Abstract:
A lighting and starting device for two-electrode lamp includes a plurality of voltage-multiplier rectifying circuits parallelly connected to two electrodes of the lamp with stepping voltages, for instance, high, medium and low voltage levels, whereby upon selection of the desired voltage level, the light of the lamp can be adjusted optimumly.

Description:
BACKGROUND OF THE INVENTION 
     A conventional fluorescent lamp has the following disadvantages: 
     1. When starting the conventional fluorescent lamp, a high current must be applied to heat the lamp filaments to easily blacken the tube to ultimately fail. 
     2. The electromagnetic waves caused from the high frequency induction coil for starting the fluorescent lamp is hazardous to human health. 
     3. The lamp is not adjustable for varying the illumination or light intensity, being unsatisfactory for the lamp user. 
     The present inventor has found the drawbacks of conventional fluorescent lamp and invented the present device for obtaining a two-electrode lamp having high efficiency and being adjustable for lamp. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a lighting device for two-electrode lamp including a plurality of voltage-multiplier rectifying circuits parallelly connected to two electrodes of the fluorescent lamp with stepping voltages, for instance, high, medium and low voltage levels, whereby upon selection of the desired voltage level, the light of the fluorescent lamp can be adjusted optimumly. 
     Another object of the present invention is to provide a protective device to limit current or to prevent from over current as fed back by the reverse voltage from the lamp and led to the lighting circuit of the two-electrode lamp. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a circuit diagram of the present invention. 
     FIG. 2 shows a double-voltage rectifying circuit as included in the present invention. 
     FIG. 3 shows a quadruple-voltage rectifying circuit existing in the present invention. 
     FIG. 4 shows an octa-voltage rectifying circuit in the present invention. 
     FIG. 5 is an illustration when added with a further light-adjusting device of the present invention. 
     FIG. 6 shows a fluorescent lamp as protected in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     As shown in the drawing figures, a preferred embodiment of the present invention comprises a plurality of (or three) voltage-multiplier rectifying circuits Ckt 1 , Ckt 2  and Ckt 3  parallelly connected across two electrodes of a fluorescent lamp FL. 
     As shown in FIG.  2 . The first voltage-multiplier rectifying circuit Ckt 1  of full-wave bridge type rectifier is described hereinafter. 
     An alternative current (AC) power source supply having voltage V 0  is applied to the circuit Ckt 1  through points A and C. The operation principles are shown as follows: 
     First Cycle 
     When point A meets a positive half cycle of voltage V 0  and point C meets a negative half cycle, the diode D 3  is conducted (D 5  is interrupted) and the capacitor C 1  is charged up to the voltage V 0 . Meanwhile, when point A meets the positive half cycle of voltage V 0  and point C meets negative half cycle of voltage V 0 , the diode D 6  is conducted (D 4  is interrupted) and the capacitor C 4  is charged up to voltage V 0 . 
     During the positive and negative alternation, the positive electricity as charged to the capacitor C 1  will be discharged through diode D 1  and resistor R 1  and output through a first contactor a 1  of a first electrode (or positive electrode) of the fluorescent lamp FL (FIG.  1 ), and the negative electricity will be output through diode D 6 , diode D 8 , resistor R 4  and a second contactor b 2  of a second electrode (or negative electrode) of the fluorescent lamp FL. Meanwhile, the positive electricity charged to the capacitor C 4  will be discharged through diode D 3 , diode D 1  and resistor R 1  and output through the first contactor a 1  of the first electrode of the lamp FL; and the negative electricity thereof is output through diode D 8 , resistor R 4  and the second contactor b 2  of the second electrode of the lamp FL. 
     Second Cycle 
     When point A meets a negative half cycle of the voltage V 0 , and point C meets a positive half cycle of voltage V 0 , the diode D 4  is conducted (D 6  is interrupted) and the capacitor C 2  is charged up to the voltage V 0 . Meanwhile, when point A meets the negative half cycle and point C meets positive half cycle, the diode D 5  is conducted (D 3  interrupted) and the capacitor C 3  is charged up to the voltage V 0 . 
     During the alternation, the positive electricity as charged to the capacitor C 2  will be discharged through diode D 2  and resistor R 2  and output through the second contactor a 2  of the first electrode of the lamp FL, and the negative electricity is output through diode D 5 , diode D 7  and resistor R 3  and output through the first contactor b 1  of the second electrode (or negative electrode) of the lamp FL. Meanwhile, the positive electricity charged to the capacitor C 3  will be discharged through diode D 4 , diode D 2  and resistor R 2  and output through the second contactor a 2  of the first electrode of the lamp FL, and the negative electricity will be output through the diode D 7  and resistor R 3  and output through the first contactor b 1  of the second electrode of the lamp FL. 
     Accordingly, the contactors a 1 , a 2  of the first electrode of the lamp FL are connected in parallel and the contactors b 1 , b 2  of the second electrode are also connected in parallel to output a voltage of 2V 0  since capacitors C 1 , C 3  are connected in series, and capacitors C 2 , C 4  are also connected in series. 
     For calculating a total impedance value R x  of a “loop” of the lighting means as connected with the lamp (having a half-wave internal resistance of R x1 , R x2 ), the following formula may, for instance, be used: 
     
       
           {overscore (R)}   1   =R   1   +R   3 +{1÷[2 πf ( C   1   +C   3 )]}= R   x1   
       
     
     
       
           {overscore (R)}   2   =R   2   +R   4 +{1÷[2 πf ( C   2   +C   4 )]}= R   x2   
       
     
     
       
           R   x =1÷[(1 ÷R   x1 )+(1 ÷R   x2 )] 
       
     
     The alternation of the positive or negative pulses of an alternative current (AC) power source supply to forwardly conduct diodes and reversely interrupt the diodes and to discharge the capacitors as already being charged to thereby multiply the voltage. For instance, the voltage V 0  of power source will be multiplied to be 2V 0  to eliminate the high frequency induction coil or transformer of a starter as required by a conventional fluorescent lamp. The electromagnetic waves as caused by the high frequency induction coil or transformer of conventional fluorescent lamp will then be prevented in accordance with the present invention, thereby being helpful for human health. 
     The first rectifying circuit Ckt 1  can produce double voltage, i.e., 2V 0 ; and the second rectifying circuit Ckt 2  (FIG. 3) can produce quadruple voltage, 4V 0 ; and the octa-voltage, 8V 0  will be obtained by the third rectifying circuit Ckt 3  (FIG. 4) as hereinafter described. 
     By selectively connecting either of the rectifying circuits Ckt 1  or Ckt 2  or Ckt 3 , three (or plural) multiplied voltage levels can be chosen and applied to the first and second electrodes of the fluorescent lamp FL for adjusting the light intensity of the fluorescent lamp. Namely, Ckt 1  (2V) may obtain a high light illumination, Ckt 2  (4V) obtaining a medium light, and Ckt 3  (8V) obtaining a low light illumination. 
     As shown in FIG. 3, a second voltage-multiplier rectifying circuit (full-wave bridge type) Ckt 2 , as parallelly connected to the lamp FL as shown in FIG. 1, is described as hereinafter. V 0  is the alternative-current (AC) power source supply, alternatively delivering a positive half cycle and a negative half cycle to the circuit Ckt 2  through the point A and point C continuously. The operation principles are described as follows: 
     First Cycle 
     When point A is positive and point C is negative, the diode D 17  is conducted and the capacitor C 17  is charged to the voltage V 0 . When point A is negative and point C is positive, the diode D 17  is interrupted and the diode D 19  is conducted to charge the capacitor C 17  to the voltage V 0  which is added on the voltage V 0  of power source supply to further charge the C 13  to be 2V 0  (V 0 +V 0 =2V 0 ). 
     During the alternation of positive and negative electricity, the positive electricity of C 13  is discharged through the first contactor a 1  of the first electrode of the lamp FL through D 15 , D 13 , D 11  and R 11  and the negative electricity of C 13  is discharged through the second contactor b 1  of the second electrode of the lamp FL through D 21 , R 13 . 
     Meanwhile, when point A is positive and point C is negative, D 16  is conducted and C 16  is charged to the voltage V 0 . When point A is negative and point C is positive, D 16  is interrupted and D 14  is conducted to charge C 16  to the voltage V 0  which is added on with the voltage V 0  of power source supply to further charge C 12  to be 2V 0 . During the alternation of positive and negative electricity, the positive electricity of C 12  is discharged through a 2  of the lamp FL through D 12 , R 12  and the negative electricity is discharged through b 2  of lamp FL through D 18 , D 20 , D 22  and R 14 . 
     Second Cycle 
     When point A is negative and point C is positive, D 15  is conducted and C 15  is charged to V 0 . When point A is positive and point C is negative, D 15  is interrupted and D 13  is conducted to charge C 11  to be 2V which is obtained by the voltage V 0  of C 15  plus the voltage V 0  of power source. During the alternation of the positive and negative electricity, the positive electricity of C 11  is discharged through a 1  of lamp FL through D 11 , R 11 , and the negative electricity discharged through b 1  of lamp FL through D 17 , D 19 , D 21  and R 13 . 
     Meanwhile, when point A is negative and point C is positive, D 18  is conducted and C 18  is charged to voltage V 0 . When point A is positive and point C is negative, D 18  is interrupted and D 20  is conducted to charge C 18  to V 0  which is added with V 0  of power source to further charge C 14  to be 2V 0 . During the alternation of positive and negative electricity, the positive electricity of C 14  is discharged through a 2  of lamp FL through D 16 , D 14 , D 12  and R 12 , and the negative electricity discharged through b 2  of FL through D 12 , R 14 . 
     By the way, C 11  is connected in series with C 13  to obtain 4V 0  (2V 0 +2V 0 =4V 0 ); while C 12  is connected with C 14  in series to obtain 4V 0  to obtain a quadruple voltage (4V 0 ) of the power source when the a 1 , a 2  are parallelly connected and the b 1 , b 2  are also parallelly connected to the lamp FL. 
     As shown in FIG. 4 of octa-voltage multiplier of full-wave bridge type rectifier connected to points A and C of the AC power source, the first contactor a 1  of the first electrode of the lamp FL is connected with the elements including D 29 , D 27 , D 25 , D 23 , D 21 , R 21 , C 31 , C 29 , C 23  and C 21 ; the second contactor a 2  connected with D 30 , D 28 , D 26 , D 24 , D 22 , R 22 , C 32 , C 30 , C 24  and C 22 ; the b 1  of the second electrode connected with D 31 , D 33 , D 35 , D 37 , D 39 , R 23 , C 25 , C 27 , C 33  and C 35 ; and the b 2  connected with D 32 , D 34 , D 36 , D 38 , D 40 , R 24 , C 26 , C 28 , C 34  and C 36 . When C 21 , C 23 , C 25 , C 27  are connected in series, 8V 0  is obtained at a 1 , b 1 ; and C 22 , C 24 , C 26 , C 28  connected in series, 8V 0  is obtained at a 2 , b 2 . Therefore an octa-voltage (8V 0 ) can be obtained. 
     So, multiplier voltage of 2V 0 , 4V 0  and 8V 0  can be selected from FIGS. 2,  3 ,  4  in accordance with the present invention to respectively obtain illumination light intensity of the florescent lamp FL explained as follows: 
     First Step for Starting or Lighting Lamp 
     By using the third full-wave voltage-multiplier bridge rectifying circuit Ckt 3  of FIG. 4 to parallelly connect a 1 , a 2  to the first electrode of fluorescent lamp FL to supply positive charge to the first electrode of 8V 0  high voltage and also to parallelly connect b 1 , b 2  to the second electrode of FL to supply negative charge to the second electrode of 8V 0  voltage, the lamp FL is lighted by reducing the resistance in the lamp tube by the high voltage. However, the current is low so that the first step for lighting the lamp is a low light intensity (or low brightness) illumination. 
     Second Step for Lighting Lamp 
     By using the second rectifying circuit Ckt 2  as shown in FIG. 3 to connect a 1 , a 2 , b 1  and b 2  respectively to the two electrodes of the lamp FL to apply the medium voltage (4V 0 ) to the lamp, a second step for lighting the lamp at a medium light intensity illumination with medium current which is still higher than the current of first step (by Ckt 3 ) to further reduce the internal resistance in the lamp and thus brighter than that of Ckt 3 . 
     Third Step 
     By using the first rectifying circuit Ckt 1  as shown in FIG. 2 to apply the low voltage (2V 0 ) to the lamp FL, a third step for lighting the lamp FL at the brightest level than the second step since maximum current and lowest voltage is applied to the lamp to minimize the internal resistance in the lamp tube. 
     Therefore the light intensity of the lamp can be adjusted stepwise by selecting the desired rectifying circuit. Naturally, the circuits are not limited to Ckt 1 , Ckt 2  and Ckt 3  as aforementioned in accordance with the present invention. 
     The lower the internal resistance in the lamp tube is, the higher the current in the tube will be, thereby emitting more electrons for strongly ionizing vapor in the tube for glowing the lamp brighter. 
     As shown in FIG. 1 for showing a starter device, since the first or positive electrode (filament) Fa is far apart from the second or negative electrode (filament) Fb of the lamp FL, an outer negative electrode S b  (which may be an electrically conductive ring or metal ring) is closely disposed about the positive electrode Fa as partitioned by an electrically insulative tube wall of the lamp FL and is connected to the negative electrode Fb by a limiting-current resistor Rb; and an outer positive electrode Sa (which may be an electrically conductive ring or metal ring) is closely disposed about the negative electrode Fb as partitioned by the electrically insulative tube wall of the lamp and is connected to the positive electrode Fa by another limiting-current resistor Ra. 
     Since each outer electrode Sb or Sa is quite close to the electrode Fa or Fb in the lamp tube by the insulative tube wall to play as a capacitor, the voltage between the outer electrode with the electrode (filament) in the lamp tube will be discharged to have the function of a starter for starting the fluorescent lamp FL. 
     Accordingly, a conventional starter for boosting the voltage in order to start the fluorescent lamp will be eliminated in accordance with this starter device of the lamp FL as above-mentioned. 
     As shown in FIG. 6, each contactor a 1 , a 2 , b 1 , b 2  is connected to each electrode Fa or F b  by a limiting-current resistor R to limit the current under a safety value in consideration of a “critical impact effect” for protecting the filaments Fa, Fb and the lamp FL, for instance, for preventing from damage and blackening of the tube. 
     The present invention provides a fluorescent lamp which is light adjustable, safely protected and not hazardous as caused by the electromagnetic wave, thereby serving for convenient, safe and energy-saving use. 
     As shown in FIG. 5, each terminal such as point C (or point A) is selectively connected with a plurality of selecting switches S, for instance, Nc for power off; a first switch (numeral “1”) for a first current supply and first light intensity; a second switch (numeral “2”) connected with a resistor R s  to the circuit for a second (lower) current supply and second (weak) light intensity. A third switch (“3”) may also be added. However, such a switch device is so conventional and can be modified by those of skill in the art. 
     The present invention may be modified without departing from the spirit and scope of this invention. The voltage multipliers are also not limited to voltage doublers. 
     The two-electrode lamp of the present invention may refer to a fluorescent lamp, and other two-electrode illuminators.