GB2580646A

GB2580646A - Smoke detector

Info

Publication number: GB2580646A
Application number: GB1900748.3A
Authority: GB
Inventors: Mark Dibden Gareth; Smoley David; Revill Steve
Original assignee: FFE Ltd
Current assignee: FFE Ltd
Priority date: 2019-01-18
Filing date: 2019-01-18
Publication date: 2020-07-29
Also published as: GB201900748D0

Abstract

A smoke detector apparatus comprises: transmitter 108 for projecting an infrared beam onto reflector 128; infrared receiver 110 for detecting the beam intensity received back from the reflector; camera 106, and motorised gimbal 120 for aligning the transmitter and the infrared receiver. Image recognition is executed on processor 126 to recognise the reflector from images received by the camera, ascertain any misalignment between a position of the reflector in the field of view of the camera and the direction of projection of the transmitter, and for signalling the misalignment to the motorised gimbal; wherein the motorised gimbal automatically aligns the transmitter with the reflector. In a second aspect, a smoke detector system transmits light onto reflectors and detects light received from each of the reflectors; wherein each reflector is recognisable by identification of an associated identifier through image recognition using a camera. The system initiates a warning, signal, alarm, or other reaction with an identification of the associated reflector if the detected light is lower than a predetermined threshold.

Description

Smoke Detector

Field of the Invention

The present invention relates to a smoke detector of a wide-area type that employs a beam projected onto a detector and measures obscuration of the beam ias an indicator of smoke.

Background

Smoke detectors of this type are known, for example from EP3258452. That patent appiication describes a reflective optical beam smoke detector system with a detector unit which includes both a transmitter and a receiver, and a retro-reflector. The detector unit and the reflector are placed opposite each other at opposing ends of a volume to be protected and monitored. The transmitter projects a beam, for example an Infrared (IR) beam, cm to the retro-reflector which reflects the IR beam along the same axis back to the receiver, Smoke in the beam path will reduce the amount of light returning to the rece(ver. The receiver continuously monitors the amount of light received and, if it drops below a certain user-defined threshold, then an alarm is initiated.

W02010124347 describes systems in which a beam is projected across a monitored area and attenuation of the beam is measured and refers to these as obscuration detectors', or 'bean' detectors'. it mainly describes a version which uses a separate transmitter unit and receive a unit located on opposite sides or the open space being monitored, but also describes a version in which the beam detectors employs a co located transmitter and receiver with a distant reflector.

In normal circumstances when no smoke is present), correct operation of the system relies upon stability of the amount of light being returned from the retro-reflector, as the receiver struggles to distinguish between a reduction in the level of light caused by the presence of smoke, and that caused by other factors, for example typical environmental movement of a building which can affect alignment of the system, The light beam must be correctly aligned on to the retro-reflector during initial installation.

Manual alignment can be a slow and drawn-out process, and it is surprisingly easy, even for professionals using this method, to achieve the wrong alignment -for instance, alignment with a reflective object which is not the reflector per se. Laser targeting -illumination of the reflector with a visible laser -has led to a reduction in wrong alignment; however, alignment of the laser on the reflector is no: guarantee of alignment of the transmitter and the reflector, and the reflector and the receiver: In the co-located transmitter/receiver arrangement of W02010124347, the receiver includes a matrix of light sensor elements, e.g. CU) (charge-coupled device) image sensor chip, or LIV105 (complementary metal-oxide-semiconductor) image sensors such as in a video camera. It uses imaging optics to form an image of a field Q f its view, including a target. It records the intensity of lig ht in its field of view, in the form of data representing the image *intensity at a series of locations throughout the field of view. A portion of this data will correspond, at least partially, to light reflected from the target A microcontroller analyses the image data, and determines which portion of the data provides the best estimate of the light reflected from the target. It is described that the receiver has a wide field of view and has the ability to independently measure light at a wide range of points within its field of view. For this reason, the light source need not be carefully aligned with the target or with the receiver.

Such an arrangement is not;deal for smoke detection. Smoke detection ideally uses certain preferred infra-red frequencies, so such an arrangement either calls for a CCD of preferred wavelength but limited resolution, or a camera of high resolution but 'suboptimal wavelength, or an expensive bespoke iR camera of the preferred wavelength and high resolution.

EP3258452 describes a more efficient and effective alignment procedure. it describes a method for aligning a projected beam on a reflector in a reflective-type beam detector. It describes adjusting the projected beam so as to: project on to substantially all, if not all, of a reflective surface of the reflector; or project on to at least a portion of a reflective surface of the reflector until a constant signal is received from the reflector.. One or more edges of the reflective surface of the reflector are detected and thereby the projected beam is centred, so as to align an approx. centre of the projected beam on an approx. centre of the reflective surface of the reflector. A shape or profile of the reflector can be ascertained, It can often be the case that other reflective surfaces in the installation environment can give quite good reflections and cause alignment problems. For example, windows, shiny metal surfaces, highly polished surfaces and the like can all give false reflections that create problems for the alignment search and may slow it down while the search finds just the retro-reflector of interest (preferably by its shape distinguishing it from these other artefacts).

Summary of the invention.

In accordance with a first aspect cif the invention, an apparatus For smoke detection is provided comprising: means for projecting an infrared beam onto a reflector; an infrared receiver for detecting the beam received back from the reflector; means for measuring intensity of the refle d beam to diagnose the presence of smoke; means for aligning the means for projecting and the infrared receiver a camera; and image recognition means for recognising the reflector from images received by the camera and for ascertaining any misalignment between a position of the reflector in the field of view of the camera and the direction of projection of the means for projecting and for nailing the misalignment to the means for aligning. The means for aligning automatically aligns the means for projecting with the reflector, A processor receives signals from the means for detecting and initiates rning, sign-Is an alarm or otherwise reacts Oased on the received signals. The camera records images before and after the time the processor reacts. E,g, it uploads the images to an external device or to a cloud service.

in accordance with a second aspect of the invention, a kit of parts is provided. The kit comprises a first part, comprisng; means for projecting a beam onto a reflector; means for detecting the beam received from the reflector; and means for aligning the means for projecting and the means for detecting; a second part, comprising a controller for the means for aligning, wherein the controller accepts user inputs, and wherein the second part is;capable of mounting the first part onto a surface; a third part, comprising alternative means for mounting the first part onto the surface; and a faceplate for the second part; wherein the faceplate substitutes the first part when attached to the second part, The first part can be mounted onto the surface by the second part or the first part can be;mounted onto the surface by the third part, separate from bu connected to the second part, with the faceplate attached to the second part.

The second part preferably comprises a processor that receives signals from the means for dete ing and inihates a warning, signals an alarm or otherwise reacts based on the received signals, in:accordance with a third aspect, a smoke detector stem is provided, comprising; plurality of wherein each of the plurality of reflectors comprises an identifier; means for transmitting light he plurality of reflectors; means for detecting light received from each of the plurality of recognising the identifier and thereby recognising the associated refl ector; and a processor; if the detected light is lower than a predetermined threshold, the processor initiates a warning, signals an alarm, or otherwise reacts and identifies the associated reflector, The transmitted light IS preferably infrared. The means for detecting may be an infrared detector or a camera, e.g. a wide angle camera.

The means for transmitting may rotates about a vertical, axis to face each of ere plurality of reflectors. In another example, the means for transmitting and the means for receiving may rotate about a vertical axis to face each of the plurality of reflectors,

Brief Description of the Drawings

Preferred embodiments of the invention will now be disclosed, byway of example only, with reference to the following drawings, in which: Figure 1 illustrates an apparatus fora smoke detector system, Figures 2a and 2b illustrate a process of aligning the apparatus.

Figure 3 illustrates an alternative arrangement of the apparatus for the smoke detector system. Figure 4 illustrates an example method of smoke detect on using multiple rejectors.

Detailed Description

Figure 1 illustrates an apparatus for a detector system, which includes.a mount unit 102 and a detector unit 104.. The detector unit 104 comprises a housing 112 that houses a camera 106, a transmitter 108 and a receiver 110. The camera 106, transmitter 108 and receiver 110 are all directed in the same direction. The camera 106, transmitter 108 and receiver 110 are fixed to a 2-axis gimbal 120. A controller 122 and motors (not shown), which are connected to the gimbal 120, each has a control interface, and are connected through a control circuit. The controller 122 has an alignment mode button or switch 125_ it also has up/down and left/right buttons 127 (or a joystick or touchpad or similar 2 D controller) and may have other buttons. The controller 122 is connected to interface 124 on the mount unit 102. The mount unit 102 also comprises a processor 126, The *proce5sor preferably has a video output (e,g. USB or HDMI or RGB) far connection to a screen, which.

will be described. The apparatus is pointed towards a reflector 128, The transmitter 108 may transmit an infrared beam. Housing 112 may be made of a material that is opaque to the camera 106, transrriitter 108 and receiver 110. in this case, the housing 112 has three openings 114, 116 and 118 at the operational end of detector unit 04. The openings 114, 116 and 118 are formed of a material that is transparent to the camera, transmitter 108 and receiver 11a The apparatus is mounted to a wall, and the reflector is fixed on an opposite wall of a room or space to be monitored. To mount the apparatus to a wall, the mount tsnit 10 is affixed to the wall (by screw holes not shown) and the detector unit 104 is attached to the moo t unit 102. In an example, the detector unit is attached to the mount unit with a bayonet push-and-t c!section having a peripheral elastomeric Cl-ring seal.

The apparatus needs to be aligned with the reflector 128. The apparatus may be manually aligned: n 125 is to enter alignment mode. When manually aligning the apparatus, the output of the camera 106 protected onto:a screen (not shown) via the video output on the mount unit 102.

Figure 2a illustrates an example of the field, of view 201 of the camera 114 as projected on the screen when the apparatus is not aligned with the reflector 128, Camere 106 may be sensitive to visual light and infrared light. The reflector 128 is [Ruminated by natural or artificial light. By way of example, Figure 2a also shows a window with sunlight corning through. The window may be. as brightly lit as the reflector, but the reflector may also be illuminated by infrared light From the transmitter 108. A graphical image of a crosshair 200 or other indicator (generated by controller 122) indicates to the user where the transmitter 108 and receiver 110 are targeting, it is approximately in the centre of the field of view 20 may not be exactly in the centre, due to manufacturing tolerance). As the crosshair is not over the reflector 128, this indicates to the user that the apparatus is not aligned with the reflector 128" The user uses the buttons 127 to input alignment instructions through the interface 124, thereby controlling X and Y axis motors of the gimbal 120 to adjust the direction of the transmitter, receiver and camera, and uses what is projected on the screen to align the apparatus with the reflector 128.

Figure 2b illustrates ark example of what is projected on the screen us is aligned with the reflector. It can be seen that the apparatus is aligned when the crosshair is over the centre of the reflector 128, Once the apparatus is aligned, the user can set the apparatus, for example by pressing button 125 on the interface 124 to exit the alignment mode; whereupon the alignment is in an example, the interface 124 allows a user to set the alignment procedure to be manual or automatic. RI automatic, alignment, the processor 126 performs image recognition to search for arid recognise the reflector 128 from the camera's field of view. This may include looking for, or for a combination of, a particular shape or a particular brightness (or colour).

it may be noted that no time-consuming raster or other scan is necessary. The image recognition software identifies the target from within the image received by the camera.

The camera 106 may be able to observe the visible light spectrum and/or the infrared spectrum. In one example, where the camera 106 is sensitive. to infrared light, the conditions for recognising the reflector 128 may be a predetermined shape with a high intensity of infrared light.

If the reflector 128 has been recognised, the controller 122 automatically controls the X and Y motors for the gimbal 120 to align the apparatus with the reflector 128. In an example, the controller 122 calculates an angle of offset between the centre of the reflector and the crossharrs and performs incremental stepwise X andY adjustments of the gimbal motors in proportion to the calculated angle, taking a new image with each step. The apparatus is aligned to the reflector when the receiver 128 is able detect the beam, which was transmitted by the transmitter 108, when it is reflected at the centre of the reflector 128.

Alternatively, if the distance between the detector unit 104 and the target is known: the angle of offset can be calculated, and the necessary X and V adjustments can be calculated and made in a single step. The distance to the target canoe measured using round-trip IP puke measurements and the speed of light and by halving the round-trip distance, If no reflector is recognised by the image recognition software, an error message is generates and the search for a reflector is terminated.

In operation, the transmitter 108 transmits a beam towards reflector 128. The receiver 110 detects the intensity of the beam when it is reflected back, If the detected beam intensity is less than a threshold, the processor initiates a warning, signals an alarm or otherwise reacts. In an example, further thresholds can be used to determine whether the loss of intensity is due to smoke or an obstruction.

As the camera 106 is pointing in the same direction as the transmitter 108 and the receiver 110, the camera 105 is in a position to -see' the same view as the transmitter 108 and the receiver 110 The camera 106 captures actikay within its field of view at a suitable rate, e.g. SG-2G0 images per second, and saves these in a buffer (e.g. a first-in-first-out buffer).

The camera 106 may comprise fiGa sensors, wherein the red sensor extends to the range of the beam projected by the transmitter 108.

The outputs, of the receiver 110 and camera feed into the processor,. Images from the camera re input into the buffer. The buffer is capable of storing a rolling window of T1 seconds of 4 images (for example 20 seconds to a minute). The size of the buffer is a matter of choice.

From the buffer, when triggered arm, the 71 seconds of images are output by a suitable output transmitter, e.g. a radio transmitteror other output. These T1 seconds can be output by simply reading out the contents of the buffer while a further TI seconds are being read in, or the buffer may have parallel output capability, in which case the entire buffer is output in one operation.

The latter is advantageous, because it is advantageous to output e Iocation in case the processor and its Duffer are consumed by fire. (Alternatively, the processor and buffer can be located at a rem =te location,remote from the sensors and camera), After the alarm, the camera continues to capture activity, which it saves in the buffer and outputs (via output transmitter or otherwise) for a second window of 72 seconds. T2 may be a period of several minutes, e.g. 10 minutes to an hour. After T2, the controller reverts to normal operation.

The images can be compressed prior to storing in the buffer (whereto-storage in the buffer is more efficient) or on heading out fro n the butter (whereby compression is not performed unnecessarily and there is no delay storing into the buffer) which can be important if what is being recorded is an explosion), if uncompressed images are stored in the buffer, they can be compressed at the time of sending. Thus, the camera 106 allows for image capture before and after an activation, e.g. alarm or fault.

A first window, T1, prior to the alarm event, and a second window, 72, after the event are captured and can be relayed to a remote location where they can be analysed by fire personnel or by technical personnel, Thus, thecame or image e before and after at activatitrn, e.g.:alarm or fain Images captured can be remotely reported via output 33 and managed and/or manipulated. Thus, for example, the output may be an Internet Protocol interface allowing reporting to a remote server or a cloud computing service. At the remote service, diagnostics can be conducted from the field of view of the camera, Smoke tends to rise, in air, and it is advantageous to mount the detector unit 104 high up, near ceiling height. It may be advantageous for the detector unit 104 to be separate from the controller 122 and interface 124 of the mount unit 102. For example, if the detector unit is to be mounted in a high place, near ceiling height, which requires equipment such as a ladder to access, it may be preferable to be able to perform the alignment from lower down.

Figure 3 illustrates an alternative arrangement of the apparatus, which includes the mount unit 102 and the detector unit 104 of Figure 1, as well as a simple mount 302 and a faceplate 304.

In this arrangement, the detector unit 104 iS mounted onto a wall using the simple mount 302. In an *example. the detector unit is attached to the simple mount with a bayonet (push-and-twist) connection having a peripheral elastornenc CI-ringseal. The mount unit 102 is mounted somewhere that is more accessible, The faceplate 304 is used to cover where the detector unit 104 would have otherwise been attached, In an example, a display can be attached to the faceplate or mounted on the faceplate -Le, the simple faceplate is replaced with a display, The mount unit 102 and the simple mount 302 are connected so that the mount unit can still send signals to and receive signals from the detector unit 104.

In an example, the connection between the mount unit 102 and the simple mount 302 has a fireproof cable or a plastic conduit through which a wire connects the two parts. The part-cylindrical wa 1 of the mount unit 102 has up to three (top, left and right) push-out holes for the conduit and other conduits. The cylindrical wall of the sin-ale mount 302 may have four push-out holes (top, bottom, left and right). In another example. the connection between the mount unit 102 and the simple mount 302 is a wire with no conduit, In another example, the connection between the mount unit 101 and the simple mount 302 is a wireless connection.

The mount unit 102, the detector unit 104, the simple mount 302 and the faceplate 304 may form a kit of parts supplied together is common packaging, There are two Possible arrangements. The first is that the detector unit 104 is mounted onto a wall using the mount unit 102. in this case, the simple mount 302 and the faceplate 304, which are inexpensive plastic items that do not contain any electronics, may simply be discarded. In the second arrangement, as described above with reference to Figure 3, the detector unit 104 is mountedonto a wall using the simple mount 302, and the mount unit 102 is separately attached to a wall with the faceplate 304, with a connection between the mount unit 102 and the simple mount 302.

Fig, 4 illustrates an alternative method of smoke detection. The figure shows a room in plan view, with reflectors 402, 404, 406 and 408. Although this illustration uses four reflectors, it is understood that a smaller number of reflectors could be used, e.g. 2 or 3, or more than 4 can housed. At the centre of the room there is apparatus 41, which comprises of a camera, a transmitter and a receiver, The transmitter and receiver may be transmitter 108 and receiver 110 of Figure 1 respectively. The camera is a wide-angle camera, capable of capturing an image over at least 90 degrees and preferably 180 degrees or more, or even a full 360 degree camera (as in the Illustration). The dashed lines on Figure 4 depict the path of a beam between the apparatus 410 and each of the reflectors 402, 404, 406 and 408.

The reflectors 402, 404, 406 and 408 each have an identifier which can be used by apparatus 410 to identify each individual reflector. In an example, the unique identifier comprises a portion of the reflector that is obscured in a unique way.. In an example, each reflector is obscured with a different shape. Byway of example, stick-on shapes such as square, circle and triangle can be used. These may be black so as to riot reflect light or may be vvhite or other colour. The shapes a re such as can readily be recognised by standard image recognition software.

In these examples, the centre of the reflector, where the beam is reflected, is preferably free from obsCuration.

Pairs or combinations of shapes (circle 4 triangle etc.) can be used to uniquely identify reflectors.

Numbers, letters, symbols or combinations can be used so long as they are readily recognisable by image recognition. In another example" the unique identifier comprises a barcode or.a QR code across the face of the reflector.

The transmitter projects a beam onto each of the reflectors 402, 404, 406 and 408. In an example, the transmitter projects a beam that covers an area slightly wider than a reflector. In an example, the transmitter projects a wide beam that covers more than one reflector. in an example, the transmitter rotates about a vertical axis to face each reflector in turn, The beam may be an infrared beam.

The receiver detects the intensity of each beam when it is reflected back. If the detected beam iritensity is less than a threshold, the processor initiates a warning, signals an alarm or otherwise reacts. In an example, further thresholds can be used to determine whether the loss of intensity is due to smoke or an obstruction.

In an example, the receiver is an infrared detector in an example,receiver rotates with the transmitter about the same vertical axis.

In an example, the receiver is the°camera, In an example, he camera is, a wide angle can aera, In an example, the camera is a 360 degree camerae ctors may be arranged to identify zones in theprotected area. Fur example, a r fle be placed on each wall of a room. When a beam intensity of less than the threshold^ is detected, the camera identifies the reflector associated with the beam and thereby the zone within the overall space in which the beam is obstructed, If the cause le loss of intensity is smoke, this may help identify the source of the smoke, If several reflectors re obstructed in a sequence, this may help identify the direction of propagation of the smoke.

If the cause of loss of intensity is an obstruction, then the unique identifier associated ith the reflector will identify which zone is being obstruct In an example, the camera may be used to determine the reason forthe loss of inten5 ty, In an exampie, images from the camera for before and after the event maybe recorded in response to the detection of intensity below a threshold, In this case the recorded images could also provide information on what caused the fire/smoke or a false alarm,

Claims

Claims 1. An apparatus for smoke detection, comprising: means for projecting an infrared beam onto a reflector; an infrared receiver for detecting the beam received back from the reflector; means for measuring intensity of the reflected beam to diagnose the presence of smoke; means for aligning the means for projecting and the infrared receiver; a camera; and image recognition means for recognising the reflector from images received by the camera and for ascertaining any misalignment between a position of the reflector in the field of view of the camera and the direction of projection of the means for projecting and for signalling the misalignment to the means for aligning; wherein the means for aligning automatically aligns the means for projecting with the reflector.
2. The apparatus of claim 1, wherein an output from the camera is projected to a screen.
3. The apparatus of claim 1, wherein the camera detects visible and infrared light.
4. The apparatus of any preceding claim, further comprising a processor, wherein the processor receives signals from the means for detecting and initiates a warning, signals an alarm or otherwise reacts based on the received signals.
5. The apparatus of claim 4, wherein the camera records images before and after the time the processor reacts.
6. The apparatus of claim 5, wherein the camera uploads the images to an external device or to a cloud service.
7. A method, performed at a smoke detector comprising: projecting an infrared beam onto a reflector; detecting the beam received back from the reflector at an infrared receiver; measuring intensity of the reflected beam to diagnose the presence of smoke; aligning the means for projecting and the infrared receiver;: recognising the reflector, by image recognition, from images received by a camera; ascertaining any misalignment between a position of the reflector in the field of view of the camera and the direction of projection of the means for projecting; signalling misalignment to the means for aligning; and aligning the means for projecting with the reflector.
8. A kit of parts, comprising: a first part, comprising: means for projecting a beam onto a reflector; means for detecting the beam received from the reflector; and means for aligning the means for projecting and the means for detecting; a second part, comprising a controller for the means for aligning, wherein the controller accepts user inputs, and wherein the second part is capable of mounting the first part onto a surface; a third part, comprising alternative means for mounting the first part onto the surface; and a faceplate for the second part, wherein the faceplate substitutes the first part when attached to the second part; whereby: the first part can be mounted onto the surface by the second part or the first part can be mounted onto the surface by the third part, separate from but connected to the second part, with the faceplate attached to the second part.
9. The kit of parts of claim 8, wherein the second part further comprises a processor, wherein the processor receives signals from the means for detecting.
10. The kit of parts of claim 9, wherein the processor initiates a warning, signals an alarm or otherwise reacts based on the received signals.
11. The kit of parts of claim 8, wherein the means for aligning comprises a gimbal.
12. The kit of parts of claim 8, wherein the controller controls the means for aligning automatically.
13. The kit of parts of claim 8, wherein the controller controls the means for aligning using the user inputs.
14. The kit of parts of claim 8, wherein the projected beam is an infrared beam.
15. The kit of parts of claim 8, wherein the first part and faceplate are connectable to the second part with a common bayonet connection. 5
16. The kit of parts of claim 8, wherein the faceplate further comprises a display.
17. A smoke detector system, comprising: a plurality of reflectors, wherein each of the plurality of reflectors comprises an identifier; means for transmitting light onto the plurality of reflectors; means for detecting light received from each of the plurality of reflectors; means for recognising the identifier and thereby recognising the associated reflector; and a processor; wherein if the detected light is lower than a predetermined threshold: the processor initiates a warning, signals an alarm, or otherwise reacts and identifies the associated reflector.
18. The system of claim 17, wherein the transmitted light is infrared.
19. The system of claim 18, wherein the means for detecting is an infrared detector.
20. The system of claim 17, wherein the means for detecting is a camera.
21. The system of claim 20, wherein the camera is a wide angle camera. 25
22. The system of claim 20, wherein the camera is a 360 degree camera.
23. The system of claim 17, wherein the means for transmitting rotates about a vertical axis to face each of the plurality of reflectors. 30
24. A method, performed at a smoke detector system comprising: transmitting light onto a plurality of reflectors, each comprising an identifier; detecting light received from each of the plurality of reflectors; recognising the identifier by image recognition using a camera, and thereby recognising the associated reflector; and if the detected light is lower than a predetermined threshold, initiating a warning, signalling an alarm, or otherwise reacting and identifying the associated reflector.