Apparatus and method for a smoke alarm device with integrated testing circuits

Claim 2

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result i a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said sensing component includes a heating element, said heating element and said switch means coupled in series and having said first regulated voltage applied thereto, said switch means having a bias resistive component and a switch, said bias resistive component coupled in parallel with said switch, activation of said switch causing a short circuit across said bias resistive component.

Claim 3

The smoke detector unit of claim 1 wherein said bias resistive component is a resistor.

Claim 4

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said switch means in parallel across said resistor means, said switch means including a switch and a bias resistor coupled in series, wherein activation of said switch causes said bias resistor to be electrically isolated from said smoke detector unit.

Claim 5

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said switch means in parallel across said resistor means, said switch means including a switch and a bias resistor coupled in series, wherein activation of said switch causes said bias resistor to be electrically isolated from said smoke detector unit.

Claim 6

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled i series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said switch means includes a bias resistor coupled in series with said sensing component and said resistor means, said switch means including a switch coupled in parallel with aid bias resistor, wherein activation of said switch means provides a short circuit across said resistor.

Claim 7

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled i series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said switch means includes a bias resistor coupled in series with said sensing component and said resistor means, said switch means including a switch coupled in parallel with aid bias resistor, wherein activation of said switch means provides a short circuit across said resistor.

Claim 8

A smoke detector unit including testing apparatus, said smoke detector unit comprising; a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said second voltage regulator includes a voltage dividing network, said reference voltage being determined by said voltage dividing circuit, said switch means including a switch and a first resistor, said said switch and said first resistor being coupled in parallel across a resistor of said voltage dividing network, wherein activation of said switch causes said reference voltage applied to said first comparator terminal to decrease.

Claim 9

A smoke detector unit including testing apparatus, said smoke detector unit comprising; a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said second voltage regulator includes a voltage dividing network, said reference voltage being determined by said voltage dividing circuit, said switch means including a switch and a first resistor, said said switch and said first resistor being coupled in parallel across a resistor of said voltage dividing network, wherein activation of said switch causes said reference voltage applied to said first comparator terminal to decrease.

Claim 10

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch mans is activated; wherein said sensing component includes a heating element, said heating element coupled in parallel with said sensing component and said resistor means, said switch means coupled between said second voltage regulator and said sensing component, said switch means including a switch coupled in parallel with a bias resistor, activation of said switch means causing a short circuit across said bias resistor.

Claim 11

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch mans is activated; wherein said sensing component includes a heating element, said heating element coupled in parallel with said sensing component and said resistor means, said switch means coupled between said second voltage regulator and said sensing component, said switch means including a switch coupled in parallel with a bias resistor, activation of said switch means causing a short circuit across said bias resistor.

Claim 12

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said second voltage regulator includes a resistor dividing network for determining said reference voltage, wherein said switch means includes a switch coupled to a resistor in said resistor dividing network, activating said switch means causing a resistance a said resistor dividing network to be changed thereby altering said reference voltage.

Claim 13

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said second voltage regulator includes a resistor dividing network for determining said reference voltage, wherein said switch means includes a switch coupled to a resistor in said resistor dividing network, activating said switch means causing a resistance a said resistor dividing network to be changed thereby altering said reference voltage.

Claim 14

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; a second comparator unit, said second comparator unit having a second terminal coupled to said resistor terminal; and resistor dividing means coupled to said first voltage regulator circuit for providing a second reference voltage to a first input terminal of said second comparator means, wherein said voltage applied to said second comparator second terminal is less than said second reference voltage, said second comparator providing a second alarm signal upon failure of said sensing component.

Claim 15

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means coupled in series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; a second comparator unit, said second comparator unit having a second terminal coupled to said resistor terminal; and resistor dividing means coupled to said first voltage regulator circuit for providing a second reference voltage to a first input terminal of said second comparator means, wherein said voltage applied to said second comparator second terminal is less than said second reference voltage, said second comparator providing a second alarm signal upon failure of said sensing component.

Claim 16

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means couple din series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said resistor means is a rheostat, said resistor terminal being a variable terminal of said rheostat.

Claim 17

A smoke detector unit including testing apparatus, said smoke detector unit comprising: a first voltage regulator providing a first regulated voltage; a sensing component responsive to products of combustion, a sensing component resistance decreasing when products of combustion are detected by said sensing component; resistor means couple din series with said sensing component, said said resistor means having a resistor terminal, said resistor means and said sensing component coupled to said first voltage regulator; a second voltage regulator providing a reference voltage; comparator means for providing an alarm signal at an output terminal of said comparator means when a voltage applied to a second terminal of said comparator means is greater than a detector voltage applied to a first terminal of said comparator means, said reference voltage being applied to said first terminal, said second terminal of said comparator means being coupled to said resistor terminal, wherein said detector voltage applied to said second terminal is less than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance less than a predetermined value and wherein said detector voltage applied to said second terminal is greater than said reference voltage when products of combustion detected by said sensing component result in a sensing component resistance greater than said predetermined value; and switch means for causing said voltage applied to said second terminal to be greater than said reference voltage when said switch means is activated; wherein said resistor means is a rheostat, said resistor terminal being a variable terminal of said rheostat.

Claim 18

A smoke detector unit and associated test circuits, said smoke detector unit comprising: a sensing means for detecting products of combustion, wherein detection of said products of combustion causes a detection voltage applied to a sensing means voltage terminal to change; reference means for providing a reference voltage; comparison means responsive to said reference voltage and to said detection voltage for providing an alarm signal when said detection voltage is greater than said reference voltage; a voltage supply for applying a sensing means voltage to said sensing means, wherein said voltage supply has plurality of supply terminals, each supply terminal having a different voltage applied thereto; and switch means coupled to said plurality of supply terminals for controlling a magnitude of sensing means voltage, wherein activation of a preselected position of said witch means results in a detection voltage that is greater than said reference voltage.

Claim 19

A smoke detector unit and associated test circuits, said smoke detector unit comprising: a sensing means for detecting products of combustion, wherein detection of said products of combustion causes a detection voltage applied to a sensing means voltage terminal to change; reference means for providing a reference voltage; comparison means responsive to said reference voltage and to said detection voltage for providing an alarm signal when said detection voltage is greater than said reference voltage; a voltage supply for applying a sensing means voltage to said sensing means, wherein said voltage supply has plurality of supply terminals, each supply terminal having a different voltage applied thereto; and switch means coupled to said plurality of supply terminals for controlling a magnitude of sensing means voltage, wherein activation of a preselected position of said witch means results in a detection voltage that is greater than said reference voltage.

Claim 20

The smoke detector unit of claim 10 wherein said voltages of said supply voltages are alternating voltages.

Claim 21

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a resistor and a sensing element, said resistor and said sensing element being coupled in series, said reference voltage being determined by a second voltage regulator and a voltage dividing network, wherein said switch means includes a switch and a resistor coupled in series, said switch means being couple din parallel with a resistor of said voltage dividing network.

Claim 22

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a resistor and a sensing element, said resistor and said sensing element being coupled in series, said reference voltage being determined by a second voltage regulator and a voltage dividing network, wherein said switch means includes a switch and a resistor coupled in series, said switch means being couple din parallel with a resistor of said voltage dividing network.

Claim 23

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, wherein said switch means is coupled in parallel with said resistor, said switch means including a switch and a bias resistor coupled in series.

Claim 24

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, wherein said switch means is coupled in parallel with said resistor, said switch means including a switch and a bias resistor coupled in series.

Claim 25

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor, said switch means being coupled in series with said sensing element, said witch means including a switch and a bias resistor coupled in parallel.

Claim 26

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor, said switch means being coupled in series with said sensing element, said witch means including a switch and a bias resistor coupled in parallel.

Claim 27

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison mans for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, said sensing element including a heating element, wherein said switch means and said heating element are couple din series and coupled to said first voltage regulator, said switch means including a switch and a bias resistor coupled in parallel.

Claim 28

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison mans for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, said sensing element including a heating element, wherein said switch means and said heating element are couple din series and coupled to said first voltage regulator, said switch means including a switch and a bias resistor coupled in parallel.

Claim 29

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, said sensing element including a heating element, said switch means being coupled to said first voltage regulator, said switch means being coupled in in series with said heating element and being coupled in series with said heating element, said switch means including a switch and a bias resistor coupled in parallel.

Claim 30

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said sensing means includes a sensing element and a resistor coupled in series, said sensing element including a heating element, said switch means being coupled to said first voltage regulator, said switch means being coupled in in series with said heating element and being coupled in series with said heating element, said switch means including a switch and a bias resistor coupled in parallel.

Claim 31

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said first voltage regulator includes a resistor dividing network for determining said regulated voltage, said switch means being coupled to at least one resistor of said voltage dividing network, said switch means including a bias resistor and a switch, activation of said switch means changing said regulated voltage.

Claim 32

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising: sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; and switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; wherein said first voltage regulator includes a resistor dividing network for determining said regulated voltage, said switch means being coupled to at least one resistor of said voltage dividing network, said switch means including a bias resistor and a switch, activation of said switch means changing said regulated voltage.

Claim 33

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising; sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; and wherein a second reference voltage is provided by said reference means; second comparator means, said second comparator means having said second reference voltage connected to a first terminal of said second comparison means, said second comparison means having a second terminal coupled to said voltage terminal, wherein a malfunction of said sensing means results in a decrease in said voltage terminal voltage, a second alarm signal being generated at an output terminal of said second comparator means in response to said voltage terminal voltage decrease.

Claim 34

A smoke detector unit for detecting a presence of products of combustion, said smoke detector unit comprising; sensing means for providing a resistance that is a function of detected products of combustion, wherein said sensing means includes a voltage terminal for determining a voltage at a preselected point in said sensing means; a first voltage regulator for applying a regulated voltage to said sensing means; reference means for providing a reference voltage; comparison means for determining when said resistance changes by a preselected amount, said comparison means comparing a first voltage determined by said voltage terminal with said reference voltage, said comparison means providing an alarm signal when said first voltage is greater than said reference voltage; switch means for changing a one of said first voltage and said reference voltage in response to activation of said switch means; and wherein a second reference voltage is provided by said reference means; second comparator means, said second comparator means having said second reference voltage connected to a first terminal of said second comparison means, said second comparison means having a second terminal coupled to said voltage terminal, wherein a malfunction of said sensing means results in a decrease in said voltage terminal voltage, a second alarm signal being generated at an output terminal of said second comparator means in response to said voltage terminal voltage decrease.