JP2012089383A - Lighting device, and lighting fixture using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which supplies a current to a semiconductor light-emitting element by using an insulating transformer, and can enhance conversion efficiency in feedback control while reducing the cost, and to provide a lighting fixture using the same.SOLUTION: The lighting device comprises a transformer T1 having a primary winding N1, a secondary winding N2 and a tertiary winding N3 coupled magnetically where a rectifying and smoothing circuit 3 is connected across the primary winding N1 and an LED unit 7 is connected across the secondary winding N2, a switching element Q1 which conducts and interrupts a current supplied to the primary winding N1, and a control unit 5 which controls on/off operation of the switching element Q1 based on the output from the tertiary winding N3 thus controlling the LED current Io supplied to the LED unit from the secondary winding N2.

Description

  The present invention relates to a lighting device using a semiconductor light emitting element such as an LED, and a lighting fixture using the same.

  Conventionally, there is a lighting device that lights a semiconductor light emitting element such as an LED (Light Emitting Diode). This lighting device uses an insulating transformer, and the current supplied to the primary side of the transformer is turned on and off to control the current supplied to the semiconductor light emitting element connected to the secondary side of the transformer. (For example, refer to Patent Document 1).

JP 2010-93874 A

  The lighting device as described in Patent Document 1 requires a resistor (current detection resistor) for detecting the output current on the secondary side of the transformer in order to control the current supplied to the LED. However, since the power loss in the current detection resistor is large, there is a problem that the conversion efficiency of the circuit is lowered. In addition, in order to feed back the detection signal of the current detection resistor to the control circuit provided on the primary side of the transformer, an insulating photocoupler is required, which increases the cost of the device.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to supply current to a semiconductor light emitting element using an insulating transformer and to improve conversion efficiency and reduce cost in feedback control. It is providing the lighting device which can be used, and a lighting fixture using the same.

  The lighting device according to the present invention includes a primary winding, a secondary winding, and a tertiary winding that are magnetically coupled to each other, and a DC power source is connected between both ends of the primary winding. A transformer having a semiconductor light emitting element connected between both ends thereof, a switching element for conducting / cutting off a current supplied to the primary winding, and an on / off operation of the switching element based on the output of the tertiary winding And a control unit for controlling a current supplied from the secondary winding to the semiconductor light emitting element.

  In the present invention, a detection circuit that detects at least one of a short circuit state and a no-load state of the semiconductor light emitting element based on the output of the tertiary winding is provided, and the control unit includes the detection circuit that detects the semiconductor light emission. When a short circuit state or no load state of the element is detected, it is preferable to reduce the current supplied to the semiconductor light emitting element.

  In this invention, it is preferable that the control unit uses the output of the tertiary winding as a power source.

  In the present invention, the control unit detects a current flowing through the secondary winding based on an output of the tertiary winding, and when the current flowing through the secondary winding becomes a predetermined value or less, It is preferable to turn on the switching element.

  In the present invention, the transformer and the switching element preferably constitute a flyback converter.

  In the present invention, the secondary winding and the tertiary winding are preferably configured to have the same polarity.

  The lighting apparatus of the present invention includes a primary winding, a secondary winding, and a tertiary winding that are magnetically coupled to each other, and a DC power source is connected between both ends of the primary winding, and the secondary winding A transformer in which a semiconductor light emitting element is connected between both ends thereof, a switching element that conducts and cuts off a current supplied to the primary winding, and an on / off operation of the switching element is controlled based on the output of the tertiary winding And a lighting device including a control unit that controls a current supplied from the secondary winding to the semiconductor light emitting element, and connected between both ends of the secondary winding, from the secondary winding of the lighting device. And a semiconductor light emitting element to which a current is supplied.

  As described above, according to the present invention, there is an effect that current can be supplied to the semiconductor light emitting element using an insulating transformer, and conversion efficiency in feedback control can be improved and cost can be reduced.

2 is a circuit diagram illustrating a configuration of a lighting device according to Embodiment 1. FIG. It is a block diagram which shows the structure of the integrated circuit for control same as the above. It is a characteristic view which shows a LED current-output voltage characteristic same as the above. It is a circuit diagram which shows the structure of the lighting device of Embodiment 2. It is a circuit diagram which shows the structure of the lighting device of Embodiment 3. It is a circuit diagram which shows another structure of DC power supply. It is a schematic block diagram which shows the external appearance of the lighting fixture of Embodiment 4.

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

(Embodiment 1)
FIG. 1 shows a configuration of a lighting device 1 according to the present embodiment, and the lighting device 1 includes a filter circuit 2, a rectifying / smoothing circuit 3, a converter unit 4, a control unit 5, and a control power supply circuit 6. Between the input ends of the filter circuit 2 is connected to a commercial power source 200 (for example, 100 V, 50/60 Hz) via a connector CN1, and a fuse F1 is interposed between the connector CN1. The LED unit 7 is connected between the output ends of the converter unit 4 via the connector CN2.

  In the filter circuit 2, a parallel circuit of a varistor VR1 and a capacitor C1 is connected between input terminals, and a common mode choke coil LF1 is connected to each of the input terminals. Further, the capacitor C2 is connected in parallel to the capacitor C1 via the common mode choke coil LF1. The filter circuit 2 has the above configuration to reduce noise components in the input stage.

  The rectifying / smoothing circuit 3 includes a rectifier DB1 that receives the output of the filter circuit 2 and full-wave rectifies the AC voltage of the commercial power supply 200, and a capacitor C3 that smoothes the rectified output of the rectifier DB1. The rectifying / smoothing circuit 3 rectifies and smoothes the AC power of the commercial power supply 200 by using the above configuration, and functions as the DC power supply of the present invention.

  The converter unit 4 includes an insulating transformer T1, and the transformer T1 includes a primary winding N1, a secondary winding N2, and a tertiary winding N3. The primary winding N1, the secondary winding N2, and the like. The tertiary winding N3 is magnetically coupled to each other. A series circuit of the primary winding N1, the switching element Q1, and the resistor R1 is connected between the output terminals of the rectifying and smoothing circuit 3. A series circuit of a capacitor C4, a regenerative diode D1 and a resistor R3 is connected between both ends of the primary winding N1, and a resistor R2 is connected in parallel to the capacitor C4, and both ends of the primary winding N1. A snubber circuit for suppressing the voltage is configured. Further, a series circuit of a diode D2 and a capacitor C5 is connected between both ends of the secondary winding N2, and the voltage generated between both ends of the primary winding N1 is rectified and smoothed. A connector CN2 is connected between both ends of the capacitor C5, and is connected to the LED unit 7 via the connector CN2. That is, the voltage across the capacitor C <b> 5 becomes the output voltage Vo and is applied to the LED unit 7.

  The control power supply circuit 6 includes a Zener diode ZD1 and a capacitor C7 connected in parallel, and generates a control voltage Vcc set to the Zener voltage of the Zener diode ZD1. As a simple configuration, a high resistance (not shown) is interposed between the positive electrode of the capacitor C3 and the positive electrode of the capacitor C7, and the DC voltage output from the rectifying and smoothing circuit 3 is used as the input of the control power supply circuit 6.

  The LED unit 7 includes one or more LED elements 71. In the present embodiment, the LED unit 7 includes a plurality of LED elements 71 connected in series. The LED unit 7 may be configured by connecting a plurality of LED elements 71 in parallel or in series-parallel.

  The converter unit 4 having the above configuration operates as a flyback converter, and conducts / cuts off the primary current I1 supplied from the rectifying / smoothing circuit 3 to the primary winding N1 by turning on / off the switching element Q1. . The converter unit 4 receives a DC power source constituted by the rectifying / smoothing circuit 3, and when the switching element Q1 is turned on, the primary current I1 is supplied from the rectifying / smoothing circuit 3 to the primary winding N1, and magnetic energy is supplied to the transformer T1. Is accumulated. The primary current I1 increases approximately linearly unless the transformer T1 is saturated.

  When the switching element Q1 is switched from the on state to the off state, an induced voltage is generated in the secondary winding N2 by the magnetic energy accumulated in the transformer T1. Thus, the secondary current I2 flows from the secondary winding N2 via the diode D2, and an output voltage Vo obtained by stepping down the DC voltage output from the rectifying and smoothing circuit 3 is generated between the capacitors C5. At this time, since the voltage across the secondary winding N2 is clamped to the output voltage Vo, the secondary current I2 decreases with a substantially constant slope. The capacitor C5 is set to have a capacity capable of smoothing a pulsating component due to the on / off of the switching element Q1 and supplying a current with little ripple to the LED unit 7.

  Further, a resistor R1 is connected in series to the series circuit of the primary winding N1 and the switching element Q1, and this resistor R1 is a primary current detection resistor for detecting the primary current I1, The voltage across R1 serves as a detection signal for the primary current I1. Since the resistor R1 is a low resistance for current detection, it hardly affects the driving of the switching element Q1 described later.

  The control circuit 5 has a function of controlling the LED current Io supplied to the LED unit 7 to a desired value by driving the switching element Q1 on and off at a high frequency, and includes a control integrated circuit K1, a transformer It is composed of the N1 tertiary winding N3 and its peripheral circuits.

  The control integrated circuit K1 has the internal configuration shown in FIG. 2, and a peripheral circuit is connected to each of the 1st to 8th pins P1 to P8. In the present embodiment, the control integrated circuit K1 uses an L6562 IC chip manufactured by STMicroelectronics. This IC chip is originally a circuit for controlling the operation of the step-up chopper for power factor correction control, and internally includes a multiplication circuit and the like necessary for controlling the step-up chopper operation. In addition, the chip has a function to control the peak value of the input current and a zero-cross control function in order to control the average value of the input current in a similar manner to the envelope of the input voltage. Used to control the converter. Note that the specific configuration of the control integrated circuit K1 is not limited to the above-described IC chip, and it is sufficient that a similar function can be realized by using another IC chip or a discrete circuit.

  First, one end of the tertiary winding N3 of the transformer N1 is connected to the low-voltage output path of the rectifying / smoothing circuit 3 via a series circuit of a diode D3 and resistors R4 and R5, and the other end of the tertiary winding N3 is The rectifying / smoothing circuit 3 is directly connected to the low-voltage output path. The tertiary winding N3 is configured to have the same polarity as the secondary winding N2, and a voltage corresponding to the slope of the secondary current I2 flowing through the secondary winding N2 is present between both ends of the tertiary winding N3. appear. Accordingly, the switching element Q1 is switched from the on state to the off state, and the secondary current I2 that decreases with a substantially constant gradient flows from the secondary winding N2 in which the induced voltage is generated. A voltage is generated between them. That is, the tertiary winding N3 is a winding for detecting the secondary current I2 flowing in the secondary winding N2, and the voltage generated in the tertiary winding N3 becomes a detection signal of the secondary current I2. The feedback control described later is performed.

  One end of the tertiary winding N3 is connected to the fifth pin P5 via the resistor R11, and the fifth pin P5 functions as a zero cross detection terminal for detecting the zero cross timing of the secondary current I2. To do.

  Further, the output voltage Vo (the voltage across the capacitor C5) is N × when the forward voltage Vf of the LED element 71 and the number of LED elements 71 constituting the LED unit 7 connected in series (the number of serial connections) N are N × Vf. Therefore, the greater the number of LED elements 71 connected in series, the higher the output voltage Vo and the higher the voltage across the tertiary winding N3.

  Therefore, the voltage across the tertiary winding N3 is divided by the resistors R4 and R5 via the diode D3, and the voltage across the resistor R5 is used as a detection signal for the output voltage Vo. Then, the detection signal of the output voltage Vo by the resistor R5 is connected to the third pin P3 via the resistor R6, and feedback control described later is performed. A parallel circuit of a resistor R7 and a capacitor C6 is connected between the third pin P3 and the low-voltage output path of the rectifying / smoothing circuit 3. Further, the third pin P3 is also connected to the control voltage Vcc via the resistor R10.

  A detection signal of the primary current I1 from the resistor R1 is input to the fourth pin P4 via the resistor R12, and feedback control described later is performed. That is, the fourth pin P4 has a function as a chopper current detection terminal.

  The control voltage Vcc is divided by a series circuit of resistors R8 and R9, and the voltage across the resistor R9 is input to the first pin P1.

  The seventh pin P7 has a function as a gate drive terminal of the switching element Q1, and is connected to the gate of the switching element Q1 via a parallel circuit of a series circuit of a diode D4 and a resistor R13 and a resistor R14. . The series circuit of the diode D4 and the resistor R13 is a discharge path when extracting the gate charge, and the resistor R14 is a charging path when charging the gate charge. Furthermore, the gate of the switching element Q1 is connected to the low voltage output path of the rectifying / smoothing circuit 3 via the resistor R15.

  The 6th pin P6 and the 8th pin P8 each have a function as a power supply terminal and a GND terminal, the 8th pin P8 is connected to the control voltage Vcc, and the 6th pin P6 is a low voltage output of the rectifying and smoothing circuit 3 It is connected to the route (GND).

  Note that the second pin P2 is not connected anywhere in the present embodiment.

  The control integrated circuit K1 operates as follows.

  First, the 8th pin P8 connected to the control voltage Vcc is connected to the control power supply 106. The control power supply 106 generates the reference voltages Vr1 and Vr2 if the control voltage Vcc exceeds a predetermined voltage at the time of start-up. Each circuit in the integrated circuit K1 can be operated. The reference voltage Vr1 is connected to the non-inverting input of the error amplifier 107, and the reference voltage Vr2 is connected to the non-inverting input terminal of the comparator 102.

  At startup, the starter 101 outputs a start pulse to the OR element 103, and the OR element 103 outputs a high level signal (hereinafter referred to as an H level signal). The output of the OR element 103 is connected to the S terminal (set terminal) of the RS flip-flop 104, and the RS flip-flop 104 that receives the H level signal from the OR element 103 to the S terminal receives the H level signal as the Q terminal. To the drive circuit 105.

  The drive circuit 105 has a function of outputting a drive signal for driving the gate of the switching element Q1 in accordance with the output of the RS flip-flop 104. When the output of the RS flip-flop 104 is an H level signal, the drive circuit 105 drives a positive voltage. The signal is output to the seventh pin P7. The seventh pin P7 is connected to the gate of the switching element Q1 through the resistor R14, and the positive drive signal is divided by the resistors R15 and R14 and applied between the gate and the source of the switching element Q1. The The switching element Q1 to which the positive drive signal is applied to the gate is turned on so that the drain and the source are conductive, and the primary current I1 is supplied from the rectifying and smoothing circuit 3 to the primary winding N1.

  The primary current I1 flows along the path of the rectifying / smoothing circuit 3 → the primary winding N1 → the switching element Q1 → the resistor R1 → the rectifying / smoothing circuit 3, and the detection signal of the primary current I1 by the resistor R1 is applied to the fourth pin P4. Have been entered.

  The fourth pin P4 is connected to the non-inverting input terminal of the comparator 109 via a filter circuit composed of a series circuit of a resistor R101 and a capacitor C101. The non-inverting input terminal of the comparator 109 is connected to the primary current I1. A detection signal is input. For example, the resistor R101 is set to 40 kΩ, and the capacitor C101 is set to 5 pF.

  Further, the error amplifier 107 amplifies the difference between the resistance divided value of the control voltage Vcc input to the first pin P1 and the reference voltage Vr1 output from the control power supply 106 and outputs the amplified difference to the multiplication circuit 108. The multiplication circuit 108 multiplies the output of the error amplifier 107 and the detection signal of the output voltage Vo input to the third pin P3, and outputs the multiplication result to the inverting input terminal of the comparator 109. This multiplication result becomes a threshold value used when the comparator 109 described later determines the turn-off timing of the switching element Q1, and this threshold value is a value corresponding to the output voltage Vo (the number N of LED elements 71 connected in series). Therefore, the on-time of the switching element Q1 can be feedback controlled to a time corresponding to the output voltage Vo (the number N of LED elements 71 connected in series), and constant current control is possible regardless of the number N of LED elements 71 connected in series. Become.

  The comparator 109 compares the output of the multiplication circuit 108 input to the inverting input terminal with the detection signal of the primary current I1 input to the non-inverting input terminal, using the output as a threshold value. The comparator 109 outputs an H level signal when the detection signal of the primary current I1 exceeds the threshold value. The output of the comparator 109 is connected to the R terminal (reset terminal) of the RS flip-flop 104, and the RS flip-flop 104 that receives the H level signal from the comparator 109 to the R terminal receives the low level signal (hereinafter referred to as L level). A level signal) is output from the Q terminal to the drive circuit 105. The L level signal output from the RS flip-flop 104 is a signal for turning off the switching element Q1, and the on-time (turn-off timing) of the switching element Q1 is feedback controlled using the detection signal of the primary current I1.

  When the output of the RS flip-flop 104 is an L level signal, the drive circuit 105 outputs a negative voltage (or zero voltage) drive signal to the seventh pin P7. The seventh pin P7 is connected to the gate of the switching element Q1 via the resistor R13 and the diode D4. Due to the negative voltage drive signal, the charge between the gate and source of the switching element Q1 causes the resistor R13 and the diode D4 to be connected. Pulled through. The switching element Q1 to which the negative voltage drive signal is applied to the gate is turned off with the drain-source cut off, and an induced voltage is generated in the secondary winding N2 by the magnetic energy accumulated in the transformer T1. . Then, a secondary current I2 that decreases with a substantially constant slope flows, and the capacitor C5 is charged.

  While the secondary current I2 is flowing, a voltage is generated across the tertiary winding N3, and the voltage generated in the tertiary winding N3 is the fifth pin P5 as a detection signal of the secondary current I2. Is input. The zero cross timing of the secondary current I2 is detected by the comparator 102 having the inverting input terminal connected to the fifth pin P5 and the non-inverting input terminal connected to the reference voltage Vr2. When the detection signal of the secondary current I2 becomes equal to or lower than the reference voltage Vr2, the comparator 102 outputs an H level signal to the OR element 103, and the output of the OR element 103 also becomes an H level signal.

  The output of the OR element 103 is connected to the S terminal (set terminal) of the RS flip-flop 104, and the RS flip-flop 104 that receives the H level signal from the OR element 103 to the S terminal receives the H level signal as the Q terminal. To the drive circuit 105. The H level signal output from the RS flip-flop 104 is a signal for turning on the switching element Q1, and the OFF time (turn-on timing) of the switching element Q1 is feedback controlled using the detection signal of the secondary current I2.

  When the output of the RS flip-flop 104 is at the H level, the drive circuit 105 outputs a positive voltage drive signal to the seventh pin P7. The switching element Q1, to which a positive drive signal is applied to the gate via the seventh pin P7, is turned on so that the drain-source is conductive, and the primary current I1 flows from the rectifying / smoothing circuit 3 to the primary winding N1. Is supplied.

  Thereafter, the above operation is repeated to turn on / off the switching element Q1, and an output voltage Vo obtained by stepping down the DC voltage output from the rectifying and smoothing circuit 3 is generated between the capacitors C5 and supplied to the LED unit 7. The LED current Io is constant current controlled.

  In addition to the LED element 71, a semiconductor light emitting element such as an organic EL element or a semiconductor laser element may be used as a light source.

  In the present embodiment, as described above, the detection signal of the secondary current I2 is fed back using the tertiary winding N3 of the transformer T1, and the switching element Q1 on the primary side of the transformer T1 is controlled to be turned on / off. Yes. Therefore, a resistor for detecting the secondary current I2 becomes unnecessary, and the conversion efficiency of the circuit is improved. Further, an insulating photocoupler used for feeding back the detection signal of the secondary current I2 becomes unnecessary, and the cost of the apparatus can be reduced.

  Further, the configuration for feeding back the detection signal of the output voltage Vo similarly uses the tertiary winding N3 of the transformer T1, thereby improving the conversion efficiency of the circuit and reducing the cost of the apparatus.

  In this manner, a lighting device is realized that can supply current to the semiconductor light emitting element using an insulating transformer and can improve conversion efficiency and reduce costs in feedback control.

  FIG. 3 shows the LED current Io-output voltage Vo characteristics when the load of the LED unit 7 is varied. A curve Y1 shows the LED current Io-output voltage Vo characteristic when the number N of LED elements 71 connected in series is gradually increased from the start point P1 to the end point P2. In this case, the constant current control for controlling the LED current Io to approximately 300 mA is possible in the section W1 having a load resistance value of 100Ω to 400Ω.

  In the present embodiment, as described above, the on-time of the switching element Q1 is feedback-controlled to a time corresponding to the output voltage Vo (the number N of LED elements 71 connected in series). Therefore, constant current control for controlling the effective value of the LED current Io to be substantially constant is possible regardless of the number N of LED elements 71 connected in series.

  In this embodiment, the voltage of the tertiary winding N3 is used to detect the zero cross timing of the secondary current I2. However, the zero cross timing of the secondary current I2 may be detected by another method. . For example, a method of detecting an increase in the reverse voltage of the diode D1 or a method of detecting a decrease in the voltage across the switching element Q1 may be used, and the method of detecting the zero-cross timing of the secondary current I2 is not limited.

  Further, in the internal configuration of the control integrated circuit K1 shown in FIG. 2, the DISABLE unit 110 omits the drive circuit 105 when the applied voltage (the detection signal of the secondary current I2) of the fifth pin P5 is a predetermined value or more. It has a function to operate power. That is, power saving of the control integrated circuit K1 is achieved.

(Embodiment 2)
FIG. 4 shows the configuration of the lighting device 1 of the present embodiment. The lighting device 1 is provided with a no-load detection circuit 8 and a short-circuit detection circuit 9 in the configuration of the first embodiment, and further a capacitor C13 in the resistor R9. Connected in parallel. In addition, the same code | symbol is attached | subjected to the structure similar to Embodiment 1, and description is abbreviate | omitted.

  In the no-load detection circuit 8, a series circuit of a Zener diode ZD2, a diode D5, and a resistor R16 is connected between both ends of the tertiary winding N3, and a capacitor C8 is connected in parallel to the resistor R16. Further, a series circuit of resistors R17 and R18 is connected in parallel to the resistor R16, and a connection point of the resistors R17 and R18 is connected to the base of the transistor Q2. The collector of the transistor Q2 is connected to the control voltage Vcc via the resistor R19, and the emitter of the transistor Q2 is connected to the low voltage output path of the rectifying and smoothing circuit 3. Further, the base of the transistor Q3 is connected to the collector of the transistor Q2, the collector of the transistor Q3 is connected to the control voltage Vcc via the resistor R20, and the emitter of the transistor Q3 is connected to the low voltage output path of the rectifying and smoothing circuit 3. ing. The collector of the transistor Q3 is connected to the first pin P1 of the control integrated circuit K1 via the diode D6.

  When the LED unit 7 is in a no-load state, the voltage across the tertiary winding N3 increases. In the no-load detection circuit 8, the Zener diode ZD2 is turned on, the transistor Q2 is turned on, the transistor Q3 is turned off, and the control voltage Vcc is applied to the first pin P1 of the control integrated circuit K1. In the control integrated circuit K1 in which the control voltage Vcc is applied to the first pin P1, the drive signal of the switching element Q1 output from the seventh pin P7 becomes a negative voltage, and the switching element Q1 maintains the off state.

  Therefore, when the LED unit 7 is in a no-load state, the converter unit 4 stops operating, and the LED current Io supplied to the LED unit 7 is reduced to zero (or the LED current Io is reduced). Can be secured.

  Next, the short circuit detection circuit 9 connects a series circuit of a diode D7 and resistors R21 and R22 between both ends of the tertiary winding N3, and a capacitor C9 is connected in parallel to the resistor R22. Further, a series circuit of resistors R23 and R24 is connected in parallel to the capacitor C9, and a connection point of the resistors R23 and R24 is connected to the base of the transistor Q4. The collector of the transistor Q4 is connected to the control voltage Vcc via the resistor R25, and the emitter of the transistor Q4 is connected to the low voltage output path of the rectifying and smoothing circuit 3. The collector of the transistor Q4 is connected to the first pin P1 of the control integrated circuit K1 via the diode D8.

  When the LED unit 7 is short-circuited, the voltage across the tertiary winding N3 becomes almost zero. In the short circuit detection circuit 9, the transistor Q4 is turned off, and the control voltage Vcc is applied to the first pin P1 of the control integrated circuit K1. In the control integrated circuit K1 in which the control voltage Vcc is applied to the first pin P1, the drive signal of the switching element Q1 output from the seventh pin P7 becomes a negative voltage, and the switching element Q1 maintains the off state.

  Therefore, when the LED unit 7 is short-circuited, the converter unit 4 stops its operation, and the LED current Io supplied to the LED unit 7 is reduced to zero (or the LED current Io is reduced). It can be secured.

  When the no-load state or the short-circuit state of the LED unit 7 is resolved, the charging voltage of the capacitor C13 is applied to the first pin P1 of the control integrated circuit K1, and the switching element Q1 of the control integrated circuit K1 On / off control is resumed.

  In the control power supply circuit 6 of this embodiment, a series circuit of a transistor Q5 and a choke coil L1 is provided between the positive electrode of the capacitor C3 and the eighth pin P8 of the control integrated circuit K1. Furthermore, the transistor Q5 and the drive circuit K2 that drives the transistor Q5 are configured by an IPD (Intelligent Power Device). A series circuit of a Zener diode ZD3 and a diode D11 is connected between the input of the drive circuit K2 and the eighth pin P8, and a capacitor C10 is connected between the input of the drive circuit K2 and the emitter of the transistor Q5. , C11 parallel circuit is connected. Further, a diode D10 is connected in parallel to the capacitor C12 via the transistor Q5. The transistor Q5 is driven and controlled so that the control voltage Vcc becomes the Zener voltage of the Zener diode ZD3.

(Embodiment 3)
FIG. 5 shows a configuration of the lighting device 1 according to the present embodiment. The same reference numerals are given to the same configurations as those in the first embodiment, and the description thereof will be omitted.

  First, in the present embodiment, the tertiary winding N3 is used as the input of the control power supply circuit 6, and the diode D12 and the resistor R26 are provided between one end of the tertiary winding N3 and the Zener diode ZD1 of the control power supply circuit 6. A series circuit is provided. Therefore, the tertiary winding N3 can be used not only for the feedback of the detection signal of the secondary current I2 and the detection signal of the output voltage Vo, but also for the generation of the control power supply Vcc, thereby simplifying the configuration of the apparatus. , Loss can be reduced.

  In the first to third embodiments, the rectifying / smoothing circuit 3 is used as a DC power supply. However, as shown in FIG. 6, a power factor correction circuit 10 including a full-wave rectifier DB1 and a boost chopper circuit 11 is provided. It may be used as a DC power source. In this case, the power supply winding magnetically coupled to the choke coil used in the boost chopper circuit 11 may be used as the input of the control power supply circuit 6.

(Embodiment 4)
FIG. 7 is a schematic configuration diagram showing an external appearance of the lighting apparatus of the present embodiment. This lighting fixture comprises the lighting device 1 and the LED unit 7 as separate bodies.

  The LED unit 7 houses a substrate 72 mounted with an LED element 71 in a housing 73 formed in a metal cylinder having an opening on one side, and a light diffusing plate 74 covers the opening of the housing 73. Has been. The light emitted from the LED element 71 is diffused and transmitted through the light diffusion plate 74 and irradiated to the outside. The LED unit 7 is embedded in the ceiling panel 400, and the light diffusion plate 74 is exposed downward from the surface of the ceiling panel 400.

  The lighting device 1 is disposed on the back surface of the ceiling panel 400, the output of the converter unit 4 is connected to the LED unit 7 via the lead wire 300 and the connector 301, and the LED current Io is supplied to the LED unit 7. The connector 301 is configured such that the connector 301a on the lighting device 1 side and the connector 301b on the LED unit 7 side are detachable, and the lighting device 1 and the LED unit 7 can be separated during maintenance or the like.

  The circuit configuration of the lighting device 1 is configured in the same manner as in any one of the first to third embodiments. Even in such a lighting apparatus, current is supplied to the semiconductor light emitting element using an insulating transformer, and feedback control is performed. It is possible to improve the conversion efficiency and reduce the cost.

  Moreover, you may accommodate the lighting device 1 and the LED unit 7 in the same housing | casing.

  Further, the lighting device 1 may be used not only for lighting equipment but also for the purpose of lighting a light source such as a backlight of a liquid crystal display, a copying machine, a scanner, or a projector.

1 Lighting device 3 Rectification smoothing circuit (DC power supply)
4 Converter section 5 Control section 7 LED unit T1 transformer N1 primary winding N2 secondary winding N3 tertiary winding Q1 switching element

Claims (7)

A semiconductor light emitting device having a primary winding, a secondary winding, and a tertiary winding that are magnetically coupled to each other, and a DC power source is connected between both ends of the primary winding, and between both ends of the secondary winding A transformer connected to the
A switching element for conducting / interrupting the current supplied to the primary winding;
A controller that controls on / off operation of the switching element based on an output of the tertiary winding and controls a current supplied from the secondary winding to the semiconductor light emitting element. apparatus. A detection circuit that detects at least one of a short circuit state and a no-load state of the semiconductor light emitting element based on the output of the tertiary winding;
2. The lighting device according to claim 1, wherein the control unit reduces a current supplied to the semiconductor light emitting element when the detection circuit detects a short circuit state or a no-load state of the semiconductor light emitting element.   The lighting device according to claim 1, wherein the control unit uses an output of the tertiary winding as a power source.   The control unit detects a current flowing through the secondary winding based on the output of the tertiary winding, and turns on the switching element when the current flowing through the secondary winding becomes a predetermined value or less. The lighting device according to any one of claims 1 to 3, wherein:   The lighting device according to claim 1, wherein the transformer and the switching element constitute a flyback converter.   6. The lighting device according to claim 1, wherein the secondary winding and the tertiary winding are configured to have the same polarity. A semiconductor light emitting device having a primary winding, a secondary winding, and a tertiary winding that are magnetically coupled to each other, and a DC power source is connected between both ends of the primary winding, and between both ends of the secondary winding A transformer connected, a switching element for conducting / interrupting current supplied to the primary winding, an on / off operation of the switching element based on an output of the tertiary winding, and the secondary winding A lighting device comprising a control unit for controlling a current supplied from the semiconductor light emitting device to the semiconductor light emitting device;
A lighting device comprising: a semiconductor light emitting element connected between both ends of the secondary winding and supplied with a current from the secondary winding of the lighting device.

Images