JP2015041430A - Lighting device and luminaire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which can light up a light-emitting element to a deep light control level and can smoothly change the brightness of the light-emitting element over a wide range, and a luminaire using the same.SOLUTION: A lighting device 1 comprises a first current adjustment part 123 for adjusting the current flowing in an LED 31 by turning on/off a transistor Q2 according to a PWM signal S3 in which the on-duty ratio changes in response to the light control signal S1 from outside; and a second current adjustment part 122 for adjusting the current flowing in the LED 31 by changing the voltage applied to a gate of the transistor Q2 according to the light control signal S1. When the light control level by the light control signal S1 is a predetermined value or more, the first current adjustment part 123 controls the brightness of the LED 31, and when the light control level is less than the predetermined value, a control state controlled by the first current adjustment part 123 when the light control level is the predetermined value, is kept and the brightness of the LED 31 is controlled by the second current adjustment part 122.

Description

  The present invention relates to a lighting device and a lighting fixture using the lighting device.

  Conventionally, a power supply assembly for supplying power to an LED (light emitting diode) module has been provided (see, for example, Patent Document 1). This power supply assembly includes a series circuit of a diode and a control switch connected between both ends of a DC power supply, and a controller that outputs a dual PWM signal to the control switch. Between the both ends of the diode, an inductor and an LED module are provided. A series circuit is connected.

  The controller has a pulse width modulator, and a current reference signal, a detection current, and a high-frequency sawtooth signal from a current source are input to the pulse width modulator. The pulse width modulator outputs a high frequency PWM signal to one input part of the AND gate, and a low frequency PWM signal is inputted to the other input part of the AND gate. The AND gate outputs a dual PWM signal obtained by combining the high-frequency PWM signal and the low-frequency PWM signal, and this dual PWM signal is input to the gate of the control switch via the amplifier.

  In this power supply assembly, the intensity of light output from the LED module can be changed by changing the low frequency component of the dual PWM signal output from the controller to the control switch.

JP 2006-511078 gazette

  By the way, since the light emitting diode has higher luminance than incandescent lamps and fluorescent lamps, when the light is emitted with the same luminous flux as incandescent lamps and fluorescent lamps, the user recognizes that the light emitting diodes are brighter than incandescent lamps and fluorescent lamps. Therefore, in order to make the apparent brightness the same as that of an incandescent lamp or a fluorescent lamp, it is necessary to suppress the driving current of the light emitting diode and reduce the luminous flux.

  For example, in the case of a lighting fixture including one or a plurality of light emitting diodes with a rated current of 350 mA, the lower limit value of the current needs to be set to several μA to several mA or less. However, in the so-called burst dimming method in which dimming is performed so that the load current intermittently flows in the LED module as in the power supply assembly described in Patent Document 1 described above, it is difficult to control the minute current as described above. there were.

  In addition, when the light emitting diode is faded in or faded out, it is necessary to control the driving current of the light emitting diode over a wide range from a minute current value to a rated current value in order to smoothly change the brightness of the light emitting diode. There is.

  For example, when the rated current of the light emitting diode is 350 mA, it is necessary to adjust the drive current in the range of 100 μA to 350 mA, and the drive current must be controlled with a resolution of about 1/1000. For this reason, in the power supply assembly shown in Patent Document 1 described above, it is difficult to smoothly change the brightness of the light emitting diode.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to light up the light emitting element to a deeper dimming level and to smoothly change the brightness of the light emitting element over a wide range. And a lighting apparatus using the same lighting device.

  The lighting device of the present invention includes a DC power supply unit, a series circuit of a light emitting element and a switch element connected between output terminals of the DC power supply unit, and a PWM whose on-duty ratio changes according to a dimming signal from the outside. A first current adjusting unit that adjusts a current flowing through the light emitting element by turning on and off the switch element according to a signal; and the light emission by changing a voltage applied to a control terminal of the switch element according to the dimming signal. A second current adjusting unit that adjusts a current flowing through the element, and controls the brightness of the light emitting element by the first current adjusting unit when a dimming level by the dimming signal is a predetermined value or more. When the dimming level is smaller than the predetermined value, the second current adjusting unit maintains the control state of the first current adjusting unit when the dimming level is the predetermined value. And controlling the more the brightness of the light emitting element.

  In this lighting device, it is preferable that the predetermined value is a dimming lower limit value of dimming control by the first current adjusting unit.

  In this lighting device, it is also preferable that the first current adjustment unit has a frequency modulation period at least one of a rising edge and a falling edge of a control signal output to the switch element.

  The lighting fixture of this invention is equipped with said lighting device, It is characterized by the above-mentioned.

  When the dimming level is equal to or higher than a predetermined value, dimming control is performed by the first current adjusting unit. When the dimming level becomes smaller than the predetermined value, the second current adjusting unit is added to the dimming control by the first current adjusting unit. The dimming control by is performed together. As a result, the light-emitting element can be turned on to a deeper dimming level, and the brightness of the light-emitting element can be smoothly changed over a wide range.

2 is a circuit diagram illustrating an example of a lighting device according to Embodiment 1. FIG. It is a graph which shows the relationship between the gate voltage and load current in the same as the above. (A)-(c) is explanatory drawing explaining operation | movement same as the above. (A)-(d) is a partial circuit diagram of the direct-current power supply part used for the same as the above. (A)-(c) is explanatory drawing explaining operation | movement of the lighting device of Embodiment 2. FIG. It is sectional drawing which shows the construction state of the lighting fixture using the lighting device of Embodiment 1 or 2.

  Embodiments of a lighting device and a lighting fixture using the lighting device will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a circuit diagram illustrating an example of a lighting device 1 according to the present embodiment. The lighting device 1 includes a DC power supply unit 11, a current adjustment unit 12, and a dimming control unit 13, and includes a dimmer 2. The light emitting unit 3 is turned on at a dimming level corresponding to the dimming signal S1 output from the.

  The light emitting unit 3 includes a plurality (four in FIG. 1) of LEDs 31 (light emitting elements) connected in series, and is connected between the output terminals of the DC power supply unit 11 via a transistor Q2 (switching element) and a resistor R1. ing. Note that the number of the LEDs 31 constituting the light emitting unit 3 may be one, or may be two, three, or a plurality of five or more. Moreover, you may comprise the light emission part 3 by connecting several LED31 in parallel.

  The DC power supply unit 11 has a so-called diode bridge DB1 constituted by four diodes, and a smoothing capacitor C1 is connected between the output terminals of the diode bridge DB1. A series circuit of a primary winding n1 of the transformer Tr1 and a transistor Q1 is connected between the output terminals of the diode bridge DB1. A diode D1 is connected to one end of the secondary winding n2 of the transformer Tr1, and a smoothing capacitor C2 is connected between both ends of the secondary winding n2.

  Here, in this embodiment, an N-channel MOSFET is used as the transistor Q1, and the drive circuit 111 is connected to the gate of the transistor Q1. The transistor Q1 is controlled to be turned on / off by a PWM signal output from the drive circuit 111. In the DC power supply unit 11, a DC voltage generated between both ends of the smoothing capacitor C <b> 2 becomes an output voltage of the DC power supply unit 11.

  The current adjustment unit 12 includes a first current adjustment unit 123, a second current adjustment unit 122, a transistor Q2, and a resistor R1. The first current adjustment unit 123 includes a so-called totem pole output circuit configured by connecting a transistor Q3 made of a P-channel MOSFET and a transistor Q4 made of an N-channel MOSFET in series.

  The source of the transistor Q3 is connected to the output terminal of the operational amplifier 122b of the second current adjustment unit 122, and the source of the transistor Q4 is connected to the negative electrode of the DC voltage source 122a of the second current adjustment unit 122. The gates of the transistors Q3 and Q4 are connected to the dimming control unit 13, and the on / off state is controlled by the PWM signal S3 output from the dimming control unit 13. Further, the connection point between the transistor Q3 and the transistor Q4 is connected to the gate (control terminal) of the transistor Q2.

  The second current adjustment unit 122 includes a DC voltage source 122a whose output voltage varies according to the control signal S2 output from the dimming control unit 13, and the positive electrode of the DC voltage source 122a is a non-inverting input terminal of the operational amplifier 122b. It is connected to the. Further, the negative electrode of the DC voltage source 122 a is connected to the negative electrode of the DC power supply unit 11. Further, the connection point between the transistor Q2 and the resistor R1 is connected to the inverting input terminal of the operational amplifier 122b.

  Here, in the present embodiment, an N-channel MOSFET is used as the transistor Q2, and the output terminal of the first current adjusting unit 123 (the connection point between the transistors Q3 and Q4) is connected to the gate of the transistor Q2. The impedance of the transistor Q <b> 2 changes according to the magnitude of the voltage output from the first current adjustment unit 123, and thereby the magnitude of the current flowing through the light emitting unit 3 can be adjusted.

  When the dimming signal S1 from the dimmer 2 is input, the dimming control unit 13 generates a control signal S2 and a PWM signal S3 corresponding to the dimming signal S1, and uses the control signal S2 as the second current. While outputting to the adjustment part 122, PWM signal S3 is output to the 1st electric current adjustment part 123. FIG. Here, the dimming signal S1 is a signal indicating the magnitude of the load current to be passed through the light emitting unit 3, that is, the brightness of the light emitting unit 3.

  Next, the operation of the lighting device 1 will be described with reference to FIGS.

  FIG. 2 is a graph showing the relationship between the gate voltage v1 of the transistor Q2 constituting the current adjusting unit 12 and the load current i1 flowing through the light emitting unit 3. According to this graph, the gate voltage v1 is a constant value when the load current i1 is greater than or equal to i12, and the gate voltage v1 decreases as the load current i1 decreases when the load current i1 is smaller than i12.

  3A and 3B show the gate signal S4 to the transistor Q2 when the dimming control is performed by the first current adjusting unit 123. FIG. When the load current i1 = i11, as shown in FIG. 3A, the on-duty ratio (t1 / T1) of the gate signal S4 is large, and when the load current i1 = i12 (<i11), FIG. ), The on-duty ratio of the gate signal S4 becomes small. As described above, the brightness of the light emitting unit 3 can be changed by changing the on-duty ratio of the gate signal S4 according to the magnitude of the load current i1.

  FIG. 3C shows a gate signal S4 to the transistor Q2 when the dimming control is performed by the second current adjusting unit 122. In this case, by changing the magnitude (amplitude vm) of the gate voltage v1 of the transistor Q2 in accordance with the control signal S2, the magnitude of the load current i1 flowing through the light emitting unit 3 changes, and as a result, the brightness of the light emitting unit 3 is increased. Can be changed.

  When the dimming level of the dimming signal S1 output from the dimmer 2 indicates full lighting, the output voltage of the DC power supply unit 11 is set to the rated voltage of the light emitting unit 3, and the load current i1 flowing through the light emitting unit 3 is i11. As a result, the light emitting unit 3 is fully lit.

  From this state, when the user operates the dimmer 2 so that the light emitting unit 3 becomes dark, the dimming level of the dimming signal S1 output from the dimmer 2 also decreases. When the dimming signal S <b> 1 from the dimmer 2 is input, the dimming control unit 13 generates a PWM signal S <b> 3 that decreases the on-duty ratio of the transistor Q <b> 2 and outputs the PWM signal S <b> 3 to the first current adjustment unit 123. In the range where the load current i1 is greater than or equal to i12 and smaller than i11, the control signal S2 output to the second current adjustment unit 122 is set to the same value as when all the lights are on.

  When the PWM signal S3 from the dimming control unit 13 is input, the first current adjustment unit 123 turns on / off the transistors Q3 and Q4 according to the PWM signal S3. As a result, the on-duty ratio of the transistor Q2 is reduced, and the load current i1 flowing through the light emitting unit 3 is also reduced. The above-described operation is performed in a range where the load current i1 is i12 or more and smaller than i11.

  Next, when the user operates the dimmer 2 so that the light emitting unit 3 becomes darker, the dimming level of the dimming signal S1 output from the dimmer 2 is further reduced. When the dimming signal S1 from the dimmer 2 is input, the dimming control unit 13 outputs the PWM signal S3 to the first current adjusting unit 123. In this case, the PWM signal in which the load current i1 is i12. S3 is output. Further, the dimming control unit 13 generates a control signal S2 that decreases the gate voltage v1 of the transistor Q2, and outputs the control signal S2 to the second current adjustment unit 122.

  When the control signal S2 from the dimming control unit 13 is input, the second current adjustment unit 122 adjusts the output voltage of the DC voltage source 122a so that the gate voltage v1 according to the control signal S2 is obtained. Thereby, the load current i1 flowing through the light emitting unit 3 is reduced, and the brightness of the light emitting unit 3 is lowered. Here, in the present embodiment, the dimming level when the load current i1 = i12 is a predetermined value, and the predetermined value is a dimming lower limit value of dimming control by the first current adjusting unit 123.

  As described above, when the dimming level is equal to or higher than the predetermined value, the dimming control is performed by the first current adjusting unit 123, and when the dimming level becomes smaller than the predetermined value, the dimming control by the first current adjusting unit 123 is performed. In addition, dimming control by the second current adjusting unit 122 is performed together. As a result, the LED 31 can be lit up to a deeper dimming level, and the brightness of the LED 31 can be smoothly changed over a wide range.

  In the present embodiment, the output voltage of the diode bridge DB1 is stepped down by the flyback converter using the transformer Tr1 and applied to the light emitting unit 3. However, the step-up chopper shown in FIG. 4A is used instead of the flyback converter. The circuit 112 may be used.

  Further, instead of the flyback converter, a step-up / step-down chopper circuit 113 shown in FIG. 4B, a step-down chopper circuit 114 shown in FIG. 4C, a forward converter circuit 115 shown in FIG. Good. In any case, the same effect can be obtained by providing the current adjusting unit 12 between the light emitting unit 3.

  In the present embodiment, the case where the light emitting element is an LED has been described as an example. However, the light emitting element is not limited to the LED, and may be, for example, an organic EL element or a laser diode (LD).

  The lighting device 1 includes a DC power supply unit 11, a series circuit of an LED 31 and a transistor Q2 connected between output terminals of the DC power supply unit 11, a first current adjustment unit 123, and a second current adjustment unit 122. The first current adjusting unit 123 adjusts the current flowing through the LED 31 by turning on / off the transistor Q2 according to the PWM signal S3 whose on-duty ratio changes according to the dimming signal S1 from the outside. The second current adjustment unit 122 adjusts the current flowing through the LED 31 by changing the voltage applied to the gate of the transistor Q2 in accordance with the dimming signal S1. When the dimming level by the dimming signal S1 is equal to or higher than a predetermined value, the brightness of the LED 31 is controlled by the first current adjusting unit 123. When the dimming level is smaller than the predetermined value, the brightness of the LED 31 is controlled by the second current adjusting unit 122 while maintaining the control state of the first current adjusting unit 123 when the dimming level is the predetermined value.

  Moreover, it is preferable that the predetermined value is a dimming lower limit value of dimming control by the first current adjusting unit 123.

(Embodiment 2)
Embodiment 2 of the lighting device 1 will be described with reference to FIG. Since the circuit configuration of the lighting device 1 is the same as that of the first embodiment, the description is omitted here, and FIG. 1 is referred to when necessary.

  As shown in FIG. 1, the lighting device 1 of the present embodiment includes a DC power supply unit 11, a current adjustment unit 12, and a dimming control unit 13, and generates a dimming signal S <b> 1 output from the dimmer 2. The light emitting unit 3 is turned on at a corresponding dimming level.

  FIGS. 5A and 5B show the gate signal S4 to the transistor Q2 when the dimming control is performed by the first current adjusting unit 123, and FIG. 5C shows the second current adjusting unit 122. This is the gate signal S4 to the transistor Q2 when the dimming control is performed. Then, by turning on / off the transistor Q2 by these gate signals S4, the waveform of the load current i1 flowing through the light emitting unit 3 becomes rectangular.

  When the waveform of the load current i1 is rectangular, noise may occur when the load current i1 rises or falls, and this noise becomes a problem depending on the application. Therefore, in the present embodiment, in order to suppress the noise, a period T2 for frequency modulation is provided at the time of rising of the gate signal S4 (control signal) (see FIGS. 5A to 5C).

  The frequency of the gate signal S4 in the period T2 is set higher than that of the normal gate signal S4 for turning on / off the transistor Q2, thereby suppressing the peak value of noise generated at the rise of the gate signal S4. Can do.

  Also in the present embodiment, when the dimming level is equal to or higher than the predetermined value, the dimming control is performed by the first current adjusting unit 123, and when the dimming level becomes smaller than the predetermined value, the dimming control by the first current adjusting unit 123 is performed. In addition, the dimming control by the second current adjusting unit 122 is performed together. As a result, the LED 31 can be lit up to a deeper dimming level, and the brightness of the LED 31 can be smoothly changed over a wide range.

  Also in this embodiment, instead of the flyback converter using the transformer Tr1, the one shown in FIGS. 4A to 4D may be used. The same effect can be obtained by providing the current adjusting unit 12 in the circuit. Also in the present embodiment, the light emitting element is not limited to the LED, and may be, for example, an organic EL element or a laser diode (LD).

  Further, in the present embodiment, the period T2 is provided when the gate signal S4 rises. However, the period T2 may be provided at least one of the rise time and the fall time of the gate signal S4, and the present invention is not limited to this embodiment.

  The lighting device 1 includes a DC power supply unit 11, a series circuit of an LED 31 and a transistor Q2 connected between output terminals of the DC power supply unit 11, a first current adjustment unit 123, and a second current adjustment unit 122. The first current adjusting unit 123 adjusts the current flowing through the LED 31 by turning on / off the transistor Q2 according to the PWM signal S3 whose on-duty ratio changes according to the dimming signal S1 from the outside. The second current adjustment unit 122 adjusts the current flowing through the LED 31 by changing the voltage applied to the gate of the transistor Q2 in accordance with the dimming signal S1. When the dimming level by the dimming signal S1 is equal to or higher than a predetermined value, the brightness of the LED 31 is controlled by the first current adjusting unit 123. When the dimming level is smaller than the predetermined value, the brightness of the LED 31 is controlled by the second current adjusting unit 122 while maintaining the control state of the first current adjusting unit 123 when the dimming level is the predetermined value.

  Further, it is preferable that the first current adjusting unit 123 has a frequency modulation period at least at the time of rising or falling of the control signal output to the transistor Q2.

(Embodiment 3)
An embodiment of the lighting fixture A will be described with reference to FIG. FIG. 6 is a cross-sectional view illustrating a construction state of the lighting fixture A of the present embodiment. The lighting fixture A includes the lighting device 1, the light emitting unit 3, and the fixture main body 4 described in the first or second embodiment. Is provided. The lighting device 1 is connected to the dimmer 2 by wire, and turns on the light emitting unit 3 at the dimming level of the dimming signal S1 output from the dimmer 2.

  The instrument body 4 is, for example, an aluminum die-cast product, and is formed in a bottomed cylindrical shape with one surface (the lower surface in FIG. 6) opened, and is embedded in the ceiling through an embedding hole 100a provided in the ceiling material 100. Established. A substrate 32 on which a plurality of (three in FIG. 6) LEDs 31 are mounted is accommodated in the cylinder of the instrument body 4, and light that diffuses light from the LEDs 31 is formed at the opening edge of the instrument body 4. A diffusion plate 33 is attached. Here, in the present embodiment, the light emitting unit 3 is configured by the substrate 32 on which the LEDs 31 are mounted and the light diffusion plate 33.

  In the lighting fixture A of the present embodiment, as shown in FIG. 6, the fixture body 4 that houses the light emitting unit 3 and the lighting device 1 are arranged with a space therebetween, and the space between the light emitting unit 3 and the lighting device 1 is between. The power line 5 is electrically connected via the connector 6. As described above, when the lighting device 1 is separated from the fixture body 4, it is only necessary to store the light emitting unit 3 inside the fixture body 4, so that the height dimension of the fixture body 4 can be reduced. In addition, there is an advantage that the degree of freedom of installation of the lighting device 1 is improved.

  As described above, by using the lighting device 1 described in the first or second embodiment, the light emitting unit 3 can be lit to a deeper dimming level, and the brightness of the light emitting unit 3 can be smoothly changed over a wide range. Luminaire A can be provided.

  In the present embodiment, the lighting device 1 is provided separately from the fixture body 4, but the lighting device 1 may be provided integrally with the fixture body 4. Further, although the wired dimmer 2 is used in the present embodiment, a wireless dimmer using infrared rays, radio waves, or the like may be used, and is not limited to the present embodiment.

  The lighting fixture A includes a lighting device 1.

1 lighting device 31 LED (light emitting element)
122 2nd current adjustment part 123 1st current adjustment part Q2 Transistor (switch element)
S1 Dimming signal S3 PWM signal

Claims (4)

A DC power supply,
A series circuit of a light emitting element and a switch element connected between the output ends of the DC power supply unit;
A first current adjusting unit that adjusts a current flowing through the light emitting element by turning on / off the switch element according to a PWM signal whose on-duty ratio changes according to a dimming signal from the outside;
A second current adjusting unit that adjusts a current flowing through the light emitting element by changing a voltage applied to a control terminal of the switch element according to the dimming signal;
When the dimming level by the dimming signal is a predetermined value or more, the brightness of the light emitting element is controlled by the first current adjustment unit,
When the dimming level is smaller than the predetermined value, the second current adjusting unit maintains the control state of the first current adjusting unit when the dimming level is the predetermined value. A lighting device characterized by controlling brightness.   The lighting device according to claim 1, wherein the predetermined value is a dimming lower limit value of dimming control by the first current adjusting unit.   3. The lighting according to claim 1, wherein the first current adjusting unit has a frequency modulation period at least one of a rising edge and a falling edge of a control signal output to the switch element. apparatus.   A lighting fixture comprising the lighting device according to any one of claims 1 to 3.

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