Ophthalmic Lens Mold Closure Velocity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing ophthalmic lenses, particularly contact lenses, face challenges in achieving rapid mold closure without introducing imperfections such as bubbles or incomplete lens formation due to improper velocity control during the mold closure process.
Innovation Solution
A method and apparatus that measure and control the force applied during mold closure, ensuring the mold halves are acceptably closed by maintaining a predetermined threshold force, and adjust velocities to prevent splashing or inadequate polymer distribution, using a force sensor and controller to manage the movement of mold halves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mold halves are brought together at a rapid velocity, then the productivity is improved, but bubbles are introduced into the lens-shaped cavity and polymerizable composition
Solution Approach 1:
The patent applies dynamics by transitioning from a static, single-velocity mold closure approach to a dynamic, multi-stage velocity control system. The mold halves are brought together in stages with different velocities: a first velocity for initial contact and a second, lower velocity for final closure. This dynamic velocity adjustment prevents bubble formation during the critical final closure stage while maintaining overall productivity through optimized stage transitions.
Solution Approach 2:
The patent implements periodic action by dividing the mold closure process into distinct temporal stages with different velocity characteristics. The closure is performed periodically in phases: an initial approach phase at higher velocity, followed by a final closure phase at controlled lower velocity. This periodic velocity modulation ensures complete mold closure while preventing harmful bubble introduction.
2Object-generated harmful factors
If the mold halves are moved at a slow velocity, then bubble formation is prevented, but the polymerizable composition spreads outwards on the male mold half resulting in inadequate volume
Solution Approach 1:
The patent uses dynamics to adjust velocity based on the closure stage. During the initial approach stage, a higher velocity is maintained to prevent polymerizable composition spread. In the final closure stage, velocity is reduced to prevent bubbles. This dynamic velocity control ensures both adequate composition volume retention and bubble prevention.
Solution Approach 2:
The patent applies preliminary action by performing the initial mold half approach at a controlled velocity that prevents composition spread before the final closure occurs. This preliminary positioning ensures the polymerizable composition remains in the correct volume and position, and subsequent final closure at lower velocity then prevents bubble formation without causing spread.
3Loss of time
If the mold halves are brought together rapidly, then the manufacturing time is reduced, but the lens diameter variability increases due to improper closure
Solution Approach 1:
The patent applies dynamics by implementing time-variant velocity control during mold closure. The velocity profile is dynamically adjusted: higher velocity during the approach phase to minimize time loss, and precisely controlled lower velocity during the final closure phase to ensure consistent lens diameter. This dynamic control achieves both rapid closure and manufacturing precision.
Solution Approach 2:
The patent uses periodic action by structuring the closure process into time-segregated stages with different velocity characteristics. The periodic velocity modulation ensures that the time-critical approach phase operates at high speed while the precision-critical final closure operates at controlled speed, thereby minimizing overall time loss while ensuring lens diameter consistency.
4Device complexity
If a single velocity is used for mold closure, then the device complexity is reduced, but the quality of lens formation deteriorates due to inability to prevent both splashing and spread
Solution Approach 1:
The patent applies dynamics by implementing a multi-velocity control system that adjusts velocity based on closure stage requirements. The controller dynamically selects between a first velocity for initial contact and a second velocity for final closure. This dynamic velocity adjustment prevents both polymerizable composition splashing (at higher velocity) and spread (at lower velocity), thereby improving lens formation quality without excessive complexity.
Solution Approach 2:
The patent uses periodic action by dividing the closure process into distinct velocity phases controlled in sequence. The controller periodically switches between different velocity settings: a first velocity regime for the approach phase and a second velocity regime for the final closure phase. This periodic velocity control ensures both splashing prevention and spread prevention, improving lens quality while maintaining manageable system complexity.
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
This approach reduces variability in lens diameters and defective lenses by ensuring accurate mold closure, maintaining a consistent contacting velocity and force to prevent bubble formation and ensure complete polymerization.
Implementation Method 1
measuring the force applied during the contacting step
Implementation Method 2
polymerizable composition for forming an ophthalmic lens
Data Source
Figure 1
AI summary
Apparatus and methods for manufacturing ophthalmic lenses by bringing together a pair of mold halves (2,5) to form a closed mold assembly, are described. The method includes measuring a force applied to bring the mold halves (2,5) together. The apparatus includes at least one force sensor (4) in operative communication with a single pair of mold halves (2,5), and a controller (10) for controlling a velocity of movement of a mold half (5) and for determining when a measured force or average measured force is greater than or equal to a predetermined threshold force.