Dental Chair Backrest Arc Prismatic Guide
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Solution Overview
Problem
Existing dental patient chairs face challenges in efficiently transitioning the backrest from an upright to a reclined position, particularly in achieving the Trendelenburg position, which requires complex and costly mechanisms, and results in the dentist needing to reposition during chair reclining, compromising ergonomics and space requirements.
Innovation Solution
A combined arc prismatic guide system dynamically connected to a four-bar linkage, allowing the backrest to pivot and translate along the chair's longitudinal axis, synchronized with seat movement, using a single actuator, and optionally incorporating a leg-rest mechanism for enhanced ergonomics and modularity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hydraulic system with four bar linkage is used to achieve Trendelenburg position, then the backrest can be reclined to the required position, but the mechanism becomes complex and costly
Solution Approach 1:
The patent combines the arc prismatic guide system with a four-bar linkage mechanism into an integrated assembly. The arc prismatic guide (102, 104) works in conjunction with the four-bar linkage (112, 114, 116, 118) to achieve both the reclining motion and longitudinal compensation movement. This merging allows the system to achieve Trendelenburg position while reducing overall complexity compared to separate hydraulic systems.
Solution Approach 2:
The arc prismatic guide system acts as an intermediary mechanism between the actuator and the backrest. It translates the linear motion of the actuator into the combined reclining and longitudinal compensation movements of the backrest, simplifying the overall control mechanism while achieving the required adaptability.
2Ease of operation
If the backrest reclines without longitudinal compensation, then the mechanism is simpler, but the patient's head relocates in space requiring the dentist to reposition
Solution Approach 1:
The patent implements dynamic longitudinal compensation movement where the backrest not only reclines but also moves longitudinally along the chair axis. The arc prismatic guide system enables this dynamic adjustment, ensuring the patient's head remains in a consistent position relative to the dentist's working area throughout the reclining process, improving ergonomics without requiring manual repositioning.
Solution Approach 2:
The kinematic coupling between the arc prismatic guide and the four-bar linkage creates an automatic feedback mechanism. As the backrest reclines, the longitudinal compensation movement is automatically activated to maintain proper head positioning, eliminating the need for separate control systems or manual adjustments by the dentist.
3Ease of manufacture
If a single actuator is used to control both backrest reclining and seat movement, then the system is more cost-effective, but the coordination of movements must be precise
Solution Approach 1:
The patent merges the control functions of backrest reclining and seat movement into a single actuator (108). This actuator simultaneously drives both the arc prismatic guide system and the four-bar linkage, reducing the number of components and manufacturing costs while maintaining precise coordination through the inherent kinematic relationships of the combined mechanism.
Solution Approach 2:
The kinematic design ensures that the movements of the backrest and seat are equipotential, meaning they occur in a coordinated manner that maintains proper spatial relationships throughout the range of motion. The arc prismatic guide and four-bar linkage are designed to work together so that both components move in unison, eliminating the need for complex control systems.
4Ease of operation
If the dentist is positioned behind patient's head in alignment with chair longitudinal axis, then the working position is optimal, but no room is left for the dentist when reclining the chair
Solution Approach 1:
The patent implements dynamic space management through longitudinal compensation movement. As the backrest reclines, the entire assembly (backrest and seat) moves longitudinally along the chair axis, dynamically adjusting the spatial configuration to maintain adequate working space for the dentist while preserving the optimal working position alignment with the chair's longitudinal axis.
Solution Approach 2:
The invention adds a longitudinal dimension to the backrest movement, not just reclining in one direction but also translating along the chair's longitudinal axis. This dimensional change creates additional space for the dentist while maintaining the optimal working position, effectively solving the space constraint problem through spatial reconfiguration.
Data Source
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AI summary
Patient chair (1) preferably for dentistry, comprising a lifting group comprising a base (4) on which a pantograph arm (5) is hinged, which is hinged on and shifts a turret (14), a moving group for relatively moving said seat (3), comprising an under seat (15) which is in its turn hinged to said turret (14) through two piston rods (6 and 7), wherein the reclining of the backrest (2) occurs according to an arc of a circle, said chair (1) having moreover a longitudinal compensation mechanism. According to the invention, said reclining and compensation movements are obtained thanks to the combination of an arc prismatic guide system for backrest reclining, dynamically combined with a four-bar linkage for moving the under seat (15) and seat (3), said four-bar linkage comprising said two piston rods (6 and 7), said turret (14) and an under seat (15) which links said seat (3) to said turret (14) and said movements are obtained through an actuator only.