JP2010177115A - Rare gas discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rare gas discharge lamp lighting device improving startability even if a dimming ratio is small and capable of widening a dimming range, without generating excessive ripples or noises at an output of an AC/DC conversion part. <P>SOLUTION: In the rare gas discharge lamp lighting device 10, a dimming circuit 4 is connected between an input power source part Vin and a switching circuit 1 connected with a primary side of a high-voltage transformer T1. The dimming circuit 4 inputs a dimming signal outputted from a dimming control circuit 3, and supplies high-frequency pulse voltage capable of setting a frequency arbitrarily to an input part of the switching circuit 1 at dimming by superimposing onto a direct-current voltage impressed at normal time, so that higher trigger voltage than at normal time is impressed onto a rare gas discharge lamp DL. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rare gas discharge lamp lighting device for lighting a rare gas discharge lamp used as a light source for a backlight, illumination, etc. of a liquid crystal display panel at a high frequency.

  Conventionally, cold cathode discharge lamps and hot cathode discharge lamps have been used as backlight sources and illumination light sources for liquid crystal display panels, but in recent years, rare gases such as xenon that do not contain mercury, which is a harmful substance, have been sealed. Noble gas discharge lamps have been developed. It is known that a rare gas discharge lamp can obtain high brightness by lighting by applying a pulsed high frequency voltage, and an inverter circuit that generates such a high frequency voltage as a lighting device for a rare gas discharge lamp. A lighting device having the above is preferably used.

  In general, the screen luminance of a liquid crystal display panel on which such a rare gas discharge lamp is mounted is required to be adjusted to an appropriate magnitude according to the ambient brightness and image information. This screen brightness adjustment is performed, for example, by dimming the backlight using a PWM control method. The backlight dimming is generally burst dimming. Also in lighting applications, a wide dimming range is required for indirect lighting or the like in order to adjust the brightness according to the usage environment. However, if dimming control of a rare gas discharge lamp is attempted and the on-duty of the dimming pulse is narrowed (decreasing the dimming rate), the discharge becomes unstable and the discharge lamp flickers or disappears. There is a problem that the phenomenon tends to occur and the light control range cannot be widened.

  Conventionally, with respect to luminance adjustment by burst dimming, for example, means for solving the above problems at the time of dimming start has been disclosed (for example, see Patent Document 1).

  Patent Document 1 discloses a discharge lamp lighting device 100 shown in FIG. 3, and this discharge lamp lighting device 100 is rectified by a rectifier DB including a diode bridge that rectifies an AC power supply AC, and the like. A DC power supply circuit 101 that outputs a DC voltage from the voltage, a high-frequency power supply circuit PS that converts the DC voltage output from the DC power supply circuit 101 into a high-frequency voltage, and an induction coil L103 to which the high-frequency output power of the high-frequency power supply circuit PS is applied The impedance matching circuit 104 provided between the induction coil L103 and the high frequency power supply circuit PS, and the dimming control of the electrodeless discharge lamp 105 by adjusting the high frequency output of the high frequency power supply circuit PS. The electrodeless discharge lamp 105 is disposed in the vicinity of the induction coil L103.

  The DC power supply circuit 101 includes a step-up / step-down chopper circuit that stabilizes a DC voltage. The step-up / step-down chopper circuit includes switching elements Q103 and Q104, diodes D101 and D102, an inductance element L101, a smoothing capacitor C101, and a switching element. A chopper control circuit 101a for driving and controlling the elements Q103 and Q104 is provided. The chopper control circuit 101a switches the switching elements Q103 and Q104 in a time division manner so that a predetermined DC voltage E stabilized is generated.

  The high frequency power supply circuit PS includes a drive circuit 103 including an oscillation circuit and a preamplifier (not shown), and a power amplification circuit 102 that amplifies the output of the drive circuit 103. The power amplifying circuit 102 used here is one that performs push-pull operation of two transistors Q101 and Q102 to perform class D amplification, and generates high-frequency power through a series resonant circuit of an inductor L102 and a capacitor C102. It is designed to output.

  The dimming circuit 107 controls driving / stopping of the switching elements Q101 and Q102 of the power amplifier circuit 102 by outputting a pulse-shaped dimming control signal that intermittently divides the high-frequency output in a time division manner to the drive circuit 103. Thus, the light output of the electrodeless discharge lamp 105 is dimmed. In addition, the dimming circuit 107 predicts the time for which the electrodeless discharge lamp 105 is lit, for example, by providing a timer circuit therein. The chopper control circuit 101a and the dimming circuit 7 constitute an output voltage variable means 106.

  The time when the DC power supply circuit (step-up / step-down chopper circuit) 101 is started up is t1, and the time when the electrodeless discharge lamp 105 is lit is t2. When the electrodeless discharge lamp 105 is started in a state in which the dimming control signal is output from the dimming circuit 107, that is, at the time of dimming start, the dimming circuit 107 outputs, for example, a high level to the chopper control circuit 101a. A signal is output. Further, when the electrodeless discharge lamp 105 is started in a state where the dimming control signal is not output from the dimming circuit 107, that is, at the start without dimming, the dimming circuit 107 has a low level with respect to the chopper control circuit 101a. A signal is output.

  The chopper control circuit 101a determines that the dimming is started when a high level signal is input from the dimming circuit 107, and outputs the output voltage (smoothing capacitor) of the step-up / down chopper circuit 101 between times t1 and t2. The voltage between both ends of C101 is controlled to be a voltage E2 higher than E1. The voltage E2 here is set to a sufficiently large voltage to light the electrodeless discharge lamp 105 at the time of dimming start. Then, at time t2 after the electrodeless discharge lamp 105 is turned on, the chopper control circuit 101a controls the output voltage so that the output voltage of the step-up / step-down chopper circuit 101 becomes a voltage E1 lower than the initial voltage E2. .

  On the other hand, when a low level signal is input from the dimming circuit 107, the chopper control circuit 101a determines that the dimming is not started, and the output voltage of the step-up / down chopper circuit 101 is E1 from the beginning of time t1. Control to be. Thus, in the case of the dimming start, the output voltage of the step-up / down chopper circuit 101 is first set to E2 and then switched to E1 after lighting. In the case of the start without dimming, the output voltage is E1. Will remain fixed. When the electrodeless discharge lamp 105 is stably lit after the elapse of time t2, the output voltage of the step-up / step-down chopper circuit 101 remains E1, so that the drive circuit 103 is controlled by the dimming control signal output from the dimming circuit 107. The high frequency output is turned on / off in a time-sharing manner to control the high frequency output, and the electrodeless discharge lamp 105 is dimmed so as to have a predetermined light output.

  As described above, in the discharge lamp lighting device 100, when dimming is started, a voltage E2 that is large enough to light the electrodeless discharge lamp 105 is first generated and switched to a predetermined E1 after lighting. The startability until the electrodeless discharge lamp 105 is in a stable lighting state is improved, and the dimming range can be widened.

Japanese Patent Laid-Open No. 2002-134295

However, such a conventional discharge lamp lighting device has the following problems.
That is, in the discharge lamp lighting device 100, the dimming range is widened by controlling the output voltage of the step-up / step-down chopper circuit 101 by the chopper control circuit 101a in accordance with the signal output from the dimming circuit 107. Therefore, in order to control the output voltage, it is necessary to improve the responsiveness of the control system. However, if the responsiveness of the output voltage control system is improved, the commercial AC frequency generated in the step-up / down chopper circuit 101 is doubled. There is a problem that frequency ripple noise increases. On the other hand, in order to suppress this ripple noise, there is a problem that it is necessary to slow down the response of the output voltage control system.

  The present invention has been made in view of the above problems, and has a simple circuit configuration, does not generate excessive ripple noise in the output of the AC / DC converter, and has a low dimming rate. Even in such a case, an object of the present invention is to provide a rare gas discharge lamp lighting device with improved startability and capable of extending the dimming range.

  The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further, while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) An input power supply unit, a high-voltage transformer, a switching circuit connected to the primary side of the high-voltage transformer, a drive circuit that drives the switching circuit, and a dimming control circuit that generates and outputs a dimming signal In the rare gas discharge lamp lighting device for lighting the rare gas discharge lamp connected to the secondary side of the high-voltage transformer, a dimming circuit is connected between the input power supply unit and the switching circuit, and the dimming The circuit receives the dimming signal output from the dimming control circuit, and superimposes a high-frequency pulse voltage whose frequency can be arbitrarily set at the time of dimming on a DC voltage applied in a steady state. A rare gas discharge lamp lighting device is characterized in that a higher trigger voltage is applied to the rare gas discharge lamp than in a steady state by supplying to the input section.

(2) In the rare gas discharge lamp lighting device according to item (1), the dimming circuit includes an intermittent oscillation control circuit and a dimming auxiliary circuit, and the intermittent oscillation control circuit includes the input power supply unit and the dimming control circuit. The dimming auxiliary circuit is connected between the dimming auxiliary circuit and performs an on / off operation at the time of dimming, and the dimming auxiliary circuit is applied with the high-frequency pulse voltage at the steady state during the off operation of the intermittent oscillation control circuit. A rare gas discharge lamp lighting device characterized in that it is superimposed on a direct current voltage and supplied to the input of the switching circuit (claim 2).

(3) In the rare gas discharge lamp lighting device according to item (2), the dimming auxiliary circuit includes a diode, a first capacitor, and first and second switching elements, and the diode has one end thereof. Is connected to the intermittent oscillation control circuit together with one end of the first switching element, the other end is connected to one end of the switching circuit together with one end of the first capacitor, and the other end of the first capacitor is connected to the first capacitor. A rare gas discharge lamp lighting, wherein the second switching element is connected to one end of the second switching element together with the other end of the first capacitor, and the other end of the second switching element is connected to the negative electrode side of the input power supply unit. Device (claim 3).

(4) In the rare gas discharge lamp lighting device according to (3), the dimming auxiliary circuit has one end connected to the other end of the diode and the other end together with the other end of the second switching element. A rare gas discharge lamp lighting device, further comprising a second capacitor connected to the negative electrode side of the input power supply unit (Claim 4).

(5) In the rare gas discharge lamp lighting device according to any one of (2) to (4), one end of the intermittent oscillation control circuit is connected to a positive electrode side of the input power supply unit, and the other end is the dimming auxiliary circuit. A rare gas discharge lamp lighting device comprising: a light control element comprising a switching element connected to one end of the light source; and a drive circuit for driving the light control element.

(6) In the rare gas discharge lamp lighting device according to any of (2) to (5), the driving frequency of the switching circuit is higher than the driving frequency of the intermittent oscillation control circuit, and the driving frequency of the dimming auxiliary circuit A rare gas discharge lamp lighting device characterized by the following: (Claim 6).

  Since the present invention is configured as described above, it does not generate excessive ripple noise in the output of the AC / DC converter while having a simple circuit configuration, and can be started even when the dimming rate is small. Thus, it is possible to provide a rare gas discharge lamp lighting device capable of expanding the dimming range.

It is a circuit block diagram which shows the discharge lamp lighting device in one Embodiment of this invention. It is a timing chart which shows operation | movement of the discharge lamp lighting device shown in FIG. It is a circuit block diagram which shows an example of the conventional discharge lamp lighting device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, a discharge lamp lighting device 10 according to an embodiment of the present invention boosts a voltage while switching the polarity of an input power supply Vin that supplies a DC voltage, a step-up transformer T1, and a DC voltage input from the input power supply Vin. A switching circuit 1 that is applied to the primary side of the transformer T1, a switching element drive circuit 2 that drives the switching circuit 1, and a dimming control circuit 3 that outputs a dimming signal are provided. A rare gas discharge lamp DL is connected. The input power supply unit Vin includes, for example, a commercial AC input power supply, a diode bridge that rectifies the AC voltage of the commercial AC input power supply, and a boost chopper circuit that converts the AC voltage into a DC voltage and outputs the voltage. .

  The switching circuit 1 includes four switching elements Q1, Q2, Q3, and Q4, and includes a switching element Q1 connected to the positive side of the input power supply unit Vin and a switching element Q2 connected to the negative side of the input power supply unit Vin. And a series circuit composed of a switching element Q3 connected to the positive side of the input power supply unit Vin and a switching element Q4 connected to the negative side of the input power supply unit Vin are connected in parallel to form a full bridge circuit. Has been. The switching elements Q1 to Q4 are preferably made of MOSFETs. In this case, each switching element Q1 to Q4 includes a built-in parasitic diode.

  The switching circuit 1 alternately turns on / off the pair of switching elements Q1 and Q4 and the other pair of switching elements Q2 and Q3 based on the output signal of the switching element drive circuit 2, whereby the input power supply unit Vin Is converted into an AC voltage and supplied to the rare gas discharge lamp DL.

  The dimming control circuit 3 includes a burst dimming signal generation circuit, for example, for outputting a signal for adjusting the luminance of the rare gas discharge lamp DL by burst dimming.

  The discharge lamp lighting device 10 has an inductance element L1 connected in series with the primary winding of the step-up transformer T1 on the primary side of the step-up transformer T1, and occurs in series-parallel with the rare gas discharge lamp DL. It has a parasitic capacitance (not shown). The inductance element L1 can be omitted by using the leakage inductance of the step-up transformer T1.

  Further, the discharge lamp lighting device 10 includes a dimming circuit 4 in addition to the above-described components. The present invention is characterized in that the dimming circuit 4 is connected between the input power supply unit Vin and the switching circuit 1. As described later, the dimming circuit 4 is provided, so that a simple circuit configuration is provided. However, excessive ripple noise does not occur in the output voltage obtained by converting the AC voltage of the input power source Vin, that is, the commercial AC input power into DC, and the startability is improved even when the dimming rate is small. The effect that the light control range can be expanded is exhibited.

  As shown in FIG. 1, the dimming circuit 4 includes an intermittent oscillation control circuit 5 and a dimming auxiliary circuit 6. The intermittent oscillation control circuit 5 includes a dimmer element Q5 that is a switching element and a dimmer element drive circuit 7. The dimmer auxiliary circuit 6 includes a diode D1 and first and second capacitors C1. , C2 and first and second switching elements Q6 and Q7 made of FET.

  In the intermittent oscillation control circuit 5, the dimming element Q5 has a drain electrode connected to the positive side of the input power source Vin, a source electrode connected to the anode terminal of the diode D1 of the dimming auxiliary circuit 6, and a gate electrode connected to the dimming element Q5. A pulse signal of the optical element drive circuit 7 is applied. At the time of dimming, the dimming element Q5 performs an on / off operation by a pulse signal output from the dimming element drive circuit 7.

  In the dimming auxiliary circuit 6, the diode D1 has an anode terminal connected to the drain electrode of the first switching element Q6 and the source electrode of the dimming element Q5 of the intermittent oscillation circuit 5, and a cathode terminal connected to the switching element Q1 of the switching circuit 1. Connected to the drain electrode. The first capacitor C1 has one end connected to the cathode terminal of the diode D1, the other end connected to the source electrode of the first switching element Q6, and the source electrode of the first switching element Q6 is connected to the second switching element Q7. The source electrode of the second switching element Q7 is connected to the negative electrode side of the input power supply unit Vin. The second capacitor C2 has one end connected to the cathode terminal of the diode D1 and the other end connected to the negative electrode side of the input power supply portion Vin. The gate electrodes of the first and second switching elements Q6 and Q7 are connected to the second capacitor C2. The output signal of the dimming control circuit 3 is applied.

  Hereinafter, with reference to the timing chart shown in FIG. 2, the operation of the discharge lamp lighting device 10 in the steady drive state and the dimming drive state, and the pulse voltage applied to the rare gas discharge lamp DL in each case will be described in detail. The operation of the light control circuit 4 will be described.

  2, (a) Vds (Q5) is the drain-source voltage of the dimming element Q5, and (b) V (Q6) and (c) V (Q7) are the first of the dimming auxiliary circuit 6, respectively. The output voltages of the second switching elements Q6 and Q7, (d) V (OUT1), are the output voltages of the dimming auxiliary circuit 6. (E) V (P1), (f) V (P2), (g) V (P3), (h) V (P4) are switched by switching element drive circuit 2 through switching elements Q1, Q2, Q3 of switching circuit 1. , Q4 is a driving voltage applied to each of the gate electrodes. (I) Vds (Q4) is the drain-source voltage of the switching element Q4, (j) V (DL), (k) I (DL) are the pulse voltage and pulse current applied to the rare gas discharge lamp DL, respectively. It is. Switching elements Q1 and Q4 and switching elements Q2 and Q3 are driven in the same phase.

In FIG. 2, the discharge lamp lighting device 10 is in a steady drive state during a period from t0 to t1.
In this period, as shown in FIG. 2A, the dimming element Q5 maintains the ON state (the drain-source voltage Vds (Q5) of the dimming element Q5 is low), and FIG. , (C), the first and second switching elements Q6 and Q7 of the dimming auxiliary circuit 6 are maintained in the off state (voltages V (Q6) and V (Q7) are low). As shown in FIG. 2 (d), the output voltage V (OUT1) of the dimming auxiliary circuit 6 becomes a constant DC voltage V1.

  Further, as shown in FIGS. 2E to 2H, the group of switching elements Q1 and Q4 and the group of Q2 and Q3 of the switching circuit 1 are turned on alternately by the switching element drive circuit 2. Pulse voltages V (P1), V (P4) and V (P2), V (P3) are applied so as to repeat / off.

  As shown in FIG. 2 (i), a pulse voltage having a voltage value of Vds1 is output to the drain-source voltage Vds (Q4) of the switching element Q4, and each of FIGS. 2 (j) and 2 (k) is output. As shown, a pulse voltage V (DL) having a differential waveform is applied to the rare gas discharge lamp DL, and a pulse current I (DL) flows.

  During steady driving, the energy generated by the inductance element L1 is recovered by the second capacitor C2 of the dimming auxiliary circuit 6.

Next, in FIG. 2, the discharge lamp lighting device 10 is in a dimming drive state during a period after t1.
In this period, as shown in FIG. 2A, the dimming element Q5 repeats the on / off state (the drain-source voltage Vds (Q5) of the dimming element Q5 is Low / High), and 2B and 2C, in the first and second switching elements Q6 and Q7 of the dimming auxiliary circuit 6, the dimming element Q5 is in the on state (the voltage Vds (Q5) is low). In this case, by alternately repeating the on / off operation (voltages V (Q6) and V (Q7) are High / Low), a high-frequency pulse signal is alternately output, and the dimming element Q5 is in an off state (voltage Vds ( When Q5) is High), it is turned off (voltages V (Q6) and V (Q7) are Low).

  As a result, as shown in FIG. 2 (d), the output voltage V (OUT1) of the dimming auxiliary circuit 6 is a high-frequency pulse voltage in addition to the constant DC voltage V1 when the dimming element Q5 is on. V2 is a voltage periodically superimposed in synchronization with the switching cycle of the first and second switching elements Q6 and Q7.

  As shown in FIG. 2 (i), the drain-source voltage Vds (Q4) of the switching element Q4 has a high frequency in addition to the pulse voltage having the voltage value Vds1 when the dimming element Q5 is on. The pulse voltage Vds2 becomes a voltage periodically superimposed in synchronization with the switching periods of both the first and second switching elements Q6 and Q7. As a result, as shown in FIGS. The rare gas discharge lamp DL is applied with a pulse voltage V (DL) having a differential wave shape having a voltage value Vm larger than the voltage value Vn at the steady state, and has a current value Im larger than the current value In at the steady state. A differential wave-shaped pulse current I (DL) flows.

  In this way, at the time of dimming, by supplying a higher voltage to the input part of the switching circuit 1 than in the steady state, a pulse voltage larger than that in the steady state is applied to the rare gas discharge lamp DL. A larger pulse current flows in the discharge lamp DL than in the steady state, and the current flowing in the rare gas discharge lamp DL increases from that in the steady state, so that the lighting state is stabilized and the startability is improved even when the dimming rate is small. The dimming range can be expanded.

  Further, in the discharge lamp lighting device 10 in the present embodiment, the output of the chopper control circuit is not directly controlled by the dimming circuit as in the conventional discharge lamp lighting device 100 shown in FIG. Since the output can be controlled by an independent dimming circuit, it is not necessary to design a wide bandwidth of the control system of the AC / DC power conversion circuit constituting the input power supply unit Vin in FIG. As a result, excessive ripple noise is not generated in the output of the input power supply section Vin, and the dimming range can be widened.

  As described above, the discharge lamp lighting device 10 according to the present embodiment connects the dimming circuit 4 between the input power supply unit Vin and the switching circuit 1, and the dimming circuit 4 performs the intermittent oscillation control circuit 5 during dimming. Is turned on / off, and at the time of the on operation, a voltage higher than the steady state (a voltage obtained by superimposing a high-frequency pulse voltage on the steady state DC voltage) is supplied to the input part of the switching circuit 1, thereby A pulse voltage larger than that in the steady state is applied to the DL as a trigger voltage, and as a result, a larger pulse current flows in the rare gas discharge lamp DL than in the steady state. As a result, the current flowing through the rare gas discharge lamp DL increases from the steady state, so that the lighting state is stable, and an excessive ripple noise is generated in the output of the input power supply unit Vin while having a simple circuit configuration. There is also provided a rare gas discharge lamp lighting device that can improve startability even when the dimming rate is small, can widen the dimming range, and can prevent the rare gas discharge lamp from turning off during dimming. be able to.

  In the discharge lamp lighting device 10 according to the present embodiment, the driving frequency of the intermittent oscillation control circuit 5 (that is, the driving frequency of the dimming element Q5, referred to as f4) is several hundred Hz, and the driving frequency of the dimming auxiliary circuit 6 (That is, the driving frequency of the first and second switching elements Q6 and Q7, referred to as f5) is, for example, about 200 kHz, the driving frequency of the switching circuit 1 (that is, the driving frequency of switching elements Q1 to Q4, referred to as f2). Is, for example, about several tens to 100 kHz, and the relationship of f4 <f2 <f5 is established.

  That is, the drive frequency f2 of the switching circuit 1 is higher than the drive frequency f4 of the intermittent oscillation control circuit 5 and lower than the drive frequency f5 of the dimming auxiliary circuit 6. When such a relationship is established, a high-frequency wave (adjustment frequency) that is an arbitrary frequency is not affected by the drive frequency of the switching circuit 1 when the dimming is in an on state (intermittent oscillation control circuit 5 is on). Since the pulse voltage of the frequency synchronized with the driving frequency of the optical auxiliary circuit 6 can be superimposed on the output voltage of the intermittent oscillation control circuit 5, the driving frequency of the dimming auxiliary circuit 6 is easily changed as necessary. It is possible to freely design the increase rate of the current flowing through the rare gas discharge lamp DL. The drive frequency f2 of the switching circuit 1 and the drive frequency of the dimming drive circuit 6 may be the same frequency.

  The representative embodiment of the present invention has been described above, but the present invention is not limited to the circuit configuration of the above embodiment, and various modifications can be made without departing from the spirit of the present invention. .

  For example, in the present embodiment, a full bridge configured by the switching elements Q1, Q2, Q3, and Q4 is used as the switching circuit 1. However, the present invention is not limited to such a full bridge. Alternatively, it may be constituted by a half bridge or push-pull. Also, bipolar transistors or IGBTs are used as the switching elements Q1 to Q4 of the switching circuit 1, the dimming element Q5 of the intermittent oscillation control circuit 5, and the first and second switching elements Q6 and Q7 of the dimming auxiliary circuit 6. It may be.

The intermittent oscillation control circuit 5 is not limited to the circuit configuration shown in the present embodiment, and can be replaced with another circuit as long as the same switching operation is performed.
Further, using a programmable device such as a microcomputer or DSP, the switching element drive circuit 2 is supplied with a signal V (P1) for driving the switching circuit 1 during an off period (for example, a period from t3 to t4 in FIG. 2) during dimming. ) To V (P4) can be stopped, so that the switching element drive circuit 2 can have the same function as the intermittent oscillation control circuit 5 of the dimming circuit 4. The intermittent oscillation control circuit 5 constituting the optical circuit 4 can be omitted.

  Further, in the above embodiment, the dimming auxiliary circuit 6 includes the second capacitor C2, but the second capacitor C2 is not always necessary and can be omitted. In this case, the regenerative current generated by the inductance element L1 in the steady state may be recovered by the first capacitor C1 by turning on the second switching element Q7.

1: switching circuit, 2: switching element drive circuit, 3: dimming control circuit, 4: dimming circuit, 5: intermittent oscillation control circuit, 6: dimming auxiliary circuit, 7: dimming element drive circuit, C1: first 1 capacitor, C2: second capacitor, D1: diode, DL: rare gas discharge lamp, L1: inductance element, Q1 to Q4: switching element, Q5: switching element (dimming element), Q6: first switching Element, Q7: second switching element, T1: step-up transformer, Vin: input power supply unit

Claims (6)

  An input power supply unit; a high-voltage transformer; a switching circuit connected to a primary side of the high-voltage transformer; a drive circuit that drives the switching circuit; and a dimming control circuit that generates and outputs a dimming signal. In the rare gas discharge lamp lighting device for lighting the rare gas discharge lamp connected to the secondary side of the transformer, a dimming circuit is connected between the input power supply unit and the switching circuit, The dimming signal output from the dimming control circuit is input, and at the time of dimming, a high-frequency pulse voltage whose frequency can be arbitrarily set is superimposed on a DC voltage applied in a steady state to input the switching circuit A rare gas discharge lamp lighting device is characterized in that a higher trigger voltage is applied to the rare gas discharge lamp than in a steady state by supplying to the rare gas discharge lamp.   The dimming circuit includes an intermittent oscillation control circuit and a dimming auxiliary circuit, and the intermittent oscillation control circuit is connected between the input power supply unit and the dimming auxiliary circuit and is turned on / off during dimming. The dimming auxiliary circuit supplies the input to the switching circuit with the high-frequency pulse voltage superimposed on the DC voltage applied in the steady state when the intermittent oscillation control circuit is turned off. The rare gas discharge lamp lighting device according to claim 1.   The dimming auxiliary circuit includes a diode, a first capacitor, and first and second switching elements, and one end of the diode is connected to the intermittent oscillation control circuit together with one end of the first switching element. The other end of the first capacitor is connected to one end of the switching circuit together with one end of the first capacitor, and the other end of the first capacitor is connected to one end of the second switching element together with the other end of the first capacitor. The rare gas discharge lamp lighting device according to claim 2, wherein the other end of the second switching element is connected to the negative electrode side of the input power supply unit.   The dimming auxiliary circuit further includes a second capacitor having one end connected to the other end of the diode and the other end connected to the negative electrode side of the input power supply unit together with the other end of the second switching element. The rare gas discharge lamp lighting device according to claim 3.   The intermittent oscillation control circuit has a dimming element composed of a switching element having one end connected to the positive electrode side of the input power supply unit and the other end connected to one end of the dimming auxiliary circuit, and drives the dimming element The rare gas discharge lamp lighting device according to claim 2, comprising a drive circuit.   6. The rare frequency according to claim 2, wherein a driving frequency of the switching circuit is higher than a driving frequency of the intermittent oscillation control circuit and is equal to or lower than a driving frequency of the dimming auxiliary circuit. Gas discharge lamp lighting device.

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