Door Lever Pivot Plate Ligature Wedge Prevention
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Solution Overview
Problem
In psychiatric institutions, patients attempt suicide by hanging using cords or ligatures looped over door handles, and existing door lever designs fail to prevent ligatures from becoming wedged, allowing sufficient weight to be supported for successful suicides, despite previous designs attempting to prevent this by making ligatures slide off.
Innovation Solution
A door lever assembly with a mouse-like shape and integrated key lock cylinder, featuring a mounting plate with an aperture and a pivot plate that always underlies the aperture, eliminating gaps between the lever and door, ensuring ligatures cannot be wedged or securely attached, with a smooth surface preventing ligature attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional door lever with pivot and elongated handle is used, then the door can be easily opened, but ligatures can be looped around the lever shaft and handle, creating suicide risk
Solution Approach 1:
The lever is designed with a substantially U-shaped configuration where the handle portion curves upward and backward, forming a smooth continuous curve without sharp angles or flat surfaces. This curvature prevents ligatures from being looped or wedged, as the rounded surfaces cause ligatures to slide off rather than secure.
Solution Approach 2:
The lever is divided into distinct functional portions: a head portion that engages the spindle, a shaft portion that pivots, and a handle portion that curves upward and backward. This segmentation allows each portion to be optimized for its specific function while collectively preventing ligature engagement.
2Ease of operation
If the lever design includes gaps between the lever and door surface, then the lever can pivot freely, but ligatures can be wedged in the gap between the lever and door
Solution Approach 1:
A pivot plate is introduced as an intermediary component between the lever and the door. The pivot plate provides a smooth surface that allows the lever to pivot freely while preventing ligatures from being wedged between the lever and door surface, as the ligature would contact the smooth pivot plate surface instead.
Solution Approach 2:
The pivot function is extracted from the lever itself and placed into a separate pivot plate component. This separation allows the lever to focus on its primary function of being pushed to open the door, while the pivot plate handles the pivoting movement and prevents ligature wedging.
3Adaptability or versatility
If a key lock cylinder is mounted independently of the latch mechanism, then the lock can function independently, but the door lever design becomes more complex and may create additional ligature engagement points
Solution Approach 1:
The key lock cylinder is integrated into the head portion of the lever assembly, combining the locking function with the lever structure. The cylinder is positioned such that it shares the same mounting space and structural support as the latch mechanism, reducing overall complexity while maintaining independent lock functionality.
Data Source
AI summary
A door lever and mounting plate assembly attachable to a door and coupleable to a latch and spindle assembly in the door, includinga. a mounting plate including an aperture therein mountable on the door with the aperture axially aligned with the spindle,b. a door lever assembly comprising a handle part with a bottom surface, and a pivot plate, the handle part being coupleable to the spindle, and the pivot plate being fixed to the bottom surface of the handle and having an area greater than the area of the aperture and being situated closely adjacent and underlying the aperture, such that when the handle is pivoted the aperture is at all times fully underlied by at least parts of the pivot plate, andd. a keylock cylinder mounted in the handle part with a linkage to engage and control rotation of the spindle.