JP3285231B2 - Discharge lamp lighting device - Google Patents

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 using an inverter for converting DC power to AC power.

[0002]

2. Description of the Related Art FIG. 18 shows a conventional half-bridge inverter device used as a discharge lamp lighting device. In this inverter device, MO is connected between both ends of the DC power supply E.
Switching elements S ₁ and S ₂ composed of SFETs are connected in series, and a load circuit composed of at least a resonance circuit composed of an inductor L ₁ and a capacitor C ₂ and a discharge lamp La as a load is connected to a DC cut capacitor C ₁ . is connected to both ends of the switching element S ₂ through. Further, the DC cut capacitor C ₁ has a capacity normally equal to that of the capacitor C _{1.
Since it} is considerably larger than the capacitance of ₂ , it is not usually included in the resonance circuit, but may be included in the resonance circuit depending on the capacitance.

Under the control of the control circuit 1, each of the switching elements S ₁ and S ₂ of the inverter device shown in FIG.
The DC power supply E is turned on and off alternately as shown in FIG.
Is converted into an AC voltage (in this case, a high-frequency voltage) and supplied to the discharge lamp La, and the discharge lamp La is turned on at a high frequency.
This operation will be described in detail below. Now, at time t ₀ , FIG.
Control output V ₁ is a high level of the control circuit 1 (a), when the control output V ₂ as shown in FIG. (B) goes low, the switching element S ₁ is turned on, switching element S ₂ is turned off. At this time, the switching element S ₁ , inductor L ₁ , DC cut capacitor C ₁ , capacitor C ₂
In addition, a current is supplied to the discharge lamp La through the path of the discharge lamp La.

[0004] At this time, the capacitor C ₁ is DC blocking is charged. Energy is also stored in the resonance circuit. The case where the operating frequency of the inverter circuit is set to a range higher than the resonance frequency of the resonance circuit will be described below. In this case, energy stored in the inductor L ₁ is affected mainly the circuit operation as described below.

At time t ₁ , FIG.
As shown in the figure, the control output V1 of the control circuit ₁ is low level,
Control output V ₂ as shown in FIG. (B) becomes high level, the switching element S ₁ is turned off, the switching element S ₂ is turned on. However, unlike the pure switch in the switching elements S ₁ and S ₂ , when a voltage having a polarity opposite to the normal voltage (a voltage having a polarity opposite to the polarity of the DC power supply E) is applied to the switching element S ₂ , Originally
The direction of flow of the current I _S2 is (current direction indicated by the arrow in FIG. 18) has a parasitic diode having a function of flowing a current in the opposite direction. Therefore, when turning on the switching element S _2, the original current direction does not become turned on, current flows through the parasitic diode of the switching element S ₂ in the energy stored in the inductor L _2. That is, the switching element S ₂ is in a state where conduction in the reverse direction. Then, a current flows in the same direction as far inductor L ₁
The action, by energy stored in the resonant circuit,
A current flows through the path of the inductor L ₁ , the DC cut capacitor C ₁ , the capacitor C _{2, the} discharge lamp La, and the parasitic diode of the switching element S ₂ . That is, since the operating frequency of the inverter circuit is set in a range higher than the resonance frequency of the resonance circuit, the load circuit operates as described above.

When the current of the resonance circuit becomes zero,
From the point, the switching element S ₂ is the original ON state (a state in which current I _S2 flows in a direction indicated by an arrow in FIG. 18), a DC cut capacitor C ₁ con resonance circuit
With the electric charge accumulated in the capacitor C ₂ and the power supply, a current in the reverse direction flows through the path of the DC cut capacitor C ₁ , the inductor L ₁ , the switching element S ₂ , the capacitor C _2, and the discharge lamp La.

After that, at time t ₂ , as in the case of time t ₀ , the control output V ₁ of the control circuit ₁ is at a high level.
Since the control output V ₂ as shown in (b) becomes a low level, the switching element S ₁ is turned on, the switching element S ₂ is turned off. However, it should not turned on in the switching element S ₁ even when the flow direction original current I _S1 (direction indicated by an arrow in FIG. 18), the resonance times
Parasitic diode of the switching element S ₁ is turned on by the energy stored in the road. That is, the switching element S
₁ becomes a state of conduction in the reverse direction. Then, the energy stored in the resonant circuit, the parasitic diode of the switching element S _1, a DC power source E, a capacitor C ₂ and the discharge lamp La, the current path of the DC cut capacitor C ₁ flows.

When the current of the resonance circuit becomes zero,
From this point , the switching element S ₁ is turned on, and the DC power supply E, the switching element S ₁ , and the inductor L
₁ , a current flows through the path of the DC cut capacitor C ₁ , the capacitor C ₂ and the discharge lamp La. Hereinafter, by repeating the above series of operations, the DC power supply E is converted into high-frequency power, and high-frequency power is supplied to the discharge lamp La. At this time, the current I _L1 flowing through the inductor L ₁ is as shown in FIG.

In the above description, the switching element S ₁ is turned on in the original current direction at time t ₀ , but the switching elements S ₁ and S ₂ have been described up to that time.
Are turned on and off alternately, at time t ₀
Current also flows by turning on the parasitic diode of the switching element S ₁ in, followed by the original switching element
It goes without saying that the transistor is turned on in the direction in which the current I _{S1 of} S ₁ flows. In the above description, the switching element S
_Although the parasitic diodes ₁ and S ₂ are used to release the energy of the inductor L ₁ , the switching elements S ₁ and S 2
Diodes may be connected in antiparallel to _{2 respectively} .

[0010]

When the power supplied to the load in the inverter device (that is, the output of the inverter device) is varied, the switching elements S ₁ , S ₁
Change the switching frequency of ₂ . When the load is the discharge lamp La as described above, dimming control of the discharge lamp La is performed.

Here, as described above, when the switching frequency of the switching elements S ₁ and S ₂ is set to a range higher than the resonance frequency of the resonance circuit, if the switching frequency is lowered, the switching frequency becomes higher than the resonance frequency of the resonance circuit. approaches the frequency, the higher the voltage generated across the capacitor C _2, the power supplied is increased to the discharge lamp La. Conversely, if the switching frequency is increased, the switching frequency moves away from the resonance frequency of the resonance circuit,
Voltage generated across the capacitor C ₂ is lowered, the power supplied is reduced to the discharge lamp La.

However, when the DC power supply E is obtained by rectifying and smoothing the AC power supply, the switching elements S ₁ ,
Varying the switching frequency of the S _2, there is a high-frequency leakage problems to the AC power supply side. Therefore, a filter for preventing high-frequency components from leaking to the AC power supply side is provided at an input terminal of a diode bridge for rectifying the AC power supply. However, when the operating frequency of the inverter device changes as described above, there is a problem that the design of the filter for removing high-frequency components becomes complicated.

When the operating frequency of the inverter device is changed when the load is the discharge lamp La, the frequency of the light emitted from the discharge lamp La changes with the change. There is also the problem of adverse effects. Further, when the discharge lamp La is an HID lamp, there is a high possibility that an acoustic resonance phenomenon is caused by a change in the output frequency, which causes a problem related to reliability that the discharge lamp La is broken. That is, when the operating frequency of the inverter device increases, the possibility that the operating frequency coincides with the frequency at which the HID lamp causes an acoustic resonance phenomenon increases.

Therefore, as a conventional example which can improve this point, “Off-Line Application of Fixed-Frequency Clam”
ped Mode Series Resonant Converter ”, IEEE Tansacti
on onPower Electronics, Vol. 6; No. 1, January, 1991. In this conventional example, two sets of a series circuit of two switching elements are connected in parallel with a DC power supply,
A load circuit comprising at least an LC resonance circuit and a load is connected between the connection points of the switching elements of the respective series circuits, and the switching elements of the respective series circuits are alternately turned on and off so as not to be simultaneously turned on. The on / off phase of the switching element of the other series circuit is changed with respect to the on / off timing of the switching element of
It is as that.

The operation of the conventional example will be described in detail in the section of the embodiment of the present invention. According to this conventional example, the power supplied to the load can be changed without changing the operating frequency. However, the above-mentioned conventional example is applied particularly as a discharge lamp lighting device, and the discharge lamp La goes out in a state where the electric power supplied to the discharge lamp La is reduced at a low temperature.
Or flickering due to moving stripes . For this reason, there has been a problem that the dimming range of the discharge lamp La is limited.

The present invention has been made in view of the above points, and an object of the present invention is to adjust the power to be supplied to a discharge lamp without changing the frequency and to reduce the supplied power. An object of the present invention is to provide a discharge lamp lighting device capable of stably operating a discharge lamp even in such a case.

[0017]

According to the present invention, in order to achieve the above object, a first switching element and a second switching element which are connected in parallel to a DC power supply and are turned on and off without being simultaneously turned on. , A second series circuit of a third switching element and a fourth switching element which are connected in parallel to a DC power supply and are turned on and off without being simultaneously turned on, and switching elements of the first and second series circuits And a load circuit composed of a discharge lamp and at least an LC series resonance circuit connected between the connection points of the first switching element and a second switching cycle of the second switching element with respect to the first switching cycle of the first switching element. The first switching cycle and the second switching cycle are made different from each other as an integral multiple, and the first switching cycle and the fourth switching element And a switching period to the same, the third of the second switching cycle and the third switching element
And the on / off timings of the fourth and third switching elements of the second series circuit with respect to the on / off timings of the first and second switching elements of the first series circuit. Ru <br/> have is varied.

In order to prevent fluctuations in the power supplied to the load due to fluctuations in the power supply voltage, the fluctuations in the power supply voltage are detected, and the on / off timing of the switching element of one of the series circuits is changed. The power supplied to the load may be controlled to be constant by adjusting the on / off timing of the switching element. Further, in order to supply a constant power to the load, the load current is detected, and the on / off timing of the switching element of one series circuit is turned on / off of the switching element of the other series circuit. The off timing may be adjusted to control the load current to be constant.

Further, when power is supplied to a plurality of loads, a plurality of series circuits composed of the other two switching elements are provided, and a connection point of the switching element of one series circuit and a connection point of each other series circuit are connected. Between at least L
A plurality of load circuits including a C resonance circuit and a load can be respectively connected. In this case, it is also possible to prevent all the switching elements of the other series circuit from being simultaneously turned on.

When starting the discharge lamp when the load is a discharge lamp, the switching frequency of the switching element is set to be higher than the resonance frequency of the LC resonance circuit at least when the discharge lamp is at a point of failure. What is necessary is just to make the switching frequency of the switching element close to the resonance frequency of the LC resonance circuit. Also, when the discharge lamp is used as the load, when starting the discharge lamp, the switching frequency of the switching element is set higher than the resonance frequency of the LC resonance circuit at least when the discharge lamp is in a faulty state. ON of the switching element of the series circuit of
The on / off timing of the switching element of the other series circuit may be changed from a phase shifted by 180 degrees from the off timing to the same phase.

Furthermore, at least one load is further provided, and at least one set of switching elements of the series circuit is further provided.
And the connection point of the switching element of this series circuit
Between the connection point of the switching element of one series circuit
It is also possible to connect the above-mentioned additional loads to separately supply electric power composed of an AC component and a DC component to the respective loads.

[0022]

According to the present invention, the first series circuit of the first
And the on / off timing of the second switching element, the on / off timing of the fourth and third switching elements of the second series circuit are varied, so that the switching frequency is not changed and the discharge lamp is It allows the supplied power to be adjusted, avoiding the various problems associated with changing the switching frequency. Further, the first switching cycle and the second switching cycle are made different from each other by setting the second switching cycle of the second switching element to an integral multiple of the first switching cycle of the first switching element. And the third switching cycle of the third switching element are made the same as the switching cycle of the fourth switching element and the fourth switching cycle of the fourth switching element. The positive and negative supply powers are unbalanced, the energy stored in the LC series resonance circuit can be supplied to the load as a DC component, and the discharge lamp can be prevented from going out or flickering due to moving stripes. .

[0023]

【Example】

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The inverter device of the present embodiment converts a DC voltage obtained by rectifying an AC power supply AC by a diode bridge DB into an AC voltage, and includes switching elements S ₁ and S ₂ and switching elements S ₃ and S ₄ . Connected between the output terminals of the diode bridge DB, respectively, between the connection point of the switching elements S ₁ and S _{2 and} the connection point of the switching elements S ₃ and S ₄ .
Series resonant circuit consisting of inductor L ₁ and capacitor C ₂ and is connected to a load circuit composed of the load Z. The load Z is coupled in parallel with the capacitor C _2. That is,
This inverter device has a so-called full bridge configuration in which the switching elements S _{1 to} S ₄ are bridge-connected.

In this type of ordinary full-bridge type inverter device, switching elements S ₁ and S ₄ and switching elements S ₂ and S ₃ provided at diagonal positions are generally turned on and off by the control circuit 1 as a set. Turn off to supply AC current to the load circuit. First, the above-mentioned general operation will be described in further detail so that the operation of the present invention can be easily understood.
Now, at time t ₀ , the control outputs V ₁ and V ₄ of the control circuit 1 go high, and the control outputs V ₂ and V ₃ go low. At this time, the switching elements S ₁ and S ₄ are connected as shown in FIG.
(A), to turn on as shown in (d), the switching element S _2, S ₃ is the figure (b), turned off as shown in (c), a diode bridge DB, the switching elements S _1, inductor L ₁ , the capacitor C ₂ and the load Z,
A current flows through the load Z through the path of the switching element S ₄ and the diode bridge DB . That is, the load current I _{Z in the} direction indicated by the arrow in FIG. 1 is supplied.

At time t ₂ , the control outputs V ₁ and V _{4 of the} control circuit 1 go low, and the control outputs V ₂ and V ₃ go high. Then, the switching elements S ₁ and S
₄ is turned off as shown in FIGS. 2A and 2D, and the switching elements S ₂ and S ₃ are turned on as shown in FIGS. 2B and 2C. Here, when the set higher than the resonant frequency of the resonant circuit composed of the switching frequency of the inverter device from the inductor L ₁ and capacitor C ₂ is
As described in the related art section, the energy stored in the resonance circuit causes the inductor L ₁ , the capacitor C ₂ and the load Z, the parasitic diode of the switching element S ₃ , the diode bridge DB, the AC power supply AC, and the switching element S ₂ Current flows through the path of the parasitic diode.

Then, the current of the resonance circuit becomes zero.
At this point , the switching elements S ₂ and S ₃ are turned on, and the switching element S ₂ is switched from the diode bridge DB.
_3, the capacitor C ₂ and the load Z, inductor L _1, the switching element S _2, a path of the diode bridge DB,
The load current I _Z flows in the opposite direction (the direction opposite to the arrow in FIG. 1). At time t ₄ , as in time t ₀ , the control outputs V ₁ and V ₄ of the control circuit 1 go to high level, and the control outputs V ₂ and V ₃ go to low level, and the switching elements S ₁ and S 3 ₄ is turned on, and the switching elements S ₂ and S ₃ are turned off. Also in this case, the co
The energy stored in the Fukairo, inductor L _1, a parasitic diode of the switching element S _1, the diode bridge DB, the AC power source AC, the switching element S
₄ the parasitic diode, a current flows through a path of the capacitor C ₂ and the load Z.

When the current of the resonance circuit becomes zero,
From the point of view, from the diode bridge DB, the switching element S ₁ , the inductor L ₁ , the capacitor C ₂ and the load Z,
In the path of the switching element S _4, current flows to the load Z. In the case where the inverter device is operating normal, even at the time t _0, after release of the stored energy of the resonant circuit through a parasitic diode of the switching element S _1, S _4, the switching element S _1, through the S ₄
A forward load current I _Z is supplied. There is also a device in which a diode is connected in anti-parallel to each of the switching elements S _{1 to} S _4, and a current of a resonance circuit flows .

By the way, in the case of the latter conventional inverter device described in the section of the prior art, when the power supplied to the load Z is changed, the series-connected switching shown in FIGS. The on / off timing of the elements S ₁ and S ₂ is shifted from the on / off timing of the switching elements S ₃ and S ₄ shown in FIGS. The switching elements S ₁ and S ₂ and the switching elements S ₃ and S ₄ connected in series between the output terminals of the diode bridge DB are turned on and off alternately.

Further, the operation of the conventional inverter device will be described in detail. Note that the following description is similar to the above case,
An example in which the switching frequency of the inverter device is set higher than the resonance frequency of the resonance circuit will be described. At time t ₁ , the switching element S ₃ is turned on , the switching element S ₄ is turned on , as shown in FIGS.
Therefrom by a diode bridge DB, a switching element S _3, capacitor C ₂ and the load Z, inductor L _1, the switching element S _2, the diode bridge DB
, The load current I _Z is supplied.

At time t ₂ , the switching element S ₂ is turned off as shown in FIG.
No voltage is applied to the power supply . The switching element S
₂ off at the same time, FIG. 3 the switching element S ₁ (a)
Control output V ₁ is applied from the control circuit 1 so as to turn on as shown in FIG. In this case, the energy stored in the resonance circuit is used as the inductor L ₁ and the switching element S ₁
, The load current I _Z flows in the same direction as before through the path of the parasitic diode, the switching element S ₃ , the capacitor C ₂ and the load Z.

At time t ₃ , as shown in FIG.
Switching element S ₃ is turned off. The switching element S ₄ 3 control outputs V ₄ from the control circuit 1 so as to turn on as shown in (d) is applied at the time of this. Therefore, when energy remains in the resonance circuit , the inductor L ₁ , the parasitic diode of the switching element S ₁ ,
Diode bridge DB, the AC power source AC, a parasitic diode of the switching element S _4, the capacitor C ₂ and the load Z
The current flows through the path.

When the current of the resonance circuit becomes zero,
From the point, both turned ON the switching element S _1, S _4, a diode bridge DB, a switching element S
₁ , inductor L ₁ , capacitor C ₂ and load Z, switching element S ₄ , diode bridge DB ,
The load current I _{Z in the} opposite direction to that before is passed. However,
In the event <br/> if the current is zero in the resonant circuit at the time of the time t _3, the control output V ₄ of the control circuit 1 is at the same time a high level, the switching element S ₄ is turned on. In this case, since already the switching element S ₁ in this time t ₃ is on, at time t _3, the diode bridge DB, the switching elements S _1, inductor L _1, a capacitor C ₂ and the load Z, the switching element S ₄ , Daioh
The route of Doburijji DB, the load current I _Z is Ru flow.

At time t ₄ , the switching element S ₁ is turned off, and the supply of the load current I _Z through the above path is stopped. At this time, a control signal V _{2 for} turning on the switching element S _{2 from} the control circuit 1 is simultaneously applied, and the energy accumulated in the resonance circuit causes the inductor L ₁ , the capacitor C ₂ and the load Z, the switching element S ₄ , current flows through a path of the parasitic diode of the element S _2.

At time t ₅ , the switching element S ₄ is turned off, and a high-level control output V _{3 of} the control circuit 1 for turning on the switching element S ₃ is applied as shown in FIG. 3C. At this time, if energy remains in the resonance circuit , the inductor L ₁ and the capacitor C ₂
And load Z, the parasitic diode of the switching element S _3,
Diode bridge DB, the AC power source AC, a route of the parasitic diode of the switching element S _2, current flows. After the current in the resonant circuit becomes zero, the diode bridge DB, a switching element S _3, capacitor C
₂ and the load Z, inductor L _1, the switching element S _2, a path of the diode bridge DB, the load current I _Z
Is shed.

[0035] Also in this case, at the time t _5, power of the resonant circuit
If the flow is zero, at time t _5, a diode bridge DB, a switching element S _3, capacitor C ₂
And load Z, inductor L ₁ , switching element S ₂ ,
In the path of the diode bridge DB, Ru <br/> load current I _Z flows. It should be noted that, at the time of steady-state operation, the time, even the time t ₁ t ₅
The operation state is the same as described above. By repeating the above series of operations, the diode bridge DB
Is converted to an AC voltage, and the AC voltage is supplied to the load circuit. In this inverter device, the simultaneous on-periods of the switching elements S ₁ , S ₄ and the switching elements S ₂ , S _{3 at} the diagonal positions are shorter than in the case where they coincide as shown in FIG. The power supplied is reduced. Incidentally, it is set <br/> lowest range not higher than the resonance frequency of the resonance circuit the switching frequency of the inverter device.

That is, in this inverter device, the on / off phase of the switching elements S ₃ and S ₄ is changed with respect to the on / off timing of the switching elements S ₁ and S ₂ , so that the switching element S ₁ , by changing the time S ₄ and the switching element S _2, S ₃ is turned on at the same time, without changing the switching frequency of the switching elements S ₁ to S _4, it is possible to vary the power supplied to the load circuit It is. Therefore, the AC power source A
This facilitates the design of a filter (not shown) for preventing the leakage of the high-frequency output to C. Further, when the load Z is a discharge lamp, the frequency of the light emitted from the discharge lamp does not change and does not adversely affect other devices such as an infrared remote controller. Further, when the discharge lamp is an HID lamp, the possibility that an acoustic resonance phenomenon is caused by a change in the output frequency can be reduced.

In the above description, the case where the switching phase of the switching elements S ₃ and S ₄ is delayed with respect to the switching phase of the switching elements S ₁ and S ₂ is described. The power supplied to the load circuit can be changed. However, when the load Z is a discharge lamp in the inverter device, when the power supplied to the discharge lamp is reduced at a low temperature, the discharge lamp goes out and the dimming control range of the discharge lamp becomes narrow. is there. Also, reduce the power supplied to the discharge lamp.
In such a case, there is a problem that flickering may occur due to moving stripes.
You.

Therefore, in this embodiment, this point is improved.
For example, as shown in FIG._Two, S_Three
Switching frequency (switching cycle)
Element S₁, S_FourThe switching frequency (switchon
Cycle). In this embodiment, the switch
Switching element S_Two, S_ThreeIs the switching element S₁, S _Four
With the off point of
It is turned on.

This operation will be further described in detail. Note that time t
The operations from _{0 to} t ₃ are the same as the operations described with reference to FIG. Also, this description will be made for a case where the switching frequency of the inverter device is higher than the resonance frequency of the resonance circuit. At time t _3, the switching element S _2, S ₃ is not turned ON. For this reason, the storage in the resonance circuit
Depending on the accumulated energy, the inductor L ₁ , the capacitor
Sa C ₂ and the load Z, the parasitic diode of the switching element S ₃
Mode, diode bridge DB, AC power supply AC, switch
Current flows through a path of the parasitic diode of the quenching element S ₂
You .

At time t ₄ , the switching elements S ₁ , S
The _4-one, from the diode bridge DB, the switching elements S _1, inductor L _1, a capacitor C ₂ and the load Z, the switching element S _4, the diode bridge D
In the path of the B, the load current I _Z is flowed. Incidentally, at this time, if the remaining energy in the resonant circuit, in a form added to the output of the diode bridge DB, the load current I _Z is flowed, the energy stored in the inductor L ₁ becomes larger.

At time t ₅ , the switching elements S ₂ , S
_When the control signals V ₂ and V ₃ for turning on ₃ are given, the energy accumulated in the resonance circuit causes the inductor L ₁ , the load Z and the capacitor C ₂ , the parasitic diode of the switching element S ₃ , and the diode bridge DB , Exchange
Power AC, a current flows through the parasitic diode of the switching element S _2, by turning on the switching element S _2, S ₃ after the current in the resonant circuit becomes zero, the diode bridge DB, a switching element S _3, the load Z, the capacitor C ₂ , the inductor L ₁ , the switching element S ₂ , and the load of the load current I _Z through the path of the diode bridge DB.
Is supplied. The switching elements S ₂ and S ₃ are turned on within an on-period period.

[0042] In this manner, positive and negative voltages applied to the resonant circuit becomes unbalanced, the energy stored in inductor L ₁ is applied as a DC component in the load Z. FIG. 5 is different from FIG. 3 described above in that the on and off timings of the switching elements S ₁ and S _{2 and} the on and off timings of the switching elements S ₃ and S ₄ are shifted, so that the switching element S _{1 at the} diagonal position is shifted. , S ₄ and the switching elements S ₂ , S ₃ are simultaneously turned on, and the power supplied to the load Z is reduced.

In this way, the power supplied to the load Z can be changed without changing the switching frequency, as described with reference to FIG. Moreover, when the switching frequency of the switching element S _1, S ₄ and the switching element S _2, S ₃ are different (in this embodiment, the switching frequency of the switching element S _1, S ₄ of the switching element S _2, S ₃ switching Therefore, the positive and negative voltages applied to the resonance circuit become unbalanced, and a DC voltage is applied to the load Z. Therefore,
When the load Z is a discharge lamp, the discharge lamp can be stably lit even when the dimming state is deepened at a low temperature, and the dimmable range is not narrowed.

FIGS. 6 and 7 show specific circuits of the control circuit 1 in the inverter device. The control circuit 1 includes an oscillating circuit 2 that generates a square wave signal having a fundamental frequency, driving circuits 3 and 4 that drive switching elements S ₁ and S ₂ according to the output of the oscillating circuit 2, It comprises a delay circuit 5 for producing a signal whose output is delayed for a fixed time, and drive circuits 6 and 7 for driving the switching elements S ₃ and S ₄ according to the output of the delay circuit 5.

The oscillation circuit 2 includes a timer IC 2a, an external resistor R ₁₁ , variable resistors VR ₁₁ and VR of the timer IC 2a.
_12, is composed of a diode D _11, D ₁₂ and capacitor C _11, generates a rectangular wave signal of FIG. 8 (a). Here, by adjusting the variable resistor VR _11, VR _12, which is the ratio between the high-level period and the low level period of the square wave signal can be variably.

The drive circuit 3 for driving the switching element S ₁ sets a dead-off period for the output Va of the oscillation circuit 2 to prevent a short-circuit between the diode bridge DB by turning on simultaneously with the switching element S _2.
1, are constituted by a level shift circuit 32 to be supplied to the switching element S ₁ to the output of the dead circuit 31 to the level shift.

By the way, no explanation was given in the above case.
Are connected in series to the diode bridge DB
Switching element S₁, S_TwoAnd switching elements
S_Three, S _FourAre turned on at the same time,
In order to prevent this, the switching element S₁, S_Two
Or switching element S_Three, S_FourIs turned on and off
At the time of switching, the switching element S₁, S_TwoThere
Is the switching element S_Three, S_FourIs off
A dead-off period is provided.

The dead-off circuit 31, a variable resistor VR ₁₃ ~
VR ₁₅ , diodes D ₁₃ and D ₁₄ , capacitor C ₁₂ and buffer amplifier B ₁ . That is, the variable resistance V
The signal shown in FIG. 8C in which the rise of the output Va of the oscillation circuit 2 is delayed by a time determined by the time constants of R ₁₃ , VR ₁₄ and the capacitor C ₁₂ (period t ₀ −t ₁ in FIG. 8). .

The level shift circuit 32 includes a transistor Q
₁₁ to Q and the current mirror circuit CM ₃ consisting of _14, a buffer amplifier B _2, the diode bridge Zener diode ZD ₁ and a capacitor C to the output voltage to a constant voltage of DB
₁₈ and a constant voltage circuit 33. In the level shift circuit 32, in place of the current output of the dead-off circuit 31 in the current mirror circuit CM _3, transmits a signal to the buffer amplifier B ₂ to operate at different potentials, the control signal V ₁ the output of the buffer amplifier B ₂ providing the switching element S ₁ as.

The driving circuit 4 of the switching element S ₂ includes a dead-off circuit 41 to set the dead-off time to prevent a short circuit between the diode bridge DB and simultaneous ON and the switching element S ₂ from the output Va of the oscillation circuit 2,
From the output of the dead-off circuit 41, the switching element S
₁ are constituted by a frequency converting circuit 42 to create a control signal V ₂ to turn on the switching element S ₂ in the switching period of 2 times in synchronization with the time when turned off. Since the operation reference potential of the switching element S ₂ is consistent with the reference potential of the control circuit 1, the level shift circuit is not necessary.

The dead-off circuit 41 includes an inverter gate I ₁ , variable resistors VR _{16 to} VR ₁₈ , a diode D ₁₅ ,
D ₁₆ , a capacitor C ₁₃ and a buffer amplifier B ₃ . In the dead-off circuit 41 inverts the output Va of the oscillation circuit 2 in the inverter gate I ₁ (showing the inverted output Vb in FIG. 8 (b)), a time constant of the variable resistor VR _16, VR ₁₇ and capacitor C ₁₃ The determined time (t ₄ −t in FIG. 8)
The signal shown in FIG. 8D in which the rise of the output Va of the oscillation circuit 2 is delayed only for the period indicated by ₅ ). The frequency conversion circuit 42 generates a frequency-divided IC (for example, 4516B) 42a that generates an output obtained by dividing the frequency of the output Vn of the dead-off circuit 41 by 2 as a clock, the output O _{0 of the} frequency-divided IC 42a and the dead-off circuit 41. An AND gate AND ₄ for ANDing the output Vn. Dividing IC
The output of 42a is obtained as shown in FIG.
Taking the AND of the output Vn of the output Vo and the dead-off circuit 41, as shown in FIG. (S), the switching element S ₂ in the switching period of 2 times in synchronization with the time when the switching element S ₁ is turned off Control signal V ₂ for turning on
Is created.

The delay circuit 5 includes a delay time setting section 51 for setting a time for delaying the output Va of the oscillation circuit 2, and an output V of the oscillation circuit 2 according to the delay time of the delay time setting section 51.
and a delay signal creation unit 52 that creates a signal obtained by delaying the signal a as a whole. The delay time setting unit 51 includes variable resistors VR ₁₉ and VR ₂₀ , a diode D ₁₇ , a capacitor C ₁₄ ,
It is composed of inverter gates I ₃ and I ₄ and has a variable resistor VR.
₁₉ and time determined by the time constant of the capacitor C ₁₄ (e.g., the period indicated by t ₀ -t ₂ in FIG. 8) is the output Va of the oscillation circuit 2
Is the time to delay. More specifically, the charging of the capacitor C ₁₄ as shown in FIG. 8 (e) is started from the rise of the output Va of the oscillation circuit 2, when the voltage across the capacitor C ₁₄ reaches a threshold voltage of the inverter gate I _3, the output Vd of the inverter gate I ₃ is as shown in FIG. 8 (f).

The delay signal creation section 52 includes a delay time setting section 5
1 inverter gate I_ThreeOutput Vd and output of the oscillation circuit 2
AND gate AND to AND with force Va₁And the delay
Capacitor C to get time_FifteenAnd AND gate AN
D₁The output Vg of the capacitor C_FifteenTo charge transis
TA Q₂₀~ Q_{twenty four}Current mirror circuit CM consisting of₁And
Capacitor C_FifteenComparing the voltage between both ends of
Data CP₁And an inverter for inverting the output Va of the oscillation circuit 2.
Data gate I_TwoAnd the inverter gate I_TwoOutput Vf
Comparator CP₁AND with AND of output Vi
Gate AND_TwoAnd AND gate AND_TwoAnd the output Vj of
An OR gate that ORs with the output Ve of the delay time setting unit 51
To OR₁And OR gate OR₁Output Vk and inverter
Gate I _TwoAND gate A for ANDing with output Vf
ND_ThreeAnd AND gate AND_ThreeAccording to the output Vl of the
Capacitor C_FifteenTransistor Q that discharges_{twenty five}, Q₂₆From
Current mirror circuit CM_TwoIt consists of

The operation of the delay signal generator 52 will be described below. The AND gates the AND _1, the output Vd of the inverter gate I ₃ of the delay time setting unit 51 shown in FIG. 8 (f)
If, taking the AND of the output Va of the oscillation circuit 2, the output Vg of the AND gates the AND _1, as shown in FIG. 8 (i), period high corresponding to the delay time set by the delay time setting unit 51 Level. Period output Vg of the AND gates the AND ₁ is at high level, the capacitor C _15, as shown in FIG. 8 (j) is charged by a current mirror circuit CM _1. Here, since the reference voltage of the comparator CP ₁ is set at approximately 0V, the output Vi is kept at a high level as shown in FIG. 8 (k).

[0055] In the operation time described above, FIG. 8 so as shown in (h) the output Vf of the inverter gate I ₂ is at low level, the AND gate the AND ₂ As shown in FIG. (L)
Is at a low level. The output Vi of the comparator CP ₁ is maintained in a period high level capacitor C ₁₅ is charged. Now, FIG.
When the output Va of the oscillation circuit 2 goes low as shown in FIG. ₇ , the output Vf of the inverter gate I2 goes high as shown in FIG. Accordingly, the output Vj of the AND gates the AND ₂ As shown in FIG. (L) becomes high level. Thus, even after the output Ve of the inverter gate I ₄ of the delay time setting unit 51 has fallen to the low level, the output Vk of the OR gate OR ₁ is kept at a high level as shown in FIG. 8 (m).

At this time, the output V of the AND gate AND ₃
l by changes to the high level as shown in FIG. 8 (n), the current mirror circuit CM ₂ is operated, the capacitor C
₁₅ discharges are started. Here, the current mirror circuit C
M ₂ and the current mirror circuit CM ₁ a mirror ratio of 1:
Since is set to 1, as shown in FIG. 8 (j), after the same time as the delay time set by the delay time setting unit 51, the capacitor C ₁₅ is completely discharged.

[0057] When the capacitor C ₁₅ is completely discharged, the output Vi of the comparator CP ₁ becomes low level, as shown in FIG. 8 (k). Accordingly, the output Vj of the AND gates the AND ₂ becomes low level, as shown in FIG. 8 (l), a low level, as shown in the output Vk also drawing of the OR gate OR ₁ (m). The output V of the AND gates the AND ₃ by the output Vk of the OR gate OR ₁
l becomes a low level as shown in FIG. 8 (n), the operation of the current mirror circuit CM ₂ is stopped.

That is, the delay signal creation unit 52
The same amount of time as the time set in the time setting
Agate OR₁To delay the fall of the output Vk
Oscillation according to the delay time of the delay time setting unit 51
By creating a signal obtained by delaying the output Va of the circuit 2 as a whole,
I have. Then, based on the signal Vk, the driving circuits 6, 7
Is the switching element S_Three, S _FourDrive. Switchon
Element S_ThreeThe drive circuit 6 includes a dead-off circuit 61,
A number conversion circuit 62 and a level shift circuit 63
Switching element S_FourOf the drive circuit 7 is a dead-off circuit 7
1.

The dead-off circuit 61 includes an inverter gate I ₅ , variable resistors VR _{24 to} VR ₂₆ , a diode D ₂₀ ,
D ₂₁ , a capacitor C ₁₇ and a buffer amplifier B _5. The output Vk of the OR gate OR ₁ is connected to the inverter I ₅
The rising of the output Vm (shown in FIG. 8 (o)) inverted by
The dead-off period is set by delaying the time determined by the time constant of the variable resistors VR ₂₄ and VR ₂₆ and the time constant of the capacitor C ₁₇ (the period indicated by t ₆ -t ₇ in FIG. 8). This output Vp is shown in FIG.
It becomes as shown in.

The frequency conversion circuit 62 includes a dead-off circuit 6
A frequency dividing IC (for example, 4516B) 62a that generates an output obtained by dividing the frequency by 2 using the rising edge of one output Vp as a clock;
The output Vq of the frequency dividing IC 62a and the dead-off circuit 61
AND gate the AND ₅ take the AND of the output Vp of are constituted by. 8 (u) is obtained as the output Vq of the frequency dividing IC 62a. When the output Vq and the output Vp of the dead-off circuit 61 are ANDed, the output Vq shown in FIG.
As shown, the control signal V ₃ to the switching element S ₄ is to turn on the switching element S ₃ in the switching period of 2 times in synchronization with the time when the off is created.

[0061] The level shift circuit 63 includes a current mirror circuit CM ₄ composed of the transistors Q ₁₅ to Q _18,
It comprises a buffer amplifier B ₆ and a constant voltage circuit 64 comprising a Zener diode ZD ₂ for making the output voltage of the diode bridge DB a constant voltage and a capacitor C ₁₉ . The operation is the same as that of the level shift circuit 32. Dead-off circuit 71, the variable resistor VR ₂₁ to VR _23, the diode D
_18, D _19, Yes and a capacitor C ₁₆ and the buffer amplifier B _4, the rise of the output Vk of the OR gate OR ₁ variable resistor VR _21, VR ₂₂ and time determined by the time constant of the capacitor C ₁₆ (t in FIG. 8 ₂ period indicated by -t ₃₎ delays, sets the dead-off period. Its output V ₄ is as shown in FIG. (Q).

In this manner, the phase difference θ between the ON and OFF timings of the switching elements S ₁ and S ₂ and the switching elements S ₃ and S ₄ is represented by the time t in FIG.
₁₋ t ₃ . (Embodiment 2) FIG. 9 shows another embodiment of the present invention. This embodiment basically operates in the same manner as in the above embodiment. The feature of this embodiment is that the load Z is the discharge lamp La, and the operation of the above embodiment is applied. The point is that the discharge lamp La is satisfactorily preheated and is turned on.

When the discharge lamp La is out of order,
Becomes very high and does not affect the resonance of the resonant circuit.
Therefore, the resonance frequency becomes highest. So switching
Element S ₁~ S_FourOf the lowest switching frequency among
(In the case of the above embodiment, the switching element S_Two,
S_ThreeThe switching frequency of the resonance circuit
Set slightly higher than And the switching element
S₁~ S_FourOne with the highest switching frequency
(In the case of the above embodiment, the switching element S₁, S_Four)
Switching element S based on the control signal of₁, S_Two
Switching element S _Three, S_FourSwitching phase
The phase is changed from the state shifted by 180 degrees until the phase becomes the same.
By doing so, the switching element S₁, S_FourAnd
Switching element S _Two, S_ThreeThe period of simultaneous ON is short
State to a long state, and the discharge lamp La
To preheat the filament and then discharge to the discharge lamp La
The starting lighting can be performed by applying a starting voltage.

As a method for starting the discharge lamp La after preheating, the switching frequency of the inverter is changed to the resonance frequency of the resonance circuit, as in the case of a discharge lamp lighting device using this type of ordinary inverter. Needless to say, a method of starting and lighting by approaching may be adopted. However, at the time of steady lighting, it goes without saying that dimming control is performed by changing the simultaneous ON periods of the switching elements S ₁ and S ₄ and the switching elements S ₂ and S ₃ .

(Embodiment 3) FIG. 10 shows another embodiment of the present invention. This embodiment is basically the same as the above-described first embodiment, and is different from the first embodiment in that the power supplied to the load Z is prevented from fluctuating according to the power supply voltage fluctuation. There are features. In the case of the embodiment, the power fluctuation preventing circuit 8 which power supplied to the load Z by power fluctuations is prevented from varying, the transistor Q ₃₀ that change a conduction state in accordance with the output fluctuation of the diode bridge DB , it is composed of a photocoupler PC ₁ the input current varies according to the conduction state of the transistor Q _30.

That is, when the output voltage of the diode bridge DB changes, the diode bridge DB of the control circuit 1 changes.
Terminal a is connection to the output, the voltage between b is changed, the conduction state of the transistor Q ₃₀ is changed. Accordingly, the charging current change in the capacitor C ₁₄ changes the current flowing through the output transistor of the photocoupler PC _1, the delay time setting unit 5
The setting state of one delay time changes.

[0067] Now, when the power supply voltage increases, increased current to be bypassed by the transistor Q ₃₀ is, the photo-coupler P
Current input is reduced to C _1. Therefore, the output current decreases photocoupler PC _1, the charging time of the capacitor C ₁₄ becomes longer. Therefore, the switching elements S ₁ and S ₄
Further, the period during which the switching elements S ₂ and S ₃ are simultaneously turned on is shortened, and the power supplied to the load Z is reduced. Thereby, the current flowing through the load Z according to the power supply voltage fluctuation can be suppressed.

Conversely, when the power supply voltage decreases, the load Z
It functions to increase the power supplied to the. As described above, the power fluctuation prevention circuit 8 can stabilize the power supplied to the load Z by applying feedforward. For example, when the load Z is a discharge lamp, the power fluctuation prevention circuit 8 can perform stable lighting. (Embodiment 4) In the above embodiment, one load Z is used. However, as shown in FIG. 11, power may be supplied to a plurality of loads Z and Z 'from the same inverter device.
In the case of FIG. 11, a series circuit of a capacitor C ₄ and the load Z, and the inductor L ₂ and a series circuit of the load Z ', is connected across the capacitor C _2. If you do this,
Only the AC current due to resonance can flow through the load Z, and the DC component can mainly flow through the load Z ′. The load and Z 'is the discharge lamp, when connecting the inductor L ₂ at both ends of the non-power side of the filament of the discharge lamp, passing a preheating current to the filaments DC component generated in the inductor L _2, a low tone of the discharge lamp It is possible to stably light up to the light level.

(Embodiment 5) FIG. 12 shows another embodiment of the present invention.
Is shown. In this embodiment, the lamp current flowing through the discharge lamp La is
Detected and supplied to the discharge lamp La in accordance with the lamp current.
The power to be automatically adjusted. In this embodiment,
Switching element S_Three, S_FourSwitch in parallel with the series circuit of
Ching element S_Five, S₆And the inductor L₁And discharge
The series circuit with the lamp La is connected to the switching element S.₁, S_TwoContact
Connection point and switching element S_Three, S_FourConnection point
Then, inductor L₁And the connection point between
Ching element S_Five, S₆Capacitor C between the_Two
Is connected. And the switching element S _FourSaw
The current detection resistor R for detecting the lamp current₀Connect
I have. The switching element S_Five, S₆Is a switch
Ching element S_Three, S_FourOn and off in sync with each of
Therefore, the operation of the inverter device is no different from that of the above-described embodiment.
Works as expected.

That is, what is configured as described above is as follows.
In order to reliably detect the current of the discharge lamp La, the flow path of the lamp current and the flow path of the resonance current are separated.
If the lamp current decreases according to the detection output of the detection resistor R ₀ , the simultaneous ON periods of the switching elements S ₁ and S ₄ and the switching elements S ₂ and S ₃ are lengthened to increase the lamp current, Conversely, if the lamp current increases, switching elements S ₁ , S ₄ and switching elements S ₂ , S
The simultaneous control period of ₃ may be shortened, and the feedback control may be performed so as to reduce the lamp current .

Embodiment 6 FIG. 13 shows a discharge lamp lighting device using an inverter device for lighting a plurality of discharge lamps La. That is, the switching elements S ₁ and S ₂ are also used as discharge lamp lighting devices for the respective discharge lamps La, and switching elements S ₅ and S ₆ are newly connected in parallel to the switching elements S ₃ and S ₄ , respectively. The connection point between S ₁ and S ₂ and the switching elements S ₃ and S ₄
A first load circuit is connected between the switching elements S ₁ and S ₂ and the switching elements S ₅ and S ₅ .
The second load circuit is connected to the connection point ₆ . The switching elements S ₅ and S ₆ are turned on and off in synchronization with each of the switching elements S ₃ and S ₄ . Here, in the case of the present embodiment, the switching cycle of the switching elements S ₃ and S ₅ is lengthened as shown in FIG. Therefore, the present embodiment operates almost in the same manner as the first embodiment. With such a configuration, a multi-discharge lamp lighting device can be configured by adding a series circuit of one set of switching elements. In addition, there is an advantage that even if one of the discharge lamps La is in a faulty state, it does not affect the lighting state of the other discharge lamps La. In the above case, the case of two lamps has been described.
It can be applied to more than light .

(Embodiment 7) A plurality of discharges were performed in the same manner as in Embodiment 6.
Discharge lamp lighting device using inverter device for lighting lamp La
In the configuration, as shown in FIG.
Element S_Three~ S ₆Are controlled individually.
It is. FIG. 16 shows the operation state at time t.
₀~ T₁Then the switching element S ₁, S_FourTurn on,
Time t₁~ T_TwoThen the switching element S_Two, S_ThreeOn
And time t_Two~ T_ThreeThen the switching element S₁, S₆
At time t_Three~ T _FourSo any switching
Element S₁~ S₆At time t_Four~ T_FiveThen Sui
Switching element S₁, S_FourAt time t_Five~ T₆so
Switching element S _Two, S_FiveAt time t₆~ T
₇Then the switching element S₁, S₆At time t
₇~ T₈Then, any switching element S₁~ S₆Oh
It repeats a series of operations of not performing the operation. Toes
Switching element S_Three, S_FiveAnd switching elements
S_Four, S₆Are turned on alternately. like this
However, the plurality of discharge lamps La are substantially the same as in the first embodiment.
The lighting operation can be controlled by the operation of

[0073] Figure 17 shows another method of operation, the switching element S ₆ is turned on in the first half of the period to turn on the switching element S _1, the switching element S in the second half portion
₄ is operated, in which as the switching element S ₅ is turned on in the first half of the period to turn on the switching element S _2, turns on the switching element S ₃ in the second half portion. In other words, the switching phases of the switching elements S ₃ and S ₄ are delayed by 90 degrees with respect to the switching phases of the switching elements S ₁ and S ₂ , and the switching element S
_5, the switching phase of S ₆ in which is advanced 90 degrees. Even in this case, the lighting control can be performed by substantially the same operation as in the first embodiment.

In the above description, the case where the switching element is an FET has been described. However, a bipolar transistor or a thyristor in which a diode is connected in anti-parallel may be used. Needless to say, the DC power supply includes a pure DC power supply and a DC power supply formed by rectifying and smoothing an AC power supply.

[0075]

As described above, according to the present invention, the ON / OFF timing of the first and second switching elements of the first series circuit is controlled by the fourth and third states of the second series circuit, respectively.
To vary the on-off timing of the switching element
Since it is, without changing the switching frequency, the discharge
The power supplied to the lamp can be adjusted, and various problems associated with changing the switching frequency can be avoided. Further, the first switching cycle and the second switching cycle are made different from each other by setting the second switching cycle of the second switching element to an integral multiple of the first switching cycle of the first switching element.
And the fourth switching cycle of the fourth switching element are made the same, and the second switching cycle and the third switching cycle of the third switching element are made the same. Imbalances the positive and negative power supply so that the energy stored in the LC series resonance circuit can be supplied to the load as a DC component, and discharge
It is possible to prevent the lamp from going out or flickering due to moving stripes.

Further, the power supply voltage fluctuation is detected, and the on / off timing of the switching element of the other series circuit is adjusted with respect to the on / off timing of the switching element of the other series circuit. If the supplied power is controlled to be constant, it is possible to prevent fluctuations in the power supplied to the load due to power supply voltage fluctuations. Further, by detecting the load current and adjusting the on / off timing of the switching element of the other series circuit with respect to the on / off timing of the switching element of one series circuit, the load current is controlled to be constant. , And a constant power can be supplied to the load.

Further, a plurality of series circuits composed of the other two switching elements are provided, and at least an LC resonance circuit and a series circuit are connected between the connection point of the switching element of one series circuit and the connection point of each other series circuit. By connecting a plurality of load circuits composed of loads respectively, it is possible to drive a plurality of loads simultaneously, and since it is only necessary to add a series circuit composed of the other two switching elements according to the load,
The circuit configuration is simplified.

The load is a discharge lamp, and the switching frequency of the switching element is set to be higher than the resonance frequency of the LC resonance circuit at least when the discharge lamp is in a non-operational state. The on / off timing of the other series circuit can be changed from a phase shifted by 180 degrees from the on / off timing to the same phase with respect to the on / off timing of the other series circuit, so that the discharge lamp can be satisfactorily preheated to be turned on. it can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a basic operation of an inverter device having a full bridge configuration.

FIG. 3 is an operation explanatory diagram showing a method of varying power supplied to a load without changing a switching frequency.

FIG. 4 is an operation explanatory view showing a method of applying a DC component to a load as a main part of the present embodiment.

FIG. 5 is an explanatory diagram of an operation in a case where a DC component is applied to a load and power supplied to the load is changed without changing a switching frequency.

FIG. 6 is a circuit diagram showing a part of a specific configuration of the above control circuit.

FIG. 7 is a circuit diagram showing another part of the specific configuration of the control circuit of the above.

FIG. 8 is an explanatory diagram of an operation of the control circuit of the above.

FIG. 9 is a circuit diagram of another embodiment.

FIG. 10 is a specific circuit diagram of a control circuit provided with a power fluctuation prevention circuit.

FIG. 11 is a circuit diagram of an embodiment for driving a plurality of loads driven by AC and DC.

FIG. 12 is a circuit diagram of an embodiment having a function of constant control of a load current.

FIG. 13 is a circuit diagram of an embodiment for driving a plurality of loads.

FIG. 14 is an operation explanatory view of the above.

FIG. 15 is a circuit diagram of another embodiment for driving a plurality of loads.

FIG. 16 is an operation explanatory view of the above.

FIG. 17 is an operation explanatory diagram when the above is operated in a different state.

FIG. 18 is a circuit diagram of a conventional half-bridge inverter device.

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

[Explanation of symbols]

AC AC power supply DB Diode bridge S _{1 to} S ₄ Switching element L ₁ Inductor C ₂ Capacitor Z Load 1 Control circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05B 41/24 H05B 41/392

Claims (7)

(57) [Claims] A first switching element and a second switching element connected in parallel to a DC power supply and turned on and off without being turned on at the same time.
A first series circuit with a first switching element, a second series circuit with a third switching element and a fourth switching element which are connected in parallel to a DC power supply and operate on / off without being simultaneously turned on, A second switching element for a first switching period of the first switching element, comprising at least an LC series resonance circuit connected between the connection points of the switching elements of the two series circuits and a load circuit including a discharge lamp. The first switching cycle and the second switching cycle are made different by making the second switching cycle of the second integer an integral multiple, and the first switching cycle and the fourth switching cycle of the fourth switching element are made the same. 2 switching period and the third switching element
And the ON / OFF timings of the fourth and third switching elements of the second series circuit with respect to the ON / OFF timings of the first and second switching elements of the first series circuit, respectively. discharge lamp, characterized in that kick set a control circuit for controlling so as to vary
Lighting device. 2. A power supply voltage fluctuation is detected, and the on / off timing of the switching element of one series circuit is adjusted with respect to the on / off timing of the switching element of the other series circuit, so that the load is adjusted to the load. 2. The discharge lamp point according to claim 1, wherein the supplied power is controlled to be constant.
Lighting device. 3. A load current is detected, and the on / off timing of a switching element of one of the series circuits is determined.
2. The discharge lamp lighting device according to claim 1, wherein the on / off timing of the switching element of the other series circuit is adjusted to control the load current to be constant. 4. A series circuit comprising two other switching elements is provided, and at least an LC resonance circuit and a load are connected between a connection point of the switching element of one series circuit and a connection point of each of the other series circuits. 2. A discharge according to claim 1, wherein the plurality of load circuits are connected to each other.
Lighting device. 5. The discharge lamp lighting device according to claim 4, wherein all the switching elements of the other series circuit are not simultaneously turned on. 6. The load is a discharge lamp, wherein the switching frequency of the switching element is set to be higher than the resonance frequency of the LC resonance circuit at least when the discharge lamp is at a point of failure, and the switching frequency of the switching element is set when the discharge lamp is started. 2. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is configured to approach a resonance frequency of the LC resonance circuit. 7. The load is a discharge lamp, and the switching frequency of the switching element is set higher than the resonance frequency of the LC resonance circuit at least when the discharge lamp is in a non- operational state. First and second switches
The second series
ON of the fourth and third switching elements of the circuit respectively
Turn off the voltage generated between both ends of the load circuit.
Control to change from a low state to a high state
2. The discharge lamp spot according to claim 1, further comprising a circuit.
Lighting device .