GB2602792A

GB2602792A - Sensor cover

Info

Publication number: GB2602792A
Application number: GB2100137.5A
Authority: GB
Inventors: Blick Vivian; Norris Neil
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-01-06
Filing date: 2021-01-06
Publication date: 2022-07-20
Also published as: GB202100137D0

Abstract

A sensor cover 16 for a PIR sensor (10, Fig. 1) comprises at least a first curved cover member 18 which is mounted about a pivotal axis. In use, the curved cover member is movable between different positions about the pivotal axis for partially covering a sensor. There may be a second cover member 20 mounted to the pivotal axis. One or both cover member may be partly spherical or spherical lune shaped. A mounting ring 22 may be provided for the cover(s) with upwardly extending circular flange 32. Flange 32 may include two diametrically opposed protrusions (34, Fig. 3) with circular apertures (36, Fig. 3) for receiving stub axles 26. At least one cover may have a pair of diametrically extending stub axles 26 which engage apertures 36. Second cover member 20 may feature diametrically opposing apertures for engaging stub axles 26 of cover 18. Covers 18 and 20 may rotate independently relative to mounting ring 22. A bezel may retain the ring 22 in position. At least cover 18 can rotate about 2 orthogonal axes. There may be an audible alert device comprising a PIR sensor for detecting a person. A sensing device may sense persons or animals.

Description

SENSOR COVER

The present invention relates to a sensor cover and particularly but not exclusively to a sensor cover for a passive infra-red (PIR) sensor.

BACKGROUND TO THE INVENTION

PI R sensors are routinely used to identify the presence of a person or animal, enabling the triggering of an electrical device, for example, a light, camera or an alarm. A PIR sensor is often built into a device. To set the field of operation of the sensor, the device is mounted pointing directly to the required position. However, a problem of using a FIR sensor is that there is no way of focussing the sensing once in position.

In certain circumstances, the device can be triggered more frequently than desired, because the angular range of detection of the sensor, that is, the angular spread or field of detection, is too large. This is particularly so with a device intended for use in both wide and narrow spaces. For example, when an audible alert device for detecting the presence of a person and issuing an audible warning is positioned in a narrow shop entrance with one-way markings on the ground, it may be desirable to only detect people entering the shop. It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to a first aspect of the present invention there is provided a sensor cover for a PIR sensor comprising at least a first curved cover member, the curved cover member being mounted about a pivotal axis, in use, the curved cover member being movable between different positions about the pivotal axis for partially covering a sensor beneath the cover.

Advantageously, the cover member can be rotated to a desired position, thereby shielding a desired part of the field of sensing of the sensor beneath. This enables the angular field of sensing to be directed to a particular position.

A second curved cover member may be mounted to the pivotal axis.

The use of a second cover member enables the field of sensing to be further reduced or tailored, if desired.

The or each curved cover member may be part spherical. The or each curved cover member may include the shape of a spherical lune.

The spherical form of the cover members enables them to cover the senor beneath and to rotate around the sensor unimpeded.

A mounting ring may be provided for mounting the or each curved cover member.

The mounting ring is preferably circular and has an upwardly extending circular flange for mounting the or each curved cover member.

The flange may include two diametrically opposed protrusions, the protrusions having circular apertures for receiving axle stubs.

A pair of diametrically extending stub axles may be provided on the at least first curved cover member, which engage in the circular apertures of the protrusions.

Conveniently, the stub axles of the first cover member are able to rotate in the apertures in the protrusions on the mounting ring.

The second curved cover member may be formed with a larger diameter curve to fit over the at least one cover member. This enables the cover members to be stacked, with the second cover member lying over the lower cover member, thereby only restricting the field of sensing by the angular width of one of the cover members. They may be substantially the same size.

The second curved cover member may have diametrically opposing apertures for engagement on the stub axles of the at least one coved member.

The second cover member rotates around the stub axles of the first cover member. In other words, the first and second cover members may rotate independently relative to the mounting ring.

A circular bezel may fit over the mounting ring for retaining the mounting ring in a position around a sensor. The mounting ring may rotate to different angular positions relative to the bezel.

Advantageously the bezel connects the mounting ring to a device, around a sensor to be directionally shielded. The bezel allows the mounting ring to be rotated about an axis perpendicular to the plane of the base of the mounting ring. In other words, it enables another range of movement. For example, the first and second cover members may be set to shield the left side of a vertically disposed sensor, but if the mounting ring is rotated 90 degrees anti-clockwise, the lower part of the sensor may be shielded. This may be useful, for example, to avoid detection of pets, such as dogs.

The at least first cover member may rotate about two orthogonal axes and in fact both cover members may rotate about two orthogonal axes.

VVhen the mounting ring is rotated, both of the cover members are rotated at the same time, since they are both mounted to the protrusions by the stub axles.

In another aspect of the invention, an audible alert device may be provided comprising a FIR sensor for detecting the presence of a person, and a sensor cover according to the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows perspective front view of a cover of the invention mounted to a voice alert device; Figure 2 shows the cover and device of Figure 1 from a lower perspective view; Figure 3 shows a perspective exploded view of the component parts of the cover of Figure 1; Figure 4 shows a perspective view of the assembled cover of Figure 1; Figure 5 shows different operational position of the cover of Figure 1; Figure 6 shows different operational positions of the cover of Figure 1; and Figure 7 shows possible angles of sensing using the cover of Figure 1. DESCRIPTION OF PREFERRED EMBODIMENTS Referring firstly to Figures 1 and 2, an audible alert device is indicated generally at 10.

The device 10 has a proximity sensor 12, particularly a passive infra-red (PIR) sensor, which detects the presence of a person. When a person is detected, the device 10 plays a pre-recorded alert message though speaker 14.

The device 10 is primarily intended to sit in a sanitising station to remind people to sanitise their hands in the battle against the COVID-19 pandemic caused by the SARSCOV-2 virus.

PIR detectors are typically designed to have a large field of detection, which is particularly useful for use in lighting and alarm installations. However, in the current device 10, this can be dis-advantageous and it is desirous to be able to focus the field of detection or narrow its' scope.

To achieve this, a sensor cover 16 is mounted around the PIR sensor 12. Referring also to Figures 3 and 4, the sensor cover 16 includes first and second curved cover members 18, 20, a mounting ring 22 and a circular bezel or cover member 24. The first and second cover members 18, 20 are part spherical and take the general shape of a spherical lune.

The cover members 18,20 rotate about a first axis described further below.

A pair of stub axles 26, cylindrical pins, extend from either side of the first cover member 18 lying substantially on the first axis of the spherical form.

A pair of circular apertures 27 are disposed on either side of the second cover member 20. The pair of circular apertures are shaped, sized and positioned so as to receive the stub axles 26 on the first axis.

A lip 28 is disposed on the peripheral edge of the first cover member 18. The lip 28 provides a finger grip to facilitate movement of the cover member 18.

A recess 30 is disposed in the outer peripheral edge of the second cover member 20. The recess 30 is on the same side as the lip 28 on the first cover member 20. The recess 30 may be sized and shaped so as to receive the lip 28.

The second cover member 20 has a larger diameter curve allowing it to fit over at least a portion of the first cover member 18. The recess 30 may be sized and shaped to receive the lip 28. This arrangement allows for a nested arrangement of cover members 18,20.

An upwardly extending flange 32 extends from a substantially annular base 33 of the mounting ring 22. The upwardly extending flange 32 is spaced from a peripheral edge of the substantially circular base 33.

Two diametrically opposed protrusions 34 are included in the upwardly extending flange. A circular aperture 36 is disposed in each diametrically opposed protrusion and are sized and shaped to receiving a portion of a stub axle 26.

The arrangement of circular apertures 27,36 and stub axles 26 allow both the first and second cover members 18,20 to rotate about the first axis.

In use, the PI R sensor 12 is disposed in the hole 35 formed in the annular base 33.

Each cover member 18,20 may independently rotate about the first axis, apart from when the lip 28 interfaces with the recess 30 of the second cover member 20.

A central bore 38 is provided in the circular bezel or cover member 24. The central bore 38 is sized and shaped so as to receive the mounting ring 22. A first portion of the central bore 38 has slightly larger diameter than the upwardly extending flange 32 which allows the flange to be concentrically disposed in the central bore 38. A second portion of the central bore 38 has slightly larger diameter than the base 33. The second portion has a larger diameter than the first portion.

In use, the circular bezel or cover member 24 is disposed over the mounting ring 22 and retains it in position.

The mounting ring 22 may rotate relative to the bezel or cover remember 24. That is to say that the mounting ring rotates about a second axis substantially orthogonal to the first axis. Figure 5 shows some of the possible operational position of the cover when the mounting ring is rotated about bezel. This additional degree of rotation provides an additional way to tailor the field of detection.

Figure 6 show some of the possible operational positions of the cover 16, when the first and second cover member 18,20 are rotated about the first axis. Each column shows a different operational position of the cover 16; the rows in each column show plan and side views of the cover in the operational position. For example, the first column shows the cover 16 being disposed to one side with the first cover member nested underneath the second cover member. Each operational position of the cover 16 provides a different field of detection for a PIR sensor 12, examples are shown in Figure 7 with the field of detection shown in dotted lines 40.

Each cover member 18,20 covers substantially 60 degrees of arc. Hence when nested the detection arc reduces from 180 degrees to around 120 degrees. When both covers are fully restricting detection, then the arc of detection is only around 60 degrees. If the cover members are, for example, centrally disposed, then the detection area may be 30 degrees either side of the un-nested cover members.

It will be appreciated that by careful positioning of the cover members 18,20, chosen arcs of detection can be created and directed to a desired position. The further ability to rotate the cover members together as shown in Figure 5 can be useful for directing the arc of detection, for example, downwardly for pets or other animals, or upwardly, for example, to cover stairs or upper openings such as windows.

Whilst the cover member is described for use with a PIR in a voice alert device, it will be appreciated that the cover member can be used in any desired PIR detection arrangement as desired, where the arc or field of detection requires adjustment.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS1 A sensor cover for a PIR sensor comprising at least a first curved cover member, the curved cover member being mounted about a pivotal axis, in use, the curved cover member being movable between different positions about the pivotal axis for partially covering a sensor beneath the cover.
2 A sensor cover as claimed in claim 1, in which a second curved cover member is mounted to the pivotal axis.
3. A sensor cover as claimed in claim 1 or claim 2, in which the or each curved cover member is part spherical.
4. A sensor cover as claimed in claim 3, in which the or each curved cover member includes the shape of a spherical lune.
5. A sensor cover as claimed in any preceding claim, in which a mounting ring is provided for mounting the or each curved cover member.
6 A sensor cover as claimed in claim 5, in which the mounting ring is circular and has an upwardly extending circular flange for mounting the or each curved cover member.
7 A sensor cover as claimed in claim 6, in which the flange includes two diametrically opposed protrusions, the protrusions have circular apertures for receiving axle stubs.
8 A sensor cover as claimed in claim 7, in which a pair of diametrically extending stub axles are provided on the at least one curved cover member, which engage in the circular apertures of the protrusions.
9. A sensor cover as claimed in claim 8, when dependent on claim 2, in which the second curved cover member is formed with a larger diameter curve to fit over the at least one cover member.
10. A sensor cover as claimed in claim 9, in which the second curved cover member has diametrically opposing apertures for engagement on the stub axles of the at least one coved member.
11. A sensor cover as claimed in claim 10, in which the first and second cover members can rotate independently relative to the mounting ring.
12. A sensor cover as claimed in any preceding claim, when dependent on claim 5, in which a circular bezel fits over the mounting ring for retaining the mounting ring in a position around a sensor.
13. A sensor cover as claimed in claim 11, in which the mounting ring can rotate to different angular positions relative to the bezel.
14. A sensor cover as claimed in any preceding claim in which the at least first cover member can rotate about two orthogonal axes.
15. An audible alert device comprising a PIR sensor for detecting the presence of a person, and a sensor cover as claimed in any preceding claim.
16. A sensing device comprising a PIR sensor for detecting the presence of a person or animal, and a sensor cover as claimed in any one of claims 1 to 14.