Battery voltage detection and warning means
First Claim
1. For use in a battery-operated device such as a smoke detector, means for detecting when the battery voltage drops below a predetermined level and for providing warning in response thereto, said detection and warning means comprising:
- terminal means for connection to the terminals of a battery,a capacitor,capacitor charging circuit means connected to said terminal means and said capacitor for gradually charging said capacitor when the voltage of a battery connected to said terminal means drops below a predetermined level, said capacitor charging circuit means including resistive means coupled to said capacitor, a normally conductive switching element in parallel with said capacitor, and voltage sensing means connected across said terminal means, said voltage sensing means coupled to said normally conductive switching element to maintain said normally conductive element conductive when the voltage of a battery connected to said terminal means is above the predetermined level and to render said normally conductive element non-conductive when the voltage of a battery connected to said terminal means drops below the predetermined level, whereby said capacitor charges only when the voltage of a battery connected to said terminal means drops below the predetermined level for a period of time,capacitor discharging circuit means connected to said capacitor and responsive to the voltage of said capacitor for rapidly discharging said capacitor when the charge on said capacitor exceeds a predetermined level,and alarm means coupled to said capacitor discharging circuit means for producing a warning signal in response to at least the initial discharge of said capacitor.
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Accused Products
Abstract
A battery operated smoke detector or the like is provided with means for monitoring the voltage of the battery and providing a warning when the voltage drops below a predetermined level. The detection and warning system includes means for sensing when the battery voltage has dropped below the predetermined level and producing periodic output signals in response thereto. A first alarm means produces a permanent warning signal in response to the first output signal, and a second alarm means produces periodic warning signals in response to the periodic output signals.
24 Citations
5 Claims
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1. For use in a battery-operated device such as a smoke detector, means for detecting when the battery voltage drops below a predetermined level and for providing warning in response thereto, said detection and warning means comprising:
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terminal means for connection to the terminals of a battery, a capacitor, capacitor charging circuit means connected to said terminal means and said capacitor for gradually charging said capacitor when the voltage of a battery connected to said terminal means drops below a predetermined level, said capacitor charging circuit means including resistive means coupled to said capacitor, a normally conductive switching element in parallel with said capacitor, and voltage sensing means connected across said terminal means, said voltage sensing means coupled to said normally conductive switching element to maintain said normally conductive element conductive when the voltage of a battery connected to said terminal means is above the predetermined level and to render said normally conductive element non-conductive when the voltage of a battery connected to said terminal means drops below the predetermined level, whereby said capacitor charges only when the voltage of a battery connected to said terminal means drops below the predetermined level for a period of time, capacitor discharging circuit means connected to said capacitor and responsive to the voltage of said capacitor for rapidly discharging said capacitor when the charge on said capacitor exceeds a predetermined level, and alarm means coupled to said capacitor discharging circuit means for producing a warning signal in response to at least the initial discharge of said capacitor. - View Dependent Claims (2, 3, 4, 5)
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Specification