Optical Element Molding Pressure Feedback Control

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Solution Overview

Problem

Existing methods for shaping resins, such as those used in optical element production, face challenges in reducing takt time and improving surface accuracy, particularly for larger areas like wafer-level lenses, as they struggle to properly control molding conditions and respond to resin curing and shrinkage, leading to issues like sink marks and reduced productivity.

Innovation Solution

An optical element producing device and method that includes a driving section, pressure detecting section, and controlling section to detect negative pressure and apply a predetermined positive pressure to the mold when the resin reaches its gel point, allowing for precise control during the resin's soft solid state, enabling improved surface accuracy and productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If molding conditions are controlled by controlling position and/or speed of drive shaft, controlling time with timer, or controlling temperatures, then productivity can be improved by reducing takt time, but manufacturing precision deteriorates due to inability to properly extract molding conditions and follow resin curing and shrinkage

Engineering Contradiction:

Improvetakt timeVSAvoidsurface accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs feedback control by using a pressure sensor to detect pressure changes during resin curing. The control unit adjusts the drive shaft position and speed based on real-time pressure feedback, enabling the mold to dynamically follow resin shrinkage and maintain optimal molding conditions throughout the curing process, thereby preventing sink marks while maintaining high productivity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from fixed time-based or temperature-based control to dynamic pressure-based control. By monitoring pressure changes during curing and adjusting molding parameters accordingly, the system adapts to resin shrinkage and maintains manufacturing precision even at reduced takt times

Inventive Principle:

Principle #35Parameter changes

2Productivity

If weight control means is provided at a distance from the mold due to restrictions on curing means, then productivity can be improved, but responsivity deteriorates increasing the likelihood of improper molding

Engineering Contradiction:

ImproveresponsivityVSAvoidmolding accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces a pressure sensor as an intermediary between the mold and the control system. This intermediary device enables real-time detection of pressure changes during curing, allowing the control unit to adjust molding parameters dynamically without requiring the control means to be physically close to the mold, thus maintaining both productivity and molding accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

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 allows for reduced production time and enhanced surface accuracy of optical functional surfaces by applying pressure during the resin's soft solid state, preventing sink marks and ensuring high productivity even with increased heating rates.

Implementation Method 1

a pressure detecting section configured to detect pressure exerted from the resin to the mold

Methodology Applied

Scientific EffectPressure detection:

Implementation Method 2

the controlling section configured to control, by causing the driving section to start operating at a time when the pressure detecting section has detected a state in which the pressure exerted to the mold is a negative pressure, the position of the mold so that the pressure exerted to the mold is increased to a predetermined positive pressure and thereafter the positive pressure is maintained

Methodology Applied

Scientific EffectMechanical pressure application: Mechanical Force

Implementation Method 3

the time when the pressure exerted to the mold has reached a negative pressure is a point in time where the temperature of the resin has reached a gel point

Methodology Applied

Scientific EffectGel point phase transition: Gel

Implementation Method 4

curing the resin until the temperature of the resin reaches a gel point

Methodology Applied

Scientific EffectThermal curing: Heating

Implementation Method 5

the resin is in a soft solid state, and thus possible to easily extract setting conditions during the control even with a heating rate higher than conventional controlling methods

Methodology Applied

Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentUS9427919B2Optical element producing device, optical element producing method, controlling program, and recording medium

Publication Date: 2016.08.30 DAICEL CORP

AI summary

When an optical element is produced by sandwiching a resin between a pair of molds, the resin is cured while a mold is kept in contact with the resin until the temperature of the resin reaches a gel point. Throughout the process, a load cell monitors pressure exerted to the mold. After detection of a state in which the pressure exerted to the mold is a negative pressure, the resin is cured while the position of the mold is controlled so that the pressure exerted to the mold is increased to a predetermined positive pressure and thereafter the positive pressure is maintained.