two duty ratios of the dimming PWM signal corresponding to two amplitudes of the modulated PWM signal flow through the light emitting elements 23 and 23A.
Therefore, the lighting system according to the second embodiment has the following unique effects.
(1) Since the lighting equipment 2A does not require a control circuit such as a microcomputer and a memory and a bulk capacitor, the configuration is simple, the size can be reduced, and the noise is small as compared with the prior art.
(2) Since the dimmer apparatus 1A and the lighting equipment 2A are connected to each other via the two-wire power supply line 5, the construction is extremely easy.
(3) Since the PWM signal has three amplitude levels as in the second embodiment, each LED of two colors can be controlled, so that the color adjustment (toning) can be performed.
Referring to
(1) The dimmer apparatus 1B is provided instead of the dimmer apparatus 1A, and the specifics are as follows:
(1a) a control circuit 10B is provided instead of the control circuit 10A; and
(1b) a MOS transistor Q4 and a DC-DC converter 14 are further provided.
(2) The lighting equipment 2B is provided instead of the lighting equipment 2A, and the specifics are as follows:
(2a) a voltage shift circuit 31B is provided instead of the voltage shift circuit 31A; and
(2b) three light emitting elements 51 to 53, comparators 61 to 63, low-pass filters 71 to 73, and current control circuits 41 to 43 are provided.
In particular, the lighting system according to the third embodiment has the following feature, as compared to the lighting system according to the second embodiment:
changing the dimming power supply voltage V8 including a PWM signal having three amplitudes to a dimming power supply voltage V31 including a PWM signal having four amplitudes to drive, thereby controlling three light emitting elements 51 to 53. The differences will be described below.
In the dimmer apparatus 1B of
The control circuit 10B receives the dimming control signal, turns on either one of the MOS transistors Q1, Q2, Q3, and Q4 correspondingly to the dimming signal level of the dimming control signal, turns off the other to generate a PWM signal of 0 V, 1 V, 2 V, or 3 V, and then, applies the PWM signal to the negative terminal of the AC-DC converter 11 as a reference voltage of the AC-DC converter 11.
(1) When the MOS transistor Q1 is turned on and the MOS transistors Q2, Q3, and Q4 are turned off, the reference voltage of the AC-DC converter 11 is 0 V.
(2) When the MOS transistor Q2 is turned on and the MOS transistors Q1, Q3, and Q4 are turned off, the reference voltage of the AC-DC converter 11 is 1 V.
(3) When the MOS transistor Q3 is turned on and the MOS transistors Q1, Q2, and Q4 are turned off, the reference voltage of the AC-DC converter 11 is 2 V.
(4) When the MOS transistor Q4 is turned on and the MOS transistors Q1, Q2, and Q3 are turned off, the reference voltage of the AC-DC converter 11 is 3 V.
The dimming power supply voltage V31 from the dimmer apparatus 1B configured as described above is a power supply voltage including a superimposed PWM signal that changes between 45 V, 46 V, 47 V, and 48 V.
The lighting equipment 2B of
Referring to
In addition, the reference voltage V34 is inputted to the inverting input terminal of the comparator 61. Further, the voltage V33 at the connection of the diodes D31 and D32 is applied to a non-inverting input terminal of the comparator 61 and each inverting input terminal of the comparators 62 and 63. The voltage V32 at the connection of the zener diodes ZD32 and ZD31 is applied to the non-inverting input terminal of the comparator 63, the positive power supply terminal of each of the comparators 61 to 63, and the positive power supply terminal of a NOR Gate 64.
The low-pass filter 71 is configured by connecting the resistance R33 and the capacitor C33 in an L shape, smooths the output voltage V35 of the comparator 61 to generate a voltage V36, and outputs the voltage V36 to the non-inverting input terminal of an operational amplifier 81. The low-pass filter 72 is configured by connecting the resistance R34 and the capacitor C34 in an L shape, smooths the output voltage V37 of the comparator 62 to generate a voltage V38, and outputs the voltage V38 to the non-inverting input terminal of the operational amplifier 82. The low-pass filter 73 is configured by connecting the resistance R35 and the capacitor C35 in an L shape, smooths the voltage inputted from the output voltage V41 of the comparator 63 via the NOR gate 64 to generate a voltage V40, and outputs the voltage V40 to the non-inverting input terminal of the operational amplifier 83. It is noted that the voltage V41 and the voltage V37 are applied to the NOR gate 64, and the NOR gate 64 is provided to drive and control the light emitting element 54 with the voltage obtained by the operation result of the negative OR of these voltages.
The current control circuit 41 is a circuit that drives and controls the current of the light emitting element 51, and includes an operational amplifier 81, an N-channel MOS transistor Q31, and a resistance Rsns31, in a manner similar to that of the current control circuit 33 of
It is noted that the light emitting elements 51 to 53 of the lighting equipment 2B are, for example, a red LED, a green LED, and a blue LED, which are capable of emitting three colors, and it is possible to provide a color adjusting (toning) function in combination with light adjustment by adjusting the ratio of the current flowing through the light emitting elements 51 to 53.
In the timing chart of
In the present embodiment, since the drive currents of the light emitting elements 51 to 53 are adjusted with the duty ratios of 48 V, 46 V and 45 V of the PWM signal, each duty ratio cannot be set to 100%. However, by setting the resistance value of each of the resistances Rsns31, Rsns32, Rsns33 to ⅓ of the resistance value of
According to the lighting system according to the third embodiment configured as described above, the dimmer apparatus 1B generates the DC voltage V31 including the dimming PWM signal having four amplitudes corresponding to the dimming control signal, and outputs the DC voltage V31 to lighting equipment 2B. In addition, the lighting equipment 2B includes:
the light emitting elements 51 to 53, that have the forward voltage VF lower than the DC voltage V31 inputted from the dimmer apparatus 1B and emit light by the DC currents IL31, IL32, and IL33 based on the DC voltage V31; and a current control circuit, that demodulates the dimming PWM signal included in the DC voltage V31 and controls the brightness of the light emitting elements 51 to 53, so that the DC currents IL31, IL32, and IL33 further corresponding to the duty ratio of the dimming PWM signal corresponding to three amplitudes of the modulated PWM signal flow through the light emitting elements 51 to 53A.
Therefore, the lighting system according to the third embodiment has the following unique effects.
(1) Since the lighting equipment 2B does not require a control circuit such as a microcomputer and a memory and a bulk capacitor, the configuration is simple, the size can be reduced, and the noise is small as compared with the prior art.
(2) Since the dimmer apparatus 1B and the lighting equipment 2B are connected to each other via a two-wire power supply line 5, the construction is extremely easy.
(3) Since the PWM signal has four amplitude levels as in the third embodiment, each LED of red, green, and blue, for example, can be controlled, so that the light emission can be adjusted to be an arbitrary color by color toning.
In the above embodiments, the PWM amplitude (ground voltage) of the PWM signal is preferably equal to or smaller than a predetermined safety extra low voltage (SELV), which is, for example, a DC voltage of 60 V. Setting the PWM amplitude to equal to or smaller than the safety extra low voltage (SELV) eliminates the need for insulation on the lighting equipment side, making the lighting equipment smaller and lighter. The safety extra low voltage (SELV) varies depending on the standard, but is a DC of 120 V or lower in JIS C 8105-1, for example.
Further, it is preferable that the PWM amplitude (ground voltage) of the PWM signal is equal to or lower than 50 V. In this case, it has the advantage of eliminating the need for an electrician's qualification as required by the Electricians Act, when wiring or connecting the dimmer apparatus and the lighting equipment using a two-wire power supply line.
In addition, the circuits of the lighting equipment 2, 2A, and 2B are preferably mounted on a single substrate, and in this case, the lighting equipment can be made smaller and lighter. Further, if the substrate is an aluminum substrate, the heat dissipation capacity increases and high-density mounting becomes possible.
In the above embodiments, a predetermined voltage value is set as the output voltage of each circuit, but the present invention is not limited to this, and may be changed within the scope of the design.
In the above embodiments, the lighting system that drives and controls one, two, and three light emitting elements has been described, but the present invention is not limited to this, and a lighting system that drives and controls four or more light emitting elements may be configured in a similar manner. In this case, by providing three or more light emitting elements, the lighting color of the lighting equipment can be arbitrarily changed (or toned).
As described in detail above, the present invention can be applied to a lighting system including a dimmer apparatus and lighting equipment connected to each other via a two-wire power line.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/020086 | 5/21/2020 | WO | 00 |
