WO1994023551A1

WO1994023551A1 - New fluorescent starter

Info

Publication number: WO1994023551A1
Application number: PCT/US1994/002989
Authority: WO
Inventors: Chao-Cheng Lu
Original assignee: Idea Inc; Lu Chao Cheng
Priority date: 1993-04-05
Filing date: 1994-03-21
Publication date: 1994-10-13

Abstract

Disclosed is a fluorescent starter consisted of a master switch circuit (400), an ignition circuit (300), and a time control circuit (200), the time control circuit being coupled to the ignition circuit by a photo coupler, the ignition time of the ignition circuit being synchronous to the peak value of the heating current.

Description

NEW FLUORESCENT STARTER

BACKGROUND OF THE INVENTION

The present invention relates to a fluorescent starter, and more specifically to an electronic fluorescent starter which accurately controls the heating time and the absolute synchronizing fire point for instant ignition with less power consumption.

The principle of the heating of the conventional fluorescent starters is to define one half cycle of AC power supply and to use its electric energy for starting the other half cycle. The principle of the ignition of the conventional fluorescent starters is to use resistors and capacitors as the time constant for controlling the ignition time. Therefore, resistors and capacitors are commonly used in conventional fluorescent starters for time constant control during heating and ignition. Because the value of resistors and capacitors may vary quickly, it is difficult to accurately control the heating time and the ignition time. Therefore, the fluorescent lamp may be overheated, inaccurately ignited, or over-ignited, causing waste of power supply and shortening of the service life of the fluorescent lamp. This is the reason why the electronic fluorescent starters are not popularly accepted.

SUMMARY OF THE INVENTION

The major object of the present invention is to provide a fluorescent starter which eliminates the aforesaid drawbacks by accurately controlling the heating time and the absolute synchronizing fire point. According to the preferred embodiment of the present invention, the fluorescent starter is comprised of a time control circuit, a master switch circuit, and an ignition circuit. The master switch circuit is comprised of a darlington circuit constructed according to the SCR control circuit of US Pat. No. 5,122,695, the GTO Thyristor control circuit of US Pat. No. 4,918,340 for heating switch control.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of a fluorescent starter according to the present invention;

Fig. 2 is a circuit diagram of the fluorescent starter;

Fig. 3 is a circuit diagram of an alternate form of the time control circuit of the circuit shown in Fig. 2;

Fig. 4 is a waveform chart of the voltage between the contacts A and B in Figs. 2 and 3;

Fig. 5 is a circuit diagram of another alternate form of the time control circuit; and

Fig. 6 is a circuit diagram of an alternate form of the fluorescent starter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Fig. 1, a fluorescent starter 2000 is coupled to a fluorescent lamp device 1000 to control its operation. The fluorescent starter 2000 is comprised of a time control circuit 200, a master switch circuit 400, and an ignition circuit 300.

Referring to Fig. 2, the time control circuit 200 is comprised of a rectifier diode 201, a time constant resistor 202, a zener diode 204, a time constant capacitor 203, a discharge resistor 207, a limit current resistor 205, and a photo coupler 206. The ignition circuit 300 is comprised of a diode 301, the photo coupler 206, a phase control resistor 302, a phase control capacitor 303, and a transistor 304. As indicated, the ignition circuit 300 and the time control circuit 200 commonly use the photo coupler 206 for operation. The time control circuit 200 uses the input terminal of the photo coupler 206 while the ignition circuit 300 uses the output terminal of the photo coupler 206. The master switch circuit is comprised of a darlington circuit consisted of transistors 402 and 403. The darlington circuit is also an invention of the present invention under U.S. Pat. Nos. 4,918,314; 5,122,695. The fluorescent lamp device 1000 is comprised of a fluorescent lamp 102 and a ballast 101. In contrary to the normal open switch circuit of the prior art fluorescent lamp switch, the darlington circuit of the master switch circuit 400 is a normal close switch circuit for heating operation.

Referring to Fig. 2 again, when contact B is at the AC positive half cycle, positive voltage is connected to charge the rectifier diode 201, the time constant resistor 202, and the time constant capacitor 203. As the voltage of the time constant capacitor 203 is boosted over the breakdown voltage of the zener diode 204, current passes through the limit current resistor 205 to the input terminal of the photo coupler 206, causing the light emitting diode (LED) to give light. At the same time, the collector and the emitter of the transistor at the output end of the photo coupler 206 are electrically connected. The voltage at the two opposite ends of the time constant capacitor 203 may not become higher than the breakdown voltage of the zener diode 204 during the positive half cycle. It may become higher than the breakdown voltage of the zener diode 204 after two or more cycles. This cycles within which the voltage at the time constant capacitor 203 is still below the breakdown voltage of the zener diode 204 is the heating time of the fluorescent lamp.

When power is off, the voltage of the time constant capacitor 203 is partially discharged to the discharge resistor 207 and partially discharged to the zener diode 204, and therefore, the voltage at the two opposite ends of the time constant capacitor 203 becomes zero. As the discharging voltage surpasses the breakdown voltage of the zener diode 204, the LED of the photo coupler 206 is actuated to give light, and the ignition circuit 300 starts to ignite. When the LED at the photo coupler 206 is off, the base of the transistor 402 of the darlington circuit of the master switch circuit 400 receives the positive voltage of the resistor 401 causing the darlington circuit to be electrically connected. At the same time the positive voltage is sent from contact A through the collector and emitter of the transistor 403, the diodes 404; 405; 406 and then to contact B, causing the fluorescent lamp 102 heated (see the dotted line in Fig. 3) . The master switch circuit 400 further comprises a fly-wheel diode coupled in parallel to the transistor 403 to protect it. As the LED at the photo coupler 206 is on, its output terminal is electrically connected, the voltage waveform between contacts A and B is as shown in Fig. 4 in case the voltage at contact A is positive, and the value of the voltage is equal to the saturation voltage between the collector and emitter of the transistor 403 plus the saturation voltage of the transistors 404; 405 and the diode 406. The voltage between contacts A and C is equal to the saturation voltage between the collector and emitter of the transistor 403 plus the saturation voltage of the diodes 404; 405. Because the emitter of the transistor 304 and one end of the phase control capacitor 303 are connected to contact C, the voltage of the diode 301 is equal to the voltage between contacts A and C, the voltage between contacts A and C is higher than the saturation voltage of the transistor 301. Therefore, current is sent from the transistor 301 to the output terminal of the photo coupler 206, then sent through the phase control resistor 302 to the phase control capacitor 303 to start the ignition. The ignition waveform is as shown in the real line in Fig. 4. The resistor 302 and the phase control capacitor 303 are to control the phase of the AC voltage, therefore the voltage at the base of the transistor 304 is phase controlled, and the ignition time is controlled at the peak value of the positive half cycle of contact A or any point thereabout, by means of the control of the resistor 302 and the capacitor 303. The maximum current value (di) can thus be obtained at the the peak of the positive half cycle or thereabout. Further, because ignition voltage -e = L di/dt, the ignition time according to the present invention is regarded synchronous to the peak value of the positive half cycle. This ignition and heating produce by cyclic ensures the stability of the intensity of light of the fluorescent lamp. The transistors 404; 405 are to conrrol the maximum voltage value of the ignition impulse, and their number can be changed according to different requirements. As the base of the transistor 304 receives a voltage, the transistor 304 is electrically connected causing a change of the master switch circuit 400 to a closed state instantly. This instant change causes the two opposite ends of the ballast 101 to produce a high voltage to the two opposite ends of the fluorescent lamp 102 so that the fluorescent lamp 102 is actuated to give light.

As indicated, the present invention uses a photo coupler to couple the time control circuit 20O and the ignition circuit 300 without causing any interference therebetween. The ignition time of the ignition circuit 300 is determined according to the peak value of the heating current, and is synchronous to the impulse of the heating current. It is also one of the features of the present invention to use a normal close switch circuit for making the master switch circuit 400.

Referring to Fig. 3, therein illustrated is an alternate form of the time control circuit. In this alternate form, the time control circuit is referenced by 200A. When the voltage at contact A is at the positive voltage stage, AC voltage is sent through the diode 208 to charge the time constant resistor 209 and the time constant capacitor 210. As the voltage at the two opposite ends of the time constant capacitor 210 surpasses the breakdown voltage of the zener diode 211, the transistor 212 is electrically connected and turned to the saturation state. At the same time, the ignition circuit 200 starts to ignite. The time constant capacitor 210 and time constant resistor 209 of the time control circuit 200 are to control the heating time of the fluorescent lamp. The resistor 302 and the phase control capacitor 303 are to control the ignition time. The transistors 404; 405 are to control the ignition impulse, and their number are changeable according to different requir _*ements. Further, a power MOSFET may be used to replace the darlington circuit of the master switch circuit 400.

Referring to Fig. 5, therein illustrated is another alternate form of the time control circuit 200. In this alternate form, the time control circuit is referenced by 200B. When the voltage at contact A is at the positive voltage stage, AC voltage is sent through the diode 301 to charge the time constant resistor 213 and the time constant capacitor 214. As the voltage at the two opposite ends of the time constant capacitor 214 surpasses the breakdown voltage of the zener diode 215, the time control transistor 216 is electrically connected and turned to the saturation state. At the same time, the ignition circuit 300 starts to ignite. After ignition, the fluorescent lamp is turned on. When power is on, the base of the p-n-p transistor 217 has a negative voltage, therefore the discharge transistor 217 is connected, and the voltage of the time constant capacitor 214 is discharged to the collector and emitter of the discharge transistor 217 until zero voltage. This procedure is repeated to turn on the fluorescent lamp when the power switch is switched on again. The resistor 218 at the base of the discharge transistor 217 is to keep the discharge transistor 217 carrying the positive voltage. The base-emitter resistor is to keep the charge transistor 217 carrying a negative voltage. The discharge transistor 217 is off when its collector is carrying the positive voltage, or on when its collector doesn't carry any positive voltage.

Referring to Fig. 5 again, a full-wave rectifier 500 may be connected to the fluorescent starte «r so as to form a full-wave fluorescent starter. The m and n terminals of the full-wave rectifier 500 are connected to the fluorescent lamp. Contact A is connected to the positive terminal of the full-wave rectifier 500. Contact B is connected to the negative terminal of the full-wave rectifier 500. Therefore, the operation cycle of the full-wave fluorescent starter is a full cycle. The operation of each half cycle is similar to the aforesaid half-wave fluorescent starter.

Referring to Fig. 6, therein illustrated is an alternate form of the circuit diagram of the fluorescent starter. In this alternate form, a resistor 408 is used in the master switch circuit 400 to replace the diodes 404; 405; the ignition circuit 300 is simply comprised of a transistor 904; the time control circuit 200C is comprised of a time control resistor 222, a time control capacitor 221, a p-n-p type transistor 223, a zener diode 220, and a shunt circuit. As contact A is at the stage of positive voltage, the master switch circuit 400 is on, and AC voltage is equal to the saturation voltage of the transistor 403 plug the voltage drop at the two opposite ends of the resistor 408. The resistor 408 is to limit the current to the filament circuit of the fluorescent lamp 102, therefore the fluorescent starter fit any of a variety of fluorescent lamps. An additional resistor may be connected in series to the resistor 408 so as to increase AC voltage drop. At the same time, the voltage at contact A of the time control circuit 200C charges the time control resistor 22 and the time control capacitor 221, and the shunt resistor 224 provides a voltage to the base of the p-n-p type transistor 223 in turning it off. As the voltage at the two opposite ends of the time control capacitor 221 surpasses the breakdown voltage of the zener diode 220, the transistor 304 of the ignition circuit 300 becomes on, and the fluorescent lamp 102 finishes the ignition operation. When the voltage at AB is zero, the voltage at the base of the transistor of the time control circuit 200C becomes zero, and at the same time, the voltage at the two opposite ends of the time control capacitor 221 is discharged through the collector and emitter of the transistor, and therefore the fluorescent lamp 102 is turned to the waiting state for next operation. This design prevents the residual charges of the time control capacitor 221 from interfering with the ignition time.

Claims

What is claimed is;

1. A fluorescent starter comprising a time control circuit, a master switch circuit, and an ignition circuit for controlling the ignition and heating of a fluorescent lamp, wherein said time control circuit, said master switch circuit, and said ignition circuit are connected into a parallel circuit directly coupled to the first and second contacts at two opposite ends of said fluorescent lamp; said time control circuit is coupled to said ignition circuit by a photo coupler; said ignition circuit is directly coupled to said master switch circuit for direct On/Off controls, and its ignition time is synchronous to the peak value of the heating current.

2. The fluorescent starter of claim 1 wherein said time control circuit is comprised of a rectifier diode, a time constant resistor, a time constant capacitor, a discharge resistor, a zener diode, a limit current resistor, and a photo coupler, said rectifier diode and said time constant resistor and said time constant capacitor being connected in series to the two opposite contacts of said fluorescent lamp, said time constant capacitor being charged as the first contact of said fluorescent has the positive voltage, said time constant capacitor being to discharge to said discharge resistor and said zener diode, as the second contact of said fluorescent lamp has the positive voltage, causing said photo coupler to actuate said ignition circuit, the breakdown voltage of said zener diode being obtained from the voltage at the two opposite ends of said time constant capacitor, said zener diode and said limit current resistor and said photo coupler being connected in series, said discharge resistor and said constant time capacitor being connected in parallel.

3. The fluorescent starter of claim 1 wherein said master switch circuit is a normal close switch circuit comprised of a darlington circuit having a base directly coupled with a resistor and the collector of a transistor, and a plurality of diodes, the output terminal of said darlington circuit and the connecting end between said master switch circuit and said ignition circuit being respectively and directly coupled to the first and second contacts of said fluorescent lamp, the forward voltage at the first contact of said fluorescent lamp being equal to the saturation voltage of said darlington circuit plus the saturation voltage of the diodes of said master switch circuit, the resistor of said master switch circuit being directly coupled to the first contact of said fluorescent lamp, said darlington circuit being connected in parallel with a diode for protection.

4. The fluorescent starter of claim 3 wherein the diodes of said master switch circuit are to control the ignition impulse voltage, and its number can be changed.

5. The fluorescent starter of claim 1 wherein said ignition circuit is comprised of a diode, a phase control resistor, a phase control capacitor, a transistor, and a photo coupler, the forward voltage among the diode, photo coupler, phase control resistor, and phase control capacitor of said ignition circuit being equal to the voltage between the first contact of said fluorescent lamp and the connecting end between said master switch circuit and said ignition circuit, the base of the transistor of said ignition circuit being directly coupled between said phase control resistor and said phase control capacitor, the collector of the transistor of said ignition circuit being directly coupled to the base of said darlington circuit, the emitter of the transistor of said ignition circuit being directly coupled to the connecting end between said master switch circuit and said ignition circuit.

6. The fluorescent starter of claim 2 or 5 wherein the photo coupler of said ignition circuit and the photo coupler of said time control circuit are the same photo coupler.

7. The fluorescent starter of claim 3 wherein the voltage at the first contact of said fluorescent lamp and the connecting end between said master switch circuit and said ignition circuit should be higher than the total saturation voltage of the diode, transistor and photo coupler of said ignition circuit.

8. The fluorescent starter of claim 1 wherein said time control circuit is comprised of a rectifier diode, a time constant resistor, a time constant capacitor, a zener diode, and a transistor, the rectifier diode, time constant resistor and time constant capacitor of said time control circuit being directly coupled in series, the zener diode of said time control circuit having its n pole directly coupled to the connecting end between said time constant capacitor and said time constant resistor, and its p pole directly coupled to the base of the transistor of said time control circuit, the transistor of said time control circuit haying its collector directly coupled to the n pole of the n pole of the diode of said ignition circuit, and its emitter directly coupled to one end of the phase control resistor of said ignition circuit, the rectifier diode of said time control circuit and the diode of said ignition circuit being respectively connected to the first contact of said fluorescent lamp in the same direction.

9. The fluorescent starter of claim 1 wherein said time control circuit is comprised of a rectifier diode, a time constant resistor, a time constant capacitor, a zener diode, a time control transistor, a discharge transistor, a collector-base resistor, and a base-emitter resistor, the rectifier diode of said time control circuit and the rectifier diode of said ignition circuit being the same rectifier diode, the rectifier diode, time constant resistor and time constant capacitor of said time control circuit being directly coupled in series, the zener diode of said time control circuit having its n pole connected to the connecting end between said time constant capacitor and said time constant resistor, and its p pole directly coupled to the base of said time control transistor, said time control transistor having its collector directly coupled to the connecting end between said phase control capacitor and phase control resistor of said ignition circuit, and its emitter directly coupled to the base of the transistor of said ignition circuit, said discharge transistor having its collector directly coupled to the positive terminal of said time constant capacitor, and its emitter directly coupled to the negative terminal of said time constant capacitor, said discharge transistor having its base directly coupled to the n pole of the rectifier diode of said ignition circuit through a resistor so as to obtain the positive voltage.

10. The fluorescent starter of claim 1 which is a full wave fluorescent starter having two opposite ends respectively connected to the positive and negative terminals of a full wave rectifier, said full wave rectifier having one AC terminal connected to the first contact of said fluorescent lamp and the other AC terminal connected to the second contact of said fluorescent lamp.

11. The fluorescent starter of claim 1 wherein said ignition circuit drives a transistor to finish the ignition operation; said time control circuit is comprised of a time control resistor, a time control capacitor, a transistor, a zener diode, and a shunt circuit; the zener diode has its p terminal connected to the base of the transistor of said ignition circuit, its n terminal connected to the connecting point between said time control resistor through direct coupling and said time control capacitor and also connected to the collector of the transistor through direct coupling, the other terminal of said time control resistor and said time control capacitor being respectively connected to AC contact through direct coupling, the AC voltage being equal to the saturation voltage of the transistor of said master switch circuit plus the voltage at the two opposite ends of the resistor, the base of the transistor of said time control circuit being directly coupled to the center point of said shunt circuit, said shunt circuit having one end directly coupled to contact A, another end directly coupled to contact C, the collector connected to n terminal of the zener diode, the emitter directly coupled to contact C; said master switch circuit is comprised of a transistor darlington circuit, a resistor, and a diode, the transistor darlington circuit having its collector directly coupled to contact A, its emitter directly coupled to the resistor, the resistor having an opposite end directly coupled to the diode, the diode having the opposite end directly coupled to contact B, the transistor darlington circuit, the resistor, and the diode being connected in series, AC voltage being obtained from the saturation voltage of the transistor darlington circuit and the voltage drop at the two opposite ends of the resistor, the base of the transistor darlington circuit of said master switch circuit being directly coupled to the collector of the transistor of said ignition circuit and then connected to contact A through a resistor, the emitter of the transistor of said ignition circuit being directly coupled to one end of the resistor of said master switch circuit.