CN2539379Y

CN2539379Y - Resonance switch type electronic ballast

Info

Publication number: CN2539379Y
Application number: CN 02227055
Authority: CN
Inventors: 陈家正; 杨忠富; 杨英君; 罗晓苑
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-04-24
Filing date: 2002-04-24
Publication date: 2003-03-05
Anticipated expiration: 2012-04-24

Abstract

The utility model discloses an electronic ballast circuit for fluorescent tube, which is composed of a half-bridge circuit, a starting circuit, a ballast inductance, a control and drive circuit. Field-effect transistors M1 and M2 and capacitors C1 and C2 form one half-bridge circuit, the load of lamp is connected to A point through the ballast inductance L1, the other end of lamp tube is connected to B point, C3, RT1, and LP1 form the starting circuit of lamp tube. The control and drive circuit outputs a constant voltage signal with two phase differences (180 degree) and the frequency (f), as the frequency of the voltage is approximate to the resonance frequency generated by the ballast inductance and the lamp tube starting circuit, a high voltage is generated at two ends of lamp tube, the high voltage makes the lamp tube be illuminated, after illuminated, the neon bulb LP1 is cut off, so that the starting circuit is cut off.

Description

Resonant switch formula electric ballast

The utility model relates to a kind of fluorescent tube electric ballast, especially a kind of zero voltage switch electric ballast of independent-excited.

Existing electric ballast kind is quite numerous and diverse, and each kind all respectively has its characteristics.But its power output of existing electric ballast is all little, an electric ballast can not drive too many fluorescent tube, even there are several moneys one also to exist such-and-such shortcoming with three tubes, a kind with four tubes, be in particular in: 1, interact between several tubes, wherein a tubes damages or can influence lighting of other normal fluorescent tube unusually; 2, change the fluorescent tube inconvenience.When a tubes wherein damaged or be unusual, the electronic ballast protection function on extinguished all fluorescent tubes; When the maintenance personal changes fluorescent tube, just do not know it is that tubes needs to change on earth like this, make troubles for actual the use; 3, some one need open power supply with many electric ballast again after changing fluorescent tube; 4, some electric ballast starts the loop and continues to flow through electric current after fluorescent tube starts, and has increased electric energy loss, has shortened fluorescent tube useful life.

The purpose of this utility model provides a kind of electric ballast of high performance price ratio, and electric ballast is 3,6,12 of tractions or more tubes simultaneously, light the needed device cost of every tubes with minimizing; All be separate between every tubes, one or a few tubes damage or do not influence lighting of other normal fluorescent tube when unusual; When changing fluorescent tube, do not need power-on again; During the fluorescent tube operate as normal, the electric current that starts the loop is zero, thereby reduces electric energy loss, prolonging lamp tube service life.

For achieving the above object, thinking and technical scheme that the utility model adopts are such: export 180 ° of two phase differences by control and drive circuit, the voltage signal that frequency f is invariable from start to finish, drive two metal-oxide-semiconductors up and down of half-bridge circuit respectively, produce resonance, produce a high voltage in lamp tube ends by L1, C3, RT1, LP1, fluorescent tube is punctured startup, after fluorescent tube started, neon bulb LP1 disconnected, and starting loop current is zero.

Fig. 1 is the circuit theory diagrams of the inversion part of an embodiment of the present utility model, and this embodiment is one one and drags three electric ballast.

As shown in Figure 1, field effect transistor M1, M2 and capacitor C 1, C2 constitute a half-bridge circuit, three lamp loads are connected to the A point by ballast inductance L1, L2, L3 respectively, the other end of fluorescent tube is connected in parallel to the B point, C3, RT1, LP1 constitute the startup branch road of first tubes, C5, RT2, LP2 constitute the startup branch road of second tubes, and C6, RT3, LP3 constitute the startup branch road of the 3rd tubes.180 ° of control and two phase differences of drive circuit output, the voltage signal that frequency f is invariable from start to finish, difference driven MOS pipe M1, M2, setting up an amplitude at 2 between A, B is that 200V, frequency are the high-frequency ac voltage of f, because the frequency of this voltage is near the resonance frequency of ballast inductance and the generation of fluorescent tube start-up circuit, thereby at high voltage of lamp tube ends generation, this high voltage starts light fluorescent tube.Behind the lamp tube starting, neon bulb LP1, LP2, LP3 disconnect, and start the loop disconnection thereby make.If a certain tubes is unusual, then with startup loop that this tubes links to each other on the thermistor action, disconnect this startup loop; Other normal fluorescent tube can not be affected.

One end of capacitor C 4 links to each other with the drain electrode of M2, and the other end links to each other with the source electrode of M2.The main effect of C4 is to make field effect transistor realize switch under zero-voltage state.

Inductance L 4 is connected between 2 of A, the B.It has mainly acted on two, first effect be when zero load with capacitor C 4, produce a quasi-resonance phenomenon, make M1, M2 near no-voltage the time, turn-off; Second effect is when a certain tubes produces rectifying effect unusually, and this inductance flows through a DC component, and the voltage between 2 of the A that makes, the B maintains normal condition, thereby the fluorescent tube of protecting all the other normally to light is without prejudice.

Resistance R 2 is connected with diode D1, and is in parallel with resistance R 1 again, and an end links to each other with the grid of M1, another termination drive signal.Resistance R 4 is connected with diode, and is in parallel with resistance R 3 again, and an end links to each other with the grid of M2, another termination drive signal.R1＞R2 is arranged generally speaking, R3＞R4.The main effect of these two series-parallel circuits is turn-off speeds of accelerating M1, M2, the speed of opening of slowing down M1, M2.

Voltage source V 1 is produced by the pfc circuit of front end, and numerical values recited is decided on actual needs.

M1, M2 can be by electric current the enough big situation of ability under, can the abundant fluorescent tube of parallel connection between 2 of A, B, and all be separate between every tubes, the damage of or several tubes can not influence other normal fluorescent tube; The maintenance of fluorescent tube with change also and conveniently, do not need power-on again after changing the fluorescent tube that damages.Because a neon bulb is arranged in the startup loop of every tubes, make this electric ballast both have the function of pipeline start up by preheating, and can also make that the electric current that starts the loop under the situation of operate as normal is zero, thereby reduce electric energy loss, prolonging lamp tube service life.

Claims

1. a resonant mode electric ballast comprises control and drive circuit, half-bridge circuit, ballast inductance, start-up circuit etc.It is characterized in that: the frequency f of the drive signal of control and drive circuit output is invariable from start to finish, each tubes all has an independently start-up circuit, start-up circuit is composed in series by capacitor C 3, thermistor RT1, neon bulb LP1, is connected two ends of fluorescent tube.

2. resonant mode electric ballast according to claim 1, it is characterized in that: the grid at field effect transistor M1, M2 respectively connects a network that is made of resistance, diode, its connection is such: a resistance is connected with a diode, in parallel with another resistance again, and satisfy such relation: R1＞R2 all the time, R3＞R4.

3. resonant mode electric ballast according to claim 1 is characterized in that: be connected an inductance L 4 between A point and B point.