JP2000209873A - Power supply, discharge lamp lighting unit and illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting unit in which harmonics of input current are reduced through simple circuitry. SOLUTION: A transistor Q1 is turned on/off to apply an AC high frequency voltage to a fluorescent lamp FL thus lighting the lamp. A third capacitor C4 is charged when the transistor Q1 is turned on. The third capacitor C and an inductor L2 are oscillated by turning the transistor Q1 on/off and harmonics are suppressed by overlapping the high frequency at a lower part of the envelope of a rectified pulsating voltage from a full-wave rectifier 12. At a part of AC commercial power supply e where the instantaneous voltage is low, a current flows through the third capacitor C4, a parallel resonance circuit 17, a choke coil L4, the fluorescent lamp FL, a second capacitor C3, the full- wave rectifier 12, a first diode D1, the inductor L2 and the third capacitor C4 when the second and third capacitors C3, C4 are discharged and the transistor Q1 is turned off. Consequently, the input voltage is made continuous and harmonics are suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply, a discharge lamp lighting device, and a lighting device in which harmonics of an input current are reduced.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device of this type, for example, a configuration described in Japanese Patent Application Laid-Open No. 10-92595 is known. Japanese Patent Application Laid-Open No. Hei 10-93595 describes a configuration in which a step-up chopper type active filter for preventing input harmonics is connected to a commercial AC power supply, and an inverter circuit is connected to the active filter.

[0003]

However, in the configuration described in Japanese Patent Application Laid-Open No. Hei 10-93595, since the active filter and the inverter circuit are connected,
There is a problem that the circuit configuration becomes complicated.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a power supply device, a discharge lamp lighting device, and a lighting device in which harmonics of an input current are reduced with a simple circuit configuration.

[0005]

According to a first aspect of the present invention, there is provided a power supply device comprising: a first capacitor connected to an AC power supply;
A rectifier circuit having input terminals connected to both ends of the series circuit of the first capacitor and the second capacitor; a third capacitor and an inductor connected between output terminals of the rectifier circuit And a series circuit of a first diode connected with a polarity to discharge the third capacitor; a resonance circuit connected between output terminals of the rectifier circuit; a first capacitor and a second capacitor connected to the resonance circuit and connected to the resonance circuit. A switching element for connecting a load circuit connected to a connection point of the capacitor; and a polarity connected between the third capacitor side of the first diode and the switching element and for charging the third capacitor when the switching element is turned on. And a second diode connected thereto. In a portion where the absolute value of the voltage of the AC power supply is low, the second capacitor and the second capacitor are connected. Since the capacitor 3 discharges from the capacitor and the second capacitor discharges to the load circuit, the discontinuous portion of the output voltage of the rectifier circuit is eliminated, the harmonic component of the input current is reduced, and the switching element is switched. Supply power to the load circuit.

According to a second aspect of the present invention, there is provided the power supply device according to the first aspect, wherein the filter includes an inductor and a capacitor connected between the commercial AC power supply and a series circuit of the first capacitor and the second capacitor. And harmonics are also reduced by a filter.

A discharge lamp lighting device according to a third aspect includes the power supply device according to the first or second aspect, and a load circuit having a discharge lamp, and has respective functions.

A lighting device according to a fourth aspect of the present invention includes the discharge lamp lighting device according to the third aspect and a fixture main body to which the discharge lamp lighting device is attached, and has respective functions.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illumination device according to an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the lighting device 1 has a reflecting surface 3 on the lower surface of the fixture body 2, and lamp sockets 4 and 4 are attached to both ends of the reflecting surface 3 in the longitudinal direction. A fluorescent lamp FL serving as a discharge lamp is mounted between the sockets 4 and 4, and a discharge lamp lighting device 5 serving as a power supply device is housed inside the fixture body 2.

As shown in FIG. 1, the discharge lamp lighting device 5 has a filter 11 connected to a commercial AC power source e.
This filter 11 has a capacitor C1 and a common mode choke L1.

Further, a series circuit of a first capacitor C2 and a second capacitor C3 is connected to the filter 11, and the first capacitor C2 and the second capacitor C3 are connected.
The input terminal of the full-wave rectifier 12 composed of a diode bridge as a rectifier circuit is connected to the series circuit of C3.

An oscillation circuit 15 is connected to an output terminal of the full-wave rectifier 12. This oscillation circuit 15 is connected to a series circuit of a third capacitor C4, an inductor L2, and a first diode D1 having a polarity for discharging the third capacitor C4.

Further, an output terminal of the full-wave rectifier 12 is connected to an inverter circuit 16. This inverter circuit
16 is a capacitor C5 for resonance and an inductor for resonance
A parallel resonance circuit 17 in which L3 is connected in parallel, and a collector and an emitter of a transistor Q1 as a switching element connected in series to the parallel resonance circuit 17 are connected in series. Also, the inductor L2 and the first diode D1
A second diode D2 having a polarity for charging the third capacitor C4 when the transistor Q1 is turned on is connected between the connection point of the third resonance circuit 17 and the connection point of the parallel resonance circuit 17 and the transistor Q1. Note that a control circuit (not shown) is connected to the base of the transistor Q1.

One end of each of the filaments FL1 and FL2 of the fluorescent lamp FL is connected between the collector and the emitter of the transistor Q1 via a choke coil L4 and a DC cut capacitor C6 constituting a load circuit 18. A starting capacitor C7 is connected between the other ends of the filaments FL1 and FL2.

Further, a capacitor C6 and a filament
A connection point between the first capacitor C2 and the second capacitor C3 is connected between one ends of FL2.

Next, the operation of the above embodiment will be described.

The voltage of the commercial AC power supply e is suppressed by a filter 11 to suppress harmonics, and is subjected to full-wave rectification by a full-wave rectifier 12,
Q1 is turned on and off, and a high-frequency alternating current is applied to the fluorescent lamp FL to turn on the high-frequency light. When the transistor Q1 is on, the third capacitor C4 is charged. Further, the third capacitor C4 and the inductor L2 are oscillated by turning on and off the transistor Q1, and a high frequency is superimposed on a low portion of the envelope curve of the pulsating voltage rectified by the full-wave rectifier 12, thereby suppressing harmonics. .

Further, as shown in FIG. 3, when the instantaneous voltage of the commercial AC power supply e is low, when the second capacitor C4 and the third capacitor C4 are discharged and the transistor Q1 is off, Third capacitor C4, parallel resonance circuit 1
7, choke coil L4, fluorescent lamp FL, second capacitor C3, full-wave rectifier 12, first diode D1, inductor
The current flows through the path of L2 and the third capacitor C4, and the input voltage is continuously reduced to suppress harmonics. When the power is turned on, the first capacitor C2 and the second capacitor C3,
Since the filament FL2 of the fluorescent lamp FL and the capacitor C6 are connected, an inrush current is prevented.

[0020]

According to the first aspect of the present invention, in the portion where the absolute value of the voltage of the AC power supply is low, the second capacitor and the third capacitor discharge, and the second capacitor discharges to the load circuit. Therefore, the discontinuous portion of the output voltage of the rectifier circuit is eliminated, the harmonic component of the input current is reduced, and power can be supplied to the load circuit by switching the switching element.

According to a second aspect of the present invention, the power supply apparatus further comprises an inductor and a capacitor connected between the commercial AC power supply and a series circuit of the first capacitor and the second capacitor. Since a filter is provided, harmonics can be reduced by the filter.

A discharge lamp lighting device according to claim 3,
Since the power supply device according to claim 1 or 2 and the load circuit having the discharge lamp are provided, respective effects can be obtained.

In the lighting device according to the fourth aspect, since the lighting apparatus according to the third aspect includes the fixture body to which the lighting device for the discharge lamp according to the third aspect is attached, the respective effects can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing an appearance of the lighting device.

FIG. 3 is a waveform chart showing the same operation. (A) Full-wave rectifier voltage (b) Input current

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination device 2 Appliance body 5 Discharge lamp lighting device which is a power supply device 11 Filter 12 Full-wave rectifier as a rectifier circuit 17 Parallel resonance circuit 18 Load circuit C2 1st capacitor C3 2nd capacitor C4 3rd capacitor D1 1st Diode D2 second diode e commercial AC power supply FL fluorescent lamp as discharge lamp L2 inductor Q1 transistor as switching element

Claims (4)

[Claims] 1. A series circuit of a first capacitor and a second capacitor connected to an AC power supply; and a rectifier circuit having input terminals connected to both ends of the series circuit of the first capacitor and the second capacitor. A series circuit of a third diode connected between the output terminals of the rectifier circuit, an inductor, and a first diode connected with a polarity at which the third capacitor discharges; A resonance circuit; a switching element connected to the resonance circuit and connecting a load circuit connected to a connection point between the first capacitor and the second capacitor; and between the third capacitor side of the first diode and the switching element. A second diode connected with a polarity to charge the third capacitor when the switching element is turned on;
A power supply device comprising: 2. The power supply device according to claim 1, further comprising a filter having an inductor and a capacitor connected between the commercial AC power supply and a series circuit of the first capacitor and the second capacitor. 3. A discharge lamp lighting device comprising: the power supply device according to claim 1; and a load circuit having a discharge lamp. 4. A lighting device comprising: the discharge lamp lighting device according to claim 3; and a fixture main body to which the discharge lamp lighting device is attached.