JP2001015282A - Discharge lamp lighting device and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a drive circuit of a half bridge type inverter simple, small, and inexpensive by on-controlling first and second switching means of first and second gate drive circuits with resonance voltage of an LC resonance circuit based on feedback voltage from a load circuit and induction voltage of a secondary winding magnetically integrated to reverse polarity of an inductor. SOLUTION: An LC resonance circuit RC is resonated with high polarity voltage induced in a feedback means (s) of a first gate drive circuit GDC 1 magnetically combined with this current with current of a current limiting inductor L2 of a load circuit LC. Raised terminal voltage of an inductor L3 is applied to a gate and a first switching means Q1 is turned on. Polarity of induced voltage of a secondary winding W2 of a second gate drive circuit GDC2 is reversed, a second switching means Q2 is turned off, and then turned on by reverse of the polarity of the resonance voltage, and AC current flows to the load circuit LC by this reverse. A transformer different from the LC resonance circuit RC is made unnecessary, and the number of expensive winding components is reduced.

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 provided with a half-bridge inverter and a lighting device using the same.

[0002]

2. Description of the Related Art In a discharge lamp lighting device having a half-bridge inverter, first and second switching means of the half-bridge inverter are based on a feedback voltage generated in a winding magnetically coupled to a current-limiting inductor of a load circuit. Japanese Patent Application Laid-Open No. Hei 9-190891 discloses a configuration in which a gate drive voltage for alternately turning on and off is obtained.

That is, FIG. 1 of the related art shows a load circuit having at least one inductance L2 and at least one capacitor C7, C8, C9,
A lamp lighting circuit device comprising an inverter, which can be formed as a half-bridge device having two switching elements T1, T2, and a driving circuit AS for driving the switching elements, wherein the driving circuit AS comprises: 2 provided for each switching element T1, T2
Circuit part AS1, including two circuit parts AS1, AS2
Has an auxiliary winding HW1 and parallel oscillation circuits L3 and C3, and the circuit part AS2 has an auxiliary winding HW2 and parallel oscillation circuits L4 and C4, and each auxiliary winding HW
1 discloses a circuit configuration in which HW2 is magnetically coupled to an inductance L2 of a load circuit. (Prior Art 1) FIG. 3 of the above document shows at least one inductance L2 and at least one capacitor C7, C7.
8, a lighting circuit device for a lamp comprising a load circuit having C9, an inverter which can be formed as a half-bridge device having two switching elements T1, T2, and a driving circuit AS for driving the switching elements. The drive circuit AS includes an auxiliary winding HW1 magnetically coupled to the inductance L2 of the load circuit, a parallel oscillation circuit L3, C3 that resonates with a feedback voltage induced in the auxiliary winding HW1 to form a drive signal, and a drive circuit. A circuit configuration including a transformer TR for inverting and supplying a signal to the other switching element T2 is described. (Prior art 2) Further, Japanese Patent Laid-Open No. 10-162983, a half-bridge with a resonant load circuit 16 including a resonant inductor _{L R} and a resonant capacitance _{C R,} the two switches Q1, Q2 of complementary Gate drive circuit 30 of the inverter
A driving inductor L _D interconnected with the resonance inductor L _R of the resonance load circuit 16, a second inductor 32 connected in series with the driving inductor L _D , and a complementary switch Q 1,
The bidirectional voltage clamp 36 for clamping and limiting the gate voltage of Q2 includes a circuit configuration that allows a single gate drive circuit 30 to act commonly on the complementary switches Q1 and Q2. ing. (Prior art 3)

However, the prior art 1
Is a circuit part A of the drive circuit AS for each switching element.
Since S1 and AS2 are provided, the number of circuit components increases.
In particular, the number of relatively large and expensive winding parts increases, which is disadvantageous for downsizing and cost reduction of a discharge lamp lighting device and a lighting device incorporating the same.

In addition, since the resonance frequencies of the circuit parts AS1 and AS2 need to be matched to some extent, it is disadvantageous in terms of parts management and cost.

Next, in prior art 2, in order to invert the vibration of one parallel vibration circuit L3, C3, a parallel vibration circuit L3 is used.
3. Since the transformer TR is used separately from C3, the number of relatively large and high-cost winding components increases, so that the discharge lamp lighting device and the lighting device are reduced in size and cost as in the prior art 1. It is disadvantageous for conversion.

Further, in the prior art 3, since the gate drive circuit can be made single by using the complementary switch, the circuit configuration is simplified.
OSFETs have a problem that they are more expensive than N-channel MOSFETs, have a small product lineup, and are difficult to obtain an element having a desired rating.

In the case where the discharge lamp lighting device is incorporated into a lighting device whose size and cost are being drastically reduced, such as a bulb-type fluorescent lamp, if the number of circuit parts can be reduced as much as possible, the lighting device is required. The contribution to miniaturization and cost reduction is extremely large.

An object of the present invention is to provide a discharge lamp lighting device and a lighting device in which the gate drive circuit of a half-bridge type inverter is simplified to reduce the number of circuit components, especially the number of winding components, thereby achieving downsizing and cost reduction. With the goal.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device, comprising: a DC power supply; first and second switching means connected in series between the DC power supplies; A load circuit that includes an inductor, and a parallel circuit of a discharge lamp and a resonant capacitor in series and is operated by an alternating current generated by alternate switching of the first and second switching means; and feedback means magnetically coupled to the current-limiting inductor, feedback A first gate drive circuit that includes an LC resonance circuit that resonates with a feedback voltage generated in the means, and that turns on the first switching means based on a resonance voltage of the LC resonance circuit; and an LC resonance of the first gate drive circuit. A second winding magnetically coupled to the inductor of the circuit in a reverse polarity relationship and based on a voltage induced in the secondary winding; A second gate drive circuit for turning on the means.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

<Regarding DC Power Supply> The DC power supply may be any of a rectified DC power supply obtained by rectifying AC and a battery power supply. In the case of a rectified DC power supply, it is desirable to have a smoothing means. As the smoothing means, a configuration in which a smoothing capacitor is connected between the DC output terminals of the rectifier circuit, or an active filter that operates using first and second switching means described later, for example, a partial smoothing circuit may be used.

<First and Second Switching Means> The first and second switching means use switching means having the same polarity, but use MOSFETs or other semiconductor switches. MO as switching means
The use of SFETs is advantageous because N-channel MOSFETs currently have a rich product lineup. However, a P-channel MOSFET can be used if desired.

[0013] Connecting the first and second switching means in series between the DC power supplies means that the first and second switching means are connected in series with each other between the DC power supplies.
And the second switching means are connected in series, and another circuit component, for example, a resistor may be interposed between the first and second switching means and the DC power supply. Also, a circuit component may be interposed between the first and second switching means.

<Load Circuit> The load circuit includes at least a current-limiting inductor and a parallel circuit of a discharge lamp and a resonance capacitor in series. And it operates by the alternating current generated by the alternating switching of the first and second switching means.

The current limiting inductor and the resonance capacitor are:
It resonates with the alternating current generated by the alternating switching of the first and second switching means.

The current limiting inductor also compensates for the negative characteristics of the discharge lamp of the load.

When the discharge lamp is a low-pressure discharge lamp such as a fluorescent lamp, uses a filament electrode, and starts the discharge lamp using the filament electrode as a hot cathode, a method of heating the filament electrode at the time of starting is as follows. There are the following two types.

First, a resonance capacitor is connected in parallel with the discharge lamp via at least one filament electrode at the time of starting. Then, a current flows to the filament of the electrode through the current-limiting inductor and the resonance capacitor at the time of starting, so that the filament is heated. At the same time, the current limiting inductor and the resonance capacitor resonate appropriately in series, and the terminal voltage of the resonance capacitor increases, so that the starting of the discharge lamp is promoted.

Second, the filament electrode is heated using a filament heating transformer. The filament heating transformer may be provided separately from the current limiting inductor, but if necessary, the filament heating winding can be magnetically coupled to the current limiting inductor. This can suppress an increase in the number of circuit components.

Further, an instant start in which the discharge lamp is started by applying a high voltage between the pair of electrodes without preheating the discharge lamp may be performed.

<First Gate Drive Circuit> The first gate drive circuit includes feedback means and an LC resonance circuit magnetically coupled to the current limiting inductor, and controls ON of the first switching means. Note that the ON control means that a gate drive signal is supplied to a control terminal of a switching unit to be turned on.

The feedback means is composed of a winding and magnetically couples to the current limiting inductor to feed back the alternating current flowing through the load circuit to the first gate drive circuit.

The LC resonance circuit includes an inductor and a capacitor, and resonates with a feedback voltage generated in the feedback means.
Forming a gate drive signal for the first switching means;

In order to make the inductor as small as possible, it is preferable to use a core having an air gap or to make the inductor air-core. This makes it difficult for the inductor to be magnetically saturated even if it is small.

In order to regulate the gate drive signal to a predetermined voltage, if necessary, a voltage clamp circuit can be used as a gate protection circuit.

Further, an appropriate impedance can be interposed between the LC resonance circuit and the feedback means. Then, the phase of the feedback voltage applied to the LC resonance circuit can be appropriately adjusted by the impedance.

<Regarding the Second Gate Drive Circuit> The second gate drive circuit includes a secondary winding magnetically coupled to the inductor of the LC resonance circuit of the first gate drive circuit in a reverse polarity relationship. The switching means is turned on. That is, when the polarity of the terminal voltage of the inductor of the LC resonance circuit of the first gate drive circuit is in the direction in which the first switching means is turned on, the voltage is induced in the secondary winding of the second gate drive circuit. The voltage is pre-associated so as to have a polarity in a direction in which the second switching means is turned off. Thus, the first and second switching means are alternately turned on and off.

<Other Configurations> In order to start the half-bridge type inverter, a suitable starting circuit can be added. For example, a DC power supply voltage dividing circuit mainly composed of a resistor may be configured to divide the DC power supply voltage to the control terminal of the first switching means so that a predetermined gate drive voltage is applied. . Further, the first circuit is mainly composed of a time constant circuit and a trigger element.
A predetermined gate drive voltage may be applied to the control terminal of the switching means from the DC power supply.

When a rectified DC power supply is used as the DC power supply, a noise filter is connected to the low-frequency AC power supply and the AC input of the rectifier circuit so that high-frequency noise due to switching of the first and second switching means does not flow into the low-frequency AC power supply. It can be inserted between the ends.

<Function of the Present Invention> In the present invention, an AC half-bridge type inverter flowing through a load circuit is constituted by alternately switching the first and second switching means, and a discharge lamp as a load is attached by the AC. And the negative current characteristic of the current-limiting inductor is compensated to light the lamp. Then, the alternating current flowing through the load circuit is fed back to the first gate drive circuit by the feedback means of the first gate drive circuit magnetically coupled to the current limiting inductor.

When a feedback voltage is generated in the first gate drive circuit, the LC resonance circuit resonates with the feedback voltage, and the control terminal of the first switching means is connected so that the resonance voltage of the LC resonance circuit is applied. Therefore, when the resonance voltage has a predetermined polarity with respect to the control terminal of the first switching means,
Gate driving is performed, and the first switching means is turned on. At this time, a voltage is also induced in the secondary winding of the second gate drive circuit, but the secondary winding has a reverse polarity relationship of L.
Since it is magnetically coupled to the inductor of the C resonance circuit, 2
Since a voltage of the opposite polarity is applied to the control terminal of the second switching means connected to the next winding, the second switching means maintains the off state.

Next, when the resonance voltage of the LC resonance circuit is inverted, the voltage at the control terminal of the first switching means has the opposite polarity, so that the first switching means is turned off. On the other hand, since the voltage induced in the secondary winding of the second gate drive circuit has the opposite polarity relationship with the inductor of the LC resonance circuit, the polarity is inverted and the voltage induced in the secondary winding of the second gate drive circuit is inverted. Is applied to the control end of the switching means, and turns on the second switching means. Thereafter, the first and second switching means repeat the above operation, so that an alternating current flows through the load circuit. That is, the half-bridge inverter of the present invention performs an inverter operation by self-excited oscillation through the feedback means and the secondary winding.

As apparent from the above description, in the present invention, the secondary winding of the second gate drive circuit is magnetically coupled directly to the inductor of the LC resonance circuit of the first gate drive circuit in a reverse polarity relationship. Therefore, a transformer different from the LC resonance circuit as in the prior art 2 is not required.
For this reason, the number of relatively large and expensive winding parts is reduced, so that not only the discharge lamp lighting device but also the lighting device can be reduced in size and provided at a low cost.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device,
2. The discharge lamp lighting device according to claim 1, wherein the first and second switching means include an enhancement type M.
It is characterized by comprising an OSFET.

Since the FET is a switching means having a voltage switching structure, control is easy. Also, MO
The SFET is effective as a power switching means that is less restricted by a safe operation area. Further, the enhancement type MOSFET is easy as power-on processing, and is suitable as a power switching means.

In the enhancement type MOSFET, when a gate voltage is applied between the gate and the source, a channel is formed and the MOSFET is turned on. Therefore, the off state is maintained when no gate voltage is applied.

Thus, the present invention is a discharge lamp lighting device in which an enhancement type MOSFET is specified as an optimum switching means.

According to a third aspect of the present invention, there is provided a discharge lamp lighting device,
3. The discharge lamp lighting device according to claim 2, wherein the source of the second switching means is connected to the stable potential side.

The stable potential may be formed on either the negative electrode or the positive electrode of the DC power supply.

One electrode of the discharge lamp of the load is always connected to the stable potential side. Then, the other electrode of the discharge lamp is connected to a connection point of the first and second switching means via a current limiting inductor.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device,
The discharge lamp lighting device according to any one of claims 1 to 3, wherein the first gate drive circuit includes a gate protection circuit connected in parallel with the inductor of the LC resonance circuit.

The gate protection circuit prevents an excessive voltage from being applied to the gates of the first and second switching means, and may have any specific circuit configuration. For example, a gate protection circuit can be configured by connecting at least two or more zener diodes in series with opposite polarities. By connecting this gate protection circuit in parallel with the inductor of the LC resonance circuit, a voltage higher than the Zener voltage with respect to the resonance voltage of both positive and negative polarities is clamped and applied to the control terminals of the first and second switching means. can do.

Here, the reason why the second switching means also has a gate protection function is that a clamped voltage is induced by magnetic coupling also in the secondary winding of the second gate drive circuit. Because.

Further, the gate protection circuit can be configured by various similar circuit configurations as long as it is a constant voltage element, without using a Zener diode.

Further, the number of constant voltage elements to be used may be determined according to the relation between the constant voltage and the gate voltage.

Then, the voltage which becomes overvoltage with respect to the gate is short-circuited and absorbed by the gate protection circuit, so that only an appropriate voltage is applied to each gate of the first and second switching means. Not done. When an overvoltage is applied to the switching means, the switching means may be destroyed. Therefore, it is preferable to add a gate protection means.

Further, in the present invention, even if the first and second switching means are of the same polarity, only one set of the gate protection circuit needs to be used. This can contribute to downsizing of the device.

According to a fifth aspect of the present invention, there is provided a lighting device comprising: a lighting device main body; and the discharge lamp lighting device according to any one of the first to fourth aspects supported by the lighting device main body. And

In the present invention, the term "illumination device" is a broad concept including any device utilizing the light emission of a discharge lamp, and includes, for example, a lighting device, a backlight device such as a liquid crystal device, a personal computer and a television incorporating the same. It includes various information devices such as receivers and GPS devices, image reading devices and OA devices such as copiers, facsimiles and scanners incorporating the same, and light bulb-type fluorescent lamps.

In particular, in the present invention, since the discharge lamp lighting device can be remarkably miniaturized, it is suitable for a compact compact fluorescent lamp.

[0051]

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

FIG. 1 is a circuit diagram showing a first embodiment of a discharge lamp lighting device according to the present invention.

In the figure, AS is a low-frequency AC power supply, f is an overcurrent fuse, NF is a noise filter, RD is a rectified DC power supply, Q1 is a first switching means, and Q2 is a second switching means.
Switching means, LC is a load circuit, GDC1 is the first
GDC2 is a second gate drive circuit, and ST is a start circuit.

<Regarding Low Frequency AC Power Supply AS> The low frequency AC power supply AS is a commercial 100 V AC power supply.

<Regarding Overcurrent Fuse f> The overcurrent fuse f is, for example, a pattern fuse integrally formed on a wiring board on which circuit components of the discharge lamp lighting device are mounted, and the low-frequency AC input current becomes an overcurrent. At this time, the circuit is protected from fusing and burning.

<Regarding Noise Filter NF> The noise filter NF is composed of a low-frequency AC power supply AS and a rectified DC power supply R.
D in series to prevent high-frequency noise generated by the alternate switching of the first and second switching means Q1 and Q2 from flowing out to the low-frequency AC power supply AS side. , Inductor L
1 low-frequency AC power supply AS on the low-frequency AC power supply AS side
And a capacitor C1 which is connected in parallel with the inductor L1 to form an inverted L-shaped circuit together with the inductor L1.

<Regarding Rectified DC Power Supply RD> The rectified DC power supply RD includes a bridge type full-wave rectifier circuit BRC and a smoothing capacitor C2.

The bridge type full-wave rectifier circuit BRC has an AC input terminal connected to a low-frequency AC power supply AS via a noise filter NF, and a DC output terminal connected to both ends of a smoothing capacitor C2.

<Regarding First Switching Means Q1>
The first switching means Q1 is composed of an enhancement-type N-channel MOSFET, and has a drain connected to the positive electrode of the rectified DC power supply RD.

The second switching means Q2 is also composed of an enhancement type N-channel MOSFET, the drain of which is connected to the source of the first switching means Q1, and the source of which is connected to the negative electrode of the rectified DC power supply RD. ing.

The first and second switching means Q1, Q2 are connected in series between both ends of the rectified DC power supply RD.

<Regarding Load Circuit LC> Load Circuit LC
Is a current limiting inductor L2, a DC cut capacitor C3,
It consists of a discharge lamp DL and a resonance capacitor C4.

One end of the current limiting inductor L2 is connected to a connection point between the first and second switching means Q1 and Q2, and the other end is connected to one end of the DC cut capacitor C3.

The other end of the DC cut capacitor C3 is connected to one end of the discharge lamp DL.

The discharge lamp DL constitutes a load in the load circuit LC. In this embodiment, a fluorescent lamp is used. Then, one electrode E of the discharge lamp DL
One power supply side terminal is connected to one end of the DC cut capacitor C3, and the other power supply side terminal of the electrode E2 is connected to the source of the second switching means Q2.

The resonance capacitor C4 is connected between the non-power-supply-side terminals of both electrodes E1 and E2 of the discharge lamp DL.

Thus, the load circuit LC forms a series resonance circuit including the current limiting inductor L2, the capacitor C3, and the resonance capacitor C4. However, since the DC cut capacitor C3 has a large capacitance, the resonance capacitor C4 mainly contributes to resonance.

<Regarding First Gate Drive Circuit GDC1> The first gate drive circuit GDC1 includes a feedback means s, an impedance Z1, an LC resonance circuit RC, and a capacitor C5.

The feedback means s comprises an auxiliary winding magnetically coupled to the current limiting inductor L2 of the load circuit LC, one end of which is connected to the connection point of the first and second switching means Q1 and Q2, and the other end of which is connected to the first and second switching means Q1 and Q2. Each is connected to one end of an impedance Z1 composed of a resistor.

The LC resonance circuit RC comprises a parallel circuit of an inductor L3 and a capacitor C6, and both ends thereof are connected in parallel to a feedback means s via an impedance Z1.

The inductor L3 is formed by winding a coil around a core having a gap.

The capacitor C5 has a relatively large capacitance, and has an LC resonance circuit RC and an impedance Z1.
And the gate of the first switching means Q1 is inserted in series.

<Regarding Second Gate Drive Circuit GDC2> The second gate drive circuit GDC2 includes a secondary winding W2 and an impedance Z2.

The secondary winding W2 is magnetically coupled in reverse polarity to the inductor L3 of the LC resonance circuit RC of the first gate drive circuit GDC1, and one end thereof is connected to the gate of the first switching means Q2. . Also, the secondary winding W
The other end of 2 is connected to the source of the second switching means Q2.

The impedance Z2 consists of a resistor,
It is connected in parallel to the secondary winding W2.

<Regarding the starting circuit ST> Starting circuit ST
Consists of resistors R1 and R2.

The resistor R1 has one end connected to the positive electrode of the rectified DC power supply RD and the other end connected to the first switching means Q.
It is connected to the connection point of the first gate and the capacitor C5 of the first gate drive circuit GDC1.

The resistor R2 is connected to the second switching means Q
2 are connected in parallel between the drain and source.

<Circuit Operation> Low-frequency AC power supply AS
Is turned on, a DC voltage smoothed by the rectified DC power supply RD appears at both ends of the smoothing capacitor C2. Then, a DC voltage is applied between the drain and the source of the first and second switching means Q1 and Q2 connected in series. However, the first and second switching means Q1,
Q2 remains off because no gate voltage is applied.

The DC voltage is simultaneously applied to the series circuit of the resistor R1, the capacitor C5 of the first gate drive circuit GDC1, the inductor L3 and the resistor R2, and while the capacitor C5 is being charged, the resistors R1 and R2 are connected. Since the DC voltage higher than the source is applied to the gate of the first switching means Q1 by the proportional ratio of the resistance values of the first switching means Q1,
Since the switching means Q1 exceeds the threshold voltage, a channel is formed and the switching means Q1 is turned on.

On the other hand, the second switching means Q
2 remains off because no voltage is applied to its gate.

When the first switching means Q1 is turned on, the load circuit LC, that is, the current limiting inductor L2, the DC cut capacitor, is connected from the positive electrode of the rectified DC power supply RD via the drain and source of the first switching means Q1. C3, resonance capacitor C4 and rectified DC power supply RD
A current flows through the negative electrode path. At this time, the series resonance circuit of the current limiting inductor L2, the DC cut capacitor C3, and the resonance capacitor C4 of the load circuit LC resonates, and the terminal voltage of the resonance capacitor C4 increases and is charged.

On the other hand, when a current flows through the current-limiting inductor L2, the feedback means s of the first gate drive circuit GDC1 magnetically coupled to the current-limiting inductor L2 has a polarity symbol attached to the feedback means s in the figure. A high polarity voltage is induced at the terminals. At this time, the voltage drop of the current limiting inductor L2 is higher at the terminal to which the polarity symbol is attached in the figure.

When the voltage induced in the feedback means s is applied to the LC resonance circuit RC via the impedance Z1, L
The C resonance circuit RC resonates. Due to this resonance, the terminal voltage of the inductor L3 rises, and the first
Is applied as a gate drive voltage to the gate of the first switching means Q1.
Remains on.

On the other hand, in the second gate drive circuit GDC2, since the polarity of the induced voltage of the secondary winding W2 is reversed, a voltage lower than the source is applied to the gate of the second switching means Q2. Therefore, it remains off.

However, the polarity of the resonance voltage of the LC resonance circuit RC is inverted next due to the vibration caused by the resonance.
At that time, the gate of the first switching means Q1 is turned off due to the reverse voltage, and conversely, the gate of the second switching means Q2 is turned on with the polarity in the drive direction.

Therefore, the first switching means Q1
Is ON time of the first gate drive circuit GDC1.
It is determined by the capacitance of the capacitor C6 of the C resonance circuit RC and the primary inductance of the inductor L3.

The capacitance of the capacitor C5 is selected to be large enough not to affect the values and phases of the positive and negative gate voltages.

When the first switching means Q1 is turned off, the electromagnetic energy stored in the current limiting inductor L2 is released, and the direct current cut capacitor C3, the resonance capacitor C4, the second switching means Q2 Regulation diode and current limiting inductor L2
When the current becomes 0, the charge of the resonance capacitor C4 is discharged through the path of the DC cut capacitor C3, the current limiting inductor L2, the second switching means Q2, and the resonance capacitor C4. Then, the current flows in the opposite direction. At this time, the voltage induced in the feedback means s magnetically coupled to the current limiting inductor L2 is low at the terminal to which the polarity symbol is attached in FIG.
Since the other terminal becomes higher, the first switching means Q1 to which the resonance voltage is applied via the LC resonance circuit RC maintains the off state, and the second switching means Q2 maintains the on state.

However, the first gate drive circuit GD
When the resonance voltage of the LC resonance circuit RC of C1 oscillates and the polarity is inverted, the first switching means Q1 turns on again,
The second switching means Q2 turns off.

As a result, a current flows from the positive electrode of the rectified DC power supply RD to the load circuit LC again as described first. Hereinafter, the operation described above is repeated to operate as a half-bridge type inverter.

By the way, in the load circuit LC, when a current flows through the resonance capacitor C4 during the above operation, the current flows through the filaments of the pair of electrodes E1 and E2 of the discharge lamp DL to heat the filaments. The electrodes E1 and E2 enter thermionic emission state, and a high voltage due to resonance is applied between the electrodes E1 and E2, so that the discharge lamp DL is started up and turned on.

When the discharge lamp DL is turned on, its electrode E
Since the voltage between E1 and E2 becomes a lamp voltage as low as about half of the DC voltage, the resonance of the resonance capacitor C4 is relaxed. However, a voltage drop due to the lamp current appears in the current limiting inductor L2. Voltage induction is continued.

FIG. 2 is a circuit diagram showing a second embodiment of the discharge lamp lighting device according to the present invention.

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the stable potential side is the positive side of the rectified DC power supply RD, a gate protection circuit GP is provided, and a start circuit ST having a different circuit configuration is provided.

That is, since the first and second switching means Q1 and Q2, the load circuit LC, and the first and second gate drive circuits GDC1 and GDC2 are respectively connected to the inverting positions in the figure, the rectification is performed. It is configured such that a stable potential appears on the positive electrode side of the DC power supply RD. However, the circuit operation is basically the same as that of FIG.

The gate protection circuit GP has two zener diodes connected in anti-series, and is connected in parallel between the gate voltage output terminals of the first gate drive circuit GDC1. When the first gate drive voltage is higher than a predetermined value, the gate protection circuit GP clamps a voltage higher than the predetermined value.

The voltage clamping operation by the gate protection circuit GP acts on positive and negative gate drive voltages.

Also, the voltage clamped on the primary side is LC
Since the secondary winding W2 magnetically coupled to the inductor L3 of the resonance circuit RC is also induced in the second gate drive circuit GDC2, the gate of the second switching means Q2
The gate voltage applied between the sources is also clamped.

The starting means ST comprises a time constant circuit TC, a trigger element Tg and a diode D1.

The time constant circuit TC comprises a series circuit of a resistor R3 and a capacitor C7, and is connected between the output terminals of the rectified DC power supply RD.

The trigger element Tg is connected between the connection point of the resistor R3 and the capacitor C7 of the time constant circuit TC and the gate of the first switching means Q1.

The diode D1 has an anode connected to the connection point of the resistor R3 and the capacitor C7 of the time constant circuit TC, a drain connected to the drain of the first switching means Q1, and a cathode connected to the source.
Are connected so as to be short-circuited.

Therefore, the diode D1 discharges the charge of the capacitor C7 by the first switching means Q1 after the activation of the half-bridge type inverter, so that the capacitor C7 is charged via the resistor R3 and the terminal voltage rises. By doing so, it works to prevent the starting circuit ST from operating again.

When the low-frequency AC power supply AS is turned on, the capacitor C7 of the time constant circuit TC is charged via the resistor R3, and the terminal voltage increases. When the terminal voltage exceeds the trigger voltage of the trigger element Tg, the trigger element Tg is turned on, so that the terminal voltage of the capacitor C7 is applied between the gate and the source of the first switching means Q1. Thereby, the first switching means Q
1 turns on.

On the other hand, the second switching means Q
2 is in an off state because no voltage is applied between its gate and source.

The subsequent circuit operation is basically the same as in FIG.

FIG. 3 is a waveform diagram showing waveforms of voltages and currents at various parts in the discharge lamp lighting device according to the second embodiment of the present invention.

In the figure, (a) is the induced voltage Vs of the feedback means, (b) is the gate drive voltage Vd1 of the first switching means Q1, and (c) is the second switching means Q
2, the gate drive voltage Vd2, (d) is the current Iq1 of the first switching means, and (e) is the current Iq2 of the second switching means.

The first and second switching means Q1,
It can be understood from the waveforms that the gate drive voltages Vd1 and Vd2 of Q2 are both gate voltages clamped by the gate protection circuit GP.

FIG. 4 is a front view showing a bulb-type fluorescent lamp as one embodiment of the lighting device of the present invention.

FIG. 5 is an enlarged cross-sectional view of the main part.

In each of the figures, 1 is a fluorescent lamp, 2 is a discharge lamp lighting device, 3 is an envelope, and 4 is a base.

In the fluorescent lamp 1, three U-shaped glass tubes are equally arranged on a concentric circle, and the glass tubes are connected by a thin connecting tube so that a bent discharge path is formed inside. A light-transmitting discharge container formed in a compact shape, a phosphor layer disposed on the inner surface side of the light-transmitting discharge container, and a pair of electrodes sealed at both ends of the light-transmitting discharge container,
An ionizing medium containing an appropriate amount of mercury and a rare gas sealed inside the translucent discharge vessel.

The discharge lamp lighting device 2 has the circuit configuration shown in FIG.

The envelope 3 comprises a light-transmitting globe 3a, a light-shielding base 3b, and a partition 3c located between the light-transmitting globe 3a and the light-shielding base 3b.

The translucent globe 3a has a glass bottomed cylindrical shape with a light diffusing coating formed on the inner surface.

The light-shielding substrate 3b has a cup shape formed by molding a white synthetic resin, and a light-transmitting globe 3a is fixed to the opening end thereof by using a silicone adhesive 3d.

The partition 3c is formed by molding a white synthetic resin, and is fixed to the opening end of the light-shielding base 3b of the envelope 3 together with the translucent glove 3a by the silicone adhesive 3d.

The partition 3c divides the inside of the envelope 3 into a light-emitting room A and a circuit storage room B. Further, a fluorescent lamp support hole 3c1 and the like are formed in the partition 3c.

Then, both ends of the fluorescent lamp 1 are inserted into the fluorescent lamp supporting holes 3c1 of the partition 3c from the light emitting chamber A side and fixed and supported by the silicone adhesive, and the light of the envelope 31 is emitted. It is located in room A.

The discharge lamp lighting device 2 comprises a board 2a and a circuit component 2b mounted on the board 2a.
c and is disposed in the circuit storage room B of the envelope 3.

The base 4 is mounted on the base end of the light-shielding base 3b of the envelope 3 and connected to the AC input end of the discharge lamp lighting device 2. The output end of the discharge lamp lighting device is connected to both electrodes of the fluorescent lamp 1. Connected to

[0125]

According to the first to fourth aspects of the present invention, at least a current-limiting inductor operated by an alternating current generated by alternate switching of first and second switching means connected in series between DC power supplies, And a first gate drive circuit including a load circuit including a parallel circuit of a discharge lamp and a resonance capacitor in series, and including feedback means magnetically coupled to the current limiting inductor and an LC resonance circuit resonating with a feedback voltage generated in the feedback means. And a second gate drive circuit including a secondary winding magnetically coupled to the inductor of the LC resonance circuit in a reverse polarity relationship, wherein the first gate drive circuit controls the first switching means,
Controlling the second switching means by the gate drive circuit of (1), the first and second gate drive circuits of the half-bridge type inverter are simplified, and the number of circuit components, particularly winding components, is reduced to reduce the size and cost. A down-loaded discharge lamp lighting device can be provided.

According to the second aspect of the present invention, in addition to the above, the first and second switching means are provided with an enhancement type MO.
By using the SFET, it is possible to provide a discharge lamp lighting device having easy-to-control and optimum switching means for electric power.

According to the third aspect of the present invention, since the second switching means is connected to the stable potential side, the stable potential may be formed on either the positive electrode or the negative electrode of the DC power supply. A lamp lighting device can be provided.

According to the fourth aspect of the present invention, in addition to the above, the first gate drive circuit includes the gate protection circuit connected in parallel to the inductor of the LC resonance circuit.
And a discharge lamp lighting device in which gate protection is effectively applied to the gate drive circuit.

According to the fifth aspect of the present invention, it is possible to provide a lighting device having the effects of the first to fourth aspects.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a discharge lamp lighting device according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the discharge lamp lighting device of the present invention.

FIG. 3 is a waveform diagram showing waveforms of voltages and currents of respective parts in a second embodiment of the discharge lamp lighting device of the present invention.

FIG. 4 is a front view showing a bulb-type fluorescent lamp as one embodiment of the lighting device of the present invention.

FIG. 5 is an enlarged sectional view of a main part of the same.

[Explanation of symbols]

 AS: Low frequency AC power supply f: Overcurrent fuse NF: Noise filter L1: Inductor C1: Capacitor RD: Rectified DC power supply BRC: Bridge type full-wave rectifier circuit C2: Smoothing capacitor Q1: First switching means Q2: Second Switching means LC: Load circuit L2: Current limiting inductor C3: DC cut capacitor C4: Resonant capacitor DL: Discharge lamp E1: One electrode E2: The other electrode GDC1: First gate drive circuit s ... Feedback means Z1: Impedance C5: capacitor RC: LC resonance circuit L3: inductor C6: capacitor GDC2: second gate drive circuit W2: secondary winding Z2: impedance GP: gate protection circuit ST: start circuit TC: time constant circuit R3: resistor C7 … Capacitor Tg… Trigger element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideo Kozuka 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Litec Corporation (72) Inventor Hajime Osaki 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo No. Toshiba Litec Corporation F-term (reference) 3K072 AA02 BA03 BB01 BC01 BC03 DB03 DD04 GA03 GB12 GC02 5H007 BB03 CA02 CB03 CB17 CB22 CC07 CC32 HA03

Claims (5)

[Claims] 1. A DC power supply; a first switching means and a second switching means connected in series between the DC power supplies; and at least a current limiting inductor, and a parallel circuit of a discharge lamp and a resonance capacitor in series. A load circuit operated by an alternating current generated by alternate switching of the first and second switching means; a feedback means magnetically coupled to the current-limiting inductor; an LC resonance circuit resonating with a feedback voltage generated in the feedback means; A first gate drive circuit for turning on the first switching means based on the resonance voltage of the LC resonance circuit; and a secondary winding magnetically coupled to the inductor of the LC resonance circuit of the first gate drive circuit in a reverse polarity relationship. A second gate drive circuit that turns on the second switching means based on the voltage induced in the secondary winding; Discharge lamp lighting apparatus, characterized in that it comprises a. 2. The discharge lamp lighting device according to claim 1, wherein said first and second switching means comprise enhancement-type MOSFETs. 3. The discharge lamp lighting device according to claim 2, wherein the source of the second switching means is connected to the stable potential side. 4. The discharge lamp lighting device according to claim 1, wherein the first gate drive circuit includes a gate protection circuit connected in parallel with the inductor of the LC resonance circuit. . 5. A lighting device comprising: a lighting device main body; and the discharge lamp lighting device according to claim 1 supported by the lighting device main body.