US4983853A — Method and apparatus for detecting flame

Claim 1

Independent Claim 117 words

A method of detecting flame within a region, comprising the steps of: (a) measuring radiation emitted from said region within a selected portion of a visible frequency band; (b) concurrently measuring radiation emitted from said region within a selected portion of an infra-red frequency band; (c) deriving the coherency between said measurements; (d) comparing said coherency with a prestored coherency signature representative of the coherency between measurements of radiation emitted from said region within said selected portions of said visible and infra-red frequency bands while known flame conditions prevail within said region, thereby estimating the deviation of said derived coherency from said prestored coherency signature; and, (e) comparing said deviation with a first predetermined threshold alarm value.

Claim 2

Independent Claim 117 words

A method of detecting flame within a region, comprising the steps of: (a) measuring radiation emitted from said region within a selected portion of a visible frequency band; (b) concurrently measuring radiation emitted from said region within a selected portion of an infra-red frequency band; (c) deriving the coherency between said measurements; (d) comparing said coherency with a prestored coherency signature representative of the coherency between measurements of radiation emitted from said region within said selected portions of said visible and infra-red frequency bands while known flame conditions prevail within said region, thereby estimating the deviation of said derived coherency from said prestored coherency signature; and, (e) comparing said deviation with a first predetermined threshold alarm value.

Claim 3

Dependent Claim 93 words

A method as defined in claim 1, further comprising: (a) deriving the auto spectrum of said visible frequency band measurements; (b) comparing said visible measurement auto spectrum with a prestored auto spectrum signature representative of the auto spectrum between measurements of radiation emitted from said region within said selected portion of said visible frequency band while known flame conditions prevail within said region, thereby estimating the deviation of said derived visible measurement auto spectrum from said prestored visible auto spectrum signature; and, (c) comparing said deviation with a second predetermined threshold alarm value.

Claim 4

Dependent Claim 93 words

A method as defined in claim 2, further comprising: (a) deriving the auto spectrum of said infra-red frequency band measurements; (b) comparing said infra-red measurement auto spectrum with a prestored auto spectrum signature representative of the auto spectrum between measurements of radiation emitted from said region within said selected portion of said infra-red frequency band while known flame conditions prevail within said region, thereby estimating the deviation of said derived infra-red measurement auto spectrum from said prestored infrared auto spectrum signature; and, (c) comparing said deviation with a third predetermined threshold alarm value.

Claim 5

Dependent Claim 92 words

A method as defined in claim 3, further comprising: (a) deriving the transfer function of said visible and infra-red frequency band measurements; (b) comparing said transfer function with a prestored transfer function signature representative of the transfer function between measurements of radiation emitted from said region within said selected portions of said visible and infra-red frequency bands while known flame conditions prevail within said region, thereby estimating the deviation of said derived transfer function from said prestored transfer function signature; and, (c) comparing said deviation with a fourth predetermined threshold alarm value.

Claim 6

Dependent Claim 22 words

A method as defined in claim 1, further comprising repeating said measurements for other portions of said visible and infra-red frequency bands.

Claim 7

Dependent Claim 22 words

A method as defined in claim 2, further comprising repeating said measurements for other portions of said visible and infra-red frequency bands.

Claim 8

Dependent Claim 22 words

A method as defined in claim 3, further comprising repeating said measurements for other portions of said visible and infra-red frequency bands.

Claim 9

Dependent Claim 22 words

A method as defined in claim 4, further comprising repeating said measurements for other portions of said visible and infra-red frequency bands.

Claim 10

Dependent Claim 28 words

A method as defined in claim 5, wherein said coherency comparing step comprises applying a weighted least squares fit to said derived coherency and said prestored coherency signature.

Claim 11

Dependent Claim 34 words

A method as defined in claim 6, wherein said visible auto spectrum comparing step comprises applying a weighted least squares fit to said derived visible auto spectrum and said prestored visible auto spectrum signature.

Claim 12

Dependent Claim 34 words

A method as defined in claim 7, wherein said infra-red auto spectrum comparing step comprises applying a weighted least squares fit to said derived infra-red auto spectrum and said prestored infra-red auto spectrum signature.

Claim 13

Dependent Claim 31 words

A method as defined in claim 8, wherein said transfer function comparing step comprises applying a weighted least squares fit to said derived transfer function and said prestored transfer function signature.

Claim 14

Dependent Claim 26 words

A method as defined in claim 5, wherein said coherency comparing step comprises applying a stochastic fit to said derived coherency and said prestored coherency signature.

Claim 15

Dependent Claim 32 words

A method as defined in claim 6, wherein said visible auto spectrum comparing step comprises applying a stochastic fit to said derived visible auto spectrum and said prestored visible auto spectrum signature.

Claim 16

Dependent Claim 32 words

A method as defined in claim 7, wherein said infra-red auto spectrum comparing step comprises applying a stochastic fit to said derived infra-red auto spectrum and said prestored infra-red auto spectrum signature.

Claim 17

Dependent Claim 29 words

A method as defined in claim 8, wherein said transfer function comparing step comprises applying a stochastic fit to said derived transfer function and said prestored transfer function signature.

Claim 18

Dependent Claim 27 words

A method as defined in claim 5, wherein said coherency comparing step comprises applying a bounded limits fit to said derived coherency and said prestored coherency signature.

Claim 19

Dependent Claim 33 words

A method as defined in claim 6, wherein said visible auto spectrum comparing step comprises applying a bounded limits fit to said derived visible auto spectrum and said prestored visible auto spectrum signature.

Claim 20

Dependent Claim 33 words

A method as defined in claim 7, wherein said infra-red auto spectrum comparing step comprises applying a bounded limits fit to said derived infra-red auto spectrum and said prestored infra-red auto spectrum signature.

Claim 21

Dependent Claim 26 words

A method as defined in claim 5, wherein said coherency comparing step comprises applying a Gaussian fit to said derived coherency and said prestored coherency signature.

Claim 22

Dependent Claim 32 words

A method as defined in claim 6, wherein said visible auto spectrum comparing step comprises applying a Gaussian fit to said derived visible auto spectrum and said prestored visible auto spectrum signature.

Claim 23

Dependent Claim 32 words

A method as defined in claim 7, wherein said infra-red auto spectrum comparing step comprises applying a Gaussian fit to said derived infra-red auto spectrum and said prestored infra-red auto spectrum signature.

Claim 24

Dependent Claim 29 words

A method as defined in claim 8, wherein said transfer function comparing step comprises applying a Gaussian fit to said derived transfer function and said prestored transfer function signature.

Claim 25

Dependent Claim 34 words

A method as defined in claim 5, further comprising: (a) weighting said coherency deviation estimates; (b) summing said weighted estimates; (c) averaging said summed, weighted estimates; and, (d) normalizing said averaged, summed, weighted estimates.

Claim 26

Dependent Claim 36 words

A method as defined in claim 6, further comprising: (a) weighting said visible auto spectrum deviation estimates; (b) summing said weighted estimates; (c) averaging said summed, weighted estimates; and, (d) normalizing said averaged, summed, weighted estimates.

Claim 27

Dependent Claim 36 words

A method as defined in claim 7, further comprising: (a) weighting said infra-red auto spectrum deviation estimates; (b) summing said weighted estimates; (c) averaging said summed, weighted estimates; and, (d) normalizing said averaged, summed, weighted estimates.

Claim 28

Dependent Claim 35 words

A method as defined in claim 8, further comprising: (a) weighting said transfer function deviation estimates; (b) summing said weighted estimates; (c) averaging said summed, weighted estimates; and, (d) normalizing said averaged, summed, weighted estimates.

Claim 29

Dependent Claim 23 words

A method as defined in claim 1, further comprising repeating said coherency comparing step with prestored coherency signatures representative of selected flame conditions.

Claim 30

Dependent Claim 25 words

A method as defined in claim 2, further comprising repeating said visible auto spectrum comparing step with prestored coherency signatures representative of selected flame conditions.

Claim 31

Dependent Claim 27 words

A method as defined in claim 3, further comprising repeating said infra-red auto spectrum comparing step with prestored infra-red auto spectrum signatures representative of selected flame conditions.

Claim 32

Dependent Claim 25 words

A method as defined in claim 4, further comprising repeating said transfer function comparing step with prestored transfer function signatures representative of selected flame conditions.

Claim 33

Independent Claim 225 words

A method of detecting flame within a region, comprising the steps of: (a) deriving "m" data signals x 1 (t), where i=1, 2, . . . m, each of said data signals characterizing radiation emitted from said region within a corresponding portion of the visible frequency band; (b) sampling each of said data signals "N" times in each of "k" block periods, where "k" is an integer, each block having duration "T" seconds, to derive a plurality of "c" signal samples characterized by x ik (c); (c) deriving the discrete auto-power spectrum density estimate S iik [L] for x i (t) as: S.sub.iik [L]=X.sub.ik [L] *·X.sub.ik [L] where: X ik [L]is the complex discrete Fourier transform of sampled signal x i (t) for the k th sample block; "L" =0, 1, . . . N/2-1 is the L th harmonic component at frequency (L/T) Hertz; and, "*" denotes the complex conjugate; (d) comparing said auto-power spectrum density estimate with a prestored auto-power spectrum density signature representative of the auto-power spectrum density between measurements of radiation emitted from said region within said corresponding portions of said visible frequency band while known flame conditions prevail within said region, thereby estimating the deviation of said derived auto-power spectrum density from said prestored auto-power spectrum density signature; and, (e) comparing said deviation with a first predetermined threshold alarm value.

Claim 34

Independent Claim 225 words

A method of detecting flame within a region, comprising the steps of: (a) deriving "m" data signals x 1 (t), where i=1, 2, . . . m, each of said data signals characterizing radiation emitted from said region within a corresponding portion of the visible frequency band; (b) sampling each of said data signals "N" times in each of "k" block periods, where "k" is an integer, each block having duration "T" seconds, to derive a plurality of "c" signal samples characterized by x ik (c); (c) deriving the discrete auto-power spectrum density estimate S iik [L] for x i (t) as: S.sub.iik [L]=X.sub.ik [L] *·X.sub.ik [L] where: X ik [L]is the complex discrete Fourier transform of sampled signal x i (t) for the k th sample block; "L" =0, 1, . . . N/2-1 is the L th harmonic component at frequency (L/T) Hertz; and, "*" denotes the complex conjugate; (d) comparing said auto-power spectrum density estimate with a prestored auto-power spectrum density signature representative of the auto-power spectrum density between measurements of radiation emitted from said region within said corresponding portions of said visible frequency band while known flame conditions prevail within said region, thereby estimating the deviation of said derived auto-power spectrum density from said prestored auto-power spectrum density signature; and, (e) comparing said deviation with a first predetermined threshold alarm value.

Claim 35

Dependent Claim 219 words

A method as defined in claim 32, further comprising: (a) while deriving said data signals x i (t), concurrently deriving "m" data signals xj(t), where j=1, 2, . . . m, each of said data signals xj(t) characterizing radiation emitted from said region within a corresponding portion of the infra-red frequency band; (b) sampling each of said data signals xj(t) "N" times in each of "k" block periods, where "k" is an integer, each block having duration "T" seconds, to derive a plurality of "c" signal samples characterized by x ak (c), where a=1, 2, ... m; (c) deriving the discrete auto-power spectrum density estimate S jjk [L] for x j (t) as: S.sub.jjk [L]=X.sub.jk [L] *·X.sub.jk [L] where: X jk [L]is the complex discrete Fourier transform of sampled signal x j (t) for the k th sample block; (e) comparing said auto-power spectrum density estimate S jjk [L] with a prestored auto-power spectrum density signature representative of the auto-power spectrum density between measurements of radiation emitted from said region within said corresponding portions of said infra-red frequency band while known flame conditions prevail within said region, thereby estimating the deviation of said derived auto-power spectrum density S jjk [L] from said prestored auto-power speotrum density signature; and, (e) comparing said deviation with a second predetermined threshold alarm value.

Claim 36

Dependent Claim 122 words

A method as defined in claim 33, further comprising: (a) deriving the discrete modulus squared transfer function estimate H jik [L] for x i (t) and x j (t) as: H.sub.jik [L]=(S.sub.jik [L])*·S.sub.jik [L])/(S.sub.jk [L]·S.sub.ik [L]) (b) comparing said discrete modulus squared transfer function estimate with a prestored discrete modulus squared transfer function signature representative of the discrete modulus squared transfer function between measurements of radiation emitted from said region within said corresponding portions of said visible and infra-red frequency bands while known flame conditions prevail within said region, thereby estimating the deviation of said derived discrete modulus squared transfer function from said prestored discrete modulus squared transfer function signature; and, (c) comparing said deviation with a third predetermined threshold alarm value.

Claim 37

Dependent Claim 122 words

A method as defined in claim 34, further comprising: (a) deriving the discrete modulus squared coherency function estimate C jik [L] for x i (t) and x j (t) as: C.sub.jik [L]=((S.sub.jik [L])*·S.sub.jik [L])/(S.sub.jk [L]·S.sub.ik [L]) (b) comparing said discrete modulus squared coherency function estimate with a prestored discrete modulus squared coherency function signature representative of the discrete modulus squared coherency function between measurements of radiation emitted from said region within said corresponding portions of said visible and infra-red frequency bands while known flame conditions prevail within said region, thereby estimating the deviation of said derived discrete modulus squared coherency function from said prestored discrete modulus squared coherency function signature; and, (c) comparing said deviation with a fourth predetermined threshold alarm value.

Claim 38

Dependent Claim 40 words

A method as defined in claim 35, further comprising repeating said data signal derivation steps within a plurality of portions of said visible and infra-red frequency bands and then repeating said comparison steps for each of said derived data signals.

Claim 39

Dependent Claim 130 words

A method as defined in claim 36, wherein said prestored signatures "z" comprise the average "Z ave ", minimum "Z min ", and maximum "Z max ", values of spectral estimates derived for said known flame conditions, said method further comprising deriving the probability "p(x)" that each of said derived estimates "x" is a measure of the corresponding prestored signature "z", as follows: (a) if Z min <Z ave : deriving e=(x-Z ave ) 2 ; deriving e max =(Z min -Z ave ) 2 ; deriving p(x)=1.0-e/e max ; or, (b) if Z ave <x<Z max : deriving e=(x-Z ave ) 2 ; deriving e max =(Z max -Z ave ) 2 ; deriving p(x)=1.0-e/e max ; or, (c) if (x<Z min ) or (x>Z max ): setting p(x)=0.0.

Claim 40

Dependent Claim 85 words

A method as defined in claim 36, wherein said prestored signatures "z" comprise the average "Z ave ", minimum "Z min ", and maximum "Z max ", values of spectral estimates derived for said known flame conditions, said method further comprising deriving the normalized probability "(p[j]/p max )" that each of said derived estimates "x" is a measure of the corresponding prestored signature "z", where: p[i]=prob{Z, Z.sub.min +i·δ<Z<Z.sub.min +(i+1)·δ}; j=int ((x-Z min )/δ) δ=(Z max -Z min )/n; Σp[i]=1.0; and, p max =max{p[i],i=0 .. n}.

Claim 41

Dependent Claim 151 words

A method as defined in claim 36, wherein said prestored signatures "Z" comprise the average "Z ave ", minimum "Z min ", and maximum "Z max ", values of spectral estimates derived for said known flame conditions, said method further comprising deriving the probability "p(x)" that each of said derived estimates "x" is a measure of the corresponding prestored signature "z", as follows: (a) if Z minn <X<Z ave : deriving e=|X-Z ave |; deriving e max =|Z min -Z ave |; deriving p(x)=1.0-ƒ(e/e max ); or, (b) if Z ave <X<Z max : deriving e=|x-Z ave |; deriving e max =Z max -Z ave |; deriving p(x) =1.0-ƒ(e/e max ); or, (c) if (x<Z min ) or (x≦Z max )l : setting p(x)=0.0; where the function ƒ(·) is defined for all values in the range 0, . . . , 1 and is normalized such that: ƒ(0)=0; ƒ(1)=1; and, 0≦ƒ(·)≦1.0.

Claim 42

Dependent Claim 18 words

A method as defined in claim 39, wherein said function ƒ(·) is a uniform weighting function [ƒ(x)=1.0 (0<x<1.0)].

Claim 43

Dependent Claim 18 words

A method as defined in claim 39, wherein said function ƒ(·) is a triangular weighting function [ƒ(x)=x; (0<x<1.0)].

Claim 44

Dependent Claim 19 words

A method as defined in claim 39, wherein said function ƒ(·) is a cubic weighting function [ƒ(x)=x 3 ].

Claim 45

Dependent Claim 61 words

A method as defined in claim 36, wherein said prestored signatures "z" comprise the average "Z ave ", standard deviation "Z dev " values of spectral estimates derived for said known flame conditions, said method further comprising deriving the probability "p(x)" that each of said derived estimates "x" is a measure of the corresponding prestored signature "z", as follows: p(x)=exp((x-Zave).sup.2 /Zdev.sup.2).

Claim 46

Dependent Claim 34 words

A method as defined in claim 37, further comprising weighting, summing and normalizing said probabilities to obtain an overall fit probability "p fit ", where: p fit =Σw[i]·p(x[i]), for all estimates x[i]; and, Σw[i]=1.0.

Claim 47

Dependent Claim 34 words

A method as defined in claim 38, further comprising weighting, summing and normalizing said probabilities to obtain an overall fit probability "p fit ", where: p fit =Σw[i]·p(x[i]), for all estimates x[i]; and, Σw[i]=1.0.

Claim 48

Dependent Claim 34 words

A method as defined in claim 39, further comprising weighting, summing and normalizing said probabilities to obtain an overall fit probability "p fit ", where: p fit =Σw[i]·p(x[i]), for all estimates x[i]; and, Σw[i]=1.0.

Claim 49

Dependent Claim 34 words

A method as defined in claim 43, further comprising weighting, summing and normalizing said probabilities to obtain an overall fit probability "p fit ", where: p fit =Σw[i]·p(x[i]), for all estimates x[i]; and, Σw[i]=1.0.

Claim 50

Dependent Claim 53 words

A method as defined in claim 44, wherein said deviation comparison step comprises deriving said deviation "d[i]" as: d[i]=min{|x[i]ave-Z[i]ave|/Z[i]dev} where: Z[j], J=0,1,1. . . m, is a predetermined flame "off" signature; X is a predetermined flame "on" signature; [i] ave denotes the average signature value; and [i] dev denotes the signature standard deviation.

Claim 51

Independent Claim 26 words

A method as defined in calim 48, wherein: (a) said signature weighting function w[i]=(d[i]/d max ); and, (b) d max =Σd[i] for all spectral functions x[i].

Claim 52

Independent Claim 26 words

A method as defined in calim 48, wherein: (a) said signature weighting function w[i]=(d[i]/d max ); and, (b) d max =Σd[i] for all spectral functions x[i].

Claim 53

Dependent Claim 28 words

A method as defined in claim 48, wherein: (a) said signature weighting function 2[i]=(d[i]/d max ) 2 ; and, (b) d max =Σd[i] for all spectral functions x[i].

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-01-07	1994-07-09	1995-01-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-01-07	1998-07-09	1999-01-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-01-07	2002-07-09	2003-01-08	$7700.00	Window Closed / Lapsed

Method and apparatus for detecting flame

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