JP2005259454A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device suppressing generation of striation and preventing danger of electric shock. <P>SOLUTION: The discharge lamp lighting device is equipped with a rectified DC power source DC, a DC-DC conversion circuit BCU outputting DC voltage exceeding raised and smoothed 300 V, a DC-AC conversion circuit DAC converting DC voltage outputted from the DC-DC conversion circuit BUC to high frequency AC voltage, a load circuit LC containing a discharge lamp connected between output terminals of the DC-AC conversion circuit DAC, a dimmer DM of the discharge lamp, and a resistor R1 having such a resistance value that when a resistor of 1 KΩ is connected between the output end on the high voltage side of the load circuit and an earth in a no load, current flowing through the resistor of 1 KΩ is 1 mA or less and when a light control ratio of the discharge lamp in no load is 25%, DC voltage of 1 V or more is applied to the discharge lamp, and connected between the output end of the DC-DC conversion circuit and the high voltage side of the discharge lamp. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp at high frequency.

  When a fluorescent lamp is lit at a high frequency at a low temperature, a phenomenon in which a moving stripe pattern appears on the tube wall, so-called striation, occurs. In order to prevent this striation, the current value of the lamp current flowing through the fluorescent lamp is made asymmetric with positive and negative polarities (see, for example, Patent Document 1). The above-mentioned striation is likely to occur because the temperature of the discharge lamp is lowered even when the discharge lamp is turned on with a large dimming degree.

On the other hand, if the lamp current waveform is asymmetrical, a phenomenon in which the emission intensity at the tube end of the fluorescent lamp is extremely different, so-called catalysis, occurs. As a measure to prevent this catalysis, it is equipped with an electronic ballast that outputs a lamp voltage in which a DC component is superimposed on an AC component, and a discharge lamp connected to the electronic ballast. In the temperature range, the relationship between the DC component V _DC (V) of the lamp voltage and the coldest spot temperature Tc (° C.) of the discharge lamp is Tc ≧ 5 when 0 <V _DC ≦ 2, and 2 < There is known a low-temperature lighting fixture that stipulates that Tc ≧ 20 when V _DC ≦ 4 and Tc ≧ 35 when 4 <V _DC (see Patent Document 2).

According to Patent Document 2, a striation phenomenon occurs when the direct-current component _VDC of the lamp voltage of the fluorescent lamp is low and the coldest spot temperature T _C (° C.) is low. That is, since Patent Document 2 focuses on the prevention of the cataphoresis phenomenon, no consideration is given to the prevention of the striation phenomenon, so that it is insufficient as a measure for preventing both the catalysis phenomenon and the striation phenomenon. It is.

  Therefore, it has been proposed that the direct-current component of the lamp voltage of the discharge lamp be 0.5 to 1.6 V when the coldest spot temperature of the discharge lamp is 5 to 40 ° C., thereby reducing cataphoresis and striation. Both of these phenomena are prevented (see Patent Document 3).

On the other hand, when the discharge lamp is dimmed, if the dimming ratio is dimmed to a limit value of approximately 25%, for example, the lamp current is reduced, so that striation is likely to occur. When a DC component voltage is applied to the discharge lamp at this time, striation is suppressed.
Japanese Examined Patent Publication No. 64-3318 JP 2001-023781 A JP 2003-229291 A

  In Patent Document 2, a circuit configuration for applying a direct current component to a fluorescent lamp is not disclosed, and thus is unknown. In Patent Document 3, a DC component is applied to the discharge lamp by obtaining an output voltage having an asymmetric waveform using a one-stone inverter.

  On the other hand, when a high-frequency AC voltage is generated using a DC-AC conversion circuit that outputs a symmetric waveform, such as a half-bridge inverter, between the DC power supply and the discharge lamp via a resistor. If connected, a DC component can be applied.

  However, although the problem of striation is solved by connecting the resistor as described above, when the person comes into contact with the lighting fixture on which the fluorescent lamp is mounted, for example, when the lamp is replaced, the resistor and the lighting fixture are connected. A DC leakage current flows from the DC power supply to the ground through a person. For this reason, there is a risk of electric shock. In particular, when the voltage of the DC power supply exceeds 300V, the risk of electric shock becomes relatively high.

  According to the technical standards of the Electrical Appliance and Material Safety Law, it is stipulated that a ballast for lighting a discharge lamp whose rated secondary voltage exceeds 300V is an insulation transformer in principle. There are some exceptions to this. According to the inventor's investigation and examination, although it is not currently recognized as an exception, if the current that flows when a 1 kΩ resistor is connected between the output terminal and the ground is 1 mA or less, it is actually It turns out that there is no risk of electric shock. As a result of further investigation, a resistor having a resistance value within a specific range is provided in a circuit even in high-frequency lighting using a DC-AC converter that generates a high-frequency AC voltage having a symmetrical waveform. By connecting to the position, it was found that the occurrence of striations is suppressed and at the same time there is no risk of electric shock, and the present invention has been made.

  An object of the present invention is to provide a discharge lamp lighting device that suppresses the occurrence of striations and at the same time does not cause a risk of electric shock.

    The discharge lamp lighting device according to the first aspect of the present invention includes a rectified DC power source whose input terminal is connected to an AC power source and rectifies the AC voltage; and a DC voltage output from the rectified DC power source is input and boosted. A DC-DC converter circuit that outputs a smoothed DC voltage exceeding 300V; a DC-AC converter circuit that converts a DC voltage output from the DC converter circuit into a high-frequency AC voltage; and a DC-AC converter A load circuit including a discharge lamp connected between the output terminals of the circuit; dimming means for dimming and lighting the discharge lamp of the load circuit; 1 kΩ between the output terminal on the high voltage side of the load circuit and the ground when there is no load The resistance value is such that a DC voltage of 1 V or more is applied to the discharge lamp when the resistance flows and the current flowing through the resistor is 1 mA or less and the dimming ratio of the discharge lamp is 25% at the time of load. Have, DC It is characterized in that it comprises a; a resistor connected between the high voltage side output end and a discharge lamp of the direct current between the converter circuit.

  In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

  <Regarding the Rectified DC Power Supply> The rectified DC power supply is a circuit means whose input end is connected to an AC power supply, rectifies the AC voltage, converts it to a DC voltage, and outputs the DC voltage. The DC voltage output may be smoothed or non-smooth. The rectifier circuit may be any known circuit means. In the present invention, any AC power source may be used. For example, commercial AC power supplies such as 100V, 200V, 242V, and 256V can be selectively used.

  <About DC-DC converter circuit> The DC-DC converter circuit is a circuit means for converting a DC voltage into a DC voltage of a different value, and the output DC voltage exceeds 300 V in terms of effective value and is smoothed. For example, any method of step-up conversion and step-down conversion may be used. However, in general, as described above, the AC power supply voltage is often an effective value of less than 300 V, so the boost conversion method is used. The reason why the output DC voltage is limited to more than 300 V is that when it is in such a range, the risk of electric shock is relatively high, and thus the significance of the present invention is enhanced. Further, even if the output DC voltage is allowed, the instantaneous value of the DC voltage does not substantially exceed the effective value, and the generation of harmonics is reduced, which is effective.

  Further, a boost chopper can be preferably used as the DC-DC converter circuit. In this case, the output voltage can be smoothed and made substantially constant by configuring the boost ratio to be automatically adjusted according to the instantaneous value of the DC power supply voltage. Therefore, in the present invention, the input voltage of the DC-DC converter circuit may be a non-smooth DC voltage.

  <Regarding DC-AC Conversion Circuit> The DC-AC conversion circuit is a circuit means for converting a smoothed DC voltage exceeding 300 V output from the DC-DC conversion circuit into a high-frequency AC voltage. In the present invention, since the DC component of the voltage applied to the discharge lamp is obtained by a resistor described later, the high-frequency AC voltage obtained from the DC-AC converter circuit may have a symmetric waveform. A DC-AC converter circuit that outputs a symmetric waveform of a high-frequency AC voltage can employ a known circuit means having a simplified circuit configuration, such as a half-bridge inverter, and therefore a discharge lamp lighting device can be used. Inexpensive, small and lightweight. However, it is also acceptable to employ an inverter that outputs an asymmetrical high-frequency AC waveform within a certain range.

  Furthermore, inverters that can be used in the present invention will be described as follows. That is, regardless of the circuit system of the inverter, the excitation system of the main switching element provided therein may basically be either self-excited oscillation or separately-excited oscillation. When the inverter is a self-excited oscillation system, the current flowing through the lighting main circuit can be fed back as described above to drive the main switching element. On the other hand, in the case of the separately excited oscillation method, an oscillation circuit is provided, and a drive signal can be formed according to the oscillation signal output from the oscillation circuit to drive the main switching element. An oscillation signal can be generated using a microcomputer or an oscillation circuit in an IC together with the control of a high frequency output described later.

  Further, the inverter can set the output characteristics so that the high-frequency voltage that is the output changes according to the stage of operation of the discharge lamp. For example, the inverter selectively has at least a preheating mode and a starting mode as its output characteristics. The “preheating mode” is an output characteristic in which the hot cathode electrode is preheated to thermionic emission state in the pre-starting stage, and the starting voltage is set so that the discharge lamp does not start undesirably during preheating. A lower voltage is configured to be applied to the discharge lamp. The “starting mode” is an output characteristic of the inverter when starting the discharge lamp, and generates an output that promotes the starting of the discharge lamp by applying a high voltage between a pair of electrodes of the discharge lamp. After the discharge lamp is started and lit, the start mode may be maintained, or a lighting mode may be set separately. When performing dimming lighting, the control circuit is simplified by maintaining the state of the start mode. When the lighting mode is set separately from the start mode, for example, it is suitable for the case where the light is turned on in the all-light lighting state, and it is preferable that a high frequency voltage lower than that in the start mode is output. “All-light lighting” means that the discharge lamp is lit at 100% brightness preset as a discharge lamp lighting device. Therefore, the brightness at the time of rating inherent to the discharge lamp does not uniquely mean. In general, a voltage lower than the starting voltage is applied to the discharge lamp when all the lights are on. “Dimming lighting” means lighting with a brightness of less than 100%.

  Furthermore, as an output characteristic of the inverter, in addition to the preheating mode and the start mode, a start mode can be added as desired. “Start-up mode” is an output characteristic when the high-frequency inverter is turned on, and is sufficiently low so that the discharge lamp does not cause undesired operation due to a transient phenomenon caused by turning on the power, for example, the discharge lamp does not flicker instantaneously. It is preferable to be configured to output a voltage. In addition, the output voltage at the time of starting can be set so that it may change in steps or continuously.

  <Regarding the load circuit> The load circuit includes a discharge lamp connected between the output terminals of the DC-AC conversion circuit. The load circuit shapes the rectangular wave by switching into a high-frequency AC voltage into a sine wave and starts the discharge lamp. And it is a circuit means for lighting stably. That is, it includes a waveform shaping circuit, a starting circuit, and a ballast circuit. The waveform shaping circuit can be shaped into a sine wave by forming a resonance circuit that resonates with the fundamental frequency of the rectangular wave by switching. The starting circuit is allowed to adopt a known starting circuit in order to start the discharge lamp as required. For example, a filament heating transformer, a capacitor preheating circuit, or the like can be selectively used. In the case of the capacitor preheating circuit, it can be configured by connecting a capacitor in parallel with the discharge lamp via one or both filament electrodes of the discharge lamp, but the capacitor is also used as the capacitor of the resonance circuit. be able to. Further, the means for stably lighting the discharge lamp is a ballast connected in series with the discharge lamp, that is, a current limiting means, and is constituted by an appropriate value of impedance, preferably an inductance acting by an inductor. Let the lamp current flow. The inductance of the ballast can also be used as the inductance of the waveform shaping circuit.

  Any discharge lamp may be used, but a low-pressure discharge lamp such as a fluorescent lamp is suitable. Further, when a low pressure discharge lamp is provided with a hot cathode electrode, a preheating mode is provided in the output characteristics of a high frequency inverter described later, and in order to preheat the hot cathode electrode during the preheating mode, in parallel with the discharge lamp, that is, A resonant capacitor can be connected between one power supply side terminal of the pair of hot cathode electrodes and the other power supply terminal or power supply terminal of the same electrode. As a result, the resonant capacitor is connected to the lighting main circuit via at least one non-power supply side terminal of the pair of hot cathode electrodes in the discharge lamp. Thus, in the preheating mode before starting, an appropriate preheating current can be supplied to the hot cathode electrode via the resonance capacitor to preheat the electrode as required. In the case of a discharge lamp provided with a cold cathode electrode, a high resonance voltage can be applied to the discharge lamp at the start only by connecting a resonance capacitor in parallel with the discharge lamp.

  Moreover, the discharge lamp may be single or plural. In the latter case, a plurality of discharge lamps can be connected in series to a single load circuit. If a plurality of load circuits are connected in parallel, a plurality of discharge lamps can be connected in parallel.

  <Regarding Dimming Unit> In the present invention, the dimming unit is a circuit unit capable of dimming and lighting the discharge lamp of the load circuit to at least a dimming ratio of 25%. The “dimming ratio” refers to the ratio of the brightness at the time of dimming when the brightness of all-light lighting is 100%.

  The dimming means can adopt various known circuit systems as desired. For example, a frequency change method for dimming by changing the operating frequency of the DC-AC converter circuit, a frequency that is higher than the frequency of the AC power source and sufficiently lower than the frequency of the high-frequency voltage. The PWM change method that intermittently turns on and off and the voltage change method that changes the output voltage of the DC-DC converter circuit can be used alone or in combination. Furthermore, the dimming can be configured to change the dimming ratio continuously or stepwise.

  <Regarding Resistor> The resistor is connected between the output terminal on the high voltage side of the DC-DC conversion circuit and the high voltage side of the discharge lamp. (1) When a 1 kΩ resistor is connected between the output terminal of the load circuit and the ground at no load, the current flowing through the resistor is 1 mA or less. (2) The dimming ratio of the discharge lamp at the load The resistance value is such that a DC voltage of 1 V or more is applied to the discharge lamp when the voltage is 25%. In addition to the above conditions (1) and (2), it is preferable that (3) the resistor has a resistance value that minimizes power consumption by the resistor.

  The condition (1) is for preventing the danger of electric shock. This condition is obtained as a resistance value necessary for the current value obtained by dividing the peak value of the voltage between the grounds that can appear at the output terminal on the high voltage side of the load circuit at no load by 1 kΩ to be 1 mA or less. it can. Therefore, the condition (1) is proportional to the AC power supply voltage.

  The condition (2) is for suppressing flickering of the light output during dimming. This condition is proportional to the product of the discharge lamp impedance and the lamp current when the lamp is lit at a dimming ratio of 25%.

  The condition (3) is to set the resistance value so that the power consumed by the resistor during standby is 1 W at most, preferably 0.5 W or less, more preferably 0.1 W or less.

  <Operation of the Present Invention> In the present invention, by having the above-described configuration, even when a low luminous flux is lit, such as dimming with a large dimming ratio, between the electrodes of the discharge lamp. Since a voltage drop of 1 V or more occurs, the discharge becomes stable and no striation occurs. For this reason, it is possible to effectively suppress the occurrence of flickering light output and arc extinction. In addition, when replacing a lamp when there is no load, even if a person inadvertently touches the output terminal on the high voltage side of the load circuit, there is no risk of electric shock. In addition, when the resistor satisfies the condition (3), the standby power of the entire discharge lamp lighting device can be reduced to 1 W or less, and an energy saving discharge lamp lighting device can be obtained. .

    A discharge lamp lighting device according to a second aspect of the present invention includes a rectified DC power source whose input end is connected to an AC power source and rectifies the AC voltage; and a DC voltage output from the rectified DC power source is input and stepped up and smoothed. A DC-DC converter circuit that outputs a converted DC voltage; a DC-AC converter circuit that converts a smoothed DC voltage exceeding 300 V output from the DC converter circuit into a high-frequency AC voltage; and DC-AC A load circuit including a discharge lamp connected between the output terminals of the intermediate conversion circuit; dimming means for dimming and lighting the discharge lamp of the load circuit; and a nominal AC voltage of the AC power supply is 100V, 200V, 242V or 256V, The lower limit is 122 kΩ or more when the nominal AC voltage is 100 V, 245 kΩ or more when 200 V, 296 kΩ or more when 242 V, and 314 kΩ or more when 256 V Moreover, it has a resistance value for applying a DC voltage of 1 V or more to the discharge lamp when the dimming ratio of the discharge lamp of 800 kΩ or less is 25% regardless of the nominal AC voltage, and the upper limit value is between DC and DC. A resistor connected between the output terminal of the conversion circuit and the high-pressure side of the discharge lamp.

  In the present invention, the lower limit value of the resistance value of the resistor connected between the output terminal of the DC-DC converter circuit and the high voltage side of the discharge lamp is set to the nominal AC voltage of the AC power source to which the discharge lamp lighting device is connected. According to the specific number of positions. Since the lower limit value is proportional to the AC power supply voltage, the resistance value varies depending on the nominal AC voltage of the AC power supply used. On the other hand, since the upper limit value of the resistor is proportional to the product of the impedance and the lamp current when the discharge lamp is dimmed, it varies depending on the discharge lamp used.

  And in this invention, there exists an effect | action similar to the thing in Claim 1 by having comprised the said structure.

    The discharge lamp lighting device according to claim 1 or 2 described above can be used by being incorporated in a lighting device. The “illuminating device” is a broad concept including all devices that use the light emitted from the discharge lamp of the discharge lamp lighting device, and includes, for example, a lighting fixture, a marker lamp, a display lamp, and an advertisement lamp. The lighting device includes a lighting device body and a discharge lamp lighting device. The “illuminating device body” refers to the remaining part of the lighting device excluding the discharge lamp lighting device.

    According to the first and second aspects of the invention, it is possible to provide a discharge lamp lighting device that suppresses the occurrence of striation with a simple circuit configuration in which a resistor is connected to a predetermined circuit position and at the same time does not cause a risk of electric shock. it can.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

    FIG. 1 is a circuit diagram showing an embodiment for implementing a discharge lamp lighting device of the present invention. In this embodiment, the discharge lamp lighting device has an input terminal connected to an AC power source AC, a rectified DC power source DC, a DC-DC converter circuit BUC, a DC-AC converter circuit DAC, a load circuit LC, a light control means. DM and resistor R1 are provided.

  AC power supply AC consists of commercial AC power supply, for example.

  The rectified DC power source DC is composed of a full-wave rectifier circuit.

  The DC-DC converter circuit BUC is composed of a boost chopper. The step-up chopper includes an inductor L1, a switching element Q1, a chopper control circuit CCC, a diode D, and a smoothing capacitor C1. One end of the inductor L1 is connected to the positive electrode of the DC output end of the rectified DC power source DC, and the other end is connected to the switching element Q1. The switching element Q1 is made of a MOSFET and is connected in series with the inductor L1 and then connected between the DC output terminals of the rectified DC power supply DC. The chopper control circuit CCC generates a gate drive signal for the switching element Q1 and applies it between the gate and source of the switching element Q1, and automatically sets the oscillation frequency of the gate drive signal according to the instantaneous value of the power supply voltage. By controlling, the power factor is improved. The diode D and the smoothing capacitor C1 are connected in series and then connected in parallel between the drain and source of the switching element Q1. Thus, a DC voltage boosted and smoothed between both ends of the smoothing capacitor C1 is output from the DC-DC conversion circuit BUC.

  The DC-AC converter circuit DAC is composed of a half-bridge inverter, and includes an inverter main circuit INV and a control circuit ICC. The inverter main circuit INV includes a series circuit of a pair of switching elements Q2 and Q3. A series circuit of the pair of switching elements Q2 and Q3 is connected in parallel to the smoothing capacitor C1 of the DC-DC converter circuit BUC. Each of the pair of switching elements Q2 and Q3 is formed of an N-type MOSFET.

  The control circuit ICC includes a control circuit main body ICC1 and a lamp mounting detection circuit LD, generates a gate drive signal for the DC-AC conversion circuit DAC, and adjusts the frequency of the gate drive signal in response to the dimming means DM described later. Change. The control circuit main body ICC1 indicates the remaining part obtained by removing the lamp mounting detection circuit from the control circuit CC. The LD lamp mounting detection circuit LD includes a voltage dividing circuit connected between a pair of electrodes E of the discharge lamp DL, which will be described later, and the non-power supply side terminals of the E. The voltage divider circuit is composed of a pair of resistors R2 and R3 and a smoothing capacitor C5 connected in series, and the voltage across the resistor R3 is smoothed by the smoothing capacitor C5 and output to the control circuit body ICC1.

  The load circuit LC is connected between both ends of the switching element Q3 that is between the output ends of the DC-AC converter circuit DAC, and includes a pair of DC cut capacitors C2, C3, an inductor L2, a resonant capacitor C4, and a discharge lamp DL. It is configured to include. That is, the DC cut capacitor C2, the inductor L2, the resonant capacitor C4, and the DC cut capacitor C3 form a series circuit. The inductance of the inductor L2 and mainly the resonance capacitor C4 form a series resonance circuit. Further, the discharge lamp DL is connected in parallel to the resonance capacitor C4 of the series resonance circuit, and the pair of filament electrodes E and E of the discharge lamp DL are connected in series with the resonance capacitor C4, thereby providing a filament electrode heating circuit. Forming.

  The light control means DM operates this to control the control circuit ICC of the DC-AC converter circuit DAC, for example, to increase the oscillation frequency of the gate drive signal. Thereby, the lamp current flowing through the discharge lamp DL is reduced, and the discharge lamp DL is dimmed.

  The resistor R1 is connected between the output terminal on the high voltage side of the DC-DC conversion circuit BUC and the high voltage side of the discharge lamp DL, for example, the connection point of the DC cut capacitor C2 and the inductor L2. When no load is applied, when the resistor R4 of 1 kΩ is connected between the output terminal of the load circuit LC, for example, the power supply side terminal of the electrode E on the high voltage side of the discharge lamp DL and the ground, the current flowing through the resistor R4 is 1 mA or less. And a resistance such that a DC voltage of 1 V or more appears between the pair of electrodes E and E of the discharge lamp DL when the dimming means DM is operated during load and the dimming ratio is 25%. Is set to a value.

  Then, when the AC input terminal of the rectified DC power supply DC is connected to the AC power supply AC, a boosted and smoothed DC voltage is output between the output terminals of the DC-DC converter circuit BUC. . Then, the DC-AC converter circuit DAC operates by applying the DC voltage, and a high-frequency voltage is output between its output terminals. The high-frequency voltage is applied to the load circuit LC, the filament electrode heating circuit heats the pair of filament electrodes of the discharge lamp DL, preheats the filament electrodes, and then starts the discharge lamp DL. As a result, the discharge lamp DL is lit at a high frequency.

AC power supply: 242V commercial AC power supply Output voltage of DC-DC converter circuit BUC: 410V when operating, 342V when no load
Discharge lamp DL: FHF32 type fluorescent lamp Resistor R1: Resistance value 500 kΩ
Electrical characteristics: 0.744 mA of current flowing through the resistor R4 at no load,
DC voltage 1.6V applied to the discharge lamp DL when the dimming ratio is 25%
FIG. 7 is a bottom view showing an open-bottomed implantable device as an embodiment of a lighting device incorporating the discharge lamp lighting device of the present invention. In the figure, 11 is a luminaire body, 12 is a reflector, and 13 and 13 are fluorescent lamps.

  The luminaire main body 11 is formed by pressing a metal plate into an elongated rectangular shape, and its lower surface is open. And the standing edge 11a contact | abutted to a ceiling surface is formed in the periphery.

  The reflection plate 12 is formed by press-molding a metal plate to have a mountain-shaped cross section, and the surface is covered with a white coating film. And the fluorescent lamp 13 is accommodated in the inside of the lighting fixture main body 11 so that it may be in the state surrounded by the cross-sectional mountain-shaped part except the lower surface side part.

  Each of the fluorescent lamps 13 and 13 is of the FHF32 type, and has a tube diameter of 25.5 mm, a tube length of 1198 mm, a rated lamp power of 32 W / 45 W, and a rated lamp current of 0.255 A / 0.425 A.

  Inside the luminaire main body 11, a discharge lamp lighting device (not shown) is disposed on the back side of the reflector 12.

The circuit diagram which shows one form for implementing the discharge lamp lighting device of this invention The bottom view which shows the lower surface open | release type implantation implement as one form of the illuminating device incorporating the discharge lamp lighting device of invention

Explanation of symbols

  AC ... AC power supply, DC ... rectified DC power supply, BUC ... DC-DC conversion circuit, DAC ... DC-AC conversion circuit, LC ... load circuit, DM ... light control means, R1 ... resistor

Claims (2)

A rectified DC power source whose input terminal is connected to an AC power source and rectifies the AC voltage;
A DC-DC converter circuit that inputs a DC voltage output from a rectified DC power supply, boosts the DC voltage, and outputs a smoothed DC voltage;
A DC-AC converter circuit for converting a smoothed DC voltage exceeding 300 V output from the DC converter circuit into a high-frequency AC voltage;
A load circuit including a discharge lamp connected between the output terminals on the high voltage side of the DC-AC converter circuit;
Dimming means for dimming the discharge lamp of the load circuit;
When a 1 kΩ resistor is connected between the output terminal of the load circuit and the ground when there is no load, the current flowing through the resistor is 1 mA or less, and the dimming ratio of the discharge lamp is 25% when loaded A resistor having a resistance value for applying a DC voltage of 1 V or more to the discharge lamp and connected between the output terminal of the DC-DC converter circuit and the high voltage side of the discharge lamp;
A discharge lamp lighting device comprising: A rectified DC power source whose input terminal is connected to an AC power source and rectifies the AC voltage;
A DC-DC converter circuit that inputs a DC voltage output from a rectified DC power supply, boosts the DC voltage, and outputs a smoothed DC voltage;
A DC-AC converter circuit for converting a smoothed DC voltage exceeding 300 V output from the DC converter circuit into a high-frequency AC voltage;
A load circuit including a discharge lamp connected between the output ends of the DC-AC converter circuit;
Dimming means for dimming the discharge lamp of the load circuit;
When the nominal AC voltage of the AC power supply is 100V, 200V, 242V or 256V, and the lower limit value is 122 kΩ or more when the nominal AC voltage is 100 V, 245 kΩ or more when 200 V, 296 kΩ or more when 256 V, 256 V 314 kΩ or higher and the upper limit value is 820 kΩ or lower for any nominal AC voltage, and a DC voltage of 1 V or higher is applied when the dimming ratio of the discharge lamp is 25% under load. A resistor connected between the output end of the DC-DC converter circuit and the high-pressure side of the discharge lamp;
A discharge lamp lighting device comprising:

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