JPH03117372A - Power supply - Google Patents

Abstract

PURPOSE:To save power consumption after start of operation by closing a starting resistor, connected in series with the gate of a switching transistor in a transistor inverter circuit, by means of a switching element upon start of the inverter. CONSTITUTION:Power from an AC power source 11 is rectified through a rectifying circuit 12 to produce a DC voltage which is then applied onto a series circuit of a smoothing circuit 13 and an impedance element 14. At the same time, power is fed to a load, i.e., a transistor inverter circuit 21, and a fluorescent lamp 24 is connected, for example, to the circuit 21. At the time of starting, a switching element 23 is opened and a high voltage, divided by the impedance element 14, is applied through a starting resistor 22 onto the gate of a switching transistor 20 thus starting oscillation. Upon elapse of predetermined time, the switching element 23 is closed with the fluorescent lamp 24 being lighted thus lowering the level of power to be fed to the starting resistor 22. By such arrangement, power consumption can be saved after starting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power supply device used, for example, in a discharge lamp lighting device.

(Prior Art) Conventionally, a configuration shown in FIG. 3, for example, is known as this type of power supply device.

The power supply device shown in FIG. 3 includes an AC power source 1 and a rectifier circuit 2.
A series circuit of a smoothing circuit 3 and an impedance element 4 is connected to the rectifier circuit 2, and a switching element 5 is connected in parallel to the impedance element 4. Further, an inverter circuit 6 having a transistor is connected to the rectifier circuit 2, and a starting resistor 7 is connected to the transistor of the inverter circuit 6. A discharge lamp 8 is connected to this inverter circuit 6.

Further, as another conventional configuration, the configuration shown in FIG. 4 is known.

The configuration shown in FIG. 4 has a capacitor 11 in the rectifier circuit 2.
Connect a series circuit of diode 12 and capacitor 1
! and the connection point of the diode 12 to the inverter circuit 6
It is connected to.

(Problem to be Solved by the Invention) However, in the case of the configuration shown in FIG. 3 or 4 described above, the voltage across the rectifier circuit 2 is always applied to the starting resistor 7 for supplying current at startup However, there is a problem in that the power loss caused by the starting resistor 7 is very large.

The present invention was made in view of the above problems, and an object of the present invention is to provide a power supply device that reduces power loss due to starting resistance without increasing the number of parts.

[Structure of the invention]

(Means for Solving the Problems) A power supply device of the present invention includes a rectifier circuit connected to an AC power source, a smoothing circuit provided on the output side of the rectifier circuit and having a capacitor, and the capacitor in the smoothing circuit. and an impedance element for inrush current reduction connected between the negative electrodes of the rectifier circuit, a switching element connected in parallel to the impedance element, and a switching transistor supplied with the outputs of the rectifier circuit and the smoothing circuit. The device includes a transistor inverter circuit, a starting resistor connected between a connection point between the capacitor and the impedance element, and a base of the switching transistor of the transistor inverter circuit.

(Function) According to the present invention, when the switching element is off, a high voltage is generated in the impedance element, and sufficient power is supplied to the starting resistor. When the switching element is turned on, the impedance element is short-circuited, so the power supplied to the starting resistor is reduced, and the power loss due to the starting resistor is reduced.

(Example) Hereinafter, a power supply device according to an example of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a commercial AC power source, to which the AC input end of a rectifier circuit 12 is connected, and to the output end of the rectifier circuit 12, a smoothing circuit 13 such as a Schottney circuit, An impedance element 14 for reducing inrush current, such as a resistor or an inductor, is connected in series. The smoothing circuit 13 includes a first capacitor 1 between the positive output terminal of the rectifier circuit 12 and the impedance element 14.
5, a diode 16 and a second capacitor 17 that is the same as the first capacitor 15 are connected, and the rectifier circuit 12
A diode 18 is connected between the positive output terminal of the rectifier circuit 12 and the connection point between the diode 16 and the capacitor 17, and the diode 18 is connected in a forward direction toward the positive output terminal of the rectifier circuit 12.
A capacitor 15 and a diode 1 are connected between the connection point of the rectifier circuit 12 and the negative output terminal of the rectifier circuit 12.
A diode 19 is connected in the forward direction toward the connection point No. 6.

Further, the input terminal of a transistor inverter circuit 21 that performs oscillation by the switching transistor 20 is connected between the output terminals of the rectifier circuit 12. The base of the switching transistor 20 is connected to a connection point between the capacitor 17 and the impedance element 14 via a starting resistor 22, and a switching element 23 is connected in parallel to the impedance element 14.

Further, a discharge lamp 24 such as a fluorescent lamp is connected to the output end of the transistor inverter circuit 21.

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

First, the AC from the commercial AC power supply 11 is rectified by the rectifier circuit 12, partially smoothed by the smoothing circuit 13, power is supplied to the transistor inverter circuit 21, and the discharge lamp 24 is turned on. Note that during smoothing, valley filling smoothing is performed by discharging the capacitor 17 via the capacitor 15 and diode I8.

Further, at the time of starting, the switching element 23 is turned off, a high partial voltage is generated in the impedance element 14, and a current is applied to the base of the switching transistor 2o via the starting resistor 22 to start oscillation. Thereafter, after a predetermined period of time has elapsed, the switching element 23 is turned on, the impedance element 14 is short-circuited, the voltage is reduced, and the power supplied to the starting resistor 21 is reduced.

Note that after the switching element 23 is turned on, the voltage of the impedance element 14 decreases as shown in FIG. 4.

The switching element 23 may be a timer that measures time from the start, a device that responds to the heat generation of components due to energization, or, in the case of a lighting device, a device that is turned on after a predetermined time by detecting the lamp current or light output. It is.

Further, the smoothing circuit 13 is not limited to a Schottney circuit, and may be a capacitor-only one or another smoothing circuit.

According to the above-mentioned embodiment, since the number of parts is not increased from the originally required parts, it is possible to save space and construct a compact design.

〔Effect of the invention〕

According to the present invention, by turning on and off the switching element, the voltage of the impedance element changes, and the power supplied to the starting resistor can be changed according to this voltage. Power loss due to starting resistance can be reduced when power is not required. Furthermore, since there is no increase in parts, the structure can be constructed at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the power supply device of the present invention, FIG. 2 is a voltage waveform diagram of the same impedance element, and FIGS. 3 and 4 are circuit diagrams showing conventional examples. 11... AC power supply, I2... Rectifier circuit, 13... Smoothing circuit, 14... Impedance element, 17... Capacitor, 20... Switching transistor, 2-transistor inverter circuit, 22... Starting resistor, 23 ...Switching element. ([Jshi

Claims (1)

[Claims] (1) A rectifier circuit connected to an AC power source, a smoothing circuit provided on the output side of this rectifier circuit and having a capacitor, and an inrush circuit connected between the capacitor in this smoothing circuit and the negative electrode of the rectifier circuit. an impedance element for current reduction; a switching element connected in parallel to the impedance element; a transistor inverter circuit that is supplied with the outputs of the rectifier circuit and the smoothing circuit and has a switching transistor; and a connection between the capacitor and the impedance element. and a starting resistor connected between a base of the switching transistor of the transistor inverter circuit and a base of the switching transistor of the transistor inverter circuit.