Electronic ballast with over-voltage protection

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a gas discharge lamp having a pair of lamp terminals and being functional to provide luminous output when supplied with an amount of lamp current;
• and
• a main assembly having (i) a pair of power input terminals connected with the power line terminals, and (ii) a pair of AC output terminals connected with the lamp terminals;
• the main assembly including electronic circuitry and being otherwise characterized by:
• (a) having:
• (i) a tuned L-C circuit connected with the AC output terminals, the L-C circuit having a tank-inductor and a tank-capacitor, the tank-capacitor being effectively connected across the AC output terminals;
• and (ii) a magnitude-limiting sub-assembly connected within the electronic circuitry as well as with the AC output terminals;
• and
• (b) being functional to cause an AC output voltage to exist across the AC output terminals;
• the magnitude of the AC output voltage being determined by a combination of:
• (i) a Q-multiplying effect associated with the L-C circuit;
• (ii) the frequency of the AC output voltage;
• (iii) the amount of power drawn by the lamp from the AC output terminals;
• and (iv) a magnitude-limiting effect provided by the magnitude-limiting sub-assembly in response to the magnitude of the AC output voltage;
• the magnitude-limiting effect, by which an increasing magnitude of the AC output voltage causes a change in the frequency of the AC output voltage away from the natural resonance frequency of the L-C circuit, resulting in a diminishment of the Q-multiplying effect in such a manner as to cause the magnitude of the AC output voltage, whenever no power is being drawn by the lamp, to be distinctly lower than it would have been in the absence of said magnitude-limiting effect.

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a gas discharge lamp having a pair of lamp terminals and being functional to provide luminous output when supplied with lamp current;
• and
• a main assembly having (i) a pair of power input terminals connected with the power line terminals, and (ii) a pair of AC output terminals connected with the lamp terminals;
• the main assembly including electronic circuitry and being otherwise characterized by:
• (a) having:
• (i) a tuned L-C circuit connected with the AC output terminals;
• and (ii) a magnitude-limiting sub-assembly connected within the electronic circuitry as well as with the AC output terminals;
• and
• (b) being functional to cause an AC output voltage to exist across the AC output terminals;
• the magnitude of the AC output voltage being determined by a combination of:
• (i) a Q-multiplying effect associated with the L-C circuit;
• (ii) the amount of power drawn by the lamp from the AC output terminals;
• and (iii) a magnitude-limiting effect provided by the magnitude-limiting sub-assembly in response to the magnitude of the AC output voltage;
• the magnitude-limiting effect, by which an increasing magnitude of the AC output voltage causes a change in the frequency of the AC output voltage away from the natural resonance frequency of the L-C circuit, resulting in a diminishment of the Q-multiplying effect in such a manner as to cause the magnitude of the AC output voltage, whenever no power is being drawn by the lamp, to be distinctly lower than it would have been in the absence of said magnitude-limiting effect.

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a lamp means having lamp terminals and being operative to provide light when drawing a lamp current;
• and
• a main assembly characterized by:
• (i) having power input terminals connected with the power line terminals;
• (ii) having AC output terminals connected with the lamp terminals;
• (iii) being operative to provide an AC output voltage at the AC output terminals, the frequency of the AC output voltage being higher than that of the power line voltage;
• (iv) having a sub-assembly connected within the main assembly as well as with the AC output terminals, the sub-assembly being operative under a certain condition, by causing a change in the frequency of the AC output voltage, to limit the magnitude of the AC output voltage to a level lower than what it would have been if the sub-assembly had not been so connected, said certain condition occurring if the lamp means were to fail to draw said lamp current;
• such that if the sub-assembly were to be disconnected, and if the lamp means were to fail to draw said lamp current, the magnitude of the AC output voltage would attain a level substantially higher than the level attained with the sub-assembly connected;
• and (v) having a pair of terminals between which two transistors are series-connected and across which exists a DC supply voltage.

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a lamp having lamp terminals and being operative to provide light when being supplied with a lamp current;
• and
• a main assembly characterized by:
• (i) having power input terminals connected with the power line terminals;
• (ii) having AC output terminals connected with the lamp terminals, thereby to cause said lamp current to be supplied to the lamp;
• (iii) being operative to provide an AC output voltage at the AC output terminals, the frequency of the AC output voltage, which is much higher than that of the power line voltage, increasing with increasing magnitude of the AC output voltage;
• (iv) having an L-C circuit connected with the AC output terminals, the L-C circuit having a natural resonance frequency not higher than the fundamental frequency of the AC output voltage;
• (v) having a pair of transistors series-connected between two terminals across which is provided a DC voltage whose absolute magnitude always is equal to or higher than that of the power line voltage;
• and (vi) having a sub-assembly connected within the main assembly as well as with the AC output terminals, the sub-assembly being operative under a certain condition to limit the magnitude of the AC output voltage to a level lower than what it would have been if the sub-assembly had not been so connected, said certain condition occurring if the lamp were to fail to draw said lamp current;
• such that, if the sub-assembly were to be disconnected, the magnitude of the AC output voltage would reach an undesirably high level in case the lamp were to be disconnected or otherwise fail to draw said lamp current.

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a lamp having lamp terminals and being operative to provide light when drawing a lamp current;
• and
• a main assembly characterized by:
• (i) having power input terminals connected with the power line terminals;
• (ii) having AC output terminals connected with the lamp terminals;
• (iii) providing an AC output voltage at the AC output terminals, the AC output voltage having a frequency that changes in response to the magnitude of the AC output voltage;
• (iv) having two terminals between which a pair of transistors are series-connected and across which exists a DC voltage whose absolute magnitude is about equal to or higher than that of the power line voltage;
• and (v) having a sub-assembly connected within the main assembly as well as with the AC output terminals, the sub-assembly being operative under a certain condition to limit the magnitude of the AC output voltage to a level lower than what it would have been if the sub-assembly had not been so connected, said certain condition occurring if the lamp were to fail to draw said lamp current;
• such that if the sub-assembly were to be disconnected, and if the lamp were to fail to draw said lamp current, the magnitude of the AC output voltage would attain a level substantially higher than the level attained with the sub-assembly connected.

An arrangement comprising:

• a power source operative to supply a power line voltage at a pair of power line terminals;
• a lamp having lamp terminals and being operative to provide light when drawing a lamp current;
• and
• a main assembly characterized by:
• (i) having power input terminals connected with the power line terminals;
• (ii) having AC output terminals connected with the lamp terminals;
• (iii) providing an AC output voltage at the AC output terminals;
• (iv) having two terminals between which a pair of alternatingly switching transistors are series-connected and across which is provided a DC voltage whose absolute magnitude is always distinctly higher than that of the power line voltage;
• and (v) having a sub-assembly connected within the main assembly as well as with the AC output terminals, the sub-assembly being operative under a certain condition to cause the frequency of the AC output voltage to change, thereby to limit the magnitude of the AC output voltage to a level lower than what it would have been if the sub-assembly had not been so connected, said certain condition occurring if the lamp means were to fail to draw said lamp current;
• such that if the sub-assembly were to be disconnected, and if the lamp means were to fail to draw said lamp current, the magnitude of the AC output voltage would attain a level substantially higher than the level attained with the sub-assembly connected.

An arrangement comprising:

• a power source operative to supply an AC power line voltage at a pair of power line terminals;
• and
• a combination of:
• (A) a gas discharge lamp having a pair of lamp terminals and being functional to provide luminous output when supplied with an amount of lamp current;
• the gas discharge lamp being further characterized by including:
• (i) two parallel-disposed relatively long straight sections of tubing, each one having a first cross-sectional area;
• and (ii) a relatively short section of tubing having a second cross-sectional area that is substantially smaller than said first cross-sectional area;
• (B) a main assembly having:
• (i) a pair of power input terminals adapted to connect with a pair of terminals across which exists said AC power line voltage;
• and (ii) a pair of AC output terminals connected with the lamp terminals;
• the main assembly including electronic circuitry and being otherwise characterized by:
• (1) having a tuned L-C circuit connected with the AC output terminals, the L-C circuit having a tank-inductor and a tank-capacitor, the tank-capacitor being effectively connected across the AC output terminals;
• and
• (2) whenever an ordinary AC power line voltage is present across the power input terminals, being operative to cause an AC output voltage to exist across the AC output terminals;
• and
• (C) a mechanical structure having a screw-base operable to be screwed into and held by an ordinary Edison-type lamp socket;
• the mechanical structure also being functional to rigidly hold together the gas discharge lamp and the main assembly, thereby to form a single lamp-ballast entity operable to be screwed into and powered from the AC power line voltage usually provided at an ordinary Edison-type lamp socket.