NZ604670B - A sensor - Google Patents

Abstract

604670 Disclosed is a sensor (200) for sensing electromagnetic radiation from a viewing area. The sensor (200) includes a housing (120) having an aperture (126) for receiving electromagnetic radiation from the viewing area. A sensing region (131) is located within the housing (12) and is sensitive to electromagnetic radiation and operable to provide an electrical signal once a predetermined threshold condition is met. A focusing element (211) which forms part of the sensor (200) directs electromagnetic radiation from the viewing area onto the sensing region (131) and is formed of a flexible material. Focusing characteristics of the focusing element (211) may be modified to modify the viewing area of the sensor (200). Flexing means (310) is also included to modify the focusing characteristics of the focusing element (211) by flexing or bending the focusing element (211) without obscuring a central region of the focusing element (211). e to electromagnetic radiation and operable to provide an electrical signal once a predetermined threshold condition is met. A focusing element (211) which forms part of the sensor (200) directs electromagnetic radiation from the viewing area onto the sensing region (131) and is formed of a flexible material. Focusing characteristics of the focusing element (211) may be modified to modify the viewing area of the sensor (200). Flexing means (310) is also included to modify the focusing characteristics of the focusing element (211) by flexing or bending the focusing element (211) without obscuring a central region of the focusing element (211).

Description

PATENTS FORM NO. 5 s Ref: 39391NZ PATENTS ACT 1953 COMPLETE SPECIFICATION A SENSOR We, Schneider Electric (Australia) Pty Limited, 78 Waterloo Road, Macquarie Park, New South Wales, 2113, Australia, Australia do hereby declare this invention to be described in the following statement: PRIORITY DOCUlVIENTS The present application claims priority from Australian Provisional Patent ation No. 2011905218 entitled “A SENSOR” and filed on 14 December 2011. The t of this application is hereby incorporated by reference in its ty.

TECHNICAL FIELD The present invention relates to sensors for sensing electromagnetic radiation. In a particular form, the t invention relates to a motion sensor for sensing movement of an object in a viewing area of the sensor based on detecting infra-red (IR) radiation.

BACKGROUND Motion sensors are used primarily to monitor an area by detecting the presence of an object within a viewing area of the sensor. This may be in the context of securing an area from an intruder or to trigger the operation of a further device such as the case where a vehicle enters a viewing area and the operation of a garage door is then actuated to allow exit or entry from a building. There are many types of electromagnetic sensors ranging from those based on ing changes in the visual characteristics of an area, to those that detect changes in the ambient temperature of the viewing area using a passive red (PlR) detector to other examples that use microwave transceivers which rely on detecting the reflection of microwaves emitted from the transceiver.

Typically, a sensor will comprise a housing having an aperture through which electromagnetic radiation from the g area enters and a sensing region with associated electronic circuitry mounted within the housing. These housings are often substantially hermetically sealed to both increase reliability where the sensor may be subject to the outdoor environment, and/or to prevent tampering. In order to maximise the g area, the sensor will often incorporate a means for focusing electromagnetic radiation that functions to concentrate or focus electromagnetic radiation onto the sensing region of the sensor. The ation of the sensitivity of the g region and the optical characteristics of the focusing member then define the effective viewing area of the sensor.

Referring now to Figure 1, there is shown an example of an R based motion sensor 100 of the type that would typically be d on a wall or the like that operates by detecting changes in the ambient temperature. Motion sensor 100 comprises a housing 120 having a forward facing viewing aperture or window 110. Located in the housing is a HR or 130 having a sensing region 131 and associated electronic control circuitry 140 mounted in housing 120 responsible for both poweiing and processing the output from PR or 130. Typically, an electrical signal will be provided by electronic control circuit 140 based on the output of sensing region 131 once a threshold condition is met. This electrical signal may be relayed by cabling 150 which in this example also functions to power motion sensor 100.

To improve the viewing range of motion sensor 100, window 110 may incorporate a focusing element III that functions to focus IR radiation incident on window 110 onto sensing region 131 of PIR detector 130 which is located at the centre of window 110 as viewed from the front. The use of a focusing element 111 is generally employed to broaden or change the acceptance angle of the motion sensor 100 as compared to a sensor without a focusing element.

To ensure a t configuration, the focusing element 1 ll, as is the case here, is implemented as a substantially planar Fresnel lens t formed from a al such as plastic. In other es, the focusing t 111 may comprise an array of Fresnel lens elements. The focusing element 111 design is dependent on the desired g area of the sensor. In the case of where focusing element 111 consists of an array of Fresnel lens elements, rows of lens ts or even individual elements may be designed to cover specific portions or fields of view of the viewing area. In this way, the coverage of the viewing area may be tailored according to ements.

One disadvantage of the motion sensors incorporating such a focusing arrangement is that the viewing area cannot be easily modified. Accordingly, if the desired viewing area changes in practice from the ally specified viewing area of the motion sensor then a new sensor will have to be sourced. In some ces, there may also be a requirement to be able to change the viewing area of a motion sensor on a regular basis. There is therefore a need for a motion sensor whose viewing area may be readily modified.

SUMMARY In a first aspect, the present invention ingly provides a sensor for g electromagnetic radiation from a viewing area including: a housing having an aperture for receiving electromagnetic radiation from the viewing area; a sensing region located within the housing, the sensing region sensitive to electromagnetic radiation and operable to provide an electrical signal once a predetermined threshold condition is met; a focusing element forming part of the sensor to direct electromagnetic ion from the viewing area onto the sensing region, the focusing element formed of a flexible material wherein the focusing characteristics of the ng element may be modified to modify the viewing area of the sensor; and flexing means to modify the focusing characteristics of the focusing t by flexing or bending the focusing element without obscuring a central region of the focusing element.

In another form, the flexing means includes moveable abutment means that abut at least one edge of the focusing element to apply a flexing force.

In another form, the moveable abutment means includes an able screw that abuts a side edge portion of the focusing element.

In another form, the moveable abutment means is manually actuated.

In another form, the moveable abutment means is mechanically actuated.

In another form, the flexing means displaces the edges of the focusing element with respect to the central region of the focusing element which is fixed.

In another form, the flexing means displaces a central region of the ng element with t to fixed edges of the focusing element.

In another form, the flexing means includes pressure ation means to change the internal pressure of the g to cause the focusing element to flex or bend.

In another form, the pressure modification means includes an electronically controlled micro— pump d in the housing.

In another form, the focusing element includes a resilient frame or surround portion.

In another form, the viewing area of the sensor is modified by modifying the acceptance angle of the sensor.

In another form, the Viewing area of the sensor is modified by ing the range of the SCHSOI‘.

In another form, the sensor is operative to sense electromagnetic radiation in the infra—red range.

In another form, the sensor is a e infra-red (FIR) motion based sensor.

In r form, the focusing element is a Fresnel lens based element.

In a second aspect, the present invention accordingly provides method for modifying a viewing area of a sensor for sensing electromagnetic radiation, the sensor having a housing including an aperture to receive omagnetic radiation from the viewing area, the method including: focusing by a flexible focusing element the electromagnetic radiation from the viewing area onto a sensing region located in the housing, the sensing region ive to provide an electrical signal once a predetermined threshold condition is met; ing the focusing characteristics of the focusing element by flexing or bending the focusing element to modify the viewing area focused by the focusing element onto the sensor without obscuring a central region of the focusing element In another form, the sensor is operative to sense electromagnetic operation in the infra-red range.

In another form, the sensor is a passive infra-red (PIR) motion based sensor.

In another form, modifying the viewing area includes modifying the acceptance angle of the sensor.

In another form, the viewing area includes modifying the range of the sensor.

BRIEF PTION OF DRAWINGS Illustrative embodiments of the present invention will be discussed with reference to the accompanying drawings n: FIGURE 1 is a figurative perspective view of a prior art motion sensor; FIGURES 2a and 2b are top sectional views of a sensor in accordance with an rative embodiment of the present invention depicting the flexing or bending of the focusing element to change the focusing characteristics of the sensor; FIGURE 3 is a detailed sectional view of the flexing means illustrated in Figures 2a and 2b operative to flex or bend the focusing element; FIGURE 4 is a front ctive View of a ng element orating a frame portion; FIGURES 5a and 5b are schematic views depicting the change in viewing area as a result of changing the focusing characteristics of the sensor as depicted in Figures 2a and 2b; FIGURES 6a, 6b and 6c are top figurative views of different flexing arrangements in accordance with further illustrative embodiments of the present invention; and FIGURES 7a and 7b are top nal views of a sensor in accordance with another rative embodiment of the present invention.

In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS [003 8] For ease of description, the sensors embodying the present ion are described below in their usual assembled position as shown in the accompanying drawings and terms such as front, rear, upper, lower, horizontal, udinal etc., may be used with reference to this usual position. However, the sensors may be manufactured, transported, sold, or used in orientations other than that described and shown herein.

Referring now to s 2a and 2b, there are shown top sectional views of a sensor 200 according to an illustrative embodiment. Sensor 200 in this illustrative embodiment shares a number of common features with sensor 100 ing a g 120 having a forward facing viewing aperture or window 110 and a HR detector 130 having a sensing region 131 and associated electronic control circuitry mounted 140 in housing 120. However, ng element 211 is formed of a flexible material which in this embodiment is a e plastic and mounted within housing 120 to allow the focusing characteristics of focusing element 211 to be modified to modify the viewing area of sensor 200.

In this illustrative embodiment, sensor 200 includes flexing means 300 in the form of an arrangement that applies a flexing force to one or both sides of flexible focusing element 211 substantially in the plane of the focusing element 211. The application of this flexing force causes flexing or bending of focusing element 211 thereby increasing or decreasing its ure (as best seen Figure 2b). Flexing means 300 in this illustrative embodiment includes opposed moveable nt means in the form of adjustment screws 310 that each abuts a side edge portion 212 of focusing element 211.

Referring now also to Figure 3, each adjustment screw 310 includes a head portion 311 that is recessed within a countersunk region 121 of housing 120 and a screw threaded shank 312 that extends h a complementary screw threaded bore 122 in g 120 and terminates in a receiving region 313 that receives a side edge portion 212 of flexible ng element 211. As can be seen by reference to Figure 2b, by screwing adjustment screw 310 into countersunk region 121 a flexing force is applied to the edge of focusing element 211 that causes focusing element 211 to flex or bend dly thereby lly increasing the curvature of the focusing element. In this illustrative embodiment, the portion of housing 120 that surrounds ng element 211 further includes top and bottom arcuate cut-out portions 126 that define the outward limit of movement of focusing element 211.

To reduce this induced curvature, adjustment screw 310 may be unscrewed causing receiving region 313 to move outwardly and reduce the flexing force applied to side edge portions 212 of focusing element 211. As would be appreciated by those of ordinary skill in the art, one edge of focusing element 211 may be fixed to housing 120 and the flexing force applied to only one side edge portion 212.

Furthermore, while in this illustrative embodiment a flexing force has been applied to one or more of the side edges of focusing t 211 depending on requirements one or more of the top and/or bottom edges may be so manipulated. In another illustrative embodiment, a transparent window not having any focusing characteristics may be mounted behind focusing element 211 and covering window 110 to maintain the sealing characteristics of housing 120 if desired.

While in the illustrative embodiment depicted in Figures 2a and 2b, adjustment screw 310 is manually actuated, in another illustrative embodiment adjustment screw 310 may be mechanically actuated by an electric motor (not shown) such as a stepper motor which functions to rotate adjustment screw 310 in either direction as required. The stepper motor in this illustrative embodiment would be both powered and controlled by associated controller circuitry forming part of the electronic control circuitry 140 d in the housing 120. In this embodiment, an external ical switch or or may be employed to operate stepper motor and in turn modify the viewing area of sensor 200.

Referring now to Figure 4, there is shown a focusing element 211 that includes a ent frame or surround portion 213 that ons to improve the flexing or bending characteristics of focusing element 211. Frame portion 213 while still flexible is comparatively rigid compared to the central portion 214 of focusing element 211. This resistance to the flexing or bending force applied by the flexing means 300 is able to provide a r level control over the curvature of focusing element 211 should this be required.

Referring now to Figures 5a and 5b, there are shown tic views of sensor 200 depicting the associated viewing areas 180, 180’ corresponding to the configurations depicted in Figures 2a and 2b. As shown in Figure 5a, sensor 200 in its original configuration corresponding to Figure 2A has a viewing area defined in this illustrative embodiment by ance angle or and range (1’. It is a feature of infra-red motion sensors of the type referred to in these illustrative ments that a decrease in the ance angle or results in an increase of range (1 of the viewing area. As shown in Figure 5b, increasing the ure of focusing element 211 results in sensor 200’ having a decreased acceptance angle 011’ but an increased range (1’ which is sufficient to now encompass object 290 within modified viewing area 180’.

As would be appreciated by those of ordinary skill in the art, other types of sensors may have a ent relationship between the degree of flexing of focusing element and the resulting change in the viewing area as a result of this flexing or bending.

Referring now to Figures 6a, 6b and 6C there is shown in figurative form different flexing arrangements to flex or bend focusing element 21 1. In Figure 5a, focusing t 21 l is fixed on its side edge portions 212 to housing 120. Rotatable cam element 310 is positioned within housing 120 at the top (and/0r bottom) of focusing element 211 and upon rotation exerts a force on a top (and/or bottom) central region 219 of focusing element 211 which is held in tension with respect to the fixed side edge portions 212. In this manner, cam element 310 is operable to cause focusing element 211 to flex or bend outwardly to a degree ined by the amount of on of cam element 211.

Figure 6b depicts another flexing arrangement or means wherein the top (and/or bottom) central region 219 of focusing element is fixed to housing 120 and includes two nt screws 320 operable to abut against the front edge portion 217 of focusing element 211. Abutment screws 320 may then be rotated to exert a front force causing each front edge portion 217 to be displaced ve to the fixed central region 219 resulting in flexing or g of focusing element 211 and an associated increase in the ure of focusing element 211.

Figure 6c depicts yet another flexing arrangement or means similar to the arrangement depicted in Figure 5b but d involving two tensioning elements 330 that exert a tensioning force on each rear edge portion 218 of focusing element 211 again causing each edge portion 218 to be displaced relative to the fixed central region 219 to cause flexing or bending of focusing element 211 and increase the ure of ng element 211.

In each of the arrangements depicted in Figures 6a, 6b and 6c the curvature of focusing element 211 may be reduced by reversing the operation employed initially to increase the curvature. As previously bed, instead of being manually actuated each of the flexing means may be actuated by an riately controlled stepper motor or the like.

Referring now to Figure 7a and 7b, there is shown a top sectional View of a sensor 300 according to a further illustrative embodiment. In this embodiment housing 120 is hermetically sealed and again focusing element 211 is formed of a flexible material mounted at its periphery within housing 120. In this embodiment, sensor 300 includes a flexing means in the form of pressure modification means 380 which functions to change the internal pressure within housing 120. An increase in the internal pressure of housing 120 causes focusing element 211 to flex or bend outwardly, y increasing its curvature and changing the viewing area of sensor 300 as usly described with respect to s 5a and 5b.

In this embodiment, the pressure modification means is a micro-pump 381 controlled by electronic circuitry forming part of electronic control circuit 140. In this manner, an external switch (not shown) may be used to increase or decrease the internal pressure of housing 120 and as a result either increase or decrease the curvature of focusing t 211 respectively.

In any of the above embodiments, focusing t 211 may be a l lens based t comprised of a single Fresnel lens element or including an array of Fresnel lens elements depending on configuration requirements.

While the t illustrative embodiments have been described in relation to sensors operating in the infra-red band (i.e. 0.74pm to 300 um) it will be readily apparent that consistent with the principles described herein that the present invention will have application to sensors operating in other wavelength bands.

Throughout the specification and the claims that , unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the ion of a stated integer or group of integers, but not the exclusion of any other r or group of integers. [0055} The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any fonn of suggestion that such prior art forms part of the common general knowledge.

It will be appreciated by those skilled in the an that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred ment with regard to the particular elements and/or es described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

Claims (20)

1. A sensor for sensing electromagnetic ion from a viewing area including: a housing having an aperture for receiving electromagnetic radiation from the viewing area; a sensing region located within the housing, the sensing region ive to electromagnetic radiation and operable to provide an electrical signal once a ermined threshold condition is met; a focusing element forming part of the sensor to direct electromagnetic radiation from the viewing area onto the sensing region, the focusing element formed of a flexible material wherein the focusing characteristics of the focusing element may be modified to modify the viewing area of the ; and flexing means to modify the focusing characteristics of the focusing element by flexing or bending the focusing element Without ing a central region of the focusing t.

2. The sensor of claim 1, wherein the flexing means includes moveable abutment means that abut at least one edge of the focusing element to apply a flexing force.

3, The sensor of claim 2, wherein the moveable abutment means includes an adjustable screw that abuts a side edge portion of the focusing element.

4. The sensor of claim 2 or 3, wherein the moveable nt means is manually actuated.

5. The sensor of claim 2 or 3, wherein the moveable abutment means is mechanically actuated.

6. The sensor of claim 1, wherein the flexing means displaces the edges of the focusing element with respect to the central region of the focusing element which is fixed.

7. The sensor of claim 1, wherein the flexing means displaces the central region of the ng t with respect to fixed edges of the focusing element.

8. The sensor of claim 1, wherein the flexing means es pressure modification means to change the internal pressure of the housing to cause the focusing element to flex or bend.

9. The sensor of claim 8, wherein the pressure modification means includes an electronically controlled micro—pump located in the housing.

10. The sensor of any one of claims 1 to 9, n the focusing element includes a resilient frame or surround portion.

11. The sensor of any one of the preceding claims, n the g area of the sensor is modified by modifying the acceptance angle of the sensor.

12. The sensor of any one of the preceding claims, n the viewing area of the sensor is modified by modifying the range of the sensor.

13. The sensor of any one of the preceding claims, where the sensor is operative to sense omagnetic ion in the infra-red range.

14. The sensor of claim 13, wherein the sensor is a passive infra-red (PIR) motion based sensor.

15. The sensor of any one of the preceding claims, wherein the focusing element is a Fresnel lens based element.

16. A method for modifying a Viewing area of a sensor for sensing electromagnetic radiation, the sensor having a housing including an aperture to receive electromagnetic radiation from the viewing area, the method ing: focusing by a flexible focusing element the electromagnetic radiation from the Viewing area onto a sensing region d in the housing, the sensing region operative to provide an electrical signal once a predetermined threshold ion is met; modifying the focusing characteristics of the focusing element by flexing or g the focusing element to modify the Viewing area focused by the focusing element onto the sensor without obscuring a central region of the focusing element.

17. The method of claim 16, n the sensor is operative to sense electromagnetic operation in the infra-red range.

18. The method of claim 17, wherein the sensor is a passive infra-red (PIR) motion based sensor.

19. The method of any one of claims 16 to 18, wherein modifying the viewing area includes modifying the acceptance angle of the sensor.

20. The method of any one of claims 16 to 18, wherein the viewing area includes modifying the range of the sensor.