Dual channel pyroelectric intrusion detector

Claim 2

An intrusion detection system comprising a member of pyroelectric material, a plurality of infrared radiation sensitive elements, each said element comprising first and second spaced electrodes between which a portion of said member of pyroelectric material is positioned, each said element being operative to produce a voltage proportional to the rate of change of infrared radiation incident thereon, said elements being closely spaced to one another (the spacing being less than the width of the elements) so that the regions under surveillance are essentially fully covered, the pyroelectric material portion of each element being polariazed, first and second amplifier channels, means connecting one group of said polarized elements to said first amplifier channel, means connecting another similar group of said polarized elements to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 3

The system of claim 1 wherein the spacing between the edges of said spaced electrodes is less than ten percent of the width of said spaced electrodes.

Claim 4

The system of claim 1 wherein the edges of said spaced electrodes are parallel to one another and spaced apart less than 0.1 millimeter.

Claim 5

The system of claim 1 wherein said member of pyroelectric material is polarized uniformly in one direction.

Claim 6

An intrusion detection system comprising a plurality of infrared radiation sensitive elements, each said element comprising first and second spaced electrodes between which pyroelectric material is positioned, each said element being operative to produce a voltage proportional to the rate of change of infrared radiation incident thereon, said elements being closely spaced to one another (the spacing being less than the width of the elements) so that the regions under surveillance are essentially fully covered, the pyroelectric material of each element being polarized, said elements being polarized in pairs, first and second amplifier channels, means connecting one group of alternate ones of said polarized elements in parallel to said first amplifier channel, means connecting another similar group of alternate ones of said polarized elements in parallel to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 7

An intrusion detection system comprising a plurality of infrared radiation sensitive elements, each said element comprising first and second spaced electrodes between which pyroelectric material is positioned, each said element being operative to produce a voltage proportional to the rate of change of infrared radiation incident thereon, said elements being closely spaced to one another (the spacing being less than the width of the elements) so that the regions under surveillance are essentially fully covered, the pyroelectric material of each element being polarized, said elements being polarized in pairs, first and second amplifier channels, means connecting one group of alternate ones of said polarized elements in parallel to said first amplifier channel, means connecting another similar group of alternate ones of said polarized elements in parallel to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 8

The system of claim 1 wherein said pyroelectric material is selected from the class of lithium tantalate, lead zirconate titanate, lead germanate, strontium barium niobate, and polyvinylidene fluoride.

Claim 9

The system of claim 1 wherein said pyroelectric material is a film of polyvinylidene fluoride.

Claim 10

The system of claim 1 wherein each said amplifier channel includes a field effect transistor, an absolute value detector circuit and a pulse stretcher circuit.

Claim 11

The system of claim 1 wherein said coincidence circuit means includes logical AND circuitry.

Claim 12

The system of claim 9 wherein the spacing between the edges of said spaced electrodes is less than ten percent of the width of said spaced electrodes, the edges of said spaced electrodes are parallel to one another and spaced apart less than 0.1 millimeter.

Claim 13

The system of claim 10 and further including focusing means for focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements.

Claim 14

The system of claim 11 wherein each said amplifier channel includes a field effect transistor, an absolute value detector circuit and a pulse stretcher circuit, and said coincidence circuit means includes logical AND circuitry.

Claim 15

The system of claim 12 wherein said pyroelectric material is selected from the class of lithium tantalate, lead zirconate titanate, lead germanate, strontium barium niobate, and polyvinylidene fluoride.

Claim 16

An intrusion detection system comprising a member of pyroelectric material, a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which a polarized portion of said member of pyroelectric material is positioned, each said element being operative to product a voltage proportional to the rate of change of infrared radiation incident thereon, focusing means for focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means connected one group of said polarized elements to said first amplifier channel, means connecting another similar group of said polarized elements to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 17

An intrusion detection system comprising a member of pyroelectric material, a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which a polarized portion of said member of pyroelectric material is positioned, each said element being operative to product a voltage proportional to the rate of change of infrared radiation incident thereon, focusing means for focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means connected one group of said polarized elements to said first amplifier channel, means connecting another similar group of said polarized elements to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 18

The system of claim 14 wherein said member of pyroelectric material is polarized uniformly in one direction, one-half of said elements are connected to said first amplifier channel and the other half of said elements are connected to said second amplifier channel.

Claim 19

An intrusion detection system comprising a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which polarized pyroelectric material is positioned so that adjacent pairs of said elements are oppositely polarized, each said element being operative to product a voltage proportional to the rate of change of infrared radiation incident thereon, focusing means of focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means connecting one group of alternate ones of said polarized elements in parallel to said first amplifier channel, means connecting another similar group of alternate ones of said polarized elements in parallel to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 20

An intrusion detection system comprising a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which polarized pyroelectric material is positioned so that adjacent pairs of said elements are oppositely polarized, each said element being operative to product a voltage proportional to the rate of change of infrared radiation incident thereon, focusing means of focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means connecting one group of alternate ones of said polarized elements in parallel to said first amplifier channel, means connecting another similar group of alternate ones of said polarized elements in parallel to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 21

An intrusion detection system comprising a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which polarized pyroelectric material is positioned, each said element being operative to produce a voltage proportional to the rate of change of infared radiation incident thereon, focusing means for focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means of connecting one group of alternate ones of said polarized elements to said first amplifier channel, means connecting the others of said polarized elements to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 22

An intrusion detection system comprising a plurality of infrared radiation sensitive elements of similar width, each said element comprising first and second spaced electrodes between which polarized pyroelectric material is positioned, each said element being operative to produce a voltage proportional to the rate of change of infared radiation incident thereon, focusing means for focusing infrared radiation from multiple fields of view on corresponding ones of said infrared radiation sensitive elements, the spacing between the edges of said spaced electrodes being less than ten percent of the average width of said electrodes, the edges of said spaced electrodes being parallel to one another and spaced apart less than 0.1 millimeter so that the fields of view under surveillance are essentially fully covered, first and second amplifier channels, means of connecting one group of alternate ones of said polarized elements to said first amplifier channel, means connecting the others of said polarized elements to said second amplifier channel, and coincidence means for producing an alarm output in response to concurrent intruder signal generation by both of said channels.

Claim 23

The system of claim 17 wherein each said amplifier channel includes a field effect transistor, an absolute value detector circuit and a pulse stretcher circuit, and said coincidence circuit means includes logical AND circuitry.

Claim 24

The system of claim 18 wherein said pyroelectric material is selected from the class of lithium tantalate, lead zirconate titanate, lead germanate, strontium barium niobate, and polyvinylidene fluoride.

Claim 25

The system of claim 19 wherein said pyroelectric material has parallel opposed surfaces, and said electrode areas cover substantially all of at least one of said surfaces.