Abstract:
A four-electrode fluorescent, lamp having four filaments in a fluorescent lamp; each of the filament having two leads for being connected to a positive and a negative electrodes of a power source. A resistor is serially connected between a lead of one selective filament and a lead of another selective filaments. Each of the filaments is controlled by a transistor. A pair of capacitors are used to adjust the switching current of a pair of two transistors. The base of the transistor is connected to a respective diode set through a current limiting resistor. Each of the transistor is connected to a diode set. The four diodes are serially connected as a loop with two ends of the loop being connected to two ends of an AC power source. Thereby, a circuit for an alternative lighting four-electrode fluorescent lamp is formed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a four-electrode fluorescent lamp, and particularly to a circuit for an alternative lighting four-electrode fluorescent lamp. 
     BACKGROUND OF THE INVENTION 
     In the prior art designs, fluorescent lamps have two Electrodes with each end of the lamp tube having one electrode and a simple circuit design. In actuation, the current consumed is large and vibration of illumination is great so that surge waves and noises generate to make uneasy feeling to uses. Moreover, in prior art design, an igniter is necessary. In starting process, flashing light generates go as to harm eyes of users. 
     Moreover, the cores of the lamps made of silicon steel or carbon iron powders as a hysteresis transformer which is heavy and generates magnetic fields and noises. Further, high frequency ignition is harmful to human, and particularly to hearing comprehension and brains. The medical instruments and aerospace surveillance systems will be interfered. 
     SUMMARY OF THE INVENTION 
     Accordingly, the primary object of the present invention is to provide a four-electrode fluorescent lamp having four filaments in a fluorescent lamp wherein each of the filament has two leads for being connected to a positive and a negative electrodes of a power source. A resistor is serially connected between a lead of one selective filament and a lead of another selective filament. Each of the filament is controlled by a transistor. A pair of capacitors are used to adjust the switching current of a pair of two transistors. The base of the transistor is connected to a respective diode set through a current limiting resistor. Each of the transistor is connected to a diode set. The four diodes are serially connected as a loop with two ends of the loop being connected to two ends of an AC power source. Thereby, a circuit for an alternative lighting four-electrode fluorescent lamp is formed. 
     The various objects and advantages of the present invention will is be more readily understood from the following detailed description when read in conjunction with the appended drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of the four-electrode fluorescent lamp of the present invention. 
     FIG. 2 shows the circuit arrangement of the four-electrode fluorescent lamp of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a first embodiment of the present invention is illustrated. A four-electrode fluorescent lamp FL is illustrated. There are four filaments A, B, C, and D in the four-electrode fluorescent lamp FL, each of the filament A, B, C, D is used as an electrode. The La 1  and La 2  are leads of the filament A. The La 3  and La 4  are leads of the filament B. The Lb 1  and Lb 2  are leads of the filament C. The Lb 3  and Lb 4  are leads of the filament D. A resistor Rs is serially connected between the leads Lb 2  and Lb 3 . 
     Referring to FIG. 2, another embodiment of the present invention is illustrated. The same elements of the four-electrode fluorescent lamp FL both in FIGS. 1 and 2 are numerated with the same numbers and thus the details wilt not be described herein. It is illustrated that the four electrode fluorescent lamp FL of the present invention is arranged in the electronic circuit. One lead of each of the two electrodes A, and D is connected to a collector of a respective PNP transistor TR- 1  and TR- 4  and one lead of each of the two electrodes B, and C is connected to a collector of a respective NPN transistor TR- 2  and TR- 3 . The transistors TR- 1 , TR- 2 , TR- 3  and TR- 4  are used as switches for turning on or off the respective leads. 
     The capacitors C 1 , C 2 , C 3  and C 4  serve to store charges and charge the respective transistors so as to actuate the respective transistors. The capacitor C 1  is connected between the emitters of the transistors TR- 1  and TR- 2 , and the capacitor C 2  is connected between the collectors of the transistors TR- 1  and TR- 2 . The capacitor C 4  is connected between the emitters of the transistors TR- 3  and TR- 4 , and the capacitor C 3  is connected between the collectors of the transistors TR- 3  and TR- 4 . The base of transistor TR- 1  is connected to the emitter of the transistor TR- 2 . Thee base of transistor TR- 2  is connected to the emitter of the transistor TR- 1 . The base of transistor TR- 3  is connected to the emitter of the transistor TR- 4 . The base of transistor TR- 4  is connected to the emitter of the transistor TR- 3 . 
     All the diode sets are serially connected as a diode loop, And one end of the loop is connected to an C′ end of the power source and another end of the loop is connected to an A′ end of the power source. 
     Each of the transistors TR- 1 , TR- 2 , TR- 3  and TR- 4  is connected to a diode set through current limiting resistors; for example, the transistor TR- 1  is connected to diodes D 1  and D 2  through the resistor R 1 -R 3 . The transistor TR- 2  is connected to diodes D 3  and D 4  through the resistor R 4 -R 6 . The transistor TR- 3  is connected So diodes D 5  and D 6  through the resistor R 7 -R 9 . The transistor TR- 4  is connected to diodes D 7  and D 8  through the resistor R 10 -R 12 . 
     The fuse FUSE serves to as a safety protection of the circuit. 
     The operation of FIG. 2 will be described here. When the power switch S- 1  is in the off point, the power turns off and the four-electrode fluorescent lamp FL turns off. 
     When the switch S- 1  is at H point, the four-electrode fluorescent lamp FL is at high illumination. When the switch S- 1  is at MR point, the four-electrode fluorescent lamp FL is at middle illumination. When the switch S- 1  is at LR point, the four-electrode fluorescent lamp FL is at low illumination. 
     For the PNP transistor TR- 1 , the positive half cycle of the A′ end of the AC voltage will conduct the diodes D 1  and D 2 . Since the resistor R 1  is smaller than resistor R 2 , the transistor TR- 1  cuts off and thus the electrode A will not conduct. The diodes D 1  and D 2  cause that the capacitor C- 1  is charged. When the voltage of C′ end of the AC power source enters into the negative half cycle, the diodes D 1  and D 2  cut off and the charges in the negative side of the capacitor C 1  causes that the transistor TR- 1  conducts so that the charges at the positive side of the capacitor C 1  flows through transistor TR- 1  to charge the capacitor C 2  and the lead La 1 . 
     For the NPN transistor TR- 2 , the negative half cycle of the C′ end of the AC voltage will conduct the diodes D 4  and D 3 . Since the resistor R 6  is smaller than resistor R 5 , the transistor TR- 2  cuts off and thus the electrode C will pot conduct. The diodes D 4  and D 3  cause that the capacitor C 1  is charged. When the voltage of the C′ end in the AC power supply end enters into the positive half cycle, the, diodes D 4  and D 3  cut off and the charges in the positive side of the capacitor C 1  causes that the transistor TR- 2  conducts so that the charges at the positive side of the capacitor C 1  flows through transistor TR- 1  to charge the capacitor C 2  and the lead Lb 1 . 
     For the NPN transistor TR- 3 , the negative half cycle of the A′ end of the AC voltage will conduct the diodes D 5  and D 6 . Since the resistor R 7  is Smaller than resistor R 8 , the transistor TR- 3  cuts off and the electrode B will not conduct. The diodes D 5  and D 6 , cause that the capacitor C 4  is charged. When the voltage of the C′ end in the AC power supply end enters into the positive half cycle, the diodes D 5  and D 6  cut off and the charges in the negative side of the capacitor C 4  causes that the transistor TR- 3  conducts so that the charges at the positive side of the capacitor C 3  flows through transistor TR- 3  to charge the capacitor C 3  and the lead La 4 . 
     For the NPN transistor TR- 4 , the positive half cycle of the C′ end of the AC voltage will conduct the diodes D 8  and D 7 . Since the resistor R 12  is smaller than resistor R 11 , the transistor TR- 4  cuts off and thus the electrode D will not, conduct, The diodes D 8  and D 7  cause that the capacitor C 4  is charged; When the voltage of the C′ end in the AC power supply end enters into the positive half cycle, the diodes D 8  and D 7  cut off and the charges in the positive side of the capacitor C 4  causes that the transistor TR- 4  conducts so that the charges at the positive side of the capacitor C 4  flows through transistor TR- 4  to charge the capacitor C 3  and the lead Lb 4 . When capacitor C 1  is charged, the transistors TR- 1  and TR- 2  cut off. When the capacitor C 4  is charged, transistors TR- 3  and TR- 4  cut off. When transistors TR- 1  and TR- 2  conducts, the capacitor C 2  is charged. When transistors TR- 3  and TR- 4 , the capacitor C 3  is charged. When the capacitors C 2  and C 3  are charged, the positive charges of capacitor C 2  is guided to the lead La 1  and negative charges of the capacitor C 2  is guided to the lead Lb 1 . The negative charges of the capacitor C 3  is guided to the lead La 4  and positive charges thereof is guided to the Lb 4 . Current froth lead Lb 4  flows to the lead Lb 3  through the filament D. Then the current flows through the resistor Rs, then flow through the filament C to lead Lb 1  to the negative polarity of capacitor C 2 . Thereby, a serial loop is formed. Thereby, the voltage difference between the filament, A and filament B is 2V 0 C. Then electrodes A and B are discharged so as to generate heat (so called cool cathode method) so that the mercury in the lamp will flow greatly. Since the circuit is a serial connected circuit, the temperature of electrodes C and D will increase (so call hot cathode method) so that a great amount of electrons generate. Thereby, the illumination of the lamp is increased and the impedance in the tube is decreased so that the current is increased. Moreover, since the AC power supplies to the circuit by a sequence of C 1 , C 2 , C 4  and C 3 . Thereby, the voltages of La 1  and Lb 1  and voltages of La 4  and Lb 4  are alternatively changed so that the lamp tube lights up. 
     Advantages of the present invention will be described hereinafter. 
     The power of the four-electrode fluorescent lamp is determined by the capacitances of the capacitors. 
     The Q value is equal to C (capacitance) * V (voltage) which is equal to I (current) * T (time). No igniter, steady hysteresis transformer, and high frequency is required. 
     The hot and cold cathodes are used to control the time sequence of the power source. 
     The resistor Rs has a function of adjusting the igniting actuating current so as to protect the electrodes. 
     The currents are alternatively changed so that the emitting light is softly and warmly. 
     The capacitance of the capacitor C 2  has a value of 0.003 μF and capacitance of the capacitor C 3  has a value of 0.003 μF which serves as a surge and noise absorber. 
     The present invention will not be interfered by EM waves or fields. 
     The material used is simple. Power can be saved. 
     The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.