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 comprising: an inductive proximity sensor; and an electrical conductor target resiliently biased away from the inductive proximity sensor; wherein the electrical conductor target is moveable towards the inductive proximity sensor in response to a force from a ligature on the anti-ligature device; wherein the inductive proximity sensor is configured to detect when a separation distance between the electrical conductor target and the inductive proximity sensor is less than a predetermined threshold distance to thereby detect that a ligature is applying force to the anti-ligature device.

2. The anti-ligature device according to claim 1, wherein the anti-ligature device is configured to attach to an edge of a door leaf, and the inductive proximity sensor is located within a tamper-resistant housing.

3. The anti-ligature device according to claim 1, wherein the electrical conductor target is resiliently biased away from the inductive proximity sensor via either foam or at least one spring.

4. The anti-ligature device according to claim 1, wherein the separation distance is adjustable by a user to thereby adjust a sensitivity level of the anti-ligature device.

5. The anti-ligature device according to claim 1, further comprising an alarm, wherein the alarm is activated upon the inductive proximity sensor sensing the separation distance.

6. The anti-ligature device according to claim 1, further comprising a compressible enclosure for attachment to an edge of a door leaf, wherein the inductive proximity sensor is attached to a first inner surface of the compressible enclosure, wherein the electrical conductor target is attached to a second inner surface of the compressible enclosure, such that the inductive proximity sensor opposes the electrical conductor target within the compressible enclosure.

7. The anti-ligature device according to claim 6, wherein the inductive proximity sensor is a first inductive proximity sensor and the electrical conductor target is a first electrical conductor target, the anti-ligature device further comprising a second inductive proximity sensor paired with a second electrical conductor target, wherein the second electrical conductor target is resiliently biased away from the second inductive proximity sensor, wherein the second electrical conductor target is moveable towards the second inductive proximity sensor in response to a force from a ligature on the anti- ligature device; wherein the first inductive proximity sensor and the first electrical conductor target are positioned at a first location along a length of the compressible enclosure, wherein the second inductive proximity sensor and the second electrical conductor target are positioned at a second location along the length of the compressible enclosure, wherein the first location is spaced from the second location by a distance that is at least approximately 25% the length of the compressible enclosure.

8. An anti-ligature device comprising: a first part having a bulbous protrusion; a second part having a channel; a deformable element disposed in the channel; and a plurality of proximity sensors, wherein the bulbous protrusion is inserted in the channel, wherein the deformable element biases the first part away from the second part, wherein the plurality of sensors is configured to detect a separation distance between the first part and the second part.

9. The anti-ligature device according to claim 8, wherein the proximity sensors are connected to the second part and the first part provides an inductive target for the proximity sensors.

10. The anti-ligature device according to claim 8, wherein the proximity sensors are connected to the first part and the second part provides an inductive target for the proximity sensors.

11. The anti-ligature device according to claim 8, wherein the deformable element comprises foam.

12. The anti-ligature device according to claim 8, wherein the plurality of proximity sensors is enclosed between the first part and the second part.

13. The anti-ligature device according to claim 8, wherein the channel provides a lip, wherein the lip prevents complete separation of the second part from the first part.

14. An anti-ligature device comprising: an elongated housing configured for attachment on a door leaf; a first pair of proximity sensor and electrical conductor target mounted in the elongated housing; a second pair of proximity sensor and electrical conductor target mounted in the elongated housing and spaced from the first pair of proximity sensor and electrical conductor target, wherein the first and second pairs of proximity sensor and electrical conductor target are mounted in the elongated housing such that a force from a ligature applied to the elongated housing actuates at least one of the first or second pairs of proximity sensor and electrical conductor target, wherein for each of the first and second pairs of proximity sensor and electrical conductor target: in a first, uncompressed position, the proximity sensor and the electrical conductor target are separated by a first distance in response to a resilient bias, in a second, compressed position, the proximity sensor and the electrical conductor target are separated by a second distance in response to application of the force from the ligature on the elongated housing, wherein the second distance is less than the first distance, wherein upon at least one of the first or second pairs of proximity sensor and electrical conductor target being separated by the second distance, the respective proximity sensor is actuated.

15. The anti-ligature device according to claim 14, wherein the first and second pairs of proximity sensor and electrical conductor target are arranged in the elongated housing, such that application of the force from the ligature on the elongated housing at any location along the elongated housing will actuate at least one of the proximity sensors of the first and second pairs of proximity sensor and electrical conductor target upon the respective proximity sensor and electrical conductor target being separated by the second distance.

16. The anti-ligature device according to claim 15, further comprising an alarm, wherein separation of at least one pair of proximity sensor and electrical conductor target by the second distance activates the alarm.

17. The anti-ligature device according to claim 16, wherein the second distance is adjustable by a user to thereby adjust a sensitivity level of the anti-ligature device.

18. The anti-ligature device according to claim 17, wherein (i) the electrical conductor target is moveable towards the proximity sensor in response to a force from a ligature on the electrical conductor target; (ii) the proximity sensor is moveable towards the electrical conductor target in response to a force from a ligature on the proximity sensor; or (iii) the electrical conductor target and the proximity sensor are moveable towards each other in response to a force from a ligature on either of the electrical conductor target or the proximity sensor.

19. The anti-ligature device according to claim 17, wherein the resilient bias is selected from the group consisting of: foam, and at least one spring.

20. The anti-ligature device according to claim 17, wherein each proximity sensor of the first and second pairs of proximity sensor and electrical conductor target is an inductive proximity sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of the present disclosure will now be described, by way of example only, with reference to the accompanying figures, in which:

(2) FIG. 1 shows a cross-sectional view of an anti-ligature device according to the present disclosure;

(3) FIG. 2 shows an exploded perspective view of the anti-ligature device of FIG. 1;

(4) FIG. 3 shows an assembled perspective view of the anti-ligature device of FIGS. 1 and 2;

(5) FIG. 4 shows the anti-ligature device of FIG. 1 in a first compressed state;

(6) FIG. 5 shows the anti-ligature device of FIG. 1 in a second compressed state;

(7) FIG. 6 shows an alarm system for use with the anti-ligature device of FIG. 1;

(8) FIGS. 7A-7C show door systems according to the present disclosure;

(9) FIG. 8 shows a perspective view of a further anti-ligature device, configured for use with a lock element;

(10) FIG. 9 shows a cross-sectional view of the anti-ligature device of FIG. 8, including an electromagnetic lock element; and

(11) FIG. 10 shows a cross-sectional view of a further anti-ligature device, configured for use with a mechanical lock bolt.

(12) Like reference numerals are used for like components throughout the drawings and detailed description.

DETAILED DESCRIPTION

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) 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.

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

(20) Each of the first part 104 and the second part 106 have a uniform cross-section. They are aluminium, and formed by aluminium extrusion.

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.

(26) 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.

(27) 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.

(28) 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.

(29) 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.

(30) 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.

(31) 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.

(32) 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.

(33) 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.