US4972181A — A. C. powered smoke detector with back-up battery…

Claim 1

Independent Claim 222 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: (a) means for checking the power capacity of the back-up battery by loading the battery including: (i) a test load switch, (ii) means for applying a preselected test load to the battery when the test load switch is actuated, and (iii) means for comparing the voltage of the battery to a preselected minimum voltage corresponding to a preselected minimum power capacity when the test load switch is actuated and the battery is test loaded; (b) means for actuating the test load switch; (c) means for switchably disconnecting the D.C. power supply during battery test; and (d) means responsive to said power checking means for providing a low battery power indication in response to the battery power capacity being less than said preselected power capacity.

Claim 2

Dependent Claim 222 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: (a) means for checking the power capacity of the back-up battery by loading the battery including: (i) a test load switch, (ii) means for applying a preselected test load to the battery when the test load switch is actuated, and (iii) means for comparing the voltage of the battery to a preselected minimum voltage corresponding to a preselected minimum power capacity when the test load switch is actuated and the battery is test loaded; (b) means for actuating the test load switch; (c) means for switchably disconnecting the D.C. power supply during battery test; and (d) means responsive to said power checking means for providing a low battery power indication in response to the battery power capacity being less than said preselected power capacity.

Claim 3

Dependent Claim 49 words

The smoke detector of claim 1 in which said test load switch is an electronic switch, and the test load switch actuating means includes means for automatically and periodically actuating said test load switch for a preselected, relatively short duration during each of a plurality of successive test cycles.

Claim 4

Dependent Claim 20 words

The smoke detector of claim 2 in which the time between periods of actuation is in the order forty seconds.

Claim 5

Dependent Claim 22 words

The smoke detector of claim 1 or 2 in which said preselected duration of actuation is on the order of 10 milliseconds.

Claim 6

Dependent Claim 26 words

The smoke detector of claim 1 or 2 in which said means for electrically disconnecting the output of the D.C. power supply comprises an electronic switch.

Claim 7

Dependent Claim 45 words

The smoke detector of claim 5 in which said disconnecting means includes: a power supply control switch interconnected between the D.C. power supply and the comparing means, and means for opening said power supply control switch in response to actuation of the test load switch.

Claim 8

Dependent Claim 30 words

The smoke detector of claim 1 including a diode connected between said battery and the voltage comparator for isolating the back-up battery from the output of the D.C. power supply.

Claim 9

Dependent Claim 31 words

The smoke detector of claim 7 in which actuation of the test load switch causes current to be drawn from the battery at a level on the order of ten milliamperes.

Claim 10

Dependent Claim 41 words

The smoke detector of claim 1 in which said low battery indicating means include means for actuating said alarm in a mode different from the mode in which it is actuated by said smoke detector in response to detection of smoke.

Claim 11

Dependent Claim 52 words

The smoke detector of claim 1 in which said smoke detection circuit, said voltage comparing means and said low battery indication means are combined in a single integrated circuit package together with an oscillator, and said switch actuating means includes means responsive to said oscillator for periodically actuating said test load switch.

Claim 12

Dependent Claim 139 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: means for periodically electrically switchably disconnecting the D.C. power supply for a preselected time period; and means enabled during said period of disablement of the D.C. power supply for checking the power capacity of the back-up battery by loading the battery.

Claim 13

Dependent Claim 139 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: means for periodically electrically switchably disconnecting the D.C. power supply for a preselected time period; and means enabled during said period of disablement of the D.C. power supply for checking the power capacity of the back-up battery by loading the battery.

Claim 14

Dependent Claim 55 words

The detection circuit of claim 11 in which said disconnecting means includes a power supply control switch connecting between the output of the D.C. power supply and the detection circuit, and means for periodically actuating said power supply control switch to a relatively non-conductive state to electrically disconnect the power supply from the detection circuit.

Claim 15

Dependent Claim 51 words

The detection circuit of claim 13 in which said battery power capacity checking means includes another switch enabled in response to the control switch being in a relatively non-conductive state to load said battery, and means for comparing the voltage of the back-up battery, when loaded, to a preselected minimum voltage.

Claim 16

Dependent Claim 52 words

The detection circuit of claim 13 in which said another switch is a diode connected between the battery and the D.C. power supply output with a polarity to isolate the battery from the D.C. power supply when the voltage output level of the D.C. power supply is forced below the battery voltage.

Claim 17

Dependent Claim 160 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: means including a switch connected for disabling said D.C. power supply from providing D.C. output power; battery connecting means for momentarily electrically connecting the back-up battery through a test load when said D.C. power supply is disabled; and means for comparing the power capacity of said battery to a preselected minimum capacity when it is being electrically connected through said test load.

Claim 18

Dependent Claim 160 words

In a smoke detector with a smoke detection circuit, an alarm actuatable by the detection circuit and a D.C. power supply with an A.C. input terminal for receiving A.C. power and a D.C. output terminal on which it normally supplies output D.C. power to the detection circuit and alarm whenever it, in turn, is receiving A.C. input power and a back-up battery to provide D.C. power to the detection circuit and the alarm in the event of loss of output D.C. power from the D.C. power supply, the improvement being a supervision circuit for the back-up battery, comprising: means including a switch connected for disabling said D.C. power supply from providing D.C. output power; battery connecting means for momentarily electrically connecting the back-up battery through a test load when said D.C. power supply is disabled; and means for comparing the power capacity of said battery to a preselected minimum capacity when it is being electrically connected through said test load.

Claim 19

Dependent Claim 26 words

The smoke detector circuit of claim 15 in which said battery connecting means includes a test load switch for connecting the battery with the test load.

Claim 20

Dependent Claim 21 words

The smoke detector of claim 16 including means responsive to actuation of the test load switch to actuate the disabling means.

Claim 21

Dependent Claim 36 words

The smoke detector of claim 17 in which said battery connecting means includes the switch of said disabling means and means for connecting the D.C. output of the power supply through said test load when actuated.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-11-19	1994-05-21	1994-11-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-11-19	1998-05-21	1998-11-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-11-19	2002-05-21	2002-11-20	$7700.00	Window Closed / Lapsed

A. C. powered smoke detector with back-up battery supervision circuit

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