CN104717814B - Integrated circuit controller for ballast - Google Patents

Abstract

The present invention is used for a ballast and has an integrated circuit controller for preheating/re-preheating a filament and controlling the lighting time, comprising a charging and discharging circuit coupled to a capacitor to provide a charging and discharging path for the capacitor. When there is no error in the integrated circuit controller, the capacitor will be charged, and when an error occurs during the operation of the lamp tube or the power is tripped, the capacitor will be discharged; a control circuit is coupled to the charging and discharging circuit to control the charging and discharging circuit to charge or discharge the capacitor; a comparison circuit is coupled to the charging and discharging circuit to compare the threshold voltage and the voltage signal of the capacitor, which is used to control the timing and provide a preheating signal and a lighting signal; a logic control circuit is coupled to and controls the control circuit, and is coupled to the comparison circuit to receive the preheating signal and the lighting signal, which is used to preheat the filament and light the lamp tube. The logic control circuit further receives a feedback voltage for overvoltage protection. Once the feedback voltage exceeds the threshold voltage of the logic control circuit, the capacitor is driven to discharge through the control circuit.

Description

Integrated circuit controller for ballast

This invention is a divisional application, original application number: 200710163689X, application date: October 18, 2007, invention name: integrated circuit controller for ballast

Technical field:

The present invention relates to a ballast, especially a ballast with preheating/reheating filament and control lighting time, and used for fluorescent tube or small fluorescent tube, which uses voltage feedback to adjust operating frequency and Over-voltage protection and an external capacitor for preheating/re-preheating filament and controlling lighting time.

Background technique:

Fluorescent tubes are the most widely used light source in people's daily life. Improving the efficiency of fluorescent tubes will save energy for a long time. In the current research and development, it is mainly aimed at how to improve the performance of the ballast of the fluorescent tube and save energy, and further preheat the filament before the lamp is lit, which will help the filament to generate free electrons more easily, and using this method to light the lamp can not only Reducing the lighting voltage at both ends of the cathode can increase the service life of the lamp tube, so many electronic ballasts or integrated circuit controllers now add the function of preheating the filament to make the lamp tube have a longer service life. But this approach leads to another problem of "reheating". Re-heating means that the ballast not only preheats the filament once in a short period of time when the power supply suddenly trips, because the filament is still at a high temperature of about 1000°K during this short period of time, and the short-term power supply trip will make the ballast restart Set its function and reheat the filament once more. In this way, the filament will be given energy twice, resulting in excessive preheating, and excessive preheating will reduce the service life of the lamp tube, so this situation must be avoided.

From the above design, it can be seen that for the filament, better preheating can reduce the lighting voltage and lighting time at both ends of the cathode. If the lighting time is too long, the lamp tube will generate high voltage during this period, which will affect the service life of the lamp tube, so this situation must also be avoided.

For the function of preheating the filament, most traditional electronic ballasts connect a capacitor in parallel with the lamp tube as a starting capacitor to achieve the purpose of preheating the filament before the lamp tube is lit. However, when the lamp tube is warming up, a glow current will be generated due to the voltage drop of the capacitor, and the glow current will also reduce the service life of the lamp tube.

Please refer to FIG. 1 , which is a circuit diagram of a series resonant circuit of a traditional electronic ballast with the function of preheating the filament. As shown in the figure, it uses an integrated circuit controller 2 to achieve the function of preheating the filament. The half-bridge inverter 3 is composed of two switches 31 and 32. The switches 31 and 32 are controlled by the signals S2 and S3 generated by the integrated circuit controller 2. The switches 31 and 32 are based on a resistor 12 and a capacitor. The switching frequency controlled by 14 complementarily switches on/off, and each of the on and off is about 50% of the duty cycle. An inductor 40, a capacitor 41 and a fluorescent tube 50 form a resonant circuit, and the fluorescent tube 50 is connected in parallel with a capacitor 51, which is used as a starting capacitor. A preheating circuit 1 is composed of a logic circuit 11 , a resistor 12 , a capacitor 14 and a switch 15 , and the switch 15 is connected in series with a resistor 13 and connected in parallel with the resistor 12 . When a switching signal S1 appears, the resistor 13 and the resistor 12 can be connected in parallel by controlling the switch 15 to control the preheating function with a high switching frequency. Before the lamp tube is lit, the logic circuit 11 will control the preheating time. In addition, the use of a high starting frequency can avoid stress on the filament during starting and reduce the lighting voltage of the lamp tube.

According to the above circuit, when the power supply of the input voltage DC BUS trips or the user switches the power switch instantaneously during the operation of the lamp tube, the integrated circuit controller 2 and the preheating circuit 1 will not be able to perform their functions, and will restart The filament is reheated in one go, so multiple preheats by giving the filament twice energy must be avoided. At the same time, the lighting time cannot be controlled at this moment. If the lighting time of the lamp tube 50 is too long, the cathodes at both ends of the lamp tube 50 will cause a high voltage drop at the same time, which will cause damage to the filament and reduce the use of the lamp tube. life. In this way, the above-mentioned situation must also be avoided.

Please refer to FIG. 2 , which is a circuit diagram of another conventional electronic ballast with preheating function. As shown in the figure, a capacitor 61 is coupled to the integrated circuit controller 2 for controlling the preheating time; a capacitor 62 is coupled to the integrated circuit controller 2 for controlling the lighting time. In this circuit, two additional capacitors must be used to control the preheating and lighting time.

Based on the problems of the above-mentioned conventional technology, the object of the present invention is to provide a ballast that can control the reheating and lighting time, and use a capacitor to generate the necessary signal. Another object of the present invention is to provide a high-efficiency and low-cost ballast. circuit.

Invention content:

One of the objectives of the present invention is to provide an integrated circuit controller for a ballast, which is used to control the time of preheating/reheating the filament and turning on the lamp.

One of the objectives of the present invention is to provide an integrated circuit controller of a ballast with high performance and low cost.

The invention provides an integrated circuit controller of a ballast, which includes a power supply circuit, and the power supply circuit is coupled to a power rectifier to provide power required by logic circuits or control circuits inside the integrated circuit controller. A charging and discharging circuit is coupled to a capacitor to provide a path for charging and discharging the capacitor, and is coupled to a control circuit and a comparison circuit. When there is no error in the integrated circuit controller, the capacitor is charged. When an error or power is generated during the operation of the lamp tube The capacitor is then discharged when tripped. The control circuit controls the charging and discharging circuit. The comparison circuit is coupled to the charging and discharging circuit and a logic control circuit to compare the output signal of the charging and discharging circuit, and provide a signal to the logic control circuit to determine the highest or lowest switching frequency, and provide a signal to the control circuit to control the capacitance of the capacitor charging time or discharging time. Both the logic control circuit and a frequency compensation circuit are coupled to a feedback control circuit to receive the lamp voltage, and the logic control circuit is coupled to the comparison circuit, the frequency compensation circuit, the control circuit and an oscillation circuit. Once the lamp voltage is higher than the threshold voltage of the logic control circuit, an overvoltage protection will be generated and the capacitor will be discharged through the control circuit.

Following the above, the frequency compensation circuit is coupled to the logic control circuit and the oscillation circuit, and the frequency compensation circuit can set the switching frequency of the integrated circuit controller according to the threshold voltage of the frequency compensation circuit and the voltage of the feedback control circuit, wherein the switching frequency will vary with As the voltage of the feedback control circuit increases, the switching frequency decreases as the voltage of the feedback control circuit decreases. The oscillating circuit is coupled to the logic control circuit, the frequency compensation circuit, a driving circuit and an adaptive zero-voltage switching circuit. The oscillating circuit has an internal maximum switching frequency limit and a minimum switching frequency limit, and provides the maximum switching frequency or the minimum switching frequency to the ballast Once the feedback voltage of the feedback control circuit changes or zero-voltage switching occurs during lamp operation, the frequency compensation circuit or adaptive zero-voltage switching circuit will change the switching frequency. The adaptive zero-voltage switching circuit is coupled to the oscillator circuit and the half-bridge inverter. The switching frequency increases when non-zero voltage switching occurs or the voltage of the feedback control circuit increases, and decreases as the voltage of the feedback control circuit decreases. The driving circuit is coupled to the oscillation circuit, and is coupled to the switch of the half-bridge inverter and a capacitor. The capacitor provides switching energy to switch the switch.

The beneficial effect of the present invention is that a ballast is provided, which can control the reheating and lighting time, and use a capacitor to generate necessary signals, and meanwhile provide a circuit with high efficiency and low cost.

Description of drawings:

Fig. 1 is a circuit diagram of a conventional electronic ballast;

Fig. 2 is a circuit diagram of another conventional electronic ballast;

Fig. 3 is the circuit diagram of ballast of the present invention;

Fig. 4 is the circuit diagram of the first embodiment of the integrated circuit controller of the ballast of the present invention;

Fig. 5 is the waveform diagram of the integrated circuit controller of the ballast of the present invention;

Fig. 6 is a waveform diagram of zero voltage switching of the present invention;

Fig. 7 is the waveform diagram of comparison logic and frequency compensation of the present invention;

Fig. 8 is the graph of the experimental result of ballast of the present invention;

Fig. 9 is the bode diagram of the resonant tank with the operating point of the lamp in the present invention;

10 is a circuit diagram of a second embodiment of the integrated circuit controller of the ballast of the present invention; and

FIG. 11 is a circuit diagram of a third embodiment of the integrated circuit controller of the ballast of the present invention.

Description of figure number:

1 Preheating circuit 2 Integrated circuit controller

3 half-bridge inverter 11 logic circuit

12 Resistor 13 Resistor

14 capacitor 15 switch

20 IC controller 20’ IC controller

20” IC Controller 21 Internal Bias Circuit

22 Charge and discharge circuit 23 Control circuit

24 Comparator circuit 25 Oscillation circuit

26 Logic control circuit 27 Frequency compensation circuit

28 Drive Circuit 29 Adaptive Zero Voltage Switching Circuit

31 High side switch 32 Low side switch

40 Inductance 41 Capacitance

50 Lamp 51 Capacitor

60 capacitor 61 capacitor

71 Voltage signal 72 Capacitance

81 Feedback signal 221 Control signal

222 Voltage signal 231 Control signal

241 Preheating signal 242 Lighting signal

243 Timing control circuit 251 Oscillation signal

261 Highest frequency signal 262 Frequency sweep signal

263 Overvoltage protection signal 271 Compensation signal

281 metal oxide semiconductor field effect transistor

282 metal oxide semiconductor field effect transistor

291 Non-zero voltage signal AGND Ground terminal

BS bootstrap terminal CAP capacitor terminal

DC BUS input voltage FB feedback terminal

fmax highest frequency fmin lowest frequency

fsw Switching frequency GND Ground terminal

HGND Bootstrap Ground High-Q High-Q

Low-Q Low Q HO high voltage side output

HV high voltage side output terminal IGN lighting signal

LO Low voltage side output PRH Preheating signal

S1 switching signal S2 switching signal

S3 switching signal V3 third threshold voltage

V4 fourth threshold voltage V5 fifth threshold voltage

Vcap capacitor voltage Vign second threshold voltage

Vprh The first threshold voltage VCC supply terminal

VFB feedback voltage VFC feedback voltage

t1 Preheating time t2 Lighting time

detailed description:

In order to have a further understanding and understanding of the features of the present invention and the achieved effects, a preferred embodiment and a detailed description are provided, as follows:

Please refer to FIG. 3 , which is a circuit diagram of the ballast of the present invention. As shown in the figure, a lamp 50 , an inductor 40 and a capacitor 41 are connected in series to form a resonant circuit, and a capacitor 51 is connected in parallel with the lamp 50 to form a starting capacitor. The light tube 50 can be a fluorescent light tube. The resonant circuit generates a sine wave voltage to drive the fluorescent tube 50 to operate. A switch 31 is connected in series with a switch 32 to form a half-bridge inverter 3 and is coupled to the resonant circuit. The switch 31 is a high-voltage side switch, coupled to an input voltage DCBUS of the power converter, and controlled by a switching signal S2 generated by a high-voltage side output terminal HO of an integrated circuit controller 20 . The switch 32 is a low-side switch, coupled to ground, and controlled by a switching signal S3 generated by a low-side output terminal LO of the integrated circuit controller 20 .

Referring again to FIG. 3 , a feedback terminal FB of the integrated circuit controller 20 is coupled to a feedback control circuit 8 to receive a feedback signal 81 for adjusting the switching frequency and the overvoltage of the lamp 50 during operation. Protect. The feedback control circuit 8 is coupled to the capacitor 41 , the lamp 50 and the ground to provide a feedback signal 81 through the feedback terminal FB, wherein the feedback signal 81 represents the voltage of the lamp. A diode 91 and a capacitor 9 form a charge pump circuit, and are coupled to a bootstrap terminal BS and a bootstrap ground terminal HGND of the integrated circuit controller 20 to provide a drive circuit 28 (as shown in FIG. 4 ). The required switching energy is used to switch the high-voltage side switch 31. A capacitor 72 is coupled to a capacitor terminal CAP and a ground terminal GND to provide a voltage signal 71 to the internal logic circuit of the integrated circuit controller 20, wherein the ground terminal GND is coupled to ground to provide a current return, and all The signal will be based on the ground terminal GND. A supply terminal VCC of the integrated circuit controller 20 is coupled to the input voltage DC BUS to provide the power required by the integrated circuit controller 20 .

Please refer to FIG. 4 , which is a block diagram of the first embodiment of the integrated circuit controller of the ballast of the present invention. As shown in the figure, an internal bias circuit 21 is coupled to the supply terminal VCC to provide a necessary power supply and a reference voltage required by the integrated circuit controller 20 . A charging and discharging circuit 22 is coupled to the capacitor terminal CAP to provide a charging and discharging path for the capacitor 72 to achieve the functions of preheating, lighting, operating time and reheating. The condition of the best preheated filament is related to the impedance ratio between the two impedances of the filament at room temperature and at the working temperature, which can be expressed as follows:

Among them, Th is the working temperature of the filament, Tc is the room temperature or the reference temperature, Rc is the resistance value of the filament at room temperature or the reference temperature, Rh is the resistance value of the filament at the working temperature, and the optimum preheating condition is that the coefficient is at Between 4 and 6.

The re-preheating function means that when the power supply trips and recovers for a short period of time, the filament is preheated again. During this period, the temperature of the filament is still at the working temperature, about 1000°K. The temperature of the filament cannot be lowered to room temperature within a short period of time when the power supply is tripped, so if the integrated circuit controller 20 executes the preheating function again, the filament will be given energy twice, which will affect the service life of the lamp tube 50. The relationship between filament temperature and impedance can be expressed as follows:

Rt＝Rc[1+α(Th-Tc)+β(Th-Tc) ² ]------------------(2)

Among them, Rt is the impedance value of the filament at temperature t, Rc is the impedance value of the filament at room temperature or at a reference temperature, α is the temperature coefficient of impedance, Tc is room temperature or reference temperature, β is the amplification factor and Th is the working temperature, For metallic conductors, β is negligible, so this equation can be rewritten as follows:

Rt＝Rc[1+α(Th-Tc)]----------------------------(3)

Therefore, for a filament, the resistance value increases with increasing operating temperature Th and decreases with decreasing operating temperature Th. Therefore, if the discharge slope of the capacitor 72 is controlled to match the slope of the temperature drop of the filament, the reheating time can be controlled and an appropriate energy can be provided to the filament, so as to avoid excessive preheating when the power supply trips in a short period of time. situation.

Referring again to FIG. 4 , the capacitor 72 is controlled by the charging and discharging circuit 22 . When the integrated circuit controller 20 has no error or no fault signal is triggered, a control circuit 23 generates a signal 221 and outputs it to the charging and discharging circuit 22 to control the charging and discharging circuit 22 to charge the capacitor 72 . The charging and discharging circuit 22 is coupled to a comparison circuit 24 and the control circuit 23, and is coupled to the capacitor 72 through the capacitor terminal CAP. When the integrated circuit controller 20 has no errors, the capacitor 72 is charged, and the voltage of the capacitor 72 increases gradually. When any fault signal is triggered or the power supply is tripped, the capacitor 72 will discharge, and the voltage of the capacitor 72 will gradually decrease with a slope corresponding to the decrease of the temperature of the filament.

Following the above, the comparison circuit 24 is coupled between the charging and discharging circuit 22 and a logic control circuit 26 , and the comparing circuit 24 receives a voltage signal 222 from the charging and discharging circuit 22 to be used according to a threshold voltage of the comparing circuit 24 and the voltage of the capacitor 72 Determine the warm-up time and lighting mode. Once the charging and discharging circuit 22 charges the capacitor 72 , the voltage signal 71 will gradually increase, and the voltage signal 222 is equivalent to the voltage signal 71 .

When the voltage signal 222 is lower than a first threshold voltage (Vprh) (as shown in FIG. 5 ), the comparator circuit 24 will generate a preheat signal (PRH) 241 and transmit it to the logic control circuit 26 to control an oscillation circuit. 25 generates an oscillating signal 251 with the highest frequency (fmax) (as shown in FIG. 5 ), and is used to control a driving circuit 28 to drive the half-bridge inverter 3 (as shown in FIG. 3 ). The oscillation signal 251 determines the switching frequency of the integrated circuit controller 20 of the ballast. Once the preheat signal 241 is generated, the integrated circuit controller 20 operates in a preheat mode. When the voltage signal 222 is lower than the first threshold voltage (Vprh), the preheating signal 241 can be "low voltage signal"; when the voltage signal 222 is higher than the first threshold voltage (Vprh), the preheating signal 241 can be "high" voltage signal".

When the voltage signal 222 continues to increase and exceeds the first threshold voltage (Vprh) and is lower than a second threshold voltage (Vign) (as shown in FIG. 5 ), the comparator circuit 24 will generate an ignition signal (IGN) 242 and It is transmitted to the logic control circuit 26 to control the oscillation circuit 25, and the oscillation circuit 25 will gradually reduce the frequency until a minimum frequency (fmin) limited by the integrated circuit controller 20 (as shown in FIG. 5 ). Once the lighting signal 242 is generated, the integrated circuit controller 20 will operate in the lighting mode, and the lamp must be turned on. When the lighting signal 242 is generated, if the lighting of the lamp tube 50 (as shown in FIG. 2 ) fails, or after the lighting signal 242 disappears, and the lighting of the lamp tube 50 is too long, the integrated circuit controller 20 will enter a failure mode for use in One point light failure protection. When the voltage signal 222 is between the first threshold voltage (Vprh) and the second threshold voltage (Vign), the lighting signal 242 can be a "low voltage signal"; when the voltage signal 222 exceeds the second threshold voltage (Vign), the lighting Signal 242 may be a "high voltage signal". When the voltage signal 222 is higher than the second threshold voltage (Vign) and the lighting signal 242 disappears, the integrated circuit controller 20 will operate in an operation mode, and the frequency is the minimum frequency (fmin). As mentioned above, the first threshold voltage (Vprh) is lower than the second threshold voltage (Vign), and the minimum frequency (fmin) is lower than the maximum frequency (fmax).

Referring again to FIG. 4 , the logic control circuit 26 and a frequency compensation circuit 27 are coupled to the feedback control circuit 8 (as shown in FIG. 3 ) via the feedback terminal FB to receive the feedback signal 81 of the feedback control circuit 8, And the logic control circuit 26 is also coupled to the control circuit 23 , the comparison circuit 24 and the oscillation circuit 25 . Once the preheating signal 241 is generated from the comparison circuit 24, the logic control circuit 26 will generate a highest frequency signal 261 and transmit it to the oscillation circuit 25 to control the oscillation circuit 25 to switch the half-bridge inverter 3 at the highest frequency through the drive circuit 28 (As shown in Figure 3). When the lighting signal 242 is generated from the comparison circuit 24, the logic control circuit 26 will generate a frequency scanning signal 262 to the oscillation circuit 25 to gradually reduce the switching frequency until the switching frequency reaches the lowest frequency. When the feedback signal 81 is higher than a third threshold voltage of a logic control circuit 26, the logic control circuit 26 will perform an overvoltage protection, and the logic control circuit 26 will generate an overvoltage protection signal (OVP) 263 and a control The signal 231 is used to stop the oscillation circuit 25 and control the charging and discharging circuit 22 through the control circuit 23 to discharge the capacitor 72 . The oscillation circuit 25 generates an oscillation signal 251 with a maximum frequency limit and a minimum frequency limit according to the maximum frequency signal 261 and the frequency scanning signal 262 respectively, so as to control the driving circuit 28 .

Referring again to FIG. 4 , the frequency compensation circuit 27 is coupled to the logic control circuit 26 and the oscillation circuit 25 . The feedback signal 81 entering the frequency compensation circuit 27 will be divided into a fourth threshold voltage (V4) and a fifth threshold voltage (V5), wherein the fourth threshold voltage (V4) and the fifth threshold voltage (V5) are respectively low threshold voltage with a high threshold voltage. The frequency compensation circuit 27 generates a compensation signal 271 to the oscillation circuit 25 to adjust the switching frequency. The oscillation circuit 25 generates an oscillation signal 251 according to the compensation signal 271 to control the driving circuit 28 . The switching frequency increases to a maximum frequency (fmax) as the feedback signal 81 increases, and decreases to a minimum frequency (fmin) as the feedback signal 81 decreases. The third threshold voltage ( V3 ) is higher than the fourth threshold voltage ( V4 ) and the fifth threshold voltage ( V5 ), and the fourth threshold voltage ( V4 ) is lower than the fifth threshold voltage ( V5 ).

Referring again to FIG. 4 , the driving circuit 28 is coupled to the oscillation circuit 25 and provides high-side driving and low-side driving for the half-bridge inverter 3 (shown in FIG. 3 ), and provides energy required by the high-voltage side. The driving circuit 28 receives the oscillating signal 251 to generate switching signals S2 and S3 for controlling the high-side switch 31 and the low-side switch 32 through the high-side output terminal HO and the low-side output terminal LO respectively (as shown in FIG. 3 ). The capacitor 9 (as shown in FIG. 3 ) is coupled to the driving circuit 28 via the bootstrap terminal BS and the bootstrap ground terminal HGND to provide energy required by the high-side switch 31 .

Referring again to FIG. 4 , an adaptive zero-voltage switching (ZVS) circuit 29 is coupled to the high-side switch 31 and the low-side switch 32 of the half-bridge inverter 3 via the bootstrap ground terminal HGND (as shown in FIG. 3 ), If a non-zero voltage switching occurs during lamp operation, the adaptive zero voltage switching circuit 29 will detect the non-zero voltage switching. The non-zero-voltage switching means that when the low-voltage side switch 32 is turned on, the voltages of the high-voltage side switch 31 and the low-voltage side switch 32 of the half-bridge inverter 3 are not zero voltage, so the adaptive zero-voltage switching circuit 29 is coupled to The half-bridge inverter 3 is used to detect the voltages of the high-side switch 31 and the low-side switch 32 when the low-side switch 32 is turned on. Once the non-zero voltage switching occurs, the adaptive zero voltage switching circuit 29 will generate a non-zero voltage signal 291 to the oscillation circuit 25 to control the oscillation circuit 25 to increase the switching frequency until returning to zero voltage switching.

Please refer to FIG. 5 , which is a waveform diagram of the integrated circuit controller of the present invention. 3 and 4 together, wherein, Vcap is the voltage across the capacitor 72 (as shown in FIG. 4 ), power is the power signal when the power is turned on, and PRH is the preheating signal 241 (as shown in FIG. 4 ). ), IGN is the lighting signal 242 (as shown in FIG. 4 ), fsw is the switching frequency, and the filament temperature is the filament temperature during the operation of the lamp tube. When the power is turned on, the charging and discharging circuit 22 (as shown in FIG. 4 ) will charge the capacitor 72, and the voltage of the capacitor 72 will gradually increase. When the voltage Vcap of the capacitor 72 is lower than the first threshold voltage (Vprh) of the comparison circuit 24 (as shown in FIG. 4 ), the comparison circuit 24 will generate a preheat signal (PRH) 241 to enter the preheat mode and preheat The time is denoted as t1. During the warm-up time (t1), the switching frequency operates at the highest frequency (fmax), and the filament temperature gradually increases to the operating temperature Th.

Following the above, when the voltage (Vcap) of the capacitor 72 continues to increase and is lower than the second threshold voltage (Vign) of the comparison circuit 24, the comparison circuit 24 will generate a lighting signal (IGN) 242 to enter the lighting mode, and the lighting time indicates is t2, the switching frequency will decrease until it reaches the minimum frequency (fmin) during the lighting time (t2). When the voltage (Vcap) of the capacitor 72 is higher than the second threshold voltage (Vign), it means that the lamp 50 operates in the operation mode (as shown in FIG. 3 ) during the operation time (t3), and the switching frequency is in this period. Minimum frequency (fmin) during time (t3) unless a non-zero voltage occurs.

Following the above, when the power supply is tripped within a short time (t4), the temperature of the filament will drop to the voltage of the capacitor 72, and the oscillator circuit 25 will be stopped. When the power supply trips, if the voltage discharge slope of the capacitor 72 is equivalent to the temperature drop of the filament, after the power supply is restored, the state of the filament can be obtained according to the voltage of the capacitor 72 and the re-preheating time or re-lighting time can be controlled, wherein re-preheating The time and relighting time are denoted as t1' and t2', respectively. The switching frequency remains at the highest frequency (fmax) during the reheating time (t1'), and the switching frequency decreases until the lowest frequency (fmin) during the relighting time (t2'). When the power supply is completely cut off at time (t6), the voltage (Vcap) of the capacitor 72 will be discharged to zero to start the next operation cycle of the lamp.

Please refer to FIG. 6 , which is a waveform diagram of the ZVS of the present invention. If non-ZVS occurs, the adaptive ZVS circuit 29 (as shown in FIG. 4 ) will adjust the switching frequency until the ZVS is restored, and maintain the switching frequency.

Please refer to FIG. 7 , which is a waveform diagram of the comparison logic and frequency compensation of the present invention. VFB shown in the figure is the feedback voltage of the feedback terminal FB (as shown in FIG. 4 ), which is the feedback signal 81 (as shown in FIG. 4 ). VFC is the voltage divided by the feedback voltage through the frequency compensation circuit 27 (as shown in FIG. 4 ). As mentioned above, the feedback terminal FB has two functions, namely overvoltage protection and switching frequency adjustment, and is used for the logic control circuit 26 and the frequency compensation circuit 27 (as shown in FIG. 4 ). The feedback terminal FB has three threshold voltages, one is the threshold voltage (V3) of the logic control circuit 26 for overvoltage protection, and the other is the threshold voltage (V4) and (V4) of the frequency compensation circuit 27 for adjusting and setting the switching frequency ( V5).

Following the above, once the feedback signal 81 exceeds the third threshold voltage ( V3 ) of the logic control circuit 26 , overvoltage protection will occur, and the integrated circuit controller 20 (as shown in FIG. 3 ) will enter a failure mode. After the feedback signal 81 enters the frequency compensation circuit 27, it will be divided into the fourth threshold voltage (V4) and the fifth threshold voltage (V5) for switching frequency compensation, and the frequency compensation circuit 27 can also be based on the fourth threshold voltage The feedback voltage between the voltage ( V4 ) and the fifth threshold voltage ( V5 ) and the highest frequency and the lowest frequency of the oscillation circuit 25 are used to set the switching frequency.

Please refer to FIG. 8 , which is a graph of the experimental results of the ballast of the present invention. As shown in the figure, the relationship curve among the power output, the light output and the switching frequency is bell-shaped, that is, the light output and the power output do not increase with the switching frequency, and have a maximum value. The right side of the maximum value is a stable working area, and the resonant ballast usually operates in this area, and the left side of the maximum value is an unstable working area, because this working area is easy to eliminate the lamp tube 50 (as shown in Figure 3). arc, so the ballast should avoid operating in this area.

Please refer to FIG. 9 , which is a Bode plot of the resonant tank with the operating point of the lamp according to the present invention. As shown in the figure, the switching frequency starts at a higher frequency and gradually decreases until the lamp is lit. During the frequency reduction, the switching frequency must pass through the high-Q region (High-Q) of the resonant circuit to provide for the lamp to light. energy required. After the lamp is lit, the switching frequency will be reduced to the required frequency and the resonant circuit will operate in the low-Q region (Low-Q) to stabilize the arc of the lamp.

Please refer to FIG. 10 , which is a circuit diagram of the second embodiment of the integrated circuit controller of the present invention. As shown in the figure, most of the internal circuits of the integrated circuit controller 20' of this embodiment are the same as those of the integrated circuit controller 20 of the first embodiment, so details will not be repeated here. The main difference between the integrated circuit controller 20 of the first embodiment and the integrated circuit controller 20' of this embodiment is that the switches 31 and 32 of the integrated circuit controller 20 of the first embodiment are respectively made of metal oxide semiconductor field effect transistors ( MOSFETs) 281 and 282 are replaced and disposed in the integrated circuit controller 20'. The metal oxide semiconductor field effect transistor 281 is coupled to a high voltage side output terminal HV, which is coupled to the input voltage DC BUS (as shown in FIG. 3 ), and the metal oxide semiconductor field effect transistor 282 is coupled to a ground terminal AGND, which is coupled to Connect to ground. The MOSFETs 281 and 282 are connected in series and coupled to the driving circuit to minimize the circuit board area of the ballast.

Please refer to FIG. 11 , which is a circuit diagram of a third embodiment of the integrated circuit controller of the present invention. As shown in the figure, most of the internal circuits of the integrated circuit controller 20" of this embodiment are the same as those of the integrated circuit controller 20' of the second embodiment, so details are not repeated here. The integrated circuit controller of the second embodiment The main difference between the device 20" and the integrated circuit controller 20' is that a timing control circuit 243 replaces the capacitor 72 and the charging and discharging circuit 22 for the control of preheating, electric light and operation time, and its functions are the same as those before the present invention The above function, therefore, the control circuit 23 is coupled to the timing control circuit 243 and controls the timing control circuit 243 . The timing control circuit 243 has an internal preheating time t1 and a lighting time t2 based on a timing/counting circuit (not shown), so as to provide a preheating signal 241 and a lighting signal 242 to the logic control circuit 26 for preheating Control with lighting mode.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. All equivalent changes and modifications are done according to the shape, structure, characteristics and spirit described in the scope of the claims of the present invention. , should be included in the scope of the claims of the present invention.

Claims (15)

1. a kind of integrated circuit controller of stabilizer, it is characterised in that it is included:

One oscillating circuit, produce an oscillation signal；

One drive circuit, the switching frequency of the integrated circuit controller of the stabilizer is determined according to the oscillation signal；

One sequential control circuit, the slope that a filament temperature of a fluorescent tube reduces is matched with, a preheating signal is produced, with control One preheating time；

One control circuit, to control the sequential control circuit；And

One logic control circuit, couple and control the control circuit, and couple the sequential control circuit, receive SECO electricity The preheating signal on road, to preheat a filament of the fluorescent tube with controlling the oscillating circuit.

2. integrated circuit controller as claimed in claim 1, it is characterised in that the logic control circuit is according to the preheating signal The oscillating circuit is controlled, the oscillation signal of tool one highest frequency limitation is produced, controls the switching frequency to operate in a most high frequency Rate.

3. integrated circuit controller as claimed in claim 1, it is characterised in that the sequential control circuit stops the preheating signal And a lighting signals are produced, and the logic control circuit receives the lighting signals, with to the fluorescent tube lighting.

4. integrated circuit controller as claimed in claim 3, it is characterised in that the logic control circuit is according to the lighting signals The oscillating circuit is controlled to produce the oscillation signal of tool one low-limit frequency limitation, to reduce the switching frequency until the switching frequency Untill being reduced to a low-limit frequency.

5. integrated circuit controller as claimed in claim 4, it is characterised in that the lighting signals stop and the switching frequency is The low-limit frequency.

6. integrated circuit controller as claimed in claim 3, it is characterised in that when the fluorescent tube lighting fails, interrogated in the lighting Number disappear after, start a lighting unsuccessfully protect.

7. integrated circuit controller as claimed in claim 1, it is characterised in that the logic control circuit has a threshold voltage And a feedback signal of a feedback control circuit of the stabilizer is received, to an overvoltage protection, the feedback signal is higher than should During the threshold voltage of logic control circuit, the logic control circuit stops the oscillating circuit.

8. integrated circuit controller as claimed in claim 1, it is characterised in that further include:

One frequency compensated circuit, there is a low threshold voltage and a high threshold voltage, and couple the feedback control of the stabilizer Circuit, to receive a feedback signal, and control the vibration electric according to the feedback signal, the low threshold voltage and the high threshold voltage Road, determine the switching frequency and a frequency compensation.

9. integrated circuit controller as claimed in claim 8, it is characterised in that the frequency compensated circuit splits the feedback signal Between the low threshold voltage and the high threshold voltage.

10. integrated circuit controller as claimed in claim 1, it is characterised in that further include:

One adaptability Zero voltage switching circuit, couples the multiple switch of the stabilizer, and a low-side switch of the plurality of switch is led When logical, the adaptability Zero voltage switching circuit detects the voltage of the plurality of switch, and the voltage of the plurality of switch is not zero and this is low When pressing side switch conduction, the adaptability Zero voltage switching circuit controls the oscillating circuit, to adjust the switching frequency until this is more Untill the voltage zero of individual switch.

11. integrated circuit controller as claimed in claim 10, it is characterised in that the adaptability Zero voltage switching circuit is in this When low-side switch turns on, a high side switch of the plurality of switch and the voltage of the low-side switch are detected.

12. integrated circuit controller as claimed in claim 10, it is characterised in that the adaptability Zero voltage switching circuit is in this When the voltage of multiple switch is not zero and non-zero voltage switching occurs, the switching frequency is adjusted.

13. integrated circuit controller as claimed in claim 1, it is characterised in that further include:

One internal bias voltage circuit, an input voltage is coupled, to provide power supply.

14. integrated circuit controller as claimed in claim 1, it is characterised in that the multiple switch of the stabilizer is respectively one Low-side switch and a high side switch, to be used as a half bridge inverter.

15. integrated circuit controller as claimed in claim 1, it is characterised in that the multiple switch of the stabilizer is built into this Integrated circuit controller.