Lever-Driven Plunger Mechanism for Consistent IOL Delivery
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Solution Overview
Problem
Existing intraocular lens (IOL) injectors face challenges in delivering IOLs with consistent actuation force and user control, often resulting in unpredictable IOL ejection velocities due to varying resistance during the advancement of the plunger, which can compromise the precision and safety of the surgical procedure.
Innovation Solution
A lever-driven plunger mechanism is introduced, featuring a rail and track system within the injector body to prevent plunger rotation, utilizing a rack and pinion mechanism to convert rotational force into axial movement, providing a consistent and controlled delivery of the IOL with a return spring for ergonomic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional plunger mechanism is used, then the device structure is simple, but the actuation force is inconsistent and user control is poor
Solution Approach 1:
The patent replaces the traditional direct mechanical plunger push mechanism with a rack and pinion gear system. The lever rotates the pinion gear, which engages with the rack on the plunger, converting rotational motion into precise linear motion. This mechanical substitution provides consistent actuation force and superior user control compared to simple direct pushing mechanisms.
Solution Approach 2:
The lever-driven rack and pinion mechanism enables periodic, controlled advancement of the plunger through discrete rotational increments. Each lever rotation produces a controlled linear displacement of the plunger via the gear engagement, allowing the user to advance the plunger in controlled stages rather than continuous motion, improving precision and control.
2Reliability
If friction between plunger and bore is not controlled, then the mechanism is simpler, but sudden IOL ejection may occur
Solution Approach 1:
The patent introduces a dynamic control system where the lever angle and rack-and-pinion engagement can be adjusted to control the rate of plunger advancement. The mechanism transitions from static friction-dominated motion to dynamically controlled motion, where the gear engagement regulates the force transmission and prevents sudden releases, ensuring safe and controlled IOL ejection.
Solution Approach 2:
The rack and pinion mechanism provides inherent feedback through gear engagement, where the user can feel the resistance and progression of plunger movement. This mechanical feedback allows the user to sense the force being applied and adjust the lever input accordingly, preventing sudden ejections and ensuring controlled delivery.
3Measurement precision
If the plunger can rotate freely, then the mechanism is simpler, but the IOL delivery precision is reduced
Solution Approach 1:
The patent employs asymmetric constraint through the rack and pinion geometry. The rack on the plunger has teeth that engage specifically with the pinion gear teeth in a predetermined asymmetric pattern, allowing rotation only in the direction that advances the plunger axially. This asymmetric engagement prevents backward rotation and ensures unidirectional, precise plunger movement for accurate IOL delivery.
Solution Approach 2:
The rack and pinion gear system acts as an intermediary between the lever rotation and plunger linear motion. This intermediate mechanism converts the rotational input into controlled linear output with precise positioning, eliminating direct rotation of the plunger body while maintaining precise control over axial movement for accurate IOL delivery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lever-driven plunger mechanism ensures a consistent actuation force, enhances user control and safety, and reduces the risk of sudden IOL ejection, providing a reliable and intuitive method for delivering IOLs during surgical procedures.
Implementation Method 1
A lever-driven plunger mechanism is introduced, featuring a rail and track system within the injector body to prevent plunger rotation, utilizing a rack and pinion mechanism to convert rotational force into axial movement
Implementation Method 2
providing a consistent and controlled delivery of the IOL with a return spring for ergonomic operation
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An IOL injector having injector body with a rail disposed on an interior wall of the injector body, a plunger movably coupled within the injector body and aligned within the bore; a track disposed within the plunger, the track adapted to be axially slidably coupled with the rail and adapted to prevent rotation of the plunger around the longitudinal axis and a lever-driven plunger mechanism with a lever having a first end comprising a handle accessible to a user and a second end rotatably coupled to the injector body; a rack having one or more teeth, the rack coupled to the lever.