CN2131270Y - Electronic ballast with lamp non-starting protector - Google Patents

Abstract

The utility model relates to an electronic ballast with a lamp non-starting protector. The switch transistor of a main circuit is arranged from an emitting electrode to a base electrode or from a source electrode to a grid electrode; the ballast has no other direct current channels besides a channel provided with output windings of a pulse transformer; the protector which is additionally arranged on the main circuit uses a voltage fetching coil to fetch voltage from the oscillation inductance of the main circuit. Under the non-starting state of the lamp, a one-way thyristor is triggered and conducted by sampling and delaying, and the one-way thyristor uses on-state valve voltage drop to make the switch transistor turn off because of the clamping of the base electrode or the grid electrode to protect the components in the main circuit from being damaged by high frequency filtering for a long time. The utility model has the advantage of safety.

Description

Electronic ballast with lamp non-starting protector

The utility model is a kind of electric ballast that lamp does not start protector that has that is applicable to fluorescent lamp.

Compare with inductance type ballast, electronic ballast for fluoresent lamp has efficiently, economizes on electricity, no buzzer, no stroboscopic sense and can low voltage starting etc. advantage.But common major loop has the electric ballast of the LCRT switch oscillating circuit (hereinafter to be referred as the LCRT circuit, T representation switch transistor) that is made of LCR vibration branch road and the switching circuit that contains switching transistor and pulse transformer in use remains flimsy deficiency under abnormality.Especially when the logical but lamp of electricity did not start, the LCRT circuit continued the high frequency overcurrent, causes the element thermal breakdown in the LCRT circuit.

Task of the present utility model is; install a lamp additional at electric ballast common, that do not have other DC channel from the switching transistor emitter to its base stage or from its source electrode to its grid again except the path that contains the pulse transformer output winding and do not start protector; with the failure of current of LCRT circuit, the high frequency overcurrent does not damage when making element in the LCRT circuit avoid long when the logical and lamp of electricity does not start.

Of the present utility model being characterised in that: the lamp that is installed additional does not start protector and has a sampling circuit, time-delay triggering networking, a clamp circuit and an isolating diode.Sampling circuit has a pressure coil and obtains induced voltage with coupled modes from the vibration inductance of LCRT circuit, output one sampled voltage and after rectification, dividing potential drop link to the delay capacitor charging of time-delay in the trigger network, at the logical and lamp of electricity not under the starting state, through one section time-delay, the time-delay trigger network is with the clamp circuit triggering and conducting, after the clamp circuit conducting with high potential switching transistor base stage or grid with respect to the voltage clamp of main circuit power negative pole built in low value, force switching transistor to end or pinch off, the LCRT circuit interrupter.The power supply termination main circuit power positive pole of protector clamp circuit; clamping reference point termination main circuit power negative pole; the clamp end connects high potential switching transistor base stage or grid by isolating diode, perhaps connects the end that switching transistor base resistance or resistance link to each other with the pulse transformer output winding.Wherein isolating diode can save simultaneously with lead its shorted on both ends, and the negative terminal of sampled voltage links to each other with the main circuit power negative pole.

The utility model feature more specifically is: sampling circuit has a pressure coil, a rectifier bridge and a voltage divider.The pressure coil directly adds on the skeleton of LCRT circuit oscillation inductance to obtain induced voltage; The input port of rectifier bridge links to each other with the two ends of pressure coil, and output port links to each other with the two ends of voltage divider, and the induced voltage that rectifier bridge is used for obtaining is transformed to DC induction and presses, and the output negative terminal of rectifier bridge links to each other with the main circuit power negative pole; Voltage divider is formed by resistance and semifixed resistor serial connection, is used for pressing the dividing potential drop sampling from DC induction.Wherein, the pressure coil can be connected in series one and adjust electric capacity, and the output port of rectifier bridge can and connect a filtering and keeps electric capacity, and voltage divider can save need not.The time-delay trigger network has a time delay network and a threshold switch.Time delay network is in series by a charging resistor and a delay capacitor, and its charging current flows into the dividing point that end connects voltage divider, connects the output plus terminal of rectifier bridge when voltage divider saves, and its charging voltage negative terminal connects the main circuit power negative pole.Threshold switch is formed by a diac and current-limiting resistance serial connection, the other end of diac connects the delay capacitor positive pole, the trigger end that the other end of current-limiting resistance connects clamp circuit is the control utmost point of one-way SCR in the clamp circuit, when the diac threshold voltage was low, current-limiting resistance can save simultaneously with lead its shorted on both ends.Clamp circuit has that one-way SCR, a current limliting pull-up resistor and of clamping action are kept electric capacity together.The negative electrode of one-way SCR connects the main circuit power negative pole as clamping reference point end, anode connects the negative electrode of isolating diode as the clamp end, one end of current limliting pull-up resistor connects the main circuit power positive pole as the power end of clamp circuit, and the other end links to each other with the anode of one-way SCR.Keep between the control utmost point and negative electrode that electric capacity is connected one-way SCR, its effect is to make one-way SCR keep conducting under weak current.The anode of isolating diode connects high potential switching transistor base stage or grid, perhaps connect the end that switching transistor base resistance or resistance link to each other with the pulse transformer output winding, its effect is the electric current of isolating to come the self-limiting pull-up resistor, and the while reduces with the dv/dt that the collocation of current limliting pull-up resistor is born one-way SCR.In protector, semifixed resistor can be replaced by fixed resistance, and fixed resistance can be replaced by adjustable resistance, and all fixed resistances and semifixed resistor all can be replaced or serial connection or and connect thermistor by thermistor.

Below, solution of the present utility model is described in conjunction with the accompanying drawings.

Do not start protector for lamp of the present utility model in the chain-dotted line frame 7 in the accompanying drawing, surplus is the electric ballast major loop.Major loop has by LCR vibration branch road and contains switching transistor T ₁, T ₂And the LCRT circuit of the switching circuit of pulse transformer Y formation, and from T ₁, T ₂Emitter to its base stage or from its source electrode to its grid except containing the output winding n of Y ₁, n ₂Path, do not have other DC channel again.In protector 7, the pressure coil L ' in the sampling circuit 1 directly adds on the skeleton of LCRT circuit oscillation inductance L.Two input terminals of rectifier bridge S link to each other with the two ends of L ', and the output port of S connects voltage divider 4, and the output negative terminal of S links to each other with main circuit power negative pole K simultaneously.Voltage divider 4 is by resistance R ₁With semifixed resistor R ₂Serial connection forms, and the contact M of the two is a dividing point; Voltage divider 4 can save need not.Time delay network 5 in the time-delay trigger network 2 is by resistance R ₃With delay capacitor C ₁Serial connection forms, and its charging current flows into termination dividing point M, saves the output plus terminal P that connects S under the no situation at voltage divider 4, and its charging voltage negative terminal links to each other with the K point.Under the situation that voltage divider 4 is not economized, resistance R ₃Can economize simultaneously with lead its shorted on both ends.Threshold switch 6 in the time-delay trigger network 2 is by diac Q and current-limiting resistance R ₄Serial connection forms, and the other end of Q connects C ₁Anodal F, R ₄The other end trigger end that connects clamp circuit 3 be the control utmost point G of unidirectional controllable silicon S CR in the clamp circuit 3, at the Q threshold voltage hour, R ₄Can economize simultaneously with lead its shorted on both ends.The negative electrode of SCR connects the K point as the clamping reference point end of clamp circuit 3, and its anode is as clamp end and current limliting pull-up resistor R ₅Be connected on the A point mutually, R ₅The other end connect the anodal E of main circuit power as power end.Keep capacitor C ₂Be connected between SCR control utmost point G and the negative electrode K.The negative electrode of isolating diode D connects the A point, and anode connects high potential switching transistor T ₁Base stage or grid H, perhaps connect T ₁Base resistance or resistance R _BOutput winding n with Y ₁An end H ' point that links to each other.

In force, the withstand voltage of SCR and D should be according to the main circuit power voltage U _EKAnd the consideration safety factor is selected; R ₅Resistance to guarantee in SCR conducting moment U _EK/ R ₅Much smaller than the SCR forward mean current rating; R ₄With C ₂Resistance value or time constant suitable little; The number of turn of L ' will be guaranteed R when the logical but lamp of electricity does not start ₂On sampled voltage U _MKOr the DC induction of S output is pressed U _PK(being applicable to that voltage divider 4 saves no situation, down together) is greater than the threshold voltage U of threshold switch 6 _Q

According to above-mentioned carry out wiring and adjust after, when the normal condition lamp starts, at C ₁On voltage U _FKReach U _QIn the past, lamp was just lighted, U _MKOr U _PKReturn and drop to less than U _QNumerical value, SCR does not trigger, ballast is work as usual.And at the logical but lamp of electricity not under the starting state, excessive when the di/dt of LCR vibration branch road is long, U _PKOr U _MKHigh, through one section time-delay, U _FKReach U _Q, the SCR triggering and conducting also utilizes its on-state tube voltage drop with H point or H ' some current potential U of ordering with respect to K _HKOr U _{H ' K}Strangulation is being lower than the numerical value of 1.5V, T ₁By or pinch off, the LCRT circuit interrupter, overcurrent damages when long thereby the element in the protection LCRT circuit exempts from.

Claims (5)

1, a kind of electric ballast that lamp does not start protector that has that is applicable to fluorescent lamp, major loop have by LCR vibration branch road and contain switching transistor T ₁, T ₂And the LCRT switch oscillating circuit (hereinafter to be referred as the LCRT circuit, T representation switch transistor) of the switching circuit of pulse transformer Y formation, and from T ₁, T ₂Emitter to base stage or from its source electrode to its grid, except containing Y output winding n ₁, n ₂Path; there is not other DC channel again; it is characterized in that: on electric ballast, add a lamp and do not start protector 7; protector 7 has a sampling circuit 1, time-delay trigger network 2, a clamp circuit 3 and an isolating diode D, and sampling circuit 1 usefulness a pressure coil L ' obtains induced voltage and export a sampled voltage U after rectification, dividing potential drop link from LCRT circuit oscillation inductance L with coupled modes _MKOr DC induction is pressed U _PK(U _PKBe applicable to that potential dividing ring saves the no situation of going), U _MKOr U _PKNegative pole link to each other with main circuit power negative pole K point, clamp circuit 3 be used for lamp not starting state to high potential switching transistor T ₁Base stage or grid H point clamp, its power end connects the anodal E point of main circuit power, clamping reference point end connects main circuit power negative pole K point, clamp end A process D connects the H point, perhaps connects T ₁Base resistance or resistance R ₈With Y output winding n ₁An end H ' point that links to each other, wherein D can save simultaneously with lead its shorted on both ends.

2, according to the electric ballast of claim 1; it is characterized in that: the sampling circuit 1 in the described protector 7 has a pressure coil L ', a rectifier bridge S and a voltage divider 4; L ' directly adds on the skeleton of LCRT circuit oscillation inductance L; two of S input terminals link to each other with the two ends of L ' and output port links to each other with the two ends of voltage divider 4; the output negative terminal of S links to each other with main circuit power negative pole K, and voltage divider 4 is by resistance R ₁With semifixed resistor R ₂Be in series, wherein R ₁Available adjustable resistance replaces, R ₂Available fixed resistance replaces, R ₁, R ₂All available thermistor replace or serial connection or and connect thermistor, voltage divider 4 can save need not, L ' two ends can be connected in series one and adjust electric capacity, the output port of S can a filtering in parallel be kept electric capacity.

3, according to the electronics town device of claim 1, it is characterized in that: the time-delay trigger network 2 in the described protector 7 has a time delay network 5 and a threshold switch 6, and time delay network 5 is by charging resistor R ₃With delay capacitor C ₁Be in series, its charging current flows into the dividing point M that end connects voltage divider 4, saves the not output plus terminal P of time spent connection rectifier bridge S at voltage divider 4, and its charging voltage negative terminal connects main circuit power negative pole K, R ₃Available adjustable resistance or thermistor replace, also can be connected in series or and connect thermistor, under the prerequisite that voltage divider 4 does not save, R ₃Can economize simultaneously with lead its shorted on both ends, threshold switch 6 is by a diac Q and current-limiting resistance R ₄Serial connection forms, and the other end of Q connects C ₁Anodal F, R ₄The other end connect the control utmost point G of unidirectional controllable silicon S CR in the clamp circuit 3, when the threshold voltage of Q is low, R ₄Can economize simultaneously with lead its shorted on both ends.

4, according to the electric ballast of claim 1, it is characterized in that: the clamp circuit 3 in the described protector 7 has a unidirectional controllable silicon S CR, a current limliting pull-up resistor R ₅With one keep capacitor C ₂, the negative electrode of SCR connects main circuit power negative pole K, anode and R ₅Be connected in the A point mutually, R ₅The other end connect the anodal E of main circuit power, C ₂Be connected between the control utmost point G and negative electrode K of SCR.

5, according to the electric ballast of claim 1, it is characterized in that: the negative electrode of the isolating diode D in the described protector 7 connects anode and the current limliting pull-up resistor R of unidirectional controllable silicon S CR ₅Contact A, the anode of D connects high potential switching transistor T ₁Base stage or grid H, perhaps connect T ₁Base resistance or resistance R _BOutput winding n with pulse transformer Y ₁An end H ' point that links to each other.

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