Failing lamp monitoring and deactivating circuit
First Claim
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1. A discharge lamp monitoring and deactivating circuit comprising the combination ofa discharge lamp;
- a source of electrical energy connected to said lamp to ignite and operate said lamp as a source of visible illumination;
switch means coupling said lamp to said source to control the activation of said lamp in response to control signals;
detection circuit means connected to said lamp for monitoring the A.C. operating voltage of said lamp under operating conditions to detect a substantial change between similar halves of successive cycles of the operating voltage indicative of imminent failure of said lamp and for producing control signals for deactivating said lamp when failure thereof is imminent; and
means coupling said detector circuit to said switch means whereby said switch means can respond to said control signals from said detector circuit means.
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Abstract
A discharge lamp monitoring and deactivating circuit includes a normally closed switch in series with the discharge lamp and its ballast and a detector circuit connected across the lamp to monitor lamp operating voltage. The detector circuit includes a capacitor which is charged and discharged through separate paths so that a lamp electrical waveform change waveform can be detected, resulting in a net charge. The charge is used to open the switch after a time delay which is only manually resetable.
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12 Claims
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1. A discharge lamp monitoring and deactivating circuit comprising the combination of
a discharge lamp; -
a source of electrical energy connected to said lamp to ignite and operate said lamp as a source of visible illumination; switch means coupling said lamp to said source to control the activation of said lamp in response to control signals; detection circuit means connected to said lamp for monitoring the A.C. operating voltage of said lamp under operating conditions to detect a substantial change between similar halves of successive cycles of the operating voltage indicative of imminent failure of said lamp and for producing control signals for deactivating said lamp when failure thereof is imminent; and means coupling said detector circuit to said switch means whereby said switch means can respond to said control signals from said detector circuit means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of monitoring the operation of a discharge lamp and deactivating the lamp under impending failure conditions comprising
monitoring the characteristics of the lamp operating voltage waveform under normal operating conditions; -
detecting a change in a waveform characteristic form one portion of the waveform to another, the change being indicative of impending lamp failure; and deactivating the lamp when the change is detected.
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Specification