CA1095302A - Optics for infrared intrusion detector - Google Patents
Optics for infrared intrusion detectorInfo
- Publication number
- CA1095302A CA1095302A CA329,480A CA329480A CA1095302A CA 1095302 A CA1095302 A CA 1095302A CA 329480 A CA329480 A CA 329480A CA 1095302 A CA1095302 A CA 1095302A
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- Canada
- Prior art keywords
- radiation
- infrared
- mirror
- detector
- intrusion detector
- 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.)
- Expired
Links
- 230000005855 radiation Effects 0.000 claims abstract description 108
- 230000003287 optical effect Effects 0.000 claims abstract description 31
- 238000001514 detection method Methods 0.000 claims abstract description 30
- 238000012806 monitoring device Methods 0.000 abstract 1
- 238000013459 approach Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000003491 array Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- RZVXOCDCIIFGGH-UHFFFAOYSA-N chromium gold Chemical compound [Cr].[Au] RZVXOCDCIIFGGH-UHFFFAOYSA-N 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000002844 continuous effect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/19—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems
- G08B13/193—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems using focusing means
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Burglar Alarm Systems (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An infrared intrusion detector has an optical system for gathering infrared radiation from discrete sensitive regions and focusing such received radiation onto an infrared radiation sensor. The detector includes a monitoring device to sound an alarm when radiation sensed reaches a predetermined level. The optical system comprises an optical collector for gathering radiation from a field which includes the sensitive regions and for converging such radiation onto a plurality of reflectors. Each reflector determines one of the discrete sensitive regions and, in turn, is oriented to reflect converging radiation gathered from a sensitive region on the detector. The invention provides a simple, efficient optic system for a broad field of gathering infrared radiation, concentrating and focusing it in a manner to provide sufficient levels of received radiation for purposes of detection.
An infrared intrusion detector has an optical system for gathering infrared radiation from discrete sensitive regions and focusing such received radiation onto an infrared radiation sensor. The detector includes a monitoring device to sound an alarm when radiation sensed reaches a predetermined level. The optical system comprises an optical collector for gathering radiation from a field which includes the sensitive regions and for converging such radiation onto a plurality of reflectors. Each reflector determines one of the discrete sensitive regions and, in turn, is oriented to reflect converging radiation gathered from a sensitive region on the detector. The invention provides a simple, efficient optic system for a broad field of gathering infrared radiation, concentrating and focusing it in a manner to provide sufficient levels of received radiation for purposes of detection.
Description
3~;2 Field of the Invention This lnvention rela-tes to inErared intrusion detectors and more particularly to optical systems for such detectors.
Background oE the Invention In the field of passive types of infrared intrusion detectors, that is, detection being based upon receiving infrared radiation emitted by an intruder, several approaches have been taken to provide for reliable detection. It has been ;
very common to use various types of curved mirrors, particularly concavely curved mirrors, to gather infrared radiation and focus it directly onto an infrared radiation sensor. An e~ample of such mirror arrangement is shown in United States patent 3,703,718. In order to gain detection of a broad field and es-tablish several sensitive regions in that field, the curved mirror is made of various segments which receive radiation from various discrete, spaced-apart sensitive areas and directly reflect the radiation onto the sensor.
A similar type of mirror arrangement, in terms of segmenting the curved mirror portion of the reflector arrange-ment is shown is United States paten-t 3,886,360. In one of the embodiments, the mirror arrangement re~uires three reflections before the radia-tion is concentrated onto the infrared radiation sensor. ;~
Other types of multi-faceted mirrors for use in infrared radiation detectors are disclosed in United States patents 7 1i ~ . . , , ., ~ . .
5~ 2 3,923,382 and 3,972,598. The purpose of the mult:i-Eaceted curved mirror is to ga-ther radiation from several spaced-apart discrete fields o vlew and focus the radiation onto a single sensing element.
With mos-t in-trusion detectors, detection is based upon movement of the intruder through various sensi-tive regions such as described in United States patents RE. 29,082 and 4,052,716. In each instance, a concave mirror is used to directly reflect gathered radiation from a field of detection onto a detector which has an array of detection points to establish movement of the intruder across the field of detection.
Other approaches to establishing broad fields of detection, which may or may not employ optic lenses, is disclosed in United States patent 3,958,118. Movement of the intruder through the various fields of detection is needed in order to set off the alarm. In this particular instance, there is se~uential directing of radiation onto the group of detectors as the body passes through the field. Such movement of sensed radiation across the detector face sets off an alarm. ;
In most of the above arrangements, in order to provide a broad field of detection, the unit becomes relatively large and, in some instances, of little use other than in an industrial or military application. Further, in providing a broad field of sensitive areas in intrustion detection, most of the above systems require segmenting of the curved mirror which reduces the amount of radiation which can be gathered from any one sensitive region given the constraints on total system size.
It is, therefore, an object of this invention to provide a compact, infrared radiation intrusion detector which is economical to manufacture, useful in domestic, industrial military applications and has a relatively broad multiple field of detection.
Summary of the Invention The advantages of this invention are realized in an optical system for gathering infrared radiation from several discrete, spaced-apart sensitive regions and focusing it onto an infrared radiation sensor. The system comprises an optical collector for gathering infrared radiation from a space including such sensitive regions and for converging such radiation onto a plurality of reflectors. Each reflector determines a discrete, sensitive region and, in turn, is oriented to reflect the converging radiation gathered from a corresponding discrete sensitive region onto an infrared radiation sensor.
According to an aspect of the invention, the optical collector may be an optic lens or concavely curved mirror which converges the radiation onto an array of a plurality of reflectors. The reflector may be a planar mirror, which in ` ~ -determining a sensitive region, reflects infrared radiation from that region onto an infrared radiation sensor.
The compactness of the device is realized in the combined use of the optical collector/con~exger and plurality of reflectors, where the reflectors provide the discrete regions of sensitivity and the collectors determine the breadth of the field. The use of the reflectors permits positioni.ng of the sensor intermediate the optical collector and reflectors.
Brief Description of the Drawings Preferred embodiments of the inven-tion are shown in the drawings wherein: :
Figure 1 shows a preferred arrangement for an optical system adapted for use in an intrusion detector; .
Figure 2 is a top view of the optic system of Figure l;
1~ Figure 3 shows an alternative embodiment for the optic system for an infrared intrusion detector;
Figure 4 is a top view in section of the optic system of Figure 3;
Figure 5 shows in more detail the reflector array of the optic system; :
Fi~ure 6 shows an alternative embodiment for the optic system of the invention; and Figure 7 is a block diagram of detector monitor components.
Detailed Description of the Preferred Embodiments of the Invention ~;
5~
An optical system 10 adapted for use with an infrared intrusion detector is shown in Figure 1. An intruder 12 is shown in positions a and b which are sensitive or detection regions. The infrared radiation emitted from the body of the intruder propagates towards the optic system 10 along paths generally designated 14a and 14b. The optic system 10 ineludes an optical eollector 16 which converges the received radiation along path 18a onto an array of optical reflectors 20.
The array of optical reflectors is, in this instanee, made up of four planar mirrors 22, 24, 26 and 28. Eaeh of the reflectors is oriented differently to an adjaeent refleetor. Refleetor 24 determines the sensitive region where intruder 12a is and, in turn, is oriented to reflect along path 32a the eonverging radiation onto the infrared radiation deteetor 30.
Similarly although not shown, an intruder emitting radiation along path 34e is foeused onto the deteetor 30 by another optieal eolleetor 36 which converges the radiation onto the reflector array 20 along path 38c. In this instance, refleetor 28 reflects the converging radiation along path 40e onto the sensor 30.
The sensor 30 may be any type of suitable infrared sensor, sueh as pyro-eleetrie, thermopile or thermistor type. As appreeiated by those skilled in the art, the radiation to be sensed, in terms of intruders, varies roughly between ----~o~
7 and 15 microns. In particular, a human body emits infrared radiation peaked at a wavelength of approximately 9 microns.
The signal from -the sensor 30 is electronically processed and monitored in a manner to cause an alarm when the intensity of S the received radiation and the frequency or occurrence of the radiation level is such to correspond with that of an intruder.
As can be appreciated, the electronics, in terms of sensing are tuned to substan-tially reduce the generation of false alarms due to slow increases in radiation, such as room heating and the like. The electrical sensing of the radiation will be discussed in more detail with respect to the block diagram -of Figure 7.
Turning to Figure 2, the paths of radiation, as collected and reflected by the optic system 10, are shown where the intruder 12b is in position and a new position for an intruder 12d is shown. Due to the particular positioning of reflector 22, the infrared radiation from intruder 12b, as transmitted along a path 14b, is collected by curved mirror 16 and converged onto the reflecting surface 22. The focal point of mirror 16 is such that the reflected converying radiation along path 42b is focused onto the sensor portion 44 of detector 30.
The radius of curvature of the mirror 16 has been accentuated for purposes of illustration. It is appreciated, however, that the curvature of the mirror 16, should it be O~
spherical, would have a radius equal to twice the summation of the distances from mirror 16 to the planar mirror 22 and from mirror 22 to detector surface 44. Thus, -the focal point for the curved mirror 16 is proximate or exactly at receiver surface 49. As to intruder 12d, his radiation transmitted along path 46d is collected by mirror 36 and converged along path 48d onto mirror 26, which is arranged to reflect the converging radiation onto the receiver portion 44.
As demonstrated in Figures 1 and 2, the arrangement for the optical system is such that in collecting and reflecting the radiation onto the sensor 30, in no way does the position -of the sensor interfere with the transmission of the received ;
and focused radiation. As more clearly shown in Figure 1, the reflector array 20 is arranged such that it reflects the ra~iation slightly upwardly to converge on the sensor 30 as it is positioned somewhat above the array 20. This prevents the sensor 30 from interferring in any way with the radiation as converged onto the reflector by the gathering mirrors 16 and 36.
The array of reflectors 20, in combination with the collector optics, determines the number and location for `` -the de~ection areas in a particular field. It is apparent that, considering one side of the system, a single optic collector is provided to collect infrared radiation from all areas in a field which includes the regions to be sensed.
$
That radiation is converged towards the reflector arran~ement 20, where any radiatlon which does not land on one or more of the reflectors is, in turn, not focused onto the sensor device ~4, hence the establishment of the discrete, spaced-apart sensitive regions of detection. The mirror array 20 provides in a very simple manner a plurality of regions of detection, while relying on an easily constructed optic collector, such as spherical mirror or convex lens. The system also provides for adjusting the optic collector position or angle to select a desired space of detection which contains the discrete spaced-apart sensitive regions~
In considering both sides of the optic system 10, it is apparent that there is a set of reflectors in the array 20 for each radiation collector; i.e., reflectors (22, 24) and (26, 28) constitute the sets for collectors 16 and 36 respectively. For each set, a particular reflector is oriented differently from adjacent ones to thereby provide the regions of detection.
The reflector array 20 also provides the aspect of a ~ ~ ;
compact form of intrusion detector. As can be appreciated, without the reflectors~ the collector optics would require positioning of the sensor at its focal point which would be equidistant on the other side of array 20. Therefore, the reflector permits a close inverted positioning of the detector relative to radiation optic collectors. As can be ,, .: ... . .
appreciated, by providing the correct radius of curvature for the collectors, should it be spherical, the detector may be positioned approximately midway between the reflector array and the radiation collectors.
The size of the discrete, spaced-apart sensitive regions is dependent upon the shape of the receiving area ~ of the detector 30. According to a preferred embodiment of this invention, the shape of the detector opening 44 may be rectangular to provide at approximately 30 feet a sensitive or detector region of roughly one-half a foot wide by three-quarters of a foot high. In providing a higher than wider sensitive region, the detector is, therefore, less sensitive to vertical movement due to rising heat from a heater or the like.
It is also appreciated, of course, that inwardly of a distance of 30 feet, the sensitive regions get progressively smaller; however, this is satisfactory due to the fact that the closer the intruder is to the detector, the greater the intensity of radiation and the closer the spacing between sensitive regions.
The tilting of the reflector elements of the array 20, and in combination with positioning of the radiation collectors, provides various areas for detectionO In a room, for example, it may be desirable -to detect intruders along the floor~ along normal height and perhaps along certain portions of the ceiling . ~ ~ . . ~ . . .-, æ
where the~ may be skylights or the like which permit entry from above.
An arrangement, which is an extension of the device of Figure 2I permits detection of several areas by using only a single collection device, as shown in Figure 3. The radiation collection device, generally designated 50, is ring-shaped and has on its inner surface an annular con-tinuous concave reflector. Thus, the collector 50 may collect radiation from fields or a field all about the detector, regardless from where radiation enters. The reflector array S2 determines which portions in that field are set up as sensitive regions, where the reflector array, in this instance, has four reflecting surfaces, 54, 56, 5~ and 60q which divide the array into four quadrants, thus providing four sensitive regions which would be upper and lower and side-by-side. As shown in Figure 3, radiation transmitted along a path generally designated 62 enters from the bottom area of the field and is c~lected at the base of the collector 50 and converged along path 64 onto planar reflector 60 which, in turn, reflects the converging beam 66 onto the receiving area 44 of detector 30. Thus, in a simp]e, uncomplicated manner, sensitive areas may be established over several regions in a field to provide detection.
All the regions are predetermined not by collector 50, but instead by the reflector array 52 which, in this instance, consists of planar mirroxs and may be set up easily in various attitudes to establish the necessary regions of sensi-tivity.
~s shown in Figure 4, a section through the collector 50 shows where radiation, entering along path 68l is collected and converged onto reflector 58 and, in turn, focused on sensitive area 44 of cletector 30. Similarly, radiation entering along path 70 is reflected by surface 54 and converged on the detector surface 44 in the manner shown. With these arrangements as preferred for the optical system, it can be appreciated that there is now afforded a very flexible system in establishing sensitive regions for detection in a simple, economical manner. Depending upon the number and orientation of the reflector elements, a plurality of sensitive regions may be established and which may surround an area to be protected.
Turning to Figure 5, the reflector array 52 for the system is shown in more detail. ~adiation entering along the path 72, as collected by the collector, is reflected of~ the upper quadrant 60 and converges onto the detector 30.
Similarly, radiation entering from another direction along path 74, as converged by the collector 50, is reflected off surface 54 onto the detector. It can be appreciated that, with the array 52, the quadrants may be broken up into smaller segments to establish further sensitive regions about the upper, lower and side-by-side areas and may approach a polygonal-shaped peripheral field of detection.
The radiation collectors are such that they are able to ~s~æ ., collect radia-tion from a very broad field, which includes, of course, all of the sensitive regions as de termined by the reflector array. By using the shapes shown for the collectors or changing their shapes, it is appreciated that the system may be adapted for use in domestic, indust:rial and military situations.
The advantages of this invention, in terms of using a reflector array to establish a sensitive region can also be incorporated with optical collectors which employ a lens to concentrate or converge received radiation. As shown in Figure 6, a pair of convex lenses 76,78 converge received radiation along paths 80, 82 onto the reflector array 20 which has the individual elements 22, 24, 26 and 28. In this instance, lens 76 converges the radiation along path 84 onto mirror 28, which reflects it back to the -sens`itive area 44 of detector 30. Similarly lens 78 converges radiation along path 86 onto the reflector surfaces 24 which correspond to the sensitive region from which the radiation is emitted and, in turn, reflects it onto the detector 30.
As can be appreciated, various electronic arrangements may be employed which are connected to the detector 30 and which sound an alarm, or cause an alarm, when the relative degree of radiation has reached a predetermined level. The electronics may be such to sense movement through one or more of the sensitive regions. As shown in Figure 7, a block : - ;
diagram of the electronic components is shown. The detector 30 has its generated signal transmitted to a low noise difEerential amplifier 90 which amplifies the signal received Erom the detector 30. The amplified signal is transmitted to the active filter 92 which filters the amplified signal to pass the specified frequency corresponding to that which would be generated by an intruder entering one or more of the sensitive regions. The filtered siynal is fed to the comparator 94 where the amplitude of the signal is compared.
The comparator 94 generates a pulse which is fed to the delay timer 96 when the amplitude is above that preset in the comparator 94. The delay timer 96 delays transmission of the pulse to the logic circuit 98 for a prede-termined period of -time. The purpose of the delay is that, should the owner of the intrusion detector wish to turn it off, he is permitted ~`~
to enter the scanning region, locate the on/off controller 100 and turn the unit off. Therefore, the delay -time by the timer 96 is such to permit a person knowing the proper sequence to turn off the device before the alarm 102, comprising driver and horn, is set off by the logic circuit 98. The on/off control system 100 may be something more complicated that a simple on/off switch and which can only be operated by the owner of the device who would have the particular combination or know -the particular technique for turning off the unit.
~ g~ii3~
Although not shown, it is appreciated that other arrangementsmay be chosen ~or -the optic system in terms of the collector and reElectors. The collector devices, other than being lenses, may be in the form oE parabolic-shaped mirrorsor other curved shapes for mirrors which have the necessary curvature to provide a focal point at the sensor.
Also, the reflector arxay 20 may be made up of multi-~aceted planar arrays to determine the various sensitive regions.
The complexity of the array will be determined, of course, by its end use where for domestic purposes four sensitive regions would be suitable. The reflector arrays themselves may, if cost permits, be of a curved nature of individual facets to effect a further focusing of the converging radiation onto the detector, should a more compact arrangement be desired.
The optical system, according to this invention is, therefore, capable in a simple manner of gathering greater amounts of radiation over extended fields in a more compact arrangement compared to prior art deivces. The several areas of sensitive regions are dependent upon the number of mirrors involved in the reflector array, resu]ting in no need to segment or break up the optical collectors. Further, the reflector array, in combination with the collector optics, provides better infrared radiation gathering capabilities than existing prior art for such a compact device.
.
The radiation gatherincl capabilities oE this compact unit are sufficient to permit the use of a thermopile in the detection o intruders. Normally thermopiles require relatively high concentrations of radiation in order to properly function, whereas the more sensitive pyro-electric devices do not require as high a concentration of radiation. However, the thermopile devices are less expensive and, therefore, the optical system of this invention is more suited to the economic manufacture of an intrusion detector.
The reflector array also provides greater flexibility in design in terms of the capability of aading any number of desired sensitive regions. From a single collector surface, multiple regions may be established as determined by the number of facets in the reflector array.
To reduce the amount of energy losses in re~lection, the mirrors may be plated with a high reflectivity material.
For domestic application, it may be possible to plastic injection mold the bases for the mirrors and plate the plastic with highly reflective materials, such as gold-chromium.
Plating may be accomplished by electro-deposition or vacuum emission deposition.
Although various preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention of the scope of the appended claims.
Background oE the Invention In the field of passive types of infrared intrusion detectors, that is, detection being based upon receiving infrared radiation emitted by an intruder, several approaches have been taken to provide for reliable detection. It has been ;
very common to use various types of curved mirrors, particularly concavely curved mirrors, to gather infrared radiation and focus it directly onto an infrared radiation sensor. An e~ample of such mirror arrangement is shown in United States patent 3,703,718. In order to gain detection of a broad field and es-tablish several sensitive regions in that field, the curved mirror is made of various segments which receive radiation from various discrete, spaced-apart sensitive areas and directly reflect the radiation onto the sensor.
A similar type of mirror arrangement, in terms of segmenting the curved mirror portion of the reflector arrange-ment is shown is United States paten-t 3,886,360. In one of the embodiments, the mirror arrangement re~uires three reflections before the radia-tion is concentrated onto the infrared radiation sensor. ;~
Other types of multi-faceted mirrors for use in infrared radiation detectors are disclosed in United States patents 7 1i ~ . . , , ., ~ . .
5~ 2 3,923,382 and 3,972,598. The purpose of the mult:i-Eaceted curved mirror is to ga-ther radiation from several spaced-apart discrete fields o vlew and focus the radiation onto a single sensing element.
With mos-t in-trusion detectors, detection is based upon movement of the intruder through various sensi-tive regions such as described in United States patents RE. 29,082 and 4,052,716. In each instance, a concave mirror is used to directly reflect gathered radiation from a field of detection onto a detector which has an array of detection points to establish movement of the intruder across the field of detection.
Other approaches to establishing broad fields of detection, which may or may not employ optic lenses, is disclosed in United States patent 3,958,118. Movement of the intruder through the various fields of detection is needed in order to set off the alarm. In this particular instance, there is se~uential directing of radiation onto the group of detectors as the body passes through the field. Such movement of sensed radiation across the detector face sets off an alarm. ;
In most of the above arrangements, in order to provide a broad field of detection, the unit becomes relatively large and, in some instances, of little use other than in an industrial or military application. Further, in providing a broad field of sensitive areas in intrustion detection, most of the above systems require segmenting of the curved mirror which reduces the amount of radiation which can be gathered from any one sensitive region given the constraints on total system size.
It is, therefore, an object of this invention to provide a compact, infrared radiation intrusion detector which is economical to manufacture, useful in domestic, industrial military applications and has a relatively broad multiple field of detection.
Summary of the Invention The advantages of this invention are realized in an optical system for gathering infrared radiation from several discrete, spaced-apart sensitive regions and focusing it onto an infrared radiation sensor. The system comprises an optical collector for gathering infrared radiation from a space including such sensitive regions and for converging such radiation onto a plurality of reflectors. Each reflector determines a discrete, sensitive region and, in turn, is oriented to reflect the converging radiation gathered from a corresponding discrete sensitive region onto an infrared radiation sensor.
According to an aspect of the invention, the optical collector may be an optic lens or concavely curved mirror which converges the radiation onto an array of a plurality of reflectors. The reflector may be a planar mirror, which in ` ~ -determining a sensitive region, reflects infrared radiation from that region onto an infrared radiation sensor.
The compactness of the device is realized in the combined use of the optical collector/con~exger and plurality of reflectors, where the reflectors provide the discrete regions of sensitivity and the collectors determine the breadth of the field. The use of the reflectors permits positioni.ng of the sensor intermediate the optical collector and reflectors.
Brief Description of the Drawings Preferred embodiments of the inven-tion are shown in the drawings wherein: :
Figure 1 shows a preferred arrangement for an optical system adapted for use in an intrusion detector; .
Figure 2 is a top view of the optic system of Figure l;
1~ Figure 3 shows an alternative embodiment for the optic system for an infrared intrusion detector;
Figure 4 is a top view in section of the optic system of Figure 3;
Figure 5 shows in more detail the reflector array of the optic system; :
Fi~ure 6 shows an alternative embodiment for the optic system of the invention; and Figure 7 is a block diagram of detector monitor components.
Detailed Description of the Preferred Embodiments of the Invention ~;
5~
An optical system 10 adapted for use with an infrared intrusion detector is shown in Figure 1. An intruder 12 is shown in positions a and b which are sensitive or detection regions. The infrared radiation emitted from the body of the intruder propagates towards the optic system 10 along paths generally designated 14a and 14b. The optic system 10 ineludes an optical eollector 16 which converges the received radiation along path 18a onto an array of optical reflectors 20.
The array of optical reflectors is, in this instanee, made up of four planar mirrors 22, 24, 26 and 28. Eaeh of the reflectors is oriented differently to an adjaeent refleetor. Refleetor 24 determines the sensitive region where intruder 12a is and, in turn, is oriented to reflect along path 32a the eonverging radiation onto the infrared radiation deteetor 30.
Similarly although not shown, an intruder emitting radiation along path 34e is foeused onto the deteetor 30 by another optieal eolleetor 36 which converges the radiation onto the reflector array 20 along path 38c. In this instance, refleetor 28 reflects the converging radiation along path 40e onto the sensor 30.
The sensor 30 may be any type of suitable infrared sensor, sueh as pyro-eleetrie, thermopile or thermistor type. As appreeiated by those skilled in the art, the radiation to be sensed, in terms of intruders, varies roughly between ----~o~
7 and 15 microns. In particular, a human body emits infrared radiation peaked at a wavelength of approximately 9 microns.
The signal from -the sensor 30 is electronically processed and monitored in a manner to cause an alarm when the intensity of S the received radiation and the frequency or occurrence of the radiation level is such to correspond with that of an intruder.
As can be appreciated, the electronics, in terms of sensing are tuned to substan-tially reduce the generation of false alarms due to slow increases in radiation, such as room heating and the like. The electrical sensing of the radiation will be discussed in more detail with respect to the block diagram -of Figure 7.
Turning to Figure 2, the paths of radiation, as collected and reflected by the optic system 10, are shown where the intruder 12b is in position and a new position for an intruder 12d is shown. Due to the particular positioning of reflector 22, the infrared radiation from intruder 12b, as transmitted along a path 14b, is collected by curved mirror 16 and converged onto the reflecting surface 22. The focal point of mirror 16 is such that the reflected converying radiation along path 42b is focused onto the sensor portion 44 of detector 30.
The radius of curvature of the mirror 16 has been accentuated for purposes of illustration. It is appreciated, however, that the curvature of the mirror 16, should it be O~
spherical, would have a radius equal to twice the summation of the distances from mirror 16 to the planar mirror 22 and from mirror 22 to detector surface 44. Thus, -the focal point for the curved mirror 16 is proximate or exactly at receiver surface 49. As to intruder 12d, his radiation transmitted along path 46d is collected by mirror 36 and converged along path 48d onto mirror 26, which is arranged to reflect the converging radiation onto the receiver portion 44.
As demonstrated in Figures 1 and 2, the arrangement for the optical system is such that in collecting and reflecting the radiation onto the sensor 30, in no way does the position -of the sensor interfere with the transmission of the received ;
and focused radiation. As more clearly shown in Figure 1, the reflector array 20 is arranged such that it reflects the ra~iation slightly upwardly to converge on the sensor 30 as it is positioned somewhat above the array 20. This prevents the sensor 30 from interferring in any way with the radiation as converged onto the reflector by the gathering mirrors 16 and 36.
The array of reflectors 20, in combination with the collector optics, determines the number and location for `` -the de~ection areas in a particular field. It is apparent that, considering one side of the system, a single optic collector is provided to collect infrared radiation from all areas in a field which includes the regions to be sensed.
$
That radiation is converged towards the reflector arran~ement 20, where any radiatlon which does not land on one or more of the reflectors is, in turn, not focused onto the sensor device ~4, hence the establishment of the discrete, spaced-apart sensitive regions of detection. The mirror array 20 provides in a very simple manner a plurality of regions of detection, while relying on an easily constructed optic collector, such as spherical mirror or convex lens. The system also provides for adjusting the optic collector position or angle to select a desired space of detection which contains the discrete spaced-apart sensitive regions~
In considering both sides of the optic system 10, it is apparent that there is a set of reflectors in the array 20 for each radiation collector; i.e., reflectors (22, 24) and (26, 28) constitute the sets for collectors 16 and 36 respectively. For each set, a particular reflector is oriented differently from adjacent ones to thereby provide the regions of detection.
The reflector array 20 also provides the aspect of a ~ ~ ;
compact form of intrusion detector. As can be appreciated, without the reflectors~ the collector optics would require positioning of the sensor at its focal point which would be equidistant on the other side of array 20. Therefore, the reflector permits a close inverted positioning of the detector relative to radiation optic collectors. As can be ,, .: ... . .
appreciated, by providing the correct radius of curvature for the collectors, should it be spherical, the detector may be positioned approximately midway between the reflector array and the radiation collectors.
The size of the discrete, spaced-apart sensitive regions is dependent upon the shape of the receiving area ~ of the detector 30. According to a preferred embodiment of this invention, the shape of the detector opening 44 may be rectangular to provide at approximately 30 feet a sensitive or detector region of roughly one-half a foot wide by three-quarters of a foot high. In providing a higher than wider sensitive region, the detector is, therefore, less sensitive to vertical movement due to rising heat from a heater or the like.
It is also appreciated, of course, that inwardly of a distance of 30 feet, the sensitive regions get progressively smaller; however, this is satisfactory due to the fact that the closer the intruder is to the detector, the greater the intensity of radiation and the closer the spacing between sensitive regions.
The tilting of the reflector elements of the array 20, and in combination with positioning of the radiation collectors, provides various areas for detectionO In a room, for example, it may be desirable -to detect intruders along the floor~ along normal height and perhaps along certain portions of the ceiling . ~ ~ . . ~ . . .-, æ
where the~ may be skylights or the like which permit entry from above.
An arrangement, which is an extension of the device of Figure 2I permits detection of several areas by using only a single collection device, as shown in Figure 3. The radiation collection device, generally designated 50, is ring-shaped and has on its inner surface an annular con-tinuous concave reflector. Thus, the collector 50 may collect radiation from fields or a field all about the detector, regardless from where radiation enters. The reflector array S2 determines which portions in that field are set up as sensitive regions, where the reflector array, in this instance, has four reflecting surfaces, 54, 56, 5~ and 60q which divide the array into four quadrants, thus providing four sensitive regions which would be upper and lower and side-by-side. As shown in Figure 3, radiation transmitted along a path generally designated 62 enters from the bottom area of the field and is c~lected at the base of the collector 50 and converged along path 64 onto planar reflector 60 which, in turn, reflects the converging beam 66 onto the receiving area 44 of detector 30. Thus, in a simp]e, uncomplicated manner, sensitive areas may be established over several regions in a field to provide detection.
All the regions are predetermined not by collector 50, but instead by the reflector array 52 which, in this instance, consists of planar mirroxs and may be set up easily in various attitudes to establish the necessary regions of sensi-tivity.
~s shown in Figure 4, a section through the collector 50 shows where radiation, entering along path 68l is collected and converged onto reflector 58 and, in turn, focused on sensitive area 44 of cletector 30. Similarly, radiation entering along path 70 is reflected by surface 54 and converged on the detector surface 44 in the manner shown. With these arrangements as preferred for the optical system, it can be appreciated that there is now afforded a very flexible system in establishing sensitive regions for detection in a simple, economical manner. Depending upon the number and orientation of the reflector elements, a plurality of sensitive regions may be established and which may surround an area to be protected.
Turning to Figure 5, the reflector array 52 for the system is shown in more detail. ~adiation entering along the path 72, as collected by the collector, is reflected of~ the upper quadrant 60 and converges onto the detector 30.
Similarly, radiation entering from another direction along path 74, as converged by the collector 50, is reflected off surface 54 onto the detector. It can be appreciated that, with the array 52, the quadrants may be broken up into smaller segments to establish further sensitive regions about the upper, lower and side-by-side areas and may approach a polygonal-shaped peripheral field of detection.
The radiation collectors are such that they are able to ~s~æ ., collect radia-tion from a very broad field, which includes, of course, all of the sensitive regions as de termined by the reflector array. By using the shapes shown for the collectors or changing their shapes, it is appreciated that the system may be adapted for use in domestic, indust:rial and military situations.
The advantages of this invention, in terms of using a reflector array to establish a sensitive region can also be incorporated with optical collectors which employ a lens to concentrate or converge received radiation. As shown in Figure 6, a pair of convex lenses 76,78 converge received radiation along paths 80, 82 onto the reflector array 20 which has the individual elements 22, 24, 26 and 28. In this instance, lens 76 converges the radiation along path 84 onto mirror 28, which reflects it back to the -sens`itive area 44 of detector 30. Similarly lens 78 converges radiation along path 86 onto the reflector surfaces 24 which correspond to the sensitive region from which the radiation is emitted and, in turn, reflects it onto the detector 30.
As can be appreciated, various electronic arrangements may be employed which are connected to the detector 30 and which sound an alarm, or cause an alarm, when the relative degree of radiation has reached a predetermined level. The electronics may be such to sense movement through one or more of the sensitive regions. As shown in Figure 7, a block : - ;
diagram of the electronic components is shown. The detector 30 has its generated signal transmitted to a low noise difEerential amplifier 90 which amplifies the signal received Erom the detector 30. The amplified signal is transmitted to the active filter 92 which filters the amplified signal to pass the specified frequency corresponding to that which would be generated by an intruder entering one or more of the sensitive regions. The filtered siynal is fed to the comparator 94 where the amplitude of the signal is compared.
The comparator 94 generates a pulse which is fed to the delay timer 96 when the amplitude is above that preset in the comparator 94. The delay timer 96 delays transmission of the pulse to the logic circuit 98 for a prede-termined period of -time. The purpose of the delay is that, should the owner of the intrusion detector wish to turn it off, he is permitted ~`~
to enter the scanning region, locate the on/off controller 100 and turn the unit off. Therefore, the delay -time by the timer 96 is such to permit a person knowing the proper sequence to turn off the device before the alarm 102, comprising driver and horn, is set off by the logic circuit 98. The on/off control system 100 may be something more complicated that a simple on/off switch and which can only be operated by the owner of the device who would have the particular combination or know -the particular technique for turning off the unit.
~ g~ii3~
Although not shown, it is appreciated that other arrangementsmay be chosen ~or -the optic system in terms of the collector and reElectors. The collector devices, other than being lenses, may be in the form oE parabolic-shaped mirrorsor other curved shapes for mirrors which have the necessary curvature to provide a focal point at the sensor.
Also, the reflector arxay 20 may be made up of multi-~aceted planar arrays to determine the various sensitive regions.
The complexity of the array will be determined, of course, by its end use where for domestic purposes four sensitive regions would be suitable. The reflector arrays themselves may, if cost permits, be of a curved nature of individual facets to effect a further focusing of the converging radiation onto the detector, should a more compact arrangement be desired.
The optical system, according to this invention is, therefore, capable in a simple manner of gathering greater amounts of radiation over extended fields in a more compact arrangement compared to prior art deivces. The several areas of sensitive regions are dependent upon the number of mirrors involved in the reflector array, resu]ting in no need to segment or break up the optical collectors. Further, the reflector array, in combination with the collector optics, provides better infrared radiation gathering capabilities than existing prior art for such a compact device.
.
The radiation gatherincl capabilities oE this compact unit are sufficient to permit the use of a thermopile in the detection o intruders. Normally thermopiles require relatively high concentrations of radiation in order to properly function, whereas the more sensitive pyro-electric devices do not require as high a concentration of radiation. However, the thermopile devices are less expensive and, therefore, the optical system of this invention is more suited to the economic manufacture of an intrusion detector.
The reflector array also provides greater flexibility in design in terms of the capability of aading any number of desired sensitive regions. From a single collector surface, multiple regions may be established as determined by the number of facets in the reflector array.
To reduce the amount of energy losses in re~lection, the mirrors may be plated with a high reflectivity material.
For domestic application, it may be possible to plastic injection mold the bases for the mirrors and plate the plastic with highly reflective materials, such as gold-chromium.
Plating may be accomplished by electro-deposition or vacuum emission deposition.
Although various preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention of the scope of the appended claims.
Claims (21)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an infrared intrusion detector, an optical device to direct gathered infrared radiation from several discrete, spaced-apart sensitive regions onto an infrared radiation sensor, said device comprising an optical collector for gathering infrared radiation from a space including such sensitive regions and for converging such radiation from a space onto a plurality of reflectors corresponding in number to the number of sensitive regions where each reflector determines a discrete sensitive region and, in turn, is oriented to reflect converging radiation from a corresponding discrete sensitive region into said infrared radiation sensor.
2. In an infrared intrusion detector of claim 1, said optical collector being a concave mirror.
3. In an infrared intrusion detector of claim 1, said optical collector being a convex lens.
4. In an infrared intrusion detector of claim 1, each reflector being a planar mirror oriented differently from adjacent planar mirrors to thereby determine said discrete, spaced-apart sensitive regions.
5. In an infrared intrusion detector of claim 1, said optical collector having a focal point for reflected converging radiation between said optical collector and said plurality of of reflectors, an infrared radiation sensor being positionable proximate said focal point.
6. In an infrared intrusion detector of claim 4, said optical collector in combination with said plurality of reflectors converging radiation to a point located between them, where a radiation sensor is positionable.
7. In an infrared intrusion detector of claim 5 or 6, said reflectors being oriented to permit locating said sensor in a position which is non-inteferring with converging beams of radiation
8. In an infrared intrusion detector of claim 1, a spaced-apart pair of said optical collectors, each to a side of an infrared radiation detector, sets of plurality of reflectors, each set associated with an optical collector to reflect converging radiation from corresponding discrete sensitive regions corresponding in number to the number of reflectors in each set onto said infrared radiation detector.
9. In an infrared intrusion detector of claim 8, each optical collector being a concave mirror.
10. In an infrared intrusion detector of claim 9, said concave mirror being a spherical mirror.
11. In an infrared intrusion detector of claim 1, said optical collector being a ring having an annular reflective concave surface, said plurality of reflectors being positioned in quadrants to define discrete sensitive regions in ach of four areas.
12. In an infrared intrusion detector of claim 11, a planar mirror positioned in each quadrant for the reflector arrangement.
13. In an infrared intrusion detector of claim 11, said reflectors being arranged to define sensitive regions in upper and lower areas and side-by-side areas.
14. System of mirrors adapted for use with an infrared intrusion detector having an infrared radiation sensor, said mirror system receiving infrared radiation from several discrete, spaced-apart detection regions and focusing such received radiation onto an infrared sensor, said mirror system comprising a concavely curved mirror for receiving infrared radiation from an area which includes such regions of detection, and converging such received radiation from such area onto an array of planar mirrors, each planar mirror providing a predetermined discrete detection region as radiation is converged towards the array of mirrors, said planar mirror being positioned to reflect radiation received from a corresponding detection region onto an infrared radiation sensor, said concavely curved mirror having a focal point proximate the receiving portion of an infrared radiation sensor.
15. A system of claim 14, wherein said concavely curved mirror is a spherical mirror having a radius of curvature equal to double the distance the radition travels in reflection from spherical mirror to planar mirror to sensor.
16. A system of claim 14, wherein each planar mirror is oreiented differently from adjacent planar mirrors to thereby define such discrete, spaced-apart detection regions.
17. A system of claim 14, wherein there is a pair of spaced-apart concavely curved mirrors, each being offset relative to an infrared radiation detector, sets of a plurality of planar mirrors in the array, each set associated with a corresponding curved mirror to reflect focused radiation received from a corresponding discrete detection region onto an infrared radiation detector.
18. A system of claim 17, wherein each concave mirror is a spherical mirror.
19. A system of claim 14, wherein said concavely curved mirror is a ring having an annular reflective concave surface, said array of planar mirrors being positioned in quadrants to define discrete detection regions in each of four areas.
20. A system of claim 19, wherein a planar mirror is positioned in each quadrant of the array.
21. A system of claim 19, wherein said array of planar mirrors is arranged to define sensitive regions in upper and lower areas and side-by-side areas of the space in which intrusion is to be detected.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,480A CA1095302A (en) | 1979-06-11 | 1979-06-11 | Optics for infrared intrusion detector |
| EP80301819A EP0021630A3 (en) | 1979-06-11 | 1980-06-02 | Infrared intrusion detector and optical system for such a detector |
| JP7830080A JPS562091A (en) | 1979-06-11 | 1980-06-10 | Infrared ray invador detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,480A CA1095302A (en) | 1979-06-11 | 1979-06-11 | Optics for infrared intrusion detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1095302A true CA1095302A (en) | 1981-02-10 |
Family
ID=4114409
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA329,480A Expired CA1095302A (en) | 1979-06-11 | 1979-06-11 | Optics for infrared intrusion detector |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0021630A3 (en) |
| JP (1) | JPS562091A (en) |
| CA (1) | CA1095302A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0001879B2 (en) * | 1977-09-07 | 1989-11-23 | Imperial Chemical Industries Plc | Thermoplastic aromatic polyetherketones, a method for their preparation and their application as electrical insulants |
| CH650604A5 (en) * | 1980-10-24 | 1985-07-31 | Cerberus Ag | OPTICAL ARRANGEMENT FOR AN INFRARED BURGLAR DETECTOR. |
| SE446505B (en) * | 1982-11-16 | 1986-09-22 | Gambro Dialysatoren | MEMBRANE AND WAY TO MAKE THIS |
| KR101887054B1 (en) * | 2012-03-23 | 2018-08-09 | 삼성전자주식회사 | Infrared ray detecting device and heating cooker including the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2734157A1 (en) * | 1958-02-22 | 1979-02-01 | Heimann Gmbh | PASSIVE INFRARED ALARM |
| US3886360A (en) * | 1973-09-04 | 1975-05-27 | Gulf & Western Mfg Co | Infrared intrusion detection apparatus |
-
1979
- 1979-06-11 CA CA329,480A patent/CA1095302A/en not_active Expired
-
1980
- 1980-06-02 EP EP80301819A patent/EP0021630A3/en not_active Ceased
- 1980-06-10 JP JP7830080A patent/JPS562091A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0021630A2 (en) | 1981-01-07 |
| JPS562091A (en) | 1981-01-10 |
| EP0021630A3 (en) | 1981-01-21 |
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