CA1119269A - Smoke detector with test means for simulating a pre-determined percentage of smoke - Google Patents
Smoke detector with test means for simulating a pre-determined percentage of smokeInfo
- Publication number
- CA1119269A CA1119269A CA000317076A CA317076A CA1119269A CA 1119269 A CA1119269 A CA 1119269A CA 000317076 A CA000317076 A CA 000317076A CA 317076 A CA317076 A CA 317076A CA 1119269 A CA1119269 A CA 1119269A
- Authority
- CA
- Canada
- Prior art keywords
- light
- photo
- light beam
- plate
- smoke
- 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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4785—Standardising light scatter apparatus; Standards therefor
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
- G08B17/113—Constructional details
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Emergency Management (AREA)
- Business, Economics & Management (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Fire-Detection Mechanisms (AREA)
Abstract
ABSTRACT
A smoke detector of the photo-electric type having a photo-responsive device viewing a volume illuminated by a light beam, in which a test member is provided for being temporarily positioned in the light beam so that one side of said member is exposed to the light and the other side is in the view of the photo-responsive device.
The last member has a light-transimtting area which is small in relation to the cross-sectional area of the light beam. In one embodiment of the invention the light-transmitting area is thin enough to be translucent, so that the translucent area illuminated by the beam simulates a predetermined percentage of smoke in the beam with a high degree of accuracy, since the transmission characteristics of the translucent area can be consistently maintained within production telerances, and the exact position of the translucent area in the light beam for the smoke simulation is not cri?.
In another embodiment of the invention, a small hole is provided is the test member to pass a predetermined amount of light from one side of the thin area to the other.
A smoke detector of the photo-electric type having a photo-responsive device viewing a volume illuminated by a light beam, in which a test member is provided for being temporarily positioned in the light beam so that one side of said member is exposed to the light and the other side is in the view of the photo-responsive device.
The last member has a light-transimtting area which is small in relation to the cross-sectional area of the light beam. In one embodiment of the invention the light-transmitting area is thin enough to be translucent, so that the translucent area illuminated by the beam simulates a predetermined percentage of smoke in the beam with a high degree of accuracy, since the transmission characteristics of the translucent area can be consistently maintained within production telerances, and the exact position of the translucent area in the light beam for the smoke simulation is not cri?.
In another embodiment of the invention, a small hole is provided is the test member to pass a predetermined amount of light from one side of the thin area to the other.
Description
1119Zf~9 BACKGRO~D OF THE rNVENTION
17 Smoke detectors of the photo-electric type utilize a focused light beam 18 passing through a volume which receives smoke from the ambient atmosphere, with ¦
l9 a photo-responsive device viewing the light beam at an angle to the axis thereof, so that smoke particles illuminated by the beam are seen by the 21 photo-responsive device.
22 Such detectors are calibrated to provide an alarm when the concentration 23 of smoke in the light beam reaches a predetermined level. Cer-tain organizations 24 that test and approve smoke detectors require that means be provided whereby the user of the detector can test the operability thereof, by simulating the 26 s~ount smoke to whioh the detector is req~ired to respond.
1 Various methods have been proposed to providc such tegt means. However,
17 Smoke detectors of the photo-electric type utilize a focused light beam 18 passing through a volume which receives smoke from the ambient atmosphere, with ¦
l9 a photo-responsive device viewing the light beam at an angle to the axis thereof, so that smoke particles illuminated by the beam are seen by the 21 photo-responsive device.
22 Such detectors are calibrated to provide an alarm when the concentration 23 of smoke in the light beam reaches a predetermined level. Cer-tain organizations 24 that test and approve smoke detectors require that means be provided whereby the user of the detector can test the operability thereof, by simulating the 26 s~ount smoke to whioh the detector is req~ired to respond.
1 Various methods have been proposed to providc such tegt means. However,
2 it has been fol~d difficult to provide a method which will ~ive consistent
3 results in a smoke detector manufactured in great quantity because of the difficulty of holding accurate tolerances in the mechanical componcnts.
Methods nsed heretofore depend on light reflected or scattered from an object, 6 such as a wire~ inserted into the light bea~. However~ the amount of light 7 scattered onto the cell depends on the size of the wire~ the surf~ce finish 8 thereof~ and its position in the light beam. The diameter of the wire required 9 to provide the small amount of light re~uired is very small, and is therefore susceptible to damage in handling during manufacture or damage in use by the 11 user .
SUMMA~Y OF T~E INVENTION
12 This invention provides a smoke detector with a test member and means for 13 positioning the test member in the light beam 80 that one side thereof is 14 illnminated by the light source and the other side thereof is in the view of the photo-responsive device. In one embodiment of the inventiwl a portion of 16 the test member at or near the front edge thereof is sufficiently thin to be 17 translucentl said translucent portion being small in area in relation to the 18 cross-sectional area of the portion of the light beam into which it is inserted.
19 In another embodiment of the invention~ a small hole is provided in the 20 test member so that a predetermined amount of light passes through the test 21 member when the test member is moved into the light beam.
22 In one embodiment of the invention, the test member is in the form of a 23 plate positioned in a slot in the housing contsining the light source and photo-24 cell~ and an external lever is provided to move the test plate out of the slot 90 that the leading edge of the test member enters the light beam. The light-26 transmitting portion is so disposed on the test member so as to be centrally 27 disposed both in the light beam and in the field of view of the photo-cell when 28 moved into the test position.
1119Z~g Hence, when the test member is projected forwardly into the light beam, the amount of illumination passing through the test member and seen by the photocell will be consistent from one detector to another so long as the light-transmitting portion of the test member is positioned within about the center one quarter of the light beam. The dimensional tolerances of the mechanical components necessary to position the test member in the test position are there-fore not restrictive.
In accordance with a particular embodiment of the invention there is provided, in a smoke detector of the photo-electric type which includes a light source providing a light beam and photo-responsive means viewing transversely a portion of the light beam, the improvement comprising test means for simulating a predetermined smoke concentration, said means comprising a substantially opaque plate and means for temporarily positioning the plate in the light beam between the light source and the photo-responsive device so that the plate is illuminated on one side by the light beam and the other side is viewed by the photo-responsive device, said plate having a light-transmitting portion, said light trans-mitting portion allowing a predetermined amount of light to pass therethrough when the plate i9 SO positioned in the light beam.
BRIEF DESCRIPTIO~ OF THE DRAWI~GS
Fig. 1 is a top plan view, partly broken away, showing a housing for the optical components of a smoke detector with the cover removed~
Fig. 2 is a view of the housing of Fig. 1 as seen from the front, with the cover in place.
Fig. 3 is a view in section taken on line 3-3 - of Fig. 2, with the test member in the normal retracted ~ position.
1~192~;9 Fig. 4 is a view similar to Fig. 3 in which the test member is in the forward or test position.
Fig. 5 is a top plan view of Fig. 4.
Fig. 6 is an enlarged view of the test member as seen in Fig. 4.
Fig. 7 is a view in section taken on line 7-7 of Fig. 6.
Fig. 8 is a view similar to Fig. 6, illustrating a modified form of test member.
Fig. 9 is a view taken on line 9-9 of Fig. 8.
Fig. 10 is a view similar to Fig. 6 illustrating another modified form of test member.
Fig. 11 is a vi~w taken on line 11-11 of Fig. 10.
D - 3a -lllsa6s DESCRIPTION OF T~E ILI,USTRATEV E~OD~1EN~
1 Referring to the drawing, thcre is illllstrated a llousing 10 for use in a 2 smoke dciector of t}~lC photo-electric type. The llollsillg is preferably formed of 3 injection molAed plastic and comprises a body 12 comprising a ba9e 1IL, a back
Methods nsed heretofore depend on light reflected or scattered from an object, 6 such as a wire~ inserted into the light bea~. However~ the amount of light 7 scattered onto the cell depends on the size of the wire~ the surf~ce finish 8 thereof~ and its position in the light beam. The diameter of the wire required 9 to provide the small amount of light re~uired is very small, and is therefore susceptible to damage in handling during manufacture or damage in use by the 11 user .
SUMMA~Y OF T~E INVENTION
12 This invention provides a smoke detector with a test member and means for 13 positioning the test member in the light beam 80 that one side thereof is 14 illnminated by the light source and the other side thereof is in the view of the photo-responsive device. In one embodiment of the inventiwl a portion of 16 the test member at or near the front edge thereof is sufficiently thin to be 17 translucentl said translucent portion being small in area in relation to the 18 cross-sectional area of the portion of the light beam into which it is inserted.
19 In another embodiment of the invention~ a small hole is provided in the 20 test member so that a predetermined amount of light passes through the test 21 member when the test member is moved into the light beam.
22 In one embodiment of the invention, the test member is in the form of a 23 plate positioned in a slot in the housing contsining the light source and photo-24 cell~ and an external lever is provided to move the test plate out of the slot 90 that the leading edge of the test member enters the light beam. The light-26 transmitting portion is so disposed on the test member so as to be centrally 27 disposed both in the light beam and in the field of view of the photo-cell when 28 moved into the test position.
1119Z~g Hence, when the test member is projected forwardly into the light beam, the amount of illumination passing through the test member and seen by the photocell will be consistent from one detector to another so long as the light-transmitting portion of the test member is positioned within about the center one quarter of the light beam. The dimensional tolerances of the mechanical components necessary to position the test member in the test position are there-fore not restrictive.
In accordance with a particular embodiment of the invention there is provided, in a smoke detector of the photo-electric type which includes a light source providing a light beam and photo-responsive means viewing transversely a portion of the light beam, the improvement comprising test means for simulating a predetermined smoke concentration, said means comprising a substantially opaque plate and means for temporarily positioning the plate in the light beam between the light source and the photo-responsive device so that the plate is illuminated on one side by the light beam and the other side is viewed by the photo-responsive device, said plate having a light-transmitting portion, said light trans-mitting portion allowing a predetermined amount of light to pass therethrough when the plate i9 SO positioned in the light beam.
BRIEF DESCRIPTIO~ OF THE DRAWI~GS
Fig. 1 is a top plan view, partly broken away, showing a housing for the optical components of a smoke detector with the cover removed~
Fig. 2 is a view of the housing of Fig. 1 as seen from the front, with the cover in place.
Fig. 3 is a view in section taken on line 3-3 - of Fig. 2, with the test member in the normal retracted ~ position.
1~192~;9 Fig. 4 is a view similar to Fig. 3 in which the test member is in the forward or test position.
Fig. 5 is a top plan view of Fig. 4.
Fig. 6 is an enlarged view of the test member as seen in Fig. 4.
Fig. 7 is a view in section taken on line 7-7 of Fig. 6.
Fig. 8 is a view similar to Fig. 6, illustrating a modified form of test member.
Fig. 9 is a view taken on line 9-9 of Fig. 8.
Fig. 10 is a view similar to Fig. 6 illustrating another modified form of test member.
Fig. 11 is a vi~w taken on line 11-11 of Fig. 10.
D - 3a -lllsa6s DESCRIPTION OF T~E ILI,USTRATEV E~OD~1EN~
1 Referring to the drawing, thcre is illllstrated a llousing 10 for use in a 2 smoke dciector of t}~lC photo-electric type. The llollsillg is preferably formed of 3 injection molAed plastic and comprises a body 12 comprising a ba9e 1IL, a back
4 wall 16, end walls 18, front wall portions 20 and a pair of up~t~ding members 22 medially disposed between the ends of the front wall portions, forming ~ openings 24 and 26. The upstanding members 22 are spaced apart fo~ng a 7 slot 28.
8 Other upwardly extending members are provided in the housing to form 9 suitably shaped cavities 30 and 32 to receive a light source 34 and a photo-responsive device 36, with associated focusing lenses 38 and 40.
11 The cavitieg 30 and 32 are shaped and dimensioned to retain the light 12 source and photo-responsive device in a position and orientation such t~at the 13 light beam from the source projects out of the opening 26 at an angle of about 14 22~- from the longitudinal axis of the housing and the viewing axis of the photo-responsive device extends out of the opening 24 also at an angle of 16 about 222 to the axis of the housing, so that thc vicwing axis of tbe photo-17 responsive device intersects the axis of the light beam in front of the medial 18 portion of the housing at a point A ~ig. 5) at an angle of about 135 to take 19 advantage of the well-known "forward scatter" effect. The intersection of the viewing cone of the photo-cell and the cone of the light beam is illustrated 21 by the shaded area V.
22 The light source and photo-responsive device may be connected into suitable 23 circuitry (not shown), by which the light source is energi~ed in a desired 24 manner, and light reflected onto the photo-responsive device irom smoke particles in the light beam cause a response of said photo-responsive device 26 that actuates an alarm.
27 Examples of such circuitry may be found in U.S. patents 3,946,241 issued 28 March 23, 1976~ 3,917,956 issued November 4? 1975, and patent 4,125~779 issued 29 November 14, 1978.
_4_ 1~
.9269 1 The viewing area of the photo-cell may be surrounded by a suitable 2 enclosure 41 having internal light absorbing baffles 43, said enclosure having 3 suitable apertures (not shown) to freely admit ambient atmosphere.
~ A cover plate 42 is provided for the housing~ said plate being providedwith an aperture 44 in the medial portion of the front edge and a pair of 6 support arms 46 extending upwardly on opposite sides of the aperture, each 7 leg having an inwardly extending pin ~8 near the upper end thereof.
8 Assembled with the cover is a test lever 50, comprising a medial portion 9 having a pair of recesses 52 on opposite sides thereof receiving the pins 48so that the lever is movable on said pins as an axis. Depending from the 11 medial portion is a test plate 54 which is disposed in the slot 28 of the 12 housing, and extending upwardly and rearwardly therefrom is an operating member 13 56. Extending rearwardly from the lever 50 is an integral plastic leaf spIing 14 58, which, when the lever and cover are assembled with the housing, rests on a spring support 60 on the rear of the housing, so that the lever is biased 16 clockwise (as seen in Fig. 3) retaining the test plate 54 retracted into the17 slot 28.
18 The test plate 54 is moved to the test position by depressing the operating 19 member 56~ thereby pivoting the lever 50 counter-clockwise (Fig. 1~) and flexing the spring 58.
21 To limit the pivotine movement of the lever~ so that when the operating22 member is depressed a predetermined portion of the test plate stops substantiall 23 at the center of the light beam~ stop member 61 is provided on the cover, 24 positioned to contact the operating member 56 and limit the downward movement thereof.
26 In the embodiment of Figs. 6 and 7~ the leading portion of the test plate 27 has an area 62 which is thin in relation to rest of the mcmbcr, said arca bcing 28 substantially smaller than that of the light beam at the intersection of the29 light beam and the field of view of the photo-cell. When the test plate is ll~,9Z69 1 moved forwardly into t~e light beam, one side thereof is i~ minatPd by the 2 light beam, and the other side is viewed by the photo-responsive dcvicc. In 3 a preferred cmbodiment of the invention the housing lO and the lever 50 are Il formed of black plastic, to absorb stray radiation and to mini~i~e the transmission of light through the test plate 54.
6 ~owever, it has been fol~d that if the area 62 of the test plate is made 7 thin enough, sufficient light is transmitted therethrough and seen by the 8 photo-responsive device to simulate the reqllired ~lolmt of smoke and actuate 9 the alarm.
The amount of light passing through the thin area 62 of the test plate for 11 a given plastic composition, is a function of the thickness of said thin area 12 and the area thereof. For a detector housing of given size and composition, 13 and with a known amount of smoke to be simulated, the area and thickness that 14 will simulate a required amount of smoke can easily be dete~ined by experiment.
In the accompanying drawing, the thickness of the portion 62 as shown in 16 Fig. 7 is not intended to be a representation of the actual thickness necessary 17 for the desired result. ~
18 Although in the embodiment of Figs. 6 and 7 the translucent portion is 19 provided near the leading edge of the test plate, it will be understood that the thin translucent portion could be in a central portion of the test plate, and 21 means provided ~or projecting the test plate further into or completely across 22 the light beam so that the thin translucent portion is centered in the light 23 beam.
24 Referring to Figs. 8 and 9, there is illustrated a modified form of test plate 54a which is similar to test plate 54, with the e~ception that the 26 portion 62a need not be so thin as to be translucent~ and a small aperture 6l~
27 is provided in the portion 62a to allow a predetermined amount of light to pass 28 therethrough, The aperture 6~ may be 80 positioned in thé portion 62a as to be 29 substantially centrally located in the light beam when the test plate is in the 3o test position.
1 Although in the embodiment o~ Figs. 8 and 9, the aperture 6!l is positioned ¦
2 in a thin portion 62a, it will be undcrstood that if desired the plate may be 3 of uniform thickness with the aperture suitably positioned in the plate.
4 ~owever~ the providing of such a small hole in a plate o~ any appreciable thickness may be a more difficult molding process~ and therefore it is preferred 6 to provide a plate of sufficient thickness to impart the necessary strength for 7 handling in bulk after molding and individually after molding, and provide a 8 thin portion in which the aperture is molded, said thin portion being spaced 9 inwardly from the edges of the plate, ~o that it is protected from damage by the surrounding thicker portion of the plate.
11 Referring now to Figs. 10 and 11~ there is illustrated another modified 12 form of test plate 54b, which may be of uniform thickness except for the front 13 edge which is beveled, forming surface~ 66 and 68 disposed at a predetermined 14 acute angle to each other~ forming an extreme forward edge portion 70. When the plate 54b is moved forwardly so that the edge 70 approximately bisectY the 16 light beam, sufficient light is transmitted through the thin extreme forward 17 edge 70 and seen by the photo-responsive device to simulate the required 18 amount of smoke and actuate the alarm.
19 The amount of light passing through the forward edge of the beveled portion of the test plate for a given plastic composition, is a function of the 21 included angle between the two surfaces and the length thereof e~posed to the 22 light~ witb a greater ligllt transmission resulting with smaller angles. For 23 a detector housing of given size and composition, the angle between the surfaces 24 that will simulate a required amount of smoke can easily be determined by experiment.
26 Since changes apparent to one skilled in the art may be made in the 27 illustrated embodiment of the invention without departing from the scope of 28 the invention, it is intended that all matter contained hercin be interpreted 29 ~in an i trative and not n limitin~ sen~e.
~ _7_
8 Other upwardly extending members are provided in the housing to form 9 suitably shaped cavities 30 and 32 to receive a light source 34 and a photo-responsive device 36, with associated focusing lenses 38 and 40.
11 The cavitieg 30 and 32 are shaped and dimensioned to retain the light 12 source and photo-responsive device in a position and orientation such t~at the 13 light beam from the source projects out of the opening 26 at an angle of about 14 22~- from the longitudinal axis of the housing and the viewing axis of the photo-responsive device extends out of the opening 24 also at an angle of 16 about 222 to the axis of the housing, so that thc vicwing axis of tbe photo-17 responsive device intersects the axis of the light beam in front of the medial 18 portion of the housing at a point A ~ig. 5) at an angle of about 135 to take 19 advantage of the well-known "forward scatter" effect. The intersection of the viewing cone of the photo-cell and the cone of the light beam is illustrated 21 by the shaded area V.
22 The light source and photo-responsive device may be connected into suitable 23 circuitry (not shown), by which the light source is energi~ed in a desired 24 manner, and light reflected onto the photo-responsive device irom smoke particles in the light beam cause a response of said photo-responsive device 26 that actuates an alarm.
27 Examples of such circuitry may be found in U.S. patents 3,946,241 issued 28 March 23, 1976~ 3,917,956 issued November 4? 1975, and patent 4,125~779 issued 29 November 14, 1978.
_4_ 1~
.9269 1 The viewing area of the photo-cell may be surrounded by a suitable 2 enclosure 41 having internal light absorbing baffles 43, said enclosure having 3 suitable apertures (not shown) to freely admit ambient atmosphere.
~ A cover plate 42 is provided for the housing~ said plate being providedwith an aperture 44 in the medial portion of the front edge and a pair of 6 support arms 46 extending upwardly on opposite sides of the aperture, each 7 leg having an inwardly extending pin ~8 near the upper end thereof.
8 Assembled with the cover is a test lever 50, comprising a medial portion 9 having a pair of recesses 52 on opposite sides thereof receiving the pins 48so that the lever is movable on said pins as an axis. Depending from the 11 medial portion is a test plate 54 which is disposed in the slot 28 of the 12 housing, and extending upwardly and rearwardly therefrom is an operating member 13 56. Extending rearwardly from the lever 50 is an integral plastic leaf spIing 14 58, which, when the lever and cover are assembled with the housing, rests on a spring support 60 on the rear of the housing, so that the lever is biased 16 clockwise (as seen in Fig. 3) retaining the test plate 54 retracted into the17 slot 28.
18 The test plate 54 is moved to the test position by depressing the operating 19 member 56~ thereby pivoting the lever 50 counter-clockwise (Fig. 1~) and flexing the spring 58.
21 To limit the pivotine movement of the lever~ so that when the operating22 member is depressed a predetermined portion of the test plate stops substantiall 23 at the center of the light beam~ stop member 61 is provided on the cover, 24 positioned to contact the operating member 56 and limit the downward movement thereof.
26 In the embodiment of Figs. 6 and 7~ the leading portion of the test plate 27 has an area 62 which is thin in relation to rest of the mcmbcr, said arca bcing 28 substantially smaller than that of the light beam at the intersection of the29 light beam and the field of view of the photo-cell. When the test plate is ll~,9Z69 1 moved forwardly into t~e light beam, one side thereof is i~ minatPd by the 2 light beam, and the other side is viewed by the photo-responsive dcvicc. In 3 a preferred cmbodiment of the invention the housing lO and the lever 50 are Il formed of black plastic, to absorb stray radiation and to mini~i~e the transmission of light through the test plate 54.
6 ~owever, it has been fol~d that if the area 62 of the test plate is made 7 thin enough, sufficient light is transmitted therethrough and seen by the 8 photo-responsive device to simulate the reqllired ~lolmt of smoke and actuate 9 the alarm.
The amount of light passing through the thin area 62 of the test plate for 11 a given plastic composition, is a function of the thickness of said thin area 12 and the area thereof. For a detector housing of given size and composition, 13 and with a known amount of smoke to be simulated, the area and thickness that 14 will simulate a required amount of smoke can easily be dete~ined by experiment.
In the accompanying drawing, the thickness of the portion 62 as shown in 16 Fig. 7 is not intended to be a representation of the actual thickness necessary 17 for the desired result. ~
18 Although in the embodiment of Figs. 6 and 7 the translucent portion is 19 provided near the leading edge of the test plate, it will be understood that the thin translucent portion could be in a central portion of the test plate, and 21 means provided ~or projecting the test plate further into or completely across 22 the light beam so that the thin translucent portion is centered in the light 23 beam.
24 Referring to Figs. 8 and 9, there is illustrated a modified form of test plate 54a which is similar to test plate 54, with the e~ception that the 26 portion 62a need not be so thin as to be translucent~ and a small aperture 6l~
27 is provided in the portion 62a to allow a predetermined amount of light to pass 28 therethrough, The aperture 6~ may be 80 positioned in thé portion 62a as to be 29 substantially centrally located in the light beam when the test plate is in the 3o test position.
1 Although in the embodiment o~ Figs. 8 and 9, the aperture 6!l is positioned ¦
2 in a thin portion 62a, it will be undcrstood that if desired the plate may be 3 of uniform thickness with the aperture suitably positioned in the plate.
4 ~owever~ the providing of such a small hole in a plate o~ any appreciable thickness may be a more difficult molding process~ and therefore it is preferred 6 to provide a plate of sufficient thickness to impart the necessary strength for 7 handling in bulk after molding and individually after molding, and provide a 8 thin portion in which the aperture is molded, said thin portion being spaced 9 inwardly from the edges of the plate, ~o that it is protected from damage by the surrounding thicker portion of the plate.
11 Referring now to Figs. 10 and 11~ there is illustrated another modified 12 form of test plate 54b, which may be of uniform thickness except for the front 13 edge which is beveled, forming surface~ 66 and 68 disposed at a predetermined 14 acute angle to each other~ forming an extreme forward edge portion 70. When the plate 54b is moved forwardly so that the edge 70 approximately bisectY the 16 light beam, sufficient light is transmitted through the thin extreme forward 17 edge 70 and seen by the photo-responsive device to simulate the required 18 amount of smoke and actuate the alarm.
19 The amount of light passing through the forward edge of the beveled portion of the test plate for a given plastic composition, is a function of the 21 included angle between the two surfaces and the length thereof e~posed to the 22 light~ witb a greater ligllt transmission resulting with smaller angles. For 23 a detector housing of given size and composition, the angle between the surfaces 24 that will simulate a required amount of smoke can easily be determined by experiment.
26 Since changes apparent to one skilled in the art may be made in the 27 illustrated embodiment of the invention without departing from the scope of 28 the invention, it is intended that all matter contained hercin be interpreted 29 ~in an i trative and not n limitin~ sen~e.
~ _7_
Claims (8)
1. In a smoke detector of the photo-electric type which includes a light source providing a light beam and photo-responsive means viewing transversely a portion of the light beam, the improvement comprising test means for simulating a predetermined smoke concentration, said means comprising a substantially opaque plate and means for temporarily positioning the plate in the light beam between the light source and the photo-responsive device so that the plate is illuminated on one side by the light beam and the other side is viewed by the photo-responsive device, said plate having a light-transmittingl portion, said light transmitting portion allowing a predetermined amount of light to pass therethrough when the plate is so positioned in the light beam.
2. A smoke detector as set out in claim 1 in which said light-transmitting portion has an area substantially smaller than the area of the light beam at its intersection with the field of view of the photo-responsive device, and means is provided for positioning said portion in the light beam at the intersection of the light beam with the field of view of the photo-responsive device.
3. A smoke detector as set out in claim 2 in which said light-transmitting portion is imperforate and has a thickness such that it is sufficiently translucent to allow the required amount of light to be seen by the photo-responsive device.
4. A smoke detector as set out in claim 3 in which said light-transmitting portion is surrounded by plate portions which are appreciably thicker than said light-transmitting portion.
5. A smoke detector as set out in claim 1 in which said light-transmitting portion is an aperture.
6. A smoke detector as set out in claim 4 in which said aperture is disposed in a portion of the plate which is substantially thinner than the surrounding portion of the plate.
7. A smoke detector as set out in claim 1 in which the light-transmitting portion comprises a translucent portion at the extreme forward edge.
8. A smoke detector as set out in claim 7 in which the forward edge of the plate is beveled at an acute angle to form said translucent portion at the apex of the beveled portion.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US855,624 | 1977-11-29 | ||
| US855,623 | 1977-11-29 | ||
| US05/855,623 US4144458A (en) | 1977-11-29 | 1977-11-29 | Smoke detector with test means for simulating a predetermined concentration of smoke |
| US05/855,624 US4144459A (en) | 1977-11-29 | 1977-11-29 | Smoke detector with test means for simulating a predetermined percentage of smoke |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119269A true CA1119269A (en) | 1982-03-02 |
Family
ID=27127301
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000317076A Expired CA1119269A (en) | 1977-11-29 | 1978-11-29 | Smoke detector with test means for simulating a pre-determined percentage of smoke |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5491395A (en) |
| AU (1) | AU516023B2 (en) |
| CA (1) | CA1119269A (en) |
| DE (1) | DE2851660A1 (en) |
| GB (1) | GB2009399B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112447019A (en) * | 2019-08-27 | 2021-03-05 | 霍尼韦尔国际公司 | Self-testing fire sensing apparatus |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4306230A (en) * | 1979-12-10 | 1981-12-15 | Honeywell Inc. | Self-checking photoelectric smoke detector |
| JPS626144A (en) * | 1985-07-03 | 1987-01-13 | Nittan Co Ltd | Photoelectric type smoke sensor |
| GB2259761B (en) * | 1991-09-18 | 1995-04-05 | Graviner Ltd Kidde | Smoke and particle detector |
| JP3251407B2 (en) * | 1993-12-22 | 2002-01-28 | 能美防災株式会社 | Photoelectric fire detector and adjuster |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4021792A (en) * | 1975-06-23 | 1977-05-03 | Wellen Industries | Smoke alarm |
| JPS52141682A (en) * | 1976-05-20 | 1977-11-26 | Matsushita Electric Works Ltd | Sensitivity tester of photoelectric sensor |
-
1978
- 1978-11-28 AU AU41980/78A patent/AU516023B2/en not_active Expired
- 1978-11-29 GB GB7846512A patent/GB2009399B/en not_active Expired
- 1978-11-29 CA CA000317076A patent/CA1119269A/en not_active Expired
- 1978-11-29 DE DE19782851660 patent/DE2851660A1/en not_active Withdrawn
- 1978-11-29 JP JP14769378A patent/JPS5491395A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112447019A (en) * | 2019-08-27 | 2021-03-05 | 霍尼韦尔国际公司 | Self-testing fire sensing apparatus |
| US11749097B2 (en) | 2019-08-27 | 2023-09-05 | Honeywell International Inc. | Self-testing fire sensing device |
Also Published As
| Publication number | Publication date |
|---|---|
| AU4198078A (en) | 1979-06-07 |
| DE2851660A1 (en) | 1979-06-07 |
| GB2009399A (en) | 1979-06-13 |
| AU516023B2 (en) | 1981-05-14 |
| JPS5491395A (en) | 1979-07-19 |
| GB2009399B (en) | 1982-05-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |