Ignitor disabler

Claim 1

An ignitor disabler for use with a circuit for igniting a lamp, including an ignitor portion, wherein the lamp has a characteristic voltage which may vary during phases of lamp operation and wherein the lamp has a nominal operating voltage between 52 volts and 100 volts, comprising: (a) a bi-directional triode thyristor or triac which is connected in series with the common line and the ignitor connection point in such a manner that when the triac is turned off it prevents the ignitor from functioning; (b) a circuit connected between a power supply portion and the reset pin of an oscillator chip, the circuit including a zener diode biased such that its breakdown voltage exceeds the voltage at the input of the circuit under normal lamp operating conditions, the circuit being designed to generate an output voltage corresponding to a logic 0 upon sensing conduction by the zenner diode; (c) trigger means comprising: (i) an oscillator chip with pin connections and associated circuit components such that an input voltage corresponding to a logic 0 at the reset pin of the oscillator chip causes an output voltage corresponding to a logic 1 to appear at the output pin of the oscillator chip after a predetermined period of time; (ii) a buffer stage with input connected to the output pin of the oscillator chip; and (iii) an opto-isolator circuit with input connected to the output of the buffer stage in such a manner that a logic 1 voltage generated at the output of the buffer stage when fed to the emitter side of the opto-isolator results in the opto-isolator circuit being turned off thereby engaging the disabling means. (d) A circuit with output connected to the reset pin of the oscillator chip, the circuit being designed to generate an output voltage corresponding to a logic 1 upon sensing lamp ignition being accomplished; (e) A power supply portion comprising: (i) a first stage series resonant circuit connected across the lamp terminals designed to attenuate the high frequency harmonics generated by the high voltage starting pulses, from the lamp voltage and to reduce the voltage; (ii) a second stage full-wave rectifier to receive the output from the first stage designed to generate a substantially direct current type, the voltage equivalent of which is dependent upon the lamp operating voltage, this substantially direct voltage signal forming the input signal for both the threshold establishing circuit and a third stage of the power supply; (iii) a filtering third stage to receive the output from the second stage and designed to generate a signal which more closely approximates a direct current type signal; (iv) a voltage regulating fourth stage to receive the output signal from the third stage and to generate a signal which more closely approximates a direct voltage-type signal; (v) a filtering fifth stage to receive the output signal from the fourth stage and to generate a final signal in which substantially all of the alternating type components have been attenuated.