JP2002334798A - Inverter lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preheate a self-excited inverter lighting device with a simple circuit. SOLUTION: A diode series circuit 12 and a capacitor series circuit 13 are connected in parallel with each other in a power circuit of this self-excited inverter lighting device 11, and a diode D5 is connected between the connection point of the capacitors C1 and C2 of the series circuit 13 and that on the anode terminal A side of the series circuit 12 by disposing its cathode on the connection point side of the capacitors C1 and C2. The lighting device employs a structure where the connection point of the capacitors C1 and C2 is connected to one side of an AC power source, and the other side of the AC power source is connected to the connection point of diodes D4 and D6 through a switch means 14 for carrying a current only toward the connection point of the diodes D4 and D6 after turning on the power and for carrying the current in both directions after a predetermined period elapses. Thus, an AC amplitude voltage for preheating is outputted after turning on the power, and a lighting double voltage is outputted after the predetermined period elapses, so that the preheating can be performed with the simple circuit structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter lighting device capable of performing preheating with a simple circuit configuration.

[0002]

2. Description of the Related Art As an inverter lighting device, there is a self-excited inverter lighting device.

In a self-excited inverter device, a circuit including a discharge tube itself is turned on as an oscillating circuit. For example, as shown in FIG.
1, a transistor series circuit 1 in which T2 is push-pull connected, and a diode series circuit 2 in which anode terminals and cathode terminals of two diodes D1 and D2 are connected in parallel. Connection point of two NPN transistors T1 and T2 (emitter and collector)
And an inductor L, a discharge tube (fluorescent lamp) 6, and a connecting point between the anode terminal and the cathode terminal of the diodes D1 and D2.
A series circuit including the base windings N1 and N2 is connected, and a capacitor 5 'is connected to the remaining heater terminal of the discharge tube (fluorescent lamp) 6.

At this time, the base windings N1, N2
Are provided so as to be in opposite phases to each other and the transistor T
1 and T2, when a leakage current flows to either of the transistors T1 and T2 when the power is turned on,
The magnetic flux of the base windings N1 and N2 changes, and the transistor T
1, a voltage for turning on T2 is induced.

Therefore, when the transistor T1 is turned on by the induced voltage, for example, the base current of the transistor T2 is turned off in the opposite phase, and the current of the transistor T1 increases. When the current of the transistor T1 increases, the magnetic flux of the inductor L saturates, and the voltage induced in the base winding N1 becomes zero. As a result, the transistor T
When 1 is turned off, the energy stored in the inductor L becomes back electromotive force, appears in the base winding N2, and turns on the transistor T2.

As described above, when the transistor T2 is turned on, the base current has the opposite phase, so that the transistor T1 is turned off, and the current of the transistor T2 increases. When the magnetic flux of the inductor L is saturated by this increase, the voltage induced in the base winding N1 becomes 0, and the transistor T2 is turned off.

Thus, the transistors T1 and T2
Are turned on and off repeatedly to oscillate. From such a mechanism, the oscillation frequency is determined by the applied voltage.

Therefore, the self-excited inverter circuit 10
By applying a device to the power supply circuit section for applying a voltage to the fluorescent lamp 6, the preheating circuit can be easily formed, and the blackening of the fluorescent lamp 6 can be prevented.

For example, as shown in FIG.
23791), a boost converter IC circuit co between the rectifier circuit B and the self-excited inverter circuit 10.
n, the operation of the step-up converter IC circuit con is delayed by the timer circuit p when the power is turned on, and a rectified voltage is directly applied to the self-excited inverter circuit 10 during the operation. The circuit I is preheated and oscillated.

In this way, the fluorescent lamp 6 is preheated by shifting from the DC lighting to the AC lighting over several seconds.

[0011]

However, in the case of using the above-mentioned boost converter IC circuit, a stable lighting circuit can be constructed relatively easily because the IC circuit is used, but the cost is lower and the cost is lower. In order to make failure less likely to occur, use general parts instead of using special parts such as a boost converter circuit.
The challenge is to enable preheating with a simple circuit.

An object of the present invention is to make it possible to preheat a self-excited inverter device with a simple circuit configuration.

[0013]

In order to solve the above-mentioned problems, according to the present invention, a transistor series circuit in which two transistors are push-pull connected, and a diode series circuit in which an anode terminal and a cathode terminal of two diodes are connected. Circuit, and an inductor, a fluorescent lamp, and a base winding of the transistor are connected in series between a connection point between transistors of the parallel circuit and a connection point between an anode terminal and a cathode terminal of a diode. A self-excited inverter circuit for lighting a discharge tube by self-oscillation based on a voltage applied between both ends of the circuit, a diode series circuit connecting anode and cathode terminals of two diodes, and two capacitors Are connected in parallel to a capacitor series circuit, and both ends of the parallel circuit are connected to the self-excited inverter. And a diode connected in parallel with the cathode terminal connected between the capacitors in the capacitor series circuit and the anode end of the diode series circuit with the cathode terminal connected between the capacitors. A connection point between capacitors of the circuit is connected to one of the AC power supplies, and a connection point between an anode terminal and a cathode terminal of the diode series circuit and the other of the AC power supplies are connected from the AC power supply to the anode for a predetermined period after power-on. The power supply circuit unit is connected to the power supply circuit unit through a switch that allows a current to flow only in the direction of the connection point between the terminal and the cathode terminal and allows the current to flow in both directions after a predetermined period of time.

By adopting such a configuration, when an AC half-wave is inputted to a connection point connecting the anode terminal and the cathode terminal of the diode series circuit via the switch means at the time of power supply, one side of the diode series circuit is turned on. , The self-excited inverter circuit section, the current flows to the AC power supply via a diode connected in parallel with the capacitor, and one of the two capacitors of the capacitor series circuit connected to the connection point is charged. Therefore, a voltage corresponding to the AC amplitude is applied to the self-excited inverter circuit unit.

On the other hand, when the switch means inputs both AC waves after a predetermined period, the half-wave of the opposite polarity has the opposite polarity to the previous half-wave, so the other capacitor → the diode of the diode series circuit → It flows with the AC power supply and charges the other capacitor in the capacitor series circuit.

For this reason, a voltage that is twice the AC amplitude is applied to the self-excited inverter circuit section by the charged capacitor.

As described above, the voltage applied to the self-excited inverter circuit section can be doubled by the switch means, so that the oscillation frequency of the self-excited inverter circuit section is changed to perform preheating oscillation at the same voltage, and The lighting may be performed at the double voltage.

At this time, instead of connecting to the AC power supply of the power supply circuit section, a connection point between the anode terminal and the cathode terminal of the diode series circuit is connected to the other of the AC power supplies,
A switch that allows a current to flow only in the direction of the AC power supply from the connection point of the capacitors to the connection point between the capacitors of the capacitor series circuit and one of the AC power sources for a predetermined period after power-on, and to flow the current in both directions after the predetermined period has elapsed. A configuration connected via means can be adopted.

By adopting such a configuration, an AC half-wave flows through one diode of the diode series circuit → the self-excited inverter circuit section → the diode connected in parallel with the capacitor when the power is turned on. One of the series circuits is charged, and a voltage corresponding to the AC amplitude is applied to the self-excited inverter circuit unit.

Then, when both waves are input after a lapse of a predetermined period, a half-wave of the opposite polarity flows from the other capacitor → the diode of the diode series circuit → the AC power supply to charge the other capacitor of the capacitor series circuit. A double voltage can be supplied to the inverter circuit section by the charged capacitor.

At this time, a second inductor is provided between the switch means of the power supply circuit section and a connection point between the anode terminal and the cathode terminal of the diode series circuit, and the connection point to which the second inductor is connected is provided. And the connection point between the anode terminal and the cathode terminal of the diode of the parallel circuit of the self-excited inverter circuit and the connection point of the anode terminal and the cathode terminal of the diode series circuit. Is excited by an AC power supply, and when the polarity of the AC power supply is switched, the retained energy is supplied to the inverter circuit via a capacitor to reduce the power factor of the power supply. Can be improved.

Further, at this time, if the switch means is constituted by a power MOSFET and a timer circuit which operates the power MOSFET after a predetermined period has elapsed after the power is turned on, the timer circuit turns off the power MOSFET at the time of lighting, and the built-in timer circuit turns off the power MOSFET. Flywheel diodes pass half-waves of AC. Also, if the timer circuit turns on the power MOSFET after preheating, both waves can be passed.

At this time, the switching means is turned on after a lapse of a predetermined period of time after the power is turned on, and a switch section in which the anode terminal of the thyristor and the cathode terminal of the diode are connected in parallel and the thyristor of the switch section is turned on. If the thyristor is turned off by the timer circuit at the time of lighting, the diode connected in parallel with the thyristor conducts and can pass an AC half-wave. Also, after preheating, if the timer circuit turns on the thyristor, both waves can pass through the thyristor that has been fired by the diode.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the inverter lighting device of this embodiment includes a self-excited inverter circuit section 10 and a power supply circuit section 11.

The self-excited inverter circuit section 10 is the same as that described in the above-described conventional example, and includes a connection point between the emitter and the collector of the push-pull connected NPN transistors T1 and T2, and an anode terminal A of the diode series circuit 2. A series circuit consisting of an inductor L, a fluorescent lamp 6, and base windings N1 and N2 is connected between a connection point of
The configuration is such that a capacitor 5 ′ is connected to the remaining heater terminal of the fluorescent lamp 6.

The base windings N1 and N2 are provided so as to have opposite phases to each other and are connected to the bases of the transistors T1 and T2. If a leakage current flows to one of the transistors T1 or T2 when the power is turned on. , Base winding N
1 and N2 change, and the remaining transistors T1 and T2
2 is turned on.

The power supply circuit section 11 includes two diodes D
4, a diode series circuit 12 composed of D6, a capacitor series circuit 13 composed of two capacitors C1 and C2, a diode D5 and switch means 14.

The diode series circuit 12 connects the anode terminal A and the cathode terminal K of two diodes D4 and D6. Also, the capacitor series circuit 13
One end of each of two capacitors C1 and C2 is connected.

The two series circuits 12 and 13 are connected in parallel, and both ends of the parallel circuit are connected to the self-excited inverter circuit section 10 to output power to the inverter circuit section 10.

Further, a diode D5 having a cathode connected to a connection point between the capacitors is connected between a connection point between the capacitors of the capacitor series circuit 13 and an anode terminal at both ends of the diode series circuit 12.

Incidentally, in this embodiment, the diode series circuits D3 and D6 and the diode D5 are configured by using the ready-made diode bridge elements D3 to D6.
The diode D3 is not required separately in the circuit.

The connection point between the capacitors C1 and C2 of the capacitor series circuit 13 of this parallel circuit is connected to one of the AC inputs (in this embodiment, via a filter circuit), and the other of the AC inputs is connected to the switch means 14. Anode terminal A and cathode terminal K of the diode series circuit 12
Is connected to the connection point.

In this case, the switch means 14 is N
a power MOSFET 18 and a timer circuit 19, as shown in FIG.
The drain 18 is connected to the connection point between the anode terminal A and the cathode terminal K of the diode series circuit 12, and the source s is connected to an AC input.

The power MOSFET 18 has a built-in (protection) diode D7 between the source s and the drain d as shown in FIG. 1, and the built-in diode D7 is connected in parallel with the MOSFET 18 with the anode A side as the source s side. It is connected. Therefore, a current can flow from the cathode side to the drain side regardless of whether the MOSFET 18 is on or off.

The gate q of the power MOSFET 18
Is connected to a timer circuit 19.

The timer circuit 19 uses a timer capacitor C3. As shown in FIG. 1, a diode D8 and voltage dividing resistors R1 and R2 are provided between AC input terminals, and a connection point of the voltage dividing resistors R1 and R2 is provided. , A timer capacitor C3 is connected in parallel and connected to the gate q of the power MOSFET 18.

Reference numeral 20 denotes a filter circuit.

This embodiment is configured as described above. In this lighting device, when the power is turned on, the timer circuit 1
The timer capacitor C3 of No. 9 is not charged, and the voltage of the capacitor C3 is “0”. Therefore, the gate q voltage of the power MOSFET 18 connected to the capacitor C3 is also “0”, and the power MOSFET 18 is off. As a result, as shown by the arrow (solid line) in FIG. 2A, the negative half-wave of AC flows through the built-in diode D7 → diode D4 → capacitor C1 → AC power supply, and charges the capacitor C1 with the polarity of FIG. I do. Therefore, the capacitor C
The voltage of 1 becomes an AC amplitude voltage, and a current flows from the capacitor C1 to the capacitor C1, the inverter circuit section 10, the diode D5, and the capacitor C1, and the supply voltage to the inverter circuit section 10 also becomes the AC amplitude voltage.

At this time, the inverter circuit 10 to which the amplitude voltage is applied starts oscillating, but the oscillation frequency at this time is lower than the lighting voltage because the applied voltage is an AC amplitude voltage, and the fluorescent lamp 6 does not discharge. That is, the heater of the fluorescent lamp 6 is heated.

After that, when the timer capacitor C3 of the timer circuit 19 is charged by the voltage dividing resistors R1 and R2 and the voltage rises, and the increased voltage exceeds the threshold voltage of the power MOSFET 18, the power MOSFET 18 is turned on. As shown in (1), a positive half-wave (dashed arrow) flows through the circuit.

As shown in FIG. 2 (a), this positive half-wave flows from the AC power source → the capacitor C2 → the diode D6 → the power MOSFET 18 → the AC power source, and the capacitor C2
Is charged with the polarity shown in FIG. Therefore, a current flows from the charged capacitor C2 to the capacitor C2 → the capacitor C1 → the inverter circuit unit 10 → the capacitor C2, and the voltage applied to the inverter circuit unit 10 is determined by the capacitors C1 and C2.
2 plus a voltage that is twice the AC amplitude.

As a result, as shown in FIG. 2B, when the fluorescent lamp 6 of the inverter circuit 10 reaches the discharge voltage due to the increased voltage, it starts discharging and lights up, and the oscillation frequency also decreases.

As described above, in this lighting circuit, preheating can be performed with a simple circuit configuration without using a booster converter IC circuit or the like, so that cost can be easily reduced.

At this time, the preheating time t1 can be easily set by changing the time constants of the voltage dividing resistors R1 and R2 of the timer circuit 19 and the timer capacitor C3. In particular, when the MOSFET 18 is used as the switching means, almost no current flows through the gate q, so that the preheating time can be accurately determined and the setting thereof can be easily performed.

FIG. 3 shows a second embodiment in which the power factor of the first embodiment is improved.

That is, in this embodiment, as shown in FIG. 3, the second inductor L is connected between the switch means 14 of the power supply circuit section 11 and the connection point between the anode terminal A and the cathode terminal K of the diode series circuit 12. 'Is provided.

A charge / discharge capacitor C4 is connected between the connection point to which the second inductor L 'is connected and the connection point between the anode terminal and the cathode terminal of the diode series circuit 2 of the self-excited inverter circuit section 10. .

Thus, for example, when the transistor T2 is turned on, the AC power supply → the second inductor L ′ → the charging / discharging capacitor C4 → the fluorescent lamp 6 → the inductor L → the base windings N1, N2 → the transistor A current flows through a path of T2 → diode D5 → AC power supply, and the capacitor C4 is charged and the second inductor L ′
Is excited.

Therefore, when the transistor T2 is turned off, an induced current is generated in the excited second inductor L ', and the second inductor L' → the diode D4 → the capacitor as shown by the arrow (solid line) in FIG. A current flows through a path of C1 → AC power supply → second inductor L ′.

Similarly, when the transistor T1 is ON, the AC power supply → the diode D3 → the transistor T1 → the base windings N1, N2 → the inductor L → the fluorescent lamp 6 → the charge / discharge capacitor C4 → the second inductor L ′ → the AC A current flows through the path of the power supply, charging the capacitor C4 and exciting the second inductor L '.

Therefore, when the transistor T1 is turned off, an induced current is generated in the excited second inductor L 'as shown by an arrow (broken line) in FIG. 3, and the second inductor L' → AC power supply → capacitor. A current flows through a path of C2 → diode D6 → second inductor L ′.

As described above, by providing the second inductor L ', a current always flows through the capacitors C1 and C2, and the input power factor can be increased.

The capacitors C5 and C6 are protection capacitors, and the capacitor C6 and the inductor Lf are provided to prevent the current having the oscillation frequency from flowing out to the power supply.

FIG. 4 shows a third embodiment in which a thyristor 2 is used instead of the power MOSFET 18 of the switch means 14.
The case using 0 is shown.

That is, in this embodiment, the thyristor 20
By connecting the cathode terminal K of the diode D9 to the anode terminal A of the thyristor 20 and connecting the diode D9 to the thyristor 20 in parallel, a current can flow from the cathode K side of the thyristor 20 to the anode A side regardless of whether the thyristor is on or off. It has become.

A trigger circuit using a Zener diode 21 is provided at the gate q of the thyristor. The trigger circuit turns on the thyristor 20 when the voltage of the timer capacitor C3 exceeds the Zener voltage Vz. Has become.

The other configuration and operation are the same as those of the second embodiment, and the description is omitted.

With this configuration, the switch means 14 can be constituted by the thyristor 20 having a low cost.
The cost of the inverter lighting device can also be reduced.

FIG. 5 shows a fourth embodiment.

This embodiment shows another embodiment of the power supply circuit section 11, and as shown in FIG. 5, the direction of the diode D7 of the switch means 14 is opposite to that of the first to third embodiments. Things.

Therefore, the switch means 14 is provided between the connection point between the capacitors of the capacitor series circuit 13 and the AC power supply.

In the power supply circuit section 11 configured as described above, a positive half-wave is supplied from the AC power supply to the diode D when the power is turned on.
4 → capacitor C1 → diode D7 → AC power supply (solid line arrow) to charge capacitor C1.

Therefore, the charged voltage of the capacitor C1 becomes an AC amplitude voltage, and the voltage of the capacitor C1 is changed from the capacitor C1 to the inverter circuit section 10 to the diode D5.
→ The current flows through the capacitor C1 and the inverter circuit 10
The supply voltage to the inverter also becomes an AC amplitude voltage.

When the switch means is operated and a current flows in both directions in the circuit, a negative half-wave flows through the AC power supply → the switch means 14 → the capacitor C2 → the diode D5 → the AC power supply (broken arrow). The capacitor C2 is charged, and the voltage applied to the inverter circuit unit 10 is doubled.

As described above, the preheating voltage and the lighting voltage can be supplied as in the first embodiment.

In the embodiment, the switch means is provided with the MO.
Although one using a one-way switch element and a diode such as an SFET or a thyristor is shown, the present invention is not limited to this, and it is apparent that a two-way switch element such as a triac may be used.

[0068]

According to the present invention, the self-excited inverter device can be preheated with a simple circuit configuration. Therefore, it is possible to lower the cost and to make the failure less likely to occur.

[Brief description of the drawings]

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

FIGS. 2A and 2B are explanatory diagrams of the operation of the first embodiment.

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

FIG. 4 is a circuit diagram of a third embodiment.

FIG. 5 is a circuit diagram of a fourth embodiment.

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

[Explanation of symbols]

 Reference Signs List 6 fluorescent lamp 10 self-excited inverter circuit section 11 power supply circuit section 12 diode series circuit 13 capacitor series circuit 14 switch means 18 power MOSFET 19 timer circuit 20 thyristor A anode C1 capacitor C2 capacitor C3 timer capacitor C4 charge / discharge capacitor K cathode L inductor L '1st inductor N1 base winding N2 base winding T1 transistor T2 transistor D1-D9 diode

Claims (5)

[Claims] 1. A transistor series circuit in which two transistors are push-pull connected, and a diode series circuit in which anode terminals and cathode terminals of two diodes are connected in parallel, and the transistors in the parallel circuit are connected to each other. An inductor, a fluorescent lamp, and a base winding of the transistor are connected in series between a point and a connection point between an anode terminal and a cathode terminal of the diode, and self-oscillation is performed based on a voltage applied between both ends of the parallel circuit. A self-excited inverter circuit for lighting the discharge tube, a diode series circuit connecting the anode and cathode terminals of two diodes, and a capacitor series circuit connecting two capacitors in series are connected in parallel. Both ends of the parallel circuit are used as the power output to the self-excited inverter circuit, while the output of the capacitor series circuit is Connect the diode in parallel between the connection point between the capacitors and the anode end of the diode series circuit with the cathode terminal on the connection point side between the capacitors, and connect the connection point between the capacitors in the capacitor series circuit to one of the AC power supplies. Then, the connection point between the anode terminal and the cathode terminal of the diode series circuit and the other of the AC power supply, a current flows only from the AC power supply to the connection point of the anode terminal and the cathode terminal for a predetermined period after power-on, An inverter lighting device comprising: a power supply circuit connected via a switch for flowing current in both directions after a predetermined period has elapsed. 2. A connection between a connection point of an anode terminal and a cathode terminal of the diode series circuit and the other of the AC power supply in place of connection with the AC power supply of the power supply circuit section, and connection of capacitors of the capacitor series circuit. The point and one of the AC power supplies are connected via a switch means for flowing a current only in the direction of the AC power supply from the connection point of the capacitors for a predetermined period after the power is turned on, and flowing the current in both directions after a predetermined period. 2. The inverter lighting device according to 1. 3. A switching means of the power supply circuit section, and a second inductor is provided between a connection point of an anode terminal and a cathode terminal of a diode series circuit, and the connection point to which the second inductor is connected is self-excited. 3. The inverter lighting device according to claim 1, wherein a connection point between the anode terminal and the cathode terminal of the diode in the parallel circuit of the inverter circuit is connected via a capacitor. 4. The power MOSFET according to claim 1, wherein
The inverter lighting device according to any one of claims 1 to 3, further comprising a timer circuit that operates the power MOSFET after a lapse of a predetermined period after power-on. 5. A switch unit in which the switch means is connected in parallel by connecting an anode terminal of a thyristor and a cathode terminal of a diode, and a timer for turning on the thyristor of the switch unit after a predetermined period has elapsed after power-on. The inverter lighting device according to any one of claims 1 to 4, comprising a circuit.