KR20020014578A - Protective Circuit For Ballast High Pressure Discharge Lamp - Google Patents

Abstract

PURPOSE: A protection circuit for a ballast of a high voltage discharge lamp is provided to avoid damage of related devices and parts of the ballast by detecting over-voltage induced in the high voltage discharge lamp when the lamp can't be turned on. CONSTITUTION: A protection circuit for a ballast of a high voltage discharge lamp comprises a DC converter(10) for stably supplying high power of about 100-1000 Watts, a switching signal generator(20) having a first and a second switching transistors(Q1, Q2) and a first switching transformer wound wire(T2-c), and a lamp driver(30). The protection circuit includes a high power pulse transformer(T3). A first wound wire of the transformer(T3) is coupled between the first switching transformer wound wire(T2-c) and a high voltage discharge lamp(L) of the lamp driver(30). One end of the second wound wire of the transformer(T3) is coupled a variable resistor(RT), a bi-polar transistor(Q3) and a diode(D3) that adjust turn-on timing. The other end of the transformer(T3) is coupled to a diode(D2), capacitor(C4), a Zener diode(Z5) and a resistor(R6) that charge/discharge high pulse power from the high power pulse transformer(T3) to detect over-voltage induced when the high voltage discharge lamp(L) can't turn on and adjust.

Description

Protection Circuit for Ballast High Pressure Discharge Lamp

The present invention relates to a ballast circuit for a high-pressure discharge lamp, and more particularly, to protect the peripheral circuit element from high voltage generated before the high-pressure discharge lamp is sufficiently cooled to protect the ballast for the high-voltage discharge lamp to improve the reliability of the ballast. It is about a circuit.

As is well known, high-pressure discharge lamps such as mercury lamps, sodium lamps, metal halide lamps and halogen lamps are used for outdoor lighting such as parks, parking lots and railway stations. In addition to being used as a light, it is also widely used for lighting of indoor facilities such as gymnasiums, department stores, exhibition halls, and the like.

These high-pressure discharge lamps have a higher power efficiency than general light bulbs and lamps, have excellent power saving effect, and have high penetrating power of fog or smoke instead of fast lighting time, so they can be installed in a wide variety of places and fields. There is this.

On the other hand, since the high-voltage discharge lamp uses a high power of about 100 to 1000 watts (W), a dedicated ballast circuit is employed to maintain such a high power stably, and the ballast circuit is a field effect transistor or the like. It consists of a switching circuit and a lamp driver for driving a high-pressure discharge lamp.

However, in the case of such a high-pressure discharge lamp, the lamp is broken or disconnected due to disturbance or the like, or about 2 to 5 minutes are required to be sufficiently cooled in the process of repeatedly lighting and cooling the high-pressure discharge lamp. Since the lamp is not turned on during the period, a high overvoltage pulse signal is applied to circuit elements such as field effect transistors constituting the switching circuit of the ballast circuit because the supply of electric energy due to an increase in the internal pressure cannot be supplied to the lamp. As is applied, there is a problem that damage to the circuit elements and related parts is caused, and acts as a factor to shorten the life of the discharge lamp.

Accordingly, the present invention has been made to solve the above-described conventional problems, the object of which is to stabilize the ballast by detecting the overvoltage induced in the high-pressure discharge lamp in the state that the high-pressure discharge lamp is not turned on and the lamp is not sufficiently cooled It is to provide a protection circuit for the ballast of the high-pressure discharge lamp to prevent damage to the circuit elements and components of the circuit.

1 is a circuit diagram illustrating a protection circuit for a ballast of a high-pressure discharge lamp according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: direct current converter, 20: switching signal generator,

30: protection circuit part, 40: lamp drive part,

Q1, Q2: field effect transistor, Q3: bipolar transistor,

T1: noise filter, T2-c: 1st side switching transformer winding,

T2-a, T2-b: secondary side switching transformer winding, T3: high voltage pulse transformer,

C2: smoothing capacitor, D1-D5: diode,

DA: DIAC, R1-R7: Resistance,

Z1-Z5: Zener diode.

In order to achieve the above object, according to the present invention, a switching function is initiated according to a trigger operation of a trigger circuit, and the first and second switching transistors are alternately and repeatedly switched with each other when a counter electromotive force of the switching transformer is generated, In the ballast circuit of a high voltage discharge lamp having a high voltage pulse transformer and a capacitor for generating a high voltage for turning on the high voltage discharge lamp by matching a resonance frequency in accordance with the switching operation of the first and second switching transistors, Provided is a protective circuit for a ballast of a high voltage discharge lamp including a protection circuit portion for detecting an overvoltage generated from the high voltage pulse transformer during an equal period and adjusting a switching period of the first and second switching transistors.

Preferably, the protection circuit unit has a diode, a bipolar transistor, and a variable resistor for controlling the timing of lighting at one end of the secondary winding of the high voltage pulse transformer connected to any one of the first and second switching transistors, A diode, a capacitor, a zener diode, and a resistor for charging and discharging according to an overvoltage are connected to the other end of the secondary winding.

According to the present invention configured as described above, the high pressure discharge lamp is broken or disconnected and is not lit, or is generated due to the failure of applying high voltage electrical energy to the high pressure discharge lamp during the unlit period corresponding to the time before it is sufficiently cooled. When the detected overvoltage is detected, the timing of turning on the switching conditions of the plurality of switching transistors switched to drive the high voltage discharge lamp is controlled so that the timing of lighting up to the time at which the lighting condition of the high voltage discharge lamp is formed can be adjusted. It is possible to prevent the associated circuit elements of the ballast circuit from being damaged by overvoltage.

Hereinafter, the present invention configured as described above will be described in detail with reference to the accompanying drawings.

1 is a circuit diagram showing a state in which a protection circuit according to the present invention is applied to a ballast circuit of a high-voltage discharge lamp.

As shown in FIG. 1, in the present invention, the DC converter 10, the switching signal generator 20, and the like, for stably supplying high power of about 100 to 1000 watts (W) to the high-pressure discharge lamp (L). The lamp driver 30 is configured.

In addition, in the present invention, the high-pressure discharge lamp L is damaged or disconnected due to disturbance or the like, or a period of about 2 to 5 minutes required until sufficient cooling is performed in the process of lighting and cooling repeatedly. In such a state that the high voltage discharge lamp L cannot be turned on as described above, the overvoltage generated by the increase in the internal pressure of the high voltage discharge lamp L is detected to protect the circuit elements constituting the switching signal generator 20. The protection circuit part 40 is comprised.

In the figure, the DC converter 10 has a negative voltage thermistor NTC and a fuse F connected to one end and the other end of an AC power source AC, and a surge voltage removing element TNR is connected between both ends thereof. In addition to the connection, the high frequency noise filter T1 and the capacitor C1 are connected.

In addition, both ends of the AC power source AC via the high frequency noise filter T1 and the capacitor C1 in the DC converter 10 are connected to a bridge diode BD for rectifying an AC voltage. The bridge diode BD is connected to the smoothing capacitor C2 for smoothing the pulsating component of the rectified voltage.

Here, the negative voltage thermistor NTC is designed to open an internal resistance when the AC voltage of the overvoltage is detected to short the connection terminal, and the fuse F is open when an AC voltage of the overvoltage is applied.

In addition, the surge voltage removing element TNR absorbs the surge voltage mixed in the AC power source AC, and the high frequency noise filter T1 and the capacitor C1 remove only the high frequency noise components included in the AC voltage. It is supposed to be.

In the figure, the switching signal generator 20 has a resistor R1 and a capacitor C3 in series with each other at both ends of the bridge diode BD and the smoothing capacitor C2 of the DC converter 10. The first field effect transistor Q1 is connected as a switching circuit element between the forward connection end of the diode D1 and the output end of the bridge diode BD from the connection point of the resistor R1 and the capacitor C3. The secondary side switching transformer winding T2-a and the zener diodes Z1 and Z2 are connected between the gate terminal and the drain terminal of the first field effect transistor Q1, respectively.

In addition, the switching signal generator 20 is provided between a connection terminal of the resistor R4 and the die solution DA connected between the resistor R1 and the capacitor C3 and an output terminal of the bridge diode BD. A second field effect transistor Q2 is connected as a switching circuit element, and the secondary side switching transformer winding T2-b and the zener diode Z3 (Z4) are connected between the gate end and the drain end of the second field effect transistor Q2. Are connected to each other.

On the other hand, the primary side switching transformer windings T2-c, which are connected by the secondary side switching transformer windings T2-a and T2-b by a predetermined turns ratio, have one end of the first and second field effect transistors ( Connected to the connecting nodes of Q1 and Q2, and the other end thereof is connected to the high-pressure discharge lamp L of the lamp driving unit 30 via the primary winding of the high-voltage pulse transformer T3 constituting the protective circuit unit 40; Connected.

In the same figure, one end of the high voltage discharge lamp L is connected to the primary switching transformer winding T2-c of the switching signal generator 20 through the resistor R5. A capacitor C5 and a resistor R7 are connected between both ends of the high voltage discharge lamp L.

On the other hand, a capacitor C6 and a diode D4 are connected in parallel between one end between the other end of the high voltage discharge lamp L and an output end of the bridge diode BD, and the capacitor C7 and the diode D5 are respectively connected to the other side. It is connected in parallel.

In addition, the protection circuit 40 is a high-voltage pulse transformer (T3) between the primary switching transformer winding (T2-c) of the switching signal generator 20 and the high-pressure discharge lamp (L) of the lamp driver (30). The primary winding of is connected, and the secondary winding of the high voltage pulse transformer T3 is connected to the variable resistor RT, the bipolar transistor Q3, and the diode D3 for adjusting the lighting timing of one end thereof. The other end thereof is connected to a diode D2, a capacitor C4, a zener diode Z5, and a resistor R6 for charging and discharging a high pulse voltage induced from the high voltage pulse transformer T3, respectively.

Here, the bipolar transistor Q3 is made of an NPN transistor, and the variable resistor RT and the resistor R6 are commonly connected to a base end thereof, and the collector end thereof is connected to the second electric field via a diode D3. It is connected to the gate terminal of the effect transistor Q2.

According to the protection circuit in the ballast of the high-voltage discharge lamp according to the present invention made as described above, in the switching signal generator 20, the capacitor C3 charges the DC voltage from the DC converter 10 and is constant When the period elapses, as the die solution DA is turned on so that the second field effect transistor Q2 is turned on, one of the capacitors C6 and C5 of the lamp driver 30 and the high voltage pulse transformer T3 is turned on. The driving current is applied through the secondary winding and the primary switching transformer winding T2-c.

In this state, when charging of the capacitors C6 and C5 is completed, a counter electromotive force is generated in the secondary switching transformer winding T2-a so that the first field effect transistor Q1 is turned on, while the first field effect transistor Q1 is turned on. The second field effect transistor Q2 is turned off and a driving current is applied through the primary side switching transformer winding T2-c, the primary winding of the high voltage pulse transformer T3, and the capacitors C5 and C7. .

On the other hand, when the charging of the capacitors C5 and C7 is completed, a counter electromotive force is generated in the secondary-side switching transformer T2-b and the second field effect transistor Q2 is turned on instead of turning on the first electric field. When the effect transistor Q1 is turned off, the frequency oscillated by the alternating and repetitive on / off operation of the first field effect transistor Q1 and the second field effect transistor Q2 is a high voltage pulse transformer T3. The capacitor C5 passes through the primary winding of the capacitor and the capacitor C5 and C6 and passes through the primary winding of the high voltage pulse transformer T3 and the capacitor C5 and C7. The high voltage discharge lamp L is turned on while a high voltage of about 3 to 5 KV is generated at both ends of the &quot;

On the other hand, the high-pressure pulse during the cooling time of about 2 to 5 minutes required until the high-pressure discharge lamp (L) is broken or disconnected by external force or the like, or sufficient cooling is achieved in the process of repeatedly lighting and cooling the lamp. Electrical energy from the transformer T3 is not applied to the high-pressure discharge lamp L side, and high pulse voltage is induced.

At this time, the protection circuit 40 detects the overvoltage through the secondary winding of the high-voltage pulse transformer (T3), the diode D2, the capacitor (C4), the zener diode (Z5) and the resistance (R6) The switching operation of the second field effect transistor Q2 and the first field effect transistor Q1 is adjusted at a timing controlled by the variable resistor RT, the bipolar transistor Q3, and the diode D3 according to the charge / discharge period. Done.

That is, when the protection circuit unit 40 detects an overvoltage generated due to insufficient cooling time while the high voltage discharge lamp L is not turned on, the first and second field effect transistors Q1 are detected. By stopping the switching operation of Q2 and stopping the generation of high voltage, it is possible to prevent breakage and shortening of life due to overvoltage of the related circuit elements and components including the first and second field effect transistors Q1 and Q2. It becomes possible.

According to the present invention as described above, when the overvoltage generated when the high-voltage discharge lamp is broken or disconnected, or not turned on in a state that is not sufficiently cooled, it is possible to stop the switching operation of the switching transistor, It is possible to protect related circuit elements and components of the ballast circuit from overvoltage and to improve the reliability of the ballast.

Claims (2)

The switching function is started according to the triggering operation of the trigger circuit, and the first and second switching transistors are alternately and repeatedly switched according to the generation of counter electromotive force of the switching transformer and the switching operation of the first and second switching transistors. In the ballast circuit of a high voltage discharge lamp having a high voltage pulse transformer and a capacitor for generating a high voltage for matching a resonance frequency to light a high voltage discharge lamp, Stable protection of the high-voltage discharge lamp, characterized in that it comprises a protection circuit for detecting the overvoltage generated from the high-voltage pulse transformer during the non-lighting period of the high-voltage discharge lamp to adjust the switching period of the first and second switching transistors. Protection circuit for aircraft. 2. The protection circuit of claim 1, wherein the protection circuit unit has a diode for controlling the timing of lighting at one end of the secondary winding of the high voltage pulse transformer, a bipolar transistor, and a variable resistor having any one of the first and second switching transistors. And a diode, a capacitor, a zener diode, and a resistor for connecting to the other end of the secondary side winding for charging and discharging according to an overvoltage, and a resistor for the ballast of the high voltage discharge lamp.