KR100259186B1 - Power stabilization circuit for lamp - Google Patents

Abstract

PURPOSE: A power stabilizing circuit of a lamp is provided to prevent a heat from being generated in a switching element and improve reliability of a transistor by operating a protection circuit. CONSTITUTION: A frequency generating part outputs two square wave pulses having different time gaps when a power is supplied through the first transducer. A current limiting part supplies a limited current by performing a switching operation according to the square wave pulse output form the frequency generating part. An inductor(T10) detects a current flowing when a fluorescent lamp is normally or abnormally operated. A second side inductor outputs a voltage organized according a current flowing the inductor. A lamp protecting part rectifies the organized voltage supplied form the second side inductor and operates or stops the frequency generating part according the rectified voltage. When the fluorescent lamp is normally turned on, the current flowing the inductor is steady and the DC voltage organized in the inductor is transferred to a diode.

Description

Power stabilization circuit of lamp

The present invention relates to a power supply stabilization circuit for stably supplying or interrupting power to a lamp when a preheating current is applied to the lamp and then a discharge voltage is applied to light the lamp, but the lamp is not lit due to the end of the lamp's life. In particular, the present invention relates to a power supply stabilization circuit of a lamp that ensures reliable separation by minimizing the stress of a circuit by clearly distinguishing a signal generated during abnormal operation and abnormal operation such as the end of a load.

1 is a conventional lamp driving circuit diagram. As shown in FIG. 1, a rectified and smoothed and smoothed voltage is obtained by using a primary transformer T1 for boosting an input power and a diode and a capacitor connected to the primary transformer T1. A first power supply unit 10 for supplying a line voltage, a secondary transformer T1a for supplying a voltage induced during operation of the primary transformer T1, and a diode connected to the secondary transformer T1a; A second power supply 20 for rectifying and smoothing the capacitor and supplying the smoothed voltage, and a frequency generator for outputting different driving wave pulses with time difference when the power is supplied from the second power supply 20 ( 30), the current limiting unit 40 for limiting the supply current by switching according to the driving wave pulse generated in the frequency generator 30, and the waveform of the current supplied from the current limiting unit 40 as a sine wave Choke inductor (T2) to make, and the cho A fluorescent lamp 50 which is turned on or off by charging and discharging by a current supplied from an inductor T2, and is connected between the first power supply unit 10 and the current limiting unit 40, and the fluorescent lamp 50 ) Is configured as a thermal protector 60 that cuts off the line voltage when it is mis-charged or not lit due to the end of the load.

Looking at the prior art configured in this way in detail as follows.

When the power is input, the input power is boosted by the primary transformer T1 and provided to the first diode D1 of the first power supply unit 10.

Then, when the first diode D1 operates, the line voltage is increased by the step-up inductance value of the primary transformer T1.

The line voltage is smoothed by the first capacitor C2 and transferred to the thermal protector 20.

In this case, the voltage induced by the secondary transformer T1a is transferred to the second diode D2 of the second power supply 20, and accordingly, the second diode D2 operates to convert the induced voltage into a first capacitor. To C1).

Accordingly, the first capacitor C1 supplies a DC voltage obtained by performing a smooth operation to the frequency generator 30 by limiting a current through a resistor R1 connected in series with the first capacitor C1.

Then, the frequency generator 30 generates a driving pulse to its output terminals O1 and O2 using the voltage supplied from the first capacitor C1 as a power source.

The driving pulse generated at this time is controlled so that the switching transistors Q1 and Q2 can switch alternately.

Therefore, when the first switching transistor Q1 is turned on and the second switching transistor Q2 is turned off, current supplied through the first diode D1 and the thermal protector 60 is transferred through the first switching transistor Q1. It is supplied to the choke inductor T2.

When the first switching transistor Q1 is turned off and the second switching transistor Q2 is turned on, the current supplied through the first diode D1 and the thermal protector 60 is cut off, and the choke inductor T2 is turned off. The current supplied to the circuit is bypassed to the ground side through the second switching transistor Q2.

As a result, current is limited to the choke inductor T2.

At this time, the square wave switched by the switching transistors Q1 and Q2 becomes a sine wave in the choke inductor T1a.

The sinusoidal current passes through the first filament F1 of the fluorescent lamp 50, passes through the third capacitor C3, and is then preheated while passing through the second filament F2, and then discharged from the third capacitor C3. Lights up by.

Then, when the fluorescent lamp 50 is incorrectly connected or does not turn on due to the end of load, high heat (about 100 degrees) is generated in the switching transistors Q1 and Q2, and the heat connected in series to the first diode D1 is generated by the heat. The protector 60 senses heat and cuts off the line voltage.

When the heat of the thermal protector 60 cools down, it is connected to the line voltage again to perform the protection operation of the circuit.

Eventually, the thermal protector 60 is connected to the line voltage in series to sense heat to cut off the line voltage when the predetermined value or more, and to connect the line voltage again when the heat cools to protect each circuit.

However, in the prior art as described above, if the lamp is not turned on at the end of the fluorescent lamp load, the operating frequency is not matched between the lamp loads, and the resonance is turned off. As a result, the switching transistor of the current limiting unit does not achieve the proper switching operation. The thermal protector is used to cut off the circuit. Usually, it is operated when 85 ℃ to 100 ℃ heat is generated, which causes a problem in the reliability of the transistor and does not sense the heat unless the thermal protector is tightly attached to the switching transistor (Q1). As a result, the thermal protector does not operate, and there is a risk of the switching transistors Q1 and Q2 being burned out.

Accordingly, an object of the present invention for solving the conventional problems as described above is to provide a power supply stabilization circuit of a lamp to ensure the reliability of the transistor by operating the protection circuit without generating heat to the switching element.

1 is a conventional lamp driving circuit diagram.

Figure 2 is a circuit diagram of a power supply stabilization circuit of the lamp of the present invention.

*** Explanation of symbols for main parts of drawing ***

100: lamp protection unit 200: frequency generator

300: current limiting unit 400: lamp

F1.F2: Filament T1: Primary Transformer

T10: Inductor ZD: Zener Diode

The present invention for achieving the above object is a frequency generator for outputting a square wave pulse having a different time difference when the power supply through the primary transformer, and performing a switching operation according to the square wave pulse output from the frequency generator to limit the current A current limiter for supplying, an inductor for detecting a current flowing in a normal or abnormal operation of the fluorescent lamp, a secondary inductor for outputting an induced voltage according to the current flowing in the inductor, and an insulated supply from the secondary inductor And a lamp protection unit configured to rectify the voltage and to operate or cut off the frequency generator in accordance with the rectified voltage.

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

FIG. 2 is a configuration diagram of a power stabilization circuit of a lamp according to the present invention. As shown therein, a frequency generator 200 outputting two square wave pulses having different time differences when power is supplied through a primary transformer T1. ) And a current limiting unit 300 for supplying a limited current by performing a switching operation according to the square wave pulse output from the frequency generator 200, and detecting a current flowing in a normal or abnormal operation of the fluorescent lamp 400. Rectifies the inductor T10, the secondary side inductor T10a outputting the induced voltage according to the current flowing in the inductor T10, and the induced voltage supplied from the secondary side inductor T10a, and the rectified voltage. According to the configuration of the lamp protection unit 100 to operate or cut off the frequency generator 200.

Referring to the operation and effect of the present invention configured as described in detail as follows.

When the fluorescent lamp 400 is normally turned on, the current flowing through the inductor T10 is constant, so that an AC voltage induced in the inductor T10a is transmitted to the diode D10.

Then, the diode is clamped by the diode D10, the current is limited by the resistor R12 of the lamp protection unit 100, and the voltage is distributed by the parallel diode R13 to charge the capacitor C13.

Even when charged in the capacitor C13 and rectified by direct current, the zener diode ZD is blocked without conduction.

Therefore, the power supply control transistor G3 is turned off.

Accordingly, the current through the diode D10 is supplied to and driven by the frequency generator 200 through the resistor R11.

When the frequency generator 200 is driven, a time-wave square wave pulse alternately turns on or off the field effect transistors G1 and G2 of the current limiter 300.

As the field effect transistors G1 and G2 are alternately switched, current through the primary transformer T1 and the diode D1 is limited and supplied to the inductor T10.

Then, the inductor T10 outputs a current waveform by making a sine wave.

The sinusoidal current passes through the first filament F1 of the fluorescent lamp 50 and passes through the third capacitor C3, and is then preheated while passing through the second filament F2. It is lit by discharge.

Then, when the fluorescent lamp 50 is incorrectly connected or does not discharge due to the discharge of the lamp due to the end of the load, the current does not flow from the filament F1 to the filament F2, but all flows to the capacitor C5.

At this time, more current flows in the inductor T10 than usual, and the voltage induced in the inductor T10a is also induced larger than in normal lighting.

The largely induced AC voltage is clamped in the diode D10, and when the current is limited in the resistor R12 of the lamp protection unit 100 and the voltage is distributed in the resistor R13, the zener is charged and discharged when the capacitor C13 is discharged. The diode ZD is sufficiently conducted.

The voltage transferred through the zener diode ZD is charged in the capacitor C14 and then discharged.

The discharged voltage turns on the power control transistor G3.

Therefore, the voltage supplied to the frequency generator 200 through the diode D10 and the resistor R11 is bypassed to the ground side through the power control transistor G3 to make zero potential.

Then, since the frequency generator 200 stops the operation and does not output the square wave pulse, the field effect transistors G1 and G2 of the current limiter 300 stop the switching operation so that no current flows to the inductor T10.

Then, no voltage is induced to the inductor T10a to return to the initialization state.

This operation is repeated to operate the lamp protection unit 100 without generating heat to the field effect transistors G1 and G2 elements of the current limiting unit 300 to ensure reliability.

Accordingly, the present invention ensures a distinction between signals that are induced during abnormal operation and abnormal operation, such as incorrect wiring of the fluorescent lamp or end of load, so as to minimize the stress of the circuit to ensure reliability, and to stabilize the power supply to the lamp. It has the effect of being able to supply with.

Claims (3)

A frequency generator for outputting square wave pulses having a different time difference when the power is supplied through the primary transformer, a current limiting unit for supplying a limited current by switching according to the square wave pulses output from the frequency generator, and a fluorescent lamp The inductor for detecting the current flowing in the normal or abnormal operation of the secondary, the secondary inductor for outputting the induced voltage according to the current flowing in the inductor, and the rectified voltage supplied from the secondary inductor is rectified to the rectified voltage And a lamp protection unit configured to operate or cut off the frequency generator. The power supply stabilization circuit of claim 1, wherein the current limiting unit is formed of a field effect transistor. The method of claim 1, wherein the lamp protection unit comprises a resistor, a capacitor and a zener diode for charging, discharging and rectifying the input voltage, and a power control transistor for turning on or off in accordance with the output of the zener diode to control the operation of the frequency generator. The power stabilization circuit of the lamp, characterized in that.

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