Circuit for eliminating low battery voltage alarm signal at night
First Claim
1. In a battery voltage alarm circuit including means for comparing a first signal which is a function of the battery voltage to a relatively fixed reference signal and indicating means for providing an alarm output when the first signal is less than the reference signal to indicate low battery voltage, the improvement comprising condition-responsive control means for automatically shifting the level of one of the first and reference signals for varying the difference therebetween thereby to vary the time at which the alarm output can occur.
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Accused Products
Abstract
A battery-operated smoke alarm includes an alerting signal means for indicating when the battery voltage is low by comparing a first signal which is a function of the battery output voltage with a relatively fixed reference signal and producing an alerting signal when the first signal is less than the reference signal. Means are provided for squelching the low battery voltage alerting signal for the first several nights after the onset of the low battery voltage condition by incorporating photosensitive means in the generating circuit for either the first signal or the reference signal for shifting the level of that signal away from the other signal under dark conditions.
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Citations
13 Claims
- 1. In a battery voltage alarm circuit including means for comparing a first signal which is a function of the battery voltage to a relatively fixed reference signal and indicating means for providing an alarm output when the first signal is less than the reference signal to indicate low battery voltage, the improvement comprising condition-responsive control means for automatically shifting the level of one of the first and reference signals for varying the difference therebetween thereby to vary the time at which the alarm output can occur.
- 6. A battery voltage alarm circuit for indicating when the output voltage of a battery falls below a predetermined level, said alarm circuit comprising first signal generating means connected to the battery for producing a first signal which is a function of the output voltage of the battery, second signal generating means connected to the battery for producing a relatively constant-voltage reference signal, and indicating means connected to said first and second signal generating means for comparing said first signal with said reference signal and producing an alarm output signal when said first signal is less than said reference signal, said second signal generating means including condition-responsive variable impedance means for automatically shifting the constant-voltage level of said reference signal thereby to vary the difference between said first and reference signals for varying the time at which the alarm output signal can occur.
- 10. A battery voltage alarm circuit for indicating when the output voltage of a battery falls below a predetermined level, said alarm circuit comprising first signal generating means connected to the battery for producing a first signal which is a function of the output voltage of the battery, second signal generating means connected to the battery for producing a relatively constant-voltage reference signal, and indicating means connected to said first and second signal generating means for comparing said first signal with said reference signal and producing an alarm output signal when said first signal is less than said reference signal, said first signal generating means including condition-responsive variable impedance means for automatically shifting the level of said first signal thereby to vary the difference between said first and reference signals for varying the time at which the alarm output signal can occur.
Specification