CN2157616Y

CN2157616Y - Demagnetisation protection arrangement for electronic ballast

Info

Publication number: CN2157616Y
Application number: CN 93210905
Authority: CN
Inventors: 罗初东; 劳定阶; 罗穗生
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-04-23
Filing date: 1993-04-23
Publication date: 1994-02-23
Anticipated expiration: 2003-04-23

Abstract

The utility model provides a demagnetization protection device of an electronic ballast, which comprises a bridge rectifier circuit, a start-up circuit, a switch oscillation circuit, a transformer feedback coupling circuit, an output circuit and a protection circuit. The electronic ballast is used for a fluorescent lamp with a straight pipe, a ring-shaped fluorescent lamp and an energy-saving lamp. The utility model is characterized in that the utility model utilizes the demagnetization principle to interrupt the coupling signal of the switch oscillation circuit. A switch pipe stops oscillating, which can protect the electronic ballast. Simultaneously the utility model can ideally supply protection for kinds of faults, such as the excess voltage, the overload, the open circuit, the short circuit, the overtemperature, etc. The service life of the electronic ballast can be effectively prolonged.

Description

Demagnetisation protection arrangement for electronic ballast

The utility model relates to electric ballast, particularly a kind of degaussing protective device of electric ballast.

Existing electric ballast has economize on electricity, saves steel, volume is little, in light weight and advantage such as easy for installation, just progressively replaces traditional appendiron core transformer.Electric ballast is the special-purpose assorted product that is used for fluorescent lamp and electricity-saving lamp, and it can directly be transformed to the high frequency voltage supply load that is higher than 20KHz to the line voltage of 50Hz.Therefore it is just progressively accepted by users.But, this product in use, often because voltage ripple of power network, reasons such as user's improper use or load variations, and cause abnormal conditions such as overvoltage, overload, short circuit, open circuit and overtemperature cause product badly damaged or burn.Because the spoilage height of this product, poor reliability is its main cause of promoting the use of of overslaugh.How to improve the reliability of electronic transformer, a great problem that the domestic and international in recent years just relevant personnel seek to solve.

The purpose of this utility model provides a kind of degaussing principle of utilizing and realizes protection to electric ballast, thus the degaussing protective device that electric ballast can not damaged because of situations such as overvoltage, overload, open circuit, short circuit and overtemperatures.

Technical solution of the present utility model is: electric ballast degaussing protective device comprises that bridge rectifier, start-up circuit, switch oscillating circuit, transformer feedback coupling circuit, output circuit, protective circuit form jointly.Its solution is: described protective circuit is made up of coil n4, the thyristor T3, diode D7-D9, the resistance R 6-R12 that are arranged on coupling magnet ring B1.The positive pole of the terminating diode D7 of the coil n4 of B1 wherein, the common port of another termination protective circuit.Resistance R 6 one termination power positive poles, the anode A of another termination T3, R7 is attempted by between the A and K of thyristor T3, and the positive pole of diode D8 connects the emitter of switch transistor T 2, the end of the negative pole connecting resistance R8 of D8, the control utmost point G end of another termination thyristor T3 of R8.Be connected across between thyristor G end and the common port after resistance R 9 and capacitor C 5 are in parallel, resistance R 11 and R12 series connection on DC power supply, the terminating resistor R11 of diode D9 and the point of contact of R12, the control G end of another termination thyristor.The common port of protective circuit joins through resistance R 10 and power cathode simultaneously.

The fault detection signal of protective circuit described in the utility model promptly can be obtained from the emitter resistance R3 of switch transistor T 2, obtains in the coil of some circles of coiling on the magnetic core of choke B2 that also can be in output circuit.Make one of coil terminate at the positive pole of diode D8, another termination common port.In addition, detection signal can also be obtained from resistance R 10, and with the positive pole of the diode D8 right-hand member from the emitter-base bandgap grading reconfiguration of switch transistor T 2 to resistance R 10, and the left end of R10 connects the protective circuit common port.

Degaussing coil n4 described in the utility model is wound on the couples back magnet ring B1, and wherein the high-frequency induction voltage of coil n4 is delivered on the resistance R 7 by halfwave rectifier or full-wave rectification or bridge rectifier.In addition, the main element of control short-circuited coil n4 short circuit can also adopt contact switch element such as miniature relay except adopting contactless element thyristor T3 or transistor.

The utility model has following advantage especially except the advantage with general electric ballast:

(1) adopt such scheme to make the utility model solve several error protections such as overvoltage, overload, open circuit, short circuit, overtemperature simultaneously in very good ground.And circuit structure is simple, dependable performance.

(2) when circuit is protected, switch oscillating circuit failure of oscillation is in the timeout state, and the electrical network input power drops to not enough 1W, and has memory function.Have only power cutoff, energized again after fixing a breakdown, entire circuit is just recovered operate as normal again.

(3) utilize the degaussing principle to make the switch oscillating circuit lose oscillating condition and break-off, so when protection, all elements did not generate heat, consumed power not even be in guard mode for a long time, can not damaged any element yet yet.

(4) aging, starter occurred not and flashed when fluorescent lamp usually, caused electric ballast to be in long-time series resonance state, often burnt because of electric current is very big.This circuit is effective to the protection characteristics of this situation, and the protection effect is obvious, provides guarantee to the life-span of guaranteeing electric ballast.

Below in conjunction with accompanying drawing the utility model is illustrated,

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

As shown in Figure 1; this electric ballast degaussing protective device; comprise bridge rectifier (diode D1-D4, capacitor C 1), start-up circuit (resistance R 1, capacitor C 2, diode D6), switch oscillating circuit (switch transistor T 1, T2, resistance R 2-R5); transformer feedback coupling circuit (coupling magnet ring B1 and coil n1-n3); output circuit (choke B2, capacitor C 3, C4), protective circuit (coil n4, diode D7-D9, resistance R 6-R11, the thyristor T3 of coupling magnet ring B1) is common to be constituted.

Its operation principle is: line voltage obtains about 300 volts of direct voltages through after the bridge rectifier filtering, when capacitor C 2 when resistance R 1 charges to the puncture voltage of diode D6, diode D6 conducting immediately, trigger switch pipe T2 conducting.This moment, sense of current was from positive source → capacitor C 3 → C4 → choke B2 → coil n1 → switch transistor T 2 → resistance R 3 → resistance R 10 → power cathode.Capacitor C 3, C4 charging at this moment, the filament heating.The ending of the same name of coil n2, n3 has guaranteed that switch transistor T 2 saturated T1 end in the accompanying drawing.Cause the polarity inversion of the induced voltage of magnetic ring coil n2, n3 owing to the sign modification of flux change rate, cause switch transistor T 2 saturated by, T1, this moment sense of current from capacitor C 3 upper ends → switch transistor T 1 → resistance R 2 → coil n1 → choke B2 → capacitor C 4 → capacitor C 3 lower ends, make C3, C4 discharge, energy is sent back to power supply, and filament continues heating.Switch transistor T 1, T2 so constantly replace saturated and end, and until choke B1 and capacitor C 4 series resonances take place, and produce a very high resonance potential on C4, and fluorescent lamp is punctured till the starter.Fluorescent lamp is in parallel with electric capacity 4 behind the starter, and resonance disappears, and fluorescent lamp is normally lighted.

The operation principle of protective circuit is: when circuit generation overvoltage, overload, short circuit, open circuit, the aging not starter of fluorescent tube; during any fault such as overtemperature; obtaining fault-signal voltage from resistance R 3 rises; by delivering to the control end G of thyristor T3 after diode D8 guiding and resistance R 8, the R9 dividing potential drop; 5 cushioning effects of capacitor C, T3 is conducting to a coil n4 short circuit immediately, produces a bigger short circuit ampere-turn after the coil n4 short circuit; make magnet ring B1 enter demagnetizing state, the flux change rate is minimum.So the feedback voltage on coil n2, the n3 disappears substantially, make switch transistor T 1, T2 failure of oscillation.Resistance R 6 obtained from DC power supply and kept electric current this moment, guaranteed the reliable conducting of thyristor T3, always hold-in winding n4 short circuit.Owing to be used in the coupled signal that the degaussing principle is come the interrupt switch oscillating circuit; make the switching tube failure of oscillations; caught the work essence of electric ballast to protect from principle; therefore; elements all during protection neither generate heat, and also consumed power not is even be in guard mode for a long time; can not damage any element yet, thereby guarantee the useful life of electric ballast.

Claims

1; a kind of electric ballast degaussing protective device; comprise bridge rectifier; start-up circuit; the switch oscillating circuit; the transformer feedback coupling circuit; output circuit; protective circuit constitutes; it is characterized in that: described protective circuit is by the coil n4 that is arranged on the coupling magnet ring B1; diode D7-D9; resistance R 6-R12; thyristor T3 forms; the positive pole of the terminating diode D7 of the coil n4 of B1 wherein; the common port of another termination protective circuit; resistance R 6 one termination power positive poles; the anode A of another termination thyristor T3; R7 is attempted by between the A and K of thyristor T3; the positive pole of diode D8 connects the emitter of switch transistor T 2; D8 negative pole connecting resistance R8 one end; the control G end of another termination thyristor T3 of R8; be connected across between thyristor G end and the common port after capacitor C 5 and resistance R 9 are in parallel; resistance R 11 and R12 series connection are on DC power supply; the point of contact of diode D9 one termination R11 and R12; the G end of another termination thyristor; simultaneously, the common port of protective circuit joins through resistance R 10 and power cathode.

2; electric ballast degaussing protective device according to claim 1; it is characterized in that: the fault detection signal of protective circuit; both can obtain from the emitter resistance R3 of switch transistor T 2; obtain in the coil of some circles of coiling on the magnetic core of high frequency transformer B2 that also can be in output circuit; this moment is an end of the anodal reconfiguration coil of diode B8; another termination common port of coil; in addition; also can obtain detection signal from resistance R 10; at this moment the anodal reconfiguration of diode D8 is arrived the right-hand member of resistance R 10, the left end of resistance R 10 connects the common port of protective circuit.

3, electric ballast degaussing protective device according to claim 1 is characterized in that: the high-frequency induction voltage of the coil n4 that this states is delivered on the resistance R 7 by halfwave rectifier or full-wave rectification or bridge rectifier.

4, according to claim 1 or 3 described electric ballast degaussing protective devices; it is characterized in that: the main element of control short-circuited coil n4 short circuit can also adopt the switch element such as the miniature relay of contact except adopting contactless element thyristor T3 or transistor.