KR960010711B1 - Fluorescent lamp control circuit - Google Patents

Abstract

The circuit extends the life time of the product by controlling the pre-heating period for preventing the darkening of the fluorescent lamp according to the circumference temperature, and includes a 3 step time converter adjusting the pre-heating time according to the circumference temperature; a 3 step start controller generating a frequency control signal varying with the 3 steps by the control time of the time converter; a saw tooth wave generator generating a variable voltage signal and the wave by the frequency control signal; a voltage adjuster varying the voltage according to the variable voltage signal in order to adjust the dead time of a switch; a comparator generating the control signal for the dead time of the switch by comparing the outputs of the saw tooth wave generator and the voltage adjuster; an output means outputting the output signal corresponding to the controller; a overheat protector sensing the temperature of the switch to control this system "on/off"; a base voltage supplier providing the 3 step start reset signal for the 3 step time converter until the base voltage is supplied and providing the base power to parts except for the over heat protector when the power is supplied more then the fixed voltage.

Description

Fluorescent Ballast Control Circuit

1 is an overall configuration diagram of a fluorescent lamp ballast control circuit according to the present invention.

2 is an operational waveform diagram of a three-step start controller included in the control circuit of the present invention shown in FIG.

3 is a detailed circuit diagram of an overheat protection part, a 3-step start time variable part, a 3-step start control part, a sawtooth wave generation part and a voltage variable part included in the control circuit of the present invention shown in FIG.

4 is a graph showing the conversion of the output and the dead time of the comparator by the operation of the voltage variable unit according to the frequency at the three-step start in the present invention.

In general, in the fluorescent ballast control, the purpose of giving the preheating section in the initial starting section is to preheat the filament between both ends of the fluorescent lamp to prevent blackening caused by the discharge of the fluorescent lamp to extend the life of the fluorescent lamp.

In addition, the preheating section is substantially deeply related to the ambient temperature at which the fluorescent lamp is installed. In other words, if the ambient temperature of the fluorescent lamp is high, even if the preheating section is short, blackening may be prevented during the discharge of the fluorescent lamp. On the contrary, if the ambient temperature of the fluorescent lamp is lower than the room temperature, the blackening phenomenon should be prevented by making the preheating section longer. I can do it.

However, since the ambient temperature changes according to the season, giving a predetermined preheating section in the initial start section, the fluorescent ballast control is not efficient. In other words, if the preheating section is extended to prevent blackening in the entire temperature range, the discharge time of the fluorescent lamp will be the same as the time when the ambient temperature is low when the ambient temperature is high. Therefore, the fluorescent lamp is discharged late after the power switch is turned on. The inconvenience is that it will lose the advantages of the electronic ballast.

Accordingly, an object of the present invention is to provide a fluorescent lamp ballast control circuit capable of automatically adjusting a preheating section according to a change in ambient temperature.

In order to achieve the above object, the present invention provides a ballast control circuit of a fluorescent lamp controller which rectifies an input AC power source into a DC power source and then supplies a power source having a predetermined voltage converted by a system control unit composed of a converter to a fluorescent lamp through a switching element. And a means for sensing the ambient temperature of the fluorescent lamp and controlling the system control unit to automatically adjust the preheating section in the initial start section of the ballast control of the fluorescent lamp based on the detected ambient temperature. It provides a fluorescent ballast control circuit.

In addition, the fluorescent lamp ballast control circuit according to the present invention of the above configuration further detects the temperature state of the switching element and controls the drive of the system control unit based on the temperature state detection signal further means for preventing overheating of the switching element. Include.

Furthermore, in the fluorescent lamp ballast control circuit of the present invention, the control means for controlling the system control unit generates a time control signal for adjusting the preheating time of the fluorescent lamp based on the ambient temperature of the fluorescent lamp detected by the temperature sensor. A three-step start control section for generating a frequency control signal in which the frequency is changed in multiple steps from the initial start to three-step with time based on the time control signal from the three-step time converter; A sawtooth wave generator for generating a voltage variable signal at the same time based on the frequency control signal from the 3-step start controller and a sawtooth wave for adjusting the dead time of the switching element at the time of frequency change. A voltage variable section for varying the voltage according to the frequency change based on the voltage variable signal from the generator. A comparator for generating a control signal for adjusting the dead time of the switching element by comparing the output of the sawtooth generator and the output of the voltage varying part as inputs of one side and the other of the input, and being operated according to the control signal from the comparator and switching Output means for providing a corresponding output signal to the system control unit so that the dead time of the device can be adjusted, and to detect the temperature of the switching device to prevent overheating of the switching device, based on the sensed temperature signal 3-step By controlling the output signal of the time converter and the comparator, the overheat protection unit for controlling the driving of the system controller on / off, and the 3-step start reset signal are provided to the 3-step time converter until the reference voltage is supplied. When the predetermined voltage or more is supplied, the reference voltage supplying the reference voltage to each component other than the overheat protection part. It consists of benefits.

On the other hand, the 3-step time conversion unit employed in the control means according to the present invention is controlled to a predetermined constant preheating time when the ambient temperature of the fluorescent lamp is higher than the set reference temperature, and preheating in proportion to the ambient temperature when the ambient temperature is lower than the set reference temperature. Generates a time control signal for controlling the time to take longer.

Further, in the control means employed in the fluorescent lamp ballast control circuit of the present invention, the three-step start control section includes means for switching a change in time to a change in a constant voltage, and a means for adjusting the amount of current according to the switched voltage. And means for controlling the flow of the adjusted current amount for setting the changed preheating time, and means for comparing the reference voltage value and the value output by flow control.

Other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

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

FIG. 1 is an overall configuration diagram of a fluorescent lamp ballast control circuit according to the present invention. As shown in the figure, the ballast control circuit of the present invention includes an AC input rectifying end 100, a fluorescent lamp ballast system unit 200, and a signal controller. It consists of 300.

The AC input rectifier stage 100 converts the AC input to a DC output by the capacitor C ₀ of the input stage through the full bridge rectifier 110. The fluorescent ballast system unit 200 includes a system control unit 210 formed of a control transformer wound around one core, two switching elements 220 and 220 'connected to an output side of the system control unit 210, and four diodes D1 to D4. 4 capacitors C1 to C4 and a series connection of the resonant inductor Lr and the resonant capacitor Cr.

The fluorescent ballast system unit 200 having the configuration as described above zeros the two switching elements 220 and 220 'by the system controller 210 when an output is generated at the output terminal OUTPUT1.2 of the signal controller 300. Switch to voltage.

Referring to the form in which the switching elements 220 and 220 'are controlled by the system control unit 210, first, when the switching element 220 is in a conducting state, the other switching element 220' is maintained in a non-active state. When the resonant frequency is resonated, the two switching elements 220 and 220 'are turned off before the resonant half-cycle ends, and the switching elements 220' are conducted before the half-cycle current resonance starts, thereby forming a current resonant path. As this type of control occurs repeatedly, the switching elements 220 and 220 'are electrically connected to the diodes D1 or D2, respectively, resulting in zero voltage switching.

On the other hand, the signal control unit 300 included in the ballast control circuit of the present invention, as shown in Figure 1, for adjusting the preheating time of the fluorescent lamp based on the ambient temperature of the fluorescent lamp detected by the temperature sensor (TS) On the basis of the three-step time converting unit 310 for generating the time control signal g and the time control signal g from the three-step time converting unit 310, the frequency is three from the initial start according to time. Generating a sawtooth wave corresponding to the three-step start control unit 320 for generating a frequency control signal that is varied in multiple steps in a step, and the frequency control signal h from the three-step start control unit 320; The sawtooth wave generator 330 which generates the voltage variable signal k at the same time, and the voltage variable signal k from the sawtooth wave generator 330 to adjust the dead time of the switching elements 220 and 220 'when the frequency changes. According to the frequency change For controlling the dead time of the switching elements 220 and 220 'by comparing the voltage variable unit 340, the output of the sawtooth wave generator 330, and the output of the voltage variable unit 340 to one side and the other side thereof. A comparator 350 generating a control signal and an output signal corresponding to the system controller 210 are operated according to the control signal from the comparator 350 so that the dead time of the switching elements 220 and 220 'can be adjusted. In order to prevent overheating of the output unit 360 and the switching elements 220 and 220 ', the temperature of the switching element is sensed and the three-step time converter 310 and the comparator 350 are based on the sensed temperature signal. 3-step start reset to the over-temperature protection unit 370 for controlling the output signal of the system control unit 210 on / off and the 3-step time conversion unit 310 before the reference voltage is supplied. Provides a signal r and is set to a predetermined voltage or more When the feed is composed of a reference voltage supply unit 380 for supplying a reference voltage to the respective constituent members other than the over-temperature protection unit 370.

In the signal control unit 300 of the present invention having the configuration as described above, the reference voltage supply unit 380 having a UVLO, each component member except the overheat protection unit 370 when a certain voltage or more is supplied to this component member a reference voltage (V _ref) and supplying a reference voltage (V _ref) is supplied to step 3 until the start reset signal (r) because the 3-step time supplied to the conversion unit 310 when the start-up circuit Li 3-step start control is enabled.

Then, when the three-step start reset signal r is released while the reference voltage V _ref is supplied to each component except the overheat protection unit 370, the three-step start control unit ( The signal is controlled from the sawtooth wave generator 330 to the output stage OS 1.2 by the frequency control operation of 320.

2 shows an operation waveform diagram of a three-step start controller in the signal controller. As can be seen from the figure, the period t0 to t1 to which the reset signal r is applied is controlled at a frequency f1, and the frequency f1 is a frequency for preheating the filament of the fluorescent lamp to help discharge the fluorescent lamp. This must be satisfied.

In addition, the interval t1 to t2 decreases with a constant slope from f1 to f2, and this interval is for discharging the fluorescent lamp. In the case of stepped control in which the frequency is drastically reduced from the frequency f1 to f2 in this section, the frequency is drastically lowered so that a large discharge current flows and the resonant inductor Lr generates audible noise and is unreasonable to the system elements. This has the disadvantage of causing instantaneous power transfer.

Furthermore, the section t3 to t4 is a section that raises the frequency by giving a constant slope to prevent the dimming portion of the light suddenly before going to the dimming section for adjusting the illuminance of the fluorescent lamp. After the section t4 is a dimming section, the dimming frequency can be controlled from f2 to a higher frequency. On the other hand, the sawtooth wave generator 330 in the signal controller 300 generates the sawtooth wave at the frequency determined by the three-step start controller 320 based on the frequency control signal h from the three-step start controller 320. Done. In addition, the sawtooth wave generator 330 provides the voltage variable signal k to the voltage variable unit 340 which varies the voltage according to the change of frequency. Then, by displacing the positive potential in the comparator 350 compared with the sawtooth wave generated in the sawtooth wave generator 330, by adjusting the duty of the output of the comparator according to the frequency, the dead time (switching element) (220, 220 ') section is adjusted to be adjusted.

Next, the output of the comparator 350 includes two D flip-flops 362 and 364 and two AND gates 366 and 368 so that the dead time of the switching elements 220 and 220 'can be adjusted. ) Is input to the output unit 360 that provides an output signal corresponding to the system control unit 210.

More specifically, the output of the comparator 350 becomes the respective clock (CK, CK) inputs of the two D flip flops 362 and 364, and each of the two outputs Q, 1 and Q2 of the two D flip flops 362 and 364. , Q1, Q2) signals are ANDed together with Q1 * Q2 and Q1 * Q2 to obtain two output A and B signals, and the output Q1 of the D flip-flop 362 is connected to the D2 terminal of the D flip-flop 364. The output Q2 of the D flip flop 364 is connected to the D1 terminal of the D flip flop 362.

Here, the two output stages OS1 and 2 connected to the output sides of the two AND gates 366 and 368 are designed to match the output potential or the current size to control the system controller 210.

On the other hand, the overheat protection unit 370 in the signal control unit 300 detects the temperature by the temperature sensor (TS) attached to the switching elements 220 and 220 'for sensing the temperature of the switching elements 220 and 220' and ambient temperature. On the basis of the operating temperature range of the switching elements 220 and 220 ', when a temperature set to overheat is detected, a short-down signal (x, y) is output to the output of the 3-step time converter 310 and the comparator 350. The output is controlled so that the output OUTPUT 1.2 of the output stages OS1 and 2 is at the low level so that the operation of the fluorescent lamp ballast system unit 200 is stopped.

Then, when the temperature of the switching elements 220, 220 'is lowered to the set temperature according to the attention temperature, the overheat protection unit 370 dismantles the short down signal (x, y) to cause the signal control unit 300 to be driven again. do. At this time, the initial drive characteristic of the three-step start control unit 320 is three-step start driving.

On the other hand, the 3-step time converter 310 in the signal controller 300 performs a function of adjusting the time of the 3-step start controller 320 based on the ambient temperature sensed by the temperature sensor TS. do. That is, when the ambient temperature is below room temperature or becomes negative temperature, the preheating time of the fluorescent lamp should be longer than at room temperature. At this time, if the preheating time of the fluorescent lamp is not prolonged under the above circumstances, the discharge of the fluorescent lamp does not occur or the sufficient preheating time is not provided, and excessive power is transmitted at the moment of discharge, causing blackening, resulting in reduced light output or lifetime of the fluorescent lamp. This shortens the result.

Therefore, the three-step time conversion unit 310 according to the present invention, so that the above points can be eliminated, to control only a predetermined time above the reference temperature based on the set reference temperature, the temperature below the reference temperature The lower the value, the time t of the 3-step start control section 320 is controlled through the time control signal g which controls the longer time.

Substantially, the temperature sensor used in the overheat protection unit 370 or the three-step time conversion unit 310 uses NTC (NEGA TIVE TEMPERATURE COEFFFCIENT) in which the resistance decreases when the sensed temperature increases.

FIG. 3 shows a detailed circuit diagram of the overheat protection part, the 3-step start time variable part, the 3-stem start control part, the sawtooth wave generating part and the voltage variable part in the signal control part shown in FIG.

As shown in FIG. 3, the overheat protection unit 370 has a voltage source V1 independent of the reference voltage V _ref . Therefore, even if the reference voltage V _ref is shortened by the hysteresis of the UVLO, the V1 voltage source supplied to the overheat protection unit 370 is not shortened.

First, referring to the operation of the overheat protection unit 370, when the base potential Vs of the transistor Q10 that appears as the temperature sensor TS changes in temperature decreases as the temperature increases, I1 appearing on the base of the transistor Q4. It is compared with the voltage by I2. At this time, the potential of I1 * I2 is the voltage conversion value of the temperature set for temperature protection. Then, as compared, transistor Q8 is turned on so that transistor Q6 is turned on, and two transistors Q5 and Q7 are turned on by mirror operation of transistor Q6. Transistor Q7 acts as a signal for shorting down the reference voltage V _ref , and transistor Q5 flows the current IO made by (V1-Vbe Q1 / R1.) Current flowing through transistor Q5 (IO) raises the base potential of the transistor Q4, and this increased potential is substantially set according to the ambient temperature of the temperature sensor TS.

Next, the 3-step start controller 320 functions to adjust the frequency by adjusting the amount of current charged by the sawtooth generator 330 to the capacitor Ct. That is, as can be seen from FIG. 2, in the staring section t0, t1 is a capacitor whose current which is the sum of the current In set in the sawtooth wave generator 330 and the current I5 of the 3-step start controller 320 is a capacitor. The current charged in (Ct) is shown. In the period t1, t2 is the period until the voltage generated at the capacitor Cs conducts the transistor Q20 to the emitter current of the transistor Q20 to be I5, and at time t2, the transistor Q27 is not in operation. . In the period t2, t3 is a period in which only the current of the sawtooth wave generator 330 flows, and in the period t3, t4 is a period in which the transistor Q35, which has been in a non-active state, becomes a conductive state, and a voltage generated in the capacitor Cs. Is the interval until the emitter current of the transistor Q21 becomes Id which is the current flowing through the resistor R14 while the Vcs becomes high and the transistor Q21 is conducted. The current after the period t4 is the current in which the sum of Id and In charges the capacitor Ct.

On the other hand, in order to give the three-step start control unit 320 as described above the appropriate time period, the sections t1 and t3 can be set according to the potentials of Va and Vb represented by the three resistors R11, R12, and R13, The intervals t2 and t4 can also be changed by adjusting the sizes of the two resistors R7 and R8.

On the other hand, the three-step time converter 310 receives the Vs potential whose voltage is changed according to the temperature change as the base of the transistor q14, and varies the 30 step start time by the current control. When the temperature sensor TS is above a certain temperature, Vs becomes below a constant voltage, so that the current flowing through the resistor R5 is almost equal to the current flowing through the collector of the transistor Q16 by the current mirrors of the two transistors Q15 and Q16. Since the current is greater than I4, the transistor Q17 is turned off. Therefore, the current charged in the capacitor Cs becomes (Vref-Vbe Q18) / R6.

Then, when the temperature of the temperature sensor TS is lower than the constant temperature, Vs becomes high, and the current Ir5 flowing through the resistor R5 becomes smaller than I4, so that the current flowing through the transistor Q17 is Iq17 (I4-Ir5). Will flow). Therefore, the current charged in the capacitor Cs is reduced by Iq17 so that the Vcs potential has a gentler slope than when Iq17 is zero. The slope of the Vcs is proportional to the time of the 3-step start controller 320 due to the characteristics of the circuit. In other words, when the slope is substantially smooth, the time is controlled to be longer in proportion to it.

Next, as shown in FIG. 3, the voltage variable part 340 is configured of four transistors Q42, Q43, Q44, and Q45, and senses the amount of current charged by the capacitor Ct to determine the amount of Vr. By varying the voltage change, as shown in FIG. 4, the waveform diagram functions to adjust the duty of the comparator 350 output. In FIG. 4, (a) indicates a pulse output waveform, (b) indicates a comparator output waveform, and tpdtddtnd means dead time. This duty adjustment function of the voltage variable unit 340 is necessary to ensure the zero voltage switching operation of the switching elements 220 and 220 'when the fluorescent ballast system unit 200 is controlled from the initial starting to 3-step start. Therefore, in the sections t0 to t1 shown in FIG. 2, the duty width should be reduced so that the section in which the diode D1 or the diode D2 is conducted occurs in the section in which the two switching elements 220 and 220 'are turned off. .

Therefore, the present invention intends to obtain by the above-described operation process, that is, the control of the ballast lamp of the tongue.

As described above, according to the present invention, by effectively controlling the ballast of the fluorescent lamp by automatically adjusting the preheating section given in accordance with the change in the ambient temperature of the fluorescent lamp in order to prevent the blackening of the fluorescent lamp, the lifetime of the fluorescent lamp as well as the efficiency of use This has a promoting effect.

Claims (3)

A ballast control circuit of a fluorescent lamp controller which rectifies an input AC power into a DC power and supplies a power having a predetermined voltage converted by a system control unit configured of a converter to a fluorescent lamp through a switching element, wherein the ambient temperature of the fluorescent lamp is sensed. And means for controlling the system control unit to automatically adjust the preheating section in the initial start section of the ballast control of the fluorescent lamp based on the sensed ambient temperature, wherein the control means for controlling the system control section includes: temperature A three-step time converting unit generating a time control signal for adjusting the preheating time of the fluorescent lamp based on the ambient temperature sensed by the sensor; A three-step start control section for generating a frequency control signal in which a frequency is multi-step changed from an initial start to three-steps with time based on a time control signal from the three-step time conversion section; A sawtooth wave generator for generating a sawtooth wave corresponding to the frequency control signal from the three-step start controller and a voltage variable signal; A voltage variable unit for varying a voltage according to a frequency change based on a voltage variable signal from the sawtooth wave generator to adjust the dead time of the switching element at a frequency change; A comparator for generating a control signal for adjusting the dead time of the switching element by comparing the output of the sawtooth wave generator with the output of the voltage varying unit as one input and the other input; Output means which is operated according to a control signal from the comparator to provide a corresponding output signal to the system controller so that the dead time of the switching element can be adjusted; In order to prevent overheating of the switching device, the driving of the system controller is controlled on / off by sensing the temperature of the switching device and controlling output signals of the 3-step time converter and the comparator based on the sensed temperature signal. Overheat protection unit for; And providing a 3-step start reset signal to the 3-step time conversion unit before the reference voltage is supplied, and supplying a reference voltage to each of the component members other than the overheat protection unit when a predetermined voltage or more is supplied. Fluorescent lamp ballast control circuit comprising a supply unit. The method of claim 1, wherein the 3-step time converting unit controls the predetermined preheating time when the ambient temperature of the fluorescent lamp is higher than the set reference temperature, and controls the preheating time in proportion to the ambient temperature when the ambient temperature is lower than the preset reference temperature. Generating the time control signal for controlling to take longer. 2. The apparatus of claim 1, wherein the three-step start control section comprises means for switching a change in time to a change in a constant voltage, a number for adjusting the amount of current according to the switched voltage, and an adjustment for setting a changed preheating time. And a means for controlling the flow of the current amount and a means for comparing a reference voltage value with the flow-controlled output value.