CN2146100Y - Overvoltage protecting device for electronic ballast - Google Patents

Abstract

The utility model relates to an overvoltage protecting device for electronic ballasts, which is used for improving the working reliability of electronic ballasts, comprising a gas-discharge tube and a resistor which are connected in series. The overvoltage protecting device for electronic ballasts can be connected to the output end of the switching power tube of an electronic ballast and the common end of filtering capacitors C-[1] and C-[2], and can also be connected in parallel with the current limiting inductance or resonant capacitor of the electronic ballast to absorb the overvoltage pulse voltage caused by the abnormal phenomena, such as poor contact of the lamp pins of a daylight lamp, lamp filament breaking, flash and non-glow of a lamp tube, switching shock of the power supply, etc. so as to prevent electronic components from breakdown. The utility model has the advantages of simple structure, low cost, high reliability, etc.

Description

Overvoltage protecting device for electronic ballast

The utility model is a kind of over-pressure safety device that is used to improve the electric ballast functional reliability, belongs to lighting technical field.

Fluorescent lamp ballast great majority of the prior art are iron inductance formula ballasts, along with development of electronic technology.Released electric ballast.Advantage such as electric ballast has energy-conservation, no ac stroboflash and hum, low-voltage starter are good, in light weight.It is made up of rectification circuit, circuits for triggering, HF switch oscillator and LC resonant tank etc. usually.Electric ballast unusual overvoltage occurs because of current break causes inductance coil when the fracture of the loose contact of fluorescent tube pin, tube filament, the weak discharge of fluorescent tube glimmer that anomaly such as build-up of luminance and mains switch impact does not occur.Cause electronic component, the particularly damage of switching oscillator power tube, this is the common cause that electric ballast damages.The reliability that improves electric ballast is current production and the key problem in technology applied.Fusing fuse reaction speed commonly used is slow, and poor reliability can not play a protective role to unusual damage.In recent years; some quick protection schemes have appearred; the disclosed protective device of Chinese patent (CN2076291U) for example; it adopts a winding is set on the oscillator coupling transformer; take from the unusual overvoltage pulse of this winding and after rectification, go to trigger controllable silicon and triode, force the base stage of switching power tube and emitter-base bandgap grading short circuit and failure of oscillation.Simultaneously make the starting of oscillation trigger of oscillator no longer trigger starting of oscillation again, but this scheme circuit complexity, cost height also because of the delayed action of protective circuit self, may not catch up with required impulse speed.The disclosed another kind of scheme of Chinese patent (CN2072311U) and for example; adopt the fluorescent lamp starter to absorb overvoltage pulse; it is parallel to the starter for fluorescent of two serial connections on the resonant capacitance; after abnormal pressure occurring; starter discharge and two electrodes are connected; but the starter electrode of this scheme is an on-off action, self causes the impact of an electric current, voltage again, is unfavorable for protecting electric ballast.

The utility model is at the deficiencies in the prior art, and a kind of simple in structure and protective device that can protect electric ballast not damaged unusually effectively is provided.

The utility model adopts the high-pressure discharge pipe to make over-voltage protection element; it is made up of gas discharge tube and resistance; gas discharge tube and resistance serial connection; the firing voltage of gas discharge tube can be 200～1000V; resistance value is 0～20K Ω, and it can be connected between the output and fluorescent lamp high frequency pumping voltage zero current potential filament of electric ballast switch power oscillating tube.Typical discharge tube firing voltage value is selected in 200～220V, and resistance value is 0.5～10K Ω, and resistance value is decided according to the permission electric current of discharge tube, and for the cermet discharge tube, resistance value is desirable little, does not even use resistance; If adopting discharging current is the little neon bulb of 1～2mA, then should get bigger resistance value.As long as the potential difference at protective device two ends surpasses the firing voltage of gas discharge tube; discharge tube is discharge just; tube voltage drop descends thereupon; this discharging current has suppressed abnormal pulsers voltage; thereby protected the trouble free service of electric ballast power switch transistor; this protective device can also be in parallel with the current-limiting inductance L or the resonant capacitance C of electric ballast, and the discharge tube firing voltage can be 600～1000V, to realize different protection requirements.

The utility model compared with prior art, have simple in structure, cost is low, protection is reliable and advantage such as effective, protective device is directly made overvoltage protection to the transistorized emitter-base bandgap grading-collector electrode of switch, not time-delay; During the electric ballast operate as normal, not power consumption of protective device; Gas discharge tube firing voltage precision height has the significant protection boundary.The utility model finds to have the phenomenon of damaging electric ballast yet through the action of lighting a lamp of No. nearly ten thousand switches, tests through filament break-make repeatedly, and circuit working is normal.

Fig. 1 is an electric principle schematic of the present utility model, and Fig. 2 is the winding diagram of embodiment.

The utility model can be realized by scheme shown in the drawings.As shown in Figure 1, gas discharge tube P can adopt cermet discharge tube or little neon bulb, and resistance R can be taked resistance commonly used, and embodiment can realize that BA is a fuse, D by scheme shown in Figure 2 ₁～D ₅Be diode, R ₁～R ₄Be resistance, C ₁～C ₄Be electric capacity, D ₆Be controllable silicon, protective device is connected on transistor BG ₁With BG ₂, capacitor C ₁With C ₂Tie point on, as required, also can be connected in parallel on current-limiting inductance L or the resonant capacitance C, T is a transformer.

Claims (4)

1, a kind of over-pressure safety device that is used to improve the electric ballast reliability is characterized in that it is made of gas discharge tube and resistance serial connection.

2, over-pressure safety device according to claim 1, the firing voltage that it is characterized in that gas discharge tube is 200～1000V.Resistance is 0～20K Ω.

3, over-pressure safety device according to claim 1 and 2 is characterized in that output and fluorescent lamp high frequency pumping voltage that protective device two terminates at the electric ballast switching power tube are the glower end of zero potential.

4, over-pressure safety device according to claim 1 and 2 is characterized in that the protective device two ends are attempted by on the current-limiting inductance L or resonant capacitor C of electric ballast.

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