Insect trap and method

Abstract

An insect trap and a method of using the same. The insect trap includes a housing. The insect trap also includes a glue board receiving space located inside the housing. The insect trap further includes one or more light sources for attracting insects into the housing. The insect trap also includes a camera having a lens. The lens has a front element. The camera is positioned to capture images of a glue board when the glue board is received in the glue board receiving space. There is no line of sight between the or each light source and the front element of the lens. This may prevent light from the or each light source reaching the front element directly. The method can include using an image captured by the camera to determine that a glue board received in the glue board receiving space needs to be replaced.

Description

<DP=1>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²1²INSECT TRAP AND METHOD²FIELD OF THE INVENTION²This invention relates to an insect trap and to a method of using an insect ²traps²BACKGROUND OF THE INVENTION²Known insect traps typically use UV light having a wavelength of approximately²368nm to attract insects onto an insect disabling portion such as a glue board ²or a high voltage²killing grid provided within a housing.²When a glue board is used, the glue board needs to be replaced periodically, ²as it dries ²out and / or becomes covered with captured insects. It is difficult to predict ²how long a glue²board may last for before it needs to be replaced. It is known to use a camera ²to take images²for determining the capture of insects in an insect trap. It is also known to ²use images of this ²kind to determine the number and kind of insects that have been caught.²JP 2013 236586 describes an insect capturing device that includes an insect-²attracting²light in an insect capturing case for attracting an insect having an opening, ²and an adhesive²sheet for adhering and capturing the insect attracted by the light of the ²insect-attracting light. ²A plurality of CCD cameras capable of photographing exposed parts of an upper ²surface of the ²adhesive sheet are arranged to face the adhesive sheet so that a part not ²included in a ²photographing regions of the CCD cameras out of the exposed part is ²eliminated.²EP 2 149 301 describes a method and device for the automated registering of ²insects ²present on a catch plate. The catch plate is introduced into a device and ²scanning of the catch ²plate is carried out with the aid of a camera and light. The presence of ²insects, like the number ²of insects, is determined based on vision technologies. Optionally with the ²intervention of a²remotely positioned central processing unit, a signal is issued, based ²thereon, if a threshold ²value is exceeded. Based thereon, it is possible to take measures, in for ²example a growing ²space where the catch plates are positioned, in order to counteract ²undesirable phenomena.²<DP=2>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²2²US 2006 / 215885 describes systems and methods for detecting presence and ²movement ²of pests. A pest detection system can be based on, for example, a beam-²interrupt detector or a ²thermal imaging device. The beam-interrupt detection based system can provide ²fimctionalities ²such as counting of pests crossing a given beam. A plurality of such beams at ²different heights²can also allow distinguishing different sized pests. The thermal imaging based ²detection system²can provide functionalities such as tracking movement of pests. A recording ²can be triggered ²by detection of pest movement, thereby improving the efficiency of recording ²and reviewing ²information indicative of presence and movement of pests in a monitored area. ²Movement of ²pests can be monitored on a passive basis, or by providing a stimulus that ²induces movement.²WO 2014 / 125158 describes a method and an apparatus for imaging arthropods. In ²the ²method an arthropod is detected. The arthropod may be illuminated when ²necessary. The ²method further comprises providing at least a first view to at least a part of ²the arthropod, ²providing a second view to the arthropod, and capturing at least one image of ²at least the first²view and a second view of the arthropod. The apparatus comprises means for ²detecting an²arthropod; means for providing a first view to at least a part of the ²arthropod and means for ²capturing an image of at least the first view and a second view of the ²arthropod.²JP 2003 169584 describes a noxious insect trap that has a supplying roll ²winding an²adhesive sheet for capturing the noxious insects, a winding roll for winding ²up the adhesive²sheet drawn out from the supplying roll, an insect trap part for extending the ²adhesive sheet ²between the supplying roll and winding up roll and a trapped insect analyzing ²part for ²performing the counting of the number of trapped insects on the adhesive sheet ²and / or ²identification of their kinds. The trapped insect-analyzing part is ²constituted by having a²picture-taking part for taking the pictures of transmitted light of the ²trapped insects by the²adhesive sheet and the analyzing part for performing the counting of the ²number of the insects ²and / or the identification of their kinds from image information obtained by ²the picture-taking ²part 70.²JP 2009 072131 describes an insect catcher that comprises a means for ²attracting²outside insects thereinto inside a long-length casing with openings, via which ²insects can ²intrude thereinto and a holder capable of holding a strip of insect-catching ²sheet provided with ²a tacky surface for catching insects the casing in the longitudinal direction. ²This insect catcher²<DP=3>²CA 03041394 2019-04-23²WO 2018 / 134550 ²PCT / GB2017 / 053315²3²is characterized by being equipped with a photographer movable along the ²insect-catching ²sheet in the longitudinal direction to enable the whole length of the insect-²catching sheet X to ²be photographed.²JP 2008 259448 describes an insect trap including an insect-attracting light, ²which is²arranged in the depth direction of an opening part through which insects come ²in and out; a ²prescribed insect-trapping space for trapping the insects is formed ²therebetween. The adhesive ²sheet is arranged at the lower side of the insect-trapping space, and the ²image-taking means for ²taking the image of the insects attached to the adhesive sheet by facing ²thereto is arranged at²the upper side and constituted so as to be able to move reciprocatingly along ²the longitudinal²direction of the sheet surface.²JP 2013 236586 describes an insect capturing device that includes an insect-²attracting ²light in an insect capturing case for attracting an insect having an opening, ²and an adhesive²sheet for adhering and capturing the insect attracted by the light of the ²insect-attracting light.²A plurality of CCD cameras capable of photographing exposed parts of an upper ²surface of the ²adhesive sheet are arranged to face the adhesive sheet so that a part not ²included in a ²photographing regions of the CDC cameras out of the exposed part is ²eliminated.²<DP=4>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²4²SUMMARY OF THE INVENTION²Aspects of the invention are set out in the accompanying independent and ²dependent ²claims. Combinations of features from the dependent claims may be combined ²with features of ²the independent claims as appropriate and not merely as explicitly set out in ²the claims.²According to an aspect of the invention, there is provided an insect trap ²comprising:²a housing;²a glue board receiving space located inside the housing;² one or more light sources for attracting insects into the housing; and ²a camera having a lens with a focal length in the range 1 mm < f < 18mm, the ²lens ²having a front element, wherein the camera is positioned to capture images of ²a glue board ²when said glue board is received in the glue board receiving space, wherein ²the light received ²by the lens of the camera for capturing images of the glue board comprises ²light from the one²or more light sources reflected from the glue board;²wherein there is no line of sight between the or each light source and the ²front element²of the lens, for preventing light from the or each light source reaching the ²front element directly.²The focal length of the lens, in the range 1 mm < f < 18mm, can allow the lens ²to be²placed close to the glue board (for reducing the physical size of the trap). ²Wide angle lenses ²may be particularly susceptible to lens flare. Since light from the or each ²light source cannot ²reach the front element of the lens directly, lens flare in images captured by ²the camera may be ²prevented. This can improve the quality of the images captured by the camera.²The improved quality of the images may allow a more accurate determination to ²be ²made as to the status of the glue board. For instance, an improved ²determination may be made ²as to whether a glue board received in the glue board receiving space needs to ²be replaced or ²not.²The camera may be generally fixed in position with respect to the glue board ²receiving ²space and a glue board received in the glue board receiving space.²<DP=5>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²The or each light source may be located a greater distance away from the glue ²board ²receiving space, along a direction substantially parallel to an optical axis ²of the lens, than a ²front surface of the front element of the lens. By positioning the or each ²light source behind ²the camera in this way, it may be ensured that there is no line of sight ²between the or each light²5 ²source and the front element of the lens, without necessarily having to take ²any further²measures to prevent lens flare (e.g. providing a hood for the lens). ²Additionally, it is noted that ²placing the light source(s) further away from the glue board receiving space ²may generally lead ²to less intense reflections from the glue board itself, which can help to ²prevent glare in the ²images of the glue board captured by the camera.²A surface may be located inside the housing, which faces the glue board ²receiving ²space. The lens of the camera may be mounted in an opening in the surface. The ²surface may ²be the surface of an enclosure containing the camera and one or more further ²electronic ²components of the insect trap. The or each light source may be located outside ²the enclosure.²In this way, the enclosure may shield the camera and / or further electronic ²components of the²trap from heat generated by the or each light source, while the opening in the ²surface can allow ²the lens access to capture images of a glue board received in the glue board ²receiving space. ²Note that in some examples, features of the enclosure may also serve to block ²any line of sight ²between the or each light source and the front element of the lens.²The glue board receiving space may substantially fill a field of view of the ²camera. In ²this way, the camera can capture images covering substantially all of a glue ²board received in ²the glue board receiving space.²An optical axis of the lens may be oriented substantially parallel to a ²surface normal of²the glue board when the glue board is received in the glue board receiving ²space. This can help ²reduce perspective distortion in the captured images.²A distance between a front surface of the front element and the glue board ²receiving²space, along an optical axis of the lens, may be in the range 50mm <d < 200mm. ²In one²example, the distance may be in range 70mm < d < 130mm. In one particular ²example, the ²distance may be around 100mm. By reducing the distance between the lens and a ²glue board ²received in the glue board receiving space, the insect trap may be made more ²compact. In one²<DP=6>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²6²example, the lens may have a focal length in the range 2mm < f < 12mm. In one ²particular ²example, the lens may have a focal length of around 2.1mm. The lens may be a ²fisheye lens.²The or each light source may be a fluorescent tube. A longitudinal axis of the ²or each²fluorescent tube may be oriented substantially parallel to a plane containing ²the glue board²receiving space. This can allow the insect trap to be made compact while also ²ensuring that no ²part of the tube(s) is visible to the camera lens.²The or each light source may be a light emitting diode.²One or more surfaces located inside the housing may be anti-reflective ²surfaces. For ²instance, the surfaces may be coated with anti-reflective paint, or may be ²provided with some ²other form of matt coating. In one example, the surface(s) may be matt plastic ²surfaces. This ²can prevent lens flare arising from light reflected from surfaces within the ²trap reaching the² .. front element.²The or each light source may be configured to emit ultraviolet light having a ²peak ²wavelength in the range 300nm < < 400nm. For instance the peak wavelength may ²be around ²368nm. This wavelength is particularly effective at attracting insects.²According to another aspect of the invention, there is provided a method of ²using an²insect trap of the kind set out above, the method comprising:²using an image captured by the camera to determine that a glue board received ²in the²glue board receiving space needs to be replaced; and²replacing the glue board.²Because of the above mentioned measures taken for reducing or preventing lens ²flare ²in images captured by the camera, the accuracy of the determinations as to ²whether a glue board ²received in the glue board receiving space needs to be replaced may be ²improved. This can²prevent glue boards being left in the insect trap too long, or conversely ²being replaced too early.²<DP=7>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²7²BRIEF DESCRIPTION OF THE DRAWINGS²Embodiments of the present invention will be described hereinafter, by way of ²example ²only, with reference to the accompanying drawings in which like reference ²signs relate to like² elements and in which:²Figure 1 shows a front isometric view of an insect trap according to an ²embodiment of²the invention;²Figure 2 shows a rear isometric view of the insect trap of Figure 1, according ²to an²embodiment of the invention;²Figure 3 shows a left side view of the insect trap of Figure 1, according to ²an²embodiment of the invention;²Figure 4 shows a right side view of the insect trap of Figure 1, according to ²an²embodiment of the invention;²Figure 5 shows a top side view of the insect trap of Figure 1, according to an²embodiment of the invention;²Figure 6 shows a bottom side view of the insect trap of Figure 1, according to ²an²embodiment of the invention;²Figure 7 shows a front side view of the insect trap of Figure 1, according to ²an²embodiment of the invention;²Figure 8 shows a front side view (with the front cover removed) of the insect ²trap of ²Figure 1, according to an embodiment of the invention;²Figure 9 shows cross section of the insect trap of Figure 1, according to an ²embodiment ²of the invention; and²Figure 10 shows a rear isometric view (with the rear cover plate removed) of ²the insect²trap of Figure 1, according to an embodiment of the invention.²<DP=8>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²8²DETAILED DESCRIPTION²Embodiments of the present invention are described in the following with ²reference to²the accompanying drawings.²Figures 1 to 10 show various views of an insect trap 10 according to an ²embodiment of²this invention.²The insect trap 10 in this example is suitable for use in a premises such as a ²factory,²warehouse, restaurant or offices. The insect trap 10 in this example is wall ²mountable. It is ²also envisaged that a trap according to the present invention may be ceiling ²mounted, or may ²be free standing for placement on a surface such as the floor or on a table.²The insect trap includes a housing 10. The housing in this example includes a²substantially flat rear cover plate 8. The rear cover plate 8 may be provided ²with one or more ²fixtures to facilitate the mounting of the insect trap 10 on a surface such as ²a wall.²The housing may also include a front cover 2. The front cover 2 in the present ²example ²includes a front portion 4 for covering the front of the insect trap (which ²faces outwardly, when²the trap 10 is mounted on a wall). As shown particularly in Figure 3, the ²front cover 2 may ²also include an upper portion 6 for covering an upper side of the trap 10 and ²a lower portion 7 ²for covering a lower side of the trap. Accordingly, the front cover 2 may be ²substantially C-²shaped. The front portion 4, upper portion 6 and lower portion 7 may be ²integrally formed. As ²can be seen from Figures 1 and 2, there is a gap between the rear cover plate ²8 and the upper²portion 6, and another gap between the rear cover plate 8 and the lower ²portion 7. These gaps ²allow insects to enter the trap for immobilisation.²The housing may also include a first sidewall 32 and a second sidewall 34 ²opposite the ²first side wall. Each side wall 32, 34 may include one or more openings 36. ²The openings 36² may allow insects to enter the trap 10.²The various parts of the housing described above may, for instance, be formed ²from²sheet metal (e.g. Zinc plated mild steel sheet), stamped and folded into the ²desired shape.²<DP=9>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²9²The insect trap 10 also includes a glue board receiving space. The glue board ²receiving ²space may be substantially planar for receiving a flat glue board. However, it ²is also envisaged ²that the glue board receiving space may in other examples be shaped to ²accommodate a non-² flat glue board (e.g. a glue board including one or more folds).²In the present example, the glue board receiving space is defined by a surface ²of the ²rear cover plate 8 which faces the inside of the trap 10. This surface of the ²rear cover plate 8 ²may be provided with features for mounting the glue board. In the present ²example, the rear²cover plate 8 is provided with opposing channels 12 located at either end ²thereof (e.g. adjacent²the side sidewalls 32, 34 as shown in Figure 1). The channels 12 can receive ²the edges of the ²glue board, for holding the glue board in place. When installed, a sticky ²surface of the glue ²board faces the inside of the trap 10 for immobilising insects that have ²entered the trap 10.²The insect trap 10 also includes one or more light sources. These light ²sources may,²for example, be fluorescent tubes or light emitting diodes (LEDs). The light ²sources are ²configured to attract insects into the housing of the trap 10. As such, the ²light sources may be ²operable to emit light at wavelengths that are known to attract insects. In ²one example, the or ²each light source may be configured to emit ultraviolet light having a peak ²wavelength in the²range 300nm < X < 400nm. For instance the peak wavelength may be around 368nm. ²This²wavelength is particularly effective at attracting insects.²Each light source may be located inside the housing. Each light source is ²positioned so ²that light emitted from it may illuminate a glue board received in the glue ²board receiving²space. The front cover 2 may be provided with one or more openings 2A, 2B to ²allow light²generated by the light sources to exit the housing for attracting insects. ²Insects may also enter ²the housing through these openings 2A, 2B. Furthermore, the openings 2A, 2B ²may allow heat ²generated by the light source(s) to leave the housing (e.g. by radiation and ²by air convection).²In the present example, the insect trap 10 is provided with two light sources, ²each light²source comprising a fluorescent tube 20A, 20B. A first of the fluorescent ²tubes 20A in this ²example is located adjacent the front portion 4 and upper portion 6 of the ²front cover 2 (e.g. at ²a corner joining these two parts), while a second of the fluorescent tubes 20B ²in this example²<DP=10>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²is located adjacent the front portion 4 and lower portion 7 of the front cover ²2 (e.g. at a corner ²joining these two parts). As can be seen in Figure 1, a longitudinal axis of ²each fluorescent ²tube 20A, 20B in this example is oriented substantially parallel to a plane ²containing the glue ²board receiving space defined by the surface of the rear cover plate 8. The ²insect trap includes²5 ²electrical connectors 22 for supplying power to the terminals of each ²fluorescent tube 20A,²20B. The connectors 22 may be mounted on outer surfaces of the enclosure 80 to ²be described ²below.²As a glue board installed within the trap 10 increases in age, the number of ²insects²10 ²immobilised on it may increase, to the point at which the glue board becomes ²too full to be²fully effective for capturing further insects. At this point the glue board ²may be replaced with ²a fresh one.²The insect trap 10 also includes a camera 66. The camera 66 may be used to ²capture²images of a glue board that is received in the glue board receiving space. ²These images may²be used to inspect the glue board e.g. to determine whether the glue board ²needs to be replaced.²The camera 66 has a lens, which faces the glue board receiving space to allow ²the ²camera to capture images of the glue board. The lens has a front element 60. ²In the present²example, the camera 66 is mounted in an enclosure 80 located inside the ²housing of the insect²trap 10.²The enclosure 80 in this example is substantially box-shaped (e.g. rectangular ²cuboid ²shaped) and includes a number of sidewalls. The enclosure 80 in this example ²is located at the²front of the housing of the insect trap 10, distal the rear cover plate 8. ²Note that the fluorescent²tubes 20A, 20B may be located around the edges of the enclosure. For instance, ²in the present ²example, the fluorescent tube 20A is located above the enclosure 80, while the ²fluorescent tube ²20B is located below the enclosure 80.²One of the sidewalls of the enclosure 80 has an outer surface 50, which faces ²the glue²board receiving space. In the present example, the outer surface 50 is ²substantially planar, and ²is parallel the inwardly facing surface of the rear cover plate 8. The outer ²surface 50 of the ²enclosure 80 includes an opening 52. The lens of the camera 66 is mounted in ²the opening 52.²<DP=11>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²11²In this way, the camera 66 may be located inside the enclosure 80 while still ²being able to ²capture images of the glue board. The lens may substantially fill the opening ²52.²The insect trap may also include a control module 82. The control module may ²be²located inside the enclosure 80 along with the camera 66. The control module ²82 can serve to²control the operation of the camera to capture, store and distribute images of ²the glue board. ²The control module may include features such as a processor, memory and one or ²more I / O ²ports for implementing these functions.²The insect trap 10 may further include electronic ballast 72 for the ²fluorescent tubes²20A, 20B. The electronic ballast 72 may also be located inside the enclosure ²80.²Note that the enclosure 80 can provide physical protection (e.g. against ²mechanical ²shock or the ingress of dust etc.) for the components of the insect trap 10 ²such as the camera²66, control module 82 and the electronic ballast 72, while also shielding ²these components to²some extent against the heat produced by the light source(s). As can be seen ²in Figure 9, the ²lights sources are typically located outside the enclosure 80.²The insect trap may include one or more sockets 24 for receiving power ²connections²such as plugs 26 and cables 28. This may allow the insect trap 10 to be ²connected to a mains²power supply. In the present example, the socket(s) 24 are located outside the ²enclosure 80, ²on one of the sidewalls 32 of the housing.²The insect trap 10 may also include an antenna 40. The antenna may allow the ²insect²trap 10 (in particular, the control module 82 thereof) to connect wirelessly ²to a local network²and / or the internet. This may allow the insect trap 10 to be ²controlled / configured remotely, ²and may also allow the insect trap 10 to transmit the images captured by the ²camera 66 to a ²server. These images may then be used to monitor the status of the insect ²trap.²It is envisaged that the images captured by the camera 66 may be processed ²either at²the server or locally at the trap 10 itself in order to determine whether the ²glue board needs to ²be replaced. This may prevent the glue board from being replaced too early, ²reducing the costs²<DP=12>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²12²for maintaining the trap. It may also prevent delays in replacing the glue ²board after it has ²become too full to continue to immobilise insects effectively.²In order to allow effective processing of the images as described above, it is ²desirable²that the images captured by the camera 66 are substantially free from ²artifacts and are a good²representation of the actual appearance of the glue board.²An example of an artifact that may inhibit correct evaluation of the status of ²the glue ²board using the captured image is lens flare. Lens flare is generally ²associated with the²presence of a bright light source. In the context of an insect trap 10 that ²includes one or more²light sources and a camera 66 located in an enclosed space such as the ²housing, it will be ²appreciated that lens flare may well be problematic.²Lens flare may be caused by the scattering of light by multiple glass surfaces ²located in²a lens. Lenses that include multiple lens elements are particularly prone to ²lens flare, as the²number of surfaces available in the lens for scattering increases with an ²increasing number of ²lens elements that are included. It is noted that wide angle lenses may ²generally be more prone ²to lens flare owing to their large field of view.²Lens flare can degrade the captured images in two ways. Firstly, there may be ²a general²reduction in contrast in the images that are produced (often referred to as ²haze in the image). ²Secondly, lens flare may give rise to more specific artifacts, usually in the ²shape of the lens ²iris, which may be formed when light follows a pathway through the lens that ²contains one or ²more reflections from the lens surfaces.²The camera 66 is generally fixed in position with respect to the glue board / ²glue board ²receiving space (by which it is meant that the camera 66 is not configured to ²scan along ²different parts of the glue board for capturing multiple image(s) of different ²parts of the glue ²board (e.g. for use in a composite image)). The camera 66 may be operable to ²capture²individual images that each cover substantially all of a glue board received ²in the glue board²receiving space. For instance, the glue board receiving space may ²substantially fill a field of ²view of the camera 66. Because of this, there is no need to provide ²complicated and expensive²<DP=13>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²13²components in the insect trap 10 for implementing the use of a camera that ²scans the glue board ²(e.g. to produce a composite image).²In order to keep the size of the insect trap 10 compact, it may be generally ²desirable to²locate the camera 66 as close to the glue board receiving space as is ²practical. For instance, it²is envisaged that a distance between a front surface of the front element 60 ²of the lens and the ²glue board receiving space, along an optical axis of the lens, may be in the ²range 50mm < d < ²200mm. In one example, the distance may be in range 70mm < d < 130mm. In one ²particular ²example, the distance may be around 100mm. In view of this, it is anticipated ²that the lens²itself may need to have a relatively wide field of view, in order that the ²images captured by the²camera can cover substantially all of the glue board. The lens has a focal ²length in the range ²1 mm < f < 18mm. In one example, the lens may have a focal length in the range ²2inm < f < ²12mm. In one particular example, the lens may have a focal length of around ²2.1mm. It is ²envisaged that the lens may be a fisheye lens. As noted above, lenses having a ²large field of² .. view may generally be more prone to lens flare.²In accordance with embodiments of this invention, steps may be taken to reduce ²or ²eliminate lens flare in the images of the glue board captured by the camera ²66.²In particular, in accordance with embodiments of this invention, there is no ²line of sight²between the or each light source and the front element 60 of the lens of the ²camera 66. In this ²way, light from the or each light source can be prevented from reaching the ²front element 60 ²of the lens directly, and the light sources themselves may be kept out of the ²field of view of the ²camera 66. In accordance with embodiments of this invention, it envisaged that ²substantially²all of the light received by the lens of the camera 66 may thus be light ²reflected by the surface²of a glue board received in the glue board receiving space (as can be seen ²from the Figures, the ²camera 66 is located on the same side of the glue board receiving space as the ²one or more light ²sources 20A, 20B, so that the light received by the lens of the camera 66 for ²capturing images ²of a glue board received in the glue board receiving space comprises light ²from the one or more²light sources 20A, 20B reflected from the glue board (e.g. as opposed to light ²that is transmitted²through the glue board from a light source located on the opposite side of the ²glue board). This ²light would typically not be intense enough to produce lens flare. Although ²the images ²captured by the camera may include features of the trap other than the glue ²board (e.g. parts of²<DP=14>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²14²the rear cover plate 8 and / or the channels 12), the light reflected from these ²parts may also not ²be intense enough to produce lens flare. As described below these parts may ²also be anti-²reflective surfaces.²The cross section of Figure 9 illustrates the lack of a line of sight between ²the²fluorescent tubes 20A, 20B and the front element 60 of the lens 66 in the ²present example.²The approximate field of view of the camera 66 is represented by the dashed ²lines ²labelled C in Figure 9. In this example, the focal length of the camera is ²chosen so that the²images captured by the camera encompass substantially all of the rear cover ²plate 8, including²the glue board receiving space defined between the channels 12.²As represented by the dotted lines labelled A and B in Figure 9, in the ²present example ²the fluorescent tube 20A generally illuminates an upper part of the glue board ²received in the²glue board receiving space, while the fluorescent tube 20B generally ²illuminates a lower part²of the glue board received in the glue board receiving space. A central part ²of the glue board ²may be illuminated by both fluorescent tubes 20A, 20B. Note that each ²fluorescent tube 20A, ²20B is located outside the field of view of the camera 66.²In Figure 9, the optical axis of the lens is indicated by the dotted line ²labelled D. Note²that in the present example, the optical axis D of the lens is oriented ²substantially parallel to a ²surface normal of the glue board received in the glue board receiving space. ²This alignment of ²the lens and the glue board can help reduce perspective distortion (another ²undesirable artifact) ²in the captured images.²In the present example, each fluorescent tube 20A, 20B is located further away ²from ²the glue board receiving space along a direction substantially parallel to an ²optical axis D, than ²a front surface of the front element 60 of the lens. By placing the light ²sources of the trap 10 ²behind the front surface of the front element 60 of the lens in this way, it ²may be ensured that²the light sources are kept out of the field of view of the camera, thereby to ²prevent lens flare²from occurring.²<DP=15>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²It is also envisaged that the front surface to the front element 60 of the ²lens may be ²recessed slightly within the opening 52 in the surface 50 of the enclosure 80. ²In this way, the ²edges of the opening 52 may act as a hood for the lens, again to assist in ²preventing lens flare. ²The lens may also (or instead) be provided with a separate hood.²5²As noted above, a longitudinal axis of each fluorescent tube 20A, 20B in this ²example ²is oriented substantially parallel to a plane containing the glue board ²receiving space defined ²by the surface of the rear cover plate 8. This orientation of the fluorescent ²tubes 20A, 20B can ²allow the insect trap 10 to be made compact while also ensuring that no part ²of the fluorescent²10 tube 20A, 20B are visible to the camera.²Another measure that may be taken to prevent lens flare in images captured by ²the ²camera 66 may be to provide the light sources themselves with a shroud or ²hood. The shroud ²or hood may be configured (shaped and positioned) such that it does not ²inhibit light emitted²15 by the light source from reaching the glue board. On the other hand, the ²shroud or hood may ²be configured (shaped and positioned) to prevent light emitted from the light ²sources reaching ²the front element of the lens directly. This approach may be particularly ²useful in traps in ²which the confined space of the housing makes it difficult to position the ²light source(s) outside ²the field of view of the camera.²A further measure that may be taken to prevent lens flare in images captured ²by the ²camera 66 may be to ensure that at least some of the internal surfaces of the ²housing of the trap ²10 are anti-reflective surfaces. For instance, these surfaces may be coated ²with anti-reflective ²paint, or may be provided with some other form of matt coating. In one ²example, the surface(s)²may be matt plastic surfaces. These surfaces may include the surface 50, the ²surfaces of the ²channels 12, the inner surfaces of sidewalls 32, 34, the inner surfaces of the ²upper portion 6 ²and the lower portion 7, and the inwardly facing surface of the rear cover ²plate 8. This can ²help to prevent stray light from the light sources unintentionally reaching ²the front element 60 ²of the lens by reflection from surfaces inside the housing.²Accordingly, there has been described an insect trap and a method of using the ²same. ²The insect trap includes a housing. The insect trap also includes a glue board ²receiving space ²located inside the housing. The insect trap further includes one or more light ²sources for²<DP=16>²CA 03041394 2019-04-23²WO 2018 / 134550 PCT / GB2017 / 053315 ²16²attracting insects into the housing. The insect trap also includes a camera ²having a lens. The ²lens has a front element. The camera is positioned to capture images of a glue ²board when the ²glue board is received in the glue board receiving space. There is no line of ²sight between the ²or each light source and the front element of the lens. This may prevent light ²from the or each²5: light source reaching the front element directly. The method can include ²using an image ²captured by the camera to determine that a glue board received in the glue ²board receiving ²space needs to be replaced.²Although particular embodiments of the invention have been described, it will ²be²appreciated that many modifications / additions and / or substitutions may be made ²within the ²scope of the claimed invention.²

Claims

<DP=1>²17²What is claimed is:²1. An insect trap comprising:²a housing;²a glue board receiving space located inside the housing;²one or more light sources for attracting insects into the housing; and²a camera having a lens with a focal length in the range lmm < f < 18mm,²the lens having a front element, wherein the camera is positioned to capture ²images of²a glue board when said glue board is received in the glue board receiving ²space, and wherein²the light received by the lens of the camera for capturing images of the glue ²board comprises²light from the one or more light sources reflected from the glue board, and²wherein there is no line of sight between the or each light source and the ²front element²of the lens, for preventing light from the or each light source reaching the ²front element directly.²2. The insect trap of claim 1, wherein the or each light source is located ²a greater distance ²away from the glue board receiving space, along a direction substantially ²parallel to an optical ²axis of the lens, than a front surface of the front element of the lens.²3. The insect trap of claim 2, comprising a surface located inside the ²housing, wherein the ²surface faces the glue board receiving space, and wherein the lens of the ²camera is mounted in ²an opening in the surface.²4. The insect trap of claim 3, wherein said surface located inside the ²housing is a surface ²of an enclosure containing the camera and one or more further electronic ²components of the ²insect trap, and wherein the or each light source is located outside said ²enclosure.²5. The insect trap of any one of claims 2 to 4, wherein the optical axis of ²the lens is oriented ²substantially parallel to a surface normal of the glue board when the glue ²board is received in ²the glue board receiving space.²6. The insect trap of any one of claims 2 to 5, wherein a distance between ²the front surface ²of the front element and the glue board receiving space, along the optical ²axis of the lens, is in ²the range 50mm < d < 200mm.²<DP=2>²18²7. The insect trap of any one of claims 1 to 6, wherein the glue board ²receiving space ²substantially fills a field of view of the camera.²8. The insect trap of any one of claims 1 to 7, wherein the lens has a ²focal length in the ²range 2mm < f < 12mm.²9. The insect trap of any one of claims 1 to 8, wherein the lens is a ²fisheye lens.²10. The insect trap of any one of claims 1 to 9, wherein the or each light ²source comprises ²a fluorescent tube.²11. The insect trap of claim 10, wherein a longitudinal axis of the or each ²fluorescent tube ²is oriented substantially parallel to a plane containing the glue board ²receiving space.²12. The insect trap of any one of claims 1 to 9, wherein the or each light ²source comprises ²a light emitting diode.²13. The insect trap of any one of claims 1 to 12, wherein one or more ²surfaces located inside ²the housing are anti-reflective surfaces.²14. The insect trap of any one of claims 1 to 13, wherein the or each light ²source is ²configured to emit ultraviolet light having a peak wavelength of around 368nm.²15. A method of using the insect trap according to any one of claims 1 to ²14, the method²comprising:²using an image captured by the camera to determine that the glue board ²received in the²glue board receiving space needs to be replaced; and²replacing the glue board.²