ANTI-LIGATURE DEVICE

Abstract

An anti-ligature device for attachment to an edge of a door leaf, the anti-ligature device having a proximity sensor arranged to detect a ligature secured around the anti-ligature device. The proximity sensor may be arranged to detect a weight being suspended from a ligature secured around the anti-ligature device. The sensitivity of the proximity sensor may be user-controllable, such that the anti-ligature device can be calibrated once affixed to the door leaf.

Claims

1. An anti-ligature device for attachment to an edge of a door leaf, the anti-ligature device comprising a proximity sensor arranged to detect a ligature secured around the anti-ligature device.

2. The anti-ligature device according to claim 1, wherein the proximity sensor is housed within the anti-ligature device.

3. The anti-ligature device according to claim 1, further comprising a target opposing the proximity sensor, wherein the target is moveable relative to the proximity sensor when a ligature is secured around the anti-ligature device, and wherein the proximity sensor is configured to detect a change in proximity of the target.

4. The anti-ligature device according to claim 3, wherein the target is moveable towards the proximity sensor when a ligature is secured around the anti-ligature device.

5. The anti-ligature device according to claim 4, wherein the target is resiliently biased away from the proximity sensor.

6. The anti-ligature device according to claim 3, wherein the target is moveable between a first position in which it is separated from the proximity sensor by a first distance, and a second position in which it is separated from the proximity sensor by a second distance.

7. The anti-ligature device according to claim 6, wherein the proximity sensor is configured to detect when the separation between the target and the proximity sensor crosses a predetermined threshold distance, wherein one of the first and second distances is larger than the threshold distance, and the other of the first and second distances is smaller than the threshold distance.

8. The anti-ligature device according to claim 7, wherein the target is resiliently biased into one of the first position and the second position.

9. The anti-ligature device according to claim 8, wherein the target is moveable into the other of the first position and the second position when a ligature is secured around the anti-ligature device.

10. The anti-ligature device according to claim 3, wherein the proximity sensor is an inductive proximity sensor, and the target is a metal target.

11. The anti-ligature device according to claim 3, comprising a first part for attachment to a door leaf, and a second part coupled with the first part; wherein the proximity sensor is connected to one of the first part and the second part; and the other of the first part and the second part comprises the target.

12. The anti-ligature device according to claim 11, wherein the part comprising the target is configured to float relative to the other part such that the target is moveable relative to the proximity target.

13. The anti-ligature device according to claim 12, wherein the target is moveable between a first position in which it is separated from the proximity sensor by a first distance, and a second position in which it is separated from the proximity sensor by a second distance; wherein the part comprising the target is resiliently biased into one of the first position and the second position.

14. The anti-ligature device according to claim 12, wherein the second part is biased away from the first part.

15. The anti-ligature device according to claim 11, wherein the first and second parts define an enclosure within which the proximity sensor is located.

16. The anti-ligature device according to claim 1, comprising a first plurality of proximity sensors.

17. The anti-ligature device according to claim 1, wherein the anti-ligature device is elongate and configured for attachment along at least a portion of an edge of a door leaf.

18. The anti-ligature device according to claim 1, further comprising an opening for receiving a lock element.

19. A door leaf comprising an anti-ligature device according to claim 1 attached to an edge thereof.

20. The door leaf according to claim 19, wherein the anti-ligature device extends along at least a portion of the edge.

21. The door leaf according to claim 20, comprising a further anti-ligature device according to claim 3 attached to a further edge thereof.

22. A door system comprising a door leaf pivotally attached to a door frame, and further comprising an anti-ligature device according to claim 1 attached to one of a top edge, bottom edge, and closing edge, of the door leaf.

23. The door system according to claim 22, comprising a further anti-ligature device according to claim 3 attached to another of the top edge, bottom edge, and closing edge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Examples of the present disclosure will now be described, by way of example only, with reference to the accompanying figures, in which:

[0036] FIG. 1 shows a cross-sectional view of an anti-ligature device according to the present disclosure;

[0037] FIG. 2 shows an exploded perspective view of the anti-ligature device of FIG. 1;

[0038] FIG. 3 shows an assembled perspective view of the anti-ligature device of FIGS. 1 and 2;

[0039] FIG. 4 shows the anti-ligature device of FIG. 1 in a first compressed state;

[0040] FIG. 5 shows the anti-ligature device of FIG. 1 in a second compressed state;

[0041] FIG. 6 shows an alarm system for use with the anti-ligature device of FIG. 1;

[0042] FIGS. 7A-7C show door systems according to the present disclosure;

[0043] FIG. 8 shows a perspective view of a further anti-ligature device, configured for use with a lock element;

[0044] FIG. 9 shows a cross-sectional view of the anti-ligature device of FIG. 8, including an electromagnetic lock element; and

[0045] FIG. 10 shows a cross-sectional view of a further anti-ligature device, configured for use with a mechanical lock bolt.

[0046] Like reference numerals are used for like components throughout the drawings and detailed description.

DETAILED DESCRIPTION

[0047] FIG. 1 shows an end view of an anti-ligature device 100 according to the present disclosure, attached to an edge of a door leaf 102. The anti-ligature device includes a first part 104 attached to the door leaf 102, and a second part 106 coupled with the first part 104. The coupling between the first part 104 and the second part 106 is such that the second part 106 floats relative to the first part 104. This is achieved by a bulbous protrusion 108 which is received within a channel 110 of the first part 104. Because of the bulbous end to the protrusion 108, the second part 106 cannot completely separate from the first part 104. In particular, the inward facing lip 112 of the channel 110 prevents separation of the second part 106 from the first part 104. Therefore, not only is the second part 106 able to float relative to the first part 104, but its movement away from the first part 104 is limited. In other words, the travel of the second part 106 relative to the first part 104 is limited.

[0048] A piece of resiliently deformable foam 114 is located within the channel 110, and arranged to bias the second part 106 away from the first part 104. Accordingly, in its rest configuration (i.e. in which no external forces are applied, such as by a ligature), as illustrated in FIG. 1, the second part 106 is spaced from the first part 104. As the user will understand, a spring could be used instead of foam.

[0049] Attached to the first part 104 of the anti-ligature device 100 are a first inductive proximity sensor 116A, and a second inductive proximity sensor 116B. The inductive proximity sensors 116A, 116B face the second part 106. The inductive proximity sensors 116A, 116B are thus configured to detect the separation distance from the second part 106. Moreover, they are configured to detect changes in the separation distance.

[0050] In effect, the second part 106 provides an inductive target for the inductive proximity sensors 116A, 116B to detect. The second part 106 is aluminium, so that it is detectable by the inductive proximity sensors 116A, 116B. As the reader will understand, any conductor could be used for the target/second part. Thus, when the second part 106 moves towards the inductive proximity sensors 116A, 116B, the inductive sensors can detect the change in separation distance from the second part 106. This is described in more detail below, in relation to FIGS. 4 and 5.

[0051] Referring still to FIG. 1, upturned edges of each of the first part 104 and the second part 106 mean that the inductive proximity sensors 116A, 116B are concealed/enclosed within the anti-ligature device 100, even when the second part 106 is spaced from the first part 104 as shown in FIG. 1.

[0052] FIG. 2 shows an exploded view of the anti-ligature device 100 according to the present disclosure. As can be seen from FIG. 2, the anti-ligature device 100 and its components are elongate, for attachment along the edge of the door leaf 102. Eight inductive proximity sensors 116A-116H are provided attached to the first part 104. As the reader will understand, a different number of proximity sensors could be used. Inductive proximity sensors 116A, 116C, 116E and 116G are located on a first lateral side of the anti-ligature device 100. Inductive proximity sensors 116B, 116D, 116F, 116H are located on a second lateral side of the anti-ligature device 100. Inductive proximity sensors 116A, 116B, 116C, 116D are located at a first longitudinal end of the anti-ligature device. Inductive proximity sensors 116E, 116F, 116G, 116H are located at a second longitudinal end of the anti-ligature device. Inductive proximity sensors 116B, 116A, 116H, 116G are respectively located at the four corners of the anti-ligature device 100. Screws 118 are used to secure the second part 106 to the first part 104. An end-plate 120 is affixed to each end of the anti-ligature device 100, to conceal the contents of the anti-ligature device 100.

[0053] FIG. 3 shows an assembled view of FIG. 2. As can be seen, the internals of the anti-ligature device 100 are completely concealed.

[0054] Each of the first part 104 and the second part 106 have a uniform cross-section. They are aluminium, and formed by aluminium extrusion.

[0055] As the skilled person will appreciate, the anti-ligature device 100 can have a variety of dimensions, dependent on the size of the door leaf 102 to which it is to be fitted. Nonetheless, dimensions of an example anti-ligature device 100 will now be provided for illustrative purposes.

[0056] The anti-ligature device 100 of FIG. 1 has a length, in the longitudinal direction, of 1 m. That is to say, the first and second parts 104, 106 each have a length of 992 mm, such that the entire anti-ligature device 100 has a length of 1 m when the end-plates 120 are fitted.

[0057] The anti-ligature device 100 has an outer width (in the horizontal direction when fitted to a door) of 44 mm. Thus, the pressure monitor having these dimensions is particularly suited for attachment to a door leaf having an edge that is 1 m long, and a thickness of 44 mm.

[0058] In the uncompressed configuration as shown in FIG. 1, the separation distance between the inductive proximity sensors 116A, 116B and the second part 106 is 2.75 mm. Each of the inductive proximity sensors 116A, 116B is configured to detect when the separation distance from the second part 106 drops below 2 mm. For example, the sensors may activate an alert when the distance drops below 2 mm. This is described in more detail in relation to FIG. 6 below. In short, each of the inductive proximity sensors is sensitive to a movement of just 0.75 mm in the second part 106. In other words, sensitivity is high. In some examples, the sensitivity may be user-configurable to avoid false positives and false negatives. For example, the sensitivity may be calibrated once the anti-ligature device 100 has been installed.

[0059] Referring now to FIGS. 4 and 5, when a force F1 or F2 is applied to the second part 106 (e.g. by a ligature looped around the second part 106), the second part 106 is caused to move towards the first part 104. The foam 114 is compressed, and the separation distance between the second part 106 (i.e. the target) and the inductive proximity sensor(s) decreases. Thus, the ligature can in effect be detected. As shown in FIG. 4, even if the force is unevenly applied to the second part 106, thereby resulting in an asymmetric depression of the second part 106, the first inductive proximity sensor 116A can nonetheless still detect the movement—even if the second inductive proximity sensor 116B cannot. Therefore, the anti-ligature device 100 is robust.

[0060] When the force F1 or F2 is removed, the foam will return to its original shape, thereby returning the anti-ligature device to the configuration shown in FIG. 1.

[0061] The inductive proximity sensor(s) 116 used may be IFFM 08P17A6/L inductive sensors from Baumer. The inductive proximity sensor 116 is configured to produce a binary output. In particular, each sensor is configured to activate an LED when the separation distance from the target drops below 2 mm. As the reader will understand, different proximity sensors could equally be used. Accordingly, if the separation distance between the second part 106 and any one of the inductive proximity sensors 116A-116H of FIG. 1 drops below 2 mm, the LED(s) associated with the proximity sensor(s) in question will activate.

[0062] FIG. 6 is a schematic diagram showing an alarm system for use in with the anti-ligature device of FIG. 1. As shown, each inductive sensor 116A-116H is connected, by fibre-optic cable, to alarm processing unit 700. In effect, the alarm processing unit 700 operates as an OR gate, such that if the input from any one of the inductive sensors 116A-116H indicates that the separation distance has dropped below 2 mm (i.e. if any one of the LEDs is turned on), then a signal is issued to activate the alarm 702. The alarm processing unit may be located within the anti-ligature device 100, or may be external from the anti-ligature device 100.

[0063] FIGS. 7A-7C show door systems according to the present disclosure. Each door system includes a door leaf 102 pivotally attached to a door frame 103. In the door system of FIG. 7A, an anti-ligature device 100 according to FIG. 1 is attached to a top edge thereof. In the door system of FIG. 7B, a first anti-ligature device 100 according to FIG. 1 is attached to a top edge thereof, and a second anti-ligature device 100′ according to FIG. 1 is attached to a closing edge thereof. In the door system of FIG. 7C, a first anti-ligature device according to FIG. 1 is attached to a top edge thereof, a second anti-ligature device 100′ according to FIG. 1 is attached to a closing edge thereof, and a third anti-ligature device 100″ according to FIG. 1 is attached to a bottom edge thereof.

[0064] FIG. 8 shows a further example of an anti-ligature device 800 according to the present disclosure. The anti-ligature device 800 is the same in configuration and operation as the anti-ligature device 100. However, the anti-ligature device 800 further includes an opening 802 for accommodating a lock, for example an electromagnetic lock element.

[0065] FIG. 9 shows an example of the anti-ligature device 800, in which an electromagnetic lock element 804 is provided in the opening. FIG. 9 is viewed along direction A as shown in FIG. 8. The electromagnetic lock element is mounted to the base plate (first part 104). The opening 802 is provided in the surface plate (second part 106), and the electromagnetic lock plate 804 extends through the opening 802. The electromagnetic lock element may be configured to float relative to the first part 104. For example, the electromagnetic lock element may be resiliently biased away from the first part 104 by a compressible element 806, e.g. a helical spring. In use, the electromagnetic lock element 804 will be arranged to coincide with a cooperating electromagnetic lock element coupled to the adjacent door frame.

[0066] FIG. 10 shows a further example of an anti-ligature device 1000 according to the present disclosure. Again, the anti-ligature device 1000 is the same in configuration and operation as the anti-ligature device 100. The device 1000 includes a first opening 1002a in the first part 104, and a second opening 1002b in the second part 106. The first and second openings 1002a, 1002b are aligned, so as to receive a mechanical lock bolt (not show) therethrough when the lock bolt is in a thrown position. Accordingly, a lock bolt (not shown) can be thrown through the openings 1002a, 1002b of the anti-ligature device 1000, in order to lock the door.

[0067] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to a specific example implementation, it will be recognized that the disclosure is not limited to the implementations described, but can be practiced with modification and alteration insofar as such modification(s) and alteration(s) remain within the scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.