JP5904455B2 - Lighting power supply and lighting device - Google Patents

Description

  Embodiments described herein relate generally to a lighting power source and a lighting device.

  2. Description of the Related Art In recent years, in illumination devices, replacement of incandescent bulbs and fluorescent lamps with light-saving, long-life light sources such as light-emitting diodes (LEDs) has been progressing. In addition, new illumination light sources such as EL (Electro-Luminescence) and organic light-emitting diode (OLED) have been developed. Since the light output of these illumination light sources depends on the value of the flowing current, a power supply circuit that supplies a constant current is required when lighting the illumination. In addition, when dimming, the supplied current is controlled. Also, switching power supplies such as DC-DC converters are known as power supplies that are highly efficient and suitable for power saving and miniaturization.

JP2011-119237A

  It is an object of the present invention to provide a lighting power source and a lighting device with a wide output current variable range.

The illumination power supply according to the embodiment includes an output element. The output element is connected between a power source and a lighting load, and is configured to be switchable between a switching operation that repeats an on state and an off state and an on-continuation operation that continues the on state. When the output to the lighting load is equal to or lower than the first output, the output element is switched to the on-continuation operation, and when the output to the lighting load is equal to or higher than the second output that is larger than the first output, Switching the output element to the switching operation, and when the output to the lighting load is larger than the first output and smaller than the second output, the output element is switched to the on-continuation operation for the first period, In the second period, the switching operation is performed.

  According to the embodiment of the present invention, it is possible to provide a lighting power source and a lighting device that have a wide variable range of output current.

It is a block diagram which illustrates the illuminating device containing the power supply for illumination which concerns on 1st Embodiment. FIG. 5 is a characteristic diagram illustrating the relationship between an output voltage VOUT supplied to a lighting load and an output current IOUT. It is a wave form diagram which illustrates the current waveform of an output element. It is a wave form diagram which illustrates the current waveform of the output element in a 2nd embodiment. It is a circuit diagram which illustrates direct-current power supply containing a dimmer.

  Hereinafter, embodiments will be described in detail with reference to the drawings. Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram illustrating a lighting device including a lighting power source according to the first embodiment.
As illustrated in FIG. 1, the lighting device 1 includes a lighting load 2 and a lighting power source 3 that supplies power to the lighting load 2.

  The illumination load 2 includes an illumination light source 4 such as an LED, for example. The illumination load 2 is supplied with output power POUT (output voltage VOUT, output current IOUT) from the illumination power source 3 and lights up. The lighting load 2 can be dimmed by changing the output power POUT. For example, dimming can be performed by changing at least one of the output voltage VOUT and the output current IOUT. Each value of the output power POUT, the output voltage VOUT, and the output current IOUT is defined according to the illumination light source 4.

FIG. 2 is a characteristic diagram illustrating the relationship between the output voltage VOUT supplied to the lighting load and the output current IOUT.
In FIG. 2, the characteristic of the illumination load which has an illumination light source with small operation resistance at the time of lighting, such as LED, is illustrated.
When the output voltage VOUT is lower than the predetermined voltage, the illumination load 2 is not lit and is turned off. When the output voltage VOUT is equal to or higher than a predetermined voltage, a current flows and lights up.

  For example, when the illumination light source 4 is an LED, the predetermined voltage is a forward voltage of the LED and is determined according to the illumination light source 4. In addition, the illumination light source 4 has a low operating resistance when lit, and the output voltage VOUT hardly changes even if the output current IOUT increases near the rated operating point P, for example. Therefore, the illumination load 2 having the characteristics as shown in FIG. 2 can control light by controlling the light output of the illumination light source 4 by changing the output current IOUT. Further, when the output voltage VOUT is lower than the predetermined voltage, the illumination light source 4 is turned off and the output current IOUT does not flow. For example, when the output voltage VOUT is output after being smoothed by a capacitor, the value of the output voltage VOUT is held above the predetermined voltage. The

Further, for example, by changing the output voltage VOUT supplied to the illumination light source 4, the light output of the illumination light source 4 can be controlled and dimmed.
Thus, by changing the output power POUT supplied to the illumination load 2, the light output of the illumination light source 4 can be controlled and dimmed. In the following description, changing the output means changing at least one of the output voltage VOUT, the output current IOUT, and the output power POUT.

  The illumination power source 3 includes an output element 5, a constant current element 6, a first drive circuit 70 that drives the output element 5, a second drive circuit 71 that drives the constant current element 6, and first and first A control circuit 72 for controlling the output element 5 and the constant current element 6 via two drive circuits 70 and 71, and an interface circuit 73. The illumination power supply 3 converts the input power PIN input to the input terminals 74 and 75 and outputs it as output power POUT between the high potential output terminal 30 and the low potential output terminal 31.

  The output element 5 is connected between the illumination load 2 and the power source 7. The output element 5 is configured to be switchable between a switching operation that repeats an on state and an off state and an on-continuation operation that continues the on state.

  FIG. 3 is a waveform diagram illustrating the current waveform of the output element, where (a) is an on-continuation operation, (b) and (c) are operations that continuously vibrate, and (d) is a switching operation. This is the case. In FIG. 3, the horizontal axis represents time t, and the waveform of the current I5 of the output element 5 is represented.

  As shown in FIG. 3A, in the on-continuation operation of the output element 5, a substantially constant DC current limited by the constant current element 6 flows through the output element 5. In a state where the output element 5 outputs a constant direct current, the illumination power supply 3 operates like a series regulator.

  As shown in FIGS. 3B and 3C, in the operation in which the current oscillates while the on-state is continued, the output element 5 is in an incompletely oscillating state, for example. However, in this operation, the output element 5 is not turned off but continues to be turned on. The peak value of the oscillating current of the output element 5 is a value limited by the constant current value of the constant current element 6. Further, the vibration period T of the output element 5 changes according to the fluctuation range of the current. FIG. 3C illustrates a case where the fluctuation range of the current I5 of the output element 5 is larger than that in the case of FIG.

  As shown in FIG. 3D, in the switching operation of the output element 5, the output element 5 oscillates. At this time, the illumination power supply 3 operates as a switching power supply.

  The constant current element 6 is connected in series to the output element 5 and limits the peak value of the current I5 of the output element 5. The output element 5 and the constant current element 6 are, for example, field effect transistors (FETs), for example, high electron mobility transistors (HEMTs).

  The first drive circuit 70 drives the output element 5. For example, the first drive circuit 70 controls the potential of the control terminal of the output element 5 to switch the operation of the output element 5. The second drive circuit 71 drives the constant current element 6. The second drive circuit 71 controls the constant current value by controlling the potential of the control terminal of the constant current element 6, for example.

  The control circuit 72 controls the output element 5 via the first drive circuit 70 and controls the constant current element 6 via the second drive circuit 71. The control circuit 72 controls the driving conditions of the output element 5 and the constant current element 6 to switch the output element 5 to the switching operation or the on-continuation operation, and also controls the current value of the output element 5.

  When the control circuit 72 receives a control signal for relatively increasing the output to the lighting load 2, the control circuit 72 controls the constant current element 6 to increase the constant current value of the constant current element 6, and the output element 5. Is controlled to switch the output element 5. When the control circuit 72 receives a control signal for relatively reducing the output to the lighting load 2, the control circuit 72 controls the constant current element 6 to reduce the constant current value of the constant current element 6 and the output element 5. And the output element 5 is kept on.

  The interface circuit 73 inputs a dimming signal for controlling the light output of the lighting load 2 and outputs it to the control circuit 72 as a control signal for controlling the output power POUT. The dimming signal is, for example, a phase control signal, a PWM dimming signal, a DALI (Digital Addressable Lighting Interface) signal, a wireless or wired communication signal such as a LAN, and an output signal of a sensor.

  When the dimming signal is, for example, a phase control signal, the interface circuit 73 detects, for example, the conduction period and the cutoff period of the dimmer 8 by comparing the AC voltage phase-controlled by the dimmer 8 with a predetermined value. A control signal can be generated.

  When the dimming signal is, for example, a PWM signal, the interface circuit 73 can generate a control signal based on, for example, a duty ratio.

  When the dimming signal is, for example, a DALI signal, the interface circuit 73 has, for example, a microcomputer, for example, a logic circuit, decodes the DALI signal, and outputs it as a control signal.

  When the dimming signal is, for example, a wireless or wired communication signal, the interface circuit 73 includes, for example, a receiving circuit that demodulates the communication signal, a microcomputer that decodes the demodulated signal, and outputs the control signal as a control signal. be able to.

  When the dimming signal is, for example, an output signal of a sensor, the interface circuit 73 can include, for example, a receiving element that receives the output signal of the sensor and an analysis circuit that analyzes the signal received by the receiving element. The sensor is provided outside the illumination power supply 3. The sensor may include, for example, a far infrared sensor, a near infrared sensor, an ultrasonic sensor, a proximity sensor, an acceleration sensor, a gravity sensor, a sound sensor (sound pressure sensor), a color sensor (wavelength sensor), and the like. .

  Further, the interface circuit 73 may generate the control signal based on the input power PIN or the input power PIN and the output power POUT without using the dimming signal input from the outside. For example, the output power POUT can be controlled in accordance with a change in the input power PIN supplied from the power supply 7 to the illumination power supply 3. For example, in a power source obtained by rectifying an AC power source that is phase-controlled by the dimmer 8, the input power PIN can be changed by the dimmer 8. Further, the output can be controlled in accordance with the change in the power supply voltage VIN of the power supply 7.

  In this case, when the power difference between the input power PIN or the input power PIN and the output power POUT is relatively large, the interface circuit 73 generates a control signal that relatively increases the output to the lighting load 2 as a control signal. Generate. Further, the interface circuit 73 generates a control signal for relatively reducing the output to the lighting load 2 when the power difference between the input power PIN or the input power PIN and the output power POUT is relatively small.

  The power source 7 only needs to be able to supply direct current, and is, for example, a battery, a power source composed of solar power generation and a secondary battery, a USB power source, a LAN power source, or the like. is there. The power source obtained by rectifying the AC power source is, for example, a full-wave rectified power source, for example, a power source smoothed by a smoothing capacitor.

FIG. 4 is a circuit diagram illustrating a DC power supply including a dimmer.
As shown in FIG. 4, the power source 7 includes a dimmer 8, a rectifier circuit 9, and a smoothing capacitor 40.
The dimmer 8 is a two-wire phase control dimmer. The dimmer 8 is connected to the AC power source 76 and is inserted in series into one of the pair of power supply lines. Thus, the dimmer 8 may be inserted in series with a pair of power supply lines.

  The dimmer 8 includes a triac 12 inserted in series in the power supply line, a phase circuit 13 connected in parallel with the triac 12, and a diac 14 connected between the gate of the triac 12 and the phase circuit 13. Have.

The triac 12 is normally in an off state, and is turned on when a pulse signal is input to the gate. The triac 12 can pass a current in both directions when the AC power supply voltage VIN is positive and negative.
The phase circuit 13 includes a variable resistor 15 and a capacitor 16, and generates a voltage whose phase is delayed at both ends of the capacitor 16. Further, when the resistance value of the variable resistor 15 is changed, the time constant changes and the delay time changes.

The diac 14 generates a pulse voltage when the voltage charged in the capacitor of the phase circuit 13 exceeds a certain value, and turns on the triac 12.
The dimmer 8 can adjust the timing at which the triac 12 is turned on by changing the time constant of the phase circuit 13 and controlling the timing at which the diac 14 generates a pulse.

  The rectifier circuit 9 inputs an AC power supply voltage via the dimmer 8 and outputs a DC voltage. The rectifier circuit 9 is configured by a diode bridge. The rectifier circuit 9 outputs a DC voltage whose voltage changes according to the dimming degree by the dimmer 8. The rectifier circuit 9 only needs to rectify the AC voltage input from the dimmer 8 and may have another configuration. Further, a capacitor for reducing noise generated in the illumination power supply 3 is connected to the input side of the rectifier circuit 9.

The smoothing capacitor 40 is connected between the high potential terminal 9a and the low potential terminal 9b of the rectifier circuit 9. The smoothing capacitor 40 smoothes the DC voltage rectified by the rectifier circuit 9.
In the illumination power supply 3, a configuration in which a DC power supply is connected is illustrated as the power supply 7, but the rectification circuit 9 and the smoothing capacitor 40 are included in the illumination power supply 3, and the illumination power supply 3 is AC. A configuration may be adopted in which power is supplied from the power source 76.

The switching power supply is a power supply with low power consumption and high efficiency because the output element 5 performs a switching operation that repeats an ON state with low resistance and an OFF state in which no current flows.
In this embodiment, when the output power POUT is larger than a predetermined value, the switching operation is performed, and when the output power POUT is small, the operation is performed like a series regulator. When the output power POUT is large, the product of the potential difference ΔV between the input and output and the current is large, and the loss increases when the series regulator is operated. Therefore, when the output power POUT is large, the switching operation is suitable for low power consumption. Further, when the output power POUT is small, the loss is small, and there is no problem in operating as a series regulator.

  In the present embodiment, when the output power POUT is smaller than a predetermined value, the output element 5 does not turn off, the current vibrates while continuing the on state, and illumination is performed with the average value of the current. The load 2 is turned on (FIGS. 3B and 3C). Further, when the output power POUT is further small, the output element 5 outputs a direct current to the lighting load 2 and keeps the light on while keeping the ON state (FIG. 3A). As a result, in the present embodiment, the output current can be continuously changed to zero. Moreover, the illumination load 2 in the illumination device 1 can be turned off smoothly.

  Therefore, in the present embodiment, the output power from the maximum value at the time of the switching operation of the output element 5 to the minimum value at the time of outputting the direct current while the output element 5 is kept on according to the output power POUT. POUT can be continuously changed. Moreover, the illumination load 2 in the illuminating device 1 can be dimmed continuously in the range of 0 to 100%.

  In FIGS. 3B and 3C, the output element 5 oscillates while the ON state is maintained without being turned off, and the fluctuation range of the current increases as the output power POUT increases. The operation | movement which becomes is illustrated. However, the output element 5 oscillates by performing a switching operation that repeats an ON state and an OFF state when the output power POUT is equal to or higher than a predetermined value (FIG. 3D), and the output power POUT is smaller than the predetermined value. In some cases, an operation may be performed in which a direct current is output while the on state is continued (FIG. 3A). That is, the output element 5 does not have to perform an operation (FIGS. 3B and 3C) in which the current oscillates while continuing the ON state without being in the OFF state.

(Second Embodiment)
FIG. 5 is a waveform diagram illustrating a current waveform of the output element in the second embodiment, where (a) is an on-continuation operation, and (b) and (c) are an operation that switches between an on-continuation operation and a switching operation. , (D) is a case of a switching operation. In FIG. 5, the horizontal axis represents time t, and the waveform of the current I5 of the output element 5 is represented.
The second embodiment is different from the first embodiment in the operation of the output element 5.

  As shown in FIG. 5A, when the output power POUT is less than or equal to the first output, the entire period of time t is the first period T1 during which the output element 5 continues to be turned on. It has become. A substantially constant direct current limited by the constant current element 6 flows through the output element 5. In a state where the output element 5 outputs a constant direct current, the illumination power supply 3 operates like a series regulator.

  As shown in FIGS. 5B and 5C, when the output power POUT becomes higher than the first output, the output element 5 performs the first period T1 during which the on-continuation operation is performed and the first period during which the switching operation is performed. The period T2 of 2 is repeated. The peak value of the oscillating current of the output element 5 is a value limited by the constant current value of the constant current element 6. In addition, the first period T1 in which the output element 5 is continuously turned on and the second period T2 in which the switching operation is performed vary according to the output power POUT. For example, FIG. 5C shows a case where the output power POUT is larger than in the case of FIG. 5B, and the second period T2 is longer than the first period T1.

  As shown in FIG. 5D, when the output power POUT is a second output that is relatively large, the entire period of time t is a second period T <b> 2 in which the switching operation of the output element 5 is performed. At this time, the illumination power supply 3 operates as a switching power supply. The second output is an output value larger than the first output.

As described above, the control circuit 72 switches the output element 5 to the on-continuation operation in the first period T1 and the switching operation in the second period, and continuously changes the average power. As a result, the output power POUT can be continuously changed between the maximum value and the minimum value. Moreover, the illumination load 2 in the illuminating device 1 can be dimmed continuously in the range of 0 to 100%.
Also in this embodiment, the same effect as that of the first embodiment can be obtained.

  As described above, the embodiments have been described with reference to specific examples. However, the embodiments are not limited thereto, and various modifications are possible.

  For example, the output element 5 and the constant current element 6 are not limited to the GaN-based HEMT. For example, a semiconductor element formed using a semiconductor (wide band gap semiconductor) having a wide band gap such as silicon carbide (SiC), gallium nitride (GaN), or diamond on the semiconductor substrate may be used. Here, the wide band gap semiconductor means a semiconductor having a wider band gap than gallium arsenide (GaAs) having a band gap of about 1.4 eV. For example, a semiconductor having a band gap of 1.5 eV or more, gallium phosphide (GaP, band gap about 2.3 eV), gallium nitride (GaN, band gap about 3.4 eV), diamond (C, band gap about 5.27 eV) , Aluminum nitride (AlN, band gap of about 5.9 eV), silicon carbide (SiC), and the like. Such a wide band gap semiconductor element can be made smaller than a silicon semiconductor element when the breakdown voltage is made equal, so that the parasitic capacitance is small and high speed operation is possible, so that the switching cycle can be shortened, and the winding parts and Capacitors can be miniaturized.

  The illumination light source 4 is not limited to an LED, and may be an EL or an OLED. A plurality of illumination light sources 4 may be connected to the illumination load 2 in series or in parallel.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 2 ... Illumination load, 3 ... Illumination power supply, 4 ... Illumination light source, 5 ... Output element, 6 ... Constant current element, 7 ... Power supply, 8 ... Dimmer, 9 ... Rectifier circuit, 9a ... High Potential terminal, 9b ... Low potential terminal, 12 ... Triac, 13 ... Phase circuit, 14 ... Diac, 15 ... Variable resistor, 16 ... Capacitor, 30 ... High potential output terminal, 31 ... Low potential output terminal, 40 ... Smoothing capacitor, DESCRIPTION OF SYMBOLS 70 ... 1st drive circuit, 71 ... 2nd drive circuit, 72 ... Control circuit, 73 ... Interface circuit, 74, 75 ... Input terminal, 76 ... AC power supply

Claims (6)

An output element connected between a power source and a lighting load and configured to be able to switch between a switching operation that repeats an on state and an off state and an on continuation operation that continues the on state ,
When the output to the lighting load is equal to or lower than the first output, the output element is switched to the on-continuation operation,
Switching the output element to the switching operation when the output to the illumination load is equal to or greater than a second output greater than the first output;
When the output to the lighting load is larger than the first output and smaller than the second output, the output element is switched to the on-continuation operation during the first period, and the switching operation is performed during the second period. Switching power supply for lighting.   The illumination power supply according to claim 1, further comprising: a control circuit that switches the output element to a switching operation or an on-continuation operation based on a control signal that controls an output to the illumination load.   The output element is switched to the switching operation when the output to the lighting load is relatively large, and the output element is switched to the on-continuation operation when the output to the lighting load is relatively small. The power supply for illumination according to 2. Said output element, lighting power according to any one of claims 1 to 3 which is an element of the normally-on type. The illumination power supply according to claim 4 , further comprising a constant current element connected in series to the output element. Lighting load,
The power supply for illumination according to any one of claims 1 to 5 , wherein power is supplied to the illumination load.
A lighting device comprising:

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