JP2002153071A - Inverter type stabilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further reduce the size of a neutral point inverter type stabilizer. SOLUTION: This neutral point inverter type stabilizer comprises a rectifier DB for rectifying an AC voltage Vi, voltage dividing capacitors C4, C5 connected in parallel between the DC output terminals DC+, DC- of the rectifier DB, a smoothing capacitor C33 for smoothing an DC output of the rectifier DB, FETs Q5, Q7 connected in parallel between DC output terminals of the rectifier DB, and a self-excitation type drive circuit DR provided with a drive transformer T2 to alternately drive ON and OFF the FETs Q5 and Q7. Moreover, this neutral point inverter type stabilizer connects one end AC2 of an AC input of the rectifier DB; and a neutral point B of the capacitors C4, C5, distributes a voltage step-up inductor L6 between the neutral point B and the connecting point SW of the FETs Q5 and Q7, and also distributes a Lamp LT via a current limiting inductor. The smoothing capacitor C33 is formed of (x) divided capacitors C33a to C33n connected in parallel, each of which is composed of a film capacitor. Each divided capacitor C33a to C33n is provided horizontally to realize arrangement along the longitudinal direction of the casing thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies high-frequency AC power to a discharge tube such as a fluorescent lamp by rectifying and smoothing an AC voltage, converting it to a substantially DC voltage, and then converting it to a high-frequency AC voltage. The present invention relates to an inverter type ballast.

[0002]

2. Description of the Related Art In fluorescent lamps for domestic use and fluorescent lamps for facilities, a circuit system for lighting a fluorescent lamp is conventionally called a copper-iron type ballast such as a choke current limiting type or a leakage transformer type. However, due to limitations in terms of shape, weight, and efficiency, today's fluorescent lighting fixtures require an AC voltage to be rectified, smoothed, temporarily converted to a DC voltage, and then further converted to a high-frequency voltage. 2. Description of the Related Art A lamp control device called an inverter type ballast (high frequency lighting type ballast) for supplying high frequency power obtained by conversion to a fluorescent lamp appliance as a load has been used.

[0003] This inverter type ballast has advantages such as efficient power saving, reduction of lamp flicker and ballast noise, and weight reduction. Is rapidly advancing. In such an inverter type ballast, a current limiting inductor or a leakage transformer is required as a means for limiting the lamp current exhibiting negative resistance, but since the lamp current has a high frequency, the element itself is a conventional one. Smaller and lighter than copper-iron type ballast.

However, the inverter type ballast generally employs a capacitor smoothing circuit system of full-wave rectification using a rectifier (diode) and smoothing it with an electrolytic capacitor, and distorted wave caused by nonlinearity of the diode. The current flows to the commercial power supply, and as a result, a problem that a harmonic component (harmonic current) flows in the input current on the commercial power supply side, that is, a problem of so-called harmonic disturbance of the power supply occurs.

[0005] For this reason, when converting the power supply into an inverter, it is necessary to consider a circuit technique for suppressing harmonic currents. For example, an AC reactor insertion method, a partial smoothing method, an active smoothing filter method (inverter fluorescent lamp;
Electronic technology, Vol.32, No.3, pp.113-119) Dither rectification method (High power factor switching regulator using dither effect; Proceedings of IEEJ National Convention, No.546, pp.5-137
See).

Further, similarly to the dither rectification method, a neutral point inverter type ballast (neutral point type electronic ballast circuit) capable of reducing the harmonic component of the input current on the commercial power supply side only by the inverter for lighting the fluorescent lamp. (“One method of simple harmonic reduction circuit”; Yoshito Kato, Journal of the Institute of Electrical Installations,
Vol.12, No.10, pp.902-904, "Development of Electronic Ballast with Low Input Current Using Neutral Point Inverter"; Yoshito Kato, Journal of the Illuminating Engineering Institute of Japan, Vol79, No.2, pp.14- 20 etc.).

[0007] The applicant of the present application also proposed in Japanese Patent No. 2869397 a method in which a conventional neutral point type electronic ballast circuit was improved as a suitable circuit for preventing harmonic interference of inverter equipment, and an example of its utilization form. A neutral point inverter type ballast with a fluorescent lamp as a load is proposed.

The neutral point inverter type ballast proposed by the applicant of the present application can prevent harmonic interference as described in the same publication and can use a commercial AC voltage without using a step-up transformer. In addition to being able to supply a high-output and stable high-frequency voltage to a load such as a discharge tube by itself, a relatively small boost inductor or smoothing capacitor can be used, which is convenient for miniaturization of the device. Good and good.

[0009]

In recent years, however, the diameter of fluorescent lamps has been gradually reduced in consideration of resource saving, and there has been a demand for smaller lighting fixtures. Inverter-type ballasts are increasingly required to be downsized.

Here, an inverter type ballast using a method other than the neutral point type as described above requires a large-capacity and large-sized smoothing capacitor, usually several hundred μF, as opposed to the above-mentioned application. As described in the above patent publication, the neutral point type inverter ballast proposed by humans has a wide allowable range for setting the constant of the smoothing capacitor without the input peak current flowing, so that ripple voltage and the like can be reduced. In consideration of this, a small-capacity and small-sized capacitor of, for example, 7 to 10 μF can be used, which is convenient for miniaturizing the ballast.

However, when trying to reduce the thickness and size of the one described in this patent publication, the size of the smoothing capacitor still poses a problem.

The present invention has been made in view of the above circumstances, and has as its object to provide an inverter-type ballast that can be made smaller and thinner.

[0013]

An inverter type ballast according to the present invention is an inverter type ballast for supplying high-frequency AC power to a discharge tube, comprising: a rectifier for rectifying an input AC voltage; The first connected in parallel with the DC output
And a second capacitor (smoothing capacitor) for smoothing the DC output of the rectifier, and first and second switching elements connected in parallel to the DC output of the rectifier. , A first and second diode (fly-hole diode) connected in parallel to the first and second switching elements so as to be in the opposite directions in direct current, respectively, and the first and second switching elements.
A drive circuit for alternately turning on and off the respective switching elements, one end of an AC input of the rectifier, and first and second
And a boost inductor connected between the switching element and a neutral point, which is a connection point between the first and second capacitors, and one end of the AC input of the rectifier. In an inverter type ballast in which a discharge tube is arranged in parallel with an inductor, a third capacitor is constituted by a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are arranged along a longitudinal direction of the discharge tube. It is characterized by being provided in a line.

When the third capacitor is constituted by a plurality of divided capacitors electrically connected in parallel, the capacitance required as the third capacitor is substantially equal to the sum of the capacitances of the plurality of divided capacitors connected in parallel. That is to make them equal. The capacitances of the split capacitors may be all equal or different.

Here, an electrolytic capacitor generally used as the third capacitor has a problem that a large loss (tan δ) is generated and heat is generated. Therefore, the capacitance required as the third capacitor is required from the viewpoint of circuit characteristics. It is common to take measures against heat generation by using a capacitor having a capacity about 5 to 10 times larger than the capacity mentioned above, which is one of the causes of an increase in the size of the ballast. When an electrolytic capacitor is used as the split capacitor, each of the split capacitors can have a smaller capacity and a smaller loss than the capacity required for the third capacitor, and the heat generation is reduced accordingly. Therefore, when the capacitance required as the third capacitor is made substantially equal to the total sum of the respective capacitors of the plurality of divided capacitors connected in parallel, for example, taking into account the effect of reducing heat generation due to the loss reduction, for example, circuit characteristics The total capacitance may be smaller than the capacitance required as the third capacitor, for example, about 3 to 8 times the capacitance required from above.

In the inverter type ballast according to the present invention,
It is desirable to provide each of the plurality of divided capacitors such that the longitudinal direction of the divided capacitors extends in the longitudinal direction of the discharge tube.

Further, in the inverter type ballast according to the present invention, it is preferable that each of the plurality of divided capacitors is a film capacitor.

[0018]

According to the inverter type ballast of the present invention,
The smoothing capacitor serving as the third capacitor is constituted by a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are provided so as to be arranged along the longitudinal direction of the discharge tube. In addition, the capacity and the size can be reduced as compared with the case where the smoothing capacitor is constituted by one capacitor. Further, since the small-capacity and small-sized split capacitors are provided so as to be arranged along the longitudinal direction of the discharge tube, the ballast can be made smaller, thinner, and thinner.

If the split capacitor is provided so that the longitudinal direction of the split capacitor extends in the longitudinal direction of the discharge tube, the ballast can be made thinner.

Further, since a plurality of split capacitors are arranged side by side in the longitudinal direction of the discharge tube, as a whole,
A thin ballast can be configured.

Further, since each of the divided capacitors can be dispersedly arranged on the printed circuit board, it can be installed in a surplus space of other components on the printed circuit board, and there is an advantage that the degree of freedom in mounting the divided capacitors is increased. . In addition, such a distributed arrangement makes it possible to adjust the smoothed potential of each part on the substrate, so that the effect of the inverter operation and the malfunction prevention of other circuits such as a protection circuit can be obtained.

If a film capacitor is used instead of an electrolytic capacitor as a split capacitor, a capacitor having a smaller loss can be used, and the problem of heat generation can be almost ignored. As a result, the total sum of the capacitances of the divided capacitors connected in parallel can be made substantially equal to the required capacitance in terms of circuit characteristics, and the ballast is formed using an extremely small and small-capacity film capacitor. It can be smaller and thinner. In addition, since the film capacitor is relatively thin and flat, if the film capacitor is arranged so that the longitudinal direction of the film capacitor extends in the longitudinal direction of the discharge tube, the ballast can be made thinner. it can.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an inverter type ballast according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram of an inverter type ballast according to the present invention.

This inverter type ballast is based on the configuration proposed by the applicant of the present invention in the above-mentioned patent publication, in which the power is supplied to the lamp without passing through a leakage transformer.

First, the circuit configuration will be described. In the present embodiment, a self-excited type using a drive transformer is used instead of a separately-excited type circuit using a dedicated drive IC as a drive (drive) circuit for driving a switching element on and off. Uses an oscillation circuit. The drive circuit may have a separately-excited configuration using a dedicated drive IC or the like.

As shown in FIG. 1, the inverter-type ballast 1 includes four diodes D1 to D4 connected in a bridge, and a rectifier (power supply rectification bridge) DB for full-wave rectifying an input AC voltage. In parallel with the rectifier DB (specifically, between two DC output terminals DC +, DC-)
A series circuit of two connected voltage-dividing capacitors C4 and C5 as first or second capacitors, and a rectifier DB
, A smoothing capacitor C33 as a third capacitor for smoothing the ripple voltage of the output signal, and two FETs (field effect transistors) Q as switching elements connected in parallel with the output of the rectifier DB and the smoothing capacitor C33.
5 and Q7, and a drive circuit DR for alternately turning on and off the FETs Q5 and Q7, respectively. One end of the AC input of the rectifier DB (point AC2 in the figure) is connected to a neutral point (point B in the figure) which is a connection point of the voltage dividing capacitors C4 and C5, and the connection between the neutral point B and the FET is connected. A point (SW point in the figure) is connected to a step-up inductor L6, and a lamp LT as a discharge tube is disposed in parallel with the step-up inductor L6 without passing through a leakage transformer. It has a point-type inverter ballast configuration.

The commercial AC voltage Vi is supplied to the AC input terminals AC1 and AC1 of the rectifier DB via a noise filter LPF composed of an inductor Lf and a capacitor Cf for preventing harmonic interference.
Input between C2.

As the smoothing capacitor C33, a plurality (x) of split capacitors C33a to C33n are provided.
Are electrically connected in parallel. As the division capacitors C33a to C33n, film capacitors are used instead of electrolytic capacitors.

Since the two FETs Q5 and Q7 each include a diode in a direction opposite to the direct current (this state is referred to as an anti-parallel connection state), the diode is used as a flywheel diode. When a transistor is used as a switching element, the flywheel diode must be provided independently, which is more convenient in reducing the size of the device.

The drive circuit DR includes a drive transformer T including a primary winding NP and two secondary windings NS1 and NS2.
2 is configured as a self-excited oscillation circuit, one terminal NPa of the primary winding NP is connected to the connection point SW of the FET, and one terminal NS1a of the secondary winding NS1 is connected to the resistor R
27, the other terminal NS1b is connected to the connection point SW and the boost inductor L6, and one terminal NS2a of the secondary winding NS2 is connected to the gate of the FET Q7 via the resistor R28. And the other terminal NS2b is connected to the rectifier D
B is connected to the DC output terminal DC−.

Two current limiting inductors (current limiting reactors) for limiting the lamp power so as to be electrically connected in series with the lamp LT as a whole between the neutral point B and the connection point SW of the FET. L5 and L7 are connected via the primary winding NP of the drive transformer T2 and two capacitors C7 and C23. Further, a capacitor C11 is connected in parallel with the lamp LT. The capacitors C7 and C23 are set to have a capacitance one order of magnitude greater than that of C11, and are provided for separation (direct current blocking) from a DC circuit such as an abnormal voltage detection circuit (not shown). On the other hand, the capacitor C11 is a current limiting inductor L
It is provided to start the lamp by the series resonance voltage of 5 + L7 and to make the lamp current a sine wave.

The inverter type ballast 1 having the above configuration has a resonance type half bridge configuration. In order to achieve long life as a lighting fixture, it is necessary to turn on the lamp by applying a high voltage after sufficient preheating of the filament.However, the resonance type half-bridge configuration generates a resonance voltage and starts instantaneously. Long life cannot be achieved. In the present embodiment, a power thermistor PTC1 as an element for preventing this is connected in parallel with the lamp LT to form a filament preheating circuit.

The drive circuit DR is composed of a self-excited oscillation circuit using the drive transformer T2 as described above, and the connection of the boost inductor L6 to the primary winding NP is connected to the terminal NPb.
Instead of the terminal NPa, one terminal of the boost inductor L6 is connected to the connection point SW of the FETs Q5 and Q7 without passing through the primary winding NP of the drive transformer T2.
With this configuration, only the lamp current flows through the primary winding NP of the drive transformer T2, and the boosting current does not flow. Since the boosting current flows through the boosting inductor L6, when the boosting inductor L6 is connected to the terminal NPb, not only the lamp current but also the boosting current flows through the primary winding NP, and the boosting current is unstable in a direction to cancel the lamp current. Thus, a signal other than turning on the lamp LT is generated, and furthermore, when there is no lamp LT, oscillation cannot be stopped, and the safety operation is impaired, which is disadvantageous. The connection mode as described above is to avoid this problem.

The inverter type ballast 1 has an output power capacity of 40 W class, and has a ballast thickness of 14 mm.
In order to achieve the following, a flat ferrite core, such as EP manufactured by TDK, is widely used as the boost inductor L6 and the two current limiting inductors L5 and L7.
C core is used as a core material. Then, the inductors are juxtaposed so as to extend in the longitudinal direction of the lamp LT.

The step-up inductor L6 and the two current-limiting inductors L5 and L7 are not limited to these. For example, a long and flat ultra-thin ferrite core having a length of about 140 mm is used as a core material. Using a thin and long ferrite core with a winding formed, this inductor is
The lamps LT can be juxtaposed so as to extend in the longitudinal direction. In this case, it is desirable to arrange a magnetic material for forming a magnetic path on one side or both sides of the inductor so as to extend in the longitudinal direction of the lamp LT in order to reduce the magnetic influence of the surrounding metal members. Note that the two current limiting inductors L5 and L7 may be collectively configured by one inductor.

When the capacity of the voltage dividing capacitors C4 and C5 increases, a pause period of the input current occurs near the AC zero of the input voltage Vi, and a low power factor current waveform (a so-called capacitor input type current waveform). On the other hand, if the capacitances of the voltage dividing capacitors C4 and C5 are small, a high voltage is obtained in the smoothing capacitor C33, but it becomes unstable. Considering these factors comprehensively, the ratio of the capacitance value of the smoothing capacitor C33 to the capacitance value of the voltage dividing capacitors C4 and C5 is 1: 1/100.
About 00 is desirable. For example, when the capacitance value of the smoothing capacitor C33 is 7 to 10 μF,
The capacitance value of C4 and C5 is about 0.004 to 0.01 μF.

Here, the inverter type ballast which is not provided with the voltage dividing capacitor and which is not provided with the voltage dividing capacitor, such as the AC reactor insertion type, the partial smoothing type, the active smoothing filter type, the dither rectification type, etc. In the ballast, a large-capacity and large-sized one, usually several hundred μF, is required as a smoothing capacitor. On the other hand, the inverter-type ballast 1 having the above-described structure has no
Since the allowable range of the constant setting of 33 is wide, a small-capacity and small-sized capacitor of, for example, 7 to 10 μF can be used in consideration of the ripple voltage and the like, which is convenient for downsizing the ballast. I have.

However, in the inverter type ballast having such a configuration, if the smoothing capacitor C33 is configured to be thin and small while being constituted by one electrolytic capacitor, the size of the smoothing capacitor C33 still poses a problem.

On the other hand, in the inverter type ballast 1 having the above configuration, the split capacitors C33a to C33n
As described above, a plurality of divided capacitors are electrically connected in parallel to form the smoothing capacitor C33, so that a smaller capacity and smaller one can be used as each divided capacitor. Can be made smaller.

The split capacitors C33a to C33n
Since a film capacitor is used instead of an electrolytic capacitor, a capacitor having a smaller loss (so-called tan δ) can be used as compared with a case where an electrolytic capacitor is used. As a result, the divided capacitors C33a to C33 can be used.
The total capacitance can be further reduced, for example, by making the sum of the respective n capacitances connected in parallel substantially equal to the required capacitance in terms of circuit characteristics, thereby making it possible to provide a smaller and thinner ballast.

Further, each of the split capacitors C33a-C3
Since 3n can be dispersedly arranged on the printed circuit board, it can be installed in a surplus space of other components on the printed circuit board, and there is a merit that the degree of freedom of mounting the divided capacitor is increased. Further, each of the split capacitors C33a to C3
If 3n are distributed, the smoothed potential of each part on the substrate can be adjusted, and the effect of preventing malfunction of other circuits such as an inverter operation and a protection circuit can be obtained.

For example, as in the conventional case, one smoothing capacitor is used.
When trying to make the inverter thinner when realizing it with one electrolytic capacitor, the size of the electrolytic capacitor (generally a cylindrical large one) used as a smoothing capacitor after the transformer or inductive reactance becomes a problem . Even when a cylindrical electrolytic capacitor is used sideways, it is often the case that the printed circuit board is cut. However, this method is not sufficient to achieve a thin 7 mm thickness.

On the other hand, the printed circuit board for the lamp is often thin and long, and the printed circuit board is often designed so that the power supply voltage is taken in from the short end face on one side and the power is supplied to the lamp LT from the short end face on the other side. In this case, the components are arranged such that a smoothing electrolytic capacitor is arranged after the rectifier DB (diode bridge), and then a switching circuit (a circuit mainly including the FETs Q5 and Q7 in FIG. 1), an inductive reactance, and a resonance capacitor Are often placed. If a starting circuit and a protection circuit are added in addition to the circuit shown in FIG. 1, the thin substrate becomes full of patterns, and the ground pattern in the circuit has to be routed, resulting in a thin and long ground pattern. I will. This often causes a potential difference between the entrance and the exit of the ground pattern and makes the operation of the inverter and the protection circuit unstable in many cases. As a countermeasure, for example, DC + and DC + on the output side such as an inductive reactance are used. −between 0.01 and
A measure was taken by adding a film capacitor of about 1.0 μF. This is a technique similar to a bypass capacitor inserted between a power pin and a ground pin of a digital IC.

On the other hand, according to the configuration of the present invention, as described above, the division capacitors C33a to C33n can be dispersedly arranged, so that the inverter operation and protection can be performed without taking additional measures for the film capacitor. It is possible to prevent malfunction of a circuit or the like.

FIG. 2 shows divided capacitors C33a to C33n.
FIG. 2 is a diagram showing a state in which the inverter type ballast 1 having the above structure is mounted in a lighting fixture housing, and is a perspective view (a), an assembly view (b), and a sectional view (c) taken along the line II in FIG. is there.

As the lighting fixture housing 9, two metal plates 13 and 14 made of aluminum or the like and plastic side panels 18 and 19 are used to sandwich circuit components constituting the inverter type ballast 1. In addition, the lower surface metal plate 13 and the upper surface metal plate 14 are opposed to each other, so that the lighting fixture can be made as thin as possible. In practice, a method is used in which the inverter type ballast 1 is first housed in a predetermined ballast case 2 and the ballast case 2 is arranged in the lighting fixture housing 9. At this time, it is assumed that the side cross section of the two metal plates 13 and 14 in the assembled state is substantially U-shaped or square. In the present embodiment, as shown in FIG. 4C, the two metal plates 13 and 14 have an L-shaped cross section, and the portion surrounding the circuit component in the assembled state is substantially square. To Further, the flange portion 14a on the upper surface side of the upper surface metal plate 14 is fixed to the lamp LT during the assembled state.
And extend it to cover it.

Split capacitor C33a as a circuit component
As shown in FIG. 3 (A) or (B), C33n is the longitudinal direction, the width direction, and the thickness direction (however, the length in the longitudinal direction> width direction) of the lighting fixture housing 9 using the lamp LT. Length> length in the thickness direction), the thickness direction z of the flat film capacitor is made parallel to the thickness direction of the housing, and the longitudinal direction x or the width direction y of the film capacitor is It extends in the longitudinal direction of the lamp LT, whereby the flat surface of the film capacitor is arranged so as to be parallel to the plane including the longitudinal direction and the width direction of the lighting fixture housing. That is, each film capacitor is aligned with the longitudinal direction of the film capacitor. It is provided horizontally so that the direction x or the width direction y is aligned along the longitudinal direction of the lamp LT. This allows the ballast to be small, thin, and thin. However, FIG.
The arrangement of (A) can make the ballast width W narrower.

Also, by adopting such an arrangement,
Since the thickness can be reduced, a long and flat ultra-thin ferrite core having a length of about 140 mm, for example, is used as the core material for the boosting inductor L6 and the current limiting inductors L5 and L7 so as to be more suitable for thinning. A thin and long ferrite core with a winding formed is used, and the inductors are juxtaposed so as to extend in the longitudinal direction of the lamp LT.

As a result, the entire ballast can be designed to be extremely thin. For example, in the case of an output power capacity of 40 W class, a ballast having a finished ballast thickness (thickness T of the case outer shape) of about 7 mm can be realized. Was.

As shown in FIG. 3C or 3D, the flat film capacitor is provided vertically so that the width direction y of the flat film capacitor is parallel to the thickness direction of the housing. As shown in (E) or (F), the flat film capacitor may be provided vertically so that the longitudinal direction of the flat film capacitor is the thickness direction of the housing.

In the case of the vertical arrangement as shown in FIGS. 3 (C) to 3 (F), the length or width of the film capacitor limits the height of the ballast. Becomes difficult.

In the above embodiment, the dividing capacitor C33
Although the smoothing capacitor is configured using a plurality of film capacitors a to C33n, the present invention is not limited to the film capacitor, and the smoothing capacitor is configured using a plurality of electrolytic capacitors (generally a columnar shape). You can also.

Also in this case, as shown in FIG. 4 (A) or (B), the longitudinal direction, the width direction, and the thickness direction (however, the length in the longitudinal direction) of the lighting fixture housing using the lamp LT are used. > Length in the width direction> Length in the thickness direction), so that the radial direction d of the cylindrical electrolytic capacitor is parallel to the thickness direction of the housing, and the longitudinal direction h or It is provided horizontally so that the radial direction d is arranged along the longitudinal direction of the lamp LT. This makes it possible to construct a small and thin ballast as a whole, though it is thicker than when a film capacitor is used.

As shown in FIG. 4 (C), the electrolytic capacitor may be provided vertically so that the longitudinal direction h of the electrolytic capacitor is the thickness direction of the housing. In this case, the length h of the electrolytic capacitor
However, since the height of the ballast is restricted, it is more difficult to reduce the thickness of the ballast.

In the above embodiment, the four diodes D1 to D4 bridge-connected for full-wave rectification are used as the rectifier DB. However, the rectifier DB shown in FIG.
Both of the diodes D3 and D4 can be eliminated. At this time, the circuit constants, starting characteristics, or waveforms of each part of the ballast are different due to the omission of D3 and D4.
It is necessary to readjust the inductance, that is, the number of turns of the inductor or the number of series connections.

When connecting the boosting inductor L6 between the neutral point B and the connection point SW of the FET, it is necessary to connect the booster inductor L6 shown in FIG.
As shown in (1), a configuration may be adopted in which connection is made via a capacitor C12. In this case, by adjusting the combination of the additional capacitor C12 and the step-up inductor L6, a circuit member for 100V without the additional capacitor C12 (in a state where the portion is short-circuited) as shown in FIG.
A ballast corresponding to an input voltage of 100 V or more, such as a 220 V to 240 V power supply system, can be provided.

The inverter type ballast according to the above-described embodiment has a configuration in which power is supplied to the lamp without passing through a leakage transformer. However, the present invention is not limited to this. Various modifications are possible, such as through a leakage transformer or through an autotransformer. This will be briefly described below.

In the first example, in the above-described neutral point inverter type ballast, the connection between the lamp and the current limiting inductor is different from the original neutral point type configuration. The capacitor No. 3 is composed of a plurality of split capacitors electrically connected in parallel, and the plurality of split capacitors are provided so as to be arranged in the longitudinal direction of the discharge tube.

That is, the inverter type ballast of the first example is an inverter type ballast for supplying high-frequency AC power to a discharge tube, and includes a rectifier for rectifying an input AC voltage, and a DC voltage of the rectifier. The first connected in parallel with the output
And a series circuit of a second capacitor, a third capacitor for smoothing the DC output of the rectifier, a series circuit of first and second switching elements connected in parallel to the DC output of the rectifier, A first and a second diode connected in parallel to the first and the second switching elements so as to be in opposite directions in the direct current direction, and a drive circuit for alternately turning on and off the first and the second switching elements, respectively. , One end of an AC input of the rectifier and the first
And a boost inductor connected between a connection point of the second switching element and a neutral point which is a connection point between the first and second capacitors and one end of an AC input of the rectifier. An inverter-type ballast connected, wherein the discharge tube is arranged between a DC output of the rectifier (either positive or negative; hereinafter the same in the first example) and a connection point of the first and second switching elements. , Wherein the third capacitor is constituted by a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are provided so as to be arranged in a longitudinal direction of the discharge tube. It is.

Specifically, the neutral point B and the SW shown in FIG.
As shown in FIG. 6, a lamp load circuit RT including a ramp LT between points and a current limiting inductor L6 is connected between the SW point and DC− via the primary winding NP of the drive transformer T2. is there. You may connect to DC + instead of DC-. However, the circuit constants of the components (not limited to the current limiting inductor L6) need to be significantly changed from those of the above-described embodiment.

In the second example, a smoothing capacitor is used in a configuration in which one of a DC output of a rectifier and a voltage dividing capacitor connected in parallel with a smoothing capacitor is removed. And a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are provided so as to be arranged in the longitudinal direction of the discharge tube.

That is, the inverter type ballast of the second example is an inverter type ballast for supplying high-frequency AC power to the discharge tube, and includes a rectifier for rectifying an input AC voltage, and a DC of the rectifier. A smoothing capacitor for smoothing the output, a series circuit of first and second switching elements connected in parallel with the smoothing capacitor, and a first and a second switching element so that the DC and the switching are in opposite directions. First and second diodes connected in parallel;
A drive circuit for alternately turning on and off the first and second switching elements, and a booster connected between one end of two AC inputs of the rectifier and a connection point of the first and second switching elements. And a midpoint capacitor connected to at least one of the switching elements via the boosting inductor, and a connection point between the midpoint capacitor and the boosting inductor is connected to one end of an AC input of the rectifier. In the inverter type ballast connected with the booster inductor and the discharge tube is arranged in parallel with the step-up inductor, the third capacitor is constituted by a plurality of split capacitors electrically connected in parallel, and the plurality of split capacitors are electrically connected in parallel. The capacitor is provided so as to be arranged along the longitudinal direction of the discharge tube.

More specifically, one of the capacitors C4 and C5 that can be connected to the neutral point A may be omitted (see the configuration in which C4 is removed shown in FIG. 7). However, the fine adjustment of the oscillation frequency can provide the same input electric characteristics and lamp output as those of the neutral point type ballast shown in FIG. 1 using both the capacitors C4 and C5. In this case, however, the remaining capacitor capacity of C4 or C5 needs to be twice as large as when both are used.

The third example is an inverter type ballast that does not have a voltage dividing capacitor, such as the AC reactor insertion method, the partial smoothing method, the active smoothing filter method, and the dither rectification method described above.
Is composed of a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are provided so as to be arranged along the longitudinal direction of the discharge tube.

That is, the inverter type ballast of the third example is an inverter type ballast for supplying high-frequency AC power to the discharge tube, and includes a rectifier for rectifying an input AC voltage, and a DC voltage of the rectifier. A smoothing capacitor for smoothing the output, a series circuit of first and second switching elements connected in parallel to the DC output of the rectifier, and a DC reverse direction to the first and second switching elements, respectively. First and second diodes connected in parallel as described above, a drive circuit for alternately turning on and off the first and second switching elements respectively, one end of an AC input of the rectifier, and the first and second diodes. A boost inductor connected between the connection point of the switching element and
In the inverter type ballast in which the discharge tube is arranged in parallel with the boost inductor, the third capacitor is constituted by a plurality of divided capacitors electrically connected in parallel, and the plurality of divided capacitors are discharged by the discharge capacitor. It is characterized by being provided along the longitudinal direction of the pipe.

The above-described inverter type ballast includes a discharge tube in a load circuit and supplies high-frequency AC power to the discharge tube. A third capacitor as a smoothing capacitor is electrically connected in parallel. And a method of providing the plurality of divided capacitors so as to be arranged along the longitudinal direction of the discharge tube.
The present invention can be applied to any inverter device that supplies high-frequency AC power to something other than the discharge tube.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of an embodiment of an inverter type ballast according to the present invention.

FIG. 2 is a view showing a state in which the inverter type ballast of the present invention is mounted on a lighting fixture housing, and is a perspective view (a), an assembly view (b), and a sectional view (c).

FIG. 3 is a diagram showing an arrangement method of each film capacitor when a plurality of film capacitors are used as a smoothing capacitor.

FIG. 4 is a diagram showing an arrangement method of each electrolytic capacitor when a plurality of electrolytic capacitors are used as a smoothing capacitor.

FIG. 5 is a circuit diagram showing an example of another circuit configuration (capacitor series connection).

FIG. 6 is a circuit diagram showing an example of another circuit configuration (first example);
Example)

FIG. 7 is a circuit diagram showing an example of another circuit configuration (second circuit configuration);
Example)

[Explanation of symbols]

 Reference Signs List 1 inverter type ballast DB rectifier C4 voltage dividing capacitor (first capacitor) C5 voltage dividing capacitor (second capacitor) C33 smoothing capacitor (third capacitor) C33a to C33n dividing capacitor L5 current limiting inductor L6 boosting inductor L7 Current-limiting inductor Q5 FET (first switching element) Q7 FET (first switching element) DR drive circuit T2 drive transformer LT lamp (discharge tube) LPF noise filter

Claims (3)

[Claims] An inverter type ballast for supplying high-frequency AC power to a discharge tube, comprising: a rectifier for rectifying an input AC voltage; and a first and a second rectifier connected in parallel to a DC output of the rectifier. A series circuit of two capacitors, a third capacitor for smoothing the DC output of the rectifier, a series circuit of first and second switching elements connected in parallel to the DC output of the rectifier; A first and a second diode connected in parallel to the second switching element so as to be in the opposite direction in direct current, a drive circuit for alternately turning on and off the first and the second switching element, respectively, A boost inductor connected between one end of an AC input of the rectifier and a connection point of the first and second switching elements, wherein one end of the AC input of the rectifier is An inverter-type ballast in which a neutral point which is a connection point of the first and second capacitors is connected, and the discharge tube is arranged in parallel with the boosting inductor, wherein the third capacitor is electrically connected. An inverter-type ballast comprising a plurality of divided capacitors connected in parallel, wherein the plurality of divided capacitors are arranged along the longitudinal direction of the discharge tube. 2. The inverter type ballast according to claim 1, wherein each of said plurality of divided capacitors is provided such that a longitudinal direction of said divided capacitors extends in a longitudinal direction of said discharge tube. 3. The inverter-type ballast according to claim 1, wherein each of the plurality of split capacitors is a film capacitor.