CN2442475Y - Abnormal state protection electronic ballast - Google Patents

Abstract

The utility model provides an electronic ballast with the function of abnormal state automatic protection, which is suitable for a lamp and multiple lamps is additionally provided with abnormality protecting circuit on the basis of a known circuit. The abnormality protecting circuit is composed of a discharge circuit, an isolating circuit, a time delay circuit and a short-circuited circuit. When one or a plurality of fluorescent tubes loaded by the electronic ballast is in the abnormal state, the output is automatically stopped. Once the abnormal state is removed, the circuit can rapidly restore actions. The abnormality protecting circuit of the ballast has the greatest characteristics of reliable operation, long service life, wide application scope, low cost, etc.

Description

Differential mode protection electric ballast

The utility model relates to a kind of electric ballast, a kind of electric ballast that has protective effect under abnormality.

Electric ballast progressively replaces traditional Inductive ballast owing to have advantages such as power-saving, that starting is fast.Present electric ballast comprises automatic bias auto-excitation type and zero-bias separated exciting, mainly is made up of rectification circuit, filter circuit, triggering start-oscillation circuit, high-frequency oscillating circuits, choke and resonant capacitance etc.These electric ballasts damage when abnormal conditions such as load short circuits occurring easily, thereby have blemish in an otherwise perfect thing.

The purpose of this utility model is the shortcoming that overcomes prior art, and a kind of electric ballast with differential mode defencive function is provided.

For achieving the above object, the utility model increases the differential mode protective circuit on the circuit base of known electric ballast, and this differential mode protective circuit is made up of bleeder circuit, buffer circuit, delay circuit and short circuit current.

Below in conjunction with drawings and Examples the utility model is further described.

Fig. 1 is a structure principle chart of the present utility model;

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

See figures.1.and.2; the utility model comprises rectification circuit (1), filter circuit (2), triggers start-oscillation circuit (3), high-frequency oscillating circuits (4), choke (5) and resonant capacitance (6); increased differential mode protective circuit (7), this differential mode protective circuit (7) is made up of bleeder circuit (7a), buffer circuit (7b), delay circuit (7c) and short circuit current (7d):

1. go up resistance of cross-over connection at filter circuit (2) and constitute bleeder circuit (7a);

2. triggering a polarity free capacitor formation of start-oscillation circuit (3) insertion buffer circuit (7b);

3. go up a PTC resistance in parallel (semistor) at resonant capacitance (6) and constitute delay circuit (7c);

4. go up or the fluorescent tube two filaments outside short circuit current (7d) that is in series by two bimetal leaf starters in parallel at resonant capacitance (6).

Above-mentioned short circuit current (7d) can also be connected in series a current-limiting resistance.

The technical program both had been applicable to the automatic bias auto-excitation type, also was applicable to zero-bias independent-excited electric ballast.Both be suitable for single fluorescent tube electric ballast, also be applicable to many fluorescent tubes electric ballast.For many fluorescent tubes electric ballast, every tubes all is provided with a choke (5), resonant capacitance (6) and delay circuit (7c) and short circuit current (7d).

When the fluorescent tube of electric ballast load is in abnormality (as the tube filament short circuit), short circuit current (7d) is short circuit after the PTC resistance time-delay of delay circuit (7c), and LC resonance is ended immediately.Electric capacity and supply voltage in buffer circuit this moment (7b) are in on the equipotential, trigger start-oscillation circuit (3) and are isolated and starting of oscillation again, and this moment, electric ballast was in protected state.After supply voltage disconnected, the electric capacity in the buffer circuit (7b) was rapidly by the conductive discharge in the bleeder circuit (7a), but circuit returns to starting state very soon.

The utlity model has that circuit is simple, abnormal protection is reliable, low cost and other advantages.

Claims (3)

1. a differential mode is protected electric ballast; comprise rectification circuit (1), filter circuit (2), trigger start-oscillation circuit (3), high-frequency oscillating circuits (4), choke (5) and resonant capacitance (6); it is characterized in that having increased differential mode protective circuit (7), this differential mode protective circuit (7) is made up of bleeder circuit (7a), buffer circuit (7b), delay circuit (7c) and short circuit current (7d):

A. go up resistance of cross-over connection at filter circuit (2) and constitute bleeder circuit (7a);

B. triggering a polarity free capacitor formation of start-oscillation circuit (3) insertion buffer circuit (7b);

C. go up a PTC resistance in parallel at resonant capacitance (6) and constitute delay circuit (7c);

D. go up or the fluorescent tube two filaments outside short circuit current (7d) that is in series by two bimetal leaf starters in parallel at resonant capacitance (6).

2. differential mode protection electric ballast according to claim 1 is characterized in that short circuit current (7d) can also be connected in series a current-limiting resistance.

3. differential mode protection electric ballast according to claim 1 is characterized in that for many fluorescent tubes electric ballast every tubes all is provided with a choke (5), resonant capacitance (6) and delay circuit (7c) and short circuit current (7d).