JPH1167478A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adapt to multiple kinds of power sources by means of reducing input current distortion by setting impedance elements so that the input current wave form from an a.c. power source should become a sinusoidal wave in response to the power consumption between the maximum and minimum values of multiple kinds of rated power consumption. SOLUTION: An input current from an a.c. power source AC is rectified by a diode bridge rectifier DB by way of a high frequency suppressing filter F and is applied to a load circuit composed of switching elements Q1 , Q2 controlled by an integrated circuit IC1 , a resonating inductor L2 , a direct current cutting capacitor C3 and the like via diodes D3 , D4 , a smoothing capacitor C0 , feedback capacitor C5 and the like so as to obtain high frequency voltage which is boosted by a transformer T1 and applied to a filament of a discharge lamp La . In the discharge lamp lighting device, the capacitor C5 used as an impedance element is so set that the input current wave form of the a.c. power source AC becomes sinusoidal at an intermediate power consumption amount of multiple kinds of different rated power consumption amounts of multiple kinds of discharge lamps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art Conventionally, there has been provided a discharge lamp lighting apparatus in which electric power is supplied from an AC power supply such as a commercial power supply and a discharge lamp as a load is lit with a high frequency output. In this type of discharge lamp lighting device, it is common to use an inverter circuit that performs DC-AC conversion, and in order to suppress an increase in input current distortion and to reduce an input power factor, a DC circuit is provided upstream of the inverter circuit. -Many have a chopper circuit for performing DC conversion.

As disclosed in Japanese Patent Application Laid-Open No. 1-120797, a switching element is provided separately from an inverter circuit, and a part of a resonance current generated in the inverter circuit is returned to an AC power supply. is there. In these configurations, a switching element is required in addition to the switching element forming the inverter circuit in order to suppress an increase in input current distortion, and thus there is a problem that the number of parts increases and the circuit configuration becomes complicated. ing.

Therefore, it has been considered to suppress an increase in input current distortion without providing a switching element in addition to the switching elements constituting the inverter circuit. For example, the circuit shown in FIG. 6 operates in the same manner as the circuit disclosed in Japanese Patent Application Laid-Open No. 5-38161, in which the DC output terminal of the rectifier DB for full-wave rectification of the AC power supply AC is connected to the smoothing capacitor C0. In between, a relatively small capacitor C
5 and a diode D5 are inserted in parallel, and a pair of switching elements Q1 is connected between both ends of a smoothing capacitor C0.
, Q2. The diode D5 is inserted in a direction in which a charging current flows from the rectifier DB to the smoothing capacitor C0, and has a cathode connected to the negative electrode of the DC output terminal of the rectifier DB. Also, both switching elements Q1,
One end of an inductor L2 is connected to the connection point of Q2, and a series circuit of a discharge lamp La and a DC cut capacitor C3 for coupling is connected between the other end of the inductor L2 and the cathode of a diode D5. A capacitor C2 is connected in parallel to the lamp La.

In this configuration, both switching elements Q 1,
When Q2 is controlled to be turned on and off alternately, a pulse current can be passed from the rectifier DB at a high frequency due to the relationship between the voltage across the smoothing capacitor C0, the output voltage of the rectifier DB, and the voltage across the capacitor C5. AC power supply A
If a filter for blocking high frequency is provided between C and the rectifier DB, the input current waveform from the AC power supply AC can be made substantially continuous. That is, an increase in input current distortion can be suppressed.

In this circuit configuration, charging / discharging of the capacitor C5 greatly contributes to suppression of an increase in input current distortion from the AC power supply AC. Therefore, this operation will be described in more detail. In the normal operation, there are six operating states shown in FIG. 7 during one cycle of ON / OFF of the switching elements Q1 and Q2. FIG. 7A shows a state in which the switching element Q1 is on and the switching element Q2 is off. At this time, the voltage across the smoothing capacitor C0 is higher than the output voltage of the rectifier DB, and the voltage across the capacitor C5 is the smoothing capacitor. Assuming that the voltage is between C0 and the output voltage of the rectifier DB, the smoothing capacitor C0 is used as a power source, and as shown by the arrow, as shown by the arrow, the smoothing capacitor C0, the switching element Q1, the inductor L2, the discharge lamp La, the capacitor C3, and the capacitor C5
Current flows through the path of the smoothing capacitor C0, and the capacitor C0
5 is charged.

When charging is performed until the voltage across the capacitor C5 becomes substantially equal to the voltage across the smoothing capacitor C0,
As shown by the arrow in FIG. 7B, a current flows through a route of the rectifier DB, the switching element Q1, the inductor L2, the discharge lamp La, the capacitor C3, and the rectifier DB. This state continues until the switching element Q1 is turned off. When the switching element Q1 is turned off, a regenerative current flows due to the energy stored in the inductor L2. At this time, since the voltage across the smoothing capacitor C0 and the voltage across the capacitor C5 are still substantially equal, the rectifier DB, the smoothing capacitor C0, the switching element Q2, the inductor L2, and the discharge lamp as shown by arrows in FIG. A regenerative current flows through the path of La-capacitor C3-rectifier DB. The current flowing through the switching element Q2 actually passes through a regenerative diode provided in parallel with the switching element Q2, but the diode is not shown. In this state, the input current from the AC power supply AC flows. When the switching element Q1 is turned off, the switching element Q2 is turned on.

When the regenerative current caused by the inductor L2 stops flowing, as shown by the arrow in FIG. 7D, the capacitor C3 is used as a power source, and the capacitor C3-discharge lamp La-inductor L2-switching element Q2-capacitor C5-capacitor C3. A current flows through the path, and the capacitor C5 is discharged. After discharging the capacitor C5, a diode D is used instead of the capacitor C5 as shown by an arrow in FIG.
5 flows through the path.

Thereafter, when the switching element Q2 is turned off, as shown by an arrow in FIG.
A regenerative current due to the stored energy flows through the path of the capacitor C3, the discharge lamp La, the inductor L2, the switching element Q1, the smoothing capacitor C0, the diode D5 and the capacitor C3. The current flowing through the switching element Q1 is
Actually, it passes through a regenerative diode provided in parallel with the switching element Q1, but the diode is not shown. When the switching element Q2 is turned off, the switching element Q1 is turned on.

When the regenerative current caused by the inductor L2 stops flowing, the operation returns to the state shown in FIG. 7A in which the current flows using the smoothing capacitor C0 as a power supply, and the above operation is repeated in a steady state. Therefore, an alternating current flows through the discharge lamp La, and a period occurs in which the input current flows from the AC power supply AC for each ON / OFF cycle of the switching elements Q1 and Q2, so that the switching elements Q1 and Q2 are turned on and off at a high frequency. This allows the input current to flow at a high frequency.

Now, assume the state of FIG.
The states of (a) to (e) are denoted by. The sign is given in this way in order to make the voltage between both ends of the capacitor C5 rise from the minimum value and correspond to the fall to the minimum value. If the discharge lamp La has a relatively heavy load, the voltage across the capacitor C5 changes as shown in FIG. 8B according to the output voltage of the rectifier DB. That is, the voltage across the capacitor C5 is equal to the rectifier D
The output voltage of B (FIG. 8A) is superimposed with a high frequency. Therefore, if the high-frequency component is removed by the filter, the input current waveform passes through the center of each cycle of the waveform in FIG. 8B, and the input current distortion is improved. FIG. 8C shows the voltage across the smoothing capacitor C0.

By the way, according to FIG. 8, the time of the valley (near zero volt) of the output voltage waveform of the rectifier DB is longer than the peak (near the peak value),
It can be seen that the time of, is shortened. ,
Is a period during which the voltage across the capacitor C5 changes between the voltage across the smoothing capacitor C0 and the output voltage of the rectifier DB. At the valley of the output voltage of the rectifier DB, the voltage between the both ends of the smoothing capacitor C0 and the rectifier This is because the difference from the output voltage of DB becomes large. In this state, the voltage across the capacitor C5 is clamped by the voltage across the capacitor C0, so that it does not become higher than the voltage across the smoothing capacitor C0. In that sense, the portion higher than the voltage across the smoothing capacitor C0 is indicated by a broken line.

However, near the zero-cross point of the voltage waveform of the AC power supply AC, as shown in FIG. 9A, the input current (A) becomes relatively small and the voltage (B) across the capacitor C5 becomes sinusoidal. In the vicinity of the peak point of the voltage waveform, as shown in FIG. 9B, the input current (a) becomes relatively large and the charging period of the voltage (b) across the capacitor C5 becomes short.

Here, when the discharge lamp La is of one type and the AC power supply AC is of one voltage, if the peak of the output voltage waveform of the rectifier DB is designed to be a sine wave, the input current is stopped. The input current distortion can be prevented from increasing without generating a period or causing a jump in the input current. As is apparent from the above description, in the configuration shown in FIG. 6, the charging / discharging of the capacitor C5 greatly affects the input current waveform, and if the charging time of the capacitor C5 is short, the high-frequency current flowing into the rectifier DB is reduced. As the input current waveform increases, the input current waveform becomes trapezoidal. Conversely, if the charging time of the capacitor C5 is long, the high-frequency current flowing into the rectifier DB decreases, and a pause period occurs in the input current waveform. In other words, if an attempt is made to obtain a sinusoidal waveform without any pause or jump as the input current waveform, the capacitor C
5 and the operating frequency (the switching frequency of the switching elements Q1, Q2) must be properly set.

[0015]

However, in the circuit configuration shown in FIG. 6, when it is intended to support a plurality of types of discharge lamps La having different rated power consumptions, an inverter circuit supplies the discharge lamps La to the discharge lamps La. The balance between the voltage and the current that can be applied is lost. As a result, when the discharge lamp La has a light load, the capacitor C5 may not be sufficiently charged. If the above-described six states are repeated without sufficiently charging the capacitor C5, FIG.
A quiescent period occurs in the input current waveform like 0 (c). When the discharge lamp La becomes heavily loaded, the capacitor C5 is charged in a short time, the input current waveform becomes trapezoidal, and the current value jumps as shown in FIG. Become. Here, if the load is appropriate, the input current has a sine wave shape as shown in FIG.

If the operating frequency of the switching elements Q1 and Q2 is set higher than during rated lighting, such as during dimming lighting, the capacitor C5 may not be sufficiently charged,
The charging of the capacitor C5 is performed in a shorter time than usual, and the balance between the supply side and the discharge lamp La as a load is lost. On the other hand, in the circuit configuration shown in FIG. 6, even when trying to correspond to a plurality of types of AC power supplies AC having different voltages, a pause period or a jump occurs in the input current waveform. That is, if the voltage of the AC power supply AC is higher than the optimum value, the voltage across the capacitor C5 reaches the peak even near the zero-cross point of the voltage waveform before the voltage reaches the peak.
The state shifts to the operation state (FIG. 8) of FIG.
And the jump of the input current waveform occurs. Conversely, if the voltage of the AC power supply AC is lower than the optimum value,
Even near the peak value of the voltage waveform, the voltage across the capacitor C5 is no longer clamped, and the charging time of the capacitor C5 is prolonged, causing a pause in the input current waveform.

As described above, when a discharge lamp having different rated power consumption is used, when dimming lighting is performed, when a plurality of types of AC power supplies AC having different voltages are used, a pause period may occur in an input current waveform. This causes a problem that a jump occurs in the input current waveform. By the way, in order to solve this kind of problem at the time of dimming lighting, FIG.
As shown in the figure, the capacitor C5a and the switching element Q3
Is connected in parallel with the capacitor C5, and the switching elements Q1, Q
It is considered that the switching element Q3 is turned off when the operating frequency of the second element is set high. That is, the switching element Q3 is turned on at the time of rated lighting, and the switching element Q3 is turned off at the time of dimming lighting to reduce the capacitance component connected in parallel with the diode D5. Also, the capacitance component connected in parallel with the diode D5 is sufficiently charged. With this configuration, it is possible to prevent a pause period from occurring in the input current waveform even under a light load such as during dimming lighting.

However, in order to adopt this type of configuration, a bidirectional switching element is required as the switching element Q3.
Is generally more expensive than a unidirectional switching element, and in addition to the switching element Q3, a capacitor C5a is added and the switching element Q3
3 also requires a control circuit, which increases the number of parts and leads to higher costs.

The phenomenon that a pause period occurs in an input current waveform or a jump occurs in an input current waveform depending on the voltage of an AC power supply AC can be dealt with by designing a circuit to correspond to each voltage. However, if products with different circuit constants are manufactured for the difference in specifications of only the voltage of the AC power supply AC, the number of parts increases, and production management and inventory management for products with different specifications are required. This leads to increased manufacturing and inventory costs.

The present invention has been made in view of the above circumstances, and has as its object to cope with a plurality of types of discharge lamps having different rated power consumption without causing a pause or a jump in an input current waveform. Another object of the present invention is to provide a discharge lamp lighting device capable of supporting a plurality of types of AC power supplies having different voltages.

[0021]

According to a first aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and an alternately connected capacitor between both ends of the smoothing capacitor. A series circuit of a pair of switching elements that are turned on and off, and a loop circuit including a load circuit including one switching element, a discharge lamp and a resonance circuit, a DC cut capacitor, and an impedance element. A plurality of different types of discharge lamps can be used, and the input current waveform from the AC power supply is sinusoidal when the power consumption is between the maximum and minimum values of the rated power consumption of the available types of discharge lamps. The impedance element is set so that According to this configuration, the impedance element is set so that the input current waveform is sinusoidal when the power consumption is between the maximum value and the minimum value of the rated discharge power of the usable discharge lamp. The degree of increase in input current distortion is relatively small in both the cases where the maximum rated power consumption is used and the case where the minimum discharge power is used among the possible discharge lamps, and there is no particular change in the configuration. There is an advantage that input current distortion can be reduced as a whole only by setting circuit constants.

According to a second aspect of the present invention, in the first aspect of the present invention, the input current waveform from the AC power supply is near an intermediate value between the maximum value and the minimum value of the rated power consumption of a plurality of types of discharge lamps that can be used. The impedance element is set to have a sine wave shape. According to this configuration, the degree of the increase in the input current distortion is substantially equal for both the maximum and the minimum rated power consumption of the available discharge lamps, and the input current distortion as a whole is Can be suppressed from increasing significantly.

According to a third aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and a pair of alternately connected ON / OFF connected between both ends of the smoothing capacitor. It is composed of a series circuit of switching elements, one switching element, a load circuit including a discharge lamp and a resonance circuit, and a loop circuit including a DC cut capacitor and an impedance element, and is used for a plurality of types of AC power supplies having different voltages. It is possible to set the impedance element so that the input current waveform from the AC power supply becomes sinusoidal when the voltage is between the maximum value and the minimum value of the voltages of the plurality of types of available AC power supplies. is there. According to this configuration, the impedance element is set so that the input current waveform becomes a sine wave when the voltage is between the maximum value and the minimum value of the voltage of the available AC power supply. The degree of increase in input current distortion is relatively small in both the case of using the largest voltage and the case of using the smallest voltage among the power supplies, and only the setting of the circuit constant is performed without any particular change in the configuration. This has the advantage that the input current distortion can be reduced as a whole.

According to a fourth aspect of the present invention, in the third aspect of the invention, the input current waveform from the AC power supply has a sinusoidal waveform near an intermediate value between the maximum value and the minimum value of the plurality of types of usable AC power supplies. The impedance element is set so that According to this configuration, the degree of the increase in the input current distortion is substantially the same for both the maximum and the minimum voltage among the available AC power supplies, and the input current distortion is greatly increased as a whole. A significant increase can be suppressed.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the impedance element is a capacitor. This configuration is a preferred embodiment.
According to a sixth aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and a pair of switching elements connected between both ends of the smoothing capacitor and alternately turned on and off. A series circuit;
It consists of one switching element, a load circuit including a discharge lamp and a resonance circuit, a loop circuit including a DC cut capacitor and an impedance element, and a transformer circuit in which the input voltage to the rectifier is variable. A plurality of different types of discharge lamps can be used, and the higher the rated power consumption, the higher the output voltage of the transformer circuit is set. According to this configuration, since the input voltage to the rectifier is adjusted by the transformer circuit in accordance with the rated power consumption of the discharge lamp that can be used, an increase in input current distortion due to a change in the rated power consumption of the discharge lamp is canceled by the transformer circuit. can do.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, a load detection circuit for detecting the power consumption of the discharge lamp is added, and as the power consumption of the discharge lamp detected by the load detection circuit increases, the voltage of the transformer circuit increases. The output voltage is set high.
With this configuration, the output voltage of the transformer circuit is automatically adjusted according to the power consumption of the discharge lamp.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) In this embodiment, a plurality of types of discharge lamps having different rated power consumptions are supported. Hereinafter, a discharge lamp having a large rated power consumption is referred to as a heavy load discharge lamp, and a discharge lamp having a small rated power consumption is referred to as a light load discharge lamp. Further, among the discharge lamps used, the discharge lamp having the highest rated power consumption is called the heaviest load discharge lamp, and the discharge lamp having the lowest rated power consumption among the discharge lamps used is called the lightest load discharge lamp.

Thus, in the present embodiment, in the circuit configuration shown in FIG. 6, a jump occurs in the input current waveform when the heaviest load discharge lamp is used, and a pause period occurs in the input current waveform when the lightest load discharge lamp is used. The circuit constant (capacitor C5) is set so as to cause the following. That is, in the input current waveform, the critical point at which the transition between the jump and the pause period is set to be between the time of using the heaviest load discharge lamp and the time of using the lightest load discharge lamp.

Specifically, the circuit shown in FIG. 1 is employed, and a rectifier DB comprising a diode bridge is connected to an AC power supply AC via a high frequency blocking filter F, and a DC output terminal of the rectifier DB is provided. A pair of diodes D between
3, a smoothing capacitor C0 is connected via D4.
Further, a MOSFET is connected between both ends of the smoothing capacitor C0.
A series circuit of a pair of switching elements Q1 and Q2 is connected. One switching element Q2 includes a DC cut capacitor C3, a resonance inductor L2, a resonance capacitor C2, and a feedback capacitor C5. A series circuit is connected in parallel. The discharge lamp La is composed of a transformer T1 having a primary winding connected between both ends of a capacitor C2.
Connected to the next side. The transformer T1 has a preheating winding, and the filament of the discharge lamp La is connected to the preheating winding via capacitors C61 and C62. A DC cut capacitor C8 is inserted in the path from the secondary winding of the transformer T1 to the filament of the discharge lamp La.

The switching elements Q 1 and Q 2 are integrated circuits for control (using LGS566 manufactured by SGS Thomson).
It is turned on and off alternately by a control signal from IC1. The control integrated circuit IC1 is driven by a control power supply E.
Further, a detection circuit for detecting a zero cross point of the voltage waveform of the AC power supply AC based on the output voltage of the rectifier DB is provided, and the on / off timing of the switching elements Q1, Q2 is determined based on the zero cross point.

Although the circuit configuration shown in FIG. 1 is a modification of the circuit configuration shown in FIG. 6, the basic operation is the same, and the time required for charging the capacitor C5 charged and discharged at a high frequency under a heavy load. And the input current waveform jumps,
Conversely, when the load is light, the time required for charging the capacitor C5 becomes longer, and a pause occurs in the input current. That is, the input current distortion increases under both light and heavy loads.

In this embodiment, there are three types of discharge lamps La (FLR40S, FLR40S / 36, FLR32S).
Shall be used. In this case, since the FLR 40S is the heaviest load and the FLR 32S is the lightest load, when the FLR 40S / 36 is used, FIG.
As shown in (b), the capacitor C5 is set so that an idle period and a jump hardly occur in the input current waveform. In such a setting, when FLR32S is used, FIG.
As shown in FIG. 2C, a pause period occurs, and when the FLR 40S is used, some jumps occur as shown in FIG. 2A, but the degree thereof is relatively small. By setting such conditions, the input current distortion could be suppressed to 10% or less regardless of which discharge lamp La was used.

Assuming that the capacitor C5 is set so as to prevent a pause or a jump from occurring at the heaviest load, the power supplied from the inverter circuit to the load (discharge lamp La) becomes excessive, and the charging and discharging time of the capacitor C5 is increased. Becomes shorter, and when the lightest load is used, the pause period of the input current waveform becomes longer and the input current distortion becomes larger. If the capacitor C5 is set so as to prevent a pause or a jump from occurring at the lightest load, the jump of the input current waveform increases when the heaviest load is used, and the input current distortion increases. As described above, if the capacitor C5 is set so that the input current distortion is minimized at a load close to one of the heaviest load and the lightest load among a plurality of types of discharge lamps La to be used, the other loads are not used. Since the input current distortion becomes large, it is desirable to set the capacitor C5 so that the input current distortion is minimized at a load between the heaviest load and the lightest load (actually, near the middle). It should be noted that the discharge lamp La is not limited to the above-described combination, and the number of types may be plural. In any case, by setting the critical point between the state in which the jump occurs in the input current waveform and the state in which the idle period occurs, near the midpoint when the heaviest load and the lightest load are used, the input current distortion is reduced. The increase can be suppressed.

(Embodiment 2) As shown in FIG. 3, this embodiment embodies the circuit configuration of the conventional configuration shown in FIG. 6, and includes a control integrated circuit for driving the switching elements Q1, Q2. The IC uses IR2155 from IR. The control power supply for driving the control integrated circuit IC is obtained by converting the DC output of the rectifier DB to a constant voltage with the resistor R1 and the Zener diode ZD1, and smoothing the DC output with the smoothing capacitor C1. The other configuration is the same as the conventional configuration shown in FIG. 6, and the capacitor C5 is selected in the same manner as in the first embodiment. In this embodiment, a diode D6 is provided instead of the diodes D3 and D4 in the first embodiment.

In the first and second embodiments, it has been proposed to suppress an increase in input current distortion with a simple structure in a discharge lamp lighting device capable of handling a plurality of discharge lamps La having different rated power consumption. The same applies to a case where an increase in input current distortion is suppressed in a discharge lamp lighting device that can support a plurality of different AC power supplies AC. That is, assuming that the voltages of the target AC power supply AC are 200 V and 240 V, when the voltage is 240 V, the capacitor C5 is rapidly charged and the input current waveform is likely to jump. Here, assuming that the capacitor C5 is selected so that the input current waveform becomes a sine wave when the voltage of the AC power supply AC is 240V, when the voltage is 200V, the charging of the capacitor C5 is insufficient and the idle period becomes long. That is, at 200 V, the input current distortion increases considerably.

Therefore, the capacitor C5 is set so that the input current waveform becomes sinusoidal at a voltage near the middle between the minimum value and the maximum value of the voltage range to be used. AC power supply A
If the voltage of C is 200 V and 240 V, for example, 2
The capacitor C5 is set so that the input current waveform becomes sinusoidal at 20V. In such a setting, 240
In the case of V, a jump occurs in the input current waveform, and in the case of 200 V, a pause period occurs in the input current waveform, but the degree thereof is relatively small, and the increase in input current distortion is suppressed as a whole. . The voltage value of the AC power supply AC to be used is not limited to the above-described value, and three or more voltage values may be set in the same manner. That is, the capacitor C5 is set so that the input current waveform becomes sinusoidal at a value near the middle between the maximum value and the minimum value of the voltage values used.
Is set, the increase in input current distortion can be relatively reduced at all voltages.

(Embodiment 3) In the above-described embodiment, it has been proposed to set the capacitor C5 to an optimum value in order to suppress an increase in input current distortion, but in this embodiment, the rated consumption of the discharge lamp La is A configuration is shown in which, when the power changes, the input current distortion is suppressed by increasing the input voltage to the rectifier DB so as to cancel the influence of the change on the input current distortion. That is, in the circuit configuration of FIG. 6, during rated lighting, a jump occurs in the input current waveform under a heavy load, and a pause occurs in the input current waveform under a light load. On the other hand, when the voltage of the AC power supply AC increases, a pause period occurs, and when the voltage decreases, a jump occurs. Therefore, as shown in FIG. 4, the rectifier D
B, a voltage transformer circuit 11 for raising or lowering the voltage of the AC power supply AC is provided.
1 is changed. In FIG. 4, the DC power supply 13 is shown in FIG. 6 as a portion mainly including a rectifier DB and a smoothing capacitor C0, and the inverter circuit 14 is shown as switching elements Q1 and Q2 as main components. This section converts the voltage between both ends of the smoothing capacitor C0 into a high-frequency AC voltage.

When a heavy load is detected by the load detection circuit 12, the input voltage to the rectifier DB is boosted by the transformer circuit 11 compared to when a normal load is used, and a light load is detected by the load detection circuit 12. Transformer circuit 11 when detected
The output voltage is lowered more than when a normal load is used. For example, the FLR40S and FLR40S / 36 which are rapid tubes are used as the discharge lamp La. When the FLR40S is used, the output voltage of the transformer circuit 11 is set to 220V, and when the FLR40S / 36 is used, the output voltage of the transformer circuit 11 is set to 200V. You do it.

If the configuration shown in FIG. 4 is represented by a concrete circuit, it can be configured as shown in FIG. 5, for example. The circuit shown in FIG. 5 has a configuration in which a transformer circuit 11 and a load detection circuit 12 are added to the circuit shown in FIG. Power is supplied to the discharge lamp La via a transformer (insulating transformer) T1, and the load detection circuit 12 determines the magnitude of the load based on the output of a detection winding provided in the transformer T1.

That is, the load detection circuit 12 rectifies the output of the detection winding of the transformer T1 with the diode D3, smoothes the output of the diode D7 with the resistor R7 and the capacitor C7, and furthermore, compares the voltage between both ends of the capacitor C7 with the comparator CP1. Is compared with the reference voltage Vref. The voltage across the capacitor C7 increases as the load increases. FLR40S and FLR40S /
36, the reference voltage Vref
Indicates that the output of the comparator CP1 is H when the FLR is 40S.
Level, and the output of the comparator CP1 is set to the L level at the time of the FLR 40S / 36.

On the other hand, the transformer circuit 11 comprises a step-up transformer T 2 having a tap on the secondary winding, and a switch element SW for switching the tap according to the output of the load detection circuit 12. An electromagnetic relay is used for the switch element SW. The tap of the step-up transformer T2 is provided with a tap corresponding to 200 V and a tap corresponding to 220 V. The switch element SW selects the tap of 220 V when the output of the load detection circuit 12 is at the H level, and selects the tap of L at the L level. If there is 2
Select the 00V tap.

In short, if the discharge lamp La is the FLR 40S, a 220V tap is selected, and the FLR 40S / 36 is selected.
In this case, a tap of 200 V is selected. With such an operation, the input current waveform can be kept substantially sinusoidal for a plurality of types of discharge lamps La having different rated power consumption, and an increase in input current distortion can be suppressed.

In this embodiment, a step-up transformer T2 having a tap on the secondary winding is used as the transformer circuit 11, but a chopper circuit (DC-DC) is provided downstream of the rectifier DB.
A converter may be provided to control the voltage across the smoothing capacitor C0 by controlling the chopper circuit.
Any type of chopper circuit may be used, but if a reverse polarity (Buck-Boost) type is used, the voltage can be changed over a wide range. In order to switch the output voltage of the transformer circuit 11 or to switch the output voltage of the chopper circuit, the load detection circuit 1
2 may not be provided, and switching may be performed manually. To detect the magnitude of the load, the lamp current may be detected instead of the lamp voltage of the discharge lamp La, or the resonance current flowing through the inverter circuit 14 may be detected. Further, the example in which only two types of discharge lamps La are used is shown. The magnitude of the load can be determined in more stages (for example, using a window comparator) and the output voltage of the transformer circuit 11 can be switched in multiple stages. If possible, it is possible to cope with more types of discharge lamps La.

[0044]

According to the first aspect of the present invention, a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and a rectifier connected between both ends of the smoothing capacitor are alternately turned on and off. A series circuit of a pair of switching elements, a load circuit including one switching element, a discharge lamp and a resonance circuit, a loop circuit including a DC cut capacitor and an impedance element, and a plurality of types of different rated power consumption. It is possible to use a discharge lamp so that the input current waveform from the AC power supply becomes sinusoidal when the power consumption is between the maximum value and the minimum value of the rated power consumption of a plurality of types of discharge lamps that can be used. The impedance element is set, and the input current waveform is positive when the power consumption is between the maximum and minimum values of the rated power consumption of the discharge lamp that can be used. Since the impedance element is set to be wavy, the input current distortion increases in both the case where the maximum rated power consumption is used and the case where the minimum rated power consumption is used among the available discharge lamps. There is an advantage that the input current distortion can be reduced as a whole only by setting the circuit constant without particularly changing the configuration.

As in the second aspect of the present invention, the waveform of the input current from the AC power supply becomes sinusoidal near the middle value between the maximum value and the minimum value of the rated power consumption of a plurality of types of discharge lamps that can be used. When the impedance element is set to, the degree of increase in the input current distortion is almost equal for both the largest and the smallest rated power consumption of the available discharge lamps. There is an advantage that a large increase in input current distortion can be suppressed.

According to a third aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a smoothing capacitor connected via a diode to a DC output terminal of the rectifier, and a pair of alternately connected ON / OFF connected between both ends of the smoothing capacitor. It is composed of a series circuit of switching elements, one switching element, a load circuit including a discharge lamp and a resonance circuit, and a loop circuit including a DC cut capacitor and an impedance element, and is used for a plurality of types of AC power supplies having different voltages. It is possible to set the impedance element so that the input current waveform from the AC power supply becomes sinusoidal when the voltage is between the maximum value and the minimum value of the voltages of the plurality of types of available AC power supplies. The input current waveform is sinusoidal when the voltage is between the maximum and minimum values of the available AC power supply voltage. Since the power factor is set, the degree of increase in input current distortion is relatively small in both the case where the maximum voltage is used and the case where the minimum voltage is used among the available AC power supplies, The configuration has an advantage that the input current distortion can be reduced as a whole only by setting the circuit constant without any particular change.

According to a fourth aspect of the present invention, the impedance is set so that the waveform of the input current from the AC power supply becomes sinusoidal in the vicinity of an intermediate value between the maximum value and the minimum value of the voltages of a plurality of types of usable AC power supplies. Element is set. According to this configuration, the degree of the increase in the input current distortion is substantially the same for both the maximum and the minimum voltage among the available AC power supplies, and the input current distortion is greatly increased as a whole. There is an advantage that a significant increase can be suppressed.

According to a sixth aspect of the present invention, there is provided a rectifier for rectifying an AC power supply, a smoothing capacitor connected via a diode to a DC output terminal of the rectifier, and a pair of alternately turned on / off connected between both ends of the smoothing capacitor. A series circuit of switching elements, a load circuit including one switching element, a discharge lamp and a resonance circuit, a loop circuit including a DC cut capacitor and an impedance element, and a transformer circuit in which the input voltage to the rectifier is variable. It is possible to use multiple types of discharge lamps with different rated power consumption, and the higher the rated power consumption, the higher the output voltage of the transformer circuit is set. The input voltage to the rectifier is adjusted by the transformer circuit in accordance with There is an advantage that can be compensated by pressure circuit.

According to the seventh aspect of the present invention, a load detection circuit for detecting the power consumption of the discharge lamp is added, and the higher the power consumption of the discharge lamp detected by the load detection circuit, the higher the output voltage of the transformer circuit is set. This has the advantage that the output voltage of the transformer circuit is automatically adjusted according to the power consumption of the discharge lamp.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is a circuit diagram showing a second embodiment.

FIG. 4 is a block diagram showing a third embodiment.

FIG. 5 is a circuit diagram of the same.

FIG. 6 is a circuit diagram showing a conventional example.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is an operation explanatory view of the above.

FIG. 9 is an operation explanatory view of the above.

FIG. 10 is an operation explanatory view of the above.

FIG. 11 is a circuit diagram showing another conventional example.

[Explanation of symbols]

 11 Transformation circuit 12 Load detection circuit AC AC power supply C0 Smoothing capacitor C2 Capacitor C3 Capacitor C5 Capacitor D3, D4 Diode DB Rectifier L2 Inductor La Discharge lamp Q1, Q2 Switching element

Claims (7)

[Claims] 1. A series circuit of a rectifier for rectifying an AC power supply, a smoothing capacitor connected via a diode to a DC output terminal of the rectifier, and a pair of switching elements connected between both ends of the smoothing capacitor and turned on and off alternately. And a load circuit including one switching element, a discharge lamp and a resonance circuit, and a loop circuit including a DC cut capacitor and an impedance element, and a plurality of types of discharge lamps having different rated power consumption can be used. That the impedance element is set so that the input current waveform from the AC power supply has a sinusoidal waveform when the power consumption is between the maximum and minimum values of the rated power consumption of multiple types of discharge lamps that can be used. Discharge lamp lighting device. 2. An impedance element is set such that a waveform of an input current from an AC power supply becomes a sine wave near an intermediate value between a maximum value and a minimum value of rated power consumption of a plurality of types of discharge lamps that can be used. The discharge lamp lighting device according to claim 1, wherein: 3. A series circuit of a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and a pair of switching elements connected between both ends of the smoothing capacitor and turned on and off alternately. And a load circuit including one switching element and a discharge lamp and a resonance circuit, a loop circuit including a DC cut capacitor and an impedance element, and can be used with a plurality of types of AC power supplies having different voltages, A discharge lamp characterized in that an impedance element is set such that a waveform of an input current from the AC power supply has a sine wave shape when a voltage between a maximum value and a minimum value of a plurality of types of usable AC power supplies is used. Lighting device. 4. An impedance element is set such that a waveform of an input current from an AC power supply has a sinusoidal waveform near an intermediate value between a maximum value and a minimum value of voltages of a plurality of types of usable AC power supplies. The discharge lamp lighting device according to claim 3, wherein 5. The discharge lamp lighting device according to claim 1, wherein the impedance element is a capacitor. 6. A series circuit comprising a rectifier for rectifying an AC power supply, a smoothing capacitor connected to a DC output terminal of the rectifier via a diode, and a pair of switching elements connected between both ends of the smoothing capacitor and alternately turned on and off. A load circuit including one of the switching elements, a discharge lamp and a resonance circuit, a loop circuit including a DC cut capacitor and an impedance element, and a transformer circuit having a variable input voltage to the rectifier. A discharge lamp lighting device wherein a plurality of types of discharge lamps having different powers can be used, and the output voltage of the transformer circuit is set higher as the discharge lamp has a higher rated power consumption. 7. A load detecting circuit for detecting power consumption of the discharge lamp is added, and the output voltage of the transformer circuit is set higher as the power consumption of the discharge lamp detected by the load detecting circuit is larger. Item 7. A discharge lamp lighting device according to Item 6.