US3626403A — Protective systems and apparatus therefor

Claim 1

Independent Claim 157 words

A protective system comprising a single electrical loop including a bistate control device associated with an alarm circuit, said bistate control device operatively changes from one state to another whenever an abnormal situation against which protection is required occurs, the loop being connected to a voltage source and also including a plurality of detection contacts actuated whenever such abnormal situation occurs; a respective unidirectional current-conducting device connected across at least selected ones of said contacts such that the system is capable of operating in accordance with one currentconducting mode despite actuation of any of said at least selected ones of said contacts and switching means to inhibit current flow through the unidirectional current-conducting devices to permit the bistate control device to change to the other of said operative states whenever any one of said contacts is actuated such that the system operates in accordance with a second current-conducting mode and thereby provides continuous monitoring of the loop.

Claim 2

Dependent Claim 157 words

A protective system comprising a single electrical loop including a bistate control device associated with an alarm circuit, said bistate control device operatively changes from one state to another whenever an abnormal situation against which protection is required occurs, the loop being connected to a voltage source and also including a plurality of detection contacts actuated whenever such abnormal situation occurs; a respective unidirectional current-conducting device connected across at least selected ones of said contacts such that the system is capable of operating in accordance with one currentconducting mode despite actuation of any of said at least selected ones of said contacts and switching means to inhibit current flow through the unidirectional current-conducting devices to permit the bistate control device to change to the other of said operative states whenever any one of said contacts is actuated such that the system operates in accordance with a second current-conducting mode and thereby provides continuous monitoring of the loop.

Claim 3

Dependent Claim 92 words

A protective system comprising a single closed electrical loop including the winding of a relay having contacts associated with an alarm circuit, the loop also including a plurality of series-connected contacts arranged to be actuated when an abnormal situation occurs, a respective unidirectional current-conducting device connected across at least selected ones of said contacts such that the system is capable of operating in accordance with one current-conducting mode and switching means to inhibit current flow through said unidirectional current-conducting devices such that the system operates in accordance with a second current-conducting mode.

Claim 4

Dependent Claim 92 words

A protective system comprising a single closed electrical loop including the winding of a relay having contacts associated with an alarm circuit, the loop also including a plurality of series-connected contacts arranged to be actuated when an abnormal situation occurs, a respective unidirectional current-conducting device connected across at least selected ones of said contacts such that the system is capable of operating in accordance with one current-conducting mode and switching means to inhibit current flow through said unidirectional current-conducting devices such that the system operates in accordance with a second current-conducting mode.

Claim 5

Dependent Claim 138 words

A protective system as claimed in claim 2 wherein said series-connected contacts are each normally closed and arranged to be opened whenever the presence of an intruder is detected, such as to change the state of said relay, said unidirectional current conducting devices each comprising a semiconductor diode connected across a respective series-connected contact, such that for said one current-conducting mode, whenever a series-connnected contact is opened, current continues to flow around the loop to maintAin the normal state of said relay, and said switching means being arranged to reverse the direction of current flow through the loop such that thereafter during said second current-conducting mode, whenever a series-connected contact is opened, the current flow through the loop is interrupted to change the state of said relay and provide an alarm indication of the presence of an intruder.

Claim 6

Dependent Claim 31 words

A protective system as claimed in claim 2 wherein in addition to said series-connected contacts, at least one parallel-connected contact is provided with a unidirectional current-conducting device connected in series therewith.

Claim 7

Dependent Claim 136 words

A protective system as claimed in claim 4 wherein the parallel-connected contacts are normally open and arranged to be closed whenever the presence of an intruder is detected said at least one unidirectional current-conducting device comprising a semiconductor diode connected in series with the associated parallel-connected contact such that whenever the contact closes during said one current-conducting mode, the reverse connection of said diode substantially inhibits the passage of current therethrough and no short circuiting of the relay winding occurs, said switching means being arranged to reverse the direction of current flow through the loop such that thereafter, during said second current-conducting mode, whenever a parallel-connected contact is closed, the diode passes current to decrease the flow of current through the winding of the relay and provide an alarm indication of the presence of an intruder.

Claim 8

Dependent Claim 70 words

A protective system as claimed in claim 2 wherein an additional relay is included in the loop together with a plurality of additional parallel-connected contacts connected in series with impedance means such that when an additional parallel-connected contact is actuated, the current flow through said additional relay is increased to an extent sufficient to change the state thereof but without effecting a change in the state of said first-mentioned relay.

Claim 9

Dependent Claim 58 words

A protective system as claimed in claim 6 wherein said additional parallel-connected contacts are normally-open and arranged to be closed whenever heat, fire or smoke is detected and said additional relay having associated contacts connected in circuit with a fire warning circuit such as to provide an alarm indication of the presence of said fire, heat, or smoke.

Claim 10

Dependent Claim 141 words

A single closed electrical loop for the protective system of claim 2 including a single relay winding connected in series with a DC voltage source and a plurality of series-connected contacts each arranged to provide intruder protection at a respective location and to be actuated by an intruder and selected ones of said series-connected contacts each having a unidirectional current-conducting device connected in parallel therewith, said unidirectional current-conducting devices being connected such that when the current flows through the loop in one direction opening of one of said selected ones of said series-connected contacts fails to interrupt the current flow through the winding of the relay and switching means for changing the direction of current flow through the loop whereby the unidirectional current-conducting devices thereafter inhibit current flow through the winding of the relay whenever an associated series-connected contact is opened.

Claim 11

Dependent Claim 108 words

A single closed electrical loop as claimed in claim 8 including normally-open parallel-connected contacts each arranged to provide intruder protection at a respective specific location and to be closed by an intruder and at least one of said parallel-connected contacts having a unidirectional current-conducting device connected in series therewith and connected such that when the current flows through the loop in one direction closing of an associated contact fails to interrupt the current flow through the winding of the relay, and when said switching means changes the direction of current flow through the loop closing of a contact thereafter interrupts current flow tHrough the winding of the relay.

Claim 12

Dependent Claim 138 words

A protective system as claimed in claim 1 wherein the loop includes switching means for connecting the loop alternately to a DC and an AC voltage source, the loop also including a plurality of series-connected contacts, selected ones of which having capacitor means connected in parallel therewith, and a relay having contacts associated with an alarm circuit, the arrangement being such that when the loop is connected to the AC source, the current through the loop is maintained at a sufficient level to retain the winding of said relay energized despite the actuation of any series-connected contact shunted by said capacitor means, and when the loop is connected to said DC voltage source, the current through the loop is interrupted in response to the actuation of any series-connected contact, such as to change the state of said relay.

Claim 13

Dependent Claim 83 words

A protective system as claimed in claim 1 wherein the loop includes a plurality of series-connected contacts shunted by impedance means and a relay having contacts associated with an alarm circuit, the voltage level of the voltage source being sufficient to maintain the state of the relay despite actuation of any series-connected contact shunted by impedance means and means for reducing the voltage such that the voltage across the relay is insufficient to maintain the stare thereof whenever a series-connected contact is actuated.

Claim 14

Dependent Claim 77 words

A protective system as claimed in claim 1 wherein the loop includes a plurality of series-connected contacts and a relay having associated contacts connected in an alarm circuit, and a capacitor connected across said relay winding, such that whenever a series-connected contact is actuated, the capacitor maintains the state of the relay, and switching means for removing the capacitor from the loop such that actuation of a series-connected contact effects a change of state of the relay.

Claim 15

Dependent Claim 23 words

A protective system as claimed in claim 2 wherein each unidirectional current-conducting device is incorporated within a switch unit containing the respective contacts.

Claim 16

Dependent Claim 17 words

A protective system as claimed in claim 13 wherein the contacts are of the magnetic reed type.

Claim 17

Dependent Claim 43 words

A protective system as claimed in claim 2 wherein each unidirectional current-conducting device is incorporated within a switch unit containing the respective contacts; the said unidirectional device and an impedance means being connected in series with or across the contacts of the switch.

Claim 18

Dependent Claim 79 words

A protective system as claimed in claim 1 wherein a two wire loop is terminated by impedance means first relay means arranged to be actuated whenever a whole or partial short circuit or open circuit condition occurs in the loop, second relay means operable to provide second channel operation and interlocking means associated with the two relay means to prevent operation of the second relay means should such a whole or partial short circuit or open circuit condition occur.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-12-06	1975-06-07	1975-12-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-12-06	1979-06-07	1979-12-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-12-06	1983-06-07	1983-12-07	$7700.00	Window Closed / Lapsed

Protective systems and apparatus therefor

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