JPH1126180A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device with little number of elements to be used, providing a high input power factor and a low input current distortion factor with simple control, capable of preventing output voltage of a chopper circuit from increasing more than necessary at low load period such as preheating and starting. SOLUTION: A chopper circuit 3 is arranged between an inverter circuit 1 and a rectifying circuit 2. A control circuit 8 controls so as to interlock a chopper driving signal OUTC to drive a switching element Q1 of the chopper circuit 3 and an inverter driving signal OUTI to control main switching elements Q2 and Q3 of the inverter circuit 1 by the same oscillating frequency. The control circuit 8 also reduces on-duty of the chopper driving signal OUTC as the oscillating frequency becomes high.

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 for lighting an electric discharge lamp by converting the output of a chopper circuit to a high frequency by an inverter circuit.

[0002]

2. Description of the Related Art FIG. 16 is a circuit diagram of a conventional discharge lamp lighting device of this type. This discharge lamp lighting device outputs the output of an inverter circuit 1 for converting a DC voltage to a high-frequency voltage to a discharge lamp L
a to perform high-frequency lighting of the discharge lamp La.
The DC voltage is obtained by rectifying an AC power supply AC by a rectifier circuit 2 including a diode bridge, and boosting an output of the rectifier circuit 2 by a booster type chopper circuit 3.

The chopper circuit 3 includes a choke coil L
_1, a switching element to Q ₁ chopper connected in series to the choke coil L _1, a control circuit 4 for controlling the turning on and off of the switching element Q _1, the choke coil L ₁
A diode D ₁ to form a path for discharging the energy stored in the, and a smoothing capacitor C _3. The chopper circuit 3 switches the switching element Q ₁ at a high frequency by the control circuit 4 to chop the output of the rectifier circuit 2 and, when the switching element Q ₁ is turned on, uses the energy accumulated in the choke coil L ₁ to switch the switching element Q 1. thereby discharged through diode D ₁ when ₁ off, the chopping voltage output through a diode D ₁ is for smoothing by the smoothing capacitor C _3. The control circuit 4 mainly uses an active filter control IC.

In this discharge lamp lighting device, a separately excited half-bridge configuration is used as the inverter circuit 1, and the main switching elements Q ₂ and Q ₃ connected in parallel to the smoothing capacitor C ₃ of the chopper circuit 3 are connected in series. Circuit and driving circuit 5 for driving main switching elements Q ₂ and Q ₃
And a control circuit 6 for alternately turning on and off the main switching elements Q ₂ and Q ₃ . In addition, diodes D ₂ and D ₃ for reflux are connected in anti-parallel to the main switching elements Q ₂ and Q ₃ , respectively.

[0005] At both ends of the switching element Q ₃ constituting the inverter circuit. 1 are connected resonance circuit 7 consisting of the choke coil L ₂ and capacitor C ₂ through the capacitor C ₁ is an inverter the resonance circuit 7 are so as to start lighting the discharge lamp La which is connected across capacitor C ₂ by exciting the circuit 1. Capacitor C
₁ together with a capacitor for cutting direct current, the main switching element Q ₂ ON electric charges charged at the time is that used as the power source when turning the main switching element Q _3.

An inverter drive signal composed of a pulse signal is supplied from the control circuit 6 to the drive circuit 5, and the drive circuit 5 outputs a main switching element Q based on the inverter drive signal.
The _2, Q ₃ by alternately turned on and off has an inverter circuit 1 so as to oscillate. When the inverter circuit 1 is oscillated by alternately turning on and off the main switching elements Q ₂ and Q ₃ by the control circuit 6, a high voltage is applied to both ends of the discharge lamp La by the resonance circuit 7,
The discharge lamp La is turned on. Thereafter, the lighting of the discharge lamp La is maintained by performing the on / off control of the main switching elements Q ₂ and Q _{3 at} a predetermined cycle by the control circuit 6.

In the discharge lamp lighting device described above, since the chopper circuit 3 is provided between the AC power supply AC and the inverter circuit 1, the idle period of the input current flowing from the AC power supply AC is eliminated, so that the input power factor Becomes approximately 1, and
The distortion of the input current is reduced, and input harmonic components can be suppressed. However, in the above configuration, the chopper circuit 3 and the inverter circuit 1 have separate control circuits 4 and 4, respectively.
6 is required, and there is a problem that the cost increases as the control circuit becomes complicated and the number of components increases.

[0008] In contrast, the discharge lamp lighting device shown in FIG. 17, the switching element Q ₃ of the inverter circuit 1 16
₁ also serves as the switching element Q1 of the chopper circuit 3. Therefore, the main switching elements Q ₂ , Q ₃
Supplies high frequency power to the discharge lamp La by being alternately turned on and off, while the main switching element Q ₃ also functions as a switching element of the chopper circuit 3. That is, the main switching element Q ₃ is once turned on, the DC output ends of the rectifier circuit 2 is short-circuited by the choke coil L _1,
Energy is stored in the choke coil L _1. Next, when the main switching element Q ₃ is turned off, the diode D ₂
Energy of the choke coil L ₁ is discharged to the capacitor C ₃ through. That is, the main switching element Q ₃ together also serves the function of switching elements to Q ₁ 16,
Diode D ₂ also serves the function of diode D ₁ of the Figure 16. Therefore, in this discharge lamp lighting device, the partial can be omitted switching element Q _1, a diode D _1, there is an advantage that the number of elements used is reduced. Further, the control circuit 4 of the switching element Q ₁ is also unnecessary.

However, in this discharge lamp lighting device,
Only the switching element Q ₃ and diode D ₂ to be shared by a chopper circuit 3 and the inverter circuit 1, since the chopper current and the inverter current flows simultaneously, one of the two in the inverter circuit 1 of the main switching element Q _2, Q ₃ the main switching element Q ₃ only to stress there is a problem that the concentration of. Moreover, since the by sharing switching element Q ₃ at a chopper circuit 3 and the inverter circuit 1, is difficult to separate the control of the chopper circuit 3 and the inverter circuit 1. Therefore, for example, when starting the lighting of the discharge lamp La, at the time of dimming lighting control of the discharge lamp La, at the time of disconnection of the discharge lamp La when a plurality of discharge lamps La are lit in parallel, at the end of life of the discharge lamp La, or the like. In the case of fluctuation, a separate control circuit is required to control the output of the chopper circuit 3, and there has been a problem that the control circuit becomes complicated and the cost increases as the number of parts increases.

FIG. 18 shows a discharge lamp lighting device which solves the above-mentioned problems of the discharge lamp lighting devices of FIGS. The basic configuration of the discharge lamp lighting device shown in FIG. 18 is substantially the same as the circuit configuration of FIG. 16, and the control circuit 4 and the control circuit 6 of FIG.
Are provided as one control circuit 8 ', and the switching operation timings of the main switching elements Q ₂ and Q _{3 of} the inverter circuit 1 and the switching element Q ₁ of the chopper circuit 3 are made common.
_The energy stored in the choke coil L1 of the chopper circuit 3 is adjusted by independently controlling the on-time of ₁ and the output of the chopper circuit 3 is arbitrarily controlled. And the controllability of the output voltage Vdc of the chopper circuit 3 can be improved.

[0011]

[SUMMARY OF THE INVENTION Incidentally, the conventional discharge lamp lighting device shown in FIG. 18, the main switching element Q _2, Q ₃ of inverter circuit 1, the switching element Q _1, the same frequency of the chopper circuit 3 When the operation mode of the inverter circuit 1 is switched,
For example, a preheating mode for giving sufficient preheating to the filament of the discharge lamp La, a start mode for reliably starting the discharge lamp La, and a lighting mode for maintaining the output of the discharge lamp La at an arbitrary output. And the operation mode, the main switching elements Q ₂ and Q _{3 of} the inverter circuit 1 and the switching element Q ₁ of the chopper circuit 3 perform the same oscillation frequency switching control. Therefore, adjustment of the output of the chopper circuit 3 is not must be performed by only the on-time control switching elements to Q ₁ chopper circuit 3, the preheating, the output voltage of the chopper circuit 3 at light load starting such (voltage across the smoothing capacitor C ₃ ) Needs to be controlled to prevent it from rising more than necessary, causing problems such as a complicated control circuit and an increase in the number of parts. Also, when switching between poor on-time control of the switching elements to Q ₁ chopper circuit 3 operating modes, i.e. immediately after the oscillation frequency is switched, the chopper circuit 3, as shown in FIG. 19
May rise (abnormally rise) in the output voltage Vdc.

The present invention has been made in view of the above circumstances, and has as its object to achieve a high input power factor and a low input current distortion factor while using a small number of elements and controlling easily.
It is another object of the present invention to provide a discharge lamp lighting device capable of preventing an output voltage of a chopper circuit from unnecessarily increasing during a light load such as preheating and starting.

[0013]

According to a first aspect of the present invention, an output voltage of a rectifier circuit connected to an AC power supply is chopped by turning on and off a chopper switching element. A chopper circuit that rectifies and smoothes the DC voltage to a predetermined DC voltage, an inverter circuit that converts the DC voltage of the chopper circuit to a high-frequency voltage by turning on and off a switching element and supplies high-frequency power to a discharge lamp, and a chopper switching element Control means for interlockingly controlling the first drive signal to be driven and the second drive signal for driving the switching element of the inverter circuit at the same oscillation frequency, the control means comprising:
The on-duty of the first drive signal is reduced as the oscillating frequency increases, and a chopper circuit is provided between the AC power supply and the inverter circuit to stop the input current flowing from the AC power supply. Since the period is eliminated, a high input power factor and a low input current distortion factor can be achieved, and the first driving of the chopper switching element can be achieved.
Control means for controlling the drive signal of the inverter circuit and the second drive signal for driving the switching element of the inverter circuit at the same oscillation frequency, so that the number of elements used is small and the configuration of the control circuit can be simplified. Since the means reduces the on-duty of the first drive signal as the oscillation frequency increases, it is possible to prevent the output voltage of the chopper circuit from unnecessarily increasing during a light load such as preheating and starting of the discharge lamp.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means reduces the output voltage of the chopper circuit when the oscillation frequency increases, or substantially reduces the output voltage of the chopper circuit regardless of the oscillation frequency. The provision of the constant value means prevents the output voltage of the chopper circuit from unnecessarily increasing during a light load such as preheating and starting the discharge lamp.

According to a third aspect of the present invention, in the second aspect of the present invention, the control means increases the on-duty between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When changing, the on-duty is gradually changed, so that the output voltage of the chopper circuit can be prevented from rising more than necessary when switching the operation mode.

According to a fourth aspect of the present invention, in the second aspect of the invention, the control means increases the on-duty between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When changing, the oscillation frequency is gradually changed, so that it is possible to prevent the output voltage of the chopper circuit from rising more than necessary when switching the operation mode.

According to a fifth aspect of the present invention, in the second aspect of the invention, the control means increases the on-duty between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When changing, the on-duty is changed gradually and the oscillation frequency is changed gradually, so that the output voltage of the chopper circuit can be prevented from rising more than necessary when switching the operation mode.

The invention of claim 6 is the invention of claims 2 to 5
According to the invention, the control means includes an output adjusting means capable of arbitrarily adjusting the output voltage of the chopper circuit, so that the output voltage of the chopper circuit can be arbitrarily adjusted. According to a seventh aspect of the present invention, in the sixth aspect, the control means includes dimming control means for performing dimming control of the discharge lamp using the output adjustment means, so that the oscillation frequency is not changed. Therefore, radiation noise can be reduced as compared with the conventional dimming control in which the oscillation frequency is increased.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a circuit diagram of a discharge lamp lighting device of the present embodiment. The basic configuration of the discharge lamp lighting device of the present embodiment is substantially the same as the conventional configuration shown in FIG. 18, and is characterized by the configuration of the control circuit 8.

The control circuit 8 has a configuration as shown in FIG. 2, and includes an oscillating circuit 10 for setting the oscillating frequencies of the switching elements Q ₁ , Q ₂ and Q ₃ of the chopper circuit 3 and the inverter circuit 1, and an inverter. Inverter drive signal OUT for driving main switching elements Q ₂ and Q ₃ of circuit 1
An inverter PWM circuit 11 for generating the I, is composed of a chopper PWM circuit 12 for generating a chopper driving signal OUTC for driving the switching element to Q ₁ chopper circuit 3.

The oscillation circuit 10 includes a mode switching circuit 1
3, a current source 30, a capacitor Cpls, a transmitter 14, and the like. The mode switching circuit 13 controls the current source 30 to change the charging current of the capacitor Cpls according to each operation mode. Oscillation frequency 14 increases when the charging current to capacitor Cpls is large (when the voltage of capacitor Cpls rises quickly), and increases when the charging current is small (when the voltage rise of capacitor Cpls is slow). Perform the operation.

The inverter PWM circuit 11, the mode switching circuit 15, a current source 31, capacitor Cinv, comparator CP _1, RS flip-flop FF _1, Yes constituted by such as a driver circuit 21, current controlled by the mode switching circuit 15 The current from the source 31 charges the capacitor Cinv. The comparator CP ₁ is connected to the capacitor C input to the non-inverting terminal.
inv and the reference voltage V input to the inverting terminal
_ref1 and being adapted to compare, the output terminal is connected to the set terminal S of the RS flip-flop FF _1, is connected to the base of the transistor Q _1. R
The reset terminal R of the S flip-flop FF ₁ trigger signals S ₁ consisting of the pulse signal outputted from the oscillator 14 described above is input. The driver circuit 21, the output of the output terminal Q of the RS flip-flop FF ₁ is input, and outputs an inverter driving signal OUTI to the drive circuit 5. In the inverter PWM circuit 11, the mode switching circuit 15 changes the charging current of the capacitor Cinv according to each operation mode, and sets the on-duty of the inverter drive signal OUTI to approximately 50% in each operation mode.

The chopper PWM circuit 12 includes a current source 32,
It is composed of a capacitor Cchop, a comparator CP ₂ , an RS flip-flop FF ₂ , a driver circuit 22, and the like. The capacitor Cchop is charged by a current from a current source 32. The comparator CP ₂
And the voltage across the capacitor Cchop inputted to the non-inverting terminal, is adapted to compare the reference voltage V _ref2 is input to the inverting terminal, the output terminal RS flip-flop F
Is connected to the set terminal S of the F _2, it is connected to the transistor Q _2. RS flip-flop FF ₂
Of the inverter PWM circuit 11
The output of the comparator CP ₁ is input. The driver circuit 22, the output of the output terminal Q of the RS flip-flop FF ₂ is input, and outputs a chopper driving signal OUTC for driving the switching element Q _1.

Vcc in FIG. 2 indicates a power supply voltage.
The power supply voltage Vcc may be obtained by smoothing the output of the rectifier circuit 2, an external power supply may be used, or a constant DC voltage may be used. Hereinafter, the operation of the control circuit 8 will be described with reference to FIGS. 3A and 3A show the voltage waveform of the capacitor Cpls of the oscillation circuit 10, and FIG. 3B shows the voltage waveform of the capacitor Cpls of the inverter PWM circuit 11.
(c) shows the inverter PWM circuit 11
The inverter drive signal OUTI output from the
4 shows the voltage waveform of the capacitor Cchop of the chopper PWM circuit 12, and (e) shows the chopper drive signal OUTC output from the chopper PWM circuit 12, respectively. FIG. 3 shows the preheating mode in which the oscillation frequency is set high, and FIG. Is a waveform in the full lighting mode in which the oscillation frequency is set low.

The inverter PWM circuit 11 includes a transmitter 14
The triggering signal S ₁ (trigger signal S ₁ rises at the peak of the voltage of the capacitor Cpls) sets the timing to start charging the capacitor Cinv, and the inverter drive signal OUTI goes low during the charging period of the capacitor Cinv. , During the discharge period of the capacitor Cinv (FIGS. 3B and 3C and FIG.
(See (b) and (c)).

The chopper PWM circuit 12 includes an inverter P
The charging start timing of the capacitor Cchop is set by the trigger signal S ₂ (the output of the comparator CP) generated by the WM circuit 11, but the charging current of the capacitor Cchop is a constant current. The chopper drive signal OUTC goes low during the charging period of the capacitor Cchop, and goes high during the discharging period of the capacitor Cchop (FIG. 3).
(D), (e) and FIGS. 4 (d), (e)). Also,
The charge start timing of the capacitor Cchop is synchronized with the timing at which the inverter drive signal OUTI changes to a high level, and the charge current of the capacitor Cchop is constant. Therefore, the on-duty of the chopper drive signal OUTC decreases when the above-described oscillation frequency is high, When the oscillation frequency is low, the on-duty increases (see FIGS. 3E and 4E). FIG. 5 shows the relationship between the oscillation frequency f and the on-duty of the chopper drive signal OUTC. As shown in FIG. 5, the on-duty (chopper on-duty) of the chopper drive signal OUTC decreases as the oscillation frequency f increases.

[0027] Thus, the energy stored in the choke coil L ₁ of about chopper circuit 3 oscillation frequency increases decreases, because energy oscillation frequency is accumulated in the choke coil L ₁ of the low indeed chopper circuit 3 becomes large, Chopper circuit 3 at light load with high oscillation frequency
Can be prevented from rising more than necessary. In the present embodiment, when the oscillation frequency is high and the load is light, the output voltage Vdc of the chopper circuit 3 decreases as the oscillation frequency increases, but the output voltage Vdc of the chopper circuit 3 is controlled to be substantially constant. Is also good.

Thus, in the present embodiment, the inverter circuit
Main switching element Q of road 1_Two, Q _ThreeAnd the chopper circuit
3 switching element Q₁Switching operation timing
When the oscillation frequency is high, the chopper circuit
3 switching element Q₁Driving chopper drive signal
When the on-duty becomes small and the oscillation frequency is low
The on-duty of the chopper drive signal increases
With a simple circuit configuration, no additional circuit is required.
Output voltage V of chopper circuit 3 at light load such as heat and starting
dc can be prevented from rising more than necessary.

(Embodiment 2) FIG. 6 is a circuit diagram of a discharge lamp lighting device according to this embodiment, and FIG. 7 is a circuit diagram of a control circuit in FIG. The basic configuration of the present embodiment is substantially the same as that of the first embodiment.
It is characterized in that the dc detection circuit 16 is connected to the chopper PWM circuit 12.

[0030] Vdc detection circuit 16 is connected a series circuit of a transistor Q ₁₆ of mirror circuit 17 and the resistor R ₁₆ via a resistor R _18, R ₁₉ to the output of the chopper circuit 3, the transistor Q ₁₇ of mirror circuit 17 connected in parallel to the capacitor Cchop chopper PWM circuit 12 a series circuit of a and a resistor R _17. Hereinafter, the operation of the control circuit 8 will be described with reference to FIG. 8A shows the voltage waveform of the capacitor Cpls of the oscillation circuit 10, FIG. 8B shows the voltage waveform of the capacitor Cinv of the inverter PWM circuit 11, and FIG. 8C shows the inverter drive output from the inverter PWM circuit 11. The signal OUTI, (d) shows the voltage waveform of the capacitor Cchop of the chopper PWM circuit 12, and (e) shows the chopper drive signal OUTC output from the chopper PWM circuit 12.

The Vdc detection circuit 16 varies the charging current of the capacitor Cchop of the chopper PWM circuit 12 according to the output voltage Vdc of the chopper circuit 3. That is, when the output voltage Vdc of the chopper circuit 3 increases, the charging current of the capacitor Cchop decreases, and the capacitor Cchop
The charging time becomes longer (i.e., the voltage waveform of the capacitor Cchop is the increase of the voltage becomes slow changes in the direction of arrow A ₁ in FIG. 8 (d)). Therefore, the comparator CP ₂
Output period until reset by the trigger signal S ₂ becomes shorter after setting the flip-flop FF ₂ at a high level. As a result, the chopper drive signal OU
Since the on-duty of the TC decreases, the output voltage Vdc of the chopper circuit 3 decreases. When the output voltage Vdc of the chopper circuit 3 is decreased, the charging current increases the capacitor Cchop, the charging time of the capacitor Cchop is shortened (i.e., the voltage waveform of the capacitor Cchop is an arrow A ₂ direction in FIG. 8 (d) And the voltage rises faster). As a result, the on-duty of the chopper drive signal OUTC decreases, and the output voltage Vdc of the chopper circuit 3 increases. Thus, the output voltage Vdc of the chopper circuit 3 is controlled to be substantially constant.

Thus, in this embodiment, the output voltage Vdc of the chopper circuit 3 in each operation mode can be accurately adjusted. (Embodiment 3) The basic configuration of this embodiment is the same as that in Embodiment 2, the case of increasing the on-duty of the drive signal of the switching element to Q ₁ chopper circuit 3 at the time of operation mode switching, slowly the on-duty The feature is that it is changed.

Hereinafter, the operation of this embodiment will be described with reference to FIG. FIG. 9 shows the operation mode when the power is off.
The waveform of each part when shifting to the time of preheating, starting, and lighting is shown, (a) shows the output voltage Vdc of the chopper circuit 3,
(B) is the oscillation frequency of the oscillation circuit 10, the (c) the drive signal of on-duty switching element to Q ₁ chopper circuit 3 (chopper on-duty), respectively.

That is, in this embodiment, the operation mode
The oscillation frequency is f₁→ f_Two→ f _ThreeAnd becoming smaller
Switching element Q₁Drive signal on-duty
Is OD₁→ OD_Two→ OD_ThreeAnd grow. here
When switching to each operation mode,
Change the on-duty slowly (sweep
Control) to shift to a predetermined on-duty.
You. Thus, in this embodiment, light loads such as preheating and starting are performed.
The output voltage Vdc of the chopper circuit 3 during loading rises abnormally
Can be prevented and when switching to each operation mode,
That the output voltage Vdc of the chopper circuit 3 rises more than necessary.
Can be prevented.

[0035] (Embodiment 4) The basic configuration of this embodiment is the same as that in Embodiment 2, the case of increasing the on-duty of the drive signal of the switching element to Q ₁ chopper circuit 3 at the time of operation mode switching, an oscillation circuit 10 Is characterized by the fact that the oscillation frequency is gradually changed. Hereinafter, the operation of the present embodiment will be described with reference to FIG. FIG.
0 shows the waveform of each part when the operation mode shifts to power off, preheating, starting, and lighting, (a) shows the output voltage Vdc of the chopper circuit 3, and (b) shows the output voltage of the oscillation circuit 10. the oscillation frequency, the on-duty of the (c) driving signal of the switching element to Q ₁ chopper circuit 3, respectively. That is, in the present embodiment, the oscillation frequency decreases as f ₁ → f ₂ → f ₃ according to the change in the operation mode, and the on-duty increases as OD ₁ → OD ₂ → OD ₃ . Here, when switching to each operation mode, control is performed so that the oscillation frequency is swept within a certain fixed period to shift to a predetermined oscillation frequency. Since the relationship between the oscillation frequency and the ON duty has the relationship shown in FIG 5 described in Embodiment 1, the oscillation from the oscillation frequency f ₁ of the low value the oscillation frequency from a high value (for example, and FIG. 10 (b) During the period of sweeping to the frequency f ₂ ), the on-duty is changed from a small value to a large value (for example, FIG.
(C) On duty OD ₁ to on duty OD
₂ ) It gradually changes to. Therefore, it is possible to prevent the output voltage Vdc of the chopper circuit 3 from unnecessarily increasing at the time of mode switching.

In the present embodiment, however, it is possible to prevent the output voltage Vdc of the chopper circuit 3 from abnormally increasing at the time of light load such as preheating and starting, and to prevent the chopper circuit 3 from switching to each operation mode. The output voltage Vdc can be prevented from rising abnormally. (Embodiment 5) Basic configuration of the present embodiment is the same as that in Embodiment 2, the case of increasing the on-duty of the drive signal of the switching element to Q ₁ chopper circuit 3 when the operation mode is switched, the switching element of the chopper circuit 3 Q ₁
In this case, the on-duty and the oscillation frequency of the drive signal are gradually changed.

Hereinafter, the present embodiment will be described with reference to FIG.
The operation will be described. FIG. 11 shows that the operation mode is power off.
Time, preheating, starting, and lighting
7A shows the waveform, and FIG. 7A shows the output voltage Vdc of the chopper circuit 3.
(B) is the oscillation frequency of the oscillation circuit 10, and (c) is the oscillation frequency.
Switching element Q of chopper circuit 3₁ON of the drive signal of
The duties are shown respectively. Change of operation mode
The oscillation frequency is f ₁→ f_Two→ f_ThreeAnd become smaller
The chopper on duty is OD₁→ OD _Two→ O
D_ThreeAnd grow. Here, switch to each operation mode
When changing the chopper on-duty within a certain period
Sweep and oscillate the oscillation frequency, and
Shift to chopper on duty and oscillation frequency
To control.

Thus, in this embodiment, it is possible to prevent an abnormal increase in the output of the chopper circuit 3 during a light load such as preheating or starting, and to prevent an abnormal increase in the output of the chopper when switching to each operation mode. In addition, it is possible to accurately adjust the output voltage Vdc of the chopper circuit when switching to each operation mode. (Embodiment 6) FIG. 12 is a circuit diagram of a discharge lamp lighting device of the present embodiment, and FIG. 13 is a circuit diagram of a control circuit 8 in FIG. The basic configuration of this embodiment is substantially the same as that of the second embodiment, and is characterized in that a Vdc adjustment circuit 19 is connected to a Vdc detection circuit 16 in the control circuit 8. Vdc adjustment circuit 19 is constituted by parallel-connected volume VR to the series circuit of the resistor R ₁₉ and transistor Q ₁₆ of the Vdc detection circuit 16 and the resistor R _16, by changing the resistance value of the volume VR, Since the current flowing through the mirror circuit 17 can be varied, the charging current of the capacitor Cchop of the chopper PWM circuit 12 can be adjusted arbitrarily. Therefore, the on-duty of the chopper drive signal OUTC can be arbitrarily adjusted by changing the resistance value of the volume VR. As a result, the output voltage Vdc of the chopper circuit 3 can be arbitrarily adjusted.

By the way, also in the present embodiment, since the on-duty of the chopper drive signal OUTC increases as the oscillation frequency decreases, the output voltage Vdc of the chopper circuit 3 also increases (or remains substantially constant) as the oscillation frequency decreases. Therefore, when the output voltage Vdc of the chopper circuit 3 is arbitrarily adjusted by the Vdc adjustment circuit 19, if the output voltage Vdc is adjusted to a predetermined value in the operation mode having the lowest oscillation frequency, the other operation modes Does not cause the output voltage Vdc to exceed the predetermined value.

Thus, in this embodiment, the output voltage Vdc of the chopper circuit 3 can be adjusted with a simple configuration. In the present embodiment, since the switching elements Q ₁ , Q ₂ , and Q ₃ of the chopper circuit 3 and the inverter circuit 1 oscillate at the same frequency, a means for arbitrarily adjusting the oscillation frequency (for example, a variable resistor) And the like, the output voltage Vdc of the chopper circuit 3 changes according to the change of the oscillation frequency. Therefore, a means for arbitrarily adjusting the oscillation frequency and a means for arbitrarily adjusting the chopper output (Vdc adjustment circuit 19). If both are provided, the oscillation frequency may be adjusted first, and then the output voltage Vdc of the chopper circuit 3 may be adjusted.

(Embodiment 7) FIG. 14 is a circuit diagram of a discharge lamp lighting device of the present embodiment, and FIG. 15 is a circuit diagram of the control circuit 8 in FIG. The basic configuration of the present embodiment is substantially the same as that of the sixth embodiment.
1 is connected. In this embodiment,
Since a current flowing through the Vdc detection circuit 16 can be adjusted by inputting a dimming signal from the outside to the dimming control circuit 21, the charging current of the capacitor Cchop of the chopper PWM circuit 12 can be arbitrarily adjusted by the dimming control circuit 21. Since the adjustment can be performed, the on-duty of the chopper drive signal OUTC can be arbitrarily adjusted, and as a result, the output voltage Vdc of the chopper circuit 3 can be arbitrarily adjusted.

In the present embodiment, when dimming the discharge lamp La to an arbitrary dimming level (reducing the light output), the dimming control circuit 21 adjusts the current value corresponding to the dimming level to Vdc. By applying the signal to the circuit 19, the chopper PWM
Since the charging current of the capacitor Cchop provided in the circuit 12 decreases, the on-duty of the chopper drive signal OUTC decreases. Therefore, the output voltage V of the chopper circuit 3
As the dc decreases, the output of the inverter circuit 1 also decreases, and the discharge lamp La enters a dimming state. Therefore, in the present embodiment, since the dimming can be performed without changing the oscillation frequency, the radiation noise can be reduced as compared with the conventional dimming control by increasing the oscillation frequency.

[0043]

According to a first aspect of the present invention, a chopper for chopping an output voltage of a rectifier circuit connected to an AC power supply by turning on and off a switching element for a chopper, rectifying and smoothing the chopping voltage, and converting the chopping voltage to a predetermined DC voltage. Circuit, an inverter circuit that converts a DC voltage of the chopper circuit into a high-frequency voltage by turning on and off the switching element and supplies high-frequency power to the discharge lamp, a first drive signal for driving the chopper switching element, and a switching element of the inverter circuit Control means for interlockingly controlling the second drive signal for driving the first and second drive signals at the same oscillation frequency. The control means reduces the on-duty of the first drive signal as the oscillation frequency increases, so that the AC power supply and the inverter Input power flowing from the AC power supply side by providing a chopper circuit between , The high input power factor and the low input current distortion factor can be achieved, the first drive signal for driving the chopper switching element and the second drive signal for driving the inverter circuit switching element. Since there is a control means for controlling the drive signal in conjunction with the same oscillation frequency, the number of elements used is small and the configuration of the control circuit can be simplified.
Since the on-duty of the drive signal is reduced, the output voltage of the chopper circuit can be prevented from increasing more than necessary at light loads such as preheating and starting the discharge lamp.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means reduces the output voltage of the chopper circuit when the oscillation frequency increases, or substantially reduces the output voltage of the chopper circuit regardless of the oscillation frequency. The provision of the constant value means has an effect that the output voltage of the chopper circuit can be prevented from unnecessarily increasing during a light load such as preheating and starting the discharge lamp.

According to a third aspect of the present invention, in the second aspect of the invention, the control means increases the on-duty between two values according to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When the change is made, the on-duty is gently changed, so that there is an effect that the output voltage of the chopper circuit can be prevented from rising more than necessary when switching the operation mode.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the control means increases the on-duty between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When the frequency is changed, the oscillation frequency is gradually changed, so that there is an effect that the output voltage of the chopper circuit can be prevented from rising more than necessary when switching the operation mode.

According to a fifth aspect of the present invention, in the second aspect of the invention, the control means increases the on-duty between two values according to the respective operation modes before and after the switching when switching the operation mode of the discharge lamp. When changing, the on-duty is changed gradually and the oscillation frequency is changed slowly, so that there is an effect that the output voltage of the chopper circuit can be prevented from rising more than necessary when switching the operation mode.

The invention of claim 6 is the invention of claims 2 to 5
In the invention, the control means includes an output adjusting means capable of arbitrarily adjusting the output voltage of the chopper circuit, and thus has an effect that the output voltage of the chopper circuit can be arbitrarily adjusted. According to a seventh aspect of the present invention, in the sixth aspect, the control means includes dimming control means for performing dimming control of the discharge lamp using the output adjustment means, so that the oscillation frequency is not changed. Therefore, radiation noise can be reduced as compared with the conventional dimming control in which the oscillation frequency is increased.

[Brief description of the drawings]

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

FIG. 2 is a main part circuit diagram of the same.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is a diagram illustrating another operation of the above.

FIG. 5 is another operation explanatory view of the above embodiment.

FIG. 6 is a diagram showing a second embodiment.

FIG. 7 is a main part circuit diagram of the same.

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

FIG. 9 is an operation explanatory diagram of the third embodiment.

FIG. 10 is an operation explanatory diagram of the fourth embodiment.

FIG. 11 is an operation explanatory diagram of the fifth embodiment.

FIG. 12 is a circuit diagram showing a sixth embodiment.

FIG. 13 is a main part circuit diagram of the same.

FIG. 14 is a circuit diagram showing a seventh embodiment.

FIG. 15 is a main part circuit diagram of the same.

FIG. 16 is a circuit diagram showing a conventional example.

FIG. 17 is a circuit diagram showing another conventional example.

FIG. 18 is a circuit diagram showing another conventional example.

FIG. 19 is a diagram illustrating the operation of the above.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 inverter circuit 2 rectifier circuit 3 chopper circuit 5 drive circuit 8 control circuit AC AC power supply La discharge lamp Q ₁ switching element Q ₂ , Q ₃ main switching element OUTI inverter drive signal OUTC chopper drive signal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koji Fujimoto 1048 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Works, Ltd.

Claims (7)

[Claims] 1. A chopper circuit for chopping an output voltage of a rectifier circuit connected to an AC power supply by turning on / off a chopper switching element, rectifying and smoothing the chopping voltage and converting the chopped voltage to a predetermined DC voltage, An inverter circuit for converting a voltage into a high-frequency voltage by turning on and off the switching element and supplying high-frequency power to the discharge lamp; a first drive signal for driving the chopper switching element; and a second drive for driving the switching element of the inverter circuit A discharge lamp lighting device, comprising: control means for performing interlock control of signals at the same oscillation frequency, wherein the control means decreases the on-duty of the first drive signal as the oscillation frequency increases. 2. The method according to claim 1, wherein the control means includes means for reducing the output voltage of the chopper circuit when the oscillating frequency increases, or for making the output voltage of the chopper circuit substantially constant regardless of the oscillating frequency. The discharge lamp lighting device according to claim 1. 3. The method according to claim 1, wherein the on-duty gradually changes when the operation mode of the inverter circuit is switched between two values corresponding to the operation modes before and after the switching. The discharge lamp lighting device according to claim 2, wherein the discharge lamp lighting device is operated. 4. When the on-duty is increased and changed between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the inverter circuit, the control means gradually changes the oscillation frequency. The discharge lamp lighting device according to claim 2, wherein the discharge lamp lighting device is operated. 5. The method according to claim 1, wherein the control means changes the on-duty slowly when changing the on-duty between two values corresponding to the respective operation modes before and after the switching when switching the operation mode of the inverter circuit. 3. The discharge lamp lighting device according to claim 2, wherein the oscillation frequency is gradually changed. 6. The discharge lamp lighting device according to claim 2, wherein said control means comprises an output adjusting means capable of arbitrarily adjusting an output voltage of the chopper circuit. 7. The discharge lamp lighting device according to claim 6, wherein the control means includes dimming control means for performing dimming control of the discharge lamp using the output adjusting means.