JP7203348B2 - Lighting device and lighting device - Google Patents

Description

The present disclosure relates generally to lighting devices and lighting devices. More specifically, the present disclosure relates to a lighting device and a lighting device that light a plurality of light sources that emit light with different color temperatures.

2. Description of the Related Art Conventionally, there is an LED driving device that performs toning by lighting two LED loads having different color temperatures.

For example, the LED driver of Patent Document 1 converts AC input power to desired DC output power, and supplies the DC output power to two LED loads with different color temperatures. The control circuit of the LED driver adjusts the DC output power so that the current flowing through the LED load becomes the reference current. Furthermore, a ripple current reduction circuit is connected to each of the two LED loads, and each ripple current reduction circuit reduces the current ripple flowing through each LED load.

JP 2014-160574 A

The LED driving device of Patent Document 1 has a configuration including one power supply circuit that outputs a DC output voltage, and can light two LED loads having different color temperatures to perform color toning.

However, the LED driving device of Patent Document 1 has a relatively large power loss in the ripple current reduction circuit (current adjustment circuit).

An object of the present disclosure is to provide a lighting device and a lighting device that can adjust load currents supplied from one power supply circuit to a plurality of light sources and reduce power loss in the current adjustment circuits. be.

A lighting device according to an aspect of the present disclosure lights a plurality of light sources that emit light with different color temperatures. The lighting device includes a power supply circuit, a voltage control circuit, and a current control circuit . The power supply circuit applies a DC output voltage between a pair of conductors. The voltage control circuit controls the power supply circuit. A plurality of current paths are connected in parallel between the pair of conductors, and each of the plurality of current paths includes one of the plurality of light sources and a current adjustment circuit that adjusts the load current flowing through the current path. be The voltage control circuit selects, as a target monitoring voltage, the voltage across the current adjustment circuit corresponding to the light source with the highest light intensity among the plurality of light sources. The voltage control circuit feedback-controls the output voltage so that the value of the target monitoring voltage matches a target voltage value. The current control circuit controls the plurality of current adjustment circuits to match the values of the respective load currents to respective target current values, thereby toning the mixed colors of the lights of the plurality of light sources. . The voltage control circuit pre-stores correspondence data in which one of the voltages across the plurality of current adjustment circuits is associated with each color temperature range of the mixed light. The voltage control circuit externally acquires an instruction signal that indicates the color temperature of the mixed light. The voltage control circuit controls, based on the corresponding data, the voltage across the current adjustment circuit corresponding to the color temperature of the mixed light indicated by the instruction signal, among the voltages across the plurality of current adjustment circuits. Select as the target monitoring voltage.

A lighting device according to an aspect of the present disclosure lights a plurality of light sources that emit light with different color temperatures. The lighting device includes a power supply circuit, a voltage control circuit, and a current control circuit. The power supply circuit applies a DC output voltage between a pair of conductors. The voltage control circuit controls the power supply circuit. A plurality of current paths are connected in parallel between the pair of conductors, and each of the plurality of current paths includes one of the plurality of light sources and a current adjustment circuit that adjusts the load current flowing through the current path. be The current control circuit controls the plurality of current adjustment circuits to match the values of the respective load currents to respective target current values, thereby toning the mixed colors of the lights of the plurality of light sources. . The voltage control circuit pre-stores correspondence data in which one of the voltages across the plurality of current adjustment circuits is associated with each color temperature range of the mixed light. The voltage control circuit externally acquires an instruction signal that indicates the color temperature of the mixed light. Based on the corresponding data, the voltage control circuit compares, among the voltages across the plurality of current adjustment circuits, the voltage across the current adjustment circuit corresponding to the color temperature of the mixed light indicated by the instruction signal . Elephant monitor voltage. The voltage control circuit feedback-controls the output voltage so that the value of the target monitoring voltage matches a target voltage value. In the correspondence data, as the color temperature of the mixed light increases, the color temperature of the light source corresponding to each of the voltages across the plurality of current adjustment circuits associated with each range increases.

A lighting device according to an aspect of the present disclosure includes the lighting device described above, and a plurality of light sources that are lit by the lighting device and emit light with different color temperatures.

As described above, according to the present disclosure, it is possible to adjust the load currents supplied from one power supply circuit to each of the plurality of light sources, and to reduce the power loss in the current adjustment circuits.

FIG. 1 is a circuit diagram showing a lighting device provided with a lighting device according to an embodiment. FIG. 2 is a circuit diagram showing a power supply circuit of the same lighting device. FIG. 3 is a chromaticity diagram showing a toning range of the same lighting device. FIG. 4 is a diagram for explaining the operation of the lighting device;

Embodiments will be described below based on the drawings.

(Lighting device)
FIG. 1 shows the circuit configuration of a lighting device A1 of this embodiment. The lighting device A1 is, for example, a color rendering lighting device, a stage lighting device, or a lighting device for museums. However, the illumination device A1 may be used for applications other than the above, and is not limited to a specific application.

The lighting device A1 includes a lighting device 10 and two light sources 2 (21, 22). The lighting device 10 includes a power supply circuit 1 , two current adjustment circuits 3 ( 31 and 32 ), and a control circuit 4 .

The power supply circuit 1 receives an AC voltage Vi from an AC power supply 9, converts the AC voltage Vi into a DC output voltage Vo, and outputs the output voltage Vo. The AC power supply 9 is, for example, a commercial power supply with a nominal voltage of 100 V or 200 V and a frequency of 50 Hz or 60 Hz.

The power supply circuit 1, as shown in FIG. The rectifier 11 outputs a rectified voltage Va obtained by full-wave rectifying the AC voltage Vi. A series circuit of the primary winding 121 of the transformer 12 and the switching element 13 is connected between the output terminals of the rectifier 11 . A first end of the primary winding 121 is connected to the high potential side output end of the rectifier 11 . The switching element 13 is an N-channel enhancement type MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The drain of switching element 13 is connected to the second end of primary winding 121 . The source of the switching element 13 is connected to the output end of the rectifier 11 on the low potential side. A first end of the capacitor 14 is connected to the drain of the switching element 13 and a second end of the capacitor 14 is connected to the anode of the diode 16 . A first end of the secondary winding 122 of the transformer 12 is connected to the anode of the diode 16 and a second end of the secondary winding 122 is connected to the output end of the rectifier 11 on the low potential side. The positive terminal of the capacitor 15 is connected to the cathode of the diode 16, and the negative terminal of the capacitor 15 is connected to the output end of the rectifier 11 on the low potential side. A positive terminal of the capacitor 15 is connected to the first conductor W1, and a negative terminal of the capacitor 15 is connected to the second conductor W2. Capacitor 15 is preferably an electrolytic capacitor. The first conductor W1 and the second conductor W2 are electrical conductors, and are composed of, for example, terminals, wiring, or metal thin films. The power supply circuit 1 power-converts the AC voltage Vi to generate a DC output voltage Vo across the capacitor 15 . Therefore, a DC output voltage Vo is applied between the first conductor W1 and the second conductor W2.

Specifically, when the switching element 13 is turned on, a current flows through the primary winding 121 from the high potential side output terminal of the rectifier 11 to the low potential side output terminal, and energy is accumulated in the primary winding 121 . Next, when the switching element 13 is turned off, the energy stored in the primary winding 121 is released through the secondary winding 122, and the capacitor 15 is charged with the released energy. A DC output voltage Vo is generated across the capacitor 15 by turning on/off (switching) the switching element 13 .

The drive circuit 17 is configured to be connected to the gate of the switching element 13 and output a drive signal (gate voltage) between the gate and source of the switching element 13 to turn the switching element 13 on and off. The drive circuit 17 receives the voltage control signal Sb from the control circuit 4 and turns on/off the switching element 13 based on the voltage control signal Sb.

The power supply circuit 1 may be configured by a circuit other than the boost chopper circuit, and may be configured by, for example, a buck chopper circuit or a buck-boost chopper circuit.

Two current paths R1 and R2 are respectively formed between the first conductor W1 and the second conductor W2. Two current paths R1, R2 are connected in parallel between the first conductor W1 and the second conductor W2. Current paths R1 and R2 each include a series circuit of light source 2 and current regulation circuit 3 .

The light source 2 has an LED array in which a plurality of LED (Light Emitting Diode) elements (solid light emitting elements) are connected in series. The light source 2 may have multiple LED arrays connected in parallel. Here, the anode of the LED element at one end of the LED array is connected to the first end of the light source 2, and the first end of the light source 2 is called the anode side. The second end of the light source 2 is connected to the cathode of the LED element at the other end of the LED array, and the second end of the light source 2 is called the cathode side.

The current adjustment circuit 3 includes a series circuit of a transistor 3a and a detection resistor 3b, and a drive circuit 3c. The transistor 3a is an N-channel enhancement type MOSFET. The first conductor W1 is connected to the anode side of the light source 2, and the cathode side of the light source 2 is connected to the drain of the transistor 3a. The source of transistor 3a is connected to the first end of sensing resistor 3b. A second end of the sensing resistor 3b is connected to the second conductor W2. That is, each of the two current paths R1 and R2 includes a series circuit of the light source 2 and the current adjustment circuit 3 . In other words, the two light sources 2 are provided in one-to-one correspondence with the two current paths R1 and R2, respectively, and the two current adjustment circuits 3 are provided in one-to-one correspondence with the two current paths R1 and R2. is provided.

The drive circuit 3c of the current adjustment circuit 3 is connected to the gate of the transistor 3a and outputs a drive signal (gate voltage) between the gate and source of the transistor 3a. The drain-source resistance of the transistor 3a varies depending on the gate voltage of the transistor 3a. That is, the voltage drop by the transistor 3a (voltage between the drain and source of the transistor 3a) varies depending on the gate voltage of the transistor 3a. The current adjustment circuit 3 can adjust the load current flowing through the light source 2 by the output voltage Vo by controlling the voltage drop by the transistor 3a. In FIG. 1, the load current flowing through the current path R1 is Io1, and the load current flowing through the current path R2 is Io2.

The current path R1 has a white light source 21 as the light source 2 and a current adjustment circuit 31 as the current adjustment circuit 3 . The white light source 21 has a series circuit of a plurality of LED elements 2a. The plurality of LED elements 2a each emit white light with a color temperature of 6500K. The drive circuit 3c of the current adjustment circuit 31 receives the current control signal Sc1 from the control circuit 4 and adjusts the gate voltage of the transistor 3a based on the current control signal Sc1. That is, the current adjustment circuit 31 can adjust the load current Io1 based on the current control signal Sc1.

The current path R<b>2 has an incandescent light source 22 as the light source 2 and a current adjustment circuit 32 as the current adjustment circuit 3 . The light bulb color light source 22 has a series circuit of a plurality of LED elements 2b. The plurality of LED elements 2b each emit light of incandescent color with a color temperature of 2700K. The drive circuit 3c of the current adjustment circuit 32 receives the current control signal Sc2 from the control circuit 4 and adjusts the gate voltage of the transistor 3a based on the current control signal Sc2. That is, the current adjustment circuit 32 can adjust the load current Io2 based on the current control signal Sc2.

Moreover, it is preferable that the white light source 21 is detachably attached to the first conductor W1 and the current adjustment circuit 31 through the connector CN1. It is preferable that the bulb-colored light source 22 is detachably attached to the first conductor W1 and the current adjustment circuit 32 by means of the connector CN2.

The control circuit 4 includes a voltage control circuit 41 and a current control circuit 42 .

The voltage control circuit 41 is connected to the drive circuit 17 of the power supply circuit 1 and outputs a voltage control signal Sb to the drive circuit 17 . The drive circuit 17 turns on and off the switching element 13 based on the voltage control signal Sb. That is, the voltage control circuit 41 boosts the AC voltage Vi by controlling the switching operation of the switching element 13, and controls the value of the output voltage Vo to the target voltage value.

Voltages across the detection resistors 3b of the current adjustment circuits 31 and 32 are input to the current control circuit 42 as resistance voltages Vs1 and Vs2. The current control circuit 42 generates current control signals Sc1 and Sc2 based on the resistance voltages Vs1 and Vs2. The current control circuit 42 is connected to each drive circuit 3c of the current adjustment circuits 31 and 32, and outputs current control signals Sc1 and Sc2 to each drive circuit 3c. Each drive circuit 3c adjusts the gate voltage of each transistor 3a based on the current control signal Sc1 or the current control signal Sc2. That is, the current control circuit 42 can control each dimming level of the white light source 21 and the light bulb color light source 22 by individually controlling the gate voltage of each transistor 3a and individually controlling the load currents Io1 and Io2. .

The control circuit 4 mentioned above comprises a computer system. A computer system is mainly composed of a processor and a memory as hardware. Each function of the voltage control circuit 41 and the current control circuit 42 is realized by the processor executing the program recorded in the memory. The program may be recorded in advance in the memory of the computer system, may be provided through an electric communication line, or may be stored in a non-temporary recording medium such as a computer system-readable memory card, optical disk, or hard disk drive. May be recorded and provided. A processor in a computer system consists of one or more electronic circuits including semiconductor integrated circuits (ICs) or large scale integrated circuits (LSIs). A plurality of electronic circuits may be integrated into one chip, or may be distributed over a plurality of chips. A plurality of chips may be integrated in one device, or may be distributed in a plurality of devices. For example, the voltage control circuit 41 and the current control circuit 42 may be implemented in one computer system, or a first computer system that implements the voltage control circuit 41 and a second computer system that implements the current control circuit 42. may be implemented.

Then, the illumination device A1 can adjust the color of the mixed light obtained by mixing the lights of the light sources 21 and 22 by individually adjusting the white light source 21 and the light bulb color light source 22 . The toning operation by the illumination device A1 will be described in detail below.

First, an external controller transmits an instruction signal S0 to the current control circuit 42 according to the control details required for the lighting device A1. The instruction signal S0 is a signal that instructs the color temperature of the mixed light of the white light source 21 and the light bulb color light source 22 and the dimming level of the mixed light. Note that the instruction signal S0 is either one of a signal that instructs the color temperature of the mixed light and the dimming level of the mixed light, or two or more signals that instruct the color temperature of the mixed light and the dimming level of the mixed light. may be

Then, the current control circuit 42 controls the color temperature of the mixed light to be the indicated color temperature and the dimming level of the mixed light to be the indicated dimming level (hereinafter referred to as dimming instruction value). Secondly, each dimming level of the white light source 21 and the light bulb color light source 22 is controlled. That is, the current control circuit 42 controls the load currents Io1 and Io2 so that the load currents Io1 and Io2 match their respective target current values. Specifically, the current control circuit 42 generates dimming reference voltages respectively corresponding to the white light source 21 and the warm-white light source 22 based on the respective dimming instruction values of the white light source 21 and the warm-white light source 22 . Each value of the dimming reference voltage is a value corresponding to the target current value, and increases as the dimming instruction value increases and decreases as the dimming instruction value decreases. The current control circuit 42 compares the dimming reference voltage corresponding to the white light source 21 with the resistance voltage Vs1 and generates a current control signal Sc1 for controlling the current adjustment circuit 31 . The current control signal Sc<b>1 is a control signal for controlling the current adjustment circuit 31 so that the resistance voltage Vs<b>1 matches the dimming reference voltage of the white light source 21 . Further, the current control circuit 42 compares the dimming reference voltage corresponding to the light bulb color light source 22 with the resistance voltage Vs2 and generates a current control signal Sc2 for controlling the current adjustment circuit 32 . The current control signal Sc<b>2 is a control signal for controlling the current adjustment circuit 32 so that the resistance voltage Vs<b>2 matches the dimming reference voltage of the bulb-colored light source 22 .

The drive circuit 3c of the current adjustment circuit 31 adjusts the gate voltage of the transistor 3a based on the current control signal Sc1 to adjust the load current Io1 (the dimming level of the white light source 21). The drive circuit 3c of the current adjustment circuit 32 adjusts the gate voltage of the transistor 3a based on the current control signal Sc2 to adjust the load current Io2 (the dimming level of the light bulb color light source 22).

Therefore, the current control circuit 42 can control the color temperature and dimming level of the mixed light of the white light source 21 and the light bulb color light source 22 according to the instruction content of the instruction signal S0. In this embodiment, the color temperature of the white light emitted by the white light source 21 is 6500K, and the color temperature of the light bulb-colored light emitted by the light bulb color light source 22 is 2700K. Therefore, the color temperature of the mixed light of the white light source 21 and the light bulb color light source 22 can change along the straight line Ya in the chromaticity diagram of FIG.

Assuming that the voltage of the white light source 21 viewed from the cathode side to the anode side (the voltage across the white light source 21) is the forward voltage Vf1 (see FIG. 1), the value of the forward voltage Vf1 is the lighting start voltage of the white light source 21. is exceeded, the white light source 21 is turned off. When the value of the forward voltage Vf1 exceeds the lighting start voltage of the white light source 21, the load current Io1 flows and the white light source 21 is lit. The forward voltage of the white light source 21 is the sum of the forward voltages of the plurality of LED elements 2a connected in series.

Further, if the voltage (voltage across the bulb-colored light source 22) viewed from the cathode side to the anode side of the bulb-colored light source 22 is defined as a forward voltage Vf2 (see FIG. 1), the value of the forward voltage Vf2 corresponds The light bulb color light source 22 is extinguished until the starting voltage is exceeded. When the value of the forward voltage Vf2 exceeds the lighting start voltage of the bulb-colored light source 22, the load current Io2 flows and the bulb-colored light source 22 is lit. The forward voltage of the bulb-colored light source 22 is the sum of the forward voltages of the plurality of LED elements 2b connected in series.

In this embodiment, it is preferable that the voltage-current characteristics of the white light source 21 and the light bulb color light source 22 are the same (almost the same). In this case, if the load current Io1 and the load current Io2 are equal, the value of the forward voltage Vf1 and the value of the forward voltage Vf2 are equal (substantially equal). It should be noted that even if the voltage-current characteristics do not match completely, each voltage-current characteristic being the same means that the difference between each voltage-current characteristic is relatively small, for example, the difference between each voltage-current characteristic is a predetermined value. It also includes forms that fall within the range. Further, when the value of the forward voltage Vf1 and the value of the forward voltage Vf2 are equal (same), the forward voltages Vf1 and Vf2 are completely the same when the load current Io1 and the load current Io2 are equal (same). Even without it, the difference between the forward voltages Vf1 and Vf2 is relatively small.

For example, the LED element 2a of the white light source 21 has a blue LED chip and a first phosphor. White light is generated by the blue light emitted from the blue LED chip passing through the first phosphor. Also, the LED element 2b of the bulb-colored light source 22 has a blue LED chip and a second phosphor. Then, the blue light emitted from the blue LED chip passes through the second phosphor, thereby generating incandescent light. In this case, the LED elements 2a and 2b have blue LED chips, and the forward voltages of the LED elements 2a and 2b are equal. That is, the LED elements 2a and 2b have the same voltage-current characteristics. Therefore, if the number of series connections of the LED elements 2a in the white light source 21 and the number of series connections of the LED elements 2b in the light bulb color light source 22 are the same, the voltage-current characteristics of the white light source 21 and the light bulb color light source 22 are the same. become.

Further, when the forward voltages of the LED elements 2a and 2b are different under the condition that the load current Io1 and the load current Io2 are equal, the number of series connections of the LED elements 2a in the white light source 21 and the light bulb color light source The number of series connections of the LED elements 2b in 22 is set to a different number. If the forward voltage of the LED element 2a is higher than the forward voltage of the LED element 2b under the condition that the load current Io1 and the load current Io2 are equal, the number of LED elements 2a connected in series is equal to the number of LED elements 2b connected in series. Less than the number of connections. As a result, the white light source 21 and the light bulb color light source 22 can have the same voltage-current characteristics.

In order to light the light sources 21 and 22 respectively, the power supply circuit 1 needs to make the value of the output voltage Vo higher than the values of the forward voltages Vf1 and Vf2. In this case, each differential voltage between the output voltage Vo and the forward voltages Vf1 and Vf2 causes heat generation in the transistor 3a. That is, the differential voltage between the output voltage Vo and the forward voltage Vf1 causes power loss in the current adjustment circuit 31. FIG. A differential voltage between the output voltage Vo and the forward voltage Vf2 causes power loss in the current adjustment circuit 32 .

Therefore, the voltage control circuit 41 reduces each power loss of the current adjustment circuit 3 by controlling the output voltage Vo as follows.

The drain voltage of the transistor 3a of the current adjusting circuit 31 (the voltage on the cathode side of the light source 21) is set as a monitoring voltage Vd1. The drain voltage of the transistor 3a of the current adjusting circuit 32 (the voltage on the cathode side of the light source 22) is set as a monitoring voltage Vd2. The voltage control circuit 41 receives monitoring voltages Vd1 and Vd2, selects one of the monitoring voltages Vd1 and Vd2 as a target monitoring voltage, and uses the target monitoring voltage to feedback-control the output voltage Vo. Note that the monitoring voltage Vd1 corresponds to the voltage across the current adjustment circuit 31 . The monitoring voltage Vd2 corresponds to the voltage across the current adjustment circuit 32 .

FIG. 4 shows the relationship between the color temperature of mixed-color light and the load currents Io1 and Io2. In the first range 81 where the color temperature is from 2700 to 4100K, the value of the load current Io2 is greater than the value of the load current Io1, and the intensity of the light bulb-colored light emitted by the light bulb-colored light source 22 is higher than that of the white light emitted by the white light source 21. greater than strength. In the second range 82 where the color temperature is from 4100 to 6500 K, the value of the load current Io1 is greater than the value of the load current Io2, and the intensity of the white light emitted by the white light source 21 is lower than that of the warm white light emitted by the warm white light source 22. greater than strength. In this case, the voltage control circuit 41 selects the monitoring voltage Vd2 as the target monitoring voltage in the first range 81 . In the second range 82, the voltage control circuit 41 selects the monitoring voltage Vd1 as the target monitoring voltage. That is, in the first range 81 where the color temperature of the mixed light is low, the monitor voltage Vd2 corresponding to the light bulb color light source 22 with the low color temperature, out of the white light source 21 and the light bulb color light source 22, is selected as the target monitor voltage. In the second range 83 where the color temperature of the mixed light is high, the monitor voltage Vd1 corresponding to the white light source 21 with the high color temperature is selected as the target monitor voltage from among the white light source 21 and the light bulb color light source 22 . In other words, the voltage control circuit 41 selects the monitoring voltage corresponding to the light source with the higher light intensity out of the white light source 21 and the light bulb color light source 22 as the target monitoring voltage. It can also be said that the voltage control circuit 41 selects the monitoring voltage corresponding to the load current Io1 or Io2, whichever is larger, as the target monitoring voltage.

Here, when the white light source 21 is lit, the value of the forward voltage Vf1 increases as the value of the load current Io1 increases. Further, when the bulb-colored light source 22 is lit, the larger the value of the load current Io2, the higher the value of the forward voltage Vf2. Therefore, if the voltage-current characteristics of the white light source 21 and the light bulb color light source 22 are the same as described above, if the value of the load current Io1 is greater than the value of the load current Io2, the value of the forward voltage Vf1 is the forward voltage higher than the value of Vf2. Also, if the value of load current Io2 is greater than the value of load current Io1, the value of forward voltage Vf2 will be higher than the value of forward voltage Vf1. In other words, if the value of load current Io1 is greater than the value of load current Io2, the value of monitor voltage Vd1 will be lower than the value of monitor voltage Vd2. If the value of load current Io2 is greater than the value of load current Io1, the value of monitor voltage Vd2 will be lower than the value of monitor voltage Vd1.

Therefore, the voltage control circuit 41 selects the lower one of the monitoring voltages Vd1 and Vd2 as the target monitoring voltage when the white light source 21 and the light bulb color light source 22 are lit. For example, if the value of the monitoring voltage Vd1 is lower than the value of the monitoring voltage Vd2, the monitoring voltage Vd1 becomes the target monitoring voltage. If the value of the monitoring voltage Vd2 is lower than the value of the monitoring voltage Vd1, the monitoring voltage Vd2 becomes the target monitoring voltage. The voltage control circuit 41 compares the value of the target monitoring voltage with a predetermined target voltage value, and generates the voltage control signal Sb based on the comparison result. The voltage control signal Sb is a control signal for controlling the power supply circuit 1 so that the value of the target monitoring voltage matches a predetermined target voltage value. The target voltage value is a value obtained by adding a constant value α to the maximum value of the forward voltage of the light source 2 . α is preset to about 2 to 3 V, for example. Since the voltage-current characteristics of the white light source 21 and the light bulb color light source 22 are the same, the maximum value of the forward voltage of the light source 2 may be the maximum value of either of the forward voltages Vf1 and Vf2.

The drive circuit 17 of the power supply circuit 1 adjusts the switching operation (on-duty, switching frequency, etc.) of the transistor 3a based on the current control signal Sc1 to adjust the value of the output voltage Vo. Therefore, the output voltage Vo is maintained at a value that enables lighting of the light source with the higher dimming level among the light sources 21 and 22 . Furthermore, the value of the drain-source voltage of each transistor 3a of the current adjusting circuits 31, 32 is maintained near the above α, and the power loss of each of the current adjusting circuits 31, 32 can be reduced. In this case, the above α is preferably set to a value as low as possible while allowing the light source 2 to be dimmed over the entire dimming range.

Further, in this embodiment, if the voltage-current characteristics of the white light source 21 and the light bulb color light source 22 are different, power loss will occur in the transistor 3a.

For example, the power loss P1 of the current adjustment circuit 31 (power loss at the transistor 3a of the current adjustment circuit 31) is represented by the following equation (1). Note that Rb is the resistance value of the detection resistor 3b.
P1=(Vd1−Io1·Rb)·Io1 ………… Formula (1)
A power loss P2 of the current adjustment circuit 32 (power loss at the transistor 3a of the current adjustment circuit 32) is expressed by the following equation (2).
P2=(Vd2−Io2·Rb)·Io2 ………… Formula (2)
Here, if Vd2=Vd1+β, the power loss P2 of the current adjustment circuit 32 is represented by the following equation (3). where β represents the difference between the monitor voltages Vd1 and Vd2 that occurs when the load currents Io1 and Io2 have the same value.
P2=(Vd1+β-Io2・Rb)・Io2 ………… Formula (3)
In this case, the difference Pa between the power loss P1 and the power loss P2 is represented by Equation (4) below.
Pa=P2−P1=β・Io2 ………… Formula (4)
That is, the power loss in the current adjustment circuit 32 is increased by Pa compared to the current adjustment circuit 31 . For example, if β is 3V and Io2 is 0.2A, Pa will be 0.6W. It is necessary to use a transistor with specifications that allow the difference Pa between the power loss P1 and the power loss P2 as the transistor 3a.

Further, when one of the light sources 21 and 22 is fully lit (dimming level 100%) and the other of the light sources 21 and 22 is dimming lighting (less than 100% dimming level), the power losses P1 and P2 are In both cases, it is necessary to suppress variations in the forward voltages Vf1 and Vf2 so as not to exceed the value of the power loss during full lighting. For example, by using a plurality of LED elements 2a and a plurality of LED elements 2b having the same forward voltage rank, variations in the forward voltages Vf1 and Vf2 can be suppressed.

(Modification)
The voltage control circuit 41 may select a target monitoring voltage from the monitoring voltages Vd1 and Vd2 according to the color temperature of the mixed light indicated by the instruction signal S0. In this case, the voltage control circuit 41 stores corresponding data in advance in a memory or the like. The correspondence data is data in which one of the monitoring voltages Vd1 and Vd2 is associated with each color temperature range.

In the correspondence data showing the relationship in FIG. 4, the first range 81 is associated with the monitoring voltage Vd2, and the second range 82 is associated with the monitoring voltage Vd1. Then, if the color temperature of the mixed light indicated by the instruction signal S0 falls within the first range 81, the voltage control circuit 41 selects the monitoring voltage Vd2 as the target monitoring voltage. If the color temperature of the mixed light indicated by the instruction signal S0 falls within the second range 82, the voltage control circuit 41 selects the monitoring voltage Vd1 as the target monitoring voltage. Also in this modified example, each power loss of the current adjusting circuits 31 and 32 can be reduced.

In addition, although the illumination device A1 of the above-described embodiment and modification includes two light sources 2 with different color temperatures, it may include three or more light sources 2 with different color temperatures. In this case, the lighting device 10 includes three or more current adjustment circuits 3 corresponding to three or more light sources 2, respectively. Then, the voltage control circuit 41 selects the minimum monitoring voltage among the monitoring voltages of the three or more current adjusting circuits 3 as the target monitoring voltage. As in the modified example, the voltage control circuit 41 divides the entire range of color temperature that can be adjusted into three or more ranges, and corresponds to the range to which the color temperature of the mixed light indicated by the instruction signal S0 belongs. The monitoring voltage to be monitored may be selected as the target monitoring voltage.

It should be noted that the light source 2 is not limited to having an LED as a solid light emitting device. The light source 2 may have, for example, an organic EL (Organic Electro Luminescence, OEL) or other solid state light emitting device such as a semiconductor laser (Laser Diode, LD).

Also, the switching element 13 and the transistor 3a are not limited to MOSFETs, and may be other switching elements (transistors) such as J-FETs (Junction Field Effect Transistors) or bipolar transistors.

As described above, the lighting device (10) of the first aspect according to the embodiment lights the plurality of light sources (2) that emit light with different color temperatures. A lighting device (10) includes a power supply circuit (1) and a voltage control circuit (41). A power supply circuit (1) applies a DC output voltage (Vo) between a pair of conductors (W1, W2). A voltage control circuit (41) controls the power supply circuit (1). A plurality of current paths (R1, R2) are connected in parallel between the pair of conductors (W1, W2). Each of the plurality of current paths (R1, R2) includes one of a plurality of light sources (2) and a current adjustment circuit (3) that adjusts load currents (Io1, Io2) flowing through the current paths (R1, R2). and are included. The voltage control circuit (41) selects the voltages (Vd1, Vd2) across the current adjustment circuit (3) corresponding to the light source (2) having the highest light intensity among the plurality of light sources (2) as the target monitoring voltage. select. Then, the voltage control circuit (41) feedback-controls the output voltage (Vo) so that the value of the target monitoring voltage matches the target voltage value.

The lighting device (10) described above can adjust the load currents (Io1, Io2) respectively supplied from one power supply circuit (1) to the plurality of light sources (21, 22), and Power loss can be reduced.

Moreover, it is preferable that the lighting device (10) of the second aspect according to the embodiment further includes a current control circuit (42) in the first aspect. A current control circuit (42) controls a plurality of current adjusting circuits (3) to match the values of the load currents (Io1, Io2) to their respective target current values, thereby controlling the plurality of light sources (2). Toning the mixed light of each light.

The lighting device (10) described above is capable of toning control.

Further, in the lighting device (10) of the third aspect according to the embodiment, in the second aspect, the voltage control circuit (41) controls the voltages (Vd1, Vd2) across the plurality of current adjustment circuits (3) It is preferable to select the minimum voltage across both ends (Vd1, Vd2) as the target monitoring voltage.

The lighting device (10) described above can easily select the target monitoring voltage from the voltages (Vd1, Vd2) across the plurality of current adjusting circuits (3).

Further, in the lighting device (10) of the fourth aspect according to the embodiment, in the second aspect, the voltage control circuit (41) provides a plurality of currents for each color temperature range (81, 82) of the mixed light. It is preferable to pre-store correspondence data that associates either of the voltages (Vd1, Vd2) across the adjustment circuit (3). A voltage control circuit (41) externally acquires an instruction signal (S0) that instructs the color temperature of the mixed light, and based on the corresponding data, controls voltages (Vd1, Vd2) across the plurality of current adjustment circuits (3). Among them, the voltages (Vd1, Vd2) across the current adjustment circuit (3) corresponding to the color temperature of the mixed light indicated by the instruction signal (S0) are selected as the target monitoring voltages.

The lighting device (10) described above can easily select the target monitoring voltage from the voltages (Vd1, Vd2) across the plurality of current adjusting circuits (3).

Further, the lighting device (10) of the fifth aspect according to the embodiment lights the plurality of light sources (2) that emit light with different color temperatures. A lighting device (10) includes a power supply circuit (1), a voltage control circuit (41), and a current control circuit (42). A power supply circuit (1) applies a DC output voltage (Vo) between a pair of conductors (W1, W2). A voltage control circuit (41) controls the power supply circuit (1). A plurality of current paths (R1, R2) are connected in parallel between the pair of conductors (W1, W2). Each of the plurality of current paths (R1, R2) includes one of a plurality of light sources (2) and a current adjustment circuit (3) that adjusts load currents (Io1, Io2) flowing through the current paths (R1, R2). and are included. A current control circuit (42) controls a plurality of current adjusting circuits (3) to match the values of the load currents (Io1, Io2) to their respective target current values, thereby controlling the plurality of light sources (2). Toning the mixed light of each light. The voltage control circuit (41) preliminarily stores correspondence data in which one of the voltages across the plurality of current adjustment circuits (3) is associated with each color temperature range (81, 82) of the mixed light. A voltage control circuit (41) externally acquires an instruction signal (S0) that instructs the color temperature of the mixed light, and based on the corresponding data, controls voltages (Vd1, Vd2) across the plurality of current adjustment circuits (3). Among them, the voltages (Vd1, Vd2) across the current adjustment circuit (3) corresponding to the color temperature of the mixed light indicated by the instruction signal (S0) are selected as the target monitoring voltages. A voltage control circuit (41) feedback-controls the output voltage (Vo) so that the value of the target monitoring voltage matches the target voltage value. In the correspondence data, as the color temperature of the mixed light increases, the light source (2) corresponding to the voltages (Vd1, Vd2) across the plurality of current adjustment circuits (3) associated with each range (81, 82) respectively. color temperature is higher.

The lighting device (10) described above can adjust the load currents (Io1, Io2) respectively supplied from one power supply circuit (1) to the plurality of light sources (21, 22), and Power loss can be reduced.

Further, in the lighting device (10) of the sixth aspect according to the embodiment, in any one of the first to fifth aspects, the current adjustment circuit (3) is electrically connected in series with the light source (2). It is preferable to have a transistor (3a) and a resistor (3b) that are connected. The current adjustment circuit (3) adjusts the load currents (Io1, Io2) by controlling the voltage drop across the transistor (3a).

The above lighting device (10) can reduce the power loss in the transistor (3a).

Further, the lighting device (A1) of the seventh aspect according to the embodiment is lit by the lighting device (10) of any one of the first to sixth aspects and the lighting device (10), and the lighting device (A1) has the color temperature of each other. a plurality of light sources (2) emitting different light.

The lighting device (A1) described above can adjust the load currents (Io1, Io2) respectively supplied from one power supply circuit (1) to the plurality of light sources (21, 22), and in the current adjustment circuit (3) Power loss can be reduced.

Further, according to the lighting device (A1) of the eighth aspect according to the embodiment, in the seventh aspect, if the values of the load currents (Io1, Io2) flowing through the plurality of light sources (2) are the same, the plurality of The voltages (Vf1, Vf2) across the light source (2) are preferably the same.

The lighting device (A1) described above can suppress variations in voltages (Vf1, Vf2) across the plurality of light sources (2).

Further, in the lighting device (A1) of the ninth aspect according to the embodiment, in the seventh or eighth aspect, each of the plurality of light sources (2) has the same voltage-current characteristics. One or more solid state It is preferable to have light emitting elements (2a, 2b).

The lighting device (A1) described above can suppress variations in voltages (Vf1, Vf2) across the plurality of light sources (2).

Further, in the lighting device (A1) of the tenth aspect according to the embodiment, in the seventh to ninth aspects, the plurality of light sources (2) include a white light source (21) that emits white light and light of incandescent color. It preferably includes a warm-white light source (22) that emits a

The lighting device (A1) described above enables lighting with high color rendering properties.

Also, the above-described embodiment and modifications are examples of the present invention. Therefore, the present invention is not limited to the above-described embodiments and modifications, and other than the embodiments and modifications can be designed as long as they do not depart from the technical idea of the present invention. Of course, various modifications are possible depending on the requirements.

A1 lighting device 10 lighting device 1 power supply circuit 2 light source 21 white light source 22 light bulb color light source 2a, 2b LED element (solid light emitting element)
3, 31, 32 current adjustment circuit 3a transistor 3b detection resistor (resistor)
41 voltage control circuit 42 current control circuit 81 first range (range of color temperature)
82 second range (color temperature range)
W1 first conductor (conductor)
W2 second conductor (conductor)
R1, R2 Current path Io1, Io2 Load current Vd1, Vd2 Monitoring voltage Vf1, Vf2 Forward voltage Vo Output voltage S0 Instruction signal

Claims (8)

A lighting device for lighting a plurality of light sources emitting light with different color temperatures,
a power supply circuit that applies a DC output voltage between a pair of conductors;
a voltage control circuit that controls the power supply circuit;
a current control circuit ;
A plurality of current paths are connected in parallel between the pair of conductors, and each of the plurality of current paths includes one of the plurality of light sources and a current adjustment circuit that adjusts the load current flowing through the current path. be,
The voltage control circuit selects, as a target monitoring voltage, a voltage across the current adjustment circuit corresponding to the light source having the highest light intensity among the plurality of light sources, and the value of the target monitoring voltage is a target voltage value. feedback-controlling the output voltage to match
The current control circuit controls the plurality of current adjustment circuits to match the values of the respective load currents to respective target current values, thereby toning the mixed colors of the lights of the plurality of light sources. ,
The voltage control circuit is
pre-storing correspondence data in which one of the voltages across the plurality of current adjustment circuits is associated with each color temperature range of the mixed light;
externally obtaining an instruction signal indicating the color temperature of the mixed light;
Based on the correspondence data, among the voltages across the plurality of current adjustment circuits, the voltage across the current adjustment circuit corresponding to the color temperature of the mixed light indicated by the instruction signal is selected as the target monitoring voltage.
lighting device. The voltage control circuit selects a minimum voltage across the plurality of current adjustment circuits as the target monitoring voltage.
The lighting device according to claim 1. A lighting device for lighting a plurality of light sources emitting light with different color temperatures,
a power supply circuit that applies a DC output voltage between a pair of conductors;
a voltage control circuit that controls the power supply circuit;
a current control circuit;
A plurality of current paths are connected in parallel between the pair of conductors, and each of the plurality of current paths includes one of the plurality of light sources and a current adjustment circuit that adjusts the load current flowing through the current path. be,
The current control circuit controls the plurality of current adjustment circuits to match the values of the respective load currents to respective target current values, thereby toning the mixed colors of the lights of the plurality of light sources. ,
The voltage control circuit is
pre-storing correspondence data in which one of the voltages across the plurality of current adjustment circuits is associated with each color temperature range of the mixed light;
externally obtaining an instruction signal indicating the color temperature of the mixed light;
based on the corresponding data, among the voltages across the plurality of current adjustment circuits, a voltage across the current adjustment circuit corresponding to the color temperature of the mixed light indicated by the instruction signal is selected as a target monitoring voltage;
feedback-controlling the output voltage so that the value of the target monitoring voltage matches a target voltage value;
In the correspondence data, as the color temperature of the mixed light increases, the color temperature of the light source corresponding to each of the voltages across the plurality of current adjustment circuits associated with each range increases.
lighting device. The current regulation circuit has a transistor and a resistor electrically connected in series with the light source, and regulates the load current by controlling a voltage drop across the transistor.
The lighting device according to any one of claims 1 to 3, characterized in that: a lighting device according to any one of claims 1 to 4;
a plurality of light sources that are lit by the lighting device and emit light having different color temperatures from each other;
lighting device. If the values of the load currents flowing through the plurality of light sources are the same, the voltages across the plurality of light sources are the same.
6. A lighting device according to claim 5. Each of the plurality of light sources comprises one or more solid state light emitters having the same voltage-current characteristics.
7. The lighting device according to claim 5 or 6. The plurality of light sources include a white light source that emits white light and a light bulb-colored light source that emits bulb-colored light.
8. A lighting device according to any one of claims 5-7.

Images