CN2221286Y - Electronic ballast of fluorescent lamp - Google Patents

Abstract

The utility model relates to an electronic ballast for a daylight lamp, comprising a rectifier and filter circuit (1), a push-pull oscillation circuit (2) and an LC series resonance circuit (4). The utility model is characterized in that a buffer circuit (3) is added between the push-pull oscillation circuit (2) and the LC series resonance circuit (4). The additional circuit of the utility model is simple, has a reliable performance, is capable of effectively prolonging the life time of a lamp tube, causes the lamp tube to start more than 7000 times but not become black and is suitable for various daylight lamps.

Description

A kind of electronic ballast for fluorescent lamp

The utility model relates to a kind of electronic ballast for fluorescent lamp.

Common electric ballast, filament preheating circuit are all perfect inadequately, and its starter generally is cold starter, and starter moment is very big to the impact of fluorescent tube, and fluorescent tube easily turns black and the lost of life.In order to overcome this problem, it is pre-thermal element that PCT is adopted in the invention that has, the employing two starters series connection that has, but the two effect aspect energy-conservation and reduction resonance current is bad; A kind of fluorescent lamp ballast of Chinese patent application " 94224032.4 ", between rectification circuit and oscillating circuit, added a buffer circuit, the starting voltage of lamp tube ends is raise gradually and reduce impact, but the buffer circuit of this ballast is had relatively high expectations to the technical performance of control element, cost is increased, and damping characteristics is also not ideal enough.

The purpose of this utility model is to provide a kind of can effectively reduce oscillating current, the fluorescent lamp ballast in prolonging lamp tube useful life.

The utility model is realized its purpose as follows: ballast comprises current rectifying and wave filtering circuit 1, push-pull oscillator circuit 2 and LC series resonant circuit 4, has added a buffer circuit 3 between oscillating circuit 2 and series resonant circuit 4.Triode T in the buffer circuit 3 ₃Collector electrode be connected to triode T in the oscillating circuit 2 ₁Base stage, emitter meets the elementary winding N of feedback transformer ₁With secondary winding N ₂Common port, base stage is passed through resistance R ₇, capacitor C ₄And diode D ₇Be connected to elementary winding N ₁The other end, T ₃Emitter and diode D ₇Also be connected to capacitor C between negative pole ₅

Advantage of the present utility model is that circuit is simple, and cost is low, reduces oscillating current effectively and impacts, and prevents the fluorescent tube blackout, and prolonged the useful life of fluorescent lamp greatly.

Embodiment further specifies the utility model below in conjunction with accompanying drawing.

Fig. 1 is a circuit diagram of the present utility model.

Fig. 2 is a block diagram of the present utility model.

In the utility model ballast, the input of the buffer circuit of setting up 3 can join with the base stage of any in two triodes in the oscillating circuit 2, and its control element adopts triode (NPN or PNP) or low-power transistor module.

During work, the triode T in the oscillating circuit 2 ₁, T ₂Alternate conduction, end, produce high frequency voltage, the elementary winding N of feedback transformer B in lamp tube ends ₁On voltage through diode D ₇And capacitor C ₅Behind the rectifying and wave-filtering, pass through capacitor C ₄And resistance R ₇Give triode T ₃Provide base current to make its conducting, to triode T ₁Base current carry out shunting, triode T in the oscillating circuit ₁, T ₂The conducting degree thereby diminish, its output oscillation amplitude also diminishes, and makes the resonance electricity capacitor C in the LC resonant circuit 4 ₇On voltage do not reach the starter value, filament is in heated condition; T ₁The size of base bleeder current is with capacitor C ₄Charging process and descending, through 1～2 second, C ₄After charging finishes, triode T ₃Ended by the conducting change, shunting finishes, triode T ₁, T ₂Operate as normal, the output oscillation amplitude increases capacitor C ₇On voltage increase gradually, make tube starting after reaching starting voltage.

By said process, filament of fluorescent lamp obtains abundant preheating before starter, and its oscillating current is ascending, can not cause any impact.After tested, common fluorescent lamp ballast power factor is 0.6～0.8, and triple-frequency harmonics is about 40～70%, and the utility model power factor is 0.95, and triple-frequency harmonics only is 16%; Thereby with the fluorescent tube of common ballast in the promptly serious blackout of turning on light 1000～1500 times, and the utility model can reach more than 7000 times without any the blackout sign, makes lamp tube service life longer more than 4 times than the fluorescent tube that uses the ordinary electronic ballast.

Claims (2)

1. a fluorescent lamp ballast comprises current rectifying and wave filtering circuit (1), push-pull oscillator circuit (2) and LC series resonant circuit (4), it is characterized in that: added a buffer circuit (3) between oscillating circuit (2) and series resonant circuit (4).

2. fluorescent lamp ballast according to claim 1 is characterized in that: triode T in the buffer circuit (3) ₃Collector electrode be connected to triode T in the oscillating circuit (2) ₁Base stage, emitter meets the elementary winding N of feedback transformer ₁With secondary winding N ₂Common port, base stage is passed through resistance R ₇, capacitor C ₄And diode D ₇Be connected to elementary winding N ₁The other end, T ₃Emitter and diode D ₇Also be connected to capacitor C between negative pole ₅

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