JP2014049244A - Led driver and lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED driver having a wide adjustable range and capable of lighting control with high adjustment freedom.SOLUTION: An LED driver 1 comprises: a DC/DC converter 2 for driving an LED module 10; a lighting control unit 3; and a lighting control signal generation circuit 4. The LED driver 1 performs lighting control operation of the LED module 10 by outputting a lighting control signal Sd from the lighting control signal generation circuit 4 to the DC/DC converter 2. The lighting control signal generation circuit 4 purifies a DC voltage signal corresponding to the on-duty of a PWM signal Sp sent from the lighting control unit 3, and outputs as a lighting control signal Sd. When a control signal Sc is sent from the lighting control unit 3, the lighting control signal generation circuit 4 adjusts the magnitude of a DC voltage signal depending on that control signal, and outputs the DC voltage signal thus adjusted as a lighting control signal Sd.

Description

  The present invention relates to an LED driving device and a lighting fixture, and more particularly to an LED driving device and a lighting fixture that perform dimming control of an LED module.

  In recent years, an LED module including a plurality of LEDs (light emitting diodes) has been used as a light source in lighting fixtures and the like. Such an LED module is driven and lit by an LED driving device. As an LED drive device, there is one that turns on an LED module by dimming control.

  Patent Document 1 below discloses a constant current circuit that drives an illumination light source with a constant current, a constant current switching circuit that switches a constant current value of the constant current circuit, and a PWM that controls the illumination light source according to the duty of a PWM signal. The structure of the illumination light control apparatus provided with the drive circuit is disclosed. In this apparatus, the PWM control is performed by varying the on-duty of the PWM signal indicating the proportion of the period during which the switching element is turned on for a predetermined period. Thereby, dimming control of the LED light source is performed.

JP 2005-332586 A

  The LED driving device as described in Patent Document 1 has the following problems.

  Such a luminaire is required to have a high degree of dimming (a wide range of dimming intensity). At the limit value of the on duty (pulse width) of the PWM signal for turning on the switching element (that is, the minimum adjustment value of the pulse width), the dimming degree reaches the dimming lower limit by PWM control. In order to deepen the dimming degree, it is necessary to make the on-duty of the PWM signal as small as possible. However, this has a limit, and there is a problem that the dimming degree cannot be further deepened.

  In addition, the dimming adjustment is performed in a stepwise manner (up and down in a non-linear manner) because it is performed with a digital value by the on-duty of the PWM signal. In other words, there is a problem that dimming cannot be performed smoothly (linearly) and finely. Since the dimming degree is adjusted only by the on-duty, the degree of freedom of dimming is reduced.

  In particular, in connection with the first problem, the above-described LED is used in a lighting fixture that adjusts the relative color temperature by adjusting the color temperature using two LED light sources having different color temperatures. When the driving device is used, the following problems occur. That is, in such a lighting fixture, the relative color temperature moves to the color temperature side of the other light source as the illuminance of one LED light source is reduced (= the dimming degree is lowered). In the color temperature range of a single light source of each LED light source, there is a minimum limit value of the dimming degree of the other LED light source. Therefore, when dimming to a relative color temperature that approximates the color temperature of a single light source of each LED light source, there is a problem that it is difficult to make fine adjustments and it is difficult to obtain a natural dimming result. .

  The present invention has been made to solve such problems, and an object of the present invention is to provide an LED driving device and a lighting fixture capable of dimming with a wide adjustable range and a high degree of freedom of adjustment. .

  In order to achieve the above object, according to one aspect of the present invention, an LED driving device that performs dimming operation of an LED (light emitting diode) module according to a dimming instruction signal includes a driving circuit unit that outputs driving power to the LED module; The dimming instruction signal is input, and the dimming control unit that generates an on-duty PWM (pulse width modulation) signal corresponding to the dimming instruction signal, and the PWM signal generated by the dimming control unit are turned on. A dimming signal generation circuit that converts the DC voltage signal corresponding to the duty and outputs the dimming signal as a dimming signal to the drive circuit unit, and the dimming control unit is a control for adjusting the DC voltage signal When the control signal is input from the dimming control unit, the dimming signal generation circuit adjusts the magnitude of the DC voltage signal according to the control signal and adjusts the adjusted DC voltage signal. And outputs to the drive circuit unit as a signal.

  Preferably, the dimming signal generation circuit converts the PWM signal into a DC voltage signal and outputs the dimming signal to the drive circuit unit, and the direct current according to the control signal input from the dimming control unit A dimming signal adjustment circuit for adjusting the magnitude of the voltage signal and adjusting the dimming signal output from the signal conversion circuit.

  Preferably, the dimming control unit outputs a control signal to the dimming signal adjustment circuit when the on-duty of the PWM signal is a predetermined value or less.

  Preferably, the dimming signal adjustment circuit operates in a plurality of adjustment modes according to the control signal, and the dimming control unit changes the combination of the on-duty level of the PWM signal and the adjustment mode of the dimming signal adjustment circuit. As a result, the dimming signal generation circuit changes the magnitude of the DC voltage signal.

  Preferably, the dimming signal adjustment circuit includes at least one voltage dividing circuit unit, and controls the operation of the at least one voltage dividing circuit unit according to the control signal output from the dimming control unit, whereby the DC voltage Adjust the signal magnitude.

  Preferably, the dimming signal adjustment circuit includes a plurality of voltage dividing circuit units, and operates among the plurality of voltage dividing circuit units in accordance with a control signal input to each of the plurality of voltage dividing circuit units from the dimming control unit. The magnitude of the DC voltage signal is adjusted by changing the combination of the voltage dividing circuit sections to be performed.

  According to another aspect of the present invention, the luminaire includes one or more LED modules each composed of a single LED unit in which one or more LEDs are connected in series, or one or more LEDs formed by connecting a plurality of LED units in parallel. A module, one or more LED driving devices described above that drive each of the one or more LED modules, and a dimming control device that outputs a dimming instruction signal to each of the one or more LED driving devices. Prepare.

  According to these inventions, when the control signal is input from the dimming control unit, the dimming signal generation circuit adjusts the magnitude of the DC voltage signal according to the control signal, and dimmes the adjusted DC voltage signal. The signal is output as a signal to the drive circuit unit. Therefore, it is possible to provide an LED drive device and a lighting fixture that can adjust light with a wide adjustable range and a high degree of freedom of adjustment.

It is a block diagram which shows the structure of the lighting fixture using the LED drive device in the 1st Embodiment of this invention. It is a block diagram which shows the structure of an LED drive device and an LED module. It is a figure which shows an example of the circuit structure of a DC / DC converter. It is a figure which shows an example of the circuit structure of a light control signal generation circuit. It is a figure which shows the adjustment aspect of a light control signal adjustment circuit. It is a graph which shows an example of the relationship between the light control signal in the conventional lighting fixture, and the luminous intensity of an LED module. It is a graph which shows the 1st example of the relationship between the light control signal in this Embodiment, and the luminous intensity of an LED module. It is a graph which shows the 2nd example of the relationship between the light control signal in this Embodiment, and the luminous intensity of an LED module. It is a graph which shows the 3rd example of the relationship between the light control signal in this Embodiment, and the luminous intensity of an LED module. It is a graph which shows the 4th example of the relationship between the light control signal in this Embodiment, and the luminous intensity of an LED module. It is a block diagram which shows the structure of the lighting fixture which concerns on 2nd Embodiment. It is a figure which shows the relationship between the color temperature of each LED module in a lighting fixture, and illumination intensity.

  Hereinafter, the lighting fixture using the LED drive device in embodiment of this invention is demonstrated.

  [First Embodiment]

  FIG. 1 is a block diagram illustrating a configuration of a lighting fixture using the LED driving device according to the first embodiment of the present invention.

  As shown in FIG. 1, the lighting fixture 50 includes an LED driving device 1, an LED module 10, and a dimming control device 20. The luminaire 50 performs illumination when the LED module 10 is driven and turned on.

  The LED driving device 1 is connected to the LED module 10. The LED driving device 1 drives the LED module 10.

  In the present embodiment, the LED driving device 1 is connected to the dimming control device 20. The dimming control device 20 outputs a dimming instruction signal Sad to the LED driving device 1. The LED driving device 1 performs a dimming operation of the LED module 10 based on the dimming instruction signal Sad sent from the external dimming control device 20. That is, in the lighting fixture 50, the brightness of the illumination by the LED module 10 can be changed.

  The dimming instruction signal Sad is, for example, a digital signal.

  The dimming control device 20 is, for example, a remote controller provided in the lighting fixture 50 in order to change the brightness. The connection between the light control device 20 and the LED driving device 1 may be wired or wireless. For example, when the dimming control device 20 and the LED driving device 1 are connected wirelessly, the dimming control device 20 is provided with a light emitting unit, the LED driving device 1 is provided with a light receiving unit, and infrared communication is performed between the two. It may be configured to perform.

  FIG. 2 is a block diagram illustrating configurations of the LED driving device 1 and the LED module 10.

  As shown in FIG. 2, in the present embodiment, the LED module 10 includes LED units 11 and 12 formed by connecting a plurality of LEDs in series. The LED module 10 is configured by connecting an LED unit 11 and an LED unit 12 in parallel.

  The LED module 10 is not limited to the two LED units 11 and 12, and more LED units may be provided. For example, the LED module 10 may be configured by connecting three or more LED units 11, 12,. The LED units 11 and 12 are not limited to those having a plurality of LEDs, and may have one LED. For example, the LED module 10 may be composed of a plurality of LEDs connected one by one in parallel.

  The LED drive device 1 includes a DC / DC converter (an example of a drive circuit unit) 2, a dimming control unit 3, and a dimming signal generation circuit 4. The LED module 10 is connected to the DC / DC converter 2. The DC / DC converter 2 supplies drive power to the LED module 10 and performs a dimming operation as described later. The LED module 10 is driven when the output voltage Vo is applied from the DC / DC converter 2.

  The dimming control unit 3 is, for example, a microcomputer. A dimming instruction signal Sad is input to the dimming controller 3. The dimming control unit 3 generates and outputs an on-duty PWM signal Sp corresponding to the dimming instruction signal Sad. The dimming control unit 3 generates and outputs a control signal Sc for controlling the operation of the dimming signal generation circuit 4. The PWM signal Sp and the control signal Sc are input to the dimming signal generation circuit 4.

  Here, the control signal Sc is a signal for adjusting the DC voltage signal generated by the dimming signal generation circuit 4 as described later. For example, the dimming control unit 3 outputs the control signal Sc when the on-duty of the PWM signal Sp is a predetermined value or less. The timing for outputting the control signal Sc may be appropriately changed based on, for example, a user instruction.

  In the present embodiment, the dimming signal generation circuit 4 includes a signal conversion circuit 5 and a dimming signal adjustment circuit 6. The signal conversion circuit 5 and the dimming signal adjustment circuit 6 are connected to each other. A PWM signal Sp is input to the signal conversion circuit 5. A control signal Sc is input to the dimming signal adjustment circuit 6.

  The dimming signal generation circuit 4 converts the PWM signal Sp generated by the dimming control unit 3 into a DC voltage signal corresponding to the on-duty. Then, the DC voltage signal is output as a dimming signal Sd. The dimming signal Sd is input to the DC / DC converter 2.

  In the present embodiment, the dimming signal generation circuit 4 adjusts the magnitude of the DC voltage signal according to the control signal Sc when the control signal Sc is input from the dimming control unit 3. Then, the adjusted DC voltage signal is output to the DC / DC converter 2 as a dimming signal Sd.

  The LED drive device 1 is connected to a DC power source and operates by being supplied with a DC voltage Vdc and a drive voltage Vcc. The DC voltage Vdc is supplied to the DC / DC converter 2. The drive voltage Vcc is supplied to the DC / DC converter 2, the dimming signal generation circuit 4, and the like. The DC / DC converter 2, the dimming signal generation circuit 4 and the like are driven by being supplied with a driving voltage Vcc.

  FIG. 3 is a diagram illustrating an example of a circuit configuration of the DC / DC converter 2.

  In the present embodiment, a DC / DC converter 2 having a general circuit configuration can be used. That is, as shown in FIG. 3, the DC / DC converter 2 roughly includes a transformer Tr, a detection resistor Rf, an operational amplifier OP, a photocoupler PC, a control circuit IC1, and a switching element (FET (field effect transistor)) Qc. Etc.

  On the secondary side of the transformer Tr, a direct current that flows to the LED module (load) 10 flows to the resistor Rf. The current flowing through the LED module 10 is detected as a voltage value by the detection resistor Rf (detection signal Sf). The detection signal Sf is a terminal voltage of the resistor Rf and is a DC voltage. The detection signal Sf is input to the operational amplifier OP via a resistor or the like (detection signal Sfa).

  The operational amplifier OP receives the detection signal Sfa and the dimming signal Sd input from the dimming signal generation circuit 4. The operational amplifier OP compares the dimming signal Sd with the detection signal Sfa. The output waveform of the operational amplifier OP is a result of comparing the detection signal Sfa, which is the reference voltage, with the dimming signal Sd at high speed, and therefore has fluctuations.

  The operational amplifier OP outputs the comparison result (difference signal) to the control circuit IC1 via the photocoupler PC. Here, the transistors in the photocoupler PC do not simply repeat ON / OFF. That is, in the first case where the detection signal Sfa is larger than the dimming signal Sd (when Sfa> Sd), the current flowing through the photodiode in the photocoupler PC increases and the amount of light of the photodiode increases. Therefore, the current flowing through the transistor in the photocoupler PC increases. On the other hand, in the second case where the detection signal Sfa is smaller than the dimming signal Sd (when Sfa <Sd), the current flowing through the photodiode in the photocoupler PC decreases, and the light amount of the photodiode decreases. As a result, the current flowing through the transistor in the photocoupler PC decreases.

  The comparison result output from the operational amplifier OP is input to the control circuit IC1. Then, the control circuit IC1 performs on / off control of the switching element Qc according to the comparison result. Here, the control circuit IC1 changes the on-duty of the gate of the switching element Qc according to the amount of current flowing through the transistor in the photocoupler PC. Thereby, the electric current which flows into LED module 10 is adjusted.

  Specifically, when the voltage of the dimming signal Sd increases, the on-duty that becomes “H (high)” in the gate pulse waveform of the switching element Qc increases. If the voltage of the dimming signal Sd decreases, the on-duty becomes narrower. The current to the LED module 10 can be adjusted by the magnitude of the on-duty.

  FIG. 4 is a diagram illustrating an example of a circuit configuration of the dimming signal generation circuit 4.

  The signal conversion circuit 5 converts the input PWM signal Sp into a DC voltage signal and outputs a dimming signal Sd to the DC / DC converter 2. As shown in FIG. 4, the signal conversion circuit 5 receives the drive voltage Vcc and the PWM signal Sp. The signal conversion circuit 5 includes resistors R1 and R2, a capacitor C1, and a transistor Q1. The capacitor C1, the resistor R2, and the collector-emitter of the transistor Q1 are connected in parallel with each other, and are connected to the ground potential on the emitter side of the transistor Q1. The drive voltage Vcc is connected to the collector side of the transistor Q1 across the resistor R1. The PWM signal Sp is input to the base of the transistor Q1.

  The dimming signal adjustment circuit 6 adjusts the magnitude of the DC voltage signal of the signal conversion circuit 5 according to the control signal Sc input from the dimming control unit 3, and the dimming signal Sd output from the signal conversion circuit 5. Adjust the size of. In other words, the dimming signal adjustment circuit 6 controls the control signal Sc input from the dimming control unit 3 so that the dimming signal Sd having a magnitude corresponding to the dimming instruction signal Sad is output from the signal conversion circuit 5. To adjust the magnitude of the DC voltage signal.

  Here, the dimming signal adjustment circuit 6 includes two voltage dividing circuit portions 7a and 7b. The voltage dividing circuit portions 7a and 7b are connected in parallel to each other. In the present embodiment, two signals Sca and Scb are input as the control signal Sc. The control signal Sca is input to the voltage dividing circuit unit 7a. The control signal Scb is input to the voltage dividing circuit unit 7b. Each of the voltage dividing circuit units 7a and 7b operates in accordance with the control signals Sca and Scb.

  Each of the voltage dividing circuit sections 7a and 7b is configured as follows. That is, the voltage dividing circuit section 7a includes a resistor R3 and a transistor Q2 having a collector connected to the resistor R3. The emitter of the transistor Q2 is connected to the ground potential, and the control signal Sca is input to the base. The voltage dividing circuit section 7b includes a resistor R4 and a transistor Q3 having a collector connected to the resistor R4. The emitter of the transistor Q3 is connected to the ground potential, and the control signal Scb is input to the base. Of the terminals of the resistor R3 and the resistor R4, terminals on the opposite side to the side connected to the transistors Q2 and Q3 are connected. This terminal is connected to the signal conversion circuit 5. That is, the resistors R3 and R4 are connected between the resistor R1 and the collector of the transistor Q1. The dimming signal Sd is output from this line.

  FIG. 5 is a diagram illustrating an adjustment mode of the dimming signal adjustment circuit 6.

  The dimming signal adjustment circuit 6 controls the operation of the two voltage dividing circuit units 7a and 7b in accordance with the control signal Sc (control signals Sca and Scb) output from the dimming control unit 3 to thereby generate a DC voltage signal. The size of can be adjusted. The dimming signal adjustment circuit 6 operates in four adjustment modes according to the control signals Sca and Scb. That is, the dimming signal adjustment circuit 6 is turned on (operates) of the two voltage dividing circuit units 7a and 7b in accordance with the control signal Sc input to each of the two voltage dividing circuit units 7a and 7b. ) Can be adjusted to adjust the magnitude of the DC voltage signal.

  As adjustment modes (operation settings) by the dimming signal adjustment circuit 6, there are four settings “A”, “B”, “C”, and “D” shown in FIG. That is, the setting “A” is a case where both the voltage dividing circuit portions 7a and 7b are off (the transistors Q2 and Q3 are off). The setting “B” is a case where only the voltage dividing circuit unit 7a is off. The setting “C” is a case where only the voltage dividing circuit unit 7b is off. The setting “D” is a case where both the voltage dividing circuit portions 7a and 7b are on.

  In the case of setting “A” shown in FIG. 5, that is, when the dimming signal adjustment circuit 6 is not operating, the dimming signal Sd output from the signal conversion circuit 5 is a direct current obtained by integrating the PWM signal Sp. It becomes a voltage signal. The dimming signal SdA in this case is expressed by the following equation. Here, K is a variable coefficient whose value changes according to the on-duty of the PWM signal Sp (also affected by the capacitance value of the capacitor C1). As represented by the following equation, the dimming signal SdA is a DC voltage signal having a magnitude corresponding to the PWM signal Sp.

  SdA = K * Vcc * (R1 / (R1 + R2))

  When the dimming signal adjustment circuit 6 is operating, that is, in the case of the settings “B”, “C”, and “D” shown in FIG. 5, the dimming signal Sd output from the signal conversion circuit 5 is a voltage dividing circuit. It changes according to the combination of the operations of the units 7a and 7b.

  For example, when the setting “B” shown in FIG. 5, that is, only the voltage dividing circuit unit 7 b operates (when the control signal Scb is input), the dimming signal SdB output from the signal conversion circuit 5 is It becomes as follows. In the following equations, the symbol “‖” means (added value of left and right terms of the symbol) / (multiplied value of left and right terms of the symbol).

  SdB = K * Vcc * (R2‖R4) / (R1 + (R2‖R4))

  When only the setting “C” shown in FIG. 5, that is, the voltage dividing circuit unit 7a operates (when the control signal Sca is input), the dimming signal SdC output from the signal conversion circuit 5 is It becomes like this.

  SdC = K * Vcc * (R2‖R3) / (R1 + (R2‖R3))

  When the setting “D” shown in FIG. 5, that is, when both of the voltage dividing circuit sections 7 a and 7 b operate (when the control signals Sca and Scb are both input), the dimming output from the signal conversion circuit 5 The signal SdD is as follows.

  SdD = K * Vcc * (R2‖R3‖R4) / (R1 + (R2‖R3‖R4))

  As can be seen from the above formula, the dimming signals SdA to SdD can be set to desired sizes by setting the resistance elements R1, R2, R3, and R4 to appropriate values at the time of design.

  In this embodiment, since the DC voltage signal can be changed by the dimming signal adjustment circuit 6 in this way, the adjustable range of the luminous intensity of the LED module 10 can be widened in the LED driving device 1. Furthermore, the dimming control unit 3 can change the combination of the on-duty magnitude of the PWM signal Sp and the adjustment mode of the dimming signal adjustment circuit 6. Thereby, the dimming signal generation circuit 4 can change the magnitude of the DC voltage signal, thereby enabling dimming with a high degree of freedom of adjustment.

  FIG. 6 is a graph showing an example of the relationship between the light control signal Sd and the light intensity of the LED module 10 in a conventional lighting fixture. FIG. 7 is a graph showing a first example of the relationship between the dimming signal Sd and the luminous intensity of the LED module 10 in the present embodiment.

  As shown in FIG. 6, in the conventional LED driving device, as described above, there is a limit in reducing the on-duty of the PWM signal Sp, so the magnitude of the dimming signal Sd (sometimes referred to as dimming voltage). ) Can only be changed within a certain range (as an example, the range Vm to Vn shown in FIG. 6). Therefore, the luminous intensity of the LED module 10 can only be changed within a range corresponding to the dimming voltage (as an example, the range Im to In shown in FIG. 6). In other words, in the case shown in FIG. 6, the dimming voltage Vn is set at the on-duty adjustment limit value (minimum) of the PWM signal Sp, and the dimming voltage cannot be smaller than Vn. Therefore, In has a minimum value of In.

  On the other hand, in this Embodiment, the range which can adjust the luminous intensity of the LED module 10, ie, the light control range, can be widened. For example, FIG. 7 shows an operation example when the dimming signal adjustment circuit 6 is operated outside the on-duty adjustable range of the PWM signal Sp (low dimming range). That is, the adjustment mode of the voltage dividing circuit units 7a and 7b is set to “A” in FIG. 5 at the dimming voltage Vn or more, and the adjustment mode is set to “B”, “C”, “D” below the dimming voltage Vn. ", The change in luminous intensity is shown. In the present embodiment, it is assumed that the voltage dividing circuit unit 7a is configured to be smaller in the magnitude of the dimming signal Sd than the voltage dividing circuit unit 7b.

  As shown in FIG. 7, in the region of the dimming voltages Vm to Vn, the setting is “A” (the voltage dividing circuit units 7a and 7b are both turned off). As a result, the light intensity decreases in a range from Im to In according to a decrease in the on-duty of the PWM signal Sp (that is, a decrease in the dimming voltage).

  In the region of the dimming voltages Vn to V4, the setting is “B” (only the voltage dividing circuit unit 7b is turned on). Then, the dimming voltage changes instantaneously from Vn to the dimming voltage V5, and the luminous intensity decreases from In to I3. Thereafter, the light intensity becomes constant.

  In the region of the dimming voltages V4 to V2, the setting is “C” (only the voltage dividing circuit unit 7a is turned on). Then, the dimming voltage changes instantaneously from V4 to the dimming voltage V3, and the luminous intensity decreases from I3 to I2. Thereafter, the light intensity becomes constant.

  In the region of the dimming voltage V2-0, the setting is “D” (the voltage dividing circuit units 7a and 7b are both turned on). Then, the dimming voltage changes instantaneously from V2 to the dimming voltage V1, and the luminous intensity decreases from I2 to I1. Thereafter, the light intensity becomes constant.

  Thus, even in a region where the dimming voltage is low from Vn to 0, the luminous intensity can be changed stepwise. Therefore, the light control range can be widened.

  FIG. 8 is a graph showing a second example of the relationship between the dimming signal Sd and the luminous intensity of the LED module 10 in the present embodiment. FIG. 9 is a graph showing a third example of the relationship between the dimming signal Sd and the luminous intensity of the LED module 10 in the present embodiment. FIG. 10 is a graph showing a fourth example of the relationship between the dimming signal Sd and the luminous intensity of the LED module 10 in the present embodiment.

  8 to 10 show a case where the dimming signal adjustment circuit 6 is operated within the on-duty adjustable range of the PWM signal Sp or across the adjustable range. By operating the dimming signal adjustment circuit 6 in this manner, the dimming of the LED module 10 can be performed in various modes.

  In the example shown in FIG. 8, dimming is performed as follows. That is, in the region of the dimming voltages Vm to V11, the setting is “A”. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, as the dimming voltage decreases, the light intensity decreases in a range from Im to I9.

  In the region of the dimming voltages V11 to V9, the setting is “B”. Then, the dimming voltage changes instantaneously from V11 to the dimming voltage V8, and the light intensity decreases from I9 to I8. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, the light intensity decreases in the range from I8 to I7 in accordance with the decrease in the dimming voltage (V10 to V9).

  In the region of the dimming voltages V9 to V7, the setting is “C”. Then, the dimming voltage changes instantaneously from V9 to the dimming voltage V8, and the light intensity decreases from I7 to I6 smaller than In. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, the light intensity decreases in the range from I6 to I5 in accordance with the decrease in the dimming voltage (V8 to V7).

  In the region of the dimming voltage V7-0, the setting is “D”. Then, the dimming voltage changes instantaneously from V7 to the dimming voltage V6, and the light intensity decreases from I5 to I4. Here, the range of the dimming voltage from V6 to Vn is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, in this range, the light intensity decreases in the range from I4 to I1 in accordance with the decrease in the dimming voltage (V6 to Vn). When the dimming voltage reaches Vn, the dimming voltage is set to V1. And in the range of the dimming voltage V1-0, it becomes out of the adjustable range of the on-duty of the PWM signal Sp. At this time, the luminous intensity is constant at I1.

  In the example shown in FIG. 9, dimming is performed as follows. That is, in the region of the dimming voltages Vm to V13, the setting is “A”. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, as the dimming voltage decreases, the light intensity decreases in a range from Im to I11.

  In the region of the dimming voltages V13 to V0, the setting is “D”. Then, the dimming voltage changes instantaneously from V13 to the dimming voltage V12, and the luminous intensity is greatly reduced from I11 to I10 smaller than In. Here, the range of the dimming voltage from V12 to Vn is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, in this range, the luminous intensity decreases in the range from I10 to I1 in accordance with the decrease in the dimming voltage (V12 to Vn). When the dimming voltage reaches Vn, the dimming voltage is set to V1. In the range of the dimming voltage V1 to 0, the luminous intensity is constant at I1.

  In the example shown in FIG. 10, dimming is performed as follows. That is, in the region of the dimming voltages Vm to V18, the setting is “A”. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, as the dimming voltage decreases, the light intensity decreases in a range from Im to I15.

  In the region of the dimming voltages V18 to V16, the setting is “B”. Then, the dimming voltage is instantaneously changed from V18 to the dimming voltage V17, and the luminous intensity is decreased from I15 to I14. This range is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, the light intensity decreases in a range from I14 to I13 smaller than In according to the decrease in the dimming voltage (V17 to V16).

  In the region of the dimming voltages V16 to V14, the setting is “C”. Then, the dimming voltage changes instantaneously from V16 to the dimming voltage V15, and the luminous intensity decreases from I13 to I12. Here, the range of the dimming voltage from V15 to Vn is within the adjustable range of the on-duty of the PWM signal Sp. Therefore, in this range, the light intensity decreases in the range from I12 to I2 in accordance with the decrease in the dimming voltage (V15 to Vn). When the dimming voltage reaches Vn, the dimming voltage is set to V3. The range of the dimming voltages V3 to V14 is outside the adjustable range of the on-duty of the PWM signal Sp. At this time, the luminous intensity is constant at I2.

  In the region of the dimming voltage V14-0, the setting is “D”. Then, the dimming voltage changes instantaneously from V14 to the dimming voltage V1, and the luminous intensity decreases from I2 to I1. Thereafter, the light intensity remains constant at I1.

  As described above, in this embodiment, the LED module is obtained by both the on-duty adjustment of the PWM signal Sp and the combination of the adjustment of the dimming signal Sd of 2 bits (by the two voltage dividing circuit units 7a and 7b). 10 dimming controls can be performed. Thereby, the light control of the LED module 10 can be performed even in a range lower than the on-duty adjustable range of the PWM signal Sp. Further, the light intensity can be adjusted to an arbitrary light intensity according to the light adjustment voltage in the light intensity range (the range of In to I1 in FIGS. 7 to 10) lower than the light intensity In at the minimum value (limit value) of the conventional PWM signal Sp. , Can increase the degree of freedom of dimming. Accordingly, the lighting fixture 50 can be adjusted in a wide range according to the user's preference. Even within the on-duty adjustable range of the PWM signal Sp, by operating the adjustment signal adjustment circuit 6, it is possible to set the light intensity to a magnitude that cannot be adjusted by the signal conversion circuit 5 alone. Thereby, the freedom degree of a light control characteristic increases.

  [Second Embodiment]

  The second embodiment is different from the first embodiment in that two LED modules and two LED driving devices are used. Since the details of the configuration of the LED module and the LED driving device are roughly the same as those of the first embodiment, the description here may not be repeated.

  FIG. 11 is a block diagram illustrating a configuration of the lighting fixture 100 according to the second embodiment.

  As shown in FIG. 11, the lighting fixture 100 is adjusted to two LED modules 10a and 10b, two LED driving devices 1a and 1b that drive the respective LED modules 10a and 10b, and LED driving devices 1a and 1b. And a light control device 20 that outputs a light instruction signal Sad.

  The LED driving devices 1a and 1b share one dimming control unit 3a. That is, the LED drive device 1a includes a dimming control unit 3a, a dimming signal generation circuit 4a, and a DC / DC converter 2a. The LED drive device 1b includes a dimming control unit 3a, a dimming signal generation circuit 4b, and a DC / DC converter 2b. The LED drive device 1a supplies the output voltage Vo1 from the DC / DC converter 2a to the LED module 10a, and drives the LED module 10a. The LED driving device 1b supplies the output voltage Vo2 from the DC / DC converter 2b to the LED module 10b, and drives the LED module 10b.

  The dimming signal generation circuits 4a and 4b each have the same configuration as the dimming signal generation circuit 4 in the first embodiment. Further, each of the DC / DC converters 2a and 2b has the same configuration as the DC / DC converter 2 in the first embodiment.

  Based on the dimming instruction signal Sad, the dimming control unit 3a outputs the PWM signal Sp1 and the control signal Sc1 to the dimming signal generation circuit 4a, and outputs the PWM signal Sp2 and the control signal Sc2 to the dimming signal generation circuit 4b, respectively. To do. The dimming signal generation circuit 4a outputs the dimming signal Sd1 to the DC / DC converter 2a. The dimming signal generation circuit 4b outputs the dimming signal Sd2 to the DC / DC converter 2b.

  In the second embodiment, the color temperature of the LED module 10a is different from the color temperature of the LED module 10b. That is, the luminaire 100 can adjust the relative color temperature (toning) by adjusting each color temperature using two LED light sources having different color temperatures. For example, the color temperature of the LED included in the LED module 10a is 6,500K (Kelvin), and the color temperature of the LED included in the LED module 10b is 2,700K.

  FIG. 12 is a diagram showing the relationship between the color temperature and the illuminance of each LED module 10a, 10b in the lighting fixture 100. As shown in FIG.

  In the second embodiment, the LED drive devices 1a and 1b can reduce the dimming degree even when the PWM signals Sp1 and Sp2 are below the minimum adjustment limit value of the on-duty. Therefore, in the luminaire 100, when the illuminance of one LED module to be effective is lowered in the color temperature range of each single light source, the influence of the color temperature of the other LED module becomes smaller than before. Therefore, it is possible to adjust the relative color temperature as close as possible to the color temperature of the single light source, and as a result, it is possible to widen the color temperature adjustment range. As a result, more natural light adjustment and color adjustment are possible.

  As shown in FIG. 12, when only the LED module 10a is enabled and the illuminance is changed, the illuminance change curve with respect to the color temperature is changed from the conventional curve La0 (dashed line) to the curve La1 (solid line). it can. That is, at the minimum adjustment value (Min) of illuminance, the relative color temperature can be changed from X3 to X4 closer to 6500K. In other words, compared to the conventional case, the color temperature can be adjusted even in the color temperature range from X3 to X4 at the minimum adjustment value of illuminance.

  Similarly, when only the LED module 10b is enabled and the illuminance is changed, the illuminance change curve with respect to the color temperature can be changed from the conventional curve Lb0 (broken line) to the curve Lb1 (solid line). Therefore, the relative color temperature can be changed from X2 to X1 closer to 2700K at the minimum adjustment value of illuminance. That is, the color temperature can be adjusted even in the color temperature range from X2 to X1 at the minimum adjustment value of illuminance as compared with the conventional case.

  [Others]

  The configuration of the lighting fixture is not limited to the above-described embodiment. For example, various configurations such as a configuration in which a plurality of LED modules are driven by one LED driving device, a configuration in which each LED driving device has a dimming control unit individually, and a configuration in which three or more LED driving devices are provided. Can do.

  Each circuit of the LED driving device may be configured using circuit elements different from those of the above-described embodiment.

  The circuit configuration of the dimming signal generation circuit is not limited to the above embodiment. For example, the voltage dividing circuit unit included in the dimming signal adjustment circuit is not limited to two, and may be at least one or more.

  The relationship between the dimming signal and the luminous intensity of the LED module is not limited to the specific example shown in the above-mentioned figure. Various controls are possible by freely controlling the operating state of the voltage dividing circuit section. Further, more detailed adjustment is possible by increasing the number of voltage dividing circuit portions.

  The configuration of the LED module is not limited to that described above. The number of LEDs constituting the LED unit may be one or more, and the number of LED units connected in parallel may be one or more. For example, the number of LED modules may be more than three.

  In addition to the above-described DC / DC converter, dimming control unit, dimming signal generation circuit, and the like, the LED driving device may be provided with another circuit. In the LED drive device, the configuration of the drive circuit unit that outputs drive power to the LED module is not limited to the DC power supply and the DC / DC converter. For example, an AC power source and an AC / DC converter may be used.

  In addition, the LED driving device according to the present invention is not limited to that used in a lighting fixture that illuminates a space. For example, the LED driving device according to the present invention may be used in a lighting fixture used as a backlight of various devices. In addition, the present invention can be applied to various devices such as an instrument that irradiates a light beam for a specific purpose using an LED and an instrument that displays and transmits information by the light from the LED itself.

  The processing in the above embodiment may be performed by software or by using a hardware circuit.

  A program for executing the processing in the above-described embodiment can be provided, or the program can be recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card and provided to the user. It may be. The program may be downloaded to the apparatus via a communication line such as the Internet. The processing described in the text based on the above flowchart is executed by a CPU or the like according to the program.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1, 1a, 1b LED drive device 2, 2a, 2b DC / DC converter (an example of a drive circuit unit)
3, 3a Dimming control unit 4, 4a, 4b Dimming signal generation circuit 5 Signal conversion circuit 6 Dimming signal adjustment circuit 7a, 7b Voltage dividing circuit unit 10, 10a, 10b LED module 11, 12 LED unit 20 Dimming control Device 50, 100 Lighting fixture Sad Dimming instruction signal Sc, Sc1, Sc2 Control signal Sd, Sd1, Sd2 Dimming signal Sp, Sp1, Sp2 PWM signal

Claims (7)

An LED driving device that performs dimming operation of an LED (light emitting diode) module in response to a dimming instruction signal,
A drive circuit unit that outputs drive power to the LED module;
A dimming control unit that receives the dimming instruction signal and generates an on-duty PWM (pulse width modulation) signal corresponding to the dimming instruction signal;
A dimming signal generation circuit that converts the PWM signal generated by the dimming control unit into a DC voltage signal corresponding to the on-duty, and outputs the DC voltage signal to the driving circuit unit as a dimming signal; ,
The dimming control unit outputs a control signal for adjusting the DC voltage signal,
The dimming signal generation circuit adjusts the magnitude of the DC voltage signal according to the control signal when the control signal is input from the dimming control unit, and uses the adjusted DC voltage signal as a dimming signal. An LED driving device that outputs to the driving circuit unit. The dimming signal generation circuit includes:
A signal conversion circuit that converts the PWM signal into the DC voltage signal and outputs the dimming signal to the drive circuit unit;
A dimming signal adjustment circuit that adjusts the magnitude of the DC voltage signal according to a control signal input from the dimming control unit and adjusts the magnitude of the dimming signal output from the signal conversion circuit; The LED driving device according to claim 1, comprising:   The LED drive device according to claim 2, wherein the dimming control unit outputs the control signal to the dimming signal adjustment circuit when an on-duty of the PWM signal is a predetermined value or less. The dimming signal adjustment circuit operates in a plurality of adjustment modes according to the control signal,
The dimming control unit changes the combination of the on-duty magnitude of the PWM signal and the adjustment mode of the dimming signal adjustment circuit, so that the dimming signal generation circuit changes the magnitude of the DC voltage signal. The LED driving device according to claim 2 or 3.   The dimming signal adjustment circuit includes at least one voltage dividing circuit unit, and controls the operation of the at least one voltage dividing circuit unit according to a control signal output from the dimming control unit. The LED driving device according to claim 2, wherein the magnitude of the voltage signal is adjusted.   The dimming signal adjustment circuit includes a plurality of voltage dividing circuit units, and among the plurality of voltage dividing circuit units according to a control signal input from the dimming control unit to each of the plurality of voltage dividing circuit units 6. The LED driving device according to claim 2, wherein a magnitude of the DC voltage signal is adjusted by changing a combination of operating voltage dividing circuit units. 6. One or more LED modules each consisting of a single LED unit in which one or more LEDs are connected in series, or one or more LED modules in which a plurality of the LED units are connected in parallel;
The one or more LED driving devices according to any one of claims 1 to 6, wherein each of the one or more LED modules is driven.
A lighting fixture comprising: a dimming control device that outputs the dimming instruction signal to each of the one or more LED driving devices.

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