Controlled driven series-resonant ballast

An arrangement comprising:

• a load circuit having a pair of load circuit input terminals and a pair of load circuit output terminals;
• the load circuit output terminals being disconnectably connected with a pair of lamp terminals of a gas discharge lamp;
• and
• an inverter circuit having a pair of DC input terminals connected with a source of DC supply voltage and a pair of AC output terminals connected with the load circuit input terminals;
• the inverter circuit providing an AC output voltage at the AC output terminals;
• the AC output voltage (i) consisting of substantially rectangular voltage pulses of alternating polarity, (ii) having a fundamental frequency, and (iii) having a fundamental period;
• the inverter circuit being further characterized in that:
• (a) whenever the gas discharge lamp is indeed connected with the load circuit output terminals and is drawing a lamp current therefrom, each voltage pulse has a duration equal to about half the duration of the fundamental period;
• and (b) whenever the gas discharge lamp is not so connected, each voltage pulse has a duration distinctly shorter than half that of the fundamental period.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC supply terminals;
• an inverter circuit connected with the DC supply terminals and providing an AC voltage at a pair of inverter terminals;
• the AC voltage consisting of substantially rectangular voltage pulses of alternating polarity;
• the voltage pulses occurring at a pulse frequency;
• each voltage pulse having a pulse duration;
• the inverter circuit being further characterized by including a control sub-assembly connected in circuit therewithin and operative to control the pulse frequency as well as the pulse duration;
• the control sub-assembly having a first and a second control input;
• the pulse frequency being controllable by application of a first control signal to the first control input;
• the pulse duration being controllable by application of a second control signal to the second control input and in such manner that the pulse duration may be controlled independently of the pulse frequency;
• and
• a load circuit connected with the inverter terminals;
• the load circuit including a disconnectable gas discharge lamp.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC supply terminals;
• an inverter circuit connected with the DC supply terminals and providing an AC voltage at a pair of inverter terminals;
• the AC voltage consisting of substantially rectangular voltage pulses of alternating polarity;
• each voltage pulse being separated from the immediately following voltage pulse by a period of near-zero-magnitude voltage;
• the voltage pulses occurring at a pulse frequency;
• each voltage pulse having a pulse duration;
• the inverter circuit being further characterized by including a control sub-assembly connected in circuit therewithin and operative to determine the pulse frequency as well as the pulse duration;
• the control sub-assembly having a first and a second control input;
• the pulse frequency being controllable by application of a first control signal to the first control input;
• the pulse duration being controllable by application of a second control signal to the second control input;
• and
• a load circuit connected with the inverter terminals;
• the load circuit including a disconnectable gas discharge lamp.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC supply terminals;
• an inverter circuit connected with the DC supply terminals and providing an AC voltage at a pair of inverter terminals;
• the AC voltage having a fundamental frequency and consisting of half-cycles of alternating polarity;
• each half-cycle consisting of a substantially rectangular voltage pulse of relatively high magnitude followed by a period of relatively low-magnitude voltage;
• the period of relatively low-magnitude voltage having a first duration;
• the substantially rectangular voltage pulse having a second duration;
• the inverter circuit being further characterized by including a control sub-assembly operative to control the fundamental frequency as well as the second duration;
• the control sub-assembly having a first and a second control input;
• the fundamental frequency being controllable by application of a first control signal to the first control input;
• the second duration being controllable by application of a second control signal to the second control input;
• and
• a load circuit connected with the inverter terminals;
• the load circuit including a disconnectable gas discharge lamp.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC supply terminals;
• an inverter circuit connected with the DC supply terminals and providing an AC voltage at a pair of inverter terminals;
• the AC voltage having a fundamental frequency and consisting of half-cycles of alternating polarity;
• each half-cycle consisting of two distinct periods (i) a first period represented by a voltage pulse of substantially rectangular shape and a first magnitude, and (ii) a second period represented by a voltage of low or near-zero magnitude;
• the inverter circuit being further characterized by including a control sub-assembly operative to control the fundamental frequency as well as the duration of the second period;
• the control sub-assembly having a first and a second control input;
• the fundamental frequency being controllable by application of a first control signal to the first control input;
• the duration of the second period being controllable by application of a second control signal to the second control input;
• and
• a load circuit connected across the inverter terminals;
• the load circuit including a disconnectable gas discharge lamp.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC terminals;
• a tank-inductor and a tank-capacitor series-connected across a pair of load terminals;
• the tank-inductor and the tank-capacitor having a natural series-resonance frequency;
• a gas discharge lamp being disconnectably connected in parallel with the tank-capacitor;
• a ballast output voltage existing across the tank-capacitor as long as a certain AC voltage is provided across the load terminals;
• and
• an inverter circuit connected between the DC terminals and the load terminals;
• the inverter circuit being operative to provide the certain AC voltage to the load terminals;
• the certain AC voltage having (ii) a peak-to-peak magnitude that remains substantially constant irrespective of the magnitude of any current flowing from the inverter circuit to the load terminals, and (ii) a fundamental frequency about equal to said natural series-resonance frequency;
• the inverter circuit being further characterized by being operative, whenever the gas discharge lamp is non-connected with the tank-capacitor, to cause the magnitude of the ballast output voltage to be limited to a certain substantially constant level, remaining at this substantially constant level for as long as the gas discharge lamp remains non-connected;
• said certain level being attained without using a clamping-type voltage-limiting means connected in parallel with the tank-capacitor.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC terminals;
• a tank-capacitor and a tank-inductor series-connected across a pair of load terminals;
• the tank-capacitor and the tank-inductor having a natural series-resonance frequency;
• a gas discharge lamp being disconnectably connected in parallel with the tank-capacitor;
• the gas discharge lamp requiring for proper lamp starting to be provided with a voltage of magnitude at least equal to a certain minimum magnitude;
• a ballast output voltage existing across the tank-capacitor whenever a certain AC voltage is being provided at the load terminals;
• and
• an inverter circuit connected between the DC terminals and the load terminals;
• the inverter circuit being operative to provide said certain AC voltage at the load terminals;
• the certain AC voltage having:
• (i) a peak-to-peak magnitude that remains substantially constant irrespective of the magnitude of any current being supplied by the inverter circuit to the load terminals, and (ii) a fundamental frequency about equal to said natural series-resonance frequency;
• the inverter circuit being further characterized by, whenever the gas discharge lamp is non-connected with the tank-capacitor, causing the magnitude of the ballast output voltage to remain substantially constant at a certain level;
• which certain level is at least equal to said certain minimum magnitude;
• the certain level being attained without using a clamping-type voltage-limiting means connected in parallel with the tank-capacitor.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC terminals;
• a tank-capacitor and a tank-inductor series-connected across a pair of load terminals;
• the tank-capacitor and the tank-inductor having a natural series-resonance frequency;
• a gas discharge lamp being disconnectably connected in parallel with the tank-capacitor;
• the gas discharge lamp requiring for proper lamp starting to be provided with a voltage of magnitude at least equal to a certain minimum magnitude;
• a ballast output voltage existing across the tank-capacitor whenever a certain AC voltage is being provided at the load terminals;
• and
• an inverter circuit connected between the DC terminals and the load terminals;
• the inverter circuit being operative to provide said certain AC voltage at the load terminals;
• the certain AC voltage having:
• (i) a peak-to-peak magnitude that remains substantially constant irrespective of the magnitude of any current being supplied by the inverter circuit to the load terminals, and (ii) a fundamental frequency about equal to or higher than said natural series-resonance frequency;
• the inverter circuit being further characterized by including a frequency control sub-circuit operative:
• (a) whenever the gas discharge lamp is non-connected with the tank-capacitor, to cause the fundamental frequency to be relatively high, thereby to cause the magnitude of the ballast output voltage to be substantially constant and have a magnitude at least equal to said certain minimum magnitude;
• and (b) when the gas discharge lamp is connected with the tank-capacitor, to cause the fundamental frequency to be relatively low, thereby to cause the gas discharge lamp to be supplied with an appropriate amount of power.

An arrangement comprising:

• a DC source providing a DC supply voltage at a pair of DC terminals;
• a ballast load circuit connected across a pair of load terminals;
• the load circuit including a pair of ballast output terminals;
• a ballast output voltage existing across the ballast output terminals whenever a certain AC voltage is being provided at the load terminals;
• a gas discharge lamp being connected across the ballast output terminals, thereby to be properly powered whenever said certain AC voltage is being provided;
• and
• an inverter circuit having a pair of DC input terminals connected with the DC terminals and and a pair of inverter output terminals connected with the load terminals;
• the inverter circuit being operative to provide said certain AC voltage to the load terminals;
• the inverter circuit being further characterized by including a first and a second transistor series-connected across the DC input terminals;
• the first and the second transistor having, respectively, a first and a second pair of control input terminals;
• a first and a second drive signal existing, respectively, across the first and the second pair of control input terminals;
• the first drive signal having a waveshape distinctly different from that of the second drive signal.