CN2169274Y

CN2169274Y - Electronic flueorescent ballast capable of adjusting brightness

Info

Publication number: CN2169274Y
Application number: CN 93237140
Authority: CN
Inventors: 李守运
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-24
Filing date: 1993-06-24
Publication date: 1994-06-15
Anticipated expiration: 2003-06-24

Abstract

The utility model provides an electronic ballast capable of adjusting brightness for fluorescent lamps, which is composed of a bridge rectifier circuit, a filtering capacitor, chokes and a push-pull oscillator circuit. Because the chokes L< 1 >L< 2 > are connected with the bridge rectifier circuit and the push-pull oscillator circuit, a working circuit and an external circuit are isolated and the mutual interference of the working circuit and the external circuit is eliminated. Because a protection circuit composed of a capacitor, a resistor and a transformer coil which are connected in series is arranged between a base electrode and an emitting electrode of a transistor, the utility model can normally work in a wider voltage range. The brightness of a fluorescent lamp can be adjusted.

Description

Electronic flueorescent ballast capable of adjusting brightness

The utility model relates to a kind of electronic ballast for fluorescent lamp, particularly a kind of tunable optical electronic ballast for fluorescent lamp.

Existing electronic ballast for fluorescent lamp, generally be adopt by bridge rectifier the civil power of 220V is become about 300V direct voltage after, directly be added on the push-pull oscillator circuit of forming by two triodes and transformer, produce the high frequency alternating current, light fluorescent tube thereby filament heated by force.This ballast lacks warm, thereby is easier to damage fluorescent tube owing to be that filament is heated by force, and the high-frequency pulse current that its push-pull oscillator circuit produced simultaneously has harmful effect to electrical network; In addition, the operating voltage range that this electric ballast was suitable for is narrower, particularly under the situation of voltage lower (being lower than 100V).Just can not normal starting, phenomenons such as light flash perhaps appear, and when voltage was higher, transistor damaged easily.Therefore, use the fluorescent lamp of this electric ballast also can't regulate its brightness significantly by changing voltage.

The purpose of this utility model provides a kind of employing preheating soft start, and electrical network is not produced high-frequency impulse influence, the wide adjustable significantly electronic ballast for fluorescent lamp of lighting tube brightness that makes of operating voltage range.

Technical solution of the present utility model is as follows, is described in detail below in conjunction with accompanying drawing.

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

This electric ballast is by bridge rectifier, filter capacitor, choke coil and push-pull oscillator circuit consist of, two terminations of the bridge rectifier that D1～D4 forms are through the civil power of pressure regulation, two output parallel filtering capacitor C, the 1 rear choke coil L1 that connects respectively, the end of L2, the colelctor electrode of the direct connecting triode BG1 of the other end of L1, the emitter stage of the direct connecting triode BG2 of the other end of L2, the emitter stage of BG1 directly is connected with the colelctor electrode of BG2, parallel resistance R1 between the colelctor electrode of BG1 and base stage is behind the resistance R 2 reverse series diode D5 and by capacitor C 2, after being associated, the series circuit that resistance R 3 and transformer coil n1 form is parallel to again between the base stage and emitter stage of BG1; Similarly, parallel resistance R4 between the emitter stage of BG2 and base stage, behind the resistance R 5 reverse series diode D6 with by capacitor C 4, After being in parallel, the series circuit that resistance R 6 and transformer coil n2 form is parallel to again between the base stage and emitter stage of BG2; The colelctor electrode of BG1 connects the end of filament of fluorescent lamp A by capacitor C 5, the other end of filament A connects the end of filament of fluorescent lamp B by capacitor C 6, the other end of filament B meets the tie point of the colelctor electrode of BG1 emitter stage and BG2, shunt capacitance C3 between the collector and emitter of BG2 after by choke coil L3 series transformer coil n3.

Operation principle of the present utility model and process are as follows:

Civil power or the direct voltage process C1, the L1 that export by bridge rectifier through the civil power of pressure regulation, the filtering of L2 obtain direct voltage more stably, when the moment of power connection, BG1 and BG2 all are in cut-off state, and capacitor C 2, C3, C4, C5, C6 all are in charged state.Because the charging rate of C2 and C4 is difference to some extent, so BG1 and BG2 always have a first conducting, if the BG1 conducting, then to the C3 charging, the tie point voltage of the emitter of BG1 and the collector electrode of BG2 raises, and the C2 discharge makes the decline of BG1 base voltage end once more until BG1.At this moment, the C4 charging rate is accelerated and is saturated rapidly, makes BG2 upset conducting, then has electric current to pass through filament A, B like this on n3, the L3 and charges to C5, C6.Because R6 has controlled the C4 charging rate, has also just controlled BG2 conducting amount, therefore, the charging of C5, C6 has also been reached the effect of little current preheating filament.Again because the electric current of n3 increases, n1 on same magnet ring, n2 just produce mutual voltage, make BG1, BG2 base stage obtain the reverse voltage of 180 degree each other respectively, again circulation forms vibration, change in voltage because of n1, n2, make frequency of oscillation raise, the electric current that has strengthened n3, L3 simultaneously once more is raised to certain value until filament temperature, lights fluorescent tube.If the conducting of BG2 elder generation, its course of work and said process are similar.

The utility model has increased the antijamming capability of circuit owing to inserted choke L1, L2 between bridge circuit and high-frequency oscillating circuits, and HFS and external circuit are isolated, and has strengthened circuit stability; Because the access of C2, C4 makes initial oscillation intensity obtain desirable tracking, the preheating of filament is played significant effect, make the circuit also can normal starting under the lower situation of voltage.In addition, owing to be provided with the protective circuit of being made up of R2 and D5 and R5 and D6 respectively between the base stage of BG1, BG2 and emitter, feasible when voltage is higher, the base voltage of BG1, BG2 is unlikely too high and breakdown.Thereby guarantee the utility model can be in the voltage range of broad operate as normal, make fluorescent lamp brightness to regulate significantly.

Claims

1, a kind of tunable optical electronic ballast for fluorescent lamp, comprise bridge rectifier, filter capacitor, choke and push-pull oscillator circuit, two outputs that it is characterized in that bridge rectifier are connected by the collector electrode of the transistor BG1 in choke L1, L2 and the push-pull oscillator circuit, the emitter of BG2 respectively; Start-oscillation circuit that is composed in series by capacitor C 2, resistance R 3 and transformer coil n1 in parallel respectively and the protective circuit that is composed in series by resistance R 2 and diode D5 between the base stage of BG1 and emitter; Start-oscillation circuit that is composed in series that is composed in series by capacitor C 4, resistance R 6 and transformer coil n2 in parallel respectively and the protective circuit that is composed in series by resistance R 5 and diode D6 between the base stage of BG2 and emitter.