JP5975774B2 - LED lighting device - Google Patents

Description

The present invention relates to a lighting device for a light emitting diode (hereinafter referred to as LED: Light Emitting Diode).

LED attracts attention as a light source excellent in environmental properties, and has come to be used as LED lighting in houses and offices. Among LED lighting, there is a bulb-type LED lighting that has a base similar to an incandescent light bulb and is attached to an incandescent light fixture. Among them, there is a product corresponding to a phase control type dimmer (hereinafter simply referred to as a dimmer) that has been used as a dimming means for an incandescent bulb. Many dimmers conduct and block between the AC power supply and the load by turning on and off the semiconductor element. A triac (TRIAC: Triode Alternating Current Switch, three-terminal bidirectional thyristor) is used as a semiconductor element of the dimmer. Hereinafter, the semiconductor element is referred to as a triac, but other types of semiconductor elements may be used.

  After the triac is turned on (ignited), it is turned off (extinguishes) again unless a current larger than a predetermined current value called a holding current continues to flow. The holding current varies depending on the type of dimmer (triac), but has a width of about 5 to 50 mA. Many dimmers are designed on the assumption that the load is an incandescent bulb. If the load is an incandescent bulb, a sufficient current exceeding the holding current flows from the time when the triac is turned on until the time near the zero cross of the AC power supply voltage (hereinafter sometimes referred to as Vac), and the triac is turned on. The TRIAC turns off at the point near the zero cross.

  However, in the case where the load is an LED and its lighting device, since the power consumption is smaller than the case where the load is an incandescent light bulb, and the current is small, the triac turns off before reaching the vicinity of the zero cross of the AC power supply. Can happen. Hereinafter, this phenomenon is referred to as false extinction. In particular, in a situation where erroneous extinction occurs randomly or suddenly, or in a situation where the timing of erroneous extinction varies, the operation of the LED lighting device becomes unstable and flickering occurs.

  As an LED lighting device that prevents false extinction and prevents flickering, for example, there is a device described in Patent Document 1. In the device described in Patent Document 1, a damping resistor and a switch element are connected in series, and the damping resistor is connected in parallel to the noise prevention circuit of the dimmer for a predetermined period from the turn-on of the triac. As a result, the resonance operation generated by the noise prevention circuit at the turn-on of the triac is braked, and the current is vibrated greatly to prevent it from being smaller than the holding current of the triac. This prevents false arc extinction of the triac and flickering caused by this.

JP 2012-023001 A

In the device described in Patent Document 1, reduction of inrush current is not considered. When an LED lighting device is configured on the basis of a capacitor input type power supply circuit as described below, the voltage of the capacitor rapidly increases when the triac is turned on, so that an inrush current accompanying charging of the capacitor occurs. Many existing dimmable bulb-type LED lights are equipped with an inrush current prevention resistor (hereinafter abbreviated as an inrush prevention resistor) in order to reduce the inrush current. However, the increase in the size of the device and the increase in the loss due to the mounting of the impingement resistance were problems. Further, even if the inrush resistance is provided, the inrush current is still large, and there is a fear that the capacitors, the inrush resistance, the input filter parts, etc. are increased in size and loss. Since this inrush current will be described in the item of the following embodiment, the description is omitted here. Further, in the device described in Patent Document 1, a damping resistor, a switch element for controlling whether or not the damping resistor is connected to the noise prevention circuit, and a control circuit for controlling the switch element are newly provided externally. There is a need to increase the size of the device.

  An object of the present invention is to realize a small and highly efficient LED lighting device capable of preventing flicker and reducing inrush current when a dimmer is connected.

In order to achieve the above object, in the present invention, a rectifier circuit that converts an AC voltage into a rectified voltage and a DC output side of the rectifier circuit that is connected to the DC output side of the rectifier circuit through a first diode, the rectified voltage is converted into a DC link voltage. A first capacitor that converts the DC link voltage to supply power to a light emitting diode (hereinafter referred to as LED) load, and a current setting value of the DC-DC conversion circuit based on the rectified voltage A current setting circuit that outputs current, a shunt circuit that is connected between the DC output terminals of the rectifier circuit and includes at least one series body of a resistor and a switch element, and a switching circuit that controls the switch element in the series body. The switching circuit includes a period when the rectified voltage is lower than a desired reference voltage, and a time when the rectified voltage becomes higher than the desired reference voltage. In the period until the time of al desired time has elapsed, turns on the switch element in at least one of the series connection of the series connection body, the desired time, the rectified voltage is higher than the desired reference voltage the rectified voltage from the time when the said DC link voltage was so that is set as a time equal to or longer than up to the point of matching.

According to the LED lighting device of the present invention, when a dimmer is connected, flicker can be prevented and inrush current can be reduced, and a small and highly efficient LED lighting device can be realized.

It is a basic lineblock diagram of the LED lighting device in a 1st embodiment of the present invention. It is an internal circuit diagram of a dimmer. It is an operation | movement waveform at the time of using an incandescent lamp as a load of a dimmer. It is an operation | movement waveform which shows the subject about the conventional inrush current. It is an example of a structure of the shunt circuit and switching circuit in 1st Embodiment of this invention. It is an operation | movement waveform in 1st Embodiment of this invention. It is another example of a shunt circuit. It is another example of a switching circuit. It is another example of a shunt circuit and a switching circuit. It is another example of a switching circuit. It is another example of the operation | movement waveform in 1st Embodiment of this invention. It is another example of a shunt circuit and a switching circuit. It is another example of the operation | movement waveform in 1st Embodiment of this invention. It is a basic block diagram of the LED lighting device in 2nd Embodiment of this invention. It is a structural example of the shunt circuit and switching circuit in 2nd Embodiment of this invention. It is an operation | movement waveform in 2nd Embodiment of this invention. It is another example of the basic block diagram of the LED lighting device in 2nd Embodiment of this invention. It is an example of composition of a rectifier circuit and a DC-DC conversion circuit in a LED lighting device of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a basic configuration diagram of an LED lighting device 1 according to the first embodiment of the present invention. In FIG. 1, the AC power source 100, the dimmer 101, and the LED load 106 are not included in the LED lighting device 1. The LED lighting device 1 includes a rectifier circuit 102, a diode 103, a capacitor 104, a DC-DC conversion circuit 105, a shunt circuit 107, a switching circuit 108, and a current setting circuit 109.

  One end of the AC power supply 100 is connected to one end of the dimmer 101, and the other end of the dimmer 101 is connected to the rectifier circuit 102 in the LED lighting device 1. The other end of AC power supply 100 is connected to rectifier circuit 102. The AC power supply 100 generates an AC power supply voltage (hereinafter referred to as Vac). The rectifier circuit 102 rectifies the AC voltage phase-controlled by the dimmer 101 to generate a rectified voltage (hereinafter sometimes referred to as Vdc1). The rectifier circuit 102 is connected to the diode 103, the shunt circuit 107, the switching circuit 108, and the current setting circuit 109. The diode 103 is connected to the capacitor 104 and the DC-DC conversion circuit 105. Capacitor 104 converts the rectified voltage into a DC link voltage (hereinafter sometimes referred to as Vdc2). For example, when a capacitor input type power supply circuit is used, the DC link voltage is a voltage obtained by smoothing the rectified voltage. By smoothing the rectified voltage, it becomes easy for the subsequent DC-DC conversion circuit 105 to suppress the pulsation of the current flowing through the LED load 106 (hereinafter referred to as LED current). The DC-DC conversion circuit 105 converts the DC link voltage and supplies power to the LED load 106. Regarding the LED load 106, the number of LEDs and the connection form are not limited, and an LED module incorporating a protection element or the like may be included.

  A shunt circuit 107 is connected between the DC output terminals of the rectifier circuit 102. Although not shown in FIG. 1, the shunt circuit 107 includes at least one resistor and a switch element in series, and the current value flowing through the shunt circuit 107, in other words, the impedance of the shunt circuit 107 can be controlled from the outside. The switching circuit 108 outputs a switching signal for controlling the switch element of the shunt circuit 107 based on the rectified voltage. The shunt circuit 107 and the switching circuit 108 also serve to control the on / off state of the triac in the dimmer 101 according to the rectified voltage, and to reset the timer circuit of the dimmer 101 and turn on the triac again. . The current setting circuit 109 outputs the current setting value of the DC-DC conversion circuit 105 based on the rectified voltage. The current setting circuit 109 enables control of the LED current according to the operation of the dimmer 101, that is, dimming. Specific operations of the current setting circuit 109 include generating a current setting value corresponding to the average value of the rectified voltage, or detecting the firing angle of the dimmer 101 described below from the rectified voltage, and firing the current setting value. Some generate current setting values according to the corners. Some of the above components may be incorporated in the control IC, or may be implemented as a control program such as a microcomputer. In addition to the above components, a fuse, a rush resistance, an input filter coil, a capacitor, and the like may be added.

  Before describing the specific operation, the operation of the dimmer 101 will be described. FIG. 2 shows an internal circuit of the dimmer 101 using the triac 110. As shown in FIG. 2, the triac 110 is connected between the AC power supply 100 and the load 115. In parallel with the triac 110, a timer circuit that is a series body of a resistor 111, a variable resistor 112, and a capacitor 113 is connected. A connection point between the variable resistor 112 and the capacitor 113 is connected to the gate of the triac 110 via the diac 114. Although a coil and a capacitor are often added as a noise prevention circuit, they are omitted in FIG.

  FIG. 3 shows waveforms of the on / off state of the triac 110, the load voltage, and the load current when an incandescent bulb is connected as the load 115. During the on period of the triac 110, the load voltage is substantially the same as the voltage of the AC power supply 100. Since the incandescent bulb is almost pure resistance, the waveform of the load current is similar to the AC voltage. In the vicinity of the zero cross of the AC power supply voltage, when the load current becomes smaller than the holding current of the triac 110, the triac 110 is turned off. When the load 115 is an incandescent lamp, the holding current is sufficiently smaller than the amplitude value of the load current as shown in FIG.

  During the off period of the triac 110, a minute current flows from the AC power source 100 to the path of the resistor 111, the variable resistor 112, the capacitor 113, and the load 115, and charges are stored in the capacitor 113. Since the impedance of the dimmer 101 is sufficiently larger than that of the load 115, the load voltage becomes substantially zero. When the voltage on the capacitor 113 rises and the diac 114 is turned on, the triac 110 is turned on again. When the resistance value of the variable resistor 112 is increased by operating the dimmer 101, the time until the triac 110 is turned on again becomes longer. As a result, the load power is reduced, and the light output is reduced for an incandescent bulb. As shown in FIG. 3, the phase angle from the zero cross point of the AC power supply voltage until the triac 110 is fired is defined as the firing angle. If the firing angle is represented by the symbol θ, the possible range is 0 ≦ θ ≦ 180 [deg]. The greater the firing angle, the smaller the light output.

  In the present invention, the load 115 in FIG. 2 is the LED lighting device 1 in FIG. Specifically, the impedance is higher than that of an incandescent bulb, and it is not necessarily pure resistance like an incandescent bulb. Therefore, the operation waveform is not always the same as in FIG.

  Next, the problem of inrush current focused on in the present invention will be described. FIG. 4 is an operation waveform when the inrush current becomes particularly large when a conventional LED lighting device (without considering the countermeasure for inrush current) is connected as the load of the dimmer 101. This LED lighting device includes a rectifier circuit 102, a diode 103, a capacitor 104, and a DC-DC converter circuit 105, as in the device of the present invention. The rectifier circuit 102 smoothes the rectified voltage, and the capacitor 104 smoothes the rectified voltage. To generate a DC link voltage. In FIG. 4, the rectified current is a DC output current of the rectifier circuit 102. In FIG. 4, the operation waveform for the half cycle of the AC power supply 100 is shown.

  In the LED lighting device based on the capacitor input type power supply circuit, the DC link voltage is higher than the rectified voltage (Vdc2> Vdc1) when the triac 110 is turned on as shown in FIG. Such a situation is likely to occur when the firing angle of the triac 110 is small and the dimming level is high (bright), or when the capacitance of the capacitor 104 that generates the DC link voltage is large. At this time, since the rectified current does not flow even when the triac 110 is on, the triac 110 is immediately erroneously extinguished as shown in FIG.

  The triac 110 does not turn on again until a certain amount of time has elapsed after the false arc extinction until the capacitor 113 of the timer circuit of the dimmer 101 is recharged. From FIG. 4, there is a time point (Vdc1 = Vdc2) at which the rectified voltage and the DC link voltage become equal after erroneous extinction. In the case where the dimmer 101 is not connected, in the capacitor input type power supply circuit, an inrush current for charging the capacitor 104 at this time, and consequently, a rectified current starts to flow. However, when the dimmer 101 is connected and the triac 110 is turned off as shown in FIG. 4, almost no rectified current flows.

  In FIG. 4, when the triac 110 is turned on (re-ignited) again, the AC power supply voltage (the absolute value thereof) is higher than the DC link voltage (| Vac |> Vdc2). At this time, the voltage of the capacitor 104 increases rapidly, and a large inrush current is generated to charge the capacitor 104. From FIG. 4, the rectified current starts to flow abruptly when the triac 110 is re-ignited, and this is the inrush current that charges the capacitor 104. In addition, since the rectification current starts to flow when the rectifier current starts to flow when the dimmer 101 is not connected, that is, when the dc current becomes Vdc1 = Vdc2, the rectification current starts flowing at a later time (phase is advanced). Becomes bigger. In FIG. 4, the operation after the triac 110 is re-ignited will be described below, and the description is omitted here.

  Next, the specific configuration and operation of the LED lighting device according to the first embodiment of the present invention, and the reason why the flicker can be prevented and the inrush current can be reduced by this will be described. FIG. 5 is a configuration example of the shunt circuit 107 and the switching circuit 108 in the first embodiment of the present invention. (However, FIG. 5 also shows other components such as the rectifier circuit 102.) FIG. 6 shows the operation of the LED lighting device obtained by configuring the shunt circuit 107 and the switching circuit 108 as shown in FIG. It is a waveform.

  The shunt circuit 107 in FIG. 5 is a series body of a resistor 126 and a switch element 127. In FIG. 5, the switch element 127 is a MOSFET, but other types of elements such as bipolar transistors and IGBTs may be used.

  The switching circuit 108 includes a preprocessing circuit 116, a comparison circuit (comparator) 117, and a falling delay circuit 118. The preprocessing circuit 116 preprocesses the rectified voltage in order to compare the rectified voltage with the reference voltage in the comparison circuit 117 in the subsequent stage. In FIG. 5, the preprocessing circuit 116 is a voltage dividing circuit composed of resistors 119 and 120. In addition, a regulator circuit described later, a clamp circuit, or a slice circuit may be used. Whether the switching circuit 108 includes the preprocessing circuit 116 is arbitrary, but the level of the rectified voltage is lowered by a voltage dividing circuit or the like, or the maximum value of the rectified voltage is clamped by a clamp circuit or the like. Thus, the comparator circuit 117 can use a low breakdown voltage comparator.

  The comparison circuit 117 includes a comparator 121 and a voltage source 122 that generates a reference voltage, and compares the rectified voltage or the preprocessed rectified voltage with the reference voltage. In FIG. 5, a logic is used in which the comparison circuit 117 outputs a low level (hereinafter referred to as L level) when the rectified voltage is higher than the reference voltage. However, depending on the configuration of the subsequent stage of the comparison circuit 117, the reverse logic may be used. Although the generation method of the voltage source 122 is arbitrary, there are a method of generating from a DC link voltage using a regulator (dropper) circuit, and a method of using the operating voltage if a control IC is used.

  The falling delay circuit 118 includes a resistor 123, a diode 124, and a capacitor 125, and outputs a switching signal to the switch element 127 of the shunt circuit 107. The switch element 127 is a MOSFET, and the switching signal corresponds to its gate voltage. In the falling delay circuit 118, the resistor 123 and the capacitor 125 function as an RC (low pass) filter with respect to the falling of the rectangular wave signal output from the comparison circuit 117. Therefore, after the output signal of the comparison circuit 117 becomes L level, the voltage of the capacitor 125, that is, the switching signal gradually decreases according to the time constant of the RC filter. That is, there is a delay from when the output signal of the comparison circuit 117 becomes L level until the switch element 127 is turned off. With respect to the rise of the output signal of the comparison circuit 117, the delay as described above hardly occurs due to the effect that the diode 124 bypasses the resistor 123. Therefore, when the rectified voltage becomes lower than the reference voltage and the output signal of the comparison circuit 117 becomes high level (hereinafter referred to as H level), the switch element 127 is immediately turned on. Note that the use of the capacitor 125 is arbitrary because the parasitic capacitance of the switch element 127 can be used in place of the capacitor 125.

  With the above configuration, as shown in FIG. 6, the switch element 127 in the shunt circuit 107 is in a period in which the rectified voltage is lower than the reference voltage and a period from when the rectified voltage becomes higher than the reference voltage until a desired delay time elapses. Turns on.

  The operation of the first embodiment will be described with reference to FIG. When the rectified voltage becomes lower than the reference voltage, the switching circuit 108 turns on the switch element 127 of the shunt circuit 107 and makes the resistor 126 conductive between the DC output terminals of the rectifier circuit 102. At this time, the triac 110 of the dimmer 101 is turned off. When the minute current flows from the AC power source 100 to the path of the resistor 111, the variable resistor 112, the capacitor 113, and the resistor 126 of the dimmer 101, the capacitor 113 is charged.

  When the capacitor 113 is charged and the triac 110 is turned on, the rectified voltage increases to almost the same value as the AC power supply voltage (absolute value thereof). Although the rectified voltage becomes higher than the reference voltage, the switch element 127 is not immediately turned off at this time, but the switch element 127 is kept on until a desired time elapses as described above. Therefore, even if the DC link voltage is higher than the rectified voltage (Vdc2> Vdc1) and the current for charging the capacitor 104 does not flow, the rectified current exceeding the holding current flows in the shunt circuit 107, so that the triac 110 is not erroneously extinguished. Keep on.

  When the rectification current and the DC link voltage coincide with each other (Vdc2 = Vdc1) while the triac 110 is kept on, a current for charging the capacitor 104 flows. Therefore, the rectified current increases rapidly as shown in FIG. However, for the reasons described above, the increase in the rectified current at this time is smaller than that of the conventional LED lighting device (not taking measures against the inrush current), and as a result, the effective value of the rectified current is also reduced. . When a desired time elapses after the rectified voltage becomes higher than the reference voltage, the switch element 127 is turned off. Thereafter, as long as the current for charging the capacitor 104 is larger than the holding current, the triac 110 is kept on.

  As the charging of the capacitor 104 proceeds, the rectified current decreases. The triac 110 is turned off when the DC link voltage almost reaches its peak value and the rectified current becomes smaller than the holding current. Even after the triac 110 is turned off, the DC-DC conversion circuit 105 operates stably by the voltage of the charged capacitor 104, that is, the DC link voltage. Further, the timing at which the TRIAC 110 is turned off, that is, the timing at which the rectified current is reduced to the holding current or less hardly changes in each cycle of the AC power supply, and thus flicker does not occur.

Note that the configuration shown in FIG. 5 is an example for realizing on / off control of the switch element 127 shown in FIG. 6 with a simple circuit. If the on / off control of the switch element 127 shown in FIG. 6 can be realized, the configurations of the shunt circuit 107 and the switching circuit 108 may be different from those in FIG.
FIG. 7 shows another example of the shunt circuit 107. In FIG. 7, a resistor 129, a Zener diode 130, and a MOSFET 131 constitute a regulator circuit 128, and a series body of a resistor 126 and a switch element (MOSFET) 127 is connected as a load. Instead of the MOSFET 131, other types of semiconductor elements such as bipolar transistors and IGBTs may be used.

  When the rectified voltage is higher than the zener voltage, the voltage applied to the series body of the resistor 126 and the switch element (MOSFET) 127 becomes substantially equal to the zener voltage of the zener diode 130. That is, the regulator circuit plays a role of clamping the rectified voltage. Further, the current flowing through the shunt circuit 107 when the switch element 127 is on is constant regardless of the rectified voltage, and can be adjusted by the resistor 126. In the operation of FIG. 6, in a period in which the triac 110 is kept on until Vdc2 = Vdc1, a current larger than the holding current of the triac 110 may be supplied. 7 is effective in reducing the loss of the shunt circuit 107 because the current can be minimized by adjusting the resistor 126.

  As shown in FIG. 7, the resistor 132 may be connected in parallel with the series body of the resistor 126 and the switch element 127 to adjust the current flowing through the shunt circuit 107. This can be said in the configuration of all the shunt circuits 107 in the present invention. The connection of the resistor 132 is arbitrary.

  FIG. 8 shows another example of the switching circuit 108. In FIG. 8, a comparison circuit 133 including a comparator 134 and a voltage source 135 is connected to the subsequent stage of the falling delay circuit 118, and the comparison circuit 133 outputs a switching signal. When the output voltage of the falling delay circuit 118 is higher than the voltage of the voltage source 135, the switching signal becomes H level and turns on the switch element 127 of the shunt circuit 107. That is, the on / off threshold value of the switch element 127 shown in FIG. 6 is replaced with the voltage of the voltage source 135. If the power required for driving the switch element 127 is large, a driver circuit may be optionally added after the comparison circuit 133.

  Based on the configuration of FIG. 8, the following modifications are also possible. First, the output logic of the comparison circuits 117 and 133 is inverted. Specifically, the comparison circuit 117 outputs an H level when the preprocessed rectified voltage is higher than the voltage of the voltage source 122. The same applies to the comparison circuit 133. Next, the falling delay circuit 118 is changed to a rising delay circuit. The rise delay circuit functions as an RC filter only for the rise of the rectangular wave signal output from the comparison circuit 117. Specifically, the direction of the diode 124 is reversed and the anode is connected to the output terminal of the comparison circuit 117.

  FIG. 9 shows another example of the shunt circuit 107 and the switching circuit 108. In the shunt circuit of FIG. 9, a series body of a resistor 136 and a switch element 137 is added, and two series of resistors and a series body of the switch element are connected in parallel. The switching circuit 108 outputs the output signal of the comparison circuit 117 as the switching signal of the switch element 137. That is, the switching circuit 108 outputs two switching signals having different on / off timings. With this configuration, the magnitude of the current flowing through the shunt circuit 107 can be changed between a period in which the rectified voltage is lower than the reference voltage and a period in which a desired time elapses after the rectified voltage becomes higher than the reference voltage. . In addition, a regulator circuit may be added as shown in FIG. 7, and a series body of two sets of resistors and switch elements may be connected as a load of the regulator circuit. In this other example, the current of the shunt circuit 107 can be easily adjusted by the two sets of series bodies, and it is effective in distributing heat generation to the two sets of series bodies.

  As described above, in the first embodiment of the present invention, the dimmer can be stably operated to suppress flickering, and the inrush current can be reduced. By reducing the inrush current, the inrush resistance, the capacitor 104, and the input filter component can be reduced in size and loss. In addition, the first embodiment of the present invention can solve two problems of flicker suppression and inrush current reduction with a single configuration, and is also effective in reducing the size and cost of an LED lighting device.

  FIG. 10 shows another example of the switching circuit 108, and FIG. 11 shows operation waveforms obtained when the switching circuit 108 of FIG. 10 and the shunt circuit 107 of FIG. 5 are combined. In the switching circuit 108 in FIG. 10, the falling delay circuit 118 in FIG. 8 is changed to a delay circuit 149. The delay circuit 149 is an RC filter including a resistor 123 and a capacitor 125. As shown in FIG. 11, the voltage of the capacitor 125 increases or decreases according to the time constant of the RC filter both at the rising edge and the falling edge of the output of the comparison circuit 117. Therefore, not only is a delay from when the rectified voltage becomes higher than the reference voltage until the switch element 127 in the shunt circuit 107 is turned off, but also the switch element 127 is turned on after the rectified voltage becomes lower than the reference voltage. A delay occurs. Here, by setting the voltage value of the voltage source 135 in FIG. 10 to a value close to the L level, the latter delay becomes almost negligible as shown in FIG. As a result, the on / off timing of the switch element 127 becomes substantially the same as that shown in FIG.

  FIG. 12 shows another example of the shunt circuit 107 and the switching circuit 108. In the switching circuit 108 in FIG. 12, subdivision such as the preprocessing circuit 116 and the comparison circuit 117 shown in FIG. 5 is omitted. 12, the shunt circuit 107 is based on FIG. 7, and a series body of a resistor 126 and a switch element 127 is connected as a load of a regulator circuit composed of a MOSFET 131 and the like. However, as a difference from FIG. 7, a resistor 150 and a capacitor 151 are connected in parallel with the Zener diode 130 of the regulator circuit. This regulator circuit is also a part of the switching circuit 108, and the resistor 150, the capacitor 151, and the resistor 129 function as an RC filter in FIG.

  In the switching circuit 108, the comparator 152 compares the output voltage of the regulator circuit with the voltage of the voltage source 153. When the output voltage of the regulator circuit is lower than the voltage of the voltage source 153, the switching signal that is the output of the comparator 152 becomes H level, and the switch element 127 of the shunt circuit 107 is turned on.

  FIG. 13 shows operation waveforms obtained when the shunt circuit 107 and the switching circuit 108 of FIG. 12 are used. After the triac 110 is turned on and the rectified voltage becomes higher than the reference voltage, the voltage of the Zener diode 130 gradually increases according to the time constant determined by the resistors 129 and 150 and the capacitor 151, and becomes the break voltage of the Zener diode 130. Reach.

  At this time, the output voltage of the regulator circuit gradually increases according to the voltage of the Zener diode 130. As a result, as shown in FIG. 13, a delay is generated after the rectified voltage becomes higher than the reference voltage until the output voltage of the regulator circuit becomes higher than the voltage of the voltage source 135 and the switch element 127 is turned off. be able to. The on / off timing of the switch element 127 is substantially the same as that shown in FIG.

  In this other example, the shunt circuit 107 and the switching circuit 108 can be configured with a small number of parts, which is effective for reducing the size and cost of the apparatus.

  FIG. 14 is a basic configuration diagram of an LED lighting device according to the second embodiment of the present invention. In the second embodiment, a resistor 138 for detecting the current flowing in the capacitor 104 is added to the first embodiment shown in FIG. The switching circuit 108 outputs a switching signal according to the current detected by the resistor 138 in addition to the rectified voltage. The resistor 138 may be connected to an arbitrary position in FIG. 14 under the condition that the current of the capacitor 104 can be detected. Further, the current of the capacitor 104 may be detected by another type of current sensor instead of the resistor 138.

  The current of the capacitor 104 may be indirectly detected by detecting the rectified current.

  FIG. 15 shows an internal configuration example of the switching circuit 108 in the second embodiment of the present invention. FIG. 15 also shows other components such as the shunt circuit 107. FIG. 16 is an operation waveform of the LED lighting device obtained by configuring the switching circuit 108 as shown in FIG. In FIG. 16, it is assumed that the current of the capacitor 104 is indirectly detected by detecting the rectified current as described above.

  In the switching circuit 108 in FIG. 15, a comparison circuit 139 including a comparator 140 and a voltage source 141 is added to the circuit shown in FIG. Here, although the comparator 140 is an open collector output, a comparator that is not an open collector output may be used depending on other configurations. The comparison circuit 139 compares a current detected by the resistor 138 (hereinafter referred to as a detection current) with a reference current expressed as a voltage value of the voltage source 141. In FIG. 15, a logic is used in which the comparison circuit 139 outputs an L level when the detected current is larger than the reference current. Accordingly, when the detected current is larger than the reference current, the switching signal is forcibly set to the L level, and the switch element 127 of the shunt circuit 107 is turned off. In the switching circuit 108, the detection current may not be input directly to the comparison circuit 139, but may be input via a preprocessing circuit such as 116 in FIG. In particular, a configuration in which the preprocessing circuit is an integration circuit or a low-pass filter is effective for removing high-frequency components of the detection current.

  The operation of the second embodiment will be described with reference to FIG. As in the first embodiment shown in FIG. 6, the switch element 127 is not turned off immediately after the rectified voltage becomes higher than the reference voltage, but the switch element 127 is turned on until a desired time elapses. Try to maintain. When the rectified current coincides with the DC link voltage (Vdc1 = Vdc2), a current for charging the capacitor 104 flows, and the rectified current suddenly increases. As a result, the detection current becomes larger than the reference current, and at this time, the switch element 127 is forcibly turned off. As described above, in the second embodiment, the predetermined delay time in the first embodiment is automatically generated as “time until the detected current becomes larger than the reference current”. Note that, during the period when the detected current is smaller than the reference current, the output signal of the comparison circuit 139 is at the open collector H level, so that the other circuits are not affected and the operation is the same as in the first embodiment.

  If Vdc2 = Vdc1 and a current for charging the capacitor 104 starts to flow, the triac 110 can be kept on without supplying current to the shunt circuit 107. In the second embodiment, it is possible to minimize the period during which a current flows through the shunt circuit 107 and reduce the loss of the shunt circuit 107.

  Note that the configuration shown in FIG. 15 is an example for realizing on / off control of the switch element 127 shown in FIG. 16 with a simple circuit. As long as the on / off control of the switch element 127 shown in FIG. 16 can be realized, the configurations of the shunt circuit 107 and the switching circuit 108 may be different from those in FIG. Another example of the shunt circuit 107 or the switching circuit 108 shown in FIGS.

  FIG. 17 is another example of the basic configuration diagram of the LED lighting device according to the second embodiment of the present invention. In FIG. 17, the DC link voltage is detected instead of detecting the current of the capacitor 104 in FIG. The switching circuit 108 outputs a switching signal according to the rectified voltage and the DC link voltage. As a specific operation of the switching circuit 108 in FIG. 17, if a point in time when the rectified voltage and the DC link voltage match (Vdc1 = Vdc2) is detected and the switch element 127 is turned off as in the switching circuit in FIG. The operation shown in FIG. 16 can be realized. A specific configuration of the switching circuit 108 in this other example is omitted.

  FIG. 18 specifically shows the configuration of the rectifier circuit 102 and the DC-DC conversion circuit 105 in the LED lighting device shown in FIG. The same configuration can be applied to the LED lighting devices of FIGS. 14 and 17. In FIG. 18, the full-wave rectifier circuit using the diode bridge 142 corresponds to the rectifier circuit 102. A step-down chopper circuit including a diode 143, a MOSFET 144, a choke coil 145, a capacitor 146, a current detection resistor 147, and a control circuit 148 corresponds to the DC-DC conversion circuit 105. In addition to these, a fuse, an anti-shock resistor, an input filter coil, a capacitor, and the like may be added. Depending on the voltage of the LED load 106, a step-up / step-down chopper or a step-up chopper may be used instead of a step-down chopper, and a flyback converter may be used if insulation is necessary. Instead of the MOSFET 144, other kinds of elements such as bipolar transistors and IGBTs may be used.

  In FIG. 18, the control circuit 148 controls the current output from the DC-DC conversion circuit 105 to the LED load 106 according to the current setting value. Specifically, it is conceivable to control the MOSFET 144 until the current flowing through the MOSFET 144 reaches a current set value.

  By controlling the current flowing through the MOSFET 144, the current flowing through the LED load 106 can be indirectly controlled. Such a control circuit 148 can be easily configured by using a commercially available LED control IC. Of course, without using the control IC, it may be configured by combining discrete components such as a comparator, or may be configured as software using a microcomputer or a digital signal processor.

1 LED lighting device 100 AC power supply 101 Dimmer 102 Rectifier circuit 103 Diode (124 is also the same)
104 capacitors (same for 113, 125, 146, 151)
105 DC-DC conversion circuit 106 LED load 107 Shunt circuit 108 Switching circuit 109 Current setting circuit 110 Triac 111 resistance (119, 120, 123, 126, 129, 132, 136, 138, 147, 150 are also the same)
112 Variable resistance 114 Diac 115 Load 116 such as incandescent bulb Pre-processing circuit 117 Comparison circuit (the same applies to 133 and 139)
118 Falling delay circuit 121 Comparator (134, 140, 152 are also the same)
122 Voltage source (Same for 135, 141, 153)
127 MOSFET (same for 131, 137, 144)
128 Regulator circuit 130 Zener diode 142 Diode bridge 145 Choke coil 148 Control circuit 149 Delay circuit

Claims (10)

A rectifier circuit that converts an AC voltage into a rectified voltage, a first capacitor that is connected to a DC output side of the rectifier circuit via a first diode, converts the rectified voltage into a DC link voltage, and converts the DC link voltage. A DC-DC conversion circuit that supplies power to a light emitting diode (hereinafter referred to as LED) load, a current setting circuit that outputs a current setting value of the DC-DC conversion circuit based on the rectified voltage, An LED lighting device comprising: a shunt circuit that is connected between DC output terminals and includes at least one series body of a resistor and a switch element; and a switching circuit that controls the switch element in the series body,
The switching circuit includes the serial body in a period in which the rectified voltage is lower than a desired reference voltage and a period from a time when the rectified voltage is higher than the desired reference voltage to a time when a desired time elapses. Turning on at least one switch element in the series body ;
The desired time, the rectified voltage is set as the desired the rectified voltage from the higher becomes time than the reference voltage and the time equal to or longer than up to the point of the DC link voltage coincides with said Rukoto LED lighting device. The LED lighting device according to claim 1,
The switching circuit sets the time from when the rectified voltage becomes higher than the desired reference voltage to the time when the current flowing through the first capacitor becomes larger than the desired reference current as a desired time in claim 1. LED lighting device characterized. The LED lighting device according to claim 1,
2. The LED according to claim 1, wherein the switching circuit sets a time from when the rectified voltage becomes higher than the desired reference voltage to a time when the rectified voltage matches the DC link voltage as a desired time in claim 1. Lighting device. In the LED lighting device according to any one of claims 1 to 3,
The switching circuit includes a first comparison circuit that outputs a signal that is at a low level during a period in which the rectified voltage is higher than the desired reference voltage, and a desired time constant with respect to a fall of the output signal of the first comparison circuit. And a falling delay circuit that outputs a signal given a delay time according to claim 1, wherein the switch element is controlled by an output signal of the falling delay circuit. In the LED lighting device according to claim 4,
The falling delay circuit includes a series body of a first resistor and a second capacitor connected between the output terminal of the first comparison circuit and the ground, and a second diode connected in parallel with the first resistor. One end of the resistor is connected to the output terminal of the first comparison circuit, one end of the second capacitor is connected to the ground, and the anode terminal of the second diode is connected to the output terminal of the first comparison circuit. The LED lighting device characterized by the above-mentioned. In the LED lighting device according to any one of claims 1 to 3,
The shunt circuit includes two or more series bodies of resistors and switch elements, and the switching circuit includes a period when the rectified voltage is lower than the desired reference voltage, and a time when the rectified voltage becomes higher than the desired reference voltage. A first switching signal for turning on a switching element in at least one of the series bodies in a period from a time point until a point in time when a desired time elapses, and the rectified voltage is The LED lighting device, wherein a second switching signal is output in order to control to turn on a switch element in at least one of the series bodies in a period lower than the desired reference voltage. The LED lighting device according to claim 6,
The switching circuit includes a first comparison circuit that outputs a signal that becomes a low level during a period in which the rectified voltage is higher than the reference voltage, and a delay based on a desired time constant with respect to a fall of the output signal of the first comparison circuit A falling delay circuit for outputting a signal given with time, wherein the output signal of the falling delay circuit is the first switching signal, and the output signal of the first comparison circuit is the second switching signal. LED lighting device. In the LED lighting device according to any one of claims 1 to 7,
An LED lighting device, wherein a series body of a resistor and a switch element included in the shunt circuit is connected between DC output terminals of the rectifier circuit. In the LED lighting device according to any one of claims 1 to 7,
The shunt circuit includes a regulator circuit that clamps the rectified voltage at the desired voltage value, and a series body of a resistor and a switch element included in the shunt circuit is connected as a load of the regulator circuit. LED lighting device. In the LED lighting device according to any one of claims 1 to 3,
The shunt circuit includes a second resistor and a Zener diode connected in series between the DC output terminals of the rectifier circuit, a third resistor and a third capacitor connected in parallel with the Zener diode, and the second resistor. And a gate terminal connected to the connection point of the Zener diode, a MOSFET whose drain terminal is connected to the positive side of the DC output of the rectifier circuit, and a source terminal of the MOSFET and a negative side of the DC output of the rectifier circuit A fourth body resistor, and a series body of the resistor and the switch element connected in parallel with the fourth resistor,
The switching circuit also uses the second resistor, the Zener diode, the third resistor, the third capacitor, and the MOSFET included in the shunt circuit as components of the switching circuit, and the source terminal voltage of the MOSFET is higher than a reference value. An LED lighting device comprising: a second comparison circuit that outputs a signal that is sometimes at a low level, and controlling the switch element by an output signal of the second switching circuit