CN2128817Y

CN2128817Y - Fluorescent lamp electronic ballast

Info

Publication number: CN2128817Y
Application number: CN 92210939
Authority: CN
Inventors: 刘寿生
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-05-16
Filing date: 1992-05-16
Publication date: 1993-03-24
Anticipated expiration: 2002-05-16

Abstract

The utility model relates to a fluorescent lamp electronic ballast which comprises a rectifying filter circuit, an oscillating circuit and a load starting circuit. The utility model is characterized in that the oscillating circuit is an asymmetric push-pull oscillating circuit and the oscillating tube is provided with a base bias circuit. The electronic ballast overcomes the disadvantages of starting difficulty, easily produced malfunction when starting, difficulty in arrangement of a protection circuit, etc. existing in the prior art. The utility model has the advantages of simple structure, reasonable design, wide range of element parameter selection, high working reliability and low cost. Simultaneously, the circuit has load breaking protection and can be provided with over temperature and overload protection circuits conveniently for protecting various abnormal states reliably.

Description

Fluorescent lamp electronic ballast

The utility model relates to electronic ballast for fluoresent lamp.

Electric ballast comprises current rectifying and wave filtering circuit, oscillating circuit and load starting circuit, its typical circuit has two kinds, as Fig. 1, shown in Figure 2, all include two push-pull oscillator triodes in the oscillating circuit and reach the same circuits that constitutes the base loop of oscillating tube by two reverse subgrade coils of pulse transformer, the quiescent point of different is one (Fig. 1) two oscillating tubes is located at cut-off region, the cross-over connection of sawtooth waveforms circuits for triggering is in both ends of power, its triggering one seals in the diac of push-pull oscillator pipe base stage, make the work of circuit starter, its weak point is to start difficulty, does not possess excess temperature, overload and disconnected carrying are protected; Another (Fig. 2) is respectively two oscillating tubes by two groups of biasing circuits base bias current is provided, and makes the quiescent point of oscillating tube be located at the amplification region.Its deficiency is except that not possessing excess temperature, overload protection; also may be in power initiation moment; misoperation makes the conducting in advance of the oscillating tube of the first half; cause second oscillating tube not start; influence entire circuit work, particularly because the oscillating circuit of these two kinds of electric ballasts is symmetrical push-pull configuration, so require in full accord in the selection of generator triode parameter; otherwise can cause managing power consumption difference because of the junction resistance difference, the bigger oscillating tube of power consumption is burnt because of overheated.

From the above; these two kinds of typical circuits all do not possess sufficient abnormal condition protection; can under abnormality, protect automatically for making electric ballast; prior art has been added various control circuits; but because the restriction of symmetry of oscillating circuit own and triggering element function; not only inconvenience is provided with, and is difficult to reach ideal control effect.A kind of electric ballast that has overcurrent protection is disclosed as CN91200113; by increasing by one group of overcurrent sampling subgrade coil on the pulse transformer; obtain sampled signal and be connected on the trigger control circuit input; the protection entire circuit; its coil-induced very big over-current signal trigger control circuit of sampling; make second oscillating tube base stage short circuit ground connection; but other two groups of subgrade coils of pulse transformer on the same iron core have been disturbed; the former oscillating tube that has ended is vibrated again, so can not be accurately according to sampled signal control entire circuit.A kind of disconnected control type electric ballast that carries that has current cutting protection is and for example disclosed among the CN91211905, because there is symmetry in the oscillating circuit of this design, force one-way SCR control circuit cross-over connection both ends of power, by controlling conducting short-circuit protection entire circuit with the disconnected sampled signal of carrying of the sampling coil output of choke coupling; Because one-way SCR has been born whole supply voltages, controllable silicon is burnt in the moment puncture easily, does not have protective effect, and just existing in addition supplementary protection circuit is also also imperfect itself.

The purpose of this utility model provides an electric ballast, and dependable performance is provided, the electric ballast of band abnormal condition protection.

The utility model comprises current rectifying and wave filtering circuit, oscillating circuit and load starting circuit, and technical solution is in the push-pull oscillator circuit that the input pulse transformer is arranged, triode BG ₂Be provided with the working point base bias circuit, make two triode BG ₁, BG ₂Quiescent point be located at cut-off region and amplification region respectively, constitute asymmetric push-pull oscillator circuit.Temperature control circuit and over-current control circuit were set on this basis.The excess temperature sample circuit is the resistor voltage divider circuit of cross-over connection both ends of power, by dividing potential drop node output sampled signal; The overload sample circuit is to sample the output overcurrent sampled signal with the sampling coil coupling of choke coupling; Two sampled signals insert trigger control circuit, and trigger protection reaches the purpose of avoiding abnormal conditions to damage circuit,

Embodiment of the present utility model describes in detail by the following drawings:

Fig. 1, Fig. 2 are the typical circuit figure of existing electric ballast,

Fig. 3, Fig. 4, Fig. 5 are the utility model circuit diagram, and wherein Fig. 3 is a basic circuit diagram, and Fig. 4, Fig. 5 are at Fig. 3 supplementary protection circuit diagram.

Electric ballast of the present utility model comprises current rectifying and wave filtering circuit, oscillating circuit and load starting circuit constitute, wherein oscillating circuit is made up of two series connection push-pull oscillator pipes and pulse transformer two reverse subgrade coils, two subgrade coils is characterized in that oscillating tube BG as the base loop of push-pull oscillator pipe ₂Be provided with base bias circuit, make oscillating tube BG ₂Work in the amplification region, constitute asymmetric push-pull oscillator circuit.Because two oscillating tube working points are located at cut-off region and amplification region respectively,, enlarged the range of choice of oscillating tube so two pipe parameters need not to be consistent; The base stage of the amplification region of abnormal state protection circuit control simultaneously oscillating tube, sampling control signal makes oscillating tube BG ₁, BG ₂End simultaneously, therefore, can reliably control the protection entire circuit for additional abnormity protection circuit provides convenience.This electric ballast is in power connection moment, oscillating tube BG ₁Work in cut-off region, base bias circuit is oscillating tube BG ₂The base stage bias current is provided, makes it work in the amplification region, enter readiness for operation, can misoperation not influence entire circuit work.

The utility model oscillating tube BG ₂Base bias circuit be that cross-over connection is in oscillating tube BG ₂Resistance R between base stage and the positive source ₁₂Constitute.

The utility model oscillating tube BG ₂The base bias circuit most preferred embodiment be in positive source and oscillating tube BG by cross-over connection ₂Bleeder circuit R between the base stage ₁, R ₂Constitute R ₁Be connected in parallel on oscillating tube BG ₁The Ce utmost point, R ₂Be connected to BG ₁Emitter and oscillating tube BG ₂Between the base stage.R ₁, R ₂Be set to two oscillating tube BG ₁, BG ₂Energy element in the base loop provides the loop, damages oscillating tube BG when preventing disconnected carrying ₁, BG ₂

The utility model is protection generator triode BG ₁, BG ₂Emitter junction is not reversed voltage breakdown, respectively at two pipe emitter junctions backward diode D in parallel ₅, D ₆, make the reverse voltage forward be added on diode D ₅, D ₆Oscillating tube has been protected at two ends.Other two oscillating tube BG ₁, BG ₂Be in conducting, when changing, be tending towards making the coil negative feedback induction that is tending towards conducting oscillating tube base loop and quickening conducting by the transistor base loop power element discharging current diode of flowing through, be tending towards blanking tube and quicken to end D ₅D ₆The break-make speed that has improved two oscillating tubes is set, accelerated starting speed, prolong the oscillating tube life-span.

Be stable oscillation stationary vibration pipe base current, respectively series connection ballast resistance R in its base loop ₃, R ₄, guarantee two oscillating tube steady operations.

In the utility model load starting circuit, with starting capacitor C ₃Series connection carbon film insurance resistance R ₅When overload took place, big electric current was flowed through and is insured resistance R ₅, it is blown, the protection entire circuit; Its most preferred embodiment is that insurance resistance is 1/8W, Standard resistance range 10～30 Ω; For improving safety effect, resistance R ₅Last string is around being and R ₅Series connection also is wrapped in R ₅On, the number of turns is 2～6 circles, the metal fuse of φ 0.05～φ 0.15.

For further realizing abnormal protection, the utility model electric ballast is provided with the excess temperature sample circuit of cross-over connection both ends of power thermistor dividing potential drop.Overload sample circuit and the shared control triode BG of two sample circuits with the choke isolation coupling ₂The trigger control circuit of base stage, to the temperature rise of environment, oscillating tube and because of the electrical network bias voltage too high or abnormal conditions such as overload, overcurrent protected.

According to the above, the specific embodiment that the utility model provides such as Fig. 4, shown in Figure 5:

The excess temperature sample circuit is by thermistor Rt and R ₉Series connection constitutes.By dividing potential drop node A output excess temperature sampled signal, for obtaining stable DC voltage at thermistor pressure sampling circuit two ends, as prevent the voltage ripple of power network interference sample, by the interference filter capacitor C ₈Parallel voltage-stabilizing diode D ₁₀Constitute direct-flow voltage regulation source, be connected to divider resistance R between sys node B and the positive source ₁₀, thermistor Rt is a negative temperature coefficient resister, it is provided with card by oscillating tube BG ₁Or BG ₂, thermistor induced oscillation triode and environment temperature rise, resistance reduces, and dividing potential drop node A voltage is increased, and triggers control, the protection entire circuit.

The excess temperature sample circuit temperature rise signal of not only can sampling also can be sampled when power supply ripple voltage occurs, by dividing potential drop node A output ripple sampled signal, control triggering electric circuit protection entire circuit, for reaching this protection purpose, be provided with one with divider resistance R ₉Capacitor C in parallel ₇Constitute pulsation sampled signal time-delay holding circuit, make trigger control circuit that enough triggering control times be arranged, finish the pulsation protection.

The overload sample circuit is for isolating sampling coil L ₃₄With choke L ₁₂The inductive coupling signal is through rectifier diode D ₈Output one overload sampled signal control triggering electric circuit because during the overload burst, is smashed by external force suddenly during as lamp works or careless fluorescent tube one end when situation such as not contacting firmly and taking place, for avoiding the coil L that samples ₃₄Respond to the very triggering element of large-signal breakdown triggering control circuit, coupling coil output serial connection bleeder circuit R ₆, R ₇, sampled signal is adjusted to suitable triggering signal, by the dividing potential drop node through rectifier diode D ₈Output is stablized the ability of control triggering electric circuit, rectification circuit D for improving sampled signal simultaneously ₈Be connected to by R between output and the ground ₅, C ₈Time-delay holding circuit in parallel makes sampled signal keep a period of time, reliable control triggering electric circuit.

The trigger control circuit of present embodiment is made of two switching tubes, control oscillating tube BG ₂Base stage, two kinds of sample circuits are from the above mentioned exported sampled signal to trigger control circuit, start this trigger control circuit, make oscillating tube BG ₂Base stage short circuit ground connection is ended, and forces circuit to quit work, for making oscillating tube BG ₂Because of trigger control circuit control can reliably end, be connected in series a forward diode D at its emitter ₇, increase by a PN junction voltage, reach the purpose of protective circuit.

The switching tube of circuits for triggering of the present utility model is respectively an one-way SCR BTG and bidirectional trigger diode BD, and wherein bidirectional trigger diode BD one termination is gone into sampled signal, the other end be connected on oscillating tube BG ₂The control utmost point of the one-way SCR between base stage and the ground connects the interference attenuation capacitor C ₆Be connected between the control utmost point and the ground.When the sampled signal size reached the trigger voltage value of trigger tube BD, bidirectional trigger diode BD triggering and conducting made sampling trigger signal be passed to the control utmost point of one-way SCR BTG, triggers controllable silicon BTG conducting, causes oscillating tube BG ₂Base stage short circuit ground connection forces circuit to quit work, protective circuit.

For reducing circuit cost, make circuits for triggering reliably control entire circuit again and under abnormal conditions, in time quit work, Fig. 4 has showed another embodiment of circuits for triggering.Two switching tubes are respectively the switch triode BG of base stage, emitter short circuit ₅And base stage, the combination switch pipe BG of collector electrode crisscross parallel ₃BG ₄C ₆, C ₉Be combination switch pipe BG ₃, BG ₄The base stage capacitance, switching tube BG ₅Emitter be connected to BG in the combination switch pipe ₄Base stage, be stable switch pipe BG ₅Base current, base resistance R is set ₁₁Sample circuit is to switching tube BG ₅Collector electrode output sampled signal makes switching tube BG ₅Triggering and conducting makes sampled signal be passed to combination switch pipe BG ₄Base stage, oscillating tube BG then ₂Base stage is because of combination switch pipe BG ₃, BG ₄Triggering and conducting and short circuit ground connection is ended forces entire circuit to quit work, protective circuit.

Excess temperature sampled signal output line and overload sampled signal output line also connect output and are connected to trigger control circuit; for avoiding two sampled signal phase mutual interference; influence the protection effect of circuit, connecting on the output line therein makes the diode D of the unidirectional conducting of sampled signal ₉

The utility model is reasonable in design, and circuit is simple, and have the reliability height, start soon, the advantage that cost is low, not only circuit itself has protection in disconnected year but also excess temperature, overload protecting circuit can conveniently be set.

Claims

1, a kind of electronic ballast for fluoresent lamp, comprise that current rectifying and wave filtering circuit, oscillating circuit and load starting circuit constitute, oscillating circuit is made up of two reverse subgrade coils of two series connection push-pull oscillator pipes and pulse transformer, and two subgrade coils is characterized in that oscillating tube BG as the base loop of oscillating tube ₂Be provided with base bias circuit, make oscillating tube BG ₂Work in the amplification region, constitute asymmetric push-pull oscillator circuit.

2, electric ballast according to claim 1 is characterized in that by cross-over connection in positive source and oscillating tube BG ₂Resistance R between the base stage ₁₂Constitute BG ₂Base bias circuit.

3, electric ballast according to claim 1 is characterized in that by cross-over connection in positive source and oscillating tube BG ₂Resistor voltage divider circuit R between the base stage ₁, R ₂Constitute oscillating tube BG ₂Base bias circuit, R wherein ₁Be connected in parallel on oscillating tube BG ₁The Ce utmost point, R ₂Be connected to oscillating tube BG ₁Emitter and oscillating tube BG ₂Between the base stage, R ₁, R ₂Be set to oscillating tube BG ₁, BG ₂Energy element in the base loop provides the loop, damages oscillating tube BG when preventing disconnected carrying ₁, BG ₂

4, electric ballast according to claim 1 is characterized in that at oscillating tube BG ₁, BG ₂Emitter junction be parallel with backward diode D respectively ₅, D ₆, protection oscillating tube emitter junction is not reversed puncture, and quickens starter, prolongs the oscillating tube life-span.

5,, when it is characterized in that in starting circuit, being in series with overload it has been blown the resistance R of safety effect according to claim 1,4 described electric ballasts ₅

6, electric ballast according to claim 5 is characterized in that resistance R ₅Best value be 1/8 W, 10 Ω-30 Ω; For further improving its insurance ability, at R ₅Last string is wound with 2-6 circle, the metal fuse of φ 0.05～0.15.

7,, it is characterized in that being provided with the temperature-sensitive pressure sampling circuit of cross-over connection, with the overload sample circuit and the shared control oscillating tube BG of two sample circuits of choke coupling in both ends of power according to claim 1,4 described electric ballasts ₂The trigger control circuit of base stage, to the environment temperature rise, the oscillating tube temperature rise and because of the electrical network bias voltage abnormal conditions of too high or overload, overcurrent protected.

8, electric ballast according to claim 7 is characterized in that the temperature-sensitive pressure sampling circuit is by negative tempperature coefficient thermistor Rt, R ₉Constitute, Rt is provided with card by oscillating tube BG ₁/ BG ₂, by dividing potential drop node output excess temperature sampled signal; For obtaining stable DC voltage at temperature-sensitive pressure sampling circuit two ends, and connect by the interference filter capacitor C ₈Parallel voltage-stabilizing diode D ₁₀The direct-flow voltage regulation source that constitutes is connected to divider resistance R between sys node B and the positive source ₁₀

9, electric ballast according to claim 8 is characterized in that for utilizing excess temperature sample circuit Rt, R ₉Finish the power supply ripple protection, be provided with and divider resistance R ₉Capacitor C in parallel ₇The fluctuating signal time-delay holding circuit that constitutes.

10, electric ballast according to claim 7 is characterized in that transshipping sample circuit by sampling coil L ₃₄With choke L ₁₂Coupling constitutes induced signal through current rectifying and wave filtering circuit D ₈The output overloading sampled signal, control triggering electric circuit, when avoiding sampled signal excessive, the breakdown triggering element is at coupling coil L ₃₄Output is provided with the bleeder circuit R that is connected in series with it ₆, R ₇, adjust the size of sampled signal, by the dividing potential drop node through rectifier diode D ₈The output triggering signal; Stablize the ability of control triggering electric circuit for improving sampled signal simultaneously, at rectification circuit D ₈And be provided with C between the ground ₅, R ₈Time-delay holding circuit in parallel.

11, according to claim 7,8,9,10 described electric ballasts, it is characterized in that trigger control circuit is made of two switching tubes, i.e. sampled signal input triggers the first switching tube break-make, and the break-make control of this switching tube is connected to oscillating tube BG ₂Second switching tube break-make between base stage and the ground, BG during this switching tube conducting ₂Base stage short circuit ground connection is ended; At oscillating tube BG ₂Emitter is connected in series a forward diode D ₇, make its reliably by simultaneously for avoiding excess temperature, overload sampled signal to interfere with each other, the diode D of the unidirectional conducting of connecting on the output line therein ₉