Abstract:
The present invention relates generally to a simple, low cost ballast for fluorescent lamps that incorporates an integrated circuit and a number of ballast protection functions to cost effectively enhance its reliability. End of lamp life circuitry is provided to shut down the ballast when rectification currents due to lamp aging exceed a predetermined level. This circuitry also functions to stop the ballast operation when the lamp&#39;s voltage exceeds a predetermined cutoff level for a set period of time. Re-ignition circuitry is provided that restarts the ballast when new lamps are installed without shutting off the ballast. Multiple striking attempt circuitry is provided that initiates a predetermined number of striking attempts such that cold or old lamps are quickly ignited without the introduction of excessive flickering.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a Non-Provisional Utility application which claims benefit of U.S. patent application Ser. No. 60/526,723 filed Dec. 3, 2003, entitled “IC-Based Low Cost Reliable Electronic Ballast with Multiple Striking Attempts and End of Lamp Life Protection” which is hereby incorporated by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX 
   Not applicable 
   BACKGROUND OF THE INVENTION 
   The present invention relates generally to electronic ballasts for gas discharge lamps. Electronic ballasts for gas discharge lamps are well known in the art and include a variety of different types of protection features and capabilities. For example, the prior art includes electronic ballasts that use end of lamp life protection circuits that are designed to protect the electronic ballast and the gas discharge lamp from being damaged by an end of lamp life condition. The prior art also includes electronic ballasts that include re-ignition circuits that are designed to automatically ignite a gas discharge lamp when it is reconnected to the electronic ballast. In addition, the prior art includes electronic ballasts that include multiple striking circuits that are designed to generate multiple striking attempts that can be used to ignite cold, new, or old gas discharge lamps that can be difficult to ignite with a single strike. 
   An end of lamp life condition is a condition that occurs when a gas discharge lamp reaches the end of its effective operating lifetime. When this occurs, the gas discharge lamp can begin to rectify the AC current applied to the lamp. The gas discharge lamp can rectify the AC current in a positive direction, commonly referred to as positive rectification, or in a negative direction, generally referred to as negative rectification. Regardless of the direction of rectification, the rectification causes the peak to peak voltage across the lamp to gradually increase and, as a result, the power drawn by the gas discharge lamp, and thus the ballast, increases as the lamp ages. This is an undesirable condition in that the ballast is typically very sensitive to the increased power it has to deliver to the lamp and it will often overheat and be destroyed by the increased power. This situation can also cause damage to the gas discharge lamp. 
   Electronically ballasted T 4  and T 5  lamps already require end of lamp life (EOLL) shutdown protection and this type of protection is becoming more and more accepted as an industrial standard. The end of lamp life protection circuits in the prior art are designed to sense an end of lamp life condition in a gas discharge lamp and to compensate for this condition before the electronic ballast or the gas discharge lamp can be damaged by the various end of lamp life conditions that occur. Typically, the protection circuits are designed to command the electronic ballast to simply shut down completely. Alternatively, the protection circuits can cause the electronic ballast to reduce the power delivered to the gas discharge lamp to a safe level that will not damage the electronic ballast or the gas discharge lamp. 
   It is also known that new and/or cold lamps are hard to start because of the inactivity of the mercury contained in the lamps. For relatively old lamps, more striking efforts are needed to ignite the lamp due to the depletion of their fluorescent coatings over time. Thus, the ability to perform multiple striking attempts is a feature that is designed to compensate for such hard-striking lamps. In addition, an automatic re-ignition function is often provided to make lamp replacement easier by insuring that the ballast will restart the lamps after the expired lamps have been replaced by new ones. However, prior art solutions to these problems are expensive, energy inefficient and often ineffective. 
   One example of an electronic ballast including end of lamp life protection is described in U.S. Pat. No. 6,420,838, issued to Shackle on Jul. 26, 2002 and entitled “Fluorescent Lamp Ballast with Integrated Circuit”. The &#39;838 patent is directed toward a series resonant parallel-loaded (SRPL) circuit ballast with a DC blocking capacitor located in the rear end. The circuit has full end of lamp life protection in which the DC voltages between a half-bridge inverter and the blocking capacitor are compared. The difference between the voltages determines the extent of lamp DC rectification. Excessive lamp voltage protection is achieved by detecting the lamp current spike. However, such a system does not provide multiple striking protection and the required components are complicated and expensive. 
   Allison, et al., in U.S. Pat. No. 6,366,032 entitled “Fluorescent Lamp Ballast with Integrated Circuit”, discloses an interdependent circuit for the same ballast topology having all of the protection functions except for the DC lamp rectification. However, all the protections are heavily dependent on a slow-response EOLL shut down circuit and have difficulty fully cooperating with each other. 
   U.S. Pat. No. 5,925,990, issued to Crouse et al. on Jul. 20, 1999 and is entitled “Microprocessor Controlled Electronic Ballast.” In the &#39;990 patent, Crouse, et al. employs a powerful microprocessor as the ballast control to achieve the desired level of protection. Unfortunately, such a microprocessor is expensive and requires additional hardware such as a crystal and voltage regulator to function properly. The software programming required is also a time consuming endeavor that should be avoided if possible. 
   Although the prior art does teach several different types of protection circuits for electronic ballasts, these circuits have several disadvantages. For example, end of lamp life protection circuits taught by the prior art must be designed to handle very high currents and, as a result, dissipate large amounts of power. This makes these types of protection circuits inefficient. In addition, many prior art end of lamp life protection circuits sense DC rectification end of lamp life conditions or excessively high AC end of lamp life conditions, but not both. Prior art re-ignition circuits can also inadvertently attempt to reignite a lamp load even after a ballast has been shut down by another protection circuit. 
   In addition to the above-referenced disadvantages of prior art protection circuits, the inventors have also recognized that the prior art does not appear to teach one protection circuit that includes all of the desired protection and capabilities described above in an inexpensive, simple but reliable package. The prior art ballasts require expensive microprocessors or complicated circuits including a large number of component parts to accomplish each protection feature separately, both of which are very undesirable from the consumer and the manufacturer viewpoint. 
   Therefore, what is needed is an electronic ballast that includes end of lamp life protection, re-ignition capabilities, and multiple striking capabilities in an inexpensive, simple package and that overcomes the disadvantages of prior art electronic ballasts. 
   BRIEF SUMMARY OF THE INVENTION 
   A preferred embodiment of the present invention is directed toward an electronic ballast for igniting and powering at least one gas discharge lamp. The electronic ballast includes an AC/DC converter circuit for receiving an AC voltage and converting the AC voltage into a DC voltage. An integrated circuit controls the ballast. An inverter circuit receives the DC power and produces an output AC voltage. An end of lamp life circuit detects a positive or negative DC rectification current exceeding a predetermined threshold being produced by an installed gas discharge lamp and turns off the integrated circuit if such predetermined threshold is exceeded. The end of lamp life circuitry further detects excess symmetric lamp voltages and shuts down the integrated circuit if such excess symmetric lamp voltages are detected. A multiple striking circuit performs a predetermined number of striking attempts to light an installed light. The multiple striking circuit includes a charge pump and a storage capacitor wherein each striking attempt causes the charge pump to provide an amount of charge to the storage capacitor. The storage capacitor produces a turn-off voltage for disabling the integrated circuit after receiving a predetermined amount of charge from the charge pump. A re-ignition circuit connected to the inverter circuit automatically attempts to ignite a new lamp that has been installed in the ballast. The re-ignition circuitry utilizes a low voltage power supply to detect the presence of installed lamp filaments, a filament voltage to suppress a ballast starting signal after ignition, and a capacitor charged from the low voltage power supply to trigger a ballast starting procedure. A DC blocking capacitor isolates the inverter circuit from DC voltages in the end of lamp life circuit, multiple striking circuit and/or re-ignition circuit. 
   Another embodiment of the present invention is directed toward an electronic ballast for igniting at least one gas discharge lamp. The ballast includes an integrated circuit for controlling the ballast. An inverter receives a DC voltage and applies the DC voltage to a series-resonant tank such that an AC voltage is produced. A pair of output terminals receives the at least one gas discharge lamp and applies the produced AC voltage to the gas discharge lamp. Re-ignition circuitry detects if a lamp is connected between the output terminals and initiates a lamp ignition procedure when a newly installed lamp is detected between the output terminals. The re-ignition circuitry utilizes a voltage across the output terminals to detect the presence of an installed lamp and a charged capacitor to initiate a ballast ignition procedure. The re-ignition circuitry uses a voltage across the output terminals to suppress the ignition procedure after a lamp has been ignited. Multiple striking attempt circuitry is provided that includes a charge collecting capacitor for triggering a predetermined number of striking attempts to attempt to ignite a lamp wherein the striking attempts are terminated when the lamp is ignited or the predetermined number of striking attempt is exceeded. The multiple striking attempt circuitry includes a charge pump. Each striking attempt causes the charge pump to provide an amount of charge to the charge collecting capacitor and the capacitor produces a turn-off voltage for disabling the ballast after receiving an amount of charge from the charge pump. End of lamp life detection circuitry detects an end of lamp life condition and disables the ballast when such an end of lamp life condition is detected. The end of lamp life circuit detects both positive and negative rectification voltages across the output terminals and disables the ballast if the detected voltages exceed a predetermined value. The end of lamp life circuitry also detects excess symmetric lamp voltages and disables the ballast if the detected voltages exceed a predetermined value. A DC blocking capacitor isolates the inverter from DC voltages. 
   Yet another embodiment of the present invention is directed toward a method of protecting an electronic ballast for igniting and powering at least one gas discharge lamp from damaging conditions. In accordance with the method, positive and negative voltages developed across a lamp installed in the ballast are monitored to determine if an end of lamp life condition has occurred and the ballast is disabled if such a condition is detected. Installation of a new lamp in the ballast is detected and an ignition procedure is initiated if a newly installed lamp is detected. A voltage across a pair of output terminals is used to detect the presence of the installed lamp and a charged capacitor is used to initiate a ballast ignition procedure. The voltage across the output terminals is also used to suppress the ignition procedure after the lamp has been ignited. Ignition strikes are produced when an ignition procedure is initiated until an installed lamp is ignited or until a predetermined number of strikes have been produced. A blocking capacitor is used to isolate an output of an inverter of the ballast from selected DC voltages. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of integrated circuit based electronic ballast constructed in accordance with one embodiment of the present invention; 
       FIG. 2  is a schematic diagram of an end-of-lamp life detection circuit constructed in accordance with a preferred embodiment of the present invention; 
       FIG. 3  is a schematic diagram of a multiple striking attempt circuit constructed in accordance with one embodiment of the present invention; and 
       FIG. 4  is a schematic diagram of a filament sensing and re-ignition circuit constructed in accordance with a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   One embodiment of the present invention is directed toward providing a low cost, reliable electronic ballast having: (1) an end of lamp life protection feature, (2) a multiple striking attempt feature and/or (3) a re-ignition feature all contained in one economical, simple and reliable package. More particularly, the invention is directed toward a gas discharge lamp ballast with a series-resonant, parallel-loaded tank for at least one gas discharge lamp having a DC blocking capacitor located in the front end of the output of the half-bridge inverter such that all the protection functions are independent of each other. Due to the independent nature of the protection functions, a ballast in accordance with the present invention may incorporate any or all of the advanced features. 
   Referring now to  FIG. 1 , a schematic diagram of an IC-based, low cost electronic ballast  100  in accordance with one embodiment of the present invention is shown. The ballast includes an AC to DC converter  102  which provides a constant DC bulk voltage  104  for use by the ballast. Preferably, the AC power source for the converter  102  is simply a local electric utility company&#39;s AC power supply that is accessed using a common electrical outlet found in a typical home or business. AC/DC converters  102  are well known in the art and any one of a variety of different types of rectifiers may be used with the present invention. For example, the prior art includes simple rectifiers that include a single diode, half bridge rectifiers that include two diodes, and full bridge rectifiers that include four diodes. 
   A half-bridge inverter comprised of transistors  106  and  108  is driven by a driver integrated circuit (IC) (microcontroller)  110 . In other embodiments, a full bridge inverter circuit, a push pull circuit, or a parallel resonant LC circuit may be used to drive the transistors  106  and  108 . The inverter microcontroller  110  can be a L6574—CFL/TL Ballast Driver Preheat and Dimming microcontroller manufactured and sold by ST Microelectronics. However, in alternative embodiments, various other microcontrollers may be used as well. The driver IC  110  is configured to alternately switch transistors  106  and  108  on and off at a predetermined frequency. A series resonant, parallel-loaded output circuit comprised of series connected inductor  112  and capacitor  114  is attached between the series connected transistors  106  and  108  through a DC blocking capacitor  116 . The DC blocking capacitor  116  serves to isolate the transistors  106  and  108  from DC currents produced in other sections of the electronic ballast  100 . 
     FIG. 1  includes dashed boxes  120 ,  122  and  124  showing the general topology of the EOLL protection sub-circuits  120 , re-ignition circuitry  122 , and multiple striking circuitry  124 . The respective circuits  120 ,  122  and  124  are discussed in more detail herein below with regard to  FIGS. 2-4 . The sub-circuits  120 ,  122  and  124  are included for ease of understanding and should not be interpreted to mean that a particular sub-circuit  120 ,  122  and  124  includes, or must include, all of the components included in the sub-circuits. Because of the layout of the detailed schematic shown in  FIG. 1 , the sub-circuits  120 ,  122  and  124  may lack some components that are required by a particular functional circuit or include some additional circuit components that perform other functions. Those skilled in the art will appreciate that it can be difficult to precisely separate and isolate one portion of a functioning sub-circuit from the circuit as a whole. 
   As discussed in more detail below with respect to  FIGS. 2 ,  3  and  4 , the EOLL protection circuitry  120  functions to protect against high voltage and DC rectification problems caused by degradation of a gas discharge lamp over time. The re-ignition circuitry  122  insures that new lamps can be safely installed and ignited while the ballast remains powered  100 . The multiple striking circuitry  124  serves to help ignite new, cold or otherwise difficult to ignite lamps without introducing annoying flickering. The DC blocking capacitor  116  helps isolate the various circuit functions from one another such that they can be individually configured and implemented. 
   As also shown in  FIG. 1 , the ballast  100  includes a variety of additional conventional circuit components that are well known in the art and are not discussed in detail as they are not necessary for a proper understanding of the present invention. For example, the resistor/capacitor pairs connected to pins  8  and  9  of the inverter driver integrated chip  110  are used to filter noise out of the control signals applied to the pin as is well known in the prior art. 
   Referring now to  FIG. 2 , a preferred end-of-lamp life (EOLL) detection circuit  200  constructed in accordance with one embodiment of the present invention is shown. The EOLL protection circuit  200  is operable to sense the voltage applied by the ballast across the lamp load comprised of lamps  214  and  216  and to generate an end of lamp life control signal  232  when the sensed voltage exceeds a predetermined level for a predetermined time period that turns off the ballast driver IC  230 . The EOLL control signal can also be used to cause the ballast to enter an end of lamp life protected state so that the ballast and the lamp load cannot be damaged by an end of lamp life condition. As is well known in the art, gas discharge lamps  214  and  216  included in the lamp load of the present invention rectify AC current, i.e., generate a DC current in response to an applied AC current, as they approach the end of their effective operating lifetimes. The lamp rectification due increasing age may generate a positive DC voltage, referred to as positive rectification, or a negative DC voltage, referred to as negative rectification. In addition, in some cases, the failure of lamps  214  and  216  causes an excessively high symmetric voltage to appear across the lamps. 
   The end of lamp life protection circuit  200  includes a half-bridge inverter comprised of transistors  204  and  206  connected to a series resonant tank comprised of DC blocking capacitor  208 , resonant inductor  210  and resonant capacitor  212 . The two series connected lamps  214  and  216  are connected in parallel with resonant capacitor  212 . The gas discharge lamps  214  and  216  include one or more gas discharge lamps that operate using AC voltages and currents. Gas discharge lamps  214  and  216 , such as fluorescent lamps, are well known in the art and any one of a variety of these lamps may be used with the present invention. 
   The circuit  200  detects (in either direction) the lamps&#39; DC rectification and any excessive symmetric lamp voltage. In normal operation, the voltage across the large value capacitor  218  has two roots: positive DC biased voltage derived from the DC voltage divider path defined by power supply  202  and resistors  220 ,  222 ,  224  and  226 , and the relatively small value of the resistance of the lamps  214  and  216 , and negative charging from the top filament through anti-parallel diode  228 . When there is no DC lamp rectification and the voltage across lamps  214  and  216  is normal, these two voltage components can be made to cancel each other out by selecting the appropriate values of the resistors  220 ,  222 ,  224  and  226 . The total effect of properly selecting the resistive values is that there is no positive voltage on capacitor  218  when the lamps  214  and  216  are properly operating. Thus, when the ballast is operating normally, the inverting input pin  228  of the IC  230  internal operational amplifier is zero and there is no triggering voltage applied to the shut-down pin  232  of IC  230 . 
   However, when positive lamp rectification does occur, the DC voltage divider  220 ,  222 ,  224  and  226  will reflect this positive voltage. The voltage across the divider capacitor  218 , and thus the inverting input  228 , will be positive. Since the operational amplifier in the IC  230  is employed as a voltage inverter with a gain determined by the ratio of resistor  234  to resistor  236 , the output on pin  238  will be of negative value. Due to the unidirectional conduction of diodes  240  and  242 , IC  230  pin  232  will only see a positive voltage after the forward voltage drop of diode  240 . The IC shutdown pin  232  is the inverting input to an internal comparator which compares the input voltage with an internal reference voltage that is preferably set to 0.6V. The DC rectification level is preferably set to around 45V and the ballast shut down within 30 seconds of detecting such a lamp rectification voltage. The capacitance of capacitor  218  is preferably chosen to be large so that the time constant is long enough to avoid detection of a false triggering signal which might be generated during a pre-heating stage. When the positive rectification comes to 45V, the voltage cross the capacitor  218  will be 1.2V and, thus, the IC  230  will be shut down and remain in a standby mode of operation. Likewise, when the negative rectification becomes −45V, the voltage on capacitor  218  will also mirror the negative voltage accordingly. This negative voltage will be inverted and amplified through the IC&#39;s  230  internal operational amplifier so that the output pin  238  of the operation amplifier will be 1.2V with the same time constant. In this way, diode  242  conducts and diode  240  is reverse biased. Thus, the shut down pin  232  of IC  230  will be triggered to protect the ballast from damaging operation regardless of whether the DC lamp rectification that occurs is positive or negative in polarity. 
   Similar to DC lamp rectification, when the lamp voltage increases, the voltage on capacitor  218  decreases due to the negative charging through diode  229 . This negative voltage is then inverts by the operational amplifier in IC  230 . Eventually, if the lamp  214  and  216  voltage exceeds the predetermined rectification value, the operational amplifier output pin  238  will rise to 1.2V and trigger IC shut-down pin  232  which turns off IC  230 . Hence, the ballast system is also protected from excessive symmetric voltages that arise from lamp degradation. 
   Customers prefer lamp ballasts that provide a multiple striking capability for use in striking hard to ignite lamps. Cold, new, and old lamps can often be difficult to ignite using only a single striking attempt. The ballast protection circuit of the present invention commands the ballast to generate multiple striking attempts in order to ignite these types of lamps. The ballast protection circuit of the present invention, however, is not designed to provide an indefinite number of strikes. Circuits that provide an indefinite number of striking attempts can cause the lamp to repeatedly flash off and on. Not surprisingly, many customers find this flashing to be annoying. Accordingly, the ballast protection circuit of the present invention preferably provides an adjustable, limited number of striking attempts to prevent this type of situation from occurring. 
     FIG. 3  illustrates one embodiment of the multiple striking attempt circuitry  300  of the present invention shown in  FIG. 1 . The circuitry  300  is composed of two main parts, the restarting circuitry and the charge pump. The restarting is accomplished with the half-bridge current sensing resistor  302 . During the striking phase, the voltage across sensing resistor  302  grows as the frequency sweeps down from the relatively higher preheat frequency to the relatively lower frequency that is close to the unloaded resonance frequency. Once the voltage across resistor  302  grows to a sufficiently level, the re-ignition pin  316  is triggered and the striking process is restarted. 
   The charge pump circuitry, comprised of resistor  304  and electrolytic capacitor  306 , receives power from the low voltage potential of the top blue filament of the lamp V Fbt    307  through the zener diode  308 . Normally, when the ballast is operating in the steady state and during the preheat stage, the peak voltage of the blue auxiliary winding  307  is less than the breakdown voltage of the zener diode  308 . Thus, during normal operation, there is no charging of the capacitor  306  at all. On the other hand, during the striking phase, the resonant circuit operates around the resonance to provide the high open circuit voltage necessary to strike the lamps by sweeping down the driven half bridge frequency. The peak voltage across the blue auxiliary winding grows correspondingly until it is higher than the zener diode  308  breakdown voltage and the charging of capacitor  306  begins. This charging ends once the voltage across the sensing resistor  302  reaches 1.2V and, thus, triggers re-ignition pin  316  on the IC  310 . 
   The ballast is supposed to be able to start a lamp on the first try if the lamp is in good shape. However, for an aging lamp or even a new lamp, a single striking is not guaranteed to light the lamp. Nevertheless, the lamp will be easier to strike after the first attempt if another try is made immediately. With the present invention some charge will be placed on the capacitor  306  and will remain there after each striking attempt. More energy will be stored with each strike and, thus, a stepped-up voltage level will be built up on capacitor  306  with each additional strike. When the voltage across the capacitor  306  reaches the required conduction voltage (typically 0.6V) for transistor  312 , the leakage through the filter created by resistor and capacitor on pin  314  of the IC  310  (shown in  FIG. 3 ) will be provided by the power supply  311  instead of from the charge pump capacitor  306 . The voltage across the capacitor  306  thus accumulates steadily until it reaches to around 1.2V. When the voltage builds up to 1.2V, the shutdown pin  314  on the IC  310  will be triggered. The lamp will be assumed bad after the determined number of striking attempts has occurred and the ballast will shut down. The voltage on pin  318  is normally at 2V and drops to 0V when the IC  310  shuts down. Pin  318  is used to quickly discharge the accumulated energy in the capacitor  306  after the IC  310  shuts down. Typically, the maximum number of striking attempts is set from 2 to 15 depending on the different lamp loads since to do so is considered safe and does not produce annoying flickering. 
   It is desirable for a ballast to automatically shut down, or to be placed in some other type of protected state, i.e., a disconnected protected state, when a lamp is disconnected from the ballast to ensure that the high voltage present at the lamp connection terminals of the ballast output circuit does not pose any harm to customers or the ballast. Customers also prefer ballasts that automatically reignite, i.e., ignite a newly installed gas discharge lamp, when a bad lamp is disconnected from the ballast and a new lamp is connected to the ballast while the input power remains on. Therefore, as set forth in more detail below, a preferred embodiment of the present invention has re-ignition circuitry that performs these functions. 
   Referring now to  FIG. 4 , the re-ignition circuit is operable to sense lamp filament continuity when the lamp load is reconnected to the ballast after previously being removed and to generate an ignition control signal that can be used to cause the inverter circuit to attempt to ignite the newly installed lamp load. It should be noted that the power applied to the ballast remains on during the disconnection and reconnection process. In addition, as explained in more detail below, the re-ignition control signal is only generated after the lamp load has been disconnected for a predetermined amount of time. 
   In  FIG. 4 , the DC path  401  from DC power supply  412  is only possible when both the red filament and the blue filament are present for each installed lamp. The DC voltage divider capacitor  410  is biased from the power supply  412 . In the steady state, a positive DC bias voltage is formed by the parallel connection of filament path resistors  402 ,  404 ,  406  and  408  and end-of-lamp life sensing circuit resistors  222 ,  224 , and  226  shown in  FIG. 2  connected in series with resistor  402 . At the same time, however, the voltage across capacitor  410  is cancelled by the negative charging voltage provided by diode  414 , resistors  416  and  408  and capacitor  410 . Consequently, there will be no trigger voltage provided to the shutdown pin of the inverter IC shown in  FIG. 1  during steady state operation. 
   The DC voltage will increase on top of the red filament when the ballast is powered but remain constant if the filament sensing path through the lamps is broken. Whenever good lamps are placed into the sockets, the filament sensing path will be completed and the voltage across capacitor  410  will be only the positive DC biased voltage. This voltage will be charged quickly and come to 1.2V to trigger the re-ignition pin  418  (shown as pin  9  of U 2  in the  FIG. 1 ). The ballast starting procedure will then be initiated by the ballast IC. 
   Thus, although there have been described particular embodiments of the present invention of a new and useful IC-Based Low Cost Reliable Electronic Ballast with Multiple Striking Attempts and End of Lamp Life Protection, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.