CA2117474A1 - Dual channel glass break detector - Google Patents
Dual channel glass break detectorInfo
- Publication number
- CA2117474A1 CA2117474A1 CA002117474A CA2117474A CA2117474A1 CA 2117474 A1 CA2117474 A1 CA 2117474A1 CA 002117474 A CA002117474 A CA 002117474A CA 2117474 A CA2117474 A CA 2117474A CA 2117474 A1 CA2117474 A1 CA 2117474A1
- Authority
- CA
- Canada
- Prior art keywords
- frequency
- glass
- alarm
- window
- high frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/02—Mechanical actuation
- G08B13/04—Mechanical actuation by breaking of glass
Abstract
A glass break detector for detecting the breaking of a window or the like comprises an acoustic transducer (XI) having a wide band frequency response, coupled to a dual channel filter and signal processing circuit. A low frequency channel (10, 20) detects an initial positive compression wave caused by the inward flex of the window and a high frequency channel (40, 50) detects the acoustic spectrum which is characteristic of breaking glass. The two channels are combined in a logic circuit (30, 60) that is timed so that the low frequency positive flex is detected initially with the high frequency component following shortly thereafter.
If both timing conditions are fulfilled, an alarm (100) is initiated. Additional circuitry (70, 80, 90) is provided to inhibit the alarm if a negative compression wave is initially detected. The detection sequence is initiated by a loud sound characteristic of breaking glass.
If both timing conditions are fulfilled, an alarm (100) is initiated. Additional circuitry (70, 80, 90) is provided to inhibit the alarm if a negative compression wave is initially detected. The detection sequence is initiated by a loud sound characteristic of breaking glass.
Description
WO 93/16449 PCI'/US93/01010 DUAL CXANN~L ~LASg BREA~
t~r~ Or ~ r---~t ~nv-n~rn Th- rollow1ng l~ lon r-l-t-- to a gla~-br-ak ~t~t_~ and ~or- partlcul-rly to an rcou~tlc ~tonslng da~tc- that s-n--- two dlrr-r-nt r,. _~r, c~ar-actoslctlc~ or br~~t~1n~ gla-- ~nd provld - an ~lar~ upon tn- dot-ctlon Or both c~ wlthln p,~ tls~
rr~"t-- Th- lnvontlon r--ult- rron th- ~ that ~r~-t~1nq gl~-- p.Jd - - hlqhly c - ~ l-tlc p~ or acou~tlc wav -, rnd ln psrtlcu~ar, p.Jd~ -- a ch-rao-t-rl-tic poeltlv- low r.., - I acou-tLc wavo and a h~tg~
r._ - I ~-t Or acou-ttc wav - that rollow th- inltlal low ~r~ P~~' In tn~ p--e, qla-- br-ak 1~ hav-at~ to ~l~lnat- th- G~ -- 0~ ral~t- alarr-~y ~ocu-ing on hlgh and low ~.-, I charact-r:~tlc-or br-ak~ng qla-- Th- U-S- pat-nt to Yanagl, No 4,091,660, d-t-ct- ~lgnal- ln a ~ rrng- o~
th~n 50,000 cyclo- and or gr--t-r than l00,000 cycl--, produclng an _ hl~nq ~Lgnal ~or an al~rn wh-n both rL~L-- I - . ~ ar- pr --nt at eh- ~a~ tiat- Oth-r d-vic-- , 1~- that dlr~-r nt ~ ,~~~ t ~tay b- pr---nt ~t dL~-r nt tl2-- ~n n ~ ~t al U 8 2S Pat-nt No 4,668,9~, it ~ th-t br~aklnq gl---z~ an ~nltlal low r.. , I thunp : t l. - l ~round 350 ~z ~t ~ by ~ hLgh ~ C~ L~ t around 6 s kHz Ih- 6 S kHz ~lgnal 1- lndlcatlv- or glae- that br-ak- a- lt rall- on th- rloor and ~
produclng ~ t~ inq ~ound But a- polnt-d out ln Ab-l ot al U s P~t-nt No. 4,83~,558, on- can not alway-pr-su~- that gla-- onc- brok n wlll produc- th- t~n~1~nq ~ound, partlcularly lr th- gla-- p n- or wlndow l-sleuatad abov- ~ carp-t ln an o~lc- or r-~
For zou- tl~- lntru-lon ~ _ hav- ~a~- u~-Or th- p' that th- op-nln~ or a door or ~lndow p.~ - - an ~n~ra~~~1c ~._ ~ wav- that ~tay b- ~ t~ ~ I
Sul3smuTE SHEET
WO93/1~9 PCT/US93/01010 by a sensitive microphone or other acoustic transducer having a frequency response in the region of one to five or ten cycles per second. An example of such a device is shown in Yarbrough et al. U.S. Patent No. 4,8S3,677. The Yarbrough device also includes a glass break detector circuit that is coupled to the same microphone. Either a high frequency or a low frequency event will trigger an alarm if either p.~d~ces the ~p~-u~Liate frequency ~e~L.u~. Furth~ c, it has been reoogn;~od that the opening of a door or window pLvduces negative-going air p~S~ULe in the first instance and acoustic detectors which are intrusion detectors have been ~ocignod to take adv~..Lage of this fact. An example is shown in Goldstein et al. U.S. Patent No. 4,991,145.
The afo~ Lioned glass breakage and intrusion de~ecLo~ take adv~l,La~c of some of the characteristics of breaking glass but do not always inhibit false alarms which may be p.~duced by events that have frequency char-acteristics similar to those pL~duced by breaking glass.
II~ CL they fail to take into account the fact that, ospecj~lly in the low LLe~uc..~y region, different types of glass emit different LLc~uenoy spectra when they break.
Summarv of the Present Invention The present invention takes advantage of the fact that breaking glass of every known type may be characterized by a positive low frequency acoustic wave ~L~duced by an inward flex of the glass as it is being broken from the outside of the room or enclosure to be monitored. This low frequency flex is followed by high frequency acoustic waves having a characteristic frequency spectrum.
According to the invention, an intrusion detector for detecting the breaking of a window, glass pane or the like includes an acoustic transducer such as a mi~Lu~h~--e and a signal processing circuit responsive W093/1~9 PCT/US93/OtO10 CA21 1 7~74 3 to the acoustic trAncdll~or for detecting a first low frequency positive acoustic wave generated by an inward flex of the glass and an alarm responsive to the signal processing circuit. The system further includes a high frequency bAn~rAec filter for detecting high frequency acoustic waves characteristic of breaking glass and a co;nri~on~e logic circuit that enables the alarm when the low f~e~uè1.~y acoustic wave is detected during a prede-to-n;nod time window that begins with a high L~yu~n~y event generated by the breaking glass. The alarm may then be triggered by s l;ng the high frequency output of the trAne~ or at a time after the initial time window. The logic of this system takes zdv~"~age of the fact that the requisite high fle~Uen~ ~e~,u~ of acoustic waves will follow the initial positive low f~e~u~ y wave p.~duced by the inward flex of the glass pane or window.
A circuit may also be provided to inhibit the alarm upon the detection of negative-going low frequency rher followed by high frequency sounds that would otherwise partially enable the alarm. The alarm inhibit feature significantly reduces the ;n~idon~e of false alarms such as those that would be caused by a legitimate opening of a door or window followed by high frequency sounds such as the jangling of keys. The invention also takes advantage of the fact that, regardless of the type of glass, the low frequency c -nt of breaking glass lies in the frequency region between 50 Hz and lOO ~z and that the breaking of glass is always initiated by a posi-tive compression wave. Infrasonic detectors of the priorart frequently operated on the principle that a glass break creates a low frequency sound that resonates the room, coupling it to the outside world through the broken window. The problem, however, is that such low frequency resonance may also occur for a large number of events not associated with breaking glass.
WO93/1~9 PCT/US93/01010 ~A211 7474 4 It is a principal object of this invention to provide a glass break detector that accurately discrim-inates between the sounds of breaking glass and other sounds so as to prevent false alarms.
A further object of this invention is to provide a glass break detector which can detect the breaking of different types of glass.
Yet a further object of this invention is to provide a method for detecting the breaking of a glass panel on the perimeter of an enclosure such as a room by detecting a positive low freauency plesau.a wave followed by a high L~eyuel-uy sound having a L ~yu~nuy .~e~L.
which is characteristic of breaking glass.
The foregoing and other objectives, features, and adv~rLa~s of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in cunju-,uLion with the A~' , ying drawings.
Brief DescriPtion of the Drawinas FIG. l is a block schematic diagram of the dual channel glass break detector system comprising the invention.
FIG. 2A, 2B and 2C is a detailed schematic diagram based upon the block schematic diagram of FIG. l.
FIG. 3 is a waveform diagram illustrating the essential system timing.
Detailed DescriPtion of the Invention Referring to FIG. l a glass break detector includes a microphone Xl coupled to a low freauency band pass filter lO and a high freauency filter 40 in parallel with a resistor Rl7 which is coupled to a source of supply voltage Vdd. The low freauency band pass filter lO is coupled to a set of threshold comparators 20 which define different set points for low freauency . ~~ts of the signal from the microphone Xl. The output of the WO93/1~49 PCT/US93/01010 threshold comparators 20 is coupled to a flex logic circuit 30. The high frequency filter 40 is coupled to trigger comparators 50, which initiate the timing logic for the system and are coupled to timing logic circuits 60. The output of the timing logic circuits is coupled to the flex logic circuit 30 and to a NAND gate G23. The output of the high frequency filter is also coupled to a f.eyuè1..y to-voltage converter 70 whose output is in turn coupled to a window comparator 80. The output of the window ~ ~LUL 80 drives a timed latch 90. Both the timed latch 90 and the frequency-to-voltage converter 70 receive timing inputs from the timing logic circuit 60, and the outputs of the flex logic circuit 30 and the timed latch 90 are also inputs to NAND gate G23. The output of NAND gate G23 is connected to an alarm logic circuit lO0. The details of the alarm logic circuit lO0 are not shown but the circuit is active when the output of NAND gate G23 is low. This will occur only when all three inputs to NAND gate G23 are high, and the alarm logic circuit lO0 then develops audible and/or visual alarms. The details of such circuits are well known to those of ordinary skill in the art.
Referring to FIG. 2A the microphone Xl is an electret microphone having a frequency response from 20 Hz to 20 kHz plus or minus 3 db whose output polarity is positive for an increase in al ~ ric ~Le~u~e and negative for a decrease in atmospheric pressure. The microphone should be of the type that has a wide dynamic range, greater than 120 db, and an omni-directional pickup pattern. The bias current for the microphone is supplied from a 5 volt DC source through resistor Rl7.
The output of the microphone is coupled to a high frequency channel comprising high frequency filter 40. Although the microphone chosen for this application has a wide frequency response and active filtering is used throughout, it should be recognized that frequency shaping could be accomplished partially or even entirely WO93/1~9 PCT/US93/01010 CA2i 17474 6 in the mi~-opl-~-.e design rather than in the filter design. In order to detect the breaking of laminated window glass when the microphone is at a distance from the window, the high L.ey~n~ filter 40 must have a minimum slope of 6 db per octave from o Hz to 5 kHz and then rise to a 12 db per octave slope by 8 kHz. Above 20 kHz the filter response is rolled off at a minimum -6 db per octave rate to attenuate undesired ultrasonic signals.
The network including capacitor Cl resistor Rl, capacitor C2 resistor R2, and ~ lifl~r Al form an active band pass filter with gain. Capacitor Cl isolates the DC
signal of the mi~ u~h~,,e from the circuitry of the filter and in ~--ju~-~Lion with resistor Rl ~tDrmin~e a high pass pole near 19 kHz. This : ' ci 7~e high L.~ Pe at a rate of plus 6 db per octave within the band width between 0 Hz and 19 kHz. Capacitor C2 in conjunction with resistor R2 det~rm;n~e a low pass pole near 24 kHz which provides a -6 db roll off per octave of ultrasonic L.-y~ ;ec. The network comprising capacitors C3, C4, C5 and resistors R3, R4, and R5 and amplifier A2 form a low pass filter with peaking. Capacitor C3 isolates the DC offset of the first stage from the second and in ~..ju-.~Lion with resistor R3 det~-min~c a sufficiently low high pass pole near 16 Hz. The network in the feed-back path from amplifier A2 peaks the .~..se at 20 kHz and provides additional rise in the slope from +6 db per octave. Amplifier A3 forms an additional amplification stage with the ratio of resistor R7 to resistor R6 setting the gain and capacitor C6 isolating the DC offset of amplifier A2 from the circuitry of amplifier A3.
Capacitor C6 and resistor R6 determine a sufficiently low high pass pole near 160 Hz.
The freyuency to voltage converter includes an amplifier A6 that converts the output of the high frequency filter 40 from the amplitude domain to the frequency domain. The output of A6 is gated by an AND
W093/1~9 PCT/US93/OtO10 gate Gl that is triggered by the NG (noise gate) timing signal. A signal above the zero voltage threshold on the comparator amplifier A6 turns off switch MPl and turns on switch MNl placing an amount of charge on capacitor C7 that is detDr~in~d by capacitor C15 and resistors R8 and R9 as well as the bias voltage across capacitor C7. When the signal drops below the threshold of the comparator, switch MNl is turned off and switch MPl is turned on, zeroing capacitor Cl5 and allowing the charge on capac-itor C7 to leak to ground through resistor R10. Thevoltage developed across capacitor C7 in response to this periodic signal subtracts against the voltage to charge capacitor C15 and reduces the amount of charge de}ivered to capacitor C7. The output of the frequency to voltage converter is prebiased so that it lies between the two trigger points of the window comparator 80. This is done by turning on switch MP2 and connecting a voltage source VDD to the voltage divider which is formed by resistors Rll and R10 which then charges capacitor C7.
The output of the L-~yuen~y to voltage converter is connected to the window comparator 80 which includes comparator amplifiers A7 and A8 which have out-puts coupled to AND gate G2. The output of the frequency to voltage converter 70 is prebiased through switch MP2 to keep its output between the trigger points of +800 millivolts and +340 millivolts which are inputs to comparator amplifiers A7 and A8 respectively. Voltages that result from frequencies that lie within the band of interest will allow the output of the frequency to volt-age converter 70 to stay between these trigger points.Many false alarms have average frequencies that are always below the threshold of the window comparator 80, and some false alarms start out initially below the threshold and then go above the threshold into the window. Prebiasing the output in the window makes these events invalidate the signal by driving it out of the window. This is due to the fact that all true glass WO93/1~U9 PCT/US93/01010 breaks have average frequencies that will lie in the window except for some worse case tempered glass breaks which are initially below the bottom of the window but then climb into the window within the first 10 millicocnn~c.
The output of the window comparator 80 sets a timed latch 90 that in~ oc NAND gates G4 and G5. The input to the NAND gate G4 is an OR gate G3, and the other input to the OR gate G3 is a timed 10 mi 11 i cPC~n~ pulse.
This pulse occurs when the system is initially triggered as will be oYr' A; nod below. The 10 m; 11 i cec~n~ pulse keeps the timed latch 90 from resetting during the first 10 mi 11 i ce~An~c of an event which may be a valid glass break. This is because as oYrl A i nod above, some types of lS glass, particularly t~ ~=d glass, can break without nPcoccArily generating L.~luo~ iec during the first 10 mi 11 i coc~c which would be within the limits of the window comparator 80. The 10 mi 11 i ceC~n~ pulse keeps the latch 90 from resetting if the break is of this type of glass. After the initial 10 milliseconds, the output of the window comparator 80 alone will determine whether the latch 90 is reset. The latch is enabled by the timed NG
(noise gate) signal whose origin will be oYp1Ainod below.
The output of the microphone Xl is also connected to a low Lle~u~ y band pass filter 10 which consists of two amplifiers A9 and A10 together with iate feedback networks. This filter has a frequency response that : 'Aci 7es the 50 Hz to 100 Hz region, since it has been empirically determined that the initial flex made by glass just prior to its being broken is found within this frequency region. Also the positive pressure wave resulting from the initial inward flex just prior to a break is of higher magnitude than an outward flex oCroc;Ally for tempered glass. When tempered glass breaks, the outward flex after the initial inward flex is highly damped, thus detection schemes that are triggered by either an outward flex or by cycle counting may fail WO93/1~9 PCT/US93/01010 to detect many such breaks. The filter lO is therefore configured to have an output in the low frequency region that naturally occurs in all types of glass breaks.
The output of the filter lO is connected to a threshold comparator network 20 which includes compar-ators All, Al2 and Al3. The comparator amplifier All detects p~S~ULa waves associated with objects breaking a window and its threshold is set s~ f f i'-- j ~ntly low to detect worst case flexes. This is because it has been d-term;ne~ that tempered glass, _Cp~ci~11y, generates a positive ~-as~u.a wave that is much lower in amplitude than those caused by breaking plate and laminated glass.
C ator Al3 detects high level p~as~u.e waves created in very small rooms or airlocks which would be detected before a window or pane actually breaks. C - ~tor amplifier Al2 is part of an inhibit network that detects negative ~.~s~u.a which is not associated with glass breaking. The outputs of these three comparators are analyzed in the flex logic circuit 30.
Even though the window flexes before it breaks, the high fre~-n~ q of the break will reach their peak before the low frequency pressure wave resulting from a valid flex does and are thus easier to detect first. It has been empirically det-rm;~ d that a valid flex is always detectable within less than lO m; 11; ~e~ nAc after detection of the first high C-a~uen~y ~ -nts of the break. Therefore, a positive transition above the thres-hold of comparator amplifier All triggers a l millisecond one shot comprised of amplifier G22 and flip flops F27 and F28, the purpose of which is to indicate an immedi-ately occurring increase in positive al ~t.eric pres-sure. Either the output of comparator Al3 or All will set the latch comprised of NAND gates G20 and G21 unless inhibited by the latch comprised of NAND gates Gl4 and Gl5. Because of the lO millisecond input to NAND gate Gl9, this event must occur, if at all, within the first lO milliseconds of the break event. The output latch, CA21 17474 lo which is comprised of NAND gates G20 and G21 is enabled by the NG signal.
In the case of an initially negative-going pressure wave occurring within the first 10 mill;~ecnn~c, latch G14, G15 will be low preventing AND gates G16 or G17 from passing a valid high signal to OR gate G18.
This forces the latch G20, G21 low which in turn forces the output of NAND gate G23 high, disabling the alarm.
The timing logic network 60 is triggered by a high eyuel~uy event initiated by the trigger comparator circuit 50. This circuit includes two trigger l;fi~s A4 and A5. Comparator amplifier A5, which has a rela-tively low threshold, institutes a five m; 11; ~cn~
retriggerable one shot whose output resets flip flop F4.
If the amplitude of the high frequency event is high enough, comparator amplifier A4 is triggered which clocks flip flop F4 and p~uduces the NG (noise gate) pulse.
From the noise gate pulse a chain of flip flops F5-Fll are triggered which develop pulses at various times and having various duty cycles. A 10 m; 11; ~cnn~ timing pulse whose leading edge is substantially aligned with the NG pulse is p,uduced by flip flop F12. This pulse is then provided as an input to NAND gates G15, Gl9 and OR
gate G3. The AND gate G10 produces a 77 millisecond pulse (i.e., its leading edge is initiated at 77 milli-seconds) in order to enable NAND gate G23. Thus, accord-ing to the system logic, if the high frequency ,_ ~nts of the break have not driven the output of the frequency to voltage converter 70 out of the window est~hl;~h~d by the window comparator 80 after the initial 10 milli-seconds of the break, and before 77 ms after the break, and if the initial low frequency pressure wave OceuLL~d within the first 10 milliseconds of the break, a valid alarm condition will be sensed.
FIG. 3 illustrates the essential timing of the system. A typical glass break signal generates the filter outputs shown in FIG. 3 and the NG and 10 WO93/1~9 PCT/US93/01010 'C~2~ ~ 7~
millisecond pulse signals are generated accordingly.Because the break event is in the correct frequency range and of sufficient amplitude to trigger the timing logic in network 60, the output of the low frequency band pass S filter lO goes sufficiently high within the first lO
millie~cnn~c to set the latch G20, G21 at the output of the low frequency channel. The time between the end of the lO millieecnnA pulse and the beginning of the pulse at 77 milliseconds is a period during which the high o r e~uel~y channel can be driven out of the window estab-lished in the window comparator 80 by an invalid signal.
If it is not driven out of the window, however, at the initiation of the pulse at 77 millicecnn~e, the alarm will be triggered. The noise gate signal can be reset anytime the high Lle4ueney signal goes below its threshold for greater than 5 millieecnn~e.
It should be appreciated that various clock rle~ue..ey signals and voltages are used herein but the circuits generating them are not shown. For example, the signal MR~ is a master reset pulse generated upon power-up of the system by the power supply. These signals are produced by conventional oscillators and voltage supplies and as such their details are well known to those of ordinary skill in the art.
Various modifications to the above invention are possible without departing from the spirit of the invention. For example, the high and low rle~uè..ey filters may be of different configuration from those shown and could even be incorporated in the trAne~n~r design. Also, the frequency to voltage converter andwindow comparator circuits have been shown with the system biased to assume a valid signal which can be forced out of the window. This gives the system a faster response and makes it easier to detect the breaking of tempered glass. The system could be configured, however, so that a valid signal must occur before an enabling signal would be provided by a latch or the like.
WO93/1~9 PCT/US93/01010 ~A2 1 1 7 474 12 The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expres-sions, of excluding equivalents of the features shown anddescribed or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
t~r~ Or ~ r---~t ~nv-n~rn Th- rollow1ng l~ lon r-l-t-- to a gla~-br-ak ~t~t_~ and ~or- partlcul-rly to an rcou~tlc ~tonslng da~tc- that s-n--- two dlrr-r-nt r,. _~r, c~ar-actoslctlc~ or br~~t~1n~ gla-- ~nd provld - an ~lar~ upon tn- dot-ctlon Or both c~ wlthln p,~ tls~
rr~"t-- Th- lnvontlon r--ult- rron th- ~ that ~r~-t~1nq gl~-- p.Jd - - hlqhly c - ~ l-tlc p~ or acou~tlc wav -, rnd ln psrtlcu~ar, p.Jd~ -- a ch-rao-t-rl-tic poeltlv- low r.., - I acou-tLc wavo and a h~tg~
r._ - I ~-t Or acou-ttc wav - that rollow th- inltlal low ~r~ P~~' In tn~ p--e, qla-- br-ak 1~ hav-at~ to ~l~lnat- th- G~ -- 0~ ral~t- alarr-~y ~ocu-ing on hlgh and low ~.-, I charact-r:~tlc-or br-ak~ng qla-- Th- U-S- pat-nt to Yanagl, No 4,091,660, d-t-ct- ~lgnal- ln a ~ rrng- o~
th~n 50,000 cyclo- and or gr--t-r than l00,000 cycl--, produclng an _ hl~nq ~Lgnal ~or an al~rn wh-n both rL~L-- I - . ~ ar- pr --nt at eh- ~a~ tiat- Oth-r d-vic-- , 1~- that dlr~-r nt ~ ,~~~ t ~tay b- pr---nt ~t dL~-r nt tl2-- ~n n ~ ~t al U 8 2S Pat-nt No 4,668,9~, it ~ th-t br~aklnq gl---z~ an ~nltlal low r.. , I thunp : t l. - l ~round 350 ~z ~t ~ by ~ hLgh ~ C~ L~ t around 6 s kHz Ih- 6 S kHz ~lgnal 1- lndlcatlv- or glae- that br-ak- a- lt rall- on th- rloor and ~
produclng ~ t~ inq ~ound But a- polnt-d out ln Ab-l ot al U s P~t-nt No. 4,83~,558, on- can not alway-pr-su~- that gla-- onc- brok n wlll produc- th- t~n~1~nq ~ound, partlcularly lr th- gla-- p n- or wlndow l-sleuatad abov- ~ carp-t ln an o~lc- or r-~
For zou- tl~- lntru-lon ~ _ hav- ~a~- u~-Or th- p' that th- op-nln~ or a door or ~lndow p.~ - - an ~n~ra~~~1c ~._ ~ wav- that ~tay b- ~ t~ ~ I
Sul3smuTE SHEET
WO93/1~9 PCT/US93/01010 by a sensitive microphone or other acoustic transducer having a frequency response in the region of one to five or ten cycles per second. An example of such a device is shown in Yarbrough et al. U.S. Patent No. 4,8S3,677. The Yarbrough device also includes a glass break detector circuit that is coupled to the same microphone. Either a high frequency or a low frequency event will trigger an alarm if either p.~d~ces the ~p~-u~Liate frequency ~e~L.u~. Furth~ c, it has been reoogn;~od that the opening of a door or window pLvduces negative-going air p~S~ULe in the first instance and acoustic detectors which are intrusion detectors have been ~ocignod to take adv~..Lage of this fact. An example is shown in Goldstein et al. U.S. Patent No. 4,991,145.
The afo~ Lioned glass breakage and intrusion de~ecLo~ take adv~l,La~c of some of the characteristics of breaking glass but do not always inhibit false alarms which may be p.~duced by events that have frequency char-acteristics similar to those pL~duced by breaking glass.
II~ CL they fail to take into account the fact that, ospecj~lly in the low LLe~uc..~y region, different types of glass emit different LLc~uenoy spectra when they break.
Summarv of the Present Invention The present invention takes advantage of the fact that breaking glass of every known type may be characterized by a positive low frequency acoustic wave ~L~duced by an inward flex of the glass as it is being broken from the outside of the room or enclosure to be monitored. This low frequency flex is followed by high frequency acoustic waves having a characteristic frequency spectrum.
According to the invention, an intrusion detector for detecting the breaking of a window, glass pane or the like includes an acoustic transducer such as a mi~Lu~h~--e and a signal processing circuit responsive W093/1~9 PCT/US93/OtO10 CA21 1 7~74 3 to the acoustic trAncdll~or for detecting a first low frequency positive acoustic wave generated by an inward flex of the glass and an alarm responsive to the signal processing circuit. The system further includes a high frequency bAn~rAec filter for detecting high frequency acoustic waves characteristic of breaking glass and a co;nri~on~e logic circuit that enables the alarm when the low f~e~uè1.~y acoustic wave is detected during a prede-to-n;nod time window that begins with a high L~yu~n~y event generated by the breaking glass. The alarm may then be triggered by s l;ng the high frequency output of the trAne~ or at a time after the initial time window. The logic of this system takes zdv~"~age of the fact that the requisite high fle~Uen~ ~e~,u~ of acoustic waves will follow the initial positive low f~e~u~ y wave p.~duced by the inward flex of the glass pane or window.
A circuit may also be provided to inhibit the alarm upon the detection of negative-going low frequency rher followed by high frequency sounds that would otherwise partially enable the alarm. The alarm inhibit feature significantly reduces the ;n~idon~e of false alarms such as those that would be caused by a legitimate opening of a door or window followed by high frequency sounds such as the jangling of keys. The invention also takes advantage of the fact that, regardless of the type of glass, the low frequency c -nt of breaking glass lies in the frequency region between 50 Hz and lOO ~z and that the breaking of glass is always initiated by a posi-tive compression wave. Infrasonic detectors of the priorart frequently operated on the principle that a glass break creates a low frequency sound that resonates the room, coupling it to the outside world through the broken window. The problem, however, is that such low frequency resonance may also occur for a large number of events not associated with breaking glass.
WO93/1~9 PCT/US93/01010 ~A211 7474 4 It is a principal object of this invention to provide a glass break detector that accurately discrim-inates between the sounds of breaking glass and other sounds so as to prevent false alarms.
A further object of this invention is to provide a glass break detector which can detect the breaking of different types of glass.
Yet a further object of this invention is to provide a method for detecting the breaking of a glass panel on the perimeter of an enclosure such as a room by detecting a positive low freauency plesau.a wave followed by a high L~eyuel-uy sound having a L ~yu~nuy .~e~L.
which is characteristic of breaking glass.
The foregoing and other objectives, features, and adv~rLa~s of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in cunju-,uLion with the A~' , ying drawings.
Brief DescriPtion of the Drawinas FIG. l is a block schematic diagram of the dual channel glass break detector system comprising the invention.
FIG. 2A, 2B and 2C is a detailed schematic diagram based upon the block schematic diagram of FIG. l.
FIG. 3 is a waveform diagram illustrating the essential system timing.
Detailed DescriPtion of the Invention Referring to FIG. l a glass break detector includes a microphone Xl coupled to a low freauency band pass filter lO and a high freauency filter 40 in parallel with a resistor Rl7 which is coupled to a source of supply voltage Vdd. The low freauency band pass filter lO is coupled to a set of threshold comparators 20 which define different set points for low freauency . ~~ts of the signal from the microphone Xl. The output of the WO93/1~49 PCT/US93/01010 threshold comparators 20 is coupled to a flex logic circuit 30. The high frequency filter 40 is coupled to trigger comparators 50, which initiate the timing logic for the system and are coupled to timing logic circuits 60. The output of the timing logic circuits is coupled to the flex logic circuit 30 and to a NAND gate G23. The output of the high frequency filter is also coupled to a f.eyuè1..y to-voltage converter 70 whose output is in turn coupled to a window comparator 80. The output of the window ~ ~LUL 80 drives a timed latch 90. Both the timed latch 90 and the frequency-to-voltage converter 70 receive timing inputs from the timing logic circuit 60, and the outputs of the flex logic circuit 30 and the timed latch 90 are also inputs to NAND gate G23. The output of NAND gate G23 is connected to an alarm logic circuit lO0. The details of the alarm logic circuit lO0 are not shown but the circuit is active when the output of NAND gate G23 is low. This will occur only when all three inputs to NAND gate G23 are high, and the alarm logic circuit lO0 then develops audible and/or visual alarms. The details of such circuits are well known to those of ordinary skill in the art.
Referring to FIG. 2A the microphone Xl is an electret microphone having a frequency response from 20 Hz to 20 kHz plus or minus 3 db whose output polarity is positive for an increase in al ~ ric ~Le~u~e and negative for a decrease in atmospheric pressure. The microphone should be of the type that has a wide dynamic range, greater than 120 db, and an omni-directional pickup pattern. The bias current for the microphone is supplied from a 5 volt DC source through resistor Rl7.
The output of the microphone is coupled to a high frequency channel comprising high frequency filter 40. Although the microphone chosen for this application has a wide frequency response and active filtering is used throughout, it should be recognized that frequency shaping could be accomplished partially or even entirely WO93/1~9 PCT/US93/01010 CA2i 17474 6 in the mi~-opl-~-.e design rather than in the filter design. In order to detect the breaking of laminated window glass when the microphone is at a distance from the window, the high L.ey~n~ filter 40 must have a minimum slope of 6 db per octave from o Hz to 5 kHz and then rise to a 12 db per octave slope by 8 kHz. Above 20 kHz the filter response is rolled off at a minimum -6 db per octave rate to attenuate undesired ultrasonic signals.
The network including capacitor Cl resistor Rl, capacitor C2 resistor R2, and ~ lifl~r Al form an active band pass filter with gain. Capacitor Cl isolates the DC
signal of the mi~ u~h~,,e from the circuitry of the filter and in ~--ju~-~Lion with resistor Rl ~tDrmin~e a high pass pole near 19 kHz. This : ' ci 7~e high L.~ Pe at a rate of plus 6 db per octave within the band width between 0 Hz and 19 kHz. Capacitor C2 in conjunction with resistor R2 det~rm;n~e a low pass pole near 24 kHz which provides a -6 db roll off per octave of ultrasonic L.-y~ ;ec. The network comprising capacitors C3, C4, C5 and resistors R3, R4, and R5 and amplifier A2 form a low pass filter with peaking. Capacitor C3 isolates the DC offset of the first stage from the second and in ~..ju-.~Lion with resistor R3 det~-min~c a sufficiently low high pass pole near 16 Hz. The network in the feed-back path from amplifier A2 peaks the .~..se at 20 kHz and provides additional rise in the slope from +6 db per octave. Amplifier A3 forms an additional amplification stage with the ratio of resistor R7 to resistor R6 setting the gain and capacitor C6 isolating the DC offset of amplifier A2 from the circuitry of amplifier A3.
Capacitor C6 and resistor R6 determine a sufficiently low high pass pole near 160 Hz.
The freyuency to voltage converter includes an amplifier A6 that converts the output of the high frequency filter 40 from the amplitude domain to the frequency domain. The output of A6 is gated by an AND
W093/1~9 PCT/US93/OtO10 gate Gl that is triggered by the NG (noise gate) timing signal. A signal above the zero voltage threshold on the comparator amplifier A6 turns off switch MPl and turns on switch MNl placing an amount of charge on capacitor C7 that is detDr~in~d by capacitor C15 and resistors R8 and R9 as well as the bias voltage across capacitor C7. When the signal drops below the threshold of the comparator, switch MNl is turned off and switch MPl is turned on, zeroing capacitor Cl5 and allowing the charge on capac-itor C7 to leak to ground through resistor R10. Thevoltage developed across capacitor C7 in response to this periodic signal subtracts against the voltage to charge capacitor C15 and reduces the amount of charge de}ivered to capacitor C7. The output of the frequency to voltage converter is prebiased so that it lies between the two trigger points of the window comparator 80. This is done by turning on switch MP2 and connecting a voltage source VDD to the voltage divider which is formed by resistors Rll and R10 which then charges capacitor C7.
The output of the L-~yuen~y to voltage converter is connected to the window comparator 80 which includes comparator amplifiers A7 and A8 which have out-puts coupled to AND gate G2. The output of the frequency to voltage converter 70 is prebiased through switch MP2 to keep its output between the trigger points of +800 millivolts and +340 millivolts which are inputs to comparator amplifiers A7 and A8 respectively. Voltages that result from frequencies that lie within the band of interest will allow the output of the frequency to volt-age converter 70 to stay between these trigger points.Many false alarms have average frequencies that are always below the threshold of the window comparator 80, and some false alarms start out initially below the threshold and then go above the threshold into the window. Prebiasing the output in the window makes these events invalidate the signal by driving it out of the window. This is due to the fact that all true glass WO93/1~U9 PCT/US93/01010 breaks have average frequencies that will lie in the window except for some worse case tempered glass breaks which are initially below the bottom of the window but then climb into the window within the first 10 millicocnn~c.
The output of the window comparator 80 sets a timed latch 90 that in~ oc NAND gates G4 and G5. The input to the NAND gate G4 is an OR gate G3, and the other input to the OR gate G3 is a timed 10 mi 11 i cPC~n~ pulse.
This pulse occurs when the system is initially triggered as will be oYr' A; nod below. The 10 m; 11 i cec~n~ pulse keeps the timed latch 90 from resetting during the first 10 mi 11 i ce~An~c of an event which may be a valid glass break. This is because as oYrl A i nod above, some types of lS glass, particularly t~ ~=d glass, can break without nPcoccArily generating L.~luo~ iec during the first 10 mi 11 i coc~c which would be within the limits of the window comparator 80. The 10 mi 11 i ceC~n~ pulse keeps the latch 90 from resetting if the break is of this type of glass. After the initial 10 milliseconds, the output of the window comparator 80 alone will determine whether the latch 90 is reset. The latch is enabled by the timed NG
(noise gate) signal whose origin will be oYp1Ainod below.
The output of the microphone Xl is also connected to a low Lle~u~ y band pass filter 10 which consists of two amplifiers A9 and A10 together with iate feedback networks. This filter has a frequency response that : 'Aci 7es the 50 Hz to 100 Hz region, since it has been empirically determined that the initial flex made by glass just prior to its being broken is found within this frequency region. Also the positive pressure wave resulting from the initial inward flex just prior to a break is of higher magnitude than an outward flex oCroc;Ally for tempered glass. When tempered glass breaks, the outward flex after the initial inward flex is highly damped, thus detection schemes that are triggered by either an outward flex or by cycle counting may fail WO93/1~9 PCT/US93/01010 to detect many such breaks. The filter lO is therefore configured to have an output in the low frequency region that naturally occurs in all types of glass breaks.
The output of the filter lO is connected to a threshold comparator network 20 which includes compar-ators All, Al2 and Al3. The comparator amplifier All detects p~S~ULa waves associated with objects breaking a window and its threshold is set s~ f f i'-- j ~ntly low to detect worst case flexes. This is because it has been d-term;ne~ that tempered glass, _Cp~ci~11y, generates a positive ~-as~u.a wave that is much lower in amplitude than those caused by breaking plate and laminated glass.
C ator Al3 detects high level p~as~u.e waves created in very small rooms or airlocks which would be detected before a window or pane actually breaks. C - ~tor amplifier Al2 is part of an inhibit network that detects negative ~.~s~u.a which is not associated with glass breaking. The outputs of these three comparators are analyzed in the flex logic circuit 30.
Even though the window flexes before it breaks, the high fre~-n~ q of the break will reach their peak before the low frequency pressure wave resulting from a valid flex does and are thus easier to detect first. It has been empirically det-rm;~ d that a valid flex is always detectable within less than lO m; 11; ~e~ nAc after detection of the first high C-a~uen~y ~ -nts of the break. Therefore, a positive transition above the thres-hold of comparator amplifier All triggers a l millisecond one shot comprised of amplifier G22 and flip flops F27 and F28, the purpose of which is to indicate an immedi-ately occurring increase in positive al ~t.eric pres-sure. Either the output of comparator Al3 or All will set the latch comprised of NAND gates G20 and G21 unless inhibited by the latch comprised of NAND gates Gl4 and Gl5. Because of the lO millisecond input to NAND gate Gl9, this event must occur, if at all, within the first lO milliseconds of the break event. The output latch, CA21 17474 lo which is comprised of NAND gates G20 and G21 is enabled by the NG signal.
In the case of an initially negative-going pressure wave occurring within the first 10 mill;~ecnn~c, latch G14, G15 will be low preventing AND gates G16 or G17 from passing a valid high signal to OR gate G18.
This forces the latch G20, G21 low which in turn forces the output of NAND gate G23 high, disabling the alarm.
The timing logic network 60 is triggered by a high eyuel~uy event initiated by the trigger comparator circuit 50. This circuit includes two trigger l;fi~s A4 and A5. Comparator amplifier A5, which has a rela-tively low threshold, institutes a five m; 11; ~cn~
retriggerable one shot whose output resets flip flop F4.
If the amplitude of the high frequency event is high enough, comparator amplifier A4 is triggered which clocks flip flop F4 and p~uduces the NG (noise gate) pulse.
From the noise gate pulse a chain of flip flops F5-Fll are triggered which develop pulses at various times and having various duty cycles. A 10 m; 11; ~cnn~ timing pulse whose leading edge is substantially aligned with the NG pulse is p,uduced by flip flop F12. This pulse is then provided as an input to NAND gates G15, Gl9 and OR
gate G3. The AND gate G10 produces a 77 millisecond pulse (i.e., its leading edge is initiated at 77 milli-seconds) in order to enable NAND gate G23. Thus, accord-ing to the system logic, if the high frequency ,_ ~nts of the break have not driven the output of the frequency to voltage converter 70 out of the window est~hl;~h~d by the window comparator 80 after the initial 10 milli-seconds of the break, and before 77 ms after the break, and if the initial low frequency pressure wave OceuLL~d within the first 10 milliseconds of the break, a valid alarm condition will be sensed.
FIG. 3 illustrates the essential timing of the system. A typical glass break signal generates the filter outputs shown in FIG. 3 and the NG and 10 WO93/1~9 PCT/US93/01010 'C~2~ ~ 7~
millisecond pulse signals are generated accordingly.Because the break event is in the correct frequency range and of sufficient amplitude to trigger the timing logic in network 60, the output of the low frequency band pass S filter lO goes sufficiently high within the first lO
millie~cnn~c to set the latch G20, G21 at the output of the low frequency channel. The time between the end of the lO millieecnnA pulse and the beginning of the pulse at 77 milliseconds is a period during which the high o r e~uel~y channel can be driven out of the window estab-lished in the window comparator 80 by an invalid signal.
If it is not driven out of the window, however, at the initiation of the pulse at 77 millicecnn~e, the alarm will be triggered. The noise gate signal can be reset anytime the high Lle4ueney signal goes below its threshold for greater than 5 millieecnn~e.
It should be appreciated that various clock rle~ue..ey signals and voltages are used herein but the circuits generating them are not shown. For example, the signal MR~ is a master reset pulse generated upon power-up of the system by the power supply. These signals are produced by conventional oscillators and voltage supplies and as such their details are well known to those of ordinary skill in the art.
Various modifications to the above invention are possible without departing from the spirit of the invention. For example, the high and low rle~uè..ey filters may be of different configuration from those shown and could even be incorporated in the trAne~n~r design. Also, the frequency to voltage converter andwindow comparator circuits have been shown with the system biased to assume a valid signal which can be forced out of the window. This gives the system a faster response and makes it easier to detect the breaking of tempered glass. The system could be configured, however, so that a valid signal must occur before an enabling signal would be provided by a latch or the like.
WO93/1~9 PCT/US93/01010 ~A2 1 1 7 474 12 The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expres-sions, of excluding equivalents of the features shown anddescribed or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS,
1. A glass break detector for detecting the breaking of a window or the like comprising:
(a) an acoustic transducer:
(b) flex detection circuit responsive to the acoustic transducer for detecting a low frequency positive acoustic wave characteristic of an inward flex of the window; and (c) alarm circuit responsive to the flex detection circuit for generating an alarm.
(a) an acoustic transducer:
(b) flex detection circuit responsive to the acoustic transducer for detecting a low frequency positive acoustic wave characteristic of an inward flex of the window; and (c) alarm circuit responsive to the flex detection circuit for generating an alarm.
2. The glass break detector of claim 1, further including high frequency bandpass filter for detecting high frequency acoustic waves characteristic of breaking glass, and logic network for enabling said alarm circuit when said low frequency positive acoustic wave is detected by said flex detection circuit during a predetermined time window initiated by said high frequency acoustic waves.
3. The glass break detector of claim 2, further including alarm inhibit network for detecting a low frequency negative acoustic wave and for disabling said alarm circuit if said low frequency negative acoustic wave is detected during said time window.
4. The glass break detector of claims 2 or 3, further including signal processing network responsive to said high frequency bandpass filter for sensing acoustic waves within a preselected frequency range of said high frequency acoustic waves and for providing an alarm-disabling signal if waves having frequencies outside of said range are detected after said predetermined time window.
5. The glass break detector of claim 4, wherein said signal processing network comprises a frequency-to-voltage converter having an output whose amplitude varies with frequency and a window comparator for providing upper and lower frequency limits for said frequency range of said high frequency acoustic waves.
6. The glass break detector of claim 5, further including alarm timing network for activating said alarm when said high frequency acoustic waves are within the frequency limits of said window comparator at a predetermined time after said alarm circuit is enabled by said logic circuit.
7. The glass break detector of claims 1 or 6, wherein said acoustic transducer is an electret microphone having a wide frequency response.
8. The glass break detector of claims 3 or 6, wherein said low frequency negative acoustic wave is detected prior to when said low frequency positive acoustic wave is detected.
9. The glass break detector of claims 5 or 6, wherein said frequency-to-voltage converter is prebiased to have an output between the upper and lower frequency limits of said window comparator.
10. A method of monitoring the breaking of glass incident to an intrusion, comprising the steps of:
(a) detecting the occurrence of high frequency acoustic waves characteristic of breaking glass;
(b) detecting a positive low frequency acoustic wave characteristic of an inward flex of the glass within a short time window coincident with the first occurrence of said high frequency acoustic waves: and (c) initiating an alarm after performing steps (a) and (b).
(a) detecting the occurrence of high frequency acoustic waves characteristic of breaking glass;
(b) detecting a positive low frequency acoustic wave characteristic of an inward flex of the glass within a short time window coincident with the first occurrence of said high frequency acoustic waves: and (c) initiating an alarm after performing steps (a) and (b).
11. The method of claim 10, further including the step of detecting the occurrence of high frequency acoustic waves that lie within predetermined frequency limits for a time period after the expiration of the time window of step (b) as a prerequisite to performing step (c).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07835733 US5192931B1 (en) | 1992-02-11 | 1992-02-11 | Dual channel glass break detector |
| US07/835,733 | 1992-02-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2117474A1 true CA2117474A1 (en) | 1993-08-19 |
Family
ID=25270325
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002117474A Abandoned CA2117474A1 (en) | 1992-02-11 | 1993-02-05 | Dual channel glass break detector |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5192931B1 (en) |
| EP (1) | EP0626086A4 (en) |
| JP (1) | JPH07500438A (en) |
| CA (1) | CA2117474A1 (en) |
| WO (1) | WO1993016449A1 (en) |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5341122A (en) * | 1992-06-22 | 1994-08-23 | C & K Systems, Inc. | Pressure actuated glass break simulator |
| US5376919A (en) * | 1992-07-01 | 1994-12-27 | C & K Systems, Inc. | Vehicle intrusion detector |
| US5414409A (en) * | 1992-07-23 | 1995-05-09 | International Electronics, Inc. | Alarm system for detecting an audio signal when glass breakage occurs |
| AU7253094A (en) * | 1993-06-30 | 1995-01-24 | Sentrol, Inc. | Glass break detector having reduced susceptibility to false alarms |
| IL107834A (en) * | 1993-12-01 | 1997-08-14 | Visonic Ltd | Glass breakage detector |
| CA2117053C (en) * | 1994-03-04 | 2000-07-25 | Dennis Cecic | Detection of glass breakage |
| US5428345A (en) * | 1994-03-30 | 1995-06-27 | Sentrol, Inc. | Method of and apparatus for operating a security system to produce an alarm signal |
| US5438317A (en) * | 1994-04-08 | 1995-08-01 | Detection Systems, Inc. | Glass break detection with noise riding feature |
| US5450061A (en) * | 1994-04-08 | 1995-09-12 | Detection Systems, Inc. | Glass break detection using temporal sequence of selected frequency characteristics |
| US5543783A (en) * | 1994-05-20 | 1996-08-06 | Caddx-Caddi Controls, Inc. | Glass break detector and a method therefor |
| JP3298318B2 (en) * | 1994-07-18 | 2002-07-02 | 株式会社デンソー | Glass break detector |
| US5640142A (en) * | 1995-02-01 | 1997-06-17 | Pittway Corporation | Alarm system testing circuit |
| DE19521194A1 (en) * | 1995-06-10 | 1996-12-12 | Telefunken Microelectron | Monitoring method for openings, covered by glass panes, in closed and locked cabinets or cars |
| US5608377A (en) * | 1995-10-20 | 1997-03-04 | Visonic Ltd. | Acoustic anti-tampering detector |
| JPH09297892A (en) * | 1996-03-08 | 1997-11-18 | Denso Corp | Glass cracking detector |
| US6150927A (en) * | 1998-03-30 | 2000-11-21 | Nextbus Information Systems, Llc | Anti-vandalism detector and alarm system |
| GB2370118B (en) | 1999-05-07 | 2003-10-22 | Honeywell Inc | Glass-break detector and method of alarm discrimination |
| US6493687B1 (en) * | 1999-12-18 | 2002-12-10 | Detection Systems, Inc. | Apparatus and method for detecting glass break |
| US6452403B1 (en) * | 2000-03-09 | 2002-09-17 | Trw Inc. | Test apparatus for vehicle intrusion alarm |
| US7323979B2 (en) * | 2004-05-25 | 2008-01-29 | Honeywell International, Inc. | Dual technology glass breakage detector |
| US7388487B2 (en) * | 2004-06-17 | 2008-06-17 | Honeywell International, Inc. | Method of eliminating impact/shock related false alarms in an acoustical glassbreak detector |
| US7680283B2 (en) * | 2005-02-07 | 2010-03-16 | Honeywell International Inc. | Method and system for detecting a predetermined sound event such as the sound of breaking glass |
| US8410923B2 (en) * | 2008-11-25 | 2013-04-02 | Randall Wang | Single MCU-based motion detection, local alarm and supervisory arrangement for alarm system |
| US9697707B2 (en) * | 2011-05-11 | 2017-07-04 | Honeywell International Inc. | Highly directional glassbreak detector |
| US9188487B2 (en) | 2011-11-16 | 2015-11-17 | Tyco Fire & Security Gmbh | Motion detection systems and methodologies |
| GB201309549D0 (en) * | 2013-05-29 | 2013-07-10 | Pilkington Group Ltd | Glazing |
| US9349269B2 (en) | 2014-01-06 | 2016-05-24 | Tyco Fire & Security Gmbh | Glass breakage detection system and method of configuration thereof |
| US9530293B2 (en) | 2014-09-30 | 2016-12-27 | Tyco Fire & Security Gmbh | Wireless acoustic glass breakage detectors |
| GB201701924D0 (en) | 2017-02-06 | 2017-03-22 | Belron Int Ltd | Systems and methods for damage detection |
| US11066819B2 (en) * | 2018-02-02 | 2021-07-20 | Israel Rosario | Drain stopper with removable debris trap |
| EP4097696B1 (en) * | 2020-10-15 | 2024-01-24 | Arhub S.A. | Devices and system |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4091660A (en) * | 1977-03-16 | 1978-05-30 | Matsushita Electric Industrial Co., Ltd. | Apparatus for detecting the breaking of a glass plate |
| GB2171518B (en) * | 1985-02-08 | 1988-09-01 | Automated Security Holdings | Glass break detector |
| US4837558A (en) * | 1987-10-13 | 1989-06-06 | Sentrol, Inc. | Glass break detector |
| US4853677A (en) * | 1988-07-20 | 1989-08-01 | Yarbrough Alfred E | Portable intrusion alarm |
| US4991145A (en) * | 1988-08-03 | 1991-02-05 | Rabbit Systems, Inc. | Infra-sonic detector and alarm with self adjusting reference |
| US5117220A (en) * | 1991-02-11 | 1992-05-26 | Pittway Corporation | Glass breakage detector |
-
1992
- 1992-02-11 US US07835733 patent/US5192931B1/en not_active Expired - Lifetime
-
1993
- 1993-02-05 CA CA002117474A patent/CA2117474A1/en not_active Abandoned
- 1993-02-05 EP EP93904902A patent/EP0626086A4/en not_active Withdrawn
- 1993-02-05 WO PCT/US1993/001010 patent/WO1993016449A1/en not_active Application Discontinuation
- 1993-02-05 JP JP5514174A patent/JPH07500438A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| WO1993016449A1 (en) | 1993-08-19 |
| US5192931B1 (en) | 1999-09-28 |
| EP0626086A4 (en) | 1995-08-30 |
| EP0626086A1 (en) | 1994-11-30 |
| JPH07500438A (en) | 1995-01-12 |
| US5192931A (en) | 1993-03-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |