WO2019106855A1

WO2019106855A1 - Light source drive device, illuminating device, and current setting method

Info

Publication number: WO2019106855A1
Application number: PCT/JP2018/006910
Authority: WO
Inventors: 亮平多田
Original assignee: シャープ株式会社
Priority date: 2017-12-01
Filing date: 2018-02-26
Publication date: 2019-06-06
Also published as: JPWO2019106855A1; JP6944538B2

Abstract

A light source drive device (100) is provided with: a first terminal (52), to which a light source can be connected, and a setting unit (90) for setting a current flowing to the light source can be also connected; a constant current drive circuit (10) that controls the current flowing to the light source so that the current is a constant current; a conversion circuit (30), which converts a voltage supplied from the setting unit (90) connected to the first terminal (52), and which outputs a voltage signal thus converted; and a control circuit (40), which sets the current value of the constant current on the basis of the voltage signal thus converted, and which outputs, to the constant current drive circuit (10), a setting signal indicating the current value thus set.

Description

Light source drive device, lighting device, and current setting method

The present disclosure relates to a light source drive device, a lighting device, and a current setting method. This application claims priority based on Japanese Patent Application No. 2017-231636 filed on Dec. 1, 2017. The entire contents of the description of the Japanese patent application are incorporated herein by reference.

2. Description of the Related Art Conventionally, a light source drive device has been known which controls lighting of a light source such as a light emitting diode (LED) with a constant current. In various lighting devices having such a light source driving device (for example, a lighting device used in a signboard, a showcase, etc., an LED lighting used in home, etc.), the demand for brightness is determined by the user or the installation location. It is different. Therefore, it was necessary to prepare various products in line with each request. In addition, when changing the brightness after installing the lighting device in a ceiling, a store, etc., disassemble the lighting device, replace the internal light source drive device or light source, or modify the light source drive device to output current I needed to change it.

For example, as a technique for changing the above output current, Patent Document 1 (US Pat. No. 9,161,410) discloses a light emitting diode drive device in which the output current is variable. In this light emitting diode drive device, the user setting unit sends the user side setting signal to the pulse width modulation control unit, the light adjustment unit sends the light adjustment signal to the pulse width modulation control unit, and the pulse width modulation control unit makes the user side setting signal The output current control signal is acquired by multiplying the value of D by the value of the dimming signal and sent to the light emitting diode driver. The light emitting diode drive unit drives the light emitting diode with a drive current obtained by multiplying the value of the output current control signal by the value of the maximum output current.

U.S. Patent No. 9161410

However, in the light emitting diode driving device according to Patent Document 1, the light emitting diode is electrically connected to the light emitting diode driving unit, and the user setting unit is electrically connected to the pulse width modulation control unit. From this, the light emitting diode drive device needs to be provided with a dedicated connection terminal for connecting the user setting unit, which may make the device configuration complicated.

The present disclosure, in one aspect, aims to provide a light source drive capable of easily changing the current output from the light source drive to the light source. In another aspect, the present disclosure aims to provide a lighting device including the above-described light source driving device. In still another aspect, the present disclosure aims to provide a current setting method capable of easily changing the current output from a light source driver to a light source.

In the light source drive device according to an embodiment, the light source can be connected and the first terminal to which the setting unit for setting the current flowing to the light source can be connected, and the current flowing to the light source becomes a constant current And a conversion circuit for converting the voltage supplied from the setting unit connected to the first terminal and outputting the converted voltage signal, and based on the converted voltage signal. And a control circuit configured to set a current value of the constant current and to output a setting signal indicating the set current value to the constant current drive circuit.

A lighting device according to another embodiment includes the above light source driving device and a light source.
According to yet another embodiment, a current setting method is provided for setting the current supplied from the light source driver to the light source. The light source driving device includes a light source, a terminal to which a setting unit for setting a current flowing to the light source can be connected, and a constant current driving circuit that controls the current flowing to the light source to be a constant current. The current setting method converts the voltage supplied from the setting unit connected to the terminal and outputs the converted voltage signal, and sets the current value of the constant current based on the converted voltage signal. And a step of outputting a setting signal indicating a current value set in the setting step to the constant current drive circuit.

According to the present disclosure, it is possible to easily change the current output from the light source drive device to the light source.

FIG. 1 is a conceptual diagram for illustrating an overview of a current setting system according to a first embodiment. FIG. 7 is a diagram for describing an example of a signal conversion method according to the first embodiment. 7 is a flowchart for illustrating an example of a current setting method according to the first embodiment. FIG. 7 is a diagram showing an example of a circuit configuration of a current setting unit according to the first embodiment. FIG. 1 is a block diagram showing a configuration of a light source drive device according to a first embodiment. FIG. 7 is a block diagram showing a light source drive device according to a first modification of the first embodiment. FIG. 10 is a block diagram showing a light source drive device according to a second modification of the first embodiment. FIG. 10 is a block diagram of a light source drive device according to a second embodiment. FIG. 16 is a block diagram of a light source drive device according to a first modification of the second embodiment. FIG. 17 is a block diagram of a light source drive device according to a second modification of the second embodiment. FIG. 17 is a block diagram of a light source drive device according to a third modification of the second embodiment. FIG. 16 is a block diagram showing an example of a configuration of a lighting device according to a third embodiment. FIG. 17 is a block diagram showing an example of a configuration of a lighting device according to a modification of the third embodiment. FIG. 16 is a conceptual diagram for illustrating an overview of a current setting system according to a fourth embodiment. FIG. 16 is a flowchart for illustrating an example of a current setting method according to the fourth embodiment. It is a block diagram which shows the light source drive device according to other embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description about them will not be repeated.

First Embodiment
<Overview of current setting system>
FIG. 1 is a conceptual diagram for illustrating an outline of a current setting system according to the first embodiment. Specifically, FIG. 1A is a diagram showing a connection form of each device in the case of setting the output current of the light source drive device 100. As shown in FIG. FIG. 1B is a diagram showing a connection form of each device in the case of confirming the value of the set output current.

Referring to FIG. 1, the current setting system is a system for setting the current output (supplied) to the light source from the light source driving device 100 (that is, flowing to the light source). Specifically, the current setting system includes a light source drive device 100, a light source 80, an ammeter 82, a voltage source 84, and a current setting unit 90.

Referring to FIGS. 1A and 1B, the light source drive device 100 includes a constant current drive circuit 10, a constant voltage circuit 20, a conversion circuit 30, a control circuit 40, and an input terminal 51. And an output terminal 52. The output terminal 52 is configured to be able to connect the light source 80 and the current setting unit 90.

The constant current drive circuit 10 controls the current flowing through the light source 80 to be a constant current. Specifically, during the normal operation in which the light source drive device 100 drives the light source 80, the constant current drive circuit 10 receives power from the voltage source 84 and executes constant current drive control of the light source 80.

The constant voltage circuit 20 converts the voltage applied to the output terminal 52 into a constant voltage, and outputs the constant voltage to the control circuit 40. The constant voltage is a power supply voltage of the control circuit 40. The conversion circuit 30 converts the voltage supplied from the current setting unit 90 via the output terminal 52, and outputs the converted voltage signal to the control circuit 40.

FIG. 2 is a diagram for explaining an example of a signal conversion method according to the first embodiment. Referring to FIG. 2, when the negative side of output terminal 52 is 0 V, a voltage (here, 10 V or more) which is larger than the power supply voltage (here, 5 V) output from constant voltage circuit 20 to control circuit 40. 6 V) is applied to the positive electrode side of the output terminal 52. In addition, a reference voltage used for signal conversion is set to 8V.

In this case, the conversion circuit 30 compares the voltage (for example, 10 V or 6 V) applied from the current setting unit 90 to the output terminal 52 with the reference voltage (for example, 5 V), and outputs a binary signal indicating the comparison result. Are output to the control circuit 40. In the example of FIG. 2, when the voltage applied to the output terminal 52 is equal to or higher than the reference voltage, the conversion circuit 30 outputs a High signal to the control circuit 40, and the voltage applied to the output terminal 52 is the reference voltage. If it is less than this, a Low signal is output to the control circuit 40.

Again referring to FIG. 1, control circuit 40 sets the current value of the constant current output from constant current drive circuit 10 based on the binary signal converted by conversion circuit 30. Here, for example, the High signal corresponds to data “1”, and the Low signal corresponds to data “0”. The High signal may correspond to data "0" and the Low signal may correspond to data "1".

In the example of FIG. 2, the control circuit 40 recognizes the signal received from the conversion circuit 30 as data “101010” because the conversion circuit 30 alternately outputs the High signal and the Low signal three times in this order. The control circuit 40 specifies the value of the constant current corresponding to the data with reference to the information table in which each data is associated with the current value of the constant current. The information table is stored in an internal memory (for example, non-volatile memory) of the control circuit 40. The control circuit 40 sets (that is, stores) the current value of the specified constant current in the internal memory, and outputs a setting signal indicating the set current value to the constant current drive circuit 10. The constant current drive circuit 10 controls so that the current value according to the setting signal flows to the light source 80 during normal operation.

The control circuit 40 may be configured to specify the value of the constant current without referring to the information table. For example, when the maximum value of the output current of the light source drive device 100 is 100%, the control circuit 40 is configured to read what percentage of the output current is to be from the level of the signal received from the conversion circuit 30. May be

FIG. 3 is a flowchart for explaining an example of the current setting method according to the first embodiment. Referring to FIG. 3, in the current setting method, as shown in FIG. 1A, the current setting unit 90 is connected to the output terminal 52 of the light source drive device 100 (step S10). The current setting unit 90 inputs a setting voltage (for example, a voltage as shown in FIG. 2) for setting the output current of the light source drive device 100 to a desired value to the output terminal 52 (step S12). At this time, the constant voltage circuit 20 converts the set voltage into a constant voltage, and supplies the constant voltage to the control circuit 40 as a power supply voltage.

The conversion circuit 30 compares the set voltage and the reference voltage, and outputs binary signals (High signal and Low signal) as a comparison result to the control circuit 40 (step S14). Control circuit 40 refers to the information table stored in the internal memory to identify the current value of the constant current associated with the data corresponding to the binary signal, and stores the identified current value in the internal memory (Step S16).

Next, as shown in FIG. 1B, the current setting unit 90 is removed from the output terminal 52 of the light source drive device 100, and the ammeter 82 is connected in series between the output terminal 52 and the light source 80. Are connected in parallel to the output terminal 52, and the voltage source 84 is connected in parallel to the input terminal 51 (step S18). The voltage source 84 applies a voltage to the input terminal 51 of the light source drive device 100 (step S20).

Control circuit 40 outputs a setting signal indicating the current value stored in the internal memory in step S16 to constant current drive circuit 10 (step S22). For example, the control circuit 40 converts the current value into an analog voltage value by a digital-to-analog (DA) conversion function provided internally, and outputs the converted analog voltage value as a setting signal. The constant current drive circuit 10 executes constant current drive control of the light source 80 according to the setting signal (step S24). The ammeter 82 measures the output current of the light source drive device 100 (that is, the current flowing to the light source 80) (step S26). Subsequently, it is determined whether the output current is within the target range (that is, within the tolerance of the target value) (step S28). Specifically, the determination may be performed by the user, or may be performed by a terminal device (not shown) such as a PC (personal computer) that has received the input of the measurement value of the ammeter 82. .

If the measured value of the output current is within the target range (YES in step S28), the light source 80, the ammeter 82, and the voltage source 84 are removed from the light source driving device 100 (step S30), and the process ends. If the output current is not within the target range (NO in step S28), the value of the set voltage of current setting unit 90 is adjusted to correct the deviation between the measured value of output current and the target value (step S32) ), Return to step S10. At this time, at least the voltage source 84 is removed from the light source drive device 100. The ammeter 82 and the light source 80 may remain connected to the light source drive device 100.

<Configuration of current setting unit>
FIG. 4 is a diagram showing an example of a circuit configuration of current setting unit 90 according to the first embodiment. Referring to FIG. 4, current setting unit 90 includes an internal voltage source 92, resistors Ra, Rb, Rc, Rd and Re, transistors Qa and Qb, a SIGNAL terminal, a Vout terminal, and a GND terminal. .

When a High signal is input to the SIGNAL terminal from a terminal device (for example, a PC, a microcomputer or the like), the transistor Qa is turned on (closed), so both ends of the resistor Rc are shorted. In this case, a voltage Vhi obtained by subtracting the base-emitter voltage Vbe of the transistor Q2 from the voltage obtained by dividing the voltage Vs of the internal voltage source 92 by the resistors Ra and Rb is output to the Vout terminal. Specifically, the voltage Vhi is expressed as the following equation (1).

Vhi = Vs x (Rb) / (Ra + Rb)-Vbe (1)
When a low signal is input from the terminal device to the SIGNAL terminal, the transistor Qa is turned off (opened). In this case, a voltage Vlo obtained by subtracting the base-emitter voltage Vbe of the transistor Q2 from the voltage obtained by dividing the voltage Vs by the resistor Ra and the combined resistor Rbc (= Rb + Rc) of the resistors Rb and Rc is given to the Vout terminal. It is output. Specifically, the voltage Vlo is represented by the following equation (2).

Vlo = Vs x (Rb + Rc) / (Ra + Rb + Rc)-Vbe (2)
By appropriately selecting the voltage Vs and the resistance values of the resistors Ra, Rb and Rc, the voltage is larger than the output voltage of the constant voltage circuit 20 (that is, the power supply voltage of the control circuit 40), and the voltage values are different. Two voltages can be output. Therefore, the current setting unit 90 can output a set voltage in which a signal is superimposed on the power supply voltage of the control circuit 40.

<Configuration of light source drive device>
FIG. 5 is a block diagram showing a configuration of light source drive device 100A according to the first embodiment. The light source drive device 100A corresponds to the light source drive device 100 shown in FIG. 1, but for the sake of distinction from the modification described later, an additional code such as "A" is added for convenience.

The light source drive device 100A includes a constant current drive circuit 10, a constant voltage circuit 20, a conversion circuit 30A, a control circuit 40, an input terminal 51, and an output terminal 52.

An operation example during normal operation in which the light source drive device 100A drives the light source 80 will be described. During normal operation, a voltage source 84 such as a commercial AC power source is connected to the input terminal 51, and a light source 80 such as an LED is connected to the output terminal 52.

Constant current drive circuit 10 receives supply of power from voltage source 84 through input terminal 51. The constant current drive circuit 10 drives the light source 80 at a constant current. Specifically, constant current drive circuit 10 supplies light source 80 with an output current of a current value according to the setting signal received from control circuit 40.

The constant voltage circuit 20 converts the voltage applied to the output terminal 52 into a constant voltage, and supplies the converted constant voltage to the control circuit 40. Specifically, the constant voltage circuit 20 is configured by the IC 21. The IC 21 is a three-terminal regulator IC configured of three terminals: an input terminal (“IN” in the drawing), an output terminal (“OUT” in the drawing), and a ground terminal (“GND” in the drawing). The IC 21 outputs a constant voltage if the input voltage is within the input voltage range of the IC 21. The constant voltage output by the IC 21 is used as a power supply voltage of the control circuit 40.

The control circuit 40 outputs, to the constant current drive circuit 10, a setting signal indicating the current value set (stored) in the internal memory. The current value is a current value of the output current (that is, constant current) supplied from the constant current drive circuit 10 to the light source 80. The control circuit 40 is configured of, for example, an IC 41 having a non-volatile memory such as a microcomputer. The IC 41 includes a VDD terminal as a power supply terminal on the positive side, a VSS terminal as a power supply terminal on the negative side, an IN terminal as an input terminal, an OUT terminal as an output terminal, and an IN_PWR terminal as an input terminal of a detection signal.

Here, the constant current drive circuit 10 includes a detection circuit 11 that detects an input voltage applied to the input terminal 51. Specifically, when detecting that the input voltage is equal to or higher than the threshold Th, the detection circuit 11 outputs a detection signal indicating the detection result to the control circuit 40 (IC 41). The control circuit 40 (IC41) is configured not to change the setting of the output current when receiving the input of the detection signal via the IN_PWR terminal.

Specifically, when the control circuit 40 receives an input of a detection signal through the IN_PWR terminal (that is, when the voltage of the input terminal 51 is equal to or higher than the threshold Th), the control circuit 40 converts the signal through the IN terminal. Even when a voltage signal is received from 30, the current value of the constant current corresponding to the voltage signal is not set (stored) in the internal memory. In other words, control circuit 40 stores the current value of the constant current corresponding to the voltage signal in the internal memory when the input of the detection signal is not received (that is, when the voltage of input terminal 51 is less than threshold Th). Do. As a result, during normal operation of the light source drive device 100A, when the set voltage is input from the output terminal 52 by chattering that can occur at the output terminal 52 when the light source 80 is removed from the output terminal 52, etc. Misrecognition can prevent the current value of the constant current from being changed by the set voltage.

When detecting that the input voltage is less than the threshold Th, the detection circuit 11 may output a detection signal indicating the detection result to the control circuit 40 (IC 41). In this case, the control circuit 40 (IC 41) determines that the input voltage is less than the threshold value based on the detection signal, and stores the current value of the constant current corresponding to the voltage signal in the internal memory.

Next, an operation example at the time of setting the output current of the constant current drive circuit 10 will be described. At the time of setting the output current, the current setting unit 90 is connected to the output terminal 52. The current setting unit 90 inputs a set voltage for setting the output current to a desired value to the output terminal 52. The constant voltage circuit 20 receives the set voltage and supplies a constant voltage to the control circuit 40.

The conversion circuit 30A outputs, to the control circuit 40, a voltage signal obtained by converting the set voltage received into an input voltage range of the control circuit 40. Specifically, conversion circuit 30A is configured of a voltage comparison circuit including resistors R1 and R2, NPN transistor Q1, and zener diode ZD1 to determine whether the voltage at output terminal 52 is equal to or higher than the reference voltage. Be done.

In detail, when the setting voltage applied to the output terminal 52 by the current setting unit 90 is equal to or more than "the voltage between the base emitter of the NPN transistor Q1 + the Zener voltage of the Zener diode", the current limited by the resistor R1. Flows to the base of the NPN transistor Q1, and the NPN transistor Q1 is turned on. As a result, the current amplified by the current amplification action of the NPN transistor Q1 is drawn from the collector of the NPN transistor Q1 to cause a voltage drop of the resistor R2, so the Llow signal is sent to the control circuit 40 (IN terminal of IC41). It is output.

On the other hand, when the setting voltage applied to the output terminal 52 by the current setting unit 90 is less than "the voltage between the base emitter of the NPN transistor Q1 + the Zener voltage of the Zener diode", no current flows through the resistor R1. Therefore, the NPN transistor Q1 is turned off. As a result, the collector of the NPN transistor Q1 rises to the output voltage of the constant voltage circuit 20 by the resistor R2 and outputs a High signal to the control circuit 40.

The control circuit 40 receives the High signal and the Low signal output from the conversion circuit 30A, and rewrites the set value of the output current stored in the internal memory according to the contents of these signals.

(Modification 1)
FIG. 6 is a block diagram showing a light source drive device 100B according to the first modification of the first embodiment. The light source drive device 100B has a configuration in which the conversion circuit 30A of the light source drive device 100A is replaced with a conversion circuit 30B. Therefore, the detailed description of the configuration other than conversion circuit 30B in light source drive device 100B will not be repeated.

The conversion circuit 30B is a resistive voltage dividing circuit including resistors R3 and R4 and a Zener diode ZD2. In this case, a voltage obtained by dividing the voltage of the output terminal 52 by the resistors R3 and R4 is input to the IN terminal of the IC 41. In this case, the control circuit 40 converts a voltage input by an AD (Analog-to-digital) converter provided therein into a digital signal, and is stored in the internal memory according to the content of the digital signal. Rewrite the set value of the output current.

Generally, a voltage dividing resistor for detecting an output voltage is provided between ± of the output terminal 52, so that the conversion circuit 30B can be configured without newly adding a resistance element. During normal operation, the Zener diode ZD2 serves as a protection element so that the voltage input from the conversion circuit 30B to the control circuit 40 (specifically, the IN terminal) does not exceed the input voltage range of the control circuit 40. Connected in parallel to R4.

(Modification 2)
FIG. 7 is a block diagram showing a light source drive device 100C according to the second modification of the first embodiment. The light source drive device 100C has a configuration in which the conversion circuit 30A of the light source drive device 100A is replaced with a conversion circuit 30C. Therefore, the detailed description of the configuration other than conversion circuit 30C in light source drive device 100C will not be repeated.

The conversion circuit 30C is a voltage comparison circuit including resistors R5, R6, R7 and R8, a Zener diode ZD3 and a comparator 31. In the example of FIG. 7, a voltage obtained by dividing the voltage of the output terminal 52 by the resistors R 7 and R 8 is input to the non-inverting input terminal of the comparator 31. Further, a voltage obtained by dividing the output voltage of the IC 21 by the resistors R5 and R6 is input to the inverting input terminal of the comparator 31. The voltage input to the inverting input terminal is the threshold voltage of the comparator 31. A Zener diode ZD3 as a protection element is connected in parallel to the resistor R8 so that the voltage obtained by dividing the voltage of the output terminal 52 by the resistors R7 and R8 does not exceed the input voltage range of the comparator 31.

Here, let two voltage values input from the current setting unit 90 to the output terminal 52 be a voltage value V1 and a voltage value V2, respectively. In this case, a voltage value V1p (= V1 × R8 / (R7 + R8)) obtained by dividing the voltage value V1 by the resistors R7 and R8 or a voltage obtained by dividing the voltage value V2 by the resistors R7 and R8. The value V2p (= V2 × R8 / (R7 + R8)) is input.

Therefore, the voltage (that is, the threshold voltage) input to the inverting input terminal is set between the voltage value V1p and the voltage value V2p. Thus, for example, when the comparator 31 receives the input of the voltage value V1p, it outputs the voltage corresponding to the data “1” to the IC 41, and when the input of the voltage value V2p is received, the data “0” The voltage corresponding to “1” is output to the IC 41.

In the conversion circuit 30C, a voltage having good temperature characteristics, such as the output voltage of the three-terminal regulator IC, can be used as the threshold voltage of the comparator 31. Thereby, the conversion accuracy from the voltage of the output terminal 52 to the signal for the control circuit 40 is improved.

<Advantage>
According to the first embodiment, the current setting unit can be connected to the terminal for light source connection provided in the light source drive device, and the output current of the constant current drive circuit can be set by the current setting unit. . Therefore, there is no need to provide a connection terminal dedicated to the current setting unit. Further, only the input terminal and the output terminal of the light source drive device are exposed to the outside, so that the waterproof measure of the light source drive device is facilitated. In addition, it is not necessary to provide the current setting unit in the light source drive device.

In addition, fine adjustment of the output current can also be performed by repeatedly measuring and resetting the output current after setting the output current. Furthermore, even after the lighting device to which the light source drive device is applied is installed on a ceiling or the like, the brightness of the lighting device can be changed simply by connecting the current setting unit to the connection terminal for the light source. , The work of the change becomes easy.

Second Embodiment
In light source drive device 100 according to the first embodiment, when the load voltage of light source 80 connected to output terminal 52 is high during normal operation, high voltage is applied to constant voltage circuit 20, and constant voltage circuit 20 is damaged. there's a possibility that. Therefore, in the second embodiment, even if the load voltage of the light source 80 is high, a protection circuit for protecting the constant voltage circuit 20 from high voltage is added to the light source drive device so that the constant voltage circuit 20 is not damaged. The described configuration is described.

The light source drive device according to the second embodiment differs from the light source drive device 100 according to the first embodiment in that the light source drive device according to the second embodiment includes the protection circuit of the constant voltage circuit 20. The configurations of <an outline of the current setting system> and <a current setting unit> are the same as in the first embodiment, and therefore detailed description thereof will not be repeated.

FIG. 8 is a block diagram of a light source drive device 200A according to the second embodiment. Referring to FIG. 8, light source drive device 200A includes constant current drive circuit 10, constant voltage circuit 20, conversion circuit 30A, control circuit 40, input terminal 51, output terminal 52, and protection circuit 60A. including. That is, the light source drive device 200A has a configuration in which a protection circuit 60A is added to the light source drive device 100A shown in FIG. Therefore, the detailed description of the configuration other than protection circuit 60A in light source drive device 200A will not be repeated.

The protection circuit 60A is provided between the output terminal 52 and the constant voltage circuit 20. The protection circuit 60A reduces the voltage of the output terminal 52 to such an extent that the constant voltage circuit 20 is not damaged, and outputs the reduced voltage to the constant voltage circuit 20.

Specifically, protection circuit 60A includes resistors R10 and R11, an NPN transistor Q10, and a zener diode ZD10. The resistor R10 and the zener diode ZD10 create a constant voltage from the voltage of the output terminal 52. The NPN transistor Q10 and the resistor R11 enhance the current drive capability. According to the protection circuit 60A, even when a high voltage is applied to the NPN transistor Q10, a predetermined voltage (constant voltage) lower than the Zener voltage of the Zener diode ZD10 by the base-emitter voltage of the NPN transistor Q10 is a constant voltage circuit. Supplied to 20. That is, the protection circuit 60A reduces the voltage of the output terminal 52 to a predetermined voltage and outputs the predetermined voltage to the constant voltage circuit 20. Thereby, the constant voltage circuit 20 can be protected.

Further, at the time of setting the output current, as the voltage input from the current setting unit 90 to the output terminal 52 is higher, the conversion accuracy of the signal input to the control circuit 40 is improved. By providing the protection circuit 60A, the constant voltage circuit 20 is not damaged even if a high voltage is input from the current setting unit 90 to the output terminal 52, so that the signal conversion accuracy can be improved.

(Modification 1)
During normal operation of the light source drive device, when the load voltage of the light source 80 connected to the output terminal 52 is high, the bias current of the constant voltage circuit 20, the conversion circuit 30A and the control circuit 40 is protected from the constant current drive circuit 10. If it flows through the circuit 60A, the loss is large. Therefore, in the first modification of the second embodiment, the auxiliary power supply circuit is provided in the constant current drive circuit, and the bias current is not supplied from the constant current drive circuit through the protection circuit during the normal operation.

FIG. 9 is a block diagram of a light source drive device 200B according to the first modification of the second embodiment. Referring to FIG. 9, light source drive device 200B has a configuration in which constant current drive circuit 10 of light source drive device 200A is replaced with constant current drive circuit 10B, and protection circuit 60A of light source drive device 200A is replaced with protection circuit 60B. . Therefore, the detailed description of the configuration other than the constant current drive circuit 10B and the protection circuit 60B in the light source drive device 200B will not be repeated.

The auxiliary power supply circuit 12 is constituted by, for example, a DC-DC switching control circuit, and the output voltage value is about 15V. In normal operation, voltage source 84 is connected to constant current drive circuit 10B through input terminal 51, so that auxiliary power supply circuit 12 operates, and the output voltage of auxiliary power supply circuit 12 is input to the input terminal of constant voltage circuit 20. Ru.

Protection circuit 60B includes resistors R10 and R11, an NPN transistor Q10, a Zener diode ZD10, and a diode D10. The resistor R10 and the zener diode ZD10 create a constant voltage from the voltage of the output terminal 52. The NPN transistor Q10 and the resistor R11 enhance the current drive capability. Further, at the time of setting the output current, a bias current is supplied from the output terminal 52 to the constant voltage circuit 20, the conversion circuit 30A, and the control circuit 40 through the diode D10.

Further, the emitter voltage of the NPN transistor Q10 is set lower than the output voltage of the auxiliary power supply circuit 12 by the forward voltage of the diode D10 or more. Thus, in the normal operation, the diode D10 is reverse biased by the output voltage of the auxiliary power supply circuit 12. Therefore, no bias current flows to the constant voltage circuit 20, the conversion circuit 30A, and the control circuit 40 through the diode D10, so that the power loss can be reduced.

As described above, in the light source drive device 200B, when the voltage source 84 is connected to the input terminal 51 during the normal operation, the auxiliary power supply circuit 12 outputs the voltage Vx1 to the constant voltage circuit 20. In addition, at the time of setting the output current, when the voltage source 84 is not connected to the input terminal 51 and the current setting unit 90 is connected to the output terminal 52, the protection circuit 60B performs the constant voltage circuit 20 on the voltage Vx2. Output to The voltage Vx1 output from the auxiliary power supply circuit 12 to the constant voltage circuit 20 and the voltage Vx2 output from the protection circuit 60B to the constant voltage circuit 20 may be within the input voltage range of the IC 21 and may be the same. It may be different.

(Modification 2)
In the first modification of the second embodiment, the auxiliary power supply circuit is provided in the constant current drive circuit to prevent the bias current from flowing from the constant current drive circuit through the protection circuit in the normal operation. . In the second modification of the second embodiment, in order to prevent the bias current from flowing from the constant current drive circuit through the protection circuit at the time of normal operation, an example in which the protection circuit is configured by a voltage control circuit of switching control system explain.

FIG. 10 is a block diagram of a light source drive device 200C according to the second modification of the second embodiment. Referring to FIG. 10, light source drive device 200C has a configuration in which protection circuit 60A of light source drive device 200A is replaced with protection circuit 60C. Therefore, detailed description of the configuration other than protection circuit 60C in light source drive device 200C will not be repeated.

The protection circuit 60C is a step-down chopper circuit including a switching element Q11, a capacitor C10, an inductor L10, a free wheeling diode D11, a diode D12, and an IC 61. The switching element Q11 is an N-channel type MOSFET (metal-oxide-semiconductor field-effect transistor). The IC 61 is an IC for controlling the on / off of the switching element Q11. The diode D12 is a diode for supplying a current to the IC 61.

The protection circuit 60C converts the voltage of the output terminal 52 into a predetermined voltage, and outputs the predetermined voltage to the constant voltage circuit 20. Further, according to the protection circuit 60C configured by the voltage control circuit of the switching control method, the bias current flowing from the constant current drive circuit 10 is reduced during the normal operation of the light source drive device 200C. Power loss can be reduced. The power loss due to the bias current is reduced because of the difference between the linear method and the switching method.

Specifically, assuming that the loss when all the bias current flows from the output of the constant current drive circuit 10 is WLoss 1, the output voltage of the constant current drive circuit 10 is Vоut, and the bias current is Ibias, the following equation (1) holds Do.

Wloss1 = Vout × Ibais (1)
In addition, the loss when the bias current flows from the output of the switching control method voltage conversion circuit is Wloss2, the output voltage of the switching control method voltage conversion circuit is Vaux, the bias current is Ibias, and the power conversion of the switching control method voltage conversion circuit Assuming that the efficiency is η, the following equation (2) is established.

Wloss2 = Vaux × Ibais × η (2)
Therefore, when Vout> Vaux × η holds, the power loss due to the bias current is smaller when the voltage control circuit of the switching control method is used. Normally, 70% or more can be expected.

(Modification 3)
The third modification of the second embodiment describes a configuration in which the protection circuit 60C according to the second modification is provided in the constant current drive circuit.

FIG. 11 is a block diagram of a light source drive device 200D according to the third modification of the second embodiment. Referring to FIG. 11, the light source drive device 200D has a configuration in which the constant current drive circuit 10 of the light source drive device 200A is replaced with a constant current drive circuit 10D. Therefore, the detailed description of the configuration other than the constant current drive circuit 10D in the light source drive device 200D will not be repeated.

The constant current drive circuit 10D includes a detection circuit 11, a switching control circuit 13 for controlling an output current (constant current), and a protection circuit 60C.

The switching control circuit 13 is a step-down chopper circuit including a switching element Q20, a body diode D21, a capacitor C20, an inductor L20, a free wheeling diode D20, and an IC 15. The switching element Q20 is an N-channel MOSFET.

As described above, when the step-down circuit of the switching control system such as the switching control circuit 13 is used as the circuit for controlling the constant current, the protection circuit 60C can be provided in the constant current drive circuit 10D.

When setting the output current, a voltage can be supplied from the output terminal 52 to the protection circuit 60C through the body diode D21 of the switching element Q20 of the switching control circuit 13. The protection circuit 60C reduces the voltage of the output terminal 52 to a predetermined voltage and inputs the predetermined voltage to the IN terminal of the constant voltage circuit 20 to protect the constant voltage circuit 20.

The protection circuit 60C also functions as an auxiliary power supply circuit. Specifically, during normal operation of the light source drive device 200D, even if the load voltage of the light source 80 is high, bias current is supplied to the constant voltage circuit 20, the conversion circuit 30A, and the control circuit 40 while suppressing the power loss. can do. An increase in the number of elements can also be suppressed by using the protection circuit 60C as an auxiliary power supply circuit.

<Advantage>
According to the second embodiment, in addition to the advantages of the first embodiment, the constant voltage circuit can be appropriately protected.

Third Embodiment
In the third embodiment, a configuration of a lighting device including the light source drive device according to the first or second embodiment and the light source 80 will be described.

FIG. 12 is a block diagram showing an example of a configuration of lighting device 300 according to the third embodiment. Referring to FIG. 12, lighting device 300 includes light source driving device 200B shown in FIG. 9 and light source 80. The light source drive device 200 B is connected to the light source 80 via the output terminal 52. Here, although the light source drive device 200B will be described as a representative example of the "light source drive device", it is not limited thereto. The “light source drive device” may be any of the light source drive devices 100A to 100C, 200A, 200C, and 200D described above.

When the lighting device 300 is a type of lighting device capable of separating the light source 80, the output terminal 52 is exposed to the outside by removing the light source 80 from the output terminal 52. Therefore, by connecting the current setting unit 90 to the output terminal 52, the output current of the constant current drive circuit 10 can be set.

Further, even in the case where the lighting device 300 is a type of lighting device in which the light source 80 can not be separated, it is possible to connect the output terminal 52 from the outside by removing a part of the housing of the lighting device 300. Good. Thus, similarly, the current setting unit 90 can be connected to the output terminal 52 to set the output current of the constant current drive circuit 10.

(Modification)
FIG. 13 is a block diagram showing an example of a configuration of a lighting apparatus 400 according to a modification of the third embodiment. Referring to FIG. 13, lighting device 400 includes light source driving device 200 </ b> B shown in FIG. 9 and light source 80. The light source drive device 200 B is connected to the light source 80 via the output terminal 52. Lighting device 400 differs from lighting device 300 shown in FIG. 12 in that output terminal 52 is exposed to the outside.

The output terminal 52 of the lighting device 400 is exposed to the outside while maintaining an appropriate insulation distance from the outer shell of the housing of the lighting device 400. Alternatively, the lighting device 400 further includes another output terminal connected in parallel to the output terminal 52, and the other output terminal is provided outside while maintaining an appropriate insulation distance from the outer shell of the housing of the lighting device 400. It may be exposed. In this case, the output terminal 52 or the other output terminal may be covered with a cover or the like to prevent adhesion of dust or the like. Thus, the current setting unit 90 can be connected to the output terminal 52 or another output terminal to set the output current of the constant current drive circuit 10.

<Advantage>
According to the third embodiment, even when the light source drive device is incorporated in the lighting device, the output terminal of the light source drive device can be accessed from the outside, so that the output current can be set by the current setting unit. . In addition, even after the lighting device is installed on a ceiling or the like, the output current can be easily changed without performing work such as disassembly or construction of the lighting device.

Fourth Embodiment
In the first embodiment, the current setting method in the case where the light source 80 can be separated from the light source driving device 100 has been described with reference to FIG. In the fourth embodiment, the light source driving device and the light source 80 are integrally configured, and a current setting method in the case where the light source 80 can not be separated from the light source driving device will be described.

FIG. 14 is a conceptual diagram for illustrating an outline of a current setting system according to the fourth embodiment. Specifically, FIG. 14A is a view showing a connection form of each device in the case of setting the output current of the light source drive device 100. FIG. 14B is a diagram showing a connection form of each device in the case of confirming the illuminance of the light emitted from the light source 80 by the set output current.

Referring to FIG. 14, the current setting system includes a lighting device 500, a current setting unit 90, and a light meter 86. The illumination device 500 includes a light source drive device 100, a light source 80, and an output terminal 54 connected in parallel to the output terminal 52 of the light source drive device 100. The output terminal 54 is exposed to the outside of the lighting device 500. The illumination device 500 is a type of illumination device in which the light source drive device 100 and the light source 80 are integrally configured, and the light source 80 can not be separated from the light source drive device 100. Here, although the light source drive device 100 will be described as a representative example of the “light source drive device”, it is not limited thereto. The “light source drive device” may be any of the light source drive devices 200A to 200D described above.

FIG. 15 is a flowchart for illustrating an example of the current setting method according to the fourth embodiment. Referring to FIG. 15, in the current setting method, current setting unit 90 is connected to output terminal 54 of lighting device 500 as shown in FIG. 14A (step S50). The current setting unit 90 inputs a setting voltage for setting the output current of the light source drive device 100 to a desired value through the output terminal 54 (step S52).

Since the processes of steps S54 and S56 are the same as the processes of steps S14 and S16 in FIG. 3, the detailed description thereof will not be repeated. Subsequently, as shown in FIG. 14B, the current setting unit 90 is removed from the output terminal 54, the voltage source 84 is connected in parallel to the input terminal 51, and the illuminance meter 86 is installed around the lighting device 500. (Step S58). The processes of steps S60 to S64 are similar to the processes of steps S20 to S24 in FIG. 3, respectively, and therefore the detailed description thereof will not be repeated.

The illuminance meter 86 measures the illuminance of the lighting device 500 (light source 80) (step S66). Subsequently, it is determined whether the measured illuminance is within the target range (that is, within the tolerance of the target value) (step S68). Specifically, the user may make the determination, or the determination may be made by a terminal device (not shown) that has received the input of the measurement value of the illuminance meter 86.

If the measured value of the illuminance is within the target range (YES in step S68), voltage source 84 is disconnected from lighting device 500 (step S70), and the process ends. If the illuminance is not within the target range (NO in step S68), the value of the set voltage of the current setting unit 90 is adjusted to correct the deviation between the measured value of the illuminance and the target value (step S72), It returns to step S50. At this time, the voltage source 84 is removed from the lighting device 500.

<Advantage>
According to the fourth embodiment, even with the illumination device in which the light source drive device and the light source are integrally formed, fine adjustment of the output current of the light source drive device, that is, the brightness of the illumination device is performed by using the illuminance meter. Can.

[Other Embodiments]
(1) In the embodiment described above, as shown in FIG. 11, the configuration has been described in which the constant current drive circuit has a switching control circuit for constant current output control as a voltage conversion circuit. I can not. For example, as shown in FIG. 16, the constant current drive circuit may be connected in series to the output terminal (light source), and the voltage conversion circuit may be provided separately from the constant current drive circuit.

FIG. 16 is a block diagram showing a light source drive device 100D according to another embodiment. Specifically, FIG. 16A is a block diagram showing the whole of the light source drive device 100D. FIG. 16B is a block diagram showing an example of the constant current drive circuit 10E.

Referring to FIG. 16A, light source drive device 100D includes a constant current drive circuit 10E, a constant voltage circuit 20, a conversion circuit 30, a control circuit 40, and a voltage conversion circuit 70. The detailed description of the configuration other than the constant current drive circuit 10E and the voltage conversion circuit 70 in the light source drive device 100D will not be repeated.

The voltage conversion circuit 70 is, for example, a switching control type voltage conversion circuit, and controls the output voltage such that the negative terminal of the output terminal 52 is a constant voltage as small as possible. This is because the product of the voltage between GND and the negative terminal of the output terminal 52 and the output current is a loss, so controlling by giving a margin to the lowest voltage at which the constant current drive circuit 10E operates is a loss. This is because it can be minimized.

Referring to FIG. 16B, constant current drive circuit 10E is connected in series to output terminal 52 (minus terminal side), and performs constant current control on the current flowing to light source 80 connected to output terminal 52. Specifically, constant current drive circuit 10E includes a constant current element Q25, a diode D25, a resistor R15, and an operational amplifier 35.

The constant current element Q25 is an N-channel MOSFET or a bipolar transistor. The reference voltage (setting signal) from the control circuit 40 is input to the positive terminal of the operational amplifier 35. In addition, negative feedback is applied such that the voltage across the resistor R15 is equal to the positive terminal voltage of the operational amplifier 35. The output terminal of the operational amplifier 35 is connected to the gate of the constant current element Q25. Thereby, the operational amplifier 35 controls so that a constant current according to the setting signal flows to the resistor R15 (that is, the light source 80 connected to the output terminal 52). That is, the constant current drive circuit 10E can execute constant current control such that a current value according to the setting signal flows to the light source 80 connected to the output terminal 52 during normal operation.

The diode D25 bypasses the constant current element Q25 so that the current output from the current setting unit 90 connected to the output terminal 52 can return. When constant current element Q25 is an N-channel MOSFET, a body diode is incorporated as a parasitic element. Therefore, in this case, the constant current drive circuit 10E may not include the diode D25.

The light source drive device 100D may be adopted as the light source drive device of the illumination device described in the third and fourth embodiments described above, and the protection circuit described in the second embodiment is added to the light source drive device 100D. It may be a light source drive device.

(2) In the embodiment described above, the light source driving device includes the constant voltage circuit, but the present invention is not limited to this configuration. For example, when the power supply voltage of the control circuit is configured to correspond to an arbitrary voltage, the constant voltage circuit may not be provided.

(3) In the embodiment described above, the configuration in which the auxiliary power supply circuit and the detection circuit are provided in the constant current drive circuit has been described, but the present invention is not limited to this configuration. For example, each of the auxiliary power supply circuit and the detection circuit may be provided independently of the constant current drive circuit.

(4) The configuration exemplified as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part of the configuration can be made without departing from the scope of the present invention. It is also possible to change and configure, such as omitting.

Furthermore, in the embodiment described above, the processes and configurations described in the other embodiments may be adopted appropriately and implemented.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the above description but by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 10 constant current drive circuit, 11 detection circuit, 12 auxiliary power supply circuit, 13 switching control circuit, 20 constant voltage circuit, 30 conversion circuit, 31 comparator, 35 operational amplifier, 40 control circuit, 51 input terminal, 52, 54 output terminal, 60A , 60B, 60C, 60D protection circuit, 80 light sources, 82 ammeters, 84 voltage sources, 86 illuminance meters, 90 current setting units, 92 internal voltage sources, 100, 200A to 200D light source drive devices, 300, 400, 500 lighting devices , C10, C20 capacitor, D10, D12 diode, D11, D20 free wheeling diode, D21 body diode, L10, L20 inductor.

Claims

A first terminal to which a light source can be connected and to which a setting unit for setting a current flowing to the light source can be connected;
A constant current drive circuit that controls the current flowing to the light source to be a constant current;
A conversion circuit that converts a voltage supplied from the setting unit connected to the first terminal and outputs the converted voltage signal;
A control circuit configured to set a current value of the constant current based on the converted voltage signal and output a setting signal indicating the set current value to the constant current drive circuit.
It further comprises a constant voltage circuit for supplying a constant voltage to the control circuit,
The light source drive device according to claim 1, wherein when the setting unit is connected to the first terminal, the constant voltage circuit converts a voltage supplied from the setting unit into the constant voltage.
It further comprises a protection circuit connected between the first terminal and the constant voltage circuit for protecting the constant voltage circuit,
The light source drive device according to claim 2, wherein the protection circuit reduces the voltage of the first terminal to a predetermined voltage and outputs the predetermined voltage to the constant voltage circuit.
A second terminal to which an external power supply can be connected;
An auxiliary power supply circuit for outputting a predetermined voltage to the constant voltage circuit;
When the external power supply is connected to the second terminal, the auxiliary power supply circuit is configured to output the predetermined voltage to the constant voltage circuit.
When the external power supply is not connected to the second terminal and the setting unit is connected to the first terminal, the protection circuit outputs the predetermined voltage to the constant voltage circuit. The light source driving device according to claim 3 configured as follows.
The converter circuit according to any one of claims 1 to 4, wherein the conversion circuit compares a voltage supplied from the setting unit with a reference voltage, and outputs a binary signal indicating a comparison result as the voltage signal to the control circuit. The light source drive device as described in a term.
The converter circuit according to any one of claims 1 to 4, wherein the conversion circuit divides the voltage supplied from the setting unit by a plurality of resistors and outputs a signal corresponding to the divided voltage as the voltage signal to the control circuit. The light source drive device according to any one of the preceding items.
The constant current drive circuit is connected in series to the first terminal, and controls the current flowing to the light source connected to the first terminal to become a constant current according to the setting signal. The light source driving device according to any one of items 1 to 6.
A light source drive device according to any one of claims 1 to 7;
A lighting device comprising the light source.
The lighting device according to claim 8, wherein the first terminal is exposed to the outside.
A current setting method for setting a current supplied from a light source driving device to a light source, the current setting method comprising:
The light source drive device includes a light source, a terminal to which a setting unit for setting a current flowing to the light source can be connected, and a constant current driving circuit that controls the current flowing to the light source to be a constant current. ,
The current setting method is
Converting a voltage supplied from the setting unit connected to the terminal and outputting the converted voltage signal;
Setting the current value of the constant current based on the converted voltage signal;
Outputting a setting signal indicating the current value set in the setting step to the constant current drive circuit.