Patent Publication Number: US-2012038278-A1

Title: Electronic inverter with protection for discharges produced by malfunctioning in gas discharge or fluorescent lamps at the end of the service life thereof

Description:
OBJECT OF THE INVENTION 
     The object of this invention to provide a full-wave inverter, characterized by being protected against the phenomena generated through the life of the lamp and to remain useful, when the lamp connected to the circuit reaches the end of his life and can be replaced in the same investor for a new lamp, the inverter stops operating at the time of failure of the lamp. To achieve this goal, consider all the performance characteristics of the lamps over their lives, thereby protecting its two transistors to be the exposed part, because these transistors for placement in any anomaly in the circuit overlapping signal driving cycle being short-circuited these. 
     Another advantage of this invention is that its signal circuits for alternately switching two transistors, be carried out using diodes instead of capacitors which removes all internal shocks as this mode signal currents not interrupted only change in a harmonious way, so efficiency is achieved by a range greater than three percent, compared to existing investors. 
     Despite the high efficiency, as is known has the gas discharge tube or fluorescent low pressure, as well as longer duration than is the order of ten times the life of the incandescent bulb. Having to replace the entire set when the lamp reaches the end of his life, this hurts his qualities as compared to the cost of incandescent bulb, which is about ten times smaller than the rectifier-inverter set over the lamp. 
     In order to more fairly compare the fluorescent lamp with incandescent bulb, taking into account their luminous efficiency, the fluorescent lamp is 68 lumens/Watt incandescent bulb and has only 10 to 15 lumens/Watt. (IES Lighting Handbook 8-9, 8-11, 8-26). The time-cost relationship of common incandescent light bulb, it is perfectly determined to penetrate every major economy in the lowest. Through this invention, the fluorescent lamp life can be calculated similar to the common incandescent light bulb and this will save energy with less initial cost. 
     When it first acquires the whole lamp investor attaches the rope turning the plug (socket) as is conventional today, and through this invention, the new lamp is easy to connect since the investor even if there is connected to the supply circuit, the lamp remains molten rock it and therefore without consuming energy, until you press the reset button normally open position, placed in the body of the investor, after installing the new lamp, which may have two terminals or contacts at each end, similar to those of the current Rapid start lamps. As the cost of the inverter of this invention is competitive with existing investors, can take advantage of lamp replacements and cost apportioning the cost of new lamps. 
     BACKGROUND 
     The inverter circuit full wave considered here are designed to convert an input voltage direct current output voltage to a high frequency of about 20 kHz. to 100 kHz, used as ballast in gas discharge lamps or fluorescent low pressure, more particularly mentioned here only as a lamp. These lamps can be of various types, most suitable for this type of investor is classified as a quick start by being more efficient than cold-cathode. The power of these investors may be obtained from the mains AC through rectifier circuits based on diodes and capacitors used as filters or as a voltage doubler or pulse modulator circuits and other arrangements, this in order to prevent harmonics generated by the power supply capacitors, which are used as needed according to required standards. 
     These inverter circuits consisting of two transistors have the same characteristics, which are connected in series between the positive terminal (±) and negative (−) power inverter, which lead alternative is in series with the lamp at the time driving and this is achieved by means of a small toroidal core transformer, the signal induced in its windings conduct alternately driving the transistors. The lamp is in turn connected in series with an inductor and a capacitor, which is achieved current response to a sinusoidal voltage and resonant frequency of the predetermined system. 
     These lamps have tungsten filaments mixed with alkaline oxides are placed at each end, and to emit electrons produced through the gas discharge containing the lamp. The temperature of these filaments in normal operation is 1100 degrees Celsius (Page R IES  Lighting Handbook  8-19.), And are heated by the investor permanently ending the life of the lamp when the filaments cease to issue or are interrupted. The electric arc inside is made by the gases that mainly contains argon gas and the electric current increases the arc instantly gasified mercury, which also contains in its interior. 
     These investors have the advantage of not using output transformer for the lamp, because they exploit the advantages of today&#39;s transistors, which can be switched at high voltages (several hundred volts). 
     At present, these investors for their high efficiency and good response to the lamp, they tend to supply the incandescent bulb. It is easy to see that she is about to end the life of a lamp, one ends emits more red light flashes on the other, as the tungsten filament does not sublimate her in the same way, leading one over the other and so your downloads are not symmetrical, as well as the gas becomes more conductive by the sublimation of tungsten, reducing the voltage across the lamp, asymmetrical and discharging more often than those of normal operation. 
     This phenomenon may last several hours, whereas conventional electromagnetic ballast for this phenomenon is not important, especially for this type of investor is highly detrimental for the asymmetry and duration of discharge and which directly affect the operating cycle of its transistors. These discharges pass through the primary winding of the transformer reflected in alternating cycles of the driving transistors having asymmetry in the waveform, this overlap is reflected in the driving cycle of the transistors putting short circuit, be those directly connected between the positive and negative terminals of the inverter power and operate alternately. So, when the lamp is also merges merges the investor. In the U.S. Pat. Indicates that there are U.S. Pat. No. 4,782,268 to replace the electronic circuit with the lamp when it fails. In the invention: MX Pat. Pat. 1111901 CA 143143, U.S. Pat. No. 4,276,496, is an early investor only half-wave, where the consequences of this phenomenon of a malfunction of the lamp, are damped in this case based on negative feedback and a non-saturable core transformer however, the investor continues to oscillate with the lamp melted and reaches its output transistor to fail by heating. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The diagrams shown here help to understand as illustrative features of the invention: 
         FIG. 1  is a complete diagram of the inverter voltage doubler rectifier and lamp in the circuit. 
         FIG. 2  is a diagram illustrating the course of currents in the energized phase inverter element. 
         FIG. 3  is a diagram illustrating the course of currents at the stage of de-energized elements of the inverter. 
         FIG. 4  is a diagram illustrating an electric arc lamp in the stage of a malfunction at the end of its useful life. 
         FIG. 5  shows the tubular core transformer in detail. 
         FIG. 6  shows an image of an electrical discharge in the lamp at the end of his life, obtained through digitizing oscilloscope and camera  2255  model tester AM503B DCS01 and current amplifier. 
         FIG. 7  shows the current in the lamp in normal operation, during its lifetime obtained with the same team. 
         FIG. 8  shows how you can connect more than one lamp to the circuit in  FIG. 1  by adding the capacitor  44  in series with the lamp  49  and the positive side (+)  34 , the capacitor  46  in series with the filament  45  and filament  47  and the inductor  48 , in parallel with the inductance  7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , diodes,  8  and  22 , commonly called free-bearing, which are usually built by the manufacturer in the body of the transistor used to protect the peak-inverse voltage. In order to have greater response in these diodes in the invention connects the diode  8 , the positive (+)  34 , point  43 , excluding the resistor  12  and diode  22 , negative (−)  35 , to the point  43 , excluding the resistance  11 . 
     The operation of the starting circuit of the inverter is as follows: Once the circuit connected at the source of AC power at points  40  and  41 , capacitors  38  and  39 , due to the rectifier diodes  36  and  37  as known, between the point negative (−)  35  and, the positive (+)  34 , there is a full-wave rectified voltage twice the voltage of AC power. 
     Based on the positive side (+)  34 , the condenser  2 , the filament  3 , the condenser  4 , and  6  both filament lamp  5 , the inductance  7 , the primary winding  19 , the resistance  31  and the capacitor  30  closes the circuit at the negative (−)  35 , and when the capacitor  30 , is energized, the diac  32  is placed on letting conducting state current at the point  25  which is the base of the transistor  9 , the issuer that is the point  10 , and through the resistance  11 , negative (−)  35 . As the transistor  9 , begins to conduct. 
     In order to give greater clarity to the investor behavior of this particular operation is considered in two stages: energizing stage and the stage of de-energization. 
     Once the driver to start driving transistor  9 , In  FIG. 2  one can observe in detail the energization of the inverter stage, which begins at the point positive (+)  34 , where the current passes through the condenser  2  and through strand  3 , the condenser  4 , and the filament  6 , both of the lamp  5 , while between these filaments of the lamp  5 , making the electric arc passes through the inductor  7 , the primary winding  19  by the collector the transistor  9 , and its emitter  10 ,  11  resistance, and negative (−)  35 . Simultaneously, the primary winding  19  magnetically coupled to the tubular core transformer for simplicity not drawn into the channels and clearly shown in  FIG. 5 , which induces a voltage in the secondary winding  18 ,  FIG. 2 , which generates the current flowing through the resistor  26 , and the point  25 , which is the base of the transistor  9 , paragraph  10 , which is the issuer and the resistance  11 , closing the circuit at the secondary winding  18 , bringing the transistor  9 , at maximum driving and therefore the maximum discharge lamp  5 . The current generated in the secondary winding  18 , circulates in positive direction, ie in the same direction as clockwise as illustrated in  FIG. 2 . Simultaneously by opposing secondary winding  17 , generating a current through the resistor  12 , for item  13 , the diode  21  and the diode  20 , closing the circuit at the secondary winding  17  antagonist. As you can see, the point  13 , which is the emitter of the transistor  1  has greater potential than the point  24 , which is the base of transistor  1 , so that the transistor does not conduct, being energized, the capacitor  2  and the condenser  4 . This stage concludes energizing the inverter when the tubular core of the transformer  FIG. 5 , is saturated. 
     In that instant you start the cycle of de-energizing reversing a principle known in the inverter currents  FIG. 3 , antagonist in the secondary winding  17 , generating a current flowing in the positive direction, which passes through the resistor  23 , for Item  24  is the base of transistor  1 , point  13  which is the emitter of the transistor  1 , and the resistor  12 , closing the circuit at the secondary winding  17  antagonist, this current acts on the transistor  1 , putting it in your state of maximum driving. Simultaneously in the secondary winding  18 , generates a current that flows from the negative through the resistor  11 , at point  10 , the diode  28 , through diode  29 , closing the circuit at the secondary winding  18 . As you can see the point  10  is more positive than about 25, so that the transistor  9  can not drive and the stage of de-energization of the investor ends when the capacitor  2  and the capacitor  4  is discharged completely. 
     The stages of energizing and de-energization in the discharge of the lamp currents and voltages are sinusoidal, corresponding energizing phase inverter to the positive side of the sinusoid, and the stage of de-energizing the negative side. The system operating frequency is determined by the total value of capacitance and inductance that contain inverter circuits, and can be calculated using the formula known for resonant circuits. 
     As shown in  FIG. 2 , and  FIG. 3 , in the circuits for driving and driving in non-Transistor  1  and  9 , the currents induced change their meaning in harmony but not interrupted for the purpose of no discharges and transients generated within the circuit itself can affect the proper operation of the inverter, improving its operation up to three percent compared to current investors.  FIG. 4  is a diagram illustrating the behavior of the currents generated by malfunction of the lamp  5 , the end of life, non-symmetrical shock and at a frequency higher than normal operation. As you can see the current point of the positive (+)  34 , passing through the condenser  2 , the filament  3 , the condenser  4 , the filament  6 , the discharge of a malfunction of the lamp  5 , through the inductor  7 , and the primary winding  19 , which has the necessary and sufficient inductive reactance to limit these current waveforms. 
     These lengthy downloads generate heat in the primary winding  19 , in order to avoid these warm, this invention has a circuit of two high recovery diodes  14  and  15 , whose anodes are directly connected respectively to the ends of primary winding  19 , and cathodes which are linked together connected to a resistor  16 , where its other end is directly connected to the negative potential of the circuit point  35 , and thus is able to send negative (−)  35 , more frequent discharges to the stipulated so the primary winding  19  can not induce enough voltage in the secondary winding  17  antagonist, so that it can generate enough current to make the transistor driver  1  and the condenser  2  and the condenser  4 , can not be downloaded what the investor ceases to oscillate. For very low power lamps under 10 watts, heating of the primary winding  19 , is not very strong so that cost savings can eliminate high recovery rectifiers  14  and  15  and the resistor  16 , as the circuit ceases to operate due to the inductive reactance of the primary winding to the position of the resistance  31 ,  FIG. 1  not send start signal, the capacitor being charged  2  and  4 , having an abnormality or malfunction of the lamp in with the patent. 
     Once connected a new lamp button is pressed manually contact  33 ,  FIG. 1 , normally open position so that the capacitor  2  and the capacitor  4  through the strands  3  and  6 , the new lamp  5 , download and return the investor to operate as normal. 
     For the capacitors  2  and  4 , remain energized and the inverter stops scrolling in case of malfunction of the lamp  5 , it is necessary that the resistance  31 , is connected across the primary winding  19 , the inductance  7 , strands  3  and  6 , the lamp  5  and the capacitor  4  and  2 , the positive (+)  34  in the old technology the resistance  31  is directly connected to the feeder pole  34  or  35 , so the diac  32 , will be sending impulses causing the transistor  9 , the driver no matter what the discharge lamp, as investors continue swinging to prevent the transistor  9 , stop driving discharging the capacitor  2  and the capacitor  4  through the transistor  1 . 
     The characteristic high inductive reactance of the tubular core transformer  FIG. 5 , the minimum is achieved by maintaining the path of the magnetic field lines at its core, this dimension is limited in its inner diameter to space windings requiring three turns with minimal and to reduce the reluctance of the core is necessary to increase the cross sectional area without increasing the magnetic flux path and this is achieved by increasing the longer side of its cross section, so that said core acquires its tubular shape and its length is increases to a limit such that the resulting inductive reactance does not decrease the resonant frequency of design, as well as to limit discharges of higher frequency to pass through its windings. 
     The capacitor  42  and inductor  27  form a filter to protect the inverter circuit on phenomena that occur in the line of AC power connected to points  40  and  41 . 
     Values of a circuit illustrating the invention  FIG. 1  and  FIG. 8 . 
     We present two cases 17 Watts and 80 Watts to illustrate the scope that has the invention. 
     Voltage doubler to 120 volts AC power in both cases. 
     
       
         
           
               
               
             
               
                   
               
               
                 For a lamp of 17 Watts 
                 For two lamps of 40 Watts 
               
               
                   
               
             
            
               
                 1, 9, Transistor 
                 1, 9, Transistor 
               
               
                 MJE 13007 To 220 
                 MJE 13007 To 220 
               
               
                 2, capacitor polyester 
                 2, 44, polyester capacitor 
               
               
                 .047 UF to 400 v 
                 .047 uF to 400 v 
               
               
                 4, polyester capacitor 
                 4, 46, polyester capacitor 
               
               
                 .0039 UF at 1600 V 
                 .021 uF at L600 V 
               
               
                 38, 39 electrolytic capacitor 
                 38, 39 electrolytic capacitor 
               
               
                 22 uF a 250 v 
                 I00 uF a 250 v 
               
               
                 7, Inductance 4.27 mH 
                 7, 48, inductance 2.86 mH 
               
               
                 11, 12 9 ohms Resistance 
                 11, 12 9 ohms Resistance 
               
               
                 Diode AR 
                 Diode AR 
               
               
                 14, 15, 8, 20, 21, 22, 28, 29, 
                 14, 15, 8, 20, 21, 22, 28, 29, 
               
               
                 36, 37 Diode 1N4007 
                 36 37 1N4007 diode 
               
               
                 16, 6.6 megohms Resistance 
                 16, Resistance 70 kohms 
               
               
                 23, 26, 6.8 ohms Resistance 
                 23, 26, 6.8 ohms Resistance 
               
               
                 30, ceramic capacitor 
                 30 ceramic capacitor 
               
               
                 .014 UF at 600 v 
                 .0047 uF at 600 V 
               
               
                 31, 50 k ohms Resistance 
                 31, 100 k ohms Resistance 
               
               
                 32, DIAC DB3 
                 32 DIAC DB3 
               
               
                 A core transformer of a 
                 A core transformer of a 
               
               
                 tubular shape 
                 tubular shape 
               
               
                 .122″ × .111″ × .244″ 
                 314″ × .227″ × .347″ 
               
               
                 primary coil 
                 primary coil 
               
               
                 two windings 
                 two windings 
               
               
                 secondary coil 
                 secondary coil 
               
               
                 three windings 
                 three windings 
               
               
                 27 Inductance Capacitor .01 mH 
                 27 Inductance Capacitor .01 mH 
               
               
                 42 Polyester Capacitor 
                 42 Polyester Capacitor 
               
               
                 .047 uF 600 v 
                 .047 uF 600 v