JPH07147198A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To stabilize the operating state of an inverter circuit and a discharge lamp at starting, and minimize the stress to the circuit element. CONSTITUTION:A DC power source is formed from an AC power source 1 by a chopper circuit 2. An inverter circuit 4 forms the feed power to a discharge lamp 6 with the DC power source supplied from the chopper circuit 2 as the power source. The output of a comparator IC2 possessed by a chopper control circuit 3 for controlling the output of the chopper circuit 2 is delayed by a capacitor C9 connected in parallel to a resistor R13. Thus, in the transient state for starting and lighting the discharge lamp 6, the load fluctuation as the loads of the inverter circuit 4 and the discharge lamp 6 can be relatively eased. The increase in stress to the circuit element in the transient state can be consequently prevented, and the inverter circuit 4 and the discharge lamp 6 can be stably operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a chopper circuit to create a DC power supply from an AC power supply such as a commercial power supply, and a DC power supply supplied from this chopper circuit to create high frequency power to light a discharge lamp. The present invention relates to an electric lamp lighting device.

[0002]

2. Description of the Related Art Conventionally, a discharge lamp lighting device has been widely used in which a DC voltage obtained by rectifying and smoothing an AC voltage of a commercial power source is converted into a high frequency voltage by an inverter or the like to supply high frequency power to a discharge lamp as a load. . In this type of discharge lamp lighting device, the rectified output of the commercial AC voltage is smoothed because the envelope of the high-frequency current supplied to the discharge lamp does not fluctuate in the commercial AC cycle. This is because the re-ignition phenomenon is substantially eliminated, the luminous efficiency of the discharge lamp is improved, the power consumption of the discharge lamp lighting device is reduced, and the flickering of light is eliminated to improve the performance. However, when the commercial AC voltage is rectified and smoothed, the current flowing from the commercial power source to the smoothing capacitor flows only near the peak value of the commercial AC voltage, and the peak value having a pause period is high every half cycle of the commercial AC voltage. Since it is a current, the input power factor is poor, and it also contains many high-order harmonic current components with respect to the AC fundamental wave, so that harmonic noise is mixed with other equipment connected to the same AC power distribution system. There was a bad effect of. Therefore, it is necessary to increase the power factor of the input current, reduce the harmonic components, and supply a DC smoothing voltage that is as flat as possible.

As a discharge lamp lighting device as described above, FIG.
There is one shown in. This one supplies an AC power source 1 such as a commercial power source to a chopper circuit 2 via a switch SW, and a chopper circuit 2 whose output is controlled by a chopper control circuit 3 creates a DC power source from the AC power source 1 and outputs an inverter. The operation of the inverter circuit 4 is controlled by the control circuit 5, high frequency power is generated by using this DC power source as a power source, and the high frequency power is supplied to the discharge lamp 6 to light the discharge lamp 6.

Next, the specific circuit configuration and circuit operation of the above conventional example will be described. First, FIG. 6 shows a circuit configuration diagram of the chopper circuit 2 and the chopper control circuit 3. AC power supply 1
Is connected to the AC input terminal of the full-wave rectifier DB. A small capacity capacitor C ₂ is connected to the DC output terminal of the full-wave rectifier DB. A switching element Q ₁ composed of a power MOSFET is connected to both ends of the capacitor C ₂ via an inductor L ₁ . Further, a reverse parasitic diode Ds is connected to both ends of the switching element Q ₁ , and a smoothing capacitor C ₁ is further connected via a diode D ₁ for preventing backflow, and a direct current generated at both ends of this smoothing capacitor C _1. The voltage is supplied to the inverter circuit 4. A series circuit of resistors R ₂ and R ₃ for detecting the output voltage of the chopper circuit 2 is connected to both ends on the output side of the smoothing capacitor C ₁ , and the potential at the connection point between the resistors R ₂ and R ₃ is different. Input to the dynamic amplifier IC ₃ and the reference potential V
voltage corresponding to the difference between the _{re f1} is input is amplified to an inverting input terminal of the voltage differential amplifier IC _4. Differential amplifier IC ₃
A capacitor C ₄ and a resistor R ₆ are connected as a feedback impedance to the, and a capacitor C ₃ is connected to the non-inverting input terminal of the voltage differential amplifier IC ₄ . A transistor Q ₂ is connected in parallel to both ends of the capacitor C ₃ , and an inverting output terminal Q ′ of a flip-flop FF is connected to the base of the transistor Q ₂ . The output terminal Q of the flip-flop FF is connected to the control electrode of the switching element Q ₁ via the resistor R ₁ , the output terminal of the voltage differential amplifier IC ₄ is connected to the reset terminal R, and the set terminal is further connected. The output terminal of the detector IC ₅ is connected to S. The current flowing through the switching element Q ₁ is converted into a voltage by the resistor R ₄ and the detector IC
_Entered in ₅ . In addition, a constant current flows through the transistor Q ₃ via the resistor R ₅ , and the same current flows through the transistor Q ₃ to the capacitor C ₃ through the transistor Q ₄ .

The circuit operation in the above configuration is shown in FIG.
To explain based on the time chart shown in (d),
First, time t₁Then inductor L₁And switching element
Child Q ₁Or diode D₁And smoothing capacitor C₁Through
Resistance R_FourThat the current flowing in
C_FiveDetected by the detector IC_FiveHigher level signal
Is output. As a result, the flip-flop FF set
Since the H-level signal is input to the input terminal S,
An H level signal from the output terminal Q and an inverted output terminal
An L level signal is output from Q'and the switching element
Child Q₁Turns on and transistor Q₂Turn off
To do.

Subsequently, during the period from time t _{1 to} t ₂ , the transistor Q ₂ is off and the transistors Q ₃ and Q _3
The current mirror circuit constituted by ₄ charges the capacitor C ₃ with a constant current determined by the control power supply voltage V _cc and the resistor R _5, and the voltage across the capacitor C ₃ increases linearly. At this time, the _divided potential by the resistors R ₂ and R ₃ is the differential amplifier I together with the reference potential V _ref1.
Input to C ₃ , the output of the differential amplifier IC ₃ is constant at a certain level. Capacitor C to that constant level
_When the voltage across both terminals of ₃ reaches, at time t ₂ , the signal of H level is output from the voltage differential amplifier IC ₄ to the flip-flop FF.
Is input to the reset terminal R of. As a result, an L level signal is output from the output terminal Q of the flip-flop FF and an H level signal is output from the inverting output terminal Q ′, turning off the switching element Q ₁ and turning on the transistor Q _2. Become.

Furthermore, in the period from the time t ₂ ~t _3, the inductor L ₁ while the switching element Q ₁ is turned on,
The energy stored in the inductor L _{1 due} to the current flowing through the switching element Q ₁ and the resistor R ₄ is released when the switching element Q ₁ is turned off, and the energy is accumulated from the inductor L ₁ to the diode D ₁ , the capacitor C ₁ and the resistor R ₁ .
_A current flows to ₄ and the capacitor C ₁ is charged. Further, as described above, while the capacitor C ₁ is being charged, the transistor Q ₂ is turned on, so that the capacitor C ₃
The potential of does not rise. Then, when the current due to the energy of the inductor L ₁ finishes flowing, time t ₃ (or t ₁ )
Then, the current flowing through the resistor R ₄ becomes zero, and the same operation is repeated thereafter. In this way, by keeping the interval from time t _{1 to} t ₂ constant, detecting that the current flowing through the inductor L ₁ becomes zero, and controlling the timing when the ON signal of the switching element Q ₁ enters, the inductor It is possible to eliminate the pause section of the current flowing through L ₁ . For this reason,
It is possible to obtain an input current waveform having a relatively small number of harmonic components.

However, since the output of the chopper circuit 2 contains a ripple having the same frequency as the power supply frequency f of the AC power supply 1, the differential amplifier IC ₃ responds to this ripple component, so that the AC power supply 1 outputs the ripple. The harmonic component of the input current will increase. Therefore, by setting the capacitor C ₄ which is the feedback impedance of the differential amplifier IC ₃ and the resistor R ₆ so as to satisfy the following equation, the differential amplifier IC ₃ is prevented from responding to the above-mentioned ripple component and the above-mentioned problem is solved. As a solution, the harmonic component is reduced so that the DC voltage V _DC as flat as possible can be supplied to the inverter circuit 4.

1 / 2πC ₄ R ₆ <2f (Equation 1) C ₄ : Capacitance of the capacitor C ₄ R ₆ : Resistance value of the resistor R ₆ f: Power frequency of the AC power supply 1 Next, FIG. 8 is shown. The circuit configurations and circuit operations of the inverter circuit 4 and the inverter control circuit 5 will be described based on the circuit configuration diagram. The inverter circuit 4 is the chopper circuit 2 described above.
The DC voltage V _DC supplied from the power source is used as a power source, and transistors Q ₅ and Q connected in series to the output of the chopper circuit 2 are used.
₆ has a so-called half-bridge structure in which the discharge lamp 6 is connected to both ends of the transistor Q ₅ together with the resonance circuit. The transistor is formed by a current feedback transformer CT inserted in series with the load circuit including the discharge lamp 6 and the resonance circuit. Q _5, Q ₆ transistors Q ₅ and feeding back the current to the on the Q ₆ alternatively, off, and has a self-excited supplying high frequency power to the discharge lamp 6.

Here, the transistor Q_Five, Q₆In
Anti-parallel diode D for flywheel₂, D₃
Are connected. In addition, the load circuit is a
Indexer C_FiveThrough transistor Q_FiveConnected at both ends of
The resonance circuit is a capacitor C ₆And inductance element
L₂It is composed of. The filament of the discharge lamp 6
Capacitor C connected to the non-power supply side of₆The discharge run
Also functions as a preheater for preheating the filament of type 6
Be prepared. Further, the current feedback transformer CT has a secondary winding n.
₂, N₃Base resistance R due to the voltage induced in₇, R₈
Through transistor Q_Five, Q₆Return the current to.

In this type of inverter circuit 4, a starting circuit 7 is provided to surely start the inverter circuit 4 when the power is turned on. The start-up circuit is composed of bidirectional trigger elements such as resistors, capacitors and diacs. By the way, in order to guarantee the life of the discharge lamp 6, a general discharge lamp lighting device performs a preheating operation for preheating the filament of the discharge lamp 6 without turning on the discharge lamp 6 immediately after the AC power supply 1 is turned on. Is normal. That is, in order to prevent the discharge lamp 6 from being lit during a predetermined time (preheating time) immediately after the power is turned on, the voltage across the capacitor C ₆ caused by the resonance of the resonance circuit is set to be lower than the starting voltage of the discharge lamp 6. In addition, the filament of the discharge lamp 6 is preheated. Then, the inverter circuit 4 is the inverter control circuit 5
Since the switching operation of the transistor Q ₆ is controlled by the above, the operation as described above is performed, and the operation of the inverter control circuit 5 will be described below.

First, as the control power supply (power supply voltage V _cc ) for operating the inverter control circuit 5, any structure may be used as long as it is constructed immediately after the AC power supply 1 is turned on. When the control power supply voltage V _cc is applied, the capacitor C ₈ is the charging current is supplied through a resistor R ₁₅ to the capacitor C ₈ connected to the non-inverting input terminal of the comparator IC ₂ is charged. At this time, the current waveform of the charging current of the capacitor C ₈ has an inclination by a time constant determined by the resistance value of the capacitor and the resistor R ₁₅ of the capacitor C _8. Further, the reference voltage V _ref2 generated from the control power supply is input to the inverting input terminal of the comparator IC ₂ . Here, a diode D ₄ is connected in parallel with the resistor R ₁₅ to the non-inverting input terminal of the comparator IC ₂ , and this diode D ₄ is
That is, it is for discharging the electric charge charged in the capacitor C ₈ when the power supply from the AC power supply 1 is lost.

The output terminal of the comparator IC ₂ is connected via a resistor R ₁₄ to the connection point of the series circuit of the resistors R ₁₂ and R ₁₃ provided between the control power source and the ground, and the non-inverting input of the comparator IC ₁ is also connected. It is connected to the terminal. From the output terminal of the comparator IC _2, L-level signal is output when the charging voltage v _c of the capacitor C ₈ is lower than the reference voltage V _ref2, H if the charging voltage v _c is higher than the reference voltage V _ref2 The level signal is output. Therefore, when the output of the comparator IC ₂ is L level, the resistance R ₁₃
And the voltage across the decrease, the voltage at the non-inverting input of the comparator IC ₁ at this time and V _1, the comparator IC ₂ in the opposite
When the output of H is at H level, the control power supply voltage V _{cc is changed} to the resistance R
_The voltage V ₂ divided by ₁₂ and R ₁₃ becomes the non-inverting input of the comparator IC ₁ , and the relationship of V ₁ <V ₂ is established between the _two voltages V ₁ and V ₂ . On the other hand, the inverting input terminal of the comparator IC ₁ is connected to the connection point of the series circuit of the resistor R ₁₀ and the capacitor C ₇ provided between the control power supply and the ground. In parallel with the capacitor C ₇ have transistor Q ₈ is connected, the base of the transistor Q ₈ is the base current from the control power supply via a resistor R ₁₁ is connected to the collector of the transistor Q ₉ is supplied. The base of the transistor Q ₉ has a resistor R ₁₂
The base current is supplied from the secondary winding n ₃ of the current feedback transformer CT via.

In the above configuration, the inverter circuit 4 transistor
Dista Q₆The current feedback transistor is turned on while the
Lance CT secondary winding n₃Base current is supplied from
For the transistor Q₉Is turned on, which
Langista Q₈Is turned off, the comparator IC₁
Capacitor C connected to the inverting input terminal of₇Is resistance R _Ten
Resistance value and capacitor C₇Depending on the time constant determined by
Will be charged. And the capacitor C₇Voltage across
Comparator IC₁The inverting input of is higher than the non-inverting input
Then, the comparator IC₁Output becomes H level
Transistor Q ₇Turns on. However, Transis
Q₇Is a transistor Q₆Connected to the base of
Transistor Q₇When is turned on
Dista Q ₆Turn off when no base current is supplied
It

On the other hand, the transistor Q₆Is turned off,
Transistor Q₉Turns off and transistor Q₈Is o
Capacitor C₇Charge of the transistor
Q ₈Is discharged by the above time constant through the capacitor
C₇The voltage across both ends of the₁of
When the inverting input is lower than the non-inverting input, the comparator
IC₁Output becomes L level. And again Transi
Star Q₇Turns off, so transistor Q₆Is on
It

The above circuit operation will be described with reference to the time chart shown in FIG. 9. In the preheating operation state (left half in FIGS. 9A to 9D) immediately after power-on, the output of the comparator IC ₂ is at L level. Therefore, the input voltage of the non-inverting input of the comparator IC _{1 at} this time becomes V ₁ . Therefore, as shown in FIG. 9A, in the preheating operation state, the capacitor C input to the inverting input terminal is
₇ the voltage across the input voltage V ₁ of the non-inverting input is compared, and the output of the comparator IC ₁ is switched to the H level and the L level, as shown in FIG. (C), the collector of the transistor Q ₆ Period when current flows, that is transistor Q
_The period in which ₆ is on is shorter than the on period when the discharge lamp 6 is lit, shown in the right half of the figure. for that reason,
Since the high frequency voltage applied to the discharge lamp 6 becomes lower than the starting voltage of the discharge lamp 6, the discharge lamp 6 does not light up in the preheating operation state.

When the preheating operation is completed after a lapse of a predetermined time, the output of the comparator IC ₂ becomes H level, so that the input voltage of the non-inverting input of the comparator IC ₁ is V.
_As shown in the right half of FIG. 9C, the ON period of the transistor Q ₆ is longer than in the preheating operation state, the discharge lamp 6 is turned on, and the inverter circuit 4 is turned on.

[0018]

By the way, in the above-mentioned conventional configuration, since the chopper circuit 2 is operated immediately after the AC power source 1 is turned on, there are the following problems.
That is, when the discharge lamp 6 is operated as described above, the voltage applied by the inverter circuit 4 to the discharge lamp 6 is increased during the period when the discharge lamp 6 shifts from the preheated state to the lighting state (starting lighting period of the discharge lamp 6). Since the discharge lamp 6 is in a transient state and the equivalent impedance is abruptly changed from a state in which the equivalent impedance is infinite at the time of preheating to a relatively low impedance in order to start and illuminate, the inverter circuit 4 in this transient state. The amount of change in the resonance current flowing through the switch increases. On the other hand, the differential amplifier IC ₃ of the chopper control circuit 3, since it is set that the feedback impedance to not respond to the ripple included in the AC power supply 1 as described above, the chopper control circuit 3 follows immediately thereto However, there is a problem in that the DC output voltage V _DC of the chopper circuit 2 drops significantly below the desired voltage.

Further, it follows a load change in a transient state.
Switching element Q₁Larger inflow current to
It is necessary to operate the switching element Q₁Is stressful
There is also the problem of getting worse. Furthermore, the inverter circuit 4
Is supplied from the chopper circuit 2 as described above.
DC voltage V_DCIs unstable, the
Langista Q_Five, Q ₆It is difficult to control the stable operation of the
It is difficult to change the light output of the pump 6 smoothly.
Moreover, due to the influence of transient current, etc., the transistor Q_Five, Q₆
There is also the problem of increased stress.

The present invention has been made in view of the above points, and it is an object of the present invention to stabilize the operating states of an inverter circuit and a discharge lamp as a load of a chopper circuit at the time of starting, Another object of the present invention is to provide a discharge lamp lighting device with less stress on circuit elements.

[0021]

In order to achieve the above object, the invention of claim 1 controls the output of the chopper circuit according to the output of the chopper circuit for producing the DC power supply from the AC power supply. A chopper control circuit, an inverter circuit that creates high-frequency power to be supplied to a discharge lamp by a switching operation of a switching element using a DC power supply supplied from the chopper circuit as a power source, and an inverter control circuit that controls the switching operation of the switching element. The chopper control circuit operates the chopper circuit immediately after the power is supplied from the AC power source, and the inverter control circuit causes the inverter circuit to limit the output to a small amount to preheat the filament of the discharge lamp, and to perform a predetermined operation. After a certain period of time, the discharge lamp is turned on with the desired output, and the In the transient state from the thermal operating state to lighting operation state is characterized by bringing the output of the inverter circuit is gradually output the desired lighting operation conditions.

The invention of claim 2 is characterized in that, in the invention of claim 1, the time required for the transient state of the inverter circuit is set according to the power consumption of the discharge lamp. According to a third aspect of the present invention, in the first aspect of the present invention, the chopper control circuit includes a differential amplifier that detects an output voltage of the chopper circuit, compares the output voltage with a reference voltage, and outputs a voltage according to the difference, and the differential amplifier. The output control of the chopper circuit is performed according to the output of the amplifier, and the input-output response time of the differential amplifier in at least one of the preheating operation state and the transient state of the inverter circuit is set to be greater than the response time in the lighting operation state. It is characterized by comprising a response switching means for switching the response of the differential amplifier so as to be faster.

[0023]

In the structure of the first aspect of the invention, the chopper circuit is operated immediately after the AC power is supplied from the chopper control circuit, and the output of the inverter circuit is limited to a small value by the inverter control circuit to preheat the filament of the discharge lamp. The discharge lamp is lit at a desired output after a predetermined time, and in the transition state from the preheating operation state to the lighting operation state, the output of the inverter circuit is gradually changed to the desired lighting operation state. Since the output is made closer to the output, by gradually changing the output of the inverter circuit in the transient state, the load fluctuation on the chopper circuit becomes gradual, and thereby it is possible to prevent the stress on the circuit element in the transient state from increasing. Inverter circuit or discharge run as load of chopper circuit In which it is possible to stably operate.

In the configuration of the second aspect of the present invention, since the time required for the transient state of the inverter circuit is set according to the power consumption of the discharge lamp, the operating state of the discharge lamp when the discharge lamp is in the transient state is started. It can be stabilized. In the configuration of the invention of claim 3,
The chopper control circuit includes a differential amplifier that detects the output voltage of the chopper circuit, compares it with a reference voltage, and outputs a voltage corresponding to the difference, and controls the output of the chopper circuit according to the output of this differential amplifier. A response for switching the response of the differential amplifier such that the input-output response time of the differential amplifier in the preheat operation state and / or the transient state of the inverter circuit is faster than the response time in the lighting operation state. Since it has sex switching means,
The chopper circuit can immediately respond to the load change in the preheating operation state and the transient state, and the decrease in the output of the chopper circuit can be prevented.

[0025]

【Example】

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. As shown in FIG. 1, the basic configuration of the discharge lamp lighting device of the present embodiment is that a discharge lamp 6 uses a chopper circuit 2 that creates a DC power supply from an AC power supply 1 and a DC power supply supplied from this chopper circuit 2 as a power supply. Inverter circuit 4 that creates power supply to
And a chopper control circuit 3 that controls the output of the chopper circuit 2, and an inverter control circuit 5 that controls the driving of the switching elements included in the inverter circuit 4.

The chopper control circuit 3 uses the AC power source 1
The chopper circuit is operated immediately after the power is supplied from. On the other hand, the inverter control circuit 5 operates to preheat the filament of the discharge lamp 6 by limiting the output of the inverter circuit 4 to a small value immediately after the DC power is supplied from the chopper circuit 2, and after a predetermined time, outputs the desired output. In the operating state in which the discharge lamp 6 is lit, the output of the inverter circuit 4 is gradually changed in the desired lighting operating state during the transitional period from the preheating operating state to the lighting operating state, that is, in the starting lighting period of the discharge lamp 6. The inverter circuit 4 is operated so as to approach the output.

The specific configuration of the discharge lamp lighting device of this embodiment that achieves the above operation will be described below. The chopper circuit 2, the chopper control circuit 3, and the inverter circuit 4 in the present embodiment have the same configurations as those of the conventional circuit, and the same reference numerals are given to those components, and the description thereof will be omitted, which is a feature of the present embodiment. Only the points will be described. That is, in the present embodiment, in the inverter control circuit 5 having a circuit configuration almost common to the conventional circuit, the capacitor C ₉ is connected in parallel with the resistor R ₁₃ connected to the output terminal of the comparator IC ₂ . Is different from the above case.

Next, the operation of this embodiment is shown in FIG.
This will be described with reference to a chart. First, time t₀Power on
When the power is turned on and the power supply from the AC power supply 1 is started,
DC generated from AC power supply 1 in chopper circuit 2
Power is supplied to the inverter circuit 4. On the other hand, chopper
The starting circuit 7 is operated by the DC power supplied from the circuit 2.
Then, the inverter circuit 4 is activated. Also, chopper times
Control power supply voltage V as well as creation of DC power supply in path 2_ccOccurs
Then, the comparator IC of the inverter control circuit 5 ₂Non-anti
Capacitor C connected to the input terminal₈Begins to charge
It This capacitor C₈The voltage across both ends of the comparator IC
₂Reference voltage V which is the inverting input of_ref2Lower than
Comparator IC₁The voltage V is applied to the non-inverting input of₁Is entered
As described above, the transition of the inverter circuit 4
Q₆Is turned on for a relatively short time, and the
Since the power supplied from the data circuit 4 to the discharge lamp 6 is small
The discharge lamp 6 does not light up and the discharge lamp 6 filament
Is preheated.

Then, at time t₁At capacitor C₈
Is the reference voltage V_ref2If it exceeds the
Comparator IC on the road₂Output goes to L level
Comparator IC₁The voltage V is immediately applied to the non-inverting input of
₂However, in this embodiment, the resistance R₁₃To
Capacitor C in parallel₉Is connected, the resistance R ₁₃
Resistance value and capacitor C₉With the time constant determined by the capacity of
Capacitor C₉The voltage between both ends of the₂To
In the comparator IC₁The non-inverting input of is the voltage V₂Reached
To do. That is, the transistor Q of the inverter circuit 4₆
Capacitor C is also turned on₉When the voltage across the
It will gradually become longer. Therefore, FIG.
As shown in (b), time t₁~ T₂Discharge run in the period
Since the voltage applied to the
The change in the equivalent impedance of group 6 also becomes gentle,
t₂When the applied voltage reaches the starting voltage at
6 lights up, and thereafter the discharge lamp 6 is in a steady lighting state.
It

On the other hand, the period of the transient state from time t ₁ to t _{2 when} the operation of the inverter circuit 4 shifts from the preheating operation to the lighting operation, that is, the starting lighting period T (= t ₂ -t ₁ ) of the discharge lamp 6.
In the above, it is necessary to set the starting lighting time T so that the differential amplifier IC ₃ of the chopper control circuit 3 can follow the load fluctuations of the inverter circuit 4 and the discharge lamp 6 which are the loads of the chopper circuit 2. That is, the discharge lamp 6
Rate of change when the power consumption of the lamp rises from the power consumption W ₁ during the preheating operation to the power consumption W ₂ during the lighting operation (Fig. 2
The relationship between (the slope of the straight line in (c)) and the feedback impedance formed by the resistor R ₆ and the capacitor C ₄ of the differential amplifier IC ₃ of the chopper control circuit 3 may satisfy the following equation.

[0031] _{(W 2 -W 1) / T} ≦ 80 / (R 6 · C 4) ··· ( Equation 2) where the capacity C ₄ of the resistance value R ₆ and capacitor C ₄ of the resistor R ₆ is ( Since the power consumption W ₁ and W ₂ are determined by the formula 1) and the power consumption W ₁ and W ₂ are determined by the characteristics of the discharge lamp 6, if the start lighting period T is set so as to satisfy the formula 2, this start It is possible to prevent the output voltage V _DC of the chopper circuit 2 from decreasing during the lighting period T.
When the change in the power consumption of the discharge lamp 6 is non-linear as shown in FIG. 3, the tangent line having the maximum inclination is the tangent line of the curve showing the rate of change in the power consumption (see FIG. The starting lighting period T may be defined by the dotted line A) in 3.

The inverter circuit 4 is similar to that of this embodiment.
Is not limited to a half-bridge configuration, but a full-bridge configuration
It may be composed of one or one stone, or it may be a separately excited type.
May be. Furthermore, the discharge lamp 6 is not limited to one
It may be one. (Embodiment 2) FIG. 4 shows another embodiment of the present invention. In addition,
The basic configuration of the discharge lamp lighting device of this embodiment is the same as that of the first embodiment.
Since it is common with, the same symbols are used for common parts.
To omit the description, and only the features of the present embodiment will be described.
explain about. That is, in this embodiment, the chopper
Differential amplifier IC included in the control circuit 3₃Return of Impeda
Capacitor C_FourIn series with capacitor C_Ten
And switching element Q _TenThe point of connecting the series circuit with
And a comparator IC included in the inverter control circuit 5₂
Comparator IC to the non-inverting input terminal of₆Non-inverting input end of
Comparator IC with connecting child₆Inverting input terminal
Reference voltage V to child_ref3Input, comparator IC₆Out of
Switching element Q by force_TenPoint to turn on and off
Is different from that of the first embodiment.

Next, the operation of this embodiment will be described.
The voltage across the capacitor C ₈ is input to the non-inverting input of the comparator IC ₆ and compared with the reference voltage V _ref3 . Here, the reference voltage V _ref3 is set to a voltage higher than the reference voltage V _ref2 input to the inverting input terminal of the comparator IC ₂ . Therefore, the time t _a from immediately after the power is supplied from the AC power supply 1 until the output of the comparator IC ₂ becomes the H level is longer than the time t _b until the output of the comparator IC ₆ also becomes the H level. On the other hand, when the output of the comparator IC ₆ is H level, the switching element Q ₁₀ is turned on, and conversely, the comparator IC ₆ is turned on.
_{Since the} switching element Q ₁₀ is turned off when the output of ₆ is at the L level, after all, the time t is t when the power is turned on.
In the period of 0 ≦ t <t _{b when} = 0, the switching element Q ₁₀ is turned off, the capacity of the feedback impedance of the differential amplifier IC ₃ becomes the combined capacity of the capacitors C ₄ and C ₁₀ , and the time t is t ≧ t t. During the period of _b , since the switching element Q ₁₀ is turned on, both ends of the capacitor C ₁₀ are short-circuited, so that the capacitance of the feedback impedance is only the capacitance of the capacitor C ₄ .

Here, the capacitors C ₄ and C _10
Let C _{f1 be} the combined capacitance of C _f2 and C _f2 be the capacitance of the capacitor C ₄ .
C _f1 is sufficiently smaller than C _f2 , and the capacitor C _{10 is set} so as to satisfy the following expression for the power supply frequency f of the AC power supply 1.
Set the capacity of. 1 / (2πC _f1 · R ₆ ) ≧ 2f (Equation 3) By setting as described above, the input-output response of the differential amplifier IC ₃ can be switched. That is, the period during which the inverter circuit 4 is performing the preheating operation and the discharge lamp 6
The response time of the differential amplifier IC _{3 in} the period of performing the starting lighting operation can be made faster than the response time in the period of performing the steady lighting operation in which the discharge lamp 6 is lit. As a result, during the start-up lighting period, the chopper control circuit 3 can follow the fluctuation of the load, and it is possible to prevent the output of the chopper circuit 2 from decreasing, and the resistance R
_{Since 6} and the capacitor C ₄ are also set so as to satisfy (Equation 1), stable operation can be performed without increasing harmonic components included in the input current of the AC power supply 1.

In this embodiment, the responsiveness switching means is composed of the capacitor C ₁₀ , the switching element Q ₁₀ and the comparator IC ₆ , but it is not limited to this. Further, the discharge lamp 6 is used during the period when the response is switched.
It may be only the starting lighting period.

[0036]

According to the invention of claim 1, a chopper circuit for producing a DC power supply from an AC power supply, a chopper control circuit for controlling the output of the chopper circuit according to the output of the chopper circuit, and a DC power supplied from the chopper circuit. The power supply is used as a power supply, and an inverter circuit that creates high-frequency power to be supplied to the discharge lamp by the switching operation of the switching element and an inverter control circuit that controls the switching operation of the switching element are provided. Immediately after the power is supplied, the chopper circuit is operated, and the inverter control circuit limits the output to the inverter circuit to preheat the filament of the discharge lamp, and after a predetermined time, lights the discharge lamp at the desired output. Set to the operating state, and from this preheating operating state to the lighting operating state In the transient state, the output of the inverter circuit is gradually brought closer to the output in the desired lighting operation state. Therefore, by gradually changing the output of the inverter circuit in the transient state, the load fluctuation on the chopper circuit is moderated. be able to.
As a result, it is possible to prevent an increase in stress on the circuit element in the transient state and to stably operate the inverter circuit and the discharge lamp as the load of the chopper circuit.

According to the second aspect of the present invention, the time required for the transient state of the inverter circuit is set according to the power consumption of the discharge lamp. Therefore, the operating state of the discharge lamp at the time of starting the discharge lamp in the transient state is stabilized. The effect is that you can. According to a third aspect of the present invention, the chopper control circuit includes a differential amplifier that detects an output voltage of the chopper circuit, compares the output voltage with a reference voltage, and outputs a voltage corresponding to the difference, and the chopper according to the output of the differential amplifier. The output of the circuit is controlled, and the differential circuit is controlled so that the input-output response time of the differential amplifier in at least one of the preheat operation state and the transient state of the inverter circuit is faster than the response time in the lighting operation state. Since the responsiveness switching means for switching the responsiveness of the amplifier is provided, the chopper circuit can immediately respond to the load change in the preheating operation state and the transient state, and the decrease in the output of the chopper circuit can be prevented. Not only the output of the power supply can be stabilized, but also the inverter circuit as a load and the discharge lamp can be operated stably. A.

[Brief description of drawings]

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

FIG. 2 is a time chart for explaining the operation of the above, (a) is a non-inverting input of a comparator IC ₁ ,
(B) is a figure which shows the applied voltage of a discharge lamp, (c) is a figure which shows the power consumption of a discharge lamp.

FIG. 3 is another time chart of the power consumption of the discharge lamp in the above.

FIG. 4 is a specific circuit diagram showing a second embodiment.

FIG. 5 is a block diagram showing a schematic circuit configuration of a conventional example.

FIG. 6 is a specific circuit diagram of an AC power supply, a chopper circuit, and a chopper control circuit of the above.

7A to 7D are time charts for explaining the operations of the chopper circuit and the chopper control circuit of the same.

FIG. 8 is a specific circuit diagram of the above inverter circuit and inverter control circuit.

9 (a) to 9 (d) are time charts for explaining the operation of the above inverter circuit and inverter control circuit.

[Explanation of symbols]

1 AC power supply 2 Chopper circuit 3 Chopper control circuit 4 Inverter circuit 5 Inverter control circuit 6 Discharge lamp Q ₁ Switching element Q ₅ , Q ₆ Transistor IC ₁ , IC ₂ Comparator IC ₃ Differential amplifier C ₉ Capacitor

Claims (3)

[Claims] 1. A chopper circuit for producing a DC power supply from an AC power supply, a chopper control circuit for controlling the output of the chopper circuit according to the output of the chopper circuit, and a DC power supply supplied from the chopper circuit as a power supply for a switching element. The chopper control circuit comprises an inverter circuit that creates high-frequency power to be supplied to the discharge lamp by switching operation, and an inverter control circuit that controls the switching operation of the switching element. The chopper control circuit is a chopper immediately after power is supplied from an AC power supply. The circuit is operated, and the inverter control circuit controls the inverter circuit to limit the output to a small value to preheat the filament of the discharge lamp, and after a predetermined time, put the discharge lamp into operation with the desired output. Inverter in the transient state from the operating state to the lighting operating state A discharge lamp lighting device, wherein the output of the circuit is gradually brought closer to the output in a desired lighting operation state. 2. The discharge lamp lighting device according to claim 1, wherein the time required for the transient state of the inverter circuit is set according to the power consumption of the discharge lamp. 3. The chopper control circuit includes a differential amplifier which detects an output voltage of the chopper circuit, compares the output voltage with a reference voltage, and outputs a voltage corresponding to the difference between the reference voltage and the chopper circuit according to the output of the differential amplifier. The output control is performed so that the input-output response time of the differential amplifier in at least one of the preheating operation state and the transient state of the inverter circuit is faster than the response time in the lighting operation state. 2. The discharge lamp lighting device according to claim 1, further comprising a response switching means for switching response.