JP2013037800A - Discharge lamp lighting device and lighting apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device and a lighting apparatus using the same, which can maintain the lighting of a discharge lamp even if an instantaneous blackout or voltage drop of an AC power source occurs.SOLUTION: A discharge lamp lighting device 10 comprises: a DC power supply circuit 2 and down converter circuit 3 for converting an AC voltage supplied from an AC power source 1 to a DC voltage having a desired voltage value; an inverter circuit 4 for converting the DC voltage outputted from the down converter circuit 3 to an AC voltage whose polarity is periodically inverted to supply the converted AC voltage to a discharge lamp 6; a resonance circuit 5 for generating a startup voltage for starting-up the discharge lamp 6; a voltage detection circuit 7 for detecting a voltage state of the AC power source 1; and a control circuit 8c for controlling the inverter circuit 4. If the voltage detection circuit 7 detects an instantaneous blackout or voltage drop of the AC power source 1, the control circuit 8c sets an operational frequency of the inverter circuit 4 at a frequency in the neighborhood of a resonant frequency of the resonance circuit 5 or a frequency in the neighborhood of a frequency the reciprocal of an odd number times as large as the resonant frequency.

Description

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

  Conventionally, a discharge lamp lighting device for lighting a high-pressure discharge lamp such as a metal halide lamp or a high-pressure mercury lamp has been provided (see, for example, Patent Document 1). This discharge lamp lighting device converts a direct current supplied from an alternating current power source into a direct current, and converts the direct current from the direct current power source into a rectangular wave alternating current whose polarity is inverted at a predetermined frequency for high pressure discharge. And an output unit that supplies the electric lamp. The discharge lamp lighting device includes a control unit that controls the output unit, and an abnormality detection unit that detects an instantaneous voltage drop (instantaneous power failure or instantaneous voltage drop) of the AC power supply.

  The DC power supply unit includes a rectifier that full-wave rectifies the AC current of the AC power supply, a boost chopper circuit that boosts the output voltage of the rectifier to a predetermined value, and a smoothing capacitor that smoothes the output of the boost chopper circuit. The output unit is composed of a step-down chopper circuit that steps down the output voltage of the DC power supply unit to a predetermined value, a smoothing capacitor that smoothes the output voltage of the step-down chopper circuit, an inverter circuit, a primary winding and a capacitor of the transformer. And a resonance circuit. The inverter circuit is a so-called full-bridge type inverter circuit composed of four switching elements. Two switching elements located on the diagonal are set as one set, and switching is performed by alternately switching each set of switching elements. An AC voltage corresponding to the frequency is generated across the high-pressure discharge lamp.

  In order to light a high pressure discharge lamp by this discharge lamp lighting device, first, switching elements of each set of inverter circuits are alternately turned on / off to generate a high frequency voltage of several tens kHz to several hundreds kHz between both ends of the high pressure discharge lamp. Let Then, this high frequency voltage is resonantly boosted by a resonance circuit, and a high voltage resonance voltage is applied between both ends of the high pressure discharge lamp, so that the high pressure discharge lamp breaks down and lights up. Thereafter, the operating frequency (switching frequency) of the inverter circuit is switched to a low frequency of several tens Hz to several hundred Hz, and the lighting state of the high pressure discharge lamp is stably maintained.

  In this discharge lamp lighting device, when an instantaneous voltage drop of the AC power supply is detected by the abnormality detection unit, a rectangular wave AC having a frequency lower than that of the rectangular wave AC during normal lighting is supplied from the output unit to the high pressure discharge lamp. The lighting state of the high pressure discharge lamp is maintained by this rectangular wave alternating current.

JP 2009-289480 A (paragraph [0032] -paragraph [0061] and FIGS. 1 to 3)

  In the discharge lamp lighting device shown in Patent Document 1 described above, when an instantaneous voltage drop of the AC power supply occurs, a rectangular wave AC having a frequency lower than that during normal lighting is supplied to the high pressure discharge lamp. The lighting state can be maintained. However, in this case, the voltage level of the rectangular wave AC supplied to the high pressure discharge lamp is lowered by lowering the frequency, and the lighting maintenance time is also shortened accordingly, so that the instantaneous voltage drop of the AC power supply is restored. Previously, the high pressure discharge lamp could go out.

  The present invention has been made in view of the above problems, and its purpose is to provide a discharge lamp lighting device capable of maintaining a discharge lamp even when an instantaneous power failure or voltage drop of an AC power supply occurs, and It is in providing the lighting fixture using it.

  The discharge lamp lighting device according to the present invention includes a power conversion circuit that converts an AC voltage supplied from an AC power source into a DC voltage having a desired voltage value, and a polarity that periodically reverses the DC voltage output from the power conversion circuit. A polarity inversion circuit that converts the AC voltage into a discharge lamp and supplies the same to the discharge lamp. Further, the discharge lamp lighting device includes a resonance circuit that generates a starting voltage for starting the discharge lamp, a control circuit that controls the power conversion circuit and the polarity inversion circuit, and a voltage detection unit that detects a voltage state of the AC power supply. Is provided. When an instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detection means, the control circuit has an operating frequency of the polarity inversion circuit that is higher than the lighting frequency when the discharge lamp is rated-lit, The frequency is set to a frequency in the vicinity of the resonance frequency determined by the inductance and capacitance of the resonance circuit or a frequency in the vicinity of an odd-numbered frequency of the resonance frequency.

  In this discharge lamp lighting device, it is preferable that the control circuit sets the period during which the operating frequency of the polarity inversion circuit is set higher than the lighting frequency to be longer than the instantaneous power failure or voltage drop duration of the AC power supply. .

  Further, in this discharge lamp lighting device, the control circuit detects a momentary power failure or voltage drop of the AC power source by the voltage detection means, and is in a predetermined frequency range that is in the vicinity of the resonance frequency and does not include the resonance frequency. It is also preferable to sweep the operating frequency of the polarity inversion circuit.

  Further, in this discharge lamp lighting device, the control circuit sweeps the operating frequency of the polarity inversion circuit within a predetermined frequency range including the resonance frequency when an instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detecting means. It is also preferable to make it.

  Further, in this discharge lamp lighting device, when the instantaneous blackout or voltage drop of the AC power supply is detected by the voltage detection means, the control circuit is in the vicinity of the odd frequency of the resonance frequency and the frequency. It is also preferable to sweep the operating frequency of the polarity inversion circuit within a predetermined frequency range not including the signal.

  Further, in this discharge lamp lighting device, the control circuit detects the instantaneous power failure or voltage drop of the AC power source by the voltage detecting means, and the polarity is within a predetermined frequency range including an odd fraction of the resonance frequency. It is also preferable to sweep the operating frequency of the inverting circuit.

  The lighting fixture of the present invention includes any one of the above discharge lamp lighting devices and a discharge lamp.

  There is an effect that it is possible to provide a discharge lamp lighting device that can keep the discharge lamp lit even when an instantaneous power failure or voltage drop of the AC power supply occurs and a lighting fixture using the same.

It is a schematic circuit diagram which shows an example of the lighting fixture using the discharge lamp lighting device of Embodiment 1. It is a time chart explaining operation | movement same as the above. It is another time chart explaining operation | movement same as the above. It is a schematic circuit diagram which shows the other example same as the above. It is a schematic circuit diagram which shows an example of the lighting fixture using the discharge lamp lighting device of Embodiment 2.

  Hereinafter, embodiments of a discharge lamp lighting device and a lighting fixture will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic circuit diagram illustrating an example of a lighting fixture according to the present embodiment. This lighting fixture includes a discharge lamp lighting device 10 and a discharge lamp 6 that is lit by high-frequency power supplied from the discharge lamp lighting device 10. Prepare. Here, as the discharge lamp 6, for example, a high pressure discharge lamp such as a metal halide lamp or a high pressure mercury lamp is used. Since these lamps are well known in the art, description thereof is omitted here.

  The discharge lamp lighting device 10 includes a DC power supply circuit 2, a down converter circuit 3, an inverter circuit (polarity inverting circuit) 4, a resonance circuit 5, a voltage detection circuit (voltage detection means) 7, and control circuits 8a to 8c. With.

  The DC power supply circuit 2 includes a line filter LF1 for cutting high-frequency components of the AC power supply 1, a full-wave rectifier circuit (diode bridge) 21 for full-wave rectifying the AC output of the AC power supply 1, an inductor L4, a diode D2, And a conventionally known step-up chopper circuit including a switching element Q6 and a smoothing capacitor C6. A resistor R1 is connected between the switching element Q6 and the ground, and a voltage applied to the resistor R1 is input to a control circuit 8a described later as a feedback signal.

  The down-converter circuit 3 includes a series circuit of a switching element Q1 and an inductor L1, and a diode D1 whose cathode side is connected to a connection point between the switching element Q1 and the inductor L1 and whose anode side is connected to the ground via a resistor R2. The A capacitor C1 is connected between the output terminals of the down-converter circuit 3, and a series circuit of resistors R7 and R8 is connected between the output terminal on the high voltage side and the ground. The operating frequency of the switching element Q1 of the down-converter circuit 3 is controlled by a control circuit 8b described later. The voltage applied to the resistor R2 and the divided voltages of the resistors R7 and R8 are input to the control circuit 8b as feedback signals. Is done.

  The inverter circuit 4 is a so-called full bridge type inverter circuit composed of four switching elements Q2 to Q5. A discharge lamp 6 is connected via a transformer T3 between the connection point of the switching elements Q2, Q3 connected in series and the connection point of the switching elements Q4, Q5 connected in series. Note that the operating frequency of these switching elements Q2 to Q5 is controlled by a control circuit 8c described later, and the group of switching elements Q2 and Q5 and the group of switching elements Q3 and Q4 are alternately turned on / off.

  The resonance circuit 5 includes a transformer T3 and a capacitor C2, and generates a high-frequency starting voltage that starts the discharge lamp 6. Here, the resonance frequency of the resonance circuit 5 is determined by the capacitance of the capacitor C2 and the inductance of the transformer T3. At the start of lighting, the operating frequency of the switching elements Q2 to Q5 of the inverter circuit 4 is set to a frequency near the resonance frequency. The As a result, a high-frequency starting voltage is generated in the resonance circuit 5, and the discharge lamp 6 is broken down and lit by this starting voltage. The lighting operation of the discharge lamp 6 will be described later.

  The voltage detection circuit 7 includes a series circuit of resistors R3 to R6 and a capacitor C7 connected in parallel with the resistor R6, and a voltage at a connection point between the resistors R5 and R6 is input to the control circuit 8c. Here, in this embodiment, the output voltage of the step-up chopper circuit of the DC power supply circuit 2 is used as the detection voltage of the voltage detection circuit 7, and the control circuit 8c sets the operating frequency of the switching elements Q2 to Q5 according to the value of this detection voltage. Set. This operation will be described later.

  The control circuit 8a has a function of controlling the on / off operation of the switching element Q6 of the DC power supply circuit 2, and a voltage applied to the resistor R1 is input as a feedback signal, and the switching element Q6 according to the magnitude of the feedback signal. Set the operating frequency. Then, when the switching element Q6 performs the switching operation at the set operating frequency, a DC voltage having a desired voltage value is generated between both ends of the capacitor C6.

  The control circuit 8b has a function of controlling the on / off operation of the switching element Q1 of the down converter circuit 3, and the voltage applied to the resistor R2 and the divided voltages of the resistors R7 and R8 are input as a feedback signal. The operating frequency of the switching element Q1 is set in accordance with the magnitude of (ie, the magnitude of the load current and the output voltage). Then, by performing the switching operation at the set operating frequency, the switching element Q1 reduces the output voltage of the DC power supply circuit 2 to a DC voltage having a desired voltage value. Here, in the present embodiment, the DC power supply circuit 2 and the down converter circuit 3 constitute a power conversion circuit.

  The control circuit 8c has a function of controlling the on / off operation of the switching elements Q2 to Q5 of the inverter circuit 4, and sets the operating frequency of the switching elements Q2 to Q5 near the resonance frequency of the resonance circuit 5 when starting the discharge lamp 6. Set to frequency. After the discharge lamp 6 is stably lit, the control circuit 8c switches the operating frequency of the switching elements Q2 to Q5 to a frequency lower than the resonance frequency, and maintains the lighting state.

  Next, the lighting operation of the discharge lamp 6 will be briefly described. When a user operates a power switch (not shown) attached to a construction surface (wall surface or the like) and predetermined AC power is supplied from the AC power source 1, the control circuit 8a switches the switching element Q6 of the DC power circuit 2. The operating frequency is controlled to boost the DC voltage to a desired voltage value. The DC voltage boosted by the DC power supply circuit 2 is supplied to the down converter circuit 3, and the control circuit 8b controls the operating frequency of the switching element Q1 to step down the supplied DC voltage to a DC voltage having a desired voltage value.

  The DC voltage stepped down by the down-converter circuit 3 is supplied to the inverter circuit 4, and the control circuit 8 c controls the operating frequency of the switching elements Q <b> 2 to Q <b> 5 to a frequency in the vicinity of the resonance frequency of the resonance circuit 5 to increase the frequency to the resonance circuit 5. The starting voltage is generated. As a result, the discharge lamp 6 breaks down by this starting voltage and lights up. Then, after the discharge lamp 6 is stably lit, the control circuit 8c switches the operating frequency of the switching elements Q2 to Q5 to a frequency lower than the resonance frequency (for example, 160 Hz), and maintains the lighting state of the discharge lamp 6.

  By the way, an instantaneous power failure or voltage drop of the AC power supply 1 may occur depending on a load situation on the user side, an instantaneous ON / OFF of a power switch (not shown), a power supply environment, and the like. In this case, since the lighting maintenance time is short in the above-described conventional example, the high-pressure discharge lamp may be turned off before the power failure or voltage drop is restored. In this embodiment, the following method is adopted. The above problem is solved.

  FIG. 2 is a time chart for explaining the operation of the discharge lamp lighting device 10. In this example, the capacitance of the capacitor C2 of the resonance circuit 5 is 1500 pF and the inductance of the transformer T3 is 150 μH. As a result, the resonance frequency of the resonance circuit 5 is set to about 335 kHz. A detection voltage V2 in FIG. 2 indicates a detection voltage by the voltage detection circuit 7.

  When an instantaneous power failure or voltage drop of the AC power supply 1 occurs at time t1, the output voltage (detection voltage V2) of the DC power supply circuit 2 gradually decreases from 300V in the steady state. When the detection voltage V2 falls below 260 V at time t2, the control circuit 8c switches the operating frequency f1 of the switching elements Q2 to Q5 from 160 Hz during normal operation to a frequency several kHz higher than the resonant frequency 335 kHz of the resonant circuit 5. . Then, as shown in FIG. 2, the lamp voltage V1 applied to the discharge lamp 6 rises to a voltage higher than the sustaining voltage, and as a result, the discharge lamp 6 is lit even when the output voltage of the DC power supply circuit 2 is lowered. It becomes possible to maintain the state.

  Thereafter, when the detection voltage V2 exceeds 260 V at time t3, the control circuit 8c reduces the operating frequency f1 of the switching elements Q2 to Q5 to 160 Hz and maintains the lighting state of the discharge lamp 6. Here, in the present embodiment, the period during which the switching elements Q2 to Q5 are operated at a frequency higher than the resonance frequency is a continuation period in which an instantaneous power failure or voltage drop of the AC power supply 1 is assumed to continue (for example, several ms to several 10 ms). Therefore, the discharge lamp 6 is not turned off before the instantaneous power failure or voltage drop of the AC power supply 1 is recovered, and the lighting state of the discharge lamp 6 can be reliably maintained.

  Next, FIG. 3 is another time chart for explaining the operation of the discharge lamp lighting device 10. In this example, when an instantaneous power failure or voltage drop of the AC power supply 1 occurs, the operating frequency of the switching elements Q2 to Q5 passes through 1/3 of the resonance frequency 335 kHz (about 112 kHz) of the resonance circuit 5. f1 is swept between 100 kHz and 120 kHz. As a result, similarly to the example shown in FIG. 2, the lamp voltage V1 applied to the discharge lamp 6 can be maintained at a voltage higher than the lighting maintenance voltage, and the lighting state of the discharge lamp 6 can be maintained. In this case as well, the period during which the operating frequency f1 of the switching elements Q2 to Q5 is swept is set to the same period as the continuation period (several ms to several tens of ms). Therefore, also in this case, the discharge lamp 6 is not turned off before the instantaneous power failure or voltage drop of the AC power supply 1 is recovered, and the lighting state of the discharge lamp 6 can be reliably maintained. Furthermore, according to this example, it is not necessary to consider the variation in the performance of the transformer T3 and the capacitor C2 constituting the resonance circuit 5, and the transformer T3 and the capacitor C2 are smaller than the case of sweeping through the resonance frequency. Can be realized.

  Thus, in the present embodiment, when an instantaneous power failure or voltage drop of the AC power supply 1 occurs, the operating frequency of the switching elements Q2 to Q5 of the inverter circuit 4 is set to a frequency near the resonance frequency of the resonance circuit 5. Or sweeping in a predetermined frequency range including 1/3 of the resonance frequency. As a result, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the lighting maintenance voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so that an instantaneous power failure or voltage drop of the AC power supply 1 occurs. Even in this case, the lighting state of the discharge lamp 6 can be maintained. And since the lighting maintenance time of the discharge lamp 6 can be lengthened compared with a prior art example, it can suppress that the discharge lamp 6 extinguishes before the instantaneous power failure or voltage drop of AC power supply 1 is recovered | restored.

  In the present embodiment, the full bridge type inverter circuit 4 including four switching elements Q2 to Q5 has been described as an example. However, for example, as shown in FIG. 4, two switching elements Q2 and Q3 and two capacitors C8 are used. , C9 may be a so-called half-bridge type inverter circuit. In this case as well, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the sustaining voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so an instantaneous power failure or voltage drop of the AC power supply 1 Even when this occurs, the lighting state of the discharge lamp 6 can be maintained.

(Embodiment 2)
Embodiment 2 of the lighting fixture using the discharge lamp lighting device 10 will be described with reference to FIG.

  FIG. 5 is a schematic circuit diagram illustrating an example of the lighting fixture of the present embodiment, and this lighting fixture includes a discharge lamp lighting device 10 and a discharge lamp 6.

  The discharge lamp lighting device 10 includes a DC power supply circuit 2, a resonance circuit 5, a voltage detection circuit (voltage detection means) 7, control circuits 8a and 8c, a polarity inversion step-down chopper circuit (polarity inversion circuit) 9, Is provided. Since the DC power supply circuit 2, the voltage detection circuit 7, and the control circuits 8a and 8c are the same as those in the first embodiment, the description thereof is omitted here. Here, in this embodiment, the DC power supply circuit 2 constitutes a power conversion circuit.

  The step-down chopper circuit 9 has a so-called full-bridge type inverter circuit composed of four switching elements Q2 to Q5. A series circuit of a step-down chopper inductor L3 and a smoothing capacitor C2 is connected between a connection point of the switching elements Q2 and Q3 connected in series and a connection point of the switching elements Q4 and Q5 connected in series. .

  The resonance circuit 5 includes an inductor L5 and a resonance capacitor C10. One end of the inductor L5 is connected to the connection point of the switching elements Q2 and Q3, and the other end of the inductor L5 is connected to the discharge lamp 6. Yes. Capacitor C10 has one end connected to the connection point between inductor L5 and discharge lamp 6, and the other end connected to ground via resistor R2. Since the lighting operation of the discharge lamp 6 is the same as that of the first embodiment, the description thereof is omitted here.

  Next, the operation of the discharge lamp lighting device 10 when an instantaneous power failure or voltage drop of the AC power supply 1 occurs will be described.

  When an instantaneous power failure or voltage drop of the AC power supply 1 occurs during normal operation, the control circuit 8c changes the operating frequency of the switching elements Q2 to Q5 from a low frequency during normal operation to a frequency near the resonance frequency of the resonance circuit 5. Switch. Then, when the switching elements Q2 to Q5 perform the switching operation at the changed frequency, a high-frequency starting voltage is generated in the resonance circuit 5, and the lighting state of the discharge lamp 6 is maintained by this starting voltage. Further, similarly to the first embodiment, the operating frequency of the switching elements Q2 to Q5 may be swept within a predetermined frequency range including 1/3 of the resonance frequency of the resonance circuit 5, and the discharge lamp 6 is turned on in the same manner. The state can be maintained. In the present embodiment, the period for operating the switching elements Q2 to Q5 at a frequency higher than the resonance frequency and the period for sweeping the operating frequency of the switching elements Q2 to Q5 are the same as the duration period (several ms to several tens of ms). The period is set. Therefore, the discharge lamp 6 is not turned off before the instantaneous power failure or voltage drop of the AC power supply 1 is recovered, and the lighting state of the discharge lamp 6 can be reliably maintained.

  Thus, in the present embodiment, when an instantaneous power failure or voltage drop of the AC power supply 1 occurs, the operating frequency of the switching elements Q2 to Q5 of the step-down chopper circuit 9 is set to a frequency near the resonance frequency of the resonance circuit 5. It is set or swept within a predetermined frequency range including 1/3 of the resonance frequency. As a result, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the lighting maintenance voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so that an instantaneous power failure or voltage drop of the AC power supply 1 occurs. Even in this case, the lighting state of the discharge lamp 6 can be maintained. And since the lighting maintenance time of the discharge lamp 6 can be lengthened compared with a prior art example, it can suppress that the discharge lamp 6 extinguishes before the instantaneous power failure or voltage drop of AC power supply 1 is recovered | restored.

  Further, by using the discharge lamp lighting device 10 described in the first and second embodiments, a lighting fixture capable of maintaining the discharge lamp 6 even when an instantaneous power failure or voltage drop occurs in the AC power supply 1 is provided. be able to.

  Also in this embodiment, the step-down chopper circuit 9 may be configured by a half-bridge type inverter circuit. Similarly, even when an instantaneous power failure or voltage drop of the AC power supply 1 occurs, the lighting state of the discharge lamp 6 is changed. Can be maintained.

  In the first and second embodiments described above, the output voltage of the boost chopper circuit of the DC power supply circuit 2 is used as the detection voltage of the voltage detection circuit 7. For example, the output voltage of the full-wave rectifier circuit 21 is used as the detection voltage of the voltage detection circuit 7. The present invention is not limited to this embodiment.

  Further, in the first and second embodiments, when an instantaneous power failure or voltage drop of the AC power supply 1 occurs, the operating frequency of the switching elements Q2 to Q5 is set to a frequency near the resonance frequency of the resonance circuit 5, It may be set to a frequency in the vicinity of a frequency that is an odd-numbered frequency. In this case as well, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the lighting maintenance voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so that an instantaneous power failure or voltage drop of the AC power supply 1 occurs. Even in this case, the lighting state of the discharge lamp 6 can be maintained.

  In the first and second embodiments, when an instantaneous power failure or voltage drop occurs in the AC power supply 1, the operating frequency of the switching elements Q <b> 2 to Q <b> 5 is a predetermined frequency that includes 1/3 of the resonant frequency of the resonant circuit 5. Although the frequency range is swept, the frequency range may be a predetermined frequency range including a frequency that is an odd number of the resonance frequency, and is not limited to the above embodiment. Further, the frequency range may be a predetermined frequency range including the resonance frequency of the resonance circuit 5. Also in these cases, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the lighting maintenance voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so that an instantaneous power failure or voltage drop of the AC power supply 1 can occur. Even when it occurs, the lighting state of the discharge lamp 6 can be maintained. Further, in these cases, it is not necessary to consider variations in the performance of the transformer T3 and the capacitor C2 constituting the resonance circuit 5, and in the former case, the transformer T3 is compared with the case where the resonance frequency is swept to pass through the resonance frequency. In addition, the capacitor C2 can be downsized.

  Further, the frequency range may be a predetermined frequency range that is in the vicinity of an odd-numbered frequency of the resonance frequency and does not include the frequency, or a predetermined frequency range that is in the vicinity of the resonance frequency and does not include the resonance frequency. It may be a frequency range. Also in these cases, even when the output voltage of the DC power supply circuit 2 becomes low, a voltage higher than the lighting maintenance voltage of the discharge lamp 6 can be supplied to the discharge lamp 6, so that an instantaneous power failure or voltage drop of the AC power supply 1 can occur. Even when it occurs, the lighting state of the discharge lamp 6 can be maintained. In these cases, the resonance frequency or the odd frequency of the resonance frequency is swept so as not to pass, so that the stress of the inverter circuit 4 can be reduced, and in the former case, compared with the latter case. The transformer T3 and the capacitor C2 can be downsized. In these cases, it is necessary to set the frequency range to a frequency range in which the lighting state of the discharge lamp 6 can be maintained.

  In the first and second embodiments, the period during which the switching elements Q2 to Q5 are operated at a frequency higher than the resonance frequency and the period during which the operating frequency of the switching elements Q2 to Q5 is swept are determined as an instantaneous power failure or voltage of the AC power supply 1. The duration is set to be the same as the duration (several ms to several tens of ms) where the descent is expected to continue, but may be set to a duration longer than this duration. When a power failure or voltage drop occurs, the discharge lamp 6 can be reliably kept on.

1 AC power supply 2 DC power supply circuit (power conversion circuit)
3 Down converter circuit (power conversion circuit)
4 Inverter circuit (polarity inversion circuit)
5 Resonant circuit 6 Discharge lamp 7 Voltage detection circuit (voltage detection means)
8c Control circuit 10 Discharge lamp lighting device

Claims (7)

A power conversion circuit that converts an AC voltage supplied from an AC power source into a DC voltage having a desired voltage value;
A polarity inversion circuit that converts the DC voltage output from the power conversion circuit into an AC voltage whose polarity is periodically inverted and supplies the AC voltage to the discharge lamp;
A resonant circuit for generating a starting voltage for starting the discharge lamp;
A control circuit for controlling the power conversion circuit and the polarity inversion circuit;
Voltage detecting means for detecting the voltage state of the AC power supply,
When the instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detection means, the control circuit has an operating frequency of the polarity inversion circuit higher than a lighting frequency when the discharge lamp is lighted at a rated level. A discharge lamp lighting device, wherein the frequency is set to a frequency in the vicinity of a resonance frequency determined by an inductance and a capacitance of the resonance circuit or a frequency in the vicinity of an odd-numbered frequency of the resonance frequency.   The control circuit sets a period during which the operating frequency of the polarity inversion circuit is set to a frequency higher than the lighting frequency to be longer than an instantaneous power failure or voltage drop duration of the AC power supply. Item 2. A discharge lamp lighting device according to Item 1.   When the voltage detection means detects an instantaneous power failure or voltage drop of the AC power supply, the control circuit reverses the polarity in a predetermined frequency range that is in the vicinity of the resonance frequency and does not include the resonance frequency. 3. The discharge lamp lighting device according to claim 1, wherein the operating frequency of the circuit is swept.   The control circuit sweeps the operating frequency of the polarity inversion circuit in a predetermined frequency range including the resonance frequency when an instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detecting means. The discharge lamp lighting device according to claim 1 or 2.   When an instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detection means, the control circuit is a predetermined frequency that is in the vicinity of an odd number of a fraction of the resonance frequency and does not include the frequency. 3. The discharge lamp lighting device according to claim 1, wherein the operating frequency of the polarity inverting circuit is swept within a frequency range.   When the instantaneous power failure or voltage drop of the AC power supply is detected by the voltage detection means, the control circuit operates the polarity inversion circuit in a predetermined frequency range including an odd fraction of the resonance frequency. The discharge lamp lighting device according to claim 1 or 2, wherein the frequency is swept.   A lighting fixture comprising: the discharge lamp lighting device according to any one of claims 1 to 6; and the discharge lamp.

Images