JPH09308259A - Power supply, discharge lamp lighting apparatus and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely start a switching device of an inverter even when an impedance of a control terminal circuit of a switching device is low. SOLUTION: Since a charging voltage of a capacitor C8 is low when the power switch is turned on, transistors Q3, Q4 are turned off and a resistor R12 is disconnected from the gate circuit of a transistor Q1 and an impedance of this circuit becomes high. Therefore, after a charging voltage of a capacitor C1 rises and a transistor Q2 turns on and off, even if the potential generated in the secondary side CT2 of a saturable transformer is weak, this voltage is high enough to exceed the gate voltage of the transistor Q1 and thereby the switching of the transistors Q1, Q2 are surely started. Thereafter, when a charging voltage of a capacitor C8 rises and a zener diode ZD turns on to turn on Q3, Q4, the resistor R12 is connected to the gate circuit of Q1 to make an impedance of this circuit low and raises high frequency powers outputted from the transistors Q1, Q2 up to the rated value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device that outputs a high frequency voltage to a load, a discharge lamp lighting device that uses the power supply device to supply a high frequency voltage to a discharge lamp for lighting, and a discharge lamp lighting device. The lighting device used.

[0002]

2. Description of the Related Art FIG. 1 is a circuit diagram showing a configuration example of a conventional discharge lamp lighting device. In this example, a circuit for increasing the input power factor and reducing the harmonic component of the input current by flowing a charging current from the AC power source 1 side to the capacitor C3 to reduce the level of the harmonic component on the AC power source 1 side. The composition is adopted.

When the power source is turned on, the alternating current supplied from the commercial power source 1 is rectified by the rectifier circuit 2 and charges the capacitor C1 through the resistor R1. As a result, when the charging voltage of the capacitor C1 rises and exceeds the trigger voltage of the trigger diode TD, the trigger diode TD is turned on, and the discharge voltage from the capacitor C1 becomes the resistance R8 and the resistance R.
Is applied to the gate of a field effect transistor (hereinafter simply referred to as transistor) Q2 through
Turn 2 on. As a result, the rectified current of the rectifier circuit 2 flows through the capacitor C3, the primary side of the linkage transformer 3, the primary side CT1 of the saturable transformer, and the transistor Q2. Further, when the transistor Q2 is turned on, the diode D1 is turned on and the electric charge of the capacitor C1 is discharged to the transistor Q2 side through the diode D1 and its terminal voltage becomes low level to turn off the transistor Q2.

When the transistor Q2 is turned off, a current flows in the reverse direction to the primary side CT1 of the saturable transformer,
As a result, the voltage generated in the secondary side CT21 of the saturable transformer is applied to the gate of the field effect transistor (hereinafter simply referred to as transistor) Q1 to turn on the transistor Q1. As a result, the discharge current of the capacitor C3 and the rectification current of the rectifier circuit 2 flow through the transistor Q1, the primary side CT1 of the saturable transformer, the primary side of the linkage transformer 3, and the capacitor C4. Therefore, the voltage generated in the secondary side CT21 of the saturable transformer is continuously applied to the gate of the transistor Q1 and the transistor Q1 is kept in the ON state, but when the saturable transformer is saturated, the voltage generated in the secondary side CT21. Disappears and the transistor Q1 turns off.

When the transistor Q1 is turned off, a current flows from the capacitor C4 and the primary side of the linkage transformer 3 to the primary side CT1 of the saturable transformer, and after resetting the saturable transformer, the secondary side of the saturable transformer is reset. CT22
Is applied to the gate of the transistor Q2, turning on the transistor Q2. After that, the transistors Q1 and Q2 start switching at a high frequency, and the high frequency current flows through the primary side of the linkage transformer 3, so that a boosted high frequency voltage is generated and the high frequency voltage of this high voltage is discharged. Discharge lamp 4 applied to lamp 4
Lights up.

By the way, a circuit for changing the impedance of the gate circuit of the transistor Q2 is added to this example. That is, when the power is turned on, the capacitor C8 has a resistance R
7, the charging current flows, the terminal voltage of the capacitor C8 rises, and when this terminal voltage exceeds the Zener voltage, the transistor Q3 turns on, and the output voltage of the rectifier circuit 2 is the resistance R7, at the cathode of the diode D3. The voltage divided by the voltage dividing resistors of the resistor R9, the variable resistor VR, and the resistor R10 is applied. Therefore, when the voltage on the anode side of the diode D3 becomes higher than this divided voltage, the series circuit of the variable resistor VR and the resistor R10 is connected to the gate circuit of the transistor Q2, and the impedance of the gate circuit of the transistor Q2 is lowered. , By increasing the width of the drive voltage of the transistor Q2 and lengthening its on-duty,
The high frequency output is increased. By adjusting the variable resistor VR, the resistance value of the series circuit of the variable resistor VR and the resistor R10 connected via the diode D3 can be changed to adjust the magnitude of the high frequency output.

Here, in order to increase the high frequency power output from the transistors Q1 and Q2 due to reasons such as the wattage of the discharge lamp, the on-duty of the transistors Q1 and Q2 must be lengthened. To this end, the impedance forming the gate circuit of the transistors Q1 and Q2 is lowered to widen the peak width of the voltage generated from the secondary side CT21 and CT22 of the saturable transformer applied to the gates of the transistors Q1 and Q2. Is being done.

However, if the impedance forming the gate circuit of the transistors Q1 and Q2 is lowered for the above reasons, the following problems will occur when the switching of the transistors Q1 and Q2 is started. At startup,
The trigger diode TD is turned on, and a drive voltage is applied from the starting capacitor C1 to the gate of the transistor Q2 through the trigger diode TD. However, since the power of this drive voltage is strong, it is indicated by a in FIG. 2 (A). As described above, the gate voltage VTH for turning on the transistor Q2 is exceeded, the transistor Q2 is turned on, and a drain current as shown in FIG. 2C flows through this transistor.

Since the transistor Q2 discharges the electric charge of the starting capacitor C1, its gate voltage is lowered,
When turned off, the power of the voltage generated in the secondary side CT21 of the saturable transformer is low because the charging voltage of the capacitor C3 is not stable, and as shown in (b) of FIG. Does not reach the gate voltage VTH that turns on this transistor Q1,
I can't turn on 1. Therefore, as shown in FIG.
As shown in (D), the drain current does not flow through the transistor Q1, and eventually, the transistors Q1 and Q2 forming the inverter fail to start up.

[0010]

Problems to be Solved by the Invention Transistors Q1 and Q
When the on-duty of 2 is adjusted so as to obtain a desired high frequency output, the impedance of the gate circuits of the transistors Q1 and Q2 becomes too low. Therefore, the starting circuit turns on the transistor Q2 and turns off the transistor Q1. Since a high gate voltage for turning on the transistor cannot be obtained, the transistor Q1 cannot be turned on, and the switching of the transistors Q1 and Q2 fails to start.

Therefore, the present invention has been made to solve the above problems, and a power supply circuit that can reliably start a switching element even when the impedance of a control terminal circuit of the switching element is low. An object of the present invention is to provide a discharge lamp lighting device that uses a power supply circuit and has good startability, and a lighting device that uses this discharge lamp lighting device.

[0012]

According to a first aspect of the present invention, there is provided a direct current power source; a switching circuit having a plurality of switching elements, to which a voltage of the direct current power source is applied; and a high frequency based on turning on / off of the switching elements. An output circuit that outputs a voltage and supplies it to a load; and a feedback means that inserts a primary side into the output circuit and a secondary side into a control terminal circuit of the switching element to turn on / off the switching element by a positive feedback signal; A starting capacitor that charges a DC current supplied from the DC power supply at the time of starting; a starting circuit that starts one switching element that forms a switching circuit by using the charging voltage of the starting capacitor; The control terminal circuit of the switching element that turns on next to the switching element activated by the circuit increases the impedance of the circuit, and then It is provided with; and impedance control circuit performs control to lower the impedance of the control terminal circuit.

With this structure, when the charging voltage of the starting capacitor rises due to the DC current supplied from the DC power supply when the power is turned on, the starting circuit operates and the switching element of the switching circuit turns on and then turns off. However, at this time, the impedance control circuit increases the impedance of the control terminal circuit of the switching element that is turned on next to the switching element that is activated by the activation circuit. Therefore, when the feedback signal is supplied to the control terminal circuit of the switching element to be turned on next by the feedback means after the switching element turned on by the starting circuit is turned off, the switching element is turned on to this control terminal circuit. A drive voltage sufficiently exceeding the threshold voltage is generated, and this switching element is surely turned on. This ensures that the switching circuit starts up, but after that,
The impedance control circuit lowers the impedance of the control terminal circuit of the switching element that is turned on next to the switching element activated by the activation circuit and lengthens the on-duty of this switching element, so that the switching circuit outputs the output to the output circuit. The high-frequency power reaches the rated power, and the high-frequency power is supplied to the load as rated.

However, once the switching circuit is switched, a feedback signal of large power is supplied to the control terminal circuit of the switching element which is turned on next by the feedback means. Therefore, the threshold voltage for turning on the switching element is supplied to this control terminal circuit. Drive voltage that exceeds
This switching element does not turn on, and the switching of the switching circuit continues. Further, the DC power supply here includes a pulsating current obtained by rectifying a commercial power supply by a rectifier circuit, and the same applies to the following claims.

According to a second aspect of the present invention, a DC power source; a switching circuit having a plurality of switching elements, to which the voltage of the DC power source is applied; a high frequency voltage based on ON / OFF of the switching elements, and discharging. An output circuit for supplying a lamp; a feedback means for inserting a primary side in the output circuit and a secondary side for a control terminal circuit of the switching element to turn on / off the switching element by a positive feedback signal; A starting capacitor for charging a DC current supplied from the device; a starting circuit for starting one switching element that constitutes a switching circuit by using the charging voltage of the starting capacitor; and a starting circuit when the power is turned on. Switching element that turns on next to switching element Control terminal Increase the impedance of the circuit and then It is provided with; and impedance control circuit performs control to lower the impedance of the road.

With this structure, when the charging voltage of the starting capacitor rises due to the DC current supplied from the DC power supply when the power is turned on, the starting circuit operates and the switching element of the switching circuit turns on and then turns off. However, at this time, the impedance control circuit increases the impedance of the control terminal circuit of the switching element that is turned on next to the switching element that is activated by the activation circuit. Therefore, when the feedback signal is supplied to the control terminal circuit of the switching element to be turned on next by the feedback means after the switching element turned on by the starting circuit is turned off, the switching element is turned on to this control terminal circuit. A drive voltage sufficiently exceeding the threshold voltage is generated, and this switching element is surely turned on. This ensures that the switching circuit starts up, but after that,
The impedance control circuit outputs the output from the switching circuit to the output circuit in order to lower the impedance of the control terminal circuit of the switching element that turns on next to the switching element activated by the activation circuit and lengthen the on-duty of this switching element. The high frequency power reaches the rated power, and the discharge lamp is supplied with the high frequency power as rated. However, once the switching circuit switches, a feedback signal of a large power is supplied to the control terminal circuit of the switching element which is turned on next by the feedback means, so that the threshold voltage for turning on the switching element to this control terminal circuit is sufficiently exceeded. Drive voltage is generated,
This switching element does not turn on, and the switching of the switching circuit continues.

According to the third aspect of the present invention, there is provided a power control circuit that changes the impedance of the control terminal circuit of the switching element activated by the activation circuit to change its on-duty.

With this structure, when the impedance of the control terminal circuit of the switching element is changed by the power control circuit to change its on-duty, the high frequency power output from the switching circuit is changed, whereby the rated value is changed. Satisfactory high-frequency power is supplied from the output circuit to the discharge lamp.

According to a fourth aspect of the present invention, the impedance control circuit includes an additional impedance; and a control of the switching element that is turned on next to the switching element activated by the activation circuit after a certain time has passed after the additional impedance is turned on. And a switch circuit connected to the terminal circuit.

With such a configuration, since the switch circuit of the impedance control circuit is turned off immediately after the power is turned on, the additional impedance deviates from the control terminal circuit of the switching element of the switching circuit, and the impedance of the control terminal circuit of this switching element. Is high,
Since this switching element is in a state where it is easy to turn on, switching of the switch circuit is surely activated. When the switching circuit switches and the power of the positive feedback signal by the feedback means becomes strong, the switch circuit is turned on and the additional impedance is connected to the control terminal circuit of the switching element of the switching circuit. The impedance of the circuit becomes low and the on-duty of this switching element becomes long, so that the high-frequency power output from the switching circuit becomes as large as the rated value.

According to the invention of claim 5, the additional impedance is a resistance.

With this configuration, when the switch circuit is turned on and the resistor is connected to the control terminal circuit of the switching element of the switching circuit, the impedance of the control terminal circuit becomes low.

According to a sixth aspect of the invention, the additional impedance is a parallel connection circuit of a resistor and a capacitor.

With this configuration, when the switch circuit is turned on and the parallel connection circuit of the resistor and the capacitor is connected to the control terminal circuit of the switching element of the switching circuit, the impedance of the control terminal circuit becomes low and the capacitor becomes The pulsating current of the DC power source that is loaded on the control terminal circuit is smoothed by the above, the peak of the positive feedback signal from the feedback means supplied to the control terminal circuit of the switching element becomes a flat level, and the drive voltage is below the threshold value. Therefore, even if the impedance of the control terminal circuit is low, the switching of the switching circuit is always maintained.

According to a seventh aspect of the present invention, the additional impedance is a circuit in which a series connection circuit of a second resistor and a capacitor is connected in parallel to the first resistor.

With this configuration, the switch circuit is turned on, and the control terminal circuit of the switching element of the switching circuit is connected to the circuit in which the first resistor and the series connection circuit of the second resistor and the capacitor are connected in parallel. Then, when the impedance of the control terminal circuit of the switching element is increased,
Since the capacitor is gradually charged with electric charge through the second resistor, the peak of the positive feedback signal from the feedback means supplied to the control terminal circuit of the switching element becomes too low while the capacitor is being charged. As a result, the switching element does not fail to be turned on, and even if the impedance of the control terminal circuit is lowered, the switching of the switching circuit always continues.

The invention according to claim 8 comprises the discharge lamp lighting device according to any one of claims 2 to 7; and a lighting device main body incorporating the discharge lamp lighting device.

With such a configuration, the discharge lamp lighting device according to any one of claims 2 to 7 incorporated in the lighting device main body is turned on.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a circuit diagram showing the configuration of the first embodiment of the discharge lamp lighting device of the present invention. 1
Is a commercial power supply for supplying alternating current, 2 is a rectifying circuit including a diode bridge for rectifying alternating current, 3 is a linkage transformer for boosting high frequency voltage, 4 is a discharge lamp such as a fluorescent lamp, and C1 is a charge for starting an inverter. C2, C4 are capacitors forming a resonance circuit, C3 is a charging capacitor for smoothing the rectified current, C7 is a capacitor for smoothing the output voltage of the rectifier circuit 2, and C8 is a voltage for turning on the transistor Q3. , C9 is a capacitor for smoothing the gate voltage of the transistor Q4, CT1 is the primary side of the saturable transformer, and a high-frequency current flows through this primary side, so that the secondary side CT
21 and CT22 generate a high frequency voltage, and when the primary side is saturated, the generation of the secondary side voltage is stopped. D1 is a diode forming a discharging path of the capacitor C1, D2 is a diode forming a path connecting the resistor R12 to the gate circuit of the transistor Q1, a diode connecting a series circuit of the resistor R10, and D4 is an on-voltage at the gate of the transistor Q4. , Q1 and Q2 are switching transistors (field effect transistors) that form an inverter that outputs a high frequency voltage, Q3 is a transistor that switches the output voltage of the rectifier circuit 2 to and from the resistors R14 and R9.
Q4 is a field effect transistor that switches the impedance of the gate circuit of the transistor Q1, R1 is a charging resistor that determines the charging time constant of the capacitor C1, R3 and R4 are gate bias resistors of the transistor Q1, and R5 and R6 are gate biases of the transistor Q2. Resistor, R7 is a resistor that determines the charging time constant of the capacitor C8, R8 is a current limiting resistor that limits the current flowing through the trigger diode TD,
R11 is a resistor that determines the discharge time constant of the capacitor C8,
R12 is a resistor connected to change the impedance of the gate circuit of the transistor 1; R13 is a resistor that determines the bias voltage of the gate circuit of the transistor Q4;
Reference numeral 14 is a current limiting resistor that limits the current flowing through the diode D4, TD is a trigger diode that activates the transistor Q2, and ZD is a zener diode that turns on the transistor Q3.

Here, the transistors Q1 and Q2 form a switching circuit, the linkage transformer 3 forms an output circuit, and the primary side CT1 and the secondary side CT of the saturable transformer are formed.
Although reference numerals 21 and 22 constitute a feedback means, a ballast choke or the like may be used as the feedback means. Furthermore, a starting capacitor, a trigger diode TD, a resistor R
8. The diode D1 constitutes the starting circuit, and the capacitor C
7, C8, C9, transistors Q3, Q4, Zener diode ZD, diode D4, resistors R11, R12,
R13 and R14 form an impedance control circuit. Incidentally, if the discharge lamp 4 is removed, the power supply device is constructed.

Next, the operation of this embodiment will be described. When the power is turned on, the alternating current supplied from the commercial power supply 1 is rectified by the rectifier circuit 2 and charges the capacitor C1 through the resistor R1. Thereby, the capacitor C1
4A rises and the discharge voltage from the capacitor C1 is turned on via the resistors R8 and R5 when the charging voltage rises and exceeds the trigger voltage of the trigger diode TD, as shown in FIG. 4A. Thus, since it is applied to the gate of the transistor Q2 and exceeds the gate voltage VTH, the transistor Q2 is turned on.

As a result, the rectified current of the rectifier circuit 2 flows through the capacitor C3, the primary side of the linkage transformer 3 and the primary side CT1 of the saturable transformer to the transistor Q2 side, and the transistor Q2 has the rectifier current shown in FIG. The first drain current IDQ2 flows as shown in FIG. When the transistor Q2 is turned on, the diode D1 is turned on, the charge of the capacitor C1 is discharged to the transistor Q2 side through the diode D1, the terminal voltage becomes low level, and the gate voltage of the transistor Q2 decreases, The transistor Q2 turns off.

On the other hand, when the power is turned on, the rectified current of the rectifier circuit 2 charges the capacitor C8 through the resistor R7 and raises the terminal voltage of the capacitor C8. This terminal voltage changes the Zener voltage of the Zener diode ZD. Until this is exceeded, the transistor Q3 is off, so the diode D4 is off, the gate voltage of the field effect transistor (hereinafter simply referred to as transistor) Q4 is at low level, and the transistor Q4 is off. Therefore, the resistor 12 is not electrically connected to the gate circuit of the field effect transistor (hereinafter simply referred to as transistor) Q1 during the period when the transistor Q4 is off after the power is turned on, and the impedance of the gate circuit of the transistor Q1 is It's getting higher.

In such a state, when the transistor Q2 is turned off, a current in the opposite direction to the above flows in the primary side CT1 of the saturable transformer, which causes the voltage generated in the secondary side CT21 of the saturable transformer to become an electric field. It is applied to the gate of an effect transistor (hereinafter simply referred to as transistor) Q1. At this time, since the gate voltage of the transistor Q1 has a high impedance in the gate circuit, even if the power of the voltage generated in the secondary side CT21 of the saturable transformer is weak, the gate voltage of FIG.
As shown in (B) -B, the gate voltage VTH is easily exceeded and the transistor Q1 is turned on. This allows
The discharge current of the capacitor C3 and the rectification current of the rectifier circuit 2 flow through the transistor Q1, the primary side CT1 of the saturable transformer, the primary side of the linkage transformer 3, and the capacitor C4, and the transistor Q1 is turned on as shown in FIG. The first drain current as shown flows. Therefore, the voltage generated in the secondary side CT21 of the saturable transformer is continuously applied to the gate of the transistor Q1, and this transistor Q1
1 remains on, but when the saturable transformer saturates,
The voltage generated at the secondary side CT21 disappears and the transistor Q1 turns off.

When the transistor Q1 turns off, a current flows from the capacitor C4 and the primary side of the linkage transformer 3 to the primary side CT1 of the saturable transformer, and after resetting the saturable transformer, the secondary side of the saturable transformer is reset. CT22
Drive voltage as shown in FIG. 4A is applied to the gate of the transistor Q2,
Turn 2 on. When the transistor Q2 is turned on, the rectified current of the rectifier circuit 2 flows to the transistor Q2 side through the capacitor C3, the primary side of the linkage transformer 3 and the primary side CT1 of the saturable transformer, and the transistor Q2 has the transistor of FIG. A drain current IDQ2 shown in C flows. As a result, the voltage generated in the secondary side CT22 of the saturable transformer is applied to the gate of the transistor Q2,
Although this transistor Q2 is kept in the ON state, when the saturable transformer is saturated, the voltage generated in the secondary side CT22 disappears and the transistor Q2 is turned off.

Here, before the transistor Q2 is turned off, the terminal voltage of the capacitor C8 rises,
The Zener diode ZD is turned on by exceeding the Zener voltage of the Zener diode TD. As a result, the transistor Q3 is turned on, the anode side of the diode D4 becomes high level, and the diode D4 is turned on. Therefore, a voltage determined by ZD is applied to the gate of the transistor Q4, the transistor Q4 is turned on, and the transistor Q4 is turned on. A resistor R12 is connected to the gate circuit of Q1 to reduce the impedance of the gate circuit to a normal value.

When the transistor Q2 is turned off as described above, a current in the opposite direction to the above flows in the primary side CT1 of the saturable transformer, which causes the secondary side CT2 of the saturable transformer.
The voltage generated at 1 is applied to the gate of the field effect transistor Q1. At this time, the impedance of the gate circuit of the transistor Q1 is low, but the power of the voltage generated in the secondary side CT21 of the saturable transformer is high, and as shown by D in FIG. 4 (B). , The gate voltage VTH is easily exceeded and the transistor Q2 is turned on. As a result, the discharge current of the capacitor C3 and the rectification current of the rectifier circuit 2 flow through the transistor Q1, the primary side CT1 of the saturable transformer, the primary side of the linkage transformer 3, and the capacitor C4, and the transistor Q1 is supplied to the transistor Q1.
A drain current as shown in (D) D flows.

Thereafter, the transistors Q1 and Q2 start switching at a high frequency, and a high frequency current flows through the primary side of the linkage transformer 3, so that a boosted high frequency voltage is generated on the secondary side thereof, and the high frequency of this high voltage is generated. A voltage is applied to the discharge lamp 4 to light the discharge lamp 4.

In the above description, the timing at which the transistor Q4 is turned on and the impedance of the gate circuit of the transistor Q1 becomes low is just before the transistor Q1 is first turned on and then turned off for convenience of description. This is because, after several tens of cycles after the switching of the transistors Q1 and Q2, the charging voltage of the capacitor 3 becomes stable and the power of the voltage generated from the secondary side CT21 of the saturable transformer becomes sufficiently high.

According to this embodiment, when the power is turned on, the transistor Q4 is off, the resistor R12 is removed from the gate circuit of the transistor Q1, and this gate circuit has a high impedance. After the transistor Q2 is turned on, this transistor is turned off, and even if the power of the voltage generated in the saturable transformer CT21 is weak, this voltage becomes a voltage that sufficiently exceeds the gate voltage VTH of the transistor Q1.
1 can be reliably turned on, and the transistors Q1 and Q2 can be reliably switched. Moreover, after the transistors Q1 and Q2 are switched, the capacitor C3 is
When the charging voltage of is stable, the transistor Q4 is turned on, the resistor R12 is connected to the gate circuit of the transistor Q1, and even if this gate circuit becomes low impedance,
At this time, since the power of the voltage generated in the saturable transformer CT21 is strong, the transistor Q1 can be sufficiently driven and the switching can be continued, so that the on-duty of the transistor Q1 becomes long and the rated high frequency power is discharged. It can be supplied to the lamp 4.

The present invention is not limited to the circuit on the output side of the inverter shown in the above-mentioned embodiment, but has various types such as a discharge lamp lighting device having the circuit configuration of the second embodiment shown in FIG. The same effect can be obtained by applying to the discharge lamp lighting device.

FIG. 6 shows a third embodiment of the discharge lamp lighting device of the present invention.
2 is a circuit diagram showing the configuration of the embodiment of FIG. In this example, the diode D is added to the configuration of the first embodiment shown in FIG.
3, capacitor C6, resistors R9, R10 and variable resistor V
A power adjusting circuit for adjusting the magnitude of the high frequency power output from the transistors Q1 and Q2 formed by R is added. Here, C6 is a capacitor for smoothing the divided voltage obtained from the variable resistor VR, D3 is a diode for connecting the variable resistor VR and the voltage dividing resistor of the resistor R9 to the gate circuit of the transistor Q2, and R9 and R10 are rectifier circuits. 2 is a voltage dividing resistor that divides the output voltage, VR is a variable resistor that divides the output voltage of the rectifier circuit 2, and the rest of the configuration is the same as that of the first embodiment.

When the power is turned on, the resistor R7 is connected to the capacitor C8.
A charging current flows through the capacitor C8, the terminal voltage of the capacitor C8 rises, and when this terminal voltage exceeds the Zener voltage, the transistor Q3 turns on, and the output voltage of the rectifier circuit 2 is applied to the resistors R7 and R9 at the cathode of the diode D3. The voltage divided by the variable resistance VR and the resistance R10 is applied. Therefore, when the voltage on the anode side of the diode D3 becomes higher than this divided voltage, the series circuit of the variable resistor VR and the resistor R10 is connected to the gate circuit of the transistor Q2,
Since the impedance of the gate circuit of the transistor Q2 becomes low, the width of the drive voltage of the transistor Q2 is widened, and its on-duty becomes long, the high-frequency output becomes large and the high-frequency output output from the transistors Q1 and Q2 becomes the rated value. . Further, by adjusting the variable resistance VR, the variable resistance VR connected through the diode D3 is connected.
The magnitude of the high frequency output can be adjusted by changing the resistance value of the series circuit of the resistor R10 and the resistor R10.

The terminal voltage of the capacitor C8 rises,
This terminal voltage exceeds the Zener voltage and transistor Q3
Is turned on, the operation of turning on the transistor Q4 and lowering the impedance of the gate circuit of the transistor Q1 is similar to the operation of the first embodiment, and has the same effect.
The added power control circuit may be of a feedback type that changes the on-duty of the gate circuit of the transistor Q2 according to the output voltage of the rectifier circuit 2.

By the way, in the device shown in FIGS. 3, 5 and 6, after the transistors Q1 and Q2 are switched, the transistor Q4 is turned on at the timing of (a) in FIG. 8A, and the gate circuit of the transistor Q1 is turned on. When the resistor R12 is connected to the gate circuit, a pulsating current, which is the output of the rectifying circuit 2, is placed on the gate circuit, and the drive voltage of the transistor Q1 rises and falls in synchronization with this pulsating current. ) B, after the transistor Q2 is turned off, the drive voltage generated in the secondary side CT21 of the saturable transformer is lower than the gate voltage VTH, the transistor Q1 is not turned on, and the switching is stopped. There was a fear that it would end up. Incidentally, FIG. 7 shows the pulsating current that is loaded in the gate circuit of the transistor Q1, and FIG.
8B is an enlarged view of the portion B in FIG. 8B.

FIG. 9 shows a fourth embodiment of the discharge lamp lighting device of the present invention.
2 is a circuit diagram showing the configuration of the embodiment of FIG. In this example, in order to solve the problem of the third embodiment described above, the capacitor 10 is connected in parallel to the resistor R12 that is connected to and separated from the gate circuit of the transistor Q1. Other configurations are similar to those of the third embodiment shown in FIG. Transistor Q
After switching Q1 and Q2, when the transistor Q3 is turned on and the transistor Q4 is turned on at the timing shown in FIG. 11A, the parallel circuit of the resistor R12 and the capacitor C10 is connected to the gate circuit of the transistor Q1. As a result, the impedance of this gate circuit decreases.

Then, the secondary side CT21 of the saturable transformer
When a voltage for driving the transistor Q1 is generated in the transistor Q1, the pulsating current of the rectifier circuit 2 that is included in the gate circuit of the transistor Q1 is smoothed by the capacitor 12 through the resistor R7, the transistor Q3, the resistor R14, and the transistor Q4. 11B, a drive voltage whose peak portion is always flat is applied to the gate of the transistor Q2, and the gate voltage VTH is constantly exceeded, so that the impedance of the gate circuit of the transistor Q1 is reduced and then the transistor Q1 Turns off and transistor Q1,
It is possible to avoid the problem that the switching of Q2 stops, and it is possible to maintain stable switching even after the above-described decrease in impedance. Other effects are similar to those of the third embodiment shown in FIG.

By the way, in the above-described fourth embodiment, the capacitor C10 is charged by the drive voltage generated in the secondary side CT21 of the saturable transformer immediately after the impedance of the gate circuit of the transistor Q1 is lowered. As a result, the peak portion may be lowered too much and the gate voltage VTH may be barely exceeded, as shown by (b) in FIG. 11B.
There is a risk that the drive voltage does not exceed the gate voltage VTH, the transistor Q1 does not turn on, and switching stops. However, also in this example, when the capacitor C10 is charged, the peak portion of the drive voltage rises as shown by C in FIG.
There is no fear of turning off. Note that FIG. 10A shows the drive voltage of the gate circuit of the transistor Q1, and it can be seen that the pulsating current is smoothed due to the presence of the capacitor C10. An enlarged view of the portion B in FIG. 10B is shown in FIG.
It is a part of (B).

FIG. 12 is a circuit diagram showing the configuration of the fifth embodiment of the discharge lamp lighting device of the present invention. In this example, in order to solve the problem of the above-described fourth embodiment, the resistor R12 connected to and separated from the gate circuit of the transistor Q1,
A series circuit of the capacitor 10 and the resistor R15 is connected in parallel. The other structure is the same as that of the fourth embodiment shown in FIG. After the transistors Q1 and Q2 are switched, the transistor Q4 is turned on and the transistor Q4
Immediately after the resistor R12, the capacitor 10, and the resistor R15 are connected to the gate circuit of No. 1 to reduce the impedance of the gate circuit of the transistor Q1, the saturable transformer 2
The drive voltage generated in the secondary CT21 gradually charges the capacitor C10 through the resistor R12.

Therefore, in this example, the peak of the drive voltage applied to the gate of the transistor Q1 does not decrease so much during the charging period of the capacitor C10.
The peak of the drive voltage does not fall below the gate voltage VTH, and during the charging period of the capacitor C10,
The transistor Q1 does not turn on and the transistors Q1 and Q2
It is possible to avoid the possibility that the switching of the transistor Q1 will stop, and the switching of the transistors Q1 and Q2 can be maintained most stably even after the impedance of the gate circuit of the transistor Q1 is lowered. Other effects are similar to those of the fourth embodiment shown in FIG.

FIG. 13 is a perspective view showing the configuration of an embodiment of the lighting device of the present invention. Reference numeral 111 denotes a lighting device main body, and a fluorescent lamp 112 which is a kind of a discharge lamp is mounted on the lighting device main body 111. The fluorescent lamp 112 is turned on by the discharge lamp lighting device shown in FIGS. 3, 5, 6, 9, and 12, and the discharge lamp lighting device is built in the lighting device main body 111. In this example, since the starting performance of the inverter of the built-in discharge lamp lighting device is improved, the fluorescent lamp 112 can be lit stably and reliably.

[0052]

As described above, the first, second, fourth, and fifth aspects are provided.
According to the invention, immediately after the power is turned on, when the switching circuit is activated, the impedance of the control terminal circuit of the switching element that is turned on next to the activation target switching element is increased, and then the impedance of this control terminal circuit is set to a normal low state. By doing so, even if the impedance of the control terminal circuit of the switching element is usually low, the switching element can be reliably activated.

According to the invention of claim 3, the on-duty of the switching element of the switching circuit is changed,
The magnitude of the high frequency power output from this switching circuit can be changed and adjusted.

According to the sixth aspect of the present invention, when the impedance of the control terminal circuit of the switching element of the switching circuit is lowered, the pulsating current carried on the control terminal circuit is smoothed by the capacitor so that the drive voltage is below the threshold value. Since it is possible to eliminate the possibility that the switching circuit is switched on, the switching of the switching circuit can be reliably maintained even after the impedance is lowered.

According to the invention of claim 7, when the impedance of the control terminal circuit of the switching element of the switching circuit is lowered, the charging current gradually flows from the control terminal circuit through the second resistor to the capacitor. Since it is possible to prevent the drive voltage of the control terminal circuit from becoming too low and falling below the threshold value before the capacitor is charged, it is possible to ensure that switching of the switching circuit is continued even after the impedance is lowered. it can.

According to the eighth aspect of the present invention, since the startability of the discharge lamp lighting device mounted on the lighting device is improved,
The discharge lamp can be reliably turned on.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration example of a conventional discharge lamp lighting device.

FIG. 2 is a waveform chart explaining the operation of the circuit shown in FIG.

FIG. 3 is a circuit diagram showing a configuration of a first embodiment of a discharge lamp lighting device of the present invention.

FIG. 4 is a waveform diagram illustrating an operation of the switching transistor illustrated in FIG. 3 at the time of startup.

FIG. 5 is a circuit diagram showing a configuration of a second embodiment of a discharge lamp lighting device of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a third embodiment of a discharge lamp lighting device of the present invention.

FIG. 7 is a waveform diagram showing a pulsating flow on the gate circuit of the switching transistor shown in FIG.

8 is a waveform chart explaining the operation of the switching transistor shown in FIG.

FIG. 9 is a circuit diagram showing a configuration of a fourth embodiment of a discharge lamp lighting device of the present invention.

10 is a waveform diagram showing the drive voltage of the gate circuit of the switching transistor shown in FIG.

11 is a waveform chart explaining the operation of the switching transistor shown in FIG.

FIG. 12 is a circuit diagram showing a configuration of a fifth embodiment of a discharge lamp lighting device of the present invention.

FIG. 13 is a perspective view showing a configuration of an embodiment of a lighting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial power supply 2 ... Rectifier circuit 3 ... Linkage transformer 4 ... Discharge lamp C1-C10 ... Capacitor CT1 ... Primary side of saturable transformer CT21, CT22 ... Secondary side of saturable transformer D1-D4 ... Diodes Q1, Q2, Q4 ... Switching transistor Q3 ... Discharging transistor R1 to R15 ... Resistor TD ... Trigger diode VR ... Variable resistance ZD ... Zener diode

Claims (8)

[Claims] 1. A DC power supply; a switching circuit having a plurality of switching elements, to which the voltage of the DC power supply is applied; an output circuit for outputting a high frequency voltage based on ON / OFF of the switching elements and supplying it to a load. And; feedback means in which the primary side is inserted in the output circuit and the secondary side is inserted in the control terminal circuit of the switching element to turn on / off the switching element; and a start-up for charging the DC current supplied from the DC power supply at the time of start-up. And a starting circuit for starting one switching element that constitutes a switching circuit by using the charging voltage of the starting capacitor; and a switching element that is turned on next to the switching element started by the starting circuit when the power is turned on. The control of increasing the impedance of the control terminal circuit and then lowering the impedance of this control terminal circuit is performed. A power supply device comprising: an impedance control circuit; 2. A DC power supply; a switching circuit having a plurality of switching elements, to which a voltage of the DC power supply is applied; an output for outputting a high-frequency voltage based on ON / OFF of the switching elements to supply a discharge lamp. A circuit; a feedback means in which a primary side is inserted in an output circuit and a secondary side is inserted in a control terminal circuit of a switching element to turn on / off a switching element; and a direct current supplied from the direct current power source is charged at startup. A starting capacitor; and a switching circuit is constructed using the charging voltage of the starting capacitor 1
A starter circuit for starting each switching element; when the power is turned on, the impedance of the control terminal circuit of the switching element which is turned on next to the switching element started by the starter circuit is increased, and then the impedance of this control terminal circuit is decreased. A discharge lamp lighting device, comprising: an impedance control circuit for controlling. 3. The discharge lamp lighting device according to claim 2, further comprising a power control circuit that changes the impedance of the control terminal circuit of the switching element activated by the activation circuit to change the on-duty thereof. 4. The impedance control circuit is connected to an additional impedance; and the additional impedance is connected to a control terminal circuit of the switching element which is turned on next to the switching element activated by the activation circuit, after some time has passed after the power is turned on. The discharge lamp lighting device according to claim 2 or 3, further comprising a switch circuit. 5. The discharge lamp lighting device according to claim 4, wherein the additional impedance is a resistance. 6. The discharge lamp lighting device according to claim 4, wherein the additional impedance is a parallel connection circuit of a resistor and a capacitor. 7. The additional impedance is the second resistance of the first resistance.
5. The discharge lamp lighting device according to claim 4, which is a circuit in which a series connection circuit of the resistor and the capacitor is connected in parallel. 8. A lighting device comprising: the discharge lamp lighting device according to claim 2; and a lighting device body incorporating the discharge lamp lighting device.