KR200235270Y1 - Protective circuit for ballast high pressure discharge lamp - Google Patents

Abstract

The present invention provides a protection circuit for the electronic ballast of the high voltage discharge lamp for protecting the circuit elements and the high voltage discharge lamp by stopping the operation of the ballast circuit by detecting the overvoltage generated when the high pressure discharge lamp is not sufficiently cooled. do.

To this end, the present invention has a trigger signal generator having a plurality of switching transistors that are alternately and repeatedly switched according to generation of counter electromotive force of the switching transformer to perform oscillation operation of the resonant frequency, and according to the oscillation operation of the trigger signal generator. A ballast circuit of a high voltage discharge lamp having a lamp driving unit for lighting and driving a high voltage discharge lamp at a resonant frequency, comprising: a high voltage pulse transformer for detecting an overvoltage generated from the lamp driving unit when the high voltage discharge lamp is not lit; A first lamp protection circuit that adjusts switching timings for the plurality of switching transistors when an overvoltage is detected from a pulse transformer and bypasses back electromotive force generated from the switching transformer when the overvoltage is detected from the high voltage pulse transformer to trigger the trigger. Plurality of signal generators And a second lamp protection circuit that stops the switching drive for switching transistor is characterized in that configured.

Description

Protective circuit for ballast high pressure discharge lamp

The present invention relates to an electronic ballast circuit of a high-pressure discharge lamp, and more particularly, to protect the lamp and the peripheral circuit elements by preventing the high-pressure discharge lamp from being turned on in a state in which the high-pressure discharge lamp is not sufficiently cooled. 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, and have an excellent power saving effect, and have a high permeability of fog or smoke instead of a fast lighting time, so that they can be installed in various places and fields. have.

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 a circuit element such as a field effect transistor constituting a switching circuit of the ballast circuit, because electrical energy is not supplied to the lamp due to an increase in the internal pressure. As a result, breakage of circuit elements and related components is caused, and there is a problem of acting as a factor for shortening the life of the discharge lamp.

Accordingly, the present invention is to solve the above-described problems, the purpose of which is to detect the overvoltage generated when the high-pressure discharge lamp is not sufficiently cooled to stop the driving of the ballast circuit associated circuit elements and high-voltage discharge To provide a protection circuit for the electronic ballast of the high-pressure discharge lamp to protect the lamp.

1 is a view showing the configuration of the electronic ballast protection circuit of the high-pressure discharge lamp according to the present invention.

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

10: AC-DC converter, 20: trigger signal generator,

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

Q1, Q2: field effect transistor, Q3, Q4: bipolar transistor,

T2-c: secondary switching transformer winding, T2-a, T2-b: secondary switching transformer winding,

LFT: Noise canceling inductor, D1 to D5: Diode,

R1 to R4: resistance (carbon film resistance), R5 to R7: resistance (cement resistance),

Z1-Z4: Zener diode.

In order to achieve the above object, according to the present invention, a trigger signal generator having a plurality of switching transistors are alternately and repeatedly switched according to generation of counter electromotive force of the switching transformer to perform the oscillation operation of the resonant frequency, and the trigger signal generation A ballast circuit of a high voltage discharge lamp having a lamp driving unit for lighting and driving a high voltage discharge lamp at a resonant frequency according to a negative oscillation operation, wherein the overvoltage generated from the lamp driving unit is detected when the high voltage discharge lamp is not lit. A high voltage pulse transformer, a first lamp protection circuit for adjusting switching timings of the plurality of switching transistors when an overvoltage is detected from the high voltage pulse transformer, and an overvoltage detected from the high voltage pulse transformer By bypassing back EMF Provided is a protection circuit for an electronic ballast of a high voltage discharge lamp including a second lamp protection circuit for stopping switching driving of a plurality of switching transistors of a trigger signal generator.

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

As shown in FIG. 1, in the present invention, an AC-DC converter 10 converting an AC voltage into a DC voltage in order to stably supply high power of about 100 to 1000 watts (W) to a high-pressure discharge lamp (LAMP). And a trigger signal generator 20 which is driven by receiving a DC voltage of the AC-DC converter 10 to generate a trigger signal, and a lamp driver 30 which turns on the high voltage discharge lamp LAMP by the trigger signal. And a lamp protection circuit unit 40 for protecting the high voltage discharge lamp LAMP from a high voltage.

In the figure, the AC-DC converter 10 has a negative voltage thermistor NTC and a fuse F respectively connected to one end and the other end of the AC power source AC, and a surge voltage removing element TNR is connected between both ends thereof. ) And a noise removing inductor (LFT) and a capacitor (C1) for removing high frequency noise of the AC voltage.

In this case, the negative voltage thermistor NTC is configured to short the connection terminal when an overvoltage is detected among AC voltages, and the fuse F is opened when an overvoltage greater than a predetermined allowable value is applied from the AC voltage. It is designed to be open.

In addition, the surge voltage removing element (TNR) absorbs the surge voltage mixed in the AC power, and the noise removing inductor (LFT) and the capacitor (C1) can remove only the high-frequency noise components included in the AC voltage. It is.

On the other hand, in the AC-DC converter 10, both ends of the AC power supply AC via the noise removing inductor LFT and the capacitor C1 are connected to the bridge diode BD1 for rectifying the AC voltage. The bridge diode BD1 is connected to a smoothing capacitor C2 for smoothing the pulsating component of the rectified voltage.

In the figure, the trigger signal generator 20 has a resistor R1 and a capacitor C3 mutually connected to both ends of the bridge diode BD1 and the smoothing capacitor C2 of the AC-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 BD1 from a connection point of the resistor R1 and the capacitor C3. Between the gate end and the drain end of the first field effect transistor Q1, the secondary side switching transformer winding T2-a interlocked with a primary switching transformer winding T2-c which will be described later constituting the lamp driver 30. ) And zener diodes Z1 and Z2 are connected in parallel, respectively.

In addition, the trigger signal generator 20 is connected between the connection terminal of the resistor R4 and the die solution DA1 connected between the resistor R1 and the capacitor C3 and the output terminal of the bridge diode BD1. A second field effect transistor Q2 is connected as a switching circuit element, and a primary side switching transformer winding T2-c constituting the lamp driver 30 is formed between the gate end and the drain end of the second field effect transistor Q2. The secondary side switching transformer winding T2-b and the zener diodes Z3 and Z4 are respectively 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 ( The high voltage discharge lamp LAMP of the lamp driving unit 30 is connected to the connection nodes of Q1 and Q2 and the other end thereof is connected to the primary winding of the high voltage pulse transformer T3 constituting the lamp protection circuit unit 40. Is connected to.

In the figure, one end of the high voltage discharge lamp LAMP is connected to the primary switching transformer winding T2-c through the primary winding of the resistor R5 and the high voltage pulse transformer T3. A capacitor C6 and a diode D4 are connected in parallel to one side between the other end of the high voltage discharge lamp LAMP and the output end of the bridge diode BD1, and the capacitor C7 and the diode D5 are connected to the other side thereof. The capacitors C5, the negative voltage thermistor NTC-2 and the resistor R7 are respectively connected between the both ends of the high voltage discharge lamp L, respectively.

The lamp protection circuit unit 40 may be damaged or disconnected due to disturbance due to disturbance or the like, or may take about 2 to 5 minutes until sufficient cooling is performed in a process in which the corresponding lamp is repeatedly turned on and cooled. In a state in which the high voltage discharge lamp LAMP cannot be turned on, such as within a period of time, the trigger signal generator 20 is detected by detecting a high voltage generated by an increase in the internal pressure of the high voltage discharge lamp LAMP. This is to protect the circuit elements.

In addition, the lamp protection circuit unit 40 is connected between the primary side switching transformer winding T2-c of the lamp driving unit 20 and the high voltage discharge lamp LAMP, and the primary winding of the high voltage pulse transformer T3 is connected thereto. The secondary winding of the high voltage pulse transformer T3 has one end connected to the base end of the first bipolar transistor Q3 via the protection resistor R9 and the diode D7, and the protection resistor R9 and the diode ( In parallel with the series connection state of D7), the protection resistor R8 and the diode D6 are connected to the die solution DA2 via a state in which the series connection is made in series, while the die solution DA2 is a bipolar transistor Q4. Is connected to the base end.

Here, the protection resistor (R9) and the protection resistor (R8) is for reducing the current value according to the high voltage applied from the high-voltage pulse transformer (T3), respectively, the diode (D7) and diode (D6) is the respective protection This is for rectifying the current value passing through the resistors R9 and R8.

The first bipolar transistor Q3 includes a capacitor C4 for charging current and a variable resistor RT for adjusting the lighting timing between the base end thereof and the protection resistor R9 and the series connection terminal of the diode D7. Each of them is connected in parallel, and the emitter terminal is composed of an NPN transistor connected between the resistor R1 and the capacitor C3 terminal of the trigger signal generator 20 via the forward connection state of the diode D7. .

The second bipolar transistor Q4 has two bases of the trigger signal generator 20 having its emitter terminal via the forward connection state of the diode D3 while the base terminal thereof is directly connected to the die solution DA2. It consists of an NPN transistor connected between the differential side switching transformer winding T2-b and the gate terminal of the second field effect transistor Q2.

Next, the operation of the protection circuit in the ballast of the high-pressure discharge lamp according to the present invention made as described above will be described in detail with reference to the accompanying drawings.

First, when the AC-DC converter 10 converts and supplies an AC voltage to a DC voltage, in the trigger signal generator 20, the capacitor C3 is a direct current from the DC converter 10. After a certain period of time after charging the voltage, the die solution DA is turned on as the voltage rises to a set value such as 34 V, thereby turning on the second field effect transistor Q2.

According to the turn-on state of the second field effect transistor Q2, in the lamp driver 30, the driving current is the capacitor C6 and the capacitor C5, the high voltage pulse transformer T3, and the primary side switching transformer winding T2-c. When the charging of the capacitors C6 and C5 is completed, the first field effect transistor Q1 is turned on due to the generation of back EMF of the secondary switching transformer winding T2-a. The second field effect transistor Q2 is turned off while flowing through the switching transformer winding T2-c, the high voltage pulse transformer T3, and the capacitors C5 and C7.

Here, when charging of the capacitors C5 and C7 is completed, instead of turning on the second field effect transistor Q2 as the counter electromotive force is generated in the secondary side switching transformer winding T2-b, the first field effect transistor Q2 is turned on. Since the field 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 has a high voltage pulse transformer ( Passing through the primary winding of T3 and the capacitor (C5) (C6), passing through the primary winding of the high-voltage pulse transformer (T3) and the capacitor (C5) (C7) at the instant the resonance frequency is matched to the capacitor ( The high voltage discharge lamp LAMP is turned on while a high voltage of about 3 to 5 KV is generated at both ends of C5).

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

At this time, the lamp protection circuit unit 40 rectifies the overcurrent according to the overvoltage detected through the secondary winding of the high-voltage pulse transformer T3 and reduces the current value through the resistor R9 and the diode D7. Then, the driving current is charged in the capacitor C4 under the control of the lighting timing according to the resistance value of the variable resistor RT.

When the charging of the capacitor C4 is completed, the first bipolar transistor Q3 is turned on by receiving a voltage from the secondary winding of the high voltage pulse transformer T3 through the resistor R9 and the diode D7. The first bipolar transistor Q3 is repeatedly turned on and off according to the charging state of the capacitor C4 and the resistance value for controlling the lighting timing of the variable resistor RT, and the first bipolar transistor Q3 is repeated. According to the repetitive turn on / off state for controlling the timing of lighting), the state of charge of the capacitor C3 of the trigger signal generator 20 is adjusted, and the turn on / off state of the die solution DA1 is adjusted. And switching timing for turning on / off the second field effect transistors Q1 and Q2.

On the other hand, when the overvoltage induced from the secondary winding of the high-voltage pulse transformer (T3) is reduced and the current value is rectified through the resistor (R8) and diode (D6), it corresponds to the turn-on conditions of the die solution (DA2) For example, in the case of exceeding a set value of 34 V, the die liquid DA2 is turned on while being subjected to an overvoltage exceeding the set value from the secondary winding of the high voltage pulse transformer T3, and the turn on of the die liquid DA2 is turned on. As a result, the second bipolar transistor Q4 is turned on.

According to the turn-on state of the second bipolar transistor Q4, the counter electromotive force of the secondary-side switching transformer winding T2-b is bypassed and the first and second field effect transistors Q1 and Q2 are repeatedly turned. The on / off operation is stopped so that the supply of the drive current by oscillation of the resonance frequency is completely cut off.

That is, in the lamp protection circuit unit 40, when the overvoltage generated due to insufficient cooling time is not secured while the high voltage discharge lamp LAMP is not turned on, the first and second field effect transistors ( By stopping the switching operation of Q1) (Q2) to stop 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. You can do it.

According to the present invention as described above, when the overvoltage generated in the driving circuit portion of the high-pressure discharge lamp is detected in the state of damage or disconnection of the high-pressure discharge lamp or the state of insufficient cooling, the drive circuit portion of the lamp is triggered By stopping the driving of related circuit elements including the switching transistor for oscillation, it is possible not only to protect the related circuit elements and components constituting the ballast circuit of the high-voltage discharge lamp from overvoltage, but also to improve the reliability of the ballast circuit. The effect is that it is possible to improve.

Claims (3)

High-voltage discharge at the same resonance frequency according to the oscillation operation of the trigger signal generator and a trigger signal generator having a plurality of switching transistors are alternately and repeatedly switched according to the generation of reverse electromotive force of the switching transformer to perform the oscillation operation of the resonance frequency In the ballast circuit of a high-pressure discharge lamp having a lamp driving unit for driving the lamp lighting up, A high voltage pulse transformer for detecting an overvoltage generated from the lamp driver when the high voltage discharge lamp is not lit; A first lamp protection circuit for adjusting switching timings of the plurality of switching transistors when an overvoltage is detected from the high voltage pulse transformer; And a second lamp protection circuit for stopping switching driving of the plurality of switching transistors of the trigger signal generator by bypassing back electromotive force generated from the switching transformer when an overvoltage is detected from the high voltage pulse transformer. Protection circuit for electronic ballast of high voltage discharge lamp. The high voltage pulse of claim 1, wherein the first lamp protection circuit is connected to one end of the high voltage pulse transformer to adjust a switching timing, and the high voltage pulse according to a switching timing controlled by the capacitor and the variable resistor. And a transistor configured to be driven in response to an overvoltage from a transformer and to adjust switching timings of the plurality of switching transistors of the trigger signal generator, wherein the protection circuit for the electronic ballast of the high voltage discharge lamp is configured. 2. The second lamp protection circuit of claim 1, wherein the second lamp protection circuit is switched according to the turn-on of the die solution turned on when the overvoltage applied from the high voltage pulse transformer exceeds a predetermined value, And a transistor configured to bypass the generated counter electromotive force to stop switching driving of the plurality of switching transistors.