JP2005183291A - Discharge lamp lighting apparatus and lighting equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting apparatus and lighting equipment achieving lower cost by preventing the destruction the apparatus at the time of a light load, in the termination of a service life of a lamp and in the rise of a power source voltage and also by adoption a low breakdown voltage. <P>SOLUTION: An inverter control circuit 2 is provided with a feed back control circuit FB, and a bottom voltage smoothed by a capacitor Ca is detected by a bottom voltage detecting signal S1. Then, driving signals SH and SL with variable operating frequencies according to the trough voltage Vdc2 are outputted, and feed back control is carried out by driving switching elements Q1 and Q2 on and off in an inverter INV by the feed back control circuit FB. At this time, when the trough voltage Vdc2 is higher, control is carried out by increasing a test frequency so that the trough voltage Vdc2 is decreased. When the trough voltage Vdc2 is low, control is carried out decreasing the test frequency so that the trough voltage Vdc2 is increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device that converts a DC power source obtained by rectifying and smoothing an AC power source into an AC output by turning on and off a switching element, and a lighting fixture.

  2. Description of the Related Art Conventionally, there is an inverter device used in a discharge lamp lighting device having a circuit configuration shown in FIG. 8, and this circuit performs full-wave rectification of an AC power supply AC with a rectifier circuit RE such as a diode bridge, and the rectifier circuit RE. The DC output voltage of the inverter circuit INV is converted into a high-frequency AC output and supplied to a lamp load L such as a discharge lamp, and the valley buried circuit 1 is provided on the rear side of the inverter circuit INV. Yes.

  More specifically, the inverter circuit INV includes an impedance element Z (capacitor, inductor, resistor) in which a series circuit of a positive switching element Q1 and a negative switching element Q2 is connected to the positive output of the rectifier circuit RE. Or any combination thereof) is connected between the DC output terminals of the rectifier circuit RE, and further between the DC output terminals of the rectifier circuit RE is a series resonance composed of capacitors C2 and C3 and an inductor L1. A series circuit of the circuit and the switching element Q2 is connected, and the lamp load L is connected in parallel to the capacitor C2.

  In the valley buried circuit 1, a smoothing capacitor Ca for valley filling (hereinafter simply referred to as a capacitor) is connected to the anode side of a diode Da having a cathode connected to the connection point between the switching element Q1 and the impedance element Z via an inductor La. A series circuit, a series circuit in which a valley filling smoothing capacitor Cb (hereinafter simply referred to as a capacitor) is connected to the cathode side of a diode Dc having an anode connected to the negative output of the rectifier circuit RE via an inductor Lb, and a capacitor Cc Are connected in parallel to the series circuit of both switching elements Q1 and Q2 of the inverter circuit INV, and the cathode of the diode Db having the anode connected to the connection point of the switching elements Q1 and Q2 is connected to the connection point of the diode Da and the inductor La. Die with cathode connected to connection point of switching elements Q1 and Q2 It has a configuration in which its anode connected to the over-de Dd to the connection point between the diode Dc and the inductor Lb. The capacitors Ca and Cb are electrolytic capacitors and have a sufficiently large capacity compared to the capacitor Cc. Although it is assumed that MOSFETs are used for the switching elements Q1, Q2, it is also possible to use bipolar transistors or the like in which diodes are connected in antiparallel.

  Both switching elements Q1 and Q2 are alternately turned on and off at a high frequency by an appropriate control circuit (not shown). Therefore, when the switching element Q2 is turned on, a resonant current flows from the rectifier circuit RE or the valley buried circuit 1 to the capacitor C3, the lamp load L and the capacitor C2, the inductor L1, and the switching element Q2, and when the switching element Q1 is turned on, the capacitor C3. Is discharged, and a resonance current flows through the path of the impedance element Z, the switching element Q1, the inductor L1, the lamp load L, the capacitor C2, and the capacitor C3.

  Here, in the valley buried circuit 1, when the switching element Q1 is on, the capacitor Ca is charged via the diode Db and the inductor La. When the switching element Q2 is on, the capacitor Cb is charged via the inductor Lb and the diode Dd. Charged. When the lamp is normally lit, the voltage Vdc (= the voltage across the series circuit of the switching elements Q1 and Q2) that is the output of the valley buried circuit 1 is the rectified voltage Vre (the AC power supply AC) as shown in FIG. The peak voltage Vdc1 having the same waveform as the peak of the DC output of the rectifier circuit RE and the valley voltage Vdc2 equal to the voltage smoothed by the capacitors Ca and Cb are alternately repeated. In other words, since the rectified voltage Vre is high at the peak and low at the valley, if only the valley buried circuit 1 is used as the power source of the inverter circuit INV, the supply current from the inverter circuit INV to the lamp load L is equal to the rectified voltage Vre. It changes so as to be large at the mountain and small at the valley. Next, assuming that only the input from the AC power source AC is used as the power source of the inverter circuit INV, the resonance condition in the inverter circuit INV changes according to the change in the rectified voltage Vre, and the lamp load L is changed by the change in the rectified voltage Vre. The change in the supply current changes so that the supply current to the lamp load L decreases during the period when the rectified voltage Vre is high, and the supply current to the lamp load L increases during the period when the rectification voltage Vre is low. That is, the peak value of the current waveform can be lowered by using the valley buried circuit 1 in which the change pattern of the supply current to the lamp load L with respect to the change of the rectified voltage Vre is opposite to the input from the AC power supply AC. As a result, the current waveform of the supply current from the inverter circuit INV to the lamp load L has a peak at the peak and valley of the rectified voltage Vre, and the fluctuation of the load current is reduced. .

  Furthermore, in the valley buried circuit 1, since the charging currents of the smoothing capacitors Ca and Cb are supplied to both the switching elements Q1 and Q2, the stress on the switching elements Q1 and Q2 can be reduced. Further, when the switching elements Q1 and Q2 are frequency controlled and duty controlled, the charging currents to the capacitors Ca and Cb as seen from the input side are almost constant, so that the fluctuation of the load current can be reduced and the input current distortion is reduced. Deterioration can be reduced. In other words, the control range can be widened. In addition, when the power is turned on (until the inverter circuit INV operates), the smoothing capacitors Ca, Cb are also used for boosting the voltage Vdc across the switching elements Q1, Q2 by the inductance component of the AC power supply AC and the small-capacitance capacitor Cc. Are connected in series via the diodes Dd and Db, so that the boosting of the voltage Vdc is suppressed.

  Further, as another circuit configuration, there is a circuit in which the impedance element Z in the circuit of FIG. 8 is replaced with a diode and connected in the forward direction from the rectifier circuit RE to the valley buried circuit 1. In this circuit configuration, the peak of the rectified voltage Vre is When the switching element Q2 is turned on, a current flows through a path passing through the capacitor C3. However, this current does not flow in the valley portion, and eventually the resonance condition in the inverter circuit INV changes according to the change in the rectified voltage Vre. Therefore, the supply current to the lamp load L due to the change of the rectified voltage Vre changes so that the current decreases during the period when the rectified voltage Vre is high and increases during the period when the rectified voltage Vre is low. Thus, similarly to the conventional example of FIG. 8, the valley filling circuit 1 is provided in which the change pattern of the supply current to the lamp load L with respect to the change of the rectified voltage Vre is opposite to the input from the AC power supply AC. The fluctuation of the supply current to the lamp load L can be reduced, and the stress of the switching elements Q1 and Q2 can be reduced. Another circuit configuration uses a half-bridge type inverter circuit INV. (For example, refer to Patent Document 1).

  Further, FIG. 9 shows a circuit configuration of a discharge lamp lighting device having a plurality of lamp loads L, a diode D17 having a cathode connected to the negative output of the rectifier circuit RE, a cathode connected to the anode of the diode D17, Impedance element Z composed of a diode D18 whose anode is connected to the negative electrode side of valley buried circuit 1 and capacitor C22 connected in parallel to diode D18, a connection point between diodes D17 and D18, and a connection point between switching elements Q1 and Q2 A plurality of load resonance circuits K including a lamp load L are connected in parallel to each other, and each load resonance circuit K includes a series circuit of capacitors C2, C3 and an inductor L1, and a lamp load L connected in parallel to the capacitor C2. It consists of. Further, the valley buried circuit 1 deletes the inductors La and Lb of FIG. 8 and replaces them with an inductor Lab interposed between the connection points of the switching elements Q1 and Q2 and the connection points of the diodes Db and Dd.

Moreover, what mounted the said discharge lamp lighting device is provided in the lighting fixture.
JP-A-9-260077 (paragraph numbers [0017] to [0026], FIGS. 1 to 6)

  In the above conventional discharge lamp lighting device, an input current distortion improving circuit and a high-frequency power supply circuit to a load are used together. In the configuration of FIG. 8, the switching element Q1, the diode Db, the inductor La, and the switching element Q2, the diode Depending on the balance of power consumption between the output of the chopper circuit composed of Dd and inductor Lb and the inverter circuit composed of switching elements Q1, Q2, inductor L1, capacitor C2, DC cut capacitor C3, impedance element Z, The state of the voltage Vdc that is the output of the circuit 1 changes. The voltage Vdc when the lamp is normally lit (see FIG. 2A) is a valley equal to the peak voltage Vdc1 having the same waveform as the peak of the rectified voltage Vre of the AC power supply AC and the voltage smoothed by the capacitors Ca and Cb. It becomes a waveform which repeats the partial voltage Vdc2 alternately. On the other hand, the lamp is normal during filament preheating and no load (when all the lamp loads L are removed), which is performed to extend the life of the lamp from when it is started until the lamp load L is lit. The voltage Vdc at the light load and at the end of the lamp life (see the two-dot chain line in FIG. 2B) is higher than the peak value of the rectified voltage Vre, and the peak voltage Vdc1 and the valley voltage. The difference from Vdc2 becomes small, and the voltage is boosted to a voltage higher than the voltage Vdc when the lamp is normally lit, and the electronic components (for example, capacitors Ca and Cb, switching element Q1) constituting the discharge lamp lighting device , Q2, etc.) may exceed the allowable value, leading to destruction. In addition, if a high withstand voltage is used for each electronic component in order to prevent destruction, the cost increases. Further, at the end of the lamp life, when there is no discharge between the filaments at both ends of the lamp load L, the preheating current continues to flow through the filament, and the voltage Vdc boosting operation is continued.

  Furthermore, in the circuit in which the circuit for improving the input current distortion and the high-frequency power supply circuit to the load are combined as described above, the influence of the power supply voltage fluctuation of the AC power supply AC on the voltage Vdc becomes large, as shown in FIG. In the voltage Vdc waveform when the lamp is normally lit, the peak of the rectified voltage Vre of the AC power supply AC has the same waveform as the peak voltage Vdc1 of the voltage Vdc, and the power supply voltage directly affects the voltage Vdc. That is, if the power supply voltage increases, the voltage Vdc also increases. Therefore, when the power supply voltage of the AC power supply AC increases, the voltage Vdc may further increase together with the boosting operation.

  Further, the resonance curves Y1, Y2, and Y3 when the lamp is turned on shown in FIG. 10 show the respective resonance curves when the power supply voltage of the AC power supply AC is rated, rated x 0.9, and rated x 0.8. In the case where the lighting operation is continued when the power supply voltage of the AC power supply AC is greatly reduced, the resonance curve moves to the higher frequency side as the power supply voltage is greatly reduced, and the in-phase frequencies f01, f02, f03 also moves to the higher frequency side as the power supply voltage decreases, and f01 <f02 <finv <f03 with respect to the operating frequency finv of the inverter circuit INV. When the operating frequency finv of the inverter circuit INV is lower than the in-phase frequency, the phase is advanced, and when it is higher than the in-phase frequency, the phase is retarded. Excessive stress will occur in Q2. If the operation time in the phase advance region becomes long, the lighting device may be destroyed due to thermal destruction of the switching elements Q1 and Q2.

  The present invention has been made in view of the above-mentioned reasons, and its object is to prevent the destruction of the device at the time of light load, at the end of the lamp life, and at the time of increasing the power supply voltage, and to reduce the cost by adopting low-voltage components. It is providing the discharge lamp lighting device which can aim at, and a lighting fixture.

  A discharge lamp lighting device comprising: a rectifier circuit for rectifying an AC power source; and an inverter circuit connected to an output terminal of the rectifier circuit for converting the DC power source into a high frequency output and supplying the output to a lamp load. The circuit includes first and second switching elements connected in series and alternately turned on and off, an impedance element interposed between the DC output terminals of the rectifier circuit and the series circuit of both switching elements, A series circuit including a capacitor and an inductor and having an impedance element is connected between both ends of at least one of the switching elements and includes a resonance circuit that extracts an output to the lamp load. The series circuit of the second rectifying element is connected in reverse parallel, and the connection point between the first and second rectifying elements and the second switching element are connected. A series circuit of a first inductor and a first smoothing capacitor is connected between a terminal opposite to the connection point with the first switching element, and third and fourth terminals are connected to both ends of the second switching element. The series circuit of the rectifying elements is connected in reverse parallel, and the second rectifying element is connected between the connection point of the third and fourth rectifying elements and the terminal opposite to the connection point of the second switching element in the first switching element. A valley buried circuit in which a series circuit of two inductors and a second smoothing capacitor are connected, and the first and second switching elements according to a change in voltage smoothed by at least one of the first and second smoothing capacitors And a control circuit that suppresses the boosting of the voltage across the series circuit of the first and second switching elements by changing the operating frequency.

  According to the present invention, it is possible to prevent the apparatus from being destroyed at the time of light load, at the end of the lamp life, and at the time of increasing the power supply voltage, and to reduce the cost by adopting the low-voltage component.

  According to a second aspect of the present invention, there is provided a discharge lamp lighting device comprising: a rectifier circuit that rectifies an AC power source; and an inverter circuit that is connected to an output terminal of the rectifier circuit and converts the DC power source into a high-frequency output and supplies the output to a lamp load. The circuit includes first and second switching elements connected in series and alternately turned on and off, and a diode interposed between a DC output terminal of the rectifier circuit and a series circuit of both switching elements in a forward direction. And a resonance circuit for taking out the output to the lamp load while connecting a series circuit of a diode including a capacitor and an inductor to at least one of the switching elements, and a first circuit at both ends of the first switching element. And a series circuit of the second rectifying elements are connected in reverse parallel, and the connection point between the first and second rectifying elements and the first switching element in the second switching element. A series circuit of a first inductor and a first smoothing capacitor is connected between a terminal opposite to the connection point with the switching element, and the third and fourth rectifying elements are connected to both ends of the second switching element. A series circuit is connected in antiparallel, and a second inductor is connected between a connection point of the third and fourth rectifying elements and a terminal of the first switching element opposite to the connection point of the second switching element. The operating frequency of the first and second switching elements is set according to the fluctuation of the voltage smoothed by at least one of the first and second smoothing capacitors, and the valley buried circuit connecting the series circuit of the second smoothing capacitors. And a control circuit that changes the voltage across the series circuit of the first and second switching elements to suppress the voltage boost.

  According to the present invention, it is possible to prevent the apparatus from being destroyed at the time of light load, at the end of the lamp life, and at the time of increasing the power supply voltage, and to reduce the cost by adopting the low-voltage component.

  According to a third aspect of the present invention, there is provided a discharge lamp lighting device comprising: a rectifier circuit that rectifies an AC power source; and an inverter circuit that is connected to an output terminal of the rectifier circuit and converts the DC power source into a high frequency output and supplies the output to a lamp load. The circuit includes first and second switching elements connected in series and alternately turned on and off, a capacitor and an inductor, and is connected between both ends of at least one switching element and extracts an output to a lamp load. A half-bridge circuit including a resonant circuit, wherein a series circuit of first and second rectifying elements is connected in antiparallel to both ends of a first switching element, and a connection point of the first and second rectifying elements Between the first switching element and the first switching element in the second switching element and the terminal opposite to the connection point of the first switching element. A series circuit of the first and second switching elements, a series circuit of third and fourth rectifying elements connected in antiparallel to both ends of the second switching element, and a connection point between the third and fourth rectifying elements and the first switching element A valley buried circuit in which a series circuit of a second inductor and a second smoothing capacitor is connected between a terminal opposite to the connection point with the second switching element in the first and second smoothing capacitors; A control circuit that changes the operating frequency of the first and second switching elements in accordance with a change in voltage smoothed by at least one of them, and suppresses boosting of the voltage across the series circuit of the first and second switching elements; It is characterized by providing.

  According to the present invention, it is possible to prevent the apparatus from being destroyed at the time of light load, at the end of the lamp life, and at the time of increasing the power supply voltage, and to reduce the cost by adopting the low-voltage component.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the connection point between the first and second switching elements, the series circuit of the first and second rectifying elements, and the third and fourth rectifying elements. A third inductor is interposed between the connection point of the series circuit and all or part of the first and second inductors are replaced by the third inductor.

  According to the present invention, the first and second inductors can be replaced with one inductor, or each inductor can be reduced in size.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the apparatus further comprises means for detecting an end-of-life condition of the lamp load and means for stopping the operation of the inverter circuit when the end-of-life condition of the lamp load is detected. And

  According to the present invention, it is possible to prevent heat stress by preventing heat generation of the lamp filament, which is a concern when the preheating current continues to flow through the filament at the end of the life of the lamp load.

  The invention of claim 6 is characterized in that, in claim 5, it comprises means for detecting a no-load condition, means for stopping the operation of the inverter circuit when no-load condition is detected, or means for intermittently operating the inverter circuit. .

  According to the present invention, unnecessary power consumption during no load can be reduced.

  According to a seventh aspect of the present invention, in any one of the first to fourth aspects, the inverter circuit is protected when the voltage smoothed by the first and second smoothing capacitors exceeds a predetermined voltage. .

  According to the present invention, the protective operation of the inverter circuit is performed against the abnormal boosting that occurs when the load is abnormal or when the component is broken, and the destruction of the discharge lamp lighting device is prevented.

  According to an eighth aspect of the present invention, in any one of the first to fourth aspects, the plurality of resonance circuits are connected in parallel to each other, and each of the plurality of lamp loads for extracting an output from each resonance circuit is provided, and an end-of-life state of each lamp load is detected. And means for stopping the operation of the inverter circuit when detecting the end-of-life state of any one or more lamp loads.

  According to the present invention, when even one of the plurality of lamp loads is in the end of life state, the heat generation of the lamp filament, which is a concern due to the preheating current continuing to flow through the filament, is prevented, and thermal stress is avoided. be able to.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the means for stopping the operation of the inverter circuit or the inverter circuit when the voltage of the AC power supply drops below the voltage at which the inverter circuit operates in the phase advance region is intermittently provided. Means for operating is provided.

  According to the present invention, it is possible to avoid the stress generated in the inverter circuit during the operation in the phase advance region of the inverter circuit due to the voltage drop of the AC power supply, and it is possible to improve the reliability.

  The invention of claim 10 is characterized in that the discharge lamp lighting device according to any one of claims 1 to 9 is mounted.

  According to this invention, there exists an effect similar to any one of Claims 1 thru | or 9.

  As described above, the present invention includes a control circuit that performs feedback control that suppresses voltage boost in the inverter circuit by changing the operating frequency of the switching element in accordance with voltage fluctuations in the inverter circuit. At the end of the lamp life, at the end of the lamp life, and when the power supply voltage rises, the apparatus can be prevented from being destroyed, and the cost can be reduced by using low-voltage components.

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

(Embodiment 1)
The circuit configuration and basic operation of the discharge lamp lighting device of the present embodiment shown in FIG. 1 are substantially the same as those of FIG. 8 of the conventional example. The conventional discharge lamp lighting device includes an inverter control circuit 2 and inverter control from the rectified voltage Vre. A control power supply circuit 3 for supplying power to the circuit 2 and the like is provided, and the same components are denoted by the same reference numerals and description thereof is omitted. The inverter control circuit 2 includes a feedback control circuit FB, and inputs the voltage across the series circuit of the inductor La and the capacitor Ca of the valley buried circuit 1 as the valley voltage detection signal S1, and from the valley voltage detection signal S1 to the capacitor Ca , That is, the valley voltage Vdc2 (see FIGS. 2A and 2B) of the voltage Vdc is detected. The feedback control circuit FB outputs drive signals SH and SL whose operating frequencies are variable in accordance with the valley voltage Vdc2, and performs feedback control to drive the switching elements Q1 and Q2 of the inverter circuit INV on and off. . At this time, if the valley voltage Vdc2 is high (if the valley voltage detection signal S1 is large), the operation frequency is increased and the operation frequency is moved away from the in-phase frequency to control the valley voltage Vdc2 to be lower. The voltage Vdc is reduced. On the other hand, if the valley voltage Vdc2 is low (if the valley voltage detection signal S1 is small), the operation frequency is lowered and the operation frequency is brought closer to the common-mode frequency so that the valley voltage Vdc2 is increased. Increase Vdc.

  Therefore, conventionally, the voltage Vdc at the time of light load and at the end of the lamp life has been significantly higher than the power supply voltage (rectified voltage Vre) as shown by the voltage Vdc (two-dot chain line) in FIG. The voltage Vdc of the configuration is controlled by the above-described feedback control by the inverter control circuit 2 to suppress boosting at light loads and at the end of the lamp life as shown in the voltage Vdc (solid line) of FIG. ing.

  In addition, since the inverter control circuit 2 uses the valley voltage detection signal S1 as a feedback signal, the boosting suppression effect of the voltage Vdc is further increased. This is because the increase in the valley voltage Vdc2 is clearly larger when the increase in the peak voltage Vdc1 and the increase in the valley voltage Vdc2 are compared at the light load and at the end of the lamp life.

  Further, the voltage Vdc boost suppression effect by the feedback control can suppress the voltage applied to the electronic components constituting the discharge lamp lighting device, and can use low-voltage components for the electronic components. Cost reduction can be achieved. Similarly, the voltage Vdc can be controlled to be substantially constant with respect to fluctuations in the power supply voltage of the AC power supply AC when the lamp is lit, and the output of the lamp load L can be made substantially constant.

(Embodiment 2)
FIG. 3 shows a specific circuit configuration of the discharge lamp lighting device according to the first embodiment. The inverter control circuit 2 includes a control IC 1 (L6574 manufactured by STMicroelectronics in this embodiment) which is a half-bridge driver IC. . Further, the filter circuit F is connected between the AC power supply AC and the rectifier circuit RE, the capacitor C10 is connected between the output terminals of the rectifier circuit RE, and the diode D10 is directed from the positive output of the rectifier circuit RE toward the inverter circuit INV. Are connected in the forward direction. The impedance element Z is configured by a parallel circuit of a diode D11 and a capacitor C11, and the diode D11 is connected in the forward direction from the rectifier circuit RE toward the valley buried circuit 1. In the inverter circuit INV, the switching elements Q1 and Q2 are composed of FETs, the switching element Q1 connects a resistor R11 between the gate and the source, and connects the gate to the high-side output pin P15 of the control IC 1 via the resistor R10. In addition, a capacitor C24 is connected between the drain and the source, and the switching element Q2 has a resistor R13 connected between the gate and the source, and a gate connected to the low-side output pin P11 of the control IC 1 via the resistor R12. Yes. Here, the pin P14 is connected to the source of the switching element Q1 on the high side, and the bootstrap capacitor C21 is connected to the pin P16.

  Hereinafter, the configuration and operation of the inverter circuit INV using the control IC 1 (L6574) will be described. First, a constant voltage is applied to the starting frequency setting pin P2 for setting a starting frequency for generating a starting voltage for lighting the lamp load L, and a resistor R14 and a capacitor C12 connected to the starting frequency setting pin P2 are applied. The start-up frequency is set by a current and a time constant determined by the series circuit and the resistor R15. At this time, if the current flowing through the starting frequency setting pin P2 is large, the starting frequency is high, and if the current is small, the starting frequency is low. The preheating time is set by a capacitor C22 connected to the preheating time setting pin P1, and the frequency of the oscillator provided therein is set by a capacitor C23 connected to the oscillation frequency setting pin P3. The pin P13 is an NC pin.

  A constant voltage is applied to the lighting frequency setting pin P4 for setting the lighting frequency of the lamp load L. When the current flowing through the lighting frequency setting pin P4 is large, the lighting frequency is high, and when the current is small, the lighting is high. The frequency of time will be lower.

  Pins P5 to P7 constitute respective terminals of the operational amplifier built in the control IC 1, P5 is an operational amplifier output terminal, pin P6 is an operational amplifier inverting input terminal, and pin P7 is an operational amplifier non-inverting input terminal. P5 is connected to the pin P4 via the resistor R17 and the diode D12, and the diode D12 is connected in the opposite direction to the output of the output pin P5. A parallel circuit of a resistor R18 and a capacitor C13 is connected between the output pin P5 and the inverting input pin P6, a series circuit of resistors R19 and R20 is connected to the inverting input pin P6, and a capacitor C14 is connected in parallel to the resistor R20. The non-inverting input pin P7 is connected to the lighting frequency setting pin P4. The valley voltage detection signal S1 is input to the connection point of the resistors R19 and R20 via the resistor R21, and the operational amplifier output of the output pin P5 is adjusted by the valley voltage detection signal S1, and the operational amplifier output of the output pin P5 is output. Accordingly, the amount of current drawn through the lighting frequency setting pin P4 is made variable via the diode D12 and the resistor R17, whereby the lighting frequency of the lamp load L is made variable. Then, drive signals SH and SL whose operating frequencies are variable according to the valley voltage Vdc2 are output from the pins P15 and P11, respectively. As described above, the feedback control using the valley voltage detection signal S1 is performed so that the operating frequency of the inverter circuit INV is variable and the voltage Vdc is controlled to be substantially constant. Therefore, at light load, at the end of the lamp life, Even when the AC power supply voltage fluctuates, the boosting of the voltage Vdc can be suppressed to prevent the component from being destroyed.

  Next, the lamp life end detection circuit 2a for detecting the end of life of the lamp load L will be described. The lamp life end detection circuit 2a detects the end of life of the lamp load L, and a series circuit of resistors R22 and R23 connected between the connection point between the lamp load L and the inductor L1 and the negative output of the rectifier circuit RE. A series circuit of a capacitor C15, a diode D14, and a Zener diode ZD1 connected between the connection point of the resistors R22 and R23 and the stop pin P8 of the control IC 1, and a diode D13 connected in parallel to the resistor R23 via the capacitor C15. And a resistor R24 and a smoothing capacitor C16 connected in parallel to the diode D13 via the diode D14, and a capacitor C17 and a resistor R25 connected in parallel to the capacitor C16 via the Zener diode ZD1. The output of the lamp life end detection circuit 2a (the connection point between the Zener diode ZD1 and the resistor R25) is connected to the stop pin P8 of the control IC1, and the control IC1 receives the drive signals SH and SL when a signal is input to the stop pin P8. Stop output. Since the lamp voltage rises at the end of the life of the lamp load L, the lamp life end detection circuit 2a converts the detected lamp voltage into a DC voltage and applies it to the capacitor C16, and the voltage across the capacitor C16 becomes the Zener diode ZD1. When the threshold value set by the zener voltage is exceeded, the end of lamp life is detected and an inverter operation stop signal is output to the stop pin P8 of the control IC1. Therefore, since the inverter control circuit 2 promptly shifts the inverter circuit INV to the stop state at the end of the life of the lamp load L, it is possible to avoid thermal stress due to heat generation of the lamp filament.

  Next, the control power supply circuit 3 will be described. The control power circuit 3 supplies power to the inverter control circuit 2, and includes a secondary winding L10 that is magnetically coupled to the inductor L1 and has one end connected to the negative output of the rectifier circuit RE, and the secondary winding L10. A series circuit of a diode D15 and a resistor R26 connected between the terminal and the power supply pin P12 of the control IC 1, a resistor R27 connected between the output side of the impedance element Z and the power supply pin P12, and a power supply pin P12 and GND It is composed of a parallel circuit of a Zener diode ZD2 connected between the pin P10 and a smoothing capacitor C18, and the GND pin P10 is connected to the negative output of the rectifier circuit RE. When the lamp load L is lit, power to the power supply pin P12 is supplied from two systems, a path via the resistor R26 and a path via the resistor R27, so that the inverter control circuit 2 uses the inverter circuit INV. Sufficient power is supplied to continue operation. Specifically, the induced voltage of the secondary winding L10 of the inductor L1 is supplied to the power supply pin P12 via the diode D15 and the resistor R26, and the output of the rectifier circuit RE is supplied to the power supply pin P12 via the resistor R27. The power supply voltage is determined by the Zener diode ZD2.

  On the other hand, when there is no load, power is supplied to the power supply pin P12 through only one system path via the resistor R27. The power supply via the resistor R27 is power that allows the inverter control circuit 2 to start the inverter circuit INV, but is not sufficient power to continue the operation, and the inverter circuit INV is intermittently operated repeatedly. When the power supply via the resistor R27 is further performed via the lamp load L, the power supply to the power supply pin 12 becomes zero when there is no load, and the inverter circuit INV stops. Thus, since the inverter circuit INV intermittently operates or stops at no load, the voltage Vdc is not boosted, and unnecessary power consumption can be further reduced.

  In the control power supply circuit 3, when the power supply voltage of the AC power supply AC is lowered, the voltage Vdc is lowered, so that the power supply via the resistor R27 is lowered, and further, the output to the lamp load L is also lowered. Therefore, the power supply through the resistor R26 also decreases. Therefore, when the power supply voltage of the AC power supply AC is equal to or higher than the lowest voltage that causes the inverter circuit INV to operate in the slow phase region, the control power supply circuit 3 supplies power that is higher than the voltage that can operate the inverter control circuit 2. When the inverter control circuit 2 operates the inverter circuit INV normally and, on the other hand, the power supply voltage of the AC power supply AC is equal to or lower than the lowest voltage that operates the inverter circuit INV in the slow phase region, the control power supply circuit 3 The inverter control circuit 2 supplies power that cannot continue the operation, and the operation of the inverter circuit INV is intermittently repeated or stopped. Therefore, it is possible to avoid a large stress generated in the switching elements Q1 and Q2 when the inverter circuit INV operates in the phase advance region due to the power supply voltage drop of the AC power supply AC, and the discharge lamp lighting device is more reliable. .

  Next, the abnormal voltage detection circuit 2b will be described. The abnormal voltage detection circuit 2b detects an abnormal voltage of the voltage Vdc, and includes a resistor R28 connected between the reset pin P9 of the control IC1 and the valley voltage detection signal S1 output, and a reset pin P9 of the control IC1. The control IC 1 is configured by a parallel circuit of a resistor R29 and a capacitor C20 connected between the negative side output of the rectifier circuit RE, and the control IC 1 resets the inverter operation when a signal is input to the reset pin P9. When the valley voltage detection signal S1 (that is, the valley voltage Vdc2 of the voltage Vdc) input to the abnormal voltage detection circuit 2b exceeds the threshold set by the specification of the control IC1, the control IC1 operates the inverter circuit INV. To return to the initial state (lamp preheating state). Therefore, the operation of the inverter circuit INV is reset to perform a protection operation against the abnormal voltage boost of the voltage Vdc at the time of load abnormality or component failure, thereby preventing the discharge lamp lighting device from being destroyed. When such a protection operation is not performed, the voltage across the capacitors Ca and Cb exceeds the rated voltage, the internal temperature of the capacitors Ca and Cb rises, the internal pressure rises, the explosion-proof valve opens, and the popping sound At the same time, internal gas may leak out. Further, when it is desired to stop the operation of the inverter circuit INV when an abnormal voltage of the voltage Vdc is detected, the output of the abnormal voltage detection circuit 2b is output to the pin P8 of the control IC 1 that stops the output of the drive signals SH and SL when a signal is input. Can be connected.

(Embodiment 3)
The embodiment of FIG. 4 has a configuration in which the impedance element Z in the circuit of Embodiment 1 (see FIG. 1) is replaced with a diode D11. In this circuit configuration, current flows in the path through the capacitor C3 when the switching element Q2 is turned on at the peak portion of the rectified voltage Vre, but this current does not flow in the valley portion, and eventually the inverter circuit according to the change in the rectified voltage Vre. The resonance condition at INV changes. Therefore, the supply current to the lamp load L due to the change of the rectified voltage Vre changes so that the current decreases during the period when the rectified voltage Vre is high and increases during the period when the rectified voltage Vre is low. Thus, similarly to the conventional example of FIG. 8, the valley filling circuit 1 is provided in which the change pattern of the supply current to the lamp load L with respect to the change of the rectified voltage Vre is opposite to the input from the AC power supply AC. The fluctuation of the supply current to the lamp load L can be reduced, and the stress of the switching elements Q1 and Q2 can be reduced.

  Then, similarly to the first embodiment, the inverter control circuit 2 increases the operating frequency and moves the operating frequency away from the common-mode frequency when the trough voltage Vdc2 is high (when the trough voltage detection signal S1 is large). The voltage Vdc is controlled to be lowered so that the voltage Vdc2 is lowered. If the valley voltage Vdc2 is low (if the valley voltage detection signal S1 is small), the operating frequency is lowered to bring the operating frequency closer to the common mode frequency. As a result, the valley voltage Vdc2 is controlled to increase, and the voltage Vdc is increased. Therefore, the inverter control circuit 2 prevents the destruction of the parts by controlling the boosting at the time of light load, at the end of the lamp life, and when the power supply voltage of the power supply AC fluctuates by the feedback control.

(Embodiment 4)
In the embodiment of FIG. 5, a series circuit of a pair of switching elements Q1 and Q2, a series circuit of a pair of capacitors Ce and Cf, and a series circuit of a pair of diodes De and Df are connected between both ends of the valley buried circuit 1. Then, the connection point of the capacitors Ce and Cf and the connection point of the diodes De and Df are connected, and the resonance formed by the series circuit of the inductor L1 and the capacitor C2 between the connection point and the connection point of the switching elements Q1 and Q2. A circuit is inserted, and a lamp load L is connected between both ends of the capacitor C2. The series circuit of the switching elements Q1, Q2 and the series circuit of the diodes D1, D2 are connected in antiparallel. That is, a half bridge type inverter circuit INV is configured. In this embodiment, the diodes Db and Dd constitute the impedance element Z, and the change pattern of the supply current to the lamp load L with respect to the change of the rectified voltage Vre is the AC power supply AC, as in the conventional example of FIG. By providing the valley filling circuit 1 that is opposite to the input from the power supply, fluctuations in the supply current to the lamp load L can be reduced, and the stress of the switching elements Q1 and Q2 can be reduced.

  Then, similarly to the first embodiment, the inverter control circuit 2 increases the operating frequency and moves the operating frequency away from the common-mode frequency when the trough voltage Vdc2 is high (when the trough voltage detection signal S1 is large). The voltage Vdc is controlled to be lowered so that the voltage Vdc2 is lowered. If the valley voltage Vdc2 is low (if the valley voltage detection signal S1 is small), the operating frequency is lowered to bring the operating frequency closer to the common mode frequency. As a result, the valley voltage Vdc2 is controlled to increase, and the voltage Vdc is increased. Therefore, the inverter control circuit 2 prevents the destruction of the parts by controlling the boosting at the time of light load, at the end of the lamp life, and when the power supply voltage of the power supply AC fluctuates by the feedback control.

(Embodiment 5)
In the valley buried circuit 1 shown in the embodiment of FIG. 6, the inductors La and Lb of the valley buried circuit 1 shown in the embodiments 1 to 4 are deleted, and the connection point of the switching elements Q1 and Q2 and the connection point of the diodes Db and Dd. It is replaced with an inductor Lab inserted between the two. The inductor Lab is inserted in the charging path of the smoothing capacitors Ca and Cb, and only one inductor is required, so that the size can be reduced. The valley buried circuit 1 used in each of the above examples can be replaced with a configuration as shown in this embodiment.

  In FIG. 6, a diode D16 is inserted between the positive side of the DC output terminal of the rectifier circuit RE and the inverter circuit INV to prevent backflow.

(Embodiment 6)
The basic circuit configuration and operation of the embodiment of FIG. 7 are the same as those of the second embodiment, but a load composed of a series circuit of an inductor L1 and capacitors C2 and C3 and a lamp load L connected in parallel to the capacitor C2. A plurality of resonance circuits K are provided. Further, a diode D1 having a cathode connected to the negative output of the rectifier circuit RE, a cathode connected to the anode of the diode D1, a diode D2 having an anode connected to the negative side of the valley filling circuit 1, and a capacitor C4 connected in parallel to the diode D2. Further, the valley buried circuit 1 has an inductor Lab interposed between the connection point of the switching elements Q1 and Q2 and the diodes Db and Dd, as in the fifth embodiment. .

  A plurality of load resonance circuits K are connected in parallel to each other, and in order to accurately detect the end of life for each lamp load L of the plurality of load resonance circuits K, the lamp life end detection circuit 2a includes resistors R22 and R23. , A capacitor C15 and diodes D13 and D14, each having a lamp voltage detection circuit 20a for detecting a lamp voltage, for each lamp load L. The output of each lamp voltage detection circuit 20a is connected via an OR circuit of a diode D14. When the voltage across capacitor C16 exceeds the threshold set by the Zener voltage of Zener diode ZD1, the end of lamp life is detected and inverter operation is performed at pin P8 (see FIG. 3) of control IC1. Outputs a stop signal. Therefore, it can be detected that the lamp voltage rises even at the end of the life of at least one lamp load L, and the inverter control circuit 2 promptly shifts the inverter circuit INV to the stop state. Thermal stress can be avoided.

  Moreover, if it is a lighting fixture carrying the discharge lamp lighting device in any one of Embodiment 1 thru | or 6, the effect similar to any of Embodiment 1 thru | or 6 can be acquired.

It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 1 of this invention. The voltage waveforms are the same as above, (a) is the waveform when the lamp is normally lit, and b) is the waveform when the load is light and at the end of the lamp life. It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 2 of this invention. It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 3 of this invention. It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 4 of this invention. It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 5 of this invention. It is a figure which shows the circuit structure of the discharge lamp lighting device of Embodiment 6 of this invention. It is a figure which shows the circuit structure of the conventional discharge lamp lighting device. It is a figure which shows the circuit structure of the discharge lamp lighting device which comprised the conventional multiple load. It is a figure which shows the operating frequency of the inverter circuit with respect to the different power supply voltage of a discharge lamp lighting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valley buried circuit 2 Inverter control circuit 3 Control power supply circuit AC AC power supply RE Rectifier circuit FB Feedback control circuit INV Inverter circuit Q1, Q2 Switching element L Lamp load Z Impedance element C2, C3, Ca, Cb, Cc Capacitor L1, La, Lb Inductor Da, Db, Dc, Dd Diode

Claims (10)

In a discharge lamp lighting device comprising a rectifier circuit that rectifies an AC power source and an inverter circuit that is connected to an output terminal of the rectifier circuit and converts the DC power source into a high-frequency output and supplies the output to a lamp load, the inverter circuits are connected in series with each other. Impedance elements including first and second switching elements that are alternately turned on / off, an impedance element interposed between the DC output terminals of the rectifier circuit and a series circuit of both switching elements, and a capacitor and an inductor And a resonance circuit that is connected between both ends of at least one switching element and extracts an output to the lamp load,
A series circuit of first and second rectifying elements is connected in antiparallel to both ends of the first switching element, and a connection point between the first and second rectifying elements and the first switching element in the second switching element A series circuit of the first inductor and the first smoothing capacitor is connected between the terminal opposite to the connection point, and the series circuit of the third and fourth rectifying elements is reversed at both ends of the second switching element. The second inductor and the second smoothing are connected in parallel and connected between a connection point of the third and fourth rectifying elements and a terminal of the first switching element opposite to the connection point of the second switching element. A valley buried circuit connecting a series circuit of capacitors, and
Both ends of the series circuit of the first and second switching elements by changing the operating frequency of the first and second switching elements according to the fluctuation of the voltage smoothed by at least one of the first and second smoothing capacitors. A discharge lamp lighting device comprising: a control circuit that suppresses voltage boosting. In a discharge lamp lighting device comprising a rectifier circuit that rectifies an AC power source and an inverter circuit that is connected to an output terminal of the rectifier circuit and converts the DC power source into a high-frequency output and supplies the output to a lamp load, the inverter circuits are connected in series with each other. First and second switching elements that are alternately turned on and off, a diode interposed in a forward direction between a DC output terminal of the rectifier circuit and a series circuit of both switching elements, a capacitor, and an inductor are provided. A series circuit with a diode is connected between both ends of at least one of the switching elements, and a resonance circuit that extracts an output to the lamp load; and
A series circuit of first and second rectifying elements is connected in antiparallel to both ends of the first switching element, and a connection point between the first and second rectifying elements and the first switching element in the second switching element A series circuit of the first inductor and the first smoothing capacitor is connected between the terminal opposite to the connection point, and the series circuit of the third and fourth rectifying elements is reversed at both ends of the second switching element. The second inductor and the second smoothing are connected in parallel and connected between a connection point of the third and fourth rectifying elements and a terminal of the first switching element opposite to the connection point of the second switching element. A valley buried circuit connecting a series circuit of capacitors, and
Both ends of the series circuit of the first and second switching elements by changing the operating frequency of the first and second switching elements according to the fluctuation of the voltage smoothed by at least one of the first and second smoothing capacitors. A discharge lamp lighting device comprising: a control circuit that suppresses voltage boosting. In a discharge lamp lighting device comprising a rectifier circuit that rectifies an AC power source and an inverter circuit that is connected to an output terminal of the rectifier circuit and converts the DC power source into a high-frequency output and supplies the output to a lamp load, the inverter circuits are connected in series with each other. First and second switching elements that are alternately turned on and off, and a resonance circuit that includes a capacitor and an inductor and is connected between both ends of at least one switching element and extracts an output to a lamp load. A half-bridge circuit,
A series circuit of first and second rectifying elements is connected in antiparallel to both ends of the first switching element, and a connection point between the first and second rectifying elements and the first switching element in the second switching element A series circuit of the first inductor and the first smoothing capacitor is connected between the terminal opposite to the connection point, and the series circuit of the third and fourth rectifying elements is reversed at both ends of the second switching element. The second inductor and the second smoothing are connected in parallel and connected between a connection point of the third and fourth rectifying elements and a terminal of the first switching element opposite to the connection point of the second switching element. A valley buried circuit connecting a series circuit of capacitors, and
Both ends of the series circuit of the first and second switching elements by changing the operating frequency of the first and second switching elements according to the fluctuation of the voltage smoothed by at least one of the first and second smoothing capacitors. A discharge lamp lighting device comprising: a control circuit that suppresses voltage boosting. A third inductor is interposed between the connection point of the first and second switching elements and the connection point of the series circuit of the first and second rectifying elements and the series circuit of the third and fourth rectifying elements. 4. The discharge lamp lighting device according to claim 1, wherein all or part of the first and second inductors are replaced by a third inductor. 5. The discharge lamp lighting device according to claim 1, further comprising means for detecting an end-of-life condition of the lamp load and means for stopping the operation of the inverter circuit when the end-of-life condition of the lamp load is detected. 6. The discharge lamp lighting device according to claim 5, further comprising: means for detecting a no-load condition; and means for stopping the operation of the inverter circuit when the no-load condition is detected or means for intermittently operating the inverter circuit. 5. A discharge lamp lighting device according to claim 1, further comprising means for protecting the inverter circuit when the voltage smoothed by the first and second smoothing capacitors exceeds a predetermined voltage. A plurality of resonance circuits connected in parallel to each other, a plurality of lamp loads for extracting outputs from the respective resonance circuits, a means for detecting an end-of-life state of each lamp load, and an end-of-life state of any one or more lamp loads; 5. The discharge lamp lighting device according to claim 1, further comprising means for stopping the operation of the inverter circuit at the time of detection. 9. A device according to claim 1, further comprising means for stopping the operation of the inverter circuit when the voltage of the AC power source drops below a voltage at which the inverter circuit operates in the phase advance region, or a means for intermittently operating the inverter circuit. A discharge lamp lighting device according to any one of the above. A lighting fixture comprising the discharge lamp lighting device according to any one of claims 1 to 9.

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